Spatial correlation of random displacements of light beams in a turbulent atmosphere

The study is devoted to spatial correlation functions for random center-of-gravity shifts of two beams differing in terms of the diffraction size of the emitting aperture (frequency and initial beam radius) and the focus parameter. It is found that stronger turbulence leads to higher correlation between the two beams in the near field. Furthermore, the frequency divergence between the beams in the near field does not cause any noticeable decorrelation of random displacements. It is concluded that, in investigating problems related to random center-of-gravity shifts in a light beam, it is sufficient to consider a collimated beam.