INVERSE SCATTERING OF AN UN-UNIFORM CONDUCTIVITY SCATTERER BURIED IN A THREE-LAYER STRUCTURE

We consider the inverse problem of determining both the shape and the conductivity of an un-uniform conductivity scatterer buriedin a three-layer structure by the genetic algorithm. An un- uniform conductivity scatterer of unknown shape and conductivity buriedin the secondlayer scatters the incident wave from the first layer or the thirdlayer. We measure the scatteredfieldin the first andthird layers. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the imaging problem is reformulatedinto an optimization problem. The genetic algorithm is then employedto findout the global extreme solution of the object function. As a result, the shape andthe cond uctivity of the scatterer can be obtained. Numerical results are given to demonstrate that even in the presence of noise, good reconstruction has been obtained.