Abstract: Methods for recording volume Bragg grating structures having a target wavelength are disclosed. Such a method may include providing a photosensitive recording medium, bringing a first face of the recording medium into contact with a face of a prism, the prism being made of a material that is transparent at a recording wavelength, and recording a Bragg grating onto the recording medium by exposing the prism to an incident light wave at the recording wavelength.

Abstract: There is provided a hologram recording method, including generating a signal light which is spatially modulated such that digital data is represented by an image of intensity distribution, irradiating the signal light on an optical recording medium after a Fourier transformation of the signal light such that a zero-order component of the signal light comes into focus at a point removed from the optical recording medium, forming a diffraction grating in the optical recording medium by interference between the zero-order component of the signal light and a high-order component thereof, and recording digital data represented by the signal light as a hologram.

Abstract: A holographic memory system and apparatus, and a method provide the ability to store multibit holograms in a photorefractive crystal. A single laser diode is configured to emit a collimated laser beam to both write a page of multibit data to and read the page of multibit data from the photorefractive crystal. A multilevel spatial light modulator (DMDSLM) is configured to encode the page of multibit data on an input beam split from the collimated laser beam. A first imaging relay lens pair is positioned between the multilevel spatial light modulator and the photorefractive crystal to image a multibit spatial light modulator image on a plane behind the photorefractive crystal. One or more mirrors are configured to steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal to read or write a page of the multi-bit data.

Abstract: An optical recording method includes providing an optical recording medium capable of forming both a refractive index grating and an absorption grating by light irradiation; Fourier transforming with the same lens a signal beam that represents binary digital data with a brightness image and a reference beam such that they are focused at a point outside the optical recording medium; irradiating the Fourier transformed signal beam and reference beam simultaneously onto the optical recording medium and forming a diffraction grating at the optical recording medium according to an interference fringe between the signal beam and the reference beam, or according to an interference fringe within the signal beam itself; and recording the signal beam as a hologram.

Abstract: An optical integrated unit of the present invention includes: a semiconductor laser that is a light source; at least one light receiving element; a light dividing section which divides outgoing light from the semiconductor laser and returning light from an optical disc, and reflects the returning light so as to guide it to the light receiving element; and a support substrate, and a second support substrate is concave, the light dividing section includes at least three prisms, the prisms on both sides of the light dividing section are respectively adhered to two protrusions of the concave second support substrate, and the light receiving element is adhered to the light dividing section via a cover glass. With this, it is possible to solve a problem of a conventional technology, that is, such a problem that the light receiving element cannot be adjusted highly accurately because of the thickness errors of the support substrate and the relay substrate.

Abstract: A hologram recording and reproduction apparatus is disclosed which can raise the degree of freedom in design to achieve miniaturization thereof and can raise the hologram recording density of the shift multiplexing type. Upon recording, recording light specially optically modulated by a spatial optical modulator and reference light having a wave front disturbed at random by a randomizing phase mask are coupled so as to have a common optical axis and introduced to a recording area of a hologram recording medium. As a result, the number of lenses to be moved so as to follow up the variation of the position of a recording area or a reproduction area can be reduced. Further, the random disturbance of the wave front of the reference light makes the shift selectivity sharp in both of the along-track direction and the cross-track direction.

Abstract: According to an aspect of the present invention, a data recording method in a holography optical memory system, for recording a two-dimensional pixel data page in a recording medium can be provided. In accordance with an embodiment of the present invention, the data recording method in a holography optical memory system can include recording sequentially the signal beams carrying one-dimensional pixel data lines, included in the original two dimensional pixel data page, in the recording medium by using the same reference beam. Here, the pixel data page can be recorded such that any two adjacent pixel data lines are partially overlapped with each other in an area of the recording medium.

Abstract: In a recording apparatus capable of performing a curing process at high speed by curing a plurality of books at a time during recording and capable of performing recording of a recordable type, when recording is stopped once, the unit of books to be cured at a time is set smaller than that during continuous recording, in order to realize inexpensively both performing a curing process at high speed in hologram recording and realizing recording of a recordable type freely in a book unit. It is therefore possible to terminate recording in the unit of arbitrary books irrespective of the unit of books to be cured, and perform recording of a recordable type without loss.

Abstract: Provided is an objective lens for recording a hologram that condenses an recording beam on a hologram recording medium, and the objective lens is configured so as to condense, in the case where the recording beam is incident upon the objective lens in a form of a parallel beam flux, an on-axis beam flux and an off-axis beam flux contained in the parallel flux so as to form a beam waist in the hologram recording medium, and such that a distance between an off-axis image point of the off-axis beam flux that defines a largest field angle among the off-axis beam fluxes gradually converging ahead of the beam waist and the hologram recording medium becomes minimal.

Abstract: A method is disclosed to determine an optimal optical detector orientation to decode information encoded holographically. The method supplies a matched filter, an orientation image, a holographic data storage medium encoded with the orientation image, and an optical detector comprising a moveable input screen comprising a plurality of detector elements. The method positions the input screen in a plurality of input screen orientations and calculates a correlation factor for each of the input screen orientations. The method determines an optimal optical detector orientation using the plurality of correlation factors.

Abstract: A method is disclosed to store information in a holographic data storage medium. The method provides a hologram comprising an alignment pattern, and disposes that hologram into a holographic data storage medium during manufacture.

Abstract: A holographic optical information playback apparatus for playing information that is recorded on a recording medium in a form of interference fringes is provided with a two-dimensional photoreceptor array which receives a two-dimensional array of light spots that is diffracted at the recording medium due to application of reference light onto the medium, and outputs a playback signal including information recorded on the recording medium. The two-dimensional photoreceptor array has a photoreceptor section in which plural photoreceptor cells for detecting the intensities of received lights are arranged so that a photoreceptive area corresponding to the light spot array is formed, and assigns plural photoreceptor cells are assigned to each light spot in the light spot array according to the irradiation position of the light spot array, whereby the light intensity of one light sport is detected using the output signals from the plural photoreceptor cells.

Abstract: The present invention relates to a holographic storage medium, and more specifically to a holographic storage medium with an improved servo architecture for precise positioning of a laser beam in radial, axial and tangential direction. According to the invention, a holographic storage medium includes a holographic layer for storing holograms and a servo layer with a track structure for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium, wherein the track structure includes a pack of two or more tracks.

Abstract: An optical-information recording medium includes a substrate that includes a servo surface having a servo pattern thereon; an information recording layer laminated on the servo surface of the substrate capable of recording information as a hologram produced by interference between an information beam containing the information and a reference beam; an address servo area that is formed as a part of the servo pattern, and that records therein address information and clock information for aligning a beam, emitted from an optical-information recording apparatus for recording information in the information recording layer, to a target position in the information recording layer; and a following up servo area that is formed as a part of the servo pattern, and that is to be irradiated by the beam to make the beam follow a rotation of the optical-information recording medium.

Abstract: A reproducing apparatus, reproducing method, recording and reproducing apparatus, recording and reproducing method, recording apparatus, and recording method are provided.

Abstract: There is provided an optical disk apparatus causing a hologram device to diffract a reflected light beam and causes each of reflected light beams of primary light in a longitudinal direction to generate received light signals by receiving the reflected light beams through receiving regions of a receiving unit before a preformatted signal being generated by a signal processing unit based on the received light signals. Therefore, the preformatted signal that excludes an influence of a stray light pattern by an interlayer stray light beam from a plurality of recording layers can be generated.

Abstract: An apparatus and method for processing optical information using a low density parity check code are suggested. An optical information recording method includes the steps of encoding data to record into a low density parity check code; representing the data, which is encoded into the low density parity check code, to a spatial light modulator in the unit of a data page; and modulating a recording beam into the data page representing the spatial light modulator to be recorded in the form of hologram in a recording medium. By blocking inexact probability information from being concentrated in the LDPC code block, by achieving exact probability information through effective allocation of a mark, and by improving average accuracy of the pixel, which corresponds to the LDPC code, failure rate of decoding can be minimized so that decoding performance can be improved.

Abstract: A hologram recording device for irradiating a recording beam (S) to a hologram recording medium (B) at a fixed incident angle (?s) and irradiating a reference beam (R) to an illuminated region (p) of the recording beam (S) by variably controlling an incident angle (?r) of the reference beam (R) on the hologram recording medium (B), whereby a hologram is recorded on the illuminated region (p) in multiple, includes at least a variable reflector (10) directing the reference beam (R) to the illuminated region by reflection and being swung around a predetermined axis (x) for changing the incident angle (?r) of the reference beam (R); and a light shield (11) being swung integrally with the variable reflector (10) for partially shielding the reference beam (R) so that a luminous flux diameter thereof becomes narrower as the incident angle (?r) becomes larger.

Abstract: A hologram reproducing apparatus includes a reference-light spatial-light modulating section that displays a reference light pattern for generating reference light, an image sensor that has pixels arrayed two-dimensionally that receive diffractive light generated by irradiating the reference light on a hologram recording medium, and a control unit that processes an electric signal from the image sensor and reproduces recording data. The control unit detects a predetermined area electric signal, detects a hologram electric signal, subtracts the predetermined area electric signal from the hologram electric signal to obtain a reproduced signal after noise reduction, and reproduces the recording data from the reproduced signal after noise reduction.

Abstract: An optical disc for micro-holographic data storage, including: optically-enabled material configured to store holographic data; guide grooves; a first coating disposed on the guide grooves and configured to reflect a tracking beam and to transmit a read or record beam; and a second coating disposed to cover the guide grooves and disposed on the first coating.

Abstract: A system and method of operating a dual-beam detection system of a holographic data storage disc, including: impinging a data beam on a data layer of the holographic data storage disc; impinging a tracking beam on a tracking element of the holographic data storage disc; detecting a reflection of the tracking beam from the tracking element; and coordinating position of the data beam relative to the tracking beam.

Abstract: A system and method for replicating optical data storage discs (e.g., holographic data storage discs) having multiple layers of data. Master discs providing for respective single layers of data are utilized, and each respective single layer of data from the master discs are replicate onto the optical data storage disc.

Abstract: A system and method for controlling tracking in a holographic data storage system, including: impinging a beam on a holographic data disc, wherein the beam is reflected from a micro-hologram disposed within the holographic data disc; detecting the reflected beam from the holographic data disc by a multi-element detector; and analyzing a pattern detected by multi-element detector to generate a tracking error signal.

Abstract: A servo controlling method for controlling an information processing apparatus using a hologram. The method includes a step of irradiating a holographic recording medium with light having a first wavelength and irradiating the holographic recording medium with light having a second wavelength, different from the first wavelength, a step of directing first return light by the light of the first wavelength and second return light by the light of the second wavelength to be incident on the same light receiving element, and a step of performing servo control by separating the first return light from the second return light at the light receiving element.

Abstract: A data storage device including: a plastic substrate having a plurality of volumes arranged along a plurality of depth-extending, concentrically stacked tracks; and, a plurality of micro-holograms each contained in a corresponding one of the tracks; wherein, the presence or absence of a micro-hologram in each of said volumes is indicative of a corresponding portion of data stored.

Abstract: The present techniques provide methods and systems for more reliable reading of optical data disks. In embodiments, a multi-pixel detector that is segmented into multiple areas, or detector segments, may be used to detect a pattern in the light reflected from an optical data disk. The pattern may include light scattered from a single bit that may be under a center detector, as well as light scattered from proximate bits. The detector system may then combine the quantized values from each of the detector segments mathematically to determine the presence or absence of a bit or bits of data. The mathematical combination may also use data that is known about the status of adjacent data bits (such as previously read bits, or bit patterns which are allowed or not allowed by specific data encoding schemes) to improve the accuracy of the bit prediction.

Abstract: A data storage device including: a plastic substrate having a plurality of volumes arranged in tracks along a plurality of vertically stacked, laterally extending layers therein; and, a plurality of micro-holograms each contained in a corresponding one of the volumes; herein, the presence or absence of a micro-hologram in each of the volumes is indicative of a corresponding portion of data stored.

Abstract: A system for use with a data storage media having at least one groove proximate a surface thereof and a plurality of volumes therein, including: objective lensing; a first tracking error detector optically coupled to the objective lensing and being responsive to reflections from the at least one groove; a first actuator coupled and responsive to the first tracking error detector; a second tracking error detector optically coupled to the objective lensing and responsive to reflections from micro-holograms contained in at least some of the volumes; and, a second actuator coupled and responsive to the second tracking error detector; wherein the first and second actuators cooperate to selectively position the objective lensing to focus a light beam into a target one of the volumes.

Abstract: A data storage device including: a plastic substrate having a plurality of data volumes arranged along tracks in a plurality of stacked layers; a plurality of micro-holograms each contained in a corresponding one of the data volumes; a plurality of complementary volumes, each corresponding to and being substantially aligned with one of the data volumes; a plurality of micro-holograms each contained in a corresponding one of the complementary volumes; wherein, the presence or absence of a micro-hologram in each of the data volumes is indicative of a corresponding portion of data stored; and, the ones of the complementary volumes corresponding to the ones of the data volumes containing a micro-hologram do not contain a micro-hologram; and the ones of the complementary volumes corresponding to the ones of the data volumes not containing a micro-hologram contain a micro-hologram.

Abstract: A data storage device comprises a substrate having oppositely disposed surfaces and a plurality of volumes arranged along tracks between the surfaces; a plurality of micro-holograms each contained in a corresponding one of the volumes; and, at least one groove in at least one of the surfaces and being operative to diffract light through the at least one surface and into the volumes; wherein, the presence or absence of a micro-hologram in a stacked layer in each of the volumes is indicative of a corresponding portion of data stored.

Abstract: To provide an optical recording method, optical recording apparatus and optical recording medium, capable of effective control of light irradiation position, such as focusing control or tracking control, at the time of recording or reproducing and efficiently adjusting the light irradiation position control according to variations in distance between layers in an optical recording medium or according to manufacturing errors in optical recording and reproducing apparatus, the method including applying at least one of an information light and a reference light to an optical recording medium for detection and control of focus positions of the information light and reference light in a thickness direction of the optical recording medium; and applying the information light and reference light to form an interference image to be recorded in a recording layer provided in the optical recording medium, wherein information is recorded in the recording layer by holography.

Abstract: A method and an apparatus for recording at least two multiplexed holograms. Either an object beam or a reference beam is reflected from an aspherical reflecting surface. Either the reference beam impinging on a recording media at the selected storage location or the object beam impinging on the recording media at the selected storage location is rotated through a selected azimuthal angle about an axis that passes through a plane defined by the intersection of the object beam and the reference beam in the recording media, wherein an angle between the object beam and the reference beam impinging on the recording media is preserved.

Abstract: There are provided: an optical recording method containing a deviation detecting step, a horizontal location controlling step, and an interference image recording step; an optical recording apparatus containing a derivation detecting unit, a horizontal location controlling unit, and an interference image recording unit; an optical recording medium recorded in accordance with the optical recording method; and an optical reproducing method reproducing a recorded information recorded in accordance with the optical recording method.

Abstract: A holographic memory system is disclosed. The holographic memory system comprises: a light source configured to generate a light beam; a photosensitive holographic storage medium configured to at least partially reflect the light beam; and an alignment module configured to determine an angular orientation of the storage medium based on the reflected light beam.

Abstract: A method for reproducing a hologram includes: irradiating a recording disc with a first reference beam and a second reference beam, both having a parallel light flux, in different directions at a same incident angle to form a hologram having an unslanted grating pattern in which a grating vector is parallel to a light incident surface of the recording disc; irradiating the hologram with the first reference beam or the second reference beam to extract reproduced light; and detecting a position where an intensity of the reproduced light is maximum.

Abstract: A plate body 2, multiple hologram layers 3 are provided in the thickness direction of the plate body 2, and at least one of the multiple hologram layers 3 is formed of spirally continuous hologram bands 4. Erasure areas 4A and 4B and non-erasure areas 4C and 4D of the hologram band 4 are provided in the length direction of the hologram band 4. Non-erasure areas 4E and 4F of the hologram band 4 are formed on both sides in the direction orthogonal to the length direction of the hologram band 4 in the erasure areas 4A and 4B.

Abstract: A laser converging apparatus comprising: a nonpolarizing hologram element having a first area defined by a numerical aperture corresponding to a thickness of a first protective layer of a first disk medium and a second area inside the first area, the second area defined by a numerical aperture corresponding to a thickness of a second protective layer (>the thickness of the first protective layer) of a second disk medium, the second area having a hologram pattern for diffracting laser light into zero order light and high-order diffracted light having the order of primary or higher; an objective lens having the numerical aperture corresponding to the thickness of the first protective layer, the objective lens converging the laser light having passed through a part of the first area other than the second area and the zero order light having passed through the second area onto an information surface on one side of the first protective layer, the objective lens converging the high-order diffracted light having

Abstract: A recording and reproducing apparatus includes a spatial-light-intensity modulating unit, a spatial-light-phase modulating unit, an optical system that transmits light and leads the light to a hologram recording medium, a converting unit that converts an input data sequence; an amplitude and phase controlling unit that controls, during recording, the spatial-light-intensity modulating unit and the spatial-light-phase modulating unit to generate a signal light and a reference light, and controls, during reproduction, light intensity of each of pixels in a reference light area and a signal light area and controls a phase of each of the pixels, an image-signal acquiring unit that receives the reproduced image and the DC light and obtains two kinds of image signals, a difference calculating unit that calculates a difference between the two kinds of image signals, and a decoding unit that decodes data formed by a combination of the two kinds of values.

Abstract: A method of recording holographic information and an apparatus for recording/reproducing holographic information. The method includes: forming an information layer by recording a hologram on a holographic recording layer of a holographic information storage medium; and fixing the information layer on which the hologram is recorded, by radiating light on the information layer.

Abstract: To accomplish the object, the invention provides a record medium including a plate body 2; multiple hologram layers 3 formed in the thickness direction of the plate body 2; and hologram bands 4 formed in at least one of the multiple hologram layers 3. The hologram band 4 is formed with erasure areas 4A and 4B of the hologram band 4 with no hologram band 4 in the direction orthogonal to the length direction of the hologram band 4.

Abstract: A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroelectric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.

Abstract: An optical information reproducing apparatus and an optical information reproducing method using the same are provided. The optical information reproducing apparatus includes: a light source; a beam splitter which splits a beam emitted from the light source into a reference beam and a temporary beam; a temporary beam splitter which splits the temporary beam into a pair of assistant beams; an incident optical system which inputs the reference beam and the assistant beams to a recording medium in which optical information is recorded; a reproduction beam detector which detects reproduction beams reproduced in response to the reference beam, sets the position of the reproduction beam having the largest light intensity as a reference position, and sets a signal region on the basis of the reference beam; and an assistant beam detector which compares the light intensity of the assistant beams incident on the signal region with each other and sets an incident angle of the reference beam.

Abstract: An optical information processing apparatus is provided. The optical information processing apparatus includes: an optical system which irradiates a reference beam on an optical information recording medium having a plurality of recording regions adjacent to each other so that the reference beam is wider than each of the recording regions; a filter which filters readout beams reproduced from the optical information recording medium to pass a selected readout beam reproduced from a selected recording region and separates neighborhood readout beams reproduced from neighborhood of the selected recording regions; a readout beam detector which detects the selected readout beam passing through the filter; a neighborhood readout beam detector which detects the neighborhood readout beams separated by the filter; and a controller which compares the neighborhood readout beams detected by the neighborhood readout beam detector to control a reproduction condition of the selected readout beam.

Abstract: In holographic recording by the angle multiplexing method, in order to allow a signal beam and a reference beam to sufficiently overlap with each other in a storage medium to decrease as much as possible a wastefully exposed region, which does not contribute to a signal recording, an optical pickup apparatus having a function which can control, for example, a size or a position of an aperture of the reference beam is used. An optical information reproducing apparatus or an optical information recording and reproducing apparatus using the optical pickup apparatus is used.

Abstract: A holographic storage media incorporates a holographic recording layer for storing holographic data and a DVD reflective layer for storing control information. The DVD reflective layer is positioned within the holographic storage media relative to the holographic recording layer to enable individual optical access to the holographic recording layer via a data laser light for processing the holographic data and individual optical access to the DVD reflective layer via an information laser light for processing the control information. The holographic recording layer and the DVD reflective layer may be physically separated by one or more intermediate reflective layers. The data laser light and the information laser light may differ in one or more optical characteristics. The holographic recording layer and the DVD reflective layer may be optically accessed by the respective laser lights through different light transparent faces of the holographic storage media.

Abstract: A system and method for recording and reproducing holographic interferogram with servos. A servo process is provided by the system and method to continuously record a holographic interferogram in a holographic recording medium with servo trace layers. Also, by the servo process, the intensity distribution of a reference beam is monitored, which is reflected by a reflecting mirror disposed on the other side of the holographic recording medium. By analyzing the distribution, one can adjust the distance and the incidence angle between the reflection mirror and the reference beam. Moreover, a plurality of servo tracks on different layers are provided for recording the holographic interferogram on different layers of holographic recording medium.

Abstract: A reading device for holographic storage includes a light source, a light-directing component, an optical sensor and a prism. The light-directing component is disposed on the transmission path of the light beam provided by the light source and directs the light beam to get incidence at a holographic storage medium in a reading angle to generate a data beam. The optical sensor is suitable for reading the data beam and reproducing stored data. The prism is disposed between the light source and the holographic storage medium and rotatable about a rotation axis perpendicular to the transmission path of the light beam for fine-adjusting the reading angle. The prism and the light beam satisfy the following formula: ?{square root over (n2?sin2I1)}×sin A?cos A sin I1<1 I1 is the angle of incidence of the light beam, A is the vertex angle between the light incident surface and the light emerging surface and n is the refractive index of the prism.

Abstract: Provided is an apparatus and method for recording data on a holographic storage medium. The apparatus includes: a light a light processing unit comprising the holographic storage medium and a light modulator, and recording data on the holographic storage medium using a reference beam and a signal beam modulated by the light modulator; and a control unit controlling the light processing unit to record the data on the holographic storage medium, wherein the light modulator is arranged so that an image formed on a surface of the light modulator is shorter in a radial direction that is a scanning direction of the reference beam than in a tangential direction that is perpendicular to the radial direction.

Abstract: Provided is a hologram retrieval method and a holographic recording and reproducing apparatus for preventing an increase in SNR, a decrease in retrieval accuracy, or the retrieval itself from being made impossible, which would otherwise occur because of a small size of data used for retrieval. Digital information is recorded on a holographic recording medium as data pages DP formed of a two-dimensional bit map image with each page being multiplexed. The data page DP is divided into a plurality of equal data blocks DB11 to 13, DB21 to DB23, and DB31 to DB33, and each data block DB is provided with a data image that is encoded by an encoding method for providing a certain number of ON pixels within each data block DB. A spatial light modulator allows the to-be-retrieved data image to be encoded by the encoding method and displayed as block information on a retrieval data block associated with the data block, and a signal beam to be thereby modulated.

Abstract: A compound objective lens is composed of a hologram lens or transmitting a part of incident light without any diffraction to form a beam of transmitted light and diffracting a remaining part of the incident light to form a beam of first-order diffracted light, and an objective lens for converging the transmitted light to form a first converging spot on a front surface of a thin type of first information medium and converging the diffracted light to form a second converging spot on a front surface of a thick type of second information medium. Because the hologram selectively functions as a concave lens for the diffracted light, a curvature of the transmitted light differs from that of the diffracted light.