设计了适用于制冷型320×256 中波红外凝视焦平面阵列探测器和320×256长波红外凝视焦平面阵列探测器的共孔径消热差折反射式红外双波段光学系统。该系统在中波3.7~4.8 μm, 长波7.7~11.7 μm, 环境温度10~40 ℃下工作, 其焦距为292 mm, 视场角为1.56°×1.875°, F/＃为1.93, 满足100％冷光阑效率。设计的系统共用主镜、次镜和准直镜组, 利用分光镜实现中波红外、长波红外光谱分光, 后接各自的校正镜组校正剩余像差。给出了设计原理、设计过程和工程设计时需考虑的一些因素, 通过选择合适的光学材料、机械材料和分配光焦度, 实现了两路系统在10~40 ℃环境温度下具有良好的成像性能。该系统成像质量良好、可加工性好、装配难度小、工程可实施性强。

A set of common aperture athermal catadioptric optical system with infrared dual bands is presented for 320×256 MWIR and LWIR staring focal plane array detectors. The system works at the wavelength of 3.7-4.8 μm, 7.7-11.7 μm, and the environment temperature of 10-40 ℃.Its working parameters are the effective focal length of 292 mm, field of view of 1.56°×1.875°, F/＃ of 1.93 and the cold shield efficiency of 100％.The LWIR system shares the primary mirror, secondary mirror and collimating lens with the MWIR system. The beam splitting of the MWIR and LWIR is achieved by a spectroscope and their aberrations are eliminated by correcting lenses respectively. The design principle, design process and some considering factors in engineering design moment are presented. By choosing appropriate optical materials, mechanical materials and assigning the optical power, the common aperture athermal catadioptric optical system obtains good image quality during 10 ℃ to 40 ℃. It shows good imaging quality, good machining ability, easy to be assemble, and suitable for engineering applications.