P2O-8 Single-Element PLZT Transducer for Wide-Bandwidth Imaging of Solid Materials
Document Type
Article
Publication Date
1-1-2006
Identifier/URL
40320416 (Pure); 78649337086 (QABO)
Abstract
Hard tissue medical imaging and other applications such as IC-chip package inspection present a series of challenges for ultrasound imaging, including small feature size, high acoustic clutter, and high acoustic impedances. We report here on the design and performance of a 19 MHz resonant thickness mode, ceramic PLZT (Lead Lanthanum Zirconate Titanate) transducer designed for high acoustic impedance (>10 MRayl) operation in the presence of acoustic clutter. One-dimensional transducer analysis using the Mason model is also presented and is used to predict the expected bandwidth and center operating frequency, and to compare PLZT and PZT-5H in our transducer design. The packaged transducer features a high impedance matching layer and a gallium-indium alloy couplant (17.4 MRayl), which together minimize surface clutter due to impedance mismatches. The transducer has a narrow 8deg -3 dB full beamwidth, a 30% instantaneous bandwidth, and a narrow pulse width (250 ns), resulting in high lateral (210 mum at 1.5 mm) and axial (350 mum in gallium-indium alloy) resolutions for detection of small features. The transducer has been integrated with a match filter receiver, and the system has been demonstrated to obtain a single pulse SNR of 45 dB in detecting a 25 mum thick crack in the highly cluttered environment of a human tooth. The Mason model predicts that the PLZT transducer has a 50% higher bandwidth than an equivalent PZT-5H transducer, in large part because of the increased electromechanical coupling coefficient (PLZT k ap 0.82, and PZT-5H kt ap 0.65). The tradeoff is ~30% lower acoustic-to-electric responsivity caused primarily by a larger dielectric constant. This is not so significant in the present applications (solid-state imaging), which tend to have clutter-limited environments. However, the improved bandwidth is very useful in improving range resolution and in gating out unwanted echoes, including those from the clutter.
Repository Citation
Singh, R. S.,
Culjat, M.,
Neurgaonkar, R. R.,
White, S. N.,
Grundfest, W. S.,
& Brown, E. R.
(2006). P2O-8 Single-Element PLZT Transducer for Wide-Bandwidth Imaging of Solid Materials. 2006 IEEE International Ultrasonics Symposium, IUS, 1926-1930.
https://corescholar.libraries.wright.edu/physics/1314
DOI
10.1109/ULTSYM.2006.487
