Saturation of fluctuations of the intensity of laser radiation at large distances in a turbulent atmosphere (Fraunhofer zone of transmitter)

An asymptotic theory is developed for fluctuations of the intensity of monochromatic radiation traveling in a turbulent medium with a power spectrum of fluctuations of the refractive index. The theory is based on an analysis of the solution of an equation for the fourth-order coherence function. The exact nature of the saturation of the relative fluctuations of the intensity of the radiation in the Fraunhofer zone of the transmitter is established. An estimate is obtained of the tendency of the correlation function of the intensity fluctuations to approach the asymptotic form. The results of the analysis are in good agreement with the experimental data.