相位恢复算法被广泛应用于去除同轴数字全息共轭像。其中，多采样距离相位恢复算法相比于基于单幅全息图的相位恢复算法，尤其是在两幅全息图的重建算法中，重建精度更高且收敛速度更快。针对采样距离和采样间隔对再现物光波前的精度的影响，通过记录不同采样距离的多幅数字全息图，进行相位恢复。通过分析比较再现相位像的标准化均方根误差，得到优化算法的最佳采样距离和采样间隔。结果表明，采样距离在130~160 mm范围内时误差较小，采样距离为150 mm、采样间隔为2 mm时误差最小，仅0.0096。

Phase retrieval algorithm is widely used to eliminate the unwanted conjugate image for in-line digital holography. Compared with the phase retrieval algorithms based on single hologram, phase retrieval with images recorded at multiple distances could improve the precision and convergence speed apparently, especially for the reconstruction of two images. However, it is critical to optimize the recording distances for the two images to achieve high precision and the true value of the reconstructed images. We record a lot of digital holograms at axially different planes in experiment. After analyzing the normalized root-mean-square (NRMS) error of the data, we conclude that the algorithm is suitable for the distance between 130 mm and 160 mm. And the conclusion can also be made that the reconstructed image which has the highest precision is achieved when the object distance is 150 mm and the object distance interval is 2 mm for which the NRMS error is 0.0096.