An Analytical Model to Study the Transfer of Magnetic Pattern From Videotape to Garnet Film

The magneto-optical readout system based on a signal transfer from videotape to magnetic garnet film has been proposed. To find the garnet film suitable for this system, we developed an analytical pattern of transfer readout. The garnet film considered has a magnetization almost in-plane but slightly inclined with respect to the film plane. On the basis of this model, when a videotape on which the bit length of 0.4 μm was recorded and brought close to the garnet film, the tilt angle of magnetization was estimated to be about 5 degrees for the garnet film with thickness of 0.6 μm, magnetization of 3 × 10^-2 Wb/m², and saturation field of 39 kA/m. The transfer of bit patterns from videotape to garnet film was demonstrated by using a polarizing microscope. The dependence of signal level on bit length obtained by the readout experiment with laser beam in which videotape was moved agreed well with that predicted by calculation.