旋转圆柱目标的动态散斑统计特性

摘要

Dynamic speckles appear when a cylinder rotating with a constant angular velocity is irradiated by a Gaussian light beam.The statistical property of dynamic speckles in far-field diffraction is acquired when the irradiated area is larger than the cylinder surface.The normalized space-time cross-correlation of dynamic speckle intensity fluctuations is obtained with different cylinder radii in different incidence conditions.The results show that the correlation is improved when the cylinder radius and rotating speed decrease.When the cylinder rotates at a constant speed,the peak value of cross-correlation function descends gradually as the distance between the two observation points increases,whereas the peak position increases,In the case of approximate point irradiation,the spatial correlation length is almost unchanged and the correlation time extends obviously as the cylinder radius increases.%高斯光束照射以固定角速度旋转的粗糙圆柱体表面,反射空间形成随着被测表面运动变化的动态散斑.研究了照射面积大于圆柱曲面条件下在远场衍射区形成的动态散斑统计特性,得到了不同入射条件及不同圆柱时动态散斑强度起伏空间-时间归一化相关函数.结果表明:随着圆柱半径、旋转速度以及照射光斑有效面积的增大,动态散斑强度起伏相关性快速减小；当圆柱旋转速度恒定,动态散斑光强起伏相关函数的峰值随着探测点之间距离的增大而减小,但峰值的位置随之而增大；在近似点照射情况下随着圆柱半径的增大空间相关长度基本不变,而相关时间性明显增大.