| 摘要 |
A magneto-optic disc recording system includes an E-shaped electromagnet for providing magnetic biasing selectively for the recording and erasing processes. The middle arm of the E comprises a first pole piece and is positioned radially with respect to the disc rotation, on the opposite side of the disc from, but aligned with, the path of radial motion of the focused recording/erasing light beam. The other arms of the E, parallel to the middle arm, comprise second pole pieces opposite in polarity from the first pole piece, and are positioned adjacent the disc recording surface on the opposite side of the disc from the middle arm. Two shoes of a magnetic material, coupled to the optical translation stage, provide a magnetic circuit between the respective second pole pieces and the area surrounding the objective lens focusing light on the disc recording surface, relaying a substantially vertical magnetic field through the disc at the point of incidence of the focused light beam. The density of magnetic flux at the point of incidence is increased by (a) incorporating a ring of a magnetic material on the barrel of the objective lens, thus relaying flux from the shoes to a position more vertically oriented with respect to the point of incidence; and (b) forming a narrow ridge along the first pole piece directly opposite the path of radial motion of the focused light beam, thereby concentrating the flux path through the point of incidence.
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