Performance measurement for variable-included-angle plane grating monochromators

A simple variable-included-angle plane grating monochromator(VAPGM) has been installed in Shanghai Synchrotron Radiation Facility(SSRF).High accuracy of this monochromator is needed under the ultra-high vacuum environment.Measurement and calibration are very important.The rotation-angle-accuracy measurement,repeatability of the light spot transversal shift and the grating switching mechanism are investigated by auto-collimation method in this paper.The performance of the VAPGM is successfully achieved out of beamline.The results show that rotation-angle-accuracies of the plane mirror(PM) and the plane grating(PG) are measured to be 0.19″and 0.22″,respectively,satisfying the technical requirement of 0.43″.The repeatability of the grating switching mechanism and the light spot transversal shift also satisfying the technical requirements.Experimental results further indicate that the measurement method is effective.