Abstract: A volume holographic memory for recording three-dimensional distribution of interference fringes generated owing to interference between signal light and reference light is provided, wherein the volume holographic memory is formed into a cylindrical shape. Also an optical information recording/reproducing apparatus is provided which incorporates an interference-fringe generating unit for generating interference fringes formed owing to interference between signal light and reference light; a storage unit for storing three-dimensional distribution of the interference fringes generated by the interference-fringe generating unit; a detecting unit for detecting diffracted light obtainable from the storage unit by irradiating the storage unit with reference light; and a reproducing unit for reproducing signal light from diffracted light detected by the detecting unit, wherein the storage unit is constituted by a volume holographic memory having a cylindrical shape.

Abstract: Disclosed are a holographic memory medium for use in a holographic memory system, which can prevent generation of stray light of a gating beam at the time of recording information, and a recording apparatus which uses this memory medium. This memory medium records an information signal carried by a signal beam as a coherent reference beam and the signal beam enter the memory medium with a gating beam being present. The memory medium has at least a first surface and a second surface parallel to each other and comprises an antireflection coat, formed on the first surface, for preventing reflection of the gating beam. The recording apparatus records an information signal using a holographic memory medium and comprises a light absorbing member of absorbing the gating beam coming through the memory medium.

Abstract: A prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The prepreg comprises an inner layer made from a glass fiber substrate, having a weight of 40 g or more and less than 115 g per square meter and an air permeability or 20 cm3/cm2/sec or less, impregnated with an epoxy resin, and an outer layer of an epoxy resin coating provided on at least one side of the inner layer, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

Abstract: A process for manufacturing a prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The process of manufacturing the prepreg comprises (a) a step of impregnating a glass fiber substrate with a solvent, (b) a step of impregnating the solvent-impregnated glass fiber substrate with epoxy resin, (c) a step of heating the epoxy resin-impregnated glass fiber substrate, (d) a step of further impregnating the epoxy resin-impregnated glass fiber substrate, in which the epoxy resin has been cured, with the epoxy resin, and (e) a step of heating the lastly obtained epoxy resin-impregnated glass fiber substrate, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

Abstract: Disclosed is a pretreatment method for a hologram recording medium used in the hologram recording method in which information signals loaded on signal beam are recorded by injecting coherent signal beam and reference beam to the hologram recording medium which is exposed to first light having first wavelength of ultraviolet band or short-wavelength visible light band in advance in order to generate light-induced absorption, wherein the coherent signal beam and reference beam each having longer wavelength than the first wavelength. The pretreatment method comprises subjecting the hologram recording medium to oxidation treatment prior to the irradiation of the first light has been completed.

Abstract: A description is provided of an optical information recording and reproducing apparatus. The apparatus comprises: a holographic memory made of a photorefractive crystalline material; a support portion for detachably supporting the memory; a reference beam supplying portion for supplying a coherent reference beam of a first wavelength incident on the memory; a signal beam generating portion for supplying a coherent signal beam of the first wavelength, which is modulated in accordance with image data, incident on the memory, intersecting therein the signal beam with the reference beam, and generating a three-dimensional interference pattern of the beams; a detecting portion for detecting a diffracted light from a refractive index grating of the interference pattern in the memory, due to irradiation of the reference beam; and a medium position adjusting portion for moving a position of the support portion in accordance with a signal corresponding to positioning images from the detection portion.

Abstract: A description is provided of an optical information recording and reproducing apparatus. The apparatus comprises: a holographic memory made of a photorefractive crystalline material; a support portion for detachably supporting the memory; a reference beam supplying portion for supplying a coherent reference beam of a first wavelength incident on the memory; a signal beam generating portion for supplying a coherent signal beam of the first wavelength, which is modulated in accordance with image data, incident on the memory, intersecting therein the signal beam with the reference beam, and generating a three-dimensional interference pattern of the beams; a detecting portion for detecting a diffracted light from a refractive index grating of the interference pattern in the memory, due to irradiation of the reference beam; and a medium position adjusting portion for moving a position of the support portion in accordance with a signal corresponding to positioning images from the detection portion.

Abstract: A process for manufacturing a prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The process of manufacturing the prepreg comprises (a) a step of impregnating a glass fiber substrate with a solvent, (b) a step of impregnating the solvent-impregnated glass fiber substrate with epoxy resin, (c) a step of heating the epoxy resin-impregnated glass fiber substrate, (d) a step of further impregnating the epoxy resin-impregnated glass fiber substrate, in which the epoxy resin has been cured, with the epoxy resin, and (e) a step of heating the lastly obtained epoxy resin-impregnated glass fiber substrate, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

Abstract: A prepreg exhibiting excellent formability and producing laminated boards and multiple layer circuit boards exhibiting high thickness precision is disclosed. The prepreg comprises an inner layer made from a glass fiber substrate, having a weight of 40 g or more and less than 115 g per square meter and an air permeability or 20 cm3/cm2/sec or less, impregnated with an epoxy resin, and an outer layer of an epoxy resin coating provided on at least one side of the inner layer, wherein the epoxy resin reaction rate in the inner layer is 85% or more and the epoxy resin reaction rate in the outer layer is 60% or less.

Abstract: An optical information recording and reproducing apparatus, which detachably supports a holographic memory formed of a photorefractive crystal, includes a portion for supplying a coherent reference light beam at a first wavelength into the holographic memory; a portion for supplying a coherent signal light beam at the first wavelength, modulated in accordance with image data, into the memory to produce an optical interference pattern with the reference light within the memory; a portion for supplying a gate light beam at a second wavelength into the memory for activating or deactivating an index grating in accordance with the presence or absence of the optical interference pattern to enhance a photo-sensitivity of the memory; a detector for detecting diffraction light from the index grating of the memory by the irradiation of the reference light beam; and a portion for changing and regulating a light intensity of the gate light beam.

Abstract: The present invention provides a material for electrical insulating organic film, superior in electrical properties, thermal properties and low water absorption; an electrical insulating organic film made from the material; and a process for production of the film. That is, the present invention provides an electrical insulating organic film having fine pores, consisting of a layer of a polybenzoxazole resin represented by the following general formula (1): wherein n is an integer of 2 to 1,000; X is a tetravalent organic group; and Y is a bivalent organic group; a material for electrical insulating organic film obtained by mixing a polybenzoxazole precursor or a polybenzoxazole resin, with an oligomer; and a material for electrical insulating organic film, obtained by reacting at least one carboxylic acid terminal of a polybenzoxazole precursor with an amino group- or hydroxyl group-containing oligomer.

Abstract: A two-color hologram recording/reproducing apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated, and a gate light source for directing gate light at a third wavelength into the hologram recording medium.

Abstract: A description is provided of an optical information recording and reproducing apparatus employing a holographic memory. The apparatus includes a mask disposed in an optical path of the signal light beam so as to cover a light intensity distribution of the signal light beam incident into the holographic memory at nearly a half portion thereof with respect to the center of the distribution of the zeroth-order diffracted light of the signal light beam. The center of a region of the holographic memory where the signal light beam and the reference light beam intersect with each other, is shifted by a distance substantially equal to twice the distance between peaks of the zeroth-order diffracted light or the first-order diffracted light of the signal light beam.

Abstract: Digital signal sequences to be recorded in predetermined unitary recording areas are transformed into blocks, a plurality of bit data carrying all digit levels to be read and determined upon reproduction are included in the resultant blocks, and sequences of the data blocks are recorded in the recording medium in the unitary recording areas. Upon reproduction, the blocks of the read signals obtained from a recording medium are recognized, a threshold value is determined for each block on the basis of the values of read signals corresponding to bit data carrying all digit levels to be read and determined, and each digit level of bit data in the read signal are read and determined on the basis of the threshold values.

Abstract: Digital signal sequences to be recorded in predetermined unitary recording areas are transformed into blocks, a plurality of bit data carrying all digit levels to be read and determined upon reproduction are included in the resultant blocks, and sequences of the data blocks are recorded in the recording medium in the unitary recording areas. Upon reproduction, the blocks of the read signals obtained from a recording medium are recognized, a threshold value is determined for each block on the basis of the values of read signals corresponding to bit data carrying all digit levels to be read and determined, and each digit level of bit data in the read signal are read and determined on the basis of the threshold values.

Abstract: A description is provided of an optical information recording and reproducing apparatus which detachably supports a volume holographic memory formed of a photorefractive crystal. The apparatus includes a portion for supplying a coherent reference light beam at a first wavelength into the volume holographic memory; a portion for supplying a coherent signal light beam at the first wavelength, modulated in accordance with image data, into the memory to produce an optical interference pattern with the reference light within the memory; a portion for supplying a gate light beam at a second wavelength into the memory for activating or deactivating an index grating in accordance with the presence or absence of the optical interference pattern to enhances a photo-sensitivity of the memory; and a detector for detecting diffraction light from the index grating of the memory by the irradiation of the reference light beam.

Abstract: A description is provided of an optical information recording and reproducing apparatus employing a holographic memory. The apparatus includes a mask disposed in an optical path of the signal light beam so as to cover a light intensity distribution of the signal light beam incident into the holographic memory at nearly a half portion thereof with respect to the center of the distribution of the zeroth-order diffracted light of the signal light beam. The center of a region of the holographic memory where the signal light beam and the reference light beam intersect with each other, is shifted by a distance substantially equal to twice the distance between peaks of the zeroth-order diffracted light or the first-order diffracted light of the signal light beam.

Abstract: A polybenzoxazole precursor having recurring units represented by the following general formula (1) and a polybenzoxazole resin having a structure obtained by cyclizing the polybenzoxazole precursor: wherein n denotes an integer of 1-1000, and (i) when X is selected from bivalent aromatic groups represented by the general formulas (2)-(4) defined in the specification each having two OR groups (Rs each denotes H or a monovalent organic group and may be the same or different), and the amide group in the formula (1) and the OR group respectively bond to the adjacent carbon atoms of the aromatic group, Y denotes a bivalent organic group containing fluorine; and (ii) when Y is selected from bivalent aromatic groups represented by the general formulas (5)-(7) defined in the specification, X denotes a bivalent aromatic group containing fluorine and having two OR groups (Rs each denotes H or a monovalent organic group and may be the same or different), and the amide group in the formula (1) and the

Abstract: A volume holographic memory-based optical information-recording/reproducing apparatus being capable of controlling an interference area formed by a reference beam and a signal beam within a recording medium more easily than by waveform shaping using a lens. A recording medium is installed in the apparatus for recording a three-dimensional optical interference pattern formed by at least two coherent light beams as spatial changes in refractive index of the recording medium. A signal beam optical system transmits a coherent signal beam to the recording medium through a Fourier transform lens. A reference beam optical system transmits a coherent reference beam to the recording medium. The reference beam intersects the signal beam within the recording medium, and an angle of intersection between the reference beam and the signal beam is changed. Diffracted light of the reference beam diffracted from the recording medium is detected.

Abstract: Digital signal sequences to be recorded in predetermined unitary recording areas are transformed into blocks, a plurality of bit data carrying all digit levels to be read and determined upon reproduction are included in the resultant blocks, and sequences of the data blocks are recorded in the recording medium in the unitary recording areas. Upon reproduction, the blocks of the read signals obtained from a recording medium are recognized, a threshold value is determined for each block on the basis of the values of read signals corresponding to bit data carrying all digit levels to be read and determined, and each digit level of bit data in the read signal are read and determined on the basis of the threshold values.