Measurements of the fourth moment of the optical field using the coherence enhancement phenomenon

摘要

The results of laboratory measurements of the spatial distribution of the four-point coherence function (fourth moment) of a spherical wave are presented. Using a special interferometric system we have illuminated a rough surface through turbulence with a coherent point source and observed the interference pattern in the source plane. Experimental data demonstrate the existence of a region where coherence enhancement after backscattering through turbulence may be observed. The time averaged intensity distribution in this region is described by the fourth moment of a spherical wave propagated through turbulence. This study demonstrates that the measurements of the fourth moment may also be applicable for estimating of the inner scale of the turbulence.