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Near-infrared broadband cavity-enhanced sensor system for methane detection using a wavelet-denoising assisted Fourier-transform spectrometer

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Abstract

The majority of broadband cavity-enhanced systems are used to detect trace gas species in the visible spectral range. We demonstrated a broadband cavity-enhanced sensor system in combination with a Fourier-transform spectrometer (FTS) in the near-infrared (near-IR) region for methane (CH4) detection. Light from a tungsten–halogen lamp was coupled into a high-finesse cavity and the light leaking from the cavity was imaged onto the FTS. An optimal incident beam diameter of 2.25 cm was required in the condition of a 40 cm-long cavity of a 2.5 cm diameter and a 100 cm radius of curvature (RoC) mirror. The CH4 sensor system was capable of operating at a temperature of 300 K and 1 atm gas pressure. Based on an Allan variance analysis, a minimum detectable absorption coefficient of 4.6 × 10−7 cm−1 was achieved. A wavelet denoising (WD) method was introduced in the retrieval of the gas concentration, which improved the measurement precision from 10.2 parts-per-million in volume (ppmv) to 5.3 ppmv with an enhancement factor of 2 for a 20 min averaging time. The near-IR broadband cavity-enhanced sensor system can also be used to measure high-resolution absorption spectra of other atmospheric trace gas species.

Graphical abstract: Near-infrared broadband cavity-enhanced sensor system for methane detection using a wavelet-denoising assisted Fourier-transform spectrometer

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Publication details

The article was received on 13 Jul 2018, accepted on 28 Aug 2018 and first published on 29 Aug 2018


Article type: Paper
DOI: 10.1039/C8AN01290C
Citation: Analyst, 2018, Advance Article
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    Near-infrared broadband cavity-enhanced sensor system for methane detection using a wavelet-denoising assisted Fourier-transform spectrometer

    K. Zheng, C. Zheng, Z. Liu, Q. He, Q. Du, Y. Zhang, Y. Wang and F. K. Tittel, Analyst, 2018, Advance Article , DOI: 10.1039/C8AN01290C

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