GRAVITY faint: reducing noise sources in GRAVITY$^+$ with a fast metrology attenuation system
Abstract
With the upgrade from GRAVITY to GRAVITY the instrument will evolve into an all-sky interferometer that can observe faint targets, such as high redshift AGN. Observing the faintest targets requires reducing the noise sources in GRAVITY as much as possible. The dominant noise source, especially in the blue part of the spectrum, is the backscattering of the metrology laser light onto the detector. To reduce this noise we introduce two new metrology modes. With a combination of small hardware changes and software adaptations, we can dim the metrology laser during the observation without losing the phase referencing. For single beam targets, we can even turn off the metrology laser for the maximum SNR on the detector. These changes lead to an SNR improvement of over a factor of two averaged over the whole spectrum and up to a factor of eight in the part of the spectrum currently dominated by laser noise.
Cite
@article{arxiv.2209.05593,
title = {GRAVITY faint: reducing noise sources in GRAVITY$^+$ with a fast metrology attenuation system},
author = {F. Widmann and S. Gillessen and T. Ott and T. Shimizu and F. Eisenhauer and M. Fabricius and J. Woillez and F. Gonté and M. Horrobin and J. Shangguan and S. Yazici and G. Perrin and T. Paumard and W. Brandner and L. Kreidberg and C. Straubmeier and K. Perraut and J. -B. Le Bouquin and P. Garcia and S. Hönig and D. Defrère and G. Bourdarot and A. Drescher and H. Feuchtgruber and R. Genzel and M. Hartl and D. Lutz and N. More and C. Rau and S. Uysal and E. Wieprecht},
journal= {arXiv preprint arXiv:2209.05593},
year = {2022}
}
Comments
Proceeding of SPIE Astronomical Telescopes + Instrumentation 2022