Two-dimensional problem of diffraction by dielectric cylinder of arbitrary cross-section in plane-layered medium. TheE-polarization case

An algorithm is developed for numerical solution of the two-dimensional problem of scattering of an E-polarized field by a dielectric cylinder in a plane-layered medium. Plane-wave scattering by a cylinder imbedded in a homogeneous dielectric layer with rectangular and rhombic cross-sections is studied.     

Wave diffraction by a concave statistically rough surface

Abstract

We consider a statistically rough impedance surface that is concave on average in contrast to a plane. Backscattering from such a surface is considered based on the small perturbation theory method. The diffraction problem is divided into two parts which are considered separately: the problem of scattering by small roughness (assumed to be local) and the propagation of incident and scattered fields over a smooth large-scale concave surface. In contrast to the ‘two-scale’ scattering model, the zero-order unperturbed wavefield is not assumed to be specularly reflected from the local tangent plane to the smooth surface, but it is a solution of a corresponding diffraction problem. Two particular cases of smooth surfaces are considered: first, the inner surface of a concave cylinder with a constant radius and finite angular pattern, and second, a compound surface that consists of a coupled half-plane and the cylindrical surface mentioned above. In a geometrical optics limit and with propagation at low grazing angles, the analytical results for a zero-order (unperturbed) field are obtained for these two cases in the form of a series over multiple specular reflected fields. It is shown that these non-local processes lead to the essential increase in the backscattering cross section in comparison with the two-scale model and tangent-plane approach.     

Wave diffraction by a concave statistically rough surface

We consider a statistically rough impedance surface that is concave on average in contrast to a plane. Backscattering from such a surface is considered based on the small perturbation theory method. The diffraction problem is divided into two parts which are considered separately: the problem of scattering by small roughness (assumed to be local) and the propagation of incident and scattered fields over a smooth large-scale concave surface. In contrast to the 'two-scale' scattering model, the zero-order unperturbed wavefield is not assumed to be specularly reflected from the local tangent plane to the smooth surface, but it is a solution of a corresponding diffraction problem. Two particular cases of smooth surfaces are considered: first, the inner surface of a concave cylinder with a constant radius and finite angular pattern, and second, a compound surface that consists of a coupled half-plane and the cylindrical surface mentioned above. In a geometrical optics limit and with propagation at low grazing angles, the analytical results for a zero-order (unperturbed) field are obtained for these two cases in the form of a series over multiple specular reflected fields. It is shown that these non-local processes lead to the essential increase in the backscattering cross section in comparison with the two-scale model and tangent-plane approach.     

Focusing of waves in an anisotropic plane-layered medium

The problem of propagation of electromagnetic waves in an inhomogeneous uniaxial anisotropic medium is discussed. Analytic solutions of Maxwell's equations are found for two particular cases of a plane-layered dielectric. The effect of different parameters of an inhomogeneous distribution of refractive indices on the propagation characteristics of wave beams is analyzed. The corrections of the first approximation of perturbation theory to the propagation constants of natural waves are obtained for a plane-layered focusing medium of general type. This has permitted solving the problem of a distribution of the refractive index which provides for optimal focusing.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 12, pp. 1812–1821, December, 1978.In conclusion, the author expresses his gratitude to I. V. Ivanov and N. A. Morozov for their attention to this paper.     

Nonstationary heating of a plane-layered medium by pulsed electromagnetic radiation

Nonstationary heat exchange in a nontransparent plane-layered medium irradiated with a directional beam of pulsed radiation is investigated theoretically. The radiation is absorbed on the irradiated surface, which becomes a distributed source of heat. The propagation of the heat into the layers is described by the heat-conduction equation with nonlinear boundary conditions, which take into account convection and heat exchange with the radiation. Dimensionless parameters, on which the solution depends, are obtained, and their effect on the change of the surface temperatures of the layers with time for one- and two-layered media and also on the heat pulse transmitted through the medium is analyzed.M. V. Lomonosov Moscow State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 115–121, November, 1992.     

Buried interfaces studied by photoelectron diffraction

Angle- and energy-scanned photoelectron diffraction data can be used to investigate structures below surfaces. The modulations in photoelectron intensity result from diffraction of the emitted electron wave at neighbor atoms. In the past, scanned-energy photoelectron diffraction had been mainly used to determine the adsorption site of molecules at surfaces. Recent data show, however, that the technique can also be employed to obtain information about the upper substrate layer(s). At low kinetic energies, backward scattering is strong and in scanned-angle photoelectron diffraction the recorded patterns result from backward- and multiple-scattering effects. For a structural analysis, the intensity modulations have to be compared with the results for simulations performed for model clusters. As an example, recent angle-scanned photoelectron diffraction patterns recorded for the technologically important silicon oxide/silicon interface were compared with simulations. At the Si(001) surface orientation, the interface is extended over a few layers, whereas at the Si(111) surface orientation the transition is rather abrupt and occurs within one or two layers. Received: 9 September 2002 / Accepted: 2 October 2002 / Published online: 5 February 2003 RID="*" ID="*"Corresponding author. Fax: +49-231/755-3657, E-mail: carsten.westphal@physik.uni-dortmund.de     

Grazing-incidence X-ray diffraction from multilayers, taking into account diffuse scattering from rough interfaces

Received: 21 May 1997: Accepted 30 July 1997     

Wave diffraction on an infinite chaotic screen bounding a medium with spatial and time dispersion

Electromagnetic wave diffraction on a chaotic screen, bounding a medium with time and spatial dispersion, has been investigated. The longitudinal and cross-correlation functions of waves in the limit cases of the correlation radius being longer or shorter than the wavelength have been evaluated. This letter considers the radiation of a plane antenna with dimensions much larger than the wavelength and with arbitrary current distribution on the surface; the antenna radiates into dielectric half-space with spatial and time dispersion.     

Retrieving the elastodynamic Green's function of an arbitrary inhomogeneous medium by cross correlation

A correlation-type reciprocity theorem is used to show that the elastodynamic Green's function of any inhomogeneous medium (random or deterministic) can be retrieved from the cross correlation of two recordings of a wave field at different receiver locations at the free surface. Unlike in other derivations, which apply to diffuse wave fields in random media or irregular finite bodies, no assumptions are made about the diffusivity of the wave field. In a second version, it is assumed that the wave field is diffuse due to many uncorrelated sources inside the medium.     

The surface potential method in the problem of wave diffraction by a penetrable cylinder of arbitrary cross section in a layered medium

Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 1, pp. 67–78, January, 1992.