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Open AccessArticle

A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

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Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences (IPaQS), Heriot-Watt University, Edinburgh EH14 4AS, UK
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Renishaw Plc, New Mills, Wotton-under-Edge GL12 8JR, UK
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Renishaw Plc, Edinburgh EH14 4AP, UK
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EPSRC IRC Hub, MRC Centre for Inflammation Research, Queen’s Medical Research Institute (QMRI), University of Edinburgh, Edinburgh EH16 4TJ, UK
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(2), 185; https://doi.org/10.3390/mi11020185
Received: 24 January 2020 / Revised: 6 February 2020 / Accepted: 8 February 2020 / Published: 11 February 2020
(This article belongs to the Special Issue Femtosecond Laser Micromachining for Photonics Applications)
Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices, particularly in a way suitable for large scale adoption, remains a critical challenge. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy-based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser-assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3% ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.
Keywords: optical biopsy; Raman spectroscopy; micro-optics; ultrafast laser-assisted etching optical biopsy; Raman spectroscopy; micro-optics; ultrafast laser-assisted etching
MDPI and ACS Style

Ross, C.A.; MacLachlan, D.G.; Smith, B.J.E.; Beck, R.J.; Shephard, J.D.; Weston, N.; Thomson, R.R. A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching. Micromachines 2020, 11, 185.

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