Diamond is in motion

Diamond is in motion

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The Diamond Light Source synchrotron ring in Oxfordshire welcomed it first users in February this year. Seven beamlines are now functional and more are on the way at this globally important research facility. Supplying the motion control for the project has been a challenge for Delta Tau that reports it has now installed over 600 axes of motion at the project.

The light generated within the synchrotron ring is directed to beamlines and accelerated using bending magnets located at the insertion points around the storage ring. Once the light enters the beamline, it is guided, intensified or deintesified using series of slits, lenses and crystals; the angles and positions of which are dictated using electric motors whose motion commands are generated by Delta Tau controls. While most of the electric motors used are stepping types, there are also AC and brushed DC servo motors together with some piezo electric motors for fine adjustments. The same Delta Tau motion controllers handle all these mixed motor technologies.

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In addition to the beam adjustment mechanisms, there are workholding and manipulation tools whose motion is controlled. These can include hexapod positioning stages whose six axis motion control uses complicated inverse kinematics calculations carried out a breathtaking speed within the Delta Tau PMAC centralised controllers.

The UMAC (Universal Motion and Automation Controller) is a modular PMAC system built with a set of 3U-format Eurocards. The configuration of any UMAC system starts with the selection of the PMAC CPU or MACRO optical fibre interface and continues with the addition of the necessary axes boards, I/O boards, communication interfaces (USB, Ethernet, etc.) and any other interface boards selected from the rich variety of available accessories. For example, accessory boards interface with virtually any kind of feedback sensor or to implement almost any kind of communication method with the host computer or external devices. The devices are therefore sufficiently flexible to accommodate any of the requirements encountered within each beamline.

One example of this is in the manipulation of a double crystal monochromic system. Here, the Delta Tau PMAC enables a virtual axis to be created to enable the two crystals to position in relation to each other. This is achieved in such a way as to maintain a straight beam even when the first crystal is positioned to deflect the beam – such as when monochromatically filtering white light by Bragg diffraction for specific inspection tasks. The PMAC recognises the virtual axis as theoretical and is able to calculate the real life motions required for each crystal’s axis.