GB1090406A - Improvements in or relating to image intensifiers and the like - Google Patents

Abstract

1,090,406. Electron multipliers; image converter tubes. MULLARD Ltd. June 25, 1964 [Aug. 19, 1963; Sept. 18, 1963], Nos. 32722/63 and 36758/63. Heading H1D. In an electron image intensifier comprising a matrix formed with an array of elongated channels having resistive and secondary-electron emissive surfaces extending between conductive input and output faces E 1 , E 2 of the matrix, photo-emissive surface areas are formed on the input face of the matrix or inside the channels thereof but extending to and contacting the input face. Electrons emitted by a photoemissive layer Pi on the input face are drawn into the channels by the accelerating field between E 1 and E 2 , but, if necessary, a transparent electron-reflecting electrode may be provided on the adjacent envelope wall. The input electrode E 1 ' may be light-reflective or transparent. Photo-emissive areas Pc may be formed inside the channels along 20% of their length, or along their full length if a material which is also secondary-electron-emissive is used. The matrix may be formed by glass tubes T 1 , T 2 sealed together with a transparent glaze G having a lower refractive index than the glass of the tubes, whereby light entering the tube walls may be subject to multiple internal reflections at least some of which may cause photo-emission, thus providing greater efficiency without loss of resolution. Alternatively, the sealing glaze may be opaque. The image intensifier may be manufactured or modified as described in Specifications 1,064,072; 1,064,073; 1,064,074; and 1,064,076. The matrix may be of glass and the electrodes E 1 , Eg and photoemissive areas of tin oxide or chromium, and antimony, respectively. After assembly in an envelope, the matrix is treated with caesium vapour to activate the photo-emissive areas and render the exposed channel surfaces resistive and secondary-emissive.