Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
| In EELS and imaging system, one of the important parameters is detective quantum efficiency (DQE), which is the ratio of the number of counts to the mean square fluctuation in them and is introduced to assess the varying levels of performance of imaging detectors with the aim of comparing their imaging capabilities by an unified approach [1 - 2]. The DQE is always in the range 0 to 1. Typical DQE is close to 0.9 for many commercial scintillators. The system has unit DQE if it is shot noise limited, i.e. the mean square signal fluctuation in a channel is equal to the number of counts within it. However, channel-to-channel gain variations in photodiode arrays, dark current, and detector noise of various sorts, make it difficult to come close to unit DQE [3].
[1] A. Rose, J. Soc. Motion Picture Engrs. 47 (1946) 273.
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