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arXiv · 1608.04888

The metrology system of the VLTI instrument GRAVITY

Magdalena Lippa·Stefan Gillessen·Nicolas Blind·Yipting Kok·Senol Yazici·Johannes Weber·Oliver Pfuhl·Marcus Haug·Stefan Kellner·Ekkehard Wieprecht·Frank Eisenhauer·Reinhard Genzel·Oliver Hans·Frank Haussmann·David Huber·Tobias Kratschmann·Thomas Ott·Markus Plattner·Christian Rau·Eckhard Sturm·Idel Waisberg·Erich Wiezorrek·Guy Perrin·Karine Perraut·Wolfgang Brandner·Christian Straubmeier·Antonio Amorim
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Abstract

The VLTI instrument GRAVITY combines the beams from four telescopes and provides phase-referenced imaging as well as precision-astrometry of order 10 microarcseconds by observing two celestial objects in dual-field mode. Their angular separation can be determined from their differential OPD (dOPD) when the internal dOPDs in the interferometer are known. Here, we present the general overview of the novel metrology system which performs these measurements. The metrology consists of a three-beam laser system and a homodyne detection scheme for three-beam interference using phase-shifting interferometry in combination with lock-in amplifiers. Via this approach the metrology system measures dOPDs on a nanometer-level.

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Magdalena Lippa, Stefan Gillessen, Nicolas Blind, Yipting Kok, Senol Yazici, Johannes Weber, Oliver Pfuhl, Marcus Haug, Stefan Kellner, Ekkehard Wieprecht, Frank Eisenhauer, Reinhard Genzel, Oliver Hans, Frank Haussmann, David Huber, Tobias Kratschmann, Thomas Ott, Markus Plattner, Christian Rau, Eckhard Sturm, Idel Waisberg, Erich Wiezorrek, Guy Perrin, Karine Perraut, Wolfgang Brandner, Christian Straubmeier, Antonio Amorim. 2016-08-17. The metrology system of the VLTI instrument GRAVITY. https://doi.org/10.1117/12.2232272

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