110 results about "Holographic memory" patented technology

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 a metal oxide and a photopolymerizable compound; and said hologram recording medium has a light transmittance of 50% or more at a wavelength of 405 nm, or a light reflectance of 25% or more at a wavelength of 405 nm.

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.

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.

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 comprising Si and at least one selected from the group consisting of Ta and Zr, as metals, wherein a complexing ligand is coordinated to Ta and/or Zr; and a photopolymerizable compound. The complexing ligand is preferably selected from the group consisting of β-dicarbonyl compounds, polyhydroxylated ligands, and α- or β-hydroxy acids. A hologram recording medium (11) comprising the hologram recording material layer (21).

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, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory record using not only a green laser but also a blue laser; and provides a hologram recording medium having a hologram recording layer comprising the hologram recording material. A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound, wherein the metal oxide matrix comprises at least Si and Ti as metallic elements, and Ti originates from titanium-containing oxide fine particles. A hologram recording medium (11) having the hologram recording layer (21) comprising the hologram recording material.

The present invention provides a hologram recording medium which is suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, 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 medium (11) comprising at least a hologram recording layer (21), wherein the hologram recording layer contains a metal oxide matrix comprising metal oxide fine particles, and a photopolymerizable compound; the metal oxide fine particles comprise metal oxide fine particles containing Ti as a metallic element; and at the time of subjecting the hologram recording layer before exposure to light to an extraction operation in n-butyl alcohol having a mass 100 times the mass (W) of said recording layer, thereby yielding a sol solution; filtrating the sol solution to obtain a filtrated sol solution; and measuring particle diameter distribution of sol particles in the filtrated sol solution by a dynamic light scattering method; and obtaining an average particle diameter thereof, the average particle diameter of the sol particles is in the range of 5 nm or more and 50 nm or less.

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.

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.

The present invention relates to a reproduction device of a holographic memory capable of precisely reproducing multi-value phase information without being influenced by noise. This holographic memory reproduction device comprises: a hologram diffraction ray generation unit which irradiates a first reference ray to the holographic memory and generates a diffraction ray of the first hologram; a hologram generation unit which changes the phase of a second reference ray which may interfere with the diffraction ray of the first hologram and generates a second hologram from the diffraction ray of the first hologram and the second reference ray to which the phase has been changed; a detection unit which detects the intensity distribution of the second hologram; and a processing unit which demodulates the phase modulation signal or the space quadrature amplitude modulation signal on the basis of the intensity distribution.

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 β-dicarbonyl compound is coordinated to Zr; and a photopolymerizable compound, wherein a mole ratio of the β-dicarbonyl compound to the Zr atom (β-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).

The invention relates to a photopolymer holographic storage material comprising high refractivity epoxy resin and low refractivity monomer and method for making it. Under the protection of red lamp or photophobic condition, using the following components by weight percentage: 15%-45% olefin monomer, 0.01-0.1% photosensitizer, 0.1-0.9% photo-initiation agent, 0.1-1.0% chain-transferring agent, 0.1-1.0% defoaming agent, 0.1-1.0% levelling agent, 3%-15% epoxy resin active deflocculating agent and 30%-70% epoxy resin for even mixing, forming transparent sol solution, then adding 5%-15% epoxy resin curing agent into the sol solution, mixing evenly and injecting into container, then the photopolymer holographic storage material according to the invention can be obtained through curing.

Even when a tilt error is caused in a holographic memory in a direction perpendicular to a surface including optical axes of a signal beam and a reference beam (radial tilt direction), the signal beam and the reference beam are allowed to enter the holographic memory at adequate angles relative thereto at all times by suppression of the tilt error. A reference tilt hologram for specifying a reference incident angle of the reference beam in a radial tilt direction is recorded in advance on a holographic memory medium. During recording and reproducing operations, the reference beam is emitted to a recording position of the reference tilt hologram and the reference incident angle (reference angle Sr) of the reference beam in the radial tilt direction is detected based on a received light state. A tilt actuator (19) for displacing the holographic memory medium in the radial tilt direction is driven to adjust an incident angle of the reference beam in the radial tilt direction to the reference angle Sr. Then, the signal beam and the reference beam are emitted to the holographic memory medium to execute the recording and reproducing operations.

A holographic memory apparatus comprises first phase modulation means that adds phase information to each pixel of a signal beam to generate page data at recording time; oscillator light generation means that generates an oscillator light that is superimposed on, and interferes with, a diffracted light from a holographic recording medium at reproduction time; second phase modulation means that adds phase information to the oscillator light; and light detection means that detects an interference light generated by superimposing the oscillator light and the diffracted light from the holographic recording medium.

A hologram recording medium, a hologram recording method and a recording and reproducing apparatus are capable of recording an interference pattern onto a volume holographic memory at high density. In a hologram recording method for forming a plurality of areas of a refractive index grating corresponding to one portion of a three-dimensional light interference pattern of a coherent signal light beam and coherent reference light of a first wavelength modulated in accordance with information data within a recording medium made of a photo refractive crystal of a uniaxial crystal having a shape of parallel flat plates, the signal light beam and the recording reference light beam cross each other within the recording medium, and a gate light beam having a second wavelength for revealing recording sensitivity of the recording medium is simultaneously irradiated to the recording medium so as to pass through a portion of the recording medium for crossing the signal light beam and the recording reference light beam and demarcate a volume smaller than that of this crossing portion. In a reproducing step a reproducing reference light beam is generated by reflecting the recording reference light beam in the vicinity of the beam waist of the recording reference light beam.

The pitch of light beam spots on a light receiving surface of an address detector upon search of information recorded on a holographic recording medium is decreased to reduce a distance between the holographic recording medium and the address detector. In a holographic recording and reproducing apparatus 10, a reference beam having an elliptical beam shape transformed by a beam shaping optical system 30 and an object beam having an unchanged circular shape are projected onto a holographic recording medium 20 so that interference fringes are allowed to be formed only within the elliptical shape. Therefore, even when the distance of an address detector 28 from the holographic recording medium 20 is reduced, crosstalk is prevented between array-shaped two-dimensional photodetectors 28A, 28B, 28C, and so on constituting the address detector 28.

Systems and methods for recovering data in a holographic memory system. The systems and methods use homodyne detection to introduce a local oscillator beam into a reconstructed data beam of the recovered hologram. An image of the combined beam comprising the reconstructed data beam and local oscillator beam may be processed to obtain contrast level information for the pixels of the detected image. This contrast level information may then be used to obtain an increased contrast image of the recovered hologram, which may increase the SNR of the recovered data.

A holographic memory system comprises a spatial light modulator having multiple modulators for spatially modulating at least a part of a light beam emitted from a light source and rendering it as an information light beam, and a light sensing device for reading the information light beam taken out of a recording medium. The spatial light modulator and the light sensing device are integrally formed on the same substance.

A holographic memory system includes a light source for generating a reference beam having a wavelength; and a photodetecting device for selectively detecting a reconstructed signal beam corresponding to the reference beam. The photodetecting device includes a band-pass filter for transmitting light of a wavelength band including the wavelength of the reconstructed signal beam while blocking light having a wavelength deviating from the wavelength band; and a photodetecting unit for detecting the light transmitted through the band-pass filter.

A holographic memory reproduction apparatus which makes a wavelength of a reproducing laser beam coincident with a wavelength of a laser beam used for holographic recording when information is reproduced from a holographic recording medium. In the holographic memory reproduction apparatus 10, a temperature adjustment device 26 is attached to a semiconductor laser 12. On the holographic recording medium 16, wavelength information of the laser beam used for recording is recorded as a wavelength address hologram 28. When the information is reproduced, the temperature adjustment device 26 is controlled by a wavelength control device 24 in accordance with a signal beam from the wavelength address hologram 28, thereby making an oscillation peak wavelength of the semiconductor laser 12 coincident with the wavelength of the laser beam used for recording.