Acoustic vibrations of aluminum membranes upon laser excitation by the thermoelastic mechanism

A theoretical model of the formation of a photoacoustic signal from metal membranes by laser radiation is proposed taking into account the excitation of defective states in them. The theoretical results obtained are compared for aluminum membranes with a thickness of 197 $\mu$m in the frequency range from 20 Hz to 7 kHz when they are excited by laser radiation with a wavelength of 660 nm. It is shown that the proposed theoretical model ensures good agreement between the experimental and theoretical results for membrane vibrations with a purely surface absorption of laser radiation.