Beam size measurement of BEPCⅡ storage ring by using visible synchrotron light interferometry

The vertical beam size of BEPCⅡstorage ring was measured by using visible synchrotron light spatial interference method, and the measured size is 155 μm. The measurement results fit well with the calculation predication. This method can avoid the measurement error caused by synchrotron light diffraction and makes the measurement results more accurate. In addition, the method is applicable to other small size incoherent light source.