A device and a method are disclosed for visualizing positions on a surface by means of a marking which is produced by an optically detectable radiation. In order to permit a residue-free marking which can be observed with a camera from partly extremely oblique observation directions, the device has an optical waveguide, which is coupled to a radiation source and whose light output region can be located at a desired position of the surface in order to emit optically detectable radiation at the desired position of the surface through the optical waveguide. As a result, the radiation is emitted at the desired position of the surface in various spatial directions.