Research on spatial coherence of undulator source in Shanghai synchrotron radiation facility

Abstract

Firstly, based on the Gaussian-schell model source theory and the propagation of cross-spectral density function in free space, the spatial coherence of undulator source (BL15U) in Shanghai Synchrotron Radiation Facility is studied. Secondly, the influences of pre-focusing mirror and the monochromator on the beam spatial coherence are discussed. Finally, the spatial coherent length at mono slit S2 is measured. The spatial coherent length at S2 theoretically is 66.5 μm, but experimentally is 27 μm. This difference is due to the high frequency vibration of pre-focusing mirror or monochromato. Nevertheless, high coherent hard X ray beams can be obtained at the location of experimental sample and many coherent experiments can be fulfilled on this beamline.