NanoScan v2 Installation and Operation Manual No. 50302-001 Rev G v2.6 2/26/2018 Page 1 ™ Installation And Operation Manual For NanoScan2, NanoScan2s, & NanoScan2sB
TM
Installation And Operation Manual
For NanoScan2, NanoScan2s, & NanoScan2sB
For Sales, Service or Technical Support
Phone: (435) 753-3729 Fax: (435) 753-5231 Service Email
service@us.ophiropt.com Sales Email
sales@us.ophiropt.com Ophir-Spiricon, LLC
3050 North 300 West N. Logan, Utah 84341 ©2018 Ophir-Spiricon, LLC
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 1
Notice
All Copyrights to the product and any accompanying manual(s) are reserved by Ophir-Spiricon, LLC Ophir-Spiricon, LLC reserves the right to make improvements to the product described in this manual at any time and without prior notice. While every precaution has been taken in the preparation of this manual, the publisher and author assume no responsibility for errors, omissions, or any loss of data because of said errors or omissions. Personal computer hardware and component manufacturers, along with operating system providers constantly revise their products and software upon which this product is dependent. While Ophir-Spiricon, LLC endeavors to maintain maximum compatibility with a wide variety of personal computer configurations, Ophir-Spiricon, LLC makes no guarantee that any one brand or model of personal computer will be compatible with any or all of the features contained in this application, either now or in the future. Obtain the latest version of this manual at http://www.ophiropt.com/lasermeasurement-instruments/beam-profilers/services/manuals NanoScan2, NanoScan2s, and NanoScan2sB are the physical hardware scanheads and are referred to collectively as NanoScan2. NanoScan v2 is the software that operates a NanoScan2.
Trademarks
NanoScanTM, NanoScan2TM, NanoScan2sTM, NanoScan2sBTM, and NanoScan v2TM are trademarks of Ophir-Spiricon, LLC.
Windows is a registered trademark of Microsoft Corporation. LabVIEW is a registered trademark of National Instruments.
Licenses
NanoScan v2 utilizes the OpenSceneGraph ver 3.01 library, Copyright 2002 by Robert Osfield, distributed under the Lesser Gnu Public License. More information, including OpenSceneGraph source code can be found online at the following locations: http://www.openscenegraph.org http://www.gnu.org/licenses/lgpl.html
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Table of Contents
TABLE OF CONTENTS..........................................................................................................3 IMPORTANT WARNING!...............................................................................................8 1 INTRODUCTION ...........................................................................................................9 1.1 About This Manual....................................................................................................9 1.2 Product Description ................................................................................................10 1.3 Operation and Use..................................................................................................10 1.4 NanoScan v2 Software Overview ...........................................................................11
1.4.1 NanoScan v2 Beam Profiling GUI......................................................................11 1.4.1.1 Scan Control and Profile Acquisition..................................................................11 1.4.1.2 Data Display and Visualizations.........................................................................11 1.4.1.3 Measured Beam Results....................................................................................11 1.4.1.4 Data Export........................................................................................................12 1.4.2 ActiveX Automation Server ................................................................................12 1.5 Protecting Your Investment.....................................................................................12 2 SYSTEM INSPECTION ...............................................................................................14 2.1 Inspection ...............................................................................................................14 2.2 Packing Lists...........................................................................................................14 2.2.1 NanoScan2 Laser Beam Profiling System .........................................................14 3 NANOSCAN2 SYSTEM SETUP .................................................................................15 3.1 Recommended PC Requirements ..........................................................................15 3.2 NanoScan2 Installation ...........................................................................................15 3.3 Installing the Software.............................................................................................16 3.3.1 Software Installation...........................................................................................16 3.4 Installing the Scanhead...........................................................................................22 3.4.1 USB 2.0 Connection ..........................................................................................22 3.4.2 Launching NanoScan v2....................................................................................22 3.5 Uninstalling the NanoScan v2 Software..................................................................23 4 BEAM PROFILING WITH NANOSCAN2 ....................................................................25 4.1 International Standard ISO11146-1,-2,-3................................................................25 4.1.1 Beam Width Analysis Methods ..........................................................................25 4.1.1.1 Moving-Slit Analysis...........................................................................................26
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4.1.1.2 Moving Knife-Edge Analysis ..............................................................................26 4.1.1.3 Second Moment Method Analysis......................................................................27 4.1.2 Comparison of Beam Profiling Methods.............................................................27 4.1.3 Moving Slit Techniques......................................................................................28 4.1.4 NanoScan2 Dual-Axis Scanhead.......................................................................31 4.1.5 Pulsed Beam Profiling........................................................................................32 4.1.5.1 Pulsed Mode: When to Use? .............................................................................32 4.1.5.2 Accuracy Requirement: minimum of 15 pulses per scan ...................................33 4.1.5.3 Calculating the Minimum Beam Diameter per Laser Pulse Repetition Rate ......33 4.1.5.4 Software Measurement of Laser Repetition Rate ..............................................36 4.2 Care of NanoScan2 Slits.........................................................................................36 4.2.1 Slit Damage Threshold ......................................................................................36 4.2.2 Pulsed Laser Damage Considerations...............................................................38 4.2.2.1 PWM Lasers ......................................................................................................38 4.2.2.2 Q-Switched Lasers.............................................................................................39 4.2.2.3 Pico- and Femtosecond Lasers .........................................................................39 4.2.3 Scanhead Operating Space...............................................................................41 4.2.4 Instrument Calibration........................................................................................43 4.3 NanoScan2 System Description .............................................................................43 4.3.1 Scanhead...........................................................................................................43 4.3.2 Scanhead Mechanicals......................................................................................43 4.3.2.1 Front Cap with Entrance Aperture and C-mount ................................................44 4.3.2.2 Photo Detector...................................................................................................44 4.3.2.3 Air Slits...............................................................................................................45 4.3.2.4 Power Meter.......................................................................................................46 4.3.2.5 Rotation Mount...................................................................................................46 4.4 Measurement Considerations and Guidelines ........................................................47 4.4.1 Use the Appropriate Scanhead ..........................................................................47 4.4.2 Slit Width Selection Criteria................................................................................47 4.4.3 Scanhead Positioning and Alignment ................................................................48 4.4.3.1 The Measurement Plane....................................................................................49 4.4.3.2 Entrance Aperture Mechanical Center ...............................................................49 4.4.3.3 User Defined Origin (0,0) Position .....................................................................49
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4.4.3.4 Angular Alignment and Elliptical Beams ............................................................50 4.4.4 Profile Setup and Acquisition .............................................................................51 4.4.4.1 Scan Rate ..........................................................................................................51 4.4.4.2 Spatial Sampling Resolution ..............................................................................52 4.4.4.3 Amplifier Gain ....................................................................................................53 4.4.4.4 Filter Cutoff Frequency ......................................................................................53 4.4.4.5 Regions of Interest (ROIs) .................................................................................53 4.4.4.6 Profile Frame Averaging ....................................................................................54 4.4.4.7 Coordinate System ............................................................................................54 4.4.5 Scanning Slit Obliquity Correction......................................................................54 4.4.6 Back Reflections and Laser Oscillation..............................................................54 4.4.7 Beam Divergence and Angle of Incidence .........................................................55 4.4.7.1 Divergence/NA Measurements ..........................................................................56 4.4.8 Stray Background Light......................................................................................59 4.4.9 Beam Attenuation ..............................................................................................59 4.4.10 Slit Convolution and Small Beams .....................................................................59 4.4.11 Near-Field Profiling ............................................................................................62 4.4.12 Power Measurements ........................................................................................63 4.4.13 Multiple Beam Measurement .............................................................................63 4.5 NanoScan2 USB 2.0 Hardware Specifications .......................................................63 4.5.1 NanoScan2 Scanhead Models...........................................................................64 4.5.1.1 Silicon Detectors (190-950nm)...........................................................................64 4.5.1.2 Germanium Detectors (700-1800nm) ................................................................64 4.5.1.3 Pyroelectric Detectors (0.2-20m)......................................................64 4.5.2 Mechanical Dimensions .....................................................................................65 4.5.3 Operating Space Charts ....................................................................................65 5 NANOSCAN V2 SOFTWARE .....................................................................................66 5.1 Nomenclature Change............................................................................................66 5.2 Displays ..................................................................................................................67 5.2.1 Terminology .......................................................................................................67 5.2.2 Primary Dock Window and Dock Handles..........................................................68 5.2.3 Dock Handle Cloning .........................................................................................69
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5.2.4 Auto Hide ...........................................................................................................70 5.2.5 Keyboard Shortcuts ...........................................................................................71 5.3 Controls ..................................................................................................................72 5.3.1 Quick Access Toolbar ........................................................................................72 5.3.2 File Menu ...........................................................................................................73 5.3.3 Status Bar ..........................................................................................................74 5.3.4 Ribbon Bars .......................................................................................................74 5.3.4.1 Regions of Interest (ROI) ...................................................................................75 5.3.4.2 Automatic ROI Mode..........................................................................................75 5.3.4.3 Manual ROI Mode..............................................................................................76 5.3.4.4 ROI Mode ..........................................................................................................78 5.3.5 Source Ribbon ...................................................................................................78 5.3.6 Profiles Ribbon...................................................................................................82 5.3.6.1 Profile Views ......................................................................................................85 5.3.7 2D/3D Ribbon ....................................................................................................85 5.3.7.1 2D and 3D Views ...............................................................................................86 5.3.8 Pointing Ribbon..................................................................................................87 5.3.8.1 Pointing View .....................................................................................................89 5.3.9 Capture Ribbon..................................................................................................90 5.3.10 Computations Ribbon ........................................................................................94 5.3.11 Power Ribbon ....................................................................................................99 5.3.12 Charts Ribbon..................................................................................................101 5.3.12.1 Charts View......................................................................................................101 5.3.12.2 Chart Background Context Menu.....................................................................103 5.3.12.3 Point or Series Context Menu ..........................................................................104 5.3.12.4 Axis Context Menu...........................................................................................104 5.3.13 Logging Ribbon................................................................................................104 5.3.14 M2 Ribbon ........................................................................................................106
5.3.15 M2 Wizard
.......................................................................................... 108
5.3.15.1 Measuring M2...................................................................................................110
5.3.15.2 Lens Selection and the Expected Rayleigh Length..........................................110
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5.3.15.3 Alignment.........................................................................................................111 5.3.15.4 Dual Axis Measurements w/Astigmatism .........................................................113 5.4 Results Window ....................................................................................................114 5.4.1 Notes View.......................................................................................................114 5.4.2 Message Window.............................................................................................115 5.5 NanoScan2 Status Codes.....................................................................................115 6 FREQUENTLY ASKED QUESTIONS.......................................................................118 APPENDIX A SCANHEAD SPECIFICATIONS ...............................................................123 Si/3.5/1.8m ....................................................................................................................... 123 Si/9/5m ............................................................................................................................. 123 Si/9/25m ........................................................................................................................... 123 Ge/3.5/1.8m .....................................................................................................................124 Ge/9/5m ...........................................................................................................................124 Ge/9/25m .........................................................................................................................124 Pyro/9/5m......................................................................................................................... 125 Pyro/9/25m....................................................................................................................... 125 APPENDIX B MECHANICAL DIMENSIONS ...................................................................126 APPENDIX C OPERATING SPACE CHARTS ................................................................128 Silicon/3.5mm/1.8m .........................................................................................................129 Silicon/9mm/5m ...............................................................................................................129 Silicon/9mm/25µm .............................................................................................................130 Germanium/3.5mm/1.8m .................................................................................................132 Germanium/9mm/5m .......................................................................................................132 Germanium/9mm/25µm ..................................................................................................... 133 Pyroelectric/9mm/5m .......................................................................................................134 Pyroelectric/9mm/25m .....................................................................................................135 INDEX .................................................................................................................................136
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IMPORTANT WARNING!
Do NOT expose NanoScan2 to ANY laser beam when the drum is not spinning!
Scanhead damage thresholds drop below specifications when the drum is not spinning, increasing the risk of damage. The laser beam's incident in the aperture may cause damage to the slits and detector if the drum is not spinning. The drum only spins when the power is ON and the software is running. The slit substrates are thin membranes which can be damaged. Use of a beam dump is recommended when the drum is not spinning. During long term tests, configure the PC Power Management to never go off, and turn off automatic updates. These cause the computer to reboot closing NanoScan v2, and stopping the drum.
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1 Introduction
Congratulations on the purchase of your new NanoScan2 Laser Beam Profiling System with NanoScan v2 software, the latest in the Ophir-Spiricon line of Photon scanning-slit beam-profiling instruments. Ophir-Spiricon's philosophy is to produce instruments that both end users and original equipment manufacturers can depend on to provide the utmost accuracy and precision in beam profile measurement and characterization. For over 20 years Photon's scanning slit technology has been the de facto industry standard for optical beam profiling, providing accurate and repeatable measures of beam width and beam position to the µm range. It has been recognized worldwide as the benchmark for all other beam profiling instruments. The NanoScan v2 software enhances the user experience with a number of new features and a modernized GUI layout makes it easy to learn and use.
1.1 About This Manual
This manual is designed to help you setup and operate your NanoScan2 system. Chapter 1 includes: a NanoScan2 system overview, a brief explanation of the NanoScan2 operation, an overview of the NanoScan v2 Analysis Software, and some practical suggestions on proper care and regular calibration of your new instrument. Chapter 2 includes the system's packing list, and unpacking and inspection instructions. Chapter 3 shows step-by-step system setup instructions for installing and configuring the hardware and software. Chapter 4 describes the theory of operation of the NanoScan2 scanhead and principles of laser beam profiling measurement. Chapter 5 describes the features and operation of the NanoScan v2 software and graphical user interface (GUI). Appendix A includes the Scanhead Specifications. Appendix B shows the Mechanical Dimensions of the scanheads. Appendix C shows safe region operating charts of the various NanoScan2 models.
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1.2 Product Description
NanoScan2 is a PC-based instrument for the measurement and analysis of optical beam spatial profiles in accordance with ISO standards. Beam profiles are measured in accordance with the International Standard ISO 11146. All scanheads fitted with a power meter can measure power in accordance with ISO 13694.
The system is comprised of a USB 2.0 NanoScan2 scanhead and NanoScan v2 software. An optional automation feature includes an ActiveX automation server.
NanoScan2 uses moving slits, an ISO Standard scanning aperture technique. Measurement is possible for beam sizes from microns to centimeters and at beam powers from microwatts to kilowatts, without attenuation. Detector options (silicon, germanium, and pyroelectric technologies) allow measurement at wavelengths from the ultraviolet to the far infrared. NanoScan2 can simultaneously measure multiple beams. An integrated power meter is installed with silicon and germanium detectors.
A typical NanoScan2 system includes the following:
NanoScan2 scanhead with rotation mount and protective cap
NanoScan v2 Beam Profiling and Analysis Software for Microsoft Windows 7 or Windows 10
NanoScan v2 Installation and Operation Manual
1.3 Operation and Use
The basic system operation is as follows: The scanhead "senses" incident laser beams directed into the scanhead entrance aperture. The digital output signal is proportional to the spatial beam profile, and the total power in the beam. The NanoScan v2 software controls the scanhead scan rate, signal amplification, signal filtering, and the spatial sampling rate. The acquired digital profile data is transferred into the computer memory for data analysis and display.
NanoScan2 is useful in any photonic application that requires precise and accurate measurement of beam size and position. NanoScan2 can be operated either as a standalone instrument or integrated into automated test and measurement systems. As a standalone instrument, it is useful in research and development applications to configure, test, and verify designs, and also useful in manufacturing and production for real-time optical adjustments. As an automated system, it finds applications in tools for final test and quality assurance of optical systems. In either case, NanoScan2 provides considerable savings in time and improves productivity and throughput.
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1.4 NanoScan v2 Software Overview
NanoScan v2 Beam Profiling GUI
NanoScan v2 beam profiling software is an intuitive standalone application that provides scanhead control plus profile display and data analysis. The software 1.4.i1s written specifically for MS Windows platforms, and is compatible with Windows 7, and Windows 10 32- or 64-bit operating systems. This manual does not address the basics of MS Windows operations. It assumes you are already familiar with the Windows operating environment.
Note: Ophir-Spiricon no longer verifies or certifies operation with Windows XP.
Scan Control and Profile Acquisition
The EEPROM in the scanhead contains the programmed characteristics unique 1.4.1t.o1 each scanhead model. It also contains power calibration information once a
calibration is made using the NanoScan v2 software.
Available scan rates are 1.25, 2.5, 5, 10, and 20Hz. The spatial sampling interval is determined by the user programmable sampling clock. As an example, spatial sampling can be set as fine as 0.0427m at a 10Hz scan rate. The available amplifier gains are scanhead dependent and are given in the gain table. The filter frequency can be adjusted over a range from 2kHz to 190kHz. The filter is used to improve the signal-to-noise ratio in the acquired profile data within the limits of beam diameter measurement requirements. The spatial sampling interval, the gain, the filter setting, and the scan rate can be set to optimize profile acquisition and measurement.
Profiles are acquired with 16-bit digitization and analyzed in real-time to the maximum scanhead scan rate of 20Hz.
1.4.1.2
Data Display and Visualizations
The data display screens show X and Y profiles for up to 16 regions of interest (ROIs), the position plots of the beams, and 2D and 3D renderings of the beam. 1.4.1Q.3uantitative displays of user-selected results are displayed in real time.
Measured Beam Results
Results measured include:
Beam Width at various clip levels Centroid Position Peak Position Ellipticity 1D Gaussian Fit Beam Divergence Beam Separation
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Pointing Stability ROI Power Total Power Peak (in digitizer counts) Pulsed Laser Repetition Rate
Data Export
Data can be exported to spreadsheets, math and statistical analysis programs, and process/instrumentation control programs. This is done by logging to files 1.4.1o.4r COM ports, or shared using ActiveX Automation (OLE2).
ActiveX Automation Server
1.4.Tm2hoedealust.omThaetionPhfeoatotunreNisanaovSacilaabnlevf2or
PRO (Professional) licensed scanhead analysis software includes an ActiveX
Automation server interface for integrating the NanoScan2 system into custom
automated test and measurement applications. A Developer Guide for using the
ActiveX Automation server as well as example applications with sample code
for LabVIEW and MS Excel written in Visual Basic are provided in the
Automation folder (C:\Program Files (x86)\Photon\NanoScan v2.0\Automation).
1.5 Protecting Your Investment
ALWAYS plug your PC computer into a surge protection outlet strip. Be sure the electrical ground is carried through all connections. A power surge or electrical shock can cause serious damage to your NanoScan2. This type of damage is not covered by warranty.
To provide accurate and precise measurements, the slits must be free of any debris. Operation in clean environments helps to ensure this. Ophir-Spiricon recommends that the plastic protection dust cap be installed whenever the scanhead is not in use.
NEVER touch the scanning slits with hands or objects! The slits are thin fragile membranes that can be easily damaged. Damaged slits can seriously compromise measurement accuracy.
Excessive beam power and power density from high power lasers and sharply focused beams may also damage the apertures. Refer to the Slit Damage Threshold (section 4.2.1), Scanhead Operating Space (section 4.2.3), and the Operating Space Charts (Appendix C). Verify visually that the scanhead drum is spinning before you direct the laser beam into the scanhead.
Ophir-Spiricon provides a limited warranty on parts and labor for 12 months. Ophir-Spiricon does not warrant electrical damage caused by failing to safeguard the unit with a surge protector or for ESD related damage. Damage to slits or the detector is not warrantied for any reason. Please refer to OphirSpiricon's Warranty Policy for complete details.
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Ophir-Spiricon strongly recommends an annual factory calibration and evaluation of the scanhead to maintain your investment and to ensure the product is measuring within specification. Ophir-Spiricon offers several Calibration and Preventive Maintenance options. Regular calibration means:
Measurement accuracy meets specifications Near 100% UP TIME Internal ISO requirements are met
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2 System Inspection
2.1 Inspection
Your NanoScan2 laser beam profiling System has been tested extensively at Ophir-Spiricon to ensure proper operation. All components were inspected and carefully packaged for shipment. Upon receipt of your NanoScan2, please do the following:
Check the contents of your shipment against the packing slip
attached to the shipping box. Please note any discrepancy.
Check the condition of the shipping container. Please note any
damage to the container.
If the container appears damaged, check the system
components for any signs of damage. If damage is observed, immediately report the damaged container to the shipping company. Ophir-Spiricon does not warrant damage that occurs as a result of shipment.
2.2 Packing Lists
2.2.1
NanoScan2 Laser Beam Profiling System
1. NanoScan2 scanhead with Rotation Mount and protective dust cap 2. 2-meter USB 2.0 A to mini-B cable 3. NanoScan v2 Acquisition and Analysis Software DVD 4. NanoScan2 Damage Information Pamphlet 5. Calibration Certificate 6. NanoScan2 Declaration of Conformance 7. Accessories
a. USB 3.0 Hub b. USB Connector Strain Relief with #2-56 screws c. 1/4"-20 set screw d. M6 set screw 8. Case
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3 NanoScan2 System Setup
Setup of the NanoScan2 system involves configuration of the system hardware and installation of the system software.
3.1 Recommended PC Requirements
To take full advantage of your NanoScan2 system's capabilities, the following minimum PC requirements are recommended:
A dual core processor CPU, 2GHz or better Microsoft Windows 7 or Windows 10, 32- or 64-bit Operating
System1 2GB of RAM2 1-USB 2.0 port available At least 250MB of free HDD space 1400 x 900 display resolution or better Add-in PCI/PCI-Express graphics card w/hardware
accelerator DVD-ROM drive Microsoft compatible pointing device (e.g., mouse, trackball,
etc.)
1 A business/professional version of windows is recommended. The NanoScan v2 software has not been tested with home versions of Windows. NanoScan v2 is no longer tested on Windows XP 32-bit operating systems. 2 The computer memory (RAM) will affect the performance of the software in the Data Recorder. Refer to section 5.3.9 for more information on the Data Recorder.
3.2 NanoScan2 Installation
There are two steps to installing the NanoScan2 1. Install the Software 2. Connect the Scanhead
The software should be installed before the hardware otherwise you will have to dismiss many "Failed to Install" notifications.
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3.3 Installing the Software
For first time installation proceed to Step 1 and follow the instructions. Note: The NanoScan2 model scanheads are not compatible with the legacy NanoScan v1.47 or earlier releases. NanoScan2 scanheads must be used with NanoScan v2 release 2.2 or later software. Upgrading to the new NanoScan v2 software does not require that the previous v1.47 be uninstalled before installing v2. The two versions can both reside on a single PC platform and can operate independent of each other. Meaning, older style NanoScan scanheads may continue to be used with the legacy NanoScan software, however two instances of the software cannot connect to the same head.
Software Installation
3.3.T1here may be minor differences in what is written here depending on the version of windows and the PC's auto launch settings. The procedure described here reflects Windows 7. Note: This software must be installed with Administrator Privileges. Step 1. Insert the supplied DVD. If the installer doesn't start automatically, navigate to the CD drive and double-click on the file named Amplayer.exe The following window appears:
Select Software Install.
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Step 2. Select Next from the next window:
Step 3. After a short delay the following window appears:
The Readme notes are displayed and may be examined for useful change and errata information. Click Next.
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Step 4. The following window appears:
Read through the license agreement...
Step 5. Check I accept... if you agree to abide by the license terms and conditions. Then click either Cancel or Next as appropriate.
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If you clicked Next the following window appears:
Step 6. Click Install. The installation process starts as shown below:
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While the above window is displayed the following Device Driver Installation Wizard appears:
Step 7. Click Next The following window appears:
Step 8. Click Install. The Device Driver Installation Wizard will install the appropriate driver for the current Windows operating system.
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After a short delay the following window appears:
Step 9. Click Finish. The above window closes. When The NanoScan2 setup window completes the installation, the following window appears:
Step 10. Click Finish. This completes the installation process. Remove the supplied CD and store it in a safe location.
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The NanoScan v2 shortcut icon
appears on the desktop.
3.4 Installing the Scanhead
USB 2.0 Connection
The NanoScan2 scanhead is supplied with a protective dust cover. Do not remove this cover until you have the scanhead securely mounted and are ready 3.4.t1o expose the scanhead to laser radiation. Refer to later sections of this manual for proper techniques on how to safely perform laser measurements.
To Connect the NanoScan2, do the following:
1. Connect the supplied USB2 cable's mini-B connector to the NanoScan2 scanhead.
2. Connect the USB2 cable's A connector to an available USB2 port on the computer.
3. The Windows Plug-and-Play feature should indicate that the NanoScan2's driver has been successfully connected to the scanhead. This could take a few seconds to cycle.
3.4.2 Launching NanoScan v2
The NanoScan2 scanhead is factory licensed for either STD or PRO (Standard or Professional) operation with the NanoScan v2 software. (Standard licensed products can be upgraded to Professional by means of a purchased upgrade License Key.)
With the scanhead connected to the PC:
1. Double click the NanoScan v2 icon application.
to launch the
2. The NanoScan v2 application opens with the Source ribbon displayed and the head connected.
3. Click Start to begin data collection. 4. Without a laser beam present the software only displays background
noise.
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3.5 Uninstalling the NanoScan v2 Software
The uninstall process is slightly different if both the older legacy NanoScan application and the newer NanoScan v2 is installed on the same PC. To remove NanoScan v2, do the following:
1. Close NanoScan v2 2. Unplug all USB2 scanheads from the PC 3. Click Start and select All Programs 4. Open Photon, NanoScan v2.x 5. Click on Uninstall NanoScan v2 6. Observe the following prompt and click Yes
7. The following window opens:
Note that this next window opens behind the one shown above in step 7. Click on it to bring it to the front.
If you only have NanoScan v2 installed and are removing it, click Yes. If you have the legacy NanoScan application installed and also plan to remove it click Yes. If you have the legacy NanoScan application installed and want to retain its operation after NanoScan v2 is removed click No.
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Note: All saved *.nsd, *nsdx, *.txt and *.log files will not be removed. 8. When all of the windows have closed, the uninstall process to remove NanoScan v2 is complete. 9. If you are also planning to remove the legacy NanoScan application proceed to the next section.
To remove a copy of the legacy NanoScan software, do the following: 1. Click the Start menu 2. Select Control Panel. 3. Open Programs and Features 4. Select NanoScan from the software list. 5. Click Uninstall. 6. If a User Account Control dialog box appears stating an unidentified program wants access to your computer, select Allow to continue uninstalling the software.
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4 Beam Profiling with NanoScan2
NanoScan2 creates spatial beam irradiance profiles using scanning slit techniques. The profiles are analyzed to provide beam width measurements. They can also be analyzed to derive a number of other beam characterization parameters defined in ISO/DIN 13694, including beam centroid position, peak position, ellipticity, goodness of fit, roughness of fit, and more.
With NanoScan2, beam profile measurement process is straight forward. Simply position the scanhead in the beam path and the system does the rest.
Consideration of the wavelength, beam size, and beam power ensure a particular scanhead is appropriate for a given application.
For accurate beam profiling with the NanoScan2 it is useful to understand the ISO/DIN standard and the measurement principles involved. Also, for any beam measurement, there are specific guidelines and restrictions that should be followed to obtain the most accurate and repeatable results.
4.1 International Standard ISO11146-1,-2,-3
These standards govern profile measurements and analysis using scanning apertures, variable apertures, and 2D detector arrays. Profiles obtained using these methods differ fundamentally. Each requires specific analyses to determine beam characterization parameters. Most important of which is the beam width or diameter. Profile measurements using various scanning aperture techniques were considered, including the moving-slit, moving knife-edge, 4.1.v1ariable-aperture, and scanning-pinhole.
Beam Width Analysis Methods
The four preferred methods for the measurement of beam widths were determined to be:
1. Moving-slit, ISO11146-3 (section 4.4) 2. Moving knife-edge, ISO11146-3 (section 4.3) 3. Variable aperture, ISO11146-3 (section 4.2) 4. Direct 2D Second-moment, ISO11146 (all)
The first three methods involve mechanical moving devices. The fourth method typically involves 2D focal plane arrays that employ various imaging technologies.
In theory, all of the methods give exactly the same results for the 1/e² widths of a perfect TEM00 Gaussian beam. For all other beam profiles, different values
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are obtained, although for typical beams the values are usually within 10% of each other. Method 1 provides superior spatial measurement accuracy over a wide range of beam widths. Method 2 is similar to method 1 but yields no beam profile detail. Method 3 gives no spatial detail and is not appropriate for elliptical beams. Method 4 is the only method that displays the actual 2D structure of the beam profile. The standard shows how to correlate beams measured by different methods if one has measured the propagation factor M2. The standard also suggests you state the measurement method when reporting a beam width in order to keep confusion to a minimum.
Moving-Slit Analysis 4.1.1M.1oving-Slit Beam Width Analysis, also known as Clip-Level Beam Width
Analysis, is illustrated in Figure 4.1. The observed peak is the 100% level and the measurement baseline is the 0% level. The beam width per the ISO standards is defined as the spatial width at the 13.5% (1/e²) level (for a TEM00 beam). It is also common in practice to use the beam size at other %-irradiance levels, or "clip" levels, such as, for example, the 50%, or full-width-half-max (FWHM) beam width, and is designated as dslit.
Figure 4.1 Moving-Slit Beam Width Analysis
One nice feature of the moving-slit method is that the scanned profile can also 4.1.1b.2e used to directly calculate the second moment beam widths of non- TEM00
beams. This is not possible with the knife-edge or variable aperture methods. Moving Knife-Edge Analysis
Knife-edge profiles are one-dimensional cumulative spatial power distributions in the scan direction. The knife-edge width, designated dke, is defined as the distance between the 16% and 84% levels of the profile.
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Second Moment Method Analysis
Over time, the second moment method has become the industry standard for beam width definition since it is the measurement that follows laser beam propagation theory. However, it is not always the measurement preferred by 4.1.1s.3ome users with differing laser applications. The second moment method defines the beam width as four times the square root of the second moment of the beam's spatial profile. This width, designated D4, is equivalent to the 1/e² slit and knife-edge method widths for a TEM00 Gaussian beam where M2 = 1.
The second-moment integral for the x coordinate is:
E(x,y,z)(x x )2dxdy
2 x
(z)
x2
E(x,y,z)dxdy
The corresponding beam diameter is D4 = 4x
4.1.2 Comparison of Beam Profiling Methods
During the development of the ISO standards, the committee compared what was measured by the different methods for several laser modes. The second moment method was designated as the reference method because it provides the beam profile width that is always consistent with the laser beam propagation theory.
Table 4.1 is a guide from the standard to illustrate how different each method can be. This is important if one writes a specification for a component and the vendor and the user want to correlate measurements.
To avoid confusion, the standard suggests the measurement method be stated along with the reported beam width. It is also recommended to report the standard deviation of the measurement.
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Table 4.1 Comparison of Beam Width Measurement Methods
Method
Width Measured @ % PWR
Multiplier* What Measured
Mode
TEM00 TEM01* TEM10 TEM11* TEM20 TEM21* Uniform Density Circle Uniform Density Square
Encircled Energy/ Variable Aperture 86.5% Total
1.0 D at 1/e
% Beam Width Error 0 -6.3 -5.6 -6.3 -5.5 -6.0 -7.5
Moving Slit
13.5% Highest Peak
Moving Knife-Edge
10% to 90% Maximum Value
Moving Pinhole/ Detector 1D
Array
13.5% Outer Peak
1.0 D at 1/e²
% Beam Width Error
0 -0.7 -3.9 -1.0 -3.9 -1.4 -1.0
1.5606 D at 1/e² 1.5606
% Beam Width Error 0 -1.7 7.8 9.3 11.5 12.1 7.2
1.0 D at 1/e²
% Beam Width Error 0 6.1 10.3 8.5 8.6 7.4 0
Second Moment Moving Slit
Second Moment Calculation
4.0 D at 1/e²
4.0
% Beam Width Error 0 0 0 0 0 0 0
-7.1
0
24.8
0
0
4.1.3 Moving Slit Techniques
NanoScan2 employs the moving-slit method. The various methods are illustrated in Figure 4.2. With all methods, the scanning aperture is interposed between the incident beam and a large-area detector. The detector output signal is proportional to the beam irradiance profile as the aperture scans through the beam. The scan can be made in discrete steps or in a continuous fashion. With discrete steps, the spatial sampling interval is the step dimension, whereas with continuous scanning, the scan velocity and signal sampling frequency determine the spatial sampling.
The profiles obtained using these methods differ fundamentally. The pinhole aperture provides a localized measurement through a particular segment of the beam, whereas the slit aperture integrates the beam along the slit direction, and the knife-edge integrates over the area of the beam. Thus, the profile information obtained using these techniques are dependent on the beam irradiance distribution.
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Pinhole
Detector
Signal
Slit
Laser Beam
Knife Edge
Scan Direction
Figure 4.2 Illustration of scanning aperture beam profiling techniques
With the slit and knife-edge techniques, a measure of the width of the entire beam can be obtained in only one scan. However, for the pinhole technique, the scan must either be positioned properly in the beam or a full raster scan of the beam must be made to obtain the correct beam width value.
With slit and knife-edge apertures, the acquired profiles are along the apparent motion of the aperture, i.e., in the direction perpendicular to the aperture. The NanoScan2 configuration uses two slits mounted on a rotating drum oriented at 90 to each other, thus two orthogonal profiles are measured for each scan. This technique is illustrated in Figure 4.3 and Figure 4.4. Note that the measurement is not truly planar because the aperture scan path is circular, but when the drum circumference is much larger than the beam dimensions, the errors introduced are negligible. To improve accuracy, mathematical corrections for the geometry can be made.
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Figure 4.3 Measurement of the major and minor axes of an elliptical beam using the moving-slit method with 2 orthogonal slits.
Figure 4.4 Scanning slit instrument for laser beam profiling. A slit mounted to a motorized drum scans repetitively through the beam. An optical encoder provides
motion control feedback and ensures accurate beam sampling.
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NanoScan2 Dual-Axis Scanhead
Figure 4.5 illustrates the operation of a dual-axis scanhead. The slits are typically closely matched in width and oriented at ±45° (90° to each other) with respect to the drum rotation direction. In the figure, the drum is orientated at 45° to the 4.1.i4ncident beam, and consequently the apparent motions of the slits are in the horizontal (0°) and vertical (90°) directions, respectively. In the illustration, an elliptical beam, oriented with the major axis horizontal and the minor axis vertical, is incident on the scanhead. Slit 1 (shown on the cover of the scanhead as X) scans along the vertical axis of the beam and slit 2 (shown on the cover of the scanhead as Y) scans along the horizontal axis. The measured beam profiles for each aperture are shown.
Figure 4.5 Illustration of NanoScan2 profiling with dual orthogonal slits
NanoScan2 comes with a rotation mount that allows easy adjustment for orientation through any azimuth of the incident beam. This is useful for measurement of elliptical beams with arbitrary orientation (see section 4.4.3.4 for additional information).
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Pulsed Beam Profiling
NanoScan2 can also profile pulsed laser beams with repetition rates in the 1kHz range and above. To enable the measurement of these pulsed lasers, the NanoScan2 profiler incorporates a "peak connect" algorithm. NanoScan2 is 4.1.i5deal for measuring Q-switched plus pico- and femtosecond pulsed lasers, as well as lasers operating in pulse width modulation (PWM) mode. The measurement of all these types of pulsed lasers is discussed below.
When operating in pulsed mode, the peaks of the individual pulses in the profile are connected to form a smooth profile. All parameter computations are performed on the resulting smooth profile. Measurement accuracy depends on the Pulse-to-Pulse Repeatability, on Profile Averaging, and on the number of pulses in the profile during a single scan, which in turn depends on the laser repetition rate and beam diameter.
There are two modes of operation for pulsed lasers; Short for pulsed widths <~10ns, and Long for pulse widths >~10ns.
To provide ~2% measurement accuracy in Short mode, the input signal/gain combination must limit the digitized pulse amplitude to <4096 counts in order to avoid amplifier nonlinearity. This adjustment is performed automatically by the NanoScan v2 software. Should the operator override the automatic Gain control and exceed 4096 counts, the following message will be displayed in the Message Window warning the user to decrease the gain.
In Long pulse mode, the Full-Scale amplitude is limited to 32768 counts in order to avoid amplifier nonlinearity and subsequent measurement error. As in the previous Short pulse mode, the Gain can be set manually. In this case, if the Gain is set so the amplitude is greater than 32768 counts, the above warning 4.1.5m.1essage will be displayed.
Pulsed Mode: When to Use?
The pulsed mode of operation is recommended for all pulsed beams unless they fall into the category of "quasi-CW". Results can also vary dependent on signal-to-noise ratio and pulse-to-pulse repeatability. Use of Frame Averaging and Rolling Frame Averaging can improve measured pulsed beam profiles.
For quasi-CW pulsed beam profiles a better result may be obtained using the CW mode of operation. A quasi-CW beam is one that exhibits a profile with overlapped pulses. This occurs for larger spots at higher laser repetition rates and longer pulse widths or duty cycle and slower scanhead scan rates.
To make a visual determination if a beam profile is quasi-CW, turn off the Filter Frequency auto Track and manually set the filter to 190kHz. Manually narrow the Region of Interest (ROI) to observe the individual pulses. If they overlap then the beam profile is quasi-CW. As an example, a 1mm 1/e² diameter beam with pulse rate of 100kHz appears quasi CW at 10Hz scanhead scan rate.
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In these cases, it is recommended to experiment with the different measurement modes in order to obtain the most consistent results.
Accuracy Requirement: minimum of 15 pulses per scan As shown in Table 4.2, a minimum of 15 pulses per single scan is required to obtain the specified accuracy. This condition depends on the laser spot size 4.1.5a.2nd the scanhead scan rate. If there are not enough pulses present in a single scan (<15), the software computes the corresponding head scan rate and displays a message in the Message Window (see below) recommending a lower head speed.
If the computed head scan rate for the current conditions is below 1.25Hz, a message (see below) displays in the Message Window warning the user about operating the NanoScan2 system outside the ±2% accuracy specification.
4.1.5.3
Calculating the Minimum Beam Diameter per Laser Pulse Repetition Rate
Table 4.2 gives a list of calculated minimum beam diameters at a given pulse
rate for a desired number of pulses per profile. The more pulses per profile, the more accurate the measurement is likely to be. Due to the 45o angle of the slits
to the direction of rotation, the actual speed of the slits is the drum speed
divided by the square root of two.
v
2
f
N Dmin
where:
v= drum velocity in m per msec
f = pulse frequency in kHz
N = pulses per profile
Dmin= minimum beam diameter in m
The NanoScan2 pulsed operation can operate at any scan rate, however it is recommended that the scan rate be 1.25 or 2.5Hz unless the laser repetition rate is above 50kHz.
The peak connect algorithm finds the highest peak pulse, then, using the frequency value entered by the operator, it finds the other peaks and connects them to generate a smooth beam profile. It is important that the exact pulse rate be entered into pulse acquisition parameters. NanoScan v2 provides for the
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measurement of all pulsed beams with all scanheads and detectors. Beams with an average power that was too low to be measured with the pyroelectric detector can now be profiled using silicon or germanium scanheads. At high laser repetition rates, it may be better to operate the NanoScan2 in CW mode and let the auto-filter smooth the beam. When this is preferable is dependent on the individual laser's pulse performance. If inconsistent results are seen with a high rep rate laser (e.g., >80kHz), it would be advisable to try the measurement both ways.
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Table 4.2
Minimum Beam Size per Pulse Rate
Minimum Beam Size/Pulse Rate
Scan Rate (Hz)
1.25
2.50
5.00
10.00 20.00
slit speed (µm/msec) Data Points per Profile
Pulse Rate (kHz)
0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 50 100 150
116. 63
233.25
466.50
15
15
15
933.01 1866.01
15
15
Minimum Beam diameter in m
3499 1749 875 583 437 350 292 250 219 194 175 159 146 135 125 117 109 103
97 92 87 83 80 76 73 70 35 17 12
6998 3499 1749 1166 875 700 583 500 437 389 350 318 292 269 250 233 219 206 194 184 175 167 159 152 146 140
70 35 23
N/A 6998 3499 2333 1749 1400 1166 1000 875 778 700 636 583 538 500 467 437 412 389 368 350 333 318 304 292 280 140
70 47
N/A N/A 6998 4665 3499 2799 2333 1999 1749 1555 1400 1272 1166 1077 1000 933 875 823 778 737 700 666 636 608 583 560 280 140 93
N/A N/A N/A N/A 6998 5598 4665 3999 3499 3110 2799 2545 2333 2153 1999 1866 1749 1646 1555 1473 1400 1333 1272 1217 1166 1120 560 280 187
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Software Measurement of Laser Repetition Rate
The software connects the pulse peaks based on the user input Laser Pulse Rate. If the actual and input frequencies are significantly different, the resulting profiles may be jagged (not smooth). When selected in software, the actual 4.1.5L.4aser Pulse Rate is measured and displayed as a check for a possible incorrectly entered Laser Pulse Rate value. When jagged profiles appear, try using the measured rate value and the beam profiles may become smoother.
The measured Laser Pulse Rate current value, mean, and standard deviation information could be important for your application.
4.2 Care of NanoScan2 Slits
The air slit aperture substrates are very thin and extremely fragile. Any physical contact is likely to damage them. For example, fiber tips placed too close to the aperture can easily damage a slit. Treat the slits with care; because of their fragility, never touch them with anything!
Debris such as dust particles can lodge in the very fine openings of the slits and obstruct the passage of the incident beam. This can compromise instrument performance, resulting in inconsistent measurements. Therefore, when the system is not in use, it is recommended that the protective plastic cap be used to cover the scanhead entrance aperture and avoid possible contamination.
If inconsistent performance is observed and contamination by debris is suspected, a clean jet of compressed gas may solve the problem, but excessive pressure may also damage the apertures. Do not under any circumstances attempt to clean the apertures with solvents! If aperture contamination is suspected, it is recommended that the unit be returned to Ophir-Spiricon for 4.2.s1lit inspection, cleaning or replacement, and recalibration.
Slit Damage Threshold
Damage thresholds reported in Table 4.3 below are determined under specific test conditions and should not be taken as absolute. Ophir-Spiricon does not warrant damage to slit material and detectors due to damage from high power lasers. Users of high-power lasers must exercise caution when measuring their laser beams with the NanoScan2.
Scanhead slits are made from a proprietary metallic alloy. The slit material is often blackened to reduce reflectivity. Because of possible slit damage, Ophir-Spiricon performed damage threshold tests on various NanoScan2 slit materials to establish general use guidelines for prevention of damage. If you are concerned and still not sure, Ophir-Spiricon can provide slit material that you can use as a test before applying your beam to the scanhead.
Blackened and unblackened slits with, 1.8m, 5m, and 25m nominal slit widths were tested. Tests were made at laser wavelengths of 532nm, 1.06m,
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and 10.6m. Damage thresholds are defined here to be the average laser irradiance at which the onset of visual damage occurs. The average irradiance is defined as the average power divided by the beam area at the 1/e² beam diameter.
All tests were performed under normal NanoScan2 operating conditions with the slits moving. Damage to the slit material can occur at much lower power levels if the laser beam is directed into the slit while they are stationary. The tests were performed at laser power levels <3 watts for short time exposures on the order of 5 minutes. The damage thresholds that were determined are therefore applicable only for short time exposures at these power levels. For high power lasers and long exposure times, the damage thresholds are likely to decrease due to excessive heating of the slit material and/or possible ablation that does not manifest itself as visual damage in short term exposure tests. These effects have not yet been quantified, so users are advised to exercise extreme caution when attempting to measure high power beams for long time intervals. Long exposures may heat the entire NanoScan2 and cause other failures.
Note that for the case of blackened slit materials, the onset of visual damage occurs when the black coating begins to ablate. This type of damage does not affect the integrity of the slit but only the reflectivity of the base metal. Slit integrity is only compromised at the higher laser irradiance associated with damage to unblackened metals. This damage takes the form of wrinkling or creasing of the metal fabric due to thermal stress, and scoring due to melting of the metallic alloy. At higher irradiance and longer exposure times, the metal fabric can be cut. Recommended upper limits of average laser irradiance, based on the results of the visual damage threshold tests for short time exposure (~5 minutes) at power levels less than 3 watts, are summarized below.
Table 4.3
Recommended maximum average laser irradiance incident on metallic
alloy NanoScan2 slits for short time exposures <5 minutes.
SLIT TYPE
NOMINAL SLIT WIDTH
VISUAL DAMAGE THRESHOLD (W/cm2)
(m)
532nm 1.06m 10.6m
UNBLACKENED
1.8
3 x 105
1 X 106
N/A*
UNBLACKENED
5-25
4 X 105 1.2 x 106 3.5 x 106
BLACKENED
1.8
1 x 104
3 x 104
N/A*
BLACKENED
5-25
1 x 104
3 x 104
N/A*
* Not Applicable
The values of average irradiance listed in the above table should be used as a guideline to determine if your operating conditions may cause damage to the slit material in your scanhead. These guidelines are for short time exposure (<5 minutes) at power levels <3W. For long term exposures (>5 minutes) at higher
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power levels the damage thresholds may be significantly reduced. Exercise Caution!
Ophir-Spiricon does not warrant damage to slit material and detectors due to damage from high power lasers.
Pulsed Laser Damage Considerations
Pulse width modulated (PWM) sources donot increase the peak power density in your beam over CW (continuous wave, 100% on-time) operation values. 4.2.2 CAUTION: Q-Switched, picosecond, and femtosecond lasers will increase peak irradiance above CW and may increase it enough to damage the slits and/or detectors. Be sure to read these next three sections carefully to protect your investment and call or email if you have questions.
PWM Lasers
4.2.2M.1any lasers, especially CO2 lasers, use pulse width modulation (PWM) to control the average power level of the laser. Often, duty cycles are very high, sometimes >90%. In this case, the beam operates as if it was CW, and many operators do not even realize that the laser is pulsing. However, when attempting to measure a PWM laser with a scanning slit profiler, it usually must be treated as a pulsed laser source.
To use the pulsed mode of the NanoScan2, the laser's pulse rate must be at least ~1kHz, and the combination of the rate and beam size must provide a sufficient number of pulses across the beam to generate a meaningful profile. Eight to ten pulses are a reasonable minimum, but 15 are preferred to get better accuracy. PWM lasers usually operate around 10kHz.
The relationship of the beam size and rate is a fairly simple mathematical model. The NanoScan2 drum speed is software controlled from 1.25Hz to 20Hz. At the 1.25Hz scan rate, the slits travel at around 116.6mm per second or 116.6m per millisecond. At a 10kHz laser repetition rate, a 175m beam would have 15 pulses during the time the slit was traversing it. This would provide enough data to generate a meaningful profile. A smaller beam would require a faster pulse rate; a larger one could perhaps run at a lower repetition rate. For example, a 1.0mm beam could be measured with a pulse rate as low as 2kHz and still provide a profile.
Table 4.2 displays the minimum beam sizes and pulse frequencies for the hubs at each of the set scan speeds. It is recommended that the 1.25Hz scan rate be used for pulsed beams. However, if the beam sizes are large enough, or the pulse rates fast enough, the measurement can be sped up by increasing the scan rate to 2.5Hz or above. The NanoScan v2 software generates a warning if the scan rate is set too high for the pulse rate or beam size. This warning algorithm is based on having at least 15 pulses across the beam to provide a minimum of ±2% accuracy.
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Use the CW Operating Space Chart (beam power versus beam diameter) for your scanhead when measuring PWM sources. Your maximum saturation power is still the CW (100% on-time) maximum for your laser even as the duty cycle decreases.
Q-Switched Lasers
Another type of pulsed laser, operating in the kHz pulse rate regime, is the QSwitched laser. These lasers use Q-switching to increase, rather than 4.2.2d.2ecrease, their effective power. By concentrating the laser power into a short pulse, the peak power of each pulse increases while maintaining a low average power. In order to measure these lasers the same mathematical relationship of pulse rate to beam diameter applies, but there is an additional complication; the peak power of the pulses may exceed the damage thresholds of the NanoScan2 even though the average power remains within the operating space. CW beams are measured as power (P) in watts; pulsed beams as energy (E) in joules. Therefore it is necessary to understand the beam's energy (Epulse) in order to determine whether the unattenuated beam can be directly measured with the NanoScan2.
Epulse
Pavg flaser
Therefore a beam with an average power of 300 Watts with a pulse rate of 8kHz has energy as follows:
E pulse
Pavg flaser
300W 8 103 Hz
37.5mJ
The power density per pulse is also a function of the pulse duration . This is
also important in understanding the potential damage to the profiler. Taking the above example, if the pulse duration is 1ms, then:
4.2.2.3
Ppulse
Epulse
37.5mJ 1103 s
37.5 W
Pico- and Femtosecond Lasers
When the pulse duration of the laser gets very short, such as with pico- and femtosecond lasers, the peak power of the pulses can become very large. This creates some added complications when determining the type of scanhead that can safely measure these beams. In addition to the average power of the beam, which is used to determine the proper operating space of a given scanhead, it is important to know the energy density of the pulses. The energy density must be below the damage threshold for the slit material, and the average power must fall within the operating space of the scanhead for it to be possible to measure
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the beam without additional attenuation. To determine the energy density, first use the following formula for the Epulse:
Epulse
Pavg flaser
Most pico- and femtosecond lasers have both a high repetition rate and a fairly low average power. They use the short pulse duration to amplify the effective power of the laser beam. A typical laser that one might encounter would have an average power of 1.0 watt and a repetition rate of 80kHz. For this example, the Epulse would be:
E pulse
Pavg flaser
1W 80000sec1
12.5J
Using this value, calculate the energy density for a given beam diameter by the following formula. Note that the energy density is presented as J/cm2; therefore
the beam area needs to be converted to cm in the formula. Unless the beam is
wildly different from round, it is easiest to consider that the area is that of a
circle:
E density
E pulse r2
For a 100m beam at the 12.5J:
Edensity
12.5J 100m 0.0001 2
0.16
J cm2
160 mJ cm2
2
Once the energy density is calculated, it can be compared to the damage
threshold for the slit type and the wavelength range for the slit material. The standard blackened slit material can only handle 10mJ/cm2 before the
blackening starts to ablate. For this reason, scanheads intended for use with
these pico- and femtosecond lasers should have the reflective slits, regardless
of the detector type or the average power of the lasers. The wavelength of the
laser also influences the energy density that the slit material can withstand. For the standard nickel alloy slits, the maximum energy density is 600mJ/cm2 for the range of 190nm to 400nm. For 400nm and above, the value is 1.0J/cm2. For the high power copper slits, the values are 2.5J/cm2 from 700nm to 3m wavelength and 5J/cm2 above 3m. Copper slits are not recommended for use
below 700nm, however in some experiments we have seen better performance
in the UV (@355nm) from copper slits. This may be attributable to the better
heat dissipation of the copper material or the fact that the copper slit material is
thicker than the nickel alloy.
Figure 4.6 below is a graph that can be used in lieu of the above calculations. For the above case the 12.5J energy at 100m would be below the 600mJ
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damage line, but would certainly be well above the damage level for blackened slits.
Figure 4.6 Damage Threshold Curves
These estimates of damage threshold are primarily based on the relative reflectivity of the slit material. There are many other factors that may influence interaction of the laser beam and the slit material. At some level of power and pulse duration, this interaction may become non-linear. In addition, surface finish, roughness, contamination, tarnish, or oxidation can also affect the reflectivity of the materials. For this reason, these damage threshold values can only serve as a guideline, not an absolute guarantee. Use caution when 4.2.m3 easuring any new or unfamiliar laser system.
Scanhead Operating Space
The Operating Space Chart maps the useful measurement range for a given NanoScan2 scanhead in terms of beam power and beam diameter for TEM00 Gaussian beams. The detector responsivity, the entrance aperture diameter, the slit width, and the amplifier gain and signal-to-noise performance determine the operating space. A sample operating space for a scanhead with a silicon detector and 1.8m slits is shown in Figure 4.7. The abscissa of the chart is the 1/e² beam diameter in microns and the ordinate is the incident beam power in watts. Operating Space Charts for standard scanheads are in Appendix C.
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Figure 4.7 Operating Space for a NanoScan2 with silicon detector with aperture of 3.5mm and 1.8m slits
The boundaries of the operating space define the power density of laser beams that can be measured directly. The boundary at the left side is based on acceptable errors due to slit convolution. The boundary is set at a beam diameter corresponding to four times the slit width, at which point a 5% systematic convolution error in the raw profile is introduced. This error can be corrected per the diameter correction charts in section 4.4.10. The lower boundary defines the lowest power density that can be detected and measured accurately with a minimum number of signal counts at a signal-to-noise ratio of 10. The upper boundary is the limit of beam power above which the detector saturates. The right boundary is defined by the dimension of the entrance aperture, which determines the largest beam profile and diameter that can be measured. For a TEM00 Gaussian beam the 1/e2 diameter needs to be 1/2 the aperture diameter to measure and see the entire profile out to the tails. Similarly for a Flat-top distribution the 1/e2 diameter needs to be ~95% of the aperture diameter. To obtain any given clip level diameter for any beam (but not the full profile) ~95% of the aperture is useable.
Note: The axes of the Operating Space Chart are logarithmic.
For pulsed operation in Short Pulse mode, the signal amplitude is limited to ~10% of the maximum. This effectively sets a limit indicated in the operating space by a blue line at one decade below the upper boundary.
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Two other important lines on the chart are the damage thresholds. These are the lines toward the top of the chart area. The lower yellow line describes the power density where the blackening begins to be burned off the slits. The upper red line describes the level at which the slits are physically damaged due to ablation and can be cut. Operation above the yellow line is not advised for Si and Ge scanheads with blackened slits; operation above the red line will result in immediate permanent damage to the NanoScan2.
Note: Damage to scanheads from a high laser power is not covered by the Ophir-Spiricon warranty.
Instrument Calibration
Ophir-Spiricon recommends an annual calibration on all its beam profilers, most 4.2.e4specially the scanning-slit profilers, including NanoScan2. Ophir-Spiricon
profilers are precision instruments with moving parts. Over time, miniscule movements may occur which could affect measurement accuracy. Many instruments are used in production in manufacturing plants, where dust and other particles could possibly enter the scanning-slit aperture. We recommend regular calibration to ensure that the precision is maintained and any tiny particles are cleaned. Most companies that must comply with ISO 9001 or other standards insist that instruments receive an annual calibration, cleaning, and preventive maintenance. Ophir-Spiricon sends a calibration/preventive maintenance reminder on the anniversary of the delivery of your NanoScan2.
4.3 NanoScan2 System Description
4.3.1
Scanhead
The NanoScan2 is a self-contained scanning slit system. The scanhead employs a high performance digital signal processor that controls all head electronic and electro-mechanical functions including communications via its USB2 port.
The scan rate, spatial sampling interval, signal amplifier gain, filter settings, and DC offset are controlled by the scanheads internal firmware. An EEPROM in the scanhead contains all of the scanheads model specific parameters. This information includes head ID, available scan rates, amplifier gain tables, slit and aperture information, power window, and calibration information. 4.3.T2he firmware in the scanhead is upgradable to accommodate new features that may be developed in the future.
Scanhead Mechanicals
The mechanical configuration of the main components of the scanhead is shown in Figure 4.8. These include the scan drum with optical position encoder and motor, scan slits, a power aperture, a stationary large-area photo detector,
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and a rotation mount with a knurled locking screw. The scanhead electronics are not shown.
Figure 4.8
Scanhead Components
4.3.2.1 Front Cap with Entrance Aperture and C-mount
The front cap of the scanhead has a circular entrance aperture that is slightly smaller in diameter than the photo detector. The entrance aperture dimension limits the size of the beam that can be measured. Standard NanoScan2 scanheads have nominal entrance aperture diameters of 3.5mm and/or 9mm depending on the detector type.
The scribe lines on the front cap define the 2 orthogonal scan axes. The housing tube edge is the reference surface for the scanhead measurement datum plane.
A new C-mount threaded front cap feature has been added to the NanoScan2
scanhead. This feature simplifies the addition of many Ophir-Spiricon optical
accessories that were previously useful on CCD camera systems. The C-mount
4.3.2rci.ln2ogsecroampepsrosatcahndtoardth,ebuatpecratunreb.eTrheemmovoeudntiifngthescureswers
needs the space for a can also be employed
for attachment of a user built custom accessory.
Photo Detector
NanoScan2 heads come with silicon, germanium, or pyroelectric detectors. These detectors provide for measurement at wavelengths from the ultraviolet (UV) at 190nm to the far infrared (FIR) at 100m.
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The nominal wavelength responsivity curves for the silicon, germanium, and
pyroelectric detectors used in the NanoScan2 are shown in Figure 4.9. The
response for the pyroelectric detector is flat for wavelengths from 190nm to >20µm, with a nominal value of 3.8×10-6 A/W.
Figure 4.9 Typical Photo Detector Response for silicon, germanium, and pyroelectric detectors
4.3.2.3
Air Slits
NanoScan2 scanheads come standard with matched pairs of "air" slits of 1.8m, 5m, or 25m widths. Air slits comprise a clear opening in a metallic substrate of a thin metallic membrane.
The edge quality of the slit is important to obtain the most accurate profiles, especially for the measurements of very small beams in the range of tens of microns. An example of exceptional edge quality of the slits in terms of "straightness" is shown in Figure 4.10. The figure shows photographs from a scanning electron microscope (SEM) for standard 1.8m and 5m slits.
a.
b. Figure 4.10 SEM images for a) 1.8m, and b) 5m slits.
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NanoScan2 scanheads with silicon or germanium detectors come standard with "blackened" slits to reduce light reflected back into the laser and thus prevent laser cavity oscillations. Blackening is achieved by chemical etching. As a result of the etching process, the slit edges become slightly rougher.
Power Meter The power meter provides for measurement of total beam power. It requires the user to manually calibrate the power based on an external power meter 4.3.2re.4ading. Separate manual calibrations are required for each change in wavelength. When using a pyroelectric sensor separate manual calibrations are also required for each head rotation speed. The user generated calibrations are storable for reuse in the scanhead's EEPROM. Up to 256 calibrations can be stored. In silicon and germanium scanheads an attenuator placed behind the power aperture reduces the incident beam power to avoid detector saturation. Power aperture attenuators are a metallized quartz glass substrate, useable for power levels up to 200mW. The metallized quartz glass filter has a neutral response with wavelength. They tolerate higher input laser power and show little change of attenuation with angle of incidence.
4.3.2.5 Rotation Mount A new rotation mount comes standard with all NanoScan2 scanheads. The rotation mount allows smooth continuous adjustment of the angular position of the scanhead over a range of 190°. The rotation mount sleeve fits over the scanhead and permits attachment via either a 1/4-20 or M6 thread. After mounting, the scanhead can be rotated within the sleeve by loosening and sliding the knurled knob retaining screw. A new quick mount stand has been incorporated for vertical beam sampling. It can be activated by removal of the knurled locking screw, sliding the rotation ring back to the next thread location, and reinserting the locking screw. Figure 4.11 depicts the scanhead in both mounting configurations. Note that the mounting stand is less stable if loosely mounted onto a surface without the addition of some type of clamping device.
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Figure 4.11 Rotation Mount in horizontal and vertical directions
4.4 Measurement Considerations and Guidelines
In any beam profiling application there are many considerations, as well as guidelines and restrictions to follow in order to obtain the most accurate and repeatable results.
4.4.1 Use the Appropriate Scanhead
The operating space of a particular scanhead accommodates measurements without attenuation and without profile corrections over a range of nominally three decades in beam size and seven decades in beam power at a given wavelength. This space extends even further if profile corrections, profile averaging, or beam attenuation is allowed. Due to the wide operating space of each scanhead, a single scanhead can often be used in a number of different applications. For example, characterizing different laser beams over the visible range to determine M2 or the focused spot size through an optical system. However, sometimes the measurement requirements of the applications do not 4.4.o2verlap, such as measurements of NIR beams at 1550nm and UV beams. Such diverse applications may demand the use of different scanhead types.
Slit Width Selection Criteria
The slit width determines the power measurement range and the diameter of the smallest spot that can be measured using the slit method without mathematical correction due to slit convolution. The practical lower limit for slit width dimension is 1.8m.
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The power measurement range is inversely proportional to the slit width; beam diameter size is directly proportional to the slit width. These two considerations must be balanced when selecting the measurement slit size, and sometimes a compromise is required. Slit convolution introduces a systematic error in measured spatial beam widths. The severity of the error depends on the beam profile. This is discussed in detail in section 4.4.10 for TEM00 Gaussian beams. For such beams, the systematic error in the measured beam diameter increases with the ratio of the slit width and the measured width. When this ratio exceeds approximately 0.4, the error becomes greater than 10%. It is also possible to deconvolve the slit width from the spatial profile mathematically. As a guideline, it is recommended to use a slit width that is no larger than onefourth the diameter of the smallest beam to be measured. In this case, the systematic error in the measured 1/e² beam diameter is 5%, which in many cases is an acceptable error. Mathematical deconvolution to correct the error is only required if greater accuracy is needed. As an example, if the beam diameter is 4m, and the slit width is 1m, the measured value will be 4.2m. If the beam is known to be Gaussian, then the actual value can be obtained by deconvolving the width of the slit. If the power levels are very low and near the limits of operation, it may be necessary to use the widest slit available, regardless of the magnitude of the error introduced by the slit convolution effect.
4.4.3 Scanhead Positioning and Alignment
The NanoScan2 scanhead has features to aid in the positioning and alignments required for accurate beam measurements. These are illustrated in Figure 4.12. The front cap has scribe lines at the entrance aperture that represent the orthogonal scan axes.
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Rotation mount
10° increment scribe lines
Knurled knob-- loosen locking screw to rotate
Orthogonal axis scribe lines
Measurement data plane
Front cap
Figure 4.12 Features of the NanoScan2 Scanhead
The Measurement Plane 4.4.3T.h1e measurement plane in the scanhead is at the surface of the slit materials.
This plane is accurately controlled and is mechanically referenced to the rim of the housing tube. Refer to Appendix B for specific model information regarding Scanhead Dimensions and measurement plane location.
4.4.3.2 Entrance Aperture Mechanical Center
The mechanical center of the entrance aperture [the (0,0) position] for each scanhead is determined at the factory during calibration and is assigned as the "default" center position. The accuracy of this alignment is specified at ±0.003" 4.4.3(..03762mm). This reference position is available through software.
User Defined Origin Position
It is also possible to redefine arbitrary origin (0,0) positions for the scanhead entrance aperture in the software. There are several ways that this can be done. One method is to train the software with a good, functional component or assembly. Make your setup and then record the X and Y coordinates. Load these coordinates as the new origin position into the software. If you remove the head from your setup, it is unlikely you can maintain the origin location to a micron level and recalibration becomes necessary.
Another method to establish origin positions is to translate the scanhead across a focused beam and view the back reflection at the laser source. Do this for each orthogonal axis; record the two positions. Load these coordinates as the new origin position into the software.
One more method is to translate the scanhead in the X and Y directions and observe the profiles as the beam hits the entrance aperture edges (you will see the
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beam clipped by the edge). Note the two edge position numbers for each X and Y and use the midpoints for the origin location.
Angular Alignment and Elliptical Beams
The rotation mount in Figure 4.13 can be used to align the direction of scan of the slits to the laser beams axial orientation. This allows accurate measurement 4.4.3o.f4 elliptical beams' major and minor beam widths. The rotation mount on the scanhead can maintain axial location to ±0.01mm. (If greater accuracy is required, the rotation sleeve should be replaced by a custom designed stage).
Rotation Mount
Loosen knob to rotate, Gently press knob toward beam, and then tighten knob.
Figure 4.13 NanoScan2 Rotation Mount
Carefully align the scanhead and rotation mount so it is perpendicular to the beam axis. Secure all mounting apparatus so all bolts or screws are very tight. Otherwise, it may move as the scanhead rotates. When rotating the scanhead, from 0° to 45° for example:
1. Loosen the knurled knob locking screw. 2. Put slight pressure on the side of the knurled knob in the direction of the
focused beam to eliminate play in the slot while rotating the scanhead to maintain the position of the scan plane. 3. Maintain the slight pressure against the knob while tightening it at the new scanhead position. Repeatable axial results, at least ±100m or better along the beam axis, have been produced using this technique. For the most accurate alignment, it is best to rotate the scanhead while observing the X and Y profile displays in the software and looking for the point at which the minor axis is narrowest in one axis and the major axis is widest in the other.
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Measurement of an elliptical beam is illustrated in Figure 4.14. In the figure, the slit is misaligned by the angle of ellipticity of the beam. The measured width is equal to the projection along the scan direction of the line defined by the point at which the slit first enters the beam and the point at which it exits. The entry and exit points are shown, as well as the actual beam width and the measured beam width, which is significantly in error. To obtain accurate results, a good rule-of-thumb is the requirement that the misalignment angle be less than 1/10 the angle of ellipticity.
Slit oriented at angle of ellipticity
"Entry" point
Measured width
"Exit" point
Figure 4.14
Actual beam width Error due to scan misalignment when measuring elliptical beams
The figure shows a condition where the ellipticity is of the order of 0.1, and a corresponding angle of ~5.7°, so to get a good measure the scan axis must be adjusted to <~0.57°. This range of adjustment is easily achieved using the NanoScan2 rotation mount. The optimal scan angle is set by rotating the scanhead to minimize the reported minor axis width while observing the beam profile.
However, if the beam ellipticity is of the order of 0.01 or greater, which is the case for many applications, the ellipticity angle becomes 0.57° or less, and the alignment requirement is of the order of 0.057° or less. The adjustment in this case is very difficult and the use of a high-precision rotation stage with 4.4.m4 icrometer adjustment is recommended.
Profile Setup and Acquisition
There are many factors that come into play in the acquisition of raw beam profiles in order to achieve high accuracy. These include the scan rate, the 4.4.4s.p1atial sampling interval, the detector amplifier gain and bandwidth, and the signal filter. The acquisition settings need to be optimized for any given beam measurement, based on the nominal width of the beam being measured.
Scan Rate
The Scan Rate is the maximum update rate for profile acquisition and display of profiles and reported parameters. NanoScan2 operates at user selectable scan
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rates of 1.25Hz, 2.5Hz, 5Hz, 10Hz, and 20Hz. For each scan rate, there is a corresponding lower limit for width measurement due to the detector amplifier electrical bandwidth and rise time. This is because the rise time convolves with the profile. The scan jitter generally decreases at higher rates.
The lower scan rates of 1.25 and 2.5Hz should be used for pulsed beam operation. Refer to section 4.1.5 for an explanation of the pulsed operation and the effects of scan speed on this application.
Spatial Sampling Resolution
The spatial sampling interval is determined by the sampling clock, the scan 4.4.4ra.2te, the drum radius, and the angle of the slit with respect to the drum axis of
rotation. The sampling interval available with NanoScan2 covers a very wide range, from approximately 5.3nm at 1.25Hz to 18.3m at 20Hz. Depending on the scanhead scan rate, the available sampling interval selections are shown below in Table 4.4.
Table 4.4
Spatial Sampling Intervals
1.25 Hz 0.0053 0.0076 0.0114 0.0229 0.0572 0.1144 0.2288 0.5720 1.1440
2.5 Hz 0.0107 0.0153 0.0229 0.0458 0.1144 0.2288 0.4576 1.1440 2.2880
5 Hz 0.0214 0.0305 0.0458 0.0915 0.2288 0.4576 0.9152 2.2880 4.5760
10 Hz 0.0427 0.0610 0.0915 0.1830 0.4576 0.9152 1.8304 4.5760 9.1521
20 Hz 0.0854 0.1220 0.1830 0.3661 0.9152 1.8304 3.6608 9.1521 18.3042
NanoScan2 is capable of acquiring and processing profiles across the entire entrance aperture, at the minimum spatial sampling interval, with tens to hundreds of thousands of points, depending on scan rate and sampling interval. However, to reduce the number of data points, such as for a custom automation client, the spatial sampling interval can be increased. In this case, the maximum spatial sampling interval should be chosen to provide an adequate number of samples through the beam. As a general guideline, a minimum of 100 samples typically suffices for a smooth beam. If there is structure in the beam, then the sampling interval should be correspondingly smaller to resolve the fine structure.
The spatial sampling is along the curved trajectory of the slit as the drum rotates. Consequently, the use of a constant sampling interval is slightly in error due to the curvature. This leads to an accumulated error in position of approximately 1.5% at the edges of the entrance aperture window. This may be
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significant when measuring the positions of multiple beams, depending on measurement requirements. If so, a cosine correction can be applied to the sampling interval to compensate for the error.
Amplifier Gain
Amplifier gain, or "hardware" gain, is adjustable through software. The range of gain settings depends on the scanhead type. The gain steps are nominally 1dB 4.4.4in.3crements, or a gain factor of 1.122. The gain should be set to maximize the peak of the profile.
Filter Cutoff Frequency
Bandwidth for a given scan rate affects both the signal-to-noise ratio (SNR) and 4.4.4th.4e fidelity of measured profiles. The maximum bandwidth is 190kHz and is
adjustable through software down to 2kHz. Higher bandwidth is required for measurement of smaller beam diameters. Less bandwidth is required for lower scan rates.
Figure 4.15 Profile Undershoot is an indication that the bandwidth is limited. Either increase the filter frequency or reduce the scan rate. Excessive noise in a profile indicates that the bandwidth should be reduced.
Figure 4.15 Profile Undershoot
The filter cutoff frequency control is used to adjust the bandwidth at a given scan rate and amplifier gain to optimize the signal-noise ratio in the acquired profile. The data acquisition system must have sufficient bandwidth to faithfully record all the signal components in the profile.
When setting the filter frequency manually: as a general rule of thumb for Gaussian profiles, a bandwidth of ~190kHz is required to faithfully measure a 10m diameter beam at 10Hz scan rate. At a 5Hz scan rate, the required bandwidth is then 100kHz, or for a 5m diameter beam it is again 190kHz, and so on.
The algorithm for Filter Auto Track computes a minimum Filter bandwidth based on 10 the minimum filter required for a "sinusoidal equivalent" beam diameter, or 12 the minimum filter for a "Gaussian equivalent" beam width. This is a 4.4.4c.o5nservative approximation intended to account for higher M2 profiles, including Flat Top.
Regions of Interest (ROIs)
Profile analysis is performed in defined Regions of Interest, or ROIs. ROIs can be set automatically or manually through the software. The maximum number of ROIs that can be defined is 16.
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Profile Frame Averaging
Profile frame averaging provides for improvement in the signal-to-noise ratio (SNR) with subsequent improvement in profile fidelity/accuracy and the precision of derived results. Two types of Profile Averaging are available: 4.4.4F.r6ame Averaging and Rolling Frame Averaging. These can also be used in combination. Frame Averaging takes the average of N frames before reporting a resulting profile, and Rolling Frame Averaging uses the average of the last N frames.
The specified lower boundary for NanoScan2 Operating Space corresponds to an SNR of 10. Averaging can be used to improve the SNR for such measurements and also for power levels below the boundary where the profiles are effectively "buried" in noise. Thus profile averaging extends the measurement range to even lower power levels.
Averaging is also very effective at improving the measured Centroid (pointing) precision. Standard scanheads exhibit a 1 standard deviation precision of approximately 0.2-0.4m. Use of a rolling average of 16 profiles can reduce this to values <0.1m. However, averaging can also distort the pointing accuracy measurement of a laser that is moving so you must use this measurement tool based on the pointing stability of the laser under test.
Averaging is also useful to stabilize measured profiles when using the NanoScan2 in Pulsed capture modes. This provides more accuracy and precision in measured results.
4.4.4.7 Coordinate System
The coordinate system orientation can be set through software. The default coordinate system is based on the scan axes. However, in some cases it is desirable to change the coordinate system using a rotation transformation. This 4.4.c5an be done through the software's Scaling panel.
Scanning Slit Obliquity Correction
Slit obliquity arises due to the curvature of the scan drum or due to beam incidence off the normal direction. This may be significant when measuring highly divergent beams, beams incident at large angles, or for multiple beams that fill the entrance aperture. When this is the case, corrections to the raw profile data 4.4.c6an be made using a cosine correction factor. This feature is not built into the software and must be performed externally by the user.
Back Reflections and Laser Oscillation
When measuring laser beams, if the scanhead is positioned so that the incident beam is nearly perfectly normal to the scanning drum, the reflection can propagate back into the laser cavity and cause oscillations in the laser power output. These oscillations are observed as a high frequency spatial pattern and/or moving ripples superimposed on the profile.
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For low-power/power density measurements, reflections can be minimized using slit materials with lower reflectivity at the wavelength of use, and also by blackening techniques. However, for very high-power/power density levels, it is often more important that the slit material reflect MORE of the incident beam in order to avoid damage to the slits themselves.
If oscillations are seen when measuring raw laser beams, a simple solution is to observe the reflected beam spot back at the laser output and then slightly offset and or tilt the scanhead to steer the reflected beam off axis so that it misses the laser output mirror.
When measuring focused beams, a slight offset or tilt of the scanhead may not be sufficient because the focusing lens steers the reflected beam back to the source. In this case, use of an attenuator plate in the collimated beam path, tilted slightly so it doesn't cause feedback, as shown in Figure 4.16, can solve the problem simply by reducing the incident beam, and hence the reflected beam, even if it is still feeding back into the cavity.
Collimation lens
Slightly tilted thin glass plate such as a cover glass with metallic coating or dielectric coating to reflect out most of the light
This plane represents the scanning slit plane
Focusing lens
Figure 4.16 Use of an attenuator in the beam path to reduce back reflection
4.4.7 Note: Bulk absorbing filters are subject to thermal lensing, covered in section 4.4.9.
Beam Divergence and Angle of Incidence
When considering the accuracy of a raw profile measurement, two factors influence and limit the range of the beam widths; beam divergence and angle of incidence. These factors relate to the detector dimension, the dimension and thickness of the slit, and must be considered together with the nominal beam width and position in the entrance aperture. The detector dimension and its position relative to the scan plane, and the entrance aperture diameter, determine the ultimate limit of the beam divergence and/or angle of incidence for a given beam width. For divergence and incident angles above this limit, some or all of the light transmitted through the slit misses the detector (located a few millimeters behind the slit plane). For a tightly focused beam incident near the center of the entrance aperture, the angular limit is nominally 40-45° for typical NanoScan2 scanheads. If the beam
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is incident near the edge of the aperture this angle is reduced. Also, for a larger beam the angular limit is less. A more stringent limit is due to the dimension and thickness of the slits. As the divergence or angle of incidence increases, the slit vignettes and the transmitted light is reduced. For a particular slit thickness, the vignetting decreases as the slit dimension increases, allowing for larger divergence and incident angles. In practice, the NanoScan2 is ideally suited to the measurement of typical laser beams with low divergence in the milli-radian range and at angles of incidence up to approximately ±15°. When measuring "point" sources with very high divergence, such as optical fibers, the angular limits are easily exceeded. However, in some cases it is possible to perform a mathematical correction to the raw profile data to obtain more accurate results.
Divergence/NA Measurements 4.4.7N.1anoScan v2 software provides two methods for determining Divergence and
one for Numerical Aperture, NA; the Lens divergence method, the Point Source divergence Method, and the Numerical Aperture method. Selection and configuration of the different methods is done through the Computations ribbon, in the Divergence/Numerical Aperture panel.
4.4.7.1.1 Lens Method The Lens method uses a lens of known focal length f and can help determine the divergence of the beam from a nearly collimated source. To measure the divergence, place a lens of known focal length f into the beam. To ensure aberration free measurement with a singlet, be sure that
f 16
1.5D4
Place the NanoScan2 slit plane coincident with the plane of the lens geometric focus. The beam divergence at the focal length is:
Df f
where:
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Df is the second moment beam width at the focal length of the lens (mm) f is the focal length of the lens (mm) is the full angle divergence of the input beam (mrad)
It is important to note that the geometrical focus and the waist usually do not coincide. The waist is usually beyond the geometrical focal plane. Typical f values range from 100mm to 500mm. The relationship applies for Gaussian (TEM00) as well as any higher order or multi-mode sources (Figure 4.17).
Figure 4.17 Measuring Divergence using the Lens Method
To use the lens method, select Lens from the Method dropdown control. Select the Clip Level using the BW Basis and enter the Focal Length of the lens (mm) in the corresponding edit box. The beam divergence is reported in milliradians in the Results window. Note: For lasers, divergence is typically measured using the D4 second moment beam width method which is compatible with laser beam propagation theory. 4.4.7.1.2 Point Source Method, The Point Source method requires that the beam diameter be measured in the far field. The distance L from the point source to the measurement plane must be known (Figure 4.18):
Figure 4.18 Measuring Divergence using the Point Source Method
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Use the following equation to determine the far field measurement position:
L D02
where:
L is the distance from the point source
D0 is the source size
is the beam's wavelength
The divergence measured in the far field is:
2arctan r L
where:
is the full angle divergence (deg)
r is D/2 the beam radius (m) L is the distance from source (m)
To use the Point Source Method, select Point Source from the Method dropdown control. Select the Clip Level using the BW Basis and enter the Distance from the Point Source (in mm) in the corresponding edit box. The beam divergence will be reported in degrees in the Results window. Note: For lasers, divergence is typically measured using the D4 second moment beam width method which is compatible with laser beam propagation theory.
4.4.7.1.3 The Numerical Aperture Method The Numerical Aperture (NA) is the sine of /2, the half-angle divergence. This method is typically used to characterize optical fiber. Be sure the beam width measure is made in the far field as discussed above.
NA sin 2
To use the Numerical Aperture method, select Numerical Aperture from the Method dropdown control. Enter the values for Clip Level (%) and Distance from the end of the optical fiber. Note: NA is a dimensionless result. Fiber optic NA is typically measured with a 5% clip level based on the TIA/EIA-455-177A standard.
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Stray Background Light
Stray light due to sources in the vicinity of the scanhead may affect the measurements. This is especially the case when measuring very low power sources in the visible range where the gain is very high, and room lights can 4.4.c8ause significant stray background. The presence of stray light is usually observed as an unusual or unsuspected feature in a profile. It can be verified by turning off the source of the beam being measured.
In general, care should be exercised in the measurement setup to avoid such conditions. Precautions such as turning off room lights or use of an enclosure to shield out stray light is recommended.
Beam Attenuation
4.4.Ae9xttceeneudaintiognthme auyppbeer
required for measurements of beams with power levels limit of the scanhead's operating space. When attenuation
is necessary, it must be done properly. Ophir-Spiricon offers a number of beam
attenuation options that can thread directly into the NanoScan2's C-mount ring.
Contact your local Ophir-Spiricon sales representative for assistance in
selecting the best attenuation option for each application.
4.4.10
Slit Convolution and Small Beams
If an infinitely narrow slit is scanned across a Gaussian beam, the light intensity
transmitted by the slit as it moves across the beam exactly maps out the
Gaussian profile. However, a slit of finite width is required to transmit a
measurable amount of light, and the width of the slit has a detectable effect on
the shape and width of the measured intensity profile. The effect of finite slit
widths on beam profile measurements is explained in the following paragraphs.
Begin with the assumption that the actual profile of the beam is Gaussian.
Actual Profile = G(z) exp(z2 )
Measure this profile by passing a slit of width w across the beam. Express the measured profile as follows:
where:
M(z) erf(z ax) erf(z ax) , 2 erf(ax)
M(z) = Measured Profile
a In(p)
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x slit width beam width
The beam width is measured between the points where the intensity falls to a fraction, p, of the peak intensity at the center. The most commonly used values are p=0.5 for the full width at half-maximum (FWHM), and p=0.1353 at the 1/e² diameter. The measured profile, M(z), is similar in shape to the Gaussian profile, G(z), and M(z) approaches G(z) as x in the above formula approaches zero. For any given slit width, the width of the measured profile, M(z), is greater than that of the true profile, G(z). This discrepancy becomes greater as the width of the slit increases.
When the slit width is small compared with the measured width of the beam, the ratio, F, of the true beam width to the measured beam width can be computed accurately from the value of x, which is the slit width divided by the measured beam width, using the following semi-empirical formula:
=
1
-
2 3
()2
This formula can be used without significant error (less than 1% error in F) for values of the slit width parameter x<0.45 when the beam widths are measured to the 1/e² points. If the FWHM beam width is used instead, the formula is accurate to 1% for values of x<0.60.
The semi-empirical formula is based on the fact that for the convolution of two Gaussians, the squares of the width of the convolution is equal to the sum of the squares of the widths of the Gaussians forming the convolution. When the slit width is small, its Fourier transform (a sine function) may be regarded as Gaussian without serious error. For larger slit widths, the error in the approximate formula exceeds 1% and the results of the exact calculation of the ratio of true beam width to the measured beam width must be used instead.
The graphs in Figure 4.19 and Figure 4.20 are provided so that the actual width of the Gaussian profile, G(x), can be easily determined from the width of the profile M(x). These corrections have been computed for the two most commonly used threshold fractions, 1/e² and FWHM. When other values of the threshold fraction p are used, the semi-empirical formula for F provides a closer approximation to the correction factor, provided that the slit width parameter x remains less than 0.5. The procedure for using these graphs to determine the true beam width of a Gaussian profile beam follows. (For distributions other than Gaussian, these corrections may be invalid. We believe the best condition is to use a sufficiently small slit, and Ophir-Spiricon offers standard slits in 1.8m, 5m, and 25m sizes.)
1. Use the graph in Figure 4.19 for all corrections if beam diameters are measured to the 1/e² (13.5%) points. Use the
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graph in Figure 4.20 if the beam diameters are measured to the half-intensity points (FWHM). 2. Determine the slit width of the slit used to measure the beam profile. 3. Determine the measured width of the beam (1/e² or FWHM) from the output data provided. 4. Divide the slit width by the measured beam width to determine the value of x. 5. Enter x in the graph and find the correction factor F. 6. Multiply the measured beam width of step 3 by the correction factor F to obtain the true width of the Gaussian Beam.
Figure 4.19 Slit Width Correction Data for 1/e² Measured Width
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Figure 4.20 Slit Width Correction Data for FWHM Measured Width
4.4.11
Near-Field Profiling
Ophir-Spiricon offers several near-field profiling accessories for measurement
of very small spots.
Model NFP VIS operates at 60:1 magnification and is useful from 400700nm.
Model NFP 980 operates at 60:1 magnification and is useful from 7001100nm.
Model NFP 1550 is useful from 1300-1600nm and operates at 40:1 magnification. For more information, see our data sheet at
http://www.ophiropt.com/laser-measurement-instruments/beamprofilers/products/slit-based-profilers/nanoscan-near-field
Accessories for small spot measurement include the Option H/I, which is a bracket that positions a finite conjugate DIN microscope objective lens 160mm in front of the measurement plane. For measurement of very small spots when magnifying lenses are used, an important consideration is the Modulation Transfer Function (MTF) of the lens for the wavelength of use, which determines the system optical resolution. Depending on the MTF, relayed images in the micron domain may or may not be accurate. As a general guideline, use a well-corrected objective for the wavelength of use.
Objectives with numerical apertures (NA) greater than 0.4 and magnifications greater than 40 perform better than low power, low NA objectives. Higher-price objectives are nearly always better than the alternative.
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Spot measurements below a few microns are also very difficult to perform due to system vibration. It's necessary to have sufficiently high quality mechanical fixtures for measurements in this domain. Everything moves around on the micron level. If you require measurements at less than 10-20m; you need to acquire very high quality mechanical fixtures and stages. Many off-the-shelf stages do not provide the stability or sensitivity to measure very small spots.
Power Measurements
4.4.12
The NanoScan2 Power meter provides calibrated measurements of CW beam power based on a user-generated calibration stored in the scanhead's EEPROM. See section 5.3.11 for detailed information on how to use this feature. The input Reference value must be obtained from an independent measurement of the beam's power derived from a calibrated power meter. Thus the absolute accuracy of the displayed result depends partly on the accuracy of the power meter. To achieve the most accurate and consistent results, it is advised that calibration records be generated for each source and wavelength, and also for different measurement configurations, to account for factors such as angle of incidence and beam size. If there is any doubt about the measurement accuracy, always retest the different conditions for your application before proceeding. 4.4.13
Multiple Beam Measurement
When measuring multiple beams, the arrangement of the beams, the beam divergence, and the plane of measurement determines whether or not NanoScan2 can resolve them. In general, each beam in a linear array of collimated beams can be resolved. The measurement must be performed with the scan axes oriented at ±45° to the array. Also, it is useful to use the rotation transformation feature in the NanoScan2 software to provide the beam positions in coordinates common to the linear array. When beams overlap, it is not possible to completely resolve the profiles. However, it is possible to extract information such as peak separation by defining specific ROI's around each beam's peak.
4.5 NanoScan2 USB 2.0 Hardware Specifications
The NanoScan2 is an upgraded version of the original NanoScan product line. The NanoScan2 is a self-contained scanhead that incorporates a powerful
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digital signal processor and a 16-bit analog to digital converter. All silicon and germanium NanoScan2 scanheads are provided with a power meter that can be user calibrated to make power measurements; see section 4.4.12.
Bus interface
USB 2.0, Powered via USB port
Signal digitization
16-bit
Maximum digitization clock 21.4MHz
Maximum scan rate
20Hz
Data transfer
Bulk Transfer Mode
On-board memory
64MB SDRAM
Weight
434g (15.3 ounces)
Operating temperature
0...50C
Humidity
90%, non-condensing
Sample transfer data time 0.4ms for 10K samples (20Kb)
NanoScan2 Scanhead Models
4.5.S1tandard NanoScan2 scanheads come with various combinations of detector, entrance aperture diameter, and slit width. These are listed below. Please see Appendix A for hardware specifications on the following scanhead models: (detector type / aperture dia / slit width in µm)
4.5.1.1 4.5.1.2
Silicon Detectors (190-950nm)
PH00421 PH00422 PH00423 PH00429 PH00430 PH00431
NS2-Si/3.5/1.8-STD NS2-Si/9/5-STD NS2-Si/9/25-STD NS2-Si/3.5/1.8-PRO NS2-Si/9/5-PRO NS2-Si/9/25-PRO
4.5.1.3
Germanium Detectors (700-1800nm)
PH00424 PH00425 PH00426 PH00432 PH00433 PH00434
NS2-Ge/3.5/1.8-STD NS2-Ge/9/5-STD NS2-Ge/9/25-STD NS2-Ge/3.5/1.8-PRO NS2-Ge/9/5-PRO NS2-Ge/9/25-PRO
Pyroelectric Detectors (0.2-20m)
PH00427 PH00428
NS2-Pyro/9/5-STD NS2-Pyro/9/25-STD
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PH00435 PH00436
NS2-Pyro/9/5-PRO NS2-Pyro/9/25-PRO
Mechanical Dimensions
See Appendix B for the mechanical dimensions of the scanheads.
4.5.2 Operating Space Charts
See Appendix C for the scanheads Operating Space Charts. 4.5.3
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5 NanoScan v2 Software
The NanoScan v2 Beam Profiling and Analysis software is a stand-alone graphical user-interface (GUI) for beam profiling with a NanoScan2 scanhead. The GUI includes ribbon tabs for source setup, display selections, capture settings, computation settings, power calibration, results charting, results logging, and M2 calculations. Measurement of up to 16 multiple beams is accomplished by defining specific Regions of Interest (ROIs) for beam analysis. Separate results can be computed for each enabled ROI. For multiple beams the separation of beam centroids and peaks can be computed. The default screen layout is shown in the image below.
5.1 Nomenclature Change
The legacy NanoScan software referred to the scanned profiles, axes, and results items as 1 and 2, or sometimes A1 and A2. This nomenclature is not common to the industry and is replaced with the more common X and Y notation. In some places both usages are referenced, while in others just the X/Y terminology is indicated. The face of the NanoScan2 scanhead now bears
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the X and Y markings. The 1/2 markings are also retained so that older users can see how the new axis markings correlate to the old.
5.2 Displays
A flexible display environment is available to meet your specific needs. A main display window that shows specific items can be transformed into a complex, multi-tasking display with floating desktop windows and multiple pinned charts or display windows. The example shown below contains all of the main display windows.
The screen layout is automatically saved when the application is closed and will 5.2.b1e restored the next time it is launched.
Terminology
The tools that permit making simple and complex screen layouts employ terminology that may be new to some Windows users. This section provides a graphical glossary of terminology. Note: Within the industry there is some variation on the naming conventions in the ribbon motif that is employed with NanoScan v2. The terms used are for consistency.
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File Menu Quick Access Toolbar Ribbon Tabs
Panel
Title Bar
Standard Windows Controls Ribbon Bar
Results Window
Message Window
Primary Dock Window (note tabs)
User Notes
Status Bar
5.2.2
Primary Dock Window and Dock Handles
The Results/Notes display window is a permanently docked window and is always appears in the main window. All other windows can be docked, floated, and hidden.
The first time a display window is opened, it is placed as a tab in the Primary dock window. All primary dock windows can be removed and repositioned by the user. Once a display is relocated, the application remembers the placement when closed and reopened.
To undock a primary dock window, grab the tab with the mouse and drag down into the application window area. When dislocated from a docked position a set of docking handles appear as shown below.
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Docking Handles
All view displays can be dragged and docked to the four sides of the application window. In this example, the 3D view is the object being dragged to a dock handle.
Displays can be grabbed with the mouse in their Title bar or Tab region and dragged onto a dock handle. This can also be done with the Chart displays.
Left Dock Handles
Top Dock Handles Right Dock Handles
Primary Dock Window
Bottom Dock Handles
While dragging the view in the display, place the mouse over a docking handle. When the mouse button is released, the view docks to the window in the selected location. After positioning, the view can be resized. This is done by grabbing an edge with the mouse and dragging to the desired dimensions. If no 5.2.da3oncdksinizgedpoasniytiwonheisreinodnicthaetesdc,rteheen.view sets to Floating and can be positioned
Dock Handle Cloning
Each view has its own set of dock handles. This allows docking views side by side, over, and under each other. Below is an example of many windows, some docked inside of other windows, and some floating. The best way to learn how to manipulate the windows and use the docking handles is to experiment.
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Note: Floating windows clones the docking handles and can be combined with other floating windows. When set to floating, the function of each view is the same as when the view is docked to the main display.
5.2.4 Auto Hide
Click to hide a docked view. Click to unhide a docked view. The Auto Hide feature is available on docked views and allows hiding many items in a single dock site. Clicking the view's Auto Hide button causes the selected display to collapse into the edge of the dock frame. The view can be opened by hovering the mouse over or clicking on the hidden view's tab. The figure below shows hidden view tabs at the bottom and the right side of the main window.
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To restore a hidden view, click on the rotated pin unhide tool and the view will be restored to the former docked location.
Auto Hide allows for using a large number of Charts but not occupying a lot of screen space. When a specific chart needs to be viewed, it can slide out without 5.2.o5pening the other charts.
Keyboard Shortcuts
Keyboard shortcuts allow navigating through the display window without using the mouse. These controls are accessed by first pressing the Alt key on the keyboard, followed by a sequence of letters and/or numbers that appear beneath the ribbon and panel options. A list of some default keyboard shortcuts is provided below.
Alt-F-O File Open Dialog Box Alt-F-A Save As
Alt-F-S Alt-F-P
Save Print
Alt-F-U Print Setup
Alt-F-X Close/Exit NanoScan v2
Alt-F-R Reset Window Layout
Alt-F-B About/Update License
Alt-S-L Select Black Background Style
Alt-S-B
Select Blue Background Style
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Alt-S-S Alt-S-D Space
Select Silver Background Style
Select Windows 7 Background Style
When 3D window is active, the view is reset to the default display
Alt-S-A Alt-A
Select Aqua Background Style
Open the NanoScan v2 Operation Manual
The controls can also be selected by pressing Alt followed by the arrow keys or the Tab button on the keyboard. Pressing Shift+Tab allows moving backwards through the control selections. Enter enables the highlighted control.
5.3 Controls
The controls include ribbon tabs that open ribbon bars used for choosing various settings. The ribbon tabs include Source, Profiles, 2D/3D, Pointing, Capture, Computations, Power, Charts, Logging, and M2. Above the ribbon tabs are quick launch tools in the Quick Access Toolbar with buttons for Open, Save, Profile X, Profile Y, 2D, 3D, Pointing, and Auto ROI.
5.3.1 Quick Access Toolbar
Hovering the mouse over the buttons in the quick launch tools provides a short description of each icon's function. The following buttons are available:
Opens the File Open dialog box so previous data files/setups can be loaded from saved .nsd/.nsdx files Saves the current data and setup into the last used *.nsdx data file Opens the Profile X view of the X (1) axis
Opens the Profile Y view of the Y (2) axis
Opens the 2D view
Opens the 3D view
Opens the Pointing view
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Enables/Disables Auto ROI
Opens the NanoScan v2 Operation Manual.
Buttons can be added or removed by selecting Customize Quick Access Toolbar from the drop down arrow or by right-clicking in the ribbon bar. Any control located in a ribbon bar can be added to the Quick Access Toolbar by right-clicking on the button and selecting Add to Quick Access Toolbar. To remove controls from the Quick Access toolbar, right-click on the button to be removed in the Quick Access Toolbar and select Remove from Quick Access Toolbar.
File Menu
5.3.T2he File Menu is used for basic file handling operations, including opening files, file saving, and printing.
Open... Save Save As...
Opens saved data files. The File Open dialog box will appear. This can be used to open older *.nsd and new *.nsdx file types.
Saves the current image data and settings in an *.nsdx or *.txt ASCII file format, based on the file name and type last saved. The last file name used is automatically overwritten.
Opens the File Save As dialog box for naming files and selecting the file format. The dialog lists files from the current working directory in the selected format. The possible selections are:
*.nsdx NanoScan v2 binary software data format for review and reanalysis using the NanoScan v2 software.
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Print Print Setup Reset Window Layout
About Exit
*.txt ASCII text file format that contains setup parameters and comma delimited ASCII outputs of the 1D beam profiles contained within any enabled ROI. Both Profiles are saved even if only one is being displayed.
Print dialog for printing the NanoScan v2 Report.
Opens a dialog for selecting and configuring printers.
Returns the layout of the application to its original state. All of the NanoScan v2 windows will be returned to their original positions.
Displays software version information and allows entering a new scanhead upgrade license key.
Closes the NanoScan v2 application.
Status Bar
5.3.3
The Status bar, located at the bottom of the display window displays useful information including:
The number of Samples used in the statistics results The connected head's Serial Number The current Scan Rate in Hz The current Sample Resolution in m The Automation indicator informs the user if the automation option is
available for the connected scanhead. If automation is available, Professional is displayed. If automation is not available, Standard is displayed.
This information can be shown/hidden by right-clicking on the Status bar and selecting/deselecting the desired items.
5.3.4 Note: If the head scan rate is not operating within 0.01% accuracy, the Scan Rate value turns red.
Ribbon Bars
Ribbon bars can be hidden from view by right-clicking on the ribbon and selecting Minimize the Ribbon. When minimized, only the ribbon tabs are visible. Clicking on a ribbon tab temporarily displays the ribbon until a selection has been made or the focus is directed elsewhere. To restore the ribbon bar, right-click in the ribbon tab area and deselect Minimize the Ribbon. The ribbon tabs are as follows:
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Source Profiles 2D/3D Pointing Capture Computations Power Charts Logging M2
Select and control the scanhead Select and control the Profile displays Select and control the 2D/3D displays Select and control the Pointing display Select and control the capture modes Select which results items to display Calibrate, save, and select calibration settings Enable various results Charting displays Control results logging Make manual M² measurements using the M2 Wizard
Regions of Interest (ROI) 5.3.4T.h1e Regions of Interest dialog box is used for configuring the ROI mode,
either Automatic or Manual, for selecting the Multiple Beams ROI option, and for manually setting ROIs and adjusting their boundaries. The ROI dialog box can be accessed from the Source ribbon and the Profiles ribbon.
5.3.4.2 Automatic ROI Mode
When Automatic ROI is selected, the system operates in Automatic ROI mode. In Automatic mode, the ROIs are determined automatically by the NanoScan v2 software. The algorithm defines beams and generates ROI boundaries based on the 1/e² beam width and the beam centroid position.
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Profile X Profile Y Colors
5.3.4.3
Lists the Left and Right boundary positions for each ROI in Profile X. The Left and Right edit boxes and the Add and Remove buttons are inactive when in Automatic mode.
Lists the Left and Right boundary positions for each ROI in Profile Y. The Left and Right edit boxes and the Add and Remove buttons are inactive when in Automatic mode.
The color of the respective ROI boundaries displayed in the Views window can be individually set using the Colors control. Double clicking the left mouse button on the color in front of the ROI number opens the color dialog for changing the color.
Manual ROI Mode
When Automatic ROI is not selected, the system operates in Manual ROI mode. In Manual mode, the ROI boundaries in Profile X and Profile Y can be set manually using the Left and Right edit boxes, or by using the mouse pointer to drag and drop the ROI boundaries in the Profile X and Profile Y view displays.
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Profile X Profile Y
Lists the Left and Right boundary positions for each ROI in Profile X. To manually set the boundaries using the edit boxes, first select the ROI to be adjusted. Then enter the boundaries in the appropriate edit box, and use the Update button to set the boundaries. To add an ROI, be sure there is no ROI selected in the list, then enter the boundaries in the edit boxes and click the Add button. To remove an ROI, select the ROI and use the Remove button or the Delete key. The check box under ROI # enables the computation and display of results for the corresponding ROI.
Lists the Left and Right boundary positions for each ROI in Profile Y. To manually set the boundaries using the edit boxes, first select the ROI to be adjusted. Then enter the boundaries in the appropriate edit box, and use the Update button to set the boundaries. To add an ROI, be sure there is no ROI selected in the list, then enter the boundaries in the edit box and click the Add button. To remove an ROI, select the ROI
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Colors
and use the Remove button or the Delete key. The check box under ROI # enables the computation and display of results for the corresponding ROI.
The color of the respective ROI boundaries displayed in the Views window can be individually set using the Colors control. Double clicking the left mouse button on the color in front of the ROI number opens the color dialog for changing the color.
ROI Mode
Note: The easiest way to adjust ROIs is to allow the software to generate 5.3.4.4 Automatic ROIs. Then turn off the Automatic ROI feature. The automatically
generated ROIs remain in the display, and can then be adjusted manually.
Single ROI Multiple ROI
When selected, the system assumes a single beam and only one ROI can be automatically determined or manually defined for analysis.
When selected, a maximum of 16 ROIs can be automatically determined or manually defined for analysis.
5.3.5
Note: When ROIs have been edited, switching from Multiple ROI mode to Single ROI mode enables Automatic ROI mode and all defined ROI values are deleted. To save the defined ROI values, stop data acquisition, switch to Single ROI mode, then disable Automatic ROI mode. Computations are then only made for the first defined ROI value.
Source Ribbon
The Source ribbon is used to select a NanoScan2 scanhead, start and stop data acquisition, set the scanhead scan rate, set the spatial sampling resolution, adjust the ROI, and for automatic or manual selection of gain and filter frequency settings for the X and Y axes. The Power Gain is always operating if using a silicon or germanium scanhead. A scanhead MUST be selected prior to starting data acquisition. The Source controls are unavailable until a scanhead is selected.
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Start / Stop
/ Detector
Starts and Stops profile data acquisition. These buttons are available in each ribbon bar.
Select and control the scanhead.
Scanhead Scan Rate
Dropdown list for displaying scanhead status ("Free" or "In use"). A single instance of the NanoScan v2 software can control only one scanhead at a time, selected from this dropdown list. There can be only one instance of the NanoScan v2 software running at a time. A SN of 0 indicates that the software could not connect to a scanhead.
Sets the NanoScan2 scanning speed of the connected scanhead in Hz. The sampling resolution changes with the scan rate. An information message is displayed in the message window when the scanning speed is changed.
If the head scan rate cannot be set within 0.01% accuracy, a warning message will be displayed in a dialog box and in the Message Window.
The NanoScan v2 software continues to operate as close to the selected scan rate as possible. When the actual scan rate is not within the 0.01% accuracy, the Scan Rate in the Status bar turns red. At the 0.01% stability level, the beam position accuracy is 0.1m/mm. The beam diameter accuracy is only affected if the stability exceeds the 1% level. Scan Rate selection is disabled when Data
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Sampling Resolution
Setup
Recorder is enabled. Select the desired Scan Rate before enabling the Data Recorder.
Sets the Sampling Resolution in microns. The Sampling Resolution is the same for both axes and is related to the Scan Rate and Magnification setting. This value controls the number of samples taken across the beam. In Pulsed mode, the spatial sampling is limited to fine sampling values (small numbers) in order to resolve narrow high frequency pulses.
The smaller the number, the more data is collected. The automatic setting tries to set this value so that there are ~100 data points across the beam width. Setting the Sampling Resolution to a number too small does not improve the quality of the data, but it does increase the amount of data. This tends to slow down the acquisition and make data files much larger than they need to be. There is a more detailed discussion of the effects of Sampling Resolution in section 4.4.4.2 on Spatial Sampling.
Sampling Resolution selection is disabled during Data Acquisition and when Data Recorder is enabled. Select the desired sample resolution before entering these modes.
Use to define setup values for Gain, Filter Frequency, and ROI boundaries.
Auto Find
Set ROIs Auto ROI
Initiates a "one-shot" auto setup of the Gain, Filter Frequency, and Sampling Resolution for each axis, and sets the ROI to auto mode. Auto Find also establishes a view of the beam in the Views window for Profile X, Profile Y, Pointing, 2D, and 3D.
Auto Find is disabled when Data Recorder is enabled.
Use this option to open the ROI edit window. The edit window allows enabling/disabling the Automatic ROI operation and setting ROI boundaries. See section 5.3.4 for more details.
This option allows for enabling/disabling the Auto
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Gain Track
Axis X Axis Y Power Filter Frequency
ROI feature without entering the ROI edit window.
This panel controls the electronic Gain settings for both the X and Y axes in dB.
Gain is the amplifier setting that provides the best full-scale output of the beam profile that is not saturated. This value is most easily chosen by activating Gain Track.
Enable/Disable automatic Gain Tracking on both Axis X and Axis Y. The gain for each axis is set so the maximum of the peak values of all ROIs is 1dB below saturation. In Pulsed mode the gain for both axes are reduced.
If the Gain values for Axis X or Axis Y appear unstable while Track is enabled, then Frame Averaging and Rolling Frame Averaging in the Capture ribbon may not be meaningful. When changing frame averaging values, it is suggested to disable the Gain and Filter Frequency Track.
Sets the Gain setting of the scan for Axis X (1) in dB. The allowable range varies with the scanhead type. When Track is enabled, this parameter is set automatically by the NanoScan v2 software to match the operating conditions. In most cases the software-chosen value is the most appropriate for use.
Sets the Gain setting of the scan for Axis Y (2) in dB. The allowable range varies with the scanhead type. When Track is enabled, this parameter is set automatically by the NanoScan v2 software to match the operating conditions. In most cases the software-chosen value is the most appropriate for use.
Automatically displays the Auto Gain setting for the power reading if using a silicon or germanium scanhead.
This panel controls the photo detector amplifier electronic 3dB cutoff of the sampled head signals for both the X and Y axes. A filter too large allows noise onto the profile signal which will increase the spot size and position variance. A filter that is too low for a given beam size will measure the spot size larger than actual, so one should experiment to set the filter manually. Filter
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Track Axis X Axis Y 5.3.6
Frequency Tracking is sufficient for most laser beams.
In Pulsed mode, the Filter Frequency is automatically set to 190kHz and filter control is disabled.
Enables/Disables automatic Filter Frequency Tracking to reduce noise on both Axis X and Axis Y. The filter setting is based on the beam width.
If the Filter Frequency values for Axis X or Axis Y appear unstable while Track is enabled, then Frame Averaging and Rolling Frame Averaging in the Capture ribbon may not be meaningful. When changing frame averaging values, it is suggested to disable the Gain and Filter Frequency Track.
Low-Pass filter frequency setting of the slit scan on Axis X in kHz. The allowable range is between 2 and 190kHz.
When Track is enabled, this parameter is set automatically by the NanoScan v2 software to match the operating conditions. In most cases the software-chosen value is the most appropriate for use. However, it can be manually set by the user.
Low-Pass filter frequency setting of the slit scan on Axis Y in kHz. The allowable range is between 2 and 190kHz.
When Track is enabled, this parameter is set automatically by the NanoScan v2 software to match the operating conditions. In most cases the software-chosen value is the most appropriate for use. However, it can be manually set by the user.
Profiles Ribbon
The Profiles ribbon is used to select profile viewing options of the beam and to define the origins of the beam axes. The display options include selections for both Horizontal and Vertical view scaling. The horizontal view can be set for either Auto Zoom or manual scaling. The amplitude Vertical view scale can be either linear with 1X, 10X, or 100X magnification, or logarithmic. The spatial X and Y origins can be set with the Origin Location panel.
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Display
Profile X Profile Y Set ROIs
Auto ROI Scaling
Horizontal Scaling Profile X Profile Y Auto Zoom
Select a view for display in the Views window and define ROI boundaries.
Enable the Profile X view of the X (1) axis.
Enable the Profile Y view of the Y (2) axis.
Use to open the ROI edit window. The edit window allows enabling/disabling the Automatic ROI operation and setting ROI boundaries. See section 5.3.4 for more details. Allows for enabling/disabling the Auto ROI feature without entering the ROI edit window. Select either Linear or Logarithmic scaling for the profile vertical axis for both Profile X and Profile Y. In Linear mode, select 1X, 10X, or 100X magnification for the vertical axis. When Pulsed-Short operation mode is selected, the vertical scale is forced to 10X magnification. For Log scaling, the vertical scale choices are disabled.
Use to set the horizontal zooming for Profile X and Profile Y or set to Auto Zoom.
Use to zoom in or out along the horizontal axis in the Profile X view.
Use to zoom in or out along the horizontal axis in the Profile Y view.
When enabled, the horizontal view is scaled automatically to display all enabled ROIs. If the horizontal zoom or position is manually adjusted, Auto Zoom is disabled.
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Gaussian Overlay Origin Location
ROI # Current/New
Current
Default
Apply Reference
When selected, the Gaussian fit is displayed over Profile X and Profile Y in the Profile views. The ROI boundaries define the region where the fit calculation is performed.
Use these controls to define a spatial (0,0) origin for the X and Y axes.
Selects the ROI used for the Current centroid selection.
Enter the new origin location for Axis X and Axis Y then hit Apply to execute the change. The entered values must be based on the current origin placement. The entry can be manually entered, use Current, or use Default. This change effects the spatial location in all spatial controls (such as ROI) and displays, including Pointing.
Enters the selected ROI beam's current centroid into the New/Current edit control for both Axis X and Axis Y. Centroid results must be enabled in the Computations ribbon for the Current entry to load correctly. Click Apply to make this the new origin.
Enters the factory Default origin into New/Current for both X and Y axes. Click Apply to use the default origin locations. The Default represents the geometric center of the aperture. When applying the Rotation Transform, see Computations ribbon, it is recommended that you use the Default setting for the Origin location.
Sets the displayed New/Current/Default value offsets as the new origin location for the X and Y axes.
Displays the current origin locations relative to the Default factory settings.
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Profile Views The Profile view displays the acquired beam profile data for an individual axis of the NanoScan2 scanhead. Options for setting the profile amplitude Vertical Scale and the spatial Horizontal Scale are located in the Profiles ribbon. The 5.3.6a.x1es can be viewed simultaneously by docking or floating the views on the screen. See section 5.2 for more details on docking and floating.
The Horizontal Position bar, located below the profile display allows for positioning of the Horizontal axis within the aperture. Adjusting this position disables Auto Zoom in the Profiles ribbon. The beam width chosen with the BW Basis in the Computations ribbon is 5.3.d7isplayed in the upper left corner of the profile views when in Single ROI mode. Refer to section 5.3.4 to set the software in Single ROI mode.
2D/3D Ribbon
The 2D/3D ribbon is used to select 2D and 3D viewing options. These options define both the 2D and 3D displays. The display options include selecting either Linear or Logarithmic scale, Resolution, Rendering Style, or Color Palette.
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Display
Select 2D or 3D view for display.
2D 3D Reset 3D Scale
Resolution
Style
Enable the 2D view.
Enable the 3D view.
Zoom and rotation of the 3D window return to their default values.
Select either Linear or Logarithmic scaling in the Z axial direction. In Logarithmic scaling, the contour levels are fixed at the 0, -3, -10, -13, -20, -23, -30, -33, -40, and the -48dB levels.
Allows resolution selection for both the 2D and 3D displays. Medium is the default setting. The data update rate may be reduced and image manipulation may be slower as resolution is increased. Resolution can also be increased by selecting a smaller Sample Resolution in the Source ribbon.
Choose either solid surface or wire frame rendering.
Palette
5.3.7.1
Choose one of the preset color palettes. The color palette is always auto ranged to the full display height of the displayed beam.
2D and 3D Views
The 2D and 3D views display the laser beam image in a topographic or 3dimensional viewing format. The laser beam image can be rendered with either a wire frame or solid surface. Display colors can be selected from a list of
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predefined palettes. This display is available only in Single ROI mode. Refer to section 5.3.4 to set the software in Single ROI mode.
The 3D image can be rotated, translated, panned, and zoomed using the mouse as described below. The 2D image sizes with the window. When the 3D view is active, pressing the Space bar resets the display to the default orientation.
Rotation
Pan/Translate Zoom 5.3.8
Position the cursor over the image, click the left mouse button, and drag the mouse to obtain the desired orientation. If the mouse is moving when the button is released, the image continues to rotate in the same direction the mouse was moving. Click on the screen to stop the image from rotating.
Position the cursor over the image, hold the left and right mouse button, or the scroll wheel, and drag the mouse to move the image to the desired location. If the image continues to pan/translate, click the screen to stop the movement.
Zooming in or out can be done by scrolling with the scroll wheel or by placing the mouse cursor onto the beam image, depressing the right mouse button and sliding the mouse up or down.
Pointing Ribbon
The Pointing ribbon allows charting of either the beam centroid or peak movement. An Accumulate mode can be used to map motion over extended time periods. This feature can chart multiple centroids when multiple ROI's are enabled.
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Display Pointing Accumulate Reset
Tracking Centroid
Peak
Enable the Pointing view for display. Enable/Disable accumulation mode, and reset the chart.
Enable the Pointing view.
When selected, enables the Accumulate mode which displays a history of beam positions. Enabled is the default setting.
Clears and restarts the accumulated data in the Pointing view.
Select to chart either the Centroid or the Peak locations.
Sets the point plotting to chart the spatial Centroid position of the beam.
The Centroid is a calculated value for the beam location that is based on its center of mass, also known as the "first moment." This is the point when equal amounts of the beam are on either side of the centroid.
Sets the point plotting to chart the Peak positions. In a scanning slit system the observed profile peaks may or may not represent the actual peak location of the beam. For a Gaussian TEM00 beam, the peak and the centroid ideally coincides with the centroid location. In the real world, the peak is often in a slightly different place and may well be less stable than the centroid. NOTE: If Rotation Transform is enabled in the Computations Ribbon, Peak results may not be valid.
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Indicator
Select to display the Centroid/Peak location with or without a crosshair or a beam outline.
Cross Hair Beam Outline
Center of Graph
When enabled, the Peak or Centroid position of the last plotted scan, in each enabled ROI, is displayed as a crosshair.
When enabled, the 13.5% beam widths, for each enabled ROI, is displayed as an elliptical overlay around the last plotted data point.
Note: If Beam Outline is selected and not visible, zooming out may be necessary to bring it into view.
Use to bring the selected ROI to the center of the Pointing display.
ROI Center
Zoom
5.3.8.1
Selects an ROI.
Centers the chart to the Centroid/Peak position of the selected ROI, based on the following rules:
If data acquisition is running and Centroid/Peak result is enabled, the chart centers on the Mean of the selected result.
If data acquisition is running and Centroid/Peak result is disabled, the chart centers on the last captured centroid/peak.
If data acquisition is stopped, the chart centers on the last captured centroid/peak.
Controls the zoom scaling of the Pointing view. The maximum scale depends on the scanhead aperture size. The minimum scale is 10m.
Pointing View
The Pointing view displays spatial positions of the beam profile in each enabled ROI on a Cartesian grid. The perspective of the view is looking toward the NanoScan2 scanhead entrance aperture. The axes of the display are oriented along the scanhead axes or along the direction determined by the rotation angle set in the Computations ribbon.
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Example: Below is a Pointing view display showing the beam position in 2 ROIs as cross hairs, with overlays for the 1/e² profile contours.
Example: Below is a Pointing view display with accumulation enabled, showing the sequentially accumulated beam positions for a single ROI.
5.3.9
Capture Ribbon
The Capture ribbon is used to set the Capture Mode of the scanhead for either Continuous Wave or Pulsed lasers, enable the number of data frames to average and the method to employ while averaging, and to enable/disable Data Recording.
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Capture Mode
CW Pulsed Short
Select an appropriate Capture Mode. Enter the laser pulse repetition rate if operating in pulsed mode.
Changes in Capture mode must be made prior to enabling Data Recorder. This panel is disabled when Data Recorder is enabled.
Selects operation for Continuous Wave lasers
Selects operation for Pulsed lasers with pulse widths <~10ns. To provide best accuracy, the profile peak amplitude must be <4096 counts to avoid amplifier nonlinearity. The X and Y Profile displays force vertical scaling to 10X. With Gain Track selected the amplitude is limited to <4096 counts. However, Gain can also be set manually. If the Gain is manually set so that the peak amplitude is >4096 counts, an information message displays in the Message Window warning the user to decrease the gain.
Pulsed Long
Selects operation for Pulsed lasers with pulse widths >10ns. In this mode the full-scale amplitude is limited to 32769 counts to avoid amplifier nonlinearity and subsequent measurement error.
In Pulsed mode, the Filter Frequency is automatically set to 190kHz and the filter controls are disabled, and the peaks of the individual pulses in the profile are connected to construct a smooth profile. Frame Averaging can be employed to help create a more detailed profile construct. All result computations are performed on the resulting construct.
Measurement accuracy depends on the pulse-to-pulse repeatability of the laser and on the number of pulses in the profile during a single scan, which in turn depends on the laser pulse repetition rate and beam diameter.
A minimum of 15 pulses through the beam profile is required to obtain specified accuracy. If there are not enough pulses present in a single scan (<15), the software computes the corresponding head Scan Rate and displays an information message in the Message Window recommending a
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lower Scan Rate.
If the computed head Scan Rate for the current conditions is below 1.25Hz, an information message displays in the Message Window warning the user about operating the NanoScan2 system outside the ±2% accuracy specification.
Refer to section 4.1.5 for more information about measuring pulsed beams.
Pulse Rate [kHz]
Enter the laser pulse repetition rate in kHz between 0.1-1000kHz. When no value or an invalid value is entered, NanoScan v2 assumes the Pulse Rate to be either 1 or the previous acceptable value. The more accurate this value is, the better the ability to measure the pulses and reconstruct the beam's profile. See below.
Measured [kHz]
The observed laser pulse rate is measured and displayed here as a check against an incorrect value entered above. Use this displayed value to adjust the Pulse Rate. This parameter is also reported in the Results window when Pulse Rate is selected in the Computations ribbon and a value of "0" is reported if the measurement is uncertain.
Frame Averaging
Use these controls to average scan data frames.
Average Rolling
Selects the number of profiles to be averaged per beam analysis (N). Values can range from 1 to 1000. Displayed profiles and computed results are based on an average of N profiles. Results and display update rate is N times slower than the normal scan rate.
If the Gain or Filter Frequency settings are unstable while Track is enabled, frame averaging may yield less meaningful outputs. If this is the case, disable the Gain and/or Filter Frequency Track modes as applicable.
Selects the rolling average number of profiles to be
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Data Recorder
used in rolling profile analysis (N). Values can range from 1 to 16. Displayed profiles and computed results are based on an average of N profiles. After the first N samples are acquired the data update is at the normal rate.
If the Gain or Filter Frequency settings are unstable while Track is enabled, frame averaging may yield less meaningful outputs. If this is the case, disable the Gain and/or Filter Frequency Track modes as applicable.
The Data Recorder allows for recording and reviewing a collection of beam profiles. The recorded data can be reviewed in Profile views, 2D and 3D views, and the Pointing view. The maximum number of data records depends on the Sampling Resolution (the finest Sampling Resolution is 0.0053m at 1.25Hz). The software computes the memory needed to record one full scan and then, based on the total memory of the computer, sets the maximum number of scans that can be recorded (no more than 100). When Enabled, Data Recorder acquisition can be started by clicking the Start button. Data collection automatically stops after the maximum number of frames (usually 100) is reached. The actual time that data is collected depends on the head Scan Rate; e.g., for 100 scans at 10Hz, 10 seconds of data is acquired; at 2.5Hz, 40 seconds are acquired.
While recording data, the Data Recorder controls are disabled until the Stop button is pressed or the maximum frame count is reached. The data can be reviewed and analyzed frame-by-frame and statistics gathered for selected frames. The recorded data can be saved as a *.nsdx file. This file can be opened and the data reviewed at a later date.
Many controls are disabled during the recording process. Thus it is important to have things set up properly before starting the record cycle.
With Gain Track enabled, the Data Recorder takes three or four scanhead revolutions to set the proper gain values. After that, good data can be collected. Gain and Filter Frequency settings for each axis are stored for each recorded frame.
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Enable/Disable
Enable/Disable the recording process. This control is active only when data acquisition is stopped. Click Start to begin recording. The recording process stops once the allocated frame buffer is filled. When the Data Recorder is enabled, the software computes and allocates the necessary buffers. Refer to the table below for memory allocation for minimum Sampling Resolution at different head Scan Rates. After scanning is complete, scanned data can be reviewed and saved as long as the Data Recorder remains enabled.
Head Rotation Rate [Hz] 20
10
5
2.5
1.25
Minimum Sampling Interval [m]
Memory allocation for one Scan [MB]
0.08542 0.04271 0.02136 0.01068 0.00534 0.7503 1.5005 3.0011 6.0021 12.004
Memory allocation for recorded Scans [MB]
100
75.027
150.054
300.107
600.215
1200.429
Review Frames
During the recording cycle Review Frames displays the number of frames collected in real time. After the recording stops it controls which data frame displays.
Use the arrows or enter a frame number to choose a frame to display with its results.
5.3.10
Computations Ribbon
The Computations ribbon is used to enable and control what computed items appear in the Results window, and how some items are calculated. Enabling/Disabling results resets the statistics. Controls for the following are provided:
Define how statistics are calculated Select which results to display Choose a Beam Width Basis Enable the Gauss fit Select and setup the Divergence or Numerical Aperture results Program the system Magnification factor Adjust scaling for multiple ROI's with the beam rotation
transformation
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Statistics
Determines how the statistics are computed and can stop results updating if a Finite mode is selected.
Mode Continuous Rolling Finite
Count Reset Beam Width Method
13.5%
Sets the statistics results operating mode. The Status bar indicates the Sample Count that is currently used in formulating the displayed statistical results.
Sets the statistics for continuous calculations based on all collected frames of data.
Sets the calculation of statistics based on a rolling average of the last N collected profiles. Set N in the Counts edit control. Rolling mode is the default with a count of 16. Sets the calculation of statistics to stop ater a specified number of collected frames.
Note: The display views continue to update in real-time after the statistics have stopped.
Sets the number of Rolling or Finite frames on which to compute and display statistical results.
While running, resets the statistical results and automatically restarts statistics calculations. When stopped, resets only the results.
Enable/Disable beam width calculated results items and select which Beam Width Method to apply to secondary calculations. Controls are common for multiple ROI's.
Enable/Disable the 13.5% of Peak beam widths in the Results window. For TEM00 beams this yields the 1/e² second moment beam widths.
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50% (FWHM) D4sigma % Peak 1 % Peak 2 BW Basis
Position
Enable/Disable the 50% of Peak (Full Width Half Max) beam widths in the Results window.
Enable/Disable the second moment ISO Standard 11146 D4 beam widths in the Results window.
Enable/Disable the first user programmable % of Peak beam widths in the Results window.
Enable/Disable the second user programmable % of Peak beam widths in the Results window.
Select which beam width result to apply to secondary calculations such as Divergence and Ellipticity. This also selects which beam width result is displayed in the Profile views when in Single ROI mode.
Enable/Disable spatial position results for beam Centroid and profile Peak locations. Controls are common for multiple ROI's.
Centroid Peak Separation Centroid Peak
Enable/Disable the computed Centroid positions of the beam profiles in each enabled ROI.
NOTE: If Rotation Transform is enabled in the Computations Ribbon, Centroid Position results may not be valid.
Enable/Disable the Peak positions of the beam profiles in each enabled ROI.
NOTE: If Rotation Transform is enabled in the Computations Ribbon, Peak Position results may not be valid.
Enable/Disable the spatial separation distances for multiple beams when using multiple ROI's. Separation distances are only calculated between adjacent ROI's. No results appear in Single ROI mode.
Enable/Disable the computed Centroid separation distances between all of the enabled ROI profiles.
Enable/Disable the profile Peak separation distances between all of the enabled ROI profiles.
NOTE: If Rotation Transform is enabled in the
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Additional Results
Computations Ribbon, Peak Separation results may not be valid.
Enable/Disable additional result items. Controls are common for multiple ROI's.
Peak [cnts] Ellipticity
Pulse Rate Gauss Fit Divergence/ Numerical Aperture Divergence/NA
Enable/Disable the beam Peak in each enabled ROI. Previously known as Irradiance, the values are a magnitude of the observed profile peaks in raw digitizer counts. They are not calibrated power or energy densities.
Enable/Disable the beam Ellipticity result for each enabled ROI. This calculation is performed using the selected Beam Width Basis described above.
Ellipticity is only meaningful if the scan axis is aligned with the major and minor axes of the beam. This is usually not the case in multibeam analysis. Ellipticity is computed by dividing the smaller beam width by the larger (dmin/dmax). Values approaching one (1) indicate the beam is circular.
Enable/Disable the measured Pulse Rate (kHz) in the Results window when operating in Pulsed mode. If the pulse rate is indeterminate, a value of 0 is displayed. This result is not functional when operating in CW capture mode.
Enable/Disable the Gauss Fit results for each enabled ROI. Gauss fit results are calculated using a Least Squares Fit method and displays a Goodness of Fit and a Roughness of Fit value for each profile in the Results window.
Enable and control the Divergence and Numerical Aperture results.
For Divergence calculations, the beam width employed is determined by the selected Beam Width Basis (described above). For NA, a special programmed Clip Level must be employed.
Enable/Disable the Divergence/NA results for each enabled ROI. This control is common for multiple ROI's.
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Method
Clip Level Distance Focal Length Scaling
Select which divergence method or NA result to calculate. Lens results are in mrad, Point Source results are in degrees, and Numerical Aperture results are dimensionless. See section 4.4.7.1 for more details on the Divergence/NA methods.
Used for NA calculations. Enter the % of Peak Clip Level to use in making the Numerical Aperture measurement. For fiber optic measurements, the industry standard clip level is 5%.
Used for both Point Source divergence and NA calculations. Enter the distance between the source and the NanoScan2 measurement plane in millimeters.
Used for the Lens divergence calculation. Enter the focal length of the lens in mm.
This panel allows for rescaling the profile image and to adjust for multiple ROI beams which are placed rotated to the normal X/Y axial orientation.
Mag Factor Transform Angle
Sets the magnification factor when using magnifying optics for beam profiling. When used with external imaging optics, the spatial results can be rescaled to indicate beam image expansion or reduction. Acceptable values are between 0.01 and 300. The default setting is 1.
The beam centroid values are computed along the scanhead axes (default coordinate system). The Transform Angle determines a new coordinate system, which is used for computing the Centroid position and separation. When the scanhead is rotated to accommodate a series of multiple ROI's, correct the spatial distance measurements by entering the rotation angle in degrees. Acceptable angles are between 0 and 180 degrees. 45 degrees is the preferred angle to use whenever possible. This entry only corrects the measured distances if Rotation Transform is enabled (see below).
NOTE: Peak results are not affected by the Transform Angle and therefore peak results may
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Rotation Transform
not be valid if Rotation Transform is enabled.
Enable/Disable rotation transformation spatial correction based on the above entered Transform Angle.
Power Ribbon
The Power ribbon controls define power calibrations for single or multiple lasers. With this option, the user can manually calibrate the scanhead for power mea5s.u3r.e1m1 ents of CW lasers.
For example, an Ophir power meter is used to calibrate a HeNe laser to 5mW. A calibration point is set in NanoScan v2 and the following results are produced:
Each saved calibration is stored in the scanhead's EEPROM with a maximum of 256 possible calibrations. A calibration entry contains a Reference power value, a Wavelength, and a Descriptor title. This ribbon allows the user to create and store a calibration, and select which calibration to apply.
Results
Enable/Disable Power Results in the Results window.
Total Power
% Power Power Calibration Selection
Descriptor
Enable/Disable the measured beam Total Power in the Results window. At least 1 calibration file must be generated for the Total Power measurement to operate.
Enable/Disable the calculated power in each enabled ROI as a percent of the total power in the Results window.
This panel selects which calibration set point is used in measuring the laser beam's power. A newly created set point becomes the current set point. This panel can also be used to delete a previously stored set point.
Displays the title of the selected calibration entry.
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With multiple calibrations, use the dropdown list to selected a different calibration entry.
Wavelength
Displays the wavelength of the current calibration in nm.
Reference
Displays the calibration reference power used when the entry was created.
Delete
Permanently deletes the selected calibration entry from the scanhead.
Create Calibration Point
This panel is used to create calibration entries for various operating conditions.
Descriptor
A text field for entering a unique title name for the new calibration. Maximum 32 characters. The Descriptor must be different for each calibration entry. If a new calibration is created with the same title as a previous entry, an information message displays. Clicking Yes overwrites the previous calibration.
Wavelength Reference Power Units Calibrate
A text field for entering the wavelength in nm, applicable to the new calibration.
A text field for entering the new calibration reference power value. The units are selected from a dropdown menu.
Enter the applicable power units for the new calibration. Changing the units also changes the power units in the Total Power results.
Creates and saves a new calibration entry based on the above settings. There should be a separate calibration for each laser wavelength and setup variation.
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Charts Ribbon
The Charts ribbon enables charting of select results items. Multiple Time Charts can be viewed and run simultaneously. Both Axis X and Axis Y are plotted on each chart. 5.3.12
Time Charts
Result View Chart
This panel is used to manually create time charts of result items. Charts are only available in Single ROI mode.
Select the result for a new chart.
Displays the time chart with the selected result. See below for more details.
Note: The Gaussian Fit Time Chart only plots if the Gauss Fit result is enabled in the Computations ribbon and the chart only shows the Goodness of Fit results.
5.3.12.1
Charts View
The Charts view displays strip charts for select beam results. Any of the available beam results may be viewed this way. Multiple time charts can be created and run simultaneously. Charts are only available in Single ROI mode. Refer to section 5.3.4 to set the software in Single ROI mode. Charts behave similarly to the other view displays. They can be set to docking or floating as described in section 5.2.
If a chart is closed, it is hidden from view but retains all information. The chart can be reopened by selecting the result in the Charts ribbon and clicking View Chart. Chart data is not saved when loading an *.nsd or *.nsdx file. However, data can be saved by clicking the Copy to Clipboard icon in the chart's toolbar and transferring it to a different program.
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Options for the Time Charts view are selected in the Charts menu located at the top of each chart display. Options need to be set for each chart individually.
Updating
/
Rate
Units Samples
Start/Stop the data collection in the selected chart.
Select the update rate of the chart. Update rate limits change depending on the update unit selection: 1-10 for updates/sec, 1-60 for updates/min and updates/hour.
Select the unit for the chart. Available selections are: /sec, /min, /hour.
Selects the rolling buffer size for the chart. If the buffer is set to N samples, when sample N+1 is acquired, the first sample is dropped and the last
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Set Clear
acquired sample is added to the chart. A minimum of 10 samples must be entered.
Validates all Update settings. This clears any collected data.
Clears all data in the selected chart.
Some of the chart formatting features can be accessed through each chart's toolbar or context menu:
Copy To Clipboard
Palette Selector Zoom
Provides the option to copy the chart as a Bitmap image or as a Metafile. An option is also available to copy the chart data of all points. Once copied, the image or data can be transferred to a different program and pasted.
Provides a selection of color schemes to be applied to the entire chart.
Toggles the chart zoom control allowing click-and-drag zoom. This control allows viewing the value and time of each sample.
The context menus provide many of the same features found in the toolbar.
Depending on where in the chart the user right-clicks, a different context menu is provided.
5.3.12.2
Chart Background Context Menu
Right clicking in an empty chart space opens the general context menu. Options provided in this menu affect the entire chart. For example, changes made using "Font..." apply the font changes to the entire chart.
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Point or Series Context Menu
5.3.12.3
Right-click on a particular point or series to open a limited context menu. This menu provides options to change the gallery type and color of the series as well as enable point labels and open a properties dialog specific to the selected series.
5.3.12.4
Axis Context Menu
Right-click on the labels of an axis to open an axisspecific context menu. This menu is used to configure an axis title, change the font color, or open a properties window specific to the axis.
5.3.13
Logging Ribbon
The Logging ribbon is used to select and control results logging into an ASCII text file.
File Name File Name Browse
This panel is used to create a logging file name and select the save location.
Enables data logging into a user specified named text file with a file extension of *.log. Displays the current or last used log file name. Folder path is preserved from the previous use.
Allows navigation of file directory for save location and filename. If a previously saved log
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Logging Rate
file is selected, the new data is appended. If no location is specified, the file is saved in the users Documents folder. It is recommended that a NanoScan folder be created in the users Documents folder for saving *.log, *.nsdx, and *txt files.
This panel controls the logging rate.
Rate
Units Logging Format
Delimiter Date Time Results ROI
Enter the desired logging rate. If the rate Units is /sec the maximum update Rate is the current scan rate of the head. If the Units is /min or /hour, the maximum Rate is 60. The minimum Rate is 1 for all unit settings. If the min/max rate is exceeded, logging proceeds at the applicable min/max rate.
Select the time Units for the log rate. Available values are /sec, /min, /hour. Rates set for /min and /hour divide the time period into equal periods based on the set rate. Example: 6/hour save one log record every ten minutes.
Select the log format and log items. Log records are created for each frame of computed results and appended to the log file. The first entry in a log file will be the titles of the results in the following entry records.
Selects the delimiting character used between the results entries in the log record: comma, semicolon, space, or tab.
Start each log record entry with a date stamp indicating the date that the results were collected.
Place a time stamp indicating the time that the results were collected.
When selected, beam computed results enabled in the Computations ribbon are included in the log file in the order they appear in the Results window.
When selected, the current ROI boundaries are included in the log file for each enabled ROI.
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Logger Control
Enable/Disable results logging to the specified file name. Log files are appended if a new file name is not specified between logging operations. This control is disabled until a File Name has been entered.
M2 Ribbon
An M2 Wizard button is provided to initiate a script that will walk through the M² measurement process. The Rail Control panel can be used to connect and 5.3.c1o4ntrol an optional Photon NanoModeScan RailScan automated translation table.
Part No. Model
Description
PH00078 RSP100 RailScan motion stage, 100mm length
PH00080 RSP500 RailScan motion stage, 500mm length
PH00443
NS2- RailScan motion stage, 500mm length for RSP500 NanoScan2
Communication with the RailScan is established through a selected serial COM port. It allows the operator to move the scanhead to a desired position along the rail, or by using the provided NanoModeScan software; make these measurements automatically.
Note that the use of the automated translation table is optional and movement may be performed manually using an optical rail and a user provided lens. Alternately, an optional Rayleigh Range Translation test fixture, part number PH00073, model RAL-FXT, can be substituted for a user provided optical rail. See section 5.3.15 for operation with the RAL-FXT. Consult your local OphirSpiricon sales representative for the solution that is best suited for your needs.
Rail Control COM Port
Operation with a RailScan
The software generates a list with all available COM ports on the system. Make sure the rail system is connected to one of these ports and then select the appropriate COM port in the dropdown menu.
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Rail Length Connect
Select the Rail Length in mm. Available rails for the rail system are 100 and 500mm. A 200mm option remains for users with an older 200mm rail.
Establishes communication to the rail system through the selected COM port. Make sure the Motion controller is connected to the COM port and Rail system and is turned on before selecting this option. An error message displays if the software cannot connect to the rail's motion controller.
Disconnect Position [mm] Go Home
Check the connections and the COM port connection and try again. After the software connects to the motion controller, the Disconnect button and rail controls become active. COM Port and Rail Length selections are not available while the software is connected to the rail system.
Closes the COM port connection to the motion controller and disables the rail controls. When the motion controller is disconnected, the scanhead moves to the Home position.
Enter the desired position of the scanhead along the Rail in millimeters. Note that this position is not the distance from the scanhead to the lens principle plane.
Sends the scanhead to the above specified Position.
Sends the scanhead to the home position (0mm) and checks if the home position was reached successfully. Always send the rail to the home position for accurate calibrations. If the scanhead does not reach the home position, an error message appears.
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The RailScan is equipped with two limit switches, one at each end of the rail. If one of the limit switches is tripped, an error message appears. Follow the procedure outlined in the error message to reset the system.
5.3.15
M2 Wizard
The M2 Wizard is an interactive program for determining the "times diffraction limit" factor, M2, by the Rayleigh Method. M2 is also known as the "beam propagation" factor. The M2 Wizard view prompts and guides the user through a series of measurements and data entries required for calculating M2. The
entered and calculated values are displayed in each step of the Wizard.
The M2 Wizard view includes a few buttons and options for controlling the measurement.
Next
Advances to the next step in the Wizard. This button becomes available when all measurement required data has been entered.
Previous Start Over
Displays the previous step in the Wizard for modifying measurement data.
Restarts the M2 Wizard. All computed data is lost. This is only displayed on the last page of the Wizard.
Measurement Summary
Displays the measurement data for all the steps. In the final step, M2 is computed and
displayed here.
BeamWidth
Selects the beam width computation method used in the measurement:
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Wavelength [nm]
13.5% of Peak the 13.5% of Peak (1/e²) clip level dslit width is used for computations
D4sigma the ISO Standard 11146 D4 beam width is used for computations
This selection can be made only in the first step of the Wizard.
Enter the laser wavelength in nanometers. The laser wavelength is used in the computation of M2.
This selection can be made only in the first step of the Wizard.
Setup the laser and sensor so that you can easily move the sensor along the Zaxis (nearer or farther from the laser), then start the M2 Wizard. Follow the instructions that appear. Upon completing each step, select the Next button to continue. If you make a mistake select the Previous button and redo that step. After each step, the wizard updates the Measurement Summary. When the measurement is completed the data can be printed as a report or saved in the NanoScan2 file format. Refer to section 5.3.2 for printing, file saving, and loading.
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The formula is:
M2
D2 min
2 2Zr
where:
Zr
Zmax Zmin 2
Rayleigh length Wavelength
Dmin Beam diameter at the beam waist
Zmax Distance along Z axis where beam diameter is
1.414 Dmin 2Dmin
Zmin Distance along Z axis on the other size of the
where beam diameter is 1.414 Dmin 2Dmin
waist
Measuring M2
5.3.1M5.21 is a propagation constant for a laser source defined in the ISO standard as:
M2
D2 min
2 2Zr
Physically, M2 can be thought of as a factor times the diffraction limit. For
example, if one calculates the diffraction limit for a particular lens, the source with an M2 =1.2 will produce a spot width 1.2 times the theoretical calculated
value.
The ISO standard requires 10 beam measurements and a curve-fitting algorithm. A faster method, called the Rayleigh method, provides accurate result with only 3 measurements.
The Rayleigh Method can easily be derived from the definitions and gives fast, highly accurate, and repeatable M2 values. This method requires you to
measure twice the Rayleigh length for a source. A long focal length lens (high
5.3.1F5.#2 20) should be used. You also need the wavelength and the minimum observed beam width, Dmin, while sweeping through the beam waist.
Lens Selection and the Expected Rayleigh Length We have found that the distance along the beam axis can be measured to the
nearest ½mm if one selects a focused beam size from 80m to 200m 1 e2
beam width. Example:
Source nearly collimated wavelength 0.7m and approximate exit beam width is
500m 1 e2 .
The divergence for a diffraction limited source ( M k 1 ) is:
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4 ; D
We can select the lens by assuming: d f
4 0.7 0.0018rad 500
Or, if we want the predicted waist diameter d near the focal plane to be 125m, the required focal length is:
f 125 69,444 m or 69mm 0.0018
Let's use a 75mm lens, which is more commonly found in a laboratory. The expected spot size is:
d f 75,000 m0.0018 135 m .
The expected Rayleigh length in the region of the waist is:
Z d2 4
where d is the above 135m calculated spot width.
Z 0.78541352 20,448 m or 20.4mm 0.7
Thus we have a rough starting point for M2 measurements. If M2 is much greater
than 1.0, the spot size will be larger than calculated and the Rayleigh length will
be less than calculated. What is important is that by using the diffraction-limited
case, one has a starting point. We suggest that one try this method with a small, visible HeNe laser which is nearly always close to M2=1 to gain an
appreciation for the method before trying an unknown source. If you get an M2
value close to 1 with the HeNe source, you will have the measurement method
understood! Although theoretically M2 1, it is possible to get values slightly less than 1 due to beam diameter measurement errors. If you get M2 values
5.3.1se5ing.o3nuigfihcatontallylo<w1t.h0e
recheck software
alignment as well as go through the time to pick the correct minimum waist.
waist
slow
Alignment
To measure M2, it is necessary to move the scanhead along the optical axis of the beam through the beam waist. This alignment along the optical axis is extremely important for getting accurate results.
5.3.15.3.1 Rayleigh Test Fixture accessory
Ophir-Spiricon offers an accessory called a Rayleigh Translation Test Fixture (PH00073 RAL-FXT), which consists of a base plate, a slide that allows manual axial [Z] translation of the scanhead, and an LCD measurement ruler. The base plate is rigidly mounted to an optical table or rail. The translation distance
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readout is a Mitutoyo LCD ruler that spans 150mm of travel and gives position values to the nearest 25m. The total 150mm travel allows the Rayleigh range to be such that a beam waist of approximately 200m can be measured.
The Mitutoyo scale can be zeroed at the first Rayleigh location and translated to the second to find a single, direct read number in mm to be inserted into the wizard. This accessory's purpose is to make measurements of the Rayleigh range very easy and very repeatable. The user provides a source, a focusing lens, and a mount.
5.3.15.3.2 Alignment of the sensor and laser beam without the focusing lens:
Before inserting the lens into the path, align the sensor axial travel motion parallel to the axis of the laser. We suggest that the non-alignment be no more than a couple of beam widths. For the example laser above, this would be ±500m. The Pointing view can be used to measure the misalignment over the Rayleigh range.
For the example source (previous section) this means one should see no more than ±500m motion in either X or Y as one translates the sensor along the beam axis through a distance of 2Z (41mm for our example).
Note: Move slowly through the waist region so the software can keep up with the measurement process.
Record the Z-axis position in millimeters (mm). Be sure to move slowly as you approach the beam waist minimum. The software gathers multiple samples of minimum beam width to assure accuracy. The software automatically selects the minimum value. If you want to reset this minimum value, select the Reset button. Moving the scanhead too quickly through beam waist may cause errors.
Insert the lens:
Once the sensor and source are aligned, insert and center the lens into the beam path. Now, translate the sensor through the 2Z length and again try to keep the cross translation to less than ±1-2 beam widths. For the example beam, use the calculated 135m as a goal.
Be sure the lens is well centered or you will be measuring the lens aberration as well as the M2 for the source. With a visible source, one can usually observe a back reflection from both lens surfaces. Place the back-reflected beams just slightly to the side of the laser exit aperture. Sending the reflections back into the source may cause laser oscillations due to interference.
Another centering approach is to use a machine centered removable aperture stop just before the lens. This could fit into the lens mount during alignment and be removed before measurements. Direct the beam through this small aperture (our source example uses a 2mm hole) during alignment. Be sure to remove the stop once aligned in order to prevent truncation of the source and consequently errors in the measured M2.
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Now you are ready to use the M2 Wizard.
Dual Axis Measurements w/Astigmatism To measure M2 when the source is astigmatic, the user will need to modify the basic procedure slightly. Figure 5.1 shows what this looks like.
5.3.15.4
Figure 5.1
Measurement of Astigmatic Source Using the M2 Wizard.
Example:
1. Move the sensor to D Target for Profile X. Reset the Mitutoyo scale. Enter 0 for Z Position 1 under the Axis X heading.
2. Move the sensor to D Target for Profile Y. Enter 10 for Z Position 1 under the Axis Y heading. Select the Next button.
3. Move slowly through the waist for Profile X and verify the Dmin is correct.
4. Move slowly through the waist for Profile Y and verify the Dmin is correct.
5. Move the sensor to D Target for Profile X. Enter 24 for Z Position 2 under the Axis X heading.
6. Move the sensor to D Target for Profile Y. Enter 30 for Z Position 2 under the Axis Y heading. Select the Next button.
For more details, visit:
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http://www.ophiropt.com/laser-measurement-instruments/beamprofilers/knowledge-center/tutorial/measurement-solutions
Information can also be found by contacting your local Ophir-Spiricon representative.
5.4 Results Window
The Results window displays the values and statistics for calculated beam results selected using the Computations ribbon. Rows are organized first by ROI number, then by results item.
Column spacing can be modified by using the column controls in the Heading bar and the mouse. The font size of the Results window can also be changed. Set the focus to the Results window by clicking inside the window, then hold down the Control button on the keyboard and scroll with the mouse wheel or select Ctrl+(+) or Ctrl+(-). The status bar at the bottom of the screen displays the number of samples used in the Results window statistics. The number of samples and the display of beam results can be reset with the statistics reset button located in the 5.4.C1 omputations ribbon. Options for the Results window are selected using the Computations ribbon described in section 5.3.10.
Notes View
The Notes view is a text editor for entering test information, comments, and time stamping. The Time Stamp button adds the date and time to the end of the comments field. Multiple comments and time stamps can be added to the Notes view.
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Message Window
The Message Window displays message communications between the 5.4.2NanoScan2 scanhead and the NanoScan v2 application, and the time the event
occurred. If the scanhead is operating outside of normal operating parameters, an error message appears and will instruct the user on what is out of tolerance and may suggest actions that are needed in order to correct the situation. Only the last 100 messages are displayed with the most recent message on top. The Message Window can be closed, but it will reopen each time a new message is displayed. Below is a view of the Message Window showing typical operational messages.
5.5 NanoScan2 Status Codes
The following table contains hardware and device driver related status messages. NanoScan v2 software displays these messages in a dialog box that contains the following message:
"Code (Status code:). Contact Ophir-Spiricon"
Although most of the status codes indicate a hardware problem, some of them arise from bad connections between the PC's USB port and the scanhead. Some of the status codes only apply to the legacy NanoScan scanhead and controller board.
Status Code
-1 -2 -3
Description
An error occurred while opening the device driver. An error occurred while closing the device driver. The board is already in use by another program.
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Status Code
-4
-5 -6
-7
-8
-9
-10
-11 -12 -13
-14 -15 -16 -17
-18 -19 -20 -21
Description
A DMA read error occurred. The pointer to the data buffer is invalid, an error occurred in the communication with the device driver or a data transfer timeout (2 seconds) occurred. The function failed to allocate memory space. The head EEPROM cannot be read. This usually indicates a communication problem. Check all connections. An error occurred in the communication with the NanoScan2 scanhead. Check USB and scanhead connections. An error occurred in the communication with the NanoScan2 scanhead. Check USB and scanhead connections. An error occurred while reading the head EEPROM. EEPROM information may be corrupt, or there may be a problem in the EEPROM communication interface. Check all scanhead connections. Ophir-Spiricon can provide a utility for reprogramming the EEPROM in the field that may solve the problem. The selected EEPROM descriptor cannot be found in the head EEPROM. One of the parameters passed to the function is not valid. An error occurred in the communication with the device driver. Power Calibration could not be saved to the head EEPROM. This usually indicates a communication problem or a faulty EEPROM. The head scan rate cannot be set with precision. Data acquisition cannot be started in the hardware. Data acquisition cannot be stopped in the hardware. An error occurred in the communication with the device driver. The motor cannot be started. The device driver could not set the head scan rate. The device driver could not read the head scan rate. The sampling clock divider could not be set. The retrieved sampling clock divider does not match the one set on the board.
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Status Code
-22
-23 -24 -25 -26 -27 -28 -29 -30 -31 -32 -33 -34 -35 -36 -37 -38
Description
Nominal baseline could not be determined. There are several causes for this, including detector failure, detector overheating with a high power laser, failure of the amplifier gain setting interface, and too much laser illumination incident in the aperture at program launch. If this error occurs, make sure the laser is blocked from entering the scanhead aperture and try restarting the software. If the system was used for high power laser profiling, let the scanhead cool down before restarting the software. If these attempts fail the unit likely needs to be returned. The acquisition mode could not be set. The acquisition mode does not match the acquisition mode set on the board. Acquisition channels cannot be enabled. The enable-acquisition value does not match the value sent to the board. Channel acquisition parameters cannot be set. The device driver cannot read the channel acquisition parameters from the board. Channel end position is beyond 360 degrees. Two of the defined acquisition channels overlap. First acquisition channel is disabled. The acquisition parameters set and retrieved to/from the NanoScan card do not match. Gain channels cannot be enabled. An error occurred in the communication with the device driver. The enable status of the gain channel cannot be retrieved. Gain channel (position) cannot be set. Gain channel (position) value cannot be retrieved. The gain value cannot be set. The gain value cannot be retrieved.
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6 Frequently Asked Questions
The following is a list of questions that might be useful during installation and/or operation of your NanoScan2. If you do not see a question/answer that fits your situation, please view the "Beam Profiler FAQ's" http://www.ophiropt.com/laser-measurement-instruments/beam-
profilers/services/faqs or fill out and submit the online "Ask an Expert" http://www.ophiropt.com/laser-measurement-instruments/beam-
profilers/services/ask-expert to Ophir-Spiricon Technical Support. We try to resolve your problems quickly but need your help. Please provide as many details as you can when you fill out the checklist. For example, "My scanhead (instrument) does not work" is fairly broad. Tell us what it does, or does not do, and include operating conditions and information as requested in the form. The more information you provide, the faster we can answer your questions. To determine a more definite cause for a specific symptom or problem, the instrument may have to be returned to our factory for a complete evaluation. Please obtain an RMA number before returning unit for calibration or repair. Q.1. Can I get an electronic copy of the manual? Yes, you already have one on your NanoScan v2 Installation CD. Look in Start, All Programs, Photon, NanoScan v2.0, Documentation.
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Q.2. Are there examples of ActiveX programs anywhere?
ActiveX support documentation and examples are included in your software and can be found in the Automation Folder of the software installation. Look on your hard disk in C:\Program Files (x86)\Photon\NanoScan v2.0\Automation if operating on a 64-bit machine or C:\Program Files\Photon\NanoScan v2.0\ Automation if operating on a 32-bit machine.
Q.3. Is there a Viewer for the NanoScan v2 data files?
No, this is not necessary. NanoScan v2 can run without a scanhead attached. You will get a warning message, but if you ignore this the software starts and allows you to view previously acquired data files.
Q.4. Can my NanoScan2 operate on a Mac
No.
Q.5. Can my NanoScan2 operate under Linux
No.
Q.6. What is the longest cable available for NanoScan2?
USB2 cables should be used with the standard length of 2 meters. Cables beyond this length have not been tested and a USB2 repeater with separate power supply is needed.
Q.7. Where is the detector in the NanoScan2?
The detector is mounted behind the slits. This position is not important to the measurements. The measurement plane is the scan plane of the slits which is nominally 1.1mm from the face of the front cap. Refer to the mechanical drawings in Appendix B for more detailed information.
Q.8. What is the smallest beam I can measure?
In general, the NanoScan2 can measure a beam that is 4x larger than the slit width without correcting for convolution error. For beams smaller than this you can either make mathematical convolution correction or use magnification to enlarge the beam. See section 4.4.10 for a discussion of convolution error or section 4.4.11 for information on the magnification with the near-field profiler.
Q.9. Can I measure multiple beams with the NanoScan2?
Yes, see section 5.3.4 for a discussion of the Regions of Interest (ROIs) and multiple beam analysis.
Q.10. What does "relative power meter" mean?
The power meter on silicon and germanium detector NanoScans is a "relative" measurement; which means the meter is not calibrated to an absolute standard in the factory. You need to measure the source with a calibrated power meter, and then input the value into the NanoScan v2 software. The NanoScan2 will then measure relative to this measured value.
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Q.11. Can I get a power meter option with a pyro NanoScan2?
Yes, power meter measurements are available using a pyroelectric detector with one caveat. The calibration is only valid at the same wavelength and head rotation speed at which the power was measured. See section 4.3.2.4.
Q.12. Why is the silicon NanoScan2 not recommended for 1064nm beam measurements?
The silicon detector is very transparent to NIR light >1000nm. If it is used for measuring these beams, you will often see a tailing profile because the signal does not decay fast enough. This will lead to erroneous results. We recommend using the germanium or, if there is enough power, the pyroelectric detector for these wavelengths.
Q.13. How can I increase the sensitivity of my NanoScan2?
It is sometimes possible to increase the detection of low level beams by using profile averaging to increase the signal-to-noise ratio. See section 4.4.4.6 for a description.
Q.14. The signal is oscillating in my NanoScan v2 display; what could be the cause?
Back reflections from the slits can cause the laser to become unstable. You can tip the scanhead slightly to make sure that reflections do not feedback into the laser cavity. See section 4.4.6.
Q.15. What is the largest angle of incidence I can measure with the NanoScan2?
The NanoScan2 can measure up to 45o under most circumstances. See section 4.4.7 for a detailed discussion of divergence and angle of incidence.
Q.16. How do I measure divergence?
The NanoScan v2 software has several divergence measurement methods available. See section 4.4.7 for a detailed discussion of divergence measurement.
Q.17. How can stray light impact the NanoScan2?
Both silicon and germanium detectors are quite sensitive. Stray light in the visible or NIR wavelengths are present in most settings and they will be detected by the detectors, raising the background. This can have an effect on the accuracy of the measurement by changing the baseline of the beam profile. You should be sure to shield the scanhead from sources of light other than those you are intending to measure.
Q.18. Pulsed laser operation with the NanoScan2
The NanoScan2 will measure pulsed lasers, provided that the pulse rate is high enough to get a decent profile. This is discussed at length in section 4.1.5.
Q.19. Slit Damage Calculation
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Damage to the slits and detector of your NanoScan2 is always a possibility with higher power lasers. Care should be taken to ensure that the damage thresholds are never exceeded. Remember also that the smaller the beam diameter impinging on the slits, the lower the power or energy needed to damage the slit material. There is a slit damage calculator (an Excel spreadsheet) included on your software disk. This will help you determine if you are in danger off damaging the slits. If you do not have this spreadsheet, contact Ophir-Spiricon for a free copy. Remember, damage to the slits is never covered under warranty.
Q.20. Pulse Damage to NanoScan2 Slits
Pulsing lasers is a method of increasing the effect of the laser beam by concentrating the power into a short duration pulse. These pulses can have a very high peak power, despite the average power being quite low. This means that the energy delivered by the beam can cause damage, even if the average power would not, if the laser was CW. The important parameter to be aware of with pulsed lasers is the energy, measured in Joules and calculated as the average power divided by the frequency (E=p/). It is important to recognize that the energy increase as the frequency decreases. In other words a laser beam that is safe at 80kHz may damage the NanoScan2 if the frequency is reduced to 60kHz. The slit damage calculator (see Q.19) will indicate safe levels for both power of CW lasers and energy of pulsed lasers.
Q.21. Frequency measurement with the NanoScan2
Proper measurement of pulsed lasers requires the actual pulse rate be entered into the software. This number is not always the value that is suspected based on the laser's manufacturer's specification. In order to make these measurements work more smoothly the NanoScan v2 software measures the actual pulse rate. Enter this number into the software and the pulsed measurements will be more accurate.
Q.22. Why are there two types of pulsed modes with the NanoScan2?
There are two reasons that lasers are pulsed. One, discussed above, involves concentrating the energy in short pulses. The other uses pulsing to reduce the duty cycle of the laser to actually control the output power. The latter type, called pulse width modulation, generally has fairly long pulse durations, >1sec. We have found that the NanoScan2 amplifiers work differently with long pulses than with short ones, therefore we use two different algorithms for these different laser types.
Q.23. How can I export data from the NanoScan v2 software?
There are several ways to export data from NanoScan v2 to spreadsheets, math and statistical analysis programs, process/instrumentation control programs, or reports, papers, and other documents. Logging to files is described in the manual section 5.3.13. ActiveX communication is also available and is described at length in the Automation Developer Guide (see
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Q.2). Use the Save As option as described in section 5.3.2 for saving *.nsdx or *.txt files. Saving a screen capture to a file is an easy way to get figures for reports, papers, or other documents. Q.24. Status Code -9 This indicates that there is no scanhead recognized by the software. This can mean that either nothing is plugged in or that there is something wrong with the communication. One cause of this that can be fixed remotely is that the EEPROM in the scanhead has been erased by a transient, power surge, electrostatic discharge (ESD), or the like. Check all connections to the scanhead and if you continue to get a Status Code (error code) -9, contact Ophir-Spiricon to get the head data and reloading utility to reprogram the EEPROM. In most cases this will resolve the problem. Q.25. Status Code -22 This message was much more common with earlier software versions, prior to v1.31. If you get this message, first check to ensure that you are operating with a software version later than v1.31. If not, contact Ophir-Spiricon or your local distributor to obtain an updated version. If you have the right software version, then this message indicates that there is a problem with the detector and the system should be returned for repair. Contact Ophir-Spiricon or your dealer for an RMA.
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Appendix A Scanhead Specifications
NanoScan2 Scanhead Model
Si/3.5/1.8m
Si/9/5m
Si/9/25m
Wavelength
Detector
Entrance Aperture
Slit Size
Slit Orientation 1/e² Beam Diameter Range1 Spatial Sampling Resolution
190nm - 950nm Silicon 3.5mm 1.8m +45 and -45 7m ~2.3mm
5.3nm 18.3m
190nm - 950nm Silicon 9mm 5m +45 and -45 20m ~6mm
5.3nm 18.3m
190nm - 950nm Silicon 9mm 25m +45 and -45 100m ~6mm
5.3nm 18.3m
Profile Digitization
16-bit
16-bit
16-bit
Amplifier Gain Range 1-103dB
1-103dB
1-103dB
Filter Frequency Range 2 190kHz
2 190kHz
2 190kHz
Scan Rate
1.25, 2.5, 5, 10, 20Hz 1.25, 2.5, 5, 10, 20Hz 1.25, 2.5, 5, 10, 20Hz
Power Aperture
Standard
Standard
Standard
Power Aperture OD
Metallized Quartz (200mW)
Metallized Quartz (200mW)
Metallized Quartz (200mW)
Laser Type
CW or Pulsed2
CW or Pulsed2
CW or Pulsed2
Operating Range Damage Threshold Rotation Mount Scanhead Dimension
See Operating Space Chart in Appendix C of User's Manual See Operating Space Chart in Appendix C of User's Manual Standard see drawing in Appendix B of User's Manual See Mechanical Drawing in Appendix B of User's Manual
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
1Assumes Gaussian (TEM00) Beam 2Pulsed Operation Limited to Beam Diameter >100m and pulse repetition rate 5kHz.
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NanoScan2 Scanhead Model
Ge/3.5/1.8m
Ge/9/5m
Wavelength
700nm - 1800nm
700nm - 1800nm
Detector
Germanium
Germanium
Entrance Aperture
3.5mm
9mm
Slit Size
1.8m
5m
Slit Orientation
1/e² Beam Diameter Range1 Spatial Sampling Resolution
Profile Digitization
+45 and -45 7m ~2.3mm 5.3nm 18.3m 16-bit
+45 and -45 20m ~6mm 5.3nm 18.3m 16-bit
Amplifier Gain Range 1-73dB
1-73dB
Filter Frequency Range 2 190kHz
2 190kHz
Scan Rate
1.25, 2.5, 5, 10, 20Hz 1.25, 2.5, 5, 10, 20Hz
Power Aperture
Standard
Standard
Ge/9/25m
700nm - 1800nm Germanium 9mm 25m +45 and -45 100m ~6mm 5.3nm 18.3m 16-bit 1-73dB 2 190kHz 1.25, 2.5, 5, 10, 20Hz Standard
Power Aperture OD
Metallized Quartz (200mW)
Metallized Quartz (200mW)
Metallized Quartz (200mW)
Laser Type Operating Range Damage Threshold Rotation Mount Scanhead Dimension
CW or Pulsed2
CW or Pulsed2
CW or Pulsed2
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
1Assumes Gaussian (TEM00) Beam 2Pulsed Operation Limited to Beam Diameter >100m and pulse repetition rate 5kHz.
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NanoScan2 Scanhead Model
Pyro/9/5m
Pyro/9/25m
Wavelength
200nm - 20µm
200nm - 20µm
Detector
Pyroelectric
Pyroelectric
Entrance Aperture
9mm
9mm
Slit Size
5m
25m
Slit Orientation
1/e² Beam Diameter Range1 Spatial Sampling Resolution
Profile Digitization
+45 and -45 20m ~6mm 5.7nm 18.3m 16-bit
+45 and -45 20m ~6mm 5.7nm 18.3m 16-bit
Amplifier Gain Range 1-85dB
1-85dB
Filter Frequency Range 2 190kHz
2 190kHz
Scan Rate
1.25, 2.5, 5, 10, 20Hz 1.25, 2.5, 5, 10, 20Hz
Power Aperture
N/A
N/A
Power Aperture OD Laser Type Operating Range Damage Threshold Rotation Mount Scanhead Dimension
N/A
N/A
CW or Pulsed2
CW or Pulsed2
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
See Operating Space Chart in Appendix C of User's Manual
See Operating Space Chart in Appendix C of User's Manual
Standard see drawing in Appendix B of User's Manual
See Mechanical Drawing in Appendix B of User's Manual
1Assumes Gaussian (TEM00) Beam 2Pulsed Operation Limited to Beam Diameter >100m and pulse repetition rate 5kHz.
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Appendix B Mechanical Dimensions
NanoScan2*
Mechanical Dimensions
NanoScan2* Standard Scanhead NS2-Si, NS2-Ge, and NS2-Pyro
*See below for NanoScan2s and NanoScan2sB mechanical dimensions
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NanoScan2s and NanoScan2sB
Mechanical Dimensions
NanoScan2s and NanoScan2sB Standard Scanhead NS2s-Si, NS2s-Ge, NS2s-Pyro, NS2sB-Si, NS2sB-Ge, and NS2sB-Pyro
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Appendix C Operating Space Charts
Operating Ranges are for the Peak Detector Responsivity Operating Spaces are NOT absolute
THESE CHARTS TO BE USED AS A GUIDE ONLY
The following information is a guide to reading the charts pertaining to Silicon detectors.
Silicon Detector: Responsivity varies with wavelength. Detects between 400-1100nm. Peak responsivity is 0.7 amps/watt at 980nm. Detector to detector responsivity variation can be as great as ±20%.
Power: Average power in the laser beam.
Beam Diameter: Assumes a round beam. The operating point for an elliptic beam can be approximated by using the average diameter. For extremely elliptic beams (ratio >4:1), contact Ophir-Spiricon.
Pulsed Operation ( measurements.
): Upper limit of the operating space for pulsed laser
Black Coating Removed (
): Slits are blackened to reduce back reflections;
blackening begins to vaporize near this line. Slits in pyro detectors are not blackened.
Slit Damage (
): Power density (watts/cm2) where one can begin to ablate and
cut the slits. Refer to Ophir-Spiricon's Damage Threshold with High Power Laser Measurements
document.
Left Boundary: The left boundary is 4 times the slit width, where slit convolution error becomes significant to the 5% level for reported 1/e2 diameter of a TEM00 Gaussian beam.
Right Boundary: The right boundary is the instrument entrance aperture diameter, which determines the largest beam profile and diameter that can be measured. For a TEM00 Gaussian beam the1/e2 diameter needs to be 1/2 the aperture diameter to measure and see the entire profile out to the tails. Similarly for a Flat-top distribution the 1/e2 diameter needs to be ~95% of the aperture diameter. To obtain any given clip level diameter for any beam (but not the full profile) ~95% of the aperture is useable.
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 128
Silicon/3.5mm/1.8m Silicon/9mm/5m
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 129
Silicon/9mm/25µm
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 130
The following information is a guide to reading the charts pertaining to Germanium detectors.
Responsivity: Detector converts constant, incident photons to a current.
Germanium Detector: Responsivity varies with wavelength. Detects between 800-1800nm. Peak responsivity is 1.05 amps/watt at 1550nm. Detector to detector responsivity variation can be as great as ±20%.
Power: Average power in the laser beam.
Beam Diameter: Assumes a round beam. The operating point for an elliptic beam can be approximated by using the average diameter. For extremely elliptic beams (ratio >4:1), contact Ophir-Spiricon.
Pulsed Operation ( measurements.
): Upper limit of the operating space for pulsed laser
Black Coating Removed (
): Slits are blackened to reduce back reflections;
blackening begins to vaporize near this line. Slits in pyro detectors are not blackened.
Slit Damage (
): Power density (watts/cm2) where one can begin to ablate
and cut the slits. Refer to Ophir-Spiricon's Damage Threshold with High Power Laser
Measurements document.
Left Boundary: The left boundary is 4 times the slit width, where slit convolution error becomes significant to the 5% level for reported 1/e2 diameter of a TEM00 Gaussian beam.
Right Boundary: The right boundary is the instrument entrance aperture diameter, which determines the largest beam profile and diameter that can be measured. For a TEM00 Gaussian beam the1/e2 diameter needs to be 1/2 the aperture diameter to measure and see the entire profile out to the tails. Similarly for a Flat-top distribution the 1/e2 diameter needs to be ~95% of the aperture diameter. To obtain any given clip level diameter for any beam (but not the full profile) ~95% of the aperture is useable.
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 131
Germanium/3.5mm/1.8m Germanium/9mm/5m
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 132
Germanium/9mm/25µm
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 133
The following information is a guide to reading the charts pertaining only to Pyroelectric detectors.
Pyroelectric Detector: Uniform in response between 0.2 and 20 microns wavelength.
Power: Average power in the laser beam.
Beam Diameter: Assumes a round beam. The operating point for an elliptic beam can be approximated by using the average diameter. For extremely elliptic beams (ratio >4:1), contact Ophir-Spiricon.
Pulsed Operation ( measurements.
): Upper limit of the operating space for pulsed laser
Slit Damage (
): Power density (watts/cm2) where one can begin to ablate and
cut the slits. Refer to Ophir-Spiricon's Damage Threshold with High Power Laser Measurements
document.
Left Boundary: The left boundary is 4 times the slit width, where slit convolution error becomes significant to the 5% level for reported 1/e2 diameter of a TEM00 Gaussian beam.
Right Boundary: The right boundary is the instrument entrance aperture diameter, which determines the largest beam profile and diameter that can be measured. For a TEM00 Gaussian beam the1/e2 diameter needs to be 1/2 the aperture diameter to measure and see the entire profile out to the tails. Similarly for a Flat-top distribution the 1/e2 diameter needs to be ~95% of the aperture diameter. To obtain any given clip level diameter for any beam (but not the full profile) ~95% of the aperture is useable.
Pyroelectric/9mm/5m
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 134
Pyroelectric/9mm/25m
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 135
Index
±2% accuracy...........................................................33 13.5% Clip Level Illustration .....................................26 2D/3D View .........................................................72, 86 Absolute Accuracy....................................................63 Accuracy ................. 9, 29, 43, 48, 50, 51, 54, 91, 112 Accuracy Requirement .............................................33 ActiveX ............................................... 10, 12, 119, 121 Alignment ......................................... 51, 111, 112, 113 Amplifier Gain ......................41, 51, 53, 123, 124, 125 Angle of Incidence ....................................................55 Angular Alignment ....................................................50 Attenuation............................................. 10, 40, 46, 59
Back Reflections ...............................................54 Auto Filter..................................................................34 Auto Find...................................................................80 Auto Hide ..................................................................70 Automatic ROI Mode ................................................75 Average Laser Irradiance .........................................37 Averaging ............................................................32, 54 Axis X ........................................................................82 Axis Y ........................................................................82 Back Reflections ...................................... 54, 128, 131 Bandwidth .................................................................53 Beam Attenuation .....................................................59 Beam Divergence ...............................................11, 55 Beam Pointing .........................................See Pointing Beam Position .......................................... See Position Beam Profile9, 10, 27, 32, 33, 48, 51, 59, 61, 81, 85, 89 Beam Separation......................................................11 Beam Width9, 25, 26, 27, 29, 51, 55, 58, 60, 61, 75, 80, 82, 96, 108, 110, 111, 112
Analysis Methods..............................................25 Measurement Methods .....................................27 Calculating the Minimum Beam Diameter ...............33 Calibration ...................................................... 9, 13, 43 Care of NanoScan2 Slits ..........................................36 Centroid............................................ 54, 88, 89, 96, 97 Centroid Position ......................................................11 Charts View.............................................................101 Clip Level ............................................................58, 98 Comparison Beam Width Measurement Methods.................27 Encircled Energy Method..................................28 Knife Edge ........................................................28
Measurement Methods .....................................27 Pinhole .............................................................. 28 Second Moment Method...................................28 Slit .....................................................................28 Controller................................................................ 107 Convolution .................................................. 42, 48, 60 of Slits and Small Beams ..................................59 Damage................................12, 14, 37, 39, 40, 41, 43 Damage Threshold ..........................36, 37, 38, 39, 41 of Slits ............................................................... 36 Data Collection....................................................... 102 Data Recorder..................................15, 79, 80, 91, 93 Defining Instrument Zero ..........................................49 Defining Zero Position for Beam ..............................49 Detector 10, 25, 28, 40, 41, 42, 43, 45, 46, 51, 55, 64, 117, 128, 131 Warranty Information ..................................12, 36 Dimensions, Mechanical........................................ 126 Display Terminology .................................................67 Divergence ................................................... 56, 57, 98 Lens Method .....................................................56 Numerical Aperture Method .............................. 58 Divergence Method...................................................98 Dock Handles............................................................69 Drum Radius .............................................................52 Elliptic Beams ........................................ 128, 131, 134 Ellipticity ................................................. 11, 50, 51, 97 Enable/Disable Data Recorder.................................94 Encircled Energy/Variable Aperture .........................28 Entrance Aperture10, 36, 41, 42, 44, 48, 49, 52, 55, 64, 89, 128, 131, 134 Zero Position for Beam .....................................49 Feedback ..................................................................55 Filter............. 11, 32, 51, 81, 82, 91, 93, 123, 124, 125 Filter Tracking .................................................... 53, 82 Fourier Transform .....................................................60 Front Cap ..................................................................44 FWHM .................................................... 26, 60, 61, 96 Gain ...................................................... 32, 91, 93, 117 Gain Tracking..................................................... 81, 91 Gaussian Beam ........................................................61 Gaussian Fit ....................................................... 11, 97 Head Scan Rate ..................................See Scan Rate High Power Beam.....................................................37
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Damage ............................................................36 Installation .................................................................15 Instrument Calibration ..............................................43 Irradiance ............................................................11, 97
Upper Limits......................................................37 ISO ...............................9, 10, 13, 26, 43, 96, 108, 110 ISO Standards
Clip Level ..........................................................26 on Pinhole Scans ..............................................25 Knife-Edge ................................................... 25, 26, 28 Knurled Knob ......................................................44, 46 LabVIEW...............................................................2, 12 Laser Oscillation .......................................................54 Laser Pulse Repetition Rate.....................................91 Laser Repetition Rate.................................. 32, 33, 91 Lens Method .............................................................56 Lens Selection ........................................................110 Logging ............................................................ 12, 104 M2 Measurements..................................................111 M2 View ..................................................................108 Magnification Factor .................................................98 Manual ROI Mode ....................................................76 Measured Pulse Rate...............................................97 Measurement Accuracy......................... 12, 13, 32, 91 Measurement Plane .............................. 49, 57, 62, 98 Measurements with Astigmatism ...........................113 Measuring M2 .........................................................110 Mechanical Dimensions ............................... 9, 65, 126 Microscope Objective Lens ......................................62 Minimum Sampling Resolution.................................94 Moving-Slit ................................................... 25, 26, 28 Multiple Beam Measurement ...................................63 NanoScan v2 Beam Profiling Software....................10 NanoScan2 Slits .......................................................36 Near-Field Source Profiling ......................................62 Numerical Aperture.............................................56, 58 Numerical Aperture Method .....................................58 Operating Space Chart..............41, 42, 123, 124, 125 Option H/I..................................................................62 Peak .................................28, 88, 89, 96, 97, 128, 131 Peak Connect Algorithm...........................................33 Peak Position............................................................11 Photo Detector..........................................................44 Pinhole ................................................... 25, 28, 29, 49 Point Source Method ................................... 56, 57, 58 Pointing ............................................................ 89, 112 Pointing Stability .......................................................11 Pointing View ............................................... 73, 88, 89
Position.................................49, 87, 96, 107, 113, 114 Position, Zero for Beam ............................................49 Power 11, 99, 100, 116, 123, 124, 125, 128, 131, 134
Units ................................................................ 101 Primary Dock Window ..............................................68 Profile Acquisition .....................................................51 Profile Averaging.................................... 47, 54, 91, 92 Profile View ................................72, 76, 78, 83, 84, 85 Profile X........................................76, 77, 83, 113, 114 Profile Y........................................76, 77, 83, 113, 114 Pulse Width Modulation...............................See PWM Pulsed Beam Profiling ..............................................32 Pulsed Beams.............................................. 32, 38, 39 Pulsed Laser Repetition Rate...................................11 Pulsed Mode .............................................................91 Pulse-to-Pulse Repeatability ....................................91 PWM..........................................................................38
Femtosecond ........................................32, 39, 40 Picosecond ........................................... 32, 39, 40 Pyroelectric Detectors...................................... 34, 125 Q-Switched Lasers ........................See Pulsed Lasers RailScan ................................................. 106, 107, 108 Rayleigh Length ..................................................... 110 Rayleigh Method ............................................ 108, 110 Rayleigh Range ..................................................... 112 Rayleigh Test Fixture............................................. 112 Reflections, Back ......................................................54 Regions of Interest...............................53, 66, 75, 106 Power ................................................................ 11 Relative Reflectivity of Slits.......................................41 Repetition Rate .........................................................40 Resolution ........................................ 15, 62, 80, 86, 98 Resolution Sampling Factor .....................................78 Results ...........................................11, 96, 97, 98, 105 Ribbon Bars 2D/3D ................................................................ 85 Capture ............................................................. 90 Charts ..................................................... 101, 102 Computations..............................................90, 94 Logging ........................................................... 104 Pointing ............................................................. 87 Power Meter......................................................99 Profiles .............................................................. 82 Regions of Interest (ROI) ..................................75 Source.........................................................78, 86 ROI ......................................... See Regions of Interest Rolling Profile ..................................................... 32, 54 Rotation Mount.................................46, 123, 124, 125
NanoScan v2 Installation and Operation Manual Document No. 50302-001 Rev G v2.6 2/26/2018 Page 137
Sampling Resolution.................................................80 Scan Rate ....................32, 33, 51, 52, 78, 79, 80, 105 Scanhead................ 9, 44, 49, 90, 123, 124, 125, 126
Alignment ..........................................48, 111, 112 Components...................................................... 43 EEPROM ..........................................................63 Operating Space .........................................12, 41 Positioning ........................................................48 Scan Rate .....................................See Scan Rate Specifications Table..........................................64 Theory of Measurement....................................28 Second Moment Method ..........................................27 Sensitivity ................................................................128 Setup NanoScan2 System .........................................9 Signal Filter ...............................................................53 Signal/Noise Ratio (SNR)............................ 32, 53, 54 Slit ............. 28, 31, 108, 123, 124, 125, 128, 131, 134 Blackened .........................................................37 Convolution ...........................................47, 48, 59 Damage ............................................................36 Damage Threshold ...........................................36 Graph, Slit Width Correction Data.....................61
Integrity ............................................................. 37 Unblackened .....................................................37 Warranty Information ..................................12, 36 Width ................................................................. 47 Slit Damage...............................................................36 Small Beams .............................................................45 Small Spot.................................................................62 Measurements ..................................................59 Software9, 10, 15, 16, 24, 49, 53, 75, 78, 81, 82, 106, 107, 111, 112, 115, 117 Spatial Sampling........................52, 80, 123, 124, 125 Spot Size .............................................. 33, 47, 81, 111 Standard Deviation ............................................ 27, 54 Stray Background Light ............................................59 Update Rate...........................51, 64, 86, 92, 102, 105 User Defined .............................................................49 Views............................................................ 76, 80, 83 Vignetting ..................................................................56 Visual Damage..........................................................37 Warranty............................................................. 12, 43
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