2m量级SiC非球面反射镜的摆臂轮廓检测

Measurement of 2m SiC Asphere Mirror Based on Swing Arm Profilometer

提出采用摆臂式轮廓检测的方法,实现超大口径Si C反射镜面形的高精度轮廓检测。阐述了采用摆臂轮廓仪检测超大口径反射镜的基本原理和具体实施流程;介绍了基于扫描线交点高度一致性的特点进行面形重构的算法,以及针对离焦量测量不准的问题,采用激光跟踪仪对面形离焦量进行辅助测量的手段,建立了综合优化的检测模型;结合实例对口径为2040 mm的同轴抛物面Si C反射镜进行了摆臂轮廓检测,检测精度均方根(RMS)为0.46μm,与干涉仪检测结果对比偏差0.03μm。该技术与加工机床集成实现了反射镜的在位检测,以非球面的最接近球面为测量基准,提供了一种精确、高效地测量超大口径光学非球面面形的方法,满足了大口径Si C反射镜在研磨阶段的高精度轮廓检测需求。

For the measurement of large Si C mirror before interferometry test, the method of swing arm profilometry（SAP） is introduced. The basic principle and flow chart of SAP are presented; with surface reconstructed based on consistency of surface height at scan crossings and defocusing amount of mirror surface measured with a laser tracker as supplementary, an optimized test model is built. As an example, a 2040 mm Si C mirror is tested by SAP, with accuracy of 0.46 μm root mean square（RMS）, which is 0.04 μm deviation from interferometric test. As a best-fitting sphere being basement of the test, in situ metrology is implemented; this method provides an accurate and efficient way to measure a large mirror, and meet the need of high-accuracy measurement of large Si C mirrors during grinding.