An OPO-based lidar system for differential absorption measurements of hazardous gases in mid-infrared spectral region.

We present the second phase of our work in project LISATNAS devoted to design the differential absorption lidar (DIAL) based on the mid-infrared (IR) tunable Optical Parametric Oscillator (OPO). Generation of tunable mid-infrared laser radiation using a two stage tandem OPO was demonstrated. The first stage was based on the nonlinear KTP crystal and produced up to 45 mJ of 1.57 μm radiation, while pumped by a commercial Q-switched Nd:YAG laser. The quality of signal beam was improved by the use of unstable resonator. The AgGaSe 2 crystal was used in the second stage OPO. Idler energies up to 1.2 mJ were generated in this stage within tuning range from 6 to 12 μm. The receiver consisted of a 250 mm gold mirror telescope, pyroelectric detector with control electronics. Preliminary field test results for detection of H 2 O using a retroreflector are presented.