Optics for the 20/20 telescope

H. M. Martin, J. R.P. Angel, J. H. Burge, S. M. Miller, J. M. Sasian, P. A. Strittmatter

Research output: Contribution to journalConference articlepeer-review

15 Scopus citations


We present a plan for making the optics of a 21 m telescope that builds on advances in mirror design and fabrication developed for the Large Binocular Telescope (LBT) and other large telescopes. The 21 m telescope, with a fast f/0.7 primary mirror made of only seven large honeycomb-sandwich segments and an adaptive secondary with matching segments, is much suffer than other designs and offers simpler and more accurate wavefront control. It can be a powerful stand-alone telescope, or one of a pair that move on a circular track to achieve coherent imaging with baselines up to 120 m (the 20/20 telescope). Each segment of the 21 m primary mirror is similar to an 8.4 m LBT primary, and each segment of the 2.1 m adaptive secondary mirror is similar to an LBT secondary. The off-axis segments of both mirrors can be made with the same methods and equipment currently used at the Steward Observatory Mirror Lab, and can be polished with the same stressed-lap polishing system used for the LBT mirrors. A change in algorithm to accommodate the asymmetric surface is required, but no new hardware development is needed because the lap bending is similar to that for the LBT mirrors. Each segment can be measured interferometrically, with a combination reflective and diffractive null corrector producing an accurate aspheric template wavefront and alignment references for the segments.

Original languageEnglish (US)
Pages (from-to)194-205
Number of pages12
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2002
EventFuture Giant Telescopes - Waikoloa, HI, United States
Duration: Aug 26 2002Aug 28 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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