Diamond has an exceptionally wide optical transmission window and is resistant to mechanical abrasion and chemical attack. Optical coatings are an inherent part of many optical structures. Diamond films can provide the attractive surface properties of diamond while improving optical performance. Antireflection coatings on semiconductor photon detectors, emitters, and windows. Controlled reflection on mirrors, filters, and architectural glass.
Emission pixels on field emission displays.
Applications require critical control of sub-micrometer dimensions. For most thin-film coating applications such absorption is negligible. However, not all CVD polycrystalline diamond has useful optical features. Rough surfaces and incorporation of impurities and defects can have a significant deleterious effect on polycrystalline diamond optical properties. These represent challenges to the application of CVD polycrystalline diamond to optical-coatings.