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Thermal tests of birefringent plates in molecular adhesion for spatial ultra-violet polarimetry

Le Gal, Maelle and Neiner, Coralie and Louvel de Monceaux, Matthieu and Nguyen-Tuong, Napoléon and Parisot, Jérôme and Collin, Claude and Reess, Jean-Michel and Bonafous, Marion and Blanchard, Cyril and Pelleau, Aurélien and Baudoz, Pierre and Pertenais, Martin and Costes, Vincent and Brachet, Franck and Locatello, Elsa and Desmarres, Jean-Michel (2020) Thermal tests of birefringent plates in molecular adhesion for spatial ultra-violet polarimetry. In: Proceedings of SPIE, 11451. SPIE, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV, Online. doi: 10.1117/12.2561439.

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Official URL: https://doi.org/10.1117/12.2561439

Abstract

High-resolution spectropolarimetry is a technique used to study many astronomical objects including stellar magnetic fields. It has mainly been used on ground for optical and, more recently, infrared (IR) observations. Space mission projects including ultra-violet (UV) high-resolution spectropolarimetry, such as Pollux onboard LUVOIR proposed to NASA, are being studied in Europe under CNES leadership. Bringing a spectropolarimeter into space means that the instrument should be prepared for space environment including temperatures. The UV polarimeter we are considering is composed by a rotating modulator and an analyzer. Both components are made of magnesium fluoride (MgF2). The modulator is a rotating block of waveplates in molecular adhesion, each plate having its own fast axis. The analyzer is a Wollaston prism, also made with molecular adhesion. MgF2 being birefringent, the plates and prism are anisotropic and will dilate and retract due to thermal changes differently along their fast and slow axes. Each plate having its own fast axis, the thermal changes will create stress at the interfaces, i.e. at the molecular adhesion between the plates. This study focuses on the most critical part: the plates of the modulator. To demonstrate the resistance of the modulator and increase its technological readiness level (TRL), an optical bench including interferometry has been set at the Paris Observatory. It allows us to observe in real time the state of the molecular adhesion between plates as they are submitted to thermal changes in a vacuum chamber. Additional samples have been tested in a thermal vacuum chamber at CNES. This article describes the modulator using molecular adhesion, the test experiments, and the conclusion of this thermal study. Although molecular adhesion broke in 2 samples during thermal cycling, most samples survived which provides encouraging results for this technique.

Item URL in elib:https://elib.dlr.de/140586/
Document Type:Conference or Workshop Item (Poster)
Title:Thermal tests of birefringent plates in molecular adhesion for spatial ultra-violet polarimetry
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Le Gal, MaelleLESIAhttps://orcid.org/0000-0003-0032-2248
Neiner, CoralieLESIAUNSPECIFIED
Louvel de Monceaux, MatthieuLESIAUNSPECIFIED
Nguyen-Tuong, NapoléonLESIAUNSPECIFIED
Parisot, JérômeLESIAUNSPECIFIED
Collin, ClaudeLESIAUNSPECIFIED
Reess, Jean-MichelObservatoire de Paris-Meudon, FranceUNSPECIFIED
Bonafous, MarionLESIAUNSPECIFIED
Blanchard, CyrilLESIAUNSPECIFIED
Pelleau, AurélienLESIAUNSPECIFIED
Baudoz, PierreLESIAUNSPECIFIED
Pertenais, MartinMartin.Pertenais (at) dlr.deUNSPECIFIED
Costes, VincentCNESUNSPECIFIED
Brachet, FranckCNESUNSPECIFIED
Locatello, ElsaCNESUNSPECIFIED
Desmarres, Jean-MichelCNESUNSPECIFIED
Date:13 December 2020
Journal or Publication Title:Proceedings of SPIE
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:Yes
Volume:11451
DOI :10.1117/12.2561439
Status:Published
Keywords:Space, UV, polarimetry, spectropolarimetry
Event Title:SPIE, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV
Event Location:Online
Event Type:international Conference
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space System Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Space System Technology
DLR - Research theme (Project):R - Systems Engineering Optische Systeme (old), R - Explorationsstudien (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Optical Sensor Systems > Space Instruments
Deposited By: Pertenais, Martin
Deposited On:22 Jan 2021 09:19
Last Modified:22 Jan 2021 09:19

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