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Proceedings Paper

Experimental measurements for passive athermalization of a satelliteborne MWIR telescope including dn/dT, CTE, and final evaluation
Author(s): Thomas L. Williams; Daniel R. Lobb; Alan J. Cormier
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Paper 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.

Paper Details

Date Published: 6 September 1999
PDF: 11 pages
Proc. SPIE 3739, Optical Fabrication and Testing, (6 September 1999); doi: 10.1117/12.360183
Show Author Affiliations
Thomas L. Williams, Sira Electro-Optics Ltd. (United Kingdom)
Daniel R. Lobb, Sira Electro-Optics Ltd. (United Kingdom)
Alan J. Cormier, Sira Electro-Optics Ltd. (United Kingdom)


Published in SPIE Proceedings Vol. 3739:
Optical Fabrication and Testing
Roland Geyl; Jonathan Maxwell, Editor(s)

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