Spatially offset optical coherence tomography: leveraging multiple scattering for high-contrast imaging at depth in turbid media

Gavrielle Untracht, Mingzhou Chen, Philip Wijesinghe, Josep Mas, Harold Yura, Dominik Marti, Peter Andersen*, Kishan Dholakia*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

The penetration depth of optical coherence tomography (OCT) reaches well beyond conventional microscopy; however, signal reduction with depth leads to rapid degradation of the signal below the noise level. The pursuit of imaging at depth has been largely approached by extinguishing multiple scattering. However, in OCT, multiple scattering substantially contributes to image formation at depth. Here, we investigate the role of multiple scattering in OCT image contrast and postulate that, in OCT, multiple scattering can enhance image contrast at depth. We introduce an original geometry that completely decouples the incident and collection fields by introducing a spatial offset between them, leading to preferential collection of multiply scattered light. A wave optics–based theoretical framework supports our experimentally demonstrated improvement in contrast. The effective signal attenuation can be reduced by more than 24 decibels. Notably, a ninefold enhancement in image contrast at depth is observed in scattering biological samples. This geometry enables a powerful capacity to dynamically tune for contrast at depth.
Original languageEnglish
Number of pages12
JournalScience Advances
Volume9
Issue number27
Early online date7 Jul 2023
DOIs
Publication statusPublished - 7 Jul 2023

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