a leached fiber bundle with the light outlet points positioned as accurately as possible is provided , in which the end faces are not completely fused together , but rather are only fused together at their contact surfaces . the interstices formed are permanently filled with adhesives with the aid of a pressure reduction . to protect the optical fibers from mechanical load , adhesives are introduced into the transition region between the fixed end region and a flexible region . this allows the leached fiber bundles to be produced more economically and also improves their service life .