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OPTICAL INSTRUMENTS AND COMPONENTS-NAMELY, TELESCOPES; LENSES AND LENS HOUSINGS; MIRRORS AND MIRROR CELLS; WINDOW AND WINDOW FRAMES; INTERFEROMETERS; AUTOCOLLIMATORS; TELEVISION PROJECTION EQUIPMENT AND OPTICAL AND PHOTOGRAPHIC SYSTEMS COMPRISED OF FILTERS, LIGHT SOURCES, MIRRORS AND WINDOWS FOR RECORDING WIND TUNNEL TESTS AND OTHER SUBJECTS NOT VISIBLE TO THE NAKED EYE