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: Contribution to journalArticle

62 Citations (Scopus)

Abstract

We report on progress developing the 'Precession Process', that has recently been embodied for the first time in a fully-productionised aspheric polishing machine. We describe how the process uses inflated polishing tools of continuously-variable size and hardness. Despite the rapid tool-rotation needed to give 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 an error-map as input, together with, uniquely, weighting factors for height and slope residuals and process-time. A numerical optimisation of the cost function with variable dwell-time, tool-path and tool-size is then performed. The advantages of this new technique are contrasted with conventional deconvolution methods. Results of form-control on aspheric surfaces are presented, with an interpretation in terms of spatial frequencies. We draw particular attention to control of form at the centre and periphery of a work-piece. Finally, we describe how Precession processing gives multi-directional rubbing of surfaces, and we present the superb texture achieved on samples.

Original languageEnglish
Pages (from-to)267-276
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4451
DOIs
Publication statusPublished - 27 Dec 2001
Externally publishedYes

Fingerprint

precession
Texture
Influence Function
textures
Textures
Aspheric Surface
Multiprocessing
Dwell Time
Tool Path
Polishing
Polishing machines
Numerical Optimization
Hardness
Weighting
dwell
Cost Function
Slope
polishing
Cost functions
hardness

Cite this

Walker, D. D. ; Brooks, D. ; Freeman, R. ; King, A. ; McCavana, G. ; Morton, R. ; Riley, D. ; Simms, J. / The First Aspheric Form and Texture Results From a Production Machine Embodying the Precession Process. In: Proceedings of SPIE - The International Society for Optical Engineering. 2001 ; Vol. 4451. pp. 267-276.
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The First Aspheric Form and Texture Results From a Production Machine Embodying the Precession Process. / Walker, D. D.; Brooks, D.; Freeman, R.; King, A.; McCavana, G.; Morton, R.; Riley, D.; Simms, J.

In: Proceedings of SPIE - The International Society for Optical Engineering, Vol. 4451, 27.12.2001, p. 267-276.

Research output: Contribution to journalArticle

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