The low-energy toroidal grating monochromator beamline at the synchrotron radiation source at Daresbury Laboratory

The bending magnet beam line 1.2 low-energy toroidal grating monochromator of the synchrotron radiation source (SRS) at Daresbury Laboratory, was designed1 to deliver moderately high fluxes (∼ 5 × 1011 photons s−1), of linearly polarized, medium resolution (∼0.2 eV) radiation in the energy range 5–85 eV. The colinear optical system utilizes platinum-coated silicon-carbide mirrors to focus the broad-band radiation emergent from the SRS at the entrance slits of the three grating monochromator. A single ellipsoidal mirror is then used to doubly focus the desired narrow-band radiation at the sample position. The colinear arrangement of the optical elements ensures that the radiation at the sample point is strongly horizontally plane polarized (estimated to be of order 90%). The entire system has been the subject of detailed analyses using the raytracing program shadow,2 and standard optical theory. These calculations have been compared with experimental determinations of photon flux outputs and resolution measurements.