Pointwise implementation of dynamic laser speckle technique

Abstract

The paper proposes pointwise implementation of correlation-based algorithms for processing time sequences of 2D dynamic speckle patterns of a diffuse object illuminated with a laser light in order to obtain a spatial map of physical or biological activity across its surface. Both temporal correlation and structure functions were studied with and without the pointwise normalization by the variance of intensity fluctuations in time. The performance of the algorithms was checked by simulation of dynamic speckle patterns at a given spatial distribution of the temporal correlation radius of activity and by dynamic speckle measurement of a test object. The obtained set of high contrast and high spatial resolution activity maps proves the efficiency of the normalized correlation-based algorithms to indicate regions of varying activity even at non-uniform illumination and reflectivity across the object.