Active control of edges and global microstructure on segmented mirrors

D. D. Walker; A. Beaucamp; C. Dunn; R. Evans; R. Freeman; R. Morton; S. Wei; G. Yu

doi:10.1117/12.787930

23 July 2008 Active control of edges and global microstructure on segmented mirrors

D. D. Walker, A. Beaucamp, C. Dunn, R. Evans, R. Freeman, R. Morton, S. Wei, G. Yu

Proceedings Volume 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation; 701812 (2008) https://doi.org/10.1117/12.787930
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

In this paper we address two interrelated issues important to primary mirror segments for extremely large telescopes - edge-control, and the detailed topography over the segment surface. Both affect the intensity and distribution of stray light and infrared emissivity. CNC polishing processes typically deploy spiral or raster tool-paths, tending to leave repetitive features. We compare and contrast two novel families of pseudo-random tool-paths for Precessions CNC polishing. We then show how CNC control of the three-dimensional tool-path can optimize edge-profiles. Finally, we demonstrate fluid-jet polishing used to clean up residual edge defects.

Citation Download Citation

D. D. Walker, A. Beaucamp, C. Dunn, R. Evans, R. Freeman, R. Morton, S. Wei, and G. Yu "Active control of edges and global microstructure on segmented mirrors", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 701812 (23 July 2008); https://doi.org/10.1117/12.787930

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