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 hologram recorder applies a recording beam (S) and a reference beam (R) to the illumination site (p) of a hologram recording medium (B). The interference between the recording beam (S) and the reference beam (R) produces multiple hologram recording at the illumination site (p). The recorder includes a recording-purpose reference beam reflector (10) for reflecting the reference beam (R) to the illumination site (p), and a pivot mechanism for pivoting the reflector (10) about an axis (x) to vary the incident angle (?r) of the reflected reference beam (R) to the recording medium (B). The reflector (10) is disposed to cross a predetermined optical path. The axis (x) of the pivot mechanism is so arranged that the reflected reference beam (R) is directed to the illumination site (p) even when the incident angle (?r) of the beam (R) changes due to the pivoting of the reflector (10).

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 including holographic storage media for recording or for reading recorded data using such devices or systems.

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

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

Abstract: A hologram recording device records holograms by interference between an recording beam and a reference beam. The device includes an objective lens exhibiting a predetermined aberration. It is supposed that the laser beam applied to the beam splitter has an light intensity of 1, the recording beam and the reference beam emitted from the beam splitter have light intensities of P and 1?P, respectively, the optical magnification for the recording beam traveling from the beam splitter to the objective lens is a, and N pixels are used for modulation of the recording beam in the spatial light modulator. When the recording beam at the predetermined region has an amplitude 1/k times the amplitude of the reference beam, and the amplitude of the recording beam is X times as great as when there is no aberration, the predetermined aberration of the objective lens is determined to satisfy the formula: 0 < X < a ? ( 1 - P ) 0.6 ? P × 1 kN .

Abstract: A hologram recorder (A) records holograms in a selected unit recording area (B1) of a hologram recording medium (B) by interference between a recording beam (Lr) which is applied vertically to the unit recording area (B1) and a reference beam (Lr) which is applied obliquely to the unit recording area (B1). The hologram recorder (A) includes a reference beam oblique applier (23A, 23B) for application of the reference beam (Lr) obliquely to the unit recording area (B1) by reflection, and a reference beam swing mechanism (30) for supporting the reference beam oblique applier (23A, 23B) and for swinging the reference beam oblique applier (23A, 23B) about a predetermined rotation axis which is perpendicular to an entering direction of the recording beam (Lw) that makes an entry into the unit recording area.

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

Abstract: A method for fabricating three-dimensional photonic crystal structures includes providing a layer of photosensitive material; introducing a laser beams into the material; reintroducing the laser beams into the photosensitive material during a second exposure; combining results from at least the first and second exposures to produce a three-dimensionally periodic pattern in the photosensitive material. A related system includes a laser source; a grating array having a plurality of diffraction gratings located thereon; a mask plate located on a photoresist layer and arranged in registration with the grating array; a rotating shutter arranged between the grating array and the laser source, said rotating shutter being suitable for periodically blocking light from the laser source; wherein each of the diffraction gratings is positioned and oriented so as to converge all first-order diffracted spots to a common point lying in a plane of a back side of the mask plate.

Abstract: A holographic recording medium includes a recording layer on a substrate, which records data information in a light interference pattern. Information on a thermal expansion characteristic of a recording material contained in the recording layer and/or information on temperature dependency of the refractive index of the recording material are recorded within the holographic recording medium in advance.

Abstract: Disclosed are an apparatus and a method for displaying hologram of a mobile communication terminal. The present invention can create hologram from two-dimensional image by providing a hologram processing function for a mobile communication terminal and provide the hologram to a user. Further, the mobile communication terminal with the hologram processing function can perform medical diagnosis on a user, and thus can save a life by performing accurate medical diagnosis in emergency through hologram communication with an emergency center.

Abstract: A recording medium, a recording apparatus, and a recording method. Recording data is recorded as element holograms on a hologram recording medium, a synchronization signal selected from among a plurality of synchronization signals and recording data encoded for every predetermined unit amount are arrayed to facilitate reproduction.

Abstract: When recording on a holographic recording medium by using a recording beam, the time required for an asking servo control to recover is reduced to increase the data transfer rate. In the holographic recording apparatus 10, a laser beam from a laser light source 16 is formed into a collimated beam having an expanded beam diameter and then is divided into an object beam and a reference beam. The divided object beam is modulated according to information to be recorded, and these object and reference beams are made incident on the reflective surface of a rotating polygon mirror 18, while maintaining collimated beam shapes and being adjacent to each other, through a condenser lens 24 having a focal point behind the reflective surface of the polygon mirror 18.

Abstract: A recording apparatus performing at least recording with respect to a hologram recording medium is disclosed. The recording medium includes: a light emitting means for emitting light to be radiated with respect to the hologram recording medium set at a prescribed position; a spatial light modulation means configured to be able to generate reference light and signal light to be radiated to the hologram recording medium by performing light intensity modulation to incident light in the unit of pixels; a phase modulation means for performing phase modulation to radiated light from the spatial light modulation means; and an optical system configured to guide light emitted from the light emitting means with respect to the hologram recording medium through the spatial modulation means and the phase modulation means.

Abstract: There is provided a diffractive display device having small non-uniformity of luminance within a surface, and a finder device and a camera using the diffractive display device. The diffractive display device includes a pair of substrates 24a, 24b and an optical material layer 26 arranged between the pair of substrates 24a, 24b. First illuminating means 22a for entering light through the side surface of the pair of substrates 24a, 24b and second illuminating means 22b for entering light through the side surface of the pair of substrates 24a, 24b from a direction different from the light from the first illuminating means 22a are arranged. A first portion 30a of the optical material layer 26 diffracts the light from the first illuminating means 22a and emits it from a substrate surface, and a second portion 30b diffracts the light from the second illuminating means 22b and emits it from the substrate surface.

Abstract: A value or security document (2) contains a security feature (4) in the form of a film laser with an emitter layer (12) and preferably a protective layer (14). A spatial, periodic modulation (8), preferably of the surface of a substrate, permits fine adjustment of a laser wavelength within a range of possible wavelengths. This permits a coding of the security feature by different portions of different wavelengths.

Abstract: A method of recording an exposure pattern in a recording layer of a holographic mask, using an original reticle that has the exposure pattern formed therein, the recording method comprising: illuminating a first recording light and a first reference light to the recording layer simultaneously, the first recording light being illuminated through an original reticle placed opposite to the holographic mask with a first gap therebetween, the first reference light being illuminated to the recording layer at a first incident angle; and illuminating a second recording light and a second reference light to the recording layer simultaneously, the second recording light being illuminated through the original reticle placed opposite to the holographic mask with a second gap therebetween, the second gap being different from the first gap, the second reference light being illuminated to the recording layer at a second incident angle.

Abstract: A rotary apertured interferometric lithography (RAIL) system that includes interferometric lithography tools, a mask with a slit preferably with an arc shape, and a rotating stage is disclosed. The RAIL system could create a servo pattern of a recording-head trajectory of a hard disk drive in a master for magnetic-contact printing. The master can could be used to form arrays of sub-micron sized magnetic elements on a magnetic disk media for high-density magnetic recording applications.

Abstract: Structures, subassemblies, devices, systems, and subsystems selected from: (1) a unitary holographic drive head assembly mounting structure; (2) an assembly including a unitary holographic drive head assembly mounting structure and a plurality of holographic drive head components and/or subassemblies; (3) a subassembly including a spatial light modulator, detector array, and a beam splitter; (4) a device including a spatial light modulator and a physical aperture positioned over or an imaged aperture projected onto the photoactive area of the spatial light modulator; (5) a system for optically aligning or pointing a laser in a holographic drive head assembly; (6) a light source subassembly including a laser, a fiber coupling lens; and an optical fiber having a fiber connector ready output end; and (7) a light source subsystem including a laser source, beam conditioning optics, fiber coupling optics for receiving the conditioned light beam, and a fiber optic connector for receiving the conditioned light beam f

Abstract: The present invention includes systems and compositions of holographic grating structures devices and methods for fabricating such holographic grating structures. The method comprises the steps of preparing a composite mixture comprising a polymerizable matrix, a liquid crystal, and a photo-oxidant dye, producing an interference pattern from two interference beams, wherein the two interference beams originate from a recording laser beam directed by a low energy laser, and projecting the interference pattern on the composite mixture to form a holographic grating structure. As described, the holographic grating structure yields a first-order diffraction efficiency of at least about 30% diffraction efficiency which may be adjusted by the application of an electric field.

Abstract: A method for producing a 3D image includes providing a pixel-by-pixel map over a preselected aperture of relative phases for coherent light scattered by or transmitted through a desired scene. The method includes positioning micro-mirrors of a reconfigurable mirror array to produce reflected light whose wave front has the pixel-by-pixel map over the preselected aperture in response to the array being illuminated with a coherent light beam. The method includes illuminating the reconfigurable mirror array with the coherent light beam to enable producing a 3D image of the desired scene.

Abstract: A device and method for mass producing reflection holograms. Photosensitive material is drawn across an object to be copied and coherent radiation is scanned across the material and the object. The object may comprise a component which is variable, such as a counter, or a hologram. The exposed photosensitive material is removed from the object, the symbols on the object are changed if desired, fresh material is moved into place, and a new hologram is created. The holograms of the present invention preferably have the capability to be sequentially or individually numbered or otherwise customized with a variety of symbols, for example for security purposes.

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 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 holographic record erasing method and a holographic recording and reproducing apparatus in which data reproduction can be disabled without irradiating a holographic recording medium with a high energy erasing beam or physically destroying the medium. A holographic recording medium 16 in a holographic recording and reproducing apparatus 10 has a recording layer 17 formed of two split recording layers 17A and 17B, and a crosstalk layer 17C is provided therebetween. The crosstalk 17C layer still has photosensitivity after completion of multiplex recording of data holograms 24 in the recording layer 17. An object beam IOb for erasing and a reference beam IRe for erasing each having a large beam diameter are projected onto the layer to form a crosstalk hologram 26 having low selectivity. Hence, when a reproduction beam is projected onto the data holograms 24, a diffraction beam is always generated also from the crosstalk hologram 26.

Abstract: A compact and low-cost hologram reproducing apparatus with a simple mechanism is provided. A light source 1 and a lens 11 for generating parallel light are provided on an inner surface of a housing 5. By changing the angle of a biaxially driven galvanometer mirror 2 provided at an appropriate position opposing the light source 1 and the lens 11, reflected light is applied two-dimensionally, in the vertical and horizontal directions, on a recording element 3 mounted below and adjacent to the housing, and is entered as reference light in holograms. Further, light beams exiting from the holograms are received at the same optimal position on a light-receiving element 4 disposed in an upper part of the housing. The received light is subjected to data decoding so as to reproduce read-only holograms.

Abstract: A reproduction apparatus is provided which reproduces, from a hologram recording medium on which digital data are recorded as an element hologram formed from interference fringes generated by interference of imaged data of the digital data as object light with reference light, the digital data. If a synchronization signal recorded in advance in a predetermined region of the hologram recording medium is detected successfully, then it is decided that the tracking state with regard to the element hologram is favorable. In this instance, signal processing is performed the image picked up from the element hologram to reproduce the digital data.

Abstract: A holographic memory in which a disk recording medium having a mechanism for operating an optical pick-up system is used, signal and reference light beams are so coaxially directed as to be opposed, the polarization planes of the signal with each other on the disk recording medium and which is well compatible with existing techniques and high in cost performance when manufactured as a product. The reflection holographic memory comprises random-phase modulation multiplex recording means disposed in the light guide of the signal and/or reference light beams and a spatial-shift multiplex recording means so as to increase the recording capacity. Signals are recorded in the thickness direction of the disk so as to further increase the recoding capacity.

Abstract: A hologram recording method for recording information of signal light as holograms in an optical recording medium, which includes illuminating signal light at the optical recording medium; illuminating reference light at the optical recording medium simultaneously with the signal light such that an interference pattern is formed by the signal light and the reference light intersecting in the optical recording medium; and shifting a region in the optical recording medium at which the signal light and the reference light intersect, by shifting an illumination position of the reference light along an optical axis of the signal light, thereby recording a plurality of holograms in the recording medium.

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: There is provided a holographic device that reproduces information by irradiating light beams emitted from a light beam generator onto a recording medium formed with a hologram. The light beam generator has a substrate and a plurality of light emitting units provided on the substrate, and each of the plurality of light emitting units is composed of a laser oscillator for emitting laser light having a wider wavelength bandwidth than single-mode laser light. In addition, a condensing means is provided between the light beam generator and the recording medium in order to condense a plurality of light beams emitted from each of the light emitting units onto approximately the same location of the recording medium.

Abstract: A method to encode information holographically, wherein the method provides information, and generates a plurality of data images, wherein each data image comprises a portion of the information. The method holographically encodes each of the plurality of data images in a holographic data storage medium, generates a plurality of identifiers, and associates a different one of the plurality of identifiers with a different one of the plurality of data images. The method forms a directory image reciting each of plurality of identifiers, encodes the directory image in a non-holographic data storage medium, and holographically encodes the directory image in the holographic data storage medium.

Abstract: Pre-sensitization techniques can be used in conjunction with holographic recording materials to allow high quality holographic stereograms to be recorded in those holographic recording materials using pulsed lasers. Additional hologram production system hardware and software designs for use with pulsed lasers are disclosed.

Abstract: A holographic recording and reconstructing apparatus includes a light source having a variable oscillation wavelength; a temperature sensing unit operable to sense temperature; and a control unit operable to record information about a temperature sensed by the temperature sensing unit on a holographic recording medium during recording, to obtain the information about the temperature from the holographic recording medium and obtain a temperature sensed by the temperature sensing unit during reconstruction, to determine the amount of wavelength shift to counteract the effects of a change in the dimension of the holographic recording medium between recording and reconstruction based on the difference between the temperatures, and to shift the oscillation wavelength of the light source by the determined amount.

Abstract: An optical apparatus includes: a focusing lens that focuses light which is one of recording light being irradiated to an optical recording medium with reference light for recording a hologram and reference light being irradiated to an optical recording medium for reading out a hologram; and a focal position-shifting unit that refracts the light while moving in accordance with a moving speed of the optical recording medium, so as to shift a focal position of the light in the optical recording medium a distance in a thickness direction of the optical recording medium.

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: In recording of an interference fringe of a reference beam and a signal beam in a hologram recording medium, at the time of multiple recording of holograms in the same recording region by varying the angle of incidence of the reference beam on the hologram recording medium, the angular pitch of the incidence angle of the reference beam is varied according to the incidence angle of the reference beam in the manner of ??1, ??2, . . . , ??m?1, and is thereby set to a minimum in such a range as not to worsen crosstalk. This makes it possible to increase the degree of multiplexing when the movable angle of the reference beam is the same, and to narrow the movable angle of the reference beam when the degree of multiplexing is the same, as compared with the related art.

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 hologram-recording method including recording a reflection-type volume hologram onto an optical recording medium by irradiating the optical recording medium with a modulated beam obtained by spatially modulating a laser beam and a diffused beam obtained by diffusing the modulated beam, coaxially but from different sides of the optical recording medium, respectively. The invention provides a hologram-recording method, an optical recording medium, and a hologram-recording device that enables on-demand recording of a reflection-type volume hologram which reliably prohibits forgery or alteration with a simple device configuration.

Abstract: A holographic storage drive and control of a holographic storage system are configured to write at least a group of holograms in a predetermined pattern in the holographic storage medium, and to write a directory hologram which relates to the holograms of the group to form an anchor location of the predetermined pattern. Further, a directory comprising the directory hologram stored in a memory, and the control is configured to initiate a read operation of at least one hologram of a group with an access for the directory hologram of the group at the anchor location; to read the accessed hologram, employing a matched filter to cross-correlate the read accessed hologram with an ideal version of the directory hologram derived from the directory stored in the memory; and to determine whether the read accessed hologram is the directory hologram of the group.

Abstract: An apparatus for manipulating particles (micro, nano, and pico) having one or more characteristics with an optical trap formed by modulating a laser beam with a Diffractive Optical Element (DOE). At least one characteristic of the material is selected; and a laser beam having a selected wavelength corresponding to the at least one selected characteristic of the material is generated. Values of the DOE are calculated corresponding to the at least one selected characteristic of the material. The beam and the DOE are modulated to produce a holographic optical trap having properties corresponding to the at least one selected characteristic; the trap is focused to a beam focus or selected spot size; and the beam focus is located near a particle location for trapping the particle therein.

Abstract: A hologram device records information of an interference fringe of signal light and reference light onto a hologram recording medium and reproduces the recorded information by emitting the reference light onto a recording area of the hologram recording medium. The hologram device includes a recording/reproducing controller performing a recording operation of the information concurrently with a reproducing operation of previously-recorded information, and an error detector detecting an error in the previously-recorded information reproduced concurrently with the recording operation.

Abstract: A hologram recorder (A) records holograms in a selected unit recording area (B1) of a hologram recording medium (B) by interference between a recording beam (Lr) which is applied vertically to the unit recording area (B1) and a reference beam (Lr) which is applied obliquely to the unit recording area (B1). The hologram recorder (A) includes a reference beam oblique applier (23A, 23B) for application of the reference beam (Lr) obliquely to the unit recording area (B1) by reflection, and a reference beam swing mechanism (30) for supporting the reference beam oblique applier (23A, 23B) and for swinging the reference beam oblique applier (23A, 23B) about a predetermined rotation axis which is perpendicular to an entering direction of the recording beam (Lw) that makes an entry into the unit recording area.

Abstract: A rotary apertured interferometric lithography (RAIL) system that includes interferometric lithography tools, a mask with a slit preferably with an arc shape, and a rotating stage is disclosed. The RAIL system could create a servo pattern of a recording-head trajectory of a hard disk drive in a master for magnetic-contact printing. The master can could be used to form arrays of sub-micron sized magnetic elements on a magnetic disk media for high-density magnetic recording applications.

Abstract: Producing a digital hologram-in a storage medium includes: (i) focusing a write beam onto the storage medium; (ii) moving the write beam two-dimensionally relative to the storage medium; (iii) focusing a scanning beam onto a beam-guiding mask having a plurality of tracks; (iv) moving the scanning beam two-dimensionally relative to the mask, the movement of the scanning beam being coupled with the movement of the write beam; (v) generating a position control signal when the position of the scanning beam deviates from the scanned track by a predefined value; (vi) controlling the position of the write beam on the storage medium with the aid of the position control signal; and (vii) writing the hologram by introducing radiation energy point by point, the intensity of the write beam being controlled as a function of the position of the write beam on the storage medium.

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: A distributed system for producing holographic stereograms (holograms). A data acquisition station is typically remote from image processing, printing, and replicating stations. The data acquisition station is designed to maximize customer convenience, and may be the customer's own personal computer. The data acquisition station is further designed to accept a wide variety of source data and to perform whatever processing is required to deliver image data to the image processing station in an acceptable format. The data acquisition station further has processing capability to display preview images, which may be assembled by programming executing at the data acquisition station or downloaded from a server.

Abstract: A system and method for printing a hologram are disclosed. The method includes the operation of transmitting a laser light beam. The laser light beam can be split into an object beam and a reference beam. Phase information can be added to the object beam using a spatial phase modulator to form a phase controlled object beam. The reference beam and the phase controlled object beam can be directed to a predetermined location on a holographic media to enable the reference beam and the phase controlled object beam to form an interference pattern on the holographic media.

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: Disclosed is a method of producing a hologram through a two-beam laser interfering exposure process, which comprises emitting a coherent laser light with a pulse width (?) ranging from greater than 900 femtoseconds to 100 picoseconds and a laser power of 10 ?J/pulse or more using a solid-state laser as a light source, dividing the pulses light from the laser into two beams, controlling the two beams temporally and spatially in such a manner that the two beam are converged on a surface of or inside a workpiece for recording a hologram while matching the respective converged spots of the two beams with one another temporally and spatially to create the interference therebetween so as to record a surface-relief hologram on the surface of the workpiece or an embedded hologram inside the workpiece in an irreversible manner.