Adaptive correction method of inhomogeneous light intensity for digital speckle interferometry by subtraction

In digital speckle interferometry, subtracted fringe patterns are always influenced by inhomogeneous light that is reflected from the tested object and received by the CCD. In this paper, by analyzing speckle's statistic property, we propose a numerical processing method to correct this nonuniform light intensity distribution within adaptive windows. This method includes estimating light intensity distribution of the tested object, constructing an adaptive window for every pixel, and correcting the intensity in the adaptive windows. By applying this method to our experiment, we find it is valid for intensity correction without changing necessary phase information.