Laser-Ultrasonics and Imaging through Metal Layers

Alessandro Antoncecchi

Research output: PhD ThesisPhD-Thesis - Research and graduation internal

366 Downloads (Pure)

Abstract

The combination of light and sound can be used to detect and image structures under opaque layers. In this thesis, we present the result of our studies on imaging and metrology through metal layers using laser-induced ultrasound. Ultrafast lasers can generate acoustic waves at high frequencies through the thermoelastic effect. The absorption of the energy of the laser pulse is followed by an increase in temperature and a subsequent expansion of the metal lattice. Stress is generated in the lattice, launching an acoustic wave inside the metal layer. The acoustic waves travel through the layers that compose the samples, reflecting off different interfaces and returning to the surface. When the reflected acoustic pulse comes back to the surface, it causes a change in the optical constants, as well as a physical displacement of the surface. A second laser pulse can be used to detect these changes in optical properties of the surface caused by the acoustic wave. In our research, we performed pump-probe experiments to study the generation, propagation and detection of ultrasound waves in metal layers.
Original languageEnglish
QualificationPhD
Awarding Institution
  • Vrije Universiteit Amsterdam
Supervisors/Advisors
  • Witte, Stefan, Supervisor
  • Eikema, Kjeld, Supervisor
Award date30 Mar 2022
Print ISBNs9789492323613
Electronic ISBNs9789492323613
Publication statusPublished - 30 Mar 2022

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