Efficience quantique et efficience quantique de détection des photomultiplicateurs et des matériaux photographiques

The cathode quantum efficiency of several photomultipliers is evaluated at He-Ne laser wavelength from manufacturer's data. The quantum efficiency of the photographic process is defined as the ratio of developed grains (fog grains deduced) in an area A over the number of incident quanta. Five photographic materials were tested, and the quantum efficiency lies between 4 x 10(-4) and 1.1 x 10(-2); the quantum efficiency of photographic materials may be comparable to that of the cathode of photomultipliers. The detective quantum efficiency (EQD) of any detector is defined as the mean square of the SNR over the square of the same ratio obtained with a noiseless detector. The EQD of the photomultiplier 1P21 is equal to 1.4 x 10(-4). Following Shaw, the EQD of five photographic materials is evaluated at zero spatial frequency. The range of the EQD values is 3 x 10(-6) to 1.6 x 10(-4). The EQD values of photomul ipliers and photographic materials may thus be comparable.