Abstract: There is a described a free space optical signalling system in which data is transmitted from an optical transmitter to an optical receiver. The optical transmitter includes means for modulating one or more light beams in accordance with the data to be transmitted so as to generate a plurality of modulated light beams which are output from the optical transmitter as substantially collimated, spatially-separated, parallel free-space light beams. The optical receiver includes a plurality of detectors, each detector detecting a corresponding one of the plurality of modulated, parallel, free-space light beams and converting the detected light beam into a corresponding electrical signal from which the data can be recovered.

Abstract: There is described a signalling system operable to transmit data to a moving vehicle. The signalling system includes a first signalling device which is movable relative to a second signalling device by virtue of the first signalling device being mounted to a movable vehicle. One of the first and second signalling devices comprises a light source, a lens system for directing a light beam emitted by the light source in an exit direction within a field of view of the lens system, a detector for detecting the presence of the other signalling device, and means for varying the exit direction to align the optical beam with said other signalling device. By including the varying means, a low divergence light beam can be used which advantageously reduces the total power requirements. There is also described a financial transaction system in which low divergence free-space light beam is used to convey financial data.

Abstract: A linear bearing arrangement has a slider which slides in a channel in a slide and a layer of magnetic lubricant material which adheres to a magnetized region or regions of the slide, slider or both.

Abstract: This invention concerns a method of recording wide-band signals on a thermoplastic film. The signal to be recorded is converted to an intensity modulation of a beam of electrons which is directed at the surface of a thin thermoplastic film carried on a conductive substrate. The film is rotated in its own plane and simultaneously translated so that the beam scans the film in a track which follows a spiral path. The deposition of charge produces after heating of the film a spatial modulation of the film. The intensity of the beam and the beam's impingement on the film is controlled in order that the charge pattern is appropriate for the formation of a spiral groove which is substantially invariant in cross-section but varies in depth along its direction of progression in accordance with the signal that modulates the intensity of the beam of electrons. The recording thus made can be used for the production of video discs capable of mechanical playback.

Abstract: The vertical movement of a phonograph pick-up arm is controlled magnetically or electro-magnetically by means including a body of magnetic material attached to the arm and magnetic field producing means arranged to exert a force on the body.

Abstract: This invention concerns a method of recording wide-band signals on a thermoplastic film. The signal to be recorded is converted to an intensity modulation of a beam of electrons which is directed at the surface of a thin thermoplastic film carried on a conductive substrate. The film is rotated in its own plane and simultaneously translated so that the beam scans the film in a track which follows a spiral path. The deposition of charge produces after heating of the film a spatial modulation of the film. The intensity of the beam and the beam's impingement on the film is controlled in order that the charge pattern is appropriate for the formation of a spiral groove which is substantially invariant in cross-section but varies in depth along its direction of progression in accordance with the signal that modulates the intensity of the beam of electrons. The recording thus made can be used for the production of video discs capable of mechanical playback.