SUBNANOSECOND SCHLIEREN PHOTOGRAPHY OF LASER-INDUCED GAS BREAKDOWN

Abstract
Second harmonic radiation from a mode‐locked neodymium:glass laser, providing a 400‐nsec‐long train of picosecond pulses, has been used as a light source for Schlieren photography of a laser‐induced spark. The beam from a ruby laser, Q‐switched by means of a Pockels cell, was focused in air to produce breakdown and synchronization of the two lasers was achieved by switching the Pockels cell with a spark gap illuminated by the mode‐locked pulse train.