Zhang Xiangchao, Niu Zhenqi, Ye Junqiang, Xu Min
Opt Lett. 2021 May 1;46(9):2047-2050. doi: 10.1364/OL.415953.
Phase measuring deflectometry is a powerful measuring method of complex optical surfaces that captures the reflected fringe images associated with a displaying screen and calculates the normal vectors of the surface under test (SUT) accordingly. The captured images are usually set conjugate to the SUT, which in turn makes the screen defocused. As a result, the blurring effect caused by the defocus and aberrations of the off-axis catadioptric imaging system can severely degrade the phases solved from the blurred images. In order to correct the phase errors, the space-variant point spread functions (PSFs) are modeled using a skew-normal function. The phase bias is estimated by forward convolution between the captured images and the PSF models. Demonstrated with a highly curved aspheric surface, the measurement accuracy can be improved by three times.
相位测量偏折术是一种用于测量复杂光学表面的强大方法，它通过捕获与显示屏相关的反射条纹图像，并据此计算被测表面（SUT）的法向量。所捕获的图像通常设置为与SUT共轭，这反过来会使屏幕散焦。因此，离轴折反射成像系统的散焦和像差所引起的模糊效应会严重降低从模糊图像中解算出的相位。为了校正相位误差，使用偏态正态函数对空间变化的点扩散函数（PSF）进行建模。通过捕获图像与PSF模型之间进行前向卷积来估计相位偏差。通过一个高度弯曲的非球面表面进行演示，测量精度可提高三倍。
