Abstract: Simple design of a multilayer optical recording medium is achieved while suppressing interlayer crosstalk and confocal crosstalk in the multilayer optical recording medium. Simple recording and reading control by a recording and reading unit is also achieved. The multilayer optical recording medium includes at least three or more recording and reading layers deposited one above the other with intermediate layers interposed therebetween, and information can be read by light irradiation from the layers. The intermediate layers have film thicknesses of two types or less, and all the recording and reading layers except the recording and reading layer farthest from a light incident surface have substantially the same optical constant.

Abstract: The multilayer optical recording medium with at least four or more recording and reading layers disposed one above the other has at least two or more recording and reading layer groups each including the recording and reading layers successively disposed one above the other. In adjacent recording and reading layer groups with an intermediate layer interposed therebetween, a recording and reading layer nearest a front side in the recording and reading layer group nearer a back side is higher than the higher value of the reflectances in a stacked state of two recording and reading layers nearest the back side in the recording and reading layer group nearer the front side.

Abstract: The multilayer optical recording medium with six or more recording and reading layers disposed one above the other has at least two or more recording and reading layer groups. The recording and reading layer groups each include a plurality of recording and reading layers successively disposed one above the other. The reflectance of each of the recording and reading layers in a stacked state decreases in the order from a front side near a light incident surface toward a back side far from the light incident surface. A recording and reading layer nearest the front side among the recording and reading layers in the recording and reading layer group nearer the back side has a reflectance in a stacked state higher than that of a recording and reading layer nearest the back side among the recording and reading layers in the recording and reading layer group nearer the front side.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, that is, storage stability, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory record using not only a green laser but also a blue laser. A hologram recording material comprising: a metal oxide matrix; and a photopolymerizable compound which has at least one (meth)acrylamide group as a photo-reactive group, and has a polyalkylene glycol unit represented by the following formula: —(RO)n— wherein R represents a lower alkylene group, and n represents the number of repeating units of alkylene oxide.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide containing at least Si and Zr as metals, wherein an aromatic carboxylic acid compound is coordinated to Zr; and a photopolymerizable compound. The aromatic carboxylic acid compound is, for example, toluic acid. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: Efficient recording and reading are achieved in an optical recording medium including servo layers and recording and reading layers. The optical recording medium includes: a first servo layer having a projection and a depression for tracking control that are formed in a first spiral direction; a second servo layer having a projection and a depression for tracking control that are formed in a second spiral direction opposite to the first spiral direction; and a plurality of recording and reading layers having a flat structure with no projection and depression for tracking control. Information is recorded on each of the plurality of recording and reading layers while tracking control is performed using the first servo layer or the second servo layer.

Abstract: An optical recording medium including recording and reading layers and a servo layer increases the recording capacity thereof. In the optical recording medium including the plurality of recording and reading layers and the servo layer, the servo layer has a groove and a land that can be used to perform tracking control with a long-wavelength servo beam. Information is recorded on the recording and reading layers with a recording and reading beam having a wavelength shorter than the wavelength of the servo beam. Recording marks are formed on the recording and reading layers while both the groove and land are tracked.

Abstract: In a multilayer optical recording medium, it is an object to suppress generation of crosstalk while reducing an interlayer distance of recording and reading layers. In an optical recording medium including three or more recording and reading layers, a first distance, and a second distance greater than the first distance by 3 ?m or more are alternately defined as interlayer distances of recording and reading layers.

Abstract: An optical recording and reading method is provided in which the information necessary for recording and reading layers is quickly acquired to reduce the seek time during reading and recording. The optical recording and reading method is used for an optical recording medium that includes a plurality of recording and reading layers and a servo layer. Information is recorded on or read from the recording and reading layers by irradiating them with a recording and reading beam while the servo layer is irradiated with a servo beam to perform tracking control. When information is recorded on the recording and reading layers, control information necessary for subsequent recording and reading to be performed on the recording and reading layers is recorded on the servo layer 18. When the subsequent recording or reading is performed, the control information on the servo layer is consulted, and then the recording or reading is performed on the recording and reading layers.

Abstract: A series of optical recording media is provided to reduce a burden on an optical pickup by introducing a standardized idea among a plurality of optical recording media. In the series of optical recording media, optical recording media are of a plurality of types, each optical recording medium including a plurality of planar recording and reading layers with no projections and depressions for tracking control, and a servo layer with projections and depressions for tracking control. The plurality of optical recording media have different numbers of stacked recording and reading layers, and the positions of the servo layers with respect to the corresponding light incident surfaces are standardized among the plurality of optical recording media.

Abstract: A series of optical recording media is provided to reduce a burden on an optical pickup by introducing a standardized idea among a plurality of optical recording media. In the series of optical recording media, optical recording media are of a plurality of types, each optical recording medium including a plurality of planar recording and reading layers with no projections and depressions for tracking control, and a servo layer with projections and depressions for tracking control. The plurality of optical recording media have different numbers of stacked recording and reading layers. The plurality of optical recording media have different numbers of stacked recording and reading layers. The positions of the servo layers from the corresponding light incident surfaces are standardized among the plurality of optical recording media. The position of at least one recording and reading layer from the corresponding light incident surface is standardized among the plurality of optical recording media.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide containing at least Si and Zr as metals wherein a ?-dicarbonyl compound is coordinated to Zr; and a photopolymerizable compound, wherein a mole ratio of the ?-dicarbonyl compound to the Zr atom (?-dicarbonyl compound/Zr ratio) is 2/1 or more and 3/1 or less, and a mole ratio of the Si atom to the Zr atom (Si/Zr ratio) is more than 1/1 and 1.15/1 or less in the metal oxide. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: The present invention provides a hologram recording medium which can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimension change (low shrinkage) and high multiplicity in holographic memory record using a blue laser. A hologram recording medium (11) comprising at least a hologram recording material layer, wherein the hologram recording material layer (21) comprises at least: an organometallic compound having at least a Ti—O bond, and a photopolymerizable compound; and said medium has a light transmittance is 50% or more at a wavelength of 405 nm, or a light reflectance is 25% or more at a wavelength of 405 nm. The organometallic compound is favorably obtained by subjecting an alkoxide compound of the corresponding metal(s) to hydrolysis and polymerization reaction in an organic solvent which neither contains cyclic ether skeleton nor carbonyl oxygen.

Abstract: The present invention provides a process for producing a titanium-containing metal oxide the coloration of which is decreased; a hologram recording material suitable for holographic memory recording using a blue laser, wherein a titanium-containing metal oxide the coloration of which is decreased is used as a metal oxide matrix; a process for producing the same; and a hologram recording medium. A process for producing a metal oxide comprising at least Ti as a metal element, the process comprising: providing an alkoxide compound of Ti to which a glycol other than any geminal diol and any vicinal diol is coordinated; hydrolyzing the alkoxide compound of Ti to which the glycol is coordinated, thereby yielding a precursor of a metal oxide; and advancing polycondensation reaction of the metal oxide precursor, thereby forming the metal oxide.

Abstract: A reflection type hologram recording optical system is provided which implements a method for forming a light reflection hologram having uniform reflectivity. The method includes: focusing a first laser beam through one of a pair of objective lenses, the first beam satisfying the condition given by, 4?n/(NA)2<D, where ? (?m) is the wavelength of the first laser beam, NA is the numerical aperture of the pair of objective lenses, n is the average refractive index of the optical recording medium, and D (?m) is the thickness of the medium; allowing the first laser beam to interfere with a second laser beam within the optical recording medium, the second laser beam being focused through the other opposing objective lens; and allowing the optical recording medium and a flux of the laser beams to be displaced relative to each other, thereby forming a light reflection hologram having uniform reflectivity.

Abstract: A hologram recording medium includes a glass substrate and an information recording layer supported on the glass substrate. The information recording layer is formed of a photosensitive material having a dynamic storage elastic modulus of 1.0×105 Pa or more as measured at 80° C. and a measurement frequency of 1 Hz after interference exposure or post-curing. The photosensitive material is dissolvable or dispersible in an organic solvent, and the information recording layer has sufficient storage stability that allows recorded signals to be stably held for at least 100 hours or longer at 80° C.

Abstract: A method for forming an information recording layer including a multilayer stack of reflection hologram layers modulated in the depth direction of a hologram material layer is provided. The method includes: generating a first pair of polarized coherent laser beams and a second pair of polarized coherent laser beams that are incoherent with the first pair; directing the first pair of polarized coherent laser beams to the hologram material layer from opposite sides thereof, respectively, such that the incident angles of the first pair are symmetric with respect to the hologram material layer; directing the second pair of polarized coherent laser beams to the hologram material layer from the opposite sides thereof, respectively, at incident angles different from the incident angles of the first pair; and forming the multilayer stack of reflection hologram layers according to the interference pattern of the first and second pairs of polarized coherent laser beams.

Abstract: An electrochemical device comprises a laminate including a first electrode layer, a separator layer, and a second electrode layer laminated in sequence; an electrolytic solution infiltrating the laminate; and a resin part covering an outer periphery of the laminate. The second electrode layer has an area smaller than the area of the separator layer and the area of the first electrode layer. The surface of the separator layer opposing the second electrode layer is provided with a noncontact part kept away from the second electrode layer. The noncontact part is formed like a ring along the outer periphery of the separator layer. The resin part further covers the noncontact part of the separator layer.

Abstract: The present invention provides a hologram recording material and a hologram recording medium, which are suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, that is, storage stability, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory recording using not only a green laser but also a blue laser. A hologram recording material comprising: a radical photopolymerizable compound; and a matrix which is a dispersion medium for the radical photopolymerizable compound, wherein the radical photopolymerizable compound comprises a (meth)acrylamide derivative represented by the following general formula (I): CH2?CR1—CONR2—CH2—O—R3 (I) wherein R1 represents H or a CH3 group, R2 represents H or an organic group, and R3 represents an organic group having 3 or more carbon atoms in total. A hologram recording medium 11 which has a hologram recording layer 21.

Abstract: A recording and reading system for a multi-layered optical recording medium includes: a multi-layered optical recording medium including a plurality of recording layers and a single servo layer; and an optical head. The optical head includes a recording and reading objective lens of a signal recording and reading optical system and a servo objective lens of a servo signal detection optical system that are disposed on a common actuator. The recording and reading objective lens is mounted on the common actuator through a minute-drive apparatus so as to be minutely driven in a focusing direction relative to the servo objective lens. When the servo objective lens is focused on the servo layer, a reading light beam is quickly focused on a target one of the plurality of recording layers.