Abstract: Diffraction patterns of a sample at various tilt angles are acquired by irradiating a region of interest using a first charged particle beam. Sample images are acquired by irradiating the region of interest using a second charged particle beam. The first and second charged particle beams are formed by splitting charged particles generated by a charged particle source.

Abstract: A light source module includes a light source, first and second lens elements, a reflector, and a first diffuser. The light source emits a beam focused by the first lens element on a first focal point. The reflector is disposed on a beam transmission path. The first lens element is between the light source and the reflector. The first diffuser is between the first lens element and the reflector and includes a first diffusion plate and a first drive mechanism. The first diffusion plate is at/near the first focal point. The beam is transmitted to the reflector by the first diffusion plate. The first drive mechanism is between the first diffusion plate and the first lens element, and moves/rotates the first diffusion plate. The second lens element has a second focal point, coinciding with the first focal point, at a light-incident side. The reflector is at the light-incident side.

Abstract: A microfabrication method is provided with which it is possible to easily form a fine periodic structure on a surface of any substrate. A glass precursor is applied to a substrate, and the glass precursor is irradiated with short-pulse laser light. By the irradiation with short-pulse laser light, the glass precursor is activated to undergo a thermal reaction, and a fine periodic structure can be easily formed on the surface. Furthermore, by oxidizing the substrate on which the fine periodic structure has been formed, the hue of the surface can be improved while maintaining the fine periodic structure.

Abstract: Optically transparent glass ceramic materials comprising a glass phase containing and a crystalline tungsten bronze phase comprising nanoparticles and having the formula MxWO3, where M includes at least one H, Li, Na, K, Rb, Cs, Ca, Sr, Ba, Zn, Cu, Ag, Sn, Cd, In, Tl, Pb, Bi, Th, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, and U, and where 0<x<1. Aluminosilicate and zinc-bismuth-borate glasses comprising at least one of Sm2O3, Pr2O3, and Er2O3 are also provided.

Abstract: A system for making a holographic medium includes a light source configured to provide light and a beam splitter configured to separate the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light. The system also includes a first set of optical elements configured to transmit the first portion of the light for providing a first wide-field beam onto an optically recordable medium, a second set of optical elements configured to transmit the second portion of the light through for providing a second wide-field beam, and a plurality of lenses optically coupled with the second set of optical elements configured to receive the second wide-field beam and project a plurality of separate light patterns onto the optically recordable medium for forming the holographic medium.

Abstract: Methods, apparatus, devices, and systems for three-dimensional (3D) displaying objects are provided. In one aspect, a method includes obtaining data including respective primitive data for primitives corresponding to an object, determining an electromagnetic (EM) field contribution to each element of a display for each of the primitives by calculating an EM field propagation from the primitive to the element, generating a sum of the EM field contributions from the primitives for each of the elements, transmitting to each of the elements a respective control signal for modulating at least one property of the element based on the sum of the EM field contributions, and transmitting a timing control signal to an illuminator to activate the illuminator to illuminate light on the display, such that the light is caused by the modulated elements of the display to form a volumetric light field corresponding to the object.

Abstract: A metrology apparatus includes first (21) and second (22) radiation sources which generate first (iB1) and second (iB2) illumination beams of different spatial extent and/or angular range. One of the illumination beams is selected, e.g. according to the size of target to be measured. The beam selection can be made by a tillable mirror (254) at a back-projected substrate plane in a Kohler illumination setup.

Abstract: An optical information recording apparatus and method thereof for recording information in a holographic medium. The apparatus includes a laser source which generates a reference beam and a signal beam to record the information in the holographic medium, a sensor which detects a vibrational amplitude over a time period applied to the optical information processing apparatus for recording the information, an operational circuit which calculates from the vibrational amplitude at least one statistical measure of the vibrational amplitude; and a processor programmed to control a recording mode such that the processor evaluates the calculated statistical measure to determine continuation of a recording operation to the holographic medium.

Abstract: A holographic 3D recording device includes: a photorefractive crystal and a microlens array. The microlens array includes an array face and a side face. The microlens array is provided in a light path from an object to be photographed to the photorefractive crystal such that first light of object emitted through a diffuse reflection of the object to be photographed passes through the array face of the microlens array and becomes second light of object that is emitted to the photorefractive crystal. The photorefractive crystal is configured to receive the second light of object emitted by the microlens array and reference light, respectively, and save therein an interference fringe formed by the reference light and the second light of object. The first light of object and the reference light are coherent light.

Abstract: A surface relief structure includes a recording medium configured to be structurally modified when exposed to interfering and non-interfering portions of radiation beams, the structurally modified recording medium including, when viewed in a two-dimensional cross-section along one of the axes of the recording medium a plurality of equally spaced steps of fine-sized periodicity superimposed upon a plurality of deep depressions of substantially coarse-sized periodicity. The structurally modified recording medium is configured to produce in reflection single and multiple colors in a broad spectral range when illuminated by a source of light.

Abstract: A holographic reconstruction of scenes includes a light modulator, an imaging system with at least two imaging means and an illumination device with sufficient coherent light for illumination of hologram coded in the light modulator. The at least two imaging means are arranged such that a first imaging means is provided for the magnified imaging of the light modulator on a second imaging means. The second imaging means is provided for imaging of a plane of a spatial frequency spectrum of the light modulator in a viewing plane at least one viewing window. The viewing window corresponds to a diffraction order of the spatial frequency spectrum.

Abstract: A mobile terminal and controlling method thereof are disclosed, by which a holography user interface is provided. The present invention includes a controller, a holography storing medium configured to record an interference pattern generated by interference of light, and a holography output module, if at least one event among a plurality of trigger events occurs, outputting a holography image attributed to diffraction between the light applied to the holography storing medium and the interference pattern under the control of the controller, wherein the controller controls the holography image to be outputted in accordance with at least one holography pattern set previously.

Abstract: A surface relief structure includes a recording medium configured to be structurally modified when exposed to interfering and non-interfering portions of radiation beams, the structurally modified recording medium including, when viewed in a two-dimensional cross-section along one of the axes of the recording medium a plurality of equally spaced steps of fine-sized periodicity superimposed upon a plurality of deep depressions of substantially coarse-sized periodicity. The structurally modified recording medium is configured to produce in reflection single and multiple colors in a broad spectral range when illuminated by a source of light.

Abstract: Disclosed are injection moldings, an injection-molding apparatus and a method thereof. The injection-molding apparatus comprises: a cavity mold having a cavity; a core mold having a core surface to form a molding space for injection moldings when being joined to the cavity mold; a heating unit for heating the cavity mold or the core mold; a cooling unit for cooling the cavity mold or the core mold; and a patterning stamp having a micrometer or nanometer sized pattern and provided on an inner surface of the molding space. According to the injection-molding apparatus, a micrometer or nanometer sized pattern is formed on a surface of injection moldings so as to have a super-hydrophobic characteristic and an optical characteristic, and a micrometer or nanometer sized pattern of a complex structure can be implemented.

Abstract: An apparatus includes a recording light source configured to emit recording beams, an EASLM configured to time sequentially modulate the recording beams emitted from the recording light source according to hologram information corresponding to a 3-dimensional image spatially divided into a plurality of portions, an OASLM configured to include a plurality of regions corresponding to the plurality of the divided portions of the 3-dimensional image and images on a region corresponding to the portions using the modulated recording beams to form a hologram, a scanning optical unit configured to reproduce the hologram formed by the recording beams serially modulated by the EASLM on a reduced scale and transmit the hologram to the regions of the OASLM corresponding to the portions, and a reproducing light source configured to produce a surface light and emit the surface light to the OASLM.

Abstract: An image reading device includes: a conveying unit for conveying an irradiated member that has a hologram area in a conveying direction; a first light source for applying light to an irradiated part in the hologram area; and a second light source separated from the first light source along the conveying direction and applying light to an irradiated part in the hologram area when the hologram area is conveyed by a prescribed distance. An irradiation angle at which the irradiated part is irradiated with the light of the first light source is made to be different from an irradiation angle at which the irradiated part is irradiated with the light of the second light source when the hologram part is conveyed by the prescribed distance. Lights reflected by the hologram area are respectively received to detect an electric signal of the hologram area of the irradiated member.

Abstract: A display apparatus configured to produce an interactive three-dimensional holographic image is disclosed. The display apparatus can include one or more coherent light sources configured to produce one or more beams, based on obtained image data of an object to display, and a lens assembly configured to direct the one or more beams to form a holographic image of the object. The lens assembly can include a collimating lens and a lens capable of beam steering one or more beams, including a micro-lens assembly with at least one micro-lens configured to generate a plurality of beams associated with a plurality of desired viewing angles. One or more optical sensors can be configured to obtain information regarding whether an interactive device interrupts the one or more beams, and a processor unit can determine a location of the interactive device with respect to the holographic image.

Abstract: A system for generating periodic or quasi-periodic patterns on a sample by means of an interference lithography technique includes a photon source, a mask and a sample holder. The mask has a grating for generating a predetermined pattern, wherein the mask is positioned at a first distance from the photon source. The sample holder is disposed at a second distance from the mask on a side facing away from the photon source. The second distance is selected to be where an intensity distribution is substantially stationary and distance-invariant, or the second distance is varied to obtain a desired average intensity distribution on the sample surface.

Abstract: An image reading device having a conveying unit for conveying an irradiated member that has a hologram area in a conveying direction; a first light source for applying light to an irradiated part in the hologram area; and a second light source separated from the first light source along the conveying direction and applying light to an irradiated part in the hologram area when the hologram area is conveyed by a prescribed distance. An irradiation angle at which the irradiated part is irradiated with the light of the first light source is made to be different from an irradiation angle at which the irradiated part is irradiated with the light of the second light source when the hologram part is conveyed by the prescribed distance. Lights reflected by the hologram area are respectively received to detect an electric signal of the hologram area of the irradiated member.

Abstract: A system for recording multiple volume Bragg gratings (VBGs) in a photo thermo-refractive material is configured to implement a method which provides for irradiating the material by a coherent light through a phase mask. The system has a plurality of actuators operative to displace the light source, phase mask and material relative to one another so as to mass produce multiple units of the material each having one or more uniformly configured VBGs.

Abstract: Various embodiments of the present invention are directed to negative refractive index-based holograms that can be electronically controlled and dynamically reconfigured to generate one or more color three-dimensional holographic images. In one aspect, a hologram comprises a phase-control layer having a plurality of phase modulation elements. The phase-modulation elements are configured with a negative effective refractive index and selectively transmit wavelengths associated with one of three primary color wavelength. The hologram also includes an intensity-control layer including a plurality of intensity-control elements. One or more color three-dimensional images can be produced by electronically addressing the phase-modulation elements and intensity-control elements in order to phase shift and control the intensity of light transmitted through the hologram. A method for generating a color holographic image using the hologram is also provided, as is a system for generating a color holographic image.

Abstract: An exposing device including a light emitting element array of light emitting elements arrayed in a row along a predetermined first direction; a hologram recording layer in which hologram elements are multiplex recorded such that each of the hologram elements corresponds to one of the light emitting elements and diffracts an emission beam from the light emitting element and converges the light onto a light exposure plane, such that focused beam spots are formed on the light exposure plane in a row along the first direction; and a first transmission control section, disposed at the light incident side of the hologram recording layer, provided with a structure in which light blocking sections and light transmitting sections are alternately arrayed along a second direction intersecting with the first direction, and selectively transmitting in the second direction light passing along the optical path of the reference beam.

Abstract: In one implementation, a system includes a multi-core processor and an optical display with a plurality of hogels. Each hogel is configured to radiate light in a plurality of directions, with controllable intensities in each of the plurality of directions. The multi-core processor is coupled to the optical display and configured to control the hogels. The multi-core processor includes at least two cores, an on-chip memory, and a master processor in a single integrated circuit package. The master processor may be a general-purpose on-chip processor, such as a core in the multi-core processor, that is used to coordinated operations of the other cores. Each of the cores is configured to receive hogel data and to generate signals for a corresponding subset of the plurality of hogels.

Abstract: Methods create images viewable under different selected angles on optical storage devices and other photosensitive surfaces and optical storage devices with super-imposed images. Generally, a photosensitive surface is exposed with multiple diffraction patterns creating super-imposed images. These diffraction patterns create super-imposed images on the photosensitive surfaces, which can be read by either a human or a computer.

Abstract: Exemplary embodiments provide methods for patterning large areas, beyond those accessible with the limited single-area exposure techniques, with nanometer scale features. The methods can include forming a grating pattern to make a first interferometric exposure of a first portion of a photosensitive material disposed over a substrate by interfering two or more laser beams, wherein the two or more laser beams comprise an apodized intensity profile having a continuous intensity variation. The method can further include aligning and overlapping the grating pattern to expose a second portion of the photosensitive material such that the first portion and the second portion form a continuous grating pattern.

Abstract: A method and apparatus for reducing speckle noise in an image of an object are disclosed. The method includes, placing the object in an interferometer at a first position along a beam path of an object beam, irradiating the object with the object beam, moving the object from the first position to a second position by longitudinally shifting the object along the beam path of the object beam, irradiating the object with the object beam at the second position. At each of the first and second positions a holographic image formed by interference between the object beam and a reference beam is recorded. An object image with reduced speckle noise is obtained by averaging the holographic images. Either an arithmetic mean or a weighted average may be used in the averaging of the holographic images.

Abstract: Pre-sensitization techniques can be used in conjunction with holographic recording materials to allow high quality holographic stereograms to be recorded in those holographic recording materials using pulsed lasers. Various hologram production system hardware and software designs for use with pulsed lasers can be used with the pre-sensitization techniques.

Abstract: An exposure apparatus includes a substrate in which plural light-emitting devices are arrayed one-dimensionally or two-dimensionally; and a hologram recording layer that is disposed on the substrate, plural holograms being recorded in the hologram recording layer by holographic interference between a first beam and a second beam such that a predetermined number of beam spots are disposed in the hologram recording layer in a predetermined array direction according to a portion of light-emitting devices, the portion of light-emitting devices being selected as emitters from the plural light-emitting devices, the beam spot being formed by a light beam of the second beam, the first beam passing through an optical path of diffusion light that passes through the emitter, the second beam passing through an optical path of convergent light that converges at a predetermined distance outside the optical path of the first beam.

Abstract: A holographic imaging device for imaging an object under study includes a partially reflective surface having a contact side for contacting the object under study and an imaging side for partially reflecting a radiation wave. The device also includes at least one radiation source for projecting the radiation wave onto the imaging side of the partially reflective surface and an image sensor arranged to receive the radiation wave when reflected by the partially reflective surface. The image sensor is adapted for determining an interference pattern between the radiation wave reflected by the imaging side of the partially reflective surface and the radiation wave reflected by the object under study when contacting the contact side of the partially reflective surface.

Abstract: An apparatus and method to produce a hologram of an object includes an electromagnetic radiation assembly configured to receive a received electromagnetic radiation, such as light, from the object. The electromagnetic radiation assembly is further configured to diffract the received electromagnetic radiation and transmit a diffracted electromagnetic radiation. An image capture assembly is configured to capture an image of the diffracted electromagnetic radiation and produce the hologram of the object from the captured image.

Abstract: The present invention relates to a reference beam coupler for an apparatus for reading from and/or writing to holographic storage media, to a multiplexing scheme using the reference beam coupler, and to an apparatus for reading from and/or writing to holographic storage media using such reference beam coupler or multiplexing scheme. According to the invention, the reference beam coupler has: a substrate; one or more optical fibers passing through the substrate for coupling one or more reference beams; and a reflective area on the substrate for reflecting an object beam, which serves as a Fourier filter for the object beam.

Abstract: We describe techniques for recording a holographic image onto holographic recording film, in particular for security holograms. We thus describe a structure having a stack comprising the holographic recording film and a multichannel image generation device under the film. A three-dimensional object (or hologram of a 3D object) is provided, located under the multichannel image generation device. At least a portion of the multichannel image generation device is substantially transparent or absent in a region above the object. A holographic image is recorded in the film by illuminating the stack with laser light. The multichannel image generation device under the film may comprise a volume reflection hologram of a lenticularly generated image. The structure records a hologram of the 3D object in conjunction with a multi-channel holographic image.

Abstract: This invention relates to holographic image display systems, and to related methods and processor control code. We describe a method of displaying an image holographically, the method including: inputting display image data defining said image for display; processing said image data to determine first image data representing a first spatial frequency portion of said image data and second image data representing a second spatial frequency portion of said image data, wherein said second spatial frequency is higher than said first spatial frequency; displaying a hologram of said first image data on a spatial light modulator (SLM) to form a holographically-generated intermediate real image; modulating said intermediate real image using said second image data to display said image.

Abstract: A light irradiation device includes: a focus servo control unit including a light source, a spatial light modulating unit, and a light irradiating unit, for focus servo control so that the ideal focal position of light via an objective lens is such that distance between an ideal focal position and a hologram recording medium surface is smaller than distance from the surface to the lower layer side face of the recording layer, and the focal position of light via the objective lens is constant at the ideal focal position; an objective-lens/relay-lens distance adjusting unit to adjust distance between the objective lens and a relay lens close to the objective lens; a light reception unit to receive marker light; and a constant distance control unit to control the objective-lens/relay-lens distance adjusting unit based on error between the ideal position of the marker light, and the actual position of the marker light.

Abstract: A holographic imaging system includes an electrical addressable spatial light modulator (EASLM) and an optically addressable spatial light modulator (OASLM). A read light is configured to illuminate the OASLM, and a controller is configured to address the EASLM with both positive and negative sub-images and transmit the positive and negative sub-images to the OASLM. The controller is further configured to address the OASLM with an operating voltage, wherein the read light generates a holographic image comprised of diffraction patterns from the positive and negative sub-images.

Abstract: An Apparatus and method to produce a hologram of a cross-section of an object includes an electromagnetic radiation assembly configured to receive a received electromagnetic radiation, such as light, from the object. The electromagnetic radiation assembly is further configured to diffract the received electromagnetic radiation and transmit a diffracted electromagnetic radiation An image capture assembly is configure to capture an image of the diffracted electromagnetic radiation and produce the hologram of the cross-section of the object from the captured image. The hologram of the cross-section includes information regarding a single cross-section of the object.

Abstract: Method for real-time rendering and generating of computer-generated video holograms from three-dimensional image data with depth information, where the position and viewing direction of an observer defines a view of the scene, and where the observer is assigned with at least one virtual observer window, which is situated in an observer plane near the observer eyes, comprising the following process steps: 3D rendering and generation of the depth map of scene section data between two parallel section planes, which are disposed at right angles to the viewing direction of the observer, transformation of the scene section data, repetition of the steps of 3D rendering and transformation, Back-transformation, encoding in pixel values in order to reconstruct the three-dimensional scene.

Abstract: The invention relates to a method and a playback device for a two- and/or three-dimensional illustration, having at least one light source, at least one light modulation device, a display screen, and a tracking system for tracking a virtual viewer window of a viewer plane, in which at least one viewer is located. This tracking system has a position detection system for determining the eye positions of the at least one viewer in the viewer plane, a tracking device, and a control device for activating and controlling the tracking device, and is disposed between the light modulation device and the display screen. In order to track the viewer window along an optical axis of the playback device, a focal width on the image side of an optical system of the tracking device is constant.

Abstract: A multi-color off-axis digital holographic system and the imaging method thereof are disclosed. The multi-color off-axis digital holographic system comprises: a plurality of light emitting diodes, for provide a red (R) beam, a green (G) beam and a blue (B) beam; an interference object lens module, for receiving the R, G, and B beams to generate a beam containing an interference signal; a color imaging device, for receiving the beam containing the interference signal and thus forming a hologram on a surface of the color imaging device by holographic interference while registering the hologram; and a processing device, for receiving the registered hologram form the color imaging device; wherein the processing device perform a zero-filling and reconstructing operations upon the received hologram to obtain phase information of the R, G and B beams.

Abstract: A system and method that synchronizes a spatial light modulator (SLM) with a pulsed laser to record a hologram at the repetition rate of the pulsed laser for applications including holographic displays and data storage. The color channel capability of a SLM is utilized to effectively increase the write throughput when the pulsed laser repetition rate LR exceeds the SLM's image refresh rate R. The hogels are encoded on the color channels and concatenated to form a sequence of color images such that the write throughput is equal to the repetition rate LR up to a maximum of N*R. This effectively extends the capability and continued viability of existing inexpensive SLMs.

Abstract: A video holographic display device includes a light source used to illuminate a hologram-bearing medium encoded with a hologram. The device operates so that only when an observer's eyes are positioned approximately at the image plane of the light source can the holographic reconstruction be seen properly. This contrasts with conventional holographic displays, in which the observer's eyes do not have to be at the image plane in order for a holographic reconstruction to be seen.

Abstract: An apparatus comprising: a processor for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state, wherein the one or more tunable parameters include the following parameters: the laser current and the wavelength of the output light. The apparatus may include a laser and/or a holographic storage medium. Also provided is a method for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state.

Abstract: A holographic projection system has an optical wave tracking system which adjusts the propagation direction of a modulated wavefront. It provides an adjustable wave tracking system which aligns the modulated wave with a desired eye position of one or more observers and follows the movements of the observer. The system comprises spatial light modulation means which modulate a wave with holographic information for the purpose of holographic reconstruction. The optical wave tracking provides the light path of the modulated wave with a desired propagation direction which guides the modulated wave out of the reconstruction system via a light exit position of a display screen. Position control means set adjustable tracking mirror means in terms of their inclination to a reflection direction for reflecting the modulated wave and deflection means, which are located in the set reflection direction, reflect the wave via the display screen into the desired propagation direction.

Abstract: Recording an image of a holographic stereogram includes providing an optical deflecting device in proximity to a hologram recording medium that is exposed with a stripe-shaped elemental hologram. Either an object beam or a reference beam is deflected, in a long side direction thereof, through the optical deflecting device to expose the hologram recording medium. The hologram recording medium is multiply exposed, at least twice, with different deflection angles of the optical deflecting device to cause the stripe-shaped elemental hologram to have a plurality of parallaxes in a long side direction of the stripe-shaped elemental hologram.

Abstract: Methods create images viewable under different selected angles on optical storage devices and other photosensitive surfaces and optical storage devices with super-imposed images. Generally, a photosensitive surface is exposed with multiple diffraction patterns creating super-imposed images. These diffraction patterns create super-imposed images on the photosensitive surfaces, which can be read by either a human or a computer.

Abstract: According to one aspect and example, a holographic recording system includes a light source, an object for modulating an object beam from the light source, and a relay system adapted to magnify (positive or negative) the modulated beam (e.g., an image of the object) to an output image. The object may include an SLM operable to modulate the object beam with an information layer comprising a plurality of data pages. The output image is directed to the holographic storage medium, where a reference beam is also directed, to record the resulting interference pattern. Additionally, the relay system converges the output image to an output Fourier plane, which may be disposed within the holographic storage medium. A filter may be placed at an intermediate Fourier plane located prior to the output Fourier plane, and a phase mask may be placed at the position of the output image.

Abstract: A system and method for producing a Bragg grating. A system and a method for apodization of gratings. The system and method for producing a grating include splitting a beam and reflecting one split beam an odd number of times and the other an even number of times before the two are allowed to interfere within a photosensitive target. When the original beam is scanned in predetermined directions, the split beams scan the target while interfering within the target. The original beam is scanned such that an intersection point of the reflected split beams moves along a bisector of the two split beams. In the system and method for apodizing, scanning of the interfering beams along a length of the target may be controlled to yield a substantially uniform average refractive index for the apodized grating that is being recorded in the photosensitive target medium.

Abstract: A hologram medium manufacturing method that includes disposing a first pair of master hologram media with a predetermined interval so that the first pair of the master hologram media face each other; forming a master hologram in the master hologram media by irradiating the first pair of the master hologram media with spherical wave light and reference light so that the spherical wave light and the reference light interfere with each other in the master hologram media. The spherical wave light and the reference light have a focal point between the first pair of the master hologram media. The method also includes disposing a hologram medium between the first pair of the master hologram media; and forming a hologram in the hologram medium by irradiating the first pair of the master hologram media with the reference light.

Abstract: A hologram recording apparatus where holograms corresponding to incident angles of reference light are multiple-recorded onto a medium, including a recording light projection unit projecting the recording light onto a region of the medium; a reference light projection unit projecting the reference light onto the medium by intermittently changing an incident angle; an incident-angle variation projection unit changing the incident angle of the reference light; an incident-angle switching instruction unit giving an instruction for switching the incident angle; a feed-back control unit operating the incident-angle variation projection unit by feed-back control when the switching instruction of the incident angle has been given; and a feed-forward compensation unit learning a feed-back control signal which is outputted every switching instruction of the incident angle from the feed-back control unit, wherein a feed-forward compensation is made as to a next feed-back control signal on the basis of a result of the l

Abstract: The invention provides a hologram in which a visually unidentifiable microtext or other micropattern of the order of 10 ?m is recorded, and a process for the fabrication of the same. A volume hologram recording material 2 is located on the side of a reflection type volume hologram master 1 onto which copying illumination light 11 is incident, and the copying illumination light 11 incident onto the recording material 2 and light 12 diffracted through the master 1 interfere together in the volume hologram recording material 2 thereby copying the reflection type volume hologram master.