为了模拟用于球面面形高精度检测的相移点衍射干涉仪的测试过程，介绍了点衍射干涉仪的基本工作原理，分析了相移点衍射干涉仪的测量误差。利用光学设计软件和自行编制的软件建立了点衍射干涉仪的检测模型，利用该模型分别推导了参考光束和测试光束在干涉场的复振幅分布，模拟了测量过程。根据光的相干理论，通过改变被测镜的位置，实现移相，得到移相干涉图。最后对一设定的被检镜进行实验模拟，生成了两组对称倾斜的13步移相干涉图，对干涉图处理后计算得到了被检镜的检测面形。结果表明，在不引入硬件误差时，由相位提取和波面反演造成的检测面形与设定面形偏差为RMS值0.0783 nm，PV值0.5656 nm。

To simulate the testing procedure of a Phase Shifting Point Diffraction Interferometer(PSPDI), the working principle of the PSPDI was introduced and its measuring errors were analyzed. On the basis of the lens design software and a inhome software, a test model for the PSPDI was established. By using the test model, the complex amplitudes of the reference beam and test beam were captured in an interference field, furthermore, the testing procedure was simulated. Depending on the optical coherent theory, the phase shifting was realized by changing the positions of testing mirror, and the phase shifting interferograms were acquired. Finally, for a given mirror, the model was used to generate two groups of 13-step phase intergrams with a symmetrical tilt. After processing the interferograms, it is shown that the accuracies of testing spherical mirror are 0.0783 nm(RMS) and 0.5656 nm(PV).