MUSE integral field unit: test results on the first out of 24

Abstract

MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT panoramic integral field spectrograph developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). It is composed of 24 identical Integral Field Units (IFU); each one incorporates an advanced image slicer associated with a classical spectrograph and a detector vessel. The Image Slicer subsystem -ISS-is composed of two mirror arrays of 48 spherical elements each. It is made of Zerodur and uses an innovative polishing approach where all individual components are polished together by classical method. The MUSE Spectrograph -SPS-, with fast output focal ratio of f/1.95, implements a Volume Phase Holographic Grating -VPHG. The last subsystem, the Detector Vessel -DVincludes a chip of 4k by 4k 15µm pixels supported by a Vacuum and Cryogenic System -VCS -provided by ESO. The first out of 24 IFUs for MUSE instrument has been manufactured, aligned and tested last months. First, this paper describes the optical design, the manufacturing and test results (image quality, pupil and field of view positioning) of each subsystem independently. Second, we will focus on overall system performance (image quality and positioning) of the spectrograph associated with the detector vessel. At the end, the test results (image quality, positioning, throughput, mechanical interfaces) of the first IFU for MUSE instrument will be reported. Most of them are compliant with requirements that it demonstrates that the manufacturing, integration, alignment and tests processes are mature and gives good confidence for serial production by 24 times applied to MUSE instrument.

ERASMUS-F: pathfinder for an E-ELT 3D instrumentation

“…First evaluations of the MUSE spectrograph [8] have confirmed the expected good image quality of the optical system (see figure 2 and 3). The system has originally been designed to optimally perform under the boundary conditions (numerical aperture, pupil position…) given by the mirror-based image slicer.…”

“…The Centre de Recherche Astronomique de Lyon designed and tested the MUSE spectrograph module, whose overall performance and excellent image quality were recently validated [8]. The hexabundles were developed and tested [9] at the University of Sydney (Australia) and will soon demonstrate their scientific feasibility at the Anglo-Australian Telescope.…”

The calibration unit and detector system tests for MUSE

“…This paper describes the design and development status of the calibration unit and the first performance validations of the detector subsystem. Other aspects of the instrument are described in more detail in a series of papers [4][5][6][7][8][9] in this issue, while up-to-date information can be found at the MUSE website [11]. Figure 1: CAD view of the MUSE instrument at the VLT Nasmyth platform [6].…”

“…The first (out if a series of 24) spectrographs was built and extensively tested at CRAL [9]. After evaluation of the spectrograph performance, the system was send to AIP as a reference, as to measure the correct CCD integration with respect to the detector head and spectrograph optics.…”

3D-Spectroscopy of Dense Stellar Populations

“…1.2) is an instrument of the third category: a field slicer divides the image into sub-fields that are sent to 24 identical IFUs (Laurent et al, 2010), where the image slicers split the image again, before the light reaches the spectrographs. Each of the 24 spectrographs has a detector containing a 4k×4k CCD with 15 µm pixels.…”