Cross-correlation of phase fluctuations measured with a point source and an incoherent luminous object

A high degree of cross-correlation of radiation wavefront aberrations, measured from a point reference source and from an extended object (a system of several luminous points), has been for the first time revealed based on simultaneous measurements of phase fluctuations in optical waves propagating in a turbulent atmosphere. The experimental data are consistent with analytical calculations. The high degree of cross-correlation (above 0.97) of measured phase fluctuations proves that an extended incoherent source can be used as a reference source to ensure the operation of an adaptive focusing system.