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SLAR Coatings
SLAR coatings are in most cases designed using MgF2 as film material. MgF2 is very efficient visible light SLAR coating film material on high refractive index substrates. Plots below show SLAR MgF2 centered at 550 nm on BK7 and on SF11 SCHOTT glass substrates; on SF11 R < 0.15% @ 550 nm and R < 0.25% @ 550 ±
20 nm.
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SLAR MgF2 on BK7 |
SLAR MgF2 on SF11 |
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Infrared materials such as semiconductors Si and Ge have very high index of refraction and it is relatively very easy to design SLAR coating for them using dielectrics, even oxides, for range up to 11 µ
. Plots below show SLAR on Si and Ge centered at 2.0 and 8.0 µ
, respectively. Wavelength where SLAR has a minimum R is known as the central wavelength of the SLAR.
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SLAR on Si |
SLAR on Ge |
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SLAR do not have wide bandwidth and are mostly used for instruments that operate over relatively narrow part of the spectrum. When specifying SLAR please include the following:
1. Substrate Material, 2. Angles of incidence, 3. Central Wavelength, 4. Polarization of incident light, 5. Maximum R at the central wavelength for unpolarized and/or both states of polarization, and 6. Laser Induced Damage Threshold or LIDT.
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