Abstract: In articulated optical systems, rotation of the image takes place due to the articulations. The invention eliminates this disadvantage by producing a signal whose polarity is dependent on the direction of rotation in which the image produced in the observation plane (64) is turned with respect to the object. By the signal, a compensation element (72) arranged in the articulated optical system is turned until the signal has disappeared. Two devices are disclosed for producing the signal: 1. At the start of the articulated optical system a mark (16) is introduced by reflection, it being focused at the end of the articulated optical system on a sensor (67). 2. On all articulations there are arranged position transmitters (111,112, etc.) which are connected with a minicomputer (130) which calculates the resultant image rotation and gives off a corresponding signal via a digital analog converter (131).

Abstract: The invention contemplates a micromanipulator as for the manipulation of a vitrectomy instrument, wherein a single remotely operable control means is effective through three independent spherical-coordinate servoelectric drives to selectively control the operative end of the instrument, within an operating volume defined by spherical coordinates centered at a fixed point of origin; in a vitrectomy, the fixed point of origin is illustratively the point of surgical entry through the pars plana of the eye.