干涉条纹空间频率对数字叠栅移相干涉测量精度的影响

Influence of Interference Fringe′s Spatial Frequency on the Phase Measurement Accuracy in Digital Moiré Phase-Shifting Interferometry

基于数字叠栅移相干涉原理,分析了CCD像元尺寸、随机噪声和量化误差对采样后干涉条纹和合成叠栅条纹对比度的影响,并就干涉条纹频率对叠栅移相干涉相位测量精度的影响进行了理论分析和仿真研究。结果表明,随着干涉条纹空间频率的增大,CCD的采样过程、随机噪声和量化噪声会影响叠栅条纹信号的对比度和信噪比,并通过相位解算过程直接影响数字叠栅移相干涉的相位测量精度。以相位测量精度为π/50(折合光程差精度为λ/100)作为判断标准,对应可探测干涉条纹的最大空间频率为0.45λ/pixel,为后续数字叠栅移相干涉测量范围的研究提供了定量理论依据。

The influences of CCD pixel size,random noise and quantization series on contrasts of the interferogram after sampling and the moiré fringes are analyzed based on digital moiré phase-shifting interferometry.The effects of interference fringe′s spatial frequency on the phase measurement accuracy are analyzed and simulated in detail.The results indicate that with the increase of interference fringe′s spatial frequency,the contrast and the signal to noise ratio of moiré fringes will be worse with the influences of the process of CCD sampling,random noise and quantization series.Furthermore,the phase errors will be greater after phase-unwrapping.When the interference fringe′s spatial frequency is lower than 0.45 λ/pixel,the phase measurement accuracy can be better than π/50,which is equivalent to the optical path difference better than λ/100.This provides a theoretical quantitative basis for the further study of extending the measurement range of digital moiré phase-shifting interferometry.