Tristan Buey

Publications (2)0 Total impact

• Source

  Available from: Frédéric Cassaing

  Article: Current results of the PERSEE testbench: the cophasing control and the polychromatic null rate

  Julien Lozi, Frederic Cassaing, Jean-Michel Le Duigou, Beatrice Sorrente, Jospeh Montri, Jean-Michel Reess, Emilie Lhome, Tristan Buey, Francois Henault, Aurelie Marcotto, Paul Girard, Marc Barillot, Marc Ollivier, Vincent Coude du Foresto
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  ABSTRACT: Stabilizing a nulling interferometer at a nanometric level is the key issue to obtain deep null depths. The PERSEE breadboard has been designed to study and optimize the operation of a cophased nulling bench in the most realistic disturbing environment of a space mission. This presentation focuses on the current results of the PERSEE bench. In terms of metrology, we cophased at 0.33 nm rms for the piston and 80 mas rms for the tip/tilt (0.14% of the Airy disk). A Linear Quadratic Gaussian (LQG) control coupled with an unsupervised vibration identi?cation allows us to maintain that level of correction, even with characteristic vibrations of nulling interferometry space missions. These performances, with an accurate design and alignment of the bench, currently lead to a polychromatic unpolarised null depth of 8.9E-6 stabilized at 3E-7 on the [1.65-2.45] \mum spectral band (37% bandwidth).
  09/2011;
• Source

  Available from: Frédéric Cassaing

  Article: PERSEE: Experimental results on the cophased nulling bench

  Julien Lozi, Frédéric Cassaing, Jean-Michel Le Duigou, Kamel Houairi, Béatrice Sorrente, Joseph Montri, Sophie Jacquinod, Jean-Michel Reess, Laurie Pham, Emilie Lhomé, Tristan Buey, François Hénault, Aurélie Marcotto, Paul Girard, Nicolas Mauclert, Marc Barillot, Vincent Coudé du Foresto, Marc Ollivier
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  ABSTRACT: Nulling interferometry is still a promising method to characterize spectra of exoplanets. One of the main issues is to cophase at a nanometric level each arm despite satellite disturbances. The bench PERSEE aims to prove the feasibility of that technique for spaceborne missions. After a short description of PERSEE, we will first present the results obtained in a simplified configuration: we have cophased down to 0.22 nm rms in optical path difference (OPD) and 60 mas rms in tip/tilt, and have obtained a monochromatic null of 3E-5 stabilized at 3E-6. The goal of 1 nm with additional typical satellite disturbances requires the use of an optimal control law; that is why we elaborated a dedicated Kalman filter. Simulations and experiments show a good rejection of disturbances. Performance of the bench should be enhanced by using a Kalman control law, and we should be able to reach the desired nanometric stability. Following, we will present the first results of the final polychromatic configuration, which includes an achromatic phase shifter, perturbators and optical delay lines. As a conclusion, we give the first more general lessons we have already learned from this experiment, both at system and component levels for a future space mission. Comment: 12 pages, 13 figures
  08/2010;