用于大口径平面镜检测的五棱镜扫描检测系统装调技术研究

Study on Alignment Technology of Scanning Pentaprism System for Testing Large Flat Mirrors

五棱镜扫描检测具有结构简单、检测周期短等优点,可实现低阶像差的高精度检测,是指导大口径、超大口径平面镜光学加工的有效途径。基于光线矢量追迹理论,建立五棱镜扫描检测系统数学模型,并采用最小二乘法推导出系统测量精度与系统主要光学元件角度变化量之间的解析表达式。在此基础上,分析了系统测量精度对元件装调精度的灵敏度,给出了系统精确装调的实施方案,并进行了系统装调试验,探索出适合大口径平面镜检测的五棱镜扫描检测系统装调流程。实验结果表明,由装调过程引起的系统测量误差可控制在40 nrad以内。通过理论分析和装调试验,验证了使用五棱镜扫描检测技术进行大口径平面检测的可行性。

The scanning pentaprism system （PPS） is an effective method for guiding large flat optical processing, due to its advantages such as simple structure, high testing efficiency and precise measurement of low order aberrations. This paper established PPS＇s mathematical model according to vectorial ray tracing theory, the analytical relationship between PPS＇s performance and its components＇ angular motion is obtained by least square fitting, which is useful for analyzing PPS＇s sensitivity to components＇ alignment errors. Afterward a fine alignment procedure is proposed. Experimental results show that PPS＇s measurement error caused by alignment is better than 40 nrad after fine alignment. The result shows that PPS is practical for large flat testing.