A compact acoustic spanner to rotate macroscopic objects

Toninelli, E., Cox, M. A., Gibson, G. A. , Brown, S. D., Edgar, M., Forbes, A. and Padgett, M. (2019) A compact acoustic spanner to rotate macroscopic objects. Scientific Reports, 9, 6757. (doi: 10.1038/s41598-019-43046-4) (PMID:31043652) (PMCID:PMC6494813)

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Waves can carry both linear and angular momentum. When the wave is transverse (e.g. light), the angular momentum can be characterised by the “spin” angular momentum associated with circular polarisation, and the “orbital” angular momentum (OAM) arising from the phase cross-section of the beam. When the wave is longitudinal (e.g. sound) there is no polarization and hence no spin angular momentum. However, a suitably phase-structured sound beam can still carry OAM. Observing the transfer of OAM from sound to a macroscopic object provides an excellent opportunity to study the exchange of energy between waves and matter. In this paper we show how to build a compact free-space acoustic spanner based on a 3D-printed sound-guiding structure and common electronic components. We first characterise the sound fields by measuring both phase and amplitude maps, and then show a video of our free-space acoustic spanner in action, in which macroscopic objects spin in a circular motion and change direction of rotation according to the handedness of the OAM acoustic field.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Gibson, Dr Graham and Padgett, Professor Miles and Edgar, Dr Matthew and Toninelli, Mr Ermes
Authors: Toninelli, E., Cox, M. A., Gibson, G. A., Brown, S. D., Edgar, M., Forbes, A., and Padgett, M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Scientific Reports
Publisher:Nature Research
ISSN (Online):2045-2322
Published Online:01 May 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Scientific Reports 9:6757
Publisher Policy:Reproduced under a Creative Commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
636381EPSRC Centre for Doctoral Training in Sensing and MeasurementAndrew HarveyEngineering and Physical Sciences Research Council (EPSRC)EP/L016753/1SCHOOL OF PHYSICS & ASTRONOMY
6672319UK Quantum Technology Hub in Enhanced Quantum ImagingMiles PadgettEngineering and Physical Sciences Research Council (EPSRC)EP/M01326X/1S&E P&A - PHYSICS & ASTRONOMY
624501TWISTS - Twists & more: the complex shape of lightMiles PadgettEuropean Research Council (ERC)340507S&E P&A - PHYSICS & ASTRONOMY