Abstract: A photobleachable ink composition is provided. The photobleachable ink composition includes a photopolymerizable vehicle, which is convertible to solid phase upon exposure to radiation, a photochromic dye, an inorganic or organic metallic salt, and a sensitizer. The photochromic dye is chosen from the spiropyran family and the sensitizer is chosen to accelerate the photobleaching rate of the spiropyran complex. The photobleachable ink compositions may be used to render text and other graphics invisible when exposed to visible light. The photobleachable ink compositions may be prepared in a variety of colors, thus allowing for the creation of multi-colored patterns, with each color composition being bleachable independent of the other colored compositions.

Abstract: Security and identity cards including at least one hologram of the card, or part of the card, are disclosed. Holographic methods and materials to detect and prevent forgery in identity cards such as credit cards and access cards to security areas are disclosed. This invention employs microholograms that are recorded in very small areas on the card and that are not readily visible to the bearer. Special recording materials for high efficiency holograms are used to allow the confinement of the recording in an about 10 to about 100 micron size area. Apparatus for the recording and reading of the holograms are also disclosed.

Abstract: Materials, films, methods, and systems are described which relate to infrared imaging using a polymeric semiconductor compound having an infrared absorption band crosslinked with a spiroypran capable of producing a visible absorption band. These materials, films, methods, and systems are adapted to produce a visible image when exposed to infrared radiation during use.

Abstract: The adsorption of gas on a solid surface can produce considerable variation in the optical properties of the solid surface and eventually lead to the identification of the gas adsorbed. An optical waveguide having at least a portion of its length circumferentially coated with a transparent semiconductor material may function as a gas sensor. The sensor functions by exchanging electrons with a detectable gas brought in proximity with the coating material at reactive sites on the material's surface by the process of adsorption, thereby varying the refractive index of the transparent semiconductor material and altering the ellipticity of a light transmission through the optical waveguide. Substantially monochromatic polarized light is transmitted through the optical waveguide and then quantified by a light detector. A meter or other device connected to the light detector is adjusted to register a variation in the signal received by the light detector, indicating the presence of a detectable gas.

Abstract: Materials, films, methods, and systems are described which relate to infrared imaging using a polymeric semiconductor compound having an infrared absorption band crosslinked with a spiroypran capable of producing a visible absorption band. These materials, films, methods, and systems are adapted to produce a visible image when exposed to infrared radiation during use.

Abstract: An X-Ray sensitive composition including one or several photopolymerizable monomer or photocrosslinkable polymer systems and thermochromic substances which can be used in a dry X-Ray reproduction process. The process is based on the different dielectric constants and dielectric losses exhibited by a monomer and the corresponding polymer or a polymer and the crosslinked polymer and the reaction of certain thermochromic substances which exhibits a specific threshold temperature above which these substances change from a colorless form to a color stable form. The X-Ray sensitive element is exposed according to a pattern of X-Ray with spatial modulation providing an X-Ray image to form a latent image of polymerized or crosslinked zones and unpolymerized or non crosslinked zones.

Abstract: Rapid changes in absorption are made within the volume of a photosensitive transparent member that absorbs incident radiation to prevent the photocopy of a document, the original transparency being restored after discontinuance of the incident radiation.

Abstract: The invention relates to a photosensitive composition for direct dry negative color printing composition. The photosensitive composition comprises a binder containing a plurality of grains of a semiconductor material, each grain having adsorbed on its surface one of three different complexes of spiropyran with a metal salt, each complex being sensitive to a different wavelength of light, a cross-linkable polymer and free radical initiator. The composition and process enables photofinishing or printing from a negative.

Abstract: A system for public display of ultraviolet radiation levels wherein said radiation is collected and measured by one or several optical collectors or sensor assemblies at remote sensing stations. Optical fibers receive and then convey the radiation of the sun through a filter and onto a photovoltaic sensor, measuring the intensity of the ultraviolet radiation. An electrical signal proportional to the ultraviolet radiation is produced with the signal being amplified and either used directly as analog data or converted to a digital signal for the modulation of a radio transceiver. The signal is transmitted to a transceiver of a central data processing station, where it is processed. The processed signal is retransmitted to a receiver in which the processed signal carrier is demodulated and the signal fed to a display station providing the level of exposure to the public.

Abstract: A detection panel for acoustic holography with real time image reconstruction includes, a flat cell containing a mixture of nematic and cholesteric liquid crystals whose composition provides a refractive index which varies as a function of acoustic pressure. The cell has at least one acoustic window and at least one optical window.

Abstract: A method of preparing a thin film of a semiconductor material on a substrate, in which charged microdroplets of the semiconductor material or a constituent thereof are generated by electrohydrodynamic (EHD) extraction of the droplets from a meniscus forced at an elongate tip of a nozzle containing the material in a molten state, the EHD extraction occurring under the influcence of a high electric field produced by an extractor electrode adjacent the tip of the nozzle. The microdroplets are then accelerated away from the elongate tip of the nozzle to form a two-dimensional ribbon-like beam or blanket of the charged microdroplets. The two-dimensional beam is directed onto the trailing edge of a target carried on a moving substrate such that a film of the semiconductor material is formed on the substrate by deposition of the microdroplets on the trailing edge of the moving target.

Abstract: An infrared imaging system includes a film of dichroic liquid crystal coated on a membrane, first means for forming an infrared image on the membrane, second means for illuminating the membrane with visible light, and third means for deteching variations in elliptical polarization of the light after reflection from or transmission through the membrane to provide a visible image.

Abstract: Image formation is effected on the basis of the generation and erasing of color centers in a semiconducting oxide layer disposed between an electron injection layer and a hole injection layer. An image is formed by the trapping of electrons in color-center-promoting structural defects in the oxide layer when a potential difference is applied selectively across the oxide layer with the electron injection layer being negatively biased relative to the hole injection layer so as to enforce the dual injection of electrons and holes into the oxide layer. The image is erased by applying a potential difference of opposite polarity across the electron and hole injection layers.

Abstract: The invention relates to a photosensitive composition for direct positive color photography. The photosensitive composition comprises a binder containing a plurality of grains of a semiconductor material, each grain having adsorbed on its surface one of three different complexes of spiropyran with a metal salt, each complex being sensitive to a different wavelength of light, a cross-linkable polymer and a free radical initiator. The photographic composition provides a non-silver photographic process based on the photo-decomposition of the metal-spiropyran complex absorbed on the grains of semiconductor material.

Abstract: A device for the qualitative measurement of uv radiation received by the skin consists of a laminar strip for application to the skin, the strip including a photochromic material disposed intermediate the ends of the strip and a reference material also disposed intermediate the ends of the strip. The reference material is suitably a dye which matches closely the color of the photochromic material after exposure to a pre-determined quantity of uv radiation. The predetermined quantity of uv radiation corresponds to the maximum exposure tolerable by the particular skin type. The device enables one to visually assess exposure to uv radiation by a direct comparison of the color densities of the photochromic material and the reference material during exposure to sunlight.

Abstract: A photosensitive article comprises a substrate of a triacetate or other polyester film or paper coated with a layer of a photosensitive composition. The photosensitive composition includes at least one photodissociable choline compound sensitive to x-rays or radiation of shorter wave lengths, at least one image-forming compound capable of producing a dye by reaction with the dissociation products of the choline compound, a water soluble polymeric binder and a low melting point fatty acid salt for heat development. The photosensitive article can be used to produce an x-ray image by exposing the article image-wise to x-rays and heating the exposed article to develop the image.

Abstract: Monocrystalline layers of semiconductor materials are formed by epitaxial growth from thermal vapor deposition. Crystallinity and thickness of the monocrystalline layers are monitored and controlled during growth by ellipsometry. Low defect density thin film monocrystalline semiconductor devices with appropriate doping levels are formed. These are useful in photovoltaic solar cells of high efficiencies which can approach the theoretical limits.

Abstract: Monochromatic or polychromatic photographic images are directly developed on plain paper by a photodielectric selective sublimable dye transfer process.A photosensitive belt containing a photodielectric material and a binder is exposed to a light image and the exposed parts are then passed in contact with a plain paper together with a carrier of sublimable dye under pressure and the application of an electromagnetic field.Multicolor images are formed by exposing the original through three separation filters; for example, red, blue and green on three successive areas of the photosensitive belt and each exposed area passed in contact with a plain paper and three successive carriers of sublimable dyes of color corresponding to the separation filters.

Abstract: Permanent records of X rays or radiations of shorter wavelengths are formed on a film substrate by direct exposure to the radiation and heat development. The process is not sensitive to visible radiation and can therefore be carried on in daylight. An X ray photosensitive film containing a halogenated photodegradable polymer and an aryl dye promoter reacting to free radicals is exposed to an X ray image and then heated under conditions which allow the free radical generated by the photodegradation of the polymer to migrate and react with the aryl dye promoter to provide the imaging dye. The X ray photosensitive layer of the X ray photosensitive film or paper includes, in addition to the photodegradable polymer and the aryl dye promoter, a heat activable complexing agent and an organic binder. The process can be carried out using currently available X ray equipment with the advantage of handling the film in daylight and eliminating chemical development.

Abstract: An infrared imaging system includes a film of dichroic .[.liquid crystal.]. .Iadd.material .Iaddend.coated on a membrane, first means for forming an infrared image on the membrane, second means for illuminating the membrane with visible light, and third means for detecting variations in elliptical polarization of the light after reflection from or transmission through the membrane to provide a visible image.