Ramasawmy, DR;
Martin, E;
Guggenheim, JA;
Zhang, EZ;
Beard, PC;
Treeby, BE;
Cox, BT;
(2019)
Analysis of the Directivity of Glass Etalon Fabry-Pérot Ultrasound Sensors.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
10.1109/TUFFC.2019.2921735.
(In press).
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Abstract
Planar glass-etalon Fabry-Pérot (FP) optical ultrasound sensors offer an alternative to piezoelectric sensors for measurements of high-intensity focused ultrasound (HIFU) fields and other metrological applications. In this work, a model of the frequency-dependent directional response of the Fabry-Pérot sensor was developed using the global matrix method, treating the sensor as a multilayered elastic structure. The model was validated against the experimentally measured directional response of an air-backed cover-slip Fabry-Pérot sensor with well-known material properties. Additionally, the model was compared with measurements of an all-hard-dielectric sensor suitable for HIFU measurements. The model was then used to calculate modal dispersion curves for both glass-etalon sensors, allowing the features of the directional response to be linked to specific wave phenomena. The features in the directivity of the air-backed cover-slip sensor are due to guided Lamb waves. Symmetric Lamb modes give rise to regions of high sensitivity whereas anti-symmetric modes cause regions of low sensitivity. For the all-hard-dielectric sensor, two features correspond to the water-substrate and water-spacer compressional and shear critical angles. A region of high sensitivity close to the shear critical angle is associated with a leaky-Rayleigh wave, which has a frequency-dependent phase speed. At higher frequencies, this feature is counteracted by a region of low sensitivity which occurs when there is no difference in the vertical displacement of the mirrors forming the Fabry-Pérot cavity. The model may be used to improve and optimize the design of Fabry-Pérot sensors, or could be used to assist with the accurate deconvolution of the directional response from array measurements in metrological and imaging applications.
| Type: | Article |
|---|---|
| Title: | Analysis of the Directivity of Glass Etalon Fabry-Pérot Ultrasound Sensors |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1109/TUFFC.2019.2921735 |
| Publisher version: | https://doi.org/10.1109/TUFFC.2019.2921735 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Mirrors, Acoustics, Acoustic measurements, Atmospheric modeling, Optical sensors, Sensor phenomena and characterization |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10076284 |
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