The Image Iconoscope

An iconoscope having increased sensitivity is to be desired for purposes of improving studio conditions, making possible more universal outdoor work, and permitting greater depths of focus. The new tube described obtains its high sensitivity by making use of an electron image of the scene to be transmitted, projected onto a scanned mosaic. The method permits more efficient and better photocathodes, and also secondary-emission image intensification at the mosaic, resulting in a sensitivity 6 to 10 times greater than that of the standard iconoscope operated under the same conditions. The translucent photocathode is made by evaporating silver on a transparent surface, oxidizing, treating with caesium, and evaporating more silver. The electron image may be focused by either electrostatic or magnetic fields. Several types of mosaics are suitable for receiving and storing the electron picture.