Abstract
At present, Ge/Si components are used for Mid Wave infra Red (MWIR) and Long Wave Infra Red (LWIR) assemblies. The exposed surface of these assemblies is coated with Diamond Like Carbon (DLC) films using several technologies to provide protection against rain, wind and blowing sand while also serving as the AR coating. The disadvantage is that Ge absorption increases at higher temperatures and also blocks the visible and NIR wavelengths below 2.0 micron. ZnSe, Cleartran and some Chalcogenide materials are alternate substrate material choices for multiband Visible, NIR, MWIR systems with alignment or target acquisition capability in the visible spectrum and high temperature applications. DLC films do not adhere well to ZnSe which has resulted in DLC equivalent coatings or boron Phosphide films being used. The results presented herein are for a DLC AR coating applied on ZnS, ZnSe, Chalcogenide and Glass substrates. Also presented in this paper are high transmitting AR coatings on various chalcogenide materials for MWIR AND LWIR, Broad band AR for 7.5 to 14.0 micron spectral range, Dual Band AR coatings for MWIR and LWIR which meet environmental and durability requirements of next generation optical components and assemblies. Measured data is compared with predicted theoretical performance for all aforementioned coatings.
Published Version
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