Mr. Nicolas Tchoubaklian Profile

Nicolas Tchoubaklian

at Lab d'Astrophysique de Marseille

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Publications (4)

Proceedings Article | 30 August 2022 Presentation + Paper

Connecting SPHERE and CRIRES+ for the characterisation of young exoplanets at high spectral resolution: status update of VLT/HiRISE

A. Vigan, M. Lopez, M. El Morsy, E. Muslimov, A. Viret, G. Zins, G. Murray, A. Costille, G. P. P. Otten, U. Seemann, H. Anwand-Heerwart, K. Dohlen, P. Blanchard, J. Garcia, Y. Charles, N. Tchoubaklian, T. Ely, M. Phillips, J. Paufique, J.-L. Beuzit, M. Houllé, J. Costes, R. Pourcelot, I. Baraffe, R. Dorn, M. Jaquet, M. Kasper, A. Reiners, A. Smette, L. Blanco, L. Pallanca, A. Carlotti, É. Choquet, D. Mouillet, M. N'Diaye

Proceedings Volume 12185, 121850S (2022) https://doi.org/10.1117/12.2629208

KEYWORDS: Optical spheres, Calibration, Finite element methods, Fiber science, Telescopes, Exoplanets, Optics manufacturing, Spectrographs, Spectral resolution, Planets

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Proceedings Article | 11 June 2021 Open Access

Blazed gratings on convex substrates for high throughput spectrographs for Earth and Universe observation

Frédéric Zamkotsian, Igor Zhurminsky, Patrick Lanzoni, Nicolas Tchoubaklian, Fabian Lütolf, Marc Schnieper, Christian Schneider, Sören Fricke, Marin Fouchier, Myriam Zerrad, Claude Amra, Vincent Costes, Jacques Loesel

Proceedings Volume 11852, 118520N (2021) https://doi.org/10.1117/12.2599169

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In next generation space instrumentation for Earth and Universe Observation, new instrument concepts include often non planar gratings. Their realization is complex and costly. We propose a new technology for designing and realizing convex blazed gratings for high throughput spectrographs. For this purpose, our requirements are driven by a Digital-Micromirror-Device-based (DMD) MOS instrument to be mounted on the Telescopio Nazionale Galileo (TNG) and called BATMAN. The two-arm instrument is providing in parallel imaging and spectroscopic capabilities. The objects/field selector is a 2048 x 1080 micromirrors DMD, placed at the focal plane of the telescope; it is used as a programmable multi-slit mask at the entrance of the spectrograph. The compact Offner-type spectrograph design contains a low density convex grating to disperse light. For optimization of the spectrograph efficiency, this convex grating must be blazed. A blazed reflective grating has been designed with a period of 3300 nm and a blaze angle of 5.04°, and fabricated into convex substrates with 225 mm radius of curvature and a footprint diameter of 63.5 mm. The blaze is optimized for the center wavelength of 580 nm within the spectral range of 400 – 800 nm. Such gratings have been fabricated and coated with a silver-based layer, with a final 7° blaze angle over the whole surface. Efficiency close to 90% on the 1st diffraction order at 700nm has been obtained, measured on BATMAN spectroscopic arm. Detailed mapping of the blazed grating showed a very good period uniformity with up to 0.5% deviation. Grating depth and blaze angle have higher deviation, up to 7%. An optimized device with the exact required blaze angle would reach the same efficiency and be centered on the mid of 400-800nm wavelength band: its realization is on-going. The grating brings a significant contribution in the total amount of straylight at instrument level. Their straylight level remains a critical issue, and its reduction by specific and controlled implementation of improvements in manufacturing process is a challenge to tackle. Preliminary straylight measurement has been done and shows a lowest straylight level below 10^-2 sr^-1 between the diffraction orders. This new type of non-planar reflective gratings will be the key component for future high throughput spectrographs in space missions.

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Proceedings Article | 12 July 2019 Open Access

Convex blazed gratings for high throughput spectrographs in space missions

Frédéric Zamkotsian, Igor Zhurminsky, Patrick Lanzoni, Nicolas Tchoubaklian, Christian Schneider, Sören Fricke, Marc Schnieper, Fabian Lütolf, Clément Luitot, Vincent Costes

Proceedings Volume 11180, 1118051 (2019) https://doi.org/10.1117/12.2536100

KEYWORDS: Spectrographs, Diffraction gratings, Space operations, Molybdenum, Spectroscopes, Optical design, Digital micromirror devices, Imaging spectroscopy, Reflectivity, Aerospace engineering

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Proceedings Article | 6 July 2018 Paper

BATMAN @ TNG: instrument integration and performance

Frederic Zamkotsian, Patrick Lanzoni, Nicolas Tchoubaklian, Harald Ramarijaona, Manuele Moschetti, Marco Riva, Marc Jaquet, Paolo Spano, William Bon, Mathieu Vachey, Luciano Nicastro, Emilio Molinari, Rosario Cosentino, Adriano Ghedina, Manuel Gonzalez, Walter Boschin, Paolo Di Marcantonio, Igor Coretti, Roberto Cirami, Filippo Zerbi, Luca Valenziano

Proceedings Volume 10702, 107025P (2018) https://doi.org/10.1117/12.2315222

KEYWORDS: Digital micromirror devices, Mirrors, Micromirrors, Spectroscopes, Spectrographs, Imaging spectroscopy, Telescopes, Cameras, Astronomical instrumentation

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