Abstract: An optical recording medium includes a substrate, a first recording layer formed on the substrate and containing an element selected from the group consisting of Si, Sn and Ge as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Ag as a primary component, the optical recording medium being constituted to be irradiated by a laser beam projected onto the side opposite from the substrate. According to the thus constituted optical recording medium, it is possible to decrease a noise level and improve a C/N ratio in a reproduced signal.

Abstract: An optical information medium which has excellent abrasion resistance and which further exhibits sufficient smudge-proof properties is provided. The optical information medium is coated on at least one surface with a film of a silane coupling agent containing a water- or oil-repellent substituent, said silane coupling agent being represented by the following formula (1): R1—Si(X)(Y)(Z) wherein R1 is the water- or oil-repellent substituent; X, Y and Z are independently a monovalent group; and at least one of X, Y and Z is a group which is capable of forming Si—O—Si bond by polycondensation with silanol group; and said medium has an underlying layer formed in contact with said silane coupling agent film, and at least the surface of said underlying layer comprises a compound having a chemical bond represented by the formula (2): M-A wherein M is a metal atom (including a semimetal), and A is a chalcogen atom selected from O, S, Se, and Te, nitrogen atom, or carbon atom.

Abstract: An optical recording medium includes a substrate, a first recording layer formed on the substrate and containing an element selected from the group consisting of Si, Ge, C, Sn, Zn and Cu as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Al as a primary component, the optical recording medium being constituted to be irradiated by a laser beam projected onto the side opposite from the substrate and the total thickness of the first recording layer and the second recording layer being equal to or thinner than 40 nm. According to the thus constituted optical recording medium, it is possible to decrease a noise level and improve a C/N ratio in a reproduced signal.

Abstract: An optical recording medium includes a substrate, a protective layer, a first recording layer containing an element selected from a group consisting of Si, Ge, Sn, Mg, In, Zn, Bi and Al as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Cu as a primary component. When the optical recording medium is irradiated with a laser beam, the element contained in the first recording layer as a primary component and the element contained in the second recording layer as a primary component are mixed by the laser beam and a region whose reflection coefficient has been changed is formed, whereby information is recorded.

Abstract: An optical information medium is provided which has a light-transmitting substrate which exhibits excellent light transmittance when a laser beam of blue/violet region or ultraviolet region is used as the recording and/or reading beam; whose light transmittance is not substantially affected by the variation or fluctuation of the oscillation wavelength of the laser beam source; which has a long-term weatherability; and which exhibits sufficient protective effects against exterior impacts. The optical information medium includes an information recording layer and a light-transmitting substrate, and the medium is used such that the recording and/or reading laser beam reaches the information-recording layer through the light-transmitting substrate. The light-transmitting substrate has a light transmittance T and difference &Dgr;T between the maximum value and the minimum value of the light transmittance T in arbitrary wavelength range of 10 nm which satisfies the relations: T≧0.8 and &Dgr;T≦0.

Abstract: An optical information medium which has excellent abrasion resistance and which further exhibits sufficient smudge-proof properties is provided. The optical information medium is coated on at least one surface with a film of a silane coupling agent containing a water- or oil-repellent substituent, said silane coupling agent being represented by the following formula (1): R1—Si(X)(Y)(Z) wherein R1 is the water- or oil-repellent substituent; X, Y and Z are independently a monovalent group; and at least one of X, Y and Z is a group which is capable of forming Si—O—Si bond by polycondensation with silanol group; and said medium has an underlying layer formed in contact with said silane coupling agent film, and at least the surface of said underlying layer comprises a compound having a chemical bond represented by the formula (2): M—A wherein M is a metal atom (including a semimetal), and A is a chalcogen atom selected from O, S, Se, and Te, nitrogen atom, or carbon atom.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, distance between the adjacent information-storing layers is reduced with no increase in cross talk between these layers. The optical information medium has at least two information-storing layers each storing recorded information and/or servo information, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s). The medium has a filter layer between the adjacent information-storing layers, and in the spectral absorption characteristics in the wavelength range of 300 to 1000 nm of this filter layer, a wavelength range exhibiting an absorption of 80% or higher and a wavelength range exhibiting an absorption of 20% or lower are present.

Abstract: An optical information medium has a light-transparent substrate and an information recording layer, wherein optical recording and/or reading is performed with a laser beam that enters the information recording layer from the light-transparent substrate side. A cured polysilazane film is disposed on the laser beam incident side of the light-transparent substrate, and the light-transparent substrate or the light-transparent substrate having the cured polysilazane film integrated thereon has a tensile modulus of at least 200 MPa. The medium on its laser beam incident side surface is improved in mar resistance.

Abstract: An optical recording method that performs recording by irradiating optical recording media with laser beam modulated in intensity based on a write waveform is provided. The write waveform has a plurality of write pulse blocks for forming write marks, and each write pulse block has at least one type of upward pulse. In the event that the width of said upward pulse is so narrow that the laser beam intensity corresponding to the peak intensity of that upward pulse cannot be obtained, the peak intensity of that upward pulse is increased so that, in said laser beam, the beam intensity it should have or a value close thereto is obtained. Thereby, good recording and playback characteristics can be obtained even when recording at a high transfer rate.

Abstract: An optical information medium comprising at least two data layers for bearing recorded information, and a servo layer for bearing tracking servo, information which is independently formed from the data layers; wherein the medium is used with a recording or reading system wherein a data beam for recording or reading the data in the data layer and a servo beam for reading the tracking servo information in the servo layer are used, and the servo layer is read by the servo beam that had passed through the data layer; and a filter layer is disposed between the data layer and the servo layer, and the filter layer exhibits higher absorption to the data beam than to the servo beam.

Abstract: An optical information medium includes a support substrate (20) having an information recording layer (4) on one surface, and a light transmissive layer (2) thereon, wherein writing and/or reading light enters the information recording layer (4) through the light transmissive layer (2). The light transmissive layer (2) includes a light transmissive resin sheet (201) and an adhesive layer (202) of a UV-curable resin joining the light transmissive sheet to the support substrate and having an average thickness from 0.5 &mgr;m to less than 5 &mgr;m. The light transmissive layer has a uniform thickness, minimized optical heterogeneity, and least increased birefringence and is effective for restraining medium bowing.

Abstract: An optical recording medium wherein a recording layer, an absorbent layer and a radiating layer are provided in this order as seen from a recording/reproducing light incidence side and recording/reproduction is carried out on a condition that an extinction coefficient k of the absorbent layer is k>0 in a wavelength of recording/reproducing light, and a relationship between a wavelength &lgr; of the recording/reproducing light and a numerical aperture NA of an irradiating optical system of the recording/reproducing light is &lgr;/NA≦680 nm. An optical recording medium wherein an absorbent layer and a recording layer are provided in this order as seen from a recording/reproducing light incidence side and an extinction coefficient k of the absorbent layer is k>0 in a wavelength of recording/reproducing light, and a signal including a minimum mark having a mark length Ms of MS≦0.17 &mgr;m is recorded.

Abstract: An optical information medium comprises a supporting substrate, an information recording surface 4 on the supporting substrate and a light-transmitting layer of resin on the information recording surface. Recording light and/or reproducing light are incident on the information recording surface through the light-transmitting layer. The light-transmitting layer is obtained by curing a resin layer containing an ultraviolet-curing cationic resin. If the light-transmitting layer is formed by repeating the cycle of resin coating and curing or drying a plurality of times, the uniformity of thickness of the light-transmitting layer can be much more improved and the amount of warpage can be much more reduced. Repetition of the cycle of resin coating and curing or drying is also effective for resins other than the ultraviolet-curing cationic resin.

Abstract: An optical recording medium of the invention comprises a phase change type recording layer on a surface of a substrate with reading light incident on the recording layer through the substrate, and a dielectric layer provided in contact with the recording layer and on a side of the recording layer on which the reading light is incident. The substrate has a groove acting as a guide groove and a land between adjacent grooves so that the groove and land are used as recording tracks. The phase change type recording layer contains Ag, In, Sb and Te as main components, and has a thickness tR defined by tR≦&lgr;p/20 where &lgr;p is a wavelength of the reading light. The dielectric layer has a thickness td1 that is represented in terms of an optical path length at the wavelength &lgr;p and defined by &lgr;p/2≦td1.

Abstract: In an optical recording medium comprising a grooved light-transparent substrate, a phase change recording layer, a dielectric layer and a reflective layer, recording is carried out by irradiating a laser beam to the recording layer through an objective lens in an optical system. The recording is carried out in the grooves under the conditions: 0.48≦PT/(&lgr;/NA)≦0.74, and PT≦0.50 &mgr;m wherein &lgr; is a laser beam wavelength, NA is an objective lens numerical aperture, and PT is a track pitch, thereby forming a recorded mark having opposite ends extending out of the groove. This enables high density recording and increases the data transfer rate of a phase change optical recording medium.

Abstract: An optical information medium has a light-transparent substrate and an information recording layer, wherein optical recording and/or reading is performed with a laser beam that enters the information recording layer from the light-transparent substrate side. A cured polysilazane film is disposed on the laser beam incident side of the light-transparent substrate, and the light-transparent substrate or the light-transparent substrate having the cured polysilazane film integrated thereon has a tensile modulus of at least 200 MPa. The medium on its laser beam incident side surface is improved in mar resistance.

Abstract: An optical information medium is provided. The medium comprises a supporting substrate, an information recording layer thereon, and a light-transmitting layer thereon and a recording or reading laser beam enters the recording layer through the light-transmitting layer, and in such medium, recording/reading characteristics are improved when the beam spot of a laser beam has a small diameter and the linear velocity is high with the function of the light-transmitting layer to protect the information recording layer maintained at a sufficient level. Also provided is a medium wherein storage stability is improved.

Abstract: An optical information medium is provided which has a light-transmitting substrate which exhibits excellent light transmittance when a laser beam of blue/violet region or ultraviolet region is used as the recording and/or reading beam; whose light transmittance is not substantially affected by the variation or fluctuation of the oscillation wavelength of the laser beam source; which has a long-term weatherability; and which exhibits sufficient protective effects against exterior impacts. The optical information medium comprises an information recording layer and a light-transmitting substrate, and the medium is used such that the recording and/or reading laser beam reaches said information-recording layer through said light-transmitting substrate. The light-transmitting substrate has a light transmittance T and difference &Dgr;T between the maximum value and the minimum value of the light transmittance T in arbitrary wavelength range of 10 nm which satisfies the relations: T≧0.8 and &Dgr;T≦0.

Abstract: An optical information medium comprising at least two data layers for bearing recorded information, and a servo layer for bearing tracking servo information which is independently formed from the data layers; wherein the medium is used with a recording or reading system wherein a data beam for recording or reading the data in the data layer and a servo beam for reading the tracking servo information in the servo layer are used, and the servo layer is read by the servo beam that had passed through the data layer; and a filter layer is disposed between the data layer and the servo layer, and the filter layer exhibits higher absorption to the data beam than to the servo beam.

Abstract: An optical information medium comprising a supporting substrate, an information recording area on the supporting substrate, and a light-transmitting layer covering at least the information recording area, wherein the information recording area is irradiated with the recording/reading laser beam through the light-transmitting layer, and wherein the light-transmitting layer is highly scratch resistant upon contact with the optical pickup is provided. Also provided is an optical information medium which has a scratch-resistant light transmitting layer, and which experiences reduced vibration in high-speed rotation without suffering from problems in focus servo and tracking servo. In such optical information medium, the surface of the medium on the side of the laser beam incidence at least in the part above the information recording area has a dynamic coefficient of friction of up to 0.4.