Characteristics of a laser-generated acoustic source in solids

Aindow, Alan Michael

Abstract

This thesis describes a combined experimental and theoretical study of acoustic generation in solids by laser irradiation.
Two basic types of laser acoustic source are identified, namely, the thermoelastic and the ablation source. Both sources are described in detail in metals and to a lesser extent in non-metals. The emphasis is on generation in the ultrasonic region. The thermoelastic source operates at comparatively low incident laser intensities, typically < 3 x 1012 Wm-2, and is driven by dynamic thermal expansion due to transient surface heating. The second source takes over at higher intensities, and results from the effects of surface vaporisation and plasma formation. The resultant acoustic waveforms (bulk and surface) have been studied over a wide range of experimental conditions using a pulsed Nd:YAG laser and both resonant and broad bandwidth detection probes. The surface forces produced under these various conditions are discussed in detail,and using acoustic theory, are related to the acoustic waveforms.
In a wider context, thermoelastic generation is related to the photoacoustic effect in a generalised ID model.

Citation

Aindow, A. M. (1986). Characteristics of a laser-generated acoustic source in solids. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4421475

• Thesis Type: Thesis
• Deposit Date: Oct 20, 2023
• Publicly Available Date: Oct 20, 2023
• Keywords: Applied physics
• Public URL: https://hull-repository.worktribe.com/output/4421475
• Additional Information: Department of Applied Physics; University of Hull; ; Ethos ID: uk.bl.ethos.380793
• Award Date: Nov 1, 1986