The First Aspheric Form and Texture Results From a Production Machine Embodying the Precession Process

D. D. Walker, D. Brooks, R. Freeman, A. King, G. McCavana, R. Morton, D. Riley, J. Simms

Research output: Chapter in Book/Report/Conference proceedingConference contribution

65 Citations (Scopus)

Abstract

We report on progress developing the 'Precession Process', that has recently been embodied for the firsttime in a fully-productionised aspheric polishing machine. We describe how the process uses inflatedpolishing tools of continuously-variable size and hardness. Despite the rapid tool-rotation needed togive high removal rates, the method produce well-behaved and near-Gaussian tool influence-functions,by virtue ofthe precession ofthe spin axis.

We then describe how form-errors are controlled. The method takes influence-function data and anerror-map as input, together with, uniquely, weighting factors for height and slope residuals andprocess-time. A numerical optimisation of the cost function with variable dwell-time, tool-path andtool-size is then performed. The advantages of this new technique are contrasted with conventional deconvolutionmethods. Results of form-control on aspheric surfaces are presented, with an interpretationin terms of spatial frequencies. We draw particular attention to control of form at the centre andperiphery of a work-piece.

Finally, we describe how Precession processing gives multi-directional rubbing of surfaces, and wepresent the superb texture achieved on samples.

Original languageEnglish
Title of host publicationOptical Manufacturing and Testing IV
EditorsH. Philip Stahl
PublisherSPIE
Pages267-276
Number of pages10
Volume4451
ISBN (Print)9780819441652, 0819441651
DOIs
Publication statusPublished - 27 Dec 2001
Externally publishedYes
EventInternational Symposium on Optical Science and Technology - San Diego, United States
Duration: 29 Jul 20013 Aug 2001
https://www.spiedigitallibrary.org/conference-proceedings-of-spie/browse/SPIE-Optics-Photonics/2001

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
Volume4451
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceInternational Symposium on Optical Science and Technology
CountryUnited States
CitySan Diego
Period29/07/013/08/01
Internet address

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