相移点衍射干涉仪（PS/PDI）的检测精度取决于衍射板中针孔衍射产生的参考球面波质量，而针孔的直径是影响参考球面波质量的一个重要因素。基于矢量衍射理论，以会聚光束作为入射光，分析了针孔厚度和直径、加工误差以及入射光源单项像差和综合像差对衍射波面质量的影响。仿真数据表明，为了获得数值孔径为0.2， 波前误差均方根(RMS)值不大于1.4×10-3λ的理想球面波，在针孔的实际加工制作中，应选200 nm厚度铬膜，直径为1.5 μm的针孔，并且满足仿真误差要求；对衍射板上窗口尺寸进行了仿真，结果表明窗口边长取60 μm时，仿真结果最优。用实验验证了设计结果的可行性。

The quality of the reference wavefront is constrained by the diameter of pinhole, which is the critical element that determines the precision of phase-shifting point diffraction interferometer (PS/PDI). The effects of film thickness, diameter of the pinhole, machining error and single and multiple aberrations of incident light on the diffraction wavefront errors are analyzed based on the vector diffraction theory. The analysis shows that in order to obtain a reference wavefront with a numerical aperture of 0.2 and a root-mean-square (RMS) wavefront error below 1.4×10-3λ, the best choice for the pinhole is the material chromium with a thickness of 200 nm and diameter of 1.5 μm, and the simulation error requirements should be satisfied in machining. The test window size is optimized based on the spatial frequency domain analysis. The results reveal that the optimal window size is approximately 60 μm. Experiments are carried out for the designed mask to verify the feasibility.