Acoustic cavitation events during microsecond irradiation of aqueous solutions

The acoustic boundary conditions at the site of laser irradiation affects the onset of cavitation when stress- confined laser pulses are used. This study reports the thresholds for cavitation when the laser pulse length exceeds the stress confinement time by a factor of eight. The cavitation threshold was defined as the loss of an acoustic signal from the collapse of the cavitation bubble in room temperature dye solutions. The threshold temperature increase for cavitation at a free surface was 13 plus or minus 3 degrees Celsius, at the tip of a 200 micrometer fiber in an aqueous solution was 17 plus or minus 2 degrees Celsius, and at the interface of two acoustically matched boundary materials was 80 plus or minus 20 degrees Celsius.