Aperture averaging of optical scintillations in the atmosphere: experimental results

The aperture averaging factor is a measurement of the ratio of the atmospheric turbulence-induced irradiance scintillations incident on a receiver with diameter D to those incident on a point receiver. Characterizing the amount of aperture averaging in an optical receiver system will allow for tradeoffs to be made between the error performance of an optical receiver and the size and weight of the receiver. Aperture averaging theory has been extensively developed for optical wave propagation in weak turbulence conditions. A lack of experimental aperture averaging data over a variety of turbulence strengths, test range characteristics, and aperture diameters restricts progress in the development of useable propagation models. Experimental measurements of the aperture averaging factor collected over a test range at the University of Maryland are presented here. The impact of this data on the design of free space optical communication receivers will be discussed.