FAQs

IR Coating Information

What are the specifications of a Germanium (Ge) 3-12 IR Lens?


Description
: A high efficiency anti-reflectance coating with moderate durability for germanium optics, providing good transmittance in the 3-12µm spectral band.

Application: Thermal imaging systems & FLIR systems.

Spectral Performance
: The following spectral transmittance value is based on coating both sides of a 1mm thick germanium substrate with Ge 3-12.

Spectral Performance: @ 3-12µm
Transmission: 94% average
Reflection: 2% average per surface

 

Theoretical T% Curve Ge 3-12

 

Environmental Performance: The coating is laboratory cleanable.

The coating performance specified herein is typical of this particular coating and does not preclude adherence to other specifications on a case by case basis.

Please call (603) 757-0070 or email us with your specific requirements.

What are the specifications of an Ag – DP Mirror?


Description
: An evaporated silver coating with a durable protective layer.

Application: Thermal imaging systems, FLIR systems, Scientific & Astronomical.

Spectral Performance Reflectivity: Reflectance: 98% average 2 to 12µm.

Theoretical Curve AG - DP

Environmental Performance: The coating passes the following environmental tests by design specified in MIL-F-48616 & MIL-C-48497:

Adhesion: Cellophane tape removal test
Humidity: 95% to 100% relative humidity @ 120°F (49°C) for a duration of 24 hours.
Abrasion: Moderate (No sign of deterioration such as scratches or streaks when abraded with a dry, clean cheesecloth pad)
Temperature: -80°F to +160°F (26°C to 71°C) for 2 hours at each temperature.

The coating performance specified herein is typical of this particular coating and does not preclude adherence to other specifications basis.

Please call (603) 757-0070 or email us with your specific requirements.

What are the specifications of Zinc Selenide (ZnSe) 1-5 IR Lens?


Description
: A highly anti-reflectance coating with moderate durability of Zinc Selenide optics, providing excellent transmittance in the 1-5µm spectral band. This broadband coating covers the astronomical bands “J” through “M.”

Application: Mostly used on optics for astronomical applications.

Spectral Performance
: The following spectral transmission value is based on coating both sides of a 1mm thick Zinc Selenide substrate with ZnSe 1-5.

Spectral Performance: @ 1-5µm
Transmission: 95% average
Reflection: 2% average per surface

 

Theoretical T% Curve ZnSe 1-5

 

Environmental Performance: The coating passes the following environmental tests specified in MIL-F-48616 & MIL-C-48497:

Adhesion: Cellophane tape removal test.
Humidity: 95% to 100% relative humidity @ 120°F (49°C) for a duration of 24 hours.
Abrasion: Moderate (No sign of deterioration such as scratches or streaks when abraded with a dry, clean cheesecloth pad).

Temperature: -80°F to +160°F (26°C to 71°C) for 2 hours at each temperature.

The coating performance specified herein is typical of this particular coating and does not preclude adherence to other specifications on a case by case basis.

Please call (603) 757-0070 or email us with your specific requirements.

What are the specifications of Germanium (Ge) 8-12 IR Lens?


Description
: A high efficiency, anti-reflectance coating with moderate durability for germanium optics, providing excellent transmittance in the 8-12µm spectral band.

Application: Mostly used on optics for astronomical applications.

Spectral Performance
: The following spectral transmittance value is based on coating both sides of a 1mm thick germanium substrate with Ge 8-12.

Spectral Performance: @ 8-12µm
Transmission: 98% average
Reflection: 1% average per surface

 

Theoretical T% Curve AR 0.8-2.5

 

Environmental Performance: The coating passes the following environmental tests specified in MIL-F-48616 & MIL-C-48497:

Adhesion: Cellophane tape removal test.
Humidity: 95% to 100% relative humidity @ 120°F (49°C) for a duration of 24 hours.
Abrasion: Moderate (No sign of deterioration such as scratches or streaks when abraded with a dry, clean cheesecloth pad).

Temperature: -80°F to +160°F (26°C to 71°C) for 2 hours at each temperature.

The coating performance specified herein is typical of this particular coating and does not preclude adherence to other specifications on a case by case basis.

Please call (603) 757-0070 or email us with your specific requirements.

What are the specifications of an Ag 10.6 Mirror?

Description: An evaporated Enhanced Silver Dielectric coating for High reflection at 10.6 Microns.

Application: CO2 Laser Systems

Spectral Performance Reflectivity: Greater than 99% at 10.6 microns at 0 to 45 degrees angle of incidence.

Environmental Performance: The coating passes the following environmental tests specified in MIL-F-48616 or MIL-C-48497:

Adhesion: Cellophane tape removal test
Humidity: 95%–100% relative humidity @ 120°F (49°C) for a duration of 24 hours.
Abrasion: Moderate (No sign of deterioration such as scratches or streaks when abraded with a dry, clean cheesecloth pad)
Temperature: -80°F to +160°F (-62°C to 71°C) for 2 hours at each temperature.

The coating performance specified herein is typical of this particular coating and does not preclude adherence to other specifications on a case by case basis.

Please call us (603) 757-0070 with your specific requirements.

Theoretical Curve AG 10.6

Most Popular Questions

What is the difference between ¼ wave, 1/10 wave, & 1/20 wave mirrors?

These values refer to the surface accuracy specification for the polished substrate of a mirror. Surface Accuracy describes the maximum allowable deviation of an optical surface from a perfect surface. If the mirror were flat, the value would give a reference as to "how flat." Since the method used for inspecting surface accuracy uses a specific wavelength, the value is defined in terms of this wavelength. All catalog values refer to a maximum peak-to-valley value at 632.8nm. For high accuracy parts, the amount of deviation is so small that the value is defined as a fraction of a wavelength of light. For example, a ¼-wave mirror has a surface accuracy of 158.2nm (0.25 x 632.8nm), which is equivalent to 6.2 micro inches. The lower the value of the fraction, the higher the accuracy. Typically only values less than ¼-wave are considered as precision and values less than 1/10-wave as high precision quality. As a comment on notation, the following values are equivalent: ¼-wave, ¼λ and λ4, where λ is the value of the wavelength.

What is Focal Length?

The effective focal length (EFL) is the distance from the principal point to the focal point. The back focal length (BFL) is the distance from the vertex of the last lens to the second focal point. The front focal length (FFL) is the distance from the first lens surface to the first focal point.

Diagram

Can I place ND filters back-to-back and increase optical density?

Yes, ND (neutral density) filters exhibit an additive relationship with their optical density values. For instance, stacking filters with Optical Density values of 0.6 and 0.9 yield a resultant optical density of 1.5 (which gives an overall transmission of 3%) Care should be taken when using the reflective type of ND filter in order to insure that the reflected light does not interfere with the application. In stacks, the reflective filters are not parallel in order to reduce back reflections.

What are Diffractive Optical Elements (DOE’s) and what are some of the advantages of using them in a lens design?

Diffractive Optical Elements (DOE's) can focus light just like conventional refractive elements but do so by diffraction (similar to a grating) instead of by refraction. Compared with conventional optical surfaces, which are flat or spherical in shape, DOE's can be constructed to simulate complex surface shapes to better correct aberrations and improve optical performance. Just like glass optics, DOE's can be antireflection coated with single or multilayer coatings. DOE's are useful for conventional broadband imaging applications as well as for many low- and high- power laser applications. Typical DOE sizes range from approximately 4 mm to 250 mm in diameter. For OEM applications, the principal advantages of using DOE's include: DOE's usually permit a reduction in the number of optical elements in a design, reducing costs and lens weight. DOE's often enable optical performance that would be impossible to achieve using conventional optical elements alone.

What are the differences Between Aluminum Types?

Each coating is optimized for a particular spectral region, so care must be used to select a coating that best meets the wavelength, durability, and cost demands of the application. Protected Aluminum is the most common due its large broadband coverage of the visible and near infrared spectrums at an economical price. The coating has bare aluminum overcoated with a thin layer of silicon monoxide for increased durability in handling and cleaning. Typical values include a reflectivity of greater than 85% from 400 to 700nm. The Enhanced Aluminum coating consists of a multi-layer film of dielectrics over the aluminum base that is used to improve reflectivity in either the visible (Enhanced) or the ultraviolet (UV Enhanced). Enhanced offers greater than 95% reflectivity from 450 to 650nm, while UV Enhanced offers greater than 85% reflectivity from 200 to 700nm. Protected Gold has a bare gold coating overcoated with protective silicon monoxide. Gold coatings are effective for applications requiring high performance in the near and mid-infrared with greater than 97% reflectivity from 800 to 2000nm. For all these coatings, the theoretical reflectance rises gradually through to the 10 micron wavelength. Reflectivity is greater than 95% at 10 microns. An uncoated mirror is just the polished substrate (to specific surface accuracy and f/#) without any metallic coating; this allows users to apply their own custom coatings.