Illumination apparatus includes a light source which directs a polarized source beam in a downstream direction along an optical axis and desirably focuses the beam. The lead-in area includes a first lead-in information area and a second lead-in information area. The radio base station system comprises a first splitter device, which is connected to the first, the second and the third radio base station. As the original projections are free of errors generated by the reconstruction and visualization of the 3D-image, their consideration yields an improved geometrical accuracy. The structural unit encompassing the fixing sleeve and the at least one spring plate is fitted with an axially effective separating joint for a locking connection inside the structural unit.