Image converter with alkali metal-activated photocathode - has alkali metal vapour-treated phosphor screen, preventing damage in operation

摘要

In an image converter (cf. CH 316 948) with an alkali metal, esp. Cs-activated photocathode and an output screen contg. an alkali metal-sensitive phosphor, pref. activated (ZnCd)s, the phosphor screen is treated with alkali metal vapour at max. 10-6 torr at a temp. of 70-100 degrees C and then exposed to the room atmos. before forming the actual photocathode. The output screen is protected from damaging attack by the alkali metal of the photocathode without the usual costs.