Reflection of laser-generated shocks from a hard surface

Laser-generated acoustic shock waves were measured at several locations in a free-field environment and at the corresponding locations above the acoustically hard surface of a 6-mm-hick glass sheet. The laser-generated shock waves had peak sound pressure levels of more than 170 dB at a distance of 5 cm. Although a slight reduction was observed in the peak sound pressures in certain directions at close range, the sparks approximated point sources of sound. The mean peak sound pressure levels were found to be increased by more than 3 dB at source and receiver heights of 8 and 10 mm above the acoustically hard surface and with spark to-microphone distances of up to 25 cm.