Diode laser spectroscopy using a calibration free phasor decomposition approach with RAM nulling

K.C. Ruxton; A. Chakraborty; A.J. McGettrick; K. Duffin; W. Johnstone; G. Stewart

Diode laser spectroscopy using a calibration free phasor decomposition approach with RAM nulling

K.C. Ruxton, A. Chakraborty, A.J. McGettrick, K. Duffin, W. Johnstone, G. Stewart

Electronic And Electrical Engineering

Research output: Contribution to conference › Paper

Abstract

A limiting factor of tunable diode laser spectroscopy (TDLS) analysis is the large unwanted residual amplitude modulation (RAM) background present on the recovered 1st harmonic signal. A novel approach to remove the background RAM will be presented. This new technique will be used alongside the phasor decomposition method (PDM) [1], a calibration free technique for recovery of the absolute gas absorption line-shape. The RAM nulling method developed, successfully removes the background by optical cancellation. This is
achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.

Original language	English
Pages	80
Number of pages	1
Publication status	Published - Jul 2009
Event	7th International Conference on Tunable Diode Laser Spectroscopy - Zermatt, Switzerland Duration: 13 Jul 2009 → 17 Jul 2009

Conference

Conference	7th International Conference on Tunable Diode Laser Spectroscopy
City	Zermatt, Switzerland
Period	13/07/09 → 17/07/09

Keywords

tunable diode laser spectroscopy
residual amplitude modulation
phasor decomposition method
absolute gas absorption
optical cancellation

Access to Document

http://tdls.conncoll.edu/2009/ABSTRACTBOOK2009.pdf

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Cite this

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title = "Diode laser spectroscopy using a calibration free phasor decomposition approach with RAM nulling",

abstract = "A limiting factor of tunable diode laser spectroscopy (TDLS) analysis is the large unwanted residual amplitude modulation (RAM) background present on the recovered 1st harmonic signal. A novel approach to remove the background RAM will be presented. This new technique will be used alongside the phasor decomposition method (PDM) [1], a calibration free technique for recovery of the absolute gas absorption line-shape. The RAM nulling method developed, successfully removes the background by optical cancellation. This is achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.",

keywords = "tunable diode laser spectroscopy, residual amplitude modulation , phasor decomposition method , absolute gas absorption, optical cancellation",

author = "K.C. Ruxton and A. Chakraborty and A.J. McGettrick and K. Duffin and W. Johnstone and G. Stewart",

year = "2009",

month = jul,

language = "English",

pages = "80",

note = "7th International Conference on Tunable Diode Laser Spectroscopy ; Conference date: 13-07-2009 Through 17-07-2009",

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TY - CONF

T1 - Diode laser spectroscopy using a calibration free phasor decomposition approach with RAM nulling

AU - Ruxton, K.C.

AU - Chakraborty, A.

AU - McGettrick, A.J.

AU - Duffin, K.

AU - Johnstone, W.

AU - Stewart, G.

PY - 2009/7

Y1 - 2009/7

N2 - A limiting factor of tunable diode laser spectroscopy (TDLS) analysis is the large unwanted residual amplitude modulation (RAM) background present on the recovered 1st harmonic signal. A novel approach to remove the background RAM will be presented. This new technique will be used alongside the phasor decomposition method (PDM) [1], a calibration free technique for recovery of the absolute gas absorption line-shape. The RAM nulling method developed, successfully removes the background by optical cancellation. This is achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.

AB - A limiting factor of tunable diode laser spectroscopy (TDLS) analysis is the large unwanted residual amplitude modulation (RAM) background present on the recovered 1st harmonic signal. A novel approach to remove the background RAM will be presented. This new technique will be used alongside the phasor decomposition method (PDM) [1], a calibration free technique for recovery of the absolute gas absorption line-shape. The RAM nulling method developed, successfully removes the background by optical cancellation. This is achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.

KW - tunable diode laser spectroscopy

KW - residual amplitude modulation

KW - phasor decomposition method

KW - absolute gas absorption

KW - optical cancellation

UR - http://tdls.conncoll.edu/2009/ABSTRACTBOOK2009.pdf

M3 - Paper

SP - 80

T2 - 7th International Conference on Tunable Diode Laser Spectroscopy

Y2 - 13 July 2009 through 17 July 2009

ER -