Frequency agile infrared lidar based on a nontracking KNbO3 optical parametric oscillator

We present what is to our knowledge the first mid-IR lidar system based on a KNbO3 optical parametric oscillator pumped by a Ti:sapphire laser. The op tical parametric oscillator works in a nontracking configuration and provid es high-frequency agility from 1 to 4 mu m This system constitutes an exten sion to the IR of UV lidars described previously [Europhys. J. D 4, 231 (19 98); Appl. Opt. 37, 2231 (1998); Atmos. Environ. 32, 2957 (1998)] Wr the de termination of aerosol concentrations in urban atmospheres. As first held t ests, measurements at 3.5 mu m were performed in fog conditions. Water drop let size and concentration were determined from Mie calculations. Quantitat ive temporal mappings and angular profiles are presented. (C) 2000 Optical Society of America OCIS codes: 010.1100, 010.3640, 040.3060, 190.4970.