For over two decades Denton's FSS99 has been the benchmark for protected silver coatings used in telescopes, space-flight systems and military optics. In recent years we have added several enhancements and options to provide a wide choice of coatings for different applications. The top layers are tailored for spectral performance, as indicated by the numerical designation. For example, FSS99-500 has peak reflectance at 500nm in the visible, FSS99-106 is optimized for 1.06um. Adhesion layers under the silver are customized to match the substrate. Good adhesion and durability are realized on materials such as glass, nickel, diamond turned aluminum, or polished beryllium. All FSS99 coatings pass the adhesion, abrasion, temperature and humidity requirements of MIL-M-13508.

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Denton now offers a highly durable silver coating for use in harsh environments. This coating is spectrally similar to FSS99-500, and in addition to meeting the standard tests from MIL-M-13508, it also passes the 24 hour Salt Fog test.

Download the technical paper:
X-1 Silver: A High Durability Silver Coating for use in Harsh Environments

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Gold Coatings

Gold coatings make excellent mirrors for long wavelength applications as they have very high reflectance from 700nm through the far infrared. They are also chemically inert, so that with a thin protective layer for abrasion resistance, they make very stable, durable mirror coatings. Denton's FSG98 uses SiO₂ as a standard overcoat, but other materials are available for special applications. FSG98 meets the adhesion, temperature and humidity requirements of MIL-M-13508.

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Aluminum Coatings

Aluminum coatings are versatile as they offer moderate to high reflectance from the ultraviolet to the infrared. The visible reflectance of a bare aluminum layer is about 90%. For a protected aluminum mirror (FS72H), that value can never be exceeded. For a standard enhanced aluminum coating (FS80H), the peak reflectance can be boosted to about 95%. Customized designs are available that offer even higher reflectance values over narrow wavelength ranges.

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FS72H is an aluminum mirror with a single layer of SiO₂ to provide abrasion resistance and environmental durability. The effective half-wave thickness of the protective layer can be adjusted to position the reflectance maximum at any wavelength from the UV through the visible spectral regions. For example, FS72H-400 has SiO₂ thickness for peak reflectance at 400nm. FS72H coatings are durable, meeting the adhesion, abrasion, temperature and humidity requirements of MIL-M-13508.

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Denton's FS80H family of aluminum coatings offer enhanced reflectivity and good durability. The thickness of the enhancing layers can be adjusted to provide peak reflectance at any wavelength from the UV through the visible and near infrared (NIR) spectral regions. For example, FS80H-500 has a reflectance maximum at 500nm. FS80H coatings are durable, meeting the adhesion, abrasion, temperature and humidity requirements of MIL-M-13508.


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