Search:
Computing and Library Services - delivering an inspiring information environment

Edge-control and surface-smoothness in sub-aperture polishing of mirror segments

Walker, D.D., Beaucamp, A., Evans, R., Fox-Leonard, T., Fairhurst, N., Gray, C., Hamidi, S., Li, H., Messalink, W., Mitchell, J., Rees, P. and Yu, G. (2012) Edge-control and surface-smoothness in sub-aperture polishing of mirror segments. Proceedings of SPIE - The International Society for Optical Engineering, 8450. ISSN 0277-786X

[img]
Preview
PDF
Download (689kB) | Preview

Abstract

This paper addresses two challenges in establishing a new process chain for polishing hexagonal segments for extremely large telescopes:- i) control of edge and corner profiles in small-tool polishing of hexagons, and ii) achieving the required smoothness of the bulk aspheric form. We briefly describe the performance of a CNC-grinding process used to create the off-axis asphere, which established the input-quality for subsequent processing. We then summarize processes for smoothing ground mid-spatials and pre- and corrective polishing using Zeeko CNC machines. The impact of two cases is considered; i) all processing stages are performed after the segment is cut hexagonal, and ii) final rectification of a hexagon after cutting from an aspherised roundel, as an alternative to ionfiguring. We then report on experimental results on witness samples demonstrating edges and corners close to the EELT segment specification, and results on a full-aperture spherical segment showing excellent surface smoothness. © 2012 SPIE.

Item Type: Article
Subjects: T Technology > TS Manufactures
Schools: School of Computing and Engineering
School of Computing and Engineering > Centre for Precision Technologies
Related URLs:
Depositing User: Catherine Parker
Date Deposited: 29 Nov 2016 14:40
Last Modified: 01 Dec 2016 05:14
URI: http://eprints.hud.ac.uk/id/eprint/30401

Downloads

Downloads per month over past year

Repository Staff Only: item control page

View Item View Item

University of Huddersfield, Queensgate, Huddersfield, HD1 3DH Copyright and Disclaimer All rights reserved ©