中波红外两档变焦光学系统

报道了一种用于320×240制冷型探测器的中波红外两档变焦光学系统。该系统采用二次成像、前组透镜轴向移动变焦的光学结构形式。根据探测器类型和实际的使用要求给出了系统的光学参数，并利用光学设计软件对系统的像质进行了的分析。结果表明，该系统可以实现焦距为180/60两档变焦，工作波段为3～5μm，F数为1.96，满足100％冷光阑效率，截止频率16lp/mm处的MTF值大于0.6，结构简单，使用方便，像质好。

Mid-wavelength infrared dual field-of-view optical system

For cool 320×240 detector with staring focal plane array, a middle infrared continuous zoom optical system is presented. The optical system,which is composed of 8 lens, adopts the optical structure form of secondary imaging and front group lens moving along the optical axis. Based on practical application requirement and feature parameters of the detector, the optical design parameters are given. Then used zoom system principle and optical design software the schematic diagram, modulation transfer function (MTF) curver, spot diagram, and root mean square value (RMS) of the spot diameter are investigated. The parameters of the system is 1.96 f/number, 100% cold shield efficiency, 180mm/60mm effective focal length (EFL), 3-5 μm spectrum region, and 75% transmission. The optical system is analyzed from two mode of narrow field of view (NFOV) and wide field of view (WFOV). It has the advantages of simple structure, high image quality. And moreover, only one aspheric surface is adopted in the system, so the system has the benefits of low price and easy to machining and adjust.