Optical precipitation gauge which detects scintillations produced by particle movement in the light beam

摘要

A precipitation gauge is provided for remotely detecting precipitation and for measuring the rate of precipitation in an open environment, such as an aircraft landing field. The system employs an optical transmitter and receiver, wherein particles of precipitation passing through a light beam from the transmitter cause scintillations at the receiver. The spatial separation between the light transmitter and receiver is quite small, typically substantially less than one meter. The small separation between the transmitter and the receiver is made possible by the use of a partially coherent light beam, in place of a conventional laser beam. The transmitter and receiver are spaced apart a distance of approximately 0.6 meters. The product of one half of the angle of incoherency multiplied by the spatial separation between the transmitter and receiver is preferably about 1.5 millimeters. An output from automatic gain control circuitry is processed by signal processing circuitry and appears as a direct current voltage level which could be either proportional to the rate of precipitation or to the logrithmic rate of precipitation. The precipitation gauge is quite accurate, ranging from extremely light to extremely heavy precipitation rates.