A comparison of topologies used in an interferometric gas detection technique

J. A. A. Bremner; T. Kissinger; J. Hodgkinson; R. P. Tatam

doi:10.1117/12.2555755

1 April 2020 A comparison of topologies used in an interferometric gas detection technique

J. A. A. Bremner, T. Kissinger, J. Hodgkinson, R. P. Tatam

Proceedings Volume 11354, Optical Sensing and Detection VI; 1135419 (2020) https://doi.org/10.1117/12.2555755
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

We describe a combination of Tunable Diode Laser Spectroscopy and Range Resolved Interferometry that enables multipoint gas detection using a single laser and photodetector. Tunable Diode Laser Spectroscopy (TDLS) permits gas detection via the measurement of its optical absorption while a diode laser is tuned through an absorption line. Range Resolved Interferometry (RRI) employs a signal processing technique previously used for position sensing and vibrometry. The principle of operation is the sinusoidal modulation of the emission wavelength of a laser which is coupled into a network of interferometers. The detected signal is demodulated to give the signal amplitude within each interferometer. Signals from different interferometers can be distinguished based on the optical path length difference, enabling continuous interrogation of multiple measurement channels simultaneously. In this work, a number of gas cells are combined with optical fibre to create systems of nested interferometers, including a combination of gas cells and a common local oscillator. The laser wavelength was modulated with a combination of fast sinusoidal (49kHz) and slow (2Hz) ramp wave forms, the ramp sweeping the central wavelength of the laser through the methane absorption line at 1653nm. The intensity signal for each cell was extracted using the RRI technique in order to measure the methane concentration within each cell A Mach-Zehnder topology allows the measurement of methane at concentrations as low as 200ppm. We discuss the potential performance of other topologies that are more suitable for field deployment.

Conference Presentation

Citation Download Citation

J. A. A. Bremner, T. Kissinger, J. Hodgkinson, and R. P. Tatam "A comparison of topologies used in an interferometric gas detection technique", Proc. SPIE 11354, Optical Sensing and Detection VI, 1135419 (1 April 2020); https://doi.org/10.1117/12.2555755

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available