GB1411718A - Electro-optical viewing device - Google Patents

Abstract

1411718 Viewing assembly S R CAPSEY (International Telephone & Telegraph Corp) 30 Jan 1973 4595/73 Heading H4F Image intensifier viewing assembly for low light levels or infra-red radiation comprises a housing 10 in which an image intensifier 18 with its power supply circuit 25 is rigidly mounted, e.g. embedded in a hardened epoxy resin 26, an adjustable focus objective lens system 30 being detachably mounted on the housing at the input end, and an adjustable focus eyepiece system 24 being detachably mounted on the housing at the viewing end. The image intensifier includes a planar fibre optic faceplate 14 with a photocathode 16 on its internal face, a micro-channel plate electron multiplier 18 and an output fibre optic bundle display screen 20 with a phosphor coating on its inner face and having a 180 degree twist. The power supply circuit includes an oscillator, voltage multiplier and internal leads and supplies direct voltages to the photocathode, electron multiplier and phosphor coating. By precise optical measurement techniques during the potting of the housing and intensifier as an integral unit, a collimation adjustment is made before the resin 26 hardens to provide axial alignment. Interchangeable eyepieces 24 are screw-threaded 32 on to the housing, the threaded engagement providing adjustable focusing. The objective lens assembly 30 is secured to the housing by a collar 36, accurately collimated by screws 38 and plate 48 with the housing-intensifier unit, and including a focus adjustment ring 40 rotatably mounted thereon. Focus adjustment may be effected between two fixed positions at which ball 52, which rides on a cam surface 54, engages respective detents therein. Two such viewing assemblies may be adjustably mounted on a frame adjacent each other to form a binocular viewing device, close targets being illuminated by an infra-red source mounted on the frame.