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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Effects of a laser beam on another laser beam in a photorefractive crystal. / 一激光束對在光折變晶體中之另一激光束的影響 / Effects of a laser beam on another laser beam in a photorefractive crystal. / Yi ji guang shu dui zai guang zhe bian jing ti zhong zhi ling yi ji guang shu de ying xiang

January 2000 (has links)
by Lee, Kai Kwong Dennis = 一激光束對在光折變晶體中之另一激光束的影響 / 李啓光. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 106-109). / Text in English; abstracts in English and Chinese. / by Lee, Kai Kwong Dennis = Yi ji guang shu dui zai guang zhe bian jing ti zhong zhi ling yi ji guang shu de ying xiang / Li Qiguang. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Content --- p.iv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Theory --- p.4 / Chapter 2.1 --- Two-wave Coupling --- p.4 / Chapter 2.2 --- Four-wave Mixing --- p.10 / Chapter 2.3 --- Fanning --- p.13 / Chapter 2.4 --- Phase-conjugation --- p.16 / Chapter 2.5 --- Spatial Solitons --- p.19 / Chapter Chapter 3 --- "Experiments,Results and Discussion" --- p.26 / Chapter 3.1 --- Measurements of Optically Induced Refractive Index Change --- p.26 / Chapter 3.2 --- Optical Control Experiments --- p.65 / Chapter 3.3 --- Soliton Experiments --- p.80 / Chapter Chapter 4 --- Concluding Remarks and Suggested Further Studies --- p.99 / References --- p.105
42

Synthesis and laser light scattering studies of linear polymer chains and polymeric nanoparticles.

January 2001 (has links)
Lau Chin Wa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 77-78). / Abstracts in English and Chinese. / Abstract --- p.i / Chinese Abstract --- p.ii / Acknowledgement --- p.iv / Contents --- p.v / Abbreviations --- p.viii / List of Figures --- p.xiv / List of Tables --- p.xviii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Basic Principle of Laser Light Scattering and Instrumentation --- p.7 / Chapter 2.1 --- Static laser light scattering (Static LLS) --- p.8 / Chapter 2.2 --- Dynamic laser light scattering (Dynamic LLS) --- p.9 / Chapter 2.3 --- Calibration between translational diffusion coefficient D and molar mass M --- p.10 / Chapter 2.3.1 --- Tranform G(D) to Molar Mass Distributionfw(M) --- p.10 / Chapter 2.3.2 --- Calibration between D and M- Using a set of narrowly distributed standards --- p.12 / Chapter 2.3.3 --- Calibration between D and M- Using two or more broadly distributed samples --- p.12 / Chapter 2.4 --- Data Analysis --- p.14 / Chapter 2.5 --- References --- p.16 / Chapter Chapter 3 --- Experimental --- p.17 / Chapter 3.1 --- Laser Light Scattering Instrumentation --- p.17 / Chapter 3.1.1 --- Overview of laser light scattering spectrometer --- p.17 / Chapter 3.1.2 --- Differential Refractometer --- p.18 / Chapter 3.2 --- References --- p.21 / Chapter Chapter 4 --- Thermally Sensitive and Biocompatible Poly(N-vinylcaprolactam): Synthesis and Characterization of High Molar Mass Linear Chains / Chapter 4.1 --- Introduction --- p.22 / Chapter 4.2 --- Sample Preparation --- p.23 / Chapter 4.3 --- Results and discussion --- p.24 / Chapter 4.4 --- Conclusion --- p.27 / Chapter 4.5 --- References --- p.29 / Chapter Chapter 5 --- Stabilization and destabilization of potassium persulfate (as an initiator) in an surfactant-free water/acetone mixture emulsion polymerization of styrene under microwave irradiation / Chapter 5.1 --- Introduction --- p.41 / Chapter 5.2 --- Experimental --- p.43 / Chapter 5.3 --- Results and discussion --- p.44 / Chapter 5.4 --- Conclusion --- p.51 / Chapter 5.5 --- References --- p.53 / Appendix / Chapter A.l --- Static Laser Light Scattering --- p.66 / Chapter A.1.1 --- Scattering from a small particles --- p.66 / Chapter A.1.2 --- Scattering from a large particles --- p.67 / Chapter A.1.3 --- Scattering by solutions of small molecules --- p.69 / Chapter A.1.3.1 --- Scattering from polymer solutions --- p.70 / Chapter A.2 --- Dynamic laser light scattering --- p.71 / Chapter A.2.1 --- Line-width measurement --- p.73 / Chapter A.2.2 --- Data analysis --- p.75
43

Two-wave mixing in photorefractive Cu:KNSBN and Fe:LiNbO3 crystals and bright photovoltaic spatial solitons in photorefractive Fe:LiNbO3 crystals. / 光折變摻銅鉀鈉鈮酸鍶鋇和摻鐵鈮酸鋰晶體中的二波耦合及摻鐵鈮酸鋰晶體中的亮光伏空間孤子 / Two-wave mixing in photorefractive Cu:bKNSBN and Fe:LiNbO3 crystals and bright photovoltaic spatial solitons in photorefractive Fe:LiNbO3 crystals. / Guang zhe bian shan tong jia na ni suan si bei he shan tie ni suan li jing ti zhong de er bo ou he ji shan tie ni suan li jing ti zhong de liang guang fu kong jian gu zi

January 2005 (has links)
Guo Bin = 光折變摻銅鉀鈉鈮酸鍶鋇和摻鐵鈮酸鋰晶體中的二波耦合及摻鐵鈮酸鋰晶體中的亮光伏空間孤子 / 郭斌. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Guo Bin = Guang zhe bian shan tong jia na ni suan si bei he shan tie ni suan li jing ti zhong de er bo ou he ji shan tie ni suan li jing ti zhong de liang guang fu kong jian gu zi / Guo Bin. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.v / Chapter Chapter 1 --- Introduction --- p.1 / References --- p.6 / Chapter Chapter 2 --- Background --- p.7 / Chapter 2.1 --- Photorefractive Effect Based on Band Transport Model --- p.7 / Chapter 2.2 --- Photovoltaic Effect --- p.15 / Chapter 2.3 --- Surface Charge Recombination in Fe:LiNb〇3 Crystals --- p.17 / References --- p.19 / Chapter Chapter 3 --- Noise of Two-Wave Mixing in Cu:KNSBN Crystal --- p.20 / Chapter 3.1 --- Introduction --- p.20 / Chapter 3.2 --- Experimental Setup --- p.22 / Chapter 3.3 --- Results and Discussion --- p.23 / Chapter 3.4 --- Conclusion --- p.29 / References --- p.30 / Chapter Chapter 4 --- Bright Photovoltaic Spatial Soliton in Fe:LiNb03 Crystals / Chapter 4.1 --- Introduction --- p.32 / Chapter 4.2 --- Theory --- p.33 / Chapter 4.3 --- Experimental Setup --- p.36 / Chapter 4.4 --- Results and Discussion --- p.39 / Chapter 4.5 --- Conclusion --- p.58 / References --- p.59 / Chapter Chapter 5 --- Two-Wave Mixing of Narrow Laser Beams in a Fe:LiNbO3 Crystal --- p.60 / Chapter 5.1 --- Introduction --- p.60 / Chapter 5.2 --- Theory of Two-Wave Mixing --- p.62 / Chapter 5.3 --- A Simplified Analysis of Two-Wave Mixing of Narrow Beams --- p.66 / Chapter 5.4 --- Experimental Setup --- p.70 / Chapter 5.5 --- Results and Discussion --- p.71 / Chapter 5.6 --- Conclusion --- p.86 / References --- p.87 / Chapter Chapter 6 --- Two-Wave Mixing of Narrow Laser Beams with an Incoherent Background Beam --- p.89 / Chapter 6.1 --- Theory --- p.89 / Chapter 6.2 --- Experimental Setup --- p.93 / Chapter 6.3 --- Results and Discussion --- p.94 / Chapter 6.4 --- Conclusion --- p.105 / References --- p.106 / Chapter Chapter 7 --- Conclusion and Future Outlook --- p.107
44

Laser light scattering study on breathing modes of soft porous hollow spheres swollen in liquid. / CUHK electronic theses & dissertations collection

January 2004 (has links)
Wang Chengqing. / "November 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
45

Studies on nanobubbles in aqueous solutions. / CUHK electronic theses & dissertations collection

January 2007 (has links)
Chapter 1 briefly introduces the background, problems, applications as well as recent progress of the nanobubbles research. The relationship between the formation/stabilization of nanobubbles and the long-rang structures of water molecules, particularly the restructuring of water molecules at the water/gas interface, are emphasized. / Chapter 2 introduces the theories of static and dynamic light scattering and Zeta-potential measurements as well as the details of the instrument set-up. In this chapter, the fundamental equations of the scattering theory are figured out basis on the quasi-classical electrodynamics and combination of the statistical mechanics as well as molecular dynamic theory. Finally, the statistical properties of photon counting are discussed. / In chapter 3, aqueous solutions of tetrahydrofuran, ethanol, urea and alpha-cyclodextrin were studied by a combination of static and dynamic laser light scattering (LLS). In textbooks, these small organic molecules are soluble in water so that there should be no observable large structures or density fluctuation in either static or dynamic LLS. However, a slow mode has been consistently observed in these aqueous solutions in dynamic LLS. Such a slow mode was previously attributed to some large complexes or supramolecular structures formed between water and these small organic molecules, Our current study reveals that it is actually due to the existence of small bubbles (∼100 nm in diameter) formed inside these solutions. Our direct evidence comes from the fact that it can be removed by repeated filtration and regenerated by air purging. Our results also indicate that the formation of such nanobubbles in small organic molecules aqueous solutions is a universal phenomenon. Such formed nanobubbles are rather stable. The measurement of isothermal compressibility confirms the existence of a low density micro-phase, presumably nanobubbles, in these aqueous solutions. Using a proposed structural model, i.e., each bubble is stabilized by small organic molecules adsorbed at the gas/water interface, we have, for the first time, estimated the pressure inside these nanobubbles. / In chapter 4, by using a combination of laser light scattering (LLS) and zeta-potential measurements, we investigated effects of salt concentration and pH on stability of the nanobubbles in alpha-cyclodextrin (alpha-CD) aqueous solutions. Our LLS results reveal that the nanobubbles are unstable in solutions with a higher ionic strength, just like colloidal particles in an aqueous dispersion, but become more stable in alkaline solutions. The zeta-potential measurement shows that the nanobubbles are negatively charged with an electric double layer, presumably due to the adsorption of negative OTT ions at the gas/water interface. It is this double layer that plays dual roles in the formation of stable nanobubbles in aqueous solutions of water-soluble organic molecules; namely, it not only provides a repulsive force to prevent the inter-bubble aggregation and coalescence, but also reduces the surface tension at the gas/water interface to decreases the internal pressure inside each bubble. / In chapter 5, the addition of salt can induce slow coalescence of nanobubbles (∼100 nm) in an aqueous solution of alpha-cyclodextrin (alpha-CD). A combination of static and dynamic laser light scattering was used to follow the coalescence. Our results reveal that its kinetic and structural properties follow some scaling laws; namely, the average size (<zeta>) of nanobubbles is related to their average mass (<M>) and the coalescence time (t) as <M> <zeta>dr and <zeta> ∼ tgamma with two salt-concentration dependent scaling exponents (df and gamma) For a lower sodium chloride concentration (C NaCl = 40 mM), gamma = 0.13 +/- 0.01 and df = 1.71 +/- 0.02. The increase of CNaCl to 80 mM results in gamma = 0.32 +/- 0.01 and df = 1.99 +/- 0.01. The whole process has two main stages: the aggregation and the coalescence. At the lower C NaCl, the process essentially stops in the aggregation stage with some limited coalescence. At higher CNaCl leads the coalescence after the aggregation and results in large bubbles. / In this thesis, the nanobubbles in the aqueous solutions have been studied by using combination of static and dynamic laser light scattering (LLS), isothermal compressibility measurements and Zeta-potential measurements. We found that the nanobubbles extensively exist in aqueous solutions and the interface of each nanobubble is negatively charged. The addition of electrolytes can destabilize such interface to induce the coalescence of nanobubbles. / Jin, Fan. / "Aug 2007." / Adviser: Chi Wu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1030. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
46

Light scattering studies on several fundamental problems in polymer solution. / CUHK electronic theses & dissertations collection

January 1996 (has links)
by Yubao Zhang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. 138-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.
47

Resonance-enhanced laser-induced breakdown spectroscopy : how the beam profile of the ablation laser and the interception geometry and energy of the reheating laser affect analytical performance

Yip, Wing Lam 01 January 2009 (has links)
No description available.
48

Nonlinear paraxial equation at laser plasma interaction

Osman, Frederick, University of Western Sydney, Macarthur, Faculty of Business and Technology January 1998 (has links)
This thesis presents an investigation into the behaviour of a laser beam of finite diameter in a plasma with respect to forces and optical properties, which lead to self-focusing of the beam. The transient setting of ponderomotive nonlinearity in a collisionless plasma has been studied, and consequently the self- focusing of the pulse, and the focusing of the plasma wave occurs. The description of a self-focusing mechanism of laser radiation in the plasma due to nonlinear forces acting on the plasma in the lateral direction, relative to the laser has been investigated in the non-relativistic regime. The behaviour of the laser beams in plasma, which is the domain of self-focusing at high or moderate intensity, is dominated by the nonlinear force. The investigation of self-focusing processes of laser beams in plasma result from the relativistic mass and energy dependency of the refractive index at high laser intensities. Here the relativistic effects are considered to evaluate the relativistic self-focusing lenghts for the neodymium glass radiation, at different plasma densities of various laser intensities. A sequence of code in C++ has been developed to explore in depth self-focusing over a wide range of parameters. The nonlinear plasma dielectric function to relativistic electron motion will be derived in the latter part of this thesis. From that, one can obtain the nonlinear refractive index of the plasma and estimate the importance of relativistic self-focusing as compared to ponderomotive non-relativistic self-focusing, at very high laser intensities. When the laser intensity is very high, pondermotive self-focusing will be dominant. But at some point, when the oscillating velocity of the plasma electron becomes very large, relativistic effects will also play a role in self-focusing. A numerical and theoretical study of the generation and propagation of oscillation in the semiclassical limit of the nonlinear paraxial equation is presented in this thesis. In a general setting of both dimension and nonlinearity, the essential differences between the 'defocusing' and 'focusing' cases hence is identified. Presented in this thesis are the nonlinearity and dispersion effects involved in the propagation of solitions which can be understood by using a numerical routines were implemented through the use of the mathematica program, and results give a very clear idea of this interesting phenomena / Doctor of Philosophy (PhD)
49

Statistical measurements of speckle propagation through the turbulent atmosphere /

Fossey, Michael E. January 1976 (has links)
Thesis (M.S.)--Oregon Graduate Center, 1976.
50

A mixed mode thermal/fluids model for improvements in SLS part quality, machine design, and process design /

Norrell, Jeffery Lee, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 232-244). Available also in a digital version from Dissertation Abstracts.

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