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15 September 1995 LWIR telescope design considerations for high-temperature operation
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Germanium (Ge) is the most widely used material in long wave infrared (LWIR) refractive telescopes due to its high index of refraction and very low dispersion characteristics. Unfortunately, germanium's absorption increases dramatically when operating in hot environments. Traditionally, the operating temperature of Ge is extended by doping to reduce the absorption coefficient's temperature dependence. However, depending upon the optical design form, transmission losses attributed to an operating temperature rise of 40 degrees, may still be as high as 5 to 15 percent. When such absorption losses are not tolerable, alternative materials such as ZnSe, Amtirl, and GaAs can be considered. In this paper a series of case studied is presented to compare the predicted performance of conventional Ge dominated designs with lenses composed almost entirely of these alternative materials. Fabrication and production cost issues are compared along with the utilization of hybrid refractive/diffractive optical elements.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
R. Lawrence Sinclair and Martin High "LWIR telescope design considerations for high-temperature operation", Proc. SPIE 2540, Current Developments in Optical Design and Engineering V, (15 September 1995);


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