A Three-Dimensional Reconstruction of Stray Magnetic Fields of a Magnetic Head by Electron Beam Tomography

A new fast algorithm for reconstructing the stray magnetic field of a magnetic head by electron beam tomography, and applications of the method, are described. We had previously proposed a method for 3-D reconstruction of stray magnetic fields using an "ART" method of electron beam tomography. In this new algorithm, the magnetic field distribution in the measurement plane just beyond the gap is first reconstructed using the ART method. Then the entire magnetic field distribution is calculated numerically by the boundary element method, using the reconstructed magnetic field in the measurement plane as a boundary condition. Using this method, the total reconstruction time is shortened and reconstruction accuracy is improved considerably. An example of reconstruction of the magnetic field of a MIG head is described. From these results and the results of analyses by a 2-D finite element method, it is shown that the new algorithm is useful for comparatively accurate reconstruction of the entire magnetic field distribution.