Photocathodes for use in an electron image projector

In this paper factors influencing the choice of photocathode for an image projector are discussed. First of all, a description is given of the principles of operation of an image projector. It is shown that ionic insulators are likely to be the best materials, and the most likely ones are considered. Of these, cesium iodide is the best. In the last section a table is given comparing the observed properties of cesium iodide to those of palladium which has been used up to this time.