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Scattering of Gaussian beams by disordered particulate media

Mishchenko, M., and J. M. Dlugach (2016), Scattering of Gaussian beams by disordered particulate media, J. Quant. Spectrosc. Radiat. Transfer, 183, 85-89, doi:10.1016/j.jqsrt.2016.04.016.

A frequently observed characteristic of electromagnetic scattering by a disordered particulate medium is the absence of pronounced speckles in angular patterns of the scattered light. It is known that such diffuse speckle-free scattering patterns can be caused by averaging over randomly changing particle positions and/or over a finite spectral range. To get further insight into the possible physical causes of the absence of speckles, we use the numerically exact superposition T-matrix solver of the Maxwell equations and analyze the scattering of plane-wave and Gaussian beams by representative multi-sphere groups. We show that phase and amplitude variations across an incident Gaussian beam do not serve to extinguish the pronounced speckle pattern typical of plane-wave illumination of a fixed multi-particle group. Averaging over random particle positions and/or over a finite spectral range is still required to generate the classical diffuse speckle-free regime.

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Radiation Science Program (RSP)