Mechanical design evolution of the VIRUS instrument for volume production and deployment

The Visible Integral-Field Replicable Unit Spectrograph (VIRUS) is an integral field spectrograph to support observations for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The VIRUS instrument is fed by more than 33,000 optical fibers and consists of 150 spectrographs in 75 individual, identical units. This paper discusses the evolution in mechanical design of the VIRUS unit spectrographs to maximize the cost benefit from volume production. Design features which enable volume manufacture and assembly are discussed. Strategies for reducing part count while enabling precision alignment are detailed. Design considerations for deployment, operation, and maintenance en mass at the Hobby-Eberly Telescope are also made. In addition, several enabling technologies are described including the use of cast aluminum in vacuum housings, use of cast Invar, and processing cast parts for precision tolerances.

[1]  Taylor S. Chonis,et al.  Development of a cryogenic system for the VIRUS array of 150 spectrographs for the Hobby-Eberly Telescope , 2010, Astronomical Telescopes + Instrumentation.

[2]  D. O. Astronomy,et al.  The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX): Description and Early Pilot Survey Results , 2008, 0806.0183.

[3]  Travis Prochaska,et al.  Development of VIRUS alignment and assembly fixtures , 2010, Astronomical Telescopes + Instrumentation.

[4]  Andreas Kelz,et al.  Design, construction, and performance of VIRUS-P: the prototype of a highly replicated integral-field spectrograph for HET , 2008, Astronomical Telescopes + Instrumentation.

[5]  Phillip J. MacQueen,et al.  VIRUS: an ultracheap 1000-object IFU spectrograph , 2002, SPIE Astronomical Telescopes + Instrumentation.

[6]  Phillip J. MacQueen,et al.  VIRUS-P: camera design and performance , 2008, Astronomical Telescopes + Instrumentation.

[7]  Andreas Kelz a,et al.  Prototype development of the Integral-Field unit for VIRUS , 2006 .

[8]  Andreas Kelz,et al.  Focal ratio degradation and transmission in VIRUS-P optical fibers , 2008, Astronomical Telescopes + Instrumentation.

[9]  Phillip J. MacQueen,et al.  Mechanical design of VIRUS-P for the McDonald 2.7m Harlan J. Smith Telescope , 2008, Astronomical Telescopes + Instrumentation.

[10]  Phillip J. MacQueen,et al.  Current status of the HETDEX fiber optic support system , 2008, Astronomical Telescopes + Instrumentation.

[11]  Phillip J. MacQueen,et al.  Volume phase holographic grating performance on the VIRUS-P instrument , 2008, Astronomical Telescopes + Instrumentation.

[12]  Ralf Bender,et al.  VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope , 2010, Astronomical Telescopes + Instrumentation.

[13]  Andreas Kelz,et al.  Production-line assembly of 150+ VIRUS spectrographs , 2010, Astronomical Telescopes + Instrumentation.