Search

The potential of three-wavelength Raman-lidar observations for a detailed optical and physical characterization of atmospheric particles is exemplified through a case study of measurements from 9 August 1998 of the Lindenberg Aerosol Characterization Experiment. Backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm allow one to estimate the vertical profiles of the volume concentration distribution and the complex refractive index with an inversion scheme. Subsequently the single-scattering albedo is calculated.

It is shown theoretically and verified experimentally for Raman scattering that a simple combination of a biconvex and a biconcave lens can be used as an optical energy and spatial filter to regulate the focused incident laser energy and the spatial resolution of the system simultaneously. While filtering of optical energy usually reduces the spatial resolution, the described optical filter improves the spatial resolution proportional to the square root of the energy reduction and provides a simple method to avoid gas breakdown or other disturbances of the gas state.