Abstract: A reversible thermochromic optical limiter incorporates a thermochromic material, such as a spiropyran, that has molecules present in one of two states. At ambient temperatures the material is transparent to light. Incident laser radiation causes localized heating that turns the material to a colored state, effectively limiting transmission of the laser radiation. A laser protection device may comprise an optical focusing assembly, a nonlinear thermochromic medium, and a collimating assembly. A far field image having an intrusive laser beam, is focused through the thermochromic medium. The laser beam is focused to a small volume, causing localized heating, a large increase in optical density, and absorption of the laser light. The thermochromic medium has a fast response time over a broad wavelength band and returns to its transparent state when the laser beam subsides. The far field image is focused to a much larger volume so that it does not cause significant heating or change in optical density.

Abstract: Wireless integrated miniature sensing stations which can be organized into a communicating network allow sensitive detection and analysis of vibration, infrared radiation, sound, or other physical signals indicative of an intruder or condition to be monitored over a wide area. The sensing stations operate on low power and include a sensor or sensors, a digital signal processor, a microprocessor, and a wireless transceiver for communication. Network communication is facilitated by multiple relayed transmissions from station to station.

Abstract: A solid phase photosensitizer and method of use for photochemical generation of singlet oxygen. The sensitizer comprises one or more layers of an organic polycrystalline dye solid which absorbs radiant energy to release triplet excitons. Where multiple layers are employed, triplet state energies of the layers decrease toward the outer surface. A sub-monomolecular surface layer of organic molecules has a triplet state energy which is less than that of the adjacent dye-solid layer but greater than that of molecular oxygen. The sub-monomolecular layer thus functions to trap exciton energy at the sensitizer surface for reaction with gaseous molecular ground state oxygen directed thereover.