  A single bubble in water is excited by a standing ultrasound wave. At high
intensity the bubble starts to emit light. Together with the emitted light
pulse, a shock wave is generated in the liquid at collapse time. The
time-dependent velocity of the outward-travelling shock is measured with an
imaging technique. The pressure in the shock and in the bubble is shown to have
a lower limit of 5500 bars. Visualization of the shock and the bubble at
different phases of the acoustic cycle reveals previously unobserved dynamics
during stable and unstable sonoluminescence.
