The SOAR Integral Field Unit Spectrograph (SIFS) is fed by an integral field unit composed of a bi-dimensional
arrangement of 1300 optical fibers. It has been developed in Brazil by a team of scientists and engineers led by the
National Laboratory of Astrophysics (MCT/LNA) and the Department of Astronomy of the Institute of Astronomy,
Geophysics and Atmospheric Sciences of the University of São Paulo (IAG/USP). It comprises three major subsystems;
a fore-optics installed on the Nasmyth port of the telescope or the SOAR Adaptive Optics Module, a 14-m optical fiber
IFU, and a bench-mounted spectrograph installed on the telescope fork. SIFS is successfully assembled and tested on the
SOAR Telescope in Chile and has now moved to the commissioning phase. This paper reports on technical
characteristics of the mechanical design and the assembly, integration and technical activities.
SIFS is a lenslet/fiber Integral Field Unit Spectrograph which has just been delivered to the SOAR 4.1m telescope in
Chile. The instrument was designed and constructed by the National Laboratory of Astrophysics (MCT/LNA) in
collaboration with the Department of Astronomy of the Institute of Astronomy, Geophysics and Atmospheric Sciences of
the University of Sao Paulo (IAG/USP). It is designed to operate at both the raw Nasmyth and the SAM (the SOAR
Adaptive Optics Module) which delivers GLAO-corrected images in optical wave-bands longward of 500nm. The
lenslets have a 1mm pitch feeding a set of 1,300 fibres in a 26-by-50 format. Sets of deployable fore-optics convert the
f/16.5 input beam to give samplings between ~0.1 and 0.3 arcsec. The fiber output is in the form of a curved, pupil-centric,
long-slit which is fed into a bench-mounted spectrograph. An off-axis Maksutov collimates the beam onto a set
of VPH gratings and thence imaged by an f/3 refractive camera onto a 2-by-1 mosaic of 2k-by-4k E2V CCDs. The
camera is articulated over a >90 deg. angle to allow the grating/camera combination to operate in a transmission Littrow
configuration. The wavelength range is limited by the CCDs to the 350 to 1000nm range with spectral resolution
maxima of ~20,000. The paper will review the optical design of the spectrograph and the methods used to fabricate the
As part of the Brazilian contribution to the 4.2 m SOAR telescope project we are building the Integral Field Unit spectrograph, "SIFUS." With the aim of testing the performance of optical fibers with 50 microns core size on IFUs, we constructed a prototype of the IFU and a spectrograph that were installed at the 1.6 m telescope of the Observatorio do Pico dos Dias (OPD), managed by Laboratorio Nacional de Astrofisica (LNA) in Brazil. The IFU has 512 fibers coupled to a LIMO microlens array (16 x 32) covering a 15" x 30" field on the sky. The spectrograph is a medium resolution instrument, operating in a quasi-Littrow mode. It was based on the design of the SPIRAL spectrograph built by the Anglo-Australian Observatory. The name Eucalyptus was given following the name of the native Australian tree that adapted very well in Brazil and it was given in recognition to the collaboration with the colleagues of the Anglo-Australian Observatory. The instrument first light occurred in the first semester of 2001. The results confirmed the possibility of using the adopted fibers and construction techniques for the SIFUS. We present the features of the instrument, some examples of the scientific data obtained, and the status of the commissioning, calibration and automation plans. The efficiency of this IFU was determined to be 53% during telescope commissioning tests.
We present the project of an optical spectrograph equipped with a 1300-element Integral Field Unit (IFU), that will be one of the main instruments of the SOAR (4m) telescope. The instrument consists of two separate parts, the fore-optics and the bench spectrograph, that are connected by an 11 m long fiber bundle. The fore optics system is installed at one of the Nasmyth focii of the telescope, and
produces an image of the observed object on a 26x50 array of square microlenses, each 1 mm x 1 mm lens feeding one fiber. The fibers have 50 micron cores, and are aligned at the entrance of bench spectrograph to form a slit that feeds a 100 mm beam collimator.
A set of Volume Phase-Holographic (VPH) transmission gratings can be interchanged by remote control, providing a choice of resolution and wavelength coverage. The spectrograph is tunable over the wavelength range 350 to 1000 nm, with resolution R from about 5000 to 20000. This spectrograph is ideally suited for high spatial resolution studies, with a sampled area of the sky 8" x 15", with 0.30" per microlens, in the mode to be used with the tip-tilt correction of SOAR. The project has been approved at the Project Design Review and the spectrograph is presently being constructed.