| Type |
Conference Paper |
| Names |
Michael P. Smith, Kenneth H. Nordsieck, Eric B. Burgh, Jeffrey W. Percival, T. B. Williams, Darragh O'Donohue, James O'Connor, J. Alan Schier |
| Conference Name |
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series |
| Volume |
6269 |
| Pages |
72 |
| Date |
July 1, 2006 |
| Short Title |
The prime focus imaging spectrograph for the Southern African Large Telescope |
| URL |
http://adsabs.harvard.edu/abs/2006SPIE.6269E..72S |
| Library Catalog |
NASA ADS |
| Abstract |
The Prime Focus Imaging Spectrograph (PFIS) is a first light instrument
for the Southern African Large Telescope (SALT). PFIS is a versatile
instrument designed to operate in a number of scientific modes by
utilizing volume phase holographic gratings, Fabry-Perot etalons, and
polarimetric optics, which are manipulated in and out of the beam using
various placement mechanisms. The instrument is mounted at the prime
focus 15m above the primary mirror and tilted at 37°. This remote
placement and the need for 240° of rotation about the optical axis
raises important design issues with mass, flexure and access. The
instrument structure provides the interface to the telescope Prime Focus
Instrument Platform (PFIP) as well as support points for all the optics,
mechanisms and electrical equipment. The structure is a welded open
truss of hollow, square-section Invar beams. The open truss provides the
highest stiffness to weight ratio and minimizes the effect of wind
loading, while the use of Invar negates the effects of thermal
expansion. It has been designed using finite element analysis in
conjunction with an optical tolerance analysis of the optics nodes to
minimize effective image motion under the varying gravity load. The
fundamentals of the design of the structure to minimize the flexure and
its effect on image motion, the motivation for using the open Invar
truss structure, and the design of the remotely operated mechanisms are
discussed. In 2005 PFIS was installed and commissioned on SALT in South
Africa. Included in this text are some of the results and experiences of
taking PFIS into operation. |