Observation of backscattering enhancement through atmospheric phase screens

We report an experimental investigation of enhanced backscattering (partial phase conjugation) for phase screens generated by a propane gas burner or a group of electric fan heaters. A 10-cm-diameter collimated laser beam is transmitted through the phase screen to a plane mirror and reflected back through the same screen. When the doubly scattered radiation is imaged at infinity, an intensity enhancement is observed in the backscattering direction. The backscattering peak can have a width close to the diffraction limit despite the large scattering that is due to the screens and to the relatively large astigmatism of the collimating mirror. The results are shown to be in good agreement with the theoretical predictions.