Spectral variation of the conversion factor of an image intensifier

The conversion factor of the image intensifier Sirecon duplex 25/15 was investigated by means of a videodensitometer for varying values of the tube potential and varying filtering of the radiation. It was found that the conversion factor can be increased by Cu filtering. By analysis of the measurement data, the spectral variation of the conversion factor was determined. The conversion factor has a maximum for 60 keV photons and falls rapidly for photons of energy below 45 keV. By the method described, the spectral response function of an image intensifier can be determined experimentally without the use of a spectrometer.