非球面Null Lens补偿检测中采用激光跟踪仪测量几何参数方法研究

Research on Geometric Parameter Measurement Method Using Laser Tracker in Null Lens Asphere Testing

随着非球面反射镜口径和顶点曲率半径的增大,传统的非球面几何参数测量不能满足要求。为实现非球面几何参数的高精度测量,针对广泛应用的补偿器检测非球面光路,开展了几何参数分析和测量方法研究。将二次常数和顶点曲率半径的理论近似误差关系与Zemax仿真进行对比验证,确定了测量需求及数据复核方法;阐述了采用激光跟踪仪测量几何参数的基本原理,说明了特征转换过程及建模、数据处理方法。测量实验结果表明,对2 m量级的测量光路,顶点曲率半径的重复性测量精度±0.039 mm,二次常数的重复性精度±2.05×10-5,离轴量的重复性精度±0.055 mm。说明采用该方法能够有效实现非球面参数的测量,并具有很高的重复性测量精度,适合大口径、长曲率半径非球面的几何参数测量。该方法绝对检测精度需要进一步分析。

Traditional measuring methods of geometric parameters of asphere cannot meet the accuracy requirements as the aperture and vertex radius of curvature increase. In order to realize high accuracy measurement of geometric parameters, analysis and measuring methods are studied according to the null lens testing. The theoretical relationship between radius error and conic constant error is compared with the simulation results, then the requirements of measurement and data processing check method are determined. The basic principles of using laser tracker to measure geometric parameters are presented. The feature transformation, modeling and data processing methods are introduced. Experimental results show that the repeating precision of radius, conic constant and off-axis distance are ±0.039 mm, ±2.05×10^-5 and ±0.055 mm, respectively. The high repeating accuracy indicates that this method is suitable for geometric parameters measurements, especially for large aperture and long radius aspheres. The absolute accuracy needs to be further analyzed.