Bunch Resolved 2D Diagnostics Streaking Combined with Interferometry

Due to the complexity of the filling pattern in the BESSY II electron storage ring, bunch resolved diagnostics are required for machine commissioning and to ensure the long term quality and stability of operation. In addition, low alpha operation and a possible VSR upgrade demand bunch length measurements with picosecond resolution. Therefore, a dedicated beamline equipped with a fast streak camera was set up and successfully commissioned. Couplings between time and space coordinates also call for bunch selective and correlated multi parameter detection methods. Thus, the beamline and the streak camera have been made capable of direct beam profile imaging and interferometry of the vertical beam size using the X ray blocker baffle method , . The horizontal or vertical dimension can additionally be imaged with the streak camera and bunch resolved 2D measurements are possible. Imaging the vertical direction, the characteristic dip in the center the interference pattern from pi polarized synchrotron radiation can be observed and is used to extract bunch resolved information about the vertical beam size. The streak camera measurements are validated with direct imaging measurements from a regular CCD camera at the beamline and compared to model calculations. The results are converted into absolute values by a calibration with the BESSY II pinhole monitor