We are in charge of the manufacturing and delivery of all the super-polished mirrors of the NASA/WFIRST Coronagraphic Instrument, dedicated to exoplanets imaging and characterisation from space. The manufacturing method has been developed and optimised by PhD student Mélanie ROULET, who combined the potential of additive manufacturing with the stress-polishing technique, only technique capable to provide extremely smooth surfaces for freeform mirrors, with a roughness down to 2 Angströms.

The picture below illustrates the Power Spectral Density obtained after the stress polishing of the OAP #7 prototype, developed in the frame of the ERC ICARUS. This is compared to the 2*f^{-2.5} specification. The very low level of the PSD expresses the very low level of noise in the final image. The zone between [3;30] cycles per pupil corresponds to the zone where the exoplanets are located in the final image of the instrument. Getting a very low level of noise helps revealing the tiny exoplanets which luminosity is a million to a billion times lower than the parent star they are orbiting.

The CASTLE telescope, first curved sensors on-sky demonstration for astronomy

CASTLE, the Calar Alto Schmidt-Lemaître Explorer is the very first on-sky demonstration of curved sensors for an astronomical application. It will address two cutting-edge astrophysical topics: the search for the electromagnetic counterpart of gravitational waves and the observation of Low surface brightness objects. The first light is planned for Summer 2022, it is installed at the summit of the Calar Alto Observatory in Andalousia, south of Spain.
The project is done in collaboration with the companies Pyxalis in Grenoble, Winlight in the south of France and Sinoptic in Shanghai.
The scientific Consortium gathers the Observatory of Strasbourg, the Institute of Astronomy of Andalousia and the Laboratoire d’Astrophysique de Marseille.
This is a 1.2M€ project, funded by the MERAC foundation and the European Astronomical Society-EAS, the French research agency-ANR, the European Community-EC through the European Research Council-ERC and the French national research center-CNRS.

Project Lead and scientist: Simona LOMBARDO (
Opto-mechanical architect: Eduard MUSLIMOV
Mechanical engineer: Ali FAHAD
PhD Student, integration & tests: Kelly JOAQUINA
French side: Emmanuel HUGOT (CNRS-LAM) & Pierre Alain DUC (CNRS-ObAS)
Spanish side: Francisco PRADA (CSIC-IAA)

Related publications
White paper:  Lombardo, Hugot, Duc, Prada et al “CASTLE: performances and science cases”
Simona Lombardo+2019 “Next-generation telescopes with curved focal surface for ultra-low surface brightness surveys”, Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P – Oxford Open Option A, In press, ⟨10.1093/mnras/stz2068⟩. ⟨hal-02263343⟩
Eduard Muslimov+2017, “Fast, wide‐field and distortion‐free telescope with curved detectors for surveys at ultralow surface brightness”. Applied optics, Optical Society of America, 2017, 56 (31), pp.8639-8647. ⟨10.1364/AO.56.008639⟩. ⟨hal-01678500⟩


Picture credit E. Muslimov – CNRS-LAM

(The project is co-funded by the CNRS, the CSIC, the MERAC Foundation and the European Commission through the ERC-STG-2015 – ICARUS-678777 and the ERC-PoC-CURVE-X-839271)