Cathodoluminescence has been described by several workers, often excited by a conventional electron gun1,2, or more recently using an electron microprobe3. This phenomenon can be produced by many materials, as described by Leverenz4, although the majority of recent reports have concerned themselves only with rare earth compounds. An attempt is described here to improve the efficiency of the excitation system for the production of cathodoluminescence and to investigate and compare the luminescence obtained from different compounds. For this purpose we have used the focussed electron beam furnace described by Unvala5which utilises a gun geometry similar to that suggested by Cole et al.6. This system is simple to construct and is sufficiently powerful to produce luminescence from compounds other than those of the rare earths and should offer a useful alternative to the more usual excitation systems.