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Proceedings Paper

Active temperature compensation of an infrared zoom lens
Author(s): Eric H. Ford
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Paper Abstract

IR materials have very high rates of index change with temperature. These index changes cause thermal defocusing that is an order of magnitude worse than that seen in the visible spectral band, and result in focus shifts usually too rapid to be compensated by housing material selection. The alternative is to actively compensate focus using motorized motions of a lens subgroup. Compensation of a zoom lens is more complex since the required thermal refocusing varies with zoom position. This paper presents a method for thermal compensation that is done in software for computer controlled, stepper motor driven zoom lenses. Compensation can be done to within an arbitrarily small temperature increment.

Paper Details

Date Published: 25 September 1997
PDF: 6 pages
Proc. SPIE 3129, Zoom Lenses II, (25 September 1997); doi: 10.1117/12.279085
Show Author Affiliations
Eric H. Ford, Eidetic Optical Systems (United States)


Published in SPIE Proceedings Vol. 3129:
Zoom Lenses II
Ellis I. Betensky; Allen Mann; Iain A. Neil, Editor(s)

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