基于LC-SLM的空间载波相移剪切散斑干涉

Spatial Carrier Phase-Shift Shearography Based on LC-SLM

针对传统空间载波相移剪切散斑干涉系统中剪切量难以快速、定量、精确调节的问题,提出了一种利用液晶空间光调制器(LC-SLM)调制剪切量的空间载波相移剪切散斑干涉测量系统。采用LC-SLM作为剪切量调制器件,通过电寻址的方式对LC-SLM工作区域内每个微小液晶单元的相位精确控制,通过透镜的傅里叶变换,将频域内的相移调制转化为空间域的位移调制,从而达到精确调整剪切量的目的。组建实验系统,对本文方法进行了实验验证,实验结果表明,该系统可以对物体变形引起的干涉相位变化进行全场测量,通过在LC-SLM中写入周期条纹图像,可以调节剪切量,同时也可以对空间载波频率进行调整。该系统与传统空间载波剪切散斑干涉系统相比,具有定量、精确、快速调节剪切量的优势。

To solve the problem that the shearing amount in traditional spatial carrier phase-shift shearography systems is hard to be rapidly,quantitatively,and precisely modulated,this paper proposes a spatial carrier phase-shift shearography system based on a liquid crystal spatial light modulator(LC-SLM).With LC-SLM as a shearing amount modulator,the phase of each tiny liquid crystal unit in the working area of LC-SLM is precisely controlled by electrical addressing,and the phase-shift modulation in the frequency domain is converted into displacement modulation in the spatial domain through the Fourier transform of lens.As a result,the shearing amount can be modulated accurately.An experimental setup is developed to verify the proposed method.The experimental results show that this system can carry out the full-field measurement of interference phase changes caused by object deformation.By writing the periodic fringe images in LC-SLM,this system can modulate the shearing amount and the spatial carrier frequency.Compared with the traditional spatial carrier phase-shift shearography system,the proposed system can quantitatively,accurately,and rapidly modulate the shearing amount.