ACOUSTIC DETECTION OF LASER-INDUCED MELTI NG OF METALS

A novel technique for determining the fusion threshold of metallic sam ples irradiated by high power laser pulses is presented The technique uses in situ detection of the acoustic waves produced by the laser pul se. A pulsed Nd:YAG laser was used, on brass samples, Particular atten tion has been paid to the measurement of the longitudinal and transver sal contributions to the acoustic wave. The obtained fluence threshold for fusion was verified by metallographic analysis and theoretical es timates.