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In this paper, mid-infrared spectrometer based on a liquid nitrogen cooled lead-salt diode laser, emitting at 2190 cm/sup -1/ for the in-situ measurement of stratospheric nitrous oxide is developed. The system operates unattended for several hours under changing ambient conditions: during flight, the pressure is ranging from 1000 down to 30 mbar, temperature ranges from +70/spl deg/C to -90/spl deg/C. Typical flight measurements are performed between 10000 and 22000 m of altitude and at an aircraft speed of 160-190 m/s.

In this paper, compact near-infrared distributed feedback diode-laser, emitting at 1.651 micron for the measurement of atmospheric methane profiles on an airborne platform is developed. The detection technique is based on two-tone frequency modulation spectroscopy. The calibration procedure for the analyser with respect to pressure changes during the flight mission is also discussed.