中文摘要：

同轴数字全息具有光路简单、光源相干性要求低、充分利用相机空间带宽积等优点，在各领域得到了广泛的应用，但其固有的离焦共轭像会严重降低再现像的质量。相位恢复算法能够借助记录面的光场强度，恢复出丢失的相位信息，去除共轭像的影响。对同轴全息的记录与再现、相位恢复算法的分类和基本步骤逐一进行了介绍，并按照约束条件、多物距、多波长、初始值优化这四个方面对各种相位恢复迭代算法进行了分析和讨论，列举了各种算法的约束条件和实验结果，最后对算法的发展进行了展望。

英文摘要：

In-line digital holography is widely applied in many areas due to its simple optical path, low requirement of coherence and fully utilization of camera＇s bandwidth. The reconstruction quality of in-line digital holography, however, suffers from the superposition of twin-image contamination, which can be solved via phase retrieval algorithm. By iteratively applying certain constraints on an estimate of an object in real and reciprocal domain, the real image is well seperated from the unwanted components. The recording and reconstruction process of in-line digital holography and fundemental phase retrieval methods including Gerchberg-Saxton （GS）, error reduction （ER） and hybrid input-output （HIO） algorithms are introduced. Then, the phase retrieval algorithms for in-line digital holography is divided into four categories, i. e., constraints, multiple axially recording, wavelength divergency and initial guess. The constraints and experimental results of these phase retrieval algorithms are listed. Finally, a prospect is given for the possible improvement and potential applications of phase retrieval methods in in-line digital hologaphv.