Abstract: Photocathode having a transparent conductive undercoating to provide a radial voltage distribution across the cathode surface. The conductive undercoating is in the form of radially spaced rings made of chromium deposited on a glass substrate. Over the substrate and the conducting undercoating is provided a resistive layer comprising chromium having a thickness of about 50 Angstroms. Over the resistive chromium layer is deposited a photoemissive layer of antimony, potassium, sodium and cesium. The radially spaced conductive rings are connected to sources of different voltage to produce a desired voltage distribution across the resistive chromium layer.