Experimental demonstration of multiple pulse nonlinear optoacoustic signal generation and control

Generating underwater acoustic signals from a remote, aerial location by use of a high-energy pulsed infrared laser has been demonstrated. The laser beam is directed from the air and focused onto the water surface, where the optical energy was converted into a propagating acoustic wave. Sound pressu...

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Bibliographic Details
Published in:Applied optics (2004) 2005-01, Vol.44 (1), p.103-112
Main Authors: Blackmon, Fletcher, Antonelli, Lynn
Format: Article
Language:English
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Summary:Generating underwater acoustic signals from a remote, aerial location by use of a high-energy pulsed infrared laser has been demonstrated. The laser beam is directed from the air and focused onto the water surface, where the optical energy was converted into a propagating acoustic wave. Sound pressure levels of 185 dB re microPa (decibel re microPa) were consistently recorded under freshwater laboratory conditions at laser-pulse repetition rates of up to 1000 pulses/s. The nonlinear optoacoustic transmission concept is outlined, and the experimental results from investigation of the time-domain and frequency-domain characteristics of the generated underwater sound are provided. A high repetition rate, high-energy per pulse laser was used in this test under freshwater laboratory conditions. A means of deterministically controlling the spectrum of the underwater acoustic signal was investigated and demonstrated by varying the laser-pulse repetition rate.
ISSN:1559-128X
DOI:10.1364/AO.44.000103