Manufacture of a 1.7 m prototype of the GMT primary mirror segments

H. M. Martin, J. H. Burge, S. M. Miller, B. K. Smith, R. Zehnder, C. Zhao

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

21 Scopus citations


We have nearly completed the manufacture of a 1.7 m off-axis mirror as part of the technology development for the Giant Magellan Telescope. The mirror is an off-axis section of a 5.3 m f/0.73 parent paraboloid, making it roughly a 1:5 model of the outer 8.4 m GMT segment. The 1.7 m mirror will be the primary mirror of the New Solar Telescope at Big Bear Solar Observatory. It has a 2.7 mm peak-to-valley departure from the best-fit sphere, presenting a serious challenge in terms of both polishing and measurement. The mirror was polished with a stressed lap, which bends actively to match the local curvature at each point on the mirror surface, and works for asymmetric mirrors as well as symmetric aspheres. It was measured using a hybrid reflective-diffractive null corrector to compensate for the mirror's asphericity. Both techniques will be applied in scaled-up versions to the GMT segments.

Original languageEnglish (US)
Title of host publicationOptomechanical Technologies for Astronomy
StatePublished - 2006
EventOptomechanical Technologies for Astronomy - Orlando, FL, United States
Duration: May 24 2006May 31 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6273 I
ISSN (Print)0277-786X


OtherOptomechanical Technologies for Astronomy
Country/TerritoryUnited States
CityOrlando, FL


  • 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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