Differential absorption lidar at 1.67 /spl mu/m for the detection of methane gas leakage

Differential absorption lidar (DIAL) is very useful for remote sensing of atmospheric molecules. Methane (CH/sub 4/) is one of the greenhouse gases and for the DIAL experiments, the absorption around 3.39 /spl mu/m is usually used. Continuous monitoring of the flamable CH/sub 4/ gas leakage is very important especially in a factory or along a gas pipe line. In the case of such a high concentration monitoring, absorption around 1.67 pm can be used. In this paper, we developed a DIAL system to detect CH/sub 4/ at a wavelength of 1.67 /spl mu/m Infrared (IR) laser source at 1.67 /spl mu/m is easily obtainable and fast photodetectors, such as InGaAs PIN photodiodes are available in this range.