Beamline commissioning started in June 2010. Focusing and stability of the M1A/B mirrors under full undulator power conditions have been tested. Absorption measurements with monochromatic X-rays (C-06 cell of the beamline) have been used to characterize the energy/angle curve of the four gratings already installed (G1-G4), covering the 50-1500eV range. Also, the VGD (variable groove depth) behaviour has been addressed. VGD gratings feature a groove depth that depends on the lateral position. Since the photon beam has a very small lateral size at the grating (about 200 microns), by adjusting the lateral position of the grating one can choose a precise value for the groove depth, with different efficiencies for first and second order scattering. Therefore, one can maximize either throughput or spectral purity.
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