Fourier extrapolation of magnetic fields measured by electron-beam tomography

A method for calculating the magnetic field on a plane near a magnetic recording head is presented. In this method, the magnetic field is measured at a plane farther from the head. The method involves taking the Fourier transform of the measured field, enhancing the large wave-number region of the spectrum, and effecting the reverse Fourier transform of the modified spectrum. It is estimated that a field 0.1 μm away from the head can be calculated from a field measured 0.3 μm from it, with a maximum error of less than 0.35%. A field 0.5 μm from a thin-film head calculated from the measured field at 0.7 μm has been compared with actual measurements of the field at 0.5 μm and found to agree within 8%.