E-ELT Prototype Segments
The National Facility operated by Glyndwr University is developing process and metrology technologies, and manufacturing prototype mirror segments, for what will be the world’s largest optical telescope project – the 39m aperture European Extremely Large Telescope (“E-ELT”). The prototype segment project is described in several recent publications here.
The invited SPIE newsroom article (April 2013) gives a good overview here
The first completed segment (designated SPN04) has successfully been though its pass-off tests at OpTIC, witnessed by ESO staff. An unqualified Certificate of Acceptance was subsequently received.
Find out more about the new mirror process for the world's largest telescope
Polishing the Master Spherical Segment
This 1.4m across corners, Zerodur, hexagonal Spherical Mirror has an 84m radius of curvature. This mirror is the master reference artefact against which E-ELT prototype segments are compared.
It was polished to the required 18nm RMS (surface) on the Zeeko IRP1600 machine at the National Facility.
It is particularly smooth, exhibiting 5.5nm RMS for spatial scales <250mm, and 4.2nm RMS for scales <100mm.
Prototype Full-size E-ELT segment
This shows one of the off-axis aspheric prototype segments on its hydrostatic support system, under inspection in the National Facility.
The segments are only 50mm thick, and require a support-system that:-