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
Journal ArticleDOI
Ultrahigh resolution spectroscopy for dimethyl sulfide at the ν1- and ν8-bands by a distributed feedback interband cascade laser
TL;DR: In this article, the ultrahigh-resolution, air-broadened mid-infrared absorption spectrum of dimethyl sulfide (DMS) was recorded in the spectral region of 2994.17-2999.03 cm−1, where the strong ν1-/ν8-bands are located.
Proceedings ArticleDOI
Coherent sources for mid-infrared laser spectroscopy
TL;DR: In this article, the authors used mid-infrared laser absorption spectroscopy (LAS) for molecular trace gas concentration measurements in gas mixtures, which can be used in a wide range of applications such as gas quality screening for regulation, metering and custody transfer.
Dissertation
Portable spectroscopy system for ultra-sensitive, real-time measurement of breath ethane
TL;DR: The results suggest that breath ethane may be used as an indicator of dynamic changes in oxidative stress, yielding some interesting findings in a number of pilot clinical studies.
Proceedings ArticleDOI
External laser intensity modulation based on a MEMS micro-mirror for photo-acoustic gas sensing
Li Li,George Stewart,Graham Thursby,Norhana Arsad,Deepak Uttamchandani,Brian Culshaw,Yiding Wang +6 more
TL;DR: In this article, an external laser intensity modulation system based on a micro-electromechanical systems (MEMS) mirror is presented for application to gas sensing, where the rotation direction is decided by the relative position between the driving actuator and the axis of the micro-mirror.
Dissertation
Diode Laser Spectroscopy for Measurements of Gas Parameters in Harsh Environments
TL;DR: In this article, a frequency chirped diode laser spectroscopy (FC-DLS) method was proposed to estimate the absolute line shape function and remove the impact of optical intensity fluctuations on measurement.
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