Detection of small N2O concentrations using a frequency doubled 12C18O2 laser

A reliable procedure for remote high-accuracy laser detection of N2O as one of the principal destroyers of the protective ozone layer of the Earth has been developed. The procedure is based on using a CO2-laser system emitting efficiently in the ∼4.5 μm range. In this case lasing from isotopic modification 12C18O2 of carbon dioxide with its subsequent frequency doubling by a nonlinear crystal is used. With the object of reducing the price the composition of the active medium (both for TEA laser and low-pressure longitudinal-discharge-excitation laser) has been optimized. New high-efficiency intracavity frequency doubling schemes based on nonlinear AgGaSe2 crystals have been developed for CO2-lasers of both types. Low concentrations of N2O and concentrations of the principal background gases CO and H2O have been measured under real atmosphere conditions with the aid of the lidar complex built around these lasers.