LIDAR (LIght Detection And Ranging) is an active, ground-based laser remote sensing technique to probe the atmosphere. Elastic backscatter LIDAR is typically used for studies of vertical profiles of aerosol-related quantities and clouds. The LIDAR, with its high spatial and temporal resolutions observes the attenuation of radiation appearing due to interaction of light with gas molecules and aerosols suspended in the air. A typical LIDAR has a laser and a receiver at the same place. A pulsed laser is used as a source of light directed at a certain elevation angle towards the atmosphere. The back-scattered light is collected by a receiving optics and transferred to a photo-detector. The photo-detector operates in the proportional regime so that the resulting magnitude of electrical signals corresponds to the number of photon received. A digitizer transforms analog signals from the photo-detector into digital ones, which are more suitable for data storage and computer-based analysis. The electrical signal from the photo-detector thus contains information on the presence, location, and relative concentration of atmospheric scatterers and absorbers, which can be extracted by computer-based analysis of the data. The backscattered wavelength is identical to the transmitted wavelength, and the magnitude of the received signal at a given range depends on the backscatter coefficient of scatterers at that range and the extinction coefficients of the scatterers along the path to that range.

Technical specifications

Pulse laser source: Nd:YAG
Wavelength: 1064, 532 nm
Energy/pulse: 100/50 mJ (1064/532 nm)
Pulse duration: 10 ns
Repetition rate: 1-20 Hz
Laser beam diameter: 4 mm (before expander)
Laser beam divergence: < 1.5 mrad (< 0.5 mrad after expanded)

Telescope type Cassegrainian (300 mm primary mirror)
Elastic wavelength: 1064, 532 nm

Detection unit:
Transient recorder: A/D converter (12 bit) 250 MHz
Detection channels: Elastic backscatter
Detectors: Photomultiplier tube and APD
Detection mode: Analog

General information:
Power supply: 220 VAC, 50-60 Hz, single phase
Power consumption: < 750 W

Vertical profiling of aerosol optical parameters
Aerosol layering in the troposphere
Boundary layer mixing height
Mixed layer depth and dynamic structure temporal evolution
Atmospheric transport processes
Cloud base height