The efficiency of a detector in recording radiation. It is the ratio of the number of photons usefully detected to the number (of a given frequency) that strike the detector. An ideal detector would have a quantum efficiency of 1. Photographic emulsion records only a small proportion of incoming photons, and thus has a low quantum efficiency of 0.001–0.01. Electronic detectors, such as CCDs and photomultipliers, have quantum efficiencies of 0.6–0.8 and hence can record faint objects during short exposures. The quantum efficiency of the human eye is about 0.01–0.05. Quantum efficiency is frequently expressed as a percentage.
Subjects: Astronomy and Astrophysics — Chemistry.