Abstract: A method for effecting the desired optical characteristics of an optical system (10) using phase diffractive optics. Incident light (Bi) is directed onto a surface (12i) of a material (12) whose index of refraction (n) is variable over the material. Passage of the incident light through the material effects the phase and amplitude of the light waveform. An optical map (Om) is determined for the surface of the material. This map comprises variations in the index of refraction over the material surface, and the map, in effect, represents any of a range of refractive and diffractive optical elements such as a mirror (1), a lens (2,3,6,7), or a diffraction grating (100). The map is dynamically written onto the material to map the material such that the incident light's passage through the material corresponds to the passage of the light through the optical element currently emulated by the material.

Abstract: An analog controlled angle diffuser and associated methods provide a wavelength insensitive diffuser with a controlled output. The diffuser has free formed shaped analog fringes, i.e., fringes which have a continuous cross-section from their peak to their termination. Preferably, the depth of the analog fringes will be at least 2&pgr;, even more preferably at least 2O&pgr;. Advantageously, the pattern of the diffuser is computer-generated.

Abstract: A system for producing a white-light interference hologram includes a camera adapted for recording a first and a second bitmap image of a scene from separate vantage points, and the separation distance of the vantage points, a computing engine adapted to compute three-dimensional x, y, and z characteristics of an interference hologram topology for the scene from the bitmap image and separation data, wherein x and y are two dimensional locations of bits in a bitmap of the topology and z is a depth dimension for each x,y bit, and a printer adapted to print in color the x,y bitmap, and to create the depth dimension z at each x,y bit location, providing thereby a three-dimensional interference hologram topology for the scene. In a preferred embodiment the depth dimension is created by electrophoresis, using a medium having an electrophoretic gel layer, with the ink applied to the gel in a bit-mapped pattern being ionic in nature, and capable of being migrated in the gel layer by electrophoresis.

Abstract: A device for the geometric calibration of a CCD camera, which includes a coherent light source and a synthetic hologram arranged relative to the coherent light source so that the hologram generates a real three-dimensional test structure f(x,y,z) around a focal plane of the CCD camera using coherent light. A method for geometric calibration of a CCD camera using a coherent light source and a synthetic hologram which includes the steps of calculating the synthetic hologram to provide a well-defined ideal three-dimensional test structure f(x,y,z) taking into account idealized camera optics of the CCD camera to be calibrated, illuminating the hologram using the coherent light source so that a real three-dimensional test structure f(x,y,z) is generated around a focal plane of the CCD camera, and evaluating in parallel a plurality of sensor pixels by determining a respective section plane through the real test structure f(x,y,z) from individual image information of each of the plural sensor pixels.

Abstract: In a system in which images having parallax data, and which are made up of plural images containing the parallax information are processed with viewing point conversion, and the resulting new images having parallax data are used, as in a system of generating a holographic stereogram, a unit for generating the images having parallax data is to be independent from other unit or units. To this end, the information necessary to perform viewing point conversion processing of converting the viewing point for an object is attached to images having parallax data when the images having parallax data have been produced. When the images having parallax data is exchanged between the unit for generating the images having parallax data and other unit or units, the exchanged images having parallax data need to be those to which the information has been attached.

Abstract: The present invention concerns methods and devices for creating and printing variable size and variable resolution holographic stereograms and holographic optical elements using computer rendered images of three-dimensional computer models or using computer processed images. The present invention is an apparatus and method for printing one-step, full-color, full-parallax holographic stereograms utilizing a reference beam-steering system that allows a reference beam to expose a holographic recording material from different angles. More particularly, a coherent beam is split into object and reference beams. The object beam passes through an object beam unit in which a rendered image is displayed, while the reference beam passes through the reference beam-steering system. The object and reference beams interfere with each other at an elemental hologram on a holographic recording material.

Abstract: An image data generating method for generating image data corresponding to a planar holographic stereogram is provided. First, an object of imaging device is rotated, while the distance between the object and the imaging device is kept substantially constant, for shooting plural images of different viewing angles by the imaging device. The image data of plural images is then corrected for keystone distortion. The image data corrected for keystone distortion is then processed with viewing point conversion processing for converting the viewing point for generating image data of images recorded on the holographic stereogram. In addition, image data including the information for plural images is compressed for storage in the internal storage device of the computer.

Abstract: The invention makes it possible to form a hologram for reproducing a three-dimensional image easily free of limitations placed by the size of the three-dimensional image to be reproduced, the size of the hologram and reference light for reproduction. A controller calculates a three-dimensional interference pattern for generating reproduction light associated with a desired three-dimensional image when a recording medium (1) is illuminated with reference light for reproduction, divides the three-dimensional interference pattern into partial interference patterns and calculates reference light and information light for recording for each of the partial interference patterns. A final hologram is formed by illuminating the recording medium (1) with reference light and information light for recording using a head (10) while changing the relative positional relationship between the recording medium (1) and the head (10) by moving the head (10) with a VCM (13) while transporting the recording medium (1).

Abstract: A single photographic subsystem 2 photographs an original image for a hologram and provides an image information file Fp. In addition, this subsystem provides a management information file Fm for storing management information about the image information file Fp. An image processing section 4 generates a composite image file Fs by applying specified image processing to the image information file Fp and the management information about the management information file Fm provided from the single photographic subsystem 2 via a transmission system 3a. A hologram printer 5 receives the composite image file Fs generated in the image processing section 4 and prints a holographic stereogram based on this composite image file Fs.

Abstract: A signal image is transmitted by write light from a transmission type liquid crystal element 4 to an optically-addressed type parallel-aligned nematic-liquid-crystal spatial light modulator 6. The numerical aperture NAL of a relay lens 5, the pitch P of the pixel structure of the transmission type liquid crystal element 4, and the wavelength &lgr; of light from the write light source 1 are set with the condition 1/2P<NAL/&lgr;<1/P. As a result, the signal component caused by the pixel structure can be erased. Furthermore, no degradation is generated in the entire range of the spatial frequencies of the signal image that can be produced by the transmission type liquid crystal element 4.

Abstract: The method consists of transforming a digital two-dimensional image defined by a real function into a complex two-dimensional image defined by a complex function, oversampling the complex image, simulating the production of a diffracted image resulting from the diffraction of an optical wave by the oversampled complex image, and adding a complex field representing a reference optical wave to the resulting diffracted image to produce a hologram. The hologram produced in this way can be used to produce images in three dimensions or in telecommunications.

Abstract: A pixellated diffractive device includes a multiplicity of pixels (12,22) in turn divided into multiple sub-pixels (13,23). The device is related to one or more pixellated diffraction surface structures which when illuminated generate respective corresponding optically variable images. The sub-pixels (13,23) of each pixel of the diffractive device include diffractive elements (13a,23a) arranged in one or more groups, the diffractive elements of each group matching diffractive elements of a corresponding single pixel of the respective pixellated diffraction surface structures. In each pixel of the device the diffractive elements (13a,23a) of the or each said group are intermixed with other sub-pixels and cooperatively contribute a single element of the corresponding optically variable image which is generated on illumination of the diffractive device.

Abstract: An information medium consists of an essentially circular or polygonal disk having at least two pairs of sides parallel to one another which have the same distance to one another in each pair. To reliably read stored data from such an information medium at high speed, a hologram is disposed on at least one side of the disk at its center or at the intersection of two crossing symmetry lines which can be reconstructed with a reference beam incident to the side at a right angle to a pattern consisting of essentially concentric circles, with the reference beam forming the axis of said pattern.

Abstract: A method for displaying computer generated holograms of a display object is performed by computing fringe patterns produced by light interference from the display object. The steps are summarized as follows: three-dimensional data of the display object are converted into computational data for fringe pattern generation; a sampling rule for sampling computational data is selected; computational data are sampled according to a selected sampling rule; wavefronts generated by light illumination are computed by assuming that each sampled position has a light source; fringe patterns generated by computed wavefronts and a reference beam are computed; fringe patterns are stored as hologram images; sampling and a wavefront generation are repeated for all data; and a series of hologram images thus generated are displayed successively.

Abstract: The invention provides a computer-generated hologram which can be viewed in white at the desired viewing region and a reflective liquid crystal display using the same as a reflector. The computer-generated hologram H is designed to diffuse light having a given reference wavelength &lgr;STD and incident thereon at a given angle of incidence &thgr; in a specific angle range. In a range of wavelengths &lgr;MIN to &lgr;MAX including the reference wavelength &lgr;STD wherein zero-order transmission light or zero-order reflection light of incident light on the computer-generated hologram at a given angle of incidence is seen in white by additive color mixing, the maximum diffraction angle &bgr;2MIN of incident light of the minimum wavelength &lgr;MIN in the wavelength range and incident at the angle of incidence &thgr; is larger than the minimum diffraction angle &bgr;1MAX of incident light of the maximum wavelength &lgr;MAX in the wavelength range and incident at said angle of incidence &thgr;.

Abstract: There is provided an electro-optical component comprising (a) a substrate, (b) a phase-variable element carried on the substrate, (c) a memory carried on the substrate for storing data representative of a phase state for the phase-variable element; and (d) a controller carried on the substrate, for utilizing the data and setting the phase state for the element. There is also provided an electro-optical component comprising (a) a substrate, (b) a phase-variable element carried on the substrate, and (c) a circuit carried on the substrate for computing and applying a phase state for the phase-variable element.

Abstract: A digital holography device, applicable for example to the 3D mapping of objects, is used to determine the complex amplitude of a signal wave coming from an object illuminated by a known illumination wave. For this purpose, the device includes a source for the generation of two mutually coherent waves, the object illumination wave and a reference wave, the two waves having a phase difference &phgr;i(t) that is a function of time. The device also includes a mechanism configured to induce an interference, on a detection device, between the reference wave and the signal wave coming from the object. The detection device enables a temporal sampling of the interference pattern resulting in the acquisition of a number N of interferograms, N being greater than or equal to 2.

Abstract: Lithography processes that use multiple layers require registration between layers. The accuracy requirement depends on the application of the lithograph. For microlithography, the registration requirement could be less than one micron. Systems that use lenses for imaging such as optical steppers can image conventional alignment marks through those lenses. A unique microlithography system that employs holograms has properties that are not compatible with known alignment techniques. The present invention is a new system for alignment of holographic microlithography elements.

Abstract: A system for producing a white-light interference hologram includes a camera adapted for recording a first and a second bitmap image of a scene from separate vantage points, and the separation distance of the vantage points, a computing engine adapted to compute three-dimensional x, y, and z characteristics of an interference hologram topology for the scene from the bitmap image and separation data, wherein x and y are two dimensional locations of bits in a bitmap of the topology and z is a depth dimension for each x,y bit, and a printer adapted to print in color the x,y bitmap, and to create the depth dimension z at each x,y bit location, providing thereby a three-dimensional interference hologram topology for the scene. In a preferred embodiment the depth dimension is created by electrophoresis, using a medium having an electrophoretic gel layer, with the ink applied to the gel in a bit-mapped pattern being ionic in nature, and capable of being migrated in the gel layer by electrophoresis.

Abstract: An optical device receives light from an adjustable light source, focuses part of the light into an optical waveguide, and directs another part of the light toward a control unit as monitor light for feedback control of the light source. The optical device is an optical plate with a computer-generated hologram formed on at least one surface to focus light into the optical waveguide. The monitor light may be reflected at this surface or another surface of the optical plate. The monitor light may be focused by the same or another computer-generated hologram.

Abstract: A system for producing a white-light interference hologram includes a camera adapted for recording a first and a second bitmap image of a scene from separate vantage points, and the separation distance of the vantage points, a computing engine adapted to compute three-dimensional x, y, and z characteristics of an interference hologram topology for the scene from the bitmap image and separation data, wherein x and y are two dimensional locations of bits in a bitmap of the topology and z is a depth dimension for each x,y bit, and a printer adapted to print in color the x,y bitmap, and to create the depth dimension z at each x,y bit location, providing thereby a three-dimensional interference hologram topology for the scene. In a preferred embodiment the depth dimension is created by electrophoresis, using a medium having an electrophoretic gel layer, with the ink applied to the gel in a bit-mapped pattern being ionic in nature, and capable of being migrated in the gel layer by electrophoresis.

Abstract: Method for the preparation of holographic diffusers where the holographic diffuser is designed through iterative calculations according to the Fraunhofer theory of diffraction and some constrain conditions. In the iterative calculation some constrain conditions that can change the magnitude of the light passing through the diffuser are used to design the diffuser. A novel iterative calculation is disclosed such that uniformed mixing of colors and high light utilization efficiency of the diffuser may be provided.

Abstract: Two pixel-oriented methods for designing Fourier transform holograms, pseudorandom encoding and minimum distance encoding when combined usually produce higher fidelity reconstructions than either method produces individually. In previous studies, minimum distance encoding was defined as the mapping from the desired complex value to the closest value produced by the modulator. This method is compared with a new minimum distance criterion in which the desired complex value is mapped to the closest value that can be realized by pseudorandom encoding. Simulations and experimental measurements using quantized phase and amplitude modulators show that the modified approach to blended encoding produces more faithful reconstructions than the previous method.

Abstract: A scheme for producing computer generated holograms in which a motion vector of each object to be displayed is detected, objects are classified according to their motions, a hologram fringe pattern for each classified group of objects is calculated separately by image processing stored basic patterns, and a hologram to be displayed is produced, by synthesizing all separately calculated hologram fringe patterns. In another aspect, a gaze point of the observer is determined, and a hologram to be displayed is produced by using high resolution hologram fringe patterns for objects located at the gaze point and low resolution hologram fringe patterns for regions other than the gaze point.

Abstract: A method for the numerical reconstruction of digital holograms which allows simultaneously amplitude and quantitative phase contrast imaging. The reconstruction method computes the propagation of the field that would be diffracted by the hologram during a standard hologram reconstruction. The method requires the adjustment of several reconstruction parameters for the definition of a digital replica of the reference wave. When the set-up used for the hologram creation produces phase aberrations, the method includes a digital method for the correction of the phase aberrations. The phase contrast image is quantitative, meaning that the reconstructed phase distribution can be used for quantitative measurements. The method can be used to reconstruct a set of holograms taken in different conditions. The method can be used to reconstruct several images from a single hologram taken with more than one reference waves and/or more than one object waves.

Abstract: A phase watermark hologram “W” is composed of a blaze having binary phase difference of 2&pgr;×n, where “n” is a natural number of more than 1. An watermark appears in response to phase difference, which changes by a faked blaze. A phase watermark hologram “W” and a phase hologram “D” indicating data are formed on a same surface of a substrate mixed in arbitrary locations and arbitrary ratio of both holograms.

Abstract: A phase-shift digital holographic apparatus shifts the phase of a reference wave by a phase shifting means, produces holographic image data by a holographic image pickup means having an image forming surface on which an object wave and the reference wave fall simultaneously, processes a plurality of holographic image data produced by the object wave and a plurality of reference waves of different phases determined by shifting the phase of the reference wave by the phase shifting means by an object wave calculating means to calculate phase data on the phase of the object wave and amplitude data on the amplitude of the object wave, and constitutes object wave data of the phase data on the phase of the object wave and the amplitude data on the amplitude of the object wave calculated by the object wave calculating means by a reproduced image calculating means and subjects the object wave data to a predetermined transformation process to calculate a reproduced image.

Abstract: An optical system comprises two optical paths P1, P2, and an optical path changer for changing the optical length of the two optical paths. The optical path changer includes two phase modulators M1, M2 one coupled to each of the paths. A driving system is configured to apply power to the phase modulators to drive them in the same direction and to change the power applied to the phase modulators in opposite directions so as to change the length of each optical path in a different direction. As a result, the relationship between the changes in the power applied to the phase modulators and the resulting changes in the phase of light beams passing through the optical system becomes substantially linear.

Abstract: A scheme for producing computer generated holograms in which a motion vector of each object to be displayed is detected, objects are classified according to their motions, a hologram fringe pattern for each classified group of objects is calculated separately by image processing stored basic patterns, and a hologram to be displayed is produced by synthesizing all separately calculated hologram fringe patterns. In another aspect, a gaze point of the observer is determined, and a hologram to be displayed is produced by using high resolution hologram fringe patterns for objects located at the gaze point and low resolution hologram fringe patterns for regions other than the gaze point.

Abstract: A user is able to interact with and modify an electronic holographic image using a force-feedback (or haptic) device, which is capable of sensing and reporting the 3D position of its hand-held stylus and “displaying” appropriate forces to the user. Thus, a user can feel and modify specified shapes in the haptic workspace. The haptic workspace is precisely registered with the free-standing, spatial image displayed by a holographic video (holovideo) system. In the coincident visuo-haptic workspace, a user can see, feel, and interact with synthetic objects that exhibit many of the properties one expects of real ones, and the spatial display enables synthetic objects to become a part of the user's manipulatory space.

Abstract: A technique for mapping working images to adjacently and continuously tiled subapertures having CGHs on a plate is disclosed with the result that the entirety of a working area of a plate is completely covered with working subapertures, these subapertures usually being rectangular. The design technique thereafter determines a phase function which approximately maps desired regions on each subaperture from portions of the working image in the workpiece plane. Steps in the process include first a determination of the size and shape of subapertures representing each feature. Second, a determination of the geometric transformation for each feature is made. Thereafter, backpropagation or other refinement to create the desired intensity profile at the workpiece is made.

Abstract: A coherent beam is converted into a light flux having an expanded width at a predetermined position closer to a photosensitive element. Part of the expanded light flux is irradiated directly on the photosensitive element as a reference beam. The remainder of the expanded light flux is diffused, and its optical direction is changed. Thus, the remainder of the expanded light flux not irradiated directly to the photosensitive element is converted into a scattered beam advancing as an object beam toward the photosensitive element. Interference fringes are formed on the photosensitive element by using the reference beam and the object beam.

Abstract: An image recording apparatus is capable of reducing a vibration of a hologram recording medium so that a holographic stereogram which provides an excellent reproduced image can be prepared in a short time period. A vibration member 55 is provided on the light path of reference light L4, and a hologram recording medium 10 is intermittently fed with the medium 10 kept in contact with an end portion 55a of the member 55. The reference light L4 passes through a slit 56 of the vibration restriction member 55 and is irradiated onto the hologram recording medium 10 through an opening portion 57 opened at the end side 55a.

Abstract: A real-time, dynamic, free space-virtual reality, 3-D image display system which is enabled by using a unique form of Aerogel as the primary display media. A preferred embodiment of this system comprises a 3-D mosaic topographic map which is displayed by fusing four projected hologram images. In this embodiment, 4 holographic images are projected from 4 separate holograms. Each holographic image subtends a quadrant of the 4&pgr; solid angle. By fusing these four holographic images, a static 3-D image such as a featured terrain map would be visible for 360 degrees in the horizontal plane and 180 degrees in the vertical plane. An input, either acquired by 3-D image sensor or generated by computer animation, is first converted into a 2-D computer generated hologram (CGH). This CGH is then downloaded into large liquid crystal (LC) panel. A laser projector illuminates the CGH-filled LC panel and generates and displays a real 3-D image in the Aerogel matrix.

Abstract: A microscopy and/or lithography system uses a comparatively low-resolution image projection system, which has a very small numerical aperture but large image field, in conjunction with a microlens array comprising miniature lens elements, each of which has a large numerical aperture but very small field. The projection system contains a small aperture stop which is imaged by the microlenses onto an array of diffraction-limited microspots on the microscope sample or printing surface at the microlens focal point positions, and the surface is scanned to build up a complete raster image from the focal point array. The system design thus circumvents the tradeoff between image resolution and field size which is the source of much of the complexity and expense of conventional wide-field, high-NA microscopy and microlithography systems.

Abstract: Conventional display technology can be used to display crude computer generated holograms (CGH), and can be extended to moving displays. However, the ones best suited from the standpoint of illumination flexibility, such as the common Liquid Crystal Displays (LCDs), switch very slowly. Thus systems with far better dynamic—rapid response requires very complex drive electronics. A non-memory ceramic PLZT, dynamic holographic display medium, provides much faster response time relative to common LCD technology. This system, which is the major embodiment of the present invention, also exhibits good spatial display capability. The system of the present invention, can display Fast Fourier Transformation (FFT) Computer Generated Holograms (CHHs); thus allowing the use of FFT based manipulation of images.

Abstract: A method for encoding zero-order phase-only holograms, and the holograms so encoded. The amplitude and phase of each point of a discrete mathematical transform, such as a Fourier transform, of an image to be encoded, are encoded as regions of a corresponding pixel of a transparent filter, with suitably selected fractional areas and optical path lengths. The various optical path lengths may be created by manipulating the filter's index of refraction, or by manipulating the thickness of the filter, preferably by etching. Various encoding schemes are presented, appropriate to etching systems with low lateral resolution, to etching systems with high lateral resolution but depth resolution limited to a discrete number of depths, and to etching systems with limited resolution both laterally and in depth.

Abstract: An optical pickup includes: a light source, an object lens, and an aberration correction unit for correcting aberration by giving a phase difference to a light beam. The aberration correction unit corrects astigmatism caused by an optical system of the optical pickup.

Abstract: A synthetic aperture system for producing a non-periodic pattern in a region of overlap. The system includes a source of electromagnetic radiation producing a plurality of electromagnetic beams, a plurality of beam controllers positioned to receive a respective one of the plurality of electromagnetic beams and direct the respective electromagnetic beam into the region of overlap; and a system controller in electrical communication with each of the plurality of the beam controllers. Each beam controller controls at least one of the phase, amplitude and polarization of a respective one of the plurality of electromagnetic beams in response to control signals from the system controller. The result is a non-periodic pattern formed within the region of overlap by the interference of a plurality of electromagnetic beams in response to the control signals from the system controller.The invention also relates to a method for producing a non-periodic pattern in a region of overlap.

Abstract: A scheme for producing computer generated holograms in which a motion vector of each object to be displayed is detected, objects are classified according to their motions, a hologram fringe pattern for each classified group of objects is calculated separately by image processing stored basic patterns, and a hologram to be displayed is produced by synthesizing all separately calculated hologram fringe patterns. In another aspect, a gaze point of the observer is determined, and a hologram to be displayed is produced by using high resolution hologram fringe patterns for objects located at the gaze point and low resolution hologram fringe patterns for regions other than the gaze point.

Abstract: A broadband diffractive diffuser contains at least three levels, with approximately a phase shift of .pi. between at least two of the at least three levels. Such a diffuser provides light with more than two phasor vectors at the zero order. The presence of the more than two phasor vectors reduces the zero order diffraction efficiency at non-design wavelength, increasing the usefulness of the diffuser at wavelengths other than the design wavelength. Preferably, the diffractive diffuser includes a plurality of regions, approximately 50% of an area of the plurality of regions presenting a phase shift of .pi. at a design wavelength, approximately 25% of the area of the plurality of regions presenting a phase shift of 2.pi. at the design wavelength, and approximately 25% of the area of the plurality of regions presenting a phase shift of 0 at the design wavelength.

Abstract: A method of making a holographic device comprising sensitizing a plurality of layers and stacking the layers to form a composite structure. Each layer is sensitized to at least one color wavelength. The method further includes directing at least two laser beams at the composite structure. Each of the laser beams is oriented at an angle with respect to an incident surface of the composite structure such that the laser beams intersect one another within one of the layers of the composite structure. The laser beams are moved along the layer to create interference patterns in the sensitized layer.

Abstract: An image data generating method for generating image data corresponding to a planar holographic stereogram is provided. First, an object or imaging device is rotated, while the distance between the object and the imaging device is kept substantially constant, for shooting plural images of different viewing angles by the imaging device. The image data of plural images is then corrected for keystone distortion. The image data corrected for keystone distortion is then processed with viewing point conversion processing for converting the viewing point for generating image data of images recorded on the holographic stereogram. In addition, image data including the information for plural images is compressed for storage in the internal storage device of the computer.

Abstract: A diffusing function and a lens function are provided on a single surface. Such a structure may be formed from a computer generated hologram including free form regions having a phase shift associated therewith, i.e., the computer generated hologram being shifted within the free form regions by the phase shift relative to the computer generated hologram outside the free form regions. When the computer generated hologram includes zero and .pi. regions, the zero and .pi. regions may be transposed within the free form regions.

Abstract: An optical device for use in optical communication optical network units, having an aptitude for efficient production, manufacturing cost reduction and size reduction, comprising: a first CGH element 21 for converting a multiplexed light from the first input terminal 11 into a parallel light beam; a wavelength splitting filter 23 for deflecting a light having passed through the CGH elements according to wavelengths; a second CGH element 22 for directing a first wavelength component separated by the wavelength splitting filter to the first output terminal 12; an optical path splitting means 22 for guiding a second wavelength component separated by the wavelength splitting filter to a desired optical path; a third CGH element 24 for directing a beam of a second wavelength component having passed through one optical path 27 to a second output terminal 18; and a fourth CGH element 26 guiding a beam of the second wavelength component from the second input terminal 17 to the optical path splitting means 24 so as to

Abstract: Apparatus which allows selection and generation of a variety of hologrammatic optical wavefronts. A device, which comprises a substrate layer of varying thickness and an electro optic layer, with a voltage dependent refractive index mismatch between the two, is used to modulate transmitted light, thus generating a hologrammatic wavefront. Said modulation can be changed by variation of an applied voltage and this changes the wavefront which is generated. The range of wavefronts which can be generated is defined by the distribution of substrate layer thicknesses across the device.

Abstract: Used as a propagation function is a half-plane propagation function which is restricted such that it has a value only within a half plane in a predetermined direction perpendicular to a propagating axis in a plane which is perpendicular to the propagating axis. According to a convolution integration with this function, the wavefront of object light on a hologram surface is determined, whereby hologram data is produced. Thus produced hologram is read out by means of readout light. After the light with a wavefront forming the conjugate image of the object to be viewed is blocked, the image of the object to be viewed is observed.

Abstract: A beam homogenizer that minimizes undesired intensity variations at the output plane caused by sharp breaks between facets in previous embodiments. The homogenizer includes a hologram made up of irregularly patterned diffractive fringes. An input beam illuminates at least part of the hologram. The hologram transmits a portion of the input beam onto an output plane. In doing so, the energy of the input beam is spatially redistributed at the output plane into a homogenized output beam having a preselected spatial energy distribution at the output plane. Thus, the illuminated portion of the output plane has a shape predetermined by the designer of the homogenizer.

Abstract: A method of designing a spatial phase modulation element which has a plurality of hologram surfaces with mutually different phase patterns, and a spatial phase modulation element produced in the method. The spatial phase modulation element is designed to have a variable-phase medium located on one side of each of the hologram surfaces and modulating means for modulating the phase patterns of the hologram surfaces independently of each other. Further, if the number of output patterns to be obtained with the spatial phase modulation element is n and if the number of hologram surfaces is N, the spatial phase modulation element is so designed as to meet the condition n.gtoreq.N+2, N.gtoreq.2.

Abstract: This specification discloses a hologram reconstructing apparatus having interference fringe forming means for forming optical interference fringes in conformity with an input signal, information input means for successively inputting different bits of interference fringe information to the interference fringe forming means, and illuminating means for illuminating the interference fringe forming means with a plurality of beams of light differing in wavefront from one another.