Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Ray T. Chen. Vita. Includes bibliographical references.

Thesis (Ph. D.)--Miami University, Dept. of Chemistry and Biochemistry, 2006. / Title from first page of PDF document. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: During the course of the CSIR’s research into the characterisation of explosive sources to devise methods of active intervention against threats, the need has arisen to research a particular means of early identification of the threat, which is the intense light flash during the threat detonation. For this purpose, a low cost rugged fast optical sensor was sought, since the application thereof would imply possible destruction, especially if integrated into an active intervention system later on. Given the average time of about 1ms available for intervention, it is clear that the active intervention system needs to operate within that period, hence the interest in the characteristic light emission of detonations in the pre-millisecond time frame. It was thought that by characterising this emitted light in terms of wavelength (temperature) and amplitude (and maybe other unique phenomena), the size of the threat could be determined and logic decisions derived therefrom. Needless to say, the environment in which the detonation light emission sensor is to operate, is extremely hostile in terms of shock, dust, flying debris, fast rise time of the explosive event, and Electro-magnetic Interference ( EMI) caused by the detonation itself. It must be noted that the light sensor research was driven by the outcome of research tests performed in aid of the development of an active intervention system. During this research the possibility of using commercially available low cost optical detectors at room temperature in combination with cost effective narrow band pass op- tical filters for the relative measurement of the light emission at discrete wavelengths during explosive detonation events were investigated. In 2006, not much applicable lit- erature could be found on this subject, hence the educated “shot-in-the-dark” approach then, which, by a systematic approach of explosive tests and continuous evaluation up to 2011, led to a surprisingly simple and robust low cost optical sensor. The research commenced with a range of optical detector elements selected for their responsivity and bandwidth in the optical spectrum of interest; the optical filtering by means of the recording of the emitted light signal during scaled down explosive tests at the Blast Impact Survivability Research Unit (BISRU) at the University of Cape Town. These tests were followed by full-scale tests at DBEL, and confirmed the findings at BISRU that the light emissions at the longer wavelengths (>2 m) manifest themselves too late for use within the intervention time frame. It was therefore decided to concentrate on the ultra-violet (UV) to near infra-red (NIR) spectrum of the emitted light for further full scale tests, since these discrete spectra showed the most promise for characterisa- tion of the emitted light. During this period a robust sensor housing with detector and filter mounts was designed for protection against blast shock and EMI. During the following years, certain types of optical detectors that were used during previous tests were eliminated according to results obtained, and more discrete narrow band pass filters added in the visible to NIR spectrum. A dedicated fast instrumen- tation amplifier (bandwidth > 1MHz and selectable gain up to 40dB) was developed to amplify weak signals (mainly caused by the heavy load in the detector circuit to improve rise times). However, the emission of light per wavelength in this region was measured to be relatively strong, and actually not as fast as was anticipated. This meant that the load resistor value of the detector element could be increased without affecting the signal negatively (bandwidth sufficient), thus adding to the amplitude of the signal to such a point that amplification in a 10m to 30 meter stand-off scenario was no longer needed. This culminated in an unamplified universal detector element being used with various narrow band pass filters up to 1 m, integrated as a very robust analog sensor at a discrete wavelength, and facilitating the direct comparison of light amplitude/relative intensity of the detonation at discrete spectral points. The sensor was employed in the field at various full scale explosive tests at DBEL, which led to the capture of a vast amount of light emitted data for different types of explosives, at various distances from the detonation, and of varying mass. Analysis of this data showed that the broadband light intensity of the emitted light scales to the explosive mass1/3 (as published by FJ Mostert and M Olivier in the Journal for Applied Physics, October 2011). Further analysis also confirmed the attenuation of the emitted light intensity by the square of the distance. Besides the aforesaid, various other key inputs to a possible active intervention algorithm have been identified. These findings are inputs to the determination of i.a. the detonation threat size, a vital component in the active intervention algorithm. The results of these experiments confirmed that the final low cost analog sensor can measure relative light emission at discrete wavelengths from detonation of explosives in the very early stages of development, and that the sensor has many other applications in the detonics research fields as well. / AFRIKAANSE OPSOMMING: Gedurende die WNNR se navorsing om detonerende bronne te karakteriseer ten einde aktiewe teenmaatreëls daar te stel, het die behoefte na vore gekom om die intense ligflits van ’n detonasie te ondersoek en te karakteriseer. Vir hierdie doel is ’n lae koste ligsensor benodig, synde die uiteindelike aanwending van hierdie ligsensor die vernietiging daarvan sou beteken, aldus die lae koste vereiste. Gegewe die kort tydsduur van die detonasie (’n paar millisekondes), is dit duidelik dat die ligflits karakerisering voor 1ms moet geskied, en daarom moet die ligsensor ook baie vinnig reageer om insette te lewer tot ’n aktiewe teenmaatreëlstelsel. Daar moet op gelet word dat die ligsensor se ontwikkeling uitkomsgedrewe was deur die navorsingstoetse om ’n aktiewe teenmaatreëlstelsel daar te stel. Een van die insette tot so ’n aktiewe teenmaatreëlstelsel is die grootte van die bedreiging: deur die ligflits te karakteriseer met die lae koste ligsensors t.o.v. golflengte, ligamplitude en moontlik ander verskynsels, kan bv. die massa inset verkry word wat nodig is vir die teenmaatreël algoritme. Die omgewing waarin die ligsensor moet funksioneer is baie onvriendelik i.t.v. skok, stof, vlieënde partikels en elektromagnetiese steurings, en sou daarteen beskerm moes word. Gedurende die navoring om so ’n ligsensor te ontwikkel (samelopend met die teen- maatreël navorsing), is kommersiële kamertemperatuur detektors oorweeg en aange- wend, in samewerking met nouband optiese filters. Die doel was om die ligopbrengs per golflengte te karakteriseer m.b.t. die plofstof massa, plofstof tipe en geometrie, en die afstand vanaf die detonasie. Bitter min literatuur oor die ligmeting van detonasies is aanvanklik gevind, aldus is ’n basislyn daargestel en deur sistematiese toetsing, ontleding en verbetering voortgegaan met die navorsing. Dit het gelei tot ’n verrassend eenvoudige en verharde lae koste ligsensor, wat deur meting sleutelinsette kon lewer tot die gesogte aktiewe teenmaatreël algoritme. Kommersiële detektors en nouband optiese filters is uitgesoek na aanleiding van hul prys en prestasie, en waar nodig, is versterking van die seine aangebring. Verskeie toetse met plofstof (op klein en groot skaal) is uitgevoer, waartydens ligmeting by spesifieke golflengtes opgeneem is. Analise van hierdie data het getoon dat die langer golflengtes (>2 m) se verskyning te laat is vir insluiting in die teenmaatreël algoritme, en is dus geleidelik (of sistematies) uitgeskakel. Die klem het geskuif na die detonasie liguitsetting in die UV tot naby infrarooi spektrum, wat nuwe detektors en filters tot gevolg gehad het (uitkoms gebasseerde navorsing). In die proses is ’n instrumentasie versterker ontwerp en gebou, vir buffering en versterking van seine hoër as 1 MHz met ’n selekteerbare aanwins van tot 40dB. Toetse met volskaalse ladings het egter getoon dat die liguitset besonder sterk is in die UV tot naby infrarooi spektrum, en ’n onversterkte ligsensor is aldus op die proef gestel. Hierdie proeflopie het getoon dat die onversterkte ligsensor besonder goed funksioneer op afstande tot en met 30m, en daar is op hierdie model voortgebou. Die verharde onversterkte ligsensor is aangewend in verskeie verdere volskaalse plofstof toetse, en het data gelewer t.o.v. detonasie liguitstraling by spesifieke golflengtes vir tipes plofstof, plofstof massas, plofstof geometrie en afstande vanaf die detonasie. Analise van hierdie data het getoon dat breëband liguitsetting se intensiteit skaal met die plofstof massa1=3 (gepubliseer as ’n artikel deur FJ Mostert en M Olivier in die Journal of Applied Physics’ - Oktober 2011). Verdere analise het verskeie sleutelinsette tot ’n aktiewe teenmaatreël algoritme geïdentifiseer. Die uitkoms van hierdie eksperimentele navorsing het getoon dat die lae koste lig- sensor relatiewe liguitsetting van ’n detonasie by gekose golflengtes vinnig kan meet in die baie vroeë stadia van die detonasie. Buiten dit, het die sensor verskeie ander nuttige aanwending in die detonasie navorsingsveld.

Neste trabalho foi inferida a vazão de um fluido que escoava em um tubo de cobre através do uso da termometria em diferentes regimes de escoamento, com o uso de sensores óticos de temperatura baseados em redes de Bragg escritas em fibras óticas (FBG). Foi utilizado um processo de medição não-intrusivo de vazão através do uso da termometria o qual consiste no monitoramento da temperatura em dois pontos fixos, com uma distância conhecida (d), na parede externa do tubo. Além dos sensores óticos de temperatura foram utilizados sensores comerciais de temperatura, termopares, com a intenção de comparar os resultados obtidos experimentalmente. No experimento o fluido estará escoando com uma temperatura T1, e em determinado tempo será liberado um pequeno volume de fluido com temperatura T2, onde T2 > T1, simulando um pulso térmico. É monitorada a evolução temporal do pulso térmico e anotado o tempo de trânsito (t) entre os dois sensores de temperatura. Com o valor da distância (d) e o tempo de trânsito (t) obtemos a velocidade média de escoamento (v). De posse da (v) e área de seção transversal do tubo (A) podemos inferir a vazão. A técnica de medição não-intrusiva de vazão através do uso da termometria foi testada para diferentes regimes de escoamento: laminar, transição e turbulento. Foram comparados os valores medidos da vazão mássica do sistema com os valores obtidos experimentalmente para os sensores comerciais e redes de Bragg. Para o regime turbulento a exatidão de medição da velocidade de escoamento do fluido foi de 0,75 para os sensores óticos e 0,60 para os sensores comerciais. No caso do regime de transição a exatidão na medida foi de 0,90 para o sensor ótico e 0,69 para os sensores comerciais. Finalmente para o regime laminar a exatidão nas medidas foram [sic] de 0,98 para os sensores ótico [sic] e 0,76 para os sensores comerciais. / In this work we inferred a fluid flow seeping from a cooper pipe through thermometers scheme in different flows, through the use of optical sensors based on temperature Bragg Gratings written in optical fiber (FBG). We used a non-intruse measurement process through the use of thermometry, which consists of monitoring the temperature at two fixed points with a know distance (d) on the outer wall of the tube. Besides the optical sensors of temperature, sensors were used for commercial temperature, thermocouples, with the objective of comparing the results obtained experimentally. In the experiment, the fluid is flowing at a temperature T1, and will be released at any given time a small volume of fluid with temperature T2, were T2 > T1, simulating a thermal pulse. It's monitored the evolution of the thermal pulse and noted the transit time (t) between the two temperature sensors. With the value of distance (d) and transit time (t) we obtain the average velocity of flow (v). Tenure velocity (v) and the tube transversal sectional area (A) we can infer the non-intrusive measurement technique flow. The flow though the use of thermometry was tested for different flow regimes: laminar, transitional and turbulent. We compared the values measured with the mass flow of the system with the experimental values for the sensors and commercial FBG's. In the turbulent the accuracy of measuring the speed and fluid flow was 0.75 to 0.60 optical sensors and sensor for commercial purposes. Finally for the laminar accuracy in the measurements were 0.98 optical sensors and 0.76 for commercial sensors.

Este trabalho apresenta o desenvolvimento de membranas sensoras para a detecção de oxigênio gasoso através da fosforescência resolvida no tempo, além de descrever um sistema de medição para avaliação de desempenho destes elementos. Os transdutores são formados a partir da imobilização em matrizes poliméricas, de poli(cloreto de vinila) e poliestireno, das seguintes metaloporfirinas de paládio: Coproporfirina I, Mesoporfirina IX, Deuteroporfirina IX e meso-Tetrapenta(fluorofenil)porfirina. O feixe de excitação das membranas é proveniente de um LED violeta, sendo que a fosforescência emitida pelos luminóforos é detectada por uma miniválvula fotomultiplicadora. Relatam-se a produção das membranas sensoras e seus principais parâmetros, como curvas de calibração, envelhecimento, tempos de resposta e fotoestabilidade. As membranas de PVC apresentaram sensibilidade moderada, com razões τ0/τar próximas a 4, permitindo medições com uma resolução média de 10 μs.%-1 para a faixa de 16% de O2 a ar. No caso das membranas em PS, as razões τ0/τar chegam a atingir 50, com resoluções acima de 900 μs.%-1 para concentrações entre 0% e 1% de O2; no entanto, mostram-se de difícil aplicação para concentrações acima de 16%. De modo geral, os elementos produzidos apresentaram tempos de resposta inferiores a 1 s. Assim, possíveis aplicações para estes dispositivos incluem o monitoramento da respiração humana e a detecção de oxigênio residual (e.g.: embalagens alimentícias). Evidenciou-se ainda, uma elevada fotodegradação das membranas perante a excitação na banda B, sendo que o indicador PdTFPP mostrou-se superior aos demais quanto à fotoestabilidade. / This research presents the development of sensing membranes for detection of gaseous oxygen by time-resolved phosphorescence as well as the description of a measurement system for performance evaluation of those elements. The transducers are formed by the immobilisation of palladium metalloporphyrins probes (coproporphyrin I, mesoporphyrin IX, deuteroporphyrin IX and meso-Tetrapenta(fluorophenyl) porphyrin) in polymers of poly(vinyl chloride) and polystyrene. A light emitting diode is employed for dye excitation and the phosphorescence is detected by a miniature photomultiplier tube. The production of the membranes as well as their practical parameters such as calibration curves, ageing, response times and light stability are reported. PVC membranes exhibited moderate sensitivity, with ratios τ0/τair near 4, enabling measurements with a resolution of 10 μs.%-1 for the range of 16% of O2 up to 20,5%. For PS membranes, the ratios τ0/τair reached up to 50, with resolutions of up to 900 μs.%-1 considering concentrations between 0% and 1% of O2, however they proved to be of difficult application for concentrations above 16%. Some sensor membranes showed response times below 1 s. Thus, possible applications for these devices include monitoring of human respiration and detection of residual oxygen (e.g.: food packaging). Also, it was observed a high signal degradation when the dyes are excited around their B bands. PdTFPP dye presented more light stability than the others.

Este trabalho descreve a produção de redes de Bragg e de período longo em fibras óticas, e a caracterização destas redes como dispositivos sensores na detecção de hidrocarbonetos que fluem em polidutos, bem como na monitoração de sua temperatura. O trabalho foi realizado no Laboratório de Laser da UTFPR. As redes de período longo foram produzidas pela aplicação ponto-a-ponto do arco elétrico de uma máquina de emendas de fibras óticas e caracterizadas como sensores de índices de refração de meios exteriores à fibra. Essa caracterização foi realizada usando diferentes amostras de fluidos tais como, álcool, gasolina, aguarrás, tíner, querosene e nafta. O maior deslocamento em comprimento de onda apresentado pela rede foi de 15,57 nm na presença do querosene. A sensibilidade média ao índice de refração da rede foi 2,6x10-6 pm-1 para a região compreendida entre 1,432 (tíner) e 1,448 (querosene). Esta sensibilidade resulta em uma mínima variação de índice de refração de 2,6x10-5 que pode ser medida por um analisador de espectros óticos com precisão em comprimento de onda de ± 5pm. O tempo de resposta do sensor foi da ordem de 3 segundos. As redes de Bragg foram caracterizadas como dispositivo sensor de temperatura dos fluidos. As redes de Bragg foram produzidas inicialmente em fibras SMF hidrogenadas e posteriormente em fibras fotossensíveis, utilizando a técnica de escrita interferométrica com máscara de fase e laser ultravioleta. Os dispositivos foram caracterizados como sensor de temperatura, tendo sido feito um estudo para estabilização térmica dos mesmos. A sensibilidade das redes variou desde 10,2 nm/ºC até 11,4 nm/ºC. A precisão deste tipo de sensor está intimamente relacionada com a largura de banda espectral da rede, portanto, um sistema de gravação utilizando a técnica de escrita com máscara de fase e laser UV foi implementado, tornando possível a escrita de redes mais longas com menor largura de banda. / This work describes the production of fiber Bragg gratings and long period gratings in optical fibers and their characterization as sensors devices in the detection of hydrocarbons that flow in pipelines, as well as its temperature measurement. The work was accomplished at Laser Laboratory of UTFPR. The long period gratings were produced using the point-to-point electric arc discharge technique from a splice machine and characterized as refractive index sensors of the fiber surroundings. The characterization was accomplished using different samples of alcohol, gasoline, turpentine, thinner, kerosene and naphtha. The biggest wavelength shift presented by the grating was 15.57 nm in the presence of the kerosene. The average refractive index grating sensitivity was 2.6x10-6 pm-1 in the range from 1.432 (thinner) to 1.448 (kerosene). This sensitivity relates to a smallest refractive index variation of 2.6x10-5 that can be measured, for an optical spectrum analizer with wavelength precision of ± 5 pm. The response time of the sensor was 3 seconds for the different samples used. The fiber Bragg gratings were characterized as temperature sensor devices of the samples. The gratings were produced both in SMF hydrogenated and photosensitive fibers, using an ultraviolet laser and a phase mask interferometer. The devices were characterized as temperature sensors, and a study for thermal stabilization of them was carried out. The obtained sensor sensitivity ranged from 10.2 nm/ºC up to 11.4 nm/ºC. As the precision of this type of sensor is related to the bandwidth of the fiber Bragg grating, a writing system technique based on a phase mask and an UV laser was implemented, making possible the writing of long and narrow bandwidth gratings.

Este trabalho apresenta a gravação e caracterização de redes de Bragg em fibras óticas (FBGs), com comprimentos de onda otimizados para a banda do visível, a partir de pulsos de laser femtossegundo em UV ajustados por um oscilador paramétrico ótico (OPO – optical parametric oscillator). Para tal propósito foi usado o método de inscrição direta sob máscara de fase, tendo como base diferentes fibras óticas previamente hidrogenadas com vista a incrementar a sua fotossensibilidade. Durante o processo de gravação dos sensores a fibra ótica, as FBGs foram monitoradas espectralmente em reflexão e posteriormente caracterizados em temperatura e deformação longitudinal, para a análise dos seus coeficientes de sensibilidades; seus principais parâmetros pós-gravação foram analisados comparativamente em relação às redes de Bragg funcionais na faixa espectral do infravermelho. / In this work, a visible wavelength fiber Bragg gratings (FBGs) were produced using ultrafast laser pulses adjusted with an OPO (optical parametric oscillator) to 248 nm UV femtosecond laser source. For that purpose it was employed the normal phase-mask method and different fibers loaded with hydrogen previously, in order to increase its photosensitivity. During de process the spectral characteristics were analyzed in terms of reflection as well as temperature and longitudinal deformations were made to analyze the post inscription main parameters of sensitivity comparing with IR spectral range produced FBGs.

CAPES; FINEP; Fundação Araucária / O biodiesel desponta como uma das mais promissoras alternativas ambientalmente corretas aos combustíveis fósseis. A falta de um sensor apropriado para medir sua quantidade na mistura petrodiesel-biodiesel surge como uma grande oportunidade de pesquisa. Este trabalho apresenta um estudo sobre a fabricação e a caracterização de dispositivos intrínsecos a fibra ótica com o intuito de constituir um transdutor capaz de determinar a concentração de biodiesel presente em misturas petrodiesel-biodiesel. A gravação destes dispositivos, as redes de período longo, foi feita por meio da técnica de incidência lateral ponto-a-ponto de radiação ultravioleta oriunda de um laser Excímero de KrF operando em 248 nm. Na avaliação da sensibilidade ao índice de refração do meio externo às redes foram utilizados fluídos com índices de refração entre 1,00 e 1,47. Através de um processo de espelhamento aplicado na extremidade das fibras se obtém um tipo de dispositivo conhecido como CLPG. É feita a análise para a imersão da rede e da cavidade no mensurando, só da cavidade, assim como de porções da cavidade. Os dados mais promissores foram conseguidos com pequena porção da cavidade imersa em mistura petrodiesel-biodiesel, um caso em que é possível medir o índice de refração com relação à intensidade do sinal e inferir a proporção de cada componente na mistura. Ao final os parâmetros metrológicos do sistema foram apurados indicando boa confiabilidade, principalmente para a faixa de misturas B60 a B100. / The Biodiesel presents itself as one of the most promising environment friendly alternatives to the use of fossil fuels. The lack of a suitable sensor to measure the quality of biodiesel in the petrodiesel-biodiesel blend consists a great research opportunity. This work presents the implementation of a recording system of long period gratings, through the point-by-point technique of lateral exposure to ultraviolet radiation from a KrF Excimer laser operating at 248 nm, at Laboratório de Laser of UTFPR with the goal of producing a transducer that can quantify the proportion of petrodiesel and biodiesel blends through the changes in the refraction index. To evaluate the gratings sensitivity to the refraction index of the external environment, several liquids were used with refraction index ranging from 1.00 to 1.47. Through a reflective coating applied to the extremity of the fiber a kind of device usually called CLPG is obtained. A detail study of samples in contact with both the cavity and the grating, only with the cavity and finally with submerged portions of the cavity. The case of only a small party of the cavity immersed in the substance allows the measure of the refractive index related to signal strength. Finally, the metrological parameters of the system were evaluated indicating a good confiability, mainly for the B60 e B100 blends.

CNPQ; Fundação Araucária; PETROBRÁS / Neste trabalho é apresentado um estudo sobre a aplicabilidade de redes de período longo e estruturas de redes de período longo, gravadas em fibra ótica de sílica, quando empregadas como transdutores de índice de refração para avaliar biodiesel e os óleos de origem desses biocombustíveis. Como amostras, foram utilizados óleos de soja, de fritura e de girassol, biodiesel de óleo de soja e biodiesel de óleo de girassol. Os experimentos foram realizados utilizando uma rede de período longo convencional e uma estrutura de rede de período longo, chamada de rede de período longo em cascata, na qual uma rede período longo é empregada numa configuração interferométrica similar a um interferômetro de Michelson. Inicialmente, foram analisadas as diversas amostras de óleo e biodiesel em temperatura ambiente. Os resultados mostraram que quando os dispositivos são imersos nas diferentes amostras, que possuem índice de refração igual ou maior do que o da casca da fibra ótica, as condições de guiamento da luz não permitem mais que estes possam ser usados como transdutores de índice de refração. Entretanto, no caso da rede de período longo em cascata, quando somente a cavidade do interferômetro de Michelson, ou parte desta cavidade, é colocada em contato com as amostras, o dispositivo se mostra uma promissora ferramenta para verificação da qualidade do biodiesel. Ainda na tentativa de melhorar o desempenho da rede de período longo em cascata, as amostras foram aquecidas com o objetivo de alterar o seu índice de refração, tornando-o menor do que o índice de refração da casca da fibra. Os resultados mostraram que o aumento sistemático da temperatura da amostra constitui um eficiente artifício para análise de substância cujos índices de refração, à temperatura ambiente, são iguais ou maiores que o da casca da fibra ótica. / This work presents a study of the applicability of long period gratings and long period gratings structures, written in silica optical fiber, when they are employed as a transducer of refractive index to analyze the biodiesel and their original oils. As samples were used: soybean oil, fried oil, sunflower oil, soybean oil biodiesel and biodiesel from sunflower oil. The experiments were performed using a conventional long period grating and a long period grating structure named as cascaded long period grating, in which a long period grating is employed on an interferometric configuration similar to a Michelson interferometer. Initially, were analyzed several samples of oil and biodiesel at room temperature. The results showed that when the devices were immersed in the different samples, which have refractive index equal or higher than that of the optical fiber cladding, the guiding light conditions no longer allow these devices for the use as a refractive index transducer. However, if the cascaded long period grating is used, when only the cavity of the Michelson interferometer or part of this cavity is placed in contact with samples, the devide shows a promising tool for checking the quality of biodiesel. Still trying to improve the performance of the cascade long period gratings, the samples were heated in order to modify their refractive index, making them smaller than the refractive index of the fiber cladding. The results showed that the systematic increase of the sample temperature is an efficient artifice for analysis of substances which refractive index, at room temperature, are equal of higher than that of the optical fiber cladding.