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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1.5μm的针孔,可以达到优于0.1μm的重复对准精度。
The absolute measurement accuracy and repeatability of phase-shift point diffraction interferometers (PS / PDIs) are all directly affected by the tuning error of the interferometer, so high-precision alignment of the interferometer using computer-aided tuning techniques with high sensitivity is necessary of. Based on the analysis of spatial frequency domain of PS / PDI, a set of highly sensitive computer aided tuning method was developed to achieve the alignment of interferometer. In the rough assembly phase, the light field distribution collected by the photoelectric sensor is subjected to discrete Fourier transform, and the information in the spectrogram is used to adjust the PS / PDI. In the phase of precise assembly, the frequency contrast of the interference fringes is used as the evaluation function. The maximum value of the contrast is the target fine-tuning interferometer. The experimental results show that the repeatability of better than 0.1μm can be achieved for the pinhole of 1.5μm diameter in PS / PDI of visible light.