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Lenless fiber-deployed low-coherence interferometer for in-situ measurements in non-ideal environments

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posted on 08.01.2020 by Tom Hovell, Ranveer Matharu, Jon Petzing, Laura Justham, Peter Kinnell
Low-Coherence Interferometry (LCI) is a well-established optical method used for obtaining geometric measurements, suited to operating in non-ideal environments as shown through its use in biomedical science where it is referred to as Optical Coherence Tomography (OCT). However, work on characterising this technologies ability to work in-situ within the area of manufacturing is yet to be demonstrated. This research is motivated by the need to develop robust sensors capable of operating in the harsh environment of manufacturing processes in near real-time, providing on demand process control for the next generation of precise, and highly adaptive schemes of production. The evaluation of a common-path, lensless, spectral-domain, LCI based sensor for measurements of step-heights in air and in the non-ideal operating environment of water is demonstrated. Calibration experiments have explored linearity of measurements over a 1 mm investigated axial range with deviations of the order of 50 nm in air and 100 nm in water. Step heights of 8 micrometres, 7 micrometres, 6 micrometres and 5 micrometres were measured in air and also with the sample and sensing probe submerged in water. Step heights in both mediums closely align with calibrated specifications given by the manufacturer demonstrating sub-micrometre accuracy and a precision of 56 nm in air and 76 nm in water.

Funding

UK Engineering Physical Science and Research 254 Council (EPSRC) (grant numbers EP/M020746/1, EP/L01498X/1)

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Optical Engineering

Volume

59

Issue

1

Citation

Tom Hovell, Ranveer S. Matharu, Jon N. Petzing, Laura Justham, and Peter K. Kinnell "Lensless fiber-deployed low-coherence interferometer for in-situ measurements in nonideal environments," Optical Engineering 59(1), 014113 (28 January 2020). https://doi.org/10.1117/1.OE.59.1.014113

Publisher

Society of Photo-optical Instrumentation Engineers (SPIE)

Version

VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Acceptance date

26/12/2019

Publication date

2020-01-28

Copyright date

2020

ISSN

0091-3286

eISSN

1560-2303

Language

en

Depositor

Dr Jon Petzing. Deposit date: 6 January 2020

Article number

014113

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