This session was the heart of the conference. J.M. WOZNICKI presented a routine for calculation of the polychromatic transfer function of an image intensifier. Starting with electrons energetic and spatial distributions of the photocathode, and with the electrostatic data of the electron device, the program is able to give numerically the polychromatic transfer function of any real device. Results were presented, computed over nine optical wavelengths, giving a low chromatism which was found rather optimistic by one attendee.