Prime focus coma corrector for the MMT with 'off the shelf' components

M. P. Langlois, J. P.R. Angel, M. Lloyd-Hart

Research output: Contribution to journalConference articlepeer-review


A small prime focus corrector for the new 6.5 m MMT telescopes has been built using small off-the-shelf optical components. Its purpose is to aid in initial tests of the primary mirror. At f/1.25 the paraboloidal primary is by far the fastest of any large telescope, and without correction the field and the plate scale are both inconveniently small. The corrector design is based on the Maksutov camera, with a concave spherical relay mirror and a refractive meniscus corrector to subtract the coma introduced by the primary mirror and balance out the spherical aberration from the relay mirror. The result is a 48 arcsec field at f/7 (220 μm/arcsec) with 80% encircled energy within 0.25 arcsec diameter (the uncorrected field is 6 arcsec). The instrument includes a CCD with 500×500 20 micron pixels (0.09 inches per pixel), a guide camera and provision for a fast wavefront sensor to measure mirror figure and atmospheric turbulence. The instrument was tested at the telescope before implementation of the active control of mirror support forces or the mirror air conditioning system. Nevertheless images with FWHM 0.53 arcsec were recorded.

Original languageEnglish (US)
Pages (from-to)II/-
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2000
EventConference on Optical and IR Telescope Instrumentation and Detectors - Munich, Ger
Duration: Mar 27 2000Mar 31 2000

ASJC Scopus subject areas

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


Dive into the research topics of 'Prime focus coma corrector for the MMT with 'off the shelf' components'. Together they form a unique fingerprint.

Cite this