Laboratory characterization of iLocater
arXiv:2607.27356
The paper describes laboratory tests of the iLocater near‑infrared, diffraction‑limited, fiber‑fed spectrograph for the Large Binocular Telescope, covering detector alignment, LED flat‑field illumination, model‑based focusing using OpticStudio, and mechanical/optical stability assessments to verify performance before on‑sky use.
Abstract
iLocater is a diffraction-limited, fiber-fed spectrograph designed for the Large Binocular Telescope (LBT), which targets high-precision radial velocity measurements in the near-infrared. Prior to deployment, comprehensive laboratory characterization was essential to validate instrument performance and inform alignment strategies. This paper presents results from four key areas of lab characterization: (1) adjustment and optimization of detector orientation to optimize spectrum alignment with the detector pixel grid across the focal plane; (2) the design and installation of a LED illumination source to enable high-fidelity flat-fields; (3) a model-based focusing methodology using OpticStudio image simulations to optimize the optical alignment of the spectrograph; and (4) assessment of instrument mechanical and optical stability under laboratory conditions. Together, these efforts established baseline performance metrics and demonstrated instrument readiness for delivery and on-sky commissioning.
9 pages, 6 figures, SPIE Proceedings