Diffractive pupil telescope for high precision space astrometry

Olivier Guyon, Eduardo Bendek, Mark Ammons, Michael Shao, Stuart Shaklan, Robert A. Woodruff, Ruslan Belikov

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

2 Scopus citations


A concept for high precision astrometry with a conventional wide field telescope is presented, enabling a space telescope to perform simultaneously coronagraphic imaging of exoplanets, astrometric measurement of their orbits and masses, and deep wide field imaging for a wide range of astrophysical investigations. Our concept uses a diffractive telescope pupil (primary mirror), obtained by placing a regular grid of small sub millimeter spots on the primary mirror coating. When the telescope is pointed at a bright star, the wide field image contains both a large number of background stars used for astrometric referencing, and faint diffraction spikes created by the grid of dots on the primary mirror. The diffraction spikes encode instrumental astrometric distortions due to optics or the detector, allowing precise measurement of the central star against a large number of faint background stars. With up to a few percent of the primary mirror area covered by the dots, the fraction of the central starlight located in the diffraction spikes is kept sufficiently small to allow full sensitivity deep imaging over the telescope's field of view. Since the dots are regularly spaced, they do not diffract light at small angular separations, and therefore allow full coronagraphic imaging capability. We show that combining simultaneous astrometric and coronagraphic measurements allows improved detection and characterization of exoplanets by constraining the planet(s) characteristics with both measurements. Our preliminary astrometric accuracy error budget shows that sub-micro arcsecond astrometry can be achieved with a 1.4 m diameter telescope, and that astrometric accuracy improves rapidly with telescope diameter.

Original languageEnglish (US)
Title of host publicationTechniques and Instrumentation for Detection of Exoplanets V
StatePublished - 2011
EventTechniques and Instrumentation for Detection of Exoplanets V - San Diego, CA, United States
Duration: Aug 23 2011Aug 24 2011

Publication series

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


OtherTechniques and Instrumentation for Detection of Exoplanets V
Country/TerritoryUnited States
CitySan Diego, CA


  • Astrometry
  • Coronagraphy
  • Exoplanets

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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