Experimental measurements for passive athermalization of a satelliteborne MWIR telescope including dn/dT, CTE, and final evaluation

Thomas L. Williams; Daniel R. Lobb; Alan J. Cormier

doi:10.1117/12.360183

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6 September 1999 Experimental measurements for passive athermalization of a satelliteborne MWIR telescope including dn/dT, CTE, and final evaluation

Thomas L. Williams, Daniel R. Lobb, Alan J. Cormier

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Proceedings Volume 3739, Optical Fabrication and Testing; (1999) https://doi.org/10.1117/12.360183
Event: Optical Systems Design and Production, 1999, Berlin, Germany

Abstract

The paper describes some measurements carried out in order to obtain reliable data for designing a passively athermalized MWIR telescope for observation of earth from a satellite and for finally evaluating the change of focus with temperature for the completed telescope. The telescope was a catadioptric system and the main body was a carbon composite structure, while the lens elements in the system were of either germanium or silicon. Reliable data was of course available for the coefficient of thermal expansion (CTE) of the metal components used in the structure, as well as for Ge and Si. However, the CTE of a carbon structure will to some extent depend on the exact form of construction that is used and therefore needs to be measured, or at least checked, on the actual structure. A survey of the published dn/dT data for Ge and Si as well as that provided by the material suppliers showed variations and uncertainties that were unacceptable.

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Thomas L. Williams, Daniel R. Lobb, and Alan J. Cormier "Experimental measurements for passive athermalization of a satelliteborne MWIR telescope including dn/dT, CTE, and final evaluation", Proc. SPIE 3739, Optical Fabrication and Testing, (6 September 1999); https://doi.org/10.1117/12.360183

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