Finishing of optical moulds to λ/20 by automated corrective polishing

A. Beaucamp, Y. Namba, I. Inasaki, H. Combrinck, R. Freeman

Research output: Contribution to journalArticlepeer-review


Tungsten carbide is widely used to make replication moulds for small aspheric and freeform optics, like camera lenses. Since aspheric generation by grinding generally fails to reach ultra-precision criteria, a time efficient method for finishing moulds is needed. Using a 7-axis CNC polishing machine, an on-machine tool forming technique and compensation software were developed to correctively polish a plano WC surface of diameter 25 mm from a form error above λ to below λ/20 (29 nm P-V) in under 1 h, while reducing roughness to 1.0 nm Ra. This automatic method and tooling are applicable to aspheric and freeform moulds.

Original languageEnglish
Pages (from-to)375-378
Number of pages4
JournalCIRP Annals - Manufacturing Technology
Issue number1
Publication statusPublished - 2011
Externally publishedYes


  • Finishing
  • Mould
  • Ultra-precision

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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