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A coherent 2 [micro]m differential absorption and wind lidar (Co2DiaWiL) was developed to measure C[O.sub.2] concentration and line-of-sight wind speed. We conductively cooled a pumping laser head to -80[degrees]C and diode arrays to approximately 20[degrees]C. A Q-switched laser outputs an energy of 80 mJ (pulse width 150ns (FWHM), pulse repetition frequency up to 30Hz). C[O.sub.2] measurements made over a column range (487-1986 m) for 5 min accumulation time pairs achieved 0.7% precision. Line-of-sight wind speeds for ranges up to approximately 20 km and returns from a mountainside located 24 km away from the Co2DiaWiL were obtained. OCIS codes: 010.0280, 010.3640, 280.1910, 140.3560, 140.3580.

We have developed a laser-ranging system to observe the topographical structure of volcanoes. This system can be used to measure the distance to a target by a laser and shows the three-dimensional topographical structure of a volcano with an accuracy of 30 cm. This accuracy is greater than that of a typical laser-ranging system that uses a corner-cube reflector as a target because the reflected light jitters as a result of inclination and unevenness of the target ground surface. However, this laser-ranging system is useful for detecting deformations of topographical features in which placement of a reflector is difficult, such as in volcanic regions. Key words: Laser ranging, laser altimeter.