平面面形绝对检验技术测量误差分析

Measurement Error Analysis of Absolute Flatness Test

绝对检验消除了参考面面形误差对干涉测量精度的制约,可实现纳米精度的面形测量。对现有主要平面面形绝对检验技术进行了总结比较,运用泽尼克多项式前36项构建被测平面,对边缘噪声、平面原始精度、旋转角度与偏心误差等因素对典型平面面形绝对检验技术测量精度的影响进行了模拟分析。绝对检验对被测平面原始精度、干涉图分辨率和旋转角度误差不敏感,对边缘噪声和旋转偏心误差敏感。实际测量中,旋转轴心对准误差应小于2 pixel,测量中心面积比取95%左右。

Absolute test eliminates the errors of reference flats which limit the accuracy of interference measurement,so that the figure of optical surface can be measured with nanometer accuracy.We give a brief review and comparison of several mainstream absolute flatness test methods.And then the impacts of edge noise,figure grades of the flats under test,rotation angle error and rotation eccentricity,etc.on the measurement error of absolute test are analyzed respectively.The first 36 Zernike polynomial terms are used to construct the virtual flats under test.It is found that the measurement error is not sensitive to figure grades of the flats,resolution of interferogram and rotation angle error.However,it is sensitive to edge noise and rotation eccentricity.In an absolute test system,it is recommended that the alignment error of rotation axis is less than 2 pixel,and the ratio of central area is about 95%.