Propagation of partially coherent beams: turbulence-induced degradation

We show that, when a partially coherent beam propagates through an inhomogeneous medium such as atmospheric turbulence, the phase randomization that is induced is less effective in degrading the spatial coherence properties. By evaluating the final beam widths we report what is to our knowledge the first experimental demonstration that, on propagation through thermlly induced turbulence, a partially coherent beam is less affected than a spatially coherent beam.