Two Reconstruction Methods for Microwave Imaging of Buried Dielectric Anomalies

Microwave imaging of anomalies, such as voids or discontinuities, in optically opaque regions is described. Images were reconstructed with two techniques. The experimental technique utilized laser light for reconstructions from detour phase holograms that encoded data measured in the region of Fresnel diffraction. Examples of images are presented for smooth and rough interfaces. The numerical reconstruction technique was based on the angular spectrum technique, and an approximate propagator was derived to describe propagation through two, homogeneous dielectric layers to one anomaly. Image quality was acceptable for either reconstruction method, but the optically reconstructed images are rather small because scale reduction is limited in practice.