Abstract: A holographic storage system includes a storage media in the form of a disk that is operable to incrementally rotate under a moveable optics system contained in a gantry. The gantry reciprocates along the radial axis of the media in response to a drive mechanism. A laser is operable to direct a beam to a mirror that reflects the light beam along the reciprocating axis of the gantry. The gantry contains a spatial light modulator which is operable to receive the incoming light beam and transform it through a transform lens down to a storage location on the surface of the storage media. A reference beam is reflected from a reflecting surface at a predetermined angle and directed to the storage location by an elliptical mirror to interfere with the data beam and perform a record operation. During data reconstruction, when the reference beam is generated a reconstructed data beam is directed toward the reconstruction optics and a detector array. The detector array is also contained on the gantry.

Abstract: The method involves directing first and second separate illuminating beams towards a photosensitive film from separate fixed apparent beam source positions respectively in such a manner that the beams are caused to overlap at the point of incidence at the photosensitive film. Stationary interference fringes are generated and the beams are caused to scan in a raster type pattern over the photosensitive film in such a manner whereby overlapping of the beams is maintained throughout the exposure of the film. The apparatus in one embodiment involves the generation of a third illuminating beam which is used to control means to control an associated scanner to effect synchronised movement of the second beam with the first beam. A further embodiment involves memorising the scanning movement of beam in a memory and using the memorised scanning pattern to control the scanner to maintain beam overlap.

Abstract: A holographic diffuser for use in conjunction with a back-lit flat-panel display and a source of illumination in the form of one or more tubular lamp segments is recorded so as to receive light from the lamp segments and scatter it preferentially along a plane perpendicular to the axis of the bulbs. In a back-lit display having vertically oriented tubular lamps, the diffuser scatters substantially more in the horizontal dimension, thus filling in the gaps of light intensity between the bulbs, which would otherwise be viewed by an observer, as with conventional diffusers. The high aspect ratio diffusers of the present invention are preferably formed by projecting coherent radiation through a mask having dimensions functionally related to the desired final aspect ratio, with an optional collimating lens being used to project that mask to infinity. A contact exposure process is also described.

Abstract: An optical scanning device comprises a light source for emitting a light, a light guide path being adapted to receive the emitted light and to transmitting the received light therein, a plurality of diffraction gratings disposed on the light guide path for taking out the transmitted light in a form of an array, and a liquid crystal shutter for scanning the taken out light in the form of the array. An optical scanning device comprises a first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, a light guide path disposed on the first substrate for entering a light transmitted therein into the liquid crystal layer, a plurality of micro lenses disposed on the second substrate for converging the entered light, wherein, assuming that n.sub.CORE is a refraction index of a light guide medium forming the light guide path, that n.sub.LCON is a refraction index of a liquid crystal when an electric field is applied (on), and that n.sub.

Abstract: The invention provides an optical space switch device which provides variable interconnection of one- or two-dimensionally spatially multiplexed optical signals. The optical space switch device comprises a plurality of optical space switch stages stacked to form a multi-input multi-output optical space switch. Each of the optical space switch stages comprises a plurality of 2-input 2-output optical switches, each of which comprises a polarization control layer and an optical path shifting layer. The optical path shifting layer has a bypass mode in which it outputs beams of light along optical axes and an exchange mode in which it shifts beams of light by diffraction.

Abstract: The holographic element of the present invention includes a holographic grating pattern that is impressed in the media of the element utilizing beams of electromagnetic energy of wavelength .lambda..sub.o. The holographic grating pattern is capable of manipulating a beam of electromagnetic energy having a wavelength .lambda..sub.c at which the media is not necessarily suitable for recording. The method for manufacturing the holographic element utilizes an object beam and a reference beam having aspherical wavefronts of wavelength .lambda..sub.o to create the grating pattern in the media. In the preferred embodiment, the aspherical object beam and reference beam are created utilizing parent holographic devices recorded with spherical beams. An alternative embodiment of the present invention is a doublet holographic device which incorporates two holographic elements that are formed in accordance with the present invention to manipulate a beam of electromagnetic energy of wavelength .lambda..sub.

Abstract: Methods of and apparatus for manipulating beamed electromagnetic phenomenon comprises a generator (20) of aligned conical or pyramidal elements (21a-21f) each having conical or pyramidal inner and outer surfaces (24a-24f and 23a-23f). When the beamed electromagnetic phenomenon includes a zero-order component the elements (21a-21f) minimize or eliminate the zero-order component allowing for devices such as on-axis holographic displays, demodulators and optical processors for computers.

Abstract: A method and apparatus for making a holographic shadowgram of an object are disclosed. The method and apparatus include a light source for generating and expanding a coherent light beam. The method and apparatus also include a reflector for reflecting the coherent light beam to simultaneously produce a diffuse object beam and a coherent reference beam such that differential vibration between the object and reference beams is substantially eliminated, and for illuminating the object with the object beam and creating an interference pattern between the object and reference beams. The method and apparatus further include a recorder for recording the interference pattern to produce the holographic shadowgram.

Abstract: A hologram plate manufacturing apparatus comprising a copying optical element disposed in opposed relation to a photosensitive surface of a hologram plate. The copying optical element is arranged so that its one surface facing the photosensitive surface of the hologram plate has a plane configuration and its other surface has a convex or concave configuration. On the convex or concave surface there is formed a reflection film for effectively reflecting incident light. Also included a refraction index adjusting layer which is provided between the photosensitive surface of the hologram plate and the convex or concave surface of the copying optical element, the refraction index adjusting layer having an index of refraction substantially equal to indexes of refraction of the hologram plate and the copying optical element.

Abstract: An exposure apparatus capable of making exposure for concentric circular periodic grating is provided with a quarter-wave plate (4), an ND filter (8a) having step-wisely different transmissions with boundaries of circle or a group of circles, an axially symmetric-shaped patterning mask (8b), an interference lens (9), before a sample substrate (10) having a photosensitive film (11). The interference lens (9) has a form of rotation symmetry with respect to optical axis (9L), and its incident surface (9P) is a flat plane, and its exit surface (9S) is a surface of revolution which is close to a circular cone.

Abstract: An apparatus 10 for exposing a curved grating pattern of monochromatic light on a photoresist coated semiconductor wafer 12 includes an argon gas laser 14 that outputs a monochromatic light beam 16. This monochromatic light beam 16 is filtered and collimated to produce a monochromatic light beam with a planar wavefront 24. A portion of this planar wavefront passes through a cylindrical lens array 26 and a first baffle slit 30, producing multiple cylindrical wavefront 34 that is incident upon a hypotenuse face 38 of a right angle prism 40. Another portion of the planar wavefront passes through a second baffle slit 32, producing a smaller planar wavefront 36 that is also incident upon the hypotenuse face 38 of the right angle prism 40. A destructive interference between a reflected multiple cylindrical wavefront 92 and a direct planar wavefront 90 inside the prism 40 produces a curved grating pattern of monochromatic light on an adjacent prism face 42.

Abstract: A method of recording holograms for use in optical scanners comprises the steps of generating a reference beam by means of a reference source, generating an object beam by means of an object source, and illuminating a photosensitive surface with both said object beam and said reference beam, wherein said object beam is divergent in a first direction and non-divergent in a second direction.

Abstract: An image of an object embedded in a diffusing medium is formed by propagating a coherent or equivalent light pulse through the diffusing medium and applying a reference pulse so as to gate precisely the first emerging light transmitted through the diffusing medium. An ultra-short pulse, having a duration on the order of 150 fs, insures that only the first emerging light is used to form a hologram. Instability in the diffusing medium, which may be inherent therein, as is the case with living tissue, or artificially induced therein, such as by vibrating the specimen, ensures that a subsequent hologram has a different background noise and speckle pattern. Integration of such holograms causes the background noise to average out, but time-invariant features, such as the object being imaged, become increasingly more visible as more holograms are integrated.

Abstract: A high finesse holographic Fabry-Perot etalon and method of making a high finesse holographic Fabry-Perot etalon is disclosed. Particularly, a holographic Fabry-Perot etalon which achieves high finesse despite non-flat interfaces between the etalon media is presented. In a preferred method of fabricating a high finesse Fabry-Perot etalon, single step recording of both holograms simultaneously, with the spacer and substrates in place, is employed which preserves full phase synchronization between the holograms. In spite of imperfections or irregularities of the interface surfaces of the substrates or spacers, the holographic fringes in the holograms remain flat even for slightly different refractive indices between the various media. The position and flatness of the fringes remains similar to perfect Fabry-Perot etalon structure.

Abstract: A method and an apparatus for making a hologram wherein interference patterns to be recorded on a hologram plate are prevented from travelling, thereby enabling a high quality hologram to be made.

Abstract: Methods for creating a plurality of holographic diffraction grating patterns in a raster scan fashion. In accordance with the method, the desired pattern is made up of a large plurality of individual spots, each spot comprising a holographic diffraction grating of a predetermined grating spacing and angular orientation for that spot. Variation of the angular orientation and/or grating spacing between spots and/or groups of spots provide the desired holographic effect. The spot locations may vary as desired, including locations drawing out a desired pattern, and two-dimensional orthogonal matrices in which a pattern is drawn by variations between spots or group of spots as in a raster scan type image. Various embodiments and methods for creating the same are disclosed.

Abstract: Holographic apparatus and methods are provided for generating high resolution telescopic images using low cost, small aperture lenses. Holographic media, such as photorefractive crystals, are used in conjunction with multiple and/or synthetic aperture techniques. In a multiple aperture system, a thin nonlinear holographic medium is used with a plurality of small optical lenses to compensate for the inherent piston and tilt errors of the lenses, thereby providing higher resolution. In another embodiment, synthetic aperture techniques are accomplished by illuminating a far field object with coherent light, deriving a reference beam from the coherent light, and changing the position of the reference beam in accordance with a computational formula. A hologram is formed from a sequence of image exposures in the holographic media, each made at different positions with respect to the image.

Abstract: A system that provides a structure which makes use of a recording geometry in which no significant Seidel induced aberrations arise. The recording geometry results in a pattern recorded on a photosensitive surface, thereby creating the hologram on the scanning disc. Reconstruction of the recorded object may be made by exposing the scanning disc to substantially monochromatic light. The hologram on the scanning disc not only directs the reconstruction beam, but also focuses it. An optical element may be used during reconstruction to correct for bow and linearity, and also optimize flatness of the focal plane. Reconstruction also involves achromatization, or correction of beam placement because of mode hops or drift in laser frequency. The reconstruction comprises both pre-scan holograms and post-scan holograms. Recording of the post-scan hologram is achieved with a plurality of lenses which possess different collimating properties in the vertical and horizontal planes.

Abstract: The present invention discloses a novel method for effecting illumination of an arbitrary aperture. The method comprises a first step of providing a developed hologram comprising a plurality of spatially known discrete holographic optical elements that have been generated from a common arbitrary aperture. A second step comprises directing a plurality of dedicated reconstructing beams to assigned ones of the holographic optical elements, so that a composite hologram beam illuminates the arbitrary aperture.

Abstract: An apparatus for making a hologram scale is comprised of a reference diffraction grating on which a light becomes incident and from or by which the incident light is emitted or reflected as a diffracted light, and a recording material, wherein at least two diffracted lights of the diffracted light are caused to interfere with each other as an object wave and a reference wave so as to form a hologram scale on the recording material. Further, an apparatus for making an assembled hologram scale, a hologram scale, an assembled hologram scale and a moving member having a hologram scale are also provided.

Abstract: Apparatus and method for storing holographic synthesized information for reflection integral Bragg holograms, free of the limitations of dispersing elements (such as unilateral diffusing screens, conventional lenticular screens and Fresnel lenses), multiple reference beams, mirrorized indexing or other similar materials or techniques. These holograms accurately satisfy Bragg's condition, provide an expanded (and essentially normal) vertical viewing range and can be displayed both flat (in which case the image is behind the film plane) or concave towards the viewer (in which case the image is in front of the film plane). Flat and curved holograms can be combined together. The final holographic images are produced directly from motion picture film, without intermediate transfer prints as required by the prior art. All are front illuminated. By curving the developed hologram for viewing a high definition projection image is obtained.

Abstract: The present invention provides a method and apparatus for producing a hologram from a series of two-dimensional images horizontally different in line of sight from each other. The holographic apparatus employs original images produced by photographing an object from different directions, an object optical system which makes a light be incident upon original image to project an object beam onto photo-sensitive material, and a reference optical system which projects a reference beam of a same wavelength as the object beam toward the photo-sensitive material. The horizontal component of the object beam can be converged at a rear point i.e., a point of view at image reproduction, relatively distant from the photo-sensitive material on which a hologram is produced. When the hologram is reconstructed, a beam having the same wavelength as when recorded is converged at the rear point of view, so that the reconstructed image can be viewed in a same color free from any color shading.

Abstract: A method and apparatus for the collation or fine comparison of closely related images made with coherent light, such as those that may arise in holographic interferometry, in holo-photoelasticity, or in speckle interferometry.

Abstract: A camera for use in holography comprises a source of coherent radiation (55), a beam splitter (55,56) for splitting radiation from said source into a reference and a recording beam, a film holder (62) for holding a recording medium (61), means for directing the reference beam on to the recording medium, means for directing the recording beam on to an object and means for combining the recording beam after reflection from the object with the reference beam to form a hologram within the recording medium.

Abstract: A photorefractive device is provided for converting an image-bearing incoherent input beam to a high contrast coherent output beam the intensity of which varies as the square of the input intensity pattern. The device uses an incoherent image beam to write a holographic grating directly in a photorefractive medium. In one embodiment, a parallel, laterally displaced, telecentric system of lenses is used to split a quasi-monochromatic, incoherent image-bearing beam into two equal components. The two components are superimposed at the surface of the photorefractive medium to produce the hologram. In a second embodiment, the incoherent input beam is directed through a physically translating external grating to write the hologram in the photorefractive medium. The moving grating improves the diffraction efficiency of the hologram under the influence of an applied electric field and stabilizes the temporal response characteristics for signal processing.

Abstract: A holographic recording and reproducing system for recording holographic images of an object positioned in a first medium and replaying said images in a second medium incorporates means for enhancing the relative sensitivity of the system to radiation capable of producing said holographic images.

Abstract: In an imaging process and system by transillumination of a medium illuminated by transparency by a beam, an acoustic transducer emits an acoustic wave in the medium which interferes with the beam. The frequency of the light passing through the medium is then shifted from the value of the frequency of the acoustic wave. A collimating device whose object focus is located at the intersection of the acoustic wave and the light beam collects the light diffused by the medium.

Abstract: A transmission holographic element (30) comprises a holographic material (330) deposited onto a substrate (31) to form a composite substrate structure. The substrate (31) is coated with a mirror coating (32) prior to the deposit of the holographic material (33) which is reflecting at the reading wavelength and non-reflecting at the recording wavelength. This allows the use of substrates that need not be of good optical quality because when the holographic element is exposed to light at the reading wavelength, light is reflected by the mirror coating before passing through the substrate. In addition, the mirror coating is protectred from damage during processing since it is between the substrate (31) and holographic material (33).

Abstract: A fast, accurate system for manufacturing holographic projection screens. The invention (10) includes a mechanism (28) for moving holographic film (26) along a longitudinal axis thereof in a first direction. A mechanism (12) is provided for directing and maintaining an input beam (22) onto the film (26) as the film (26) is moved. The application of a reference beam (23) is then effective to create an interference pattern on the film (26) with the input beam (22). The mechanism (12) for maintaining the input image at a fixed location on the film includes a polygon shaped mirror mounted to rotate at a rate determined in accordance with the rate of movement of the film. An image stabilization system (40) is also provided which includes a detector (58) for monitoring an interference pattern created by the signal beam and the reference beam. Circuitry (60) is included for providing control signals in response to the detector (58) outputs. A phase shifter (44) induces a phase shift in the reference beam.

Abstract: A compact, self-contained monolith hologram display apparatus includes a laser diode mounted on an edge of a solid glass plate having a front surface with a hologram mounted thereon. The beam is expanded within the glass plate and is reflected off an opposing mirrored contoured edge surface that collimates the beam and directs it onto an angled reflection grating. The reflection grating is mounted onto an edge which is canted with respect to the front surface. The reflected beam diffracts from the grating and impinges upon the hologram to provide for reconstructed image that has achromatic properties.

Abstract: A method and apparatus for registering an image using coherent radiation. Spatial homodyne means are employed to generate component signals which comprise a homodyne equivalent of the image, and the component signals of the homodyne equivalent are registered at a registering medium. Using a new principle of construction, the invention achieves on standard registering media a substantial improvement in conrast resolution. Indeed, the number of contrast levels that can be registerd by the invention is the square of the number that can be registered by the prior art. The application of temporal submodulation in a device embodying the invention additionally provides tensor parasitic phase-shift invariance.

Abstract: A holographic camera assembly includes a portable, light-tight housing having a removable cover to access the interior thereof. Camera components are positioned upon an optics tray within the housing which is vibrationally isolated from the housing. The film is releasably mounted within a frame and includes a releasable film casing protecting the film from ambient light. The frame, including the film and casing, is releasably mounted upon a rotatable platform in one corner of the tray and a three-dimensional object of one's choice is positioned therebehind. The cover is replaced upon the housing making the interior thereof light-tight. Means operable at a control panel externally of the housing selectively raise and lower the casing about the film. When in the fully raised position, a coherent light beam is allowed to travel along a fixed path (by action of a timed shutter mechanism) to pass through the film to strike the object. The reflection of light by the object back to the film creates the hologram.

Abstract: First and second coherent beams illuminate a common area on an exposure station. A phase detector senses the relative phase between the first and second beams to provide a control signal. There is at least one phase shifter in the path of at least one of the coherent beams. The control signal is coupled to the phase shifter to adjust the phase imparted thereby so that the relative phase between the first and second coherent beams is substantially constant.

Abstract: A method is provided for reconstructing an image transmitted through a thick distorting medium. A remote source provides coherent light at the object plane, and a local source, typically derived from the remote source, provides corresponding light that is coherent with respect to the remote source. Light from the remote source is directed through the thick aberrator and into a holographic medium, such as a photorefractive crystal, to interact with corresponding light from the local source and produce a volume hologram. An angularly multiplexed volume hologram, which covers the entire object field, is written into the holographic medium by successive exposures of light from the remote and local sources for successive pixels of the object plane. Light from an object, which comprises two-dimensional information from the object plane, can be reconstructed by the volume hologram after being distorted by the thick aberrator.

Abstract: Novel designs for efficient coupling mechanism for the conversion of typical profile laser beams into J.sub.o -profile beams are presented. Several specific embodiments are provided which employ non-linear optical mechanisms in the conversion process, and other embodiments are provided which utilize holography in the conversion process.

Abstract: A holographic method of the type implementing a conoscopic system including a birefrigent crystal inserted between two polarizers and a photosensitive element, wherein the method includes a step consisting in inserting one-dimensional optical means on the path of the light rays such that the conoscopic system only collects light that is parallel or quasi-parallel to a plane including the axis of the conoscopic system. The invention also provides apparatus for implementing the method.

Abstract: A holographic apparatus of the type comprising a conoscopic system including a birefringent crystal inserted between two polarizers, wherein the apparatus also includes an aperture angle limiter inserted on the path of the light rays and wherein one of the birefringent crystal and the aperture angle limiter is disposed off the optical axis of the apparatus.

Abstract: The invention provides a non-linear projection system, which includes a variable acuity non-linear holographic optical element (HOE), and an apparatus for creating the HOE. The projection system comprises a computer, a light valve which projects images generated by the computer, a lens train for focusing the images projected by the light valve, an HOE for the non-linear refraction of the focused images and a hemispherical viewing screen. The system additionally provides means for maintaining the center of the projected images in alignment with center of the field of view of an observer. The variation of the pixel size and spacing created by the system matches the variation of the human visual acuity of the observer permitting a realistic view to be presented while requiring a minimum of computer data to be generated and projected. The apparatus for creating the HOE utilizes a laser beam, three lens trains and a holographic recording medium.

Abstract: An inexpensive wallpaper, which may be plastic and self adhesive. Using the positive features and advantages of thin-layer holograms and other existing technology, the claimed invention produces a changing, moving or stable 3-D effect in the presence of a low-powered laser illuminating system. In usual (incoherent) light, the claimed wallpaper reflects light as does a standard wallpaper. On the claimed wallpaper, images of any kind can be additionally printed without damaging the coherent 3-D reconstruction. The claimed wallpaper produces 3-D images, whose qualities are not affected by mechanical damage of any kind, including scratching or scraping, and it can also be produced in a washable embodiment. The suggested object incorporates recognized computer techniques, by which an image of any level of complexity can be included. The wallpaper can be printed on plastic or other media by sequentially applying a pre-prepared small-area matrix.