Dr. Olivier Flasseur Profile

Dr. Olivier Flasseur

Associate Researcher at CRAL / CNRS

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Publications (9)

Proceedings Article | 5 August 2024 Presentation + Paper

HARMONI at ELT: project status and instrument overview

Niranjan Thatte, Dave Melotte, Benoit Neichel, David Le Mignant, Phil Rees, Fraser Clarke, Vanessa Ferraro-Wood, Oscar Gonzalez, Maia Jones, Alonso Álvarez Urueña, Heribert Argelaguet Vilaseca, Santiago Arribas Mocoroa, José Antonio Caballero, Gonzalo José Carracedo Carballal, Alberto Estrada Piqueras, Irene Ferro, Miriam García García, Isabella Lamperti, Miguel Pereira Santaella, Michele Perna, Javier Piqueras Lopez, Nicolas Bouché, Didier Boudon, Eric Daguise, Nicola Domenis, Jérémy Fensch, Olivier Olivier Flasseur, Rémi Giroud, Matthieu Guibert, Aurelien Jarno, Alexandre Jeanneau, Jens-Kristian Krogager, Maud Langlois, Florence Laurent, Magali Loupias, Jean-Emmanuel Migniau, Dieu Nguyen, Laure Piqueras, Alban Remillieux, Johan Richard, Arlette Pecontal, Lisa Bardou, David Barr, Sylvain Cetre, Sofia Dimoudi, Marc Dubbeldam, Andrew Dunn, Dimitri Gadotti, Joss Guy, David King, Anna McLeod, Simon Morris, Tim Morris, Kieran O'Brien, Emily Ronson, Russell Smith, Lazar Staykov, Mark Swinbank, Matteo Accardo, Domingo Alvarez Mendez, Pablo Alberto Fuerte Rodriguez, Elizabeth George, Derek Ives, Leander Mehrgan, Eric Mueller, Javier Reyes, Ralf Conzelmann, Pablo Gutierrez Cheetham, Angel Alonso Sanchez, Giuseppina Battaglia, Miguel Cagigas, Julio Castro-Almazán, Haresh Chulani, Graciela Delgado-García, Patricia Fernandez Izquierdo, Donaji Esparza-Arredondo, Begoña García-Lorenzo, Alberto Hernández González, Elvio Hernández Suárez, Javier Licandro, Enrique Joven, Roberto López López, Alejandro Antonio Lujan Gonzalez, Yolanda Martín Hernando, Ignacio Martín-Navarro, Evencio Mediavilla, Saúl Menéndez Mendoza, Luz Maria Montoya Martínez, José Peñate Castro, Felipe Murgas, Enric Pallé, Álvaro Pérez, Jose Luis Rasilla, Rafael Rebolo, Horacio Rodríguez, Luis Fernando Rodríguez Ramos, Victor Sánchez Béjar, Tariq Shahbaz, Afrodisio Vega Moreno, Teodora Viera, Mickaël Bonnefoy, Tony Bret, Alexis Carlotti, Jean-Jacques Correia, Stéphane Curaba, Alain Delboulbé, Sylvain Guieu, Adrien Hours, Zoltan Hubert, Laurent Jocou, Yves Magnard, Laurence Michaud, Thibaut Moulin, Fabrice Pancher, Patrick Rabou, Sylvain Rochat, Eric Stadler, Thierry Contini, Marie Larrieu, Sébastien Mamessier, Olivier Boebion, Yan Fantei-Caujolle, Daniel Lecron, Philippe Amram, Patrick Blanchard, William Bon, Anne Bonnefoi, Alexandre Bozier, William Ceria, Zalpha Challita, Yannick Charles, Elodie Choquet, Anne Costille, Audrey Delsanti, Kjetil Dohlen, Franck Ducret, Kacem El Hadi, Benjamin Foulon, Jean-Luc Gimenez, Olivier Groussin, Marc Jaquet, Edgard Renault, Paul Rouquette, Patrice Sanchez, Arthur Vigan, Annie Zavagno, Romain Fétick, Thierry Fusco, Cedric Héritier, Jean-Francois Sauvage, Nicolas Vedrenne, Demet Aksoy, Martin Caldwell, Ann Fitzpatrick, Carl Geddert, Peter Hiscock, Emma Johnson, Murali Nalagatla, Louise Saraff, Joe Shreeves, Matthew Tildesley, Mark Wells, Anastasios Aretos, Lee Barrett, Martin Black, Charlotte Bond, Saskia Brierley, Ian Bryson, Amelia Calderhead, Kenny Campbell, James Carruthers, Lee Chapman, William Cochrane, Rory Gillespie, Joel Harman, Douglas Harvey, Eamonn Harvey, Bethany Johnson, Tom Louth, Mike MacIntosh, Anna MacIver, Chris Miller, David Montgomery, Meenu Murali, John Murray, Norman O'Malley, Ruben Sanchez-Janssen, Noah Schwartz, Patrick Smith, Jonathan Strachan, Stephen Todd, Dawn Wasley, Sandi Wilson, Junyi Zhou, Eric Bell, Oleg Gnedin, Kayhan Gultekin, Mario Mateo, Michael Meyer, Jayne Birkby, Liam Boland, Michele Cappellari, Edgar Castillo Dominguez, David Gooding, Kearn Grisdale, Andrea Hidalgo, James Kariuki, Ian Lewis, Kieran McCall, R. Elliot Meyer, Eduard Muslimov, Adam Lowe, Zeynep Ozer, Sophie Paszynska, Dimitra Rigopoulou, Matthias Tecza, Alec York

Proceedings Volume 13096, 1309614 (2024) https://doi.org/10.1117/12.3018520

KEYWORDS: Equipment, Adaptive optics, Design, Telescopes, Spectrographs, Stars, Signal to noise ratio, Image quality, Cameras

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Proceedings Article | 30 August 2022 Poster + Paper

Optimal multi-epoch combination of direct imaging observations for improved exoplanet detection

Jules Dallant, Maud Langlois, Éric Thiébaut, Olivier Flasseur

Proceedings Volume 12185, 1218537 (2022) https://doi.org/10.1117/12.2630053

KEYWORDS: Signal to noise ratio, Exoplanets, Detection and tracking algorithms, Planets, Exoplanetary science, Stars, Sensors, Error analysis, Data modeling, Astrophysics

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Proceedings Article | 30 August 2022 Poster + Paper

Exoplanet detection in angular differential imaging: combining a statistics-based learning with a deep-based learning for improved detections

Olivier Flasseur, Théo Bodrito, Julien Mairal, Jean Ponce, Maud Langlois, Anne-Marie Lagrange

Proceedings Volume 12185, 121853S (2022) https://doi.org/10.1117/12.2629849

KEYWORDS: Data modeling, Statistical analysis, Exoplanetary science, Detection and tracking algorithms

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Direct imaging is an active research topic in astronomy for the detection and the characterization of young substellar objects. The very high contrast between the host star and its companions makes detection particularly challenging. In addition to the use of an extreme adaptive optics system and a coronagraph to strongly attenuate the starlight contamination, dedicated post-processing methods combining several images recorded with the pupil tracking mode of the telescope are needed. In previous works, we have presented the PACO algorithm capturing the spatial correlations of the data with a multi-variate Gaussian model whose parameters are estimated in a data-driven fashion at the scale of a patch of a few tens of pixels. PACO is parameter free and delivers reliable detection confidences with an improved sensitivity compared to the standard methods of the field (e.g., cADI, PCA, TLOCI ). However, there is a room for improvement in the detection sensitivity due to the approximate fidelity of the PACO statistical model with respect to the observations. We propose to combine the statistics-based model of PACO with a deep learning approach in a three-step algorithm. First, the data are centered and whitened locally using the PACO framework to improve the stationarity and the contrast in a preprocessing step. Second, a convolutional neural network is trained in a supervised fashion to detect the signature of synthetic sources in the preprocessed science data. The network is trained from scratch with a custom data augmentation strategy allowing to generate a large training set from a single spatio-temporal dataset. Finally, the trained network is applied to the preprocessed observations and delivers a detection map. We apply our method on eleven datasets from the VLT/SPHERE-IRDIS instrument and compare our method with PACO and other baselines of the field (cADI, PCA). Our results show that the proposed method performs on-par with or better than these algorithms, with a contrast improvement up to half a magnitude with respect to PACO.

Proceedings Article | 30 August 2022 Poster + Paper

Multispectral image reconstruction of faint circumstellar environments from high contrast angular spectral differential imaging (ASDI) data

Olivier Flasseur, Samuel Thé, Loïc Denis, Éric Thiébaut, Maud Langlois

Proceedings Volume 12185, 121853U (2022) https://doi.org/10.1117/12.2630362

KEYWORDS: Reconstruction algorithms, Statistical analysis, Data modeling, Statistical modeling

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Proceedings Article | 13 December 2020 Poster + Paper

Exoplanet imaging data challenge: benchmarking the various image processing methods for exoplanet detection

F. Cantalloube, C. Gomez-Gonzalez, O. Absil, C. Cantero, R. Bacher, M. Bonse, M. Bottom, C.-H. Dahlqvist, C. Desgrange, O. Flasseur, T. Fuhrmann, Th. Henning, R. Jensen-Clem, M. Kenworthy, D. Mawet, D. Mesa, T. Meshkat, D. Mouillet, A. Müller, E. Nasedkin, B. Pairet, S. Piérard, J.-B. Ruffio, M. Samland, J. Stone, M. Van Droogenbroeck

Proceedings Volume 11448, 114485A (2020) https://doi.org/10.1117/12.2574803

KEYWORDS: Exoplanets, Algorithm development, Planets, Stars, Adaptive optics, Coronagraphy, Interference (communication), Detection and tracking algorithms

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Proceedings Article | 30 March 2020 Presentation

Accounting for the nonstationary correlated noise in digital holography (Conference Presentation)

Olivier Flasseur, Loïc Denis, Éric Thiébaut, Thomas Olivier, Corinne Fournier

Proceedings Volume 11351, 1135113 (2020) https://doi.org/10.1117/12.2559941

KEYWORDS: Digital holography, Signal detection, Diffraction, Reflection, Optical components, Statistical analysis, Algorithm development, Detection and tracking algorithms, Holography, Microscopes

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Proceedings Article | 10 July 2018 Paper

Exoplanet detection in angular and spectral differential imaging: local learning of background correlations for improved detections

Olivier Flasseur, Loïc Denis, Éric Thiébaut, Maud Langlois

Proceedings Volume 10703, 107032R (2018) https://doi.org/10.1117/12.2313601

KEYWORDS: Exoplanets, Signal to noise ratio, Statistical analysis, Stars, Detection and tracking algorithms, Exoplanetary science, Point spread functions, Binary data, Spectrographs, Imaging systems

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