AMELIORATION DES PERFORMANCES DES CHAINES LASERS SOLIDES UTILISANT L'AMPLIFICATION A DERIVE DE FREQUENCE PDF Download

Author: Benoit Wattellier
Publisher:
ISBN:
Category :
Languages : fr
Pages : 220

View

Book Description
CE MEMOIRE DE THESE PORTE SUR L'AMELIORATION DES PERFORMANCES DES LASERS DE PUISSANCE. CETTE OPTIMISATION A D'ABORD PORTE SUR L'AMELIORATION DU COMPOSANT LE PLUS SENSIBLE D'UNE INSTALLATION LASER UTILISANT L'AMPLIFICATION A DERIVE DE FREQUENCE (CHAINE 100TW AU LULI), A SAVOIR LE RESEAU DU COMPRESSEUR SOUMIS A L'ECLAIREMENT LE PLUS ELEVE. DANS UNE SECONDE PERIODE, DES TECHNIQUES DE CORRECTION DE FRONT D'ONDE ONT ETE EXPERIMENTEE D'UNE PART POUR AMELIORER LA FOCALISATION DES FAISCEAUX, D'AUTRE PART POUR CONTROLER LA REPARTITION SPATIALE DE L'ENERGIE DANS LE VOLUME FOCAL. DEUX NOUVELLES TECHNIQUES POUR LA PRODUCTION DE RESEAUX DE DIFFRACTION ONT ETE TESTEES EXPERIMENTALEMENT, L'ACCENT ETANT PORTE SUR LA TENUE AU FLUX LASER ET L'EFFICACITE DE DIFFRACTION. IL S'AGIT DE MIROIRS DIELECTRIQUES DONT LA COUCHE SUPERIEURE EST GRAVEE OU DES RESEAUX HOLOGRAPHIQUES EN VOLUME. L'ETUDE DE LA TENUE AU FLUX LASER A ETE EFFECTUEE PAR DEUX METHODES DIRECTE ET STATISTIQUE. L'EFFICACITE DE DIFFRACTION MAXIMALE ATTEINTE EST DE 98 % (96 % SUR TOUTE LA SURFACE DU RESEAU) ET LA TENUE AU FLUX EST DEUX FOIS SUPERIEURE A CELLE DES COMPOSANTS CLASSIQUES, RECOUVERTS D'OR. LA DEUXIEME PARTIE DE CE MEMOIRE CONCERNE LA MISE EN FORME SPATIALE DES FAISCEAUX LASERS AU FOYER DES SYSTEMES DE FOCALISATION. CECI CONCERNE AUSSI BIEN LA CORRECTION DE FRONT D'ONDE DONT LE BUT EST DE CONCENTRER AU MAXIMUM L'ENERGIE LASER QUE LA MISE EN FORME PROGRAMMABLE DE TACHES FOCALES PAR MODULATION DE LA PHASE SPATIALE EN CHAMP PROCHE. DEUX SYSTEMES DE CORRECTION (UN MIROIR DEFORMABLE ET UNE VALVE ELECTRO-OPTIQUE A CRISTAUX LIQUIDES) SONT ETUDIES ET COMPARES A PARTIR DE LEUR INSTALLATION SUR LES DEUX CHAINES DE PUISSANCE DU LULI. UNE AMELIORATION D'UN FACTEUR 5 SUR L'INTENSITE CRETE SUR CIBLE A PU ETRE DEMONTREE. ENFIN, L'UTILISATION DE LA VALVE ELECTRO OPTIQUE COMME LAME DE PHASE PROGRAMMABLE DE HAUTE RESOLUTION A PERMIS DE METTRE EN FORME DES TACHES FOCALES ET D'OBTENIR DES LIGNES FOCALES OU DES ANNEAUX.

Author: Michel Neviere
Publisher: CRC Press
ISBN: 1351830619
Category : Science
Languages : en
Pages : 261

View

Book Description
Based on more than 30 years of research on differential theories of gratings, this book describes developments in differential theory for applications in spectroscopy, acoustics, X-ray instrumentation, optical communication, information processing, photolithography, high-power lasers, high-precision engineering, and astronomy. Introducing the Fast Fourier Factorization approach to improve the convergence of a truncated series, the book examines multilayers, stacked gratings, crossed gratings, photonic crystals, and isotropic and anisotropic materials; techniques and examples in grating design; and Maxwell equations in a truncated Fourier space.

Author: Carolyn D. Berdanier
Publisher: CRC Press
ISBN: 1482275201
Category : Medical
Languages : en
Pages : 433

View

Book Description
The explosion of knowledge about satiety and hunger has given new meaning to our understanding of the genetics of obesity. New interest in gene expression as related to nutrition and advances in the field of macronutrients has made the latest nutrition research intriguing. Advanced Nutrition: Macronutrients adopts an integrated approach to the understanding of macronutrient nutrition. It provides scientific foundations of the current findings on energy balance, protein need, gene expression, and carbohydrate and lipid use, and maintains emphasis on the biochemical and physiological basis for nutrient need.

Author: Vincent Bagnoud
Publisher:
ISBN:
Category :
Languages : fr
Pages : 231

View

Book Description
L'AMPLIFICATION A DERIVE DE FREQUENCE (CPA) PERMET D'AMPLIFIER DES IMPULSIONS LASERS JUSQU'A DES PUISSANCES CRETES TRES ELEVEES, OUVRANT DE NOUVEAUX CHAMPS D'INVESTIGATION EN PHYSIQUE. CETTE TECHNIQUE EST PARTICULIEREMENT ADAPTEE AUX CHAINES LASERS A SOLIDES UTILISANT DU SAPHIR DOPE AUX IONS TITANE. SI L'AUGMENTATION DES PERFORMANCES DE CES LASERS A TOUT D'ABORD ETE RAPIDE, ON SE HEURTE MAINTENANT A DES PROBLEMES QUI IMPOSENT UN CONTROLE PRECIS DE L'AMPLITUDE ET DE LA PHASE SPECTRALE DES IMPULSIONS AU COURS DE L'AMPLIFICATION. NOUS DECRIVONS LA PREMIERE REALISATION D'UN LASER DELIVRANT DES IMPULSIONS DONT LA PUISSANCE CRETE APPROCHE LE TERAWATT A LA FREQUENCE DE REPETITION DE 1 KILOHERTZ. POUR CELA, NOUS AVONS MIS EN UVRE DES TECHNIQUES ORIGINALES DE SIMULATION DE L'ETIREMENT ET DE COMPRESSION DES IMPULSIONS AFIN DE VALIDER LE CONCEPT DE RESEAUX MIXTES DANS UNE CHAINE LASER COMPRENANT BEAUCOUP DE MATERIAUX. DE PLUS, LE SPECTRE DES IMPULSIONS EST CONTROLE PENDANT L'AMPLIFICATION PAR L'UTILISATION D'UN FILTRE BIREFRINGENT (TYPE FILTRE DE LYOT). NOUS DEMONTRONS QUE CES TECHNIQUES OFFRENT UN CONTROLE SPECTRAL SUFFISANT POUR ETIRER, AMPLIFIER ET COMPRIMER DES IMPULSIONS DONT LA DUREE EST INFERIEURE A 20 FEMTOSECONDES. L'AMPLIFICATION PROPREMENT DITE EST REALISEE PAR QUATRE ETAGES D'AMPLIFICATION SUCCESSIFS OU LE PREMIER AMPLIFICATEUR EST UN AMPLIFICATEUR REGENERATIF ET LES TROIS DERNIERS SONT DES AMPLIFICATEURS MULTI-PASSAGES. DU FAIT DU FORT TAUX DE REPETITION DE LA CHAINE LASER, LE MILIEU AMPLIFICATEUR EST SOUMIS A UNE FORTE CHARGE THERMIQUE. LA LENTILLE THERMIQUE AINSI CREEE DANS LES CRISTAUX LASERS EST MISE A PROFIT POUR IMAGER LE FAISCEAU LASER ENTRE CHAQUE PASSAGE. NOUS AVONS AMPLIFIE AVEC SUCCES LE FAISCEAU LASER JUSQU'A UNE ENERGIE DE 28 MJ, UN NIVEAU JAMAIS EGALE JUSQU'A PRESENT A CE TAUX DE RECURRENCE. APRES COMPRESSION, DES IMPULSIONS LASERS AUSSI BREVES QUE 18,5 FS ONT ETE MESUREES, ET LEUR ENERGIE APPROCHE LES 20 MJ.

Author: Laure Lago
Publisher:
ISBN:
Category :
Languages : en
Pages : 192

View

Book Description
This work concerns the development of a double-clad ytterbium-doped single-mode microstructured flexible fiber-based amplifier, in the nanosecond, multi-kiloHertz and milliJoule regime, for large-scale laser facilities seeding. We have used a multi-stage master oscillator power amplifier fibered architecture. A numerical model of ytterbium-doped double-clad fiber-based amplification, including amplified spontaneous emission, was developed in order to study the behaviour of such amplifier and to correctly design the experimental set-up. This model was completed by a feed-back algorithm to numerically predict the optimal temporal shape to compensate the gain saturation process. We demonstrated experimental results in good agreement with numerical simulations, with the following performances: 0.5 mJ pulse energy, at a frequency repetition from 1 kHz to 10 kHz, with a narrow bandwidth spectrum centred at 1053 nm wavelength, with 10 ns pulse duration on a perfect super-Gaussian temporal profile, an optical signal-to-noise ratio better than 50 dB and a polarization extinction ratio of 20 dB. We checked that the beam quality was diffraction limited, with an M2 measurement of 1.1. Moreover, the system can deliver energies up to 1.5 mJ. Then, we took the advantage of such results to amplify chirped pulses. We demonstrated 0.7 mJ pulse energy, with 570 fs duration at 10 kHz repetition frequency.

Author: Claude Cohen-Tannoudji
Publisher: John Wiley & Sons
ISBN: 3527345558
Category : Science
Languages : en
Pages : 790

View

Book Description
This new, third volume of Cohen-Tannoudji's groundbreaking textbook covers advanced topics of quantum mechanics such as uncorrelated and correlated identical particles, the quantum theory of the electromagnetic field, absorption, emission and scattering of photons by atoms, and quantum entanglement. Written in a didactically unrivalled manner, the textbook explains the fundamental concepts in seven chapters which are elaborated in accompanying complements that provide more detailed discussions, examples and applications. * Completing the success story: the third and final volume of the quantum mechanics textbook written by 1997 Nobel laureate Claude Cohen-Tannoudji and his colleagues Bernard Diu and Franck Laloë * As easily comprehensible as possible: all steps of the physical background and its mathematical representation are spelled out explicitly * Comprehensive: in addition to the fundamentals themselves, the books comes with a wealth of elaborately explained examples and applications Claude Cohen-Tannoudji was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris where he also studied and received his PhD in 1962. In 1973 he became Professor of atomic and molecular physics at the Collège des France. His main research interests were optical pumping, quantum optics and atom-photon interactions. In 1997, Claude Cohen-Tannoudji, together with Steven Chu and William D. Phillips, was awarded the Nobel Prize in Physics for his research on laser cooling and trapping of neutral atoms. Bernard Diu was Professor at the Denis Diderot University (Paris VII). He was engaged in research at the Laboratory of Theoretical Physics and High Energy where his focus was on strong interactions physics and statistical mechanics. Franck Laloë was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris. His first assignment was with the University of Paris VI before he was appointed to the CNRS, the French National Research Center. His research was focused on optical pumping, statistical mechanics of quantum gases, musical acoustics and the foundations of quantum mechanics.

Author: Agnes Buka
Publisher: World Scientific
ISBN: 1848167997
Category : Science
Languages : en
Pages : 299

View

Book Description
The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Author: Mark S. Meskin
Publisher: CRC Press
ISBN: 1420031694
Category : Medical
Languages : en
Pages : 221

View

Book Description
Are soy isoflavones neuroprotective? Just how different is one species of Echinacea from another? Which phytochemicals will be effective as therapeutic agents in vivo? Supported by solid scientific research, Phytochemicals in Nutrition and Health helps provide answers to these and other probing questions concerning the mechanisms of action associat

Author: Alain Hébert
Publisher: Presses inter Polytechnique
ISBN: 2553014368
Category : Nuclear physics
Languages : en
Pages : 426

View

Book Description

Author: Rob Flickenger
Publisher: "O'Reilly Media, Inc."
ISBN: 9780596005023
Category : Computers
Languages : en
Pages : 190

View

Book Description
Building Wireless Community Networks is about getting people online using wireless network technology. The 802.11b standard (also known as WiFi) makes it possible to network towns, schools, neighborhoods, small business, and almost any kind of organization. All that's required is a willingness to cooperate and share resources. The first edition of this book helped thousands of people engage in community networking activities. At the time, it was impossible to predict how quickly and thoroughly WiFi would penetrate the marketplace. Today, with WiFi-enabled computers almost as common as Ethernet, it makes even more sense to take the next step and network your community using nothing but freely available radio spectrum. This book has showed many people how to make their network available, even from the park bench, how to extend high-speed Internet access into the many areas not served by DSL and cable providers, and how to build working communities and a shared though intangible network. All that's required to create an access point for high-speed Internet connection is a gateway or base station. Once that is set up, any computer with a wireless card can log onto the network and share its resources. Rob Flickenger built such a network in northern California, and continues to participate in network-building efforts. His nuts-and-bolts guide covers: Selecting the appropriate equipment Finding antenna sites, and building and installing antennas Protecting your network from inappropriate access New network monitoring tools and techniques (new) Regulations affecting wireless deployment (new) IP network administration, including DNS and IP Tunneling (new) His expertise, as well as his sense of humor and enthusiasm for the topic, makes Building Wireless Community Networks a very useful and readable book for anyone interested in wireless connectivity.