Dr. Jean-Laurent René Dournaux Profile

Dr. Jean-Laurent René Dournaux

Mechanical Engineer at Observatoire de Paris à Meudon

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Author

Publications (21)

Proceedings Article | 29 August 2022 Poster + Paper

A Langsdorf cloud chamber as a complementary educational material to Cherenkov telescopes for the observation of cosmic rays

Emma Rébert, Sébastien Croce, Frédéric Bouley, Timothée Dalo, Jean-Laurent Dournaux, Antoine Gusdorf, Philippe Paris, Hélène Sol

Proceedings Volume 12188, 121882P (2022) https://doi.org/10.1117/12.2629181

KEYWORDS: Clouds, Particles, Atmospheric Cherenkov telescopes, Telescopes, Computer aided design, Atmospheric particles, Prototyping, Physics, Manufacturing, Atmospheric sensing

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Proceedings Article | 29 August 2022 Poster + Paper

Mechanical optimisation of the M1 dish of the small-sized telescope of the future Cherenkov Telescope Array

Jean-Laurent Dournaux, Frédéric Bouley, Emma Rébert, Jean-Michel Huet, Fatima De Frondat, Hélène Sol, Primo Attinà, Carmelo Gargano, Gianpietro Marchiori, Giovanni Pareschi, Salvatore Scuderi, Matteo Spinola, Gianpiero Tagliaferri, Gino Tosti, Alessio Trois

Proceedings Volume 12188, 1218831 (2022) https://doi.org/10.1117/12.2627853

KEYWORDS: Computer aided design, Atmospheric Cherenkov telescopes, Telescopes, Optimization (mathematics), Optical instrument design, Mirrors, Interfaces, Lightweight mirrors, Mechanical engineering, Wind energy

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Proceedings Article | 29 August 2022 Presentation + Paper

The small-sized telescope of CTAO

G. Tagliaferri, A. Antonelli, T. Arnesen, J. Aschersleben, P. Attinà, M. Balbo, S. Bang, M. Barcelo, A. Baryshev, G. Bellassai, D. Berge, C. Bicknell, C. Bigongiari, G. Bonnoli, F. Bouley, A. Brown, A. Bulgarelli, M. Cappi, P. Caraveo, S. Caschera, P. Chadwick, F. Conte, G. Cotter, P. Cristofari, F. De Frondat, E. De Gouveia Dal Pino, N. De Simone, D. Depaoli, J.-L. Dournaux, C. Duffy, S. Einecke, C. Fermino, S. Funk, C. Gargano, G. Giavitto, A. Giuliani, T. Greenshaw, J. Hinton, J.-M. Huet, S. Iovenitti, N. La Palombara, J. Lapington, P. Laporte, S. Leach, L. Lessio, G. Leto, S. Lloyd, F. Lucarelli, S. Lombardi, A. Macchi, E. Martinetti, A. Miccichè, R. Millul, T. Mineo, T. Mitsunari, A. Nayak, G. Nicotra, A. Okumura, G. Pareschi, M. Penno, H. Prokoph, E. Rebert, C. Righi, C. Rulten, F. Russo, R. Zanmar Sanchez, F. Saturni, J. Schaefer, B. Schwab, S. Scuderi, G. Sironi, V. Sliusar, H. Sol, S. Spencer, A. Stamerra, H. Tajima, F. Tavecchio, G. Tosti, A. Trois, M. Vecchi, S. Vercellone, J. Vink, R. Walter, J. Watson, R. White, R. Zanin, L. Zampieri, A. Zech, A. Zink

Proceedings Volume 12182, 121820K (2022) https://doi.org/10.1117/12.2627956

KEYWORDS: Atmospheric Cherenkov telescopes, Telescopes, Cameras, Mirrors, Prototyping, Computer aided design, Control systems, Observatories, Vignetting, Optical instrument design

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Proceedings Article | 10 July 2018 Paper

Application of the topography optimization technique to the design of a lightweight primary mirror for the GCT, a dual-mirror telescope proposed for the Cherenkov Telescope Array

Jean-Laurent Dournaux

Proceedings Volume 10706, 107060C (2018) https://doi.org/10.1117/12.2311628

KEYWORDS: Mirrors, Computer aided design, Atmospheric Cherenkov telescopes, Telescopes, Lightweight mirrors, Optimization (mathematics), Reflectivity, 3D modeling, Solids, Manufacturing

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Optimization techniques are powerful tools for producing lightweight structures with the maximum structural stiffness. They allow an optimized design to be produced directly for a given structure and, in this way, save considerable time in the design phase of a structure by avoiding multiple iterations between the definition of the design under computer-aided design (CAD) and the verification of the performance under finite-element (FE) analysis. There are three classes of optimization: size optimization, shape optimization and topology optimization. The topology optimization technique aims to find an optimal distribution of material given boundary conditions, i.e. the fixing points and the external loads. It starts from an initial volume representing a blank of the structure and removes the most unused material to meet the objective of mass reduction. In optomechanical engineering, this technique is met in the design of lightweight mirrors and especially in the design of their core-cell shapes. To provide reliable and useable results, this technique requires a fine and regular mesh of the mirror as well as a postprocessing of the results by the mechanical engineers. These constraints, combined with the necessity of using 3-D models, contribute an increase in the computation time and complicate the meshing. We propose here an innovative approach to this design problem by using topography optimization instead of topology optimization. Topography optimization, also named bead optimization, is a branch of the shape optimization and consists in introducing beads to a surface in order to increase its structural stiffness. The main advantage of this technique is that shell models can be used instead of solid models, easing the meshing operation and decreasing the number of degrees of freedom in the FE model, and thereby reducing computation cost. This paper presents an example of the application of this technique to the design of the primary mirror panel of the GCT (Gamma-ray Cherenkov Telescope), a dual-mirror 4-meter telescope proposed for the future Cherenkov Telescope Array. FE models and optimizations are made with MD.Patran and MD.Nastran respectively.

Proceedings Article | 6 July 2018 Presentation + Paper

Final characterisation and design of the Gamma-ray Cherenkov Telescope (GCT) for the Cherenkov Telescope Array

O. Le Blanc, G. Fasola, J. M. Huet, R. White, A. Dmytriiev, H. Sol, A. Zech, A. Abchiche, J. P. Amans, T. Armstrong, M. Barcelo, D. Berge, A. Brown, G. Buchholtz, P. Chadwick, P. Clark, G. Cotter, L. Dangeon, F. De Frondat, P. Deiml, J. L. Dournaux, C. Duffy, S. Einecke, S. Flis, S. Funk, G. Giavitto, J. Gironnet, J. Graham, T. Greenshaw, J. Hinton, I. Jégouzo, M. Kraus, J. Lapington, P. Laporte, S. Leach, S. Lloyd, I. Minaya, R. Morier, A. Okumura, H. Prokoph, D. Ross, G. Rowell, C. Rulten, H. Schoorlemmer, J. Schmoll, S. Spencer, M. Stephan, R. Stuik, H. Tajima, J. Thornhill, L. Tibaldo, J. Vink, J. Watson, J. Williams, A. Zink, J. Zorn

Proceedings Volume 10700, 1070010 (2018) https://doi.org/10.1117/12.2313158

KEYWORDS: Atmospheric Cherenkov telescopes, Telescopes, Cameras, Mirrors, Prototyping, Optical instrument design, Computer aided design, Interfaces

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Proceedings Article | 5 January 2018 Open Access

Low frequency noise fiber delay stabilized laser with reduced sensitivity to acceleration

B. Argence, C. Clivati, J.-L. Dournaux, D. Holleville, B. Faure, P. Lemonde, G. Santarelli

Proceedings Volume 10564, 105643N (2018) https://doi.org/10.1117/12.2309248

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Proceedings Article | 10 August 2016 Paper

The Gamma-ray Cherenkov Telescope, an end-to end Schwarzschild-Couder telescope prototype proposed for the Cherenkov Telescope Array

J. L. Dournaux, A. Abchiche, D. Allan, J. P. Amans, T. P. Armstrong, A. Balzer, D. Berge, C. Boisson, J.-J. Bousquet, A. Brown, M. Bryan, G. Buchholtz, P. Chadwick, H. Costantini, G. Cotter, L. Dangeon, M. Daniel, A. De Franco, F. De Frondat, D. Dumas, J. P. Ernenwein, G. Fasola, S. Funk, J. Gironnet, J. Graham, T. Greenshaw, B. Hameau, O. Hervet, N. Hidaka, J.A. Hinton, J.M. Huet, I. Jégouzo, T. Jogler, T. Kawashima, M. Kraush, J. Lapington, P. Laporte, J. Lefaucheur, S. Markoff, T. Melse, L. Mohrmann, P. Molyneux, S. Nolan, A. Okumura, J. Osborne, R. Parsons, S. Rosen, D. Ross, G. Rowell, C. Rulten, Y. Sato, F. Sayède, J. Schmoll, H. Schoorlemmer, M. Servillat, H. Sol, V. Stamatescu, M. Stephan, R. Stuik, J. Sykes, H. Tajima, J. Thornhill, L. Tibaldo, C. Trichard, J. Vink, J. Watson, R. White, N. Yamane, A. Zech, A. Zink

Proceedings Volume 9908, 990848 (2016) https://doi.org/10.1117/12.2232082

KEYWORDS: Atmospheric Cherenkov telescopes, Telescopes, Cameras, Prototyping, Optical instrument design, Gamma radiation, Mirrors, Atmospheric Cherenkov telescopes, Telescopes, Gamma radiation, Space telescopes, Imaging systems, Physics

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Proceedings Article | 27 July 2016 Paper

The GCT camera for the Cherenkov Telescope Array

A. Brown, A. Abchiche, D. Allan, J.-P. Amans, T. Armstrong, A. Balzer, D. Berge, C. Boisson, J.-J. Bousquet, M. Bryan, G. Buchholtz, P. Chadwick, H. Costantini, G. Cotter, M. Daniel, A. De Franco, F. de Frondat, J.-L. Dournaux, D. Dumas, G Fasola, S. Funk, J. Gironnet, J. Graham, T. Greenshaw, O. Hervet, N. Hidaka, J. Hinton, J.-M. Huet, I. Jégouzo, T. Jogler, M. Kraus, J. Lapington, P. Laporte, J. Lefaucheur, S. Markoff, T. Melse, L. Mohrmann, P. Molyneux, S. Nolan, A. Okumura, J. Osborne, R. Parsons, S. Rosen, D. Ross, G. Rowell, Y. Sato, F. Sayede, J. Schmoll, H. Schoorlemmer, M. Servillat, H. Sol, V. Stamatescu, M. Stephan, R. Stuik, J. Sykes, H. Tajima, J. Thornhill, L. Tibaldo, C. Trichard, J. Vink, J. Watson, R. White, N. Yamane, A. Zech, A. Zink, J. Zorn

Proceedings Volume 9906, 99065K (2016) https://doi.org/10.1117/12.2231685

KEYWORDS: Atmospheric Cherenkov telescopes, Telescopes, Cameras, Prototyping, Observatories, Atmospheric Cherenkov telescopes, Telescopes, Electronics, Space telescopes, Mirrors, Field programmable gate arrays, Physics

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Proceedings Article | 22 July 2016 Paper

Aspherical mirrors for the Gamma-ray Cherenkov Telescope, a Schwarschild-Couder prototype proposed for the future Cherenkov Telescope Array

J. L. Dournaux, J. Gironnet, J. M. Huet, P. Laporte, P. Chadwick, D. Dumas, M. Pech, C. Rulten, F. Sayède, J. Schmoll, H. Sol

Proceedings Volume 9912, 991240 (2016) https://doi.org/10.1117/12.2232091

KEYWORDS: Atmospheric Cherenkov telescopes, Mirrors, Telescopes, Manufacturing, Optical design, Atmospheric Cherenkov telescopes, Mirrors, Prototyping, Telescopes, Point spread functions, Reflectivity, Glasses, Polishing

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The Cherenkov Telescope Array (CTA) project, led by an international collaboration of institutes, aims to create the world's largest next generation Very High-Energy (VHE) gamma-ray telescope array, devoted to observations in a wide band of energy, from a few tens of GeV to more than 100 TeV. The Small-Sized Telescopes (SSTs) are dedicated to the highest energy range. Seventy SSTs are planned in the baseline array design with a required lifetime of about 30 years.

The GCT (Gamma-ray Cherenkov Telescope) is one of the prototypes proposed for CTA's SST sub-array. It is based on a Schwarzschild-Couder dual-mirror optical design. This configuration has the benefit of increasing the field-of-view and decreasing the masses of the telescope and of the camera. But, in spite of these many advantages, it was never implemented before in ground-based Cherenkov astronomy because of the aspherical and highly curved shape required for the mirrors.

The optical design of the GCT consists of a primary 4 meter diameter mirror, segmented in six aspherical petals, a secondary monolithic 2-meter mirror and a light camera. The reduced number of segments simplifies the alignment of the telescope but complicates the shape of the petals. This, combined with the strong curvature of the secondary mirror, strongly constrains the manufacturing process. The Observatoire de Paris implemented metallic lightweight mirrors for the primary and the secondary mirrors of GCT. This choice was made possible because of the relaxed requirements of optical Cherenkov telescopes compared to optical ones. Measurements on produced mirrors show that these ones can fulfill requirements in shape, PSF and reflectivity, with a clear competition between manufacturing cost and final performance.

This paper describes the design of these mirrors in the context of their characteristics and how design optimization was used to produce a lightweight design. The manufacturing process used for the prototype and planned for the large scale production is presented as well as the performance, in terms of geometric and optical properties, of the produced mirrors. The alignment procedure of the mirrors is also detailed. This technique is finally compared to other manufacturing techniques based on composite glass mirrors within the framework of GCT mirrors specificities.

Proceedings Article | 22 July 2016 Paper

Performance of the Gamma-ray Cherenkov Telescope structure: a dual-mirror telescope prototype proposed for the future Cherenkov Telescope Array

J. L. Dournaux, J. P. Amans, L. Dangeon, G. Fasola, J. Gironnet, J. M. Huet, P. Laporte, A. Abchiche, S. Barkaoui, J. J. Bousquet, G. Buchholtz, D. Dumas, J. Gaudemard, I. Jégouzo, P. Poinsignon, L. Vergne, H. Sol

Proceedings Volume 9912, 99124Z (2016) https://doi.org/10.1117/12.2232099

KEYWORDS: Telescopes, Gamma radiation, Atmospheric Cherenkov telescopes, Telescopes, Prototyping, Gamma radiation, Mirrors, Atmospheric Cherenkov telescopes, Optical instrument design, Cameras, Manufacturing, Interfaces, Imaging systems

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The Cherenkov Telescope Array (CTA) project aims to create the next generation Very High-Energy (VHE) gamma-ray telescope array. It will be devoted to the observation of gamma rays from 20 GeV to above 100 TeV. Because of this wide energy band, three classes of telescopes, associated with different energy ranges and different mirror sizes, are defined. The Small Size Telescopes (SSTs) are associated with the highest energy range. Seventy of these telescopes are foreseen on the Southern site of the CTA. The large number of telescopes constrains their mechanical structure because easy maintenance and reduced cost per telescope are needed. Moreover, of course, the design shall fulfill the required performance and lifetime in the environment conditions of the site.

The Observatoire de Paris started design studies in 2011 of the mechanical structure of the GCT (Gamma-ray Cherenkov Telescope), a four-meter prototype telescope for the SSTs of CTA, from optical and preliminary mechanical designs made by the University of Durham. At the end of 2014 these studies finally resulted in a lightweight (~8 tons) and stiff design. This structure was based on the dual-mirror Schwarzschild-Couder (SC) optical design, which is an interesting and innovative alternative to the one-mirror Davies-Cotton design commonly used in ground-based Cherenkov astronomy. The benefits of such a design are many since it enables a compact structure, lightweight camera and a good angular resolution across the entire field-of-view. The mechanical structure was assembled on the Meudon site of the Observatoire de Paris in spring 2015. The secondary mirror, panels of the primary mirror and the Telescope Control System were successfully implemented afterwards leading now to a fully operational telescope.

This paper focuses on the mechanics of the telescope prototype. It describes the mechanical structure and presents its performance identified from computations or direct measurements. Upgrades of the design in the context of the preproduction and the large scale CTA production are also discussed.

Proceedings Article | 7 August 2014 Paper

Mechanical design of SST-GATE, a dual-mirror telescope for the Cherenkov Telescope Array

Jean-Laurent Dournaux, Jean-Michel Huet, Jean-Philippe Amans, Delphine Dumas, Philippe Laporte, Hélène Sol, Simon Blake

Proceedings Volume 9151, 915102 (2014) https://doi.org/10.1117/12.2054911

KEYWORDS: Telescopes, Atmospheric Cherenkov telescopes, Mirrors, Mechanical engineering, Computer aided design, Cameras, Optical instrument design, Interfaces, 3D modeling, Prototyping

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Proceedings Article | 4 August 2014 Paper

SST-GATE telescope: an innovative dual-mirror prototype for the Cherenkov Telescope Array

Delphine Dumas, Jean-Michel Huet, Jean-Laurent Dournaux, Philippe Laporte, Jean-Philippe Amans, Gilles Fasola, Andreas Zech, Cameron Rulten, Hélène Sol, Simon Blake, Jurgen Schmoll

Proceedings Volume 9145, 91452Y (2014) https://doi.org/10.1117/12.2055083

KEYWORDS: Telescopes, Atmospheric Cherenkov telescopes, Mirrors, Cameras, Optical instrument design, Prototyping, Manufacturing, Interfaces, Finite element methods, Optics manufacturing

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Proceedings Article | 22 July 2014 Paper

Seismic analysis of the 4-meter telescope SST-GATE for the Cherenkov Telescope Array

Jean-Laurent Dournaux, Jean-Michel Huet, Jean-Philippe Amans, Delphine Dumas, Simon Blake, Hélène Sol

Proceedings Volume 9145, 914558 (2014) https://doi.org/10.1117/12.2054903

KEYWORDS: Telescopes, Atmospheric Cherenkov telescopes, Earthquakes, Optical instrument design, 3D modeling, Prototyping, Mirrors, Safety, Cameras, Systems modeling

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Proceedings Article | 22 July 2014 Paper

Challenges of the opto-mechanical conceptual design of a small far-IR balloon experiment

Jean-Laurent Dournaux, Christophe Berthod, David Horville, Jean-Michel Huet, Philippe Laporte, Martina Wiedner, Alexia Romanow, Jean-Michel Krieg, Laurent Pagani, Jean Evrard, Albert Gomes, Martine Jouret

Proceedings Volume 9145, 91452T (2014) https://doi.org/10.1117/12.2054986

KEYWORDS: Mirrors, Sensors, Mechanical engineering, Tolerancing, Composites, Optical design, Skin, Aluminum, Thermography, Optical components

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Proceedings Article | 18 July 2014 Paper

SST dual-mirror telescope for Cherenkov Telescope Array: an innovative mirror manufacturing process

Delphine Dumas, Jean-Michel Huet, Jean-Laurent Dournaux, Philippe Laporte, Cameron Rulten, Jurgen Schmoll, Hélène Sol, Frédéric Sayède, Patrice Micolon, Jean-François Glicenstein, Bernard Peyaud

Proceedings Volume 9151, 91512U (2014) https://doi.org/10.1117/12.2055077

KEYWORDS: Mirrors, Telescopes, Atmospheric Cherenkov telescopes, Polishing, Cameras, Optical instrument design, Prototyping, Point spread functions, Optical design, Optics manufacturing

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Proceedings Article | 17 September 2012 Paper

SST-GATE: an innovative telescope for very high energy astronomy

Philippe Laporte, Jean-Laurent Dournaux, Hélène Sol, Simon Blake, Catherine Boisson, Paula Chadwick, Delphine Dumas, Gilles Fasola, Fatima de Frondat, Tim Greenshaw, Olivier Hervet, James Hinton, David Horville, Jean-Michel Huet, Isabelle Jégouzo, Jürgen Schmoll, Richard White, Andreas Zech

Proceedings Volume 8444, 84443A (2012) https://doi.org/10.1117/12.966860

KEYWORDS: Telescopes, Atmospheric Cherenkov telescopes, Mirrors, Cameras, Prototyping, Point spread functions, Gamma radiation, Optical instrument design, Error analysis, Optical alignment

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Proceedings Article | 29 July 2010 Paper

Demonstration prototype and breadboards of the piezo stack M4 adaptive unit of the E-ELT

B. Crépy, S. Chaillot, M. Cola, J. Conan, R. Cousty, M. Dimmler, J. Dournaux, S. De Zotti, E. Gabriel, R. Gasmi, R. Grasser, N. Hubin, P. Jagourel, L. Jochum, F. Locre, P.-Y. Madec, P. Morin, M. Mueller, G. Petit, D. Petitgas, J. Roland, J. Sinquin, E. Vernet

Proceedings Volume 7736, 77365P (2010) https://doi.org/10.1117/12.856362

KEYWORDS: Actuators, Mirrors, Prototyping, Manufacturing, Ferroelectric materials, Silicon carbide, Optics manufacturing, Polishing, Finite element methods, Capacitance

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Proceedings Article | 28 July 2010 Paper

Last progress concerning the design of the piezo-stack M4 adaptive unit of the E-ELT

B. Crepy, S. Chaillot, J. Conan, R. Cousty, C. Delrez, M. Dimmler, J. Dournaux, S. De Zotti, E. Gabriel, R. Gasmi, R. Grasser, N. Hubin, P. Jagourel, L. Jochum, F. Locre, P.-Y. Madec, P. Morin, M. Mueller, G. Petit, D. Petitgas, M. Pierard, J. Roland, J. Sinquin, E, Vernet

Proceedings Volume 7736, 77362F (2010) https://doi.org/10.1117/12.856359

KEYWORDS: Actuators, Mirrors, Telescopes, Control systems, Ferroelectric materials, Computer programming, Interfaces, Photovoltaics, Optical instrument design, Adaptive optics

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Proceedings Article | 28 July 2010 Paper

Active control of a large deformable mirror for future E-ELT

R. Gasmi, D. Le Bihan, J. Dournaux, J. Sinquin, P. Jagourel

Proceedings Volume 7736, 77361B (2010) https://doi.org/10.1117/12.856236

KEYWORDS: Deformable mirrors, Prototyping, Adaptive optics, Actuators, Monochromatic aberrations, Finite element methods, Mirrors, Modal analysis, Atmospheric turbulence, Control systems

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Proceedings Article | 20 July 2010 Paper

Overview of the GYES instrument: a multifibre high-resolution spectrograph for the prime focus of the Canada-France-Hawaii Telescope

Shan Mignot, Mathieu Cohen, Gavin Dalton, Jean-Laurent Dournaux, Gilles Fasola, Isabelle Guinouard, David Horville, Jean-Michel Huet, Philippe Laporte, Ian Lewis, Frédéric Royer

Proceedings Volume 7735, 77354H (2010) https://doi.org/10.1117/12.857094

KEYWORDS: Spectrographs, Telescopes, Sensors, Signal to noise ratio, Stars, Spectral resolution, Cameras, Calibration, Photography, Optical design

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Proceedings Article | 9 July 2008 Paper

Modeling of a large deformable mirror for future E-ELT

R. Gasmi, J. C. Sinquin, P. Jagourel, J. L. Dournaux, D. Le Bihan, F. Hammer

Proceedings Volume 7017, 70171Z (2008) https://doi.org/10.1117/12.802346

KEYWORDS: Actuators, Mirrors, Prototyping, Chemical elements, Deformable mirrors, Telescopes, Modal analysis, Adaptive optics, Optical components, Atmospheric optics

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