Thomson-csf

Louis Arquie

Michel Thirouard

Claude Bricot

Jean-Claude Lehureau

Dominique Leterme

Jean-Pierre Le Merer

A method which makes it possible to produce an optical device containing a semiconductor laser emitting a beam of parallel light which is positionally located with respect to a mechanical axis. It consists in positioning the laser with respect to an objective along three mutually orthogonal directions, and thereafter in assembling this laser and objective by means of bonding.

Optical device containing a semiconductor laser

The track of a videodisk is followed by a reading light beam produced by a device comprising a reading head fixed on a carriage which forms part of the moving system of a videodisk reader-recorder and is capable of radial displacement along the disk. An objective support frame is capable of displacement in a vertical direction with respect to the carriage in order to maintain focusing of the reading beam and of rotational displacement with respect to the carriage about a transverse axis at right angles to the radial and vertical axes in order to maintain the light beam on the track-following path. Flat coils located vertically in a plane parallel to the carriage path and placed within air-gaps of magnetic circuits serve to develop vertical forces which lift the reading head and initiate the vertical and rotational displacements by means of a differential supply circuit.

Moving system for a videodisk reader-recorder

A semiconductor laser source optical head for reading reflecting information carriers. The information is recorded on a track carried by the carrier in the form of a relief modulation. The device comprises a laser and an optical projection device for forming a reading spot which is an image of the source on the carrier. The laser is positioned on the optical axis of the optical device in such a way that the beam from the laser substantially illuminates half the entrance pupil of the optical system. The return beam reflected by the support emerges on the other half of the pupil. A deviating member is placed on the path of the return beam in order to displace the beam relative to the outward beam. Detection cells are conveniently placed in a detection plane parallel to the supports.

Semiconductor laser source optical reading head

An optical device for forming a stigmatic image of a laser source positioned at a predetermined point is intended to illuminate a reflecting surface while also providing a separation between the beam emerging from the source and the beam reflected from the surface. The device comprises a cube placed against a converging lens, the dimensions of the assembly thus formed being such that the cube face remote from the lens passes through a Weierstrass point of the spherical refracting surface formed by the lens. The laser source is positioned at the Weierstrass point. The cube is formed by two prisms cemented together, the interface being treated so as to have a polarization-separating effect.

Stigmatic optical device and an optical recording head equipped with

A device for providing access to information carried by a video disc comprises a fixed magnetic circuit having an air-gap which extends parallel to the radius of the disc. The access device is provided in addition with a low-weight moving system comprising at least one electric circuit forming a flat coil which is capable of sliding vertically within the air-gap and is so arranged that horizontal conductors are placed within the air-gap. Radial tracking and track-to-track transfer can be carried out by means of an electric circuit, at least one vertical conducting element of which is placed within the air-gap. Fast access is obtained by displacing this low-weight moving system.

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Paris, France

Louis Arquie