Laser diagnostics of the ammonia pollutant in the atmosphere from an aircraft

A differential absorption method combined with heterodyne photodetection was used in a remote laser gas analyzer placed on board of an aircraft. A waveguide CO₂ laser with alternate switching of lasing between the two nearest lines of the vibrational–rotational spectrum of CO₂ was used as the light source. The gas analyzer was placed on board a helicopter and was used to localize a simulated escape of the gas from an ammonia pipeline and to estimate the amount of ammonia released as an effluent.