Inverse scattering approach based on the field equivalence principle: inversion without a priori information on incident fields.

An inverse scattering approach based on the field equivalence principle is developed for reconstructing the parameters of the medium of a scattering object. A problem equivalent to the original scattering problem but internal to the measurement surface is set up. The equivalent surface currents determined by the measured total-field data rigorously yield the incident fields in the region under test, so the approach does not require explicit knowledge of the incident fields. Taking into account the fact that the equivalent surface currents produce a null field external to the surface, a functional of the medium's parameters is introduced, and a genetic algorithm is applied to minimization of the functional. Numerical simulations for imaging defects in a known dielectric cylinder from only total-field data measured on an observation surface are performed to illustrate the efficacy of the proposed inversion method.