Optical fibre with decoupling elements which decouple light directly

The light guide (10) has a light-conducting volume formed along the main propagation direction (x), and an interfacial out-coupling unit (14) which carries out out-coupling of light (16) through total internal reflection at the boundary surface at a predetermined angle with respect to the light exit surface of the light guide. The out-coupling element protrudes transversely from one side (26) of light-conducting volume to the main propagation direction, such that light exit surface is formed as a portion of the boundary surface of out-coupling element.