Some half-tone charge storage tubes

Four tubes are described which have been developed for use primarily in bright radar display systems. Two of the tubes are full-storage television camera tubes in which sufficient charge is stored to enable many reading scans to be performed before the charge is consumed. In the other two tubes a charge pattern is used to modulate an electron beam, the charge pattern itself remaining unchanged in the process. In the two former tubes and in one of the latter, the information to be stored must be supplied in the form of an optical image. In the fourth tube it must be supplied as an electrical signal. Continuous reading times ranging from a few seconds to several hours have been achieved. Resolutions of up to 700 spots per picture diameter are also reported. With some of the tubes, the erasure rates are readily controllable over a wide range.