Doctor of Philosophy / Department of Physics / Kristan L. Corwin / We have made significant accomplishments in the development of portable frequency standard inside hollow optical fibers. Such standards will improve portable optical frequency references available to the telecommunications industry. Our approach relies on the development of a stabilized Cr:forsterite laser to generate the frequency comb in the near-IR region. This laser is self referenced and locked to a CW laser which in turn is stabilized to a sub-Doppler feature of a molecular transition. The molecular transition is realized using a hollow core fiber filled with acetylene gas. We finally measured the absolute frequency of these molecular transitions to characterize the references. In this thesis, the major ideas, techniques and experimental results for the development and absolute frequency measurement of the portable frequency references are presented. A prism-based Cr:forsterite frequency comb is stabilized. We have effectively used the prism modulation along with power modulation inside the cavity in order to actively stabilize the frequency comb. We have also studied the carrier-envelope-offset frequency (f0) dynamics of the laser and its effect on laser stabilization. A reduction of f0 linewidth from [similar to]2 MHz to [similar to]20 kHz has also been observed. Both our in-loop and out-of-loop measurements of the comb stability showed that the comb is stable within a part in 10^11 at 1-s gate time and is currently limited by our reference signal. In order to develop this portable frequency standard, saturated absorption spectroscopy is performed on the acetylene v1+v3 band near 1532 nm inside different kinds of hollow optical fibers. The observed linewidths are a factor 2 narrower in the 20 um fiber as compared to 10 um fiber, and vary from 20-40 MHz depending on pressure and power. The 70 um kagome fiber shows a further reduction in linewidth to less than 10 MHz. In order to seal the gas inside the hollow optical fiber, we have also developed a technique of splicing the hollow fiber to solid fiber in a standard commercial arc splicer, rather than the more expensive filament splicer, and achieved comparable splice loss. We locked a CW laser to the saturated absorption feature using a Frequency Modulation technique and then compared to an optical frequency comb. The stabilized frequency comb, providing a dense grid of reference frequencies in near-infrared region is used to characterize and measure the absolute frequency reference based on these hollow optical fibers.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2008. / A rapid measurement system is implemented using two digital video cameras, presenting a faster and less expensive solution to certain metrology problems. The cameras are calibrated from one stereo image-pair of a 3D calibration grid that allows an immediate assessment of the achievable metric accuracy of the system. Three different methods, using either laser tracking or structured light patterns, were developed and employed to solve the coordinate extraction and correspondence matching problems. Different image processing techniques were used to speed up the entire measurement process. All software development was accomplished using only freely distributed software packages. The system achieves calibration in less than a minute and accumulates point correspondences at 12 frames per second. Accuracies of greater than 0.4 mm are achieved for a 235 x 190 x 95 mm measurement volume using a single pair of images with 640 x 480 pixel resolution each.

Traditionally, surface topography measurement was in the domain of quality control of engineering parts. With the advancement of manufacturing technology and affordable computational costs, different types of surfaces are produced with varied shapes and surface textures. These pose significant measurement problems, therefore, surface topography research is gaining momentum to achieve a better control of the surface. Coherence scanning interferometry (CSI) is one of the most common techniques used for measurement of surface topography. It is preferred over tactile and other non-contact techniques since it provides fast and accurate measurement with high vertical (~ 1 nm) and lateral (~1 μm) resolutions over larger areas without any damage to the surface. Essentially, CSI is treated as one dimensional (1D) superposition of the light waves from an object and a reference that generates a three dimensional (3D) interferogram. Secondly, despite the advantages, there is no standard configuration of CSI that can provide absolute surface topography measurement of an engineering part with multiple materials. An effective solution to this problem will be particularly useful in the field of semiconductor and bio-related industries where chips and instruments are made of many materials. In this Thesis, first, the CSI technique is analysed in terms of a wider theoretical framework of 3D linear filtering technique which shows the similarities among other seemingly disparate techniques such as confocal and optical coherence tomography. Due consideration to the spectral characteristic of the source and the effect of numerical aperture are given and important parameters such as vertical and lateral resolutions are computed to compare this theory with standard analysis methods. Additionally, it is shown that the 3D fringe pattern can be considered to be a superposition of a reference field and the scattered field from the top foil-like layer on the top the object. The scattered field from this foil object is dependent on the normal Fresnel reflection coefficients. Therefore, it explains the phase offset and the proportional height offset introduced by different materials, especially, metals. In an object, where multiple materials are present, each material introduces different phase to the fringe pattern and therefore, the surface topography of the entire object is altered. To overcome this problem, the optical polarising properties of the material are exploited. A novel configuration of polarisation sensitive CSI is presented where interferograms with orthogonal circular polarisations are recorded and analysed. The configuration, initially, needs to be calibrated with a material and after that at each point on the object, the refractive index and height offset can be calculated. Therefore, it can be dually used to identify unknown materials present on the object and also to compensate for the height offset introduced by each material to produce absolute surface topography of the entire object. The configuration provides good agreement with ellipsometric results for metals. Additionally, it retains the advantages of high vertical and lateral resolution same as other standard coherence scanning interferometers.

The main topic of this thesis is the development of novel diagnostics for the characterisation of infrared femtosecond and extreme-ultraviolet (XUV) attosecond pulses. High-resolution interferometric methods are applied to high harmonic radiation, both to measure the properties of the XUV light and to relate this information to the physics of the fundamental generation process. To do so, a complete high harmonic beamline has been built and optimised to enable the observation of strong signatures of the macroscopic response of the medium. The distinct spatial characteristics of long and short trajectories are studied, as well as the interference between them. An interferometric measurement allows the extraction of the atomic dipole phase, which gives direct access to the sub-cycle electron dynamics. A major focus of this thesis is on the development of a novel method which simultaneously characterises two independent electric fields as a function of any degree of freedom in which it is possible to shear one of the beams. Since each field alternately takes the role of the reference to retrieve the other field, this technique is referred to as mutual interferometric characterisation of electric-fields (MICE). One of the key features of MICE is that no sheared but otherwise identical replica of the test pulse needs to be generated, which is a typical requirement of self-referencing techniques. Furthermore, no a priori information is needed for the reconstruction. The strength and the wide applicability of MICE are demonstrated using two fundamentally different examples. First, the temporal pulse profiles of two infrared femtosecond pulses are simultaneously reconstructed in a single laser shot. In the second demonstration, the MICE approach is used to simultaneously reconstruct the wavefronts of two high harmonic beams. Having this new technique at hand, the phase properties of the different quantum trajectories are compared. All pulse characterisation techniques implicitly assume full coherence of the beam. This, however, is often not the case in practice, in particular when dealing with complex XUV light sources. Here the standard characterisation techniques fail to provide an accurate description of the electric field. Instead, the electric field must be seen as a statistical mixture of different contributions to the overall field. Here an interferometric experiment is first proposed and then performed involving multiple lateral shears to measure the two-point correlation function of high harmonic radiation. This directly provides information about the existence and the magnitude of partial coherence of high harmonics.

Due to the recent success, in terms of accuracy and precision, of a number of strontium optical lattice optical frequency standards, and the classification of the 5s² ¹S₀ to 5s5p ³P₀ transition in neutral strontium as a secondary definition of the SI unit of the second, many new strontium lattice clocks are under development. The strontium optical lattice clock (Sr OLC) at the National Physical Laboratory (NPL) is one such project. This thesis describes the design and build of the NPL Sr OLC, discussing the considerations behind the design. Details of the first cooling stage are given, which includes the characterisation of a novel permanent-magnet Zeeman slower by measurements of the longitudinal velocity distributions and loading of the MOT at 461 nm. Development of a narrow linewidth laser system at 689 nm is described, which is used for initial spectroscopy of the second-stage cooling transition. In particular, this work describes progress towards two independent ultra-narrow linewidth clock lasers. The new generation of strontium lattice clock experiments have focused on characterising the systematic frequency shifts and reducing their associated fractional frequency uncertainties, as well as reducing the fractional frequency instability of the measurement. One focus of the Sr OLC at NPL is to help characterise the frequency shift of the clock transition due to black-body radiation (BBR), which is currently the largest contributor to the uncertainty budget of the measured clock frequency. Our approach, discussed here, is to make a direct, differential measurement of the shift with the atoms housed alternately in environments of differing temperatures. Better characterisation and control of the BBR frequency shift of the strontium clock transition is crucial for the future of the Sr OLC as a leading frequency standard.

[pt] Gorduras trans são definidas pelo Codex Alimentarius como ácidos graxos insaturados que contém pelo menos uma dupla ligação trans. As gorduras trans de origem industrial são formadas durante a transformação pela hidrogenação parcial de óleos vegetais líquidos em gorduras semi-sólidas. Estas são amplamente usadas na fabricação de alimentos processados. Em 2002, um relatório da FAO/OMS, apresentou prova convincente de que a ingestão de gorduras trans aumentava efetivamente o risco de doenças cardiovasculares, e recomendou que seu consumo não deveria exceder 1% das calorias diárias ingeridas. Mesmo antes desse marco, diversas abordagens já haviam sido perseguidas por organizações governamentais e de saúde pública em diferentes países para reduzir o consumo desse tipo de gordura. No Brasil, através da resolução no360 da Anvisa de 2003, tornou-se obrigatória a declaração do conteúdo de gordura trans a partir de 2006. Esta dissertação apresenta a evolução e, analisa e avalia os processos regulatórios ligados à redução da gordura trans em alimentos nas experiências da Dinamarca, do Canadá e dos Estados Unidos, identificando as melhores práticas e lições nas experiências destes, contrapondo-as à experiência brasileira. A dissertação conclui destacando o papel da metrologia na qualificação da política pública para saúde, assim como outros aspectos derivados do diagnóstico dos diferentes estudos de caso levados a cabo. O estudo finaliza com a produção de recomendações para o refino e aprimoramento das ações de política pública e da regulação brasileira para a questão. / [en] Trans fats are defined by the Codex Alimentarius as unsaturated fatty acids containing at least a trans double bond. Industrially produced trans fats are formed in the course of the transformation through partial hydrogenation of liquid vegetable oils into semi-solid fats. They are amply used in the production of processed foodstuffs. In 2002, a FAO/WHO report presented convincing proof linking trans fat intake and the risk for developing cardiovascular disease, recommending that its daily consumption should not exceed 1% of total energy intake. Even before this milestone, several approaches had been pursued by government and public health organizations in different countries to reduce trans fat consumption. In Brazil, Anvisa’s 2003 resolution no360 established nutrition labeling of the trans fat content mandatory from 2006. This thesis presents the evolution and analyses and assesses the regulatory processes for reducing trans fats in foodstuffs in Denmark, Canada, and the United States, seeking to identify lessons and best practices in their experiences to contrast with the Brazilian one. The thesis concludes by highlighting the role of metrology in qualifying health policy as well as other aspects derived from the analysis of the case studies. At the end, the study makes some recommendations for refining and improving Brazilian public policy actions and regulation addressing this issue.

[pt] Através da função standby, um aparelho elétrico sai do seu modo de operação principal (em funcionamento); mas permanece ligado assumindo uma função em espera com o objetivo de economizar energia elétrica, até que o consumidor volte a utilizar o equipamento. Nesta dissertação é apresentada a estimativa do consumo de energia com o uso do standby em aparelhos elétricos de utilização doméstica; e o impacto financeiro deste desperdício para a população. O estudo foi motivado como forma de contribuir para o real entendimento deste consumo e oferecer subsídios que sirvam de alerta; visto que há um aumento da presença da tecnologia standby nos aparelhos existentes, e surgimento de novos equipamentos que possuem um consumo ocioso (quando não estão em funcionamento), podendo este cenário estar indo no caminho contrário às políticas atuais de conservação de energia. Para a estimativa, inicialmente foram utilizadas informações de Pesquisas de Posses e Hábitos de uso (PPH) de aparelhos elétricos para se traçar um panorama da forma como cada aparelho é utilizado sobre o modo de operação standby; em seguida coletaram-se informações de consumo de energia elétrica obtidas através de medições dos próprios equipamentos elétricos, onde foi identificado que o aparelho de TV por assinatura é o grande vilão do consumo ocioso em standby. O último passo foi extrapolar as informações estimadas para uma concessionária local e para o Brasil, e simular o desperdício de energia elétrica com o consumo do standby nos aparelhos elétricos de uso doméstico, chegando-se ao resultado de 1,6 TWh/ano de desperdício alocado aos consumidores residenciais do Brasil, o que representa 1,9 porcento do volume de vendas de energia no segmento. / [en] Through the standby function, an electrical device goes out of your main operation mode (in use); but remains on, assuming a waiting function to save electricity, until the consumer reuse the equipment. In this dissertation, the estimated power consumption is presented with the use of standby function in electrical appliances from domestic use; and the financial impact of this waste to the population. The study was motivated as a way to contribute to the real understanding of this consumption, and offer subsidies that serve as warning; since there is an increased presence of the standby technology in existing devices, and the emergence of new equipments that has an idle consumption (when not operating), perhaps this scenario may be going against the current policies of energy conservation. To estimate, initially was used information from Electrical Appliances Ownership Survey to draw a picture of how each device is used in standby operation; then collected information about power consumption obtained through measurements of each electrical equipment, where it was identified that cable TV is the biggest villain of the idle standby consumption. The last step was to extrapolate the estimates for a local electric utility and Brazil, and simulate the waste of electrical energy consumption in the standby electrical household appliances, coming to the result of 1.6 TWh/year of waste allocated to residential consumers in Brazil, which represents 1,9 percent of the energy sales in the segment.

Les techniques d’analyse thermique et de calorimétrie sont des méthodes d’essai largement utilisées dans les laboratoires d’analyse physico-chimique, pour des finalités de recherche ou de contrôle qualité. Comme tout appareil de mesure, un analyseur thermique ou un calorimètre doit être étalonné en température et en énergie avec des matériaux de référence certifiés. Les matériaux de référence recommandés correspondent généralement aux points fixes de l'échelle internationale de température (EIT-90), à savoir gallium, indium, étain, zinc et aluminium. Il existe peu de matériaux de référence certifiés au-dessus de 420 °C, alors que certains analyseurs thermiques peuvent être utilisés jusqu'à 1000 °C, voire au-delà.L’élaboration et la certification de matériaux de référence doivent employer des méthodes de mesure très précises avec un raccordement métrologique des mesures au système international d’unités (SI). Le Laboratoire Commun de Métrologie (LCM) s'est engagé dans le développement d'un moyen de référence métrologique en calorimétrie permettant des mesures précises en enthalpie de fusion et en capacité thermique massique sur la plage de température [23 °C, 1000 °C]. La solution métrologique retenue a été de modifier un calorimètre de type Calvet, et de mettre au point des procédures d’étalonnage et de mesure afin d’atteindre des incertitudes de mesures suffisamment faibles pour la certification des matériaux de référence.Dans ce travail, un système d'étalonnage fonctionnant à haute température a été spécifiquement conçu et intégré dans le calorimètre pour permettre l'étalonnage par substitution électrique. Ce système permet de réaliser successivement des étalonnages par effet Joule et des mesures d’enthalpie de fusion, sans modification des conditions expérimentales.Ce travail comprend également le développement des systèmes d’acquisition et traitement des résultats des mesures. La détermination de l'enthalpie de fusion de plusieurs métaux (indium, étain et argent notamment) avec une recherche des facteurs d’influence sur cette grandeur, et une estimation des incertitudes de mesure. La mesure de l’enthalpie de fusion d’un alliage eutectique argent-cuivre, candidat comme matériau de référence en énergie à 779 °C, est également présentée. / Differential scanning calorimeters are widely used in many academic and industrial laboratories to study the thermal behavior of materials for research or quality control. Like any measuring device, a thermal analyzer or calorimeter must be calibrated in temperature and energy with certified reference materials. Recommended reference materials generally correspond to fixed points of the International Temperature Scale (ITS- 90), namely: gallium, indium, tin, zinc and aluminum. However, there are few certified reference materials above 420 °C, while the operating range of some thermal analyzers and calorimeters exceeds 1000 °C.The certification of reference materials insures the metrological traceability of measurements to the International System of Units (SI). The LCM-LNE has been working in the development of a metrological standard facility for accurate measurements of the enthalpy of fusion and heat capacity in the temperature range [23 °C, 1000 °C]. The metrological approach is based on the modification of a commercial Calvet calorimeter and of the procedures implemented for calibration and measurement, so as to get measurement uncertainties sufficiently low to fulfill the objectives of the certification of reference materials.A new in-situ high temperature calibration system (constituted by a resistance wire wound around the crucible containing the material sample) was integrated into the calorimeter to perform the calibration by electrical substitution. The system allows both calibration and measurement without modification of the apparatus, so that the experimental conditions during both steps remain unchanged.This work also includes the development of data acquisition system and processing of measurement results. The determination of the enthalpy of fusion of several metals (indium, tin and silver in particular) with an estimation of the measurement uncertainty has been made. The measurement of the enthalpy of fusion of a silver-copper eutectic alloy, as candidate reference material at 779 °C, is also presented.

L’instrumentation et la mesure en ligne pour les Material Testing Reactors sont en pleine expansion en France en particulier avec la construction du Réacteur Jules Horowitz (RJH) qui possédera des capacités expérimentales accrues (conditions extrêmes). Conception/développement/optimisation de moyens expérimentaux sont requis pour une caractérisation fine des conditions expérimentales régnant dans ce MTR. C’est dans ce contexte que s’inscrivent mes travaux de thèse. Plus précisément depuis 2009, le CEA et l'Université d'Aix-Marseille (Laboratoire IM2NP UMR7334, eq. Microcapteurs-Instrumentation) conduisent des programmes de recherche au sein du laboratoire commun LIMMEX afin de proposer de nouveaux capteurs et dispositifs dédiés à la détermination spatiale et temporelle des flux neutrons/photons et de l’échauffement nucléaire dans les matériaux inertes par interactions rayonnements nucléaires/matière dans les canaux du RJH. Les travaux de ma thèse ont porté sur la calorimétrie, méthode permettant la quantification de l’échauffement nucléaire. L’objectif était d’étudier et d’optimiser la méthode et les capteurs hors flux nucléaires et d'améliorer les étapes conduisant à la quantification de l’échauffement nucléaire. Ces travaux expérimentaux et numériques ont comporté trois volets principaux. Le 1er a porté sur des études sur la réponse et le comportement de calorimètres différentiels classiques. Le 2ème volet a été dédié à des études sur la méthode d’étalonnage des calorimètres prototypes. Le 3ème volet a consisté à l’interprétation de mesures d’échauffement nucléaire et à la simulation de nouveaux capteurs pouvant mesurer un échauffement nucléaire de 20W.g-1 dans le RJH. / The instrumentation and on-line measurement for Material Testing Reactors are booming in France in particular with the construction of the Jules Horowitz Reactor (RJH), which possess increased experimental capacity (extreme conditions). Design / development / optimization of experimental resources are required for a detailed characterization of experimental conditions in the MTR. It is in this context that fit my thesis work. Specifically since 2009, the CEA and the University of Aix-Marseille (IM2NP Laboratory UMR7334, eq. Microcapteurs-Instrumentation) lead research programs in the LIMMEX joint laboratory to provide new sensors and devices dedicated to determining spatial and temporal neutron / photon fluxes and nuclear heating in the inert materials by nuclear radiation / matter interactions in the channels of RJH. The work of my thesis focused on calorimetry method for the quantification of nuclear heating. The objective was to study and optimize the method and sensors excluding nuclear flow and improve the steps leading to the quantification of nuclear heating. These experimental and numerical works involved three main components. The first focused on studies of the response and behavior of conventional differential calorimeters. The second part was devoted to studies on the calibration method calorimeters prototypes. The third component was the interpretation of nuclear heating measures and simulation of new sensors that can measure a nuclear heating of 20W.g-1 in the JHR.

[pt] O uso seqüencial de energia elétrica e energia térmica a partir da energia química do mesmo combustível tem sido estudado para melhorar o custo benefício de uma geração distribuída. O objetivo deste estudo é determinar o mercado potencial desta tecnologia na região de influência da concessionária local de energia elétrica. Para alcançar este objetivo, foi necessário avaliar o desempenho de um sistema de cogeração com uma microturbina fornecendo potência elétrica e energia térmica através dos gases de exaustão que aquecem água para o ginásio esportivo da PUC-Rio. O sistema está configurado por uma microturbina, uma caldeira de recuperação, um reservatório térmico (boiler) e uma caixa para alimentação de água fria. Resultados obtidos de testes de curta duração, através de uma metodologia desenvolvida, para a avaliação do desempenho do sistema de cogeração na produção de energia elétrica e térmica, são apresentados. Os testes foram realizados para potências elétricas de 100, 75, 50 e 25 % da carga máxima da microturbina. Em adição, testes para avaliação do desempenho ao longo do tempo em função das variações da carga e das condições ambientais foram estudados. Além disso, através de uma metodologia desenvolvida, mostram-se os resultados nos cálculos de incerteza dos parâmetros analisados. Dados de consumo de energia elétrica em janeiro de 2003, de cerca de 8000 consumidores na área de concessão da LIGHT SESA, em diferentes classes tarifárias, atualizadas para 2007, foram utilizados com a metodologia desenvolvida para estimar o mercado potencial de energia elétrica na região de influência da concessionária local de energia elétrica em 384,5 MW e 20415 MWh/mês, considerando uma taxa interna de retorno mínimo de 15% a.a. Foi mostrado que o elevado custo da microturbina é uma barreira para sua introdução no mercado. Entretanto, a cogeração pode colaborar substancialmente para melhorar o custo benefício. Estas conclusões foram obtidas a partir do tempo de retorno do investimento no sistema pelos consumidores analisados. / [en] The sequential use of electric energy and thermal energy from the chemical energy of the same fuel has been studied to improve the cost benefit of a distributed generation. The objective of this study is to evaluate the potential market of this technology in the region of influence of the local utility of electric energy.utility company (LIGHT). In order to attain this objective, it was necessary to evaluate the performance of a micro turbine based cogeneration system used for supplying electrical and thermal energy to PUC-RIO´S Gymnasium. The system consists of a microturbine, a heat recovery boiler, and a cold water feeding reservoir. The short duration test results are presented for the evaluation of the cogeneration system performance for the production of electric and thermal energy. The tests were carried on for 100, 75, 50 and 25% micro turbine electric energy generation loads. Time performance of the micro turbine was also studied. Moreover, a methodology was shown to calculate the uncertainty of measurements of several performance parameters. The micoturbine marked potential was estimated by analyzing the consumption of about 8000 clients in January 2003, updating the tariffs to 2007, resulting in 384,5 MW and 20415 MWh/month, considering a minimum internal rate of return of investiment of 15% per year, during a 15 year period. It was concluded that the microturbine cost is still a barrier to its market penetration. Cogeneration can be used to improve the cost benefit of the system.