Compact dual-gas sensor for simultaneous measurement of atmospheric methane, and water vapor using a 3.38 μm antimonide-distributed feedback laser diode

A simple, compact sensor involving a continuous-wave 3.38 μm distributed feedback laser in combination with a novel compact dense-pattern multipass cell was demonstrated for simultaneous measurement of atmospheric methane and water vapor. The calibration-free direct absorption spectroscopy approach was adopted for data generation and processing. Allan deviation analysis indicates that minimum detection limits (1σ) of 11.0 ppb for CH4 and 100 ppm for H2O were achieved with a 1-s integration time at an optimum pressure of 50 Torr. Atmospheric environmental mixing ratios of these two gases were recorded and analyzed. This newly developed mid-infrared dual-gas sensor is very suitable for trace gas sensing in weight-limited unmanned aerial vehicle- or balloon-embedded field observations. [Display omitted] •A novel sensor was developed for simultaneous measurement of atmospheric methane and water vapor.•The sensor system provides absolute concentration measurements of CH4 and H2O by using calibration-free direct absorption spectroscopy method.•Continuous atmospheric environmental mixing ratios variations of CH4 and H2O were reported.