Multifrequency microwave tomography of absorbing inhomogeneities

2011 13th International Conference on Transparent Optical Networks

2011

Possibilities of the coherent scanning tomography with negative-index metamaterial lens are studied. Such lens (a slab of negative refractive index material) has the power to focus the source field into a sounded media with dielectric inhomogeneities. By the 2D scanning with a source-receiver system at a number of levels from the lens surface, this focus can be immersed far into the studied region that makes it possible to realize the proposed tomography. The solution of the corresponding inverse scattering problem, i.e., the retrieval of 3D distributions of the complex permittivity in the inhomogeneous region, is based on the solution of the 3D integral equation for the scattered field that is reduced to the one-dimensional Fredholm integral equation of the 1-st kind relative to the depth profile of lateral spectrum of inhomogeneities. After the solution of this equation for each pair of spectral components, the inverse Fourier transform leads to the desired solution. The feasibility of this tomography for low-contrast targets is demonstrated in numerical simulation.

Section: Inverse Problem Of Scatteringmentioning

confidence: 99%

Section: Numerical Symulationmentioning

confidence: 99%

Metamaterial lens tomography

2011 13th International Conference on Transparent Optical Networks

2011

“…Recently more and more researchers direct their attention to investigation of possibilities of near-field microwave diagnostics [1][2][3][4][5][6][7]. Such diagnostics involves medical (detection of human tumor formations) and industrial applications (flaw detection and hygroscopy), but in both cases restriction is imposed on the depth of field penetration into the examined medium or object.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling and Experimental Investigation of the Breadboard Model of a Near-Field Interference Microscope

2016

Abstract.A circuit design for technology of near-field interference microwave microscopy using evanescent fields of several active radiators (probes) is suggested and substantiated. The feasibility of providing the spatial overlap of the evanescent fields of two probes representing expanding coaxial conical horns is demonstrated. It is shown that the structure of the electromagnetic field in the region of overlap can effectively be controlled by changing the phase difference of oscillations arriving at inputs of the probes. This technology can be used for diagnostics of liquid media comprising dielectric inhomogeneities, flaw detection, and hygroscopy.

The method of multifrequency near-field acoustical tomography of bulk inhomogeneities of the sea bottom

Khil’ko

2011

Radiophys Quantum El

Self Cite

UDC 534.26In this work, we propose a method of near-field acoustical multi-frequency coherent tomography of spatially localized inhomogeneities of the shallow-sea bottom. In the framework of the developed method, two-dimensional spatial scanning of the radiating-receiving system along the bottom over the region of location of the inhomogeneities is performed at multiple frequencies. Using the Born approximation, the initial three-dimensional integral equation for the scattered field is reduced to one-dimensional Fredholm equation of the first kind with respect to the depth profile of the transverse spatial spectrum of the inhomogeneities. In the solution of this integral equation for each pair of spectral components, we use the method of generalized residual and obtain the sought three-dimensinal distribution via the inverse Fourier transform of the reconstructed spectrum. Results of numerical simulation of the tomography scheme and visualized inhomogeneities of shallow-sea bottom are presented.Acoustical methods of remote sensing of the sea are an efficient tool in solving various practical problems related to the development of sea-shelf regions [1][2][3]. In recent years, remote acoustic sensing of the sea bottom has become especially topical. This is related to solving many practical problems of engineering seismics, detection of buried objects in sedimentary layers, and ecological monitoring in the regions of ports, underwater pipelines, and oil-producing platforms. For solving such problems, pulse-type methods using non-coherent seismo-acoustic sources of explosive type became widely spread. Along with this, promising methods of coherent sounding of the sea bottom using towed hydroacoustic radiators are also studied. Utilization of such sources makes it possible to coherently accumulate signals, which significantly helps to increase sensitivity and resolution in the sounding problems [4][5][6][7][8]. However, usually the spatial processing is performed only for synthesized apertures which are formed by translational one-directional motion of the radiating and receiving systems.Creation and testing of coherent hydroacoustic radiators for sea-bottom sounding makes it possible to apply even more efficient methods using the data of two-and three-dimensional scanning [1,2]. We note that many of such diagnostic problems based on data of multi-dimensional observations (see, for example, [8-10]) belong to the class of ill-posed inverse problems, the solution of which can be based on application of regularization methods [9, 10] and use of a priori information [11]. Such problems are topical for underwater engineering prospecting and detection of dangerous objects buried in sedimentary layers.The tomographic method proposed in the present work, i.e., the method of reconstruction of threedimensional structure of inhomogeneities located in the sea bottom based on solving the corresponding backscattering problem, is a natural development of the above-mentioned research. Studies and applications of backscattering proble...