26 July 1999 Metal oxynitride and diamond hard coatings for infrared windows
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The protection of IR windows in airborne FLIR sensor systems against erosion resulting from raindrop and particle impact is accomplished by means of a front surface coating. The wavelength ranges required are 8-14 micrometers , where diamond competes with boron phosphide based coatings for the protection of multispectral zinc sulphide used as a window for multiple detectors. This paper describes progress in the development of diamond coatings for germanium windows, including selection and deposition of durable front surface antireflection layers. The diamond layers are deposited by microwave plasma CVD techniques at 500 degrees C. For the multispectral application, hard oxynitride coatings have been developed both as stand-alone coatings and as interlayers for diamond coatings. The multispectral coatings and the antireflection coatings are deposited by a sputtering process, applicable to flats and domes. In both cases, structured surfaces at appropriate scales are used to improve optical transmission and mechanical adhesion.
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Andrew J. Miller, Andrew J. Miller, Martin D. Hudson, Martin D. Hudson, Paul V. Dennis, Paul V. Dennis, Anthony E. J. Wilson, Anthony E. J. Wilson, "Metal oxynitride and diamond hard coatings for infrared windows", Proc. SPIE 3705, Window and Dome Technologies and Materials VI, (26 July 1999); doi: 10.1117/12.354617; https://doi.org/10.1117/12.354617

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