激光散斑法测量横向微位移及其应用

Measurement of lateral micro-displacement with laser speckle and its application

针对传统激光散斑法测量横向微位移中存在的条纹对比度低、噪声大的不足,提出了改进的方法.该方法将二次曝光的散斑强度分布图利用快速傅里叶变换算法做2次快速傅里叶变换,在最终所得光场中通过测量相邻两自相关强度峰值点的间距,即可计算出被测物体的横向微位移量.将该方法应用于金属线膨胀系数测量实验,验证了该方法的可行性.

An improved method for measuring lateral micro-displacement based on laser speckle was proposed.The method overcame the shortcomings of previous laser speckle method such as low fringe contrast and high noise.Twice Fourier transform of the double-exposure speckle intensity distribution was carried out with fast Fourier transform algorithm.The lateral micro-displacement of the measured object could be calculated by measuring the spacing between two adjacent peaks of the autocorrelation intensity in the final light field.This method was applied to measure the linear expansion coefficient of metal.The experiment results demonstrated the feasibility of the method.