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Proceedings Paper

An ultra-stable cryostat for the detectors of ESPRESSO
Author(s): Jean Louis Lizon; Olaf Iwert; Sebastian Deiries; Hans Decker; Renate Hinterschuster; Antonio Manescau; Denis Megevand; Eric Mueller; Francesco Alfonso Pepe; Marco Riva
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Paper Abstract

ESPRESSO The Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, is a super-stable Optical High Resolution Spectrograph for the combined coude focus of the VLT. It can be operated by either one of the UTs or collecting the light from up to 4 UTs simultaneously. Given the wide spectral range, the optical path is split into two channels, two large 90 mm x 90 mm CCDs are used to record the full spectrum. In order to achieve the extremely high stability, ESPRESSO has a fixed optical layout; no moving parts are foreseen inside the spectrograph to maximize the stability and repeatability of the instrument performance and to avoid any thermal load generated inside the spectrograph itself. The optical bench is placed in a vacuum vessel hosted in a three level enclosure system able to guarantee temperature stability of the order of 0.001 K and in a vacuum environment. We aim for a stability of the spectral line on the detector pixel matrix in the range of a few nanometers. The paper gives a detailed description of the cryostat with the flexible de-coupling of the Dewar between the vacuum vessel and optical bench. The design including the measures taken in order to provide an optimal thermal connection and a very accurate mechanical referencing of the large chip. We are going to describe the specific experiment which has been set-up in order to verify and physically measure the real stability of the detector “pixels” relative to the rest of the world. We will also present the results obtained with the similar setup measuring the stability of the HARPS detector (the precursor of ESPRESSO) and the preliminary results of the stability of the final ESPRESSO detector system.

Paper Details

Date Published: 9 August 2016
PDF: 13 pages
Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 990866 (9 August 2016); doi: 10.1117/12.2231623
Show Author Affiliations
Jean Louis Lizon, European Southern Observatory (Germany)
Olaf Iwert, European Southern Observatory (Germany)
Sebastian Deiries, European Southern Observatory (Germany)
Hans Decker, European Southern Observatory (Germany)
Renate Hinterschuster, European Southern Observatory (Germany)
Antonio Manescau, European Southern Observatory (Germany)
European Southern Obsevatory (Germany)
Denis Megevand, Observatoire de Genève (Switzerland)
Eric Mueller, Max-Planck-Institut für Astronomie (Germany)
Francesco Alfonso Pepe, Observatoire de Genève (Switzerland)
Marco Riva, INAF - Osservatorio Astronomico di Brera (Italy)

Published in SPIE Proceedings Vol. 9908:
Ground-based and Airborne Instrumentation for Astronomy VI
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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