The experimental criteria for judging the maximum bubble radius of laser-iduced bubble in different ambient pressures

The radius of laser-induced bubble in different ambient pressures is measured by a fiber-optic diagnostic technique based on laser-beam deflection probe (BDP). The experimental criteria for judging the maximum bubble radius are modified. The estimation value of the maximum radius is defined as the arithmetic mean of the value of the detecting distances at which the characteristic waveform signals appear. The estimation of root mean square error is also obtained. The maximum value and the expanding of bubble radius are obtained by means of the BDP signals and the modified criteria. The experimental results show that the less experiment is needed for obtaining the maximum radius, the maximum radius decreases with the ambient pressure increases. These results are useful to the investigations on cavitations and the measuring of bubble.