Phasing the GMT with a next generation e-APD dispersed fringe sensor: Design and on-sky prototyping

Derek Kopon, Brian McLeod, Antonin Bouchez, Daniel Catropa, Marcos A. Van Dam, Ken McCracken, Stuart McMuldroch, William Podgorski, Joseph D'Arco, Laird Close, Jared Males, Katie Morzinski

Research output: Contribution to conferencePaperpeer-review

2 Scopus citations

Abstract

The GMT will be a 25.4-meter telescope consisting of 7 primary and secondary mirror segments that must be phased to within a fraction of an imaging wavelength in order to achieve diffraction limited performance. The need to use off-axis guide stars, coupled with the large (350 mm) segment gaps, makes the task of phasing the GMT uniquely challenging. To meet these requirements, the Acquisition, Guiding, and Wavefront Sensing system (AGWS) will use four J-band dispersed fringe sensors (DFS) to measure segment piston at each segment boundary. This DFS will use a novel array of doublet prisms, instead of grisms, to disperse segment boundary fringes with maximal throughput, minimal stray light, and no spurious diffractive orders. The DFS will also use a low noise SAPHIRA e-APD array reading out at ~100 Hz in order to freeze atmospheric turbulence in the segment boundary fringe images. We will test a prototype of this DFS on the Magellan Clay 6.5 meter telescope using an adaptive optics corrected beam from the MagAO system. We present the design of the next generation phasing prototype.

Original languageEnglish (US)
StatePublished - 2017
Event5th Adaptive Optics for Extremely Large Telescopes, AO4ELT 2017 - Tenerife, Canary Islands, Spain
Duration: Jun 25 2017Jun 30 2017

Other

Other5th Adaptive Optics for Extremely Large Telescopes, AO4ELT 2017
Country/TerritorySpain
CityTenerife, Canary Islands
Period6/25/176/30/17

Keywords

  • Active optics
  • Adaptive optics
  • Dispersed fringe sensor
  • Giant magellan telescope
  • Phasing

ASJC Scopus subject areas

  • Space and Planetary Science
  • Mechanical Engineering
  • Control and Systems Engineering
  • Instrumentation
  • Astronomy and Astrophysics
  • Electronic, Optical and Magnetic Materials

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