INNER-SCALE EFFECT ON IRRADIANCE VARIANCE MEASURED FOR WEAK-TO-STRONG ATMOSPHERIC SCINTILLATION

Experimental results are described of measurements of irradiance fluctuations of laser radiation through atmospheric turbulence. Simultaneous measurements of irradiance fluctuations, inner scale, and structure parameter were made in conditions of homogeneous turbulence during a number of summer days, from very early in the morning, before sunrise, until approximately noon. During the measurements the turbulence strength varied continuously, spanning very low as well as intermediate and very high levels. We used the data collected in selected intervals, during which turbulence was stationary, to obtain plots of irradiance variance versus the structure parameter for fixed ranges of values of the inner scale. The results clearly show the effect of the inner scale. For a given value of the structure parameter larger inner scales result in larger values of irradiance variance in the regime of strong scintillation.