Multifrequency subsurface sounding and tomography

A new method of the near-field electromagnetic sounding and tomography of subsurface dielectric inhomogeneities is studied. It is based on the transformation of the multifrequency inverse scattering problem to that for the complex-valued synthesized pulse. This new statement of the inverse scattering problem leads to the much better resolution of the scanning tomography based on its solution. Input data are formed by inverse Fourier transform of the scattered field spectrum measured at many frequencies in a broad frequency band at the 2D lateral scanning above the surface of an inhomogeneous medium. So, instead of the frequency dependence of data one deals with the data dependence on the pulse delay or on the corresponding effective depth of scattering. At that, obtained 2D images of such synthesized pulse are free from the noise related to the surface scattering. It makes possible to fix the region of sounded inhomogeneity much more precisely and, hence, to improve the quality of the tomography based on the solution of the inverse scattering problem in this new statement. For subsurface dielectric targets with a homogeneous internal structure, a method of their shape retrieval (computer holography) is demonstrated.