The performance of the optical elements at-wavelength measurement is affects by the synchrotron radiation beam divergence angle, and it is necessary to modulate a highly collimated X-ray as the measurement beam. In this paper, a multiple-crystal X-ray diffraction system composed by the channel-cut crystal, which is used to suppress the angular divergence of the synchrotron radiation beam. The Si(111) channel-cut crystal should work at the energy range of 10- 18keV, which can suppress the angular divergence of the beam lower than the Darwin width of the double crystals. The divergence angle was measured by the Si(111) analyzer is 2.9″@10keV at the vertical direction and 2.01″@18keV at the horizontal direction. The measurement results shows that the channel-cut crystal can suppress the synchrotron beam divergence angle and provide a high collimated light for the at-wavelength measurement of the optical components.
Driven by the growing demand for large-size x-ray mirrors used in synchrotron radiation and free-electron laser facilities, a linear deposition system based on magnetron sputtering technique is built. The layer growth quality and thickness uniformity are optimized by adding masks in front of the cathode to reduce the oblique-incidence particles and tune the sputtering flux distribution. Based on this, a 0.5-m-length W/Si multilayer mirror is demonstrated. The multilayer has a d-spacing of 3 nm and a bilayer number of 60. The surface roughness of the multilayer is only 0.33 to 0.25 nm in the spatial frequency range of 3.0 × 10 − 3 to 1.0 μm − 1, and the average interface width is 0.32 nm. The hard x-ray reflectivity and uniformity of the large mirror were characterized at the Optics Beamline in Shanghai Synchrotron Radiation Facility. A maximum reflectivity of 62.5% and 62.7% was measured at 8 and 18 keV, respectively, with an angular resolution of Δθ / θ = 2.7 % . The d-spacing uniformity over the 0.5-m-length and 60-mm-width area of the mirror is 1.0% and 1.2% (peak-to-valley), respectively. These results indicate a good and uniform quality of the nanoscale multilayer over the large mirror area. The measured second- and third-order reflectivities of the multilayer are more than 2 orders magnitude lower than the first order, implying a good suppression of high harmonics in the monochromator application.