Semi-analytical model of acoustic-wave generation by a laser line pulse in an optically absorptive isotropic cylinder

TL;DR

This paper develops a semi-analytical model to predict the acoustic response in an optically absorptive isotropic cylinder caused by a laser line pulse, accounting for volumetric absorption effects.

Contribution

It introduces a novel semi-analytical approach with closed-form solutions for modeling laser-induced acoustic waves in cylinders with volumetric absorption.

Findings

Numerical simulations show different wave-peak shapes depending on optical penetration depth.

The model's results differ significantly from surface dipole source calculations when absorption is high.

The approach provides insights into the influence of optical absorption on acoustic waveforms.

Abstract

Semi-analytical model for calculating acoustic response to a line-focused laser pulse in an optically absorptive isotropic cylinder is proposed and implemented. It is assumed that the laser input is absorbed over the volume and thus creates a radially distributed thermoelastic source. Closed-form solution is obtained in the Fourier domain. Two inverse Fourier transforms in frequency and circumferential wave number yield the sought waveforms of acoustic response in the time-space domain. Numerical simulation is compared to the calculation based on a surface dipole source. The two signals have essentially different shapes of the wave-arrival peaks when the optical penetration is large enough.