平面光学元件PMD面形检测的调整技术研究

Research on the Adjustment Technology of PMD Shape Measurement for Optical Flat Element

针对相位测量偏折术(PMD)检测平面光学元件面形的光路结构,系统地分析了各部件因各自由度的不确定度变化对重建面形的影响,并且提出了一种高精度的平面元件调整方法。通过对相移算法得到的显示器坐标与通过光线追迹得出的参考面显示器坐标进行比较,能够将被测镜调节至理想测试状态,从而能准确求出被测面上各点斜率,再采用波前重建算法,实现了光学元件面形重建。实验结果显示,有效口径为Ф140mm的平面元件在去掉Zernike多项式前6项的面形数据与干涉仪的测量结果差值在RMS=5nm以内,结果远优于未经过该方法调整的结果。因此,该调整方法可行,能够有效完成对平面元件的精密调整,具有很大的应用价值。

According to the light path structure of the flat optical surface detection by phase measurement deflectometry （PMD）, the influence of the test components＇ uncertainty variation caused by freedom degree on the reconstructed surface is systematically analyzed in this paper. And a kind of high accurate optical flat element adjustment method is proposed as well. By comparing the display coordinates obtained by the phase shift algorithm with the reference plane display coordinates obtained by ray tracing, the measured mirror can be adjusted to an ideal test status so as to accurately obtain the slope of each point on the measured surface. Then, the surface of optical elements can be reconstructed by the wavefront reconstruc- tion algorithm. The experimental results show that the maximum of RMS difference between the test results and the inter- ferometer measurement result is only 5 nm when the first 6 items of the Zernike polynomials is removed for a flat optics with an efficient diameter of Ф140 rnm. The result is far better than the ones without this adjustment. The adjustment method is feasible and can effectively complete the accurate adjustment and reach a high accuracy for a measurement of flat optics.