Rutherford Appleton Laboratory Case Study

Two OGP Smartscope Systems are Helping the Rutherford and Appleton Laboratory to fulfil its CERN Project Commitments and Provide Vital production information.

The CERN Project, a 3 mile wide underground particle accelerator which sits beneath and astride the Switzerland/France border, has helped to expand our understanding of the properties of energy but needs more down-to-earth technology to maintain its scientific value. Two Smartscope noncontact measuring systems, from leading vision systems specialist OGP, are ensuring that detectors used in the identification of emitted particles are aligned to within 2 microns and able to perform the specialised task required.

Plasma is accelerated to the speed of light in the ring of CERN under a vacuum, then the particles deliberately collided with others. An array of detectors, carefully positioned around the collision area, tracks the resulting particle matter, teaching scientists about the make up and behaviour of the universe itself. In such an environment, precision is of the utmost importance and, in the manufacture and positioning of the detector units, it is down to scientists at the Rutherford and Appleton Laboratory (RAL) in Oxfordshire to ensure that the quality is right.

Detector array manufacture takes many days in a slow, deliberately laborious process. Two photosensitive electronic detector plates are aligned with a TPG and beryllia baseboard on a special jig, then transferred to a floor standing Smartscope ZIP300 where the unit is checked for alignment using preinscribed crosses on the detector face. At this stage, 2D alignment has to be within 2 microns. Programming of the Smartscope, using its intuitive Measuremind software, allows the units to be automatically identified and compared with each other in relation to position and distance, whatever the orientation.

Providing the Smartscope passes the alignment, the detectors are glued into place and then the process is repeated for the addition of a further two offset detectors on the reverse of the module.

Once assembled, the module has to be checked for overall veracity and circles on the detectors are used by the Smartscope 250 to automatically calculate a virtual centre point which is compared with the same point on the reverse side,with sixteen sets measured over the entire module. The two sides must be within 5 microns of each other to pass through to the next stage.

Finally, a hybrid that has twelve electronic chips is glued to the module and wire-bonded into the assembly. The height and gradient of the wires is also critical and the Smartscopes are used to accurately measure height and profile to determine whether the module can be used in the array to be shipped to Switzerland.

Without measurement capability of the highest quality both in terms of consistency and reliability the departments work would be severely compromised. The processes involved in assembly alone can take three days, says Ozy Morris, at ASTeC (Accelerator Science and Technology Centre) at RAL, “everything is highly procedursed and it takes some special equipment to keep things on track. RAL relies heavily on the two Smartscopes and staff have been impressed by their accuracy and repeatability. It is often a matter of trust, goes on Ozy, apart from some minor teething troubles, which OGP dealt with quickly and efficiently, we have not had a single problem. He has been impressed with the advanced capabilities of both machines, particularly the self calibrating zoom lens that offers excellent accuracy on Z axis measurements.

The multi-sensor capability of the Smartscope 250 comes into its own on other components measured in the laboratory, some of which have a plain, white flat surface and therefore are difficult to light in order to pick up height variations on the surface. The laser gives a Z axis function that picks up fractions of a micron difference between points and the system plots the surface topography to analyse manufacturing variations. The Smartscopes are also used for 10,000 step programs on larger detectors from a sister laboratory, the machines often running for 24 hours a day.

The ease of programming with MeasureMind software has proved particularly effective in reducing cycle times and therefore increasing throughput with the same investment in staff and equipment. Ozy Morris was recently asked to use his experience of setting up the routines on the UK Smartscopes in the USA, where he was able to trim 75% from their overall measurement times on the same modules.

The Smartscope Zip 300 has been working without incident since the end of 1998 and the addition of the 250 in 2002 was almost a formality. We looked at the market and OGP was the name which came up for reliability and quality, says Ozy, but even so, we have been pleasantly surprised at the build quality and the robustness of the software, not to mention the competitiveness of their pricing. The relationship that has developed between the laboratory and OGP staff has also surprised Mr Morris; OGP staff are constantly in contact with us and are always there to offer help and advice when we need it.