Acousto‐optic interactions at a surface perturbed by acoustic and gravity waves

We studied the acousto‐optic interaction at a water surface perturbed by an underwater sound source. Using a coherent optical detection technique, we measured the power spectra of the scattered light. Filtering of the power spectra allowed us to detect the sound‐induced perturbations of the surface in the presence of surface waves, even though the amplitude of the waves was much larger than the acoustic perturbations of the surface. The theory of scattering by a surface perturbed by sound and by surface waves is developed and that theory is compared with the experimental results.