Phase fluctuations of a multimode laser field in a turbulent atmosphere

A method is proposed for calculating phase fluctuations of multimode radiation in a randomly inhomogeneous medium by utilizing the concept of mean diffracted rays. A study is made of the influence of the initial coherence of the source field, the diffraction conditions at the radiating aperture, and the turbulent propagation conditions on the spatial phase structure function and the variance of the jitter of the source image. The results of the theory are compared with experimental data obtained in a real atmosphere.