Open AccessOpen-path multi-species remote sensing with a broadband optical parametric oscillator
Author(s) -
Oguzhan Kara,
Frazer Sweeney,
Marius Rutkauskas,
Carl Farrell,
C.G. Leburn,
Derryck T. Reid
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.021358
Subject(s) - methane , optical parametric oscillator , optical path , fourier transform spectroscopy , broadband , optics , materials science , absorption (acoustics) , remote sensing , parts per notation , environmental science , spectroscopy , spectral resolution , fourier transform infrared spectroscopy , analytical chemistry (journal) , laser , spectral line , physics , chemistry , geology , environmental chemistry , organic chemistry , quantum mechanics , astronomy
Open-path remote sensing is critical for monitoring fugitive emissions from industrial sites, where a variety of volatile organic compounds may be released. At ranges of only a few tens of metres, spatially coherent broadband mid-infrared sources can access sufficiently large absorption cross-sections to quantify hydrocarbon gas fluctuations above ambient background levels at high signal:noise ratios. Here we report path-integrated simultaneous concentration measurements of water, methane and ethane implemented in the 3.1-3.5-µm range using 0.05-cm -1 -resolution Fourier-transform spectroscopy with an ultrafast optical parametric oscillator and a simple, non-compliant target. Real-time concentration changes were observed at a range of 70 m by simulating a fugitive emission with a weak localized release of 2% methane in air. Spectral averaging yielded a methane detection sensitivity of 595 ppb·m, implying a system capability to resolve few-ppb concentrations of many volatile organic compounds at observation ranges of 50-100 m.