Measurement of spatial stability of spark position in burst-mode breakdown with the Nd:YAG laser

Measurements to determine the precise position of the spark produced by optical breakdown in ocular media with a repetitive sequence of pulses from a Nd:YAG laser have been made. The results show that the location of the spark along the beam axis remains fixed within +/- 10 micrometers (the resolution of the experiment) for pulses with a time separation of 20 milliseconds, indicating that the surgical effects of a sequence of pulses can be cumulative.