Abstract: A hologram recording method includes eliminating a DC component from a Fourier transformation image of a signal light for expressing binary digital data as a brightness image, and irradiating an optical recording medium simultaneously with the signal light from which the DC component has been eliminated and a reference light to record an image edge portion of the signal light onto the optical recording medium as a hologram.

Abstract: The shaping of pixels of a data page for holographic recording, a holographic recording medium including data pages with shaped pixels, and apparatuses for writing to or reading from such holographic recording media are disclosed. A device for modulating a light beam to generate a data page having a plurality of pixels applies a spatially varying pixel size over the data page. An apparatus for writing to holographic recording media includes such a device for modulating a light beam, while an apparatus for reading from holographic recording media includes an adapted detector for detecting the data page having a plurality of pixels with a spatially varying pixel size.

Abstract: A recording apparatus includes a first light source irradiating first laser light, a second light source irradiating second laser light, an optical spatial modulating unit applying information to the first laser light, and an objective lens collecting the first laser light and the second laser light at different positions on the same optical axis. A hologram recording operation uses a first optical path and a second optical path. The information light is conducted to the objective lens along the first optical path. The reference light is conducted to the objective lens along the second optical path. At the same time, an address/servo control operation is carried out by employing a third optical path along which the second laser light is conducted to the objective lens. The DVD recording operation uses the second optical path. The CD recording operation uses the third optical path.

Abstract: A monocular holographic storage device or system to provide for compact recording and/or reading of data pages in a holographic storage medium. Also provided are methods for carrying out such data storage and/or data recovery using a monocular holographic storage device or system. Further provided are articles comprising holographic storage media for recording or for reading recorded data using such devices or systems.

Abstract: A holographic recording device for multiple recording a plurality of interference fringes of a reference light and intensity-modulated signal lights in a same area or in areas slightly shifted each other of a holographic recording medium is disclosed. The holographic recording device modulates the intensity of a signal light and modulates a phase of the signal light before or after the intensity modulation. A phase distribution of each signal light is changed every time when multiple recording is performed and after each phase modulation, the recording device determines if an assigned multiplicity has been achieved.

Abstract: The present invention relates to a phase mask for holographic data storage, and to a method and an apparatus for reading from and/or writing to holographic storage media using such a phase mask. According to the invention, the phase mask has a plurality of phase cells, whose size is equal to an integer multiple of the size of the pixels of a spatial light modulator of the apparatus. The phase cells have a phase variation on sub-cell scale, which is inverse for essentially half the number of phase cells.

Abstract: A system and a method for holographic storage mainly involve forming a holographic interference pattern in a holographic recording medium. The holographic storage system utilizes a light source to emit a coherent beam. The coherent beam is irradiated to a first reflector to form a divergent beam. The divergent beam is then irradiated to a second reflector to form collimating beams (a signal beam and a reference beam). The signal beam goes through a spatial light modulator (SLM) and is modulated by the SLM. After that, the reference beam and the modulated signal beam are irradiated to a convergent unit, and are directed to the holographic recording medium for forming the holographic interference pattern. The holographic storage system that the light source is split into a signal beam and a reference beam by a set of reflectors according to the reflection principle without involving refraction may employ wavelength multiplexing.

Abstract: A method and system for performing three-dimensional holographic microscopy of an optically trapped structure. The method and system use an inverted optical microscope, a laser source which generates a trapping laser beam wherein the laser beam is focused by an objective lens into a plurality of optical traps. The method and system also use a collimated laser at an imaging wavelength to illuminate the structure created by the optical traps. Imaging light scattered by the optically tapped structure forms holograms that are imaged by a video camera and analyzed by optical formalisms to determine light field to reconstruct 3-D images for analysis and evaluation.

Abstract: An optical information recording apparatus includes a light source that emits an irradiation light; a spatial light modulator that converts the irradiation light to an information light carrying information; a condenser lens that converges the information light and a reference light onto an optical information recording medium on which the information can be recorded as a hologram by an interference fringe formed by an interference between the information light and the reference light; a relay lens that propagates the information light emitted from the spatial light modulator to the condenser lens; and a permeable member, provided between the spatial light modulator and the relay lens, that has a refractive index greater than a refractive index of air and smaller than a refractive index of the relay lens, and refracts and transmits the information light.

Abstract: Hologram recording and reconstruction apparatuses and method thereof are provided. The hologram recording apparatus comprises a laser source, a spatial light modulator, and a Fourier lens. The laser source provides a coherent light beam. The spatial light modulator receives m-bits data to only determine a (p×q) block comprising ON-pixels less than OFF-pixels, and receives the coherent light beam to modulate with the (p×q) block to generate the signal beam. The Fourier lens focuses the signal beam on the hologram recording medium, so that when the focused signal beam and a focused reference beam is modulated together, the hologram data is generated to be recorded on the hologram recording medium.

Abstract: Aspects of the present invention are generally directed to a holographic system. Generally, aspects of the present invention are directed to allocating power of a light beam generated by a coherent light source among the various discrete light beams used in a holographic system. Specifically, a variable optical divider is incorporated into an optical steering subsystem of the holographic memory system to redirect the coherent light beam into one or more discrete light beams, and to dynamically allocate power of the coherent light beam among the discrete light beams.

Abstract: A reference beam is deflected by an angularly rotating mirror, and applied to a hologram recording medium at a set incident angle. The relevant applied reference beam and a signal beam are superposed within the hologram recording medium, and light intensity distribution of the resultant interference fringes is recorded as a hologram. The reference beam incident on the hologram recording medium is partially transmitted through the hologram recording medium. The relevant transmitted reference beam passes through a quarter wave plate to be incident on a hologram element. The relevant incident reference beam has its traveling direction changed into a reverse direction by the hologram element regardless of its incident angle, follows the same optical path as the incoming path, and is applied again to the hologram recording medium.

Abstract: The number M of a plurality of multiplexed recording mediums to be recorded in a projected area S on the surface of a recording medium satisfies the equation (1?) where n represents the refractive index of the recording medium, ? the wavelength in vacuum of light used to record and reproduce information, L the thickness of the recording medium, ±NAR the range of an angular spectrum in air of a reference beam, ±NAS the range of an angular spectrum in air of a reproduced beam applied to a light detector, S the projected area of a recording region to be recorded in one recording cycle onto the surface of the recording medium, N the number of bits to be recorded in one recording cycle, and Z the signal vs. signal noise ratio as a target ratio (Z=3).

Abstract: A holographic recorder (A1) can vary the optical distance between an object lens (8) and a relay lens (7b) near the object lens (8). This arrangement allows defocus-multiplexing utilizing state variations in the laser beam when the beam reaches a storage medium (B1).

Abstract: The present invention relates to a method and apparatus for producing a hologram, in particular a dot matrix volume hologram. A holographic recording system (1) comprises a source of optical radiation (7), a transparent or partially transparent holographic recording medium 6 and an optical system (10). The recording medium (6) has a first side (25), a second side (26) and a recording volume (36), the second side (26) being opposite to said first side (25) and the recording volume (36) being between said sides (25, 26). The recording medium (6) is positioned between the source of optical radiation (7) and the optical system (10) so that the first side (25) is presented towards the source of optical radiation (7) and the second side (26) is presented towards the optical system. The source (7) is arranged to project incident optical radiation (20) onto the first side (25) and through the recording volume (36) towards the optical system (10).

Abstract: A holographic storage and regeneration system includes a holographic recording medium, a light source, a spatial light modulator, and a conjugate servo light guidance portion. The light source generates a signal light and a reference light. The spatial light modulator modulates the incident signal light and makes it incident onto the medium along the incident direction of the signal light. The guidance portion guides a reference light to incident onto the medium in one direction and reflects it in another direction. A reference light and a signal light interfere with each other to produce a holographic interference fringe. The reflected reference light is guided into a first image sensor to be used to analyze the incident angle of the reference light. When the reference light incidents onto the fringe of the medium through the guidance portion in a reverse direction relative to another direction, a conjugate regenerated light is generated.

Abstract: Non-Fourier Transform (FT) plane angular filters and their use in holographic storage systems or devices for angular filtering of a data beam prior to recording holographic data or for angular filtering of a recovered beam prior to detecting the recovered holographic data. The non-FT plane filters may be a macrotube array, an etalon, a multi-layer thin film interference coating on a curved surface, a lenslet array device, a waveguide-like array, or a combination thereof. Also provided are methods for carrying out angular filtering using such filters for data storage and/or data recovery.

Abstract: An actuator includes a rotor, a stator containing the rotor, and a bearing to support the rotor to be rotatable with respect to the stator about the central axis of the rotor and an axis perpendicular to the central axis. The rotor includes rotor central magnetic poles, a rotor upper magnetic pole, and a rotor lower magnetic pole. The stator includes stator central magnetic poles larger in number than the rotor central magnetic poles, stator upper magnetic poles, stator lower magnetic poles, central coils to appropriately magnetize the stator central magnetic poles, upper coils to appropriately magnetize the stator upper magnetic poles, and lower coils to appropriately magnetize the stator lower magnetic poles. The length of each stator central magnetic pole along a central axis of the stator is larger than a length of each rotor central magnetic pole along the central axis of the rotor.

Abstract: The present invention relates to a device for reading from and/or writing to optical recording media, having a light source for producing a scanning beam for scanning the optical recording medium, detection means for detecting the beam influenced by the optical recording medium, and an optical element arranged in the optical beam path by means of a holder. The optical element has in a plane perpendicular to the axis of the beam path outer boundary lines inclined to one another in such a way as to enable a unique orientation. The holder has a cutout with correspondingly inclined inner boundary lines.

Abstract: A single method and apparatus for producing many of the most common types of hologram from digital data is disclosed. The data are generated entirely by a computer as a 3-D (animated) model or from multiple 2-D camera images taken of a real 3-D (moving) object or scene from a plurality of different camera positions. The data are digitally processed and displayed on a small high resolution spatial light modulator (SLM). A compact low energy pulsed laser, is used to record composite holograms. The present invention permits the creation of restricted or full parallax master transmission or reflection type composite holograms, known as H1 holograms, that can be copied using traditional methods. Alternatively the same invention and apparatus permits the direct writing of hologram without the need to pass through the intermediate stage of the H1 transmission hologram.

Abstract: A hologram information reproducing device is described which can reproduce information from a recording medium on which hologram information is recorded, and which can be downsized. In one aspect, when light from a light source is emitted, the light is converted into parallel reference light, by a lens of an optical system. A mirror changes the orientation of the reference light so that it is oriented obliquely downward towards a recording medium. More specifically, as viewed from the top, the mirror changes a path of the light from the light source unit by approximately 90 degrees. In addition, as viewed from the side, the mirror changes the path of the light from the light source unit downward by approximately 45 degrees. Since an interference pattern recorded on the recording medium is a Bragg grating, when the reference light illuminates a recording area of the recording medium, a reproduction light is obtained by Bragg diffraction.

Abstract: A holographic recording system with a simple structure is provided that can make a holographic recording beam follow a recording medium traveling even at high speed. The holographic recording system 10 includes a chopper lens 30 that travels in synchronization with and in a same direction as the holographic recording medium 14. The chopper lens 30 is formed so as to move the axes of incident information and reference beams relative to the recording medium and the chopper lens, and to irradiate them to an identical information recording region 15 in the holographic recording medium 14.

Abstract: A holographic recording and reproducing method for recording data in a holographic recording medium comprising a recording layer in which data are to be recorded as phase information of light by projecting a signal beam and a reference beam thereonto and a servo layer disposed on the opposite side of the recording layer as viewed in the direction of signal beam incidence on the holographic recording medium and having regions in which servo projections are formed by projecting the signal beam and the reference beam onto the holographic recording medium and reproducing holographic data from the holographic recording medium by projecting the reference beam onto the holographic recording medium, the holographic recording and reproducing method includes steps of setting an optical path of the signal beam so that the signal beam is projected onto other regions of the servo layer than the regions formed with the servo projections, setting an optical path of a servo beam different from that of the signal beam so that

Abstract: A monocular holographic storage device or system to provide for compact recording and/or reading of data pages in a holographic storage medium. Also provided are methods for carrying out such data storage and/or data recovery using a monocular holographic storage device or system. Further provided are articles comprising holographic storage media for recording or for reading recorded data using such devices or systems.

Abstract: A hologram recording apparatus (100) includes a record angle change device (19) capable of relatively changing the record angle of a hologram recording medium (200) relative to signal light (L3) and reference light (L2); and a control device (18). The control device sets a record angle for recording a specific angle record plane as a standard record angle among a plurality of angle record planes on the hologram recording medium. Furthermore, the control device controls the record angle change device so as to change and fix the record angle after then by a predetermined angle from the set standard record angle.

Abstract: A new type of FT lens is provided that improves phase conjugation in holographic data systems. This type of FT lens has a uniquely large isoplanatic patch. This enables relaxed assembly tolerances, asymmetric reader/writer architectures, and compensation for tilted plate aberrations in the media.

Abstract: A hologram record apparatus (100) includes a parameter set device (19), a move device (20), and a control device (18). The parameter set device (19) modifies parameters for multiple recordings such as a record angle and a focal depth in relation to at least one of signal light (L3) and reference light (L2) and can fix the parameters. The move device (20) relatively moves the focus position of the signal light and the reference light in the direction along the record surface of a hologram record medium. The control device (18) performs control so that the parameter for the last recording used for recording at the m-th focus position is used as the parameter for the first recording at the m+1-th focus position.

Abstract: Non-mechanical optical beam steering and switching is produced by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency volume Bragg gratings recorded in a photosensitive PTR glass. Small angle beam deflection in a photoactive liquid crystal cell is produced by exposing it to a controlling beam from an external source of radiation with predetermined distribution of power density which causes predetermined spatial gradients of a refractive index in a liquid crystal cell and, therefore, refraction of a controlled beam which is made to propagate in the region with spatial gradient of the refractive index. Large angle beam deflection is produced by a volume Bragg grating with angular selectivity adjusted in such way that small angle scanning produced by optically controlled liquid crystal spatial light modulator results in change of diffraction efficiency from zero to 100% for switching the beam for two Bragg angles.

Abstract: The present invention provides a hologram apparatus for recording interference fringes formed from reference light and signal light optically spatially modulated by a spatial light modulator on a hologram recording material or picking up an image of reproduction signal light produced by irradiating illumination reproduction light on the hologram recording material by means of an image pickup device to obtain a reproduction image signal. The hologram apparatus includes a matching data acquisition section, an arithmetic operation section, and a positioning control section. The matching data acquisition section directly picks up an image of the signal light optically spatially modulated with a pixel matching pattern displayed on the spatial light modulator by means of the image pickup device to obtain a reproduction image signal. The arithmetic operation section performs predetermined arithmetic operation using a luminance value of the reproduction image signal.

Abstract: A method, apparatus, and system provide the ability for storing holograms at high speed. A single laser diode emits a collimated laser beam to both write to and read from a photorefractice crystal. One or more liquid crystal beam steering spatial light modulators (BSSLMs) steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal.

Abstract: The invention is directed to self-referenced holographic recording techniques that make use of an element of a holographic medium to create a reference beam from a zero frequency Fourier component of a data encoded object beam. In other words, the self-referencing element may be formed on the holographic medium, rather then being a separate element of the holographic recording system. The element may comprise a diffusive element on the medium, designed to create a reference beam having controlled angles, phase and/or amplitude.

Abstract: A hologram recording medium in which data is recorded at a high density, the input of a reference beam to an area to which data is not to be recorded of a recording layer is prevented when recording data to the hologram recording medium, and an amount of noise when reproducing the data from the hologram recording medium is reduced. The hologram recording medium includes a light velocity restriction member restricting an incidence area of a hologram recording layer, thus restricting the incidence of a reference beam onto the hologram recording layer, preventing the incidence of the reference beam onto an area to which data is not to be recorded of the hologram recording layer when recording data and reproducing the amount of noise when reproducing data.

Abstract: 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.

Abstract: Disclosed are holographic storage systems and lenses for holographic storage systems. The lens units can be of a two-component design. The lenses can be used to both record to photorefractive storage media and to read from photorefractive storage media.

Abstract: A holographic recording method and a holographic recording apparatus capable of selectively rewriting or erasing only desired data without degrading data other than the desired data are provided. Holograms are multiple recorded per file, and page data in one file is multiple recorded, while page data in one file and page data in another file are not multiple recorded. Therefore, only the desired file can be selectively rewritten or erased without degrading the other files.

Abstract: An optical recording/reproducing apparatus having excellent resistance against vibration and noise. In recording, coherent light is polarization-modulated with a spatial light modulator to generate signal light and reference light whose polarization directions are crossed at right angles. The signal light permeates a polarizing beam splitter, and is incident to a quarter wavelength plate. The reference light passes through a passing hole, is diffused by a light diffuser and is incident to the quarter wavelength plate. The reference and signal light are converted into circularly polarized light which revolve in directions opposite to each other and condensed by a condenser lens, and then a predetermined area of an optical recording medium is irradiated with the reference and signal light. Thus, the reference and signal light are generated by modulating the incident light from the same light source and are coaxially incident to the polarizing beam splitter.

Abstract: A method, apparatus, and system provide the ability for storing holograms at high speed. A single laser diode emits a collimated laser beam to both write to and read from a photorefractice crystal. One or more liquid crystal beam steering spatial light modulators (BSSLMs) or Micro-Electro-Mechanical Systems (MEMS) mirrors steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal.

Abstract: Disclosed are optical systems and methods of producing obliquity corrected light beams, for example, holographic recording and retrieval systems that utilize an obliquity corrected reference beam. One method includes directing a light beam reflected from a prism mirror to a reference plane with an angle of incidence to the reference plane, wherein the prism mirror varies the width of the light beam according to the angle of incidence to the reference plane. The optical system may include a holographic data storage system and the reference plane may be associated with a holographic storage medium.

Abstract: The present invention provides a multi-channel tunable filter and methods for making such a filter. In one embodiment, the filter comprises a bank of gratings imprinted into a filter material, such as Lithium Niobate. In another embodiment, the filter comprises a bank of gratings imprinted on a thin-film filter. An optical read-head comprising a pair of lenses is configured to pass light from within an optical fiber carrying multiple wavelengths through an appropriate grating to extract or drop a specific wavelength. To ensure continuous data transmission, the filter is tuned to a wavelength by configuring the read-head to move in a hitless manner. In one embodiment, the gratings are recorded by the interference of two beams. A first plane wave reflects off a first mirror stack and a second plane wave reflects off a second mirror stack. In another embodiment, the gratings are recorded by a phase masking method.

Abstract: The invention relates to a method of providing an article with identifying information, in which a hologram is provided from which at least first and second hologram patterns separated physically from each other can be reproduced. In this case, provision is made for the hologram to be produced in such a way that the first and second hologram patterns can generally be reproduced in one and the same direction but in different planes.

Abstract: In the method for producing holograms, a plurality of images displayed on a spatial optical modulating element 6 is used as the object light. Through a lens array 7 composed of a plurality of lenses disposed corresponding to each of the images, which are included in the object light, and a reducing optical system 9 and 10 for reducing the object light emitted from the lens array 7, the object light is made to irradiate a recording surface 11 along with a reference light; thereby interference light between the object light and the reference light is recorded on the recording surface 11. Between the spatial optical modulating element 6 and the lens array 7, partitions 15 for separating the respective images are provided; thereby noise is reduced.

Abstract: The invention is directed to a spatial light modulator device that can improve holographic data recording systems, and various methods and systems incorporating the device. The spatial light modulator device includes a diffusive element to diffuse or scatter a data encoded object beam. For example, the diffusive element may comprise a two-layer diffusive laminate formed, a polymer dispersed liquid crystal material, or another diffusive material. The diffusive element can be formed over the output window, or may comprise the output window of the spatial light modulator device. In any case, the diffusive element can slightly scatter the data encoded object beam, which can significantly reduce undesirable zero-order burning effects in a holographic medium positioned in proximity to a Fourier transform plane.

Abstract: A hologram recording apparatus, a hologram recording method and a hologram recording medium reduce noise components generated by a phase modulation type spatial light modulator, thus permitting improved integrity of data to be achieved. A light beam whose diffraction state has been controlled by a diffraction control element is condensed on a hologram recording medium. With this arrangement, a predetermined diffracted light component is removed from a diffracted light beam emergent from the diffraction control element when recording information, which is based on the diffraction state controlled by the diffraction control element, in a hologram recording medium. Thus, noise components when information is recorded can be reduced.

Abstract: The present invention makes it possible to reduce the size of an optical system for multiplex recording or reproduction of information utilizing holography. A pick-up of an optical information recording/reproducing apparatus generates information light by spatially modulating laser light emitted by a laser source device with a spatial light modulator depending on the information to be recorded and generates reference light for recording having a spatially modulated phase by spatially modulating the phase of laser beam emitted by the light source device with a phase-spatial light modulator. The information light and the reference light for recording are projected upon an optical information recording medium such that they converge in different positions, and information is recorded in the hologram layer in the form of an interference pattern as a result of interference between the information light reflected by a reflecting film and the reference light for recording.

Abstract: An apparatus for forming a nano grating device to film nano-scale interference fringes by holography in order to makes a nano-scale meshed structure is disclosed. A beam emitted form a light source passes subsequently through a beam splitter and two reflectors to reach at symmetrically mounted light emitting modules. The light emitting modules generate two beams passing along the same optical paths and then projecting on a photosensitive substrate that is attached on a hemi-sphere lens. Thus, a first set of interference fringes are formed. Then, the substrate rotates with an angle and then is subjected to exposure to form a second set of interference fringes crossing the first set of interference fringes. Thereby, a nano-scale meshed structure is obtained.

Abstract: 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.

Abstract: A lens barrel includes an optical system including a short focal length for a wide angle of view; and an ND filter in the shape of a disc which is provided on an optical axis of the optical system. An optical density of the ND filter decreases in a direction radially outwards from a center of the ND filter.

Abstract: A holographic recording apparatus which can stably record data to be recorded onto a recording medium. The holographic recording apparatus of the present invention includes: a light source for generating a coherent reference light beam; a signal light generation unit including a spatial light modulator for spatially modulating the reference light beam in accordance with information data to generate a signal light beam; an interference unit for directing the signal light beam and the reference light beam toward a recording medium through an objective lens to form a region of a diffraction grating formed by an optical interference pattern within the recording medium; a lens positioning unit for positioning the objective lens with respect to a recording surface of the recording medium; and a light-receiving unit for detecting a returned beam that is returned from the recording medium through the objective lens.

Abstract: A holographic apparatus includes a mask for modulating a signal beam to generate a modulated signal beam; a conical prism, which has a cone portion and a base portion, for refracting a reference beam to generate a refracted reference beam, wherein the refracted reference beam interferes with the modulated signal beam in a holographic medium to thereby record data thereon, the base portion facing the holographic medium. The holographic apparatus can be miniaturized by a positional relationship between the conical prism and the holographic medium.

Abstract: An image detected by a CCD image sensor 108 when only a non-modulated signal light is applied to a holographic memory 120 in which data is not recorded is ensured as a noise pattern. When data is reproduced, the previously obtained noise pattern is subtracted from a reproduced image detected by the CCD image sensor 108.