edges and is propagated to the exit at the light guide end from the quotient of the amount of light introduced to the amount of light issuing it is also possible to assume a value in respect of quality in which case quality in the optimum situation is one when therefore the amount of light which is fed into the light guide corresponds to the intensity lumens of the amount of light at the issuing end of the light guide the quality of light guides however depends not just on the material of the light guide or the nature of the light introduced but also on the way in which the light guide is laid if for example the light guide is laid along a straight line quality is generally greater than if the light guide is laid in various geometries involving winding serpentine configurations or arcs or other radii of curvature movement of the light guide transversely to the direction in which it extends also means that propagation of the light in the interior of the light guide is in part limited which has the result that the level of quality overall falls in accordance with the invention in case of.