The optics of the beamline combines a normal incidence (NIM) and a grazing incidence (PGM) monochromator to provide an efficient harmonic rejection at low photon energies.
| Monochromator | NIM + PGM with collimated beam |
|---|---|
| NIM | 10 - 30 eV |
| PGM | 20 - 800 eV |
Table 3: Optics parameters
Figure 5: Optical concept of the SIS beamline combining the NIM and PGM monochromators with collimated beam.
The general concept of the SIS beamline in show in Figure 2. The first optical element is a sagittal mirror collimating the beam in the horizontal and vertical directions. The monochromator combines a normal incidence monochromator (NIM) and a plane grating monochromator (PGM). The collimated beam allows to vary the fix-focus constant Cff of the PGM as a free parameter without the need to move the exit slit. The NIM is used for the energy range of 10 - 30 eV and the PGM is used for 20 - 800 eV.