Download or read book Optique active spatiale pour l observation haute r solution written by Clément Escolle and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pour relever les défis de l'observation de la Terre et de l'astronomie, les futurs observatoires spatiaux vont requérir des télescopes de plusieurs mètres de diamètre. Les différentes contraintes liées à l'environnement spatial vont induire des déformations et des désalignements des miroirs du télescope dégradant ainsi la qualité optique des observations. L'intégration de l'optique active, utilisée depuis la fin des années 80 pour l'alignement et le maintien de la qualité optique des télescopes au sol, devient donc nécessaire. Un tel système est constitué de trois éléments : un dispositif de mesure, une fonction de correction et une boucle de contrôle qui fait le lien entre les deux éléments précédents.Les travaux de recherche présentés dans ce mémoire de doctorat s'attachent, d'une part, au développement d'un estimateur des perturbations minimisant le front d'onde résiduel dans le champ du télescope. L'analyse de cet estimateur et plus généralement des performances ultimes d'un système d'optique active spatial nous a permis de mettre en évidence l'impact des hautes fréquences spatiales sur la qualité optique. La présence de telles hautes fréquences dues à l'empreinte des supports du miroir primaire nous a poussés, d'autre part, à évaluer les possibilités de leur réduction dans le cas d'un miroir de grande dimension. A l'aide d'une modélisation éléments finis d'un tel miroir nous avons réalisé des modifications locales de la structure du miroir pour adapter ses déformations aux capacités de correction de l'optique active.
Download or read book Les instruments optiques d observation de la Terre written by Georges Otrio and published by ISTE Group. This book was released on 2015-03-01 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les instruments optiques perfectionnés qui se trouvent à bord des satellites et des véhicules spatiaux permettent d’accéder à une connaissance chaque jour plus fine des complexités physiques de l’univers et de notre planète. Cet ouvrage expose en détail les bases de l’optique spatiale et étudie les diverses étapes du développement instrumental, notamment celles de faisabilité et de pré-dimensionnement en prenant compte les contraintes liées à l’environnement spatial. Par son approche pédagogique, il propose une initiation à la conception et à la réalisation d’instruments spatiaux, puis présente un large choix de missions et d’instruments optiques sélectionnés en fonction de leur originalité et de leur usage dans des systèmes opérationnels. Les mesures de performances avant lancement, pendant les opérations en orbite et à l'issue de l'exploitation des données après réception au sol sont développées par les concepteurs eux-mêmes, responsables de programmes spatiaux internationaux de grande renommée.
Download or read book Synth se d ouverture optique pour l observation haute r solution du soleil written by Sophie Cladé and published by . This book was released on 2005 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pour permettre des images haute résolution sur le Soleil, le projet SOLARNET prévoit un système interféromètrique à trois télescopes. Ainsi tout en limitant poids et encombrement, la résolution spatiale de l'instrument est améliorée si un alignement et un cophasage précis des trois télescopes est maintenu. Un système de filtrage spectral de type double monochromateur est également prévu pour permettre une haute résolution spectrale. Pour valider les principes de l'instrument ainsi que de ses systèmes de correction de front d'onde, un banc optique de démonstration à échelle réduite été monté à l'observatoire de Meudon. Après avoir rappelé les caractéristiques de l'instrument SOLARNET ainsi que la raison de ces choix techniques, je décris dans ce document le banc optique de démonstration ainsi que ses réglages d'alignement. Je détaille alors plus particulièrement le système de correction de pointage de chaque télescope et en étudie les performances à partir de simulations et de tests directs sur le Soleil. Cette étude met en évidence la limitation du niveau de correction du pointage du à une limitation de la rapidité des miroirs. Le système de cophasage est basé sur une mesure interféromètrique en lumière blanche. Des simulations m'ont permis de mieux cerner le fonctionnement du système et de mettre en exergue un risque de biais sur la mesure. Si les tests expérimentaux confirment l'existence de ce biais, il faudra alors envisager un système de correction de phase supplémentaire. Les caractéristiques simulées de ce défaut en fonction des paramètres de la source et de l'instrument forment une première base sur laquelle s'appuyer pour la définition de ce nouveau système.
Download or read book POSSIBILITES NOUVELLES ET CONTRAINTES ASSOCIEES APPORTEES PAR L OPTIQUE ACTIVE ET ADAPTATIVE DANS LA CONCEPTION DE TELESCOPES written by JEAN BERNARD.. GHIBAUDO and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE THESE EST RELATIVE A L'OPTIQUE ACTIVE ET ADAPTATIVE, NOUVELLE TECHNIQUE POUVANT REVOLUTIONNER LA CONCEPTION DE CERTAINS INSTRUMENTS D'OPTIQUE DANS UN FUTUR PROCHE. DANS UN PREMIER TEMPS, CETTE THESE S'ATTACHE A DEFINIR LES PRINCIPES DE CES TECHNIQUES TEMPS REEL DE CORRECTION DES SURFACES D'ONDE ABERRANTES, AFIN D'OBTENIR DANS LE PLAN FOCAL D'UN INSTRUMENT UNE IMAGE LIMITEE PAR LA DIFFRACTION. DANS UN DEUXIEME TEMPS, L'ETUDE A PORTE SUR LA MODELISATION DE SURFACES D'ONDE TURBULENTES ET LA DECOMPOSITION DE CES DERNIERES SUR LES MODES OPTIQUES DE ZERNIKE, PROCHES DES MODES PROPRES DE LA TURBULENCE. L'ECRITURE MODALE DES SURFACES D'ONDE PERTURBEES PRESENTE DE MULTIPLES AVANTAGES NOTAMMENT DANS LE CADRE DU CONTROLE DES MIROIRS DE CORRECTION. L'UN DES POINTS DELICATS DE L'OPTIQUE ACTIVE ET ADAPTATIVE EST LA DETERMINATION DES LOIS DE COMMANDE EN REGIME STATIQUE ET DYNAMIQUE AFIN DE METTRE EN FORME LES MIROIRS DE COMPENSATION. CETTE ETUDE GLOBALE VALIDE L'OPTIQUE ACTIVE ET L'OPTIQUE ADAPTATIVE COMME MOYENS DE COMPENSATION AUTOMATIQUE DES ABERRATIONS. CES TECHNIQUES S'AVERERONT INDISPENSABLES POUT TOUT INSTRUMENT OPTIQUE BASE AU SOL, OU LA HAUTE RESOLUTION SPATIALE EST AVANT TOUT RECHERCHEE
Download or read book Mod lisation des effets de l chelle externe de coh rence spatiale du front d onde pour l observation haute r solution angulaire en astronomie written by Rodolphe Conan and published by . This book was released on 2000 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les performances des instruments dédiés à la Haute Résolution Angulaire (HRA) sont sévèrement limitées par les effets de la turbulence atmosphérique. Une analyse spatio-temporelle de la phase de l'onde incidente est indispensable à l'optimisation des techniques telles que l'optique adaptative et l'interférométrie à longues bases. Parmi les paramètres les mieux connus permettant de quantifier la dégradation des surfaces d'onde par la turbulence atmosphérique, nous connaissons le paramètre de Fried et l'angle d'isoplanétisme. Avec l'avènement des nouveaux interféromètres et des grands téléscopes, la connaissance d'un nouveau paramètre, l'échelle externe, est maintenant devenu indispensable à la caractérisation d'un site astronomique. L'influence de la valeur finie de l'échelle externe sur les techniques de la HRA est le thème central de la thèse qui présente les outils mathématiques et les solutions à plusieurs intégrales utiles aux modélisations des effets de l'échelle externe en HRA, puis examine les traitements théoriques des effets de l'échelle externe en HRA et donne les résultats des différentes campagnes de mesures effectuées avec le Generalized Seeing Monitor (GSM). (...) À travers ce travail, il apparaît que l'échelle externe est un paramètre dont la connaissance est indispensable à l'optimisation des futurs instruments en HRA (...)
Download or read book Backscatter written by and published by . This book was released on 2004 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ESA Bulletin written by European Space Agency and published by . This book was released on 1995 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Observational Astrophysics written by Pierre Lena and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the last twenty years astronomy has been developing dramatically. Until the nineteen-fifties, telescopes, spectrometers, and photographic plates consti tuted a relatively simple set of tools which had been refined to a high degree of perfection by the joint efforts of physicists and astronomers. Indeed these tools helped at the birth of modern astrophysics: the discovery of the expan sion of the Universe. Then came radioastronomy and the advent of electronics; the last thirty years have seen the application to astrophysics of a wealth of new experimental techniques, based on the most advanced fields of physics, and a constant interchange of ideas between physicists and astronomers. Last, but not least, modern computers have sharply reduced the burden of dealing with the information painfully extracted from the skies, whether from ever scarce photons, or from the gigantic data flows provided by satellites and large telescopes. The aim of this book is not to give an extensive overview of all the tech niques currently in use in astronomy, nor to provide detailed instructions for preparing or carrying out an astronomical project. Its purpose is methodologi cal: photons are still the main carriers of information between celestial sources and the observer. How we are to collect, sample, measure, and store this infor mation is the unifying theme of the book. Rather than the diversity of tech niques appropriate for each wavelength range, we emphasize the physical and mathematical bases which are common to all wavelength regimes.
Download or read book MILCOM 2005 written by Institute of Electrical and Electronics Engineers and published by . This book was released on 2005 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Optical Unconscious written by Rosalind E. Krauss and published by MIT Press. This book was released on 1994-07-25 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Optical Unconscious is a pointed protest against the official story of modernism and against the critical tradition that attempted to define modern art according to certain sacred commandments and self-fulfilling truths. The account of modernism presented here challenges the vaunted principle of "vision itself." And it is a very different story than we have ever read, not only because its insurgent plot and characters rise from below the calm surface of the known and law-like field of modernist painting, but because the voice is unlike anything we have heard before. Just as the artists of the optical unconscious assaulted the idea of autonomy and visual mastery, Rosalind Krauss abandons the historian's voice of objective detachment and forges a new style of writing in this book: art history that insinuates diary and art theory, and that has the gait and tone of fiction. The Optical Unconscious will be deeply vexing to modernism's standard-bearers, and to readers who have accepted the foundational principles on which their aesthetic is based. Krauss also gives us the story that Alfred Barr, Meyer Shapiro, and Clement Greenberg repressed, the story of a small, disparate group of artists who defied modernism's most cherished self-descriptions, giving rise to an unruly, disruptive force that persistently haunted the field of modernism from the 1920s to the 1950s and continues to disrupt it today. In order to understand why modernism had to repress the optical unconscious, Krauss eavesdrops on Roger Fry in the salons of Bloomsbury, and spies on the toddler John Ruskin as he amuses himself with the patterns of a rug; we find her in the living room of Clement Greenberg as he complains about "smart Jewish girls with their typewriters" in the 1960s, and in colloquy with Michael Fried about Frank Stella's love of baseball. Along the way, there are also narrative encounters with Freud, Jacques Lacan, Georges Bataille, Roger Caillois, Gilles Deleuze, and Jean-François Lyotard. To embody this optical unconscious, Krauss turns to the pages of Max Ernst's collage novels, to Marcel Duchamp's hypnotic Rotoreliefs, to Eva Hesse's luminous sculptures, and to Cy Twombly's, Andy Warhol's, and Robert Morris's scandalous decoding of Jackson Pollock's drip pictures as "Anti-Form." These artists introduced a new set of values into the field of twentieth-century art, offering ready-made images of obsessional fantasy in place of modernism's intentionality and unexamined compulsions.
Download or read book New Strategies in Locust Control written by S. Krall and published by Birkhäuser. This book was released on 2012-12-06 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the late eighties large-scale control operations were carried out to control a major desert locust upsurge in Africa. For the first time since the banning of organochlorine pesticides these operations relied mainly on non-persistent pesticides such as organophosphates and pyrethroids. The amount of pesticides sprayed and the area covered were probably the highest in the history of locust control and raised criticism with respect to efficacy, economic viability and environmental impact. As a consequence, applied research into the problem was intensified, both at the national and the international level, with the goal of finding new and environmentally sound approaches and solutions to locust and grasshopper control. Emphasis was laid on developing new control agents and techniques.
Download or read book Space Systems as Contributors to the NATO Defence Mission written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Mission Systems Panel. Symposium and published by . This book was released on 1997 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermodynamics of Minerals and Melts written by R.C. Newton and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today large numbers of geoscientists apply thermodynamic theory to solu tions of a variety of problems in earth and planetary sciences. For most problems in chemistry, the application of thermodynamics is direct and rewarding. Geoscientists, however, deal with complex inorganic and organic substances. The complexities in the nature of mineralogical substances arise due to their involved crystal structure and multicomponental character. As a result, thermochemical solutions of many geological-planetological problems should be attempted only with a clear understanding of the crystal-chemical and thermochemical character of each mineral. The subject of physical geochemistry deals with the elucidation and application of physico-chemical principles to geosciences. Thermodynamics of mineral phases and crystalline solutions form an integral part of it. Developments in mineralogic thermody namics in recent years have been very encouraging, but do not easily reach many geoscientists interested mainly in applications. This series is to provide geoscientists and planetary scientists with current information on the develop ments in thermodynamics of mineral systems, and also provide the active researcher in this rapidly developing field with a forum through which he can popularize the important conclusions of his work. In the first several volumes, we plan to publish original contributions (with an abundant supply of back ground material for the uninitiated reader) and thoughtful reviews from a number of researchers on mineralogic thermodynamics, on the application of thermochemistry to planetary phase equilibria (including meteorites), and on kinetics of geochemical reactions.
Download or read book New Trends in Fluorescence Spectroscopy written by Bernard Valeur and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first volume in the new Springer Series on Fluorescence brings together fundamental and applied research from this highly interdisciplinary and field, ranging from chemistry and physics to biology and medicine. Special attention is given to supramolecular systems, sensor applications, confocal microscopy and protein-protein interactions. This carefully edited collection of articles is an invaluable tool for practitioners and novices.
Download or read book Optical Coherence Tomography written by Mark E. Brezinski and published by Elsevier. This book was released on 2006-08-25 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography gives a broad treatment of the subject which will include 1)the optics, science, and physics needed to understand the technology 2) a description of applications with a critical look at how the technology will successfully address actual clinical need, and 3) a discussion of delivery of OCT to the patient, FDA approval and comparisons with available competing technologies. The required mathematical rigor will be present where needed but be presented in such a way that it will not prevent non-scientists and non-engineers from gaining a basic understanding of OCT and the applications as well as the issues of bringing the technology to the market. - Optical Coherence Tomography is a new medical high-resolution imaging technology which offers distinct advantages over current medical imaging technologies and is attracting a large number of researchers. - Provides non-scientists and non-engineers basic understanding of Optical Coherence Tomography applications and issues.
Download or read book Fruit flies of economic importance 84 written by C.V. Cavalloro and published by CRC Press. This book was released on 1986-06-01 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of a meeting organised by the Commission of the European Communities and the International Organisation for Biological ad Integrated Control. It includes full communications by experts from 17 different countries and 3 international organisations. The work of the IOBC/WPRS Working Group 'Fruit flies of economic importance is also reported.
