GB613189A - Image dissector - Google Patents

Abstract

613,189. Electron multipliers. FARNSWORTH TELEVISION & RADIO CORPORATION. June 14, 1946, No. 17962. Convention date, July 9, 1945. [Class 39 (i)] An image dissector tube has a translucent photo-sensitive cathode 4, Fig. 1, an annular anode 6 and an opposing electrode 5 which has a small area 10 of secondary emissive material adjacent an aperture 8, Fig. 2, or, alternatively, said material may cover the central portion of a wire (Fig. 4, not shown). A high-frequency alternating current is maintained between electrodes 4, 5, either by self-oscillation during operation or impressed by a generator 26. Electron multiplication of the stream from an elemental area of the photo-sensitive cathode takes place between the cathode and the secondary electron emissive area 10 before the multiplied stream passes through the aperture 8, under the action of the scanning coils 13, 14. The stream passing through the aperture 8 may be further passed through a static multiplier 35 before collection. In a modification (Fig. 6, not shown), the emissive material 10 and aperture 8 form an electrode separate from and in front of the remainder of electrode 5.