Strasser, F., Barnett, S. M. , Ritsch-Marte, M. and Thalhammer, G. (2022) Generally applicable holographic torque measurement for optically trapped particles. Physical Review Letters, 128(21), 213604. (doi: 10.1103/PhysRevLett.128.213604)
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Abstract
We present a method to measure the optical torque applied to particles of arbitrary shape such as micrometer-sized micro-organisms or cells held in an optical trap, inferred from the change of angular momentum of light induced by the particle. All torque components can be determined from a single interference pattern recorded by a camera in the back focal plane of a high-NA condenser lens provided that most of the scattered light is collected. We derive explicit expressions mapping the measured complex field in this plane to the torque components. The required phase is retrieved by an iterative algorithm, using the known position of the optical traps as constraints. The torque pertaining to individual particles is accessible, as well as separate spin or orbital parts of the total torque.
| Item Type: | Articles |
|---|---|
| Additional Information: | This work was supported by the Austrian Science Fund (FWF) (P29936-N36) and by the Royal Society (RP 150122). |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Barnett, Professor Stephen |
| Authors: | Strasser, F., Barnett, S. M., Ritsch-Marte, M., and Thalhammer, G. |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | Physical Review Letters |
| Publisher: | American Physical Society |
| ISSN: | 0031-9007 |
| ISSN (Online): | 1079-7114 |
| Published Online: | 25 May 2022 |
| Copyright Holders: | Copyright © 2022 American Physical Society |
| First Published: | First published in Physical Review Letters 128(21): 213604 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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