Experimental study of laser beam propagation in turbulent atmosphere

摘要

Intensity of atmospheric turbulence may overly affect bit error rate for a ground-based laser wireless communication system, so it is necessary to measure of atmospheric turbulence intensity and fluctuation of image centroid while laser beam propagates in turbulent atmosphere. In this paper, an experiment system is set up based on theory of lighttransmission in turbulent atmosphere. In the system, a laser named Nd : YAG is used horizontally to emit a laser beamwith wavelength 1.06 μm on a platform at the height of 1.5 m. Three infrared CCD cameras are set at 200 m, 300 m(or600 m) and 1000 m far from laser, which are applied to receive laser facula images from Lambertian boards,respectively.A lot of laser facula images are collected within some serial days under different periods of time every day, and hundredsof image frames are gathered at a time by making use of this experiment device. Fluctuation of image centroid iscomputed with these image frames, and the structure constant of atmospheric refractive index (C_n~2 ) is also derived. Finally, a comparison is made between aforementioned C_n~2 and those derived by meteorology factors.