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Proceedings Paper

Double-pass fade statistics of a laser beam under moderate to strong atmospheric turbulence
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Paper Abstract

For a Gaussian-beam wave incident on a point target, we use a recently developed scintillation theory and the gamma- gamma probability density function to calculate the fade statistics of the echo wave as a function of threshold below the mean irradiance. We also compare the results with experimental data collected by a coherent receiver array over a 1-km propagation path to the target using from one to eight apertures of the array. The propagation channel was determined to be a bistatic configuration for the lidar system. Values of inner scale and refractive index structure constant were simultaneously measured during the experiment by use of a scintillometer instrument. The scintillation theory employed in this work utilizes a spatial filter function that results from adapting a modulation scheme in which it is assumed that the intensity of the propagating laser beam is a product of two quantities: one related to the large scale turbulent eddies of the atmosphere and the other related to the small scale eddies. The theoretical curves arising from this analysis provide a good fit with experimental data up to four active apertures of the array, but deviate somewhat from the data for a greater number of apertures.

Paper Details

Date Published: 20 June 2001
PDF: 8 pages
Proc. SPIE 4272, Free-Space Laser Communication Technologies XIII, (20 June 2001); doi: 10.1117/12.430787
Show Author Affiliations
Ammar Al-Habash, Terabeam (United States)
Larry C. Andrews, CREOL/Univ. of Central Florida (United States)
Ronald L. Phillips, Univ. of Central Florida (United States)


Published in SPIE Proceedings Vol. 4272:
Free-Space Laser Communication Technologies XIII
G. Stephen Mecherle, Editor(s)

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