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dc.contributor.authorFacchin, Morgan
dc.contributor.authorBruce, Graham David
dc.contributor.authorDholakia, Kishan
dc.identifier.citationFacchin , M , Bruce , G D & Dholakia , K 2022 , ' Measurement of variations in gas refractive index with 10 -9 resolution using laser speckle ' , ACS Photonics , vol. 9 , no. 3 , pp. 830-836 .
dc.identifier.otherPURE: 276551241
dc.identifier.otherPURE UUID: 2e4a7ce0-25a8-4830-a786-aca899e3295e
dc.identifier.otherORCID: /0000-0003-3403-0614/work/108508580
dc.identifier.otherWOS: 000776221600014
dc.identifier.otherScopus: 85125412383
dc.descriptionFunding: This work was supported by funding from the Leverhulme Trust (RPG-2017-197) and the UK Engineering and Physical Sciences Research Council (EP/P030017/1).en
dc.description.abstractHighly-resolved determination of refractive index is vital in fields ranging from biosensing through to laser range-finding. Laser speckle is known to be a sensitive probe of the properties of the light and the environment, but to date speckle-based refractive index measurements have been restricted to 10^-6 resolution. In this work we identify a strategy to optimise the sensitivity of speckle to refractive index changes, namely by maximising the width of the distribution of optical path lengths in the medium. We show that this can be realised experimentally by encapsulating the medium of interest within an integrating sphere. We demonstrate that variations of the refractive index of air as small as 4.5x10-9 can be resolved with an uncertainty of 7x10-10. This is an improvement of three orders of magnitude when compared to previous speckle-based methods.
dc.relation.ispartofACS Photonicsen
dc.rightsCopyright © 2022 American Chemical Society. Open Access article licensed under Creative Commons Attribution CC-BY 4.0.en
dc.subjectRefractive indexen
dc.subjectIntegrating sphereen
dc.subjectQC Physicsen
dc.subjectQD Chemistryen
dc.titleMeasurement of variations in gas refractive index with 10-9 resolution using laser speckleen
dc.typeJournal articleen
dc.contributor.sponsorThe Leverhulme Trusten
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. Centre for Biophotonicsen
dc.contributor.institutionUniversity of St Andrews. Sir James Mackenzie Institute for Early Diagnosisen
dc.contributor.institutionUniversity of St Andrews. Biomedical Sciences Research Complexen
dc.description.statusPeer revieweden

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