Some Aspects of the Design and Manufacture of a Fibre-optic Coupled Cascade Image Intensifier

Abstract

This chapter elaborates the design and manufacture of a fiber-optic-coupled cascade image intensifier. The principle of using fiber-optic windows on image-converter tubes to enable several to be cascaded to produce an image intensifier is well known. The major advantage accruing from the use of fiber-optic windows is that they allow the tubes to be coupled with better optical efficiency than would be obtained by the use of large aperture lenses and with a considerable saving in bulk and weight. In this study, it has been shown that the use of a fiber-optic plate with a curved input surface gives rise to appreciable radial nonuniformities in the transmitted flux from a Lambertian emitter such as a phosphor screen. Consequently, in the design of cascade intensifiers based on electrostatic self-focusing diodes, a compromise has to be made between the luminous-flux-gain uniformity and the distortion for a given field of view and overall length. A considerable improvement in the uniformity of luminous flux gain can be achieved at the expense of increasing distortion, but the corresponding improvement in output luminance uniformity is not so great because of the increasing contribution because of the magnification changes.