自适应聚焦下基于强度传输方程的相位恢复

基于强度传输方程的非干涉相位恢复方法是通过对强度图像求解方程来获取相位的一种途径。在图像采集过程中，对聚焦图像的选择是很重要的。但该过程通常是由主观方法来确定，从而导致聚焦定位不准确，进而影响相位恢复结果的精度。首先，提出了一种基于强度传输方程的自适应聚焦相位恢复方法；其次，使用边缘占空比对采集图像进行定位，在求解相位之后进行循环角谱传播，直到边缘占空比定位位置不变，即被认为是定位到了最佳聚焦位置；最后，再使用强度传输方程求解样本的相位。结果证明:该方法不仅提高了相位恢复的准确性而且减少了获取大量图像的次数。在模拟实验中，恢复相位与原始相位的相关系数达到0.9866，均方根误差为0.3050。在实际的微透镜阵列实验中，用所提出的相位恢复方法恢复出的微透镜高度与真实高度误差仅为5.7%，证明了在显微成像领域，所提算法可以定位到最优聚焦位置，有利于自动聚焦技术的发展，进而提高相位恢复的精度。

Phase retrieval based on the transport of intensity equation under adaptive focus

The non-interference phase retrieval method based on the transport of intensity equation was a method to obtain the phase by solving the intensity images. In the process of image acquisition, the selection of in-focus image was very important. But it was usually determined by subjective methods, which led to inaccurate in-focus positioning, thus affecting the accuracy of phase results. Firstly, an phase retrieval method based on the transport of intensity equation under adaptive focus was proposed; Secondly, the edge duty ratio was used to locate the acquired images in this algorithm. After solving the phase, the optimal focus position was located when the edge duty ratio locating position kept unchanging by the circular angular spectrum propagation; Finally, the phase of the sample was solved by using the transport of intensity equation. The result show that this algorithm not only improved the accuracy of phase retrieval, but also reduced the time to obtain a large number of images. In the simulation experiment, the correlation coefficient between the retrieval phase and the original phase reached 0.9866, and the RMSE error is 0.3050. In the actual experiment of microlens array, the error between the true height of the microlens and the height solves by the phase retrieval method proposed is only 5.7%, which proves that the algorithm can locate the optimal focus position in the field of microscopic imaging. And the algorithm is conducive to the development of auto-focus technology and improves the accuracy of phase retrieval.