Parametric sources—From theory to commercial products

The interest for underwater application of nonlinear acoustic began in the late 1950s and early 1960s with Westervelts idea of using nonlinear effects to generate low frequency sound beams with high directivity; the parametric source. This idea got a lot of attention during the 1960s and 1970s from various scientific institutions. An early experiment with a parametric source was performed by ELAB at the University of Trondheim and Simrad in 1977. In the early 1980s, Bentech started the design of a towed, combined mapping system for bathymetry and detection of buried pipelines. The idea was to do detection while moving along the pipeline, which required a sub-bottom profiler with steerable beams with high directivity. Due to limited space for transducer, a parametric source was the logical choice. A prototype of the parametric sub-bottom profiler was finished in the late 1980s. Following the prototype, the system was commercialized and additional versions were developed covering applications from shallow w...