A combination of extraordinary thermal, mechanical and optical properties places natural diamond in a class by itself among materials. Diamond is the only material that offers long wave infrared (8â14 μm) transmission along with great strength and resistance to thermal shock and erosion. Diamond is also an excellent window for microwave, visible and ultraviolet radiation. Diamond absorbs midwave infrared radiation, so its utility for midwave windows is limited to a role as a thin, protective film. The extraordinary properties of diamond have been known for decades, but only the smallest of optical windows could be made because large crystals of natural diamond are extremely rare. The key technological advance that now makes diamond windows possible is the growth of chemical-vapor-deposited (CVD) diamond over large areas. CVD diamond has most of the properties of natural diamond, but its mechanical strength remains modest.
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