A high spectral resolution lidar using an iodine vapor filter at 589 nm

A high-spectral resolution Rayleigh-Mie lidar based on an iodine vapor filter and operating at 589 nm has been developed. The use of an iodine vapor filter as a band stop filter has allowed the separation of Rayleigh and Mie scattering signals. This allows the lidar to measure atmospheric state variables and optical aerosol properties as a stand alone device.; This lidar uses a narrow band pulsed laser as a light source, Rayleigh scattering by the atmosphere to provide a return signal, Doppler free saturated absorption spectra to provide an absolute frequency scale, and the absorption spectrum of iodine as a band stop filter. The determination of atmospheric and aerosol parameters relies on knowing the characteristics of the iodine absorption cell obtained by laboratory experiments. The analysis uses the theoretical Rayleigh-Brillouin frequency scattering function, as well as the assumption that the atmosphere is in hydrostatic equilibrium and acts as an ideal gas. It is also necessary to input or pin the air pressure at one altitude.; This lidar implements features not present in the previous version. Locking to a frequency reference and monitoring the quality of the locking, installation of a 1 A norrowband interference filter, and most importantly using a temperature stabilized iodine vapor cell as the ultra-narrow band stop filter. These improvements result, respectively, in elimination of rotational Raman scattering from the lidar return, in a more stable laser frequency, and a more precise vapor filter transmission function. These, together, have resulted in improved lidar performance.; Uncertainties in the experiment are predominately due to photon noise which may be reduced by various methods of increasing photon counts.; Results of the field experiment are presented in profiles averaged over 82 minutes, semi-nightly, and nightly averages. For an integration time of 82 minutes the temperature can be measured at 1 km to within 4.6K, the volume backscatter ratio to 1% and the depolarization ratio to 2.4%.