 
    
    
    
      
   The major advantage of CCDs over other detectors
   is their high efficiency. The wavelength response for the
   types of CCD currently in use on La Palma is shown in Figure
     .
   The best (thinned) devices have a peak efficiency of about 80 per cent,
   whilst the unthinned ones have a peak efficiency
   of about 50 per cent.
.
   The best (thinned) devices have a peak efficiency of about 80 per cent,
   whilst the unthinned ones have a peak efficiency
   of about 50 per cent.
  
[ TIFF ]
Figure: Responsive 
Quantum Efficiency (RQE) as a function of wavelength for the 
Tektronix and EEV CCD detectors most commonly used on the La Palma Telescopes