Temporal deconvolution of laser-generated longitudinal acoustic waves for optical characterization and precise longitudinal acoustic velocity evaluation

摘要: The laser thermoelastic generation of ultrasound is a promising technique with many potential applications, but it also complicated process physical phenomena involved. Contrary to conventional piezoelectric transducer generation, which surface phenomenon, can activate acoustic sources within the material by optical penetration excitation wavelength, resulting in asynchronous wave arrivals at given point. More generally, ideal case nondispersive isotropic material, laser-ultrasonics displacement signals result from temporal convolutions between penetration, pulse duration, and spot extension effects. In this paper, deconvolution presented that extracts duration contribution experimental signals. This scheme applied one-dimensional experiments, spread over sufficiently large area on front side sample, allows measurement absorption coefficient wavelength precise evaluation its longitudinal velocity.