Abstract: A recording medium which has, formed on a substrate, a recording layer that contains spherical grains having a substantially uniform grain size and including inorganic grains. Preferably, an undercoat layer having no substantial information recording ability is formed between the substrate and the recording layer.

Abstract: An optical data storage system writes or reads information with respect to an optical storage medium using an optical pickup including a solid immersion optical system or a solid immersion lens for generating a near-field and emitting a light beam. The optical storage medium includes a recording layer which is formed on a surface of an optical transmissive layer opposite to another surface of the optical transmissive layer which opposes the solid immersion optical system or solid immersion lens. The thickness of the optical transmissive layer is larger than one wavelength of the light beam. The interval between the surfaces of the solid immersion lens or solid immersion optical system and the optical transmissive layer is smaller than one wavelength of the light beam. Thus, the light beam reflected from the inside of an air gap and the inside of the optical storage medium between the air gap and the recording layer does not function as noise with respect to the light reflected from the recording layer.

Abstract: An optical recording medium for recording and reproducing information utilizing the change of a physical property of a recording layer caused by the irradiation with light, which comprises a substrate, characterized in that the substrate comprises a hydrogenated styrene polymer having a content of nucleus-hydrogenated styrene units of 80 wt % or more, has a glass transition temperature of 110° C. or higher, has a light transmittance of 88% or more at 400 nm, and exhibits an absolute value of retardation of 30 nm or less at 0° and 30° from the normal direction of the plane thereof. The optical recording medium suitable for use in the high density optical recording capable of responding to a greater number of openings and the use of a light having a shorter wave length in an optical head.

Abstract: The present invention is a multilayer optical disc formed of a plurality of information recording sections having a phase change recording layer. A first information recording section provided at a laser-incident side uses, as a recording material, a phase change recording material which uses Sb and Te as major components and satisfies their ratio of 2.3<Sb/Te≦4.0 according to the atomic ratio. Since this phase change recording material provides a fast crystallization speed, it is possible to stably record, reproduce, and rewrite an information signal at a high transfer rate.

Abstract: An optical data storage device for multi-level recording having: a substrate, and a phase change memory medium supported by the substrate. The phase change memory medium preferably has an alloy with a eutectic crystallization base component and at least one element for enhanced sigma-to-dynamic range. The multi-level data storage device is preferably an optical disk with a single layer of memory material for providing multi-level recording with a sigma-to-dynamic range of less than 2%.

Abstract: A write-once high density optical storage medium. The optical storage medium is applicable in an optical read or write system with blue laser having a wavelength in between 385 nm to 425 nm and an objective lens with numerical aperture (NA) greater than 0.8 and includes the following film structure: a substrate; a reflective layer disposed on the substrate; a dye recording layer disposed on the reflective layer; a protective layer disposed on the dye recording layer; and a cover layer disposed on the protective layer. The protective layer prevents direct contact between the dye recording layer and cover layer, thus assuring the medium quality.

Abstract: High density data storage device has a support substrate and one or more different types of phosphors contained at each of plural regularly arranged microscopic regions of the support substrate. Each of the different types of phosphors has a fluorescence characteristic that may be faded by incident light having a different predetermined wavelength. The use of near-field light facilitates a reduction in size of the space required for each data bit. By providing a plurality of different types of phosphors at each of the microscopic regions, the amount of information storable at each bit space is rendered multi-valued to enable higher density recording.

Abstract: An optical disk exhibits enhanced overwrite overwrite characteristics and cross-erase suppression. An optical disk includes a flattening layer formed on a substrate; a reflective layer formed on the flattening layer; a phase-change optical recording layer formed on the reflective layer, the recording layer being changeable between crystalline and amorphous states, portions of the recording layer to become the crystalline state exhibiting reflectivity lower than other portions of the recording layer to become the amorphous state; a plurality of dielectric layers stacked on the recording layer, at least two of the dielectric layers having different optical constants; and a light absorbing layer formed at one location selected from a location between the recording layer and the lowermost layer of the dielectric layers, a location between any of two adjacent layers of the dielectric layers, and a location on the uppermost layer of the dielectric layers.

Abstract: An optical information recording medium having a recording layer for inducing a reversible phase change by irradiation with energy beam. The recording layer contains Te, Ge, Sb, and N, and the concentration of the N being contained is in a range of about 0.1% by atom to about 10% by atom. In this constitution, an excellent repeated recording and erasing performance is obtained.

Abstract: An optical disc has a support base and at least one information-retrieval layer formed over the support base. The information-retrieval layer is transparent and thinner than the support base. The information-retrieval layer exhibits variation in birefringence within ±20 nmpp (nano meter peak to peak) under double-pass measurements during one rotation of the optical disc.

Abstract: The invention relates to a multi-level optical recording medium for a read/write system using a laser beam, comprising at least one substrate (4a, 4b) and a set of layers forming a deep level (12), and at least one semi-transparent level (10), each of these levels having two stable states reversible under the effect of laser radiation,

Abstract: An optical medium for storing digital data thereon comprising a sequence of binary indicators on a first layer, a reflective layer disposed on the first layer, and a photosensitive layer disposed on the reflective layer, the reflective layer disposed between the first layer and the photosensitive layer, the photosensitive layer experiencing a perceivable loss of translucence upon exposure to a light source is provided. A method of reading data from an optical medium having a sequence of indicators having a binary value assigned thereto comprising radiating light onto a surface of the optical medium having the sequence of binary indicators disposed thereon through a photosensitive material disposed over the sequence and causing the translucence of the photosensitive material to decrease, detecting light reflected from the surface of the optical medium, and interpreting the reflected light as a binary value.

Abstract: A data storage medium (1) has an optical information carrier which comprises a polymer film (11) wound in spiral fashion in a plurality of plies (10), through which information can be read from a preselected polymer film ply (10) and, optionally, written to a preselected polymer film ply (10). A varnish layer (12) set up as an adhesion layer is disposed between adjacent polymer film plies (10).

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 article is disclosed that includes a) a first polycarbonate substrate; b) a second polycarbonate substrate; and c) an adhesive composition disposed between the first polycarbonate substrate and the second polycarbonate substrate such that the first polycarbonate substrate is bonded to said second polycarbonate substrate through the adhesive composition; the adhesive composition includes an adhesive polymer that includes the reaction product of 1) an N-vinyl containing monomer selected from the group consisting of N-vinyl caprolactam, N-vinyl pyrrolidone, and N-vinyl imidazole, and combinations thereof, and 2) an acrylic acid ester monomer of a non-tertiary alcohol having an alkyl group that includes 4 to 20 carbon atoms.

Abstract: According to the present invention, there is provided an optical recording medium including at least an information recording layer and a reflective film in which the reflective film is comprised of an AgCu alloy thin film containing Cu the content of which is greater than or equal to 3.0 [atomic %] and less than or equal to 6.5 [atomic %]. Thus, the optical recording medium can be made inexpensive and weather resistance of the optical recording medium can be improved, thereby making it possible to avoid characteristics of the optical recording medium from being deteriorated even after it has been stored for a long time.

Abstract: There are provided an optical disk and a manufacturing method thereof which can increase its recording capacity, e.g. to 15 GB or higher. This optical disk may comprises an optical disk substrate 3 in which successive pits corresponding to a recording signal are formed, a reflection film 4 formed in this optical disk substrate 3 on its surface that successive pits 2 are formed and a light transmissive layer 5 formed on this reflection film 4. When a recorded signal is read out, i.e. reproduced from the optical disk, a signal recorded as successive pits is read out by irradiating of short-wavelength laser light having a wavelength of 350 nm to 420 nm from the side of the light transmissive layer 5 formed on the surface of the optical disk.

Abstract: A magneto-optical recording medium in a near-field optical storage system is provided. A flying optical head is suspended over the medium by a cushion of gas. The medium includes a magneto-optical recording layer including at least one recording track for magneto-optical recording of information. A tracking feature is associated with the recording track. An upper transparent dielectric layer is provided having an upper surface which is substantially planar over a recordable area of the medium above the recording track and the tracking feature. A reflector layer is positioned below the magneto-optical layer above a base substrate.

Abstract: A multilevel recording method based on a novel principle utilizing a phase change medium. The method comprises the steps of: radiating a recording energy beam against an information recording medium having a recording layer to locally melt the recording layer, the recording layer being adapted to produce a phase change between a crystalline state and an amorphous state upon being radiated with an energy beam; and forming an amorphous mark by cooling during a solidifying process to record information in the medium; wherein the size of the amorphous mark is controlled mainly by a competition between a recrystallization process and an amorphization process during the solidifying process; wherein an intensity of reflected light from a reproducing light beam radiated region is controlled in three or more multiple recording levels according to an optical characteristic difference between a crystalline region and a amorphous region and their areas.

Abstract: An optical information recording medium includes a substrate, and a record layer formed on the substrate. Information is recorded using a laser beam with a wavelength of 380 nm to 430 nm, and refraction index n and attenuation coefficient k of the record layer satisfy a relation of 3.9<n<5.6 and k>0.4 to the wavelength of 380 to 430 nm.

Abstract: An optical recording element having a transparent substrate and on the surface of said substrate, a recording layer, a light reflecting layer is disclosed. The recording layer comprises (i) a metallized azo ether dye having an azo group linking a substituted 3-hydroxypyridine nucleus to a phenyl nucleus wherein the phenyl nucleus has an ether substituent ortho to the azo group and said phenyl nucleus is free of strong electron withdrawing groups and (ii) a cyanine dye. The recording layer also has, when unrecorded a refractive index, at a selected wavelength from 400 to 660 nm, comprising a real part (n) greater than 1.8 and an imaginary part (k) less than 0.2.

Abstract: An optical magnetic recording medium in which reproduction is implemented by transcribing a mark to a reproducing layer based on a magnetic field from a recording layer, includes a reproducing layer, a non-magnetic layer, and a recording layer including a first recording layer and a second recording layer, wherein the reproducing layer, the non-magnetic layer, and the recording layer including the first recording layer and the a second recording layer are stacked in this sequence; the regenerating layer has a property of an easy magnetization in an in-plane direction at room temperature; the first recording layer and the second recording layer each has a property of easy magnetization in a vertical direction to the in-plane direction at room temperature in a single layer; and there is a relation of M2<M1 wherein a composition of a rare-earth metal comprising the first recording layer is defined as M1 (at %) and a composition of a rare-earth metal comprising the second recording layer is defined as M2 (at %

Abstract: An optical recording material which when exposed to actinic radiation produces a change in optical properties in the exposed regions, thereby providing a pattern of intelligence for storing and retrieving information, the recording material comprising: a) a binder; b) a reactant which is capable of undergoing a chemical transformation upon a one electron oxidation, thus causing the change in optical properties in the exposed regions; and c) a sensitizer capable of absorbing actinic radiation to cause an initial one electron oxidation of the reactant.

Abstract: The medium comprises a bilayer stack constituted of an inorganic layer (30) and a semi-reflecting layer (32). The inorganic layer (30) can be deformed under the effect of light radiation (34) passed through the semi-reflecting layer, which lowers the reflection coefficient of the stack.

Abstract: A phase change optical recording medium together with methods for optimally initializing and recording feasible for carrying out read/write/erase operations at multiple recording velocities ranging from 4.8 m/sec to 30 m/sec. Preferably, a recording layer included in the recording medium essentially consists of Ag, In, Sb and Te, with the proportion in atom % of a(Ag): b(In): c(Sb): d(Te), with 0.1≦a≦7, 2≦b ≦10, 64≦c≦92 and 5≦d≦26, provided that a+b+c−d≧97. Initializing the recording medium uses a scanning beam spot from a high power semiconductor laser having energy density input equal to, or less than, 1000 J/m20, scanning speed of the beam spot in the range of 3.5 m/sec to 6.5 m/sec0, and intensity of laser emission equal to, or greater than 330 mW.

Abstract: A phase change optical recording medium includes at least a supporting substrate and a recording layer essentially consisting of AgInSbTe alloy compositions implementing recording and readout steps utilizing changes in reflectivity. The recording medium is characterized by the relation v0≧0.7 vWH, where the critical relative velocity of phase change, v0, defined by the value of v, at which the differential coefficient, −dR(v)/dv, reaches a maximum, when the recording medium moves against an optical unit during the recording steps at a relative velocity, v, ranging from minimum and maximum relative velocities warranted for the recording medium, vWL and vWH, respectively. When the reflectivity is measured with varying erase power PE at the linear relative scanning velocity v0, the reflectivity of the recording layer as a function of erase power, R(PE), preferably has a minimum. The recording layer has an activation energy of deterioration equal to or greater than 1.

Abstract: An optical recording medium having a laminated structure portion(4) including a light-emission layer(3) and a recording layer(2). The light-emission layer(3) is made of a light-emission material excited by reproducing laser light to emit fluorescent light, and the recording layer(2) is made of a material in which at least a refractive index or an absorption coefficient can be changed relative to light emitted from the light-emission layer by recording laser light. The recording layer(2) is disposed to be closer to a side into which reproducing laser light is introduced than the light-emission layer(3). Then, recorded information recorded on the recording layer by the change of the refractive index or the absorption coefficient is read out from the recording layer as the change of intensity of light emitted from the light-emission layer(3) when it is irradiated with reproducing laser light. This optical recording medium can realize an optical memory which can generate a reproduced signal with a high S/N.

Abstract: An optical information recording medium including a substrate, a light absorbing layer which is located overlying the substrate and in which marks are formed to store information and a light reflection layer located overlying the light absorbing layer including a crystal, wherein the optical information recording medium satisfies the relationship, Lt/4≦Lc≦Lm, wherein Lc represents the average particle diameter of the crystal of the light reflection layer, Lm represents the minimum length of the marks, and Lt represents the thickness of the light reflection layer.

Abstract: An optical recording film in the form of a monomolecular layer, includes chemisorptive molecules that are chemically bonded by covalent bonding to a surface of a substrate. The optical recording film has the property that, when irradiated with polarized light, a long axis orientation of the chemisorptive molecules is changed to a direction in which the polarized light is irradiated. A reflective film may be formed on the substrate surface. For the chemisorptive molecules it is possible to use CH3—COO—C6H4—(CH2)6—SiCl3, for example. The molecules undergo a dehydrochlorination with active hydrogen in the base material surface, and are chemically bonded to the base material surface by covalent bonding. Thus, an erasable or a write-once optical recording medium of high density can be provided by chemisorption without necessitating vacuum vapor deposition to form the recording layer.

Abstract: The present disclosure relates to a limited play optical storage media and a method for limiting access to data thereon. This storage media comprises: an optically transparent substrate; a reflective layer; a data storage layer disposed between said substrate and said reflective layer; an oxygen penetrable UV coating disposed on a side of said substrate opposite said data storage layer; and a reactive layer disposed between said UV coating and said substrate, said reactive layer having an initial percent reflectivity of about 50% or greater and a subsequent percent reflectivity of about 45% or less.

Abstract: A multilevel phase change optical recording medium comprises first to N-th (N≧2) phase change optical recording layers, wherein an i-th recording layer and a j-th recording layer, which are two recording layers arbitrarily selected from the first to N-th recording layers, meet the conditions of Ti>Tmi and &tgr;wi<&tgr;xi, and Tj<Tmj or &tgr;wj>&tgr;xj, with respect to a particular recording laser beam selected from recording laser beams having different power levels, where T is the maximum temperature of the recording layer in a recording operation, Tm is the melting point of the recording layer, Tx is the crystallizing temperature of the recording layer, &tgr;w is a time required for the recording layer to be cooled down from Tm to Tx after the laser beam irradiation, and &tgr;x is the crystallizing time of the recording layer.

Abstract: A method for determining the water strain of an article is provided in the present invention by predetermining a maximum tilt range and radius for the article. Further embodiments of the present invention include a storage medium for data and a polymer for use in a storage medium for data where the storage medium comprises a plurality of layers wherein the aforementioned water strain is calculated for the plurality of layers.

Abstract: A magnetic recording medium, which includes a substrate and an amorphous magnetic layer, made of an amorphous magnetic material, for magnetic recording of data, is provided with an underlayer between the substrate and the amorphous magnetic layer, the underlayer being made of amorphous metal element, and having a mean thickness of 10 nm or less. In this manner, movement of magnetic domain walls of the amorphous magnetic layer is effectively limited by minute irregularities on a surface of the underlayer. This realizes a stable formation of a minute recording mark. This realizes recording having a sufficient signal quality, even when the high-density recording is performed by forming such a minute recording mark that a shortest length of the recording mark is less than 100 nm. Moreover, this allows the magnetic recording medium to have a simplified layer structure.

Abstract: An apparatus for retrieving information stored on an optical disk as colored dots, using an array of laser diodes emitting multiple wavelengths. Colored dots store more information than pits and spaces on optical disks because each colored dot represents a multiple-bit code of information rather than a single bit. The optical disk reader directs multiple wavelength diode laser beams to the disk surface. The reflected beams are then separated using an array of dichroic filters, and sent to light sensors. The light sensors identify the intensity of each of the reflected frequencies and determine the wavelength combination being reflected from the optical disk, which corresponds to a multiple-bit code.

Abstract: A shutter for a disk cartridge and the method for producing the shutter are provided wherein the shutter is movably attached to a cartridge and has an opening or aperture for exposing at least a portion of the signal recording surface of the disk. The shutter includes cover plates which open or close the aperture and a connecting plate interconnecting these cover plates. A coating is applied to the surfaces of the cover plates. The coating enhances the reflectivity of the cover plates such that impairment of the appearance and corrosion resulting from flaws and contamination can be prevented.

Abstract: A super-resolution recordable optical disk includes a substrate and forms sequentially on the substrate an under dielectric layer, a mask layer, an interface layer, an organic dye layer, an isolation layer, and a protection layer. A laser beam is projected into the organic dye layer through the substrate to record signals. And a super-resolution recordable optical disk for high numerical apertures also is provided that includes a substrate and forms sequentially on the substrate an organic dye layer, an interface layer, a mask layer an under dielectric layer, and a thin polycarbonate layer. A laser beam is projected into the organic dye layer through the thin polycarbonate layer to record signals.

Abstract: In an apparatus for fabricating a carbon coating, an object such as a magnetic recording 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: Method for manufacturing an optically readable digital storage disk having an arbitrary edge contour from a CD-R disk blank, as well as a CD-R disk blank suitable for the manufacture of a storage disk, starts with a blank having a plastic disk that is provided with a reflective layer on the side opposite a scanning side. The reflective layer, which is connected with the plastic disk along a first line, is welded with the plastic disk along an arbitrarily shaped second line that is closed on itself. Afterwards, the storage disk is cut from the CD-R disk blank along a third line that corresponds to the edge contour.

Abstract: Metallized azo thioether dyes having an azo group linking a substituted 3-hydroxypyridine nucleus to a phenyl nucleus are disclosed. The phenyl nucleus has an thioether substituent ortho to the azo group but does not have electron withdrawing substituents on the phenyl nucleus. The dyes are useful in optical recording elements.

Abstract: The present invention provides a write-once optical information recording medium that can achieve a high reflectance and favorable recording and reproducing characteristics such that a high C/N ratio and high sensitivity even when information is recorded/reproduced with high density. This medium includes a transparent substrate and at least one information layer formed on the substrate. The information layer includes a recording layer made of a material including Te, O and M, where M is at least one element selected from the group consisting of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Sb, Hf, Ta, W, Re, Os, Ir, Pt, Au and Bi. A reflectance with respect to a light beam incident from the side of the transparent substrate after recording information on the recording layer is lower than a reflectance before recording.

Abstract: A dielectric part 4 comprising a nitride layer 7 and an oxide layer 8, laid one upon the other, is formed on a data-recording layer 3. A light-transmitting layer 5 is boned with adhesive to the dielectric part 4. Since the dielectric part 4 is interposed between the data-recording layer 3 and the light-transmitting layer 5, the organic material of the data-recording layer 3 does not diffuse into the adhesive that bonds the light-emitting layer to the dielectric layer 4. Additionally, the data-recording layer 3 is not deteriorated due to the oxygen plasma generated during the process of forming the oxide layer 8, because the oxide layer 8 is provided on the nitride layer. Since the nitride layer 7 has a thickness of 10 nm or less, it does not influence optical enhancement effect.

Abstract: In a phase change optical recording medium in which writing, reading and/or erasing of information is conducted by utilizing change of phase of a recording layer by irradiation with light, the recording layer is made of a material containing oxygen in an amount of 1 to 30 atomic %; or the recording medium comprises an additional transparent dielectric layer 1 to 10 nm thick between the recording layer and the underlying transparent dielectric layer and the inserted transparent dielectric layer in contact with the recording layer comprising oxygen in a molar ratio greater than a molar ratio of oxygen in the underlying transparent dielectric layer; or the transparent dielectric layer underlying and in contact with the recording layer comprises oxygen in a molar ratio greater than a molar ratio of oxygen in the other transparent dielectric layer.

Abstract: An article is disclosed that includes:

Abstract: This invention relates to optical discs that preferably include multiple data layers and are configured to receive analytes which can be detected by an optical disc reader. The optical disc reader may be a standard optical disc reader or an optical disc reader modified therefrom. The optical disc may include (1) a first layer including optically readable structures which have encoded tracking information, and speed information enabling an optical disc reader to rotate the optical disc at a speed that is determinable from the speed information; (2) a second layer including optically readable structures; and (3) an analyte section capable of receiving an analyte which can be read by the optical disc reader.

Abstract: A recording medium includes a first substance and a second substance at least in which the first and second substances undergo an oxidation-reduction reaction when an external energy is applied, thereby recording information by varying the optical characteristics. In the recording medium, the reaction of the first and second substances is suppressed, reaction which degrades the recording characteristics other than the case where the recording medium is subjected to recording. In an optical disk 100 (i.e., the recording medium), a WO3 film 2 (i.e., a second substance), a C film 3 (i.e., a third substance) and an Sn-10 atomic % Sr film 4 (i.e., a first substance) are formed successively on a substrate 1. When the recording medium is irradiated with a recording laser beam as an external energy, the WO3 forming the film 2 is reduced to WO2.

Abstract: An optical data recording medium includes a transparent substrate, a thin film layer formed on the transparent substrate and a protective film which is mainly comprised of a resin and formed on the thin film layer for protecting the thin film layer. The thin film layer is a single layered or multilayered film including at least any one of a dielectric film, a recording film and a reflective film, and at least either one of a linear expansion coefficient and a Young's modulus of the protective film is greater than that of the transparent substrate, the linear expansion coefficient of the protective film is greater than 7.0×10−5 (1/° C.) and smaller than 5.0×10−4 (1/° C.).

Abstract: An optical data recording medium includes a transparent substrate, a thin film layer formed on the transparent substrate and a protective film which is mainly comprised of a resin and formed on the thin film layer for protecting the thin film layer. The thin film layer is a single layered or multilayered film including at least any one of a dielectric film, a recording film and a reflective film, and an expansion coefficient under humidity (ratio of expansion (1/%) where a difference of relative humidity (vapor content/saturated vapor amount at 25° C.) is increased by 1%) of the protective film is greater than that of the transparent substrate and smaller than 1.7×10−4(1/%).

Abstract: In a magneto-optical recording medium comprising a recording layer and a reproducing layer, a transfer layer and a magnetic shielding layer are successively formed between the recording layer and the reproducing layer respectively. The reproducing layer is prepared from Gd33(Fe70Co30)67 changing from an in-plane magnetization film to a perpendicular magnetization film at 150° C., for example. The transfer layer is prepared from Gd28(Fe90Co10)72 changing from an in-plane magnetization film to a perpendicular magnetization film at 50° C., for example. The magnetic shielding layer is prepared from SiN, for example. The recording layer is prepared from Tb20(Fe90Co10)80 whose saturation magnetization is maximized around the transition temperature of 50° C. of the transfer layer. A signal can be directly recorded in the recording layer with no magnetic influence from the reproducing layer.

Abstract: An over-writable magneto-optical recording medium in which a recording section has at least a first dielectric layer, a first recording layer, a second recording layer, and a second dielectric layer formed sequentially and a reflective layer and a protective layer formed on the recording section. A groove is formed on the transparent substrate along a recording track, both sidewalls of the groove are respectively formed into an independent wobbling shape, a relationship of 0.470≦W/Ø≦0.610 is effectuated when assuming the width of the groove as W, and a relationship of 0.120≦D(&lgr;/n)≦0.142 is effectuated when assuming the depth of the groove as D, and the angle ⊖ between wall faces of the groove is kept at 150°±10°.

Abstract: A high-density optical disk includes reflective layers respectively formed at both information-recorded surfaces of a first substrate, and semitransparent layers respectively formed at one information-recorded surface of each of second and third substrates. The second and third substrates are respectively bonded at both sides of the first substrate.