Abstract: The present invention relates to an optical recording media including two or more information layers, at least one of the information layers including a writable recording film. In the optical recording media, at least one information layer has protrusions and recesses that permit tracking and at least another one information layer is substantially flat.

Abstract: An optical disc apparatus in this invention includes an offset control unit which selects a parameter in accordance with the type of optical disc, and executes signal processing (offset control) by using the selected parameter.

Abstract: In an optical disk of the invention composed of two substrates bonded to each other, the level of double refraction is set to 60 nm or less in a read-only disk, to 60 nm or less in a write-once type disk, and to 40 nm or less in a rewritable type disk, respectively.

Abstract: The optical disk has the resin material layer provided between the metal layer of the first substrate and the thin layer of the material capable of transmitting light of a predetermined wavelength of the second substrate. The resin material layer has different properties imparted thereto between a location close to the opening and a location away from the opening.

Abstract: A phase-change optical recording medium includes a phase-change optical recording film that permits reversible phase change between a crystalline phase and an amorphous phase upon irradiation with light, and an interface film formed of hafnium oxide, or a mixture of hafnium oxide and at least one oxide selected from the group consisting of cerium oxide, titanium oxide and zirconium oxide, and formed in contact with at least one surface of the phase-change optical recording film.

Abstract: An optical recording medium of the present invention includes a light-transmitting substrate having spiral or concentric grooves formed in at least one major surface, a phase change recording film which is formed on the grooved surface of the substrate and reversibly changes phase upon irradiation of a light beam and thereby changes optical characteristics, and a reflecting layer formed on the phase change recording film, characterized in that the spiral or concentric grooves form, on at least one major surface of the substrate, lands and grooves as a rewrite region in which data is rewritten, the distance between the outer perimeter of the rewrite region and the center of the spiral or circle of the grooves is 58.5 mm or less, and the distance between the centers of a land and a groove adjacent to each other is 0.61 .mu.m to 0.62 .mu.m.

Abstract: An optical disc is constructed for operation in an alloying mode and includes first recording sublayer of Ge--Sb--Te and a second recording sublayer of Bi--Te. Apparatus is provided for recording information on an optical disc in the alloying mode or phase transformation mode in accordance with disc type information associated with the disc and readably by the apparatus. There is also provided an environmental aging technique for use in constructing optical discs to obviate significant dimensional changes in the discs during use between the extremes of the operating environment. There is further provided an optical disc construction and method in which an inorganic dielectric deposited on an organic substrate includes a hydrocarbon. There is additionally provided an optical disc construction and method in which a plasma polymer layer is disposed between an inorganic dielectric layer over the recording layer and a resin layer.

Abstract: The present invention relates to an optical disk and a method of manufacturing the same, and, more particularly, to an optical disk which can ensure high-density recording and a method of pre-formatting this optical disk. This optical disk has a surface on which data is retrieved with a focused light beam and a light beam spot of a predetermined size is formed by the focused light beam, and comprises a first pit group having a plurality of unit pits of a unit pit length arranged in such a manner that adjoining unit pits are separated from each other with a blank of a first blank length, the blank being smaller than a size of the beam spot, the first blank length being set shorter than the unit pit length, and a second pit group following the first pit group and having a plurality of data pits whose lengths are substantially integer multiples of the unit pit length, the data pits being separated from one another with a blank of a second blank length.

Abstract: The present invention provides an information recording medium including a first recording film formed on a substrate and having an amorphous phase made of an alloy containing at least Ge and Te, and a second recording film formed on the first recording film and made of a material with a relatively large light absorption coefficient, wherein the alloy of the first recording film exhibits a Raman scattering spectrum having scattering peaks at 140 to 160 cm.sup.-1 and 120 to 130 cm.sup.-1 and no scattering peaks at 100 to 110 cm.sup.-1, and recording is performed by changing optical characteristics by alloying the materials of the first and second recording films by radiating recording light on the first and second recording films.

Abstract: The present invention provides an information recording medium including a first recording film formed on a substrate and having an amorphous phase made of an alloy containing at least Ge and Te, and a second recording film formed on the first recording film and made of a material with a relatively large light absorption coefficient, wherein the alloy of the first recording film exhibits a Raman scattering spectrum having scattering peaks at 140 to 160 cm.sup.-1 and 120 to 130 cm.sup.-1 and no scattering peaks at 100 to 110 cm.sup.-1, and recording is performed by changing optical characteristics by alloying the materials of the first and second recording films by radiating recording light on the first and second recording films.