Initial formation process of laser-induced plasma shock wave in air

The initial formation process of laser-induced plasma shock wave in air during laser damage process has been studied experimentally with a well-designed optical fiber sensor based on detecting beam deflection. The experimental results indicate that the formation of the laser-induced plasma shock wave is the result of the overlap of vapor- and explosion-shock waves. The plasma explosion shock wave, which generates behind the vapor shock wave but has a higher speed, catches up with the vapor shock wave and overlaps it at a certain distance, giving the result of a strong shock wave in air. The distance is about 3 mm when a 170 mJ laser at 1.06 mu m with 30 ns duration irradiates an aluminum target in air. (C) 2000 Elsevier Science B.V. All rights reserved.