论文部分内容阅读
扩展目标夏克-哈特曼波前传感器子图像之间偏移量的计算是影响波前传感精度的关键,通常采用相关算法来实现,并通过抛物线插值等方法来达到亚像元精度。子图像相对偏移量的计算也可以采用计算相关函数质心的方法来实现,其主要步骤是先计算子图像间的相关函数,在此基础上计算相关函数的质心,达到亚像元精度。通过仿真研究表明这种算法的精度与进行相关运算时的图像大小、计算质心时的相关函数窗口大小以及相关函数阈值的设定有关;同时,图像的信噪比也会影响算法的精度。研究表明,图像的信噪比小于1时,质心算法的计算误差相对较大;当图像的信噪比高于2时,相关函数质心算法的误差大约是抛物线插值法误差的一半。实验结果与仿真结果也基本吻合。
Extended Target The calculation of the offset between the Shack-Hartmann wavefront sensor sub-images is the key to the accuracy of the wavefront sensing. Usually, the correlation algorithm is used to achieve the sub-pixel accuracy through parabola interpolation. The calculation of the relative offset of the sub-image can also be realized by calculating the centroid of the correlation function. The main step is to calculate the correlation function between the sub-images first, and then calculate the centroid of the correlation function to achieve the sub-pixel precision. The simulation results show that the accuracy of this algorithm is related to the size of the image, the size of the correlation window when calculating the centroid, and the threshold of the correlation function. Meanwhile, the SNR of the image also affects the accuracy of the algorithm. The research shows that when the SNR is less than 1, the calculation error of the centroid algorithm is relatively large. When the signal to noise ratio of the image is higher than 2, the error of the centroid algorithm of correlation function is about half that of the parabolic interpolation method. Experimental results and simulation results are basically consistent.