Remote sensing using open-path dual-comb spectroscopy

Open-path dual-comb spectroscopy (DCS) is an emerging technique for long open-path measurements across km-scale paths. It provides both broad spectral coverage over hundreds of wavenumbers with high spectral resolution and negligible instrument lineshape. In this chapter, we discuss the principle of open-path DCS; provide an overview of the necessary technology and analysis techniques; review field applications including near-infrared (NIR) measurements of urban CO2 emissions, CH4 emissions from drilling and agricultural operations, measurements to a unmanned aerial vehicle, and recent measurements of volatile organic compounds in the mid-infrared (MIR); and finally provide an outlook especially on how this technique can move to additional spectral regions beyond the NIR and MIR.