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Scattering of Gaussian Beams by Disordered Particulate MediaA 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.
Document ID
20170006100
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Mishchenko, Michael I.
(NASA Goddard Inst. for Space Studies New York, NY United States)
Dlugach, Janna M.
(National Academy of Sciences of the Ukraine Kiev, Ukraine)
Date Acquired
July 6, 2017
Publication Date
April 27, 2016
Publication Information
Publication: Journal of Quantitative Spectroscopy and Radiative Transfer
Publisher: Elsevier
Volume: 183
ISSN: 0022-4073
Subject Category
Optics
Report/Patent Number
GSFC-E-DAA-TN33700
Distribution Limits
Public
Copyright
Other
Keywords
radiative transfer theory
spectra
diffuse scattering patterns
order-disorder transformations
speckles
electromagnetic scattering

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