Projects per year
Abstract
Highly-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.
Original language | English |
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Pages (from-to) | 830-836 |
Number of pages | 7 |
Journal | ACS Photonics |
Volume | 9 |
Issue number | 3 |
Early online date | 16 Feb 2022 |
DOIs | |
Publication status | Published - 16 Mar 2022 |
Keywords
- Speckle
- Metrology
- Refractive index
- Integrating sphere
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Dive into the research topics of 'Measurement of variations in gas refractive index with 10-9 resolution using laser speckle'. Together they form a unique fingerprint.Projects
- 2 Finished
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Making the most of interference: Making the most of interference: new metrology application of laser speckle
Dholakia, K. (PI)
1/09/17 → 30/11/20
Project: Standard
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Resonant and shaped photonics for under: Resonant and shaped photonics for understanding the physical and biomedical world
Dholakia, K. (PI) & Gather, M. C. (CoI)
1/08/17 → 31/07/22
Project: Standard
Datasets
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Data underpinning "Measurement of variations in gas refractive index with 10^{-9} resolution using laser speckle"
Facchin, M. (Creator), Bruce, G. D. (Creator) & Dholakia, K. (Creator), University of St Andrews, 18 Feb 2022
DOI: 10.17630/f19b1d1f-5064-4575-bad5-a50d15ba2f34, https://doi.org/10.17630/sta/419
Dataset
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