Beam transverse size and emittance measurement of HLS Ⅱ using interferometry

With the purpose of measuring small beam size of HLS Ⅱ after upgrade, a beam transverse size and emittance measurement system of HLS Ⅱ has been developed. This paper introduces briefly the principle of measuring beam transverse size using interferometry in visible light. It illustrates in detail the software system, hardware system and the image processing algorithm of the measurement system. In order to eliminate the background noise of CCD, a lookup table between the background noise of CCD and the beam intensity has been established. In conclusion, the experiment results are presented at multi-bunch mode. The measured beam horizontal size is 265 m and the measurement error is 5.78 m, and the beam vertical size is 114 m and the measurement error is 4.89 m.