Experimental study on laser generating acoustics in water has been performed using high power pulsed CO<sub>2</sub> laser.
The influences of the laser parameters on the characteristics of the sound pulse, such as amplitude, spectra and peak
frequency of the sound pulse, efficiency of the energy conversion were investigated in detail. The results show that the
amplitude of the sound pulse increases with the energy exposed to water surface. The efficiency of the optoacoustic
energy conversion η is in the range of 0.31×10<sup>-6</sup> to 1.65×10<sup>-6</sup>, and it increases with the laser energy. The spectra have two peaks which are 15.07 kHz and 53.40 kHz, and the sound energy is distributed mainly around 53.40 kHz. The shape of
the spectra is not variable with the laser energy, but the pressure of the peaks increases with deposited laser energy. The
exciting mechanism of laser acoustic in this experiment is the combination of thermoelastic and vaporization.