Presentation
12 September 2019 Dual-comb spectroscopy for quantification of greenhouse gasses (Conference Presentation)
Author Affiliations +
Abstract
The output of a laser frequency comb is composed of 100,000+ perfectly spaced, discrete wavelength elements or comb teeth, that act as a massively parallel set of single frequency (CW) lasers with highly stable, well-known frequencies. In dual-comb spectroscopy, two such frequency combs are interfered on a single detector yielding absorption information for each individual comb tooth. This approach combines the strengths of both cw laser spectroscopy and broadband spectroscopy providing high spectral resolution and broad optical bandwidths, all with a single-mode, high-brightness laser beam and a simple, single photodetector, detection scheme. Here we use a DCS systems to measure the atmospheric absorption over long open-air paths with 0.007cm-1 resolution over 1.57 to 1.66 um, covering absorption bands of CO2, CH4, H2O and isotopologues. Inter-comparison of instruments shows that we can measure CO2 and CH4 with precision of 0.14% and 0.35%, respectively, relative to their natural abundance. In addition, this novel spectroscopy source can be employed for regional (~kilometer scale) monitoring using an array of stationed retros or in conjunction with an unmanned aerial systems (UAS). Both fixed and UAS systems combine the high-precision, multi-species detection capabilities of open-path DCS and have proven to be extremely successful at locating and sizing very small gas leaks. Here we focus on two long-term field deployments where a near-IR spectrometer is used to detect methane leaks to support oil and gas and CO2 traffic emissions from the city of Boulder.
Conference Presentation
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ian Coddington "Dual-comb spectroscopy for quantification of greenhouse gasses (Conference Presentation)", Proc. SPIE 11128, Infrared Remote Sensing and Instrumentation XXVII, 111280E (12 September 2019); https://doi.org/10.1117/12.2531510
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KEYWORDS
Spectroscopy

Absorption

Carbon dioxide

Continuous wave operation

Frequency combs

Teeth

Laser spectroscopy

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