Automatic Beam Alignment at Daresbury

Why are we trying to achieve automatic beam-alignment? Firstly, considerable timesaving can be made during a user set-up and a more reproducible and reliable alignment should result. This is especially important on today's sources and high turn over stations. Secondly, if the procedure can be made reliable enough a user may be able to realign a station during out of hours' operation.

We have identified three stages to the alignment project:

• Alignment from an unknown position (possibly with no beam visible) to a point where the beam impinges on an optical element and further optimisation can proceed.

• Optimising the beam on any particular optical element. (OE)

• Keeping the beam optimised during an experiment.

We will present three examples of beam-lines, which present varying degrees of complexity in terms of beam alignment, however, many of the optical elements are common. E.g. slits, mirrors, monochromators, sample tables and detectors. Some possibilities for automatic alignment will be described;

• Optimisation of beam clipping slits.

• Alignment of a sample table to beam.

• Focussing of beam using a triangular crystal monochromator and mirror.

• Focussing of a torodial mirror.

• Alignment/focussing of a double crystal saggital focussing monochromator.

We decided to build a system which would reflect the real world. Our aim is to create a flexible system of reusable components (a toolkit) which could be assembled in a plug and play fashion. To date we have created an underlying framework for the creation and operation of OE objects. We will describe some examples of these e.g. Slits and tables. Part of this work has been collaboration with the ESRF/Trieste to make these work with an ABA system.