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Proceedings Paper • Open Access

Manufacturing and qualification of the QM mirror for the high-resolution spectrometer of the FLEX mission
Author(s): Luigina Arcangeli; Giovanni Bianucci; Fabio Marioni; Ruben Mazzoleni; Massimiliano Rossi; Marco Terraneo; Fabio E. Zocchi; Marco Meini; Francesco Galeotti; Riccardo Gabrieli; Fabio Belli; Matteo Taccola

Paper Abstract

FLORIS (FLuorescence Imaging Spectrometer) is the single High-Resolution Spectrometer instrument of the FLEX (FLuorescence EXplorer) mission, currently under development by the European Space Agency as the eighth Earth Explorer Mission. The goal of the mission is the monitoring of the chlorophyll fluorescence of plants giving information about their photosynthetic activity.

Leonardo Avionics & Space System Division is the prime contractor for the FLORIS Instrument for which Media Lario is manufacturing the QM unit of the spherical mirror included in the High-Resolution Spectrometer (HRSPE), hereafter called HRM mirror.

The High-Resolution Mirror is a 250-mm diameter spherical mirror with a radius of curvature of approximately 440 mm. For the mirror substrate, Leonardo has selected the Aluminium alloy AlSi40, a special alloy with 40% Silicon content, coated with a hard polishing layer of Nickel Phosphorus (NiP), deposited by electroless chemical process. The Silicon content allows this special Aluminium alloy to have the same coefficient of thermal expansion (CTE) of the NiP layer, therefore preventing thermal deformations deriving from the bimetallic effect. The mirror structure is light-weighted to approximately 2.8 kg. The required wave-front error of the mirror is better than 0.5 fringes PV, while the surface microroughness has been specified at 0.5 nm RMS due to stringent straylight requirements of the FLORIS instrument.

Media Lario has been selected for the mirror development phase because of their experience in the design and manufacturing of AlSi/NiP mirrors demonstrated in the development of the Earth Observation optical payload for small satellites (called STREEGO), based on an AlSi40 TMA telescope. The manufacturing process includes precision diamond turning, optical figuring and super-polishing. The optical coating will be done by Leonardo at their thin-films facility of Carsoli, Italy. Since the recipe prescribes to pre-heat the mirror surface at 100° C, Media Lario will qualify the mirror substrate with -25/+110°C thermal cycles to ensure adequate thermal stability for the coating process.

Paper Details

Date Published: 12 July 2019
PDF: 7 pages
Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, 111808H (12 July 2019); doi: 10.1117/12.2536224
Show Author Affiliations
Luigina Arcangeli, Media Lario S.r.l. (Italy)
Giovanni Bianucci, Media Lario S.r.l. (Italy)
Fabio Marioni, Media Lario S.r.l. (Italy)
Ruben Mazzoleni, Media Lario S.r.l. (Italy)
Massimiliano Rossi, Media Lario S.r.l. (Italy)
Marco Terraneo, Media Lario S.r.l. (Italy)
Fabio E. Zocchi, Media Lario S.r.l. (Italy)
Marco Meini, Leonardo (Italy)
Francesco Galeotti, Leonardo (Italy)
Riccardo Gabrieli, Leonardo (Italy)
Fabio Belli, Leonardo (Italy)
Matteo Taccola, European Space Research and Technology Ctr. (Netherlands)

Published in SPIE Proceedings Vol. 11180:
International Conference on Space Optics — ICSO 2018
Zoran Sodnik; Nikos Karafolas; Bruno Cugny, Editor(s)

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