针对多模制导中长焦距红外光学系统结构紧凑及宽温度范围热稳定性的要求, 设计了一种中波红外折反光学系统。该系统根据其它模式制导的要求, 采用固定焦距和口径的主镜, 通过二次成像,在保持长焦距的同时减小了透镜的口径,降低了到达中继成像系统主光线的高度, 同时也降低了制造成本。设计了波长为37~48 μm、焦距f为300 mm、F数为2的中波红外成像系统。结果表明, 该系统结构紧凑像质优良, 各视场光学传递函数均大于06, 接近衍射极限, 并且在-50~70 ℃可实现光学被动消热差。针对该光学系统进行了公差分析并提出了抑制杂散辐射的方法, 该系统满足实际加工和应用需求。

In order to meet the requirement of compact structure and athermal stability with wide temperature range, a middle infrared catadioptric optical system is designed. According to the requirements of other guided modes, the focal length and aperture of the primary mirror is fixed. The height of the principal ray reaching the relay system can be reduced. The aperture of the lens can be decreased, which will lower the cost. A compact infrared imaging system with a wavelength 37-48 μm, focal length f=300 mm, F number 2, is presented in this paper. The results show that the system performs well and the optical transfer function of each field is close to the diffraction limit. Between –50-70 ℃, passive optical athermalization can be realized in this system. For this system, the tolerance analysis and some ways of resisting the stray light are presented at last. It shows that the MIR system meet the demand of actual processing and application.