Thomson-csf

Patrick Volleau

Claude Bricot

Dominique Leterme

Michel Chaboche

Jean-Pierre Le Merer

Jean P Le Merer

Michel Audouin

The optical head in the recording-reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

Optical head in a device for recording and reading a data carrier

The optical head in the recording - reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

A device makes it possible to eliminate the imbalance of a deviating mirror of an optical system which illuminates a data medium or support when that mirror is subject to rapid displacement. The imbalance is cancelled by the use of a photodetector device which receives the light reflected by a reflecting element positioned around the objective of the optical system which illuminates the medium. A control device then makes it possible to control the position of the mirror based upon the light given off by the reflecting element.

Device for compensating the lack of balance of a deviating mirror

This invention concerns electrically controlled optical deflectors, and more specifically an optical deflector comprising a mirror forming part of an assembly which cam move in relation to a fixed base, the pivotal movements of this assembly being controlled by an electrodynamic motor with a winding through which a variable current passes, and which is situated inside a predetermined magnetic field, the mechanical connection between the movable assembly and the fixed base being provided by a prismatic elastic component. This invention applies in particular to the construction of reading heads to direct an optical beam on to a videodisc track.

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Paris, France

Patrick Volleau