Hartland S. Snyder

Principles of Optical Communication Systems*General Properties of Non-Image Forming Projectors and Receivers

The factors are discussed which determine the range of an optical communication system, such as: atmospheric transmission; source area, flux, brightness, modulation, and audio pass band; transmitter and receiver focal lengths, areas, and beam widths; and detector cell noise and ±14 area. Detector cell signal-to-noise ratio varies inversely as the square root of cell area in the ideal case. For non-image-forming systems, the Abbe sine condition is replaced by a useful rule of constancy of area times solid angle. A wide-angle system is a short-range system.A general equation is given relating the range to these factors; it leads to a simple nomograph for estimating performance of a system. From laboratory measurements on components, the field range of a system may be predicted to an accuracy of ±14 mile if the atmospheric transmission is known.