Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

No description available.

No description available.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The beam quality factor (M2) of a laser is important because it describes both the quality of a laser beam as well as its propagation. Particular applications require that the beam radii (from which the M2 factor is determined) be defined in a specific way. The International Standards Organisation (ISO) recently standardised the theoretically correct, but practically difficult second moment definition of the beam radius. This thesis aims to establish correlations between the second moment definition and other more practical definitions. Chapter 2 presents a systematic introduction of moment theory for general beams. Beam centre and radius definitions as well as beam classification are derived by means of second and mixed moments. In Chapter 3 simple laser beams are modelled by means of a resonator approach. The infinite number of solutions of this model is called Gaussian solutions, which are found to be different for rectangular and cylindrical symmetric resonators. The zero order solution for both symmetries is identified as the ideal solution to which all others can be compared to for quality determinations. Chapter 4 presents different beam scanning devices, beam radius definitions and correlations between these definitions. The theoretical basis for a new correlation theory is also given. Chapter 5 describes programs and computations used to verify existing correlation methods and to calculate correlation factors for a newly proposed theory. Chapter 6 presents the results of the computations for both circular and rectangular symmetric beams. The ISO’s correlation theories are tested first. Newly proposed correlation functions between the second moment and alternative definitions as well as theoretical error graphs are given for various beams. A novel method to correlate several important beam subclasses is also presented. Chapter 7 describes the experimental setup, automation software and post processing techniques that were used to characterise a modified CO2 TEA laser. It is further shown how the theory developed in previous chapters could be applied to the experimental data. Chapter 8 presents the experimental results of the beam characterisation measurements performed on two different beams that emanated from the CO2 TEA laser. Existing and newly developed correlation theories are applied to the experimental data and the corresponding results are compared. In Chapter 9, conclusions and suggestions with respect to the initial aims identified in the first chapter are made. Several suggestions for future work are also made. / AFRIKAANSE OPSOMMING: Die bundel kwalitietsfaktor (M2) is baie belangrik omdat dit beide die kwaliteit en voortplanting van ‘n laser bundel beskryf. Bundel radiusse (waarvan die M2 faktor bepaal word) word verskillend gedefinieer vir spesifike toepassings. Die teoreties korrekte, maar minder praktiese tweede moment definisie is onlangs deur die Internasionale Standaard Organisasie (ISO) gestandariseer. Hierdie tesis se hoofdoel is om die tweede moment definisie en ander meer praktiese definisies te korreleer. Hoofstuk 2 stel die moment teorie van bundels sistematies bekend. Dit word gewys hoe die senter en radius van ‘n bundel deur tweede en gemengde momente gedefinieer kan word. In Hoofstuk 3 word laser bundels gemodeleer deur middel van resonator aanslag. Die oneindige aantal oplossings wat verkry word heet Gaussiese oplossings en is verskillend vir reghoekige en silindriese simmetriese resonators. Dit word gewys dat die ideale bundel, waarmee alle ander bundels vergelyk word, die zero orde oplossing van beide simmetrieë is. Hoofstuk 4 stel verskillende bundel skanderings apparaat, bundel radius definisies en korrelasies tussen die definisies bekend. Die teoretiese basis vir ‘n nuwe korrelasie teorie word ook gegee. Hoofstuk 5 beskryf die rekenaarprogramme en berekeninge wat gebruik word om huidige korrelasie teorie mee te toets asook om nuwes mee te skep. Hooftuk 6 gee die resultate van die berekeninge van die rekenaarprogramme vir beide reghoekig en silindriese simmetrie. Die ISO se korrelasies word eerste getoets voordat nuwe teorieë bekend gestel word. In Hoofstuk 7 word die eksperimentele opstelling, outomisasie sagteware en postprosessering tegnieke gewys wat gebruik was om ‘n aangepaste CO2 TEA laser te karakteriseer. Verder word dit gewys hoe die teorie wat in voorafgaande hoofstukke ontwikkel is op eksperimentele data toegepas kan word. Hoofstuk 8 gee die eksperimentele resultate van die bundel karakterisering van twee verskillende bundels vanaf die CO2 TEA laser. Bestaande en nuwe korrelasie metodes word gebruik om die bundels te korreleer en die resultate van elke metode word dan met mekaar vergelyk. In Hoostuk 9 word afleidings gemaak. Daar word ook voorstelle gemaak vir potensiële toekomstige werk.

Optical trapping and tweezing has been around for the last 30 years and since found its place in the fields of physics and biology. Over the years this technique has advanced exceedingly and is a unique tool to carry out research in the micrometre and nanometre scale regime. The aim of this dissertation was to illustrate that an optical trapping and tweezing system is an effective tool for the manipulation of micron sized particles and that using such a system allows one the ability to accurately and precisely measure optical forces in the piconewton scale. A custom built single gradient optical trapping system was built to illustrate the manipulation of micron sized particles. Here we will highlight some of the key components of such a system and give an explanation of how these components affect the optical trap. To enhance this system, we exploit the ability to shape light and in particular laser light to generate novel laser beams. This was achieved using a diffractive optical element known as a spatial light modulator (SLM). A spatial light modulator is an electronically addressed optical element which when incorporated into an optical system effectively manipulates the phase of light in order to generate various novel laser beams. In particular these novel laser beams include Laguerre-Gaussian, Bessel and recently proposed Bessel-like beams. Each of these beams contains interesting properties which can be beneficially exploited. Laguerre-Gaussian beams are particularly known as ‘donut’ shaped beams since they have a central dark hole. Increasing the order of these Laguerre-Gaussian beams leads to an increase in the central dark region. These beams are of particular interest since they carry orbital angular momentum. This is not easily observed; however, when incorporated into the optical trapping system, leads to the rotation of trapped particles due to the transfer of photons carrying orbital angular momentum. Bessel and Bessel-like beams on the other hand are classes of beam that possess interesting non-diffracting and self-reconstructive properties upon encountering an obstacle. Here the generation and properties of these novel laser beams will be discussed in detail. Furthermore it is well known that these novel laser beams prove highly useful when incorporated into an optical trapping system hence we will illustrate the effects on a trapped particle when incorporating a Laguerre-Gaussian beam carrying a topological charge of one. It is expected that the trapped particle should rotate due to the transfer of orbital angular momentum. The knowledge gained from beam shaping and the means to trap micron sized particles optically allows one the ability to incorporate this technique in a number of fields, including the promising field of microfluidics. This is an emerging field that deals with investigating fluid properties at the nano and microlitre regime. Optical tweezers integrated into a microfluidic device are beneficial since they are an adequate tool for measuring fluid flow using Stokes’ Law. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2011.

by Niu Aizhen. / "Mar., 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / 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.

by Iu Chun-ho. / Bibliography: leaves 80-81 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

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

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

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