TY - JOUR
AB - We study a double-scattering coherent mechanism of negative polarization (NP) near opposition that is observed for powder-like surfaces. The problem is solved numerically for absorbing structures with irregular constituents, cubes, spheres, and ellipsoids larger than the wavelength of incident light. Our simulations show that double scattering between two random irregular particles shows weak NP. Adding one more particle significantly increases the relative contribution of double scattering which enhances NP. Simulations with regular shapes and controlled geometric parameters show that the interference mechanism is sensitive to the geometry of the scattering system and can also result in no polarization or even strong enhancement of positive polarization at backscattering.
AU - Alhaddad, Samer
AU - Grynko, Yevgen
AU - Farheen, Henna
AU - Förstner, Jens
ID - 29075
IS - 1
JF - Optics Letters
KW - tet_topic_scattering
SN - 0146-9592
TI - Numerical analysis of the coherent mechanism producing negative polarization at backscattering from systems of absorbing particles
VL - 47
ER -
TY - JOUR
AB - We model negative polarization, which is observed for planetary regoliths at backscattering, solving a full wave problem of light scattering with a numerically exact Discontinuous Galerkin Time Domain (DGTD) method. Pieces of layers with the bulk packing density of particles close to 0.5 are used. The model particles are highly absorbing and have irregular shapes and sizes larger than the wavelength of light. This represents a realistic analog of low-albedo planetary regoliths. Our simulations confirm coherent backscattering mechanism of the origin of negative polarization. We show that angular profiles of polarization are stabilized if the number of particles in a layer piece becomes larger than ten. This allows application of our approach to the negative polarization modeling for planetary regoliths.
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Alhaddad, Samer
AU - Förstner, Jens
ID - 31574
JF - Icarus
KW - tet_topic_scattering
SN - 0019-1035
TI - Negative polarization of light at backscattering from a numerical analog of planetary regoliths
VL - 384
ER -
TY - JOUR
AB - We numerically simulate multiple light scattering in discrete disordered media represented by large clusters of irregular non-absorbing particles. The packing density of clusters is 0.5. With such conditions diffuse scattering is significantly reduced and light transport follows propagation channels that are determined by the particle size and topology of the medium. This kind of localization produces coherent backscattering intensity surge and enhanced negative polarization branch if compared to lower density samples.
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Förstner, Jens
ID - 17803
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
KW - tet_topic_scattering
SN - 0022-4073
TI - Light backscattering from large clusters of densely packed irregular particles
VL - 255
ER -
TY - JOUR
AB - We consider light scattering from a new type of model particle whose shape is represented in the form of a generalized ellipsoid having N foci, where N is greater than two. Such particles can be convex as well as concave. We use the geometrical optics approximation to study the light scattering from 3-foci particles. Non-zero elements of the scattering matrix are calculated for ensembles of randomly oriented independent transparent particles, m = n + i0. Several internal reflection orders are considered separately. It was found that the transmission-transmission (TT) and transmission-reflectance-transmission (TRT) components dominate in the formation of intensity of scattered light at large and small phase angles, respectively. We found a significant role of the total internal reflections of the TRT in the middle portion of the phase angle range. The main factors in the formation of positive linear polarization are the R and TRT component. The TT component is responsible for the formation of negative polarization branch at large phase angles.
AU - Stankevich, Dmitriy
AU - Hradyska, Larissa
AU - Shkuratov, Yuriy
AU - Grynko, Yevgen
AU - Videen, Gorden
AU - Förstner, Jens
ID - 8872
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
KW - tet_topic_scattering
SN - 0022-4073
TI - Light scattering by 3-Foci convex and concave particles in the geometrical optics approximation
VL - 231
ER -
TY - JOUR
AB - We study the dependence of the intensity and linear polarization of light scattered by isolated particles with the compact
irregular shape on their size using the discontinuous Galerkin time domain numerical method. The size parameter of particles varies in the range of X = 10 to 150, and the complex refractive index is m = 1.5 + 0i. Our results show
that the backscattering negative polarization branch weakens monotonously, but does not disappear at large sizes, up to the geometrical optics regime, and can be simulated without accounting for wave effects. The intensity backscattering surge becomes narrower with increasing particle size. For X = 150, the surge width is several degrees.
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Förstner, Jens
ID - 4324
IS - 15
JF - Optics Letters
KW - tet_topic_scattering
SN - 0146-9592
TI - Intensity surge and negative polarization of light from compact irregular particles
VL - 43
ER -
TY - JOUR
AB - We numerically simulate the circular polarization ratio of the radar signal backscattered from a large-grain cometary coma and compare the simulation results with the radar measurements for seven comets. We apply the discrete dipole approximation method and a model of random irregular particles. Our results confirm water ice composition of the cm-sized chunks detected by the NASA Deep Impact space probe in the vicinity of the nucleus of Comet 103P/Hartley 2. The index of the power-law size distribution in this case can be constrained to the range n ≈ 3.3–4.3. For the other considered comets the circular polarization ratio can be reproduced with variations of the power index between 2 and 5.
AU - Dogra, Shraddha
AU - Grynko, Yevgen
AU - Zubko, Evgenij
AU - Förstner, Jens
ID - 3523
JF - Astronomy & Astrophysics
KW - tet_topic_scattering
SN - 0004-6361
TI - Radar backscattering from a large-grain cometary coma: numerical simulation
VL - 608
ER -
TY - JOUR
AB - The problem of light scattering by ice crystals of cirrus clouds is considered in the case of a hexagonal ice plate with different distributions over crystal orientations. The physical-optics approximation based on (E, M)-diffraction theory is compared with two exact numerical methods: the finite difference time domain (FDTD) and the discontinuous Galerkin time domain (DGTD) in order to estimate its accuracy and limits of applicability. It is shown that the accuracy of the physical-optics approximation is estimated as 95% for the averaged backscattering Mueller matrix for particles with size parameter more than 120. Furthermore, the simple expression that allows one to estimate the minimal number of particle orientations required for appropriate spatial averaging has been derived.
AU - Konoshonkin, Alexander
AU - Borovoi, Anatoli
AU - Kustova, Natalia
AU - Okamoto, Hajime
AU - Ishimoto, Hiroshi
AU - Grynko, Yevgen
AU - Förstner, Jens
ID - 3834
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
KW - tet_topic_scattering
SN - 0022-4073
TI - Light scattering by ice crystals of cirrus clouds: From exact numerical methods to physical-optics approximation
VL - 195
ER -
TY - CONF
AB - In the problem of light scattering by ice crystals of cirrus clouds, two exact methods (FDTD – finite difference time domain and DGTD – discontinuous Galerkin time domain) and the physical-optics approximation are used for numerical calculations of the Mueller matrix in the case of ice hexagonal plates and columns. It is shown that for the crystals larger than 10 μm at the wavelength of 0.532 μm the exact methods and physical-optics approximation closely agreed within three diffraction fringes about the centers of the diffraction patterns. As a result, in the case of random orientation of these crystals, the physical-optics approximation provides accuracy 95% for the averaged Mueller matrix.
AU - Konoshonkin, Alexander V.
AU - Kustova, Natalia V.
AU - Borovoi, Anatoli G.
AU - Okamoto, H.
AU - Sato, K.
AU - Ishimoto, H.
AU - Grynko, Yevgen
AU - Förstner, Jens
ED - Matvienko, Gennadii G.
ED - Romanovskii, Oleg A.
ID - 3840
KW - tet_topic_scattering
T2 - 22nd International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics
TI - Comparison between the physical-optics approximation and exact methods solving the problem of light scattering by ice crystals of cirrus clouds
ER -
TY - JOUR
AB - We simulate light scattering by random irregular particles that have dimensions much larger than the wavelength of incident light at the size parameter of 𝑋=200 using the discontinuous Galerkin time domain method. A comparison of the DGTD solution for smoothly faceted particles with that obtained with a geometric optics model shows good agreement for the scattering angle curves of intensity and polarization. If a wavelength-scale surface roughness is introduced, diffuse scattering at rough interface results in smooth and featureless curves for all scattering matrix elements which is consistent with the laboratory measurements of real samples.
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Förstner, Jens
ID - 3843
IS - 15
JF - Optics Letters
KW - tet_topic_scattering
SN - 0146-9592
TI - Light scattering by irregular particles much larger than the wavelength with wavelength-scale surface roughness
VL - 41
ER -
TY - JOUR
AB - The physical optics approximations are derived from the Maxwell equations. The scattered field equations by Kirchhoff, Stratton-Chu, Kottler and Franz are compared and discussed. It is shown that in the case of faceted particles, these equations reduce to a sum of the diffraction integrals, where every diffraction integral is associated with one plane–parallel optical beam leaving a particle facet. In the far zone, these diffraction integrals correspond to the Fraunhofer diffraction patterns. The paper discusses the E-, M- and (E, M)-diffraction theories as applied to ice crystals of cirrus clouds. The comparison to the exact solution obtained by the discontinuous Galerkin time domain method shows that the Kirchhoff diffraction theory is preferable.
AU - Konoshonkin, Alexander V.
AU - Kustova, Natalia V.
AU - Borovoi, Anatoli G.
AU - Grynko, Yevgen
AU - Förstner, Jens
ID - 3849
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
KW - tet_topic_scattering
SN - 0022-4073
TI - Light scattering by ice crystals of cirrus clouds: comparison of the physical optics methods
VL - 182
ER -
TY - JOUR
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Förstner, Jens
ID - 1783
IS - 23
JF - Optical Letters
KW - tet_topic_scattering
TI - Light scattering by randomly irregular dielectric particles larger than the wavelength
VL - 38
ER -