利用中波和长波红外双波段联合探测，可以有效地提高机载光电探测设备的性能。介绍了四反射镜和光学被动式无热化技术的设计方法，设计了一套双波段双视场折反式光学系统。系统由四反射望远系统和二次成像会聚系统两部分构成，采用光学被动无热化设计，满足轻量化、小型化、无热化的设计要求。光学工作波段为4.5~5.1 μm/7.7～9.7 μm，焦距为100/300 mm，变倍比为3，F数为2，结构紧凑，满足100%冷光阑效率。像质评定结果表明，光学系统在-60 ℃～70 ℃温度范围内，双波段双视场成像质量良好。

The use of medium-wave and long-wave infrared dual-band combination can effectively improve the performance of airborne photoelectric detection device. The design method using four mirrors and optical passive athermal technology is introduced. A dual-band and dual fields-of-view (FOVs) catadioptric optical system is designed. The system consists of two parts, i.e., the four-mirror telescope system and secondary imaging aggregation system, and uses optical passive thermal design. It meets the design requirements of lightweight, miniaturization, and athermalization. The optical system works in the 4.5~5.1 μm and 7.7~9.7 μm wavelength bands. It can achieve the zoom of 100 mm and 300 mm, with the zoom ratio of 3, F number of 2, and a compact structure and can meet 100% cold shield efficiency. The final optical design along with their modulation transfer function (MTF) is presented, showing excellent imaging performance in dual FOVs and dual-band at the temperature range between -60 ℃ and 70 ℃.