太赫兹同轴数字全息具有较低的光子能量和对非金属与非极性物质较高的穿透能力，越来越受到人们的重视。但由于零级衍射光和共轭像的影响，会导致重建像细节模糊，造成图像质量下降。通过仿真对比分析了相位恢复法在可见光和太赫兹数字全息中的应用，并通过研究重建像的均方差随记录距离和记录间隔的变化情况，验证了在太赫兹波段可以将两次全息图记录缩减成一次的成像方法。讨论了噪声对简化成像的影响，结果表明当全息图和背景都带有噪声时，相位无法恢复到预定值，随着噪声的增大，重建像会越来越模糊，直至完全被噪声掩盖。

Terahertz inline digital holography with lower photon energy and higher penetrating power to nonmetallic and nonpolar substances has attracted increasing attention. However, the zero- order diffraction light and conjugate image will degrade the details of reconstructed image and cause the loss of image quality. The applications of phase retrieval algorithm in the visible and terahertz digital holography are compared and analyzed by simulation, and the imaging method that the number of hologram recording is reduced from two to one can be verified after studying the mean square error of reconstructed image changing with the recording distance and recording interval. The influence of noise on the simplified imaging is discussed, and the results show that when the hologram and background are both contaminated by noise, the phase cannot be restored to the predetermined value and with the increase of noise, the reconstructed image becomes more and more blurred until the image is covered completely by noise.