While at the Synchrotron Lab for part of winter vacation in 2004, I designed and built most of the hardware and circuitry for this system. I installed it to inspect the position of the x-ray beams in the G-line x-ray diffraction facility.
It uses electronically actuated pneumatic valves and pistons to move phosphorous screens into the two beams. The x-rays illuminate the screens which are viewed by two CCD cameras.
The system worked very nicely, allowing an operator to remotely insert and remove the screens, and visually monitor the beam position with the cameras.