Einrichtung zur Steuerung eines Lichtstrahles

摘要

Apparatus for steering a light beam, suitable for use in a track-following machine, in which two steering mirrors are each controlled by a servomechanism which determines the position of the mirror by counting interference fringes from an interferometer and which accelerates the mirror to the midpoint of its movement and then decelerates it, the approach to the final position being controlled asymmetrically in dependence upon the divergence from the set position to apply a larger force when the mirror is moving away from the required position.