WAVE BEAM TREMBLE WITHIN AN ABSORBING RANDOM MEDIUM WITH LENS PROPERTIES

The present paper investigates the joint influence of fluctuations of the complex dielectric constant, epsilon, of a medium and its lens pro perties on random displacements of a radiation beam. Based on a non-tr aditional approach, an expression is obtained for the variance of the beam energy centre tremble, sigma(rho)(2), taking into account the con tribution of fluctuations of the real and imaginary parts of epsilon, as well as that of their correlations. It was shown that the influence of fluctuations of the imaginary part of epsilon is particularly pron ounced in the initial section of the path, as well as in paths of grea t length. Due to regular refraction, a considerable enhancement of the dependence of sigma(rho)(2) upon the path length occurs, with the gre atest contribution being made by fluctuations of the imaginary part of the dielectric constant. A positive correlation of random changes of the real and imaginary parts of epsilon was shown to result in a parti al compensation of the beam tremble.