392 results about "Holographic data storage" patented technology

A holographic storage apparatus for recording data in a holographic medium includes at least one light source for generating a reference beam and a signal beam. The reference beam is preferably a phase beam of unchanging phase content. The apparatus also includes a holographic medium placed in a path of the reference beam and a path of the signal beam. The holographic medium has a first face and both the reference beam and the signal beam enter the holographic medium through the first face. The holographic medium also includes a data reflective surface. The reference beam and the signal beam interfere in the holographic medium to create a hologram only after at least one of the reference beam and the signal beam have reflected off of the data reflective surface.

Holographic data storage devices are presented. The holographic data storage device includes an optically transparent substrate, wherein the optically transparent substrate includes a photochemically active dye and a heat generating chromophore. Methods for making holographic data storage device are also presented.

Systems and methods for constructing concatenated codes for data storage channels, such as holographic storage channels, are provided. The concatenated codes include an outer BCH code and an inner iteratively decodable code, such as an LDPC code or turbo code. The correction power and coding rate of one or both of the codes may be programmable based on the channel characteristics and the desired SNR coding gain. The correction power and/or coding rate of the inner and/or outer code may also be dynamically adjusted in real-time to compensate for time-varying error conditions on the channel.

Methods for holographic data storage are disclosed. The method includes providing an optically transparent substrate comprising a photochemically active dye and irradiating the optically transparent substrate with a holographic interference pattern and a photochromic conversion control illumination. The pattern has a first wavelength and an intensity both sufficient to convert, in the presence of the photochromic conversion control beam, within a volume element of the substrate, at least some of the photochemically active dye into a photo-product, and producing within the irradiated volume element concentration variations of the photo-product corresponding to the holographic interference pattern thereby producing an optically readable datum corresponding to the volume element. The photochromic conversion control illumination has a second wavelength and an intensity to control the photochromic conversion amplitude in the volume element.

Methods for storing holographic data are presented. The method includes providing an optically transparent substrate comprising a thermally active photochemically active polymer composition, the polymer composition including a photochemically active dye and a heat generating chromophore, thermally activating at least a part of a volume element of the optically transparent substrate to increase a quantum efficiency of photochemical conversion of the photochemically active dye into a photo-product, within the at least a part of the volume element and converting at least some of the photochemically active dye to a photo-product, and producing concentration variations of the photo-product within the volume element of the optically transparent substrate, thereby producing an optically readable datum corresponding to the volume element.

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 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.

A data input method is applied to a holographic digital data storage system in which sequential binary input data bits are arranged in an interleaved manner among pages. A first data bit is arranged in a specific position of a predetermined page, a second data bit is arranged in a specific position having similar beam intensity with that of the first data bit. Using this method, the holographic digital data storage system can be less affected by the adverse effect of spatial beam intensity variations and makes the entire data interleaved automatically to obtain more stable output data.

The present invention provides a method and system for increasing the holographic storage capacity of a holographic recording medium using an irradiance-tailoring (e.g., optical) element by changing the irradiance profile of the modulated object beam (e.g., by imparting motion to an irradiance-tailoring element and/or the holographic recording medium and/or by reconfiguring (e.g., periodically) the phase profile of a stationary irradiance-tailoring (e.g., optical) element) to minimize the effects of fixed-pattern noise buildup from occurring in the holographic recording medium.

A spatial light modulator (SLM) having a phase mask that is provided as an internal component thereof. The phase mask can be provided as a multilevel surface of relatively higher index of refraction material on an inner surface of a transmissive cover window or as a separate transmissive window between the cover window and the pixels of the SLM. If the phase mask is to be used with a liquid crystal SLM, then it may be desirable to planarize the surface of the cover window contacting the liquid crystal by providing a layer of relatively lower index of refraction material adjacent the multilevel surface. The phase mask can also be provided on the transmissive cover window by patterned ion deposition, exposing patterned light to a photopolymeric material, or in some other suitable fashion. Arranging for the pixel electrodes to be at one of multiple levels rather than lying in an exactly planar relationship can also effectively create the phase mask.