相移点衍射干涉仪(PS/PDI)的绝对测量精度和重复精度都直接受干涉仪装调误差的影响,因此采用具有高灵敏度的计算机辅助装调技术进行干涉仪的高精度对准是必要的。在PS/PDI空间频域特性分析的基础上,开发了一套高灵敏度的计算机辅助装调方法来实现干涉仪的对准。在粗装调阶段,对光电传感器采集的光场分布进行离散傅里叶变换,利用频谱图中的信息调整PS/PDI;在精密装调阶段,采用干涉条纹的频域对比度作为评价函数,以得到对比度的最大值为目标微调干涉仪。装调实验结果表明,对于可见光波段PS/PDI中直径为1.5 μm的针孔,可以达到优于0.1 μm的重复对准精度。

Both the absolute accuracy and repeatability of phase-shifting point diffraction interferometer (PS/PDI) are influenced by the alignment errors of interferometer,so a highly sensitive computer aided alignment method is necessary. A highly sensitive computer aided alignment method based on the spatial frequency domain characteristic of PS/PDI is developed. In the coarse alignment stage,the information provided by the discrete Fourier transform of the light field distribution on CCD is used to align the PS/PDI. In the fine alignment stage,the frequency domain contrast of fringes on CCD is used as the merit function to align the PS/PDI. Alignment experimental results show that the alignment repeatability of 0.1 μm can be achieved for an 1.5 μm diameter pinhole used in visible light PS/PDI.