Power utilities around the world are now in the practice of installing fiber optic cables on their high voltage transmission networks. These high-speed communication channels can, not only transmit data needed for utility operation, but the unused fiber capacity may also be rented to others for communication. All dielectric self-supporting (ADSS) fiber optic cable appears to be the fiber optic cable most frequently installed by power utilities as it is more economical, has a larger fiber capacity and may be installed on a transmission line without de-energization. When installed however, ADSS fiber optic cable does undergo some degree of degradation caused either by armor rod corona at the towers or dry-band arcing. A comprehensive literature survey regarding both phenomena is presented in this study, as well as current mitigation techniques. Different models that describe the process of dry-band arcing are discussed, including those where an equivalent circuit is used to represent a polluted fiber optic cable in a high voltage environment. An implementation of this model on a MATLAB® based computer program is used to evaluate parameters such as leakage current magnitude, which may be used to predict the possibility of dry-band arcing. This leakage current is also compared to simulated results that were generated using a power system analysis program called Alternate Transients Program (ATP). A finite element package, FEMLAB®, was used to model the experimental system, prior to construction. A single-phase transmission line with an accompanying fiber optic cable was constructed. The leakage current magnitude obtained from this experiment was subsequently compared to those obtained from the simulations. These leakage current comparisons are discussed and explained in view of limitations with the theoretical models and refinements in the experimental techniques employed. The results clearly indicate that physical parameters like pollution severity, system voltage, length of span and the point of attachment of the ADSS fiber optic cable in the tower play a significant role in the determination of leakage currents induced on the outer sheath of the cable. These induced currents result in the formation of 'dry bands', due to joule heating, and this could result in arcing activity that erodes the fiber optic cable. / Thesis (M.Sc.Eng)-University of Natal, Durban, 2003.

The aim of this thesis is to explain the problems of optical access networks with wavelength division multiplexers, main purpose is to demonstrate the difference between theoretical and real measurement. The work is divided into several thematic areas. The introduction outlines the basic of telecommunications, fiber optics lasers, single mode, multimode, lasers fibers cables & cores, splitters division multiplexing system, there are known solutions discussed fundamental wavelength multiplexes and their possible combinations. The following chapter deals with the active elements such as AON, PON, which are essential part xWDM systems such as optical lasers, detectors and amplifiers. Another chapter focuses on passive elements, which form a key part of the wavelength multiplex. Methods of measurement of WDM/PON networks are discussed in the following part. The next section describes the topology used active and passive optical networks. The penultimate part of the work consists of architecture & technology of xWDM such as GPON and WDM-PON networks and comparing their transmission parameters. The final part of the paper presents the results of practical experimental measurements of optical access networks with wavelengths division multiplex while these results are compared with the theoretical output & methods of Optical lost test, OTDR & LSPM, with advantage & disadvantage of every methods. The second part of practical is the draft to the connection resident housing units of 30 houses, boarding-house (10 rooms) and 2 shops, 20 km distant from exchange. With comparing the possibilities of two options- passive and active optical network- PON system – WDM- Wave multiplex. Suggest the possibility of measuring and monitoring the created network.

The continued growth of the communications industry has caused interest in mode-division multiplexing (MDM) techniques to flourish in recent years. These techniques allow individual waveguide modes to be used as distinct channels. However, as with any versatile technique, it should be also useful and beneficial to extend its application to other areas. This work concerns itself with an initial conceptual design of a mode-division multiplexing (MDM) enabled optical sensor network that can use modes to interrogate either specific sensors or sensor subsystems, and specifically with quanitizing and optimizing the injection and detection of the signal of interest. A hypothetical test setup is demonstrated, and the major issue of back reflection burying the intended signal is addressed, analyzed, and improved. Improvements in the signal-to-background contrast ratio (SBCR) of approximately 10dB were achieved depending on fibre type and proximal face. Suggestions for extensions to further improve the SBCR as well as for applications of this system are discussed. / Master of Science

A iluminação dos espaços é observada há milênios, desde a utilização do fogo até as mais novas tecnologias em iluminação. Iluminar ambientes procurando, cada vez mais, a eficiência e a economia de energia vem sendo motivo de investigação constante dos pesquisadores. Atualmente, o grande problema enfrentado pela iluminação artificial é o custo da energia elétrica e por isso vários pesquisadores têm procurado soluções alternativas. O presente trabalho realizou um estudo sobre a viabilidade técnica e o desempenho de um equipamento (patenteado como Girassol®) que emprega a fibra óptica para iluminação natural em ambientes que não recebem luz direta, ainda no formato de um protótipo. O aspecto da sustentabilidade visando a economia de energia através da captação solar e condução da luz através dos cabos de fibra óptica até a célula-teste foi analisado. A questão principal a ser observada foi quão eficiente pode ser o sistema de iluminação com fibra óptica utilizando a captação de luz solar. Para isso foram feitos testes do equipamento em um ambiente previamente construído, denominado célula teste, com área aproximada de 4 m². Foi medida a quantidade de luminância e iluminâncias que chegam ao ambiente da célula-teste. Esta pesquisa visou conhecer a tecnologia atual existente no mercado comercial nacional e internacional e a tecnologia do equipamento desenvolvido no Brasil. A pesquisa considerou como a hipótese de que a correta captação de luz solar aliada à correta condução através dos cabos de fibra óptica, que permite com que a iluminação em ambientes iluminados somente com luz artificial passem a ser iluminados com a luz natural conduzida pelos cabos de fibra óptica, pode colaborar para a qualidade da luz para seus usuários e para a eficiência energética da edificação. A metodologia desenvolvida foi através de medições uma vez por semana, durante um ano, três vezes ao dia (às 9, 12 e 15 horas) comprovando a eficiência do equipamento na diversidade de situações impostas por intempéries. Os resultados obtidos comprovaram a viabilidade técnica e o bom desempenho do equipamento confirmando sua potencialidade de contribuição para a eficiência energética quando implantado. Este estudo contribuiu para a comunidade acadêmica por sua interdisciplinaridade e por apresentar avanço em conhecimentos técnicos e teóricos sobre o melhor aproveitamento da luz natural para obtenção de eficiência energética, tema de grande interesse frente a questões estéticas, ambientais e de saúde.\" / The lighting of spaces has been observed for millennia, since the use of fire up the latest lighting technologies. Lighting environments increasingly looking for efficiency and energy being a reason for constant research of the researchers. Currently, the major problem faced by artificial lighting is the cost of electrical energy and that is why several researchers have sought solutions alternatives. The present work carried out a study on the viability technique and the performance of an equipment (patented as Girassol®) that fiber optics for natural lighting in receive direct light, still in the shape of a prototype. The sustainability to save energy through solar and conduction of light through fiber optic cables to the test cell It was analyzed. The main issue to note was how efficient can be the lighting system with fiber optics using the capture of sunlight. For this, equipment tests were performed in a previously constructed environment, called the test cell, with an approximate area of 4sqm. The amount of luminance and illuminances that reached the environment of the test cell. This research aimed to know the technology existing in the national and international commercial market and the equipment technology developed in Brazil. The research considered as the hypothesis that the correct capture of sunlight allied to the correct through fiber optic cables, which allows illuminated areas with only artificial light be illuminated with natural light led by fiber optic cables, can collaborate on the quality of light for its users and for the energy efficiency of the building. The methodology developed was through measurements once a week, for one year, three times (9 am, 12 pm, and 3 pm), demonstrating the efficiency of the equipment in the diversity of situations imposed by inclement weather. The obtained results proved the technical feasibility and good performance of the equipment confirming its potential contribution to efficiency when implanted. This study contributed to the its interdisciplinarity and to present advances in technicians and theorists about the best use of natural light to obtain energy efficiency, a subject of great interest in aesthetic, environmental and health matters.

This dissertation describes the work conducted on error analysis for Brillouin Optical Time Domain Reflectometry (BOTDR), a distributed strain sensing technology used for monitoring the structural performance of infrastructures. Although BOTDR has been recently applied to many infrastructure monitoring applications, its measurement error has not yet been thoroughly investigated. The challenge to accurately monitor structures using BOTDR sensors lies in the fact that the measurement error is dependent on the noise and the spatial resolution of the sensor as well as the non-uniformity of the monitored infrastructure strain conditions. To improve the reliability of this technology, measurement errors (including precision error and systematic error) need to be carefully investigated through fundamental analysis, lab testing, numerical modelling, and real site monitoring verification. The relationship between measurement error and sensor characteristics is firstly studied experimentally and theoretically. In the lab, different types of sensing cables are compared with regard to their measurement errors. Influences of factors including fibre diameters, polarization and cable jacket on measurement error are characterized. Based on experimental characterization results, an optics model is constructed to simulate the Brillouin back scattering process. The basic principle behind this model is the convolution between the injected pulse and the intrinsic Brillouin spectrum. Using this model, parametric studies are conducted to theoretically investigate the impacts of noise, frequency step and spectrum bandwidth on final strain measurement error. The measurement precision and systematic error are then investigated numerically and experimentally. Measurement results of field sites with installed optical fibres displayed that a more complicated strain profile leads to a larger measurement error. Through extensive experimental and numerical verifications using a Brillouin Optical Time Domain Reflectometry (BOTDR), the dependence of precision error and systematic error on input strain were then characterized in the laboratory and the results indicated that a) the measurement precision error can be predicted using analyzer frequency resolution and the location determination error and b) the characteristics of the measurement systematic error can be described using the error to strain gradient curve. This is significant because for current data interpretation process, data quality is supposed to be constant along the fibre although the monitored strain for most of the site cases is non-uniformly distributed, which is verified in this thesis leading to a varying data quality. A novel data quality quantification method is therefore proposed as a function of the measured strain shape. Although BOTDR has been extensively applied in infrastructure monitoring in the past decade, their data interpretation has been proven to be nontrivial, due to the nature of field monitoring. Based on the measurement precision and systematic error characterization results, a novel data interpretation methodology is constructed using the regularization decomposing method, taking advantages of the measured data quality. Experimental results indicate that this algorithm can be applied to various strain shapes and levels, and the accuracy of the reconstructed strain can be greatly improved. The developed algorithm is finally applied to real site applications where BOTDR sensing cables were implemented in two load bearing piles to monitor the construction loading and ground heaving processes.

<p>Optical fibre sensors can be used to measure a wide variety of properties. In some cases they have replaced conventional electronic sensors due to their possibility of performing measurements in environments suffering from electromagnetic disturbance, or in harsh environments where electronics cannot survive. In other cases they have had less success mainly due to the higher cost involved in fibre-optic sensor systems. Intensity modulated fibre-optic sensors normally require only low-cost monitoring systems principally based on light emitting diodes and photo diodes. The sensor principle itself is very simple when based on coupling between fibres, and coupling based intensity modulated sensors have found applications over a long time, mainly within position and vibration sensing. In this thesis new concepts and applications for intensity modulated fibre-optic sensors based on coupling between fibres are presented. From a low-cost and standard component perspective alternative designs are proposed and analyzed in order to find improved performance. The development of a sensor for an industrial temperature sensing application, involving aspects on multiplexing and fibre network installation, is presented. Optical time domain reflectometry (OTDR) is suggested as an efficient technique for multiplexing several coupling based sensors, and sensor network installation with blown fibre in micro ducts is proposed as a flexible and cost-efficient alternative to traditional cabling. A new sensor configuration using a fibre to a multicore fibre coupling and an image sensor readout system is proposed. With this system a high-performance sensor setup with a large measurement range can be realised without the need for precise fibre alignment often needed in coupling based sensors involving fibres with small cores. The system performance is analyzed theoretically with complete system simulations on different setups. An experimental setup is made based on standard fibre and image acquisition components, and differences from the theoretical performance are analyzed. It is shown that sub-µm accuracy should be possible to obtain, being the theoretical limit, and it is further suggested that the experimental performance is mainly related to two error sources: core position instability and differences between the real and the expected optical power distribution. Methods to minimize the experimental error are proposed and evaluated.</p>

Optical fibre sensors can be used to measure a wide variety of properties. In some cases they have replaced conventional electronic sensors due to their possibility of performing measurements in environments suffering from electromagnetic disturbance, or in harsh environments where electronics cannot survive. In other cases they have had less success mainly due to the higher cost involved in fibre-optic sensor systems. Intensity modulated fibre-optic sensors normally require only low-cost monitoring systems principally based on light emitting diodes and photo diodes. The sensor principle itself is very simple when based on coupling between fibres, and coupling based intensity modulated sensors have found applications over a long time, mainly within position and vibration sensing. In this thesis new concepts and applications for intensity modulated fibre-optic sensors based on coupling between fibres are presented. From a low-cost and standard component perspective alternative designs are proposed and analyzed in order to find improved performance. The development of a sensor for an industrial temperature sensing application, involving aspects on multiplexing and fibre network installation, is presented. Optical time domain reflectometry (OTDR) is suggested as an efficient technique for multiplexing several coupling based sensors, and sensor network installation with blown fibre in micro ducts is proposed as a flexible and cost-efficient alternative to traditional cabling. A new sensor configuration using a fibre to a multicore fibre coupling and an image sensor readout system is proposed. With this system a high-performance sensor setup with a large measurement range can be realised without the need for precise fibre alignment often needed in coupling based sensors involving fibres with small cores. The system performance is analyzed theoretically with complete system simulations on different setups. An experimental setup is made based on standard fibre and image acquisition components, and differences from the theoretical performance are analyzed. It is shown that sub-µm accuracy should be possible to obtain, being the theoretical limit, and it is further suggested that the experimental performance is mainly related to two error sources: core position instability and differences between the real and the expected optical power distribution. Methods to minimize the experimental error are proposed and evaluated.

<p>Structural Health Monitoring (SHM) is a helpful tool for engineers in order to control and verify the structural behaviour. SHM also guides the engineers and owners of structures in decision making concerning the maintenance, economy and safety of structures. Sweden has not a very sever tradition in monitoring, as countries with strong seismic and/or aerodynamic activities. Anyway, several large scale monitoring projects have taken place in recent years and SHM is slowly making entrance as an essential implement in managing structures by engineers as well as owners.</p><p>This licentiate thesis presents a state-of-the art-review of health monitoring activities and over sensory technologies for monitoring infrastructure constructions like bridges, dams, off-shore platforms, historical monuments etc. related to civil engineering. The fibre optic equipment is presented with special consideration.</p><p>The permanent monitoring system of the New Årsta Bridge consists of 40 fibre optic sensors, 20 strain transducers, 9 thermocouples, 6 accelerometers and one LVDT. The aims of the static study are: to control the maximal strains and stresses; to detect cracking in the structure; to report strain changes under construction, testing period and in the coming 10 years; and to compare conventional system with fibre optic system.</p><p>The system installation started in January 2003 and was completed October 2003. The measurements took place from the very beginning and are suppose to continue for at least 10 years of operation. At the construction phase the measurements were performed manually and later on automatically through broad band connection between the office and central data acquisition systems located inside the bridge.</p><p>The monitoring project of the New Årsta Railway Bridge is described from the construction phase to the testing phase of the finished bridge. Results of the recorded statistical data, crack detection and loading test are presented and a comparison between traditional techniques like strain transducers and fibre optic sensors is done.</p><p>Various subjects around monitoring and sensor technologies that were found under the project are brought up in order to give the reader a good understanding, as well of the topics, techniques and of the bridge. Example of few applications is given with the aim of a deeper insight into monitoring related issues.</p>

This research investigates the collection of concentrating solar energy and its transmission through optical fibres for use in high temperature applications such as lunar in-situ resource utilisation (ISRU) programmes, solar power generation and solar surgery. A prototype collector, known as the Fibre Optic Concentrating Utilisation System (FOCUS), has been developed and is capable of delivering high energy fluxes to a remote target. Salient performance results include flux concentrations approaching 1000 suns with an overall optical efficiency of 13%, measured from the inlet of the collector to the fibre outlet. The system comprises a novel solar concentrator designed to inject solar energy into a four metre long fibre optic cable for the transmission of light to the target. A nonimaging reflective lens in the form of a 600 mm diameter ring array concentrator was chosen for the collection of solar energy. Advantageous characteristics over the more common parabolic dish are its rearward focusing capacity and single stage reflection. The ring array comprises a nested set of paraboloidal elements constructed using composite material techniques to demonstrate a low-cost, effective fabrication process. At concentrator focus, a fibre optic cable of numerical aperture 0.37 is positioned to transport the highly concentrated energy away from the collector. The cable is treated to withstand UV exposure and high solar energy flux, and allows flexibility for target positioning. A computational analysis of the optical system was performed using ray tracing software, from which a predictive model of concentrator performance was developed to compare with experimental results. Performance testing of FOCUS was conducted using energy balance principles in conjunction with a flat plate calorimeter. Temperatures approaching 1500°C and flux levels in the region of 1800 suns were achieved before injection to the cable, demonstrating the optical system's suitability for use in high flux applications. During testing, peak temperatures exceeding 900°C were achieved at the remote target with a measured flux of 104 W/cm2 at the cable outlet. The predicted optical efficiency was 22%, indicating that further refinements to the ray trace model are necessary, specifically with regard to losses at the inlet to the cable. FOCUS was able to demonstrate its usefulness as a test bed for lunar in-situ resource utilisation technologies by successfully melting a lunar soil simulant. The system permits further terrestrial-based ISRU research, such as oxygen production from regolith and the fabrication of structural elements from lunar soil. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

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