Physical optics approximation for solving problems of light scattering on the ice crystal particles: Comparison of the vector formulations of diffraction
A.V. Konoshonkin1,2, N.V. Kustova2, V.A. Osipov1,2, A.G. Borovoi1,2, K. Masuda3, H. Ishimoto3, H. Okamoto4
1National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050,Russia
2V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
3Meteorological Research Institute, Nagamine 1-1, Tsukuba 305-0052, Japan
4Kyushu University, Kasuga, Fukuoka 816-8580, Japan
Keywords: физическая оптика, алгоритм трассировки пучков, рассеяние света, ледяные кристаллы, FDTD, physical optics approximation, beam-splitting technique, light scattering, ice crystals, FDTD
Abstract
The formulation of the physical optics approximation based on Maxwell's equations has been considered. The equivalence of various definitions of physical optics approximation has been shown. A detailed comparison of the three diffraction formulas corresponding to
E -,
M - and (
E ,
M )-theories of diffraction has been provided. It was found that in the case of diffraction on a hole in the flat screen, all three formulas give the same diffraction scattering cross section for the diffraction angles up to 60°. The polarizing elements of the Mueller matrix in this case diverge significantly even for the angles of 15-30°. It is also shown that in the case of diffraction on the tilted screen, the difference between
E -,
M - and (
E ,
M )-theories of diffraction may be significant. So when the screen is tilted about 80° E , M diffraction theory can be applied only to very small diffraction angle. The comparison of the results with the exact solution obtained by FDTD has confirmed that the difference between
E ,
M - and (
E ,
M ) diffraction theories is not significant for the case of diffraction on the flat screen, but it is preferable to use the (
E ,
M ) diffraction theory for calculations.
|
