LASER BEAM PROPAGATION THROUGH A TURBULENT ATMOSPHERE

Abstract

The laser as a coimunication source provides high information capacity and has high spatial and to po. z'al coherence and senocha sc .ty M As for as coherence is concerned it Is destroyed due to signal distortion produced by atmospheric turbulence. The stat.. d art of laser beam propagation through the atmosphere re has been reviewed critically, Constituents of the atmosphere and turbulence play an adverse role on laser been propagating through atmos. phare, The various topics sieved include s 10 A mathematical description of the turbulent s sph.re,r 110 Limitations for an optical channel, due to (a) attenuation of the beam by precipitation td gat and (b) physical effects a i.e. beam steering. Crier spreading, image blurring, intensity $Cintill$tiono frequency, phase and polarization fluctuations. Lit, The effect of random beam scanning on the capacity of an optical channel,* The principal. Interest of the present dissertation constitutes the study of the ortical strength of turbulence of the atmosphere at various altitudes, with the help of derived expressions th. variation of the refractive inO* stzuctua r constant + With height is calculated sad plotted* The log.aaplitude covtrianc• is also evaluated for various tie. delays and various covariance lengths. The results indicate * technique for the remote probing of the a here, An irnmedtat. need for the neauureents of strength of turbulence of the at sphere is also suggested. 00