Speckle pattern analysis using differential dynamic matrix

Dynamic laser speckle analysis (LSA) is a sensitive, noninvasive, and remote technique that has been applied to study different phases of matter in various phenomena in life science and industry. On the other hand, differential dynamic microscopy (DDM) is an efficient method for the collective and quantitative analysis of microscopic particle suspensions. DDM uses successive recorded microscopy images to extract information about the diffusion and scattering functions. However, in several applications, the microscopy images include additional noises caused by turbulent dynamics of the sample, contaminations, or aberrations in the imaging system. Here, we extend DDM to LSA, which is like considering the extreme case of noisy images for DDM analysis. We show that DDM can provide additional analysis parameters for LSA, and, more importantly, the speckle patterns can be directly analyzed using DDM. To validate the proposed DDM-LSA technique, we apply it to the analysis of drying paint.