  The technique of High Spectral Resolution Lidar (HSRL) for atmospheric
monitoring allows the determination of the aerosol to molecular ratio and can
be used in UHECR Observatories using air fluorescence telescopes. By this
technique a more accurate estimate of the Cherenkov radiation superimposed to
the fluorescence signal can be achieved. A laboratory setup was developed to
determine the backscattering coefficients using microparticles diluted in water
and diffusion interfaces. In this setup we used a CW SLM laser at 532 nm and a
250 mm Newtonian telescope. Simulations of the above experimental configuration
have been made using Scatlab\c{opyright}, FINESSE\c{opyright} 0.99.8 and
MATLAB\c{opyright} and are presented in this work. We compare the simulated
2-dimensional Fabry-Perot fringe images of the backscattering signal recorded
in the CCD sensor with that of experimental ones. Additionally, we simulated
the backscattering of the laser beam by the atmosphere at a height of 2000 m
and we have studied the influence of the beam and its diameter on the fringe
image.
