SE332465B - - Google Patents

Abstract

1,164,894. Image intensifier tubes; electron multipliers. MULLARD Ltd. 29 March, 1967, No. 14225/67. Heading H1D. In an electronic imaging tube comprising a photo-cathode P spaced by a symmetrically disposed electron optical system from a channel intensifier device I, the channel intensifier is a secondary-emissive electron multiplier device which includes a plate, with conductive input and output layers E1 and E2 on opposite surfaces, and, passing through the plate, a large number of elongated channels all of which are parallel and inclined at a uniform angle # to the plane passing through the axis Z-Z and extending at right angles to the plane of the figure (termed the second main axial plane) such that none of the principal rays, which are the paths of those electrons leaving the photocathode at right angles to be brought to a focus in the focal plane F in front of the channel intensifier, is parallel to the axis of the corresponding channel. As shown in Fig. 3, the range of values for the angle # between a principal ray and a channel axis as measured from the channel axis never becomes or passes through zero, so that the formation of a dark spot is avoided by preventing electrons from being able to pass straight through a channel without undergoing any multiplication. In a particular example given the angle of inclination of the channels # is 15% and the angle # varies from 3 degrees at one edge to 27 degrees at the opposite edge of the channel intensifier. The imaging tube may be an image intensifier or image converter tube with a luminescent screen S which may be suitably biased to accelerate the electrons after they have left the field in the channels, and the electron-optical system may be of the diode type with a conical anode A electrically connected to the input layer E1 or triode type when not so connected. The channel intensifier I may, as described in Specification 1,164,895, be curved with the concave face towards the photo-cathode to more nearly conform to the shape of the focal plane F, and shaped fibre optic units (FO1) and (FO2) may be employed between the object and photo-cathode and as a faceplate for the viewing screen S, which may also be curved, Fig. 5 (not shown).