Abstract: A means, method and apparatus for producing a parallel addressable set of images by modulating a set of input beams with addressing information, and projecting the energy from a three-dimensional array of first pixel locations which decode in parallel to produce an interference image at the location of a second three-dimensional array of pixel locations, energizing at least one of the second pixels. Each image corresponds with an input address. A subset of addresses, projection surface configurations, and images exhibit useful synergistic relationships. These are used to address a ROM, RAM, or content addressable memory, provide a visual display of selected images, iterate in a series to produce four dimensional computing, integrate information from multiple energy forms, and accomplish signal processing and channel switching.

Abstract: An illumination system includes a polarization selective holographic element, which includes at least one optically anisotropic material, arranged to separate light of a first polarization type from light of a second polarization type, and converting section for converting light of at least one of the first and second polarization types to light of a common polarization type. Where the polarization selective holographic element separates two orthogonal components of plane polarized light from one another, the converting section can include a polarization rotator, for example a half wave plate, or alternatively a quarter wave plate and a reflector arranged to reflect light back through the quarter wave plate. Where the polarization selective holographic element separates opposite handed components of circularly polarized light, the converting section can include a reflector.

Abstract: A hologram display item comprising a hologram member having a front surface with a holographic image thereon and a rear surface. A light source assembly is also provided and is structurally connected to, and fixed relative to, the hologram, at a position to impinge light energy onto the holographic image. In this arrangement, the light source is fixed relative to the holographic image so as to provide, at all times, optimum viewing of the hologram by the observer independent of the position of the hologram display item relative to the position of the observer. The light source, fixed to the hologram display item, emits light energy substantially from a point within the light source at a predetermined angle advantageous for replay or viewing, the angle usually being similar to the known or discoverable angle of original hologram construction.

Abstract: Detachable hologram assembly for a compact holographic sight includes a hologram of a reticle image or other desired alignment indicia mounted within a resilient, detachable frame. The frame includes a pair of generally planar, non-parallel registration surfaces and an aperture extending through the frame at the junction of the registration surfaces. A hologram mount, also including a pair of registration surfaces which are complimentary to those of the frame is affixed to, or integral with, the sight. A fastener secures the hologram assembly to the mount with a force sufficient to maintain the registration surfaces of the frame in frictional fit, respectively, with the corresponding registration surfaces of the mount.

Abstract: The twin-image elimination apparatus of the present invention comprises (a) a scanning light source for emitting a scanning light beam; (b) an interference device which converts the scanning light beam from the scanning light source into a spherical wave and a plane wave having temporal frequencies different from each other and combines the spherical and plane waves together; (c) a scanner for scanning an object with the combined light beam from the interference device; (d) a photodetector for detecting a scattered wave from the object; (e) a first multiplier which converts an output signal of the photodetector into a cosine-coded holographic information; (f) a second multiplier which converts the output signal of the photodetector into a sine-coded holographic information; and (g) a holographic reconstruction device which converts output signals of the first and second multipliers into a sum signal, in which these output signals are added together with a phase difference of .pi./2+2n.pi.

Abstract: A hologram duplicating method and apparatus whereby a photosensitive material film is continuously and smoothly brought into close contact with the surface of a hologram original plate, and the film is effectively delaminated after a duplicating process. The apparatus includes a film supply part (31) for supplying a photosensitive material film (1), a film laminating part for successively laminating the supplied film (1) on a hologram original plate (35) with the film (1) being squeezed with a roller (46) from the upper side, a film delaminating part for successively delaminating the film (1) from the original plate (35) from one end thereof with the film (1) being pressed with the roller (46), and a film take-up part (43) for taking up the delaminated film. The film (1) can be laminated on the original plate (35) without trapping air bubbles, and the film (1) can be delaminated from the original plate (35) without causing peel unevenness such as undesired lines.

Abstract: This specification discloses a displaying apparatus having a display emitting light, and an optical element formed by two holograms each having optical power and partially overlapping each other. The light from the display is diffracted by one of the holograms to be directed to an observer's left pupil, and is diffracted by the other hologram to be directed to the observer's right pupil.

Abstract: The invention relates to an illumination device for illuminating a display device. In a preferred embodiment, non-polarized light from a non-polarized light source is polarized by a holographic polarization beam splitting device and focused onto a liquid crystal display device by a holographic focusing device. The invention is operable with monochrome and color display devices, and allows for a high light yield independent of the useful surface area of each detector element of the display device.

Abstract: The sight comprises a support adapted for mounting onto an instrument to be aimed at a target, an optical device mounted onto the support for creating an image including a first sighting mark at a first finite distance with respect to the optical device, and a device mounted on to the support for providing a second sighting mark at a finite distance with respect to the first sighting mark. The instrument is aimed at the target by aligning the sighting marks. Since at least the first sighting mark is an image, its position can be chosen to improve the accuracy of aiming by alignment of the marks without having to physically accommodate the first mark.

Abstract: The present invention provides a manufacturing process (600) and method (500) for efficiently providing a multi-holographic optical element substrate unit. Upon preparation of an original continuous/non-continuous holographic optical element with uniform diffraction efficiency and marking the original continuous/non-continuous holographic optical element with predetermined alignment marks, the original continuous/non-continuous holographic optical element is cut into a predetermined number of individual holographic optical elements in accordance with the predetermined alignment marks. Then a substrate is prepared with alignment marks in accordance with the predetermined alignment marks of the individual holographic optical elements, and the individual holographic optical elements are attached to a substrate in accordance with the alignment marks.

Abstract: A holographic apparatus for continually sensing, transmitting and reconstructing a three-dimensional image including a device for receiving a holographic interference pattern such as a video camera, a device for creating a holographic interference pattern on the receiving device, a device for focusing the interference pattern on the input of the receiving device, a device for transmitting the received holographic interference pattern including a device such as a computer, a device for converting the transmitted holographic interference pattern to a holographic interference pattern which is representative of the three-dimensional image such as an LCD and a source of coherent light illuminating the holographic interference pattern on the converting means to reconstruct the three-dimensional image.

Abstract: A three-dimensional photo mask is formed from a substrate having a first side and a three-dimensional side. A hologram is provided on the first side of the substrate. The three-dimensional side of the substrate has a photosensitive resist material provided thereon. The hologram includes information that defines features to be imaged onto the photosensitive resist material. A method and a system are disclosed for producing the three-dimensional mask.

Abstract: A composite hologram incorporates a plurality of hologram tiles arranged for display, each of the hologram tiles formed by exposing each of a plurality of different unexposed photographic plates simultaneously to light scattered by an intermediate hologram using a conjugate complex of a first reference wave from a coherent light source and to a second reference wave from the coherent light source.

Abstract: A laminated multilayer film substrate for use in the production of banknotes. The film substrate includes a first layer comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.95, the first layer oriented in at least a first direction to a degree which is at least three times greater than the degree of orientation present in a direction substantially normal to the first direction, and a second layer comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.95, the second layer oriented in at least a first direction to a degree which is at least three times greater than the degree of orientation present in a direction substantially normal to the first direction, wherein the second layer is laminated to the film substrate so that the first direction of orientation of the second layer is substantially normal to the first direction of orientation of the first layer.

Abstract: A method and system for recording and displaying grazing-incidence (i.e., steep reference beam angle) holograms supported on a substrate having thin edge-illuminatable geometry. The system and process of the present invention uses thin edge-illuminated substrates that facilitate optimal coupling of the reference light beam at steep angles approaching grazing incidence. Different recording techniques are employed when the index of refraction of the substrate is greater than that of the recording medium, than when the index of refraction of the substrate is less than that of the recording medium.

Abstract: A substrate bears holographic imagery, selected portions of which are covered by non-holographic imagery printed in predetermined geometric registry with the holographic images. Multiple replicas of this interactive graphic work are mass-produced by embossing an array of the holographic imagery into a substrate in roll form, together with eyemarks located periodically along the roll. Using these eyemarks, the roll is optically sheeted and the non-holographic imagery then printed on the holographic substrate.

Abstract: A holographic viewing apparatus for allowing an operator of a bus to view a portion of a blind spot region located in front of the bus and below the windshield of the bus. The holographic viewing apparatus includes a volume transmission holographic grating attached to a lower edge of the windshield of the bus for transmissively diffracting light from a portion of the blind spot region such that an operator of the bus sees an image of the portion of the blind spot region superimposed on a scene that is directly and non-diffractingly observed through the holographic transmission grating.

Abstract: A tight packed array of amplitude controlled in-phase light emitters produces dynamic real holographic images. A partially reflecting mirror is applied to a planar array of amplitude controlled laser diode emitters which are stimulated by each other. The emitters are forced into phase with each other by partially reflecting light energy from adjacent row and column elements onto each other. Incident energy stimulates the element receiving the energy to fire in phase with the incident energy. The array may be forced in phase by directly illumination from a master laser. A single laser is used to illuminate a flat surface containing an array of transmissive apertures which act as emitters. Amplitudes are controlled by liquid crystals. Light from the emitters forms an image which changes according to amplitudes of the individual emitters. Optical focal plane reducers reduce the effective inter element spacing.

Abstract: A holographic ornament comprises a hologram which has an operative surface. In one embodiment, the operative surface is masked by a masking member. The masking member is formed with at least one letter-shaped cut through which a part of the operative surface of the hologram is exposed. In order to protect the masking member and the exposed part of the operative surface, a transparent protection cover member covers them. In the other embodiment, the hologram per se is formed with at least one through cut which is shaped like a letter or the like. In order to protect the operative surface, a transparent protection cover member covers the same.

Abstract: A hologram forming layer, transparent evaporated layer, colored layer, adhesion anchor layer, and adhesive layer are sequentially laminated on the under surface of a base member. The laminated body is used as a seal by the presence of the adhesive layer. It is preferable for the base member to have adequate rigidity (flexibility, tensile strength) and surface flatness. The hologram forming layer has a relief type hologram image. The transparent evaporated layer is a multi-layered ceramic layer constructed by alternately laminating high-refractive index layers and low-refractive index layers and the thickness thereof is preferably set to 1 .mu.m or less. In the transparent evaporated layer, the color of visible light in predetermined wavelength range is changed according to the viewing angle when it is transmitted therethrough or reflected therefrom.

Abstract: A photosensitive recording material comprising a solvent-soluble, thermosetting epoxy oligomer capable of cationic polymerization, an aliphatic monomer having at least one ethylenically unsaturated bond, the monomer being liquid at normal temperature and pressure, having a boiling point of 100.degree. C. or above at normal pressure and being capable of radical polymerization, a photoinitiator selected from the group consisting of i) a first photoinitiator capable of simultaneously generating a radical species that activates radical polymerization and a Br.o slashed.nsted acid or Lewis acid that activates cationic polymerization, upon exposure to actinic radiation, and ii) a second photoinitiator comprised of a radical polymerization photoinitiator capable of generating a radical species that activates radical polymerization upon exposure to actinic radiation and a cationic polymerization photoinitiator capable of generating a Br.o slashed.

Abstract: A new personal laser dosimetry badge records intentional or unintentional exposure to laser radiation. A Fresnel biprism is mounted over a layer of photopolymerizable material, preferably a polymer-dispersed liquid crystal material. A laser beam striking the apex of the biprism splits into two beams crossing at an angle which depends on the prism apex angle and the angle of incidence. These crossed beams form an interference pattern at the photopolymer with bright and dark fringes separated by a distance which depends on wavelength and the crossing angle of the two beams. The light triggers a photopolymerization reaction in the bright regions and records a permanent refractive index modulation, a hologram, which serves as a record of the laser interference pattern. Light incident normally on the badge will produce a normal index grating. Light incident at an angle will produce a slanted grating.

Abstract: An apparatus is disclosed for changing the scale of a pattern printed from a total internal reflection hologram into a photosensitive layer, which apparatus includes means for reconstructing an image from said total internal reflection hologram by illuminating said total internal reflection hologram with a scanning beam and means for moving at least one of the hologram and photosensitive layer such that the magnitude of movement of the hologram relative to the photosensitive layer is equal to that of the scanning beam multiplied by the change of scale required and such that if said change of scale is a magnification the direction of said movement of the hologram relative to the photosensitive layer is the same as that of the scanning beam whereas if said change of scale is a demagnification then the direction of said movement of the hologram relative to the photosensitive layer is opposite to that of the scanning beam, and optionally comprising also means for increasing or reducing the convergence or divergen

Abstract: A combiner for combining light traveling on two optical paths to permit coincident viewing of the light includes a light-transmissive substrate having first and second surfaces, the first surface having a first diffractive structure that is a computer-generated hologram formed thereon configured to correct aberrations in light travelling on the first optical path which may be incident on the first surface and a partially reflective coating on the first diffractive structure, the partially reflective coating being reflective in a narrow bandwidth only, the first diffractive structure and the partially reflective coating configured to provide corrected reflection to light travelling on the first optical path, the second surface having a second diffractive structure that is a computer-generated hologram formed thereon as a conjugate of the first diffractive structure, so that light travelling on a second optical path which may be incident on the second surface passes through the second and first diffractive stru

Abstract: A holographic optical system includes volume hologram configurations providing a waveplate for, e.g. an optical storage device, and an aliasing suppression filter. The waveplate has diffraction characteristics adapted to impart a propagation delay for selected polarization directions. By controlling the propagation delay and the angle of an incident light beam, an output beam having altered polarization characteristics can be produced. Quarter waveplates for reflective optical storage systems and half waveplates for magneto-optical storage systems are disclosed. The holographic aliasing suppression filter divides an input optical beam into spatially separated components and may be configured to be polarization insensitive or color selective.

Abstract: A hologram comprising a diffraction grating film with an interference fringe recorded thereon, a substrate provided on one side of said diffraction grating film, and cover plates provided on the surfaces of the aforesaid diffraction grating film by use of an adhesive, wherein the lateral face portion of the aforesaid hologram is covered with a water repellent layer, or a hologram comprising a diffraction grating film with an interference fringe recorded thereon and a substrate provided on one side of said diffraction grating film, the surface of the aforesaid diffraction grating film being covered with an adhesive, wherein the aforesaid adhesive contains an epoxy resin mixture consisting of an alicyclic epoxy and novolak type epoxy and an alicyclic acid anhydride type curing agent, a chief ingredient composed of an aromatic epoxy resin(s) and a curing agent comprising a mixture of an alicyclic amine and an aliphatic amine, or a chief ingredient composed of an aromatic epoxy resin(s) and a curing agent compris

Abstract: This invention relates to a process for forming a reflection hologram. A process for forming a volume reflection hologram is provided wherein the formation of secondary holograms is suppressed by the placement of index matched filters contiguous to at least one surface of the photosensitive recording element during formation of the hologram.

Abstract: Disclosed is a method for producing an optical member having excellent optical characteristics. An optical member is composed of a support plate and an optical sheet stuck on said plate via an optical adhesive. The optical adhesive is made sticky after it is coated, including ultraviolet-curing adhesives, epoxy adhesives and their mixtures. To produce the optical member, the optical sheet is formed on the surface of a fixed substrate via a transfer film. The optical adhesive is coated onto the optical sheet, the adhesive is made sticky on the sheet, the fixed substrate is peeled off, the sheet is stuck onto the support plate using the adhesive, and the adhesive is cured.

Abstract: In a preferred embodiment, a method of providing secure identification for an article, including: providing on the article a diffraction grating strip including a pattern of a series of diffraction grating elements, each the diffraction grating element to diffract light, from a light source, in one of at least three selected different planes; serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating first information representative of the changes in plane; storing the first information representative of the changes in plane; subsequently, serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating second information representative of the changes in plane; and then, comparing the first and second information to determine the authenticity or not of the article.

Abstract: The invention relates to an illumination device in which a holographic device (HP.sub.i) separates the polarizations of an incident beam. The resulting polarized beam is transmitted to a holographic device (HL.sub.i) focusing the beam at various points of a screen. This screen may be a liquid-crystal screen (LCD).Applications: Liquid-crystal display.

Abstract: The present invention is directed to a diffractive display suitable for presenting graphic and the like displays. Broadly, the novel display is realized from a diffraction pattern (132) carried by (e.g. embossed) a film or element (138) connected to an energy source which is energizable for movement of the film (138). Movement of the patterned film (138) generates a display using the diffracted light from the embossed pattern (132). Electroactive films are known in the art, including, for example, piezoelectric films, electrostrictive films, electromotive films, and electrostatic films. Magnetoactive films also are known in the art. Any of these films (138) can carry the diffraction pattern (132) and be energized for movement to generate from the resulting diffracted light.

Abstract: The present invention relates to a three-component optical photorefractive article having improved diffraction efficiency. The article comprises (i) nonphotoconductive polymer, (ii) benzimidazoline, and (iii) a sensitizer.

Abstract: A process for making a multilayer photopolymer hologram structure without intervening adhesive layers between component photopolymer layers.

Abstract: A hologram system is comprised of two identical volume holograms. Both holograms have Bragg planes oriented perpendicular to the surface of the hologram. The first volume hologram separates a single beam into two orthogonal polarization component beams. The second volume hologram diffracts one of the polarization component beams such that a desired separation angle is achieved between the two beams. This separation angle may be precisely adjusted during manufacture by orienting the Bragg planes of the second volume hologram at a rotational angle with respect to the Bragg planes of the first volume hologram.

Abstract: Method and apparatus for monitoring wavelength shift in a holographic light protection filter to determine if the hologram has been damaged by moisture. The hologram is provided with first, second and third areas. The first area is an extra moisture protected area covered by a moisture resistant material. The second area is adjacent to the first area and is recorded at a different wavelength than the bulk of the hologram. The third area is the remainder of the hologram. The user compares light reflections at these specific areas of the hologram and observes color variations to determine if the hologram has been damaged by moisture. In another embodiment, scribe lines are drawn in the hologram through the three areas. The user detects moisture damage by observing the apparent displacement of these scribe lines in the three areas when viewed through a diffraction grating.

Abstract: A process for the production of a flexible laminate having an outer and visible layer which provides a holographic effect. A metal foil bearing a holographic image and a layer of plastics size is brought together with a flexible substrate having an outer layer of a plastics material which is comparable with said size. The substrate and foil are brought together with their plastics layers adjacent each other, under conditions of heat and pressure at a level and for a time sufficient to adhere the foil to the substrate but insufficient to destroy the holographic effect.

Abstract: An image display apparatus includes a plurality of image display elements respectively assigned to different partial image information regions of an image to be displayed, and a hologram optical element for diffracting a plurality of light beams from the plurality of image display elements and displaying the diffracted light beams as continuous single image information. By including a plurality of image display elements, each of the image display elements having a large number of pixels, and a hologram optical element for forming a synthesized image by diffracting a plurality of image light beams from the image display elements, the hologram optical element diffracts the plurality of image light beams so as to display a synthesized image by interpolating information between pixels of a plurality of images to be synthesized.

Abstract: A hologram recording device, which comprises a recording layer of a polymer composition a photoconductive element, a second-order super-polarization element and an electron or hole capturing material and having a non-centro symmetric structure is disclosed. Transparent electrode layers are provided on each side of the recording layer. The hologram recording device is capable of space light modulation and real time hologram recording. Also disclosed is a method of manufacturing the hologram recording device and a method of hologram recording using the device. The hologram recording material is of a polymer composition a photoconductive element, a second-order super-polarization element and an electron or hole capturing element. The polymer composition has a non-centro symmetric structure. The hologram recording device according to the invention comprises a recording layer of a polymer composition including a photoconductive element and a second-order super-polarization element.

Abstract: A flexible fiber optic delivery system for medical and industrial applications is described that can transmit high laser power densities and optical images. A parabolic-index profile of a graded-index fiber is perturbed so as to prevent strong localization of a laser beam in the fiber's recurring focal regions. This permits transmission of high laser powers without danger of fiber damage. An additional gain in carrying capacity for the system is achieved by using a wavefront perturbation system between the laser source and the graded-index fiber. Optical image transmission is achieved by using a measured perturbation to a parabolic-index profile of the graded-index fiber with a prescribed length and a wavefront reconstruction system in combination with the wavefront perturbation system. The system has an increased laser induced damage threshold and can transmit highly focused optical images.

Abstract: A method and a viewing device for generation of selective visual effects. The method entails encoding a holographic optical transparency for generating pre-selected patterns of light when stimulated by appropriate sources of light and a structure to enable viewing through such a transparency. The viewing device contains a suitably encoded holographic optical transparency and a structure produced with semi-rigid material which allow viewing of the natural scene through the transparency with two eyes. The encoding of the transparencies causes all limited extent light sources in a scene to be replaced with pre-selected patterns of light while producing minimal distortion in the remainder of the scene.

Abstract: A novelty filter utilizes self-nulling and self-aligning of reflection and transmission phase conjugate beams. A photorefractive crystal is arranged so that the contributions to the phase conjugate are equal and opposite in the steady state to produce destructive interference when the input image is stationary, and thus no output image is displayed. If the image moves, then the gratings will rewrite and erase themselves, each with their own response times, total destructive interference will not occur, and transient enhancement and surpression of the phase conjugate output signal will indicate the direction of motion of the input image.

Abstract: A holographic storage media (10) is fabricated from a thin layer of photopolymer recording media. The photopolymer recording media is disposed between a substrate (48) and a capping layer (56). The media (10) is divided into a plurality of storage regions (54), which are formed within wells (52) to isolate each of the regions (54). During a record operation, a pumping operation is first performed to remove oxygen molecules from the media by bombarding the select region that is to have an interference pattern recorded therein with photons for a predetermined duration of time. Once the oxygen molecules have been depleted, then a data beam is generated with data superimposed thereon and a reference beam generated for interference with the data beam in the storage region (54). This results in the recording of an interference pattern.

Abstract: An optical data storage system includes a pivotally mounted hologram. Rotation of the hologram results in beam displacement at the optical medium for purposes of fine tracking. The hologram is designed and positioned relative to the focusing lens, such that the beam always passes through the center aperture of the lens even when the beam is displaced at the optical medium. Thus, the beam is not truncated at the focusing lens and loss of light and aberration problems are prevented.

Abstract: A display card is provided on one surface thereof with two images which appear to an observer to be interacting. One of the images is provided on the card by quality ink printing such as lithography. At least a portion of this image occupies but only a portion of a prescribed field of view on the card. The second image, which occupies substantially all of the remainder of the field of view, is provided by a plastic coating adhered to the card and having a reflection-type hologram embossed therein. The holographic image circumscribes and touches at every possible point that portion of the printed image occupying a portion of the field of view. The method of making the display card comprising ink printing one image and adhering the plastic coating bearing the hologram on the card in a manner to circumscribe that portion of the printed image which occupies the field of view.

Abstract: Composite mirrors on a substrate comprising a mixture of up to 20 percent of polymer and at least 80 percent of metal clusters, e.g. of gold, palladium or silver, which have a nominal diameter less than 100 nanometers and which are agglomerated in a layer conforming to the surface of the substrate. Composite mirrors are produced by coating a substrate with a solution comprising at least 80 percent solvent, e.g. water and alcohol, and up to 20 percent of a mixture of up to 20 percent polymer, e.g. methylcellulose, and at least 80 percent metal, present as a salt of volatiles-forming anion, e.g. silver lactate or palladium acetate; dry films of polymer and salt are exposed to heat or ultraviolet light to convert the salt to metal clusters. Polymeric mirrors are especially useful for making reflection holograms on polymeric surfaces embossed with a latent holographic image in a relief pattern.

Abstract: A process for the production of a flexible laminate having an outer and visible layer which provides a holographic effect. A metal foil bearing a holographic image and a layer of plastics size is brought together with a flexible substrate having an outer layer of a plastics material which is comparable with said size. The substrate and foil are brought together with their plastics layers adjacent each other, under conditions of heat and pressure at a level and for a time sufficient to adhere the foil to the substrate but insufficient to destroy the holographic effect.

Abstract: A hologram recording method wherein a transparent member for introducing a light beam into a recording material is designed so that the transparent member and the recording film can be uniformly brought into close contact with each other through an index matching liquid without damaging the recording film, and it is possible to stably carry out uniform and continuous exposure without failure of recording nor occurrence of unnecessary interference fringes. Also disclosed is a recorded hologram. A transparent member (3) is disposed at one surface of a recording film (2). A surface (5) of the transparent member (3) that is brought into close contact with the recording film (2) is convexly curved only in the direction of feed of the recording film (2). In addition, the space between the contact surface (5) and the recording film (2) is filled with an index matching liquid (4) so that the recording film (2) is brought into close contact with the transparent member (3) through the index matching liquid (4).

Abstract: Holographic flake pigments, processes for making the pigments, decorative coatings comprising the pigments, and articles comprising the decorative coatings are disclosed. The pigment comprises particles that (1) comprise an organic polymer and further comprise one or more volume phase holograms; and (2) have a thickness of about 1 micrometer to about 100 micrometers, an average diameter of about 10 micrometers to about 300 micrometers, and a thickness to diameter ratio of about 1:2 to about 1:60.

Abstract: Holographic flake pigments, processes for making the pigments, decorative coatings comprising the pigments, and articles comprising the decorative coatings are disclosed. The pigment comprises particles that (1) comprise an organic polymer and further comprise one or more volume phase holograms; and (2) have a thickness of about 1 micrometer to about 100 micrometers, an average diameter of about 10 micrometers to about 300 micrometers, and a thickness to diameter ratio of about 1:2 to about 1:60.

Abstract: A method of writing plane holographic gratings Bragg-matched for reflection in the infrared in a photorefractive material using shorter wavelength light through a face perpendicular to the grating planes. The writing beam wavelength is selected to be within the photorefractive sensitivity range of the crystal and the angles are chosen relative to the wavelength to define a reflection grating with a period such that counter-propagating reflection occurs at the desired IR wavelength. For reflection gratings at different wavelengths, either the transmission or the reflection mode geometry may be used. In the transmission mode, the writing beams are incident on the same side face while in the reflection made the writing is on opposite faces in an off-axis (non-counter-propagating) configuration. Anti-reflection coatings of the appropriate wavelengths are used on the crystal surfaces to reduce reflection losses and improve the diffraction efficiency of the grating.