Measurement of Cosmic Ray Primary Energy with the Atmospheric Cherenkov Light Technique in Extensive Air Showers

The advantage and problems of the primary energy measurement using the Cherenkov light from extensive air showers are discussed. The problem of absolute energy calibration has been solved during the analysis of the data of complex QUEST experiment at the EAS-TOP array. The results of QUEST experiment has been used for the analysis of the data of pure Cherenkov light array Tunka.