Abstract: An optical element that features high transmission and low reflectivity at infrared wavelengths is described. The optical element includes a substrate, an adhesion layer on the substrate, and an anti-reflection coating. Substrates include chalcogenide glasses, InAs, and GaAs. Adhesion layers include Se, ZnSe, Ga2Se3, Bi2Se3, In2Se3, ZnS, Ga2S3 and In2S3. Anti-reflection coatings include one or more layers of DLC (diamond-like carbon), ZnS, ZnSe, Ge, Si, HfO2, Bi2O3, GdF3, YbF3, In2Se3, and YF3. The optical elements show high durability and good adhesion when subjected to thermal shocks, temperature cycling, abrasion, and humidity.

Abstract: An optical element based on a graphite substrate is provided. The optical element may be a reflective element and may include a finishing layer, adhesion layer, and/or galvanic compatibility layer. Finishing layers include Ni and Si and provide a surface that can be processed to a low finish to support a reflective layer or reflective stack. Graphite substrates are light weight, are amenable to diamond turning and can be machined to near net shape, have low coefficients of thermal expansion to enable operation over wide temperature ranges, and have high chemical stability.