Enabling efficient injection of light into single-mode fibers (SMFs) is a key requirement in realizing diffraction-limited astronomical spectroscopy on ground-based telescopes. SMF-fed spectrographs, facilitated by the use of adaptive optics (AO), offer distinct advantages over comparable seeing-limited designs, including higher spectral resolution within a compact and stable instrument volume, and a telescope independent spectrograph design. iLocater is an extremely precise radial velocity (EPRV) spectrograph being built for the Large Binocular Telescope (LBT). We have designed and built the front-end fiber injection system, or acquisition camera, for the SX (left) primary mirror of the LBT. The instrument was installed in 2019 and underwent on-sky commissioning and performance assessment. In this paper, we present the instrument requirements, acquisition camera design, as well as results from first-light measurements. Broadband single-mode fiber coupling in excess of 35% (absolute) in the near-infrared (0.97-1.31{\mu}m) was achieved across a range of target magnitudes, spectral types, and observing conditions. Successful demonstration of on-sky performance represents both a major milestone in the development of iLocater and in making efficient ground-based SMF-fed astronomical instruments a reality.
@article{arxiv.2010.13795,
title = {Final Design and On-Sky Testing of the iLocater SX Acquisition Camera: Broadband Single-Mode Fiber Coupling},
author = {Jonathan Crass and Andrew Bechter and Brian Sands and David L. King and Ryan Ketterer and Matthew Engstrom and Randall Hamper and Derek Kopon and James Smous and Justin R. Crepp and Manny Montoya and Oli Durney and David Cavalieri and Robert Reynolds and Michael Vansickle and Eleanya Onuma and Joseph Thomes and Scott Mullin and Chris Shelton and Kent Wallace and Eric Bechter and Amali Vaz and Jennifer Power and Gustavo Rahmer and Steve Ertel},
journal= {arXiv preprint arXiv:2010.13795},
year = {2020}
}
Comments
18 pages, 17 figures. Accepted for publication in MNRAS