Compact eye-safe backscatter lidar for aerosol studies in urban polar environment

Abstract

We report a Compact Eye-Safe Backscatter Lidar (CESBL) system conceived for tropospheric aerosol research in the Arctic environment. The instrument will play an active role in the investigation of Arctic Haze and Ice Fog during winter time; intercontinental transport of Asian dust during springtime; and Aerosol plumes released from forest fires during summer time. In addition the system will perform systematic observations of Arctic Boundary Layer dynamics and Cirrus clouds. The lidar works at 1.574 μm and delivers 200 mJ maximum per pulse at 10 Hz prf. The output beam is conveniently expanded to yield an Eye-Safe factor greater than 250 suitable to operate in Urban Environments. The receiver is aimed with a Cassegrain telescope F/10, 20 cm primary diameter. The collimation and focusing were designed using commercial optics to holds approximately 1mrad field of view over a detector surface of 0.2 mm diameter. Signal detection is made by an InGaAs-APD followed by amplifiers. The Lidar system is mounted on an optical breadboard on a steerable platform and integrated into a PXI National Instrument data acquisition computer providing two acquisition channels at 200 MS/s maximum; 200 MHz of maximum bandwidth; and 12 bits vertical resolution. The acquisition code runs in a Lab-View platform with visualization interface and acquisition options optimized for field work. In this article the lidar system characteristics and the concept design are discussed. Initial geophysical results are shown.