Automatic alignment of focussing X-ray optical elements

One of the most challenging tasks of automatic beamline alignment (ABA) is the automatic alignment of focussing X-ray optical elements (OEs), such as cylindrically bent mirrors and sagittally bent monochromators. The alignment of these OEs is often time-consuming and requires expert knowledge. An automatic alignment tool would not only decrease the time spent by beamline staff on alignment but also allow non-expert beamline operators (i.e. users) to align the beamline. Since beamlines at synchrotron radiation need to be regularly aligned and focussing OEs are omni-present, such a tool would allow beamlines to keep optimal performances more constantly.

An general purpose ABA tool is under development at the ESRF. Methods and results will be presented from the application of this tool on two ESRF beamlines with cylindrically bent mirrors (BM14 and ID14 exp. hutch 4) as well as tests on a sagittally bent monochromator on BM5. On BM14 a version of this tool has been run regularly by the beamline staff. The tool has also been used for slit alignment on BM16.

Details of the current development of the ABA tool will also be given. The tool itself consists of four parts: A set of expert system rules for the overall control, a Java program containing the expert system and the interfaces to the beamline and the user, a general purpose scientific analysis program (Yorick) and a beamline simulator. The beamline simulator is not used while using the tool on a beamline, but thanks to this simulator it has been possible to develop alignment strategies off-line that could be run without modifications on the beamlines.