An FPGA-based lock-in detection system to enable chemical species tomography using TDLAS

Andrea Chighine , Edward Fisher , David Wilson, Michael Lengden, Walter Johnstone, Hugh McCann

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

8 Citations (Scopus)
642 Downloads (Pure)

Abstract

This paper presents the design, implementation and test of a compact, low-cost and fully digital signal recovery system for tunable diode laser absorption spectroscopy (TDLAS) in narrow line-width gas sensing applications. An FPGA-based digital lock-in amplifier (DLIA), in conjunction with TDLAS using the wavelength modulation spectroscopy (WMS) technique, is utilized to demodulate and extract first (1f) and second (2f) harmonic signals for a narrow CO2 feature in the spectrum region of 1997.2nm. The spectrum in this wavelength region shows suitably weak water absorption, enabling CO2 detection with high resolution. Gas-cell experiments were carried out using the DLIA and a conventional rack-mounted commercial lock-in amplifier. The comparison between the two systems shows good agreement, validating the feasibility of this approach and demonstrating the prospect for extension to a massively multichannel system to implement Chemical Species Tomography.
Original languageEnglish
Title of host publication2015 IEEE International Conference on Imaging Systems and Techniques (IST)
Place of PublicationPiscataway, NJ
PublisherIEEE
Pages1-5
Number of pages5
ISBN (Print)9781479986330
DOIs
Publication statusPublished - Sep 2015

Keywords

  • amplifiers
  • chemical variables measurment
  • measurement by laser beam
  • absorption
  • spectrochemical analysis
  • chemical species tomography

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