Reconstructing surface wave profiles from forward scattered pulses

Surface wave shape is determined by analyzing underwater reflected acoustic signals collected at multiple receivers in a wave tank. The acoustic signals are short 3-cycle pulses of nominal frequency 300 kHz. With the use of a forward scattering model based on the Kirchhoff approximation, an inverse processing algorithm determines surface wave shape by matching model and data acoustic waveforms. Reconstructed surfaces are accurate to a resolution of about a quarter-wavelength of the acoustic pulse only within Fresnel zones associated with each source and receiver pair. Within Fresnel zone regions, the acoustically derived surface is known with greater certainty than the surface profile as measured with a camera. Multiple receivers extend the region of surface reconstructed acoustically. The type of wave features to be investigated by this technique is scalable with acoustic transmission frequency. This versatility in implementation leads to the prospect of ocean application across a wide range of length scales.