Cranfield’s atomic telescope

Posted on 11 Jun 2010 by The Manufacturer

Cranfield University has begun making seven mirror segments for the for the world's biggest telescope, the European Extremely Large Telescope.

The E-ELT is a 42m diameter ground-based telescope made up of 1,000 hexagonal segments, each 1.4m wide and just 5cm thick. At almost half the length of a soccer pitch in diameter, the E-ELT is four to five times bigger than the largest optical telescopes operating today, and will gather 15 times more light. The mirror segments are polished to an atomic level of accuracy.

The giant telescope will tackle some big scientific challenges and is aiming for a number of firsts, including tracking down Earth-like planets around other stars in the habitable zones of space where life could exist — one of the Holy Grails of observational astronomy. It will perform ‘stellar archaeology’ in nearby galaxies, and make fundamental contributions to cosmology by measuring the properties of the first stars and galaxies, and probing the nature of dark matter and dark energy.

It is also expected that the telescope will tackle new and unforeseeable questions which are expected to arise from new discoveries made with the E-ELT.

Cranfield University claims to be the only university in the UK with the capability to undertake the various stages of the machining process for the mirror segments to the accuracy required. Designed and developed at Cranfield specifically for realising these mirrors, the BoX, or Big OptiX, machine has the ability to grind large optics in a matter of hours. Also carried out on site at the university, the process is completed with a final machining phase using the Reactive Atom Plasma Technology (RAPT) machine which allows final polishing of the surface of the component to an atomic level of accuracy to remove any imperfections of the final surface.

Professor Paul Shore, head of the Cranfield Precision Engineering Centre, said: “At Cranfield we will be measuring the mirrors to ensure their accuracy, then grinding and mounting the feet that support them. They will then be moved to Technium Optic (Opto-electronics Technology and Incubation Centre) in North Wales, the location of our Integrated Knowledge Centre in Ultra Precision and Structured Surfaces, where they will be polished to a form accuracy of 25 nanometres.”

The large telescope project expects to open the doors for sustainable, beyond-research manufacturing potential. “There is a potential order, worth approx Eu250m, from the European Space Organisation for the E-ELT mirror segments,” says Prof Shore. “Through a RCUK and EPSRC [science research council]-funded collaboration between Cranfield, UCL, and three companies – Zeeko, Optic Glyndwr and Qioptiq – there is an improving chance that UK manufacturers will get some or all of this ESO contract.

“At this time there is a very strong, part-government owned French competitor and two or three US competitors hailing from the US defence sectors. Clearly in delivering this large scale contract, the so-called competitors can also be considered potential contract delivery partners. In either case the UK is now significantly well placed to enter the emerging and growing market for large scale ultra precision surfaces.”