Optoacoustic sources of sound

Laser generation of acoustic and shock waves in condensed media (liquids) is considered. It is shown that, depending on the volume density of the optical energy evolved in a liquid, the process of generation is mainly due to thermal expansion, surface evaporation, explosive boiling, or optical breakdown of the liquid. It is shown that liquids can be used as optoacoustic sources of sound. These have a number of advantages over the traditional acoustic radiators: remote action; absence of direct (in the traditional sense) contact between the body of a source and the medium which receives sound; ability to vary easily the geometric dimensions of an optoacoustic source and the frequency range; feasibility of constructing sound sources moving in a medium at an arbitrary subsonic, sonic, or supersonic velocity with complete elimination of flow of a medium around the body of a radiator. Optical generation of sound is in practice possible throughout the frequency range from infrasound to hypersound.