PhD project: The GRAVITY acquisition camera

2012- now

GRAVITY has been built and successfully installed on 4th November, 2015 at the Very Large Telescope Interferometer (VLTI) in the Paranal Observatory of ESO, Chile. The instrument is a powerful ineterferometric imaging and astrometry instrument. It combines four existing telescope light beams of the VLTI (either four 8 m or four 1.8 m) in the interferometric mode and achieves the spatial resolution of an equivalent telescope of up to 130 meters in diameter. By doing so it delivers 4 mas imaging resolution in K-band and 10 micro arcseconds astrometry precision. Having this precision, the motion of one-euro coin on the surface of Moon can be tracked from the Earth. More details about the instrument hardware can be found at publications of GRAVITY, ADS.

The main aim of the facility is to monitor the stellar motions in the vicinity of Black-Hole, which is available at the center of our Galactic Center and therefore uncover its physics. Besides, having the great sensitivity in imaging and astrometry, it has the potential to detect intermediate Black-Holes available in faint nearby Galaxies and far distant exo-planets which were out of reach with previous instruments.

GRAVITY has been built by a consortium of many European institutes, led by Max-Planck-Institut für extraterrestrische Physik (MPE), Garching, Germany, working in collaboration with SIM research group, Portugal. The SIM has contributed a sub-system called acquisition camera, where my work focuses, which monitors and analyzes the telescopes beams. It is an important contribution and plays a key role in the beam stabilization, which is required for the precise astrometry. The beam stabilization was achieved by constantly adjusting various actuators using the signals provided by the acquisition camera.

GRAVITY is expected to revolutionize the detailed study of the Galactic Center, in particular in studying ultimate questions: the origin of near-infrared flares in the vicinity of Black-Hole; the presence of young stars in the disfavored conditions in the nuclei of the Galactic Center. Also, for the first time, it tests the Einstein's Special and General Theory of Relativity in the strong gravitational potential regime. In addition, studies stellar dynamics around the Black-Hole and binary objects dynamics.

My work is related to beam stabilization. The acquisition camera (Amorim et al. 2012, Gordo et al. 2014) operates in near infrared wavelengths (1.2 and 1.65 micro metres). It implements field, pupil and Shack-Hartmann images of each beam. By doing so it measures field, pupil and higher order wavefront aberrations of four telescope beams. The highlights of the instrument are it accomplished novel near-infrared star light injection into single mode fiber and also new way telescope pupil tracking.

In the first two years of my PhD, I worked on control system for cryogenics, hardware design, assembly, optical alignment and testing. Next two years I worked on the software development for the image data reduction and beam correction control. Currently I am writing three papers based on my PhD work.

M.Tech project: Wavefront sensing / adaptive optics

2010-2011

For my master's dissertation I worked on adaptive optics at Indian Institute of Astrophysics. The work was carried out in three fronts: a) to characterize the atmospheric turbulence, it was simulated numerically and experimentally in laboratory; b) developed wavefront sensing algorithms; c) worked on alignment of the adaptive optics demonstrator. The atmospheric turbulence characterization was published in Journal of Optics (Anugu et al. 2013).

M.Tech in Astronomical Instrumentation

Indian Institute of Astrophysics / University of Calcutta

Thesis: Development of closed loop adaptive optics system at laboratory

2009-2011

M.Sc in Physics

Specialisation: solid state physics

2007-2009

B.Sc in Physics

2003-2006