Extinction of CO2 Laser Radiation Under Adverse Weather Conditions

摘要

Results of extinction measurements of CO2 laser radiation under adverse weather are presented. Data on eight different lines has been collected using a phase lock receiver with an aperture three times the beam diameter. The system dynamic range of 72 dBs is limited by the use of pyroelectric detectors. It was found that during dense fog measurements, the extinction encountered exceeded the dynamic of range of the system more than 50% of the time. Reported measurements include extinction as a function of wavelength, time, and atmospheric particulates. Experimental measurements in fogs with extinction ranging from 1 to 72 dB/km, in rain with extinction ranging from 2 to 17 dB/km, and in light snow with extinction ranging from 3 to 14 dB/km are reported. Particle size data for over 150 fog size distributions have been collected. Measurements show that transmission losses in dense fog can easily be six orders of magnitude greater than losses in heavy rain. Results indicate that extinction of CO2 laser radiation in adverse weather is at best, a very weak function of wavelength.