Final design and on-sky testing of the iLocater SX acquisition camera: broad-band single-mode fibre coupling

ABSTRACT Enabling efficient injection of light into single-mode fibres (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 s...

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Bibliographic Details
Published in:	Monthly notices of the Royal Astronomical Society Vol. 501; no. 2; pp. 2250 - 2267
Main Authors:	Crass, J, Bechter, A, Sands, B, King, D, Ketterer, R, Engstrom, M, Hamper, R, Kopon, D, Smous, J, Crepp, J R, Montoya, M, Durney, O, Cavalieri, D, Reynolds, R, Vansickle, M, Onuma, E, Thomes, J, Mullin, S, Shelton, C, Wallace, K, Bechter, E, Vaz, A, Power, J, Rahmer, G, Ertel, S
Format:	Journal Article
Language:	English
Published:	Oxford University Press 01-02-2021
Subjects:	instrumentation: adaptive optics techniques: high angular resolution instrumentation: spectrographs
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Summary:	ABSTRACT Enabling efficient injection of light into single-mode fibres (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 fibre 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. Broad-band SMF coupling in excess of 35 per cent (absolute) in the near-infrared (0.97–1.31 ${\mu {\rm m}}$) 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.
ISSN:	0035-8711 1365-2966
DOI:	10.1093/mnras/staa3355