Effect of beam waist on shock properties of laser-induced plasmas in air by the photoacoustic probe beam deflection method

A plasma induced by focusing in air at atmospheric pressure a 7 ns Nd:YAG l aser at 1.06 mum was studied by the photoacoustic probe beam deflection met hod. This technique is used for the first time to study shock waves from la ser induced plasmas in air. We have studied the effect of beam waist on ene rgy deposition. Our results indicate no appreciable effect on the shock wav e properties of laser-induced plasmas formed with different focal distance in the range from 2.5 cm to 20 cm at mus time scale. The technique was foun d to be versatile, economic and simple to implement giving essential inform ation for the shock wave evolution generated from plasmas produced by diffe rent methods.