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ABSTRACT: Several inversion algorithms for diffraction tomography have
previously been provided in a wide range of situations where the
firstorder Born or Rytov approximation fails. These algorithms are
based on the assumption of full field data so that it is assumed that
both intensity and phase of the scattered field are measurable. However,
it becomes difficult to measure the phase of the scattered field
directly, if the frequency of the incident wave is beyond several tens
of GHz. Therefore, some intensityonly reconstruction algorithms for the
objects within the firstorder Born or Rytov approximation were
proposed. The present authors give an intensityonly reconstruction
algorithm for the scatterers beyond the firstorder Born approximation.
This algorithm is based on the optimization method minimizing a
functional which is the norm of the discrepancy between the measured
intensity of the total field in the farzone and the calculated one for
an estimated object function. An outer boundary of the scatterer is used
as a priori knowledge at each step of iteration. The proposed algorithm
is an extension of Takenaka et al. (1993) No preview · Conference Paper · Jul 1994

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ABSTRACT: Presents an iterative inversion algorithm of reconstructing twodimensional buried dielectric objects in a crosswell geometry. We define a cost functional as the norm of the discrepancy between the measured scattered field and the calculated one for an estimated object function. Note that the object function is related to the refractive index of the object. Then the inverse scattering problem reduces to an optimization problem where the object function is determined by minimizing the functional. Applying the conjugate gradient method to the optimization problem, one can derive an iterative formula for deriving the object function. Numerical results are presented for a lossy and homogeneous dielectric circular cylinder. The results demonstrate that the proposed algorithm yields highquality reconstructions even for cases where the Born or the Rytov approximation breaks down No preview · Conference Paper · Jul 1994

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ABSTRACT: An iterative technique for reconstructing the image of the refractive index of scatterers from scattered farfield data is presented. The inverse scattering problem is treated as an optimization problem in which the refractive index is determined by minimizing the norm of the difference between the measured scattered field and the calculated scattered field for an estimated refractive index. The standard Tikhonov regularization is not used, but an outer contour of the scatterer as a priori information is incorporated at each step of the iteration No preview · Article · Jan 1993