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Proceedings Paper

Scattering simulation software dedicated to the design of cooled infrared detector optical shieldings
Author(s): Nicolas Gerin; Philippe Chorier
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Paper Abstract

When designing cooled infrared detectors, it is definitely a challenge to get simultaneously high optical efficiency and low radiative heat load of the cold shield. From an optical point of view, cold shield must be as big and absorbing as possible. But the reduction of cooler size, input power and cool down time require precisely an opposite approach. This critical optimization is emphasized by the necessity of conducting long and expensive experiments since radiative exchanges have been extremely complex and can not be accurately estimated by calculation. Recent optical concepts as BRDF (Bidirectional Reflectance Distribution Function) and the increase of computer processor speed have made possible the development of a lighting software for this topic. This software was developed by upgrading an existing non-sequential light propagation one. Upgrades apply particularly to capabilities of modeling complex geometries as IR focal planes, taking into account spectral dependency of radiative properties of surfaces and volumes and introduction of the diffusion behavior of actual surfaces (BRDF). BRDF properties of most current surfaces were measured at both ambient and low temperatures. At least, the software was qualified by comparison of computed and experimental results of exceeding photon fluxes in actual detector. This CAD approach is of high interest in cost driving designs by simplifying cold shield systems and in application where there is very low scene photon fluxes.

Paper Details

Date Published: 26 October 1998
PDF: 11 pages
Proc. SPIE 3436, Infrared Technology and Applications XXIV, (26 October 1998); doi: 10.1117/12.328027
Show Author Affiliations
Nicolas Gerin, SOFRADIR (France)
Philippe Chorier, SOFRADIR (France)

Published in SPIE Proceedings Vol. 3436:
Infrared Technology and Applications XXIV
Bjorn F. Andresen; Marija Strojnik, Editor(s)

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