Abstract: A hologram surface to express a phase distribution, a visual field in which a solid image can be seen; and a stereoscopic display limit are set in a virtual space. A target to be stereoscopically displayed is subsequently expressed in the virtual space by a set of micro polygons. A plurality of slice planes which are parallel with the horizontal plane are set into the virtual space including the target. The line segments which intersect the polygons are obtained for every slice plane. The detected line segment is divided or clipped as necessary and is finally divided into the portion which can be always seen from the whole region of the visual field and a portion which is obstructed by another line segment and can be seen from only a part of the visual field, thereby extracting the line segment.

Abstract: An optimized design method of a holographic optical element by calculating a correction coefficient so that an evaluating amount of a reconstructed light reconstructed by the holographic optical element can be minimized, the correction coefficient determining an aspheric term included in a phase transfer function, the phase transfer function representing a shape of an interference fringe recorded on the holographic optical element. According to the method, the wavefront aberration is expressed via a linear function of the correction coefficient by positioning a main axis point on a characteristic evaluating surface onto which the reconstructed light is projected, so that a wavefront aberration of the reconstructed light can be minimized. Then, the correction coefficient is calculated based on the linear function so that the evaluating amount can minimized.

Abstract: A computer-generated hologram recording apparatus includes a diffraction image generator which receives an input image signal representing an object and computes a corresponding diffraction pattern with a first sampling density. An interpolation processor is connected to the diffraction image generator via an intermediate page memory. The interpolation processor subjects the diffraction pattern to the interpolation process to create an interpolated diffraction pattern with an increased second sampling density. An interference pattern generator is connected to the interpolation processor to compute an interference caused pattern between the interpolated diffraction pattern and a reference wave by converting amplitude and phase distributions of the input image signal into the intensity distribution. A multi-beam scan printing apparatus records the interference pattern on a previously selected recording medium for later reproduction by use of white light.

Abstract: Light emitted from a coherent light source undergoes fine adjustment of its polarizing direction by a polarizing device and is directed to a liquid crystal device through a collimating optical system. The polarizing device is capable of fine-adjusting the polarizing direction in accordance with the wavelength of the incident light, thereby providing a high contrast ratio. When an image is recorded by holography using such a liquid crystal spacial light modulator, it is possible to obtain an image of high quality.

Abstract: Apparatus for horizontally scanning an image corresponding to electronic video input information utilizing a Bragg Diffraction cell in which collimated light from a laser directed through the cell is modulated by a real-time fourier transform of a line of video input information, thereby to produce a one line acoustic hologram in the cell which is reconstructed at a infinity as a stationary image corresponding to the horizontal line of video information. Using a suitable lens system, the stationary image is re-imaged at a plane positioned at a fixed distance from the Bragg Diffraction cell. The scanner is useful in image projection systems, in which the horizontal line image is vertically scanned by a galvanometer driven mirror vibrating in synchronism with the vertical blanking interval of the input video.

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: This is a board to transport and convert optical outgoing free-space signals from a spatial light modulator which comprises: at least one detector to process the outgoing free-space signal; at least one signal transmitter to process the outgoing free-space signal; and at least one outgoing optical signal carrier to carry a converted outgoing signal. Other methods and devices are disclosed.

Abstract: A hologram exposure apparatus for and method of obtaining a hologram using a photoresist for an in-line type interferometer wherein a photoresist substrate is detachably mounted on a substrate rotating device. A concentric pattern of a hologram from a source of light is projected onto the photoresist on the substrate mounted on the substrate rotating device while rotating the substrate and moving a projecting device in a direction at right angles with the rotary shaft of the photoresist substrate.

Abstract: A method for precisely controlling the overall average diffraction efficiency of a hologram including the steps of (a) providing a hologram layer that includes a hologram formed pursuant to hologram forming exposure and development, (b) coating the hologram layer with a photoresist layer, (c) masking the photoresist layer with a mask having opaque and transparent areas wherein the proportion of the opaque areas relative to the transparent areas is selected pursuant to the desired diffraction efficiency, the opaque and transparent areas being sufficiently small so as to have little noticeable effect when the resulting hologram is played back, (d) exposing the photoresist layer to actinic illumination through the mask transparent areas, (e) developing the photoresist layer to remove the photoresist in the areas illuminated by the actinic illumination to uncover the areas of the recording material corresponding to the transparent areas of the mask, (f) etching the recording material to remove the areas thereof t

Abstract: Computer-processed or computer-generated objects can be used to build holograms whose images are close to or straddle the hologram surface. No preliminary or first hologram is required. The hologram is built up from a number of contiguous, small, elemental pieces. Unorthodox views from inside the object are required for the creation of these elements. One method of generating the views employs unique object manipulations. The computational transformations ensure that no singularities arise and that more-or-less conventional modeling and rendering routines can be used. With a second method, a multiplicity of conventional object views are collected. Then, all pixels in these conventional viewplanes are reassigned to new and different locations in the new viewplanes for the elemental views. These methods may be used to build rainbow holograms or full parallax holograms. When properly executed they are visually indistinguishable from other types.

Abstract: A near-real-time holographic display for operations at a remote work site where a three dimensional database is collected with a laser range scanner. The database is then divided into discrete two dimensional segments or depth planes. A holographic recording material is then sequentially exposed to multiple depth planes through a stack of three spatial light modulators in a multiplane exposure process. This procedure is repeated for all depth planes in the database. The holographic recording material is then rapidly developed for viewing of the remote work site in a holographic image that simulates natural vision.

Abstract: The preferred embodiment of this invention is illustrated in FIG. 2 showing an ultrasonic holographic imaging apparatus 50 having a multiple lens system 52 that is capable of providing both zoom and focus capability. The system 52 includes lens 54 and 56 that are independently mounted on lead screws 62 and 64 for movement relative to each other along an optical axis 57. The movement of the system is controlled by drive system 66 and 68 that have encoders 72 and 74 for accurately positioning the lens 54 and 56 relative to each other in response to signals from a microcontroller 76. The microcontroller 76 is operator controlled through control device 78 and 80 to provide both zoom capability and a focus capability.

Abstract: A hologram efficiency adjusting process that includes scanning the brightness effect of a hologram, which is either the hologram to be adjusted or a hologram representative of the hologram to be adjusted, to provide brightness vs. position information. The brightness information is utilized to produce a variable duty cycle half-tone mask that contains a pattern defining the areas of the hologram which are to be removed, with the pattern being unresolvable by the viewer of the hologram from which holograms have been removed pursuant to the mask pattern. The hologram to be adjusted is then photoresist coated and etched in accordance with the mask. Alternatively, the brightness information can be utilized to directly expose, for example by a laser scanner, photoresist disposed on the hologram to be adjusted.

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 radially symmetric iterative discrete on-axis hologram has a high diffraction efficiency for a correspondingly small f-number. The radially symmetric hologram has a plurality of concentric constant radial phase fringes. Each fringe has a predetermined plurality of radial phase rings and each fringe corresponds to a predetermined plurality of radial phase transition points and a radial phase value between the radial phase transition points. The radially symmetric iterative discrete on-axis hologram also has radial phase fringes with a predetermined number of phase levels, at least two adjacent fringes have a phase level difference which is greater than one and less than the predetermined number minus one. The radially symmetric iterative discrete on-axis hologram is fabricated by determining a plurality of concentric fringes of constant phase with a plurality of radial phase transition points and radial phase values between the radial phase transition points for each concentric fringe.

Abstract: An apparatus for displaying a three-dimensional image of a plurality of tomographic images by storing pictorial information of a tomographic image in an image convering element, forming interference fringes between a reading light beam which is transmitted through the image converting element and is modulated in accordance with the pictorial information stored therein and a reference light beam, and recording the interference fringes on a photographic plate. A three-dimensional image is reproduced by projecting the reference light beam onto the thus developed photographic plate. The image converting element is formed by a Pockels readout optical modulator. An intensity and position of a coherent light beam is modulated in accordance with the pictorial information of the tomographic image, and the thus modulated coherent reading light beam is made incident upon the Pockels readout optical modulator.

Abstract: Methods for generating holograms from a computer model of any object employ a combination of numerical and optical means. An illumination model and the light dispersion properties of the object are specified. The hologram is synthesized from a plurality of smaller hologram elements. Each individual element sustains a field of view of the object. The light rays from the object lying within the field of view and along the lines of sight are sampled by the computer. The sample density should not exceed the resolution limit set by the size of the hologram element. Each light ray is specified by a direction and an amplitude function. The hologram element is obtainable from a Fourier Transform fo the sampled rays. In one embodiment, optical means are employed to physically reproduce the sampled light rays using coherent radiation. The reproduced coherent light rays are then interfered with a coherent reference beam to form the hologram element.

Abstract: This invention concerns a method and apparatus of using the relatively thin holographic material of a transmission holographic optical element in such a manner whereby a narrow spectral bandwidth may be achieved. The interference fringe planes oriented through the depth of the material are interrogated by way of the edge of the holographic optical element whereby the holographic optical element is caused to respond, in use, in the manner of a relatively thick reflection holographic optical element of considerable effective thickness. The apparatus takes the form of a narrow bandwidth optical filter which is interrogated by a tightly focussed interrogating beam.

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: A preferred embodiment of the optical reconstruction assembly 50 in which the assembly 50 includes an assembly housing 52 that is a unitary unit for supporting a spatial filter 72 and a light source 74 in a single plane at the optical length "L" from a collimating lens 86. A liquid container 88 is mounted to the assembly housing 52 containing the holographic liquid 90. The light source 74 and the spatial filter 72 are spaced a fixed distance "A" which is less than the optical diameter "D" of the collimating lens 86.

Abstract: A three dimensional display system includes a laser for generating a laser light signal. The signal is expanded and collimated using a traditional lens system and is directed to an acousto-optic modulator wherein it is modulated to generate a three dimensional image such as a holographic image. The modulation signal for the modulator is provided by a data processing system. The data processing system applies signals to the modulator that encode a diffraction pattern. The diffraction pattern is realized by the modulator upon application of the signals and the three dimensional image is produced by the modulated light signals. The image is demagnified by a demagnifier, and subsequently, imaged by a viewing lens. A horizontal scanner continuously multiplexes segments of the holographic image and compensates for the motion of segments across the modulator. A vertical scanner is provided to properly vertically position horizontal lines of the holographic image.

Abstract: This is an optical interconnect system. The system comprises: at least one signal transmitter; at least two signal receivers; at least one DMD in the same plane as the signal transmitter; and a hologram, whereby the phase of the original beam from the signal transmitter may be programmably changed, by a DMD, such that the beams received at the signal receiver may cancel or reinforce. Other methods and devices are disclosed.

Abstract: A method of manufacturing a display having diffraction grating patterns, includes the steps of (a) obtaining a plurality of two-dimensional images by observing an object at a plurality of positions, and inputting images of the plurality of two-dimensional images in a computer, (b) selecting nth image data from the plurality of image data, (c) inputting data of a reproducing light source position and a view direction, (d) inputting predetermined dot data of the nth image data, (e) determining a pitch and a direction of a grating and an area of a dot on the basis of the data of the reproducing light source position and the view direction and the dot data, (f) moving an X-Y stage to a predetermined position on the basis of the dot data and delineating the diffraction grating by using an electron scanning unit, (g) sequentially incrementing an address of the dot data and repeating the steps (d) to (f) until all data corresponding to the nth image data are processed, and (h) selecting another image data, and repea

Abstract: A recording medium has a first fringe pattern which is described by a first spectral bandwidth and a first image blur factor. The recording medium also has a second fringe pattern which is described by a second spectral bandwidth and a second image blur factor, the first spectral bandwidth being different from the second spectral bandwidth, and the first image blur factor being substantially equal to the second image blur factor. By providing multiple holograms in the single recording medium, the spectral bandwidths of each hologram are combined to provide an overall spectral bandwidth. Since the image blur factors of each hologram are substantially the same, i.e., overlap, when the two holograms are combined, the overall image blur factor is not increased. Indeed, it decreases at the same time the thickness of the recording medium is increased by a factor which is equivalent to the number of exposure in the single recording medium.

Abstract: New methods for producing computer generated holograms to be used for a liquid crystal spacial light modulator having a plurality of pixels, wherein the amplitude component of a coherent wave disturbance is corrected by taking into account the phase distortion due to the twist of liquid crystal molecules of the liquid crystal spacial light modulator.

Abstract: A method for generating holographic optical elements such as power spectrum filters is carried out using a printer and a computer. A signal function is input into the computer and traced by the printer to produce a power spectrum envelope of the signal function. The power spectrum is then filled in with a grating pattern whose line spacing is determined by the desired diffraction of coherent radiation beams used to interrogate the optical element.

Abstract: Replay apparatus for replaying in a second medium a hologram recorded by recording apparatus in a first medium having a refractive index different from that of said second medium wherein said replay apparatus incorporates correcting means for correcting aberrations introduced by said recording apparatus.

Abstract: A method for producing a display with a diffraction grating pattern comprising the steps of reading image data, assigning color for light exposure and moving a slit of an optical system to a position corresponding to the assigned color, moving an origin of an X-Y stage and setting initial data of the assigned color, reading data of an assigned address of the image data and opening a shutter of the optical system for light exposure when data of the assigned color exists, moving the X-Y stage to increase the address by one and repeating the data-reading and shutter-opening step until no further data exists, and changing the assigned color and repeating the above sequence of steps until no further color exists.

Abstract: A fiber optic point source is utilized to generate a first wavefront which is intersected with a second wavefront to form a desired interference pattern in a recording medium. The point source is moved relative to the recording medium during exposure in order to reduce multiple order scattering noise, and to provide a relatively large translational motion which is gradual and generally follows an angular scanning motion of the fiber optic point source.

Abstract: A fiber optic point source is utilized to generate a first wavefront which is intersected with a second wavefront to form a desired interference pattern in a recording medium. The point source is moved relative to the recording medium during exposure in order to reduce multiple order scattering noise, and a feedback monitoring system permits determination of portions of the recording medium requiring increased exposure.

Abstract: A passive distribution system for electromagnetic radiation using waveguides and couplers wherein radiation from a source is distributed to a number of destination points, including means at destination points for determining the power levels received at the destination points and means for transmitting from the destination points to the source location information representing said received power levels.