Phasing metrology system for the GMT

D. Scott Acton; Antonin Bouchez

doi:10.1117/12.925012

17 September 2012 Phasing metrology system for the GMT

D. Scott Acton, Antonin Bouchez

Proceedings Volume 8444, Ground-based and Airborne Telescopes IV; 844423 (2012) https://doi.org/10.1117/12.925012
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

The Giant Magellan Telescope (GMT) is a 25.4 m diameter ground-based segmented Gregorian telescope, composed of 7 8.4 meter diameter primary mirror segments, and 7 1 meter diameter adaptive secondary mirror segments. Co-phasing of the integrated optical system will be partially achieved by making real-time measurements of the wavefront of an offaxis guide star. However, slowly varying aberrations due to thermal and gravitational effects, as well as wind buffeting, will make it difficult to maintain alignment using real-time optical measurements alone. Consequently, we are proposing internal metrology systems to maintain the relative alignment of the optical elements. In this paper we describe a differential capacitive edge sensing system to maintain the relative alignment of the adaptive secondary mirror reference bodies. We also propose an interferometric system for sensing of the relative displacements of primary mirror segments.

Citation Download Citation

D. Scott Acton and Antonin Bouchez "Phasing metrology system for the GMT", Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 844423 (17 September 2012); https://doi.org/10.1117/12.925012

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