1 December 1991 Automatic active athermalization of infrared optical systems
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Abstract
Most infrared optical materials exhibit a relatively strong dependence on refractive index on temperature. This dependence is about one or two orders of magnitude more severe than for the optical glasses used in the visual spectral range. As a result, important optical properties of an IR-optical system (e.g., focal length, image plane), change with temperature. This is particularly annoying with FLIRs in aircraft because the necessary refocusing increases the pilot's workload. A method to overcome that problem will be described. It makes use of automatic autocollimation, where the radiation of a special thermal target is passing the optical system twice before hitting the infrared detector. A microprocessor evaluates the detector signals and moves an optical element in such a manner that the image plane of the optical systems always remains on the detector focal plane.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gunther Kuerbitz, Gunther Kuerbitz, "Automatic active athermalization of infrared optical systems", Proc. SPIE 1540, Infrared Technology XVII, (1 December 1991); doi: 10.1117/12.48768; https://doi.org/10.1117/12.48768
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