Use of the Fabry-Perot Interferometer for atmospheric and night sky background monitoring in EAS detection

The Fabry-Perot interferometry is studied for determining the aerosol to molecular ratio for use in Fluorescence Detectors. This can be realized using an etalon with Free Spectral Range (FSR) of 0.05 cm-1. Another use of this instrumentation is considered in monitoring the intensity of some typical spectral lines of the night sky background radiation in EAS detection with the fluorescence or air-Cherenkov technique. These lines are that of atomic oxygen at wavelengths 557.7 and 630.0 nm, and also that of mercury at 365 nm, caused by artificial light pollution. We present preliminary laboratory results and evaluate their capabilities to meet the requirements of the above two calibration issues of EAS measurements