Hardwick, James;
(2024)
Reconfigurable Acoustic Metasurfaces as
Reflective Spatial Sound Modulators.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
In this thesis, I showcase the effectiveness of acoustic metasurface (AM) based spatial sound modulators (SSMs) for reconfigurable, cost-effective manipulation of acoustic pressure distributions. SSMs are crucial for various applications, including 3D interactive displays and medical ultrasound imaging. While state-of-the-art SSMs like Phased Array Transducers (PATs) are powerful and effective modulators, they face challenges related to cost, electronic complexity, and artefacts in their output sound fields. I address these challenges by demonstrating the effectiveness of reflective AM-based SSMs. I exploit their various advantages such as simple unit cells, clear obverse faces for inclusion of actuation mechanisms, and avoidance of significant transmission losses, while mitigating their limitations through optimised design and fabrication pipelines. I begin with a study of manually reconfigurable, reflective SSM devices and demonstrate their ability to generate precise pressure landscapes, outperforming PAT techniques in terms of acoustic holographic image quality and energy distribution. Next, I outline approaches for optimisation of electronically reconfigurable SSM designs by reducing the number of actuators needed to generate sets of target acoustic pressure distributions. I present a comprehensive design pipeline for optimised SSMs comprised of segmented elements. This pipeline encompasses algorithmic design as well as physical fabrication techniques, which I validate through the creation of prototype devices. Finally, I outline several applications and discuss the practical implementation of my methods in developing reconfigurable AM-based SSM devices. This thesis presents a novel method for constructing SSMs using acoustic metasurfaces which emphasises cost effective design and fabrication without compromising on generation of high-quality acoustic pressure distributions. The methods I present open the door to a wide application space, improve the affordability, flexibility, and accessibility of SSM devices, and invite the inception of future SSMs of arbitrary sizes, usages, and actuation approaches.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Reconfigurable Acoustic Metasurfaces as Reflective Spatial Sound Modulators |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| Keywords: | Acoustic Metamaterials, Spatial Sound Modulators, Acoustic Holography, Clustering Algorithms |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10196274 |
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