Storage Technology Corporation

Kerdix, Inc.

Hoechst Aktiengesellschaft

Boris J Muchnik

Fred W Spong

Bernd F Fischer

Franklin D Kalk

Doyle W Johnston

Frank H Robertson, Iii

A magneto-optic recording structure is disclosed in which the magnetic recording layer is sandwiched between an opaque substrate and a magneto-optic layer structure. The magneto-optic recording structure comprises a substrate, a magnetic recording layer coated on the substrate and a magneto-optic layer structure coated on the magnetic recording layer. The arrangement of layers permits both the magnetic and magneto-optic layers to be addressed from the same side. The magnetic recording layer and the magneto-optic layer structure can be coated on both sides of the substrate, to make double-sided disks. The recording structure also allows the use of opaque substrates. An information recording and playback device based on the magneto-optic recording structure comprises a magnetic recording head disposed adjacent the magneto-optic layer adjacent the magneto-optic layer structure for recording and reading the magneto-optic active layer. A method for recording data on the magneto-optic layer. A method for recording data on the magneto-optic recording structure comprises the steps of recording data in the magnetic recording layer through the magneto-optic layer structure to produce a fringing magnetic field and then locally irradiating an area of the magneto-optic layer structure to raise the temperature of the area so that the area aligns itself with the fringing magnetic field.

Magneto-optic recording structure and method

Apparatus for molding a substrate for use in supporting a magneto-optic recording structure includes a mold having a cavity that defines a plane and that is designed to form a thin disk-like magneto-optic substrate. The mold is mounted 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 horizontally and relatively uniformly and radially outwardly from the center of the mold to minimize azimuthal variations in birefringence. Such flowing is by injection molding. The molding apparatus for manufacturing such magneto-optic substrate includes 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. With the plane of the mold horizontal and the hot fluid plastic flowing horizontally radially and symmetrically outwardly from the center of the mold, the fluid plastic moves substantially horizontally radially and uniformly through the mold. The resulting magneto-optic substrate has relatively small azimuthal variation in birefringence.

Apparatus for molding magneto-optic substrates

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. With the plane of the mold horizontal and the hot fluid plastic flowing radially and symmetrically outwardly from the center of the mold, the fluid plastic moves substantially radially and uniformly through the mold. The magneto-optic substrate has relatively small azimuthal variation in birefringence.

Magneto-optic substrates

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.

Magneto-optic recording media with protective layer

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.

An optical recording structure layer has an optical reflecting layer, a phase layer on the reflective layer, an active layer on the phase layer and a matrix layer on the active layer. The phase layer and matrix layer are substantially transparent to radiation. A thin metal layer on the matrix layer has a thickness from 20 to 100 Angstroms to achieve a relatively constant absorption and reflection characteristics for the structure over a broad band of radiation.

Broad band multilayer optical storage structure having a thin metallic

An information storage device in combination with a radiation recording structure comprising a substrate, a recording layer, a thin electrically conductive over-layer on the outer surface of the recording structure and a neutralizing means for maintaining said over-layer at a neutral electrical potential.

Optical storage structure

A radiation recording structure for use in an information storage device having focused write and read radiation beams includes a substrate supported reflective layer, an active structure supported on the reflective layer. The structure also includes a dust defocusing layer as an outer surface for the structure for defocusing the image of dust on the outer surface and an aluminum adhesion layer between the dust defocusing layer and the active recording layer. The adhesion layer is transparent to the radiation beams and provides surface energy to draw the defocusing layer and the recording layer together.

Laminated optical recording medium that provides desired optical properties in combination with pregrooved channels that define data tracks on which data may be written. Annular or spiral grooves are selectively placed on a base disc substrate. A recording layer is deposited on a transparent disc substrate. The two disc substrates are then bonded together so that the recording layer on the transparent disc substrate confronts the grooves on the base disc substrate. The covered grooves thus form chambers exposed to the recording layer. Prior to bonding the two disc substrates together, the chambers may be filled with an inert gas. A rigid support disc, such as is made from aluminum, may optionally be bonded to the underside of the grooved base disc substrate.

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Boulder, CO, United States of America

Boris J Muchnik