Optical breakdown thresholds in liquid water and micron-size water droplets exposed to single laser pulses

Results are presented of experiments to determine the breakdown threshold of water exposed to laser pulses at wavelengths of 1.06 and 0.69 μ. The threshold power densities are (1.0±0.3)×10¹¹ and (3.8±1.0)×10¹⁰ W/cm², respectively. In order to estimate the optical breakdown thresholds inside micron-size water droplets, calculations are made of the maxima of the internal optical field distribution for incident radiation of wavelengths in the range 0.232–1.06 μ and droplet radii between 0.5 and 20 μ. These data are used to estimate the optical breakdown thresholds in water aerosols of different sizes and the results are compared with published experimental data.