Monoscope

a television camera tube used to transmit the single, stationary image of a television test pattern. It is used to check and tune television equipment.

The principle of operation of a monoscope is similar to that of an iconoscope. However, a monoscope lacks the iconoscope’s light-sensitive, mosaic target, which is replaced by an oxidized aluminum plate with a high coefficient of secondary emission. The image being transmitted is deposited on the target using a substance with a low coefficient of secondary emission. If the target is scanned by an electron beam, the number of secondary electrons leaving the target will change according to the difference in the secondary emission coefficient among individual elements of the target, and a video signal of the image will be generated in the plate circuit or the circuit of a secondary electron collector. Monoscopes also exist that operate according to the vidicon principle, with target scan by slow electrons.