一种基于高斯拟合的衍射光斑峰值位置的定位方法

A method to locate the peak of diffraction pattern on base of Gaussian fitting

基于衍射理论的分块镜共相位误差检测中,衍射光斑最高峰峰值位置的定位精度直接影响最终的测量精度,峰值定位精度受限于CCD的像元尺寸。针对衍射光斑的特点及最高峰峰值位置亚像元的定位精度要求,提出了基于高斯拟合的最高峰峰值位置的定位方法。在采样间距为5μm,采样点在10个左右的情况下,定位精度高于600nm,与传统的质心法及Hilbert变换法相比,精度可以提高20%以上,且鲁棒性好。实验结果表明,该方法是一种有效的亚像元精度的峰值定位方法,为提高共相位误差的测量精度提供有效途径。

In piston detection on base of diffraction, the measurement accuracy is determined by the location accuracy of the highest main peak. The peak location of the diffraction pattern should be located at sub-pixel accuracy. A method on base of Gaussian fitting is supposed to locate the peak according to the character of the diffraction pattern. At the condition of 10 sampiing points or so with the sample distance to be 5μm, the location accuracy of this method is better than 600nm. The accuracy is improved by 20% compared with the traditional methods such as centroid method and Hilbert transformation. The experimental results show that it is a valid method of sub-pixel accuracy peak location. It is also a valid way to improve the measurement accuracy in piston detection.