Radiation In Inhomogeneous Medium Research Articles

Modelling the propagation of radiation in inhomogeneous media using computations on graphical processors

This paper discusses a number of questions that arise when the propagation of optical radiation in biological tissues is calculated. Results of the modelling are obtained for media with various sets of optical parameters, including a six-layer model of human skin. An approach is presented for increasing the computational efficiency of the method that is used.

Coherent properties of focused wide partially coherent beams in inhomogeneous media

The quasioptics approximation is used to analyze the propagation of a partially coherent radiation beam in a statistically inhomogeneous medium with a regular refractive index profile. This involves solving the parabolic equation for the complex field amplitude which in particular makes it possible to generalize the van Cittert–Zernike theorem (propagation of radiation in inhomogeneous media). The coherence radius is calculated and its ratio to the transverse size of the beam is analyzed.

Wave envelope elements for acoustical radiation in inhomogeneous media

This paper reviews applications of the wave envelope, finite element method to linear acoustical wave propagation. A detailed formulation is given for the particular case of acoustical radiation from a sound source embedded in a region of significant temperature variation. Results are presented for the case of sound propagating along a heated pipe and radiating from an unflanged exhaust. Measured and computed transmission losses are shown to be in close agreement. Although the formulation is presented in the context of acoustical propagation it applies equally well to other wave propagation problems which involve the solution of inhomogeneous, Helmholtz type equations. The analysis presented in this paper and all applications to date are for the axisymmetric case

On the transfer of polarized radiation in inhomogeneous media

On the transfer of polarized radiation in inhomogeneous media

Scattering and information

The paper discusses some aspects of scattering of electromagnetic radiation in inhomogeneous media from the point of view of information theory. A theory is developed, based on a concrete model of a typical scattering experiment, which takes into account the finiteness of the scattering volume and the coherence characteristics of the radiation; as a conclusion, the speckle noise which is superimposed over the signal is brought into evidence. More exactly, it is shown that the spurious oscillations are due to the non-vanishing character of the convolution square of the inhomogeneity distribution function at the point of truncation in the primary space. Subsequently, the structural information of scattering experiments is examined and the finite logoncontent determined. The sampling interval is established and the resolution achievable in scattering measurements is deduced; also the means by which it can be improved are examined. An analysis of the quantitative information obtainable is pursued and the desirability of filtering is suggested. Finally, the way in which the partial coherence effectively acts as a low-pass filter is studied.

Asymptotic Theory of Cerenkov Radiation in Inhomogeneous Media

The problem of Cerenkov radiation in infinite inhomogeneous media is considered. The mathematical description of this phenomenon is given by the integro-differential system of equations for the electromagnetic field in a dispersive medium. The leading term of the asymptotic expansion of the electromagnetic field is obtained by applying an expansion procedure called the ``ray method.'' In this method all the functions that appear in the expansion satisfy ordinary differential equations along certain space-time curves called rays. The source which gives rise to the radiation is taken to be quite general. In fact, it is shown that any multipole moving along an arbitrary trajectory is a special case of the general source considered. From the expansion of the fields an expression for the total energy of the radiation is determined. Then, as an example, the case of plane-stratified media is treated in detail.