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quantum efficiencyA measure of the efficiency of conversion or utilization of light or other radiation. It is given by the proportion of incident photons, of a particular frequency, that are converted by a device into a useful form, such as a permanent record. Photographic emulsions, at best, record only a few photons out of every thousand falling on them. Electronic detectors have a much higher efficiency.
quantum efficiency[′kwän·təm i‚fish·ən·sē]
The average number of electrons photoelectrically emitted from a photocathode per incident photon of a given wavelength in a phototube.