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Please use this identifier to cite or link to this item: http://dspace.lib.cranfield.ac.uk/handle/1826/7371

Document Type: Conference paper
Title: Surface quality of a 1m Zerodur part using an effective grinding mode
Authors: Tonnellier, Xavier
Shore, Paul
Morantz, Paul
Orton, D.
Issue Date: 11-Jul-2012
Citation: X. Tonnelliera, P. Shorea, P. Morantza and D. Orton. Surface quality of a 1m Zerodur part using an effective grinding mode. Proceedings of SPIE Optical Fabrication, Testing, and Metrology III, Tuesday 2 September 2008, Glasgow, United Kingdom, 7102, 71020B (2008). Eds. Angela Duparré, Roland Geyl
Abstract: A new ultra precision large optics grinding machine, BoX(R), has been developed at Cranfield University. This machine is located at the UK's Ultra Precision Surfaces laboratory at the OpTIC Technium, North Wales. This machine offers a rapid and economic solution for grinding large off-axis aspherical and free-form optical components. This paper presents an analysis of surface and subsurface damage assessments of Zerodur(R) ground using diamond resin bonded grinding wheels. Zerodur(R)was tested as it is one of the materials currently under study for making extremely large telescope (ELT) segmented mirrors such as in the E- ELT project. The grinding experiments have been conducted on the BoX(R) grinding machine using wheels with grit sizes of 76 μm, 46 m and 25 μm. The highest material removal rate (187.5 mm3/s) used ensures that a 1 metre diameter optic can be ground in less than 10 hours. The surface roughness and surface profile were measured using a Form Talysurf. The subsurface damage was revealed using a sub aperture polishing process in combination with an etching technique on small parts. These results are compared with the targeted form accuracy of 1 μm p- v over a 1 metre part, surface roughness of 50-150 nm RMS and subsurface damage in the range of 2-5 μm. This process stage was validated on a 1 metre hexagonal Zerodur(R)p
URI: http://dx.doi.org/10.1117/12.797451
Appears in Collections:Staff publications - School of Applied Sciences

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