Dye laser system for monitoring atmospheric molecular pollutants

A laser radar (LIDAR) system was designed, built, and successfully operated to measure ambient NO2 concentrations in the atmosphere. The LIDAR system operated by measuring the differential absorption of scattered energy (DASE) of two laser signals emitted at wavelengths corresponding to a maximum and minimum in the absorption spectrum of NO2. The LIDAR system was designed to be capable of operation in two basic modes. In the first mode, the outputs at the two required wavelengths, on and off resonance absorption of NO2, are obtainable in rapid sequence, with frequency selection by an electromagnetically-driven diffraction grating from a flash-lamp-pumped organic-dye laser. In the second mode, an intracavity dielectric-interface polarizing beam-splitter is used to obtain simultaneously the pair of close lying independently-tunable wavelengths required from the dye laser.