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 to evaluate a holographic data storage medium is disclosed. In certain embodiments, the holographic data storage medium is evaluated by a manufacturer. In certain embodiments, the holographic data storage medium is evaluated by a customer prior to encoding customer information into the storage medium. In certain embodiments, the holographic data storage medium is evaluated by a customer after encoding customer information therein.

Abstract: A recording medium records therein image data for distributing contents as element holograms with interference fringes generated by interference between an object beam representing the image data and a reference beam. The image data to be distributed which are recorded as the element holograms in the recording medium are reproduced by applying reference beams to the recording medium.

Abstract: An apparatus and method are disclosed to align the write channel portion of a holographic data storage system. The method establishes a write threshold correlation factor, provides a reference beam, and illuminates a holographic data storage medium encoded with a write reference orientation image with the reference beam to generate a write channel alignment data beam comprising a projected write reference orientation image. The method projects the write channel alignment data beam onto an optical detector, and calculates a first write correlation factor using the projected write reference orientation image, a stored write reference orientation image, and the tangential matched filter. If the method determines that the first write correlation factor is greater than or equal to the write threshold correlation factor, then the method determines that the spatial write channel is properly aligned.

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 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 medium having a recording layer on which holograms are formed by interference between an object beam and a reference beam to thereby record information. The recording layer is formed with a plurality of hologram groups each composed of a plurality of holograms. The holograms in each of the hologram groups have the same information, and adjacent holograms partially overlap each other. In addition, the holograms are arranged to be spaced apart from holograms in other hologram groups.

Abstract: The invention relates to a light redirecting polymeric film comprising a plurality of polymeric individual optical elements wherein the elements comprise curved wedge shaped features in the plane of the film, having a length in the range of 800 to 4000 micrometers.

Abstract: An inline type speckle multiplexed hologram recording apparatus and method is disclosed which can condense signal light and reference light in a sufficiently overlapping relationship with each other on a hologram recording medium without using a lens having a large aperture and a wide angle of view. A signal light region and a reference light region are displayed on a spatial light modulator, and laser light is intensity modulated with recording data displayed in the signal light region to produce signal light while the laser light having passed through the reference light region is used as reference light. The signal light and the reference light are diffused by a diffuser and then condensed in an overlapping relationship with each other on a hologram recording medium by a lens such that interference fringes produced thereby are recorded in the hologram recording medium.

Abstract: A hologram reconstructing apparatus is disclosed. The apparatus includes: unnecessary light removing means for causing the imaging means to receive necessary light only included in the reconstruction light; driving means for operating the hologram recording medium or a reconstruction light optical system; light detecting means for detecting the state that reconstruction light is projected to the unnecessary light removing means of the light cut by the unnecessary light removing means; and control means for obtaining the displacement of the hologram recording medium based on the information on a specific part of the projection state information detected by the light detecting means and controlling the driving means to cancel the displacement and move the hologram recording medium or the optical system.

Abstract: Holographic storage system with multiple reference beams The present invention relates to a coaxial type apparatus for reading from and/or writing to holographic storage media with multiple reference beams. The invention further relates to a beam generator and a filter for use in such an apparatus. According to the invention, in an apparatus for reading from and/or writing to a holographic storage medium, with a coaxial arrangement of three or more focused reference beams and an object beam or a reconstructed object beam, the foci of the focused reference beams are arranged on a circle around the object beam in a Fourier plane of the apparatus. A beam generator generates the three or more reference beams from an incoming reference beam. A filter low-pass filters the object beam and rotates the polarization of the three or more reference beams.

Abstract: A method is disclosed to store, retrieve, and search both analog data and digital data. The method encodes information comprising a plurality of analog datasets in a holographic data storage medium to form an encoded holographic data storage medium, and further encodes digital data abstracted from the plurality of analog datasets to one or more of a plurality of non-holographic data storage media. The method then selects an analog dataset, wherein digital data abstracted from that analog dataset is written to a digital storage address on the one or more non-holographic data storage media, and illuminates the encoded holographic data storage medium with an analog dataset beam comprising the analog dataset. The encoded holographic data storage medium emits a dataset reference beam that strikes the second optical detector at one or more dataset reference beam coordinates. The method then associates the analog dataset with the dataset reference beam coordinate and with the digital storage address.

Abstract: A method and apparatus for improving quality of a signal reproduced from a holographic storage medium in which a hologram is recorded by interference between a signal beam and a reference beam. The signal-quality improving method includes determining a page crosstalk value, which is caused in a page that is to be reproduced from the holographic storage medium by an adjacent page to the page that is to be reproduced, on the basis of on-pixel crosstalk values caused by a plurality of on-pixels of the adjacent page; and removing the determined page crosstalk value from a reproduced signal of the page that is to be reproduced. Since an interpage crosstalk that occurs when multiplexing recording in the holographic storage medium is calculated, and is removed from a reproduced signal, the quality of the reproduced signal can be improved.

Abstract: A hologram recording medium includes a hologram recording layer and a transparent substrate layer stacked on the hologram recording layer. The recording layer records an interference pattern of a recording beam and a reference beam. The transparent substrate layer has an inner surface facing the hologram recording layer, and this surface is formed with trace zones for guiding the recording beam and the reference beam in a prescribed guide direction. The trace zones have a higher reflectance than that of the remaining area in the inner surface of the transparent substrate layer.

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 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: An object of the invention is to prevent lowering of a dynamic range of a hologram recording medium without lowering an average data transfer rate, and to provide stabilized recording sensitivity. A scheduler determines a recording interval time from the point of time when light is irradiated to record a certain hologram of holograms to be multiplex-recorded to the point of time when light is irradiated to record a succeeding hologram in such a manner that at least parts of the holograms are recorded one over the other in a certain recording area. A recording interval time controller controls a light source to irradiate the light depending on the recording interval time determined by the scheduler.

Abstract: An apparatus to control the incident angle of a reference beam, includes a first lens element to allow the reference beam to be incident on a holographic recording medium, and a driving portion to provide the reference beam to the first lens element and to move in a direction perpendicular to an optical axis to change the incident position of the reference beam on the first lens element in a radial direction of the first lens element, wherein the incident angle of the reference beam incident on the holographic recording medium is determined according to the incident position of the reference beam in a radial direction of the first lens element.

Abstract: Photo-thermo-refractive (PTR) glass is a multi-component silicate glass having photosensitivity in rear UV region. A novel process is disclosed for PTR glass sensitization to visible region by means of two-step illumination followed by thermal development. This disclosed process utilizes a first illumination at approximately 325 nm followed by a second illumination with radiation in the visible spectral region out of the region of original photosensitivity of the PTR glass which enables fabrication of complex holographic optical elements for visible region such as plane elements, lenses, curved mirrors, combinations of complex elements and optical correlators. The same process provides a positive increment of refractive index in the bulk of the PTR glass and, therefore, can be used for refractive optical elements recording, such as lenses and waveguides.

Abstract: A hologram recording medium is for recording or reproducing information with light irradiated thereto. The medium has a recording layer made of a photo-sensitive material, a reflective layer disposed on the opposite side of the recording layer from a light irradiated side, tracks formed on the reflective layer such that the tracks are spaced apart by a first pitch from each other to extend without intersection, and positioning marks formed on the reflective layer such that the positioning marks are spaced apart by a second pitch from each other in a direction in which the tracks extend. The second pitch is a function of the first pitch.

Abstract: A hologram recording/reproducing device includes a laser light source emitting laser light; a spatial light modulator generating signal light and reference light from the laser light emitted from the laser light source, the signal light and the reference light traveling in a common light path; a first relay lens system including a first shielding plate at a focal position thereof and transmitting the signal light and the reference light generated by the spatial light modulator, the first shielding plate having a pinhole whose size is 1 to 2 times a Nyquist size; a phase modulating element disposed at a conjugate plane of the signal light and the reference light transmitted through the first relay lens system; an objective lens converging the signal light and the reference light transmitted through the phase modulating element on a hologram recording medium; and a light receiving system disposed between the phase modulating element and objective lens and receiving light returning from the hologram recording me

Abstract: An apparatus and method is disclosed wherein, even if the multiplicity in multiplexing of recording data is increased, positioning of data upon reproduction can be performed with a high degree of accuracy without decreasing the recording capacity. Interference fringes generated by interference of a light beam spatially optically modulated by a spatial light modulator on which a marker data page is displayed with reference light are recorded at a recording spot on a hologram recording medium. Similarly, interference fringes corresponding to recording data page are recorded at another recording spot on the hologram recording medium. The multiplicity of such marker data pages upon recording is set to a value with which recognition of markers upon reproduction can be performed with a high degree of accuracy so that, even if the multiplicity of the data pages is raised, positioning information of high accuracy can be obtained.

Abstract: Methods and systems are described herein for calculating a wavelength to use for a reference beam in recovering data from a holographic storage medium along with calculating a rotation and a tilt for the storage medium in data recovery. These systems and method comprise determining intensity levels for a plurality of windows (or subsets of pixels) for a data page as the angle of the reference beam is adjusted. The angles corresponding to the angles where the maximum intensity of light is detected for each window is then used in determining the wavelength, tilt, and rotation in recovering subsequent data pages from the holographic storage medium.

Abstract: In a recorder for recording optical information in a plurality of recording areas of a holographic memory medium, a recording part records the optical information on a first recording area by multiple-recording; a determining part determines whether the recording in the first recording area has been completed; and a fixing part fixes the optical information on the first recording area in determining that the recording in the first recording area has been completed. The recording part records the optical information in a second recording area by multiple-recording in parallel with or after fixing the optical information in the first recording area when determining that the recording in the first recording area has been completed. Corresponding method and the medium used are also disclosed.

Abstract: A multiple hologram recorder includes an optical system and an incident angle controller. The optical system applies a recording beam and a reference beam to a unit recording region of a hologram recording medium. The recording beam is modulated in accordance with information to be recorded. The reference and the recording beams have the same wavelength. The angle controller adjusts the incident angle of the recording or reference beam to preset angles. Every time the incident angle is adjusted to one set angle, one-page holographic recording is performed. The set angles include a reference angle associated with an angular interval. The incident angle controller causes the incident angle to continuously vary within the angular interval when the incident angle is adjusted to the reference angle. This continuous variation is performed with the recording and the reference beams irradiating the unit recording region.

Abstract: A data writing and reading device is capable of writing and reading data with respect to a holographic storage medium. The data writing and reading device includes a light source which emits a laser beam, a focusing lens unit having a multi-focal lens which splits the laser beam into a reference beam and an object beam and projects the split beams to the storage medium so that an interference pattern between the reference and object beams can be written in the storage medium, and a photo detector for detecting the object beam when the object beam is reproduced in accordance with the holographic data with the incidence of the reference beam to the storage medium. With a simple hardware, data can be written to or read out from the holographic storage medium.

Abstract: A holographic recording and reconstructing apparatus includes a laser light source for emitting a laser beam, a beam splitting element for splitting the emitted laser beam into a signal beam and a reference beam, a light modulating element for modulating the signal beam, an optical system for collecting the modulated signal beam and the reference beam onto a reflection hologram recording medium at substantially the same location, a light detection element for detecting a reconstructed light beam from the hologram recording medium, and wavelength shifting means for shifting the wavelength of the laser beam used during reconstruction from the wavelength used during recording.

Abstract: Intensity profile correction for data pages for holographic storage The present invention relates to a method for recording data pages in a holographic recording medium, and more specifically to a method for compensating for sensitivity variations of the holographic material of the holographic recording medium. According to the invention, a method for recording data pages on a holographic recording medium has the steps of: modulating a light beam with a spatial light modulator to generate a data page with data to be recorded, and applying a compensation profile to the data pages during recording for reducing contrast variations in the reconstructed data pages, wherein the compensation profile is determined from the irradiation history at the recording position and the sensitivity curve of the material of the holographic recording medium.

Abstract: Hologram recording devices and techniques can be employed to produce wide-field-of-view holograms. In one embodiment, a specialized lens is used to couple an object beam into a holographic recording material without substantially changing the angle of incidence of the object beam. When displayed, images from holograms recorded using technique can have a field-of-view greater than that of the object beam. In another embodiment, one or more aspheric reflective surfaces are used to couple an object beam into a holographic recording material at relatively steep angles.

Abstract: A holographic recording medium has at least a recording layer with a thickness of L which comprises a recording layer material having an absorption coefficient of ? and containing a photorefractive material, wherein the optical density ?L represented by the product of the absorption coefficient ? and the thickness L is in the range from 0.3 to 2.0.

Abstract: A method of fabricating a hologram having a pattern made up of pixels in which a photosensitive material for forming a hologram is stacked on either a reflection-type hologram or a transmission type hologram. According to one aspect of the invention, the photosensitive material is stacked on a reflection-type relief hologram and reconstructing illumination light of a given wavelength is struck on the reflection-type relief hologram through the photosensitive material, so that interference fringes produced by interference of the light diffracted from the reflection type relief hologram and the incident light are recorded in the photosensitive material.

Abstract: A hologram record apparatus (100) includes a spatial light modulator (15) and a control device (18). The spatial light modulator (15) is arranged on an optical path of signal light (L1) and divided into a plurality of cell blocks (151) arranged in a matrix. Each of the cell blocks (151) is further divided into a plurality of cells (152) arranged in a matrix. The spatial light modulator (15) can perform modulation on the cell basis. The control device (18) controls the spatial light modulator so as to modulate the signal light according to a plurality of record information sets to be recorded on a hologram record medium (200). Pluralities of modulation units (153) existing in the same cell block are not made into identical patterns. Since a plurality of cell blocks having a large pitch as compared to the pixel pitch are simultaneously or successively turned on/off, it is possible to reduce the distance between the zeroth-order light and the higher-order light.

Abstract: A first holographic data storage device has a first set of holograms stored thereon. A second holographic data storage device has a second set of holograms stored thereon. An opaque layer is disposed between and attached to one side of the first and the second holographic data storage devices. In the case of double reflective diffractive recording, the opaque layer is not necessary.

Abstract: In an angle multiplexing holographic storage device, a movable beam splitter is used for splitting a source beam into an object beam and a reference beam. An encoding device is used for encoding the object beam with pixel data. A parabolic reflector differentially reflects the reference beam with the movement of the movable beam splitter. A holographic storage medium is arranged at the focal point of the parabolic reflector and made to lie in the optical path of the encoded object beam so that the differentially reflected reference beams encounter and interfere with the encoded object beam at the same site of the holographic storage medium to form and record various interference patterns.

Abstract: The invention relates to a method for calculating a computer-generated hologram, in which the pixel distribution of the computer-generated hologram is calculated, in which the pixel distribution of a macroscopic superstructure is calculated and in which the pixel distribution of at least one computer-generated hologram is interconnected with the pixel distribution of the macroscopic superstructure to form a pixel distribution to be written in a storage medium. Similarly, the invention relates to a method for writing the hologram, a storage medium and also a reading device. Therefore, both a computer-generated hologram and a macroscopic superstructure which can contain directly readable information can be brought together in a pixel distribution.

Abstract: This invention provides a hologram recording apparatus for recording an interference fringe, generated by interference of a first light beam subjected to spatial light modulation by recording data with a second light beam, in a recording area of a hologram recording medium, the hologram recording apparatus including: a random phase body for randomizing the wave front of the second light beam, and a multiplex recording control unit for recording the interference fringe of the first light beam and the second light beam in the same recording area of the hologram recording medium each time the random phase body is rotated.

Abstract: Disclosed is a multiplexing method and apparatus that allows holograms to be spatially multiplexed with partial spatial overlap between neighboring stacks of holograms. Each individual stack can additionally take full advantage of an alternate multiplexing scheme such as angle, wavelength, phase code, peristrophic, or fractal multiplexing, for example. An amount equal to the beam waist of the signal beam writing a hologram separates individual stacks of holograms. Upon reconstruction, a hologram and its neighbors will all be readout simultaneously. An filter is placed at the beam waist of the reconstructed data such that the neighbors that are read out are not transmitted to the camera plane. Alternatively, these unwanted reconstructions can be filtered out with an angular filter at an intermediate plane in the optical system that has a limited angular passband.

Abstract: The invention relates to a color hologram display an image of a three-dimensional object and a hologram image of a pattern of plane characters, images or the like are recorded in the same volume type hologram photosensitive material in a superposed or multiplexed fashion. A color hologram display 27? comprising a combined reflection and volume type of single layer, wherein a color pattern 29g of plane characters, images or the like and a color three-dimensional subject image O? are reconstructably recorded while spatially superposed one upon another.

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: A method for producing an optical element, preferably a security feature, wherein a film having a first embossed hologram in an embossing layer is provided, and a second embossed hologram is embossed into the same embossing layer such that the first embossed hologram is partly replaced with the second embossed hologram. The invention further relates to a method for producing an optical element wherein an embossable film provided with an embossed hologram is partly filled with printing lacquer, and a method for producing an optical element wherein hologram embossing is prevented by prior partial printing of the embossing film with curable printing lacquer. The invention relates further to optical features producible by the inventive methods, documents of value having an inventive optical feature and a numbering embosser for use in an inventive production method.

Abstract: A first holographic data storage device has a first set of holograms stored thereon. A second holographic data storage device has a second set of holograms stored thereon. An opaque layer is disposed between and attached to one side of the first and the second holographic data storage devices. In the case of double reflective diffractive recording, the opaque layer is not necessary.

Abstract: A recording medium (1) for hologram comprises a hologram recording layer (3) comprised of photo-polymer layer is formed on a base (2) comprised of colorless and transparent resin film, etc. and a protective layer (4) comprised of colorless and transparent resin film, etc. formed on the hologram recording layer (3). As such base (2) and protective layer (4), material having less double refraction is used. Optical axis of double refraction when such components are configured to be strip-shaped is allowed to be a direction of the longer side or a direction of the shorter side.

Abstract: The present invention provides a method and apparatus for a multilayer optical articles. A method comprises forming a first multilayer article with a first substrate and a second substrate with a first adherent disposed between the first and second substrate. A first surface of a third substrate is then grasped with a first holder and a second adherent is then disposed on one or more surfaces selected from a second surface of the third substrate and a surface of the first multilayer article while the multilayer article is grasped by a second holder. The second adherent is then at least partially cured while the first and second holders maintain their grasp and while the inner surfaces of the first and second holders are in the selected angular relationship to form a second multilayer article.

Abstract: Disclosed is a multiplexing method and apparatus that allows holograms to be spatially multiplexed with partial spatial overlap between neighboring stacks of holograms. Each individual stack can additionally take full advantage of an alternate multiplexing scheme such as angle, wavelength, phase code, peristrophic, or fractal multiplexing, for example. An amount equal to the beam waist of the signal beam writing a hologram separates individual stacks of holograms. Upon reconstruction, a hologram and its neighbors will all be readout simultaneously. An filter is placed at the beam waist of the reconstructed data such that the neighbors that are read out are not transmitted to the camera plane. Alternatively, these unwanted reconstructions can be filtered out with an angular filter at an intermediate plane in the optical system that has a limited angular passband.

Abstract: In an apparatus for detecting holographic data reproduced from a holographic medium, the holographic medium has an interference pattern and the holographic data is reproduced when a first portion of a reference beam is diffracted by the interference pattern within the holographic medium. A transmission beam detector detects a light intensity of a transmission beam which is a second portion of the reference beam, wherein the transmission beam is not diffracted to reproduce the holographic data and passes through the holographic medium. Then, a CCD (charge coupled device) controller generates a driving signal in accordance with the detected light intensity. Thereafter, a CCD detects the holographic data in response to the driving signal.

Abstract: Methods for producing a hologram mask approximating the exposure produced by a non-holographic phase shifting photo mask are disclosed. One such method exposes a hologram recording material to a first object light, having passed through a first original mask and a first reference light having a difference in phase with the first object light, and further exposing the hologram recording material to a second object light, having passed through a second original mask and a second reference light having a difference in phase with the second object light, wherein first and second phase differences are not the same and wherein the exposed hologram material can be replayed to produce an exposed pattern that approximates an exposed pattern of a non-holographic phase shifting photomask.

Abstract: A volume hologram for modifying a characteristic of an input microwave beam and a method for manufacturing thereof are disclosed. The hologram is fabricated from a multi-layer artificial dielectric wherein each layer is made of a dielectric material and includes a lattice of inclusions, for example metal disks disposed on one side thereof, and wherein a pre-determined three-dimensional grating pattern of dielectric perturbations is induced by spatial modulating the lattice of the inclusions. The hologram can be designed for efficiently steering, reshaping, combining or splitting microwave beams.

Abstract: A holographic imaging system and method includes a radiation source for generating radiation. A data base has a set of elements, each element is indicative of a trajectory of a light ray exiting a point in a recorded scene. A spatial light modulator is receptive of the radiation from the radiation source and the elements of the data base mapped to the spatial light modulator, thereby projecting from the spatial light modulator an optical signal in the nature of a two dimensional bitmap of the recorded scene. A diffractive optical element includes a set of basis fringes receptive of the projected optical signal from the spatial light modulator for diffracting the optical signal in a specified direction. A multiplexer is receptive of the elements of the data base for multiplexing the elements of the data base to the spatial light modulator. A timing device synchronizes multiplexing the elements of the data base to the spatial light modulator and diffracting the optical signal in a specified direction.

Abstract: Disclosed are methods of producing obliquity corrected light beams, and holographic recording and retrieval systems that utilize a obliquity corrected reference beam. The obliquity correction is accomplished using off-center lenses.

Abstract: An optical device for security and anti-counterfeit applications comprises a diffractive structure comprising a discrete region that in response to white light illumination generates an image by a process of diffraction in close angular proximity to the specular reflection and which is thus substantially non-visible to an observer, and which under coherent illumination generates a laser projection covert image which forms an image in an image plane located away from the physical plane of the device and which is angularly co-located in close proximity to the direction and position of the specular reflection.