Tuneable diode laser spectroscopy over optical fibres for gas measurements in harsh industrial environments

Walter Johnstone, Kevin Duffin, Andrew James Mcgettrick, George Stewart, Amy CHEUNG, D. Moodie

Research output: Contribution to journalArticle

Abstract

Near infra-red tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is a powerful technique for the measurements of gas compositions, and its ability to address multiple sensing points over optical fibre networks is proving to be particularly useful. However, the complexity involved in compensating for errors arising from pressure fluctuations is a weakness. Indeed, it is desirable to develop the technique to be capable of measuring pressure. This requires the extraction of accurate linewidth information from the recovered signals, so far made difficult by the presence of a systematic distortion arising from the laser amplitude modulation. Here we report a simple detection technique to null the effects of laser amplitude modulation and recover undistorted signals from which the gas linewidth can be accurately measured. Firstly we demonstrate that the measurements of accurate gas linewidths and pressure can be made from direct detection TDLS, addressing an atmospheric water absorption line. Finally, we report the accurate and simple measurement of acetylene pressure from TDLS / WMS measurements.

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Laser Spectroscopy
Gas fuel measurement
Laser spectroscopy
Diode Laser
laser spectroscopy
Optical Fiber
Semiconductor lasers
Optical fibers
Linewidth
optical fibers
diodes
Amplitude Modulation
Amplitude modulation
Gases
gases
Spectroscopy
Modulation
Wavelength
Laser
Acetylene

Keywords

  • tuneable diode laser spectroscopy
  • wavelength modulation spectroscopy
  • optical fibre networks
  • laser amplitude modulation

Cite this

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title = "Tuneable diode laser spectroscopy over optical fibres for gas measurements in harsh industrial environments",
abstract = "Near infra-red tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is a powerful technique for the measurements of gas compositions, and its ability to address multiple sensing points over optical fibre networks is proving to be particularly useful. However, the complexity involved in compensating for errors arising from pressure fluctuations is a weakness. Indeed, it is desirable to develop the technique to be capable of measuring pressure. This requires the extraction of accurate linewidth information from the recovered signals, so far made difficult by the presence of a systematic distortion arising from the laser amplitude modulation. Here we report a simple detection technique to null the effects of laser amplitude modulation and recover undistorted signals from which the gas linewidth can be accurately measured. Firstly we demonstrate that the measurements of accurate gas linewidths and pressure can be made from direct detection TDLS, addressing an atmospheric water absorption line. Finally, we report the accurate and simple measurement of acetylene pressure from TDLS / WMS measurements.",
keywords = "tuneable diode laser spectroscopy , wavelength modulation spectroscopy , optical fibre networks, laser amplitude modulation",
author = "Walter Johnstone and Kevin Duffin and Mcgettrick, {Andrew James} and George Stewart and Amy CHEUNG and D. Moodie",
year = "2005",
doi = "10.1117/12.622820",
language = "English",
volume = "5952",
pages = "595206",
journal = "Proceedings of SPIE",
issn = "0277-786X",

}

Tuneable diode laser spectroscopy over optical fibres for gas measurements in harsh industrial environments. / Johnstone, Walter; Duffin, Kevin; Mcgettrick, Andrew James; Stewart, George; CHEUNG, Amy; Moodie, D.

In: Proceedings of SPIE: The International Society for Optical Engineering, Vol. 5952, 2005, p. 595206.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Tuneable diode laser spectroscopy over optical fibres for gas measurements in harsh industrial environments

AU - Johnstone, Walter

AU - Duffin, Kevin

AU - Mcgettrick, Andrew James

AU - Stewart, George

AU - CHEUNG, Amy

AU - Moodie, D.

PY - 2005

Y1 - 2005

N2 - Near infra-red tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is a powerful technique for the measurements of gas compositions, and its ability to address multiple sensing points over optical fibre networks is proving to be particularly useful. However, the complexity involved in compensating for errors arising from pressure fluctuations is a weakness. Indeed, it is desirable to develop the technique to be capable of measuring pressure. This requires the extraction of accurate linewidth information from the recovered signals, so far made difficult by the presence of a systematic distortion arising from the laser amplitude modulation. Here we report a simple detection technique to null the effects of laser amplitude modulation and recover undistorted signals from which the gas linewidth can be accurately measured. Firstly we demonstrate that the measurements of accurate gas linewidths and pressure can be made from direct detection TDLS, addressing an atmospheric water absorption line. Finally, we report the accurate and simple measurement of acetylene pressure from TDLS / WMS measurements.

AB - Near infra-red tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is a powerful technique for the measurements of gas compositions, and its ability to address multiple sensing points over optical fibre networks is proving to be particularly useful. However, the complexity involved in compensating for errors arising from pressure fluctuations is a weakness. Indeed, it is desirable to develop the technique to be capable of measuring pressure. This requires the extraction of accurate linewidth information from the recovered signals, so far made difficult by the presence of a systematic distortion arising from the laser amplitude modulation. Here we report a simple detection technique to null the effects of laser amplitude modulation and recover undistorted signals from which the gas linewidth can be accurately measured. Firstly we demonstrate that the measurements of accurate gas linewidths and pressure can be made from direct detection TDLS, addressing an atmospheric water absorption line. Finally, we report the accurate and simple measurement of acetylene pressure from TDLS / WMS measurements.

KW - tuneable diode laser spectroscopy

KW - wavelength modulation spectroscopy

KW - optical fibre networks

KW - laser amplitude modulation

U2 - 10.1117/12.622820

DO - 10.1117/12.622820

M3 - Article

VL - 5952

SP - 595206

JO - Proceedings of SPIE

T2 - Proceedings of SPIE

JF - Proceedings of SPIE

SN - 0277-786X

ER -