为了实现透明物体的相位测量,提出一种基于液晶空间光调制器(LC—SLM)的同步移相共光路干涉方法。在由4厂光学成像系统构成的三窗口共光路干涉仪基础上,利用LC—SLM的灰度调制能力,在LC—SLM上加载光栅进行频域滤波,进而通过1次曝光获得3幅移相干涉图实现相位测量。给出了本文方法的相位恢复数学模型,并通过光学实验对本文方法和标准四步相移算法的性能进行了比较,最后通过重复实验对方法的稳定性和重复性进行了评估。结果表明,本文方法具有较好的相位恢复效果,而且稳定性和重复性以标准差表示时分别可达0.0325rad和0.0732rad.
A simultaneous phase-shifting common-path interferometry with liquid crystal spatial light modulator (LC-SLM) is proposed for phase measurement of transparent samples. This method is based on the tri-window common-path interferometer which is built on a 4f optical imaging system,and a grating is displayed on the LC-SLM to act as a spectrum filter by the gray modulation of the LC-SLM, thus, the phase of the sample can be obtained from three phase-shifted interferograms which are recorded in one exposure. The mathematical model of the phase retrieval is given; the performances of the proposed method and standard four-step phase-shifting method are compared by optical experiments, and the stability and repeatability of the proposed method are also evaluated by repeated tests. It is proved from the experimental results that the proposed method could achieve good performance in phase retrieval, and the stability and repeatability could achieve 0. 032 5 rad and 0. 073 2 rad in standard deviation,respectively.