14 May 2018 Application of rapidly swept external cavity quantum cascade lasers for open-path and standoff chemical sensing
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Rapidly-swept external-cavity quantum cascade lasers (swept-ECQCLs) provide the broad IR spectral coverage and high spectral brightness required for sensitive multi-chemical standoff detection. The laser source characteristics of swept- ECQCLs can be applied to a variety of standoff applications where gas-phase chemical species concentrations are changing rapidly in time. Some of these applications include standoff measurements in turbulent or chemically reactive plumes, monitoring of industrial emissions from stacks, and real-time monitoring of combustion processes. We have demonstrated and characterized a swept-ECQCL design that is capable of broadband spectral acquisition (~100 cm-1) at a 5 ms acquisition rate with a high spectral resolution (<0.2 cm-1). Laser systems based on this swept-ECQCL design have been applied to open-path and standoff measurements in turbulent and reactive chemical plumes of time-varying chemical and isotopic composition. Chemical plume studies have demonstrated the capability of this technology for open-path and standoff chemical sensing applications. In this talk we will present our current progress on the development and application of swept-ECQCL technology for sensitive and rapid multi-chemical open-path measurements in MeOD/MeOH plumes with time-varying isotopic composition at a 40 Hz rate. Preliminary results will also be provided for a 5 m standoff detection of hot CO and CO2 in a turbulent flame using a rapidly-swept mode-hop free (MHF) ECQCL design that is capable of collecting 1-2 cm-1 MHF spectral windows at an acquisition rate of 1 kHz with a spectral resolution of ~0.001 cm-1.
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Brian E. Brumfield, Brian E. Brumfield, Mark C. Phillips, Mark C. Phillips, } "Application of rapidly swept external cavity quantum cascade lasers for open-path and standoff chemical sensing", Proc. SPIE 10639, Micro- and Nanotechnology Sensors, Systems, and Applications X, 1063928 (14 May 2018); doi: 10.1117/12.2305056; https://doi.org/10.1117/12.2305056

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