On applicability of the far-field approximation to the analysis of light scattering by particulate media

Abstract Problems of the theory of light scattering by densely packed discrete random media are analyzed with the model, considering such medium as a semi-infinite layer composed of randomly oriented clusters. Each of the clusters is assumed to be in the far zones of all other clusters. Under this approach, the numerical solution of the radiative transfer equation and the equation for weak localization of waves yields the characteristics of radiation reflected by the medium. Since in these equations an elementary volume of the medium is assumed to be represented by randomly oriented clusters, the near-field effects, as well as the irregular shape and heterogeneity of the scatterers, are partially taken into account. The model results are compared to the currently available laboratory measurements of the intensity and the degree of linear polarization of nonabsorbing samples (MgO, Al 2 O 3 , and SiO 2 ) composed the scatterers smaller than the wavelength in size. The scattering characteristics of the samples with different (though not very high) packing densities are considered. In the frames of the applied model, some of the calculated phase profiles of polarization well agree with the measured ones. This allowed us to estimate the relative concentration of scatterers in the media and their sizes. At the same time, the measured phase dependences of intensity are poorly fitted with the models. This suggests that some scattering mechanisms remained beyond the frames the considered model; these mechanisms noticeably influence the intensity of radiation reflected by the medium, while their effect on the linear polarization is negligible.

[1]  V. K. Varadan,et al.  Coherent electromagnetic wave propagation through randomly distributed dielectric scatterers , 1979 .

[2]  E. V. Petrova,et al.  Modeling of opposition effects with ensembles of clusters: Interplay of various scattering mechanisms , 2007 .

[3]  M. Mishchenko,et al.  Light scattering in a finite multi-particle system , 2008 .

[4]  M. Mishchenko,et al.  A multiple sphere T-matrix Fortran code for use on parallel computer clusters , 2011 .

[5]  K. Muinonen.  Coherent backscattering of light by complex random media of spherical scatterers: numerical solution , 2004 .

[6]  M. Mishchenko,et al.  Weak localization of electromagnetic waves and opposition phenomena exhibited by high-albedo atmosphereless solar system objects. , 2006, Applied optics.

[7]  Wolf,et al.  Weak localization and coherent backscattering of photons in disordered media. , 1985, Physical review letters.

[8]  M. Mishchenko,et al.  Approximate calculation of coherent backscattering for semi-infinite discrete random media , 2009 .

[9]  Yasuo Kuga,et al.  Attenuation constant of a coherent field in a dense distribution of particles , 1982 .

[10]  Andrew A. Lacis,et al.  Scattering, Absorption, and Emission of Light by Small Particles , 2002 .

[11]  D. Mackowski.  Electrostatics analysis of radiative absorption by sphere clusters in the Rayleigh limit: application to soot particles. , 1995, Applied optics.

[12]  L. Kolokolova,et al.  IMPACT OF COHERENT BACKSCATTERING ON THE SPECTRA OF ICY SATELLITES OF SATURN AND THE IMPLICATIONS OF ITS EFFECTS FOR REMOTE SENSING , 2010 .

[13]  G. Maret,et al.  Optical coherent backscattering by random media : an experimental study , 1988 .

[14]  J. Blum,et al.  Optical properties of dust aggregates : I. Wavelength dependence , 1992 .

[15]  K. Jockers,et al.  Optical properties of aggregate particles comparable in size to the wavelength , 2004 .

[16]  S. Kaasalainen,et al.  Comparative study on opposition effect of icy solar system objects , 2001 .

[17]  V. Tishkovets,et al.  Light scattering by closely packed clusters: Shielding of particles by each other in the near field , 2008 .

[18]  J. Peltoniemi,et al.  A Critical review of theoretical models of negatively polarized light scattered by atmosphereless solar system bodies , 1994 .

[19]  Y. Shkuratov,et al.  Experimental Modeling of Opposition Effect and Negative Polarization of Regolith-Like Surfaces , 2002 .

[20]  Pavel Litvinov,et al.  Models for surface reflection of radiance and polarized radiance: Comparison with airborne multi-angle photopolarimetric measurements and implications for modeling top-of-atmosphere measurements , 2011 .

[21]  Nadezhda T. Zakharova,et al.  Polarized bidirectional reflectance of optically thick sparse particulate layers: An efficient numerically exact radiative-transfer solution , 2015 .

[22]  Brian Cairns,et al.  Electromagnetic scattering by a morphologically complex object: Fundamental concepts and common misconceptions , 2011 .

[23]  J. Piironen,et al.  The Opposition Effect and Negative Polarization of Structural Analogs for Planetary Regoliths , 2002 .

[24]  Y. Shkuratov,et al.  Light backscatter by surfaces composed of small spherical particles. , 2006, Applied optics.

[25]  Michael I. Mishchenko,et al.  Scattering of electromagnetic waves by ensembles of particles and discrete random media , 2011 .

[26]  V. Tishkovets,et al.  Light scattering by densely packed systems of particles: near-field effects , 2013 .

[27]  J. Hovenier,et al.  Laboratory studies of scattering matrices for randomly oriented particles , 2003 .

[28]  J. Kong,et al.  Scattering of Electromagnetic Waves: Advanced Topics , 2001 .

[29]  Michael I. Mishchenko,et al.  Numerically exact computer simulations of light scattering by densely packed, random particulate media , 2011 .

[30]  T. Hiroi,et al.  Comparative studies of the reflectance and degree of linear polarization of particulate surfaces and independently scattering particles , 2006 .

[31]  Alfons G. Hoekstra,et al.  The discrete-dipole-approximation code ADDA: Capabilities and known limitations , 2011 .

[32]  V. Tishkovets,et al.  Coherent backscattering by discrete random media composed of clusters of spherical particles , 2013 .

[33]  A. Lacis,et al.  Multiple Scattering of Light by Particles: Radiative Transfer and Coherent Backscattering , 2006 .

[34]  E. Zubko,et al.  Numerical Techniques for Backscattering by Random Media , 2002 .

[35]  Karri Muinonen,et al.  Light-scattering evolution from particles to regolith , 2015 .

[36]  N. M. Shakhovskoy,et al.  Polarimetric remote sensing of Solar System objects , 2010, 1010.1171.