Removal of mid spatial-frequency features in mirror segments

G. Yu; H. Li; D. Walker

doi:10.2971/jeos.2011.11044

Journal of the European Optical Society - Rapid publications, Vol 6 (2011)

Removal of mid spatial-frequency features in mirror segments

G. Yu, H. Li, D. Walker

Abstract

BoX™ grinding technology has been adopted in our E-ELT segment process. The mid-spatial frequency features generated can be removed by several ‘smoothing’ processes. We have reported here a novel method that can smooth these features whilst avoiding edge down-turn. This process can be scaled up to E-ELT segment fabrication time-scale. It has been experimentally demonstrated that the surface quality is good enough for subsequent Zeeko form correction technology to achieve form specifications.

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References

eso.org/sci/facilities/eelt/science/doc/eelt_sciencecase.pdf

E-ELT Science Office, E-ELT The European Extremely Large Telescope The world's biggest eye on the sky (European Southern Observatory, 2010).

H. Martin, J. Burge, B. Cuerden, W. Davison, J. Kingsley, R. Lutz, S. Miller, and M. Tuell, "Manufacture of a combined primary and tertiary mirror for the large synoptic survey telescope" Proc. SPIE 7018, 70180G (2008).

D. Walker, A. Beaucamp, V. Doubrovski, C. Dunn, R. Evans, R. Freeman, G. McCanava, R. Morton, D. Riley, J. Simms, G. Yu, and X. Wei, "Commissioning of the first Precessions 1.2m CNC polishing machines for large optics" Proc. SPIE 6288, 1-8 (2008).

C. Dunn, and D. Walker, "Pseudo-random tool path for CNC sub-aperture polishing and other applications" Opt. Express 16, 18942-18949 (2008).

X. Tonnellier, P. Morantz, P. Shore, A. Baldwin, R. Evans, and D. Walker, "Subsurface damage in precision ground ULE® and Zerodur® surfaces" Opt. Express 15, 12197-12205 (2007).

D. Walker, A. Baldwin, R. Evans, R. Freeman, X. Wei, and G. Yu, "A quantitative comparison of three grolishing techniques for the precisions™ process" Proc. SPIE 6671, 56 (2007).

D. Walker, R. Evans, R. Freeman, D. Riley, G. McCanvana, J. Simms, S. Wei, and G. Yu, "The precessions polishing and hybrid grolishing process-implementation in a novel 1.2m capacity machine tool" in Proceedings to the Laser Metrology and Machine Performance VII, 99-108 (Lamdamap, Cardiff, (2007).

R. E. Parks, P. Lam, and W. Kuhn, "The large optical generator-aprogress report" Proc. SPIE 542, 28 (1985).

C. Song, D. Walker, and G. Yu, "Misfit of rigid tools and interferometer sub-apertures on off-axis aspheric mirror segments" Opt. Eng. 50, 073401 (2011).