New developments in the Precessions process for manufacturing free-form, large-optical, and precision-mechanical 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 contribution

9 Citations (Scopus)

Abstract

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 publication2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies
Subtitle of host publicationLarge Mirrors and Telescopes
EditorsYudong Zhang, Wenhan Jiang, Myung K. Cho
PublisherSPIE
Number of pages9
Volume6148
ISBN (Print)9780819461872
DOIs
Publication statusPublished - 30 May 2006
Externally publishedYes
Event2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies - Xian, China
Duration: 2 Nov 20055 Nov 2005
Conference number: 2

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
Volume6148
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

Conference2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies
CountryChina
CityXian
Period2/11/055/11/05

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  • Cite this

    Walker, D. D., Beaucamp, A. T. H., Doubrovski, V., Dunn, C., Freeman, R., Hobbs, G., ... Wei, X. (2006). New developments in the Precessions process for manufacturing free-form, large-optical, and precision-mechanical surfaces. In Y. Zhang, W. Jiang, & M. K. Cho (Eds.), 2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes (Vol. 6148). [614805] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 6148). SPIE. https://doi.org/10.1117/12.674039