Abstract: Electron gun having a source of electrons, means for forming the electrons into a beam directed along an axis, and an output electrode comprising a plurality of semi-cylindrical plates disposed coaxially of the axis of the beam. This electrode is part of the final lens of the gun, and voltages for deflecting the beam and correcting astigmatism are superposed on the plates of this electrode.

Abstract: There is disclosed apparatus for scanning a concave coded record which is adapted to be disposed in the inside of an open-ended tube. A rotor carries a source of illumination which illuminates the record. Light reflected from the record is reflected onto a mirror carried by the rotor and passes along the axis of rotation of the rotor through a suitable lens or lenses and is focused on a mask. The mask has an aperture through which light passes to a light receptor such as a photodetector. The light receptor is stationarily mounted to the frame. The frame also mounts a motor for driving the rotor and bearings for rotatably mounting the rotor. A cover adapted to abut the end of the tube is mounted for movement between one position in which the cover is in the reflected light path and another position in which the cover is out of the reflected light path.

Abstract: A device for measuring transmission factors is comprised of an emitter of light impulses located at a distance from a main photoreceiver. The emitter and the main photoreceiver are optically conjugated by mirrors. An auxiliary photoreceiver located adjacent to the light emitter receives a constant portion of the flux emitted by this emitter and a flux coming from the ambient light. By establishing the ratio between the impulse-type electric signals transmitted by these photoreceivers, a value proportional to the transmission factor measured between the emitter and the main photoreceiver is obtained.