Abstract

This work presents the proof of concept of a remote sensing system designed for the detection of molecular species such as gas pollutants via active differential optical absorption spectroscopy in the short- and mid-wavelength infrared. The system includes an optical parametric generator generating broad linewidth pulses tunable between 1.5 and 3.8 μm. A telescope coupled to a grating spectrograph and an in-house gated HgCdTe avalanche photodiode measures the whole return spectrum from each pulse. Experiments show simultaneous detection in atmospheric air and inside a cell of ${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{CO}}_2$ at 2 μm, and ${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{CH}}_4$ at 3.3 μm. The detection limits for ${\mathrm{CO}}_2$ and ${\mathrm{CH}}_4$ are 158 and 1 ppm·m, respectively. A new algorithm is also presented enabling the determination of concentrations when spectra include strong absorption features.

© 2015 Optical Society of America

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