Abstract: A method for molding a substrate for use in supporting a magneto-optic recording structure includes the steps of providing a mold having a cavity that defines a plane and that is designed to form a thin disk-like magneto-optic substrate and mounting such mold with such plane horizontal and an axis of circular symmetry thereof substantially vertical. Hot fluid plastic flows from the center of such horizontal mold so that the fluid plastic flows relatively uniformly and radially outwardly from the center of the mold to minimize azimuthal variations in birefringence. Such flowing may be by injection or compression molding. Molding apparatus for manufacturing such magneto-optic substrate includes such mold and a support for positioning such mold with the plane thereof horizontal. Hot fluid plastic is injected to the center of such mold, as for example from the vertical axis of symmetry of such mold.

Abstract: A protective layer for a magneto-optically active layer is formed of an outer impermeable layer and an inner layer that protects the active from the outer layer. The outer layer may be an oxide and the inner layer a non-oxide. The oxide and non-oxide layers may form discreet layers or they may be continuously graded. The graded layer may be formed by reactively sputtering aluminum in the presence of reactive gases, oxygen and nitrogen, while continually varying the flowing reactive gas from nitrogen to oxygen.

Abstract: A magnetic magneto-optic recording structure and method in which a magneto-optic active layer is positioned within the fringing magnetic field of a magnetic recording medium, the structure preferably being disk-shaped. The magneto-optic layer is irradiated by a continuous wave laser beam, by way of a transparent substrate thereon, to locally reduce the coercivity of the magneto-optic layer, so that the magneto-optic layer becomes locally magnetized to align itself with the fringing magnetic fields created by the magnetization pattern of information previously recorded on the magnetic recording layer. The information thus recorded on the magneto-optic layer can be read out with a laser beam of lesser power, employing the Kerr effect.