30TH INTERNATIONAL COSMIC RAY CONFERENCE A Fabry-Perot Interferometer prototype for use in Doppler LIDAR for atmos-

Abstract: A Fabry-Perot interferometer prototype is studied, as part of a Doppler LIDAR (DL) re-ceiver, for determining the aerosol to molecular scattering ratio for use in EAS Fluorescence Detec-tors. The etalon of this instrument has a Free Spectral Range of 0.1 cm-1 and resolution in wavenum-ber 0.008 cm-1. Possible additional use of the proposed DL receiver can be as a spectrally selective de-tector to measure the aerosol phase function normalized to the molecular phase function using a bi-static LIDAR. Both molecular and aerosol data are collected by the same DL receiver simultaneously as opposed to the Rayleigh or Raman LIDAR adopted in the atmospheric monitoring procedures in EAS fluorescence telescopes. The results from the characterization of the 0.1 cm-1 FSR etalon, pre-sented in this work, are encouraging for the possibility for a constructing a DL receiver to measure the aerosol to molecular scattering ratio with better accuracy than the present techniques used in at-mospheric monitoring for EAS fluorescence or atmospheric Cherenkov telescopes. 1