Changes in the width of the coherence for partially coherent flat topped beams with a circular aperture in turbulent atmosphere

We study the change in the degree of coherence of partially coherent flat topped (PCFT) beam limited by a circular aperture propagating through atmospheric turbulence. It is shown analytically that the degree of coherence for mentioned beam reaches its maximum value after the beam propagates a specific distance. In this paper we define the width of the coherence and it is shown analytically that the effective width of the degree of coherence also has a maximum value at the specific distance. This phenomenon is dependent on the used aperture radius size. The results are illustrated by numerical curves.