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: The present invention provides a method for producing an optical recording medium having: a supporting substrate; a light transmission layer, which transmits a laser beam; and an information layer formed between the supporting substrate and the light transmission layer, which includes: applying a resin composition on the information layer by a spin coating method to form a coating film, wherein the resin composition contains, as main components: (A) a radical-curing urethane(meth)acrylate, which is obtained by reacting (a-1) a compound having three or more isocyanate groups binding to an aliphatic carbon atom per one molecule thereof and (a-2) a polycaprolacton-modified hydroxyethyl(meth)acrylate; and (B) a radical-curing monomer having a viscosity of 400 mPa.s or less at 25° C., curing the coating film by irradiating the coating film with an ultraviolet light or an electron beam to form the light transmission layer.

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 hardcoat agent composition comprising a fluorine-containing polyether compound (A) having a perfluoropolyether unit, urethane bond and active energy ray reactive group and a curable compound (B) having equal to or more than 2 active energy ray polymerizing groups in the molecule. An optical information medium having a film substance composed of single or multiple layers containing at least the recording layer 4 or the reflecting layer on the supporting substrate 20, the optical information medium wherein at least either the surface of the supporting substrate 20 or that of the above-mentioned film substance is formed by the hardcoat layer 8 containing a curable substance of the above-mentioned hardcoat agent composition.

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: 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.

Abstract: A hardcoat agent composition comprising a fluorine-containing polyether compound (A) having a perfluoropolyether unit, urethane bond and active energy ray reactive group and a curable compound (B) having equal to or more than 2 active energy ray polymerizing groups in the molecule. An optical information medium having a film substance composed of single or multiple layers containing at least the recording layer 4 or the reflecting layer on the supporting substrate 20, the optical information medium wherein at least either the surface of the supporting substrate 20 or that of the above-mentioned film substance is formed by the hardcoat layer 8 containing a curable substance of the above-mentioned hardcoat agent composition.

Abstract: An optical recording medium has a recording layer formed of a plurality of reflection hologram layers. A spacer layer is interposed between the respective reflection hologram layers. The reflection hologram layer is made of a material having a thermal threshold value which allows, when being irradiated with a recording laser beam, local absorbed heat to vary hologram diffraction conditions at a focal position, and allows the hologram to be retained at non-focal positions. The spacer layer is made of a material which is insensitive to a laser beam of a recording wavelength and which has a smaller extinction coefficient than that of the reflection hologram layer.

Abstract: A method for using a low-cost artificial fingerprint liquid for quantitatively and with a good reproducibility evaluating an anti-staining property, and a fingerprint adhering property or a fingerprint removing property on the surface of an optical disk such as a reproduction-only optical disk, optical recording disk, magneto-optical recording disk, various displays such as a CRT, and various substances such as glass. A stamp is used to transfer the artificial fingerprint solution to the surface to be tested. An artificial fingerprint liquid comprising a fine-particle-form substance and a dispersion medium capable of dispersing the fine-particle-form substance. The dispersion medium preferably has a surface tension ranging from 20 to 50 mN/m at 25° C., and preferably is selected from at least one of higher fatty acid, derivative of higher fatty acid, terpens, and derivatives of terpens. The fine-particle-form substance is at least one selected from inorganic fine particles and organic fine particles.

Abstract: A hardcoat agent composition comprising a fluorine-containing polyether compound (A) having a perfluoropolyether unit, urethane bond and active energy ray reactive group and a curable compound (B) having equal to or more than 2 active energy ray polymerizing groups in the molecule. An optical information medium having a film substance composed of single or multiple layers containing at least the recording layer 4 or the reflecting layer on the supporting substrate 20, the optical information medium wherein at least either the surface of the supporting substrate 20 or that of the above-mentioned film substance is formed by the hardcoat layer 8 containing a curable substance of the above-mentioned hardcoat agent composition.

Abstract: An optical recording medium includes a support substrate and an information recording layer which is supported on the support substrate and made of a photosensitive material which is irradiated with light to be refractive index modulated and amplitude modulated, thereby recording information. The information recording layer has the shape of a coating which is formed by applying a photosensitive material reversibly dissolved or dispersed in an organic solvent onto the support substrate. The photosensitive material in the shape of a coating, as a photopolymer for hologram recording material, contains the cross-linked matrix to maintain the rigidity of the recording material. The optical recording medium is retained in shape with stability, and particularly prevented from being deformed due to shrinkage, thereby facilitating manufacturing of the optical recording medium.

Abstract: A method for using a low-cost artificial fingerprint liquid for quantitatively and with a good reproducibility evaluating an anti-staining property, and a fingerprint adhering property or a fingerprint removing property on the surface of an optical disk such as a reproduction-only optical disk, optical recording disk, magneto-optical recording disk, various displays such as a CRT, and various substances such as glass. A stamp is used to transfer the artificial fingerprint solution to the surface to be tested. An artificial fingerprint liquid comprising a fine-particle-form substance and a dispersion medium capable of dispersing the fine-particle-form substance. The dispersion medium preferably has a surface tension ranging from 20 to 50 mN/m at 25° C., and preferably is selected from at least one of higher fatty acid, derivative of higher fatty acid, terpens, and derivatives of terpens. The fine-particle-form substance is at least one selected from inorganic fine particles and organic fine particles.

Abstract: The present invention provides a method for producing a homogeneous complex oxide sol comprising Si and a metal other than Si as metal elements, and a method for producing a Si-containing hologram recording material using a homogeneous complex oxide sol. A method for producing a complex oxide sol comprising Si and a metal other than Si as metal elements, the method comprising: mixing a silanol compound with an alkoxide compound of a metal other than Si so that the silanol compound is reacted with the alkoxide compound, thereby yielding a precursor of a complex oxide, and adding water to the complex oxide precursor so as to hydrolyze an alkoxyl group bonded to the metal other than Si, and then making the resulting hydrolysate undergo a condensation reaction, thereby forming a complex oxide. A hologram recording medium (11) having a hologram recording layer (21) comprising the hologram recording material obtained by the production method.

Abstract: An optical information medium includes a light-transmitting supporting substrate, an information recording layer on one surface of the supporting substrate, a protective layer on the information recording layer, and a light-transmitting hard coat layer on an other surface of the supporting substrate. The medium is configured to have a recording/reproducing beam incident into the information recording layer through the hard coat later and the supporting substrate.

Abstract: The present invention provides a hologram recording medium wherein high refractive index change, flexibility, low scattering, environment resistance, durability, low dimensional change (low shrinkage), and high multiplicity are attained in holographic memory recording using a blue laser as well as a green laser. A hologram recording medium comprising at least a hologram recording layer, wherein the hologram recording layer (21) contains at least an organometallic compound which contains a metal atom, an organic group, and an oxygen atom, and has a direct bond between the metal atom and a carbon atom in the organic group (a metal-carbon bond), and a bond between the metal atoms through the oxygen atom (a metal-oxygen-metal bond) and a photopolymerizable compound; and the hologram recording layer (21) contains the metal atoms in an amount of 3.0% by mass or more and 20% by mass or less with respect to the hologram recording layer.

Abstract: The present invention provides a hologram recording medium wherein, in holographic memory recording using a blue laser as well as a green laser, a fall in light transmittance is very small even after recording. A hologram recording medium comprising at least a hologram recording material layer, wherein the hologram recording material layer (21) comprises at least fine particles of a metal compound, and a photopolymerizable compound; and the recording sensitivity of said recording medium (11) to a laser light having a wavelength of 405±5 nm is 0.05 cm/mJ or more and 1.20 cm/mJ or less.