US Patent 10113956 Remote gas leakage detection systems using mid-infrared laser

A system remotely detects a gas leakage from a target in an area. The gas detection system includes two light sources: a mid-infrared (mid-IR) laser for detecting absorbance of the gas in the area, and a visible laser for detecting a pathlength of the mid-IR laser. The absorption is determined based on the relative amplitude difference of the emitted and reflected mid-IR light beams. The mid-IR laser may use wavelength modulation techniques to improve the absorption determination. The pathlength is determined by comparing a phase between the emitted visible light beam and the measured visible light beam. The gas detection system calculates a concentration of the gas in the area using the determined absorption and pathlength. The gas detection system may be attached to an unmanned aerial vehicle.