Fabrication of large secondary mirrors for astronomical telescopes

Bryan K. Smith, James H. Burge, Hubert M. Martin

Research output: Contribution to journalConference articlepeer-review

28 Scopus citations


A new class of telescope is being built with primary mirrors as large as 8.4 meters in diameter and as fast as f/1. Fabricating the secondary mirrors for these telescopes has presented tough challenges because of their large sizes, up to 1.7 meter diameter; their aspheric departure of more than 300 microns; the required figure accuracy of a few tens of nanometers; and the fact that they are typically convex and difficult to measure. We have developed tools and techniques to meet these demands to produce secondary mirrors efficiently and accurately. A dedicated facility was constructed in the mirror lab that integrates a 1.8-m stressed-lap polishing machine with interferometric and mechanical measuring systems. This paper presents data from a 1.15-m secondary that was finished in our shop, and from two other large mirrors that are currently being fabricated.

Original languageEnglish (US)
Pages (from-to)51-61
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1997
EventOptical Manufacturing and Testing II - San Diego, CA, United States
Duration: Jul 27 1997Jul 27 1997


  • Aspheres
  • Large optics
  • Optical fabrication
  • Telescope mirrors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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