Noise in laser speckle correlation and imaging techniques

Abstract

We study the noise of the intensity variance and of the intensity correlation\nand structure functions measured in light scattering from a random medium in\nthe case when these quantities are obtained by averaging over a finite number N\nof pixels of a digital camera. We show that the noise scales as 1/N in all\ncases and that it is sensitive to correlations of signals corresponding to\nadjacent pixels as well as to the effective time averaging (due to the finite\nsampling time) and spatial averaging (due to the finite pixel size). Our\nresults provide a guide to estimation of noise level in such applications as\nthe multi-speckle dynamic light scattering, time-resolved correlation\nspectroscopy, speckle visibility spectroscopy, laser speckle imaging etc.\n