设计了一种电容位移传感器在线标定平台, 用于位移的高精度调节和检测。该平台的运动对称中心轴、测量光路的对称中心轴和传感器的传感轴共轴, 故从测量原理上减小了阿贝误差。标定平台具有z/tip/tilt调节功能, 保证了传感器的传感面和被测面板的被测面之间的装调对准。介绍了标定平台的组成和标定方法的原理, 采用对称平行四边形机构实现了微位移调节, 基于柔度矩阵法(CMM)分析了导向机构的输出柔度和行程。试验测得动平台行程为735.162 μm, 和有限元法(FEM)、CMM计算结果的误差分别为7.410%和4.633%, 满足行程误差要求。经过标定补偿后, 传感器的线性度由0.014 21%提高至0.006 231%。实验结果显示, 该线性度标定方法精度高, 标定后的传感器满足位移精密调节机构使用要求。

An on-line linearity calibration platform for capacitive displacement sensors is proposed to implement the high-precision adjustment and the measurement of displacement. The symmetry axis for movement, the measuring axis of an interferometer and the measuring axis of a sensor are collinear in the platform, so that the Abbe error is decreased in principle. For the z/tip/tilt adjustment function in the platform, the alignment between the sensor and the target surface is realized. The composition and principle of the calibration method are introduced and the micro-displacement is adjusted by a symmetrical parallelogram mechanism. Then, the output compliance and stroke of the guiding mechanism are analyzed based on Compliance Matrix Method(CMM). The experiment result demonstrates that the stroke of the calibration platform is 735.162 μm and the errors are 7.410% and 4.633% comparing with that of the Finite Element Method(FEM) and CMM, respectively, which meet the requirement of the stroke. Moreover, the sensor linearity is improved from 0.014 21% to 0.006 231% after calibration calculation. The linearity calibration method has high-precision and it satisfies the requirement of fine displacement adjustment of the mechanism.