Beam characterization and guiding for optical/infrared interferometry

Inhaltsangabe oder Einleitung

The GRAVITY instrument has been built with the goal of studying the Milky Way Galactic Center super-massive black hole. It is a powerful phase-referenced and closure phase interferometric imaging (4 milli-arcseconds) and high precise narrow-angle astrometric instrument (10 microarcseconds) and has been installed at the Very Large Telescope Interferometer (VLTI) of the ESO. There are several practical difficulties in implementing narrow-angle astrometry. The atmospheric turbulence and the error in measuring accurate baseline lengths between any two telescopes are among the major challenges. Due to these, the performance of GRAVITY can be severely degraded in two ways: a) instrument sensitivity – the efficient star’s light injection in the single mode fibers is affected in the presence of random atmospheric tip-tilts; b) astrometric errors – caused due to unwanted tip-tilts and baseline errors. As one of the subsystems required to overcome these challenges, the GRAVITY acquisition camera was built.
The acquisition camera was the responsibility of the Portuguese CENTRA-SIM group where my thesis took place. In this manuscript the acquisition camera is presented from the design phase to the commissioning, focusing on the project work packages that were lead by the author or had a major contribution by him. [...]