Absolute calibration of a CCD camera with twin beams
  We report on the absolute calibration of a CCD camera by exploiting quantum correlation. This novel method exploits a certain number of spatial pairwise quantum correlated modes produced by spontaneous parametric-down-conversion. We develop a measurement model taking into account all the possible source of losses and noise that are not related to the quantum efficiency,accounting for all the uncertainty contributions, and we reach the relative uncertainty of 0.3% in low photon flux regime. This represents a significant step forward for the characterizaion of (scientific) CCDs used in mesoscopic light regime. 
I. Ruo-Berchera, A. Meda, I. P. Degiovanni, G. Brida, M. L. Rastello,   M. Genovese
quant-ph