Abstract: An air-incident optical recording medium for use with flying heads has a system of layers, which thermally isolate the disk surface from the active, recording layer.

Abstract: An optical information recording medium according to the present invention includes at least one information layer in which a first dielectric film that contains Cr, O and at least one element (M1) selected from Zr and Hf, a recording film that is provided on the first dielectric film and changed in optical property reversibly by irradiation of laser beams, and a second dielectric film that is provided on the recording film and contains Cr, O and the at least one element (M1) selected from Zr and Hf, are provided in this order from a side on which laser beams are incident. The first dielectric film has a Cr atom concentration of at least 6 at %, the second dielectric film has a Cr atom concentration of at least 9 at %, and the Cr atom concentration of the second dielectric film is larger than the Cr atom concentration of the first dielectric film.

Abstract: In an apparatus for fabricating a carbon coating, an object such as a magnetic r cording medium is disposed on a side of an electrode connected to a high-frequency power supply. Ultrasonic vibrations are supplied to the object. Discharge is generated between the electrode connected to the high-frequency power supply and a grounded electrode to fabricate a carbon coating on the surface of the object. Also, an electrode interval is set to 6 mm or less, pressure between the electrodes is set to 15 Torr to 100 Torr, whereby high-density plasma is generated to form an ion sheath on an anode side. Therefore, a coating is fabricated on the surface of the object by bombardment of ions.

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: A film constitution in an optical recording medium including a light incident side substrate and a light reflecting side substrate cooperatively acting as a base of the medium, and includes, between these substrates, those layers formed by sputtering so as to constitute a laminated structure, which layers include: a phase-change recording layer to be phase-changed between an amorphous phase and a crystal phase by laser light irradiation; a first dielectric layer and a second dielectric layer, each having a protective function and an optical adjusting function for the phase-change recording layer; a reflecting film layer for reflecting the laser light transmitted through the phase-change recording layer; a hardness enhancing layer for enhancing the mechanical strength of the medium; and a protecting layer having a function for reducing thermal damages to the light incident side substrate and an optical adjusting function.

Abstract: A protective film for optical disks comprising an acrylic adhesive layer disposed on one face of a light transmitting substrate film, wherein a change in transmittance (X) expressed by equation [1] is 10% or smaller and the amount of elution of halogen ions and the amount of alkaline ions from an acrylic adhesive constituting the acrylic adhesive layer are each 10 ppm or smaller; and an optical disk using the protective film. X(%)=[(Ta−Tb)/Ta]×100  [1] (Ta: an initial transmittance of light of 405 nm through the protective film, Tb: a transmittance of light of 405 nm through the protective film after the protective film is left standing at 80° C. in 85% RH for 1,000 hours). The protective film is used for protecting the information recording layer of the optical disk and the functions of recording and regeneration of the optical disk are not adversely effected.

Abstract: The present invention provides an optical information medium having excellent weather resistance and repeating characteristics. The optical information medium has a barrier layer between a protective layer and a recording layer. The barrier layer includes GeN or GeON, and at least one element selected from the group consisting of Al, B, Ba, Bi, C, Ca, Ce, Cr, Dy, Eu, Ga, H, In, K, La, Mn, N, Nb, Ni, Pb, Pd, S, Si, Sb, Sn, Ta, Te, Ti, V, W, Yb, Zn and Zr.

Abstract: There is provided an optical recording medium capable of preventing cross erase and increasing its recording density. The optical recording medium includes: a reflecting film; a first transparent film provided on the reflecting film; a first semitransparent film provided on the first transparent film; a second transparent film provided on the first semitransparent film; a recording film provided on the second transparent film, the recording film being capable of reversibly changing an atomic arrangement; and a third transparent film provided on the recording film. The first semitransparent film has a complex refractive index of n−k satisfying relationships of 0<n<1 and 1<k, and a product of a thickness d (nm) of the first semitransparent film and an extinction coefficient k of the complex refractive index is d×k≦44.

Abstract: An information recording medium includes a first information layer and a second information layer. The first information layer includes a first recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by irradiation of a laser beam or application of current. The second information layer includes a second recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by the irradiation of the laser beam or the application of the current. The first recording layer is made of a first material, the second recording layer is made of a second material, and the first material is different from the second material.

Abstract: An optical disc is includes a recording layer, a reflective layer, and a protective layer provided, in that order, on one surface of a light-transmissive substrate and a hard coating layer having a thickness in the range of 1 to 5 &mgr;m on the other surface of the substrate. The hard coating layer is formed by applying and curing a solution comprising a hard coating agent containing colloidal silica and a UV-curable acrylic resin and a solvent containing propylene glycol monomethyl ether acetate as a principal constituent. The hard coating layer contains 110 mg/cm3 or less of residual solvent.

Abstract: An optical disk has a substrate, a first protective layer formed on the substrate, a recording layer formed on the first protective layer, a second protective layer formed on the recording layer, and a reflective layer formed on the second protective layer. The recording layer includes a composition expressed as (SbxTe1-x)aGebInc in which atomic ratios are 0.77≦x≦0.84, 0.85≦a≦0.95, 0.01≦b≦0.10 and 0.01≦c≦0.10 where a+b+c=1.

Abstract: Optical information-recording media comprise a first transparent substrate through which a laser beam enters, a first information-recording layer deposited on the first transparent substrate, a first reflection film formed on the first information-recording layer, an intermediate layer deposited on the first reflection film, a second information-recording layer formed on the intermediate layer, a second reflection film deposited on the second information-recording layer, and a second substrate provided on the second reflection film. The recording film of each of the first and second information-recording layers has a main composition represented by (GeTe)xSb2−yInyTe3, and its composition ratio is within ranges of 0.04≦y<2 and 4≦x≦8.

Abstract: An optical information recording medium of the present invention includes a first substrate, a second substrate placed in parallel with the first substrate, and an information layer placed between the first substrate and the second substrate, wherein the information layer includes a recording layer and a dielectric layer (lower dielectric layer/upper dielectric layer) placed so that a distance from the dielectric layer to the recording layer is 20 nm or less. The recording layer is changed between at least two different states that can be identified optically by irradiation of a laser beam incident from the first substrate side, and the dielectric layer contains ZnS and Si as main components.

Abstract: An information recording medium which ensures high reliability and favorable overwrite cyclability is provided, even when an interface layer is not provided between a recording layer and a dielectric layer. The recording layer 4 and the dielectric layers 2 and 6 are formed on the surface of the substrate 1. In the recording layer 4, a phase change is generated between a crystal phase and an amorphous phase by irradiation of light or application of an electric energy. The dielectric layers 2 and 6 are Zr—Zn—S—O-based material layers comprising Zr, Zn, S and O, preferably consisting essentially of a material expressed, for example, with the formula (ZrO2)X(Zn—S)100−X (mol %) wherein X is in the range of 50≦X≦80.

Abstract: Disclosed in this invention is a phase change optical recording material for a rewritable recording medium with a high speed crystallization and excellent erasibility, which comprises a composition having the formula of: (AaBbCc)x(GeaSbbTec)1−x wherein, A is an element selected from the elements belonging to the IVB group in the periodic table; B is an element selected from the elements belonging to the VB group in the periodic table; C is an element selected from the elements belonging to the VIB group in the periodic table; a, b and c are atomic ratios; x is a mole fraction in the range of 0 to 1; and at least one of A, B and C has a higher atomic number and thus a smaller diatomic bond strength than that of the corresponding element in the GeSbTe part.

Abstract: The inventions relates to a laser beam optical recording medium which features several read/write levels, comprising a first half-transparent level and at least a second level, the first one being close to the laser transmitting source, each level comprising a phase changing material layer with two stable states controlled by a laser beam, where the phase changing material is a metallic alloy whose chemical formula writes as: [(GeyTe1-y)a(SbzTe1-z)1-a]1-b(In1-xTex)b with: 0.4≦y≦0.6 0.3≦z≦0.5 0.4≦x≦0.6 0.3≦a≦0.5 0.01≦b≦0.3 the reflection coefficient of the first level being in the range from 10% to 30%, the transmission coefficient being at least 45%, the writing power being lower than 23 mW and the erasing power being lower than 10 mW.

Abstract: An optical information recording medium of the present invention includes: a substrate with at least one selected from the group consisting of a groove and a pit formed on one surface thereof; at least one information layer provided on the surfaces of the substrate, the information layer including at least one selected from the group consisting of a recording film and a reflective film; a resin layer provided on the information layer; and a light transmission layer provided on the resin layer. The resin layer includes a first resin film and a second resin film disposed in this order from the side of the light transmission layer, and when a water absorption rate of the first resin film is represented by A1 and a water absorption rate of the second resin film is represented by A2, A1 and A2 satisfy: A1>A2. The first resin film and the second resin film may have a different flexural modulus of elasticity.

Abstract: Provided is a medium having a phase change recording layer wherein crystallization of the recording layer is facilitated, and at the same time, wherein the region to be crystallized is crystallized at an accurate dimension. The optical recording medium has a recording layer 4 comprising at least one phase change layer 41 and at least one functional layer 42 in contact with said phase change layer. The phase change layer 41 in its as-deposited state is amorphous, and crystals having Fm3m structure or R3m structure are produced upon crystallization of this layer. The functional layer 42 in its as-deposited state is crystalline, and contains crystals having Fm3m structure. The material used for the functional layer 42 is the one which exhibits a thermal conductivity of 0.03 to 5 W/cmK as measured in thin film form of 100 nm thick.

Abstract: To provide an information recording medium which permits high density recording/reproduction, which has good thermal stability, and which, due to the use of an interface layer with a high sputter rate, has good recording/reproduction characteristics and is excellent for mass production. An information recording medium wherein the thickness of an interface layer 3 is 0.25 or more but 0.67 or less of the total thickness of a first protective layer 2 and the interface layer 3, and the interface layer 3 contains at least tantalum (Ta) and oxygen (O). The medium is excellent for mass production and has good recording/reproduction characteristics for high density recording/reproduction.

Abstract: The subject matter of the invention is to provide an optical recording medium with improvements in repeated overwrite characteristics, write power margin, archival stability and the like. The invention provides an optical recording medium having a semi-transparent layer mainly comprising Ag, a first protective layer comprising a dielectric, a phase-change recording layer comprising an alloy mainly comprising SbxTe1−x (0.7<x≦0.9), a second protective layer comprising a dielectric, and a metallic reflective layer in this order, wherein the medium further has an interdiffusion-protection layer between the semi-transparent layer and the first protective layer where the first protective layer comprises a sulfur-containing dielectric, and the medium has a higher reflectance to light incident on the semi-transparent layer side with the recording layer being in an amorphous state than in a crystalline state.

Abstract: An optical recording medium 10 comprises a substrate 1, first protective layer 2, interfacial layer 3, recording layer 4, second protective layer 5, light absorbing and heat generating layer 6, third protective layer 7, reflection layer 8 and a protective film 9 laminated in order. The light absorbing and heat generating layer 6 is a metal layer or an alloy layer containing more than one element out of Ge, Sn, Pb, Cr, Ti, In, Si, Cd, Se, W, Mo, Zr, Nb, Zn and Hf, so that a reflectivity of the optical recording medium 10 and an optical modulation factor, which is an optical modulation factor in a phase changing state of crystalline or amorphous, in the recording layer 4 can be always maintained in high. Accordingly, a recording sensitivity of the recording layer 4 in the optical recording medium 10 can be increased without deteriorating a characteristic such as reflectivity and jitter.

Abstract: An optical information recording composition suitable for use as a recording layer of an optical information recording medium. The optical information recording composition contains Sb, and one or two elements selected from N and O, and optionally one or more elements M selected from Ge, Te, Bi, Sn, Ag, Au, In, Pb, Pd, Pt, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ta, Ga, Zr, Nb, Mo, Ru, Rh, Hf, W, Re, Os, Ir, Dy and Th. A light beam having a wavelength of 200-800 nm can be used to record information on the optical information recording medium and retrieve information therefrom.

Abstract: A thermoplastic composition is described, based on a copolycarbonate which includes at least two structural units. Structure I is usually a conventional carbonate based on bisphenol A, while structure II is a bisphenol carbonate which includes branched or linear groups extending from a bridging carbon atom or carbon group which connects two aromatic rings. The compositions exhibit very good melt flow, along with enhanced shear-thinning behavior. These characteristics are important for optical disc applications. Thus, related articles are described, along with processes for preparing such articles.

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: A multi-time rewritable information recording medium conducting writing by the change of arrangement of atoms under the irradiation of light, comprising, from the light-incident side, a substrate of a thickness of 0.7 mm or less, a lower protective layer of a thickness of 20 nm to 60 nm, a recording film, an upper protective layer, and a reflective layer, wherein the interval between tracks is 0.62 &mgr;m or less. The medium can also possess favorable writing/reading characteristics at high density writing/reading, have large processing margin, use a manufacturing apparatus at a reduced cost, cut material cost, and realize mass productivity with less stresses.

Abstract: An optical recording medium is provided which comprises: a substrate including concentrically or spirally formed grooves each having a V-shaped cross section; a first dielectric layer formed on the substrate; a phase-change recording layer formed on the first dielectric layer; a second dielectric layer formed on the phase-change recording layer; and a metallic reflecting layer formed on the second dielectric layer. In particular, the optical recording medium is so formed that an objective lens having an aperture number of 0.55-0.70 can be used and a laser beam having a wavelength of 600-700 nm and passing through the objective lens is passed through the substrate and then converged on the recording layer, thereby recording or reproducing information on the recording layer in areas corresponding to the grooves.

Abstract: A silicon nitride self-lubricating layer forms the upper surface of a data storage device, such as a rotating disk or a non-rotating memory device, e.g., a credit card-type memory device using a memory strip. The silicon nitride self-lubricating layer can replace the carbon protective overcoat and liquid lubricant used in conventional data storage devices. The silicon nitride self-lubrication layer provides the desired lubrication and protection between the slider and the data storage device. The silicon nitride layer also will not evaporate under high temperatures found in an optical data storage system. In addition, a data storage device may include a plastic polymer layer over which an iron oxide material is deposited. The use of a plastic polymer layer and iron oxide recording layer is particularly advantageous because a low temperature deposition process can be used with the iron oxide material.

Abstract: An information recording medium includes a first information layer and a second information layer. The first information layer includes a first recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by irradiation of a laser beam or application of current. The second information layer includes a second recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by the irradiation of the laser beam or the application of the current. The first recording layer is made of a first material, the second recording layer is made of a second material, and the first material is different from the second material.

Abstract: The present invention pertains to an article of manufacture of restickable and replaceable label technology, particularly for use as replaceable and restickable labels for digital medium discs. In a preferred embodiment, a label is disclosed that comprises an adhesive that permits such label to be securely applied to a digital medium disc in a manner that such label does not disrupt the functionality of such disc. Further, the adhesive permits such label to be removed from the digital medium disc without damaging or disrupting the functionality of such disc. Further still, the adhesive permits such label to be reapplied to a digital medium disc. In a preferred embodiment, a circular label is disclosed that comprises an aperture in the center of such label for aligning the label correctly on a digital medium disc to ensure that the label does not disrupt the operation of such disc after the label has been properly applied.

Abstract: An optical information recording medium comprises a substrate and a multilayered film formed on the substrate, the multilayered film comprising a first information layer, a separating layer, and a second information layer in this order from the side of the substrate. Each of the first information layer and the second information layer comprises a recording layer in which an optical change is caused by irradiation of laser light, and in the first and second information layers, signals can be recorded/reproduced on/from the recording layer by irradiating the recording layer with laser light through the substrate. The first information layer comprises a first protective layer, the recording layer, and a second protective layer in this order from the side of the substrate, and at least one of the first protective layer and the second protective layer comprises at least two layers. The at least two layers comprise a first layer and a second layer in this order from the side near the recording layer.

Abstract: An optical information recording medium includes a first information layer, a separating layer, a second information layer and a protective substrate in this order on a transparent substrate. The second information layer comprises an optical interference layer, a lower protective layer, a recording layer, an upper protective layer, and a reflective layer in this order from the side near the transparent substrate. The reflective layer has a refractive index of at least 2.5 at a wavelength &lgr; of light beams. The second information layer is a reflectance-increase type where the reflectance with respect to the light beams incident from the transparent substrate side after recording is higher than that before recording. It is possible not to provide the optical interference layer if the ratio n1/n2 of the refractive index n1 at the wavelength &lgr; of the recording layer before recording to the refractive index n2 thereof after recording is not more than 0.8.

Abstract: A write once medium having a phase change recording layer is provided. In this medium, stable recorded state and high crystallizability of the recording layer are simultaneously realized. The optical recording medium has a recording layer 4 comprising at least one phase change layer 41 and at least one functional layer 42 in contact with the phase change layer. The component constituting the phase change layer 41 and the component constituting the functional layer 42 undergoes a reaction to produce a reaction product when the phase change layer 41 is heated to a temperature equal to or higher than the melting point of the phase change layer 41, and the area where the reaction product has formed experiences decrease in its optical reflectivity, and the optical reflectivity after such decrease is maintained even if the area wherein the reaction product has formed is heated to the crystallization temperature of the phase change layer.

Abstract: A phase-change optical information recording medium in which information can be recorded, erased, and read includes a substrate and a recording layer overlying the substrate. The recording layer achieves a crystal phase and an amorphous phase. The absorptance Ac of the recording layer in the crystal phase against light having a wavelength of from 370 nm to 450 nm is lower than the absorptance Aa of the recording layer in the amorphous phase against the light. Information is recorded on the recording medium with a recording wavelength of from 370 nm to 450 nm at a recording pitch of 0.3 &mgr;m to 0.52 &mgr;m.

Abstract: A phase-change optical disk includes a first dielectric layer, reflecting layer, first interface layer, recording layer, second interface layer, second dielectric layer, and light-transmitting layer sequentially formed on a support substrate. Information is written on, read from, and erased from the phase-change optical disk by changing a crystalline state of the recording layer with a laser beam radiated from a light-transmitting layer side. A disk reflectance Rc obtained when the recording layer is in a crystalline state is not less than 3% and not more than 12%. A difference in absolute value between the disk reflectance Rc and a disk reflectance Ra which is obtained when the recording layer is in an amorphous state is not less than 10%. A refractive index of one of the first and second interface layers for the laser beam with a wavelength &lgr; is higher than 2.

Abstract: In a magneto-optical disc contained in a cartridge, a first dielectric layer, signal recording layer, second dielectric layer, and light reflecting layer are sequentially stacked on a substrate having formed grooves, and a first protective layer, print layer using at least one color and second protective layer are sequentially stacked on the light reflecting layer. Thickness of the second protective layer is not smaller than that of the print layer, and thickness of the first protective layer is not smaller than 2 &mgr;m. Thus the recording medium having the print layer on at least one surface maintains a sufficient resistance to corrosion and a good slidableness.

Abstract: A method for fabricating read-only copy protected optical medium comprising a light-sensitive material at positions capable of altering the data read during copying of the optical medium but permitting read of the underlying data in the reading of the optical medium.

Abstract: The present invention relates to an optical recording medium having a protective layer and a phase-change recording layer on a substrate, said protective layer containing a metallic oxysulfide and an optical recording medium having a protective layer and a phase-change recording layer, said protective layer being formed by sputtering using a target comprising a metallic oxysulfide.

Abstract: An optical information recording medium of the present invention includes at least one information layer. The information layer includes a first protective film, a first interface film, a recording film having the optical characteristics that are changed reversibly by laser beam irradiation, a second interface film, a second protective film, and a reflective film, present in the indicated order from the laser beam incident side. The first interface film includes an oxide of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si. The second interface film includes carbon or a carbide of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si.

Abstract: Problem to be solved is that when an information recording medium is repeatedly subjected to recording of information several hundreds times, the atoms in a protective layer are diffused and dissolved into a recording layer to lower a reflectivity greatly and make the medium unendurable to many times of overwriting. This problem can be solved by a medium constituted of interference layer 10, interface layer 12, phase-change type recording layer 14, protective layer 13 having a tin content of from 23.3 atomic % to 32.3 atomic %, and a heat sink layer 8 successively formed on substrate 1, as seen from a light-incidence side. By use of this medium, the dissolution of atoms can be prevented, and overwriting for many times can be achieved.

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: In an optical recording medium comprising a phase change recording layer (4) containing Sb and optionally, Te and/or In as a main component, the recording layer is able to be crystallized to provide a crystallized region which contains rhombohedral crystals consisting essentially of Sb and is substantially free of a crystal phase other than the rhombohedral crystals. When the recording layer contains a rare earth element, Zr, Hf, Ti or Sn as an auxiliary component, the medium has a dielectric layer (31) composed of silicon oxide, silicon nitride, aluminum oxide, or a mixture of zinc sulfide and at least 30 mol % of silicon oxide, disposed contiguous to and in front of the recording layer (4) as viewed from the recording/reading beam incident side. The medium has a high transfer rate and improved thermal stability.

Abstract: An optical disc having excellent recording/retrieving characteristics and capable of improving the surface properties of the reflective layer without reducing the thermal conductivity, the reflectivity and producibility. An optical recording medium for recording and/or retrieving information by irradiation of light, which comprises a substrate, and an interlayer, a reflective layer containing a metal as the main component and a recording layer, formed in this order on the substrate directly or via another layer made of a resin or a dielectric material, wherein as observed from a light-incoming direction, the reflective layer is located in front of the interlayer, the interlayer contains the same metal as the metal constituting the main component of the reflective layer and also contains oxygen and/or nitrogen, and the interlayer has a content of the metal smaller than the reflective layer.

Abstract: An optical recording medium is provided with a recording layer made of a phase-change recording material including Ag, In, Sb, and Te as the main constituent elements, with the respective atomic percents of a, b, c, and d thereof being in the relationship of 0.1≦a≦5, 5≦b≦13, 62≦c≦73, 22≦d≦26, and a+b+c+d≧97. Alternatively, the recording material includes the constituent elements of Ag, In, Sb, Te, and Ge, with the respective atomic percents of a, b, c, d, and e thereof being in the relationship of 0.1≦a≦5, 5≦b≦13, 62≦c≦73, 22≦d≦26, 0.3≦e≦3, and a +b+c+d+e≧97. A sputtering target for forming the recording layer is also disclosed.

Abstract: Optical data medium containing a preferably transparent substrate which is optionally already coated with one or more barrier layers and on the surface of which an information layer which can be recorded on using light, optionally one or more barrier layers, and a cover layer, have been applied, which data medium can be recorded on and read using focused blue light through the cover layer on the information layer, preferably laser light with the wavelength between 360 nm and 460 nm, the information layer containing a light-absorbing compound and optionally a binder, characterized in that at least one dye is used as the light-absorbing compound wherein the cover layer on the top of the information layer including the adhesive layer do have a total thickness of 10 &mgr;m to 177 &mgr;m and the numerical aperture NA of the focusing objective lens setup is greater or equal 0.8.

Abstract: A method of forming a crystalline, phase-change layer that remains atomically smooth on its surface. Also, an atomically smooth, crystalline, phase-change layer made according to this method. The method can include forming a phase-change layer over a substrate, forming a thick capping layer over the phase-change layer, changing the phase-change layer from an amorphous phase to a crystalline phase, removing the thick capping layer, and forming a thin capping layer over the phase-change layer.

Abstract: In a material for a heat-resistant protection layer and constituting one of the components of a phase variation type recording medium , at least one compound having a thermal conductivity of higher than 10 W/m·deg inclusive in a bulk state is contained. This kind of material realizes a phase variation type optical data recording medium having a high erasure ratio and allowing data to be repeatedly recorded and erased a number of times by small power even at the time of high-speed recording and erasure.

Abstract: In order to ensure CAV recording/reproduction while preventing jitter deterioration and modulation decrease and thereby ensuring sufficient recording properties, even at a linear velocity higher than 4.8 m/s, a first dielectric film, phase change versatile recording film, second dielectric film, reflection film and protective film are formed on a disc substrate having formed lands and grooves on one major surface. The recording film is made of a GeInSbTe alloy, and the reflection film is made of an AgPdCu alloy or AlCu alloy. Composition of the GeInSbTe alloy is adjusted to contain Ge in the range of 1 to 6 wt %, In in the range of 2 to 6 wt %, and control Sb/Te in the range of 2.2 to 3.0. Composition of the AgPdCu alloy is adjusted to contain Cu not more than 1.5 wt %. Regarding groove conditions, groove depth is controlled in the range of 40 to 50 nm, groove width in the range of 0.40 to 0.

Abstract: An optical recording medium is disclosed which incorporates a recording layer made of a phase-change material. The optical recording medium has a structure such that the ratio Ac/Aa of absorptance Ac realized when the recording layer is in a crystal state and absorptance Aa realized when the recording layer is in an amorphous state is 0.9 or higher. Moreover, a crystallization enhancing layer for enhancing crystallization of the phase-change material is formed which is made to contact with at least either surface of the recording layer. Since control of the absorptance and enhancement of crystallization are simultaneously performed, the difference between the physical properties of crystal and those of amorphous can be reliably compensated for. Thus, a satisfactory direct overwriting can be performed even under high speed and dense conditions.

Abstract: In order to increase the recording capacity while preventing jitter deterioration and a decrease of the modulation factor and thereby ensuring satisfactory recording characteristics, a first dielectric film, phase recording film, second dielectric film, reflection film and protective film are sequentially formed on a disc substrate having formed lands, grooves and wobbling on one major surface. The recording film is made of a GeInSbTe alloy, and the reflection film is made of an AgPdCu alloy or AlCu alloy. Composition of the GeInSbTe alloy is adjusted to contain Ge in the range of 1 to 8 wt %, In in the range of 2 to 6 wt %, and control Sb/Te in the range of 2.2 to 3.0. Composition of the AgPdCu alloy is adjusted to contain Pd in the range of 0.9 to 1.5 wt % and Cu not more than 1.5 wt %. Composition of the AlCu alloy is adjusted to contain Cu in the not more than 1.5 wt %. Groove depth is controlled in the range of 35 to 45 nm, groove width in the range of 0.35 to 0.

Abstract: In order to ensure CAV recording/reproduction while preventing jitter increase and modulation decrease and thereby ensuring sufficient recording properties, even at a linear velocity in the range of 3.49 to 8.44 m/s, a first dielectric film, phase-versatile recording film, second dielectric film, reflection film and protective film are formed on a disc substrate having formed lands, grooves and wobbling on one major surface. The recording film is made of a GeInSbTe alloy, and the reflection film is made of an AgPdCu alloy or AlCu alloy. Composition of the GeInSbTe alloy is adjusted to contain Ge in the range of 1 to 6 wt %, In in the range of 2 to 6 wt %, and control Sb/Te in the range of 2.4 to 3.0. Composition of the AgPdCu alloy is adjusted to contain Cu not more than 1.5 wt %. Groove depth is controlled in the range of 30 to 40 nm, groove width in the range of 0.27 to 0.