The coherency of synchrotron radiation at Pohang Accelerator Laboratory

The coherency of the synchrotron radiation at Pohang Accelerator Laboratory has been investigated using Young's interferometer. The electron beam size can be measured precisely using the interferometer. An interferogram using 650 nm light at the diagnostics beamline at Pohang Light Source (PLS) has been measured to determine the electron beam distribution and the spatial coherence length. Interferograms obtained by numerical study are compared with experimental results in order to understand the measured data. From this comparison, the electron beam at PLS is revealed to be a Gaussian distribution with a standard deviation of 210 µm. The spatial coherency length of 650 nm light at PLS is measured to be 0.57 cm, and that of 0.1 nm light at PLS is predicted to be 0.88 µm by the same numerical study.