Automated finishing of diamond turned dies for hard X-ray and EUV optics replication

Anthony T.H. Beaucamp, Yoshiharu Namba, Richard R. Freeman

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


Ultra-precision diamond turning can deliver very accurate form, often less than 100nm PV. A possible manufacturing method for thin Wolter type-1 mirrors in hard X-ray space telescopes thus involves generating electroless nickel plated mandrels by diamond turning, before coating them with a reflective film and substrate. However, the surface texture after turning falls far short from the requirements of X-ray and EUV applications. The machining marks need to be removed, with hand polishing still widely employed. There is thus a compelling need for automated finishing of turned dies. A two step finishing method is presented that combines fluid jet and precessed bonnet polishing on a common 7-axis CNC platform. This method is capable of finishing diamond turned electroless nickel plated dies down to 0.28nm rms roughness, while deterministically improving form error down to 30nm P-V. The fluid jet polishing process, which consists of pressurizing water and abrasive particles for delivery through a nozzle, has been specially optimized with a newly designed slurry delivery unit and computer simulations, to remove diamond turning marks without introducing another waviness signature. The precessed bonnet polishing method, which consists of an inflated membrane rotated at an angle from the local normal to the surface and controlled by geometrical position relative to the work-piece, is subsequently employed with a novel control algorithm to deliver scratch-free surface roughness down to 0.28 nm rms. The combination of these two deterministic processes to finish aspheric and freeform dies promises to unlock new frontiers in X-ray and EUV optics fabrication.

Original languageEnglish
Title of host publicationAdvances in Optics Manufacture
PublisherTrans Tech Publications Ltd
Number of pages9
ISBN (Print)9783037856918
Publication statusPublished - 2013
Externally publishedYes
EventAsia Pacific Conference on Optics Manufacture 2012, APCOM 2012 - Changchun, China
Duration: 2012 Aug 262012 Aug 28

Publication series

NameKey Engineering Materials
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795


ConferenceAsia Pacific Conference on Optics Manufacture 2012, APCOM 2012


  • Deterministic finishing
  • Diamond turning
  • Electroless nickel
  • Fluid jet polishing
  • Precessed bonnet polishing
  • Super smooth
  • Surface roughness
  • X-ray and EUV

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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