A device for transmitting modulated optical signals between a first unit and a second unit, in which the first unit is supported to be rotatable or movable linearly relative to the second unit, comprises a light guide extending along a given track on the first unit, a first light coupler for coupling light into and out of the light guide, and a second light coupler disposed on the second unit and movable relative to the light guide for coupling light into and out of the light guide. A coupling slide is provided for supporting the second light coupler, and is mechanically loosely connected to the second unit via a take-up unit so that the coupling slide is moved along the given track together with the second unit by a movement of the second unit.