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Séminaire des doctorants - 18 mars 2016

Identification of small objects with near-Field data in quasi-backscattering configuration

Mohamed Lakhal (CMAP)

In this talk we consider a new sampling method for detecting targets (small inclusions or defects) immersed in a homogeneous medium in three-dimensional space, from measurements of acoustic scattered fields created by point source incident waves.

We will describe the harmonic regime with a data setting that corresponds with quasi-backscattering configuration. For this setting the data is collected by a set a receivers that are distributed on a segment centered at the source position and the device is swept along a path orthogonal to the receiver line. We assume that the aperture of the receivers is small compared with the distance to the targets. Considering the asymptotic form of the scattered field as the size of the targets goes to zero and the small aperture approximation, one is able to derive a special expression for the scattered field. In this expression a separation of the dependence of scattered field on the source location and the distance source-target is performed.

This allows us to propose a sampling procedure that characterizes the targets location in terms of the range of a near-field operator constructed from available data.

CMAP UMR 7641 École Polytechnique CNRS, Route de Saclay, 91128 Palaiseau Cedex France, Tél: +33 1 69 33 46 23 Fax: +33 1 69 33 46 46