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Proceedings Paper

Finite element modeling of laser-based thermoelastic ultrasound generation
Author(s): Shiwei Zhou; Paul Reynolds; Roland Krause; Takashi Buma; Matthew O'Donnell; John A. Hossack
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Paper 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.

Paper Details

Date Published: 23 May 2003
PDF: 8 pages
Proc. SPIE 5035, Medical Imaging 2003: Ultrasonic Imaging and Signal Processing, (23 May 2003); doi: 10.1117/12.479928
Show Author Affiliations
Shiwei Zhou, Univ. of Virginia (United States)
Paul Reynolds, Weidlinger Associates Inc. (United States)
Roland Krause, Weidlinger Associates Inc. (United States)
Takashi Buma, Univ. of Michigan (United States)
Matthew O'Donnell, Univ. of Michigan (United States)
John A. Hossack, Univ. of Virginia (United States)

Published in SPIE Proceedings Vol. 5035:
Medical Imaging 2003: Ultrasonic Imaging and Signal Processing
William F. Walker; Michael F. Insana, Editor(s)

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