Dynamics of laser-induced bubble collapse visualized by time-resolved optical shadowgraph

Following the first shock wave generation and the successive single bubble expansion after the breakdown by the Nd:YAG laser pulse with 35 mJ and 10 ns in distilled water, the strong secondary shock wave is generated at the instant of the bubble collapse. The single bubble expands up to 0.59 mm in radius, and then closes up by the pressure difference between the ambient liquid pressure at 10 kPa and the vapor pressure inside the bubble at 2 kPa. The maximum pressure up to 3 GPa is attained without the strong rebounding surface motion at about 93 ls after the laser shedding. We present time-resolved velocity measurements for estimating the extreme peak pressures of the first and second shock waves with the Rankine–Hugoniot analysis.