The detection quantum efficiency of electronic image recording systems

SUMMARY The principles in design and operation of TV electron‐image recording systems are elucidated. Using the ‘detection quantum efficiency’ (DQE) as a figure of merit, the influence of various parameters is discussed, such as single electron response, read‐out noise and saturation of the camera tubes as well as the properties of digital frame stores. The analogue signal processing mode gives a DQE of about 0·8 and can be adapted to a wide range of operating conditions. Counting of normalized electron signals in digital storages allows an almost ideal image detection, which can, however, at best only be applied with a current density below 10 −13 A cm −2 . Compared to photographic recording, electronic systems offer real‐time response, compatibility with computers and great flexibility of stored information. Their DQE is similar in the analogue mode but superior in the counting mode. The storage capacity, on the other hand—particularly the number of pixels—is presently still inferior to the photoplate.