X-ray beam-position monitoring in the sub-micrometre and sub-second regime

It is demonstrated that X- ray beam positions can be extracted from two-dimensional profiles with sub- pixel resolution. Beam- position measurements utilizing a self- designed low- cost two- dimensional detector have been performed at two synchrotron radiation beamlines of the Swiss Light Source. The effective detector pixel size was 4.8 mu m and the resolution achieved for the beam position was about 5 nm. At a data rate of 25 frames per second, periodic variations of the beam position could be detected with a frequency resolution below 0.1 Hz. This allowed, for example, the influence of a turbo- pump in the X- ray optics hutch on the beam position to be quantified, and even minute variations related to the electron beam in the storage ring could be detected.