提出了一种新的三维物体计算全息图的合成方法.在三维傅里叶旋转抛物面获取频谱理论的基础上，利用圆形扫描获得少量投影，采用多个半圆提取方式获取三维物体的频谱信息并采用共轭对称延拓计算全息编码得到计算全息图.传统方法中，在每幅投影上仅提取一个圆形的频谱信息.在同等投影数量的情况下，通过半圆方式在每幅投影上提取多于一个圆形信息的方法获得频谱信息，提高了每幅投影的信息利用率和全息图再现图像的质量.数字再现的实验证明了该方法的有效性及优越性.

A new method was proposed to synthesize computer-generated hologram of three-dimensional object. According to the principles of paraboloid of revolution in three-dimensional Fourier space, spectra information of three-dimensional object was gathered. A series of projection images of three-dimensional object was recorded by circular scanning method, then the information of the projection spectra in several semi-circles form was extracted and encoded into computer-generated hologram based on conjugate-symmetric extension. In the traditional method, the spectrum information is extracted in a circular form from each projection. In the case of an equal number of projections, the proposed method can extract more spectrum information. So it can effectively improve utilization of each projection, and the quality of reconstructed image from computer-generated hologram. Experimental results validate the proposed method and its good performance.