Abstract: A holographic lithography tool (110) for generating a light interference pattern used to expose a photosensitive medium (119) employs a refracting prism (121) in the optical path between divergent illuminating beams (127a, 127b). The prism is optically coupled to the photosensitive medium via an index matching fluid (123). By increasing the incident beam angle and the index of refraction, the prism reduces the size of features recorded in the photosensitive material. The divergent illuminating beams are generated by a beam delivery system which preferably employs easily adjustable fiber optic cables (176, 184). Use of the prism coupling technique facilitates use of fiber-optic-compatible wavelengths in the blue region of the spectrum in a variety of applications, such a distributed feedback grating fabrication.

Abstract: We disclose apparatus for holographic recording of information. The apparatus includes a lens or lens system, referred to here as the "FT lens," situated in such a way that light from an object beam enters the FT lens after passing through an object, and light leaving the FT lens impinges on a recording medium situated at a Fourier transform plane of the object with respect to the FT lens. In certain aspects of the invention, the apparatus includes a phase element effectively juxtaposed with the object, the phase element is effective for redistributing object-beam intensity in the Fourier transform plane, and the phase element has a correlation length greater than a maximum pixel side length associated with the object. In certain other aspects of the invention, the apparatus includes an optical element or optical system, referred to here as a "power optic," that adds convergence or divergence to the object beam before the object beam enters the FT lens.

Abstract: A method and apparatus for making holograms includes a technique for exposing a film substrate or other light-sensitive medium to consecutive two dimensional images, together representative of a physical three-dimensional system, to generate a three dimensional hologram of the physical system. Low beam ratios are employed to superimpose multiple (20-300) images on the substrate. Each image is relatively weak, but the combination of the series of weak images ultimately appears as a single clearly defined hologram.

Abstract: A holographic memory system which utilizes the Talbot Effect for the lensless, near-field propagation of repeating image planes of periodic structures. Periodic phase structures at one plane in a holographic memory system are mapped to the input amplitude data plane in the holographic memory system. In a preferred embodiment, coherent light is passed through a lenslet array and propagated via the Talbot Effect to self-image coincident on a spatial light modulator that provides the holographic memory system with input data. The lenslet array is located relative to the spatial light modulator such that the desirable phase image structure is self-imaged in its Fresnel region onto the input amplitude data structure.

Abstract: A real time fingerprint verification system includes a recording device and a verification device each having a fingerprint scanner for generating a flat, dimensionally undistorted, high contrast, fingerprint image, and an intensity sensitive, spatial light modulator (SLM) for receiving and transforming the flat fingerprint image into a planar, coherent light image. In the recording device, the planar coherent light image beam of the fingerprint from the SLM is Fourier transformed, and input into a microscope objective lens system which expands the Fourier transformed beam image sufficiently to allow mechanical blocking of its central portion or order, whereupon it is directed to interact as an object beam with a reference beam from the particular coherent light source to record a holographic matched filter.

Abstract: A holographic storage and retrieval system for use in co-propagating or counter-propagating geometries having a common optical relay for guiding a signal beam and a reference beam along a common optical axis to a holographic medium to write a hologram therein. The optical relay has an object region imaging quality such that at least 65% and preferably at least 80% of the nominal luminous energy from object pixels is encompassed or "ensquared" by the corresponding image pixels. Additionally, the optical relay has a high total numerical aperture (N.A.) of about 0.83, a pixel N.A. of approximately 0.04 for the signal beam. The system of the invention can be used with holographic storage media in the form of disks, tapes or bulk holographic crystals.

Abstract: A holographic data storage and/or retrieval apparatus having a spherical holographic recording medium and addressing means for rotating the recording medium to selectively expose the recording medium to data and reference beams at predetermined rotational positions. Whereby image data contained in the data beam is recorded in the recording medium and/or a data beam containing image data is reconstructed from the recording medium.

Abstract: A method and apparatus for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader is preferably embodied as a handheld unit and comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. An optically transmissive spacer affixed to the front of the handheld unit allows ambient light to be collected at close range, and a diffuser may be used to reflect ambient light from the handheld unit to provide additional illumination at close range. A masked CCD detector with rectangular pixels receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of the CCD detector at high illumination levels. A correlated double sampling circuit coupled to the adaptive exposure circuit rejects common mode noise and allows operation in lower light levels.

Abstract: Systems and methods for steering a complex, spatially-modulated incident beam of coherent light to gain access to data locations in a holographic memory cell (HMC). One of the systems includes: (1) a reflective element, locatable proximate a first focal plane of the incident beam, (2) a rotational steering mechanism, coupled to the reflective element, that orients the reflective element according to a desired rotational angle to steer the incident beam in a desired direction and (3) a refractive element that refracts the beam reflected from the reflective element to create a second focal plane for the beam, the HMC locatable proximate the second focal plane to receive the beam at a location thereon that is a function of the desired direction.

Abstract: A method and apparatus for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader is preferably embodied as a handheld unit and comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. An optically transmissive spacer affixed to the front of the handheld unit allows ambient light to be collected at close range, and a diffuser may be used to reflect ambient light from the handheld unit to provide additional illumination at close range. A masked CCD detector with rectangular pixels receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of the CCD detector at high illumination levels. A correlated double sampling circuit coupled to the adaptive exposure circuit rejects common mode noise and allows operation in lower light levels.

Abstract: The data encoder (e.g. an amplitude spatial light modulator, ASLM) in a volume holographic storage system is rotated by 45.degree. relative to the normal to the plane of the reference and signal beams, such that the near-Fourier transform pattern of the encoder at the medium has an X-shape. The encoder rotation allows tight packing of spatial multiplexing subvolumes in a rectangular array, and provides for uniform spatial frequency filtering in a perpendicular geometry.

Abstract: An optical scanning holography system which requires only a two dimensional scan to record three dimensional information from a fluorescent specimen wherein the optical scanning holography is based on scanning the specimen with a Fresnel zone pattern and detecting and decoding the fluorescent light reflected from the specimen. The flourescent light reflected from the specimen contains three dimensional information about the specimen so that once the fluorescent light is detected and decoded a three dimensional image of the specimen can be obtained and displayed using only the two dimensional scan.

Abstract: A fingerprint sensor having a holographic phase grating glued on one right angle surface of a prism is described where a light source oriented normally relative to the hypotenuse surface of the prism illuminates an interface of the grating and finger surface. Incident light rays are refracted and absorbed where ridges of the finger surface contact the grating surface, whereas light rays are totally internally reflected in areas between and pores in finger surface ridges not in contact the grating surface. The reflected light rays, diffracted by the holographic phase grating, propagate normally (.perp.) back into the right angle prism where they are reflected normally (.perp.) out the remaining right angle surface of the prism by a second total internal reflection at the internal hypotenuse surface of the prism. The reflected light rays emerging from the sensor contain high contrast, detailed images of the ridges and valleys of the finger surface including pores in the ridges, i.e.

Abstract: A generator of energy-depleted radiation and various methods and applications using the energy-depleted radiation. Various embodiments are disclosed of the energy-depleted radiation generator and an energy-restored radiation generator, which permits detection of wave properties of the radiation without regard to the depletion of its energy. The energy-depleted radiation generator functions in one embodiment by selective transmission of destructively interfering radiation. Other embodiments use two-beam coupling or directional coupling to achieve energy depletion. Restoring energy to an energy-depleted radiation beam is accomplished by transferring energy to it from a reference beam, in a beam-to-beam transfer or in an optical amplifier. The invention has important applications in fields such as communications, specimen analysis, photorefractive recording, holography, and other fields in which the reduction of energy content in the associated radiation is advantageous.

Abstract: Method for producing a of a transparent type hologram screen of an wide visible range. A photosensitive member and a light source of a reference light are arranged on the same side of the light diffusing body. A light source of an object light is arranged on the opposite side of the light diffusing body, so that the light is transmitted through the light diffusing body to generate a object light. A light from a light source of a reference light is reflected at the light diffusing body or a member such as a half mirror or a transparent, reflective hologram element arranged at a front side of the light diffusing body.

Abstract: Embodiments of the invention include an off-axis amplitude and phase encoding optical system, apparatus and method of storage in which a holographic optical element (HOE) is used advantageously to reconstruct optical elements typically used to phaseencode an object beam emanating from a spatial light modulator (SLM). The optical system includes a spatial light modulator (SLM) such as a digital micro-mirror device (DMD), a data storage device such as a holographic memory cell (HMC), and the holographic optical element (HOE) for duplicating the phase-encoding functions typically performed on an object beam emanating from the SLM prior to alignment with the holographic memory cell (HMC). Conventionally, a phase mask along with one or more optical elements comprising a four-F lens system typically are needed to phase encode the amplitude-encoded light pattern that propagates from the SLM.

Abstract: A holographic data storage apparatus having no readout lens. The apparatus has a spatial light modulator (SLM), a focusing element such as a lens, a holographic data storage material and a spatial light detector such as a CCD. The lens is located between the SLM and CCD such that the SLM is imaged onto the CCD (i.e. the positions of the SLM, lens, and CCD satisfy the lens equation). The holographic storage material is located between the lens and CCD. Preferably, the storage material is located centered upon a Fourier plane of the lens. In this case, the apparatus also has a phase mask located adjacent to the SLM. Alternatively, the storage material is located a distance away from the Fourier plane or is not centered on the Fourier plane. In yet another embodiment, the holographic storage material is located in contact with the CCD.

Abstract: The invention relates to a sensor (9) comprising a hologram (17) supported on or within a holographic support medium (10).A species to be detected is reactive with a substance disposed throughout, the sensor (9). Optionally, a chemical reactive with a species to be detected or a specific binding conjugate of a species to be detected is disposed throughout part of or all of the sensor (9).The resulting reaction(s) cause(s) variation(s) in the hologram (17) or holographic support medium (10) which in turn varies one or more optical characteristic(s) of the hologram (17).The variation in the optical characteristic(s) of the hologram (17) and/or the holographic support medium (10), preferably give(s) rise to a wavelength shift in incident radiation. The variation of the optical parameter is related to the species to be detected.The advantages of the sensor are that it is cheap, easy to manufacture and, once calibrated, reliable and robust.

Abstract: Device, method, and system for recording diffractive high resolution text, pictorial, and/or other graphical information is provided which is particularly suited to recording information that would be difficult to reproduce by typical counterfeiting methods. The information recorded may be used to authenticate the recorded item, or indirectly, an item to which the recording is attached. Such items may include legal, financial and commercial instruments, credit cards, and packaging for such items as software, art, and other items where forgery of the item may be a concern. In one embodiment of the invention light is selectively passed by a shutter, and a spatial filter then cleans the beam to remove undesirable frequency components.

Abstract: The present invention is a holographic reconstruction device for reconstructing successive holograms previously recorded by a recording reference beam in a recording medium, each previously recorded successive hologram being spaced apart a recording displacement. The recording reference beam has a recording wavelength in the range where the recording medium is photosensitive and a recording propagation angle. The device comprises a reconstruction mechanism having a reconstruction reference beam with a reconstruction wavelength in the range where the recording medium is relatively photo-insensitive and a reconstruction propagation angle. The reconstruction reference beam is provided onto the recording medium. Also, a succession of relative displacements in the recording medium is produced and each of the displacements are equal to the distance of the recording displacements with which the holograms were previously recorded.

Abstract: A linear conoscope producing a conoscopic interferogram of an object wherein the phase shift giving rise to the interferogram is substantially linearly dependent on displacement of an object from a geometrical axis. Two anisotropic optical elements are provided and oriented with respect to one another in such a manner as to cancel the predominant term in which the phase shift depends quadratically on displacement from the geometrical axis.

Abstract: A method and an apparatus for creating a holographic stereogram are provided for canceling noises localized to infinity and offering a high-quality hologram. The creating method is executed to display an image corresponding to a coordinate location on the hologram recording medium on the display unit, condense the laser beam transmitted through the display unit as an object beam at the coordinate location of the hologram recording medium, and apply part of the laser beam before transmission through the display unit as a reference beam onto the hologram recording medium, for sequentially forming stripped or dotted holographic elements on the hologram recording medium. The creating apparatus includes a first diffuser panel located close to the display unit, a mask, and a second diffuser panel, the latter two of which are located immediately before the hologram recording medium. The mask has an opening corresponding to the width of the holographic element.

Abstract: A high-resolution light-beam scanning apparatus utilizing only mass-producible holograms instead of utilizing auxiliary optical systems such as optical lenses or a mirror having curvature, and capable of compensating for disadvantages including scanning beam thickening and variation, failure of a rotatable hologram to rotate at a constant velocity, displacement of a scanning beam position in the scanning direction and the cross scanning direction due to a mode hop of a wavelength of a semiconductor laser, and deviation of a base of rotatable hologram from a parallel state. These disadvantages are detrimental to efforts for increasing the resolution of a hologram scanner and lowering the cost thereof. The light beam scanning apparatus includes at least two holograms with an optical path length difference .DELTA..PHI. along a scanning beam light flux. The path length is measured from a light source to a scanning surface in the first hologram, and is represented by .DELTA..PHI.<C(.lambda..sup.2 /D.lambda.

Abstract: An optical device for generating a signal based on a distance of an object from the optical device. The optical device includes a first polarizer, a birefringent crystal positioned optically downstream from the first polarizer, and a second polarizer arranged optically downstream from the birefringent crystal. The second polarizer creates a pair of interferograms by adjusting a phase of the light. Two outputs are generated by separately integrating an amount of light of at least a part of each of the pair of interferograms. Finally, the two outputs are combined such that the signal, depending only on the distance between the object and the optical system, is obtained.

Abstract: A method for improving the resolution and contrast of images associated with coherent recording is presented, which includes conventional reconstruction with a reference wave followed by re-imaging the intermediately formed image through a system based on techniques from confocal microscopy. This method provides the opportunity to bring the benefits of the optical confocal microscope, namely resolution, contrast improvement, and the accompanying three-dimensional visualization, to such diverse imaging regimes as infrared, X-ray, ultraviolet, as well as other wave propagation systems such as seismic, sonar and ultrasound imaging. In addition, through snap-shot acquisition of said coherent recordings, the capability of time resolution may be added, thus adding functionality in wavelength regions where the confocal microscope currently operates.

Abstract: Molded block optics system (10) writes and reads data from an optical storage medium and includes first molded optics block (12) for receiving reference beam (60) and original object beam (46) that contains a predetermined data set. First molded optics block (12) includes reflective surfaces (18, 20, 22, and 24) and spatial light modulator (50). Reflective surfaces (18, 20, and 24) include reference beam surfaces (24) and object beam surfaces (18, 20, and 22). Reference beam surfaces (24) direct reference beam (60) to optical storage medium (16) at predetermined location (54). Spatial light modulator (50) modulates object beam (46) and directs modulated object beam (46) to predetermined location (54). Reference beam (60) and object beam (46) form an interference pattern that writes data on optical storage medium (16). First molded optics block (12) also directs reference beam (60) to optical storage medium (16) for generating reconstructed object beam (64).

Abstract: A holographic recording apparatus includes first and second light sources for respectively generating first and second light beams. A mask is located in front of a hologram recording material and has an aperture. Interference fringes are recorded in a hologram cell on the hologram recording material corresponding to the aperture. A movement mechanism supports the hologram recording material masked by the mask and relatively moves the hologram recording material with respect to the mask in predetermined directions so that an interference pattern is formed in an area on the hologram recording material. A spatial frequency changing mechanism changes incident angles of the first and second light beams with respect to the mask.

Abstract: A method and device for measuring the mobility distribution of particulate elements using incoherent light holography, where the particulate elements are optically labeled. An elementary hologram is formed for each particulate element at a series of periodic moments representing the transfer function as a function of the instantaneous position of that element. The transfer function is modulated by a specified periodic transfer function for labeling each simple hologram and for generating conjugate elementary holograms integrated at each moment for forming a compound velocity hologram containing coded information for each particulate element. Each compound velocity hologram is decoded to obtain specified mobility information.

Abstract: Use of an aperture in the reconstructed beam in reconstruction of multiple holograms increases selectivity beyond that realizable by spatial multiplexing so as to permit differentiation of overlapping images. "Aperturization" is suitably used for differentiation in the y-direction in shift holography, depending on Bragg selection in the x-direction.

Abstract: A diaphragm having an aperture, the size of which is equal to or smaller than .lambda.f/p (.lambda. is the wavelength, p is the imaging resolution, and f is the focal length of an imaging optical system) is arranged on the focal plane of the object space of the imaging optical system, and object light via the aperture is imaged by the imaging optical system. The object light via the imaging optical system and reference light are brought to interference to form interference fringes, and an image of the interference fringes is sensed. Using the hologram sensed in this manner, the image of the object to be sensed is reconstructed by adopting an imaging optical system equivalent to that upon imaging, and setting the positional relationship between the formed hologram and the imaging optical system in correspondence with that between the imaging optical system and the imaging surface upon imaging.

Abstract: A high resolution film scanner or telecine uses a microlithographic diffuser laminate (24) arranged adjacent the film. The diffuser diffuses a collimated light beam produced from a light source and the optics of a film scanner or telecine. This type of diffuser is inexpensive, yet produces a more uniformly distributed light intensity and aids in the reduction in visibility of surface imperfections such as scratches on the scanned film.

Abstract: A method and apparatus for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader is preferably embodied as a handheld unit and comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. An optically transmissive spacer affixed to the front of the handheld unit allows ambient light to be collected at close range, and a diffuser may be used to reflect ambient light from the handheld unit to provide additional illumination at close range. A masked CCD detector with rectangular pixels receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of the CCD detector at high illumination levels. A correlated double sampling circuit coupled to the adaptive exposure circuit rejects common mode noise and allows operation in lower light levels.

Abstract: A method and apparatus are provided for reading bar codes or other images while reducing or eliminating the need for self-generated illumination. An image reader comprises an efficient optical collection system including an aperture with a high aspect ratio and/or a multi-focal lens or lenses. A CCD detector receives collected light and is coupled to an adaptive exposure circuit for preventing saturation of a CCD detector at high illumination levels. A correlated double sampling circuit receives the output of the CCD detector to allow lower light levels to be detected by the system. The correlated double sampling circuit is connected to a signal processing block which uses a derivative based technique for enhanced edge detection. Edge detection information may be provided to a decoder for decoding. Various other embodiments may utilize some but not all of the above elements, or may include additional refinements, while obtaining the benefit of reducing or eliminating the need for self-generated illumination.

Abstract: A new personal laser dosimetry badge records intentional or unintentional exposure to laser radiation. A Fresnel biprism is mounted over a layer of photopolymerizable material, preferably a polymer-dispersed liquid crystal material. A laser beam striking the apex of the biprism splits into two beams crossing at an angle which depends on the prism apex angle and the angle of incidence. These crossed beams form an interference pattern at the photopolymer with bright and dark fringes separated by a distance which depends on wavelength and the crossing angle of the two beams. The light triggers a photopolymerization reaction in the bright regions and records a permanent refractive index modulation, a hologram, which serves as a record of the laser interference pattern. Light incident normally on the badge will produce a normal index grating. Light incident at an angle will produce a slanted grating.

Abstract: The invention is embodied in a method of recording successive holograms in a recording medium, using at least a fan of M waves along at least a first axis with a separation angle between adjacent waves and directing the fan of M waves as a reference beam along a reference beam path onto the recording medium, successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to the reference beam path so that the signal and reference beams intersect at a beam intersection lying within the medium, the beam intersection having a size corresponding to beam areas of the reference and signal beams, producing a succession of relative displacements in a direction parallel to the first axis between the recording medium and the beam intersection of the signal and reference beam paths in synchronism with the succession of signal beams, each of the displacements being less than the size of the intersection whereby to record suc

Abstract: A confocal optical apparatus comprising a light source, a first aperture portion for passing light emitted from the light source and obtaining a point source, an objective lens for causing the light that has passed through the first aperture portion to converge on a measurement object, a second aperture portion located on a plane conjugate with the convergence surface on the measurement object, and light detectors for detecting light that has passed through the second aperture portion, wherein placing the first and second aperture portions in the same position and using them as the same aperture portion, as well as positioning the detection surfaces of the light detectors substantially on the same surfaces as the conjointly used identical aperture portions make it possible to reduce the size and weight of the apparatus, to perform three-dimensional shape measurements rapidly and accurately, and to facilitate the alignment of each portion.

Abstract: A manufacturing method for a hologram which can control the formation of a ghost hologram due to a surface reflected light caused on an interface with the atmosphere is disclosed. In the first manufacturing method for a hologram by a two-beam method or a one-beam method, on an interface between a substrate having a hologram photosensitive layer and the atmosphere is disposed a quarter-wave plate, and an incident light is converted from a circularly polarized light to a P-polarized light (or an S-polarized light) through the quarter-wave plate. On the other hand, in the second manufacturing method for a hologram, a substrate, which has a hologram photosensitive layer, is fittingly held by prisms on both sides thereof. A reference light is a P-polarized light, and an angle of the reference light to a surface reflected light on an interface of the reference light is set to be approximate to a right angle.

Abstract: A method for the manufacture of TIR holograms includes the division of an input laser beam into an object beam and a reference beam, the direction of the beams to a holographic recording layer so that the object beam is incident on a surface of the holographic recording layer following transmission through an object mask, so that the reference beam is incident on the other surface of the holographic recording layer at an angle such that following passage through the holographic recording layer it is totally internally reflected back into the holographic recording layer and so that the two beams are superposed at the holographic recording layer, and the displacement of the input laser beam causing the object and reference beams to traverse together the holographic recording layer. The method is especially useful for obtaining a high uniformity of exposure of the holographic recording layer.

Abstract: This invention relates to a process for forming a reflection hologram. A process for forming a volume reflection hologram is provided wherein the formation of secondary holograms is suppressed by the placement of index matched filters contiguous to at least one surface of the photosensitive recording element during formation of the hologram.

Abstract: Camera provided with a lens, a diaphragm and a photographic film or plate arranged behind the diaphragm and located on a plane which is normal to the optical axis of the lens. The lens comprises: at least two light inlets; a doublet or triplet for each light inlet, suitable for collimating the incoming light and for correcting any aberrations; and a merging system, suitable for merging the homologous light rays which leave the doublets or triplets before they reach the photographic film. The photographic film or plate is a high-resolution film.

Abstract: In a system of proximity printing utilizing coherent light, a technique of phase only image correction is disclosed. Specifically, a holographic corrector plate is utilized. The image on the holographic corrector plate is produced by constructing a holographic image from the broadcast image and the intended working image. The broadcast image and the intended working image are placed in precise proximity printing alignment. With the respective images aligned, a coherent light beam is split to provide two temporally and spatially coherent beams. One of the temporally and spatially coherent beams scans the broadcast image. The other temporally and spatially coherent beam scans a mask containing the intended working image in a corresponding scan. A plane of beam intersection is chosen, with precise correspondence between rays at any point on the broadcast mask to rays from corresponding points on the working image mask.

Abstract: A disk-based holographic storage media includes a disk fabricated from a holographic storage media. A plurality of holographic storage regions are defined within the storage media such that pages of holographic data can be stored therein in the form of an interference grating. A Read/Write head is provided for containing the optics necessary to read information from the holographic storage region and write information thereto. The Read/Write head moves along the radial direction of the disk with the disk stepped by a motor to discrete angular positions, comprising the address of the storage region along with radial positioning of the Read/Write head. Each of the storage regions is diamond-shaped and oriented such that the apexes thereof are oriented along a common radial column line. Adjacent columns have the storage regions disposed in alternating rows or tracks. This allows for a higher packing density.

Abstract: A hologram exposure system that includes a holographic recording medium, a holographic prism adjacent the holographic recording medium for most efficiently diffracting light of a predetermined wavelength and at a predetermined incidence angle, a first monochromatic beam directed toward the holographic prism at the predetermined incidence angle, and a second monochromatic beam directed toward the holographic prism at an incidence angle that allows the second monochromatic beam to be transmitted by the holographic prism without any diffraction. The holographic prism diffracts the first monochromatic beam and transmits the second monochromatic beam without any diffraction to produce a diffracted first construction beam and a non-diffracted second construction beam which interfere in the holographic recording medium to form holographic fringes therein.

Abstract: The present invention concerns a holographic process including a stage consisting in producing the hologram of a point P thank to an optical device including a crystal (131) and two polarizers (132,135) placed respectively before and after the crystal (131), characterized by the fact that it includes in addition the stages consisting in: 1) separating the answers of the optical system corresponding to two different polarizations and 2) combining both these answers in order to obtain a signal which depends only on the distance between the point P ant the optical device. The invention concerns also a device which allows the implementation or this process.

Abstract: A holographic interference exposing device using a visible laser source and a chopper to easily align the optical system while confirming the light path of the laser beam with the naked eye. The exposing device comprises a main laser source generating a short wavelength laser beam, a beam splitter for splitting the laser beam into two laser beams to cause a difference in the light path of the laser beam and to form an interference fringe on a semiconductor substrate, mirrors for guiding the laser beam to the beam splitter, and mirrors for focusing the two laser beams on a surface of the semiconductor substrate, an auxiliary laser source generating a long wavelength laser beam, and a chopper making the light path of the long wavelength laser beam get together with that of the short wavelength laser beam. The auxiliary laser source generates a visible laser beam having a wavelength longer than that of an ultraviolet laser beam.

Abstract: An exposure apparatus for reproducing a mask pattern onto a photo-sensitive surface of a substrate using holographic techniques.

Abstract: A holographic storage assembly is provided which utilizes a large holographic storage media (36) disposed between two reflecting surfaces (40) and (42). An optics system (44) is disposed between the two reflecting surfaces (40) and (42) is operable to generate both a reference beam (58) and a data beam (50). The data beam (50) and reference beam (58) are generated on a virtual spot plane (100), which is then imaged from the surface of the reflecting surface (42) onto the much larger surface of the media (36). This is operable to record an interference grating at a storage location (56). During a playback operation, a reconstructed data beam (64) is generated and reflected from the surface of the mirror (40) onto a detector (68) in the deflector system (44).

Abstract: A hologram manufacturing apparatus and a hologram manufacturing method for manufacturing a hologram optical device by a split exposure method are disclosed. The manufacturing apparatus comprises light shield means having a spatial light modulator having a light transparent area and a light non-transparent area thereof controlled corresponding to an input signal, and drive means for driving the spatial light modulator by supplying the signal to the spatial light modulator. The light shield means is arranged closely to a photosensitive material.

Abstract: An encoded hologram that produces a first image and a second image pursuant to playback illumination, wherein the first image is resolvable by human vision while the second image is not resolvable by human vision when the playback illumination comprises non-coherent broad band illumination, and wherein the second image is machine readable when the hologram is illuminated with playback illumination that is based on the original reference beam.

Abstract: An optical apparatus for controlling a wave front of a coherent light including at least a coherent light source, an electrically addressable liquid crystal device having a plurality of pixels receiving the light from said light source, and a signal generator for recording a complex amplitude distribution or hologram on the liquid crystal device.