Share Email Print
cover

Proceedings Paper

The GRAVITY metrology system: narrow-angle astrometry via phase-shifting interferometry
Author(s): Magdalena Lippa; Nicolas Blind; Stefan Gillessen; Yitping Kok; Johannes Weber; Frank Eisenhauer; Oliver Pfuhl; Annemieke Janssen; Marcus Haug; Frank Haußmann; Stefan Kellner; Oliver Hans; Ekkehard Wieprecht; Thomas Ott; Leonard Burtscher; Reinhard Genzel; Eckhard Sturm; Reiner Hofmann; S. Huber; David Huber; Stefanie Senftleben; Andreas Pflüger; Roland Greßmann; Guy Perrin; Karine Perraut; Wolfgang Brandner; Christian Straubmeier; Antonio Amorim; Markus Schöller
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

The VLTI instrument GRAVITY will provide very powerful astrometry by combining the light from four tele- scopes for two objects simultaneously. It will measure the angular separation between the two astronomical objects to a precision of 10 μas. This corresponds to a differential optical path difference (dOPD) between the targets of few nanometers and the paths within the interferometer have to be maintained stable to that level. For this purpose, the novel metrology system of GRAVITY will monitor the internal dOPDs by means of phase- shifting interferometry. We present the four-step phase-shifting concept of the metrology with emphasis on the method used for calibrating the phase shifts. The latter is based on a phase-step insensitive algorithm which unambiguously extracts phases in contrast to other methods that are strongly limited by non-linearities of the phase-shifting device. The main constraint of this algorithm is to introduce a robust ellipse fitting routine. Via this approach we are able to measure phase shifts in the laboratory with a typical accuracy of λ=2000 or 1 nm of the metrology wavelength.

Paper Details

Date Published: 24 July 2014
PDF: 11 pages
Proc. SPIE 9146, Optical and Infrared Interferometry IV, 914622 (24 July 2014); doi: 10.1117/12.2054637
Show Author Affiliations
Magdalena Lippa, Max-Planck-Institut für extraterrestrische Physik (Germany)
Nicolas Blind, Max-Planck-Institut für extraterrestrische Physik (Germany)
Stefan Gillessen, Max-Planck-Institut für extraterrestrische Physik (Germany)
Yitping Kok, Max-Planck-Institut für extraterrestrische Physik (Germany)
Johannes Weber, Max-Planck-Institut für extraterrestrische Physik (Germany)
Frank Eisenhauer, Max-Planck-Institut für extraterrestrische Physik (Germany)
Oliver Pfuhl, Max-Planck-Institut für extraterrestrische Physik (Germany)
Annemieke Janssen, Max-Planck-Institut für extraterrestrische Physik (Germany)
Marcus Haug, Max-Planck-Institut für extraterrestrische Physik (Germany)
Frank Haußmann, Max-Planck-Institut für extraterrestrische Physik (Germany)
Stefan Kellner, Max-Planck-Institut für extraterrestrische Physik (Germany)
Oliver Hans, Max-Planck-Institut für extraterrestrische Physik (Germany)
Ekkehard Wieprecht, Max-Planck-Institut für extraterrestrische Physik (Germany)
Thomas Ott, Max-Planck-Institut für extraterrestrische Physik (Germany)
Leonard Burtscher, Max-Planck-Institut für extraterrestrische Physik (Germany)
Reinhard Genzel, Max-Planck-Institut für extraterrestrische Physik (Germany)
Eckhard Sturm, Max-Planck-Institut für extraterrestrische Physik (Germany)
Reiner Hofmann, Max-Planck-Institut für extraterrestrische Physik (Germany)
S. Huber, Max-Planck-Institut für extraterrestrische Physik (Germany)
David Huber, Max-Planck-Institut für extraterrestrische Physik (Germany)
Stefanie Senftleben, Max-Planck-Institut für extraterrestrische Physik (Germany)
Andreas Pflüger, Max-Planck-Institut für extraterrestrische Physik (Germany)
Roland Greßmann, Max-Planck-Institut für extraterrestrische Physik (Germany)
Guy Perrin, Lab. d'études spatiales et d'instrumentation en astrophysique, CNRS, Observatoire de Paris à Meudon (France)
Karine Perraut, Institut de Planétologie et d’Astrophysique de Grenoble (France)
Wolfgang Brandner, Max-Planck-Institut für Astronomie (Germany)
Christian Straubmeier, Univ. zu Köln (Germany)
Antonio Amorim, Fundacão da Faculdade de Ciências da Univ. de Lisboa (Portugal)
Markus Schöller, European Southern Observatory (Germany)


Published in SPIE Proceedings Vol. 9146:
Optical and Infrared Interferometry IV
Jayadev K. Rajagopal; Michelle J. Creech-Eakman; Fabien Malbet, Editor(s)

© SPIE. Terms of Use
Back to Top