Active temperature compensation of an infrared zoom lens

Eric H. Ford

doi:10.1117/12.279085

25 September 1997 Active temperature compensation of an infrared zoom lens

Eric H. Ford

Proceedings Volume 3129, Zoom Lenses II; (1997) https://doi.org/10.1117/12.279085
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

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.

Citation Download Citation

Eric H. Ford "Active temperature compensation of an infrared zoom lens", Proc. SPIE 3129, Zoom Lenses II, (25 September 1997); https://doi.org/10.1117/12.279085

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