Abstract: A holographic recording medium with an improved servo structure is presented. The holographic recording medium has a hologram layer for storing holograms and a servo layer for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium. The servo layer is an essentially flat dye recording layer. A holographic pickup for use with such a holographic recording medium includes a light source for generating a light beam, which interacts with the dye recording layer for recording servo information.

Abstract: An optical information recording and reproducing apparatus includes an optical pickup, a phase conjugate optical system, a disc cure optical system, and a defect discrimination optical system; and an optical detector that receives a light emitted from the defect discrimination optical system and transmitted through or reflected from an optical information recording medium. A reference light and a signal light emitted from the optical pickup are irradiated onto the optical information recording medium to record and reproduce digital information by using a holography.

Abstract: In a beam applying method, recording and reproducing operations are performed on an optical recording medium, in which a signal is recorded and reproduced by applying a beam thereto and which has a recording layer on which the signal is recorded, a quarter-wavelength plate formed below the recording layer, a polarizing plate formed further below the quarter-wavelength plate, and a reflecting film formed below the quarter-wavelength plate. The beam applying method includes the steps of; emitting a beam to be applied to the optical recording medium; and driving a quarter-wavelength plate inserted into an optical system serving to guide the emitted beam to the optical recording medium so that the optical axis direction thereof has a predetermined angle difference at the time of performing a recording operation and reproduction.

Abstract: A marker selection method includes: a marker generation step for generating a marker defining a position reference when recording data according to the modulation rule of the hologram recording/reproduction; a calculation step for calculating a correlation value indicating the correlation between a template image indicating a maker and each of a first verification image containing the marker shifted by a predetermined pixel and a second verification image containing data; and a selection step for selecting such a marker that the peak of the correlation value in the first verification image becomes greater than the peak of the correlation value in the second verification image. The selected marker is used as marker data in a marker generator in a recording processing circuit during recoding and as template data of the template matching processing circuit in the reproduction processing circuit during reproduction.

Abstract: Signal processing techniques are applied to digital image data to remove the distortion caused by motion of the camera, or the movement of the subject being photographed, or defective optics, or optical distortion from other sources. When the image is captured, the effect of relative motion between the camera and the subject is that it transforms the true image into a blurred image according to a 2-dimensional transfer function. The 2-dimensional transfer function representing the motion is derived using blind estimation techniques or by using information from sensors that detect the motion. The transfer function is inverted and used to define a corrective filter. The filter is applied to the image and the blur due to the motion is removed, restoring the correct image. Another embodiment uses the transfer function to avoid blur by combining multiple consecutive images taken at a fast shutter speed.

Abstract: Then, in order to achieve the above-described object, in the optical disk of the present invention, while micro-hologram layers 7 and 8 made of plural layers are provided in an inner portion of a plate body 2 along a thickness direction of the plate body 2, dimensions of micro-holograms 4 along the thickness direction of the plate body 2, which configure the micro-hologram layer 7 formed on the side of one surface of the plate body 2 within the micro-hologram layers 7 and 8 constructed of the plural layers, are made smaller than dimensions of micro-holograms 3 along the thickness direction of the plate body 2, which configure a micro-hologram layer 8 formed on the side of an inner layer of the plate body 2.

Abstract: Signal processing techniques are applied to digital image data to remove the distortion caused by motion of the camera, or the movement of the subject being photographed, or defective optics, or optical distortion from other sources. When the image is captured, the effect of relative motion between the camera and the subject is that it transforms the true image into a blurred image according to a 2-dimensional transfer function. The 2-dimensional transfer function representing the motion is derived using blind estimation techniques or by using information from sensors that detect the motion. The transfer function is inverted and used to define a corrective filter. The filter is applied to the image and the blur due to the motion is removed, restoring the correct image. Another embodiment uses the transfer function to avoid blur by combining multiple consecutive images taken at a fast shutter speed.

Abstract: A defect entry, including position information of a defective block of a reference information layer and state information indicating the defective state of blocks of the other information layers located adjacent to a perpendicular direction at a position of the defective block of the reference information layer, is recorded on a holographic information storage medium. A method of inspecting for a defect includes determining whether blocks in a reference information layer are defective, and determining whether blocks of the other information layers located adjacent to a perpendicular direction at a position of a defective block of the reference information layer are defective, based on a result of the defect determination of the reference information layer.

Abstract: Provided are a method and apparatus for recording/reproducing holographic information. The apparatus for recording/reproducing holographic information includes an optical pickup which irradiates light on a holographic information storage medium and receives irradiated light, wherein the optical pickup comprises a focusing optical system having a numerical aperture (NA) during recording that is lower than the NA during reproduction.

Abstract: A driving apparatus, a driving method and a liquid crystal display (LCD) using the same are provided, wherein the method includes the following steps of: setting a color display sequence, wherein the color display sequence is RGBG, RGRB or RBGB; alternately reading frame data from a first frame register and a second register according to a frame period having three field periods; and sequentially displaying four color data in a cycle period having four field periods according to the color display sequence and the read frame data. By utilizing the method in the present invention, color loss of a field sequential color display occurred in a lower temperature environment is improved.

Abstract: The present invention discloses a wavelength-multiplex and space-multiplex holographic storage device, which comprises a storage medium, a plurality of signal light beams and at least one reference light beam. The signal light beams have different wavelengths and illuminate the storage medium. The reference light beam illuminates the storage medium and interferes with the signal light beams to form a plurality of interference patterns. The interference patterns are respectively stored on different-depth storage layers of the storage medium. The present invention not only has a high access rate but also has a large storage capacity.

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 method for storing data on a storage medium is provided. The method includes receiving a modulated bitstream, wherein the modulated bitstream comprises a plurality of bits comprising a bitstate of 1 and 0. The method also includes secondary modulating each of the plurality of bits comprising the bitstate of 1 to output a plurality of secondary modulated bits. The method further includes forming a plurality of marks in the storage medium, the marks indicative of each of the plurality of secondary modulated bits and the plurality of bits comprising the bitstate of 0 in the modulated bitstream.

Abstract: A need to effectively record data of various sizes on a large-capacity holographic memory capable of high-speed recording is achieved, for example, by curing a first part of the holographic recording which is able to be multiplex-recorded in one or more units of a predetermined volume, and by not recording/curing a second part which is not able to be multiplex-recorded in a predetermined volume at a timing when the first recording part is cured. Also the above need can be achieved by, another example, by adding dummy data to the second part. Alternatively, the second part can be recorded on another track, in which it is possible to record in different units, e.g. by bit recording in a track that utilizes a DVD recording format. According to the present examples, we can record data of various sizes on the holographic memory effectively while performing large-capacity and high-speed holographic recording.

Abstract: An optical recording device includes a light source, a spatial light modulator, a correcting optical system and a light guiding section. The spatial light modulator includes plural pixels, a signal light region that displays a signal light pattern, and a reference light region that displays a reference light pattern. The spatial light modulator modulates and outputs incident light for each pixel in accordance with a display pattern. The correcting optical system includes a pair of axicon lenses that correct the emitted light from the light source so as to flatten the light intensity distribution thereof on an irradiated surface of the spatial light modulator. The light guiding section guides the corrected light to the spatial light modulator. The signal light and the reference light are irradiated onto an optical recording medium simultaneously and a hologram is recorded into the optical recording medium.

Abstract: When recording/reproducing an information recording medium having a plurality of information recording layers, a photodetector receives reflected light from a recording layer which is being recorded/reproduced, as well as reflected light from another recording layer which is not being recorded/reproduced, making it difficult to appropriately detect control signals during a recording/reproducing operation. The present invention employs a polarization hologram element so that the polarization direction of 0th-order diffracted light and that of 1st-order diffracted light are made to be orthogonal to each other before light reflected from an information recording medium is incident upon the detector. Thus, it is possible to reduce the influence of interference with light from the other recording layer and to obtain appropriate control signals, thereby realizing an optical pickup device with desirable recording capability.

Abstract: A method and system for bulk erasing in a holographic storage system is disclosed. The method may involve illuminating the entire volume storage region of a photorefractive crystal with a laser to achieve bulk erasure, or may involve selective erasure of a portion of a single written page. For bulk erasure of the entire photorefractive crystal the use of a separate laser or an incoherent light source is used.

Abstract: A hologram recording and reproducing device controls an optical beam output from an external cavity semiconductor laser to improve a diffraction efficiency. The hologram recording and reproducing device includes an external cavity laser, a photodiode, a laser drive circuit and a laser diode controller. The external cavity laser has a laser diode adapted to emit an optical beam that is used to generate data light and reference light with which a hologram recording medium is irradiated. The photodiode detects the amount of the optical beam output from the external cavity laser. The laser drive circuit supplies a current to the external cavity laser. The laser diode controller controls the laser drive circuit to ensure that a value obtained by integrating the detected intensity of the optical beam with respect to time over a predetermined period is equal to predetermined recording energy.

Abstract: An optical information recording and reproducing apparatus relating to the invention employs a two-beam interference method. In the optical information recording and reproducing apparatus, a moving device moves an information recording medium between a recording and reproducing position and a retracting position, and a mirror moves together with the information recording medium. When the information recording medium moves to the recording and reproducing position, the mirror moves to a position which is displaced from the at least one of the reference beam and the information beam. When the information recording medium moves to the retracting position, the mirror moves to a position where the mirror can reflect the at least one of the reference beam and the information beam toward a detector for detecting a deviation of the at least one of the reference beam and the information beam.

Abstract: A reading device includes a spatial light modulator, a zoom lens set, an object lens, an image sensor, and an adjusting module. The spatial light modulator provides a reading beam. The zoom lens set forms the reading beam into a real image. The object lens focuses the real image onto a collinear holographic storage medium and thus produces a diffraction signal. The image sensor converts the diffraction signal into an electric signal. The adjusting module adjusts the optical magnification of the zoom lens set according to the quality of the diffraction signal.

Abstract: A holographic recording and reproduction system includes a servo optical path, which is used to provide a servo mechanism, so that holographic interference fringes can be stored continuously into a holographic recording medium, and when the reproduction signals are desired, they can be fetched and obtained swiftly and accurately by making use of the servo mechanism. In addition, the servo light spot of the servo optical path is located on the optical axis of an object lens, thus reducing the image aberrations produced and raising the quality of the signals read for the servo track searching. Moreover, the light intensity distribution of the reference beams reflected by the holographic recording medium is monitored and controlled, as such realizing the analysis and adjustment of the relative distance and inclination angle between the holographic recording and reproduction system and the holographic recording medium.

Abstract: A system for processing information is provided. The system includes multiple micro-holograms contained in multiple volumes arranged along multiple tracks in one or more storage mediums. Each of the micro-hologram includes a data. The system also includes one or more pick-up head devices with optical lenses for directing laser beams on the multiple tracks. Further, the system includes a subsystem for arranging the one or more pick-up head devices for recording and retrieving of the data from the one or more storage mediums.

Abstract: An apparatus for reading from or writing to holographic storage media, and more specifically a common aperture type apparatus for reading from or writing to holographic storage media with multiple reference beams having a reduced noise. In a common aperture type apparatus for reading from or writing to a holographic storage medium using shift-multiplexing, with a coaxial arrangement of two or more reference beams and an object beam or a reconstructed object beam, the reference beams being arranged around the object beam or the reconstructed object beam in a storage layer of the holographic storage medium. Each of the reference beams is located essentially halfway between two adjacent central peaks of shift-multiplexed holograms.

Abstract: In the specification and drawings, a collinear holographic storage method is described and shown with a controlling step to control the temperature of the collinear holographic storage media such that the writing temperature of the collinear holographic storage media is from between about 5° C. to about 50° C. higher than the reading temperature of the collinear holographic storage media.

Abstract: The invention relates to a data support (1) with a core layer (15) and at least one adjacent layer (14a), laminated to the core layer and a corresponding production method, said core layer being embodied from a holographic data store in the form of a volume hologram (5). The surface (141) facing the core layer, on the layer directly adjacent to the core layer, has a roughness (19), before lamination to the core layer, which affects the wavelength shift of the image reconstructed by the volume hologram.

Abstract: A holographic recording method includes the following steps: irradiating an optical recording medium with a coherent reference beam and a coherent information beam to produce a hologram in the optical recording medium while irradiating the optical recording medium with an incoherent pretreatment beam to consume a polymerization inhibitor; irradiating the hologram with the reference beam to extract a reproduction beam while stopping irradiating the optical recording medium with the reference beam; sensing the signal beam with an image pick-up unit to detect an intensity of the signal beam; and calculating a bit error rate with a control unit to irradiate the hologram with the information beam if the bit error rate is larger than a prescribed value, or to stop irradiating the optical recording medium with the reference beam, the information beam and the pretreatment beam if the bit error rate is smaller than the prescribed value.

Abstract: A dual-path optical recording medium and an apparatus for accessing such are disclosed. The dual-path optical recording medium includes a substrate, an intermediate recording layer, a holographic recording layer and a dichronic mirror layer. The intermediate recording layer is a rewritable data storage layer with a relatively low storage capacity. The holographic recording layer is a write-once data storage layer with a relatively high storage capacity. The dichronic mirror layer is located between the holographic recording layer and the intermediate recording layer. The apparatus for accessing the dual-path optical recording medium includes a first light module capable of generating a first laser light, and a second light module capable of generating a second laser light.

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: A laser converging apparatus includes a polarizing 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. A wavelength selecting nonpolarizing hologram element has a third area defined by a numerical aperture corresponding to a thickness of a third protective layer (>the thickness of the first protective layer) of a third disk medium. The laser converging apparatus also includes an objective lens having the numerical aperture corresponding to the thickness of the first protective layer, and a holder that holds the polarizing hologram element, the nonpolarizing hologram element, and the objective lens.

Abstract: A holographic information recording and/or reproducing apparatus including: a light source unit emitting reference light and signal light; a first optical path guiding unit guiding the lights to cross; a second optical path guiding unit including a first polarization converter located on an optical path of one of the reference and signal lights, a first polarization beam splitter located at a crossing point of the reference light and the signal light, an optical path converter guiding the reference light and the signal light so that they cross again, a second polarization converter located on an optical path of the signal light before the signal light crosses the reference light, and a second polarization beam splitter uniting the optical paths of the reference light and the signal light; and an objective lens unit illuminating the reference light and the signal light onto one side of a holographic information storage medium.

Abstract: A holographic recording apparatus is provided and includes: a signal light generation section that generates signal light modulated according to digital data; a reference light generation section that generates reference light modulated by means of a pixel pitch; a adding section that adds, in proximity to a light-convergence position where the signal light and the reference light come close to each other or overlap each other, a low-order component of the signal light obtained by Fourier transform and a high-order component of the reference light obtained by Fourier transform, the high-order component of the reference light having a spatial frequency region differing from that of the low-order component of the signal light; and an illumination optical system that irradiate an optical recording medium with the added signal and reference light.

Abstract: In an information storage device in which small partitions for storing information are three-dimensionally placed inside a solid, the invention aims at long-period storage, robustness, and rapid information reading. Accordingly, the stored three-dimensional information is divided into two-dimensional data for each layer, and two-dimensional inverse Fourier transform is previously applied for the two-dimensional data. The two-dimensional data is recorded in each layer in a Z direction inside a storage medium which is solid. When the information is reproduced, electromagnetic waves are irradiated to a storage area MA as gradually rotating the storage area MA around a z axis, and projection images of all layers during the rotation are obtained from response. By applying one-dimensional Fourier transform for a plurality of projection images obtained as described above, the recorded original three-dimensional information is rapidly reproduced.

Abstract: A holographic information recording and/or reproducing apparatus includes: a light source to emit light; a polarization conversion device to form a polarized signal beam and an orthogonal polarized reference beam; an optical path forming optical system to separate the optical paths of the signal beam and the reference beam; a focus adjustment optical system disposed on the optical path of at least one of the signal beam and the reference beam, and to vary a position of a focus of at least one of the signal beam and the reference beam in a depth direction of the holographic information storage medium; an objective lens to focus the signal beam and the reference beam in the holographic information storage medium, and form an interference pattern to record information; and a 4f relay system disposed on an optical path between the focus adjustment optical system and the objective lens.

Abstract: An optical pickup for recording a hologram by using an angle multiplexing method. An optical beam is separated into two beams, a signal beam and a reference beam having different convergence/divergence degrees, by using an optical component such as a diffraction lens. The signal and reference beams are made incident upon the same objective, and the optical component or the objective lens is moved in a direction perpendicular to an optical axis, to thereby realize angle multiplex recording. If an optical information recording medium is inclined, the optical component or the objective lens is moved along the direction along which the optical information recording medium moved to change an angle of the reference beam incident upon the optical information recording medium and compensate for degradation of a reproduction signal.

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: The present invention relates to a method for performing pre-exposure and curing of a photo-sensitive material for optical data storage, in particular for holographic data storage, and to an apparatus for writing to optical storage media using such method. According to the invention, for pre-exposure and/or curing of an optical storage medium the optical storage medium is illuminated by a coherent light beam emitted by a light source, which is also used for data recording. Pre-exposure and/or curing is performed in one or more exposure steps, in which the coherent light beam carries a data pattern, the exposure dose for each exposure step being smaller than a minimum dose such that the diffraction efficiency of the recorded data pattern is too low to distinguish data from noise.

Abstract: A data processing method for a holographic data storage system includes in a writing operation, receiving a plurality of digital data groups; modulating the digital data groups to a plurality of corresponding digital matrixes, wherein each of the digital matrix comprises a digital data group and a plurality of digital redundancies; arraying the digital matrixes on a data plane to form an image information, wherein the image information has more opaque pixels than transparent pixels; and storing the image information in a storage medium; and in a reading operation, receiving the image information; transforming the image information into a plurality of analog matrixes, wherein each of the analog matrixes comprises an analog data portion and an analog redundancy portion; demodulating the analog matrixes to a plurality of corresponding analog data groups; and transforming the analog data groups into a plurality of digital data groups by using a soft decision apparatus.

Abstract: A recording apparatus for performing recording on a hologram recording medium includes a first light source configured to output first laser light having a first wavelength; a second light source configured to output second laser light having a second wavelength differing from the first wavelength; a recorder configured to perform data recording in units of hologram pages on the data recording layer of the hologram recording medium in such a manner that a recording data sequence is converted into a data pattern in units of hologram pages, the signal light is generated by performing space light modulation on the first laser light on the basis of the data pattern; a reflected light detector configured to irradiate the hologram recording medium with the second laser light; a position controller configured to perform position control; and a recording controller configured to perform control on the recorder.

Abstract: An optical pickup apparatus includes: a light source to irradiate light onto a hologram recording medium onto which information is recorded by interference fringes of signal light and reference light; a spatial light modulation portion to generate the reference light by performing a spatial light modulation on the light from the light source; and an optical system to irradiate the reference light onto the hologram recording medium via a relay lens system and an objective lens and guide reproduction light obtained from the hologram recording medium in accordance with the irradiation of the reference light to an image pickup device via the objective lens and the relay lens system, the optical system being provided with, in an optical path between the relay lens system and the image pickup device, an angle permselective device that selectively transmits light with an incidence angle of a predetermined angle or less.

Abstract: A method using an optical holographic data storage medium and an optical holographic data storage drive, comprising removeably disposing the optical holographic data storage medium in the optical holographic data storage drive, and determining whether to write information to the holographic data storage layer, and/or whether to read information from the holographic data storage layer, and/or whether to write information to the optical data storage layer, and/or whether to read information from the optical data storage layer. The optical holographic data storage medium comprises a holographic data storage layer and an optical data storage layer. The optical holographic data storage drive comprises a reflective spatial light modulator, a first lasing device, a first optical detector for detecting first laser light, a second lasing device, and a second optical detector for detecting second laser light.

Abstract: A method to store information in a holographic data storage medium, wherein the method supplies a holographic data storage medium comprising an encoded focusing hologram and one or more encoded data holograms. The method disposes the holographic data storage medium in a holographic data storage system, and disposes a rotatable imaging lens at an (i)th orientation. The method illuminates the encoded focusing hologram to generate an (i)th reconstructed focusing image, projects that (i)th reconstructed focusing image through the rotatable imaging lens, and onto at optical detector array. The method then calculates an (i)th measured focusing metric, and determines if the (i)th measured focusing metric is greater than or equal to the threshold focusing metric. If the (i)th measured focusing metric is greater than or equal to the threshold focusing metric, then the method decodes the one or more encoded data holograms.

Abstract: There are provided: an optical recording method containing a focus point controlling step, and an interference image recording step; an optical recording apparatus containing a focus point 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: In holographic recording, it is important to form stably an interference fringe between a reference beam and a signal beam in a holographic storage medium. To suppress factors degrading stability of the interference fringe, such as fluctuation of atmospheric air, position displacement of optical components and the like during propagation of the reference and signal beams, an optical pickup and an optical information recording/reproducing apparatus adopt an optical system structure providing a higher proportion of optical components shared by the reference and signal beams optical path than conventional optical system structure. To increase the proportion of shared optical components, the signal beam and the reference beam pass through the PBS prism as parallel beams and a concave lens is placed on a reference beam path just before the objective lens.

Abstract: A holographic data storage (HDS) system and method are provided. Generally, the system includes: a light source for generating a coherent light; beam-forming optics for forming the light into collimated object and reference beams; holographic storage medium; a spatial light modulator (SLM) located in a path of the object beam from the beam-forming optics to the storage medium, the SLM having a number of pixels for encoding data to be stored in the medium into the object beam. Preferably, the SLM can modulate both the amplitude and phase of light from every pixel on the SLM. More preferably, the SLM is also located in a path of the reference beam to the storage medium to modulate the phase of the light to store multiple holographic pages of data in the same physical volume of medium through phase multiplexing. Other embodiments are also described.

Abstract: A method to set a rotation rate for an optical holographic data storage medium by determining if the optical storage layer comprises an alternating series of lands and grooves. If the optical storage layer does not comprise an alternating series of lands and grooves, the method rotates the optical holographic data storage medium at a rotation rate based upon a data acquisition rate for pit-recorded information. If the optical storage layer comprises an alternating series of lands and grooves and the distance between alternating grooves increases as a function of the distance from said center point, then the method rotates the optical holographic data storage medium at a constant angular velocity. If the distance between alternating grooves does not increase as a function of the distance from said center point, then the method rotates the optical holographic data storage medium at a constant linear velocity.

Abstract: A portable data storage assembly, comprising a holographic data storage layer, and an optical tracking layer comprising addressing information for the holographic data storage layer, wherein that addressing information defines a first storage band comprising a first plurality of storage addresses and a second storage band comprising a second plurality of storage addresses, wherein said second plurality of storage addresses is greater than said first plurality of storage addresses.

Abstract: According to one embodiment, an optical information recording apparatus includes a spatial light modulator, an optical mechanism, a driving module, and a controller. The spatial light modulator converts an irradiation beam emitted from a light source to plural partial information beams that carry information by causing the irradiation beam to pass through plural modulation areas. The optical mechanism collects the partial information beams onto an optical information recording medium and applies a reference beam onto the recording medium such that the reference beam and the partial information beams intersect with each other on an information recording layer. The driving module drives the recording medium or the optical mechanism. The controller performs angle multiplex recording of information on the information recording layer by controlling the driving module and causing the light source to emit the irradiation beam while switchingly supplying the modulation areas with the information.

Abstract: The present invention provides an optical recording method including: recording information on a recording layer for holographically recording information in an optical recording medium by irradiating the optical recording medium with an information beam and a reference beam, and repetitively recording information on the recording layer while moving at least any one of the information beam and reference beam and the recording layer along the surface of the recording layer, thereby being capable of shift-multiplex recording operations, wherein the optical recording medium is irradiated on a recording pulse basis, the peak intensity of light of the recording pulse is 0.1 mW to 100 mW, the irradiation time is 0.05 nsec to 1×105 nsec, and the irradiation of recording pulse is performed 5 times to 1×107 times per 1 msec; and also provides an optical recording apparatus and an optical recording medium.

Abstract: The invention relates to a method for reading a Fourier hologram recorded on a holographic storage medium with a holographic storage system. The method comprises the steps of: —calculating a characteristic value from a detected image of a reconstructed Fourier hologram in at least two relative positions of a reference beam and said storage medium, each of the characteristic values being indicative of a misalignment of the reference beam and said storage medium at the respective relative position, —calculating a servo value from the measured characteristic values, —determining an aligned relative position of said reference beam and said storage medium by means of a predetermined servo function using the calculated servo value, —setting the relative position of the reference beam and said storage medium to said aligned relative position, and—detecting an image at said aligned relative position.

Abstract: There is provided an optical information detecting method. The method includes: detecting an image of a source data page coded with balanced codewords by the use of 1:N (where N is greater than 1) excessive detection pixels; determining a distribution pattern of valid detection pixels and invalid detection pixels to be corrected in the detected image by the use of a light intensity distribution of the detected image; and dividing the detected image into balanced codeword detecting areas corresponding to the balanced codewords and sampling data of the balanced codeword detecting areas by the use of the determined distribution pattern and an optical distribution characteristic of the balanced codewords. Accordingly, it is possible to efficiently detect optical information by the use of a 1:N over-sampling method. Specifically, the distribution pattern of valid detection pixels and invalid detection pixels in the detected image of a data page can be properly used to sample a balanced code.