Development of 3.0–3.45 µm OPO laser based range resolved and hard-target differential absorption lidar for sensing of atmospheric methane

• OPO laser based DIAL system for measurement of atmospheric methane is developed.
• Differential absorption signal for methane up to a range of 400 m is measured.
• Daytime measurements of methane concentration varied from 1.9 ppm to 2.4 ppm.
• The sources of methane are discussed.

We have developed a tripod mounted 3.0–3.45 µm OPO laser based differential absorption lidar (DIAL) system for sensing of atmospheric methane. The system operates with Nd: YAG laser pumped OPO laser, a 20 cm aperture telescope and a pan-tilt system to scan the atmosphere. Atmospheric transmission spectra over the entire spectral region are measured and indentified the absorption region of the various molecules in comparison with HITRAN. The backscattered signal for range resolved and hard target configuration up to a range of 400 m are measured with range resolution of 15 m. The stable daytime measurements of methane concentration varied from 1.9 ppm to 2.4 ppm with rms deviation of 0.2 ppm have been achieved. The measured concentration is in good agreement with reported values.