Optical design of CAOS: a high-resolution spectropolarimeter for the Catania Astrophysical Observatory 0.91-m telescope

CAOS (Catania Astrophysical Observatory Spectrograph) is a high-resolution (R~60,000), fiber fed, bench-mounted, prism cross-dispersed, white-pupil R-4 echelle spectrograph with polarimetric capabilities, for the 0.91m telescope on Mt. Etna. Wavelengths from 390 to 710 nm are covered in one-shot with a 2Kx2K 13.5 micron CCD. Inherent high efficiency of the spectrograph and optimum matching between fibers and spectrograph will allow high throughput for the overall system. This instrument will replace the existing spectrograph, with a net gain in spectral resolution (about a factor 2) and in efficiency (about a factor 10), extending current studies undertaken by Catania Astrophysical Observatory in stellar physics.