Recent advances in the control of form and texture on free-form surfaces

D. D. Walker, A. T.H. Beaucamp, V. Doubrovski, C. Dunn, R. Freeman, G. Hobbs, G. McCavana, R. Morton, D. Riley, J. Simms, X. Wei

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Citations (Scopus)


The recent upsurge in the demand for off-axis and complex "freeform" optical surfaces is driving the development of novel processes for their fabrication. This paper focuses on recent developments of the Precessions CNC polishing process for freeform surfaces, including off-axis as a special case. First, the surface-prescription and metrology-data, and their relation to the data-input for the polishing machines, are considered. The relevance of consistent coordinate frames is emphasised. An outline of how the process can 'polish' a ground freeform part (improve the texture), and then 'figure' the part (reduce the form errors) is given. Specific experimental case-studies are then presented, illustrating the versatility of the process on different materials and forms. 

Recent work is included in which the process-speed has been moderated in order to remove tens of nanometres of stock material, rather then the more usual hundreds of nanometres to tens of microns as in the standard Precessions process. The relevance of this to improving the ultimate surface-precision that should be achievable by this method is described. As a final illustration, the potential of the process to the rapid fabrication of the hundreds to thousands of 1-2 metre class mirror segments required for extremely large telescopes is considered.

Original languageEnglish
Title of host publicationOptical Fabrication, Testing, and Metrology II
EditorsAngela Duparré, Roland Geyl, Lingli Wang
Number of pages7
ISBN (Print)0819459836, 9780819459831
Publication statusPublished - 19 Oct 2005
Externally publishedYes
EventOptical Systems Design 2005 - Jena, Germany
Duration: 12 Sep 200516 Sep 2005
Conference number: 2

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceOptical Systems Design 2005


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