能动磨盘变形检测中的各误差因素分析

Error analysis of deformation measurement of active lap

针对现有Ф530mm能动磨盘的检测系统(有效检测口径Ф420mm),系统分析了检测过程中的球头误差、传感器安装角度误差和坐标定位误差,并给出了各项误差对检测精度的影响。同时,还针对检测基座不完全水平的问题建立模型,应用最小二乘法实现了检测数据的去倾斜处理。给出了实测数据去倾斜前后和误差补偿前后的检测精度对比情况,结果表明去倾斜算法能较好地还原实测数据,补偿检测中的系统误差有助于提高检测精度。

In the progress of large aspheric mirror manufacturing, computer controlled active lap（CCAL） has been prowed tobe a useful tool with high precision and efficiency. Before polishing, the deformation measurement of the lap is necessary. Themeasurement system has 60 high precision displacement sensors. Error analysis and essential data processing of the measurementsystem are putting forward. The main error contains ball-probe error as the system error, angle error of fitting sensors and errorof coordinate offset as the stochastic error. In the mathematic model established based on the characteristic of paraboloid and eoor-dinate transform, the influence of the three kinds of errors is calculated. After some interrelated compensation and data process-ing, the result gotten shows that the measurement precision improves.