A new magneto-optic readout head using bi-substituted magnetic garnet film

In the conventional magneto-optic readout head using garner film, a limited region of transferable wavelength, for example 4-20 μm, and comparatively low velocity response (∼ 30 m/s) are major problems to be solved. The new head described here makes use of the fact that the width of straight magnetic domains formed in the garnet film, which is placed close to the recording medium, changes in response to both the strength and the direction of the leakage field from the medium. Experimental results, including a comparison of the new and conventional readout head, demonstrated the superiority of the new readout method in both transferable wavelength (3-250 μm) and dynamic response (∼ 70 m/s). With the use of Bi-substituted magnetic garnet film, a high carrier-to-noise ratio was obtained over a wide frequency range and real time readout of FM video signal recorded on CrO2flexible disk was performed.