Dual-Comb Scanning Spectrometer for Remote Sensing of Traces of Explosives

Standoff scanning dual-comb spectroscopy of explosive materials is demonstrated with quantum cascade lasers at $\sim 8~\mu \text{m}$ . The proof-of-concept of the spectrometer, capable of the detection and identification of explosive materials at a distance of 3 m, has a detection limit of cyclotrimethylenetrinitramine (RDX) and pentaerythritol tetranitrate (PETN) on various surfaces of 5– $8~\mu \text{g}$ /cm² in a scanning regime and 2– $3~\mu \text{g}$ /cm² with stationary beam in reflection–absorption and backscattering modes.