离轴三反光学系统具有大口径、大视场、传输效率高以及没有色差等优点, 易于实现多谱段共孔径。介绍了一种离轴三反系统的设计, 其工作于红外中波 3～5 .m和红外长波 8～10 .m双波段, 口径 300 mm, F数为 3。设计中充分考虑加工检测和装调的易实现性, 特点为次镜采用球面, 主镜和三镜共面, 并且整个系统没有高次非球面; 选取合理的反射镜和结构件材料, 使系统具有良好的高低温环境适应性。

Off-axis three-mirror system has the advantages of large aperture, large field of view, high transmission efficiency and achromaticity, so it’s easy to achieve co-aperture in wide wave band. An off-axis three-mirror system with 300 mm aperture and F/# 3 is introduced, which works in mid-wave(3-5 .m)and long wave(8-10 .m)IR band. It is considered adequately in design that the system will be easy to test and assemble. The system can well adapt wide environment temperature change by choosing right materials.