针孔作为点衍射干涉仪中的关键元件，针孔的制作精度将会严重影响干涉仪的检测精度。对于大多数衍射问题，标量衍射理论是一种比较好的近似，但是当衍射孔径较小时，矢量衍射理论更能说明衍射波面的实际情况。针对可见光入射针孔时，分别从标量和矢量衍射理论出发，分析针孔尺寸对衍射波质量的影响，并计算衍射波面的峰谷(PV)值和均方根(RMS)值。结果表明，标量衍射理论下，当孔径为 400 nm时，衍射波面误差 RMS最小，且随着材料厚度的变化误差变化不大。矢量衍射理论下，孔径为 200 nm时，衍射波面误差 RMS最小，且材料厚度的不同，衍射误差变化较大。

Pinhole is a key component in phase-shifting point diffraction interferometer (PS-PDI), therefore the production precision of pinhole will seriously affect the detection accuracy of interferometer. For most of the diffraction problems, the theory of scalar diffraction is a good approximation. However, the theory of vector diffraction is more suitable to explain the actual situation of diffraction wave surface when the diffraction aperture is very small. On the basis of the scalar and vector diffraction theory, effects on the quality of diffraction wave-front produced by the size of pinhole are analyzed, in the meantime, the peak and valley (PV) value and root mean square (RMS) value of diffraction wave front errors are calculated while visible lights entranced the pinhole. The results show that with the scalar diffraction theory, when aperture is 400 nm, RMS of diffraction wave front error is the minimum and changes little with the material thickness. As well, with the vector diffraction theory, when aperture is 200 nm, RMS of diffraction wave front error is the minimum, but it changes greatly with the material thickness.