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Mirror Selection Guide
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Selecting the proper mirror for your application requires making a number of choices. A few of the many considerations include: reflectivity, laser damage resistance, coating durability, thermal expansion of the substrate, wavefront distortion, scattered light, and certainly cost. The following tables should help in comparing the available choices from Newport.
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Reflective Coatings
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Newport offers a large variety of reflective coatings covering the UV, visible, near infrared, and infrared regions. Metallic coatings are more broadband, while dielectric coatings are more efficient.
Metallic Mirrors represent a good mixture of performance and value. These broadband coatings are relatively insensitive to wavelength, angle of incidence, and polarization. High-energy levels should be avoided, however.
Dielectric Mirrors offer near total reflection, minimizing losses in nearly all optical systems. These coatings are very durable, easily cleaned, and resistant to laser damage. Available either for broadband or narrowband, they operate efficiently over 0–45° angle of incidence.
High-Energy Laser Mirrors are designed and manufactured utilizing meticulous procedures to resist laser damage. They are intended for use with high-power CW lasers and high-energy pulsed lasers. These mirrors operate at a single or dual laser lines at either 0° or 45° angle of incidence.
SuperMirrors™ take advantage of our advanced super-polishing and state-of-the-art coating technology to provide the highest reflectivity and lowest loss of any commercially available mirrors. Better than 99.97% reflectivity is achieved with these optics.
Ultrafast Mirrors are all dielectric coated optics designed to minimize dispersion effects on ultrashort laser pulses. Specially optimized coatings deliver maximum bandwidth while minimizing pulse broadening.
Additionally, Newport has the capability to offer specialized coatings to help provide solutions for your applications. For more information, please contact us.
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| Coating Type |
Wavelength
Range
(nm) |
Reflectance |
Abrasion
Resistance |
Cost |
Features |
| Metallic Mirrors |
UV Enhanced Aluminum
(Broadband Metallic Mirrors, VALUMAX® Broadband Mirrors, and Concave Broadband Metallic Mirrors) |
250–600 |
Ravg >90% |
Moderate |
Low |
UV Reflectivity is enhanced by
a MgF2 overcoat |
Protected Aluminum
(VALUMAX® Broadband Mirrors) |
400–700 |
Ravg >88% |
Moderate |
Low |
Visible reflectivity is enhanced by a
protective SiO overcoat |
Enhanced Aluminum
(Utility Broadband Metallic Mirrors, Broadband Metallic Mirrors, VALUMAX® Broadband Mirrors, PinholeFreeTM Broadband Metallic Mirrors, and Concave Broadband Metallic Mirrors) |
450–700 |
Ravg >93% |
Moderate |
Low |
Visible and NIR reflectivity is enhanced
by a multilayer dielectric overcoat |
Protected Silver
(Broadband Metallic Mirrors, VALUMAX® Broadband Mirrors, PinholeFreeTM Broadband Metallic Mirrors, and Concave Broadband Metallic Mirrors) |
0.48–20 mm |
Ravg >96% |
Moderate |
Low |
Visible and IR performance superior
to aluminum coatings |
Protected Gold
(Broadband Metallic Mirrors, and VALUMAX® Broadband Mirrors) |
0.65–20 mm |
Ravg >96% |
Moderate |
Low |
NIR to Infrared performance
slightly higher than protected silver |
| Dielectric Mirrors |
Broadband Mirrors
(Broadband Dielectric Mirrors) |
488–694
700–950 |
Rs, Rp >98–99% |
High |
Moderate |
Very high reflectivity over a broad
wavelength range |
Laser Line Mirrors
(Laser Line Dielectric Mirrors) |
Various
325–1550 |
Rs, Rp >99% |
High |
Moderate |
Very high reflectivity over a narrow
wavelength range |
High-Energy Excimer
Laser Mirrors
(High-Energy Excimer Laser Mirrors) |
193, 248,
308, 352 |
Rs >99.7%,
Rp >99% |
High |
High |
High reflectivity and damage threshold
at excimer laser wavelengths |
High-Energy Nd:YAG
Laser Mirrors
(High-Energy Nd:YAG Laser Mirrors ) |
266, 354.7,
532, 1064 |
Rs, Rp >99% |
High |
High |
High reflectivity and damage threshold
at Nd:YAG laser wavelengths |
Broadband SuperMirrors™
(Broadband SuperMirrorsTM) |
485–700
700–910 |
Rs, Rp >99.9% |
Low |
High |
Highest reflectivity broadband
mirror commercially available |
Ultra-Low Loss SuperMirrors™
(Ultra-Low Loss SuperMirrorsTM) |
Various
583–1659 |
R >99.97% |
Low |
High |
Highest reflectivity and lowest losses
of any commercially available mirrors |
Ultrafast Mirrors
(Ultrafast Laser Broadband 45° Mirrors, Ultrafast Laser Super-Broadband Turning Mirrors, Ultrafast Laser Chirped Mirrors, and Ultrafast Laser High Reflecting Pump Mirrors) |
Various
700–930 |
Rs, Rp >99% |
High |
High |
High reflecting pump mirrors, output
couplers, and broadband mirrors
with minimum pulse dispersion |
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Substrate Materials
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Pyrex® is an excellent mirror substrate due to its low coefficient of thermal expansion and resistance to thermal shock. When high stability is critical, Zerodur® is the best choice for its zero thermal expansion. UV fused silica has a thermal expansion coefficient lower than Pyrex® but is more expensive. Because of its excellent transmissive properties, UV fused silica is often reserved for transmissive mirrors as well as high-energy laser mirrors.
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| Material |
Coefficient of
Thermal Expansion |
Cost |
Features |
| Pyrex® |
3.25 x 10-6/°C |
Low |
Best all around mirror substrate, low expansion borosilicate glass,
resistant to thermal shock |
| UV Fused Silica |
0.52 x 10-6/°C |
High |
Low thermal expansion for excellent stability, high laser damage resistance |
| Zerodur® |
0 ± 0.1 x 10-6/°C |
Moderate |
Nominally zero thermal expansion for ultra-high stability,
unique glass-ceramic material |
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Optical Surfaces
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The mirror application drives the requirements for surface flatness and surface quality. When preservation of wavefront is critical, a l/10 to l/20 mirror should be selected; when wavefront is not as important as cost, a l/2 to l/5 mirror can be used. For surface quality, the tighter the scratch-dig specification, the lower the scatter. For demanding laser systems, 20-10 to 10-5 scratch-dig is best. For applications where low scatter is not as critical as cost, 40-20 to 60-40 scratch-dig can be used.
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Surface Flatness
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| Figure |
Cost |
Applications |
| l/2 |
Low |
Used where wavefront distortion is not as important as cost |
| l/5 |
Moderate |
Excellent for most general laser and imaging applications where low wavefront performance must be balanced with cost |
| l/10 |
Moderate |
For laser and imaging applications where low wavefront distortion, especially in systems with multiple elements |
| l/20 |
High |
For the most demanding laser systems where maintaining accurate wavefront is critical to performance |
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Surface Quality
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| Scratch-Dig |
Cost |
Applications |
| 60-40 |
Low |
Used for low-power laser and imaging applications with unfocused beams where scatter is not critical |
| 40-20 |
Moderate |
Ideal for laser and imaging applications with collimated beams where scatter begins to affect system performance |
| 20-10 |
High |
Excellent for laser systems with focused beams that can tolerate little scattered light |
| 10-5 |
High |
For the most demanding laser systems where low scatter is critical to performance |
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Other Sizes
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For other diameters or different radii of curvature, Newport can also coat our spherical lenses with a reflective coating upon special request. Please see the Spherical Lenses Chapter for a complete selection. For more information, please contact us.
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