A High Spectral Resolution Lidar (HSRL) is designed in order to achieve high accuracy measuring the aerosol to molecular scattering coefficients ratio. This type of Lidar consists of a Continuous Wave Single Longitudinal Mode laser beam at 532 nm, a receiver with a parabolic mirror and analyzes spectrally the scattered light in a Fabry-Perot Cavity. The great wavelength sensitivity of this system allows the separation of the aerosol and molecular component due to their different levels of Doppler effects on the scattered laser light. We present a study of the effects of the various levels of CCD cooling on the sensitivity of this. Firstly we discuss preliminary experimental results based on a Fabry-Perot etalon with free spectral range (FSR) 0.1 cm−1, the expected performance of a etalon with FSR of 0.05 cm−1, under construction, and with finally an aerosol parameter analysis in Simulation Codes for EAS.