Liger is a next-generation near-infrared imager and integral field spectrograph (IFS) planned for the W.M. Keck Observatory. Liger is designed to take advantage of improved adaptive optics (AO) from the Keck All-Sky Precision Adaptive Optics (KAPA) upgrade currently underway. Liger operates at 0.84-2.45 μm with spectral resolving powers of R∼4,000-10,000. Liger makes use of a sequential imager and spectrograph design allowing for simultaneous observations. There are two spectrograph modes: a lenslet with high spatial sampling of 14 and 31 mas, and a slicer with 75 and 150 mas sampling with an expanded field of view. Two pick-off mirrors near the imager detector direct light to these two IFS channels. We present the design and structural analysis for the imager detector and IFS pick-off mirror mounting assembly that will be used to align and maintain stability throughout its operation. A piezoelectric actuator will be used to step through 3mm of travel during alignment of the instrument to determine the optimal focus for both the detector and pick-off mirrors which will be locked in place during normal operation. We will demonstrate that the design can withstand the required gravitational and shipping loads and can be aligned within the positioning tolerances for the optics.
@article{arxiv.2208.07938,
title = {Liger at Keck Observatory: Imager Detector and IFS Pick-off Mirror Assembly},
author = {Maren Cosens and Shelley A. Wright and Aaron Brown and Michael Fitzgerald and Chris Johnson and Tucker Jones and Marc Kassis and Evan Kress and Renate Kupke and James E. Larkin and Kenneth Magnone and Rosalie McGurk and Nils-Erik Rundquist and Ji Man Sohn and Eric Wang and James Wiley and Sherry Yeh},
journal= {arXiv preprint arXiv:2208.07938},
year = {2022}
}