Implementation of a violet Scheimpflug lidar system for atmospheric aerosol studies

A violet Scheimpflug lidar system employing a 1-W 407-nm multimode laser diode is developed for remote sensing of atmospheric aerosols. The laser beam of the laser diode that is transmitted into atmosphere has been investigated in detail and a cylindrical lens pair is designed to improve the geometrical transmission efficiency. A measurement scheme with automatic exposure as well as a generalized signal processing method are established to optimize the signal-to-noise ratio of lidar signals. The performance of the violet Scheimpflug lidar system has been evaluated during a six-day continuous measurement campaign on a near horizontal path. The maximum measurement distance can reach up to 7 km in sunny clean weathers and to about 2 km during haze with an aerosol extinction coefficient of about 0.9 km. The aerosol extinction coefficient retrieved by the Fernald method is promising and shows good correlation with particle concentrations measured by a local national pollution monitoring station. This work promotes the development of all-time Scheimpflug lidar systems operating at other wavelengths or multiple wavelengths for various atmospheric applications.