A SURVEY OF ULTRAVIOLET COMMUNICATION SYSTEMS

This report contains a review of ultraviolet communication systems developed during the period 1926 to 1950. Sources of radiation used in these systems were carbon arcs, low pressure mercury arc lamps, gallium lamps, and nitrogen filled tubes. Receivers were, in most cases, multiplier phototubes; however a fluorescent telescope and metascopes were also used. Several of these systems had most of the radiation concentrated in the 2536A mercury line, a region where the atmospheric attenuation is very high. Others attempted only to limit the radiation to the invisible portion of the ultraviolet spectrum, i. e., below about 3500A. None of the systems were reported to have worked well during daylight operations. Data on the transmission of the atmosphere in the ultraviolet region and on filters, sources, and receivers are included. A communication system for directional or beacon operation during daylight or night time with at least a 10-mile range on an average day is considered feasible. The source would use a mercuryxenon arc lamp or a nitrogen filled tube. Improved signal-to-noise ratio will be obtained if the source is pulsed. The receiver would use a multiplier phototube with an interference type filter.