Abstract: A method of making the cathode of a diode image intensifier tube by evaporating some alkali metals and antimony on to the inner surface of a cathode window which by means of a layer of frit is joined to a metallic cathode flange, and in which there is provided between the cathode and the cathode flange, or, as the case may be, the cathode housing, an electrical resistance of a pre-determined value such that at light levels at which there is a danger of the anode being burnt, the diode image intensifier tube is defocussed or cut off, and wherein prior to the evaporation of the metals an alkali-resistant and insulating layer is applied to the frit layer, and that the evaporation of the antimony is carried out so that there is formed between the cathode and the cathode flange an area extending around the cathode and where no antimony is present, and that at least one galvanic connection is passed vacuum-tight outside the diode image intensifier tube, and one end of said connection is arranged at the place of the

Abstract: A method of making the cathode of a diode image intensifier tube by evaporating some alkali metals and antimony on to the inner surface of a cathode window which by means of a layer of frit is joined to a metallic cathode flange, and in which there is provided between the cathode and the cathode flange, or, as the case may be, the cathode housing, an electrical resistance of a pre-determined value such that at light levels at which there is a danger of the anode being burnt, the diode image intensifier tube is defocussed or cut off, and wherein prior to the evaporation of the metals an alkali-resistant and insulating layer is applied to the frit layer, and that the evaporation of the antimony is carried out so that there is formed between the cathode and the cathode flange an area extending around the cathode and where no antimony is present, and that at least one galvanic connection is passed vacuum-tight outside the diode image intensifier tube, and one end of said connection is arranged at the place of the

Abstract: An image intensifier tube device including a plurality of diode image intensifier tubes. Each tube comprises a sealed cylindrical envelope having its one end closed by an entry window carrying a photo-sensitive, electron emitting layer enclosed by a good electrically conductive rim. A resistive layer is deposited by vaporization between the circumference of the electron emitting layer and the good electrically conductive rim, which resistive layer is connected to a terminal of a voltage source having its other terminal connected to an anode and to focussing means of the tube such that in response to a sudden increase in the brightness of the image to be intensified a voltage drop is produced across the resistive layer, as a result of which the emitted electrons are de-focussed and/or deflected.