超短曝光时间下激光散斑对比度速度分析

Speed Analysis of Laser Speckle Contrast with Ultra-Short Exposure Time

采用0.205ms的曝光时间,研究了观测速度范围包含去相关区域和未去相关区域时的散斑对比度与观测物速度间的关系。结果表明,利用对比度随取样帧数的变化趋势,并结合时间序列散斑图像相关系数曲线,可以在复杂环境下正确区分两个区间内的速度大小;同时,选用适当散斑图像帧数进行对比度计算,可以同时为探测大速度和小速度区间的速度变化提供较高灵敏度。

With the exposure time of 0.205 ms,the relationship between the object observation speed and the speckle contrast when the observable speed range includes a decorrelation area and a non-decorrelation area is investigated.The results indicate that,based on the variance trend of contrast with sampling frame and the correlation coefficient curve of time sequence speckle image,one can distinguish the speed difference between these two areas under complicated environment.Meanwhile,by choosing the suitable number of speckle image frames,one can provide a higher sensitivity for detecting the speed variance in the small speed range and the large speed range.