Abstract: A table type display device, in which a high resolution display with an unremarkable connection is realized at the time of large screen display by using a screen with a composition having few bending is described. In a table type display device comprising plural M of projectors 1L, 1R for projecting luminous flux to form an image, plural N of reflection mirrors 2L, 2R for bending optical paths of luminous fluxes projected from respective plural M of projectors 1L, 1R, screen 3 of horizontal installation type for projecting luminous fluxes for which optical path is bent, by the plurality N of reflection mirrors 2L,2R onto the predetermined region, respectively, the screen comprises a transparent base member 7 for reducing flexure of the screen, optical sheet 9 substantially for making luminous fluxes projected respectively from the plural M of projectors 1L,1R uniform, and a diffusing screen for imaging the image.

Abstract: The invention relates to a method for displaying three-dimensional images. In the method light beams (Le) are associated to several different screen points (P) of a screen (20). The light beams (Le) produce different views associated to different emission directions (E). The emission directions (E) are associated to the individual screen points (P). The light beams (Le) are generated by projecting light beams (Ld), according to the angle of the adjacent emitting directions. According to the invention, light beams (Le) without viewing direction information are generated, essentially simultaneously, with pixels (Cd) having different co-ordinates. These pixels (Cd) are pixels of a two-dimension display (50), and they are associated to different emitting directions (E) of the appropriate screen points (P).

Abstract: In a method of producing video screen holograms, a real video screen is illuminated by means of a narrowband light for producing a hologram of the real video screen. A plurality of individual recordings is carried out, each covering only a partial area of the real video screen being imaged in the hologram. The individual recordings take place, for example, by means of a scanning pulsed laser beam. The individual recordings are assembled to form the video screen hologram of the entire video screen. A recording device for this purpose comprises a scanning device for guiding the light radiation over the video screen and a light source which generates pulsed light radiation. The light source is, for example, a laser system with a pulsed q-switched oscillator and with an optical parametric oscillator.

Abstract: A holographic apparatus includes a mask for modulating a signal beam to generate a modulated signal beam; a conical prism, which has a cone portion and a base portion, for refracting a reference beam to generate a refracted reference beam, wherein the refracted reference beam interferes with the modulated signal beam in a holographic medium to thereby record data thereon, the base portion facing the holographic medium. The holographic apparatus can be miniaturized by a positional relationship between the conical prism and the holographic medium.

Abstract: A scanning pattern generator and a method for microlithographic multi-beam writing of high precision patterns on a photosensitive substrate (11), the system comprising a light source (1), preferably a laser, for generating at least two light beams, a computer-controlled light modulator (4), a deflector for scanning the beams on the substrate and an objective lens (10) to contract the at least one light beam from the light source before it reaches the substrate, wherein at least the objective lens is arranged on a carrier (22) being movable relative to the substrate (11) and the light source (1). Hereby, the carrier defines a movable optical path relative to the remaining, stationary optical path. Further, the system comprises means for altering the stationary optical path in order to maintain telecentricity for the beams as they impinge on the photosensitive substrate during the movement of the carrier and the movable optical path.

Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: A method of producing a big size holographic screen for projection of the stereoscopic or multiview 3-dimensional color images is proposed, where a narrow and elongate slit-shaped diffuser is recorded on the hologram as an object to ensure the well defined viewing zone forming in course of the image projection. As compared with the previous art the diffuser length is increased by the calculated value to provide undistorted color reproduction on whole screen surface. The parameters required for the recording of the holographic screen, including the position of a photoplate with respect to the diffuser, the position of a reference wave point source with respect to the diffuser, the distance from which an image is observed and so on are determined by consideration of the phase relationships between the reference, object, projector and reconstructed waves on the photoplate surface.

Abstract: The present invention relates to a method for producing light-scattering elements by holographic illumination of a layer (10) of a photo-sensitive material on a support plate (1) and subsequent development of the layer (10) in order to generating a surface structure. The method is distinguished in that the illumination occurs using at least two mutually coherent luminous beams (2,3) which have passed through one or a plurality of primary diffusers (8,9) respectively were reflected at one or a plurality of primary diffusers, the luminous beams (2,3) being irradiated from different directions and being at least partially superimposed on the layer (10) while forming an interference pattern. This method permits producing diffusers having a leveled scatter profile in a simple manner.

Abstract: In accordance with teachings of the present invention, a device accomplishes the task of reducing or preventing reflections of the reference beam off a diffuser from striking the holographic recording material. First, the device absorbs a large percentage of the reference beam power so that portion of the reference beam never reaches the diffuser. Second, the device blocks the small amount of reference beam that is incident on the diffuser and reflects back toward the film. Thus, the proposed device operates as an absorber-blocker (AB) for the reference beam.

Abstract: Apparatus for generating a dynamic image includes a laser light source for generating a coherent beam of light; optics for separating the light beam into a reference beam and an object beam; a lenslet light modulator, including an array of lenslets and a pixilated light modulator having a plurality of light modulating pixels associated with each lenslet in the array, the lenslet light modulator being located to modulate the object beam; image processing electronics for driving the lenslet light modulator with dynamic image data to produce a dynamic image at a recording plane; and optics for interfering the dynamic image and the reference beam at the recording plane to produce a hologram of the dynamic image in a holographic recording medium located in the recording plane.

Abstract: A method of fabricating a hologram screen having a large visual range and a hologram imaging apparatus used for the particular method of fabricating the hologram screen are disclosed. A plurality of mirrors (3) extended toward a plurality of photosensitive members (5) are arranged at a plurality of end portions (21), respectively, of a light diffuser (2). At least a reference beam (41) and object beams (42) passed through the light diffuser (2) are radiated on a plurality of the photosensitive members (5) individually thereby to form a plurality of holograms. These holograms are integrated with each other by being arranged two-dimensionally thereby to fabricate a hologram screen. Among the mirrors (3), a reference beam-side mirror (31) arranged nearer to the light source of the reference beams (41) is extended from the light diffuser (2) by a length varied with the position of the photosensitive member (5) to be exposed.

Abstract: An image display device comprising a holographic screen and an image projection device for projecting an image beam onto the holographic screen at an upward or downward angle is provided, wherein a forward view color difference &Dgr;u′v′ between a chromaticity value (u′, v′) at the center of the holographic screen when a white image is projected onto the holographic screen by the image projection device and a standard chromaticity value (u′o, v′o) is 0.04 or less when the projection angle of the image beam onto the center of the holographic screen is set to any angle within a specified projection angle range of 20 to 45°, whereby a image display device and holographic screen can be provided wherein the range of the projection angle of the image beam, in which an image with excellent color reproducibility can be displayed, is wide.

Abstract: A method and system of projecting light on a planar surface to produce an image for tracing is disclosed. The system includes a projector that has a light source and a signal conditioner that is operably connected to the projector. A computer is operably connected to the signal conditioner. A scanner is connected to the projector. A test pattern from the computer is projected from the projector through the scanners to visually align an image to a sector on a work surface. A grid is operably aligned with the work surface. A geometric pattern from the computer is then projected by the projector on the planar work surface for tracing. The method comprises the steps of creating a pattern, tracing lines along the pattern on the planar work surface, cutting the pattern along the traced lines, discarding pieces of the planar surface outside the pattern, and placing edging along an outer edge of the pattern.

Abstract: A holographic optical element comprising at least two sets of regions, the regions of each set being different from the regions of the other set(s) and being interleaved or overlapping with the regions of the other set(s) and being constructed such that light incident on each set of regions is directed to a respective one of a plurality of viewing zones. The holographic optical element is typically incorporated in a display device such as a stereoscopic display device.

Abstract: The three-dimensional system discloses screens (12, 16) that produce magnified three-dimensional images (6) that can be projected before large audiences who can view said images without special glasses or viewing aids. The screens disclosed therein are active optical systems which, together with the projection optics, serve to reconstruct and present to the audience the same light waves as though the three-dimensional scene actually exists. The present invention discloses improved screens for this system as well as methods of manufacturing said improved screens.

Abstract: The optical system includes a plurality of light modulators, one or more combining filters, and an optical relay system including a filter. Each light modulator modulates a corresponding incident light beam. The one or more combining filters superimpose the modulated light beams from each of the plurality of light modulators. The optical relay system filters the superimposed light and relays the filtered light to an image plane.

Abstract: An illumination system includes an illumination unit having at least one light emitting device which emits a light beam of a predetermined wavelength and at least one holographic optical element which reduces a cross section of the light beam emitted from the light emitting device, and an optical path changer which changes a proceeding path of an incident light passing through the holographic optical element.

Abstract: The invention provides a hologram recording or replicating optical system wherein a misalignment-with-time of the center of a laser generated beam is automatically corrected so that the color balance in a color hologram surface, for instance, can be well maintained with no disturbance. In the hologram recording or replicating optical system for irradiating a photosensitive material 20 with a beam from a laser 31 through a pinhole 10, a beam position correcting mechanism 32 and a beam splitter 33 are located in an optical path between the laser 31 and the pinhole 10, and a laser beam position detector 35 is located at a position in an optical path split by the beam splitter 33 and conjugate to the pinhole 10, so that the beam position correcting mechanism 32 can be operated on the basis of a beam position error signal obtained from the laser beam position detector 35 to keep the position of the beam incident on the pinhole 10 always constant.

Abstract: There is provided a light diffusion sheet comprising a light diffusion layer formed on a transparent substrate and containing a binder resin and resin particles that impart an uneven surface, wherein the uneven surface of the light diffusion layer exhibits an arithmetical mean deviation of 2.0 &mgr;m or more in three-dimensional surface roughness measurement and/or ten point height of irregularities of 10.0 &mgr;m or more in three-dimensional surface roughness measurement. This light diffusion sheet is high luminance in the front direction, is excellent in light-diffusing property, and is resistant to damage.

Abstract: A holographic optical element comprising at least two sets of regions, the regions of each set being different from the regions of the other set(s) and being interleaved or overlapping with the regions of the other set(s) and being constructed such that light incident on each set of regions is directed to a respective one of a plurality of viewing zones. The holographic optical element is typically incorporated in a display device such as a stereoscopic display device.

Abstract: A light reflecting and light diffusing sheet material useful, inter alia, as a back-reflector for liquid crystal displays (LCDs), comprises a sheet of light diffusing material having a light reflecting coating or backing. In a preferred embodiment, the reflective backing comprises a light-reflecting sheet formed separately from the light-diffusing sheet and juxtaposed with a rear surface of the sheet.

Abstract: A wavelength conversion system and method. The inventive system is adapted to receive a beam of input energy having a first spiked portion with a first wavelength and a first spatial and/or temporal intensity profile and a second tail portion with the first wavelength and a second spatial and/or temporal intensity profile. The inventive system includes an electro-optic switch (14) and first polarizer (16) for directing the first portion of the input beam along a first processing path (18) and a second portion thereof along a second processing path (20). A first SHG/OPO arrangement (22, 24) is disposed in the first path (18) for shifting the wavelength of the first portion of the input energy from the first wavelength to a second wavelength. The first arrangement is optimized for the first spatial and/or temporal intensity profile of the first portion of the energy.

Abstract: A system for converting an image into a hologram formed from diffraction gratings includes obtaining image data for each pixel in an image to be converted, putting it into digital form and using the image data to control portions of a laser beam split into a reference beam and at least one object beam. The diffraction gratings are formed by an interference pattern of a reference beam and at least one object beam intersecting on the surface of a photoresist material on a pixel-by-pixel basis. Modulation of at least one object beam and adjustment of the angle at which that beam interferes with the reference beam on the photoresist material is used to reflect image data for each pixel of the image being converted into a hologram consisting of diffraction gratings.

Abstract: A projection screen (30) for representation of images by back-projection comprises a plurality of holographic-optical elements (10) arranged in one plane. The holographic-optical elements are illuminated by a projector (14) comprising three projection devices (22,24,26). Each projection device (22,24,26) generates a light bundle (16,18,20) respectively including the chromatic components of an image to be projected. Each holographic-optical element (10) comprises at least one lens and one diffraction grating which are diffracted in such a manner by the different light bundles (16,18,20) that the holographic-optical element (10) will emit an exiting light bundle (28) with an identical exit angle (&bgr;) in the direction of the viewer (12). Such a projection screen will scatter the light only to a small extent so that the projection screen can be used also at daylight and for large-surface image projection.

Abstract: A laser device which directs one or more wavelengths of pulsed diffuse laser light at a target to produce a diffuse laser illumination, and a method of illuminating and viewing a target with the reflection from one or more wavelengths of diffuse laser light reflected off a target.

Abstract: A method of fabricating a hologram screen having a large visual range and a hologram imaging apparatus used for the particular method of fabricating the hologram screen are disclosed. A plurality of mirrors (3) extended toward a plurality of photosensitive members (5) are arranged at a plurality of end portions (21), respectively, of a light diffuser (2). At least a reference beam (41) and object beams (42) passed through the light diffuser (2) are radiated on a plurality of the photosensitive members (5) individually thereby to form a plurality of holograms. These holograms are integrated with each other by being arranged two-dimensionally thereby to fabricate a hologram screen. Among the mirrors (3), a reference beam-side mirror (31) arranged nearer to the light source of the reference beams (41) is extended from the light diffuser (2) by a length varied with the position of the photosensitive member (5) to be exposed.

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: High storage densities using a holographic system are achievable using a stratified medium while maintaining a relatively high selectivity upon reconstruction of the stored images. Such combination of high density and high selectivity is achievable by employing a stratified medium and a recording process where selectivity does not vary with recording thickness.

Abstract: A holographic projection screen for large screen projection and back projection with a liquid crystal projector. The screen includes at least one layer made of a photosensitive material in which at least one index grating may be recorded by an interference of an optical recording wave with an optical object wave. The thickness of the layer is equal to or greater than n0&Lgr;2/2&pgr;, where n0 is the average index of the photosensitive material, &Lgr; is the average spacing of the index grating and &lgr; is the recording wavelength.

Abstract: A method is proposed, how to produce a holographic screen for projection of the three-dimensional color images, where a narrow and elongate slit-shaped diffuser is recorded on a hologram as an object to ensure the well defined viewing zone forming in the course of the image projection. Further to the back side of the holographic screen a mirror is attached to transform it into reflection mode of operation. Further, the holographic screen is rotated under a control of an eye-tracking system to provide viewing zone movement together with a viewer's eye. Also, a diffuser with vertical light scattering is attached to a surface of the holographic screen to increase a vertical size of a viewing zone of the holographic screen. In addition, two or more holographic screens manufactured by this method are combined in a mosaic manner to form a big size holographic screen.

Abstract: A projection liquid crystal display apparatus has a light source for emitting white light and a liquid crystal display unit, between which a holographic optical element serving as the color separating/focusing means is disposed. Upon receipt of the white light, the holographic optical element performs separation into light components of the primary colors of red, green and blue, at angles corresponding to the arrangement of the pixels on the liquid crystal display unit so as to direct these primary color light components to pixels of the corresponding colors, an whereby image to be reproduced (real image) is formed on the liquid crystal display unit. The holographic optical element is produced by using the liquid crystal display unit as an exposure mask.

Abstract: A diffusive optical element exploiting holography is designed in such a way that, the higher the intensity of incident light in a wavelength range, the lower the rate at which the intensity of diffused light in that wavelength range is reduced with increasing angle relative to the maximum intensity direction. Thus, the lower the intensity of incident light in a wavelength range, the narrower the range of angles at which light is diffused in that wavelength range. This makes it possible to use light diffused at angles within a predetermined range relative to the maximum intensity direction, and thereby enhance light use efficiency in a wavelength range in which light intensity is comparatively low. This diffusive optical element is employed in an illumination optical system, which is used to illuminate photographic film from which to read images.

Abstract: A holographic optical element comprising at least two sets of regions, the regions of each set being different from the regions of the other set(s) and being interleaved or overlapping with the regions of the other set(s) and being constructed such that light incident on each set of regions is directed to a respective one of a plurality of viewing zones. The holographic optical element is typically incorporated in a display device such as a stereoscopic display device.

Abstract: The present invention relates to a method and an apparatus for holographically recording periodic or quasi-periodic features of a mask in a holographic recording layer. In holographic lithography the object beam is directed to the first substrate bearing a holographic recording layer such that it passes the mask substrate and interferes with a reference beam in the recording layer to form a hologram of the mask pattern. According to the new method the object beam is directed to the second substrate at an off-axis angle and the wavelength used and/or the angle of incidence of the object beam are selected according to the period of the features to be recorded such that essentially just the zero and one of the first diffraction orders are present for forming the hologram.

Abstract: A method and a compact apparatus to read shift-multiplexed holograms on a storage medium without the need for any lenses, and without the need for moving the storage medium. The shift-multiplexed holograms have centers at different locations. The apparatus can generate an array of diverging spherical waves of reference beams, each for illuminating one of the holograms. Each hologram is read as an image on a detector array by illuminating that hologram with a corresponding diverging spherical wave of reference beam. Different holograms can be read by illuminating the medium with a different diverging spherical reference beam. The diverging beams can be from an array of sources, or can be from switching one source.

Abstract: A method of producing a holographic screen for projection of the three-dimensional color images is proposed, where a narrow and elongate slit-shaped diffuser is recorded on the hologram as an object to ensure the well-defined viewing zone forming in the course of the image projection. As compared with the previous art the diverging reference beam is used for the screen recording, therefore only small size optical elements are used in the recording setup. When screen is illuminated by the projector, the reconstructed real images of the diffuser are formed behind the screen for each color of the projector light spectrum. A viewing zone, wherefrom a full color image can be seen as projected on the screen, is obtained by making the length of the diffuser big enough to provide overlaps of the various color diffuser images of the projector light, diffracted on the screen.

Abstract: The method and apparatus of the invention pertains to a simultaneously modulated light beam carrying the information of a three-dimensional image is directed to pixels (image points) defining a first light emitting surface, a component of the light beam is emitted from the pixels within a predetermined angle of view (field of view) in the different view directions, with an intensity corresponding to the three-dimensional image, the modulated light beams are directed to the pixels from different entry angles, depending on the emitting angles within the angle of view, wherein the light beams modulated corresponding to the different directions are directed to the pixels of the first light emitting surface from one or more light emitting points of a second light emitting surface, the second light emitting surface being spaced apart with a predetermined distance from the first light emitting surface.

Abstract: A method for producing a hologram recording an interference fringe formed by an object light and a reference light on a photosensitive dry plate, and the object light either having diffusing and scattering characteristics or being passed through an optical diffusion body, mainly includes the following steps: In a first step, a ratio &eegr;RO/&eegr;OO of a first diffraction efficiency &eegr;OO and a second diffraction efficiency &eegr;RO, is calculated. The diffraction efficiency &eegr;OO is dependent on two object light beams. The efficiency &eegr;RO is dependent on the object light and the reference light. In a second step, the intensity EO of the object light and the intensity ER of the reference light is adjusted in such a way that the ratio &eegr;RO/&eegr;OO is set to at least 10 and the efficiency &eegr;OO does not exceed 5%.

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: A holographic stereogram printing apparatus that is able to formulae a holographic stereogram superior in light utilization efficiency and in picture uniformity. The holographic stereogram printing apparatus causes the laser light from a laser light source 31 to fall on a picture display device 41 to illuminate the light transmitted through the display device 41 as object light on a holographic recording medium 30. The holographic stereogram printing apparatus also causes part of the laser light prior to being transmitted through the display device 41 to be illuminated as reference light on the holographic recording medium 30 to form the element holograms sequentially on the holographic recording medium 30. In the holographic stereogram printing apparatus, a light integrator 63 for uniforming the intensity of light incident on the display device 41 is provided on the optical path of the laser light proceeding towards the display device 41.

Abstract: An apparatus for projecting light on to a predetermined area includes a light source and a transparent element disposed adjacent the light source where in the transparent element is made from a sol-gel type glass, quartz, or other optical material. A plurality of surface micro-structures integral in a surface of the transparent element are provided which both homogenize and control directionality of light passing form the light source through the transparent element. These micro-structures produce a predetermined pattern of highly transmissive, smoothly varying, non-discontinuous light in a predetermined direction which is suitable for any number of applications wherein a sol-gel material transparent element including the diffuser surface structures are particularly well suited.

Abstract: A method for producing a hologram recording an interference fringe formed by an object light and a reference light on a photosensitive dry plate, and the object light either having diffusing and scattering characteristics or being passed through an optical diffusion body, mainly includes the following steps: In a first step, a ratio .eta..sub.R0 /.eta..sub.00 of a first diffraction efficiency .eta..sub.00 and a second diffraction efficiency .eta..sub.R0, is calculated. The diffraction efficiency .eta..sub.00 is dependent on two object light beams. The efficiency .eta..sub.R0 is dependent on the object light and the reference light. In a second step, the intensity E.sub.O of the object light and the intensity E.sub.R of the reference light is adjusted in such a way that the ratio .eta..sub.R0 /.eta..sub.00 is set to at least 10 and the efficiency .eta..sub.00 does not exceed 5%.

Abstract: A display device with a holographic diffuser which has at least first and second adjacent sets of holographic regions which overlap each other and wherein the first and second holographic regions diffract and direct light to respective first and second sets of imaging elements of a lcd to displays an image.

Abstract: There is provided a hologram with excellent heat resistance. The hologram comprises a hologram film (10) in which a diffraction grating has been recorded, a substrate (11) situated on one side of the hologram film (10) via a bonding material (13), and a polymer film (12) situated on the other side of the hologram film (10) via a bonding material (13), wherein the thickness of the polymer film (12) is no greater than 100 .mu.m. Otherwise, the polymer film (12) is subjected to prior heat treatment. There is further provided a production process for holograms with minimal appearance defects.

Abstract: A hologram of an increased size using a single color laser, capable of executing a full color regeneration in a desired view angle and a method for producing the hologram. A plurality of photo-sensitive members are independently exposed to obtain respective holograms, which are connected by using an adhesive layer 80 constructing a connecting means, in order to obtain an integrated hologram expanded in two-dimensional direction. The holograms are obtained by an interference of a reference light 22 and an object light passed through a light diffusing body 24 in order to cause the light diffusing body 24 to be recorded on the photo-sensitive member. The size of the light diffusing body 24 is such that the spectral characteristic of the diffused light from the hologram can attain a desired efficiency at least over the entire wavelength range of the visible light.

Abstract: The invention relates to a method for replicating a volume hologram having an image of a scattering object recorded therein according to a hologram replicating technique, wherein the diffraction 13 of unnecessary light due to zero-order light, etc. arising from regular reflection and a visual range capable of viewing a recorded image is limited to a desired range .alpha., so that the image can be displayed more brightly than would be possible with the original hologram plate, and a volume hologram as well. When replicating a volume hologram 4' having an image O' of a scattering body recorded therein, replicating illumination light is incident on the volume hologram 4' at an angle of incidence I.sub.1 at which a group of fringes can be replicated and recorded, said group of fringes being such that, in the vicinity of an apex defined by a supposed slant angle S.sub.g at which a replicated hologram 4' can be viewed at a supposed viewing center angle .phi. within a range .alpha.

Abstract: A method and a compact apparatus to read shift-multiplexed holograms on a storage medium without the need for any lenses, and without the need for moving the storage medium. The shift-multiplexed holograms have centers at different locations. The apparatus can generate an array of diverging spherical waves of reference beams, each for illuminating one of the holograms. Each hologram is read as an image on a detector array by illuminating that hologram with a corresponding diverging spherical wave of reference beam. Different holograms can be read by illuminating the medium with a different diverging spherical reference beam. The diverging beams can be from an array of sources, or can be from switching one source.

Abstract: The present invention is a method for optical data storage which enhances the contrast between ON and OFF pixels. The method comprises writing a two-dimensional image comprising a plurality of pixels into a recording medium with the exposure of individual ON pixels during the recording of the image. The ON pixels are then switched off and OFF pixels are switched on, and the phase of either the object beam or reference beam is changed. The process results in subtraction of residual signal from the OFF pixels.

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 photolithograhic method and apparatus for exposure of a spherical shaped semiconductor substrate according to a mask pattern of a primary spherical object mask in the manufacture of a spherical semiconductor device is disclosed. A secondary mask is provided, the secondary mask having stored therein a hologram recorded from the primary spherical object mask and containing spherical mask pattern information. The spherical shaped semiconductor substrate is then positioned with respect to the secondary mask in preparation for a photolithographic exposure. Lastly, a reference beam is directed upon the secondary mask for enabling inverse scattering of the hologram to produce an inverse scattered holographic image photolithographic exposure of the spherical shaped semiconductor substrate.