2005 - Large optical quality precision surfaces can be manufactured in a variety of ways. The adjacent picture shows a 700mm diameter mirror mould being diamond turned on LDTM at Cranfield Precision. The surface will be replicated many times to produce elements of the H.E.S.S. Phase II telescope.
A 1-metre mirror segment manufactured using traditional methods to nanometric levels of precision can take several months to complete. The timescale for machining hundreds of segments for large telescopes would be long even by the standards normally encountered in astronomy research programmes. Cranfield Precision worked within the EPSRC sponsored programme entitled "Ultra Precision Surfaces: a new paradigm" with University College London, Cranfield University, RAPT Industries, OpTic Technium and UKATC to establish a manufacturing chain that reduced significantly the time taken to complete mirror segments. Part of this work involved the design & development of the
BoX (Big OptiX) machine. Many of the innovative machine design principles developed for earlier Cranfield Precision machines including self compensating linear hydrostatics and the use of polymer concrete were incorporated to support the over-riding design ambition of low moving mass and high stiffness. The machining conditions which were created ensured minimum subsurface damage during material removal. Subsequent polishing and figuring times, as a consequence have been shown to be shorter.
BoX is a UK trademark of Cranfield University (No 2389252).
Cranfield University patent pending (App.No. GB0508695).
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