Abstract: Disclosed is a hologram transfer film which can realize easy and good transfer of a hologram and, at the same time, can realize stable transfer of the hologram in a transfer process. The hologram transfer film comprises: a substrate film; and a transfer layer provided on the substrate film, the transfer layer comprising a hologram-forming layer and a heat-sensitive adhesive layer provided in that order on the substrate film, the hologram-forming layer having a breaking strain of 0.5 to 15% at 25° C. and a breaking strain of 0.5 to 30% at 120° C.

Abstract: In a second exposure following a first exposure, a light transmitting-screening pattern of a second original mask is exposed on a hologram material by using a second object light to be irradiated on a hologram material though the second original mask and a second reference light to be irradiated on a hologram material to be irradiated on the hologram material not through the second original mask, and by changing a second phase difference between the second object light and the second reference light in a position in an optical path from a light source to the hologram material so that a first phase difference between the first object light and the first reference light may differ from the second phase difference.

Abstract: A novel process is proposed for the volume diffractive element (Bragg grating) fabrication in photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine. The process employs a photo-thermo-refractive (PTR) glass of high purity exposed to ultraviolet (UV) radiation of a He—Cd laser at 325 nm followed by thermal development at temperatures from 480° C. to 580° C., preferably at 520° C., from several minutes to several hours. Absolute diffraction efficiency up to 95% was observed for 1 mm thick gratings. Maximum spatial frequency recorded in PTR glass was about of 10,000 mm−1. No decreasing of diffraction efficiency were detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm−1) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm−1 between 400 and 700 nm, respectively, and did not exceed 0.01-0.02 cm−1 in the infrared (IR) region from 700 to 2500 nm.

Abstract: A metallic-deposition-type thermal hologram sheet having laser evaporated portions is provided. The hologram sheet includes a base sheet, a release layer, a hologram forming layer, and a metallic deposition layer. A portion of the metallic deposition layer is removed in a slit-like or mesh-like pattern by laser machining in order to form a pseudo-transparent or pseudo-semitransparent hologram sheet in the area that contains the removed portions.

Abstract: A planar and fiber optical grating structure includes a phase mask that intrinsically contains apodization. The phase mask is a volume hologram resulting from refractive index change in the media. The apodized volume hologram phase mask incorporates a change in diffraction efficiency along its length without a reduction in the average transmittance through the mask, and without changing the average refractive index of the grating along the full length of the grating. The phase mask intrinsically produces exactly two diffraction orders, the zero order and the first order, and is functional over a wavelength range greater than 10 nanometers without substantive interference from undesired diffraction orders while still maintaining adequate channel isolation.

Abstract: Disclosed is an optical recording medium having a charge generating ability capable of generating electric charges with different polarities upon irradiation with light and a charge transporting ability capable of transporting at least one of the electric charges to separate specially the electric charges from each other forming an electric field upon irradiation with light, the optical characteristics of the optical recording medium being changed depending on the electric field, wherein the charge transporting capability is imparted by a charge transporting material formed of a molecule having a charge transporting capability or a polymer containing a monomer unit having a charge transporting capability. A light intensity pattern is recorded in the optical recording medium depending on the change in the optical characteristics caused by the electric field. The average intermolecular distance of a noticed charge transporting material is defined to fall within a predetermined range.

Abstract: Disclosed is an optical recording medium comprising a recording layer. The recording layer contains: a charge generation material generating an electron and a hole by light irradiation; a charge transport material transporting one of the electron and the hole; a charge trap which traps the transported one of the electron and the hole to separate the electron and the hole; and a non-linear optical material which changes optical properties of the recording layer in accordance with electric field formed by the electron and the hole being separated from each other. The non-linear optical material has an asymmetrical carbon atom and a cyclic group. Or, it is a cyclic-group-containing constituent having: an inversion symmetric pi-electron system; at least one of an electron donating group and an electron accepting group which are bonded to the inversion symmetric &pgr;-electron system; and an asymmetrical carbon atom.

Abstract: An optical recording material which when exposed to actinic radiation produces a change in optical properties in the exposed regions, thereby providing a pattern of intelligence for storing and retrieving information, the recording material comprising: a) a binder; b) a reactant which is capable of undergoing a chemical transformation upon a one electron oxidation, thus causing the change in optical properties in the exposed regions; and c) a sensitizer capable of absorbing actinic radiation to cause an initial one electron oxidation of the reactant.

Abstract: A hologram recording material composition is disclosed, comprising (A) an allyl-based prepolymer having at least one allyl group in a molecule thereof, (B) a (meth)acrylate-based compound having at least one polymerizable unsaturated group in a molecule thereof, and (C) a photo-polymerization initiator, wherein a difference between a refractive index of said allyl-based prepolymer (A) and a refractive index of a polymer of said (meth)acrylate compound (B) is 0.005 or more.

Abstract: The present invention provides a photopolymerizable liquid crystal monomer having high durability, a low melting point and an enantiotropic property. The photopolymerizable liquid crystal monomer is a 4-(4-(alkyloxycarbonyloxy)benzoyloxy)phenyl acrylate represented by the following formula A [wherein Ph is a 1,4-phenylene group, and R is an alkyl group]: CH2═CHCOO—Ph—OCO—Ph—OCOO—R  Formula A Further, the present invention provides a polymer liquid crystal obtained by polymerizing a composition containing the monomer. Further, the present invention provides an optical element employing the polymer liquid crystal, and an optical head employing the optical element as a polarizing hologram element.

Abstract: The present invention provides a volume type hologram recording photosensitive composition. A type (i) composition comprises one or more photopolymerizable compounds, a heat-curable compound and a heat-curing crosslinking agent, wherein the heat-curing crosslinking agent is a latent heat-curing crosslinking agent which is not reacted in an interference exposure process, is not reacted at the heating temperature used in a refractive index-modulation promoting process and becomes active at the heating temperature used in a heat-curing process. A type (ii) composition further comprises a binder resin beside the type (i) volume type composition.

Abstract: This invention relates to the photo-sensitive thermoplastic top-layer of optical media for registration of holograms, where the media consists of three transparent layers where the bottom layer is a glass substrate, the mid layer is an electro-conductive film of tin dioxide, and the top layer is a thermoplastic photo-sensitive amorphous molecular semiconductor film made of a matrix which has donor properties and forms transport bands for holes, and were the matrix is doped with; a photo-sensitive substance (CICT) that has intramolecular physically separated parts with donor and acceptor properties, respectively, and which creates an intramolecular electron-hole pair when absorbing a light quantum, and which has a HOMO-level which is below the HOMO-level of the matrix substance, and a substance with acceptor properties that forms transport bands for electrons, which has a similar ring structure as the acceptor part of CICT to ensure a barrierless transfer of excited electrons from CICT to acceptor-molecules

Abstract: Blue-sensitized holographic media suitable for recording with a blue laser is disclosed. The blue-sensitized holographic media provides greater dynamic range and a higher sensitivity than a green-sensitized holographic media, thereby providing more rapid hologram writing times.

Abstract: A holographic information storage and retrieval system provides an all-optical reversible method to fix information in doped or undoped photorefractive materials. The fixed information is sufficiently stable to provide long term archival storage over a period of decades or more and can be read out non-destructively by a coherent reference beam. Holograms recorded in a photorefractive material are fixed when the material is irradiated with incoherent ultraviolet light. Hence, the holograms are preserved indefinitely against erasure by a coherent beam and against dissipation in dark storage. Holograms, which are fixed in the photorefractive material with incoherent ultraviolet light, are. also erased with incoherent ultraviolet light, thus making the process reversible.

Abstract: A method of writing a Bragg grating in a photosensitive optical waveguide (40) is disclosed comprising utilizing a single coherent beam of light (31) and a diffraction grating (32) to create two coherent working beams (33, 38) of light; positioning a plurality of reflective elements (35, 37) on each side of said waveguide; propagating the two working beams around said plurality of reflective elements, each of the beams being reflected by each of the reflective elements, so that the beams interfere at an initial predetermined position (45); and rotating at least one of the reflective elements on each side of the waveguide to simultaneously independently control the period of the interference pattern and position of the interference pattern in accordance with predetermined requirements so as to produce the grating structure in the photosensitive waveguide.

Abstract: A holographic recording medium comprising an amorphous host material which undergoes a phase change from a first to a second thermodynamic phase in response to a temperature rise about a predetermined transition temperature; a plurality of photo-sensitive molecular units embedded in the host material and which can be orientated in response to illumination from a light source; whereby said molecular units may be so orientated when said host material is at a temperature equal to or above said transition temperature but retain a substantially fixed orientation at temperatures below said transition temperature.

Abstract: Disclosed is a pretreatment method for a hologram recording medium used in the hologram recording method in which information signals loaded on signal beam are recorded by injecting coherent signal beam and reference beam to the hologram recording medium which is exposed to first light having first wavelength of ultraviolet band or short-wavelength visible light band in advance in order to generate light-induced absorption, wherein the coherent signal beam and reference beam each having longer wavelength than the first wavelength. The pretreatment method comprises subjecting the hologram recording medium to oxidation treatment prior to the irradiation of the first light has been completed.

Abstract: The positive image-forming material comprises a resin including a repeating unit corresponding to a specific monomer having an &agr;-heteromethyl structure.

Abstract: The present invention provides a method and apparatus for producing holographic stereograms. Holographic stereograms have made possible the creation of holograms of both real objects in natural or studio lighting and virtual objects created using three-dimensional graphics. There are several approaches for creating holograms from digital graphics. This paper discusses the application of the light valve to the process along with other related developments. Artists can now produce high quality inexpensive, medium-format holograms using this direct-link to digital media. Future developments will led to even higher resolution Digital Image-Light-Amplifier (D-ILA) systems.

Abstract: A holographic recording medium comprising an amorphous host material which undergoes a phase change from a first to a second thermodynamic phase in response to a temperature rise about a predetermined transition temperature; a plurality of photo-sensitive molecular units embedded in the host material and which can be orientated in response to illumination from a light source; whereby said molecular units may be so orientated when said host material is at a temperature equal to or above said transition temperature but retain a substantially fixed orientation at temperatures below said transition temperature.

Abstract: A rapid mass production of the high performance holographic recording articles including the process and composition are described. To prepare a high performance holographic recording article based on two-component urethane matrix system, for example, polyols and all the additives must be virtually free of moisture contents. Deaeration must be carried out, once isocyanate and polyols including catalysts and all other ingredients are mixed together, to eliminate all entrapped air that is introduced into the mixture during mixing. The deaeration takes time, and the urethane reaction must not be allowed to take place until all air bubbles are evacuated from the isocyanate-polyols mixture. The rapid mass production of this invention overcomes such process limitations and results in a high-volume production of the high performance holographic recording articles.

Abstract: A photopolymer data recording media includes (1) a substrate layer, (2) a capping layer, and (3) a photopolymerizable layer between the substrate layer and the capping layer comprising (a) an actinic monomer, (b) a polyurethane binder comprising the reaction product of (i) a polyisocyanate having at least two reactive isocyanate groups pendant from a primary carbon atom and a viscosity of less than about 1,000 mPa·s, and (ii) a polyol, and (c) a photosensitive initiator.

Abstract: There are disclosed the following three types of optical recording film: (1) an optical recording film comprising a gel having a network structure of an inorganic substance and a polymer which is from a photopolymerizable compound (A) and present in the network structure in the gel, said gel containing an optical recording-induced difference in the network structure. (2) an optical recording film, which consists essentially of a porous gel having a network structure of an inorganic substance, the porous gel containing recording-induced porosity differences in the network structure. (3) an optical recording film which consists essentially of a porous gel having a network structure of an inorganic substance or a gel obtained by densification of the porous gel, the porous gel or the gel having a recording-induced concavo-convex form on the surface thereof.

Abstract: A hologram recording film has a hologram image of an object recorded in a volume hologram photosensitive material by holographic duplication and further has a hologram image of an additional information pattern, e.g. a character or an image, recorded superimposedly in the same volume hologram photosensitive material simultaneously with the holographic duplication so that the additional information pattern is reconstructable in a plane with a depth from the hologram plane. Reflection type additional information is recorded in the hologram recording film so as to be reconstructable simultaneously in superimposition with a reconstructed image from the volume hologram. In addition, transmission type additional information that is in mirror image relation to the reflection type additional information is recorded in the hologram recording film so as to be reconstructable simultaneously in superimposition with the reconstructed image from the volume hologram.

Abstract: A system is provided for positioning separate portions of a sample in elongate, parallel channels of a sample chamber and for irradiating a sample in the chamber to create a diffraction pattern where the sample and chamber differ in refractive index. The system also can measure absorption of electromagnetic radiation by a sample in the chamber, and can measure the absorption simultaneously with measurement of diffraction by the sample.

Abstract: A method and apparatus for forming a device in a substrate having grating structure, includes a substantially coherent and collimated light source, a mirror having a non-planar surface, and a substrate. The mirror, substrate, and stationary light source are disposed in fixed position with respect to one another. The components are arranged such that some light beams from the light source are projected directly onto the substrate surface and other light beams are reflected from the mirror surface onto the substrate surface. The respective beams converge at the substrate surface at different interference angles across the substrate surface. The different interference angles produce an interference pattern having a varying interference period which preferably uniformly increases or decreases across the substrate. The corresponding grating structure formed within the substrate using this interference pattern, therefore also includes the varying grating period. The device formed in the substrate may be a laser.

Abstract: A pressure-sensitive adhesive for a pressure-sensitive adhesive layer in a volume hologram laminate is provided which, when kept in the pressed state, for example, during storage, is less likely to cause spotty hologram defects in the volume hologram layer. The pressure-sensitive adhesive for a pressure-sensitive adhesive layer in a volume hologram laminate is a pressure-sensitive adhesive for a pressure-sensitive adhesive layer in a volume hologram laminate comprising a substrate 2 and, stacked on the substrate 2 in the following order, a first pressure-sensitive adhesive layer 3, a volume hologram layer 5, a second pressure-sensitive adhesive layer 4, and a surface protective film 6, the second pressure-sensitive adhesive layer having been formed from an acrylic pressure-sensitive adhesive comprising an acrylic copolymer resin, composed mainly of an alkyl acrylate, and a crosslinking agent, the second pressure-sensitive adhesive layer having a dynamic storage modulus of not less than 2.

Abstract: A method of producing indicia on a metallized and/or a holographic film comprising the steps of (a) printing, on an etchable surface of the film, a co-polymeric primer in a predetermined pattern, (b) depositing an activated etching substance on top of at least the unprinted metallized and/or holographic material under conditions sufficient to etch away portions of the film not covered by the primer and thereby forming a crystallized material as the debris of etching, (c) removing the crystallized material formed during etching and also removing any excess etching substance, and (e) drying the etched, printed film. Optionally, a reinforcing film layer may be disposed over the etched surface. The reinforcing layer may be colored in a predetermined pattern, especially a pattern that corresponds to the pattern of printing of the non-etchable copolymer.

Abstract: There is provided an optical recording medium comprising a recording layer containing a charge-generating material capable of generating a first electric charge and a second electric charge by beam irradiation, the second electric charge having a different polarity from that of the first electric charge, a charge-transport material enabling at least the first electric charge to be transported to isolate the first electric charge and the second electric charge, and a trapping material retaining the first electric charge. The optical characteristics of the recording layer is changed in accordance with changes in spatial distribution of the first and second electric charges, and the trapping material is provided with a conjugated system and with at least one nitrogen-containing heterocyclic group, and bonded through an unsaturated carbon atom of the heterocyclic group to the conjugated system.

Abstract: A method of fabricating a thin film transistor array substrate for a liquid crystal display includes the step of forming a gate line assembly with gate lines, gate electrodes and gate pads. After laying a plurality of layers on the substrate, a photoresist film is deposited onto the layers. The photoresist film is first exposed to light at a first light exposing unit, and secondly exposed to light at a second light exposing unit such that the photoresist film has three portions of different thickness. The photoresist pattern, and some of the underlying layers are etched to form a data line assembly, a semiconductor pattern, and an ohmic contact pattern. The data line assembly includes data lines, source and drain electrodes, and data pads. The remaining photoresist film is removed, and a protective layer is formed on the substrate.

Abstract: When a master hologram is to be formed in this method, a diffusing screen image is output as object light onto a first recording surface 12 via a lens 8′. When a slave hologram is to be formed, a second recording surface 12″ is placed in a position where an image of the object light is formed by the lens 8′. In this method, the distance between a diffusing screen 7′ and the first recording surface 12 when a master hologram 12′ is recorded can be made different from the distance between the master hologram 12′ and the second recording surface 12″ when a slave hologram 12″ is recorded. By varying these distances as needed, a hologram can be formed using a small optical system.

Abstract: Processes for producing a holographic material wherein the holographic image is formed on a polished surface of a printing element and then transferred to a substrate. A coating is applied to the polished surface of the printing element to provide a coated surface, the coated surface is engraved to provide the holographic image, and the holographic image is then transferred to a substrate via a bonding material, thereby producing the holographic material. The holographic material may be used to provide a decorative cover for an object or item, such as a floral grouping or a potted plant.

Abstract: A post-exposure treatment method of a silver halide emulsion layer in the manufacture of a hologram, a hologram manufacturing using the post-exposure treatment method, and a holographic optical element including the hologram are provided. The post-exposure treatment method of a silver halide emulsion layer involves: pre-hardening the silver halide emulsion layer after exposure; developing the pre-hardened silver halide emulsion layer using a developer solution; bleaching the developed silver halide emulsion layer; hardening the bleached silver halide emulsion layer; drying the hardened silver halide emulsion layer; surface-hardening the dried silver halide emulsion layer; fixing the hardened silver halide emulsion layer; treating the fixed silver halide emulsion layer using warm water; and drying the silver halide emulsion layer which has been treated using warm water.

Abstract: A holographic recording medium comprising an amorphous host material which undergoes a phase change from a first to a second thermodynamic phase in response to a temperature rise above a predetermined transition temperature; a plurality of photo-sensitive molecular units embedded in the host material and which can be orientated in response to illumination from a light source; whereby said molecular units may be so orientated when said host material is at a temperature equal to or above said transition temperature but retain a substantially fixed orientation at temperatures below said transition temperature.

Abstract: Disclosed is a hologram transfer film which can realize easy and good transfer of a hologram and, at the same time, can realize stable transfer of the hologram in a transfer process. The hologram transfer film comprises: a substrate film; and a transfer layer provided on the substrate film, the transfer layer comprising a hologram-forming layer and a heat-sensitive adhesive layer provided in that order on the substrate film, the hologram-forming layer having a breaking strain of 0.5 to 15% at 25° C. and a breaking strain of 0.5 to 30% at 120° C.

Abstract: A thickness of each hologram lens for forming a hologram color filter is set so as to be smaller as the wavelength of light to be diffracted by each hologram lens is shorter. A thin plate glass layer is bonded to a surface of the hologram color filter such that it is in a firm contact therewith by adhesive agent and a sum of the thickness of the thin plate glass layer and thickness of the adhesive agent is smaller than the shortest focal length of the focal lengths in glass of a plurality of the hologram lenses. As a result, light diffracted and divided by the hologram color filter is focused on a picture element electrode of a corresponding color properly thereby eliminating deterioration of color reproduction due to mixing of colors. Further, upon production of the hologram color filter from hologram recording material, an influence of a fringe rotation is compensated.

Abstract: A holographic recording medium comprises (a) an acid generator capable of generating an acid upon exposure to actinic radiation; and (b) a polymer comprising a plurality of high refractive index moieties, a plurality of low refractive index moieties, and a plurality of acid-sensitive linking groups connecting the high and low refractive index moieties. When an interference pattern is formed within this medium, in the light areas of this interference pattern acid is generated by the acid generator and cleaves the acid-sensitive linking groups, thereby causing separation of either the high or the low refractive index moieties from the polymer, and formation of a hologram within the medium.

Abstract: The optical article of the invention, e.g., holographic recording medium or polymeric waveguide, is formed by mixing a matrix precursor and a photoactive monomer, and curing the mixture to form the matrix in situ. The reaction by which the matrix precursor is polymerized during the cure is independent from the reaction by which the photoactive monomer is polymerized during writing of data. In addition, the matrix polymer and the polymer resulting from polymerization of the photoactive monomer are compatible with each other. Use of a matrix precursor and photoactive monomer that polymerize by independent reactions substantially prevents cross-reaction between the photoactive monomer and the matrix precursor during the cure and inhibition of subsequent monomer polymerization. Use of a matrix precursor and photoactive monomer that result in compatible polymers substantially avoids phase separation. And in situ formation allows fabrication of articles with desirable thicknesses.

Abstract: A glass diffuser is fabricated by first producing a metal shim submaster or other high temperature resistant diffuser having a surface relief structure on one surface. A glass substrate material is heated to a suitable temperature and at least one exposed surface is thereby softened to a desired degree. The submaster diffuser, and particularly the surface relief structure, is then placed in contact with the exposed and softened glass substrate material in order to replicate the surface relief structure in the glass material. The submaster diffuser and the glass substrate are separated and then the glass is allowed to cool to form a glass diffuser.

Abstract: There are disclosed the following three types of optical recording film: (1) an optical recording film comprising a gel having a network structure of an inorganic substance and a polymer which is from a photopolymerizable compound (A) and present in the network structure in the gel, said gel containing an optical recording-induced difference in the network structure. (2) an optical recording film, which consists essentially of a porous gel having a network structure of an inorganic substance, the porous gel containing recording-induced porosity differences in the network structure. (3) an optical recording film which consists essentially of a porous gel having a network structure of an inorganic substance or a gel obtained by densification of the porous gel, the porous gel or the gel having a recording-induced concavo-convex form on the surface thereof.

Abstract: A method is disclosed for replicating (copying) a master hologram into a photosensitive layer to produce a copy of the hologram in a manner such that the copy of the hologram is an accurate and true replication of the master hologram with minimum interface-related defects. A holographic element containing a master hologram for use in contact copying is also disclosed.

Abstract: In order to prevent decrease in diffraction efficiency that is brought about when the diffraction peak wavelength shifts due to, for example, the shrinkage of a volume-hologram-recording photosensitive material layer 1, the present invention provides an original volume hologram film 10. The original volume hologram film 10 has a volume-hologram-recording photosensitive material layer 1 provided on a film 2, and an adhesive layer 8 provided on a film 9. The films 2 and 9 are affixed to each other with the layer 1 and 8 facing each other. The volume hologram has been recorded in the layer 1. The layer 8 can migrate an ingredient to the layer 1 to shift the diffraction peak wavelength to the opposite side.

Abstract: This invention relates to the field of holography, in particular to a method and a device for recording optical holograms by means of amorphous molecular semiconductor (AMS) films deposited on a glass substrate pre-covered with a transparent electric conducting sub-layer. More precisely, the invention relates to a method and device for registering optical holograms on AMS-films which operates in such a way that the AMS-films possess the maximum achievable information parameters: Holographic sensitivity, optimal spatial frequency of the transmitted characteristic, band parameters for the spatial frequencies of the transmitted characteristic, “signal-to-noise” ratio in the restored holographic image, reference and object beam intensities ratio during hologram registration, and cycling ability.

Abstract: A holographic information storage and retrieval system provides an all-optical reversible method to fix information in doped or undoped photorefractive materials. The fixed information is sufficiently stable to provide long term archival storage over a period of decades or more and can be read out non-destructively by a coherent reference beam. Holograms recorded in a photorefractive material are fixed when the material is irradiated with incoherent ultraviolet light. Hence, the holograms are preserved indefinitely against erasure by a coherent beam and against dissipation in dark storage. Holograms, which are fixed in the photorefractive material with incoherent ultraviolet light, are also erased with incoherent ultraviolet light, thus making the process reversible.

Abstract: The optical article of the invention, e.g., holographic recording medium or polymeric waveguide, is formed by mixing a matrix precursor and a photoactive monomer, and curing the mixture to form the matrix in situ. The reaction by which the matrix precursor is polymerized during the cure is independent from the reaction by which the photoactive monomer is polymerized during writing of data. In addition, the matrix polymer and the polymer resulting from polymerization of the photoactive monomer are compatible with each other. Use of a matrix precursor and photoactive monomer that polymerize by independent reactions substantially prevents cross-reaction between the photoactive monomer and the matrix precursor during the cure and inhibition of subsequent monomer polymerization. Use of a matrix precursor and photoactive monomer that result in compatible polymers substantially avoids phase separation. And in situ formation allows fabrication of articles with desirable thicknesses.

Abstract: The invention relates to improvements in security features in paper and other substrates and in particular to an activatable feature to warn of tampering. The invention further relates to a security feature for a security document comprising at least one activatable layer and at least one visually apparent masking layer, said at least one activatable layer comprising a composition which is generally non-mobile but which becomes mobile when wetted with a liquid, said composition further including at least one detectable component, in which under dry conditions said at least one masking layer wholly covers the activatable layer and renders it non-detectable.

Abstract: A method is provided for producing a holographic optical element that is comprised of at least one primary hologram (as defined herein) and at least one complementary hologram (as defined herein). The holographic optical element is useful as a security device, since it is relatively easily produced and yet is uncopyable in total. Also disclosed are methods for establishing the authenticity of the holographic optical element.

Abstract: An improved method and apparatus for applying discrete area holograms or other optical devices directly onto documents or other substrates in a continuous process analogous to the operation of a printing press. The continuous process is carried out in a vacuum chamber in which at least two process steps are performed in sequence: the formation of a micro-grooved discrete resin area and a localized coating of it with a reflective or refractive material layer. The formation of the micro-grooved resin area can be accomplished by electron beam curing of the resin. The localized coating of the micro-grooved resin can be done by sputtering. One or more other steps, including pre-coating, post-coating and partial removal of the reflective or refractive layer, may also be carried out as part of the continuous process within the vacuum chamber.

Abstract: Charge-transfer materials are demonstrated to be useful for generating femtosecond holographic gratings. Using semiconducting polymers sensitized with varying concentrations of C60, absorption holographic gratings with diffraction efficiencies of 1.6% were recorded with individual ultrafast laser pulses; the diffraction efficiency and time decay of the gratings were measured using nondegenerate four-wave mixing. High quantum efficiency for electron transfer reduces the effects of early recombination which otherwise limits the density of excitations in pure polymers, and the metastability of the charge transfer enables tuning of the decay dynamics by controlling the concentration of acceptors in the mixture.

Abstract: There is described an image-recording medium and an image-reading method, which make it possible to improve reading accuracy of information by avoiding duplication of an optical variable image with the information. The image-recording medium includes a substrate, an image-receiving layer provided on the substrate and an optical variable layer provided on the substrate, wherein at least a part of the optical variable layer includes an optical variable image, and the optical variable image is formed in a manner such that the optical variable image, overlapping with an image recorded on the image-receiving layer, emerges in a first direction, while the optical variable image, overlapping with an image recorded on the image-receiving layer, does not emerge in a second direction.