The sophistication of airborne instrumentation for navigation, targeting, beam weaponry and other applications has dramatically advanced. The windows are required not only to transmit the needed wavelength and energy; they also must survive thermal transients and high electric fields without energy losses or divergence. Requirements for mechanical properties might include providing for weight limits, night visibility, rain and sand abrasion and the corrosive gases emitted during rocket fire.

CVD diamond windows have major potential military applications. Apart from an intrinsic absorption band at ~5 um, diamond is an excellent multispectral window material. The combination of these good optical properties with strength, hardness, chemical inertness, and high thermal conductivity makes them particularly suited for use as the outer windows on missile seeker devices flying at high Mach numbers, exit windows for high power laser or microwave weaponry or infrared systems for viewing during inclement weather conditions, for instance.