M. Tanaka

Kagoshima University, Kagosima, Kagoshima, Japan

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Publications (4)2.33 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A new reconstruction algorithm for diffraction tomography is presented. The algorithm is based on the minimization of a functional which is defined as the norm of the discrepancy between the measured scattering amplitude and the calculated one for an estimated object function. By using the conjugate gradient method to minimize the functional, one can derive an iterative formula for getting the object function. Numerical results for some two-dimensional scatterers show that the algorithm is very effective in reconstructing refractive index distributions to which the first-order Born approximation can not be applied. In addition, the number of iterations is reduced by using a priori information about the outer boundary of the objects. Furthermore, the method is not so sensitive to the presence of noise in the scattered field data
    IEEE Transactions on Antennas and Propagation 09/1995; · 2.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Several inversion algorithms for diffraction tomography have previously been provided in a wide range of situations where the first-order 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 intensity-only reconstruction algorithms for the objects within the first-order Born or Rytov approximation were proposed. The present authors give an intensity-only reconstruction algorithm for the scatterers beyond the first-order 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 far-zone 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)
    Antennas and Propagation Society International Symposium, 1994. AP-S. Digest; 07/1994
  • [Show abstract] [Hide abstract]
    ABSTRACT: Presents an iterative inversion algorithm of reconstructing two-dimensional buried dielectric objects in a cross-well 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 high-quality reconstructions even for cases where the Born or the Rytov approximation breaks down
    Antennas and Propagation Society International Symposium, 1994. AP-S. Digest; 07/1994
  • [Show abstract] [Hide abstract]
    ABSTRACT: An iterative technique for reconstructing the image of the refractive index of scatterers from scattered far-field 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
    01/1993;

Publication Stats

78 Citations
2.33 Total Impact Points

Institutions

  • 1995
    • Kagoshima University
      Kagosima, Kagoshima, Japan
  • 1994
    • Oita University
      • Department of Electrical and Electronic Engineering
      Ōita, Ōita, Japan