采用DLP的PMP系统中的莫尔效应及其对位相测量的影响

Moiré Effect in PMP Using DLP and Its Influence on Phase Measurement

在采用数字光处理器(DLP)作为光栅投影系统的位相测量轮廓术(PMP)中,研究了莫尔效应产生的原理及其对位相测量结果的影响.DLP投射的光栅信号可视为对正弦模拟信号的抽样,CCD采集到的光栅信号又是对DLP投影信号的抽样,当DLP的核心部件DMD芯片和CCD图象传感器的空间频率满足一定条件时,CCD采集的图样将因为两次抽样过程产生莫尔条纹.通过对这两次抽样过程的分析,得到了莫尔条纹产生的条件和光强表达式,找出了N位相算法中莫尔条纹引起的位相误差规律.给出了数字模拟实验结果.

Moiré effect in PMP using DLP and its influence on phase measurement was studied. The projected grating by DLP can be regarded as the process of sampling the analog grating and the acquired grating by CCD can also be regarded as the process of sampling the projected grating. When some conditions of the spatial frequencies between DLP pixel and CCD pixel are satisfied, the moiré effect will be appeared. Moiré fringe pattern will influence phase measuring precision. The condition appeared Moiré effect was discussed and the rule of the influence to the phase measuring precision was given by analyzing the two steps sampling process. The correctness of the discussions was verified by the simulation experiment.