Fabrication of mirrors for the Magellan telescopes and the large binocular telescope

H. M. Martin, R. G. Allen, J. H. Burge, L. R. Dettmann, D. A. Ketelsen, S. M. Miller, J. M. Sasian

Research output: Contribution to journalConference articlepeer-review

36 Scopus citations


We describe the fabrication and testing of the 6.5 m f/1.25 primary mirrors for the Magellan telescopes and the 8.4 m f/1.14 primary mirrors for the Large Binocular Telescope (LET). These mirrors, along with the 6.5 m MMT primary, are the fastest and most aspheric large mirrors made. Steward Observatory developed special methods to polish and measure these and other, fast mirrors. We use a stressed-lap polishing tool to fit the aspheric surface while providing strong passive smoothing, and computer-generated holograms to verify the measurement of up to 1.4 mm peak-to-valley asphericity to an accuracy of 0.01%. The Magellan mirrors are diffraction-limited at visible wavelengths, with surface accuracies of about 20 nm rms on active supports. We are currently polishing the first LET primary mirror and preparing to make the thin shells for the LET adaptive secondary mirrors.

Original languageEnglish (US)
Pages (from-to)609-618
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue number2
StatePublished - 2002
EventLarge Ground-based Telescopes - Waikoloa, HI, United States
Duration: Aug 22 2002Aug 26 2002


  • Aspheres
  • Optical fabrication
  • Optical testing
  • Telescopes

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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