Focal-length dependence of air breakdown by a 20-psec laser pulse

Abstract

The focal-length f and beam-diameter D dependence of threshold power for air breakdown has been investigated using focused ∼20-psec 1.06-μ laser pulses. Primary spherical aberration is shown to be very important in determining the threshold power when D/f is large. Diffusion-type losses and self-focusing played no part in the breakdown mechanism in the present work.