光学学报, 2009, 29 (8): 2142, 网络出版: 2009-08-17   

图像噪声对相位变更波前传感的影响研究

Influence of Noise to Phase Diversity Wavefront Sensing
作者单位
北京理工大学光电工程系, 北京 100081
摘要
相位变更(PD)方法是一种基于两个或多个不同离焦面图像来恢复光瞳畸变波前相位的光学波前传感技术。它使用相对简单的光学系统, 运用统计最优化计算方法, 借鉴图像处理中的一些技术手段, 在得到波前信息的同时, 还可以得到目标的清晰像。但当图像存在噪声时, 用于优化算法的误差函数会出现许多局部极值点, 这会影响算法的收敛速度, 甚至会导致算法陷入局部极值而得不到正确的估计解。为消除这些影响, 需对图像进行降噪处理。在实际光学系统中, 由于光瞳大小的限制, 实际得到图像的高频信息一般要远少于低频信息, 所以宜使用低通滤波器对图像进行滤波。仿真中通过比较各种滤波器性能, 针对含有加性高斯噪声的图像, 采用了对图像模糊影响较小的巴特沃思(Butterworth)低通滤波器。研究结果表明, 利用滤波器处理后的图像, 相位恢复结果的均方根误差(RMSE)比未使用滤波器有明显下降。
Abstract
Phase diversity (PD) is a kind of wavefront sensing technique based on the measurement of two or more object images. The optical system involved is relatively simple. Using the methods of optimization and image processing, it can jointly estimate the phase aberration as well as the object itself simultaneously. However, when additive noise appears in the images, many local minimum are produced in the function function. Consequently, the convergence of the algorithm is influenced, or even worse, the algorithm will be trapped in the local minimum which are far from the global minimum. It is necessary to preprocess the image to lower the affection of noise before using the method of optimization. Low pass filter is chosen to eliminate the noise because the images contain less high-frequency components than the lower-frequency ones due to the finite size of the pupil of the optical system. The Butterworth low-pass filter is chosen after considering the performance of some low-pass filters. The research results demonstrate that the speed of convergence and precision of the algorithm is dramatically improved when the filtered images are used, and the RMSE between the estimated and real object is less than before.

王欣, 赵达尊. 图像噪声对相位变更波前传感的影响研究[J]. 光学学报, 2009, 29(8): 2142. Wang Xin, Zhao Dazun. Influence of Noise to Phase Diversity Wavefront Sensing[J]. Acta Optica Sinica, 2009, 29(8): 2142.

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