June 19 2015
Scientists finish polishing mirrors for £900m telescope
Picture: The OpTIC Centre team with Marc Cayrel from European Southern Observatory (ESO)
WORLD-LEADING scientists have successfully finished polishing prototype mirrors for the world’s largest telescope.
The team at Glyndŵr University’s OpTIC Centre in St Asaph were chosen by the European Southern Observatory (ESO) to deliver segments for the £900m European-Extremely Large Telescope (E-ELT) in 2011.
For four years they have been busy polishing the series of mirrors down to less than 7.5 nanometres – the size of a haemoglobin module –quickening the process with every milestone in preparation for manufacturing.
Project leader Caroline Gray paid tribute to the team at the Denbighshire science and technology complex and said this is a “huge” achievement for the University.
“The challenge of this latest work was the application of our processes to a round segment - one that had not been previously cut to the previous hexagonal shape - coupled with specific levels of mid-spatial conformance,” said Caroline.
“The three segments we had done were all accepted against phase two, which was a remarkable achievement, and meeting this latest milestone – the round piece of glass - has shown that our process can deliver to this interim stage within an extremely demanding time frame.”
She added: “We have met the needs of ESO and are delighted with that; it was not easy and many obstacles have come our way, but we have overcome them.
However, she admitted “work starts now” on the next phase of the multi-million pound project – finding a collaborator to produce up to 1,000 of the lenses for the E-ELT.
“The search is now on for collaborators who can take the processes through to a true manufacturing status,” said Caroline.
One of the key undertakings before work even began on polishing the mirrors was constructing an optical test tower compliant with ESO specifications – the only one of its kind in the world.
The group successfully achieved that but must now adapt to a new mirror design required for the final specification of the E-ELT primary mirror, which is essentially the conversion from an 84 metre radius to a 69 metre radius.
“We have come a long way but works starts now on taking what we’ve learned to the next level,” said Caroline.
“This has been another major success for the ESO project team and for the University, further securing our reputation as a world class optical manufacturing group.”
Due for completion in 2024, the giant eye on the sky will be sited in Chile and was given the green light in November.
Last year, the group received global acclaim for polishing the 1.5m optic down to just 7.5 nanometres, the best measurement ever managed in the UK, and the first time such a feat has ever been achieved using computer-operated machinery, coupled with Glyndŵr University’s unique polishing process and metrology system
Once completed, the E-ELT will gather light from distant stars and galaxies, be 39 metres in diameter, made of 798 segments and located on Mount Cerro Armazones in Chile, where it is set to gather 15 times more light than the largest telescopes around today.
Work is well underway on blasting away part of the 3,000m mountain’s peak and on completing access road infrastructure to support the new observatory.