Fig. 1. CW and pulse output power of MINI-QCL

Fig. 2. CW and pulse output power of MIRcat-1200-1824 QCL

Fig. 3. LDV device. (a) Schematic of LDV optical design; (b) LDV real scene

Fig. 4. Experimental setup. (a) Experimental setup at distance of 200 m; (b) LDV experimental setup on the other end

Fig. 5. Schematic of the pipeline leakage experiment setup

Fig. 6. Comparison of experimental result with infrared absorption spectrum. (a) Infrared absorption spectrum of PTFE provided by NICODOM company; (b) normalized vibration amplitude obtained by LDV at different wavenumbers

Fig. 7. Comparison of experimental result with infrared absorption spectrum. (a) Infrared absorption spectrum of acetone measured by a spectrometer; (b) normalized vibration amplitude of acetone obtained by LDV at different wavenumbers