Feros Homepage

Instrument Description

The following figures gives an impression of the overall layout of the Fiber-fed Extended Range Optical Spectrograph FEROS in its temperature controlled room at the Coudé room of the ESO 1.52-m telescope.

Optical Layout

The optical layout of FEROS and its schematic optical train is shown in the following figures:

Two fibers are coupled to the Cassegrain focus of the telescope by micro lenses. In the Coudé room, where the bench-mounted spectrograph is located, the fiber exit is converted to the F/11 focal ratio accepted by the spectrograph via a F/N lens system. A two-beam, two-slice image slicer in the F/11 focal plane halves the width of the images of the two fibers in the direction of dispersion. The fibers are re-imaged on the echelle grating through the first collimator. Then, the light goes back to the first collimator and is reflected by the folding mirror to the second collimator. The entrance surface of the prism crossdisperser is located near the pupil image and the light is finally imaged by the dioptric camera on the detector. The detector foreseen is a monolithic 2048x4096 15 micron pixel CCD.

The beam of the spectrograph is 135 mm in diameter. The fiber input/output focal ratio is F/4.6, the collimators focal ratio is F/11 and that of the camera is F/3.0.

Opto-mechanical Layout

A more detailed opto-mechanical layout of FEROS is shown in the following figure (for more detailed drawings click on the individual components).

Fiber-Link

The following pictures gives some details on the FEROS fiber link:

Image Slicer

The following pictures gives some details on the FEROS image slicer:

[Rainbowline]

If you have any comments on the FEROS project, please send me a mail .

FEROS homepage / A.Kaufer@lsw.uni-heidelberg.de

Last modified: Fri Jan 26 10:09:11 MET 2001