Abstract: A picture display device having a cathode which includes two electric current conductors between which a video signal is applied, for applying a video signal to the cathode to modulate an electron beam emitted from the cathode. To increase the feasible modulation frequency, the inductance of the two electric conductors is reduced by holding one part of the length of the conductors closer together than their spacing over another part of the same length.

Abstract: An oxide cathode comprising a base 1 which consists substantially of titanium and a heater element 5 coated with aluminium oxide 6 to heat the base 1, which bears a porous alkaline earth metal oxide emissive layer 4. When the surface of the titanium base 1 which is opposed to the heater element 5 bears a metal layer 7 consisting at least of one of the metals Pt, Mo, Ta and W, a solution is obtained to the problem occurring in titanium cathodes in that titanium in contact with aluminium oxide is not chemically stable. The metal layer preferably consisits of pure tungsten and is formed by chemical vapour desposition (CVD). The metal layer is preferably from 1 to 10 .mu.m thick.

Abstract: A method of producing a dispenser cathode provided with a top layer, in which a main body of tungsten powder is pressed to a moulding at a first pressing pressure which is sufficient to preserve the shape of the moulding when the first pressure is removed but is not sufficient to break the powder grains to a significant extent. This moulding is thereafter provided with a top layer of a second power, whereafter the overall assembly is compressed in a second pressing operation at a second, higher pressing pressure, at which pressure the powder grains are broken to a significant extent.

Abstract: A contact for a semiconductor cathode is produced by thermally bonding leads consisting of one of the metals Ag, Au, Cu and one of the metals Ta, Ti, V. Such a contact does not exhibit degradation when the cathode, after mounting in a vacuum tube, is heated several times to approximately 850.degree. C. for cleaning purposes.

Abstract: A predetermined number of optical fibre parts (27) is provided on a rectangular frame (1), the fibre parts extending parallel to each other along a straight line between two opposite first sides (3) of the frame. These first sides (3) comprise comb-shaped fibre guides (5) with teeth (13), between which the fibre parts (27) are guided so that the fibre guides determine a first relative distance between the fibre parts. The first sides (3) are pivotably connected to the two second sides (7) of the frame (1), which is then deformed to a parallelogram until the portions of the fibre parts (27) located inside the frame have a predetermined second relative distance. A permanent connection between the fibre parts (27) is established so that a ribbon of fibre parts is obtained. A number of such ribbons can be stacked with the interposition of strip-shaped spacers (29) to form a bundle.

Abstract: A dispenser cathode body is manufactured from a sintered metallic powder. A large scandium oxide concentration is provided beneath an emissive surface of the body, resulting in increased life, increased current density, and decreased sensitivity to ion bombardment.

Abstract: A beam splitting prism assembly in which at least some of the prisms are separated by an air gap, optionally connected at the edges through the beam splitting layers by means of strips of a thermo-plastic material.

Abstract: A beam splitting prism assembly in which at least some of the prisms are separated by an air gap, optionally connected at the edges through the beam splitting layers by means of strips of a thermo-plastic material.