Scientists using laser light to generate underwater sound

WASHINGTON: The United States Naval Research Laboratory is working on a new technology that uses flashes of laser light to remotely create
underwater sound.

Researchers behind the project say that the new technology has the potential to expand and improve both Naval and commercial underwater acoustic applications, including undersea communications, navigation, and acoustic imaging.

Dr. Ted Jones, a physicist in the Plasma Physics Division, is leading a team of researchers from the Plasma Physics, Acoustics, and Marine Geosciences Divisions in developing this acoustic source.

The researchers used a 532 nm laser pulse for their study at the Salt Water Tank Facility.

They also used air bubblers and controlled water and air temperatures to create ocean-like conditions in the laboratory.

The research team could efficiently convert light into sound by concentrating the light sufficiently to ionize a small amount of water, which then absorbed laser energy and superheats.

They said that the result was a small explosion of steam that could generate a 220 decibel pulse of sound.

Given that the driving laser pulse has the ability to travel through both air and water, the researchers say that a compact laser on either an underwater or airborne platform can be used for remote acoustic generation.

They believe that their method would be a significant addition to traditional direct backscattering acoustic data.

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