Experimental Study of Clear Atmospheric Turbulence Effects on Laser Beam Spreading in Free Space

In this work the effect of the atmospheric turbulence on a propagating laser beam broadening (or spreading) effect (Weff) is studied experimentally. An experimental set-up is designed to control and measure this effect under laboratory circumstances such as temperature, pressure and air speed. The refractive index structure parameter (Cn ) is measured under law and high speed (3.4 – 7.2 m/s) and its values (0.14*10 – 5.4*10 m 3 ⁄ ) respectively. A He-Ne laser beam size expanded from (0.64*10 m) to (0.7673*10 m) through a (1.6 m) path length.