Abstract: An object of the invention is to provide an optical recording medium and a method for producing an optical recording medium that enable to improve the quality of a servo signal and a reproduction signal. The optical recording medium satisfies: t3?t4?1 ?m, t4?t2?1 ?m, t2?10 ?m, and t1?(t2+t3+t4)?1 ?m, where t1 is a thickness between a surface of the optical recording medium, and the first information recording surface, t2 is a thickness between the first optical recording surface and the second information recording surface, t3 is a thickness between the second optical recording surface and the third information recording surface, and t4 is a thickness between the third optical recording surface and the fourth information recording surface.

Abstract: There is provided a read-only optical information recording medium including a reflective film which has high reflectivity, and is superior in environment resistance at the time of being kept in a high-temperature, high humidity environment as well as light resistance at the time of being kept in a high-intensity light irradiation environment and repeating reproduction durability against a repeating reproduction test. In a read-only optical information recording medium in which at least one reflective film and at least one light transmissive layer are laminated in order on a substrate, the reflective film is made of a Ag-base alloy including 0.01 to 1.0 at % of Bi and 0.1 to 13.0 at % of Cu.

Abstract: An optical recording medium includes a first half-disc and a second half-disc. The first half-disc includes a substrate and an information layer (including a reflective layer) formed on a first side of the substrate. The second half-disc is bonded by an adhesive to a second side of the substrate of the first half-disc. In addition, a cover layer is formed over the first reflective layer. The cover layer has a thickness of approximately 0.1 mm. The substrate of the first half-disc has a thickness in a range of 0.3 mm to 1.0 mm. The first and second half-discs together have a combined thickness in a range of 0.8 mm to 1.3 mm.

Abstract: Disclosed is a composition capable of imparting high hardness, abrasion resistance, excellent contamination resistance and durability of such contamination resistance even in the form of a thin film. Specifically disclosed is a composition including an organic polymer containing 5-30% by mass of a radically polymerizable monomer with a perfluoroalkyl group, 0.01-5% by mass of ?,?-dimercaptopolysiloxane, 5-40% by mass of a radically polymerizable monomer with a cationically photopolymerizable epoxy group and 25-75% by mass of another radically polymerizable monomer which is copolymerizable with the aforementioned substances. The organic polymer has a structure corresponding to a radically polymerized copolymer of the monomer mixture wherein the molar ratio of the mercapto group to the epoxy group is 0.0001-0.025 and/or a structure obtained by reacting a (meth)acrylic acid with the epoxy group of the radically polymerized copolymer.

Abstract: An optical information medium measurement method of the present invention, for measuring a degree of modulation in an optical information medium of a multilayered structure having a plurality of information layers, includes a first step of measuring the modulation degree of each layer of the optical information medium, by use of a measurement optical system, a second step of obtaining a thickness between layers of the optical information medium, a third step of obtaining a reflectance of each layer of the optical information medium, and a fourth step of converting the modulation degree of each layer, the modulation degree being measured in the first step, into a modulation degree at a reference optical system differing from the measurement optical system, based on a value indicative of the thickness between layers, the thickness being obtained in the second step, and a value indicative of the reflectance of each layer, the reflectance being obtained in the third step.

Abstract: The present invention relates to an Ag alloy film. Particularly, it is preferably used as a reflective film or semi-transmissive reflective film for an optical information recording medium having high thermal conductivity/high reflectance/high durability in the field of optical information recording media, an electromagnetic-shielding film excellent in Ag aggregation resistance, and an optical reflective film on the back of a reflection type liquid crystal display device, or the like. The Ag alloy film of the present invention comprises an Ag base alloy containing Bi and/or Sb in a total amount of 0.005 to 10% (in terms of at %). Further, the present invention relates to a sputtering target used for the deposition of such an Ag alloy film.

Abstract: An optical data store is specified, having a data storage layer with a non-toxic and biodegradable polymer as light-sensitive storage medium which has photo-inducible anisotropy, for the induction of which a threshold value of the optical intensity has to be exceeded. The light-sensitive material is preferably bacteriorhodopsin which, by way of example, is immobilized in a manner embedded in a suitable matrix material or, if appropriate, in a crosslinked manner. The storage medium permits a high storage density and can be applied in a simple manner, for instance by printing onto a substrate.

Abstract: A recording layer including a novel dye for a high density optical recording medium, employing short wavelength laser source with a wavelength not longer than 530 nm for recording high density information and reproduction/playback of the high density information recordings, is provided.

Abstract: A production method for an optical disc master includes the steps of: preparing a substrate; forming an intermediate layer having a predetermined thickness on the substrate; forming an inorganic resist layer having a thickness on the intermediate layer, a ratio of the thickness of the intermediate layer to the thickness of the inorganic resist layer being in a range between 0.8:1 and 1.5:1; irradiating the inorganic resist layer with a laser beam to selectively expose the inorganic resist layer; and developing the selectively exposed inorganic resist layer.

Abstract: A write-once optical recording medium is described, which in addition to the write-once properties also has rewritable properties. The optical recording medium has a recording layer with at least a first recording sublayer and a second recording sublayer for recording information marks by alloying material of the at least first and second recording layers. The materials of the at least first and second recording sublayers are chosen such that the alloyed material is a phase-change material adapted for recording additional data as phase changes of the alloyed material.

Abstract: The present invention provides an optical recording material allows for obtaining excellent recording signal properties even at high-speed recording and is excellent in durability in both a single-sided single layer optical recording medium and a single-sided two-layer optical recording medium having a first recording layer and a second recording layer. The optical recording material contains a cyanine compound having a specific structure and a squarylium compound as dyes for optical recording layers.

Abstract: The present invention relates to a block copolymer comprising: at least a bloc A having a Tg>?60° C., preferably a Tg>0° C., and most preferably >60°B comprising at least one photoactive monomer having a photoisomerable chromophore. The photoactive monomer having the formula (I), wherein X is H or CH3—; G is —O—C(?O)—, —C(?O)—O—, a phenyl group, substituted or un-substituted, or —NR—C(?O)—, NR being linked to L and R is H or a C1-C10 alkyl group; L is a spacer group; CR is a photoisomerable chromophore. The block copolymer provides a 3D optical memory. The invention also relates to this optical 3D memory.

Abstract: An information recording medium comprising a substrate (1), a recording layer (2) formed on the substrate in order to record information, a color filter (4) formed on the substrate, and a thermal reflectance variation layer (3) formed on the substrate in order to vary light reflectance by heat incident to irradiation of light and to reflect visible light entering from one side of the substrate through a color filter. High precision color writing or color label writing can be carried out on an information recording medium such as DVD and BD where a label can be written on the surface by irradiating light.

Abstract: A first substrate is formed to include a surface on which a first record layer is formed, and which includes an inner circumferential portion on which a ring-shaped member is provided. Ultraviolet curing resin is dropped onto part of the surface which is located inward of the ring-shaped member, and the first substrate is then spun to coat the first record layer with the ultraviolet curing resin. Furthermore, a second substrate is formed to include a surface on which a second record layer is formed, and the second substrate is spun to coat the second record layer with ultraviolet curing resin. Then, the first and second record layers are made to face each other, and the first and second substrates are bonded to each other by the ultraviolet curing resin.

Abstract: A silver alloy reflective film is used in an optical information recording medium and contains Ag as a main component, a total of 1 to 10 atomic percent of at least one selected from Nd, Gd, Y, Sm, La, and Ce, and a total of 2 to 10 atomic percent of at least one selected from Li, Mg, Al, Zn, Cu, Pt, Au, Pd, Ru, and Rh. The reflective film preferably further contains 0.01 to 3 atomic percent of at least one of Bi and Sb and/or 2 to 10 atomic percent of at least one selected from In, Sn, and Pb. An optical information recording medium includes the silver alloy reflective film. A silver alloy sputtering target has the same composition as the silver alloy reflective film.

Abstract: Optical information media containing a magnesium metal layer and a reactive material layer are disclosed. The magnesium metal can react directly with the reactive material layer, or with a chemical evolved from the reactive material layer after application of energy from a source such as a laser.

Abstract: An optical recording medium is provided. The optical recording medium includes a first recording layer and a second recording layer. The first recording layer includes a compound in the form of M(1?x)Ox, where M is one of Si, Zn or Sn, and X is approximately 0.001 to 0.1.

Abstract: An optical recording medium is provided. The optical recording medium includes a first recording layer and a second recording layer. The second recording layer includes a compound in the form of (CuXM(1-X))YO(1-Y), where M is one of Sn, Si, Zn, Al, Mg, Ge, Sb or Te, and X is approximately 0.5 to 1, and Y is approximately 0.001 to 0.1.

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: Cyanine compounds represented by the general formula (I) which exhibit decomposition behavior suitable for the optical recording material to be used in optical recording layers of optical recording media for high-speed recording: (I) wherein A and B are each an optionally substituted benzene or naphthalene ring; X is O, S, Se, CR3R4, or NY; at least either of R1 and R2 is a group represented by the general formula (II) or (III) and when only either is a group represented thereby, the other is an organic group having 1 to 30 carbon atoms; R3 and R4 are each an organic group having 1 to 30 carbon atoms; Y is hydrogen or an organic group having 1 to 30 carbon atoms; at least either of Y1 and Y2 is a group represented by the general formula (IV) and when only either is a group represented thereby, the other is hydrogen or an organic group having 1 to 30 carbon atoms; Z is hydrogen, halogeno, or cyano; Anm? is an m-valent anion; m is an integer of 1 or 2; and p is a coefficient capable of keeping the electric char

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: There is provided an optical information recording medium which can meet opposite requirements of enhancement in ink absorption and fixation properties of an image forming layer and suppression and prevention of solid attachment of a printed portion, which has excellent printability to obtain high image quality and an excellent holding property of the printed portion, and which little makes the solid attachment on the printed surface layer occur. At this time, a thick layer can be formed even by the use of a coating solution for the image forming layer. The optical information recording medium has the image forming layer on various layers stacked on a surface of a light transmitting substrate and optically readable signals are recorded or can be recorded therein by the use of laser beams incident on the other surface of the light transmitting substrate, wherein the image forming layer includes an ink absorbing porous layer made of a resin layer containing vapor inorganic particles.

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: An information recording medium comprises a substrate, a second recording layer, a second light transmitting layer, a first recording layer for recording different information from that to be recorded in the second recording layer, and a first light transmitting layer. The second recording layer is formed with a continuous second microscopic pattern of grooves. The first recording layer is formed with a continuous first microscopic pattern of grooves that is different from the second microscopic pattern. Both sidewalls of raised portions of the first and second microscopic patterns are formed with wobbling so as to be parallel with each other. Auxiliary information and a reference clock is recorded on these sidewalls alternately and continuously.

Abstract: In an information recording medium on and from which information is recorded and reproduced by applying light or electric energy, a recording layer which generates reversible phase change is formed so as to include a material containing Ge, Bi, Te and an element “M” which material is expressed with (GeTe)x[(M2Te3)y(Bi2Te3)1-y]100-x (mol %) wherein “M” represents at least one element selected from Al, Ga and In, and “x” and “y” satisfy 80?x<100 and 0<y?0.9, whereby the medium is obtained which ensures a high erasability and an excellent archival characteristic at a high linear velocity and in a wide range of linear velocities.

Abstract: Optical information media having a support substrate and an inorganic nanomaterial data layer are disclosed. The data layer provides enhanced stability and optical performance as compared to conventional data layers.

Abstract: The present invention has been completed in view of such situation, and an object of the present invention is to find a Ag based alloy which exhibits high cohesion resistance, high light resistance, high heat resistance, high reflectivity, high transmissivity, low absorptivity, and high thermal conductivity of the level which had not been realized by the pure Ag or by the conventional Ag alloys, and on the bases of such alloy, to provide a semi-reflective film and a reflective film for an optical information recording medium provided with excellent writing/reading properties and long term reliability; sputtering target for an optical information recording medium used in depositing such semi-reflective film and the reflective film; and an optical information recording medium provided with such semi-reflective film or the reflective film. A semi-reflective film or reflective film for an optical information recording medium comprising a Ag based alloy, wherein the Ag based alloy comprises 0.005 to 0.

Abstract: An information recording medium comprising: a first recording layer in which a first recording track path to record therein record information is formed; and a second recording layer which is laminated on said first recording layer and in which a second recording tack path to record therein the record information is formed in a direction opposite to the first recording track path, in one recording layer of said first and second recording layers, a predetermined area in which focus leading of laser light is performed reflecting the laser light, in the other recording layer of said first and second recording layers, a facing area which faces the predetermined area not reflecting the laser light.

Abstract: A low-cost information recording medium is provided by which good recording quality can be obtained even when high-density is made using a blue laser. The information recording medium on or from which information can be recorded and reproduced by irradiating the recording layer with laser beam is configured so that the content of O atoms is 20 atom % or more but 70 atom % or less, the content of M atoms is 1 atom % or more but 50 atom % or less and the content of Sb atoms is 10 atom % or more but 70 atom % or less when total number of the Sb atoms, the O atoms and the M atoms contained in the recording layer is 100 atom % and the recording layer does not contain Au, Pt and Pd.

Abstract: A high density information storage medium includes a recording layer in which information is stored; a thin metal film placed on the recording layer and having a structure in which nano-apertures having a size of several nanometers to several hundred nanometers are defined at regular intervals; and a protective layer placed on the thin metal film. As light irradiated from above the protective layer passes through the nano-apertures, physical characteristics of the recording layer are changed, whereby information is stored.

Abstract: An optical data store is specified, having a data storage layer with a non-toxic and biodegradable polymer as light-sensitive storage medium which has photo-inducible anisotropy, for the induction of which a threshold value of the optical intensity has to be exceeded. The light-sensitive material is preferably bacteriorhodopsin which, by way of example, is immobilized in a manner embedded in a suitable matrix material or, if appropriate, in a crosslinked manner. The storage medium permits a high storage density and can be applied in a simple manner, for instance by printing onto a substrate.

Abstract: Disclosed is an optical recording medium which can increase the gloss of a print receptive layer provided on a level surface and can provide a high quality print. An optical recording medium (200) comprises a record-reproducing layer (10) which is a substrate-incident medium and a print receptive layer (20) which can be printed with an ink and is provided on the surface opposite to the surface of the record-reproducing layer (10) which receives the irradiation with light. The print receptive layer (20) comprises a filler-containing layer (22) which contains a hydrophilic resin and an organic or inorganic filler as main ingredients and a non-filler-containing layer (21) which is laminated on the filler-containing layer (22) and contains no organic or inorganic filler.

Abstract: Various embodiments and methods relating to a storage disc having writable layer, a reflective layer and a compressive layer are disclosed.

Abstract: An optical recording medium 1 includes a support substrate 2, an information layer 3 formed on one of the surfaces of the support substrate 2, a first resin layer 4 formed on the information layer 3 and having a thickness of 30 to 200 ?m, a moisture-proof layer 5 formed on the other surface of the support substrate 2, a second resin layer 6 formed on the moisture-proof layer 5 and having a thickness of 30 to 200 ?m, and a label layer 7 formed on the second resin layer 6, and has such a structure that a laser beam is irradiated through the first resin layer 4. The second resin layer 6 contains 0.5 to 2.8 mass part of a silicon antifoaming agent with respect to 100 mass part of an ultraviolet curing resin, and is formed by a screen printing method.

Abstract: A silver alloy reflective film is used in an optical information recording medium and contains silver as a main component, a total of 1 to 10 atomic percent of at least one rare-earth element, and a total of 1 to 15 atomic percent of at least one selected from In, Sn, Al, and Mg, in which the total content of the at least one rare-earth element and the at least one selected from In, Sn, Al, and Mg is 5 atomic percent or more. The silver alloy reflective film preferably further contains 0.01 to 3 atomic percent of at least one of Bi and Sb. A silver alloy sputtering target has the same composition as the silver alloy reflective film.

Abstract: A Ag alloy reflective film for an optical information recording medium contains Ag as a main component, and at least one selected from Nd, Sn, Gd and In in a total amount of more than 3.0 atomic percent and less than or equal to 10 atomic percent. The reflective film can further contain 0.01 to 3 atomic percent of at least one of Bi and Sb, and/or can further contain comprising 20 atomic percent or less of at least one of Mn, Cu, La and Zn. An optical information recording medium includes the Ag alloy reflective film and can be subjected to laser marking. A Ag alloy sputtering target has a similar composition to that of the Ag alloy reflective film.

Abstract: A rewritable phase change optical recording medium includes a substrate, a dielectric layer deposited on a surface of the substrate, and an optical recording layer deposited on the dielectric layer, wherein the dielectric layer may be omitted. The optical recording layer contains a composition of GexSb100-x-y-zMyEz, wherein 0.5?x?14.5; 0.5?y?14.5; 0?z?14.5; and M and E are different and are selected from the group consisting of Te, Cr, V, Ti, Ag, Sn, Si, Bi, Se, Al, Au, Ni, Fe, Cu, Mn, O, Ga, Cd, In, Pb and Hf, wherein M is not Te, when x is zero; and E is not Sn, when M is Te. The optical recording composition has a small crystal grain, a high ratio of reflectivity of the amorphous phase to that of the crystalline phase thereof, and a high crystallization rate, so that a blue light laser can be used to write/erase the recording medium.

Abstract: An optical recording medium includes: a substrate; an information signal layer provided on the substrate; and a protective layer provided on the information signal layer. The information signal layer is provided with a reflecting layer, a recording layer provided on the reflecting layer and first, second and third dielectric layers laminated successively on the recording layer. Refractive indexes of the first, second and third dielectric layers are different from each other between the adjacent dielectric layers to each other. Among the first, second and third dielectric layers, the dielectric layer having the highest refractive index contains, as a main component, at least one member selected from the group consisting of titanium oxide, niobium oxide and a mixture of zinc sulfide and silicon oxide. The dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm.

Abstract: An optical recording material for use in an optical recording layer of an optical recording medium comprising the optical recording layer provided on a substrate, the optical recording material comprising a cyanine compound represented by general formula (I): wherein rings A and B each represent a substituted or unsubstituted benzene or naphthalene ring; X represents O, S, Se, CR3R4 or NY; one of R1 and R2 represents a specific group of formula (II) or (III), with the other representing a C1 to C30 organic group; R3 and R4 each represent a C1 to C30 organic group; Y, Y1, and Y2 each represent a hydrogen atom or a C1 to C30 organic group; Z represents a hydrogen atom, a halogen atom or a cyano group; Anm?1 represents an m-valent anion; m represents an integer of 1 or 2; and p represents a coefficient maintaining charge neutrality.

Abstract: A method of minimizing distortion in a glass sheet manufacturing process wherein the stress in a parent sheet of glass is measured along each edge of the sheet. The stress data is then used to develop a distortion predictor for predicting the in-plane distortion which sub-sheets of the parent sheet are likely to exhibit when the parent sheet is cut into pre-determined sizes. The in-plane distortion may be predicted based on criteria established by the glass manufacturer, or supplied by an original equipment manufacturer (OEM).

Abstract: A silver-based alloy thin film is provided for the semi-reflective coating layer of optical discs. Alloy additions to silver include zinc, lithium, germanium, indium, tin, aluminum, and silicon. These alloys have moderate to high reflectivity and reasonable corrosion resistance in the ambient environment.

Abstract: The present invention relates to pyridinone based azo dyes and/or of anionic azo metal complex dye salts made thereof with cationic basic yellow dyes, which are characterized by an unsaturated bond in beta-position to the endocyclic N atom of the pyridinone, and to their use in optical layers for optical data recording, preferably for optical data recording using a laser with a wavelength up to 450 nm. The invention further relates to a write once read many (WORM) type optical data recording medium capable of recording and reproducing information with radiation of blue laser, which employs pyridinone based azo dyes and/or anionic azo metal complex dye salts made thereof with cationic basic yellow dyes, which are characterized by an unsaturated bond in beta-position to the endocyclic N atom of the pyridinone, in the optical layer.

Abstract: A sputtering target for optical media is mainly composed of Al and contains 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag. An optical medium 100 comprises a substrate 10 and reflective layers 20A, 20B provided on the substrate 10. Each of the reflective layers 20A, 20B has a composition, mainly composed of Al, containing 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag.

Abstract: An optical recording medium which includes three or more information layers and has a higher stack density of information layers than before in the direction of thickness while reducing crosstalk during reproduction, and a method for reading the optical recording medium are provided. The optical recording medium has a three-layer structure which includes a substrate, a first information layer, a first spacer layer, a second information layer, a second spacer layer, a third information layer, and a cover layer thinner than the substrate, with these layers being stacked in that order over the substrate, wherein the following Equation (I) is satisfied: (R2×R3×R2)/R1?0.0032 ??Equation (I) where R1 is the reflectivity of the first information layer, R2 is the reflectivity of the second information layer, and R3 is the reflectivity of the third information layer, and the first spacer layer and the second spacer layer are equal to each other in thickness.

Abstract: A WORM-type recording layer in an optical information recording medium contains at least one azo-metal complex dye derived from a metal ion and a compound represented by the following general formula (1-1) or (1-2): wherein Q represents a carbocyclic group or a heterocyclic group, and R6 to R8 independently represent a hydrogen atom or a substituent. The compound represented by the general formula (1-1) or (1-2) has a dissociative hydrogen atom in Q, and the dissociative hydrogen atom in Q and the hydrogen atom in the —NH— group marked with asterisk * are eliminated from the compound, so that the residue is bonded to the metal ion to generate the azo-metal complex dye. The azo-metal complex dye may contain a component other than the metal ion and the compound represented by the general formula (1-1) or (1-2).

Abstract: An optical information recording medium includes a substrate formed in a concave-convex state by providing pits or grooves corresponding to recorded information, used for optically reproducing the information by irradiation of a light beam, and may also include a recording layer. The optical information recording medium includes a temperature responsive layer 21 whose reflectance and/or transmittance for the light beam changes with an increase in temperature caused by the irradiation of a light beam and a light absorption layer 22. With such an arrangement, the present invention provides an optical information recording medium enabling secure and highly accurate readout of information recorded with high density, a recording method and a readout method using the same, a readout device, and a recording device.

Abstract: An information recording medium with high recording sensitivity and superior repeat overwriting capability. The information recording medium (15) comprising at least recording layer (104) recording and/or reproducing information through irradiation with a laser beam or application of an electric current, and second dielectric layer (106) on substrate (14), wherein the second dielectric layer (106) comprises M1 (provided that M1 is at least one element selected from Sc, Y, La, Gd, Dy and Yb) and O.

Abstract: A dye or dyes are selected, which are capable of absorbing a laser beam with a wavelength of 350 to 500 nm and are capable of recording sub-information using a laser beam with a wavelength of 640 to 680 nm or 750 to 830 nm. An optical information recording medium including the optical recording layer records sub-information (BCA information) of a type different from that of main information (data information) in a sub-information region (a BCA recording region) different from a main information area (a data area) using a laser beam.