Abstract: A symbol reader is disclosed that uses a dynamic random access memory 24 as a detector element and a gradient refractive index material as the lens 14 to capture a symbol image. The rod shaped lens 14 passes through an opaque cover 26 and confronts the array of memory elements in the memory 24. The cover 26 is glued to a memory device package 28. The PN junctions of the random access memory 24 are activated by light reflected from a symbol 6 and appear as data when the random access memory 24 is read out. The light can be provided by light emitting diodes 34 positioned adjacent to the memory package 28 and in a hand held wand 46 that includes a light reflecting shield 48 in which the symbol is positioned for reading. The wand 46 is positioned over the symbol 6 and a read button 50 is depressed.

Abstract: The present invention is directed to a photocopy prevention film applied to a document to be protected that comprises either a volume holographic refraction grating or a surface holographic refraction grating. The refraction grating is bonded to a document and either causes normally scattered light to be focused toward the photoreceptors of a photocopy machine or causes light normally reflected toward the receptors to be scattered away from the receptors. The film is created by splitting a coherent laser beam into a reference beam and a target beam. The target beam reflects off of a special target and onto a photographic emulsion. The reference beam is also incident to the photographic emulsion. The beam reflected from the target and the reference beam create interference planes within the emulsion which can be developed to create differing refractive index planes within the emulsion or etched away to create a surface grating.

Abstract: A system for significantly reducing the laser energy striking an illuminated target such that the reflected target energy is reduced in intensity for seriously degrading the performance of energy seeking devices by introducing into a known laser path a gas or vapor material having laser absorbing and attenuating properties.