VXMS: the VISTA extreme multiplex spectrograph

Robert Content, Tom Shanks, Ray Sharples, David Bramall, Will Percival

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A study for a spectrograph delivering at least 10000 slits for galaxies and 20000 for stars over a 2.5 deg2 field have been completed as an answer to the call for proposal for future VISTA MOS instrumentation. In a single night, 65000 galaxy redshifts can be measured to z~0.7 and beyond for measuring the Baryon Acoustic Oscillation (BAO) scale and many other science goals. The design features ten cloned spectrographs which give a smaller total weight and length than a unique spectrograph to make it placable in the space envelope of the Cassegrain focus. The clones use a transparent design including a grism in which all optics are about the size or smaller than the clone rectangular subfield so that they can be tightly packed with little gaps between subfields. Only low cost glasses are used; the variations in chromatic aberrations between bands are compensated by changing a box containing the grism and two adjacent lenses. Two bands cover the 550nm to 900nm wavelength range at resolution of 1100 for blue end and 3000 for red end while another cover the Calcium triplet at 5000. An optional box does imaging but we studied different innovative methods for acquisition without imaging. A new 2.3° corrector was designed that places the pupil before and relatively near the focal plane which permits to give more space at the back of the spectrographs by placing them in a hedgehog configuration. An offaxis field lens in each spectrograph permits to control the pupil position. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Original languageEnglish
Title of host publicationGround-based and airborne instrumentation for astronomy IV
Place of PublicationBellingham
PublisherSociety of Photographic Instrumentation Engineers
ISBN (Print)9780819491473
Publication statusPublished - 2012
EventGround-based and Airborne Instrumentation for Astronomy IV - Amsterdam, Netherlands
Duration: 1 Jul 2012 → …

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-based and Airborne Instrumentation for Astronomy IV
Period1/07/12 → …


  • Multi-object spectrographs
  • cosmology
  • dark energy


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