Abstract: An apparatus, in particular for balance training and/or fine motor training, includes at least one moveable platform, which is in at least two dimensions oscillatingly moveable, and at least one damping unit for a damping of movements of the moveable platform. The damping unit comprises a central connecting element, which extends at least partially along a zero axis of a rest position of the platform, for the connection of the platform and the damping unit and for a transfer of an at least two-dimensional movement of the platform.

Abstract: An apparatus, in particular for balance training and/or fine motor training, includes at least one moveable platform, which is in at least two dimensions oscillatingly moveable, and at least one damping unit for a damping of movements of the moveable platform. The damping unit comprises a central connecting element, which extends at least partially along a zero axis of a rest position of the platform, for the connection of the platform and the damping unit and for a transfer of an at least two-dimensional movement of the platform.

Abstract: A focussing error detection system is described for determining deviations between the plane of imaging of an objective system in an optical arrangement and the radiation-reflecting surface in said system. The apparatus comprises an optical element by means of which a radiation beam coming from the radiation reflecting surface is both rendered astigmatic and separated from a radiation beam which is directed to the radiation-reflecting surface. By the use of this element the number of components of the focussing-error detection system can be minimized and a compact construction of said system can be obtained.

Abstract: A device is described for determining the linear displacement of a machine tool component with the aid of a grating which is mechanically connected to the component, which grating is disposed in the light path between a light source and a light-sensitive element which converts the incident light into an electric signal. The light-sensitive element is a multiple photo-cell which consists of a row of line-shaped photo-diodes which by means of an electrical switch are consecutively connected to an electronic circuit which processes the signal which is produced in the photo-diodes.