MAVIS: Optical and mechanical design overview of the LGS WFS carousel

Abstract

The MCAO-Assisted Visible Imager and Spectrograph (MAVIS)1,2 is an instrument that will provide an unprecedented level of imaging and spectroscopy with the highest visible angular resolution provided by any ground or space-based telescope. Operating at a wavelength range of .370-.950 um, MAVIS will be installed on the Nasmyth platform A of the ESO Yepun one of the Very Large Telescopes (VLT) as a general-purpose instrument with an angular resolution two to three times better than that of the Hubble Space Telescope. MAVIS will take advantage of the 4 lasers in the VLT Adaptive Optics Facility (AOF) with an added upgrade of the facility. This upgrade splits each of four lasers into pairs that generate the eight laser guide stars (LGS) used to feed the wavefront sensors (WFS). The MAVIS LGS WFS carousel is situated in the MAVIS Adaptive Optics Modules (AOM) where the 589 nm laser light is split from the incoming beam before the instrument derotator. The LGS WFS module consists of a focuser to adjust for the altitude of the sodium layer and a rotating carousel that houses the eight LGS WFS. In this paper, we present the final design of the optical and mechanical components of the field derotating carousel, LGS WFS optics, and c ameras. We introduce the simulations and models that continue to constrain and improve the performance of the design.