Abstract: 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.

Abstract: An optical device for recording and reading on a data carrier is provided with first optical means forming a composite source of radiant energy comprising a first semiconductor-laser source for producing a polarized reading beam, a second semiconductor-laser source for producing a polarized recording beam, the two directions of polarization being at right angles to each other, and an optical element for combining the two beams followed by a polarizer. The device is also provided with second optical means comprising an optical separating element, a quarter-wave plate and an optical system for focusing the two reading and recording components after reflection from the tracks of the disk on two distinct zones of an optoelectronic detection device.