提出一种基于液晶偏振分光的共光路干涉测量方法来测量液晶空间光调制器(LCSLM)的相位调制特性。线偏振入射光束被LCSLM 分为两束正交线偏振光，然后沿相同方向传播至渥拉斯顿棱镜(WP)；经WP 出射的两光束产生横向剪切，同时，WP 也将会在两光束之间引入倾斜调制，从而当它们再经过检偏器后产生载频干涉条纹。用傅里叶变换法计算两帧干涉条纹之间的相对相移量。给出了透射式LCSLM 相位调制特性的实验测量结果。该方法对振动、空气扰动不敏感，能够测量得到LCSLM 的整体相位调制特性，结果更加精确、科学。

A common-path interferometry is proposed to measure the phase of liquid crystal spatial light modulator (LCSLM), which is based on the pricinple of liquid-crystal polarization splitted light. The linearly polarized input beam is divided into two orthogonal polarized beams by LCSLM, and then propagates to the Wollaston prism (WP) along the same direction. Two beams transmitted from the WP generate lateral shearing and a tilt modulation is introduced into the two beams, and hence a carrier-frequency interferogram is obtained after passing analyzer polarizer. The relative phase-shift between two frames of fringes is calculated accurately by using the Fourier-transform algorithm. A phase modulation experiment to the transmissive LCSLM is given. The proposed method is less sensitive to vibrations and air turbulence. Furthurmore, it can measure the whole phase modulation characteristics of LCSLM, and the measuring result is more precise and scientific.