针对制冷型320×256焦平面阵列探测器，设计了一套用于机载光电探测设备的长波连续变焦红外光学系统。光学系统采用锗和硒化锌两种普通红外光学材料，通过引入非球面和衍射面很好地校正了系统的色差和轴外像差，使得系统整个连续变焦过程中16 lp/mm处MTF均大于0.35。系统仅由6片镜子构成，工作波段为7.7~10.3 μm，F数为3，满足100%冷光阑效率，实现了50~400 mm的连续变焦，变焦曲线光滑。像质评价结果表明该系统成像质量良好，结构紧凑。

A set of long-wave infrared continuous zooming optical system was designed for airborne photoelectric detection equipment,based on long wavelength 320×256 element cooled thermal IR Focal Plane Array(FPA) detector.The optical system is made of two kinds of common infrared materials,Ge and ZnSe.By introducing a diffractive surface and three aspheric surfaces,the chromatic aberration and the off-axis aberration are well corrected, and the Modulation Transfer Function (MTF) of the system is kept above 0.35 for all continuous zooming ratios at the spatial frequency of 16 lp/mm.The system is consisted of 6 lenses,has a F/number of 3,working wave band of 7.7~10.3 μm,and cold shield efficiency of 100%.Continuous zooming from 50 mm to 400 mm is realized with smooth zoom paths.The results show that the compact structured continuous zooming system has pretty good imaging quality.