Journal ArticleDOI
Tunable Diode-Laser Spectroscopy With Wavelength Modulation: A Calibration-Free Approach to the Recovery of Absolute Gas Absorption Line Shapes
Reads0
Chats0
TLDR
In this article, an alternative approach to tunable diode-laser spectroscopy with wavelength modulation is described, which offers the simplicity of signal analysis of direct detection while providing all the advantages of phase-sensitive electronic detection.Abstract:
The principles and implementation of an alternative approach to tunable diode-laser spectroscopy with wavelength modulation are described. This new technique uses the inherent phase shift between diode-laser power modulation and frequency modulation to separate the residual amplitude modulation and the first derivative signals recovered at the fundamental modulation frequency. The technique, through analysis of the residual-amplitude-modulation signal, is absolute, yielding gas-absorption-line-shape functions, concentrations, and pressures without the need for calibration under certain defined operating conditions. It offers the simplicity of signal analysis of direct detection while providing all the advantages of phase-sensitive electronic detection. Measurements of the 1650.96-nm rotation/vibration-absorption-line-shape function for 1% and 10% methane in nitrogen at various pressures are compared to theoretical predictions derived from HITRAN data, and the excellent agreement confirms the validity of the new technique. Further measurements of concentration and pressure confirm the efficacy of the technique for determining concentration in industrial-process environments where the pressure may be unknown and changing. An analysis of signal strength demonstrates that sensitivity comparable to that of conventional approaches is achievable. The new approach is simpler and more robust in coping with unknown pressure variations and drift in instrumentation parameters (such as laser characteristics) than the conventional approach. As such, it is better suited to stand-alone instrumentation for online deployment in industrial processes and is particularly useful in high-temperature applications, where the background infrared is strong.read more
Citations
More filters
Proceedings ArticleDOI
Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy
Li Li,Graham Thursby,George Stewart,Norhana Arsad,Deepak Uttamchandani,Brian Culshaw,Yiding Wang +6 more
TL;DR: In this paper, a micro-electromechanical system (MEMS) mirror driven by an electrothermal actuator is used for generating laser intensity modulation through the external reflection.
Proceedings ArticleDOI
Research of optic fiber CO concentration monitoring virtual system based on TDLAS
TL;DR: In this article, a CO concentration monitoring virtual system has been established based on the tuneable diode laser absorption spectroscopy (TDLAS) technology, which can accurately reflect the impact of second-tier parameters such as concentration, temperature and pressure.
Journal ArticleDOI
A trace CH4 detection system based on DAS calibrated WMS technique
TL;DR: In this paper , a compact near-infrared (NIR) laser-based trace methane (CH4) detection system was proposed, which relied on a 2334 nm distributed feedback (DFB) fiber laser as the light source.
Journal ArticleDOI
Study of a distributed feedback diode laser based hygrometer combined Herriot-gas cell and waterless optical components
TL;DR: In this article, a distributed feedback diode laser (DFB-DL) based hygrometer combined with a long-path-length Herriot gas cell and waterless optical components was proposed and investigated.
Journal ArticleDOI
Spectroscopic Techniques versus Pitot Tube for the Measurement of Flow Velocity in Narrow Ducts.
Francesco D'Amato,Silvia Viciani,Alessio Montori,Marco Barucci,Carmen Morreale,Silvia Bertagna,G. Migliavacca +6 more
TL;DR: In this article, the limits and applicability of Pitot tubes for the measurement of flow velocity in narrow ducts, e.g., biomass burning plants, were assessed. And the results of the two optical measurements were in agreement with each other and fit quite well the theoretical simulation of the flow field, while the results showed a remarkable dependence on position and inclination of the Pitot tube with respect to the duct axis.
References
More filters
Journal ArticleDOI
The HITRAN 2008 molecular spectroscopic database
Laurence S. Rothman,Iouli E. Gordon,Yurii L. Babikov,A. Barbe,D. Chris Benner,Peter F. Bernath,Manfred Birk,Luca Bizzocchi,Vincent Boudon,Linda R. Brown,Alain Campargue,Kelly Chance,Edward A. Cohen,L. H. Coudert,V. M. Devi,Brian J. Drouin,André Fayt,Jean-Marie Flaud,Robert R. Gamache,Jeremy J. Harrison,Jean-Michel Hartmann,Christian Hill,Joseph T. Hodges,D. Jacquemart,Antoine Jolly,Julien Lamouroux,R. J. Le Roy,Gang Li,David A. Long,O.M. Lyulin,C.J. Mackie,Steven T. Massie,Semen Mikhailenko,Holger S. P. Müller,Olga V. Naumenko,Andrei Nikitin,Johannes Orphal,V.I. Perevalov,Agnes Perrin,E. R. Polovtseva,Charlotte Richard,Mary Ann H. Smith,Evgeniya Starikova,Keeyoon Sung,S.A. Tashkun,Jonathan Tennyson,Geoff Toon,Vl.G. Tyuterev,G. Wagner +48 more
TL;DR: The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity, and molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth.
Journal ArticleDOI
Second-harmonic detection with tunable diode lasers — Comparison of experiment and theory
John Reid,Daniel Labrie +1 more
TL;DR: In this paper, a series of experiments are carried out by current modulating a tunable diode laser, and slowly ramping the wavelength to scan weak absorption lines in gases at pressures ranging from 2 to 60 Torr.
Journal ArticleDOI
A review of recent advances in semiconductor laser based gas monitors
TL;DR: In this paper, the main features and applications of tunable diode laser absorption spectroscopy are reviewed and the main characteristics of the currently available semiconductor diode lasers with respect to spectroscopic applications and sensitive detection techniques are discussed.
Journal ArticleDOI
Direct frequency modulation in AlGaAs semiconductor lasers
TL;DR: In this paper, the frequency modulation characteristics of three different AlGaAs lasers, a channeled-substrate planar (CSP), a buried-heterostructure (BH) and a transverse-junction-stripe (TJS) laser, were studied theoretically and experimentally.
Journal ArticleDOI
Frequency modulation and wavelength modulation spectroscopies:comparison of experimental methods using a lead-salt diode laser
TL;DR: Both of the FMS methods, which require modulating the laser at frequencies >/= 150 MHz, give relatively poor results due to inefficient coupling of the modulation waveform to the laser current, and the re ults obtained agree well with theory.
Related Papers (5)
Calibration-free wavelength-modulation spectroscopy for measurements of gas temperature and concentration in harsh environments
Wavelength modulation spectroscopy: combined frequency and intensity laser modulation
The HITRAN 2008 molecular spectroscopic database
Laurence S. Rothman,Iouli E. Gordon,Yurii L. Babikov,A. Barbe,D. Chris Benner,Peter F. Bernath,Manfred Birk,Luca Bizzocchi,Vincent Boudon,Linda R. Brown,Alain Campargue,Kelly Chance,Edward A. Cohen,L. H. Coudert,V. M. Devi,Brian J. Drouin,André Fayt,Jean-Marie Flaud,Robert R. Gamache,Jeremy J. Harrison,Jean-Michel Hartmann,Christian Hill,Joseph T. Hodges,D. Jacquemart,Antoine Jolly,Julien Lamouroux,R. J. Le Roy,Gang Li,David A. Long,O.M. Lyulin,C.J. Mackie,Steven T. Massie,Semen Mikhailenko,Holger S. P. Müller,Olga V. Naumenko,Andrei Nikitin,Johannes Orphal,V.I. Perevalov,Agnes Perrin,E. R. Polovtseva,Charlotte Richard,Mary Ann H. Smith,Evgeniya Starikova,Keeyoon Sung,S.A. Tashkun,Jonathan Tennyson,Geoff Toon,Vl.G. Tyuterev,G. Wagner +48 more