4 August 2016 The metrology system of the VLTI instrument GRAVITY
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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 μas 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, Magdalena Lippa, Stefan Gillessen, Stefan Gillessen, Nicolas Blind, Nicolas Blind, Yitping Kok, Yitping Kok, Şenol Yazıcı, Şenol Yazıcı, Johannes Weber, Johannes Weber, Oliver Pfuhl, Oliver Pfuhl, Marcus Haug, Marcus Haug, Stefan Kellner, Stefan Kellner, Ekkehard Wieprecht, Ekkehard Wieprecht, Frank Eisenhauer, Frank Eisenhauer, Reinhard Genzel, Reinhard Genzel, Oliver Hans, Oliver Hans, Frank Haußmann, Frank Haußmann, David Huber, David Huber, Tobias Kratschmann, Tobias Kratschmann, Thomas Ott, Thomas Ott, Markus Plattner, Markus Plattner, Christian Rau, Christian Rau, Eckhard Sturm, Eckhard Sturm, Idel Waisberg, Idel Waisberg, Erich Wiezorrek, Erich Wiezorrek, Guy Perrin, Guy Perrin, Karine Perraut, Karine Perraut, Wolfgang Brandner, Wolfgang Brandner, Christian Straubmeier, Christian Straubmeier, Antonio Amorim, Antonio Amorim, } "The metrology system of the VLTI instrument GRAVITY", Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 990722 (4 August 2016); doi: 10.1117/12.2232272; https://doi.org/10.1117/12.2232272
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