Laser generation as a standard acoustic source in metals

Abstract

Absolute acoustic waveforms, generated by laser irradiation of aluminium and mild steel samples, have been detected at epicenter with a wide-band capacitance transducer. Comparison has been made with theoretical waveforms, utilizing theory for wave propagation within a plate and assuming certain source characteristics. Results have shown that laser generation is able to produce three types of standard acoustic source, namely a horizontal force dipole and a normal force monopole, each with step-function time dependence, and a normal force monopole with δ-function time dependence. Underlying generation mechanisms are discussed.