Abstract: A phase-change optical information recording medium in which information can be recorded, reproduced and rewritten and which includes a first transparent substrate having a wobbling guide groove which is spirally formed thereon at a pitch; a first dielectric layer located overlying the first transparent substrate and having an optical thickness of from 80 nm to 200 nm; a phase-change recording layer located overlying the first dielectric layer and having an optical thickness of from 20 to 50 nm when the recording layer is in an erased state; a second dielectric layer located overlying the recording layer and having an optical thickness of from 10 nm to 70 nm; a reflection layer located overlying the second dielectric layer; optionally a third dielectric layer located between the second dielectric layer and the reflection layer; and a second transparent substrate located overlying the reflection layer.

Abstract: An optical information recording medium is provided. This medium at least stores information that indicates a maximum recording linear velocity Vh. The medium comprises a substrate having a concentric circular guide groove. This guide grove has land portions and groves portions. At least a phase change type recording layer is formed on the substrate. The recording layer has such a composition and thickness that a dislocation linear velocity V satisfies the relation V≧Vh×0.85.

Abstract: A phase-change optical information recording medium capable of recording information therein, reproducing recorded information therefrom, rewriting recorded information, and erasing recorded information therefrom, which phase-change optical information recording medium is provided with a recording layer containing therein a phase-change recording material including Ge, Ga, Sb, Te, and one element selected from the group consisting of Mg and Ca, which recording material is capable of performing a reversible phase transition from a noncrystalline phase to a crystalline phase and vice verse with the application of an electromagnetic wave thereto.

Abstract: An optical recording medium including a recording layer which includes a reversible phase-change recording material, the recording layer being capable of writing information therein, reading written information therefrom, and rewriting written information by utilizing the reversible phase change of the phase-change recording material, wherein when a recording mark formed in the recording layer is repeatedly read 5000 times, using a continuous wave laser beam having such an intensity Pr that satisfies the condition of 1.1 ≦R≦2.0, in which R is &dgr;repeat/&dgr;1 as defined in the specification, the optical recording medium satisfies a relationship of d1>dow as defined in the specification. The phase-change recording material, a method producing the optical recording medium, and a method of writing information in the optical recording medium, reading written information therefrom and rewriting written information thereare are proposed.

Abstract: An optical recording medium includes: a substrate on which information is recorded as phase pits, and a polarization state varying layer for rotating a polarization state of a light beam irradiated thereon in accordance with a temperature distribution caused by irradiation of the light beam. A device for reproducing information recorded on the optical recording medium includes: light irradiation unit for irradiating a read-out light beam to produce a light spot on the optical recording medium so that a light intensity of the light beam at a first portion of the light spot is higher than a predetermined level, separation unit for separating a component of light beam having a predetermined polarization state from a light beam reflected by the optical recording medium, light receiving unit for receiving the light beam separated by said separation means and generating read-out signal, and reproducing unit for reproducing information recorded on the optical recording medium on the basis of the read-out signal.

Abstract: The magneto optical disc is provided with at least first and second recording layers such that the record information is recorded to the first recording layer at a vertically magnetized state thereof and is also recorded to the second recording layer at a vertically magnetized state thereof. The information recording method of recording record information to the magneto optical disc is provided with the steps of: controlling an output power of a recording light; irradiating the recording light to the record position; and applying, while irradiating the recording light to the magneto optical disc, to the record position, an external magnetic field.

Abstract: A magneto optical disc, is provided with: a record layer to which information is recorded in a perpendicular magnetization condition; a switch layer, which perpendicular magnetic anisotropy is reduced at a room temperature and is increased at a temperature close to a predetermined reproduction temperature; and a reproduction layer opposed to the record layer through the switch layer to have a switched connection with the record layer by the switch layer.

Abstract: An optical disc has a plurality of tracks arranged in a radical direction of the disc. On each track, a plurality of servo areas for recording servo information and a plurality of data areas for recording data information are provided. A heat blocking band is provided between adjacent tracks in the data area for preventing heat from transmitting to the data area.

Abstract: A magneto-optical recording medium includes: a mask layer having a first compensation temperature higher than a predetermined reproduction temperature and lower than a predetermined first recording temperature, a first Curie temperature higher than a predetermined second recording temperature and a first coercive force, and for storing information assigned to magnetizing directions; and an information recording layer having a second compensation temperature higher than the reproduction temperature and lower than the first compensation temperature, a second Curie temperature lower than the second recording temperature and a second coercive force, and for storing information assigned to magnetizing directions.

Abstract: Method and apparatus for recording information on an overwritable optical disk in which data is recorded on the disk with a writing beam spot while shifting the writing beam spot in a radial direction by a pitch smaller than the diameter of the writing beam spot for each rotation of the disk. In a reading operation, a reading beam having a shorter wavelength than that of the writing beam is used to read recorded data.

Abstract: An optical disk includes: a substrate shaped in a disk, and having a recording surface; a plurality of recording tracks formed substantially coaxially on the recording surface; a plurality of information pits, which are reproducible by a super resolution reproduction, recorded on the plurality of recording tracks in a recording operation of the optical disk; and an address pit for address reproduction formed in advance to the recording operation on the recording surface with respect to one set of recording tracks adjacent to each other in a radial direction of the optical disk.

Abstract: An optical recording disk includes a light transmissive substrate, a recording film disposed on the substrate directly or through an intermediate layer and a protection film disposed on the recording film. The protection film consists of a dielectric material and the entirety of an upper flat surface and a side surface of the recording film is integrally covered with the dielectric material protection film.

Abstract: An optical recording disk in which a transfer layer having grooves made of ultraviolet setting resin is laminated on the surface of a substrate, and in which a recording layer is laminated on the transfer layer, the optical recording disk comprises a peeling protrusion projectingly provided on the inner circumferential side of the transfer layer.

Abstract: A magneto-optical recording disk comprises a transparent substrate on which a magneto-optical recording layer made of a rare earth-transition metal alloy having an uniaxial magnetic anisotropy is sandwiched by a pair of dielectric layers is characterized that the dielectric layers are deposited in an amorphous state by means of a low pressure sputtering method.