ESPRESSO: design and analysis of a Coudé-train for a stable and efficient simultaneous optical feeding from the four VLT unit telescopes

Alexandre Cabral; André Moitinho; João Coelho; Jorge Lima; Gerardo Ávila; Bernard-Alexis Delabre; Ricardo Gomes; Denis Mégevand; Filippo Zerbi; Paolo Di Marcantonio; Christophe Lovis; Nuno C. Santos

doi:10.1117/12.926093

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17 September 2012 ESPRESSO: design and analysis of a Coudé-train for a stable and efficient simultaneous optical feeding from the four VLT unit telescopes

Alexandre Cabral, André Moitinho, João Coelho, Jorge Lima, Gerardo Ávila, Bernard-Alexis Delabre, Ricardo Gomes, Denis Mégevand, Filippo Zerbi, Paolo Di Marcantonio, Christophe Lovis, Nuno C. Santos

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Proceedings Volume 8444, Ground-based and Airborne Telescopes IV; 84444F (2012) https://doi.org/10.1117/12.926093
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

ESPRESSO is a fiber-fed, cross-dispersed, high-resolution, echelle spectrograph. Being the first purpose of ESPRESSO to develop a competitive and innovative high-resolution spectrograph to fully exploit the VLT (Very Large Telescope), and allow new science, it is important to develop the VLT array concept bearing in mind the need to obtain the highest stability, while preserving its best efficiency. This high-resolution ultra-stable spectrograph will be installed in the VLT at the Combined Coudé Laboratory (CCL), fed by four Coudé Trains, which brings the light from the Nasmyth platforms of the four VLT Unit Telescopes to the CCL. A previous trade-off analysis, considering the use of mirrors, prisms, lenses or fibers and several possible combinations of them, pointed towards a Full Optics solution, using only conventional optics to launch the light from the telescope into the front-end unit. In this case, the system is composed of a set of prisms and lenses to deliver a pupil and an image in the CCL, including an Atmospheric Dispersion Compensator. In this paper, we present the optical design of the Coudé Trains, the opto-mechanical concept, the main characteristics and expected performances.

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Alexandre Cabral, André Moitinho, João Coelho, Jorge Lima, Gerardo Ávila, Bernard-Alexis Delabre, Ricardo Gomes, Denis Mégevand, Filippo Zerbi, Paolo Di Marcantonio, Christophe Lovis, and Nuno C. Santos "ESPRESSO: design and analysis of a Coudé-train for a stable and efficient simultaneous optical feeding from the four VLT unit telescopes", Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84444F (17 September 2012); https://doi.org/10.1117/12.926093

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