Apparatus for characterizing the VUV and soft x‐ray optical elements at the Photon Factory

An apparatus dedicated to characterizing the VUV and soft x‐ray optical elements was fabricated, and a preliminary test on its performance was made in the soft x‐ray region with a grasshopper monochromator at the Photon Factory. The results demonstrated that quantitative evaluation of diffraction efficiency of a grating could be easily performed using the apparatus.