Differential absorption lidar at 1.67 μm for remote sensing of methane leakage

A differential absorption lidar (DIAL) for field monitoring of methane (CH4) leakage at a wavelength of 1.67 mu m was;I developed. Compared with traditional DIAL systems for environmental monitoring, this system has a higher distance resolution (similar to 15m) for determining the leak position and a shorter detection range up to 500m. First, considering appropriate design parameters, a theoretical simulation was performed to evaluate the sensitivity and the detectable range of the system. Based on the analytical simulation; a prototype DIAL system was constructed and the detection of CH4 which had leaked into the atmosphere was demonstrated; The CH4 leakage of 6000 ppm.m at a distance of 130 m was successfully detected. The detection limit was 1000 ppm.m. With the improvements in the light source and the detector system, the detectable boundary can be increased in the range from 90 to 540 m for a concentration of 1500 ppm.m.