针对320×240元致冷型凝视焦平面阵列探测器，设计了一种中波红外光学补偿三视场光学系统。该系统由变 焦物镜系统和二次成像系统构成，包括8块透镜(引入3个高次非球面，其余均为球面)，并采用两个反射镜折叠光路。利用光学补偿变焦 原理和光学设计软件给出了系统的光学外形结构图，并对其像质和工艺性进行了分析。该系统可以通过对一组透镜的轴向定点移动实现 20°×15°、3.5°×2.6°和1.3°×1°三个视场的切换，系统变倍比为 1∶15。各视场在16 lp/mm空间频率处的光学传递函数(MTF)值均大于0.5，弥散斑直径的均方根(RMS) 值均小于20 m。工作波段为3.7 ～ 4.8 m，满足100 %冷光阑效率。该系统结构紧凑，工艺性好，成像质量高。

A middle infrared optically compensated triple-field-of-view optical system is designed for a 320×240-element cooled staring focal plane array detector. The system is composed of a zoom object lens system and a secondary imaging system. It contains eight lenses and two reflectors. The schematic diagram of the optical configuration of the system is given by using the optical compensation principle and an optical design software. Its image quality and processing properties are analyzed. The result shows that the system can implement the switch of three fields of view of 20°×15°, 3.5°×2.6° and 1.3°×1° with a zooming ratio of 1 to 15 by axially moving one lens group. Each field of view has an optical transfer function (MTF) greater than 0.5 at a spatial frequency of 16 lp/mm and has a root-mean-square value less than 20 m for its diffusion spot diameter. The system operates in the waveband of 3.7 m to 4.8 m. It has the features of compactness, good processing property and high image quality.