Laser Generation of Sound by Nonlinear Thermal Expansion
Final rept. 1 Dec 1991-30 Nov 1993
GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
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The two-year research effort was directed at understanding the laser generation of underwater sound at relatively low frequencies below 1 kHz by nonlinear expansion of the heated water. Three objectives were pursued 1 find an upper limit for the maximum efficiency achievable 2 solve the boundary value problem corresponding to the laser generation of sound by high-repetition rate pulsed lasers and 3 validate some of the predictions with some experiments. Results show that the efficiency of the optoacoustic conversion process remains very small for practical naval applications in the low frequency range below 1 kHz even when the nonlinearity of the thermal expansion mechanism is taken into account, even with high-repetition rate high-power pulsed lasers. More suitable applications would be those where short acoustic pulses less than a microsecond are desirable e.g., medical ultrasonics. Optoacoustics, Laser generated sound, Nonlinear thermal expansion.
- Lasers and Masers