Abstracts

Cybernetiks

The radiotomograph is a device operating electromagnetic radiation of a radio-frequency range and permitting on the basis of the data of radioprobing to restore internal electrophysical structure of object of researches. The method of a radiotomography is called to expand range of inspected parameters and integrally to supplement known methods x-ray, YMR and ultrasonic tomography. Down to the present time of really operational radiotomographs suitable for usage in practice, is not created. In the report the operational automated experimental model of such tomography is described and the paths of increase of its self descriptiveness are considered.

The main difficulty on paths of creation of a radiotomograph consists in complexity of interpretation of outcomes of probing in a case, when the wavelength of radiation is commensurable dimensioned of heterogeneities. The objectively existing effects of diffraction, interference, absorption and repeated interaction hinder with the solution of the inverse task, i.e. recovery of an inner pattern of object of researches on observable field distortions. The combination, offered in the report, of the hardware and algorithmic solutions of the task by a method of a double focusing allows essentially to lower influence of diffraction and repeated interactions and by that to increase accuracy of interpretation of outcomes of probing. The experimental model, created on this basis, of a radiotomograph already has given reassuring outcomes. So on a wavelength 3 sm the action mock-up of a microwave tomography is created, in which for creation of effect of a double focusing the radiowave lenss, manufactured of gypsum are used. The working zone of probing has the localized cylindrical form dimensioned 3 on 30 sm. In this zone there is a homogeneous electromagnetic field. Falling here of non-uniformity sounding of a medium render influence to amplitude and phase of a past electromagnetic wave. The effects of diffraction quite satisfactorily are described within the framework of a phase approximation of Huigense-Kirchoff method. The inversion of observed wave projections and reconstruction of structure of different heterogeneities are obtained by multiage sounding. For automation measurements and the data processing are used mathematical packets Labview and Mathcad.

The perspectives of increase of self descriptiveness of a radiotomography are connected to usage of ultra broadband radio emission and phased antennas. It will supply ensure a higher depth of penetration of radiation; will increase the sanction of heterogeneities and response multiage sounding. Singularities theoretically are parsed which can arise at a tomography of mediums with a strong absorption, at presence of non-linear actuations and at a tomography of opaque objects.

This work is supported by grants of Russian Foundation of Basic Research N 01-02-17233-а and Ministry of Education of Russian Federation N Т00-2.4-2119.

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