Abstract: A phase change recording medium comprising an as-deposited first recording layer configured to undergo a reversible phase change between an amorphous state and a crystalline state due to light irradiation and thereby change an optical characteristic. The as-deposited first recording layer includes a plurality of fine nuclei having an average size of 0.5 nm to 4 nm in the amorphous state.

Abstract: An optical information recording medium includes a substrate, first information recording layer, and second information recording layer. The first information recording layer includes a recording film, first dielectric film whose complex index has a real part n1, second dielectric film whose complex index has a real part n2, and third dielectric film whose complex index has a real part n3. Relationships n1>n2 and n3>n2 are satisfied.

Abstract: An optical information recording medium of this invention includes a substrate, a light incident surface, a first reflecting layer formed between the substrate and the light incident surface, a second reflecting layer formed between the first reflecting layer and the light incident surface and stacked on the first reflecting layer, the second reflecting layer being made of the same material as that of the first reflecting layer, and a phase change optical recording layer formed between the second reflecting layer and the light incident surface, the phase change optical recording layer transiting between a crystal state and an amorphous state when irradiated with a light beam.

Abstract: It is an object to improve the recording transfer rate of a phase change recording medium, to reduce the producing costs of the medium, to greatly increase the degree of freedom for the selection of the substrate of the medium, particularly to provide a medium having a structure of Rc<Ra, and to increase the storage capacity of the medium. In order to accomplish this object, a medium, wherein the initial state is an amorphous state immediately after sputtering, has a structure having a unique short-range order. In addition, there is provided a medium wherein the distribution of the number of crystal grains with respect to grain sizes has a plurality of maximum values. Moreover, when a recording operation is carried out by laser beams, an amorphous state band part is formed between tracks. In addition, the thermal conductivity of a recording layer is in a unique range, and contains Kr or Xe in a specific range.

Abstract: A production process of an optical disk, wherein when a layer of an ultra violet rays curing resin which constitutes a portion of the optical disk is formed, a semi-transparent film of a metal is formed on a molded substrate on which a pattern was transcribed and this molded substrate is used as a semi-transparent stamper, and the production of an optical disk with two layers at one side is made easy thereby.

Abstract: In a phase change optical recording medium, by determining heat conductivity relatively higher in one of interference layers on and under the recording layer, heat absorbed into the recording layer can be released moderately through an interference layer. Thereby, cross erasure caused by heating of adjacent tracks can be prevented, and at the same time, excessive heat radiation is prevented from a part of the recording layer nearer to the substrate to thereby maintain appropriate heat in the recording layer. As a result, cross-erasure is prevented, and data can be rewritten with the supply of typical recording/erasure power.

Abstract: Focusing and tracking can be stably performed using an optical information recording medium in which a high reflectivity and a large reflective change amount can be attained, and the reflectivity change amounts of the lands and grooves are set equal to each other by forming, between a transparent substrate and a first protective layer, an interference layer containing at least one material selected from the group consisting of Au, Ag, Cu, Si, and Ge. Even if information is recorded on the lands and the grooves, it can be recorded/reproduced without any crosstalk from an adjacent track.

Abstract: An optical recording medium, which has a land and a groove on which a record mark is formed, comprises a transparent substrate, an inner protection layer formed on the substrate, a recording material layer formed on the inner protection layer and a reflection layer formed on the outer protection layer. The groove is formed to have a depth of .lambda./6 and the ratio of the thickness of the outer protection layer to the thickness of the recording material layer is set in a range between 0.8 and 1.2.

Abstract: An optical recording medium comprises a transparent substrate, an inner protection layer, a recording material layer, an outer protection layer, and a reflection layer, which are laminated in this order. In an in-groove recording mode, the ratio of the thickness of the recording material layer to the thickness of the outer protection layer is in a range between 0.52 and 0.95. In an on-land recording mode, the ratio of the thickness of the recording material layer to the thickness of the outer protection layer is in a range between 0.32 and 0.6.

Abstract: An optical recording medium comprises a transparent substrate, an inner protection layer, a recording material layer, an outer protection layer, and a reflection layer, which are laminated in this order. In an in-groove recording mode, the ratio of the thickness of the recording material layer to the thickness of the outer protection layer is in a range between 0.52 and 0.95. In an on-land recording mode, the ratio of the thickness of the recording material layer to the thickness of the outer protection layer is in a range between 0.32 and 0.6.

Abstract: According to this invention, there is provided an information recording medium including a substrate, a metal layer formed on the substrate, and a recording layer formed on the metal layer and being formed a recorded portion and a non-recorded portion by changing optical characteristics by radiating a recording light beam, wherein the recording layer contains GeSbTe, a reflectance of the recorded portion of the recording layer is higher than that of the non-recorded portion, and a reflectance of the non-recorded portion is not less than 10%. Focusing and tracking operations can be stably performed.

Abstract: A laser beam is radiated on a recording medium such as a phase transition type optical disk to change optical characteristics depending on a change in arrangement of atoms in a recording layer of the recording medium so as to repetitively record/erase information represented by the lengths of optical marks, the recording power of the laser beam radiated to record the information in the recording medium is changed stepwise in two or more power levels sequentially higher than an erasure power level of a laser beam radiated to erase the information recorded in the recording medium.

Abstract: In an optical memory of phase transition type such that information is recorded or erased by reversibly changing the phase of a thin recording film between equilibrium phase and non-equilibrium phase in response to a laser beam, the memory is formed with a recording film comprising as the main component an intermetallic compound with a melting point between 300.degree. to 800.degree. C. in accordance with a binary target co-sputtering technique. Since the phase transition temperature of the recording film is higher than room temperatures, the recorded film can stably be kept in non-equilibrium phase state for a long time. Further, since the melting point thereof is lower than 800.degree. C., it is possible to record or erase information in or from the medium in response to a relatively small power laser beam.