考虑到离轴三反系统内部结构和光路的复杂性, 直接分析离轴三反系统内部各反射镜的偏转误差对视轴的影响难度较大。因此, 提出一种将离轴三反系统模型简化为单反射系统模型来进行分析的方法, 并在该模型的基础上建立离轴三反系统视轴偏转误差的计算公式。最后, 利用Zemax软件创建离轴三反系统模型, 通过变动反射镜位置来模拟系统视轴的变化, 并得到成像点的坐标, 再将得到的像点坐标代入计算公式求解出系统视轴的转动量。通过结果对比, 求解出视轴的转动量相对于仿真的最大误差不超过4%, 验证了基于单反射模型建立的理论分析方法的正确性。

Considering the complexity of internal structure and optical path of the off-axis three-mirror system, it is difficult to directly analyze the effect of deflection error of each mirror inside the off-axis three-mirror system on the line-of-sight. Therefore, a method of simplifying the off-axis three-mirror system model was presented to a single-mirror system model for analysis. Then, based on the model of single reflection system, the formula of the deflection error of the off-axis three-reaction was derived. Finally, the model of off-axis three-mirror system was created by Zemax software, the change of the line-of-sight of the system was simulated by adjusting the position of the mirror and the coordinates of imaging can be obtained, then the deflection value of the system′s line-of-sight was solved by substituting the image coordinates into the calculation formula. From comparing the results, the maximum error of the deflection of the line-of-sight relative to the deflection of the line-of-sight in the simulation is not more than 4%, which verifies the correctness of the theoretical analysis based on the single reflection model.