基于光程变化量的反射式光学系统敏感度理论分析与降敏设计方法

The final performance of an optical system depends not only on its theoretical design, but more importantly, on various error-causing factors such as surface processing, alignment position, and system stability during its construction. To explore the influencing factors and the error sensitivity of a reflective optical system, a coaxial two-mirror system is considered as the research object. The optical path variation (OPV) caused by a misalignment error is proposed as the evaluation index of the error sensitivity of the optical system, and the mathematical expression of the OPV caused by the mirror position misalignment factor is deduced theoretically. By using a standard Ritchey-Chretien system and the ray tracing method, the OPV caused by various disturbances is calculated. Compared with the theoretical value, the relative error is approximately 1%, which proves the accuracy of the theoretical expression of the OPV. Based on the theoretical study of OPV, a desensitization design method for a coaxial reflective optical system with an OPV is proposed and established. Considering a coaxial two-mirror system with a focal length of 5 600 mm as an example, an optical system that meets the OPV and wavefront error index is designed after 15 rounds of iterative optimization. The accuracy of the OPV as the sensitivity evaluation standard and the effectiveness of the desensitization design method are verified by the relationship between the OPV and the wavefront error modification.