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An analytical method to find the optimal parameters for gas detectors based on correlation spectroscopy using a Fabry-Perot interferometer

An analytical method to find the optimal parameters for gas detectors based on correlation spectroscopy using a Fabry-Perot interferometer
An analytical method to find the optimal parameters for gas detectors based on correlation spectroscopy using a Fabry-Perot interferometer
Several designs of infrared absorption based gas detector use a Fabry-Perot Interferometer (FPI) to modulate the incident light. In these systems, generally the FPI's fringes are matched with very well defined rotational absorption lines of a target molecule such as CO2, CO, N2O, CH4, etc. In order to obtain modulation the cavity length of the FPI is scanned over one half of the reference wavelength. In this work, we present a simple analytical method based on the Fourier Transform that describes the performance of these systems. Using this method the optimal reflectivity and optical spacing of the FPI can be determined. Furthermore, the modulated signal generated by the system as a function of the cavity length scan can be calculated by applying the inverse Fourier Transform. Finally, this method describes the underlying reasons why for some filters the background amplitude is severe, and gives guidance on the choice of optimised filters. Our method evaluates the optimal FPI parameters and the modulated signal much faster than the direct numerical computation which is used currently. Simulation results for different molecules in combination with diverse filters shapes are presented, with a comparison to directly computed results.
fabry-perot interferometer, rotational lines, correlation spectroscopy
9 pp
Vargas-Rodríguez, Everardo
8565869a-4312-4b09-9186-7f89409b2919
Rutt, Harvey
e09fa327-0c01-467a-9898-4e7f0cd715fc
SPIE Europe Internation Symposium on Optical System Design
Vargas-Rodríguez, Everardo
8565869a-4312-4b09-9186-7f89409b2919
Rutt, Harvey
e09fa327-0c01-467a-9898-4e7f0cd715fc

Vargas-Rodríguez, Everardo and Rutt, Harvey (2005) An analytical method to find the optimal parameters for gas detectors based on correlation spectroscopy using a Fabry-Perot interferometer. SPIE Europe International Symposium. Optical Systems Design. 12 - 16 Sep 2005. 9 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

Several designs of infrared absorption based gas detector use a Fabry-Perot Interferometer (FPI) to modulate the incident light. In these systems, generally the FPI's fringes are matched with very well defined rotational absorption lines of a target molecule such as CO2, CO, N2O, CH4, etc. In order to obtain modulation the cavity length of the FPI is scanned over one half of the reference wavelength. In this work, we present a simple analytical method based on the Fourier Transform that describes the performance of these systems. Using this method the optimal reflectivity and optical spacing of the FPI can be determined. Furthermore, the modulated signal generated by the system as a function of the cavity length scan can be calculated by applying the inverse Fourier Transform. Finally, this method describes the underlying reasons why for some filters the background amplitude is severe, and gives guidance on the choice of optimised filters. Our method evaluates the optimal FPI parameters and the modulated signal much faster than the direct numerical computation which is used currently. Simulation results for different molecules in combination with diverse filters shapes are presented, with a comparison to directly computed results.

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Published date: 2005
Venue - Dates: SPIE Europe International Symposium. Optical Systems Design, 2005-09-12 - 2005-09-16
Keywords: fabry-perot interferometer, rotational lines, correlation spectroscopy

Identifiers

Local EPrints ID: 38250
URI: https://eprints.soton.ac.uk/id/eprint/38250
PURE UUID: b2d586fd-b74e-4c7d-bc6f-692a7772d84d

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Date deposited: 06 Jun 2006
Last modified: 19 Jul 2019 18:58

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