Finite element modeling of laser-based thermoelastic ultrasound generation

Shiwei Zhou; Paul Reynolds; Roland Krause; Takashi Buma; Matthew O'Donnell; John A. Hossack

doi:10.1117/12.479928

23 May 2003 Finite element modeling of laser-based thermoelastic ultrasound generation

Shiwei Zhou, Paul Reynolds, Roland Krause, Takashi Buma, Matthew O'Donnell, John A. Hossack

Proceedings Volume 5035, Medical Imaging 2003: Ultrasonic Imaging and Signal Processing; (2003) https://doi.org/10.1117/12.479928
Event: Medical Imaging 2003, 2003, San Diego, California, United States

Abstract

Using a scanned laser to generate ultrasound, via the thermoelastic effect, offers an alternative approach for realizing high density, high frequency ultrasound imaging arrays. The approach bypasses the complexity and intricacy required for forming conventional piezoelectric array elements and their associated electrical connections. Thus, it is particularly well suited to 2D arrays. In this paper, the devices considered comprise a carbon black loaded PDMS polymer layer on top of a glass or PDMS substrate. PZFlex Finite Element Analysis (FEA) was used to investigate the impact of a variety of design variables including: laser spot size, substrate material and thermoelastic coupling medium. Predicted single element angular response broadly matched responses obtained by experiment. Specifically, if a low acoustic loss glass substrate is used then measurable sidelobes occur at approximately 40 degrees. However, if the glass substrate is replaced by a PDMS material, then the traveling waves that give rise to sidelobes are no longer supported and a smooth single element angular response is obtained in both experiment and FEA simulation. FEA suggests that there are other modes in addition to the Rayleigh mode observed in the experiment. It is believed that these modes are more quickly damped in the experimental case. Therefore, while FEA provides a very versatile and valuable analysis tool, the accuracy of its predictions are contingent on accurate knowledge of device geometry and relevant material properties.

Citation Download Citation

Shiwei Zhou, Paul Reynolds, Roland Krause, Takashi Buma, Matthew O'Donnell, and John A. Hossack "Finite element modeling of laser-based thermoelastic ultrasound generation", Proc. SPIE 5035, Medical Imaging 2003: Ultrasonic Imaging and Signal Processing, (23 May 2003); https://doi.org/10.1117/12.479928

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