3D Acoustic imagery generation by interferometric analysis of long baseline using Interferometric Real Aperture Sonar.

We are developing a technique for the systematical exploration of submarine hydrothermal ore deposits. In the Izu-Ogasawara Arc area these deposits are usually characterized by the existence of tower-like vents 2~20m high by 2~5m wide. We are using a set of Interferometric Real Aperture Sonars (InRAS) to generate 3D acoustic images of the areas surrounding the vents. We not only improved the resolution thanks to a long interferometric baseline, but we also efficietnly unwrapped the phase in this zone of large elevation differences by applying a two-stage approach (Branch Cut and SSPU methods). These improvements allow us to map the seafloor bathymetry around the submarine hydrothermal deposits. Since April 2014 we are conducting in-situ observations of both known and potential zones of hydrothermal deposits. Moreover, in November 2015 we will gather validation data in an experimental pool.