Experimental study of effects from two laser pulses

In order to investigate approximately the target-zone effects of repetitively pulsed laser beams, two CO2 lasers which were focused on the same spot were used in experiments with an adjustable temporal separation between their pulses. There are reported here studies at 1 atm of the effects of two laser pulses including high-speed photographic and interferometric observations of laser-produced plasmas, shocks, and target vapor; target damage evaluations; and investigations of impulse absorbed by the target. New effects were seen; the most significant of these was the dependence of several of these phenomena on the separation time. The interaction of the second laser pulse with the target is increased when it starts within a window 30 to 70 μsec after the start of the first laser pulse.