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Proceedings Paper

Theory And Experiments On The Probability Density Of The Irradiance In Atmospheric Turbulence
Author(s): Ronald L. Phillips; Larry C. Andrews
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Paper Abstract

A universal math model has been developed for the irradiance fluctuations of an optical beam propagating through atmospheric turbulence. This new model was developed under the assumption that the field irradiance consists of two principal compcnents, each of which has an amplitude that is m distributed. By comparing this model with our own experimental data, as well as comparable data of other researchers, we found both qualitative and quantitative agreement over all ranges tested and strengths of turbulence. The statistics used in making these comparisons were the first five normalized moments of the been' intensity. Our own data were obtained over a very homogeneous environment with ranges from 180 m to 3 km. The data so obtained correspond to many conditions of turbulence, from weak where lognormal statistics are ordinarily valid, to superstrong turbulence where negative exponential statistics exist in the limit. In the weak turbulence regime we found that the data support the lognormal and universal model, which both predict essentially the same results. For conditions of moderate to strong turbulence, both the K distribution and the universal model match the data. However, for very strong turbulence prior to the limiting form of the negative exponential distribution, only our universal model matched the data. One of the interesting observations that we made in our data was that the normalized moments follow a looped path in the vicinity of their maximum values when they are plotted as functions of the normalized second moment. None of the standard theoretical models (i.e., lognormal, K, and negative exponential distributions) predict this looping effect since they are only two-parameter models whereas our universal model is a three-parameter model.

Paper Details

Date Published: 12 July 1983
PDF: 7 pages
Proc. SPIE 0410, Laser Beam Propagation in the Atmosphere, (12 July 1983); doi: 10.1117/12.935755
Show Author Affiliations
Ronald L. Phillips, University of Central Florida (United States)
Larry C. Andrews, University of Central Florida, (United States)

Published in SPIE Proceedings Vol. 0410:
Laser Beam Propagation in the Atmosphere
John Carl Leader, Editor(s)

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