介绍了一种基于像差理论的离轴三反光学系统初始结构的求解方法，使用此方法设计了一个适用于空间遥感系统的离轴三反光学系统。该系统的工作波段为7.7~10.3 μm，焦距为1000 mm，系统F数为2，视场角为1°，给出了其具体的优化过程并进行了性能分析。设计结果表明,该系统满足空间遥感光学系统要求的长焦距、大口径、成像良好、结构紧凑等特点，验证了该方法的正确性和可行性。

A method for calculating the initial structure of off-axis optical system with three mirrors based on aberration theory is introduced, and a three-mirror off-axis optical system is designed with this method, which is adaptable for space remote sensing system.The system has a wave band of7.7~10.3 μm, effective mirror length of 1000 mm, F-number of 2, and the full FOV is 1°.The detailed optimization process is presented.It shows that the system has the advantages of long focal length, large diameter, high image quality and compact structure, which can meet the requirements of the space remote sensing system.