Dynamic response of metals and alloys to laser induced shock waves

Abstract

We present the measurements on the propagation characteristics of the laser generated acoustics shock waves and the vibrations inside material targets from laser-metal interaction in real time. Laser pulses (7 ns) from second harmonic of a Nd: YAG laser (532 nm) were used to launch compression waves inside the solid samples. The acoustic measurements were carried out using a calibrated microphone, while the vibrations induced within the material before getting converted into ASW in the atmosphere were measured using vibration transducers (piezoelectric accelerometer). The arrival time of the vibration transducer was used to measure the particle velocity within the material that increased with increasing laser energy. The measurement of the arrival time of the ASW as a function of the microphone distance from the source of explosion was carried out. The shock velocity with respect to distance from the source of explosion followed an exponential decay. The arrival time of the ASWs was found to be increasing with the distance. The shock arrival time with respect to incident laser energy showed an exponential decay where as the shock velocity was found to be linearly increasing with the incident laser energy. Overall, acoustic energy has increased with increasing density of the material. © 2012 SPIE.