Proceedings Article | 5 August 2022
Edoardo Maria Alberto Redaelli, Matteo Aliverti, Matteo Genoni, Giorgio Pariani, Luca Oggioni, Marco Riva, Gerardo Avila, Bruno Chazelas, Ian Hughes, Francesco Pepe, Denis Mégevand
KEYWORDS: Spectrographs, Telescopes, Mirrors, Interfaces, Mechanical engineering, Glasses, Optomechanical design, Optics manufacturing, Optical design, Optical alignment
The ESPRESSO spectrograph is a high resolution, super stable echelle cross-dispersed fiber-fed spectrograph, installed in the ESO-VLT Combined Coudé Laboratory of the ESO-VLT in Cerro Paranal. In the framework of the Fiber-Link (FL) recovery project, which was necessary to meet the throughput requirement of the instrument, we redesigned and build the whole fiber bundle. The FL subsystem of ESPRESSO is composed by the input ends, one per telescope and observing mode, which inject the telescope light into the fibers, the double scrambler, the light combiner for the multi-telescope mode, and the spectrograph entrance slit. In this paper we focus on the details of the optical design of the scrambler and the beam combiner, redesigned to ensure proper transmission in the blue, and on the mechanical design of the input ends and the scrambler, aimed to ensure proper reliability, alignment accuracy, stability, and robustness of the scrambler, both in the alignment phase and during the integration in the spectrograph at the telescope.