Electromagnetic techniques for nondestructive testing of dielectric materials: diffraction tomography

The paper first addresses the basic theory of inverse scattering and gives a brief overview of the scattering based imaging techniques proposed over the last decades. A particular backscattering far-field technique [Mensa et al., 1983], which appears to be promising for industrial nondestructive testing owing to its simplicity of implementation, is then presented. The authors' experimental implementation of this technique is described and some preliminary results are given to show the capability of the method in discriminating inhomogeneities in dielectric materials. Finally, the applicability of the technique to real-world situations is discussed. The extensive bibliography is intended to assist the interested readers in acquiring a deeper knowledge of both the theory and the state of the art in microwave imaging.