GB1395441A - Image intensifiers - Google Patents

Abstract

1395441 Image intensifier tubes; electron multipliers MULLARD Ltd 18 Jan 1973 2678/73 Addition to 1175599 Heading HID An image intensifier tube comprises in combination a channel plate as claimed in any one of claims 1 to 4 of the parent Specification, a photo-cathode spaced from the input face of the plate, and a display screen, wherein the channel plate input face comprising the conductive membranes is substantially non-reflective of radiation of wavelengths to which the photocathode is sensitive. The membrane may be continuous, superposed on the input electrode as in Fig. 2, or insulated from the input electrode to be at a different potential as in Fig. 3 (not shown). Alternatively membranes may be extensions of the input electrode to form together a continuous layer, Fig. 4 (not shown). Opaqueness of membranes to visible and U.V. radi tion inhibits feedback from a display screen which then requires no metal backing. Membranes D may be separate elements with their edges in electrical contact with input electrode in which ease the latter are also non- reflective. A continuous layer may include a self-supporting layer or film of A1 which is crystalline (non-reflective) and a second layer of amorphous A1 (non-reflective or "black"). In fabrication, a lacquer film is produced by flotation on water, placed over an input face in Figs. 2, 3 or on a glass substrate for the Fig. 4 device, followed by evaporation of the A1. For a glass matrix reduction of a metal (e.g. Pb) compound in the matrix for the requisite conductivity, may be repeated after final baking of the second layer in air or oxygen or can be postponed until after baking. The first A1 layer should be 200 Š thick. The second A1 layer is also evaporated but in an inert gas (e.g. nitrogen at 0À05 torr), the lacquer then being burned off. The amorphous layer thickness may be assessed by reflection of a glowing filament and is preferably 300 to 800 Š thick. Channel plate specifications are given with an A1 film Df 500 to 1000 Š thick. Image intensifier tubes of "proximity" and "inverter" type are exemplified.