MUSE (Multi Unit Spectroscopic Explorer) is a second generation Very Large Telescope (VLT) integral field
spectrograph (1x1arcmin² Field of View) developed for the European Southern Observatory (ESO), operating in the
visible wavelength range (0.465-0.93 μm). A consortium of seven institutes is currently commissioning MUSE in the
Very Large Telescope for the Preliminary Acceptance in Chile, scheduled for September, 2014.
MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates
and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units
(IFU), that are mounted within a large monolithic instrument mechanical structure. Each IFU incorporates an image
slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and
cryogenic system. During 2012 and 2013, all MUSE subsystems were integrated, aligned and tested to the P.I. institute at
Lyon. After successful PAE in September 2013, MUSE instrument was shipped to the Very Large Telescope in Chile
where that was aligned and tested in ESO integration hall at Paranal. After, MUSE was directly transferred in monolithic
way without dismounting onto VLT telescope where the first light was overcame.
This talk describes the IFU Simulator which is the main alignment and performance tool for MUSE instrument. The IFU
Simulator mimics the optomechanical interface between the MUSE pre-optic and the 24 IFUs. The optomechanical
design is presented. After, the alignment method of this innovative tool for identifying the pupil and image planes is
depicted. At the end, the internal test report is described. The success of the MUSE alignment using the IFU Simulator is
demonstrated by the excellent results obtained onto MUSE positioning, image quality and throughput.
MUSE commissioning at the VLT is planned for September, 2014.