Comprehensive 1D and 2D UHV lens changer at PETRA III beamlines

For beam collimation and focusing at the new PETRA III undulator beamlines, UHV compatible 1D and 2D compound refractive lens changers have been designed. Since these units are going to be integrated in the upstream part of the beamlines in the optics hutches, the primary design goal was to ensure reliability, failsafe operation and convenient optical alignment combined with high mechanical precision. It was chosen to further develop established concepts and combine it with actuators on the air side rather than active in-vacuum actuators. Precise and reproducible alignment is achieved by pneumatic linear motion actuators that position the lens stacks in a high precision prism. Alignment is facilitated by on-axis pinholes and an integrated diamond beam monitor. Reproducibility and first tests of a 1D lens changer at beamline P22 for intermediate focusing down to <90 µm are shown.