Scientists reach telescope milestone

February 2011

Scientists working on a project to produce mirrors for the world’s largest telescope have reached a significant milestone.

Their success comes after the construction of one of the most advanced optical testing facilities in the UK at a cost of £1.5 million.

The 10m high tower has been assembled at Glyndŵr University’s research centre in St Asaph, where a project team is building prototype mirrors for the European Extremely Large Telescope.

The tower is needed to test the accuracy of polishing on seven 1.5m wide hexagonal mirrors to within one billionth of a metre - less than 1000 of the thickness of a human hair.

This is the level of accuracy set out by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), which has awarded the project team £4.5m to produce the prototypes.

Successful delivery of these will enable the team to compete for the final multi-million Euro contract for the construction of all 1148 of the telescope’s segmented mirrors.

The tower structure, complete with a myriad of highly sophisticated lenses and mirrors, has been assembled, aligned and rigorously tested in just one year.

Phil Harris, CEO of OpTIC Glyndŵr, which is operated by Glyndŵr University at St Asaph, said: “Completion of the test tower is a significant milestone for the project team.

“It is a fantastic achievement, which is all the more remarkable when considered that this is the first test structure of its kind to have been built in the UK to such exacting standards.

“The success of the project so far really is down to the hard work carried out by the company’s highly trained and motivated team of scientists and technicians,” he added.

“The team’s hard work, together with a manufacturing operating ethos, will ensure that the tight tolerances that ESO require for the Telescope project can be measured and achieved.”

Polishing of the mirrors prior to the testing stage is being carried out using a specially designed polishing machine produced by Zeeko Ltd.

The Leicester-based manufacturer is part of the academia-industry project consortium, which also includes University College London and Cranfield University.

Richard Freeman, Managing Director of Zeeko, said: “Producing a machine to the Optic Glyndŵr tolerances required for the ESO project was a significant achievement but we are delighted to have been successful and are continuing to provide support to the excellent National Facility for Large Optics at St Asaph.”

The next step for the project team is polishing of the first large segment of glass that will become the reference piece – or Master Spherical Segment - against which all future segments will be measured.

This is in progress and is expected to be completed within the next couple of months, after which construction of the first mirror segment will begin.

Mr Harris added: “We are now looking forward to the next exciting phase in delivery of this contract for ESO and ultimately contributing to procuring the eventual manufacturing contract for all of the mirrors required by ESO for the Telescope, which would secure high technology jobs for North Wales.”

The €1 billion E-ELT will be 30 times more sensitive than current optical telescopes and have a diameter of 42m when it is launched, currently estimated to be 2018.

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