Jakobsen Michael L, Hanson Steen G
Department of Photonics Engineering, Danmarks Tekniske Universitet Fotonik, Technical University of Denmark, P.O. Box 49, DK-4000 Roskilde, Denmark.
Appl Opt. 2008 Jul 10;47(20):3674-80. doi: 10.1364/ao.47.003674.
We analyze the dynamics of laser speckle patterns, designed for sensing with a receiver, based on spatial filtering. The speckle translation arises after free-space propagation of light scattered from nonspecular surfaces of a solid object in motion. The speckle pattern is manipulated by modulating the intensity of the coherent light, illuminating the target. The space-time normalized cross covariance of speckle patterns incident on the spatial sensor is calculated for the field distribution of three Gaussian beams having arbitrary directions and separations when incident on the target. The modulation of the intensity distribution at the target introduce a higher spatial frequency component in the speckle pattern. The theoretical analysis provides the statistical parameters for both the speckles and the higher spatial frequency component. The analysis reveals that the speckles and the higher spatial frequency component do not necessarily translate as a rigid structure. The theoretical findings are supported by measurements.
我们基于空间滤波分析了用于接收器传感的激光散斑图案的动力学特性。散斑平移是在从运动固体物体的非镜面表面散射的光在自由空间传播之后出现的。通过调制照射目标的相干光的强度来操纵散斑图案。针对入射到目标上的具有任意方向和间距的三束高斯光束的场分布，计算了入射到空间传感器上的散斑图案的时空归一化互协方差。目标处强度分布的调制在散斑图案中引入了更高的空间频率分量。理论分析给出了散斑和更高空间频率分量的统计参数。分析表明，散斑和更高空间频率分量不一定作为一个刚性结构平移。测量结果支持了理论发现。
