基于光强传输方程与SLM的快速相位恢复

基于光强传输方程（TIE）的相位恢复技术，可以通过测量一系列垂直于光轴分布的散焦强度图，直接求解得到光场的相位信息。传统的基于TIE的强度图像采集系统在获得散焦图像时需要机械移动。通过在空间光调制器（SLM）上加载透镜相位图，使其实现可编程透镜的功能，任意改变此透镜的焦距值，可以实现不同的散焦距离，从而避免采集图像过程中CCD的移动。根据不同的算法理论，设计了两种光强图像采集系统。由于日常生活中使用相机拍照时，透镜的相位调制作用不可忽略，使用SLM代替含透镜的光传播模型中透镜的作用，设计了第一种实验装置。此外，通过在4f系统的频率域位置放置SLM，设计了第二种实验装置。真实实验的结果验证了这两种方法的有效性和正确性。

Rapid phase retrieval using SLM based on transport of intensity equation

The transport of intensity equation(TIE) offers an experimentally simple technique for computing phase information directly from several defocused images. In this work we developed the traditional TIE intensity acquisition system. In order to avoid the shifting of CCD, a quadratic phase pattern was displayed on the SLM to provide a lens effect for realizing different defocus distance by varying the focal length of the lens. Two kinds of phase imaging experimental configurations guided by two different theories were designed. In most instances, since a camera is used to capture images in which the phase modulation of lens cannot be ignored, the former intensity acquisition system was designed based on the single lens optical propagation system, and the relationship between the focal length and the image distance in the lens law was used to facilitate the varying of the defocus distance by changing the phase pattern displayed on the SLM. The latter was designed by locating a SLM in the Fourier domain of the 4f setup, according to the Fourier transform property of the lens and the Fresnel diffraction theory, the relationship between the defocus distance and the focal length of the quadratic phase pattern can be derived. The experimental results verify that the proposed phase retrieval methods are reasonable and correct.