CCDs for the instrumentation of the telescopio nazionale galileo

Most of the scienti c instrumentation as well as the tracking systems and the ShackHartmann wavefront analysers at the Italian National Telescope Galileo use CCDs as detectors. The characterization of detectors is of fundamental importance for their correct utilization in scienti c instrumentation. We report on the measurement of the electro-optical characteristics of CCDs that will be used in the scienti c instrumentation at the Italian National Telescope. In particular we will show and compare the quantum eÆciency, the charge transfer eÆciency, the dark current, the read out noise, the uniformity and the linearity of two sets of CCDs manufactured by EEV and LORAL. Finally, we will show the preliminary tests done at the telescope with the optical imager that has a mosaic of two EEV chips.