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Proceedings Paper

LWIR telescope design considerations for high-temperature operation
Author(s): R. Lawrence Sinclair; Martin High
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Paper Abstract

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.

Paper Details

Date Published: 15 September 1995
PDF: 10 pages
Proc. SPIE 2540, Current Developments in Optical Design and Engineering V, (15 September 1995); doi: 10.1117/12.219528
Show Author Affiliations
R. Lawrence Sinclair, Spar Aerospace Ltd. (Canada)
Martin High, Applied Physics Specilities, Ltd. (Canada)

Published in SPIE Proceedings Vol. 2540:
Current Developments in Optical Design and Engineering V
Robert E. Fischer; Warren J. Smith, Editor(s)

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