Issue 11, June 2004
There are several different approaches used to calculate scattering from dielectric targets, including the discrete dipole approximation (DDA), the plane-wave-time-domain method (PWTD), the extended boundary condition method (EBCM), the generalized multipole technique (GMT), the finite difference time domain (FDTD), the transmission line method (TLM) etc. There appear to be few discussions in the literature that compare the computational efficiency (cpu-time and memory requirements), stability and accuracy of these methods on any standard problems.
We would like to invite all interested researchers for comparison of scattering calculations on a number of interesting test problems. This comparison is intended to give hints on
At the website http://www.t-matrix.de/ we have defined some test problems which we think may be of interest to the community. We also include the results on comparison as they are computed by us or provided by other researchers.
If you are interested to contribute to this comparison please send your
computation results by email to Bruce
or Thomas with a full definition of
the scattering problem such that other researchers can compute the same problem
for comparison.
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Preprint of
the paper
Karri Muinonen
“Coherent backscattering of light by
complex random media of spherical particles: numerical solution.”
(to be
published in Waves in Random Media,
14(3), 365-388, 2004)
is available online at http://www.astro.helsinki.fi/~psr/MultipleScatter/index.html
Abstract.
Novel Monte Carlo techniques are described for the computation of reflection coefficient matrices for multiple scattering of light in plane-parallel random media of spherical scatterers. The present multiple scattering theory is composed of coherent backscattering and radiative transfer. In the radiative transfer part, the Stokes parameters of light escaping from the medium are updated at each scattering process in predefined angles of emergence. The scattering directions at each process are randomized using probability densities for the polar and azimuthal scattering angles: the former angle is generated using the single-scattering phase function, whereafter the latter follows from Kepler's equation. For spherical scatterers in the Rayleigh regime, randomization proceeds semi-analytically whereas, beyond that regime, cubic spline presentation of the scattering matrix is used for numerical computations. In the coherent backscattering part, the reciprocity of electromagnetic waves in the backscattering direction allows the renormalization of the reversely propagating waves, whereafter the scattering characteristics are computed in other directions. High orders of scattering (~10 000) can be treated because of the peculiar polarization characteristics of the reverse wave: after a number of scatterings, the polarization state of the reverse wave becomes independent of that of the incident wave, that is, it becomes fully dictated by the scatterings at the end of the reverse path. The coherent backscattering part depends on the single-scattering albedo in a non-monotonous way, the most pronounced signatures showing up for absorbing scatterers. The numerical results compare favourably to the literature results for nonabsorbing spherical scatterers both in and beyond the Rayleigh regime.
The book
M. I. Mishchenko,
L. D. Travis, and A. A. Lacis
"Scattering, Absorption, and
Emission of Light by Small Particles"
is now
publicly avaliable in the .pdf format at
http://www.giss.nasa.gov/~crmim/books.html
This book was originally published by Cambridge
University Press in June of 2002. The entire print run was sold out in less
than 16 months, and the book has been officially out of print since October of
2003. By agreement with Cambridge University Press, this electronic edition is
intended to make the book continually available. No significant revision of the
text has been attempted; the pagination and the numbering of equations follow
those of the original hardcopy edition. However, almost all illustrations have
been improved, several typos have been corrected, some minor improvements of
the text have been made, and a few recent references have been added.