Scattering of electromagnetic waves from random rough metallic surfaces with one-dimensional structure calculated by the surface impedance boundary condition method (SIBC) (original) (raw)
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A comparison between exact solutions and surface impedance boundary condition method, for the phenomenon of light scattering from one-dimensional random rough metallic surfaces in both cases of polarization (s-and p-) is presented. The reflective properties of random rough metallic surfaces at a large angle of incidence have been reported on due to their potential applications in some of the radiative heat transfer research areas. The influence of surface roughness, shadowing effects, the nature of polarization, and the nature of the material on the behavior of reflectivity and emissivity has been quantified.
Physics Procedia, 2009
We are interested in studying the contributions of the physical parameters of materials to the emissivity of random rough surfaces for both transverse electric and transverse magnetic waves. Comparisons between the surface impedance boundary condition (SIBC) and the exact results are presented. The effects of the incident angle, the material surfaces and random roughness on the directional emissivity are quantified. The contributions of the effects to the emissivity are used to investigate the domains of validity of the approximate model.
Scattering by random rough surfaces: Study of direct and inverse problem
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In order to study the problems of scattering by rough metallic surfaces, we have used Maxwell's equations in covariant form within the framework of a non-orthogonal coordinates system adapted to the geometry of the problem. Electromagnetic fields are written in Fourier's integral form. The solution is found by using a perturbation method applied to the smooth surface problem; this is fully justified when the defects are of small magnitude. For the direct problem, the mean value of diffraction intensity is obtained for random rough surfaces of finite conductivity by computer simulation. In the case of the inverse problem, the reconstruction of the profile of the metal surface from values of the diffraction intensity, obtained by simulation, is found using an iterative algorithm.
The scattering of electromagnetic waves from a randomly rough 2D metallic surface
Optics Communications, 1994
By a computer simulation approach we study the scattering of a finite beam of p-polarized light from very rough two-dimensional metallic surfaces. Enhanced backscattering is observed. It is found that the approximation of a metal surface by a perfectly conducting surface in the visible region of the optical spectrum is less good for in-plane, co-polarized and out-of-plane, crossedpolarized scattering than it is for in-plane, crossed-polarized and out-of-plane, co-polarized scattering.
Resonance effects in multiple light scattering from statistically rough metallic surfaces
Physical Review B, 1992
Multiple scattering of light from one-dimensional random rough metallic surfaces is numerically studied by means of a Monte Carlo simulation method based on the extinction-theorem boundary conditions. Angular and integrated distributions of the mean scattered intensity are computed for several values of the angle of incidence, state of polarization, surface statistical parameters, and dielectric permittivity. Two main regimes are addressed, depending on whether the surface correlation length T is larger or smaller than the wavelength A, . In the first case, we observe enhanced backscattering both for s and p waves, whereas in the latter situation there exist substantial absorption effects under p polarization, linked to the excitation of surface polaritons. In addition, calculations are made of field enhancements on the surface, owing either to surface-polariton excitation in the small-correlation-length case (T & A, ), or to multiple scattering and generation of other kinds of surface wave in the large-correlation-length case (T & A, ).
Directional hemispherical radiative properties of random dielectric rough surfaces
In this paper the directional hemispherical reflectivity and transmissivity of one-dimensional, randomly rough, dielectric surfaces are determined by the use of the integral method. This method is derived from electromagnetic theory without any restrictive hypotheses. Since this exact approach is computationally very intensive, a geometric optics approximation method is also developed. Curves displaying radiative properties versus the correlation length for a constant mean square deviation of the surface from flatness are presented. In this respect, the influence on the validity of the approximate method of multiple scattering, the shadowing effect and the real index of refraction of the dielectric have been investigated.Transverse electric and transverse magnetic polarized incident plane waves are considered. For the latter, our interest is focused on the influence of roughness on the reflected and transmitted intensities for an angle of incidence close to the Brewster angle.
Light scattering from random rough dielectric surfaces
Journal of the Optical Society of America A, 1991
A theoretical and numerical study is made of the scattering of light and other electromagnetic waves from rough surfaces separating vacuum from a dielectric. The extinction theorem, both above and below the surface, is used to obtain the boundary values of the field and its normal derivative. Then we calculate the angular distribution of the ensemble average of intensity of the reflected and transmitted fields. The scattering equations are solved numerically by generating one-dimensional surface profiles through a Monte Carlo method. The effect of roughness a-and correlation distance T on the aforementioned angular distribution, as well as on the reflectance, is analyzed. Enhanced backscattering and new transmission effects are observed, also depending on the permittivity. The ratio o/T is large in all cases studied, and thus no analytical approximation, such as the Kirchhoff approximation (KA) and small perturbation methods, could a priori be expected to hold. We find, however, that the range of validity of the KA can be much broader than that previously found in perfect conductors.
Journal of The Optical Society of America A-optics Image Science and Vision, 1994
Electromagnetic scattering of an incident plane wave from a rectangular strip and strip grating, are presented semi-analytically. The strip and strip grating are simulated by joining parallel perfect electromagnetic conductor (PEMC) circular cylinders and are illuminated by a TM z incident plane wave. The PEMC medium does not allow electromagnetic energy to enter. An interface of this medium serves as an ideal boundary to the electromagnetic field. The solution is based on the application of the boundary conditions on the surface of each cylinder in terms of its local coordinate system. The technique is used to predict the scattered field pattern of PEMC strip and PEMC strip grating.
2002
This paper presents an evaluation of three perturbation theories and the Kirchhoff approximation for calculating the reflectance Í‘the intensity of the coherent componentÍ’ of two-dimensional metallic surfaces with a random roughness distribution. The theoretical results are compared with experimental data obtained on typical samples. The samples were fabricated from photoresist, and their metallized surface profiles are a good match with a Gaussian correlation function and a Gaussian random process. The correlation distances of these surfaces range from approximately one-fifth to two wavelengths of the IR range used in the experiment.
Physical Review B, 2001
The small perturbations method has been extensively used for waves scattering by rough surfaces. The standard method developped by Rice is difficult to apply when we consider second and third order of scattered fields as a function of the surface height. Calculations can be greatly simplified with the use of reduced Rayleigh equations, because one of the unknown fields can be eliminated. We derive a new set of four reduced equations for the scattering amplitudes, which are applied to the cases of a rough conducting surface, and to a slab where one of the boundary is a rough surface. As in the one-dimensional case, numerical simulations show the appearance of enhanced backscattering for these structures.