<title>Active temperature compensation of an infrared zoom lens</title>

Abstract

JR 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.

Dual field-of-view midwave infrared optical design and athermalization analysis

“…The methodology and process for stabilizing the optical qualities by temperature compensation is called athermalization. Active athermalization is appropriate for quick responses to overcome rapid error inputs while operating in a thermally dynamic environment [17]. To facilitate athermalization, a motorized lens adjusts the position and thermal sensors measure the temperature difference.…”

110 °C range athermalization of wavefront coding infrared imaging systems

“…Available approaches of infrared athermalization focus on the active mechanical [3], passive mechanical [4] and passive optical [5] measures. As one of typical computational imaging techniques, wavefront coding technique is a powerful hybrid optical-digital technique for increasing a focal depth of imaging and for widening an athermalization temperature range.…”

A wide-FoV athermalized infrared imaging system with a two-element lens

“…Available approaches of infrared athermalization include the active mechanical [2], passive mechanical [3] and passive optical [4] measures. As a computational imaging technique, wavefront coding is a powerful hybrid optical-digital technique for extending an operating temperature range of an infrared imaging system [5][6][7][8].…”