Overview
Product Description
The Thorlabs MRA05L-E03 is a Leg-Coated Right-Angle Prism Mirror featuring broadband dielectric coating for the 750 - 1100 nm spectral range. It has a leg length of 5.0 mm.
Features
- Right-Angle Prism with Dielectric-Coated Legs
- Broadband Dielectric Coating with average reflectance (Ravg) > 99% for 750 - 1100 nm
- Leg Length of 5.0 mm
This prism mirror is manufactured from N-BK7 glass and offers a clear aperture greater than 70% of the face length and width, excluding the beveled edge. The broadband dielectric coating performs well with both s- and p-polarized light over the specified range. It is ideal for near-normal and 45° reflections.
Application Idea
Our leg-coated prism mirrors can be used with a hollow roof prism mirror to create an optical delay line. This mirror can be used in optical delay lines to extend the path length in an optical system. The right-angle prism mirror allows counterpropagating beams to be made parallel with the output orthogonal to the input. For applications requiring orthogonal beam splitting or combining into a co-linear output, knife-edge right-angle prisms are recommended.
[Image Description: A right-angle prism mirror with a holographic label 'MRA05L-E03'. The prism has two legs coated with a dielectric layer, appearing iridescent. The hypotenuse is polished but not coated. An application diagram shows two such prisms arranged to create an optical delay line.]
[Diagram Description: Figure 1.1 shows a leg-coated prism mirror used to create an optical delay line.]
[Diagram Description: Figure 1.2 illustrates that the size of this prism is defined by the leg dimension, L.]
Product Status
This item will be retired without replacement when stock is depleted. For line production requirements, please contact the Thorlabs OEM Team.
Right-Angle Prism Mirror Selection Guide
| Coating Type | Description |
|---|---|
| Hypotenuse Coated | Metallic Coatings (250 nm - 20 µm) |
| Dielectric Coatings (400 nm - 1100 nm) | |
| Laser Line (532 nm and 1064 nm) | |
| Leg Coated | Knife-Edge, Metallic and Dielectric Coatings (250 nm - 20 µm) |
| Dielectric Coating (750 nm - 1100 nm) |
Specifications
[Diagram Description: Figure 2.1 shows the dimensions of a right-angle prism, indicating the leg length 'L' and hypotenuse length 'X'.]
[Diagram Description: Figure 2.2 illustrates a right-angle prism diagram, showing coated and uncoated surfaces.]
| Specifications | Value |
|---|---|
| Substrate Material | N-BK7a |
| Dimensional Tolerance | ±0.1 mm |
| Surfaces Flatness | λ/10 @ 633 nm (Peak to Valley) |
| Surfaces Quality | 10-5 Scratch-Dig |
| Clear Aperture | >70% of Face Length and Width |
| 45°-45°-90° Prism Angular Tolerance | ±3 arcmin |
| Item # | La | Xa | Reflectance (Click for Graph) |
|---|---|---|---|
| Broadband Dielectric Coating: 750 nm - 1100 nm | |||
| MRA05L-E03 | 5.0 mm | 7.1 mm | Ravg > 99% (750 nm - 1100 nm) |
a As Specified in Figure 2.1
Graphs
These plots show the reflectance of the -E03 (750 - 1100 nm) dielectric coating for a typical coating run. The shaded region in each graph denotes the spectral range over which the coating is highly reflective. Due to variations in each run, this recommended spectral range is narrower than the actual range over which the optic will be highly reflective. For concerns about data interpretation, please contact Tech Support.
[Graph Description: Reflectance (%) vs. Wavelength (nm) for -E03 Coating at 6° AOI. Shows Unpolarized and P-Polarized reflectance. The shaded region indicates high reflectivity from approximately 750 nm to 1100 nm. A button labeled 'Click to Enlarge' is present.]
[Graph Description: Reflectance (%) vs. Wavelength (nm) for -E03 Coating at 45° AOI. Shows P-Polarized and S-Polarized reflectance. The shaded region indicates high reflectivity from approximately 750 nm to 1100 nm. A button labeled 'Click to Enlarge' is present.]
[Text Description: Link to 'Excel Spreadsheet with Raw Data for -E03 Coating, 6° and 45° AOI'.]
Laser Induced Damage Threshold (LIDT)
This section provides a general overview of how laser induced damage thresholds are measured and utilized. The LIDT of an optic depends significantly on the type of laser used. Continuous wave (CW) lasers typically cause damage from thermal effects, while pulsed lasers can strip electrons from the lattice structure before causing thermal damage.
Note: This guideline assumes room temperature operation and optics in new condition (free of scratches, digs, and contamination). Dust or particles can significantly lower damage thresholds. For cleaning information, see the Optics Cleaning tutorial.
Testing Method
Thorlabs' LIDT testing complies with ISO/DIS 11254 and ISO 21254 specifications. The process involves exposing the optic to a laser beam at multiple locations for a set duration (CW) or number of pulses (pulsed). After exposure, the optic is examined under a microscope (~100X magnification) for visible damage. The number of damaged locations is recorded, and the power/energy is adjusted for subsequent exposures until damage is observed. The LIDT is assigned as the highest power/energy the optic can withstand without damage.
[Diagram Description: Figure 37A shows a protected aluminum-coated mirror after LIDT testing, which withstood 0.43 J/cm² (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage. The stated damage threshold for a similar mirror was 2.00 J/cm² (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Test results are representative of one coating run, and Thorlabs specifies values accounting for coating variances.]
[Diagram Description: Figure 37B is an example exposure histogram used to determine the LIDT of a BB1-E02 mirror, plotting Peak Fluence (J/cm²) against the number of exposure sites showing 'No Damage' or 'Damage'.]
Example Test Data
| Fluence | # of Tested Locations | Locations with Damage | Locations Without Damage |
|---|---|---|---|
| 1.50 J/cm² | 10 | 0 | 10 |
| 1.75 J/cm² | 10 | 0 | 10 |
| 2.00 J/cm² | 10 | 0 | 10 |
| 2.25 J/cm² | 10 | 1 | 9 |
| 3.00 J/cm² | 10 | 1 | 9 |
| 5.00 J/cm² | 10 | 9 | 1 |
Continuous Wave (CW) and Long-Pulse Lasers
CW laser damage is typically caused by melting due to absorption or damage to the optical coating. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.
For pulse lengths between 1 ns and 1 µs, damage can occur due to absorption or dielectric breakdown. LIDT values are valid only for optics meeting specified surface quality. Cemented or highly absorptive optics may have lower CW damage thresholds due to absorption or scattering.
High pulse repetition frequency (PRF) pulsed lasers may behave similarly to CW beams, depending on absorption and thermal diffusivity. For high PRF beams, both average and peak powers should be compared to the equivalent CW power.
CW LIDT Calculation
Thorlabs expresses CW LIDT as a linear power density (W/cm). This value can be applied to any beam diameter without adjustment for spot size, as demonstrated in Figure 37D. The average linear power density is calculated as:
Linear Power Density = Power / Beam Diameter
[Diagram Description: Figure 37D plots LIDT in linear power density (W/cm) vs. pulse length (seconds) and spot size (µm to cm). For long pulses to CW, linear power density becomes constant with spot size. This graph was obtained from reference [1].]
[Diagram Description: Figure 37E shows the intensity distribution of uniform and Gaussian beam profiles, illustrating that a Gaussian beam typically has a maximum power density twice that of a uniform beam.]
This calculation assumes a uniform beam intensity profile. For non-uniform profiles like Gaussian beams, consider the maximum power density, which can be twice that of the uniform beam.
If the operating wavelength differs from the LIDT specification wavelength, scale the damage threshold. A general rule of thumb is a linear relationship: shorter wavelengths decrease the damage threshold (e.g., 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm). However, this is not quantitative, as CW damage also scales with absorption, which may not scale linearly with wavelength. Contact Tech Support for wavelength-specific adjustments.
Adjusted LIDT = LIDTPower * (Your Wavelength / LIDT Wavelength)
If your calculated power density is less than the adjusted LIDT, the optic should be suitable.
Pulsed Lasers
Pulsed lasers can induce damage via dielectric breakdown or thermal effects, depending on pulse length. The relevant regimes for Thorlabs' specified LIDT values are outlined below.
| Pulse Duration | Damage Mechanism | Relevant Damage Specification |
|---|---|---|
| t < 10-9 s | Avalanche Ionization | No Comparison (See Above) |
| 10-9 < t < 10-7 s | Dielectric Breakdown | Pulsed |
| 10-7 < t < 10-4 s | Dielectric Breakdown or Thermal | Pulsed and CW |
| t > 10-4 s | Thermal | CW |
When comparing a pulsed laser's LIDT specification, know the following:
- Wavelength of your laser
- Energy density of your beam (total energy divided by 1/e² area)
- Pulse length of your laser
- Pulse repetition frequency (PRF) of your laser
- Beam diameter of your laser (1/e²)
- Approximate intensity profile of your beam (e.g., Gaussian)
Pulsed LIDT Calculation
For short pulses, energy density (J/cm²) is the preferred metric. This value applies to any beam diameter without spot size adjustment. A Gaussian beam's maximum energy density is typically twice that of a uniform beam.
[Diagram Description: Figure 37G plots LIDT in energy density (J/cm²) vs. pulse length (seconds) and spot size (µm to cm). For short pulses, energy density becomes constant with spot size. This graph was obtained from reference [1].]
Adjusted LIDT (Energy) = LIDTEnergy * sqrt(Your Wavelength / LIDT Wavelength)
This provides a wavelength-adjusted energy density. If your maximum energy density is less than this value, the optic is suitable.
Beam diameter affects LIDT for larger sizes (>5 mm) as more defects may be illuminated. For data presented, a <1 mm beam size was used.
Pulse length compensation is also necessary. For pulse widths between 1 - 100 ns:
Adjusted LIDT (Pulse Length) = LIDTEnergy * (Your Pulse Length / LIDT Pulse Length)
This calculation is primarily for pulses between 10⁻⁹ s and 10⁻⁷ s. For pulses between 10⁻⁷ s and 10⁻⁴ s, the CW LIDT must also be checked.
Thorlabs includes a buffer between specified damage thresholds and test results to accommodate batch variations. Individual test information and certificates are available upon request. Contact Tech Support for more information.
References
- [1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
- [2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
- [3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
- [4] N. Bloembergen, Appl. Opt. 12, 661 (1973).
Product Information
[Image Description: A photograph of the MRA05L-E03 Leg-Coated Right-Angle Prism Mirror, showing its triangular shape and the coated leg surfaces.]
Leg-Coated Right-Angle Prism Mirror, Dielectric Coating (750 nm - 1100 nm)
| Part Number | Description | Price | Availability |
|---|---|---|---|
| MRA05L-E03 | Customer Inspired! Leg-Coated Right-Angle Prism Dielectric Mirror, 750 - 1100 nm, L = 5.0 mm | $127.94 | Lead Time |
