Near-surface excitation and spectrum analysis of photoacoustic waves and image reconstruction

Shazan Ahmad Bhat; Swaroop Ganguly; Dipankar Saha

doi:10.1117/12.2692894

12 March 2024 Near-surface excitation and spectrum analysis of photoacoustic waves and image reconstruction

Shazan Ahmad Bhat, Swaroop Ganguly, Dipankar Saha

Proceedings Volume 12842, Photons Plus Ultrasound: Imaging and Sensing 2024; 128420O (2024) https://doi.org/10.1117/12.2692894
Event: SPIE BiOS, 2024, San Francisco, California, United States

Conference Poster

Abstract

Laser parameters deftly govern the conversion of electromagnetic pulse energy into acoustic waves. Despite advancements in experimental techniques and pulsed lasers, an accurate theoretical model is still lacking for spectrum analysis of the acoustic waves generated upon irradiation of laser pulses. Here, we have studied the behavior of Photoacoustic (PA) waves in the medium upon laser pulse irradiation with varying pulse widths and repetition rates and observe the impact on frequency characteristics by variation of absorption coefficient via imaginary part of the refractive index at constant wavelength followed by wavelength variation, thereby changing the absorption coefficient of the medium following its wavelength dependence. An acoustic wave scatterer is placed inside the medium and reconstructed using Synthetic Aperture Focusing Technique (SAFT). Upon reflection from scatterers, these resultant acoustic waves return to the surface at distinct time intervals and are detected via transducers or optical techniques. In this study, a time-domain Finite Element Method (FEM) simulation has been performed for generation, propagation, and detection of acoustic waves near the medium-air interface. The framework consists of self-consistent solution of the light diffusion equation, heat equation, Poila-Kirchoff stress equation, and pressure-wave equation. The detected signals near the surface of the medium are imported to MATLAB to obtain high-resolution images using SAFT.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Shazan Ahmad Bhat, Swaroop Ganguly, and Dipankar Saha "Near-surface excitation and spectrum analysis of photoacoustic waves and image reconstruction", Proc. SPIE 12842, Photons Plus Ultrasound: Imaging and Sensing 2024, 128420O (12 March 2024); https://doi.org/10.1117/12.2692894

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