相移点衍射干涉仪利用测试波和参考波的横向错位产生载波干涉条纹，因此测量结果中必然引入一定的系统误差。在分析相移点衍射干涉仪主要系统误差源的基础上，提出了一种新的系统误差标定方法，即旋转光栅法。该方法根据光栅在正交方向上的两次测量结果，利用泽尼克多项式在单位圆域的正交特性和奇偶对称性质即可标定干涉仪的系统误差。可见光波段的标定实验结果表明，系统的几何彗差为－0.116 λ，与理论计算结果－0.133 λ基本一致，证明了该方法的有效性。

Because the phase-shifting point diffraction interferometer (PS/PDI) uses lateral shearing of test and reference waves to generate carrier frequency fringe pattern, significant systematic measurement errors are consequentialty introduced. A new calibration method of PS/PDI systematic errors, named rotating grating method, is proposed. Based on the PS/PDI measurement results obtained with two gratings in orthogonal directions, the proposed method utilizes the orthogonal and symmetric property of Zernike polynomials in unit circle to calibrate the systematic errors of PS/PDI. The calibration experiment of visible light PS/PDI is performed to verify the method. The result shows that the geometric coma of the system is －0.116 λ which is consistent with the theoretical value of －0.133 λ, which proves the validity of the method.