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

The initial formation process of laser-induced plasma shock wave in air dur ing laser damage process has been studied experimentally with a well-design ed optical fiber sensor based on detecting beam deflection. The experimenta l results indicate that the formation of the laser-induced plasma shock wav e is the result of the overlap of vapor- and explosion-shock waves. The pla sma explosion shock wave, which generates behind the vapor shock wave but h as 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 di stance is about 3 mm when a 170 mJ laser at 1.06 mu m with 30 ns duration i rradiates an aluminum target in air. (C) 2000 Elsevier Science B.V. All rig hts reserved.