Interpretation of the depolarizing effects in vector diffraction tomography

The major difficulty in evaluating possible practical applications of vector diffraction tomography is that experimental data are still sparse and that the data generated usually involve either the Born or Ryton scalar wave approximations. In order to test the depolarizing effects in electromagnetic wave equation needs to be inverted, which at the current state of the art still cannot be done. Instead, for the inverse problem of image formation, oblique incidence on a circular cylindrical scatterer is investigated. It is shown that reconstructions of the exact fields at oblique incidence deteriorate rapidly as the angle of incidence deviates further from normal incidence, due to depolarizing effects. These reconstructions are investigated, and, in addition, it is shown that apparent depolarization of the incident field increases as one approaches the object due to near field effects. The results of these numerical simulations indicate that even a small degree of depolarization strongly affects the quality of the image reconstruction. Therefore, it is concluded that the depolarizing term of the wave equation cannot be neglected in microwave (vector) diffraction tomography