The beamsplitter narrows the beam to more useful dimensions, as it comes from the source. The components depicted in red in the pictures below, are the internal parts that is exposed to the beam and do the actual narrowing.



All components before the beamsplitter (beamsplitter included) are aligned on the -6.5 mrad direction. Downstream, they are aligned along the -8 mrad direction. The soft radiation centered on the –4 mrad direction is presently blocked both inside the beamsplitter (see red part on the figure) and outside (lead block visible on the picture).