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Graaf, Menno Wouter de. "Sensor-guided robotic laser welding." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/58092.
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Mandal, Jharna. "Fibre laser development for sensor applications." Thesis, City University London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435942.
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Ayyalasomayajula, Narasimha Rao. "Nd:YAG mini slab laser hybrid integration and Raman sensor application /." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10437.
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Thesis (Ph. D.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains xiv, 170 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 159-164).
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Diwei, He M. Res. "Full field laser doppler blood flow sensor." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523084.
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Zabit, Usman. "Optimisation of a self-mixing laser displacement sensor." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0129/document.
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L'interférométrie à rétro-injection optique, également connu sous le nom de Self-Mixing, permet de concevoir des capteurs qui sont compacts, auto-alignés et sans contact. Dans ce phénomène, une partie du faisceau laser de retour réfléchi par la cible rentre dans la cavité active de laser et fait varier ses propriétés spectrales. La diode laser agit alors comme une source de lumière, un microinterféromètre ainsi qu'un détecteur de lumière. Dans cette thèse, un capteur de déplacement, basé sur la rétro-injection optique, a été optimisé de sorte que des mesures précises peuvent être obtenues en temps réel. Le capteur est robuste à la disparition des franges de self-mixing pour des vibrations harmoniques. Il est également capable de s'adapter à un changement dans le régime de feedback optique et peut donc extraire le déplacement dans les cas les plus répandus expérimentalement, à savoir un feedback faible puis modéré. L'utilisation de l'optique adaptative, sous la forme d'une lentille liquide, a également été démontrée pour ce capteur, ce qui nous a permis de maintenir le capteur dans un régime de feedback favorable. L'influence du speckle a également été réduite de telle sorte que le capteur mesure jusqu'à la gamme centimétrique pour des cibles non- oopératives. Une nouvelle technique est également présentée, elle permet de rendre le capteur insensible aux vibrations mécaniques parasites qui fausseraient la mesure pour des conditions industriellesOptical Feedback Interferometry, also known as Self-Mixing, results in compact, selfaligned and contact-less sensors. In this phenomenon, a portion of the laser beam is back reflected from the target and enters the active laser cavity to vary its spectral properties. The laser diode then simultaneously acts as a light source, a micro- nterferometer as well as a light detector. In this thesis, a self-mixing displacement sensor has been optimised so that precise measurement can be obtained in real-time. The sensor is robust to the disappearance of self-mixing fringes for harmonic vibrations. It is also able to auto-adapt itself to a change in the optical feedback regime and so can extract displacement from the weak as well as moderate feedback regime signals. The use of adaptive optics, in the form of a liquid lens, has also been demonstrated for this sensor, which has allowed us to maintain the sensor in a fringe-loss less regime. The influence of speckle has also been reduced so that the sensor can now measure up to the centimetric range for non-cooperative targets. A novel technique has also been presented that makes the sensor insensitive to parasitic mechanical vibrations that would falsify the measurement under industrial conditions
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Iakovou, D. "Sensor development and integration for robotized laser welding." Enschede : University of Twente [Host], 2009. http://doc.utwente.nl/60601.
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Habermann, Danilo. "Detecção e rastreamento de obstáculos com uso de sensor laser de varredura." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-20102010-150541/.
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Este trabalho apresenta um sistema de rastreamento de obstáculos, utilizando sensor laser 2D e filtro de Kalman. Este filtro não é muito eficiente em situações em que ocorrem severas perturbações na posição medida do obstáculo, como, por exemplo, um objeto rastreado passando por trás de uma barreira, interrompendo o feixe de laser por alguns instantes, tornando impossível receber do sensor as informações sobre sua posição. Este trabalho sugere um método de minimizar esse problema com o uso de um algoritmo denominado Corretor de Discrepâncias.An obstacle detection and tracking system using a 2D laser sensor and the Kalman filter is presented. This filter is not very efficient in case of severe disturbances in the measured position of the obstacle, as for instance, when an object being tracked is behind a barrier, thus interrupting the laser beam, making it impossible to receive the sensor information about its position. This work suggests a method to minimize this problem by using an algorithm called Corrector of Discrepancies.
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Rabeendran, Nishanthan. "A Study of Ring Laser Gyroscopes." Thesis, University of Canterbury. Physics and Astronomy, 2008. http://hdl.handle.net/10092/1989.
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This thesis presents a study of a 1.6 metre square, helium-neon based ring laser gyroscope (denoted PR-1). This device is mounted on one of the internal walls of a high rise building. After optimisation a cavity Q of 2.9x10¹¹ and a sensitivity to rotation of approximately 10⁻³ of the background Earth bias was obtained. A detailed investigation of the single mode operating regime and multi-mode thresholds was undertaken and could be well accounted for with a simple model of the gain curves. A key feature of the operation of PR-1 is persistent longitudinal mode hopping. It is shown that by running the laser at selective high powers, one obtains CW mode locked operation thereby negating the influence of mode hopping and allowing for long time data acquisition. PR-1 was used to demonstrate oscillation of the Rutherford building on its second fundamental mode during an earthquake. In a separate investigation, a range of supermirrors were studied to determine the optimum configuration in a 4 by 4 metre ring laser. The set with the highest finesse prevailed despite the comparatively low light levels on the photo detectors. The geometric stability of the lasers was not found to be a significant factor.
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McKie, Andrew Duncan William. "Applications of laser generated ultrasound using an interferometric sensor." Thesis, University of Hull, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327987.
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Hughes, Rowland. "A laser plantar pressure sensor for the diabetic foot." Thesis, University of South Wales, 2000. https://pure.southwales.ac.uk/en/studentthesis/a-laser-plantar-pressure-sensor-for-the-diabetic-foot(521b1dfa-d201-4356-b1d9-74d314b1c360).html.
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This thesis is concerned with the design and building of a foot pressure system capable of measuring the pressure distribution underneath the diabetic foot. The system is developed to have a higher resolution and be more cost-effective than existing commercial systems. The biomechanics of the foot and ankle is explained in detail, providing an explanation for the relationship between high pressures and ulcerations. Various techniques of measuring foot pressure are reviewed, providing a thorough understanding of the advantages and disadvantages of each technique. The system developed uses the technique of interferometry, which is discussed in detail, explaining why the Fizeau Interferometer technique was chosen over other interferometer techniques. A number of materials were tested as to their suitability to be used as the pressure plate in the system i.e. compression/force relationship. From the results 'Perspex' was found to be the most suitable material. Two fringe-processing software packages were tested i.e. Fringe Processor 2 and Fringe Pattern Analysis (FRAN), with Fringe Processor 2 being chosen for this research. A graphical user interface for image display was created in order to display and analyse the various pressure images. Three prototypes were implemented. The first used a variation on the Fizeau interferometer, the second used a variation on the Twyman Green interferometer, whilst the third improved on the use of the variation of the Fizeau interferometer. By analysing the advantages and disadvantages of each prototype, the 3 rd prototype was chosen as the most suitable for achieving the aims and objectives of this research. This prototype was subjected to various tests i.e. resolution, measurable area, repeatability, calibration, short term reliability and sensitivity to heat. Various normal and pathological foot measurements were taken and analysed, and the effectiveness of the image display graphical user interface tested. The main contribution of this thesis is the use of interferometry to measure pressure. This in turn provides a foot pressure system, which has extremely high resolution and accuracy. The simple nature of the new pressure system also means that the entire system is very cost effective.
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Clark, Joanne Louise. "Laser cooling in the condensed phase." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266518.
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Kim, Chan Kyu. "Development of bio-photonic sensor based on laser-induced fluorescence." Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11052007-092200.
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Polreich, Štěpán. "Podélné indexové struktury v optických vláknech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377092.
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This thesis describes basic concepts, principles and properties of optical fibers. Considerable part is devoted to fiber gratings that are created by a change in the refractive index in the optical fiber core. In this work is described description, principle, method od production and distribution of gratings on Bragg gratings, gratings with long period and chirped gratings. In this thesis are also presented different types of lasers and their advantages over other lasers. A large part deals with the description of the femtosecond laser, with which the structures will be later made into the material. In addition, the laser modes are differentiated, this is a mode of micro-machining and modification or a change in refractive index of the material. The last part deals with change the refractive index in planar technology, the creation of a groove for fastening the fiber and attempts to write the gratings into the optical fiber. Created fiber sensor are tested for temperature and tensile changes. Finally, the practical use of sensors made by femtosecond laser and the advantages over UV laser and phase mask techniques are presented.
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Tiwari, Vidhu Shekhar. "DEVELOPMENT OF FIBER OPTIC SENSOR BASED ON LASER RAMAN SPECTROSCOPY." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07082008-143038/.
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Laser Raman Spectroscopy (LRS) has received worldwide acknowledgement as a powerful molecular finger print technique. The Raman spectrum of sample contains useful information such as molecular identity, composition, constituents concentration ratio etc. These information are manifested in the Raman spectrum in band heights, peak wavelength, band areas etc. The basis of quantitative analysis in Raman spectroscopy lies in the measurement of Raman band intensity, which is linearly dependent upon the sample concentration. On the other hand, Raman spectroscopy can also yield the qualitative information of samples by exhibiting bands corresponding to various chemical constituents in the sample mixture. The potentiality of Raman spectroscopy to perform quantitative as well as qualitative analysis of samples has been exploited in the development of Raman sensors in conjugation with the techniques of fiber optics. The main focus of the presented doctoral work is to realize a fiber optic Raman sensor to monitor the quality of liquid oxygen (LO2) in a rocket engine feed line. In this research investigation, I have shown how a bulk experimental configuration can be transformed to miniaturized prototype sensor, which is equally capable to determine the ratio of liquid oxygen and liquid nitrogen in their cryogenic mixture. This research was extended to monitor the concentration of oxygen and nitrogen in their gaseous mixture. Further, I have demonstrated that the Raman spectroscopy has the potentiality to measure the temperature of hydrogen in a laboratory environment by monitoring the variation in Raman rotation-vibrational line of hydrogen gas with temperature. Finally, I have experimentally studied the surface enhanced Raman spectroscopy (SERS) of silver colloidal solution, which is another interesting branch of Raman spectroscopy that has transcended the limitation of very low Raman cross-section to offer more insight to the chemical properties of samples.
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KIM, CHAN KYU. "DEVELOPMENT OF BIO-PHOTONIC SENSOR BASED ON LASER-INDUCED FLUORESCENCE." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11052007-092200/.
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Laser-induced fluorescence (LIF) has been shown to be potentially useful for identifying microorganisms in real time. It is a selective and sensitive technique because the excitation is performed at one wavelength while the emission is monitored at longer wavelengths so that background from the excitation source can be eliminated. This specialized optical property of LIF can be applied to development of an optical sensor capable of quickly, non-invasively, and quantitatively probing complex biochemical transformations in microorganisms. Various bio-photonic optical fiber sensors based on laser-induced fluorescence (LIF) spectroscopy were developed as diagnostic tools for microorganisms. In the first phase, the enhancement of the sensitivity and selectivity of the optical sensor system focused on diagnosis of human breast cancer cell lines and Azotobacter vinelandii (an aerobic soil-dwelling organism). Auto-fluorescence spectra from human breast cancer cell lines and Azotobacter vinelandii corresponding to different growth environments were investigated. Then, the study has expanded to include the use of gold nanoparticles for specific DNA detection. The use of gold nanoparticales opens a door into construction of a compact, highly specific, inexpensive and user-friendly optical fiber senor for specific DNA detection. An optical fiber laser-induced fluorescence (LIF) sensor based has been developed to detect single-strand (ss) DNA hybridization at the femtomolar level. Effects of various experimental parameters and configuration were investigated in order to optimize sensor performance and miniaturize sensor size.
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Smith, Clinton James. "High-accuracy laser spectrometers for wireless trace-gas sensor networks." Thesis, Princeton University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3604506.
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The subject of this dissertation is the development of a wireless sensor network composed of instruments which employ both VCSELs and QCLs for accurate, highly sensitive, and reliable long-term monitoring of environmental trace-gases. The dissertation focuses on the development of low-power instruments and calibration methods that ensure the reliability of long-term measurements.
First the field deployment of a low-power, portable, wireless laser spectroscopic sensor node for atmospheric CO2 monitoring is demonstrated. The sensor node shows 0.14 ppmv Hz-1/2 1σ measurement sensitivity of CO2 concentration changes. It was first used to measure top-soil respiration rates in the laboratory and on forest floors in the field.
Then after a long-term field deployment to further assess instrument performance, new design solutions were implemented to improve fringe-limited precision of the nodes to 4-7 ppmv against a 400 ppmv CO2 background, making their performance comparable to higher power consuming commercial trace-gas analyzers. Three optimized nodes were then deployed into mixed landscapes as part of a solar powered CO2 monitoring wireless network. The three node network monitored CO2 in a grassy/woody courtyard, on top of the roof of an engineering building, and next to a road in the Princeton area. These works show that ultra-low powered VCSEL based sensor nodes can be placed in off-the-grid environments for autonomous distributed geographic monitoring of trace-gases in a manner which is impossible with current commercial techniques.
Next, this dissertation covers two techniques that were developed for the real-time calibration of laser-based trace-gas measurements. The first technique used an in-line reference gas cell and employed wavelength modulation spectroscopy (WMS) at higher harmonics to simultaneously probe the sample and reference spectra. The second technique used a revolving in-line reference cell to suppress background and other non-spectroscopic signals. These techniques were designed for eventual inclusion as a real-time calibration source for field deployable trace-gas sensors and wireless sensor networks.
Finally, this dissertation demonstrates the use of the CW injection current into a VCSEL in an external cavity configuration to tune the cavity emission's self-oscillation frequency and show through simulation and experiment that the tuning is dependent on VCSEL birefringence change.
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Kozlosky, E. S., D. H. Desrosiers, M. Glendening, and L. Morelli. "Auto Ranging Optical Sensor Suitable for High-Energy Laser Measurements." International Foundation for Telemetering, 1988. http://hdl.handle.net/10150/615027.
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International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaThis paper presents the design and performance of an auto ranging optical sensor (AROS) built for space applications and capable of measuring pulsed optical energy over a wide range of pulse widths, energy levels and wavelengths. The AROS measures energy densities over seven orders of magnitude to a maximum of 0.2 J/cm² and can withstand 1 J/cm² without damage. In addition to its intended use as a laser sensor in multi-sensor arrays on target satellites, the AROS is well suited for laboratory use in the measurement and profiling of high-power laser beams.
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Sakamoto, João Marcos Salvi. "Laser ultrasonics system with a fiber optic angular displacement sensor." Instituto Tecnológico de Aeronáutica, 2012. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2146.
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Laser ultrasonics is an all-optical non-destructive testing technique which employs ultrasonic waves as a means of ascertaining the internal part of an opaque material (for light). The difference from a conventional ultrasonics testing technique relies on the generation and detection of these waves which, in the laser ultrasonics technique, is performed by a laser pulse and an optical detector of ultrasound, respectively. This technique is employed in the aerospace and aeronautics industry for flaw detection or material characterization, since it is couplant free, non-contact and remote from the inspected object. The high cost and complexity of a commercial laser ultrasonics system, however, led to the development in this work, of an intensity-modulated fiber optic sensor to be employed as the optical detector of a laser ultrasonics system. This fiber optic sensor is capable to detect angular displacement in the range of microradians and presents high sensitivity, optical fiber compatibility, wide bandwidth and, furthermore, is simple to assembly and low cost. The fiber optic sensor comprises two optical fibers, a positive lens, a reflective surface, a laser, and a photodetector. A mathematical model was developed to determine and simulate the static characteristic curve of the sensor and to analyze the influence of geometrical parameters in its performance. Different sensor configurations were assembled and experimental static characteristic curves were acquired to validate the mathematical model. The normalized sensitivity, for the configurations tested, ranges from (0.25×Vmax) to (2.40×Vmax) mV/?rad and the linear range, from 194 to 1840 ?rad. Regarding an specific sensor configuration (the sensor 4/4) with reflective surface of 100% of reflectivity, the sensor presented an unnormalized sensitivity of 7.7 mV/?rad, an estimated resolution of approximately 1 ?rad and signal-to-noise ratio of 32 dB. The sensor was tested on the dynamic operation for sound and ultrasound detection and, finally as the optical detector of the complete laser ultrasonics system developed in this work. The sensor also proved to be suitable for time-of-flight measurements and nondestructive testing, being an alternative to the piezoelectric or the interferometric detectors.
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Azevedo, Rui Filipe Cabral de. "Sensor fusion of laser and vision in active pedestrian detection." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14414.
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Mestrado em Engenharia MecânicaThis work explores a technique of sensor fusion that aims to equip vehicles with pedestrian fast detection mechanisms in exterior environments. This method restricts image areas of search based on indicators obtained by another sensor (LIDAR). This technique is based on the idea that when having a registration among the involved sensors, one "fast" sensor, but inaccurate, that can indicate regions where potential pedestrian are located on the image, and another sensor, "slower" but more robust that is used to confirm detection more accurately. So, an algorithm was created to merge two algorithms, a LIDAR-based tracking and a vision-based detection algorithm; The LIDAR indicates the precise location and scale of the potential pedestrian on the image, and crop the image relative to the potential pedestrian, being processed afterwards by one pedestrian detection algorithm to validate the classification. The method is tested in two different cases and the results confirm their validity.
Este trabalho explora uma técnica de fusão sensorial que visa dotar veículos de mecanismos rápidos de detecção de peões em ambiente exterior. O método restringe as zonas de procura numa imagem com base em indicadores obtidos por outro sensor (LIDAR). Esta técnica tem como base a idéia de que havendo um registo entre os sensores envolvidos, um sensor "rápido" mas pouco preciso, pode indicar as regiões onde potencialmente há alvos, e outro sensor, "lento" mas mais robusto, é utilizado para fazer a confirmação da deteção. Com vista a explorar essas propriedades, foi criado um algoritmo que utiliza a informação de dois sensores, para primeiro selecionar, de entre muitos objectos, possíveis peões(fase LIDAR) e dada a informação da localização do possível pedestre, uma imagem já à escala e precisa da localização, é recortada da imagem inicial, sendo a mesma enviada a ser processada por um detetor de peões (sensor mais robusto), permitindo a sua rigorosa classificação. O método é testado em dois conjuntos de dados diferentes e os resultados confirmam a sua validade.
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Matos, Gabriel Silva de. "Laser triangulation sensor with refraction modelling for underwater 3D measurement." reponame:Repositório Institucional da UFSC, 2017. https://repositorio.ufsc.br/xmlui/handle/123456789/182608.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2017.Made available in DSpace on 2018-01-09T03:24:39Z (GMT). No. of bitstreams: 1 348525.pdf: 5019460 bytes, checksum: 4ed315a3b59a2bab9c3e13fc079bb513 (MD5) Previous issue date: 2017
Medições tridimensionais subaquáticas possuem diversas aplicações, por exemplo, na indústria de petróleo e gás para o controle de equipamentos submarinos durante procedimentos de manutenção otimizados. Sistemas com sensores de triangulação a laser (LTS) já são utilizados em ambientes subaquáticos e alguns desafios com LTS nestes ambientes já foram discutidos. Entre estes obstáculos estão a má qualidade de imagem, devido à absorção de luz e retrodifusão, e refração, devido às interfaces entre água e vidro e vidro e ar. O efeito da refração pode ser modelado conhecendo-se a distância da câmera à superfície de refração, o eixo de refração, o índice de refração dos meios e a espessura da janela óptica. Este trabalho analisa dois métodos para a calibração subaquática de LTS com experimentos em laboratório utilizando um LTS desenvolvido para esta aplicação. O primeiro método utiliza um ajuste polinomial, correlacionando o pico do laser para cada linha da imagem da câmera com um ponto 3D. Este método necessita de uma calibração subaquática completa. O segundo método, proposto aqui, é baseado no modelo de câmera pinhole e um plano matemático ajustado para o plano de luz laser projetado. Em medições de ar, para cada pico de laser detectado na imagem, uma linha pode ser definida através do centro da lente aplicando a matriz de projeção do modelo pinhole. A intersecção desta linha com o plano laser matemático resulta na medição de um ponto 3D. Para medições subaquáticas com um LTS de alta qualidade é necessário considerar, adicionalmente, o efeito da refração na interface entre a janela e água. Considerando a janela óptica normal ao eixo da câmera, um caminho de raio é definido no plano de refração de acordo com a lei de Snell para interceptar o plano do laser, definindo um ponto 3D. A calibração para medição subaquática necessita, portanto, estimar a distância da superfície de refração até o centro óptico da câmera. No método proposto, após a calibração no ar, um degrau é medido embaixo d'água e a distância da janela da câmera é otimizada. O método é avaliado de acordo com as diretrizes do VDI / VDE 2634 e vários objetos foram utilizados como exemplos de medição.
Abstract : Underwater tridimensional measurement has many applications, for example, to control underwater equipment during optimized maintenance procedures in the oil and gas industry. Systems with laser triangulation sensors (LTS) are being used underwater at present and some underwater problems with LTS have already been discussed. Among these challenging obstacles are poor image quality, due to light absorption and backscattering, and refraction, due to optical window interfaces between water and air inside the camera chamber. The refraction effect can be predicted knowing the distance from the camera pinhole center to the surface of refraction, the axis of refraction, the refractive index of the mediums and the thickness of the optical window. This work analyses two methods for underwater LTS calibration using real experiments with a built LTS, in-air and underwater. The first method uses a polynomial adjustment correlating to the laser peak for each camera image line with a 3D point. This method needs a complete calibration in the underwater environment. The second method proposed is based on the pinhole camera model and a fitted mathematical plane for the projected laser light plane. In air measurements, a line can be defined through the lens center using the pinhole projection matrix for each laser peak detected in the image. The intersection of this line with the laser mathematical plane leads to a measured 3Dpoint. For high quality underwater LTS measurements, it is necessary to additionally consider the refraction effect on the window and water interface. Considering the optical window normal to the camera axis, a ray path is defined on the plane of refraction according to the Snell?s law to intercept the laser plane, defining a 3D point. The calibration for underwater measurement needs to estimate the window distance from the camera. In the proposed method, after the in-air calibration,a step standard is measured underwater and the window distance from the camera is optimized. The method is evaluated according to the guidelines of VDI/VDE 2634 and multiple objects were evaluated.
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Solanki, Sanjay Champalal. "Implementation of laser range sensor and dielectric laser mirrors for 3D scanning of glove box environment." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001431.
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Freeborn, Scott Stuart. "Pulsed laser photoacoustic instrumentation for the monitoring of crude oil in produced water." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/1241.
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Asselin, Matthew. "Optical Sensor for Measurement of Clad Height during Laser Cladding Process." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/874.
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The process of laser cladding consists of depositing successive layers of molten metallic powder to create a near-net shape. A high-power laser is used to melt incoming metallic powder, which forms a melt pool on the surface. As the latter moves beneath the laser, this newly created melt pool solidifies. By properly controlling the trajectory of deposition tracks, one can create a diverse range of shapes with varying complexities. However, the process is very sensitive to parameters, requiring constant attention from technicians. This lends itself perfectly to the addition of automatic controllers whereby supervision is minimal. In this thesis, an optical sensor is developed to monitor the process zone. The sensor will output a measurement of the height of solidified clad, which in turn can be used by a controller to adjust this geometrical feature. The thesis is divided into three main parts, each contributing to the final algorithm.
First, in Chapter 3 an analysis is performed on the light irradiating from the interaction zone (or melt pool). It is stated that the dominating source of light is governed by blackbody radiation from this molten metal. This is confirmed by analyzing a series of images captured through a digital camera, where various narrow bandpass filters were utilized to selectively view a portion of the CCD-sensor's spectrum. This investigation also leads to the selection of bandpass filter such that a stable, relatively intense melt pool is captured through the digital camera's CCD-sensor.
Second, in Chapter 4 the captured images are taken through a pair of image processing techniques, outputting a series of coordinates representating the melt pool's boundary. The image is first analyzed to calculate an optimal threshold level based on the minimization of fuzzy entropy. With this threshold selected, the grayscale image is converted into black-and-white, where the white pixels represent the melt pool. After this step, the melt pool's boundary is extracted through an 8-connectivity border tracing algorithm. This technique outputs a series of coordinates (in pixels) as though one were traveling along the melt pool in a clockwise rotation.
Last, Chapter 5 analyzes these pixel coordinates to extract the melt pool's height. The coordinates are first transformed into real-world coordinates, by use of a perspective transformation. This transformation essentially yields the melt pool's shadow, as created by a light-source coincident with the camera. As a result, the melt pool's height is estimated based upon a right-angle triangle, where the camera's angle is known, and the projected coordinates represent the shadow length (triangle's base).
The result of applying this series of steps to the estimation of clad heights is found at the end of Chapter 5. Results varied dramatically, from 4% error to 393%. Although the errors are large at times, they are mainly caused by a bias in the estimate. That is, the dynamics of the true clad formation are very well predicted by the algorithm, however, shifting by a certain amount. This amount varies both with substrate velocity, and the clad's direction of travel, relative to the camera. A partial explanation is given such that the clad's height is offset from the laser center-point, which is a function of both these parameters. However, the specific relationship requires further experimentation.
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Zhang, Lu. "Interrogation sensor systems based on all-fiber distributed Bragg reflector laser." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110724.
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With the rapid development of fiber optic sensor systems and networks, creating a multi-functional, multi-channel with no crosstalk, low power consumption and highly compact measurement system has attracted more and more attention in recent years for monitoring structural health, environmental data, and vibration parameters.In this thesis, we investigate a fiber optic sensing system based on an all-fiber distributed Bragg reflector (DBR) laser. We measure the steady-state strain response to be 0.083nm/με and show that the response is very similar to a simple fiber Bragg grating (FBG), typically about 0.1nm/με. In addition, we demonstrate multi-channel operation without crosstalk. Also we present the low threshold power of 13.13mW of all-fiber DBR lasers. Furthermore, wavelength-to-power mapping for DBR sensors has been demonstrated by using interrogation filters, which allows using power meters or photo detectors to monitor the detected signal from the sensor. Finally, we present that all-fiber DBR lasers can also be used to detect acoustic waves generated by partial discharge arising from a power transformer, which can also improve the sensor system performance on measuring multiple parameters.Avec le développement rapide des systèmes à fibres optiques capteurs, la création d'un multi-fonctionnel, multi-canal avec aucun de diaphonie, faible consommation d'énergie et très compact système de mesure a attiré l'attention de plus en plus ces dernières années pour surveiller la santé structurelle, les données environnementales, paramètres de vibration et.Dans cette thèse, nous étudions un système de fibres optiques de détection basé sur un tout-fibre réflecteur de Bragg distribué (DBR) laser. Nous mesurons la réponse en déformation l'état d'équilibre pour être 0.083nm/με et montrent que la réponse est très similaire à un réseau de Bragg simple fibre (FBG), typiquement de l'ordre 0.1nm/με. En outre, nous démontrons le multi-canal sans diaphonie. En outre, nous présentons la puissance à bas seuil d'13.13mW de lasers DBR tout-fibre. En outre, la longueur d'onde à la puissance de cartographie pour les capteurs DBR a été démontré en utilisant des filtres d'interrogation, qui permet d'utiliser des wattmètres ou des détecteurs photo pour surveiller le signal détecté par le capteur. Enfin, nous présentons ce que tous les fibres de lasers DBR peut également être utilisé pour détecter les ondes acoustiques générées par la décharge partielle résultant d'une transformateur de puissance, qui peut également améliorer les performances du système de capteur sur la mesure de plusieurs paramètres.
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Crisostomo, Manuel Marques. "Development of a laser based proximity sensor for use with robots." Thesis, Brunel University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315489.
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Addy, Richard Charles. "The application of optical feedback in laser diodes to sensor systems." Thesis, City University London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266371.
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Tan, Tang Yew 1973. "Automated precision three-axis scanner and velocity sensor for laser dermatology." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80028.
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Ali, Md Afsar. "In-process quality monitoring of laser welds using multi-sensor measurements /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447428925.
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Bermuske, Mike, Lars Büttner, and Jürgen Czarske. "Measurement uncertainty budget of an interferometric flow velocity sensor." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35151.
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Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their in uences to the measurement uncertainty budget of the sensor is discussed. Finally, generated measurement results for the film flow of an impinging jet cleaning experiment are presented.
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Viña, Carlos. "Laser based sensor fusion and control for the tele-operation of minidrones." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066525/document.
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La robotique aérienne est un domaine de recherche qui a connu un grand succès commercial au cours des dernières années suite au développement de plates-formes aéroportées de petite taille hautement efficaces et abordables, couramment appelées mini-drones. Cela a ouvert la voie à de nouvelles applications dans les tâches de surveillance et d'inspection. Ces dernières années, cela a été un sujet de recherche clé dans l'industrie de l'énergie, où les lignes de transmission sont sujettes à la détérioration due aux conditions atmosphériques et nécessitent des programmes de surveillance étendus. Les mini-drones ont le potentiel d'automatiser entièrement le processus d'inspection, réduisant ainsi davantage les coûts et les temps d'inspection. Dans ce contexte, cette thèse aborde les inspections autonomes de tours électriques avec des MAV. A savoir, la localisation, la première étape d'une longue série de tâches vers la réalisation de capacités totalement autonomes, est le sujet principal de ce travail. Nous explorons comment les scanners laser 2D peuvent être couplés avec des capteurs couramment disponibles pour la pose à 6 degrés de liberté d'un mini-drone en temps réel avec les capacités perceptives et de traitement limites au bord de la plate-forme. Cette thèse tel que les algorithmes classiques de scan matching, comme l'algorithme Iterative Closest Point (ICP), la fusion de données et le contrôle par retour d'état. Des validations basées sur des vols expérimentaux et des simulations étendues sont présentéesAerial robotics is a prominent field of research that has seen great commercial success during the last years due to the development of highly efficient and affordable small-sized airborne platforms, commonly referred to as mini-drones. This has opened the way to promising new applications in surveillance and inspection tasks. In recent years, this has been a key subject of research in the power industry, where power utilities are subject to deterioration due to atmospheric conditions and require extensive monitoring programs. Mini-drones have the potential of fully automating the inspection process, further reducing costs and inspection times. In this context, this thesis addresses autonomous electric tower inspections with mini-drones. Namely, self-localization, the first step in a long series of tasks towards achieving fully autonomous capabilities, is the main focus of this work. We explore how 2D laser scanners can be coupled with commonly available sensors to estimate a mini-drone's 6 degree of freedom pose in real-time, using uniquely on-board sensing and processing capabilities. This thesis develops topics from classic scan matching algorithms, such as the iterative closest point (ICP) algorithm and proposed adaptations to the electric tower scene, to sensor fusion and feed-back control. Validations based on experimental flights and extensive simulations are presented
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Holmberg, Patrik. "Laser processing of Silica based glass." Doctoral thesis, KTH, Laserfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173929.
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The main topic of this thesis work is photosensitivity and photo-structuring of optical fibers and bulk glass. Although research in the field of photosensitivity in glass and optical fibers has been ongoing for more than three decades, the underlying mechanisms are still not well understood. The objective was to gain a better understanding of the photo-response by studying photosensitivity from a thermodynamic perspective, as opposed to established research focusing on point defects and structural changes, and strain and stress in optical fibers. Optical fibers was mainly used for experimental studies for two reasons; first, photosensitivity in fibers is more pronounced and more elusive compared to its bulk counterpart, and secondly, fibers provide a simplified structure to study as they experimentally can be seen as one-dimensional.Initially, ablation experiments on bulk glass were performed using picosecond infrared pulses. With a design cross section of 40x40 μm, straight channels were fabricated on the top (facing incident light) and bottom side of the sample and the resulting geometries were analyzed. The results show a higher sensitivity to experimental parameters for bottom side ablation which was ascribed to material incubation effects. Moreover, on the top side, the resulting geometry has a V-shape, independent of experimental parameters, related to the numerical aperture of the focusing lens, which was ascribed to shadowing effects.After this work, the focus shifted towards optical fibers, UV-induced fiber Bragg gratings (FBGs) and thermal processing with conventional oven and with a CO2 laser as a source of radiant heat.First, a system for CO2 laser heating of optical fibers was constructed. For measuring the temperature of the processed fibers, a special type of FBG with high temperature stability, referred to as "Chemical Composition Grating" (CCG) was used. A thorough characterization and temperature calibration was performed and the results show the temperature dynamics with a temporal resolution of less than one millisecond. The temperature profile of the fiber and the laser beam intensity profile could be measured with a spatial resolution limited by the grating length and diameter of the fiber. Temperatures as high as ~ 1750 °C could be measured with corresponding heating and cooling rates of 10.500 K/s and 6.500 K/s.Subsequently, a thorough investigation of annealing and thermal regeneration of FBGs in standard telecommunication fibers was performed. The results show that thermal grating regeneration involves several mechanisms. For strong regeneration, an optimum annealing temperature near 900 C was found. Two different activation energies could be extracted from an Arrhenius of index modulation and Braggv iwavelength, having a crossing point also around 900 °C, indication a balance of two opposing mechanisms.Finally, the thermal dynamics and spectral evolution during formation of long period fiber gratings (LPGs) were investigated. The gratings were fabricated using the CO2 laser system by periodically grooving the fibers by thermal ablation. Transmission losses were reduced by carefully selecting the proper processing conditions. These parameters were identified by mapping groove depth and transmission loss to laser intensity and exposure time.Huvudtemana i denna avhandling är fotokänslighet och fotostrukturering av optiska fibrer och bulk glas. Trots att forskning inom fotokänslighet i glas och optiska fibrer har pågått under mer än tre decennier är de bakomliggande mekanismerna ännu inte klarlagda. Syftet var att få en bättre förståelse för fotoresponsen genom att studera fotokäsligheten ur ett termodynamiskt perspektiv, i motsats till etablerad forskning med fokus på punktdefekter och strukturförändringar, samt mekaniska spännings effekter i optiska fibrer. Optiska fibrer användes för flertalet av de experimentella studierna av två skäl; för det första är fotokänsligheten i fibrer större och dessutom vet man mindre om bakomliggande mekanismer jämfört med motsvarande bulk glas, och för det andra kan fibrer vara enklare att studera eftersom de experimentellt kan ses som en endimensionell struktur.Inledningsvis utfördes ablaherings experiment på bulk glas med en infraröd laser med pikosekund pulser. Raka kanaler med ett designtvärsnitt på 40x40 μm tillverkades på ovansidan (mot infallande ljus) och bottensidan av provet och de resulterande geometrierna analyserades. Resultaten visar en högre känslighet för variationer i experimentella parametrar vid ablahering på undersidan vilket kan förklaras av inkubations effekter i materialet. Dessutom är den resulterande geometrin på ovansidan V-formad, oavsett experimentella parametrar, vilket kunde relateras till den numeriska aperturen hos den fokuserande linsen, vilket förklaras av skuggningseffekter.Efter detta arbete flyttades fokus mot optiska fibrer, UV inducerade fiber Bragg gitter (FBG), och termisk bearbetning med konventionell ugn samt även med en CO2-laser som källa för strålningsvärme.Först konstruerades ett system för CO2-laservärmning av fibrer. För mätning av temperaturen hos bearbetade fibrer användes en speciell sorts FBG med hög temperaturstabilitet, kallade ”Chemical Composition Gratings” (CCG). En grundlig karaktärisering och temperaturkalibrering utfördes och temperaturdynamiken mättes med en tidsupplösning på under en millisekund. Temperaturprofilen i fibern, och laserns strålprofil, kunde mätas med en spatiell upplösning begränsad av gitterlängden och fiberns diameter. Temperaturer upp till ~1750 °C, vilket är högre än mjukpunktstemperaturen, kunde mätas med korresponderande uppvärmnings- och avsvalningshastighet på 10.500 K/s och 6.500 K/s.Därefter gjordes en omfattande undersökning av värmebearbetning och termisk regenerering av FBG:er i telekomfiber. Resultaten visar att termisk gitter-regenerering aktiveras av flera olika mekanismer. Värmebearbetning vid en temperatur omkring 900 °C resulterade i starka gitter efter en regenerering vid en temperatur på 1100 °C. Två olika aktiveringsenergier kunde extraheras från en Arrhenius plot avseende brytningsindexmodulation och Braggvåglängd, med en skärningspunkt tillika runt 900 °C, vilket indikerar en avvägning mellan två motverkande mekanismer vid denna temperatur.Slutligen undersöktes temperaturdynamiken och de spektrala egenskaperna under tillverkning av långperiodiga fibergitter (LPG). Gittren tillverkades med CO2-vi iilasersystemet genom att skapa en periodisk urgröpning medelst termisk ablahering. Transmissionsförluster kunde reduceras med noggrant valda processparametrar. Dessa parametrar identifierades genom mätningar av ablaherat djup och transmissionsförlust som funktion av laserintensitet och exponeringstid.
QC 20150924
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Nascimento, Jehan Fonsêca do. "Sensor multiponto de corrosão baseado em reflectometria amplificada em fibra óptica." Universidade Federal de Pernambuco, 2013. https://repositorio.ufpe.br/handle/123456789/13349.
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CNPq; Programa de Pós-Graduação em Engenharia Elétrica
Esta tese apresenta dois esquemas de monitoramento de corrosão em metal à base de fibra óptica usando a técnica de reflectometria óptica amplificada no domínio do tempo e também apresenta resultados experimentais de um estudo sobre os efeitos da rugosidade de superfície no filme metálico sob o sinal óptico durante o processo de corrosão. O sistema sensor amplificado é multiponto, auto-referenciado e pode medir taxa de corrosão a vários quilômetros do equipamento OTDR. O primeiro esquema usa uma fibra dopada com Érbio com bombeamento remoto e é utilizado para avaliar o aumento do alcance do sistema quando comparado com o sistema não-amplificado. O segundo esquema usa outro EDFA próximo ao OTDR como reforço para o sinal óptico gerado por ele. Além disso, esse sistema é usado para as medidas de corrosão e também para avaliação da sensibilidade do sistema às variações de ganho do amplificador. Os resultados experimentais obtidos em condições laboratoriais controladas mostram as vantagens do sistema de amplificação, em termos do seu longo alcance, melhor resolução espacial e imunidade a variações de ganho. Nos resultados experimentais obtidos pelo sensor de corrosão foram observados efeitos ópticos que sugerem a influência da rugosidade do filme metálico na reflectância da luz, resultante do processo de corrosão. Resultados experimentais obtidos através de um aparato experimental que utiliza diferentes comprimentos de onda da luz e também diferentes meios externos indicam que ocorrem efeitos de espalhamento de luz e ressonância de plásmons de superfície.
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Griffiths, Alan David, and alan griffiths@anu edu au. "Development and demonstration of a diode laser sensor for a scramjet combustor." The Australian National University. Faculty of Science, 2005. http://thesis.anu.edu.au./public/adt-ANU20051114.132736.
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Hypersonic vehicles, based on scramjet engines, have the potential to deliver inexpensive access to space when compared with rocket propulsion. The technology, however, is in its infancy and there is still much to be learned from fundamental studies.¶
Flows that represent the conditions inside a scramjet engine can be generated in ground tests using a free-piston shock tunnel and a combustor model. These facilities provide a convenient location for fundamental studies and principles learned during ground tests can be applied to the design of a full-scale vehicle.¶
A wide range of diagnostics have been used for studying scramjet flows, including surface measurements and optical visualisation techniques.¶
The aim of this work is to test the effectiveness of tunable diode laser absorption spectroscopy (TDLAS) as a scramjet diagnostic.¶
TDLAS utilises the spectrally narrow emission from a diode laser to probe individual
absorption lines of a target species. By varying the diode laser injection
current, the laser emission wavelength can be scanned to rapidly obtain a profile of the spectral line. TDLAS has been used previously for gas-dynamic sensing applications and, in the configuration used in this work, is sensitive to
temperature and water vapour concentration.¶
The design of the sensor was guided by previous work. It incorporated aspects of designs that were considered to be well suited to the present application. Aspects of the design which were guided by the literature included the laser emission wavelength, the use of fibre optics and the detector used. The laser emission wavelength was near 1390 nm to coincide with relatively strong water vapour transitions. This wavelength allowed the use of telecommunications optical fibre and components for light delivery. Detection used a dual-beam, noise cancelling detector.¶
The sensor was validated before deployment in a low-pressure test cell and a hydrogenair flame. Temperature and water concentration measurements were verified to within 5% up to 1550 K. Verification accuracy was limited by non-uniformity along the beam path during flame measurements.¶
Measurements were made in a scramjet combustor operating in a flow generated by the T3 shock tunnel at the Australian National University. Within the scramjet combustor, hydrogen was injected into a flame-holding cavity and the sensor was operated downstream in the expanded, supersonic, post-combustion flow. The sensor was operated at a maximum repetition rate of 20 kHz and
could resolve variation in temperature and water concentration over the 3ms running time of the facility.¶
Results were repeatable and the measurement uncertainty was smaller than the turbulent fluctuations in the flow. The scramjet was operated at two fuel-lean equivalence ratios and the sensor was able to show differences between the two operating conditions. In addition, vertical traversal of the sensor revealed variation in flow conditions across the scramjet duct.¶
The effectiveness of the diagnostic was tested by comparing results with those from other measurement techniques, in particular pressure and OH fluorescence measurements, as well as comparison with computational simulation.¶
Combustion was noted at both of the tested operating conditions in data from all three measurement techniques.¶
Computation simulation of the scramjet flow significantly under-predicted the water vapour concentration. The discrepancy between experiments and simulation was not apparent in either the pressure measurements or the OH fluorescence, but was clear in the diode laser results.¶
The diode laser sensor, therefore, was able to produce quantitative results which were useful for comparison with a CFD model of the scramjet and were complimentary to information provided by other diagnostics.
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Barasa, Benedict Paul Mmtoni. "Evaluation of satellite laser ranging errors associated with pressure sensor height offsets." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/77841.
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In this study an evaluation of the satellite laser ranging (SLR) errors associated with pressure sensor height offsets was conducted. Site log sheets from satellite ranging stations were retrieved from the International Laser Ranging Services (ILRS) and examined. It was noted that some log sheets were updated more than a decade ago. In order to ascertain and assess the accuracy of height offsets between the pressure sensor and the telescope invariant point (IVP), an electronic survey was conducted. The feedback received was compared with the site log sheet data and some discrepancies were noted. Furthermore, in order to determine the effect of pressure variations on the range bias, simulations were performed on the same dataset but with different barometric pressure values. This was accomplished by adjusting pressure values in the source code of the analysis software, the Satellite Data Analysis Software (SDAS), before each run. The SDAS was developed by Prof. Ludwig Combrinck at the Hartebeesthoek Radio Astronomy Observatory (HartRAO), South Africa. The focus was to examine the standard deviation of the Observed minus Computed (O-C) results where it was noted that each alteration of pressure caused a variation of the O-C residuals. The differences of pressure sensor height offsets (pressure as a function of height) and SLR range biases were characterized across the SLR network and the station range bias (Rb) examined to determine if there is any correlation with the O-C residuals whenever pressure values changed. Overall, the analysis illustrated that, while the current atmospheric models are robust and capable of achieving sub-millimetre level accuracy, it is crucial to put more emphasis on the site activities that, if unattended will contribute to the ranging errors. It is vital to monitor constantlythe stability of pressure sensors. For example, it was noted in May 2019 at the Geodetic Observatory Wettzell, that their instrument had developed pressure drifting of -0.025 hPa/year. The Wettzell incident underscores the need for regular calibration of pressure instruments especially those that have been in service for more than a decade. Further, the site log sheets ought to be updated regularly and stations that reported estimated height offsets should be encouraged to measure them accurately. Additionally, the height of a meteorological instrument is currently ambiguous and ought to be explicitly stated.Dissertation (MSc)--University of Pretoria, 2020.
Geography, Geoinformatics and Meteorology
MSc
Unrestricted
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Zuo, Ziwei. "Fabrication of intensity-based Long-Period-Gratings fiber sensor with CO2 Laser." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54599.
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This thesis investigates the fabrication technique and procedures for producing long period grating (LPG) fiber sensors with point-by-point irradiation under a CO2 laser beam. The type of fiber sensor under examination is desirable to be highly sensitive to the variation of the thickness and refractive index of a thin film deposited on the LPGs, making it a promising candidate as a core sensor component in a biosensor system developed for detection and verification of pathogenic bacteria, such as Methicillin-resistant Staphylococcus aureus (MRSA), Francisella tularensis, and so on.
We have previously demonstrated that a UV-induced long-period-grating (LPG) based fiber sensor is extremely sensitive to small variation of refractive index (RI) and thickness of the surrounding medium. In this thesis, we will present a CO2 laser and step- stage system that operate automatically under control of a Matlab program to inscribe LPGs with desired grating period and fabrication conditions.
Examples of CO2 laser induced LPGs have been found to exhibit high sensitivity, with transmissive power attenuation of more than 15 dB at the resonant peak of 1402 nm under deposition of Ionic Self-Assembled Monolayer (ISAM) thin film that is around 50 nm in thickness. When tuned to its maximum sensitivity region, this LPG has shown a transmission power reduction of 79% with the deposition of only 1 bilayer of ISAM thin film at the monitored wavelength. This result is comparable in sensitivity with the UV-induced LPGs, yet with the advantage of lower fabrication cost and simplified fabrication procedure.Master of Science
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Kanabar, Prachi. "Three Dimensional Modeling of Hard Connective Tissues Using a Laser Displacement Sensor." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1218171143.
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Gallegos, Garrido Gabriela. "Development of a tightly-coupled composite Vision/Laser sensor for indoor SLAM." Institut national de recherche en informatique et en automatique (France). Unité de recherche (Sophia Antipolis, Alpes-Maritimes), 2011. http://pastel.archives-ouvertes.fr/tel-00604647/fr/.
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Depuis trois décennies, la navigation autonome en environnement inconnu est une des thématiques principales de recherche de la communauté robotique mobile. En l'absence de connaissance sur l'environnement, il est nécessaire de réaliser simultanément les tâches de localisation et de cartographie qui sont extrêmement interdépendantes. Ce problème est connu sous le nom de SLAM (Simultaneous Localization And Mapping). Pour obtenir des informations précises sur leur environnement, les robots mobiles sont équipés d'un ensemble de capteurs appelé système de perception qui leur permet d'effectuer une localisation précise et une reconstruction fiable et cohérente de leur environnement. Nous pensons qu'un système de perception composé de l'odométrie du robot, d'une camera omnidirectionnelle et d'un télémètre laser 2D est suffisant pour résoudre de manière robuste les problèmes de SLAM. Dans ce contexte, nous proposons une approche appearance-based pour résoudre les problèmes de SLAM et effectuer une reconstruction 3D fiable de l'environnement. Cette approche repose sur un couplage serré entre les capteurs laser et omnidirectionnel permettant d'exploiter au mieux les complémentarités des deux types de capteurs. Une représentation originale et générique robot-centrée est proposée. Une vue augmentée sphérique est construite en projetant dans l'image omnidirectionelle les mesures de profondeur du télémètre laser et une estimation de la position du sol. Notre méthode de localisation de type appearance-based minimise une fonction de coût non-linéaire directement construite à partir de la vue sphérique augmenté décrite précédemment. Cependant comme dans toutes les méthodes récursives d'optimisation, des problèmes de convergence peuvent survenir quand l'initialisation est loin de la solution. Ce problème est aussi présent dans notre méthode où une initialisation suffisamment proche de la solution est nécessaire pour s'assurer une convergence rapide et pour réduire les couts de calcul. Pour cela, on utilise un algorithme de PSM amélioré pour construire une prédection du déplacement du robotAutonomous navigation in unknown environments has been the focus of attention in the mobile robotics community for the last three decades. When neither the location of the robot nor a map of the region are known, localization and mapping are two tasks that are highly inter-dependent and must be performed concurrently. This problem, is known as Simultaneous Localization and Mapping (SLAM). In order to gather accurate information about the environment, mobile robots are equipped with a variety of sensors that together form a perception system that allows accurate localization and reconstruction of reliable and consistent representations of the environment. We believe that a perception system composed of the odometry of the robot, an omnidirectional camera and a 2D laser range finder provide enough information to solve the SLAM problem robustly. In this context we propose an appearance-based approach to solve the SLAM problem and reconstruct a reliable 3D representation of the environment. This approach relies on a tightly-coupled laser/omnidirectional sensor in order to take profit of the complementarity of each sensor modality. A novel generic robot-centered representation that is well adapted to the appearance-based SLAM is proposed. This augmented spherical view is constructed using the depth information from the laser range finder and the floor plane, together with lines extracted from the omnidirectional image. The appearance-based localization method minimizes a non-linear cost function directly built from the augmented spherical view. However, recursive optimization methods suffer from convergence problems when initialized far from the solution. This is also true for our method where an initialization sufficiently close to the solution is needed to ensure rapid convergence and reduce computational cost. A Enhanced Polar Scan Matching algorithm is used to obtain this initial guess of the position of the robot to initialize the algorithm
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Schäfer, Alexandro Gularte. "Aplicação de produtos fotogramétricos e do sensor laser scanner em projetos rodoviários." Florianópolis, SC, 2004. http://repositorio.ufsc.br/xmlui/handle/123456789/87559.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Civil.Made available in DSpace on 2012-10-21T22:03:00Z (GMT). No. of bitstreams: 1 210583.pdf: 5597448 bytes, checksum: d8af394dcfea7cc70a39eded37e53a93 (MD5)
As rodovias constituem uma categoria de empreendimentos de grande porte que alteram profundamente o desenvolvimento e o ordenamento territorial, interferindo na qualidade no meio ambiente tanto na sua fase de construção quanto durante o período de operação. O conhecimento rigoroso das condições ambientais da área onde a rodovia será implantada é fator determinante na qualidade do projeto rodoviário tanto do ponto de vista técnico como ambiental. Ao longo das últimas décadas, técnicas fotogramétricas se consolidaram em estudos para implantação de rodovias. O desenvolvimento tecnológico possibilitou o surgimento de sensores complementares às câmeras fotogramétricas como o sensor Laser Scanner, que possibilita a geração de Modelos Digitais do Terreno (MDT) e Modelos Digitais de Elevação (MDE) de uma área de forma relativamente rápida e com precisão altimétrica na casa dos decímetros. Nesta pesquisa fez-se um estudo em um trecho da rodovia SC-414 com o objetivo de estudar aplicações para produtos fotogramétricos, do sensor Laser Scanner e integração de ambos em projetos rodoviários. Utilizou-se para isso mapeamentos realizados para os estudos de anteprojeto do projeto final de construção da rodovia. Inicialmente buscou-se informações e treinamento com os detentores da tecnologia Laser Scanner no país. A próxima etapa consistiu no tratamento da nuvem de pontos laser utilizando programas CAD e programas específicos para o manuseio dos dados laser. Os dados tratados foram integrados com os produtos fotogramétricos, gerando-se mapas de uso do solo, MDTs, MDEs e cartas de declividade. Estes produtos foram sobrepostos entre si e ao cadastro técnico e projeto geométrico da rodovia, tornando possível a realização de análise temática da faixa de domínio. Realizou-se também uma análise de propriedades rurais na área diretamente afetada pela implantação da rodovia. Observou-se que sensor Laser Scanner é capaz de gerar informações temáticas de grande escala relevantes para projetos de implantação de rodovias. A integração de produtos fotogramétricos digitais forneceu informações que não seriam obtidas somente com os produtos do sensor Laser Scanner. A utilização conjunta dos produtos gerados com o cadastro técnico e o projeto geométrico da rodovia constituiu-se em excelente ferramenta para análises temáticas da área onde a rodovia será implantada.
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Griffiths, Alan David. "Development and demonstration of a diode laser sensor for a scramjet combustor /." View thesis entry in Australian Digital Theses, 2005. http://thesis.anu.edu.au/public/adt-ANU20051114.132736/index.html.
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Burns, Iain Stewart. "A sensor for combustion thermometry based on blue diode lasers." Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/244070.
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Spatially-resolved measurements of flame temperature have been demonstrated with diode lasers for the first time. The technique is based on the use of blue diode lasers to perform laser-induced fluorescence on indium atoms seeded to the flame. Temperature measurements have been carried out in laminar flames both by the two-line atomic fluorescence technique, and also by a novel line-shape thermometry method that requires the use of only a single diode laser. The first part of this work involved the development of blue extended cavity diode lasers with favourable tuning properties. Two custom-designed extended cavity diode lasers (ECDL) have been built, emitting at wavelengths of around 410 nm and 451 nm respectively. These devices are capable of mode-hop free tuning over ranges greater than 90 GHz. The performance of these devices exceeds that of commercially available systems and a patent application has been filed. High resolution fluorescence spectroscopy has been performed on both the 52P1/2→62S1/2 and 52P3/2→62S1/2 transitions of indium atoms seeded at trace quantities into atmospheric pressure flames. In both cases, the spectra obtained show excellent agreement with a theoretical fit based on the individual hyperfine components of the transition. The two ECDLs have been used to build a sensor for the measurement of temperature in combustion systems. It is much simpler, more compact, less expensive, and more versatile than any previously existing device. The two lasers were used sequentially to probe indium atoms seeded to the flame. The ratio of the resulting fluorescence signals is related to the relative populations in the two sub-levels of the spin-orbit split ground state of indium, and thus to the temperature. Temperature measurements have been successfully performed in a laminar flame and the data thus obtained do not need to be corrected by any ‘calibration constant’. This novel thermometry technique offers a robust alternative to traditional methods involving bulky high power lasers. A further development has been made by demonstrating a fluorescence line-shape thermometry technique requiring only a single diode laser excitation source. Progress has been made towards the goal of rapid temperature measurements appropriate to the study of turbulent flames. This involved the development of a simple technique for actively locking the wavelength of the blue diode laser to a resonance line of the tellurium molecule. A high-speed thermometry system would work by rapidly switching between the two locked laser beams using an optical modulator.
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Schuldt, Thilo. "An optical readout for the LISA gravitational reference sensor." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16241.
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Der weltraumgestützte Gravitationswellendetektor LISA (Laser Interferometer Space Antenna) besteht aus drei identischen Satelliten an Bord derer sich jeweils zwei frei schwebende Testmassen befinden. Die Lage der einzelnen Testmassen in Bezug auf die zugehörige optische Bank muss mit einer Genauigkeit besser 1 pm/sqrt(Hz) in der Abstands- und besser 10 nrad/sqrt(Hz) in der Winkelmessung erfolgen. In der vorliegenden Arbeit wird ein kompaktes optisches Auslesesystem präsentiert, welches als Prototyp für diese Abstands- und Winkelmetrologie dient. Das dafür entwickelte polarisierende Heterodyn-Interferometer mit räumlich getrennten Frequenzen basiert auf einem hoch-symmetrischen Design, bei dem zur optimalen Gleichtakt-Unterdrückung Mess- und Referenzarm die gleiche Polarisation und Frequenz sowie annähernd gleiche optische Pfade haben. Für die Winkelmessung wird die Methode der differentiellen Wellenfrontmessung eingesetzt. In einem ersten Prototyp-Aufbau wird ein Rauschniveau von weniger als 100 pm/sqrt(Hz) in der Translations- und von weniger als 100 nrad/sqrt(Hz) in der Winkelmessung (beides für Frequenzen oberhalb 0.1 Hz) demonstriert. In einem zweiten Prototyp-Aufbau werden zusätzlich eine Intensitätsstabilisierung und ein Phasenlock der beiden Frequenzen implementiert. Die analoge Phasenmessung ist durch eine digitale, FPGA basierte, ersetzt. Mit diesem Aufbau wird ein Rauschen kleiner 5 pm/sqrt(Hz) in der Translationsmessung und kleiner 10 nrad/sqrt(Hz) in der Winkelmessung, beides für Frequenzen größer 0.01 Hz, erreicht. Eine Rausch-Analyse wurde durchgeführt und die Nichtlinearitäten des Interferometers bestimmt. Das Interferometer wurde im Hinblick auf die LISA Mission entwickelt, findet seine Anwendung aber auch bei der Charakterisierung der dimensionalen Stabilität von ultra-stabilen Materialien sowie in der optischen Profilometrie. Die Adaptierung des Interferometers dazu sowie erste Resultate zu beiden Anwendungen werden in dieser Arbeit präsentiert.The space-based gravitational wave detector LISA (Laser Interferometer Space Antenna) consists of three identical satellites. Each satellite accommodates two free-flying proof masses whose distance and tilt with respect to its corresponding optical bench must be measured with at least 1 pm/sqrt(Hz) sensitivity in translation and at least 10 nrad/sqrt(Hz) sensitivity in tilt measurement. In this thesis, a compact optical readout system is presented, which serves as a prototype for the LISA proof mass attitude metrology. We developed a polarizing heterodyne interferometer with spatially separated frequencies. For optimum common mode rejection, it is based on a highly symmetric design, where measurement and reference beam have the same frequency and polarization, and similar optical pathlengths. The method of differential wavefront sensing (DWS) is utilized for the tilt measurement. In a first prototype setup noise levels below 100 pm/sqrt(Hz) in translation and below 100 nrad/sqrt(Hz) in tilt measurement (both for frequencies above 0.1 Hz) are achieved. A second prototype was developed with additional intensity stabilization and phaselock of the two heterodyne frequencies. The analog phase measurement is replaced by a digital one, based on a Field Programmable Gate Array (FPGA). With this setup, noise levels below 5 pm/sqrt(Hz) in translation measurement and below 10 nrad/sqrt(Hz) in tilt measurement, both for frequencies above 0.01Hz, are demonstrated. A noise analysis was carried out and the nonlinearities of the interferometer were measured. The interferometer was developed for the LISA mission, but it also finds its application in characterizing the dimensional stability of ultra-stable materials such as carbon-fiber reinforced plastic (CFRP) and in optical profilometry. The adaptation of the interferometer and first results in both applications are presented in this work.
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Khokar, Karan. "Laser assisted telerobotic control for remote manipulation activities." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003128.
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Eliasson, Emanuel. "Fusing Laser and Radar Data for Enhanced Situation Awareness." Thesis, Linköping University, Fluid and Mechanical Engineering Systems, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57928.
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With an increasing traffic intensity the demands on vehicular safety is higher than ever before. Active safety systems that have been developed recent years are a response to that. In this master thesis Sensor Fusion is used to combine information from a laser scanner and a microwave radar in order to get more information about the surroundings in front of a vehicle. The Extended Kalman Filter method has been used to fuse the information from the sensors. The process model consists partly of a Constant Turn model to describe the motion of the ego vehicle as well as a tracked object. These individual motions are then put together in a framework for spatial relationships to describe the relationship between them. Two measurement models have been used to describe the two sensors. They have been derived from a general sensor model. This filter approach has been used to estimate the position and orientation of an object relative the ego vehicle. Also velocity, yaw rate and the width of the object have been estimated. The filter has been implemented and simulated in Matlab. The data that has been recorded and used in this work is coming from a scenario where the ego vehicle is following an object in a quite straight line. Where the ego vehicle is a truck and the object is a bus. One important conclusion from this work is that the filter is sensitive to the number of laser beams that hits the object of interest. No qualitative validation has been made though.
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Wang, Hongzhi. "Development of laser system to measure pavement rutting." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001371.
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Lee, Kyung-Woo. "Fiber Fabry-Perot interferometer (FFPI) sensor using vertical cavity surface emitting laser (VCSEL)." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4221.
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This research represents the first effort to apply vertical cavity surface emitting lasers (VCSELs) to the monitoring of interferometric fiber optic sensors. Modulation of the drive current causes thermal tuning of the laser light frequency. Reflection of this frequency-modulated light from a fiber Fabry-Perot interferometer (FFPI) sensor produces fringe patterns which can be used to measure the optical path difference of the sensor. Spectral characteristics were measured for 850nm VCSELs to determine the combination of dc bias current, modulation current amplitude and modulation frequency for which single mode VCSEL operation and regular fringe patterns are achieved. The response characteristics of FFPI sensors were determined experimentally for square, triangular, saw-tooth waveforms at frequencies from 10kHz to 100kHz. The dependence of VCSEL frequency on the dc bias current was determined from spectral measurements to be ~165GHz/mA. An independent measurement of this quantity based on counting fringes from the FFPI sensor as the laser modulated was in good agreement with this value. The effect of optical feedback into the laser was also studied. By observing the fringe shift as the FFPI sensor was heated, a fractional change in optical length with temperature of 6.95 X 10-6/ðC was determined in good agreement with previous measurements on a 1300nm single mode fiber. The performance of 850nm VCSEL/FFPI systems was compared with their counterparts using 1300nm distributed feedback (DFB) lasers. The results of these experiments show that the 850nm VCSEL/FFPI combination gives regular fringe patterns at much lower bias current and modulating current amplitudes than their 1300nm DFB/FFPI counterparts.
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Dalgleish, Fraser Ross. "The development and evaluation of a laser-assisted vision sensor for AUV navigation." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408531.
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Badjatya, Vaibhav. "TUNABLE LASER INTERROGATION OF SURFACE PLASMON RESONANCE SENSORS." UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_theses/588.
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Surface plasmons are bound TM polarized electromagnetic waves that propagate along the interface of two materials with real dielectric constants of opposite signs. Surface plasmon resonance (SPR) sensors make use of the surface plasmon waves to detect refractive index changes occurring near this interface. For sensing purposes, this interface typically consists of a metal layer, usually gold or silver, and a liquid dielectric. SPR sensors usually measure the shift in resonance wavelength or resonance angle due to index changes adjacent to the metal layer. However this restricts the limit of detection (LOD), as the regions of low slope (intensity vs. wavelength or angle) in the SPR curve contain little information about the resonance. This work presents the technique of tunable laser interrogation of SPR sensors. A semiconductor laser with a typical lasing wavelength of 650nm was used. A 45nm gold layer sputtered on a BK7 glass substrate served as the sensor. The laser wavelength is tuned to always operate in the region of highest slope by using a custom-designed LabVIEW program. It is shown that the sensitivity is maximized and LOD is minimized by operating around the region of high slope on the SPR curve.
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Juarez, Juan C. "Distributed fiber optic intrusion sensor system for monitoring long perimeters." Thesis, [College Station, Tex. : Texas A&M University, 2005. http://hdl.handle.net/1969.1/ETD-TAMU-1702.
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Colaço, André Freitas. "Mobile terrestrial laser scanner for site-specific management in orange crop." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-23012017-151317/.
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Sensors based on LiDAR (Light Detection and Ranging) technology have the potential to provide accurate 3D models of the trees retrieving information such as canopy volume and height. This information can be used for diagnostics and prescriptions of fertilizers and plant protection products on a site-specific basis. This research aimed to investigate the use of LiDAR sensors in orange crops. Orange is one of the most important tree crop in Brazil. So far, research have developed and tested LiDAR based systems for several tree crops. However, usually individual trees or small field plots have been used. Therefore, several aspects related to data acquisition and processing must still be developed for large-scale application. The first study reported in this document (Chapter 3) aimed to develop and test a mobile terrestrial laser scanner (MTLS) and new data processing methods in order to obtain 3D models of large commercial orange groves and spatial information about canopy geometry. A 2D laser sensor and a RTK-GNSS receiver (Real Time Kinematics - Global Navigation Satellite System) were mounted on a vehicle. The data processing was based on generating a georeferenced point cloud, followed by the filtering, classification and surface reconstruction steps. A 25 ha commercial orange grove was used for field validation. The developed data acquisition and processing system was able to produce a reliable point cloud of the grove, providing high resolution canopy volume and height information. The choice of the type of point cloud classification (by individual trees or by transversal sections of the row) and the surface reconstruction algorithm is discussed in this study. The second study (Chapter 4) aimed to characterize the spatial variability of canopy geometry in commercial orange groves. Understanding such variability allows sensor-based variable rate application of inputs (i.e, applying proportional rates of inputs based on the variability of canopy size) to be considered as a suitable strategy to optimize the use of fertilizers and plant protection products. Five commercial orange groves were scanned with the developed MTLS system. According to the variability of canopy volume found in those groves, the input savings as a result of implementing sensor-based variable rate technologies were estimated in about 40%. The second goal of this study was to understand the relationship between canopy geometry and several other relevant attributes of the groves. The canopy volume and height maps of three groves were analyzed against historical yield maps, elevation, soil electrical conductivity, organic matter and clay content maps. The correlations found between canopy geometry and yield or soil maps varied from poor to strong correlations, depending on the grove. When classifying the groves into three classes according to canopy size, the yield performance and soil features inside each class was found to be significantly different, indicating that canopy geometry is a suitable variable to guide management zones delineation in one grove. Overall results from this research show the potential of MTLS systems and subsequent data analysis in orange crops indicating how canopy geometry information can be used in site-specific management practices.Sensores baseados em tecnologia LiDAR (Light Detection and Ranging) têm o potencial de fornecer modelos tridimensionais de árvores, provendo informações como o volume e altura de copa. Essas informações podem ser utilizadas em diagnósticos e recomendações localizadas de fertilizantes e defensivos agrícolas. Este estudo teve como objetivo investigar o uso de sensores LiDAR na cultura da laranja, uma das principais culturas de porte arbóreo no Brasil. Diversas pesquisas têm desenvolvido sistemas LiDAR para culturas arbóreas. Porém, normalmente tais sistemas são empregados em plantas individuais ou em pequenas áreas. Dessa forma, diversos aspectos da aquisição e processamento de dados ainda devem ser desenvolvidos para viabilizar a aplicação em larga escala. O primeiro estudo deste documento (Capítulo 3) focou no desenvolvimento de um sistema LiDAR (Mobile Terrestrial Laser Scanner - MTLS) e nova metodologia de processamento de dados para obtenção de informações acerca da geometria das copas em pomares comerciais de laranja. Um sensor a laser e um receptor RTK-GNSS (Real Time Kinematics - Global Navigation Satellite System) foram instalados em um veículo para leituras em campo. O processamento de dados foi baseado na geração de uma nuvem de pontos, seguida dos passos de filtragem, classificação e reconstrução da superfície das copas. Um pomar comercial de laranja de 25 ha foi utilizado para a validação. O sistema de aquisição e processamento de dados foi capaz de produzir uma nuvem de pontos representativa do pomar, fornecendo informação sobre geometria das plantas em alta resolução. A escolha sobre o tipo de classificação da nuvem de pontos (em plantas individuais ou em seções transversais das fileiras) e sobre o algoritmo de reconstrução de superfície, foi discutida nesse estudo. O segundo estudo (Capítulo 4) buscou caracterizar a variabilidade espacial da geometria de copa em pomares comerciais. Entender tal variabilidade permite avaliar se a aplicação em taxas variáveis de insumos baseada em sensores LiDAR (aplicar quantias de insumos proporcionais ao tamanho das copas) é uma estratégia adequada para otimizar o uso de insumos. Cinco pomares comerciais foram avaliados com o sistema MTLS. De acordo com a variabilidade encontrada, a economia de insumos pelo uso da taxa variável foi estimada em aproximadamente 40%. O segundo objetivo desse estudo foi avaliar a relação entre a geometria de copa e diversos outros parâmetros dos pomares. Os mapas de volume e altura de copa foram comparados aos mapas de produtividade, elevação, condutividade elétrica do solo, matéria orgânica e textura do solo. As correlações entre geometria de copa e produtividade ou fatores de solo variaram de fraca até forte, dependendo do pomar. Quando os pomares foram divididos entre três classes com diferentes tamanhos de copas, o desempenho em produtividade e as características do solo foram distintas entre as três zonas, indicando que parâmetros de geometria de copa são variáveis úteis para a delimitação de unidades de gestão diferenciada em um pomar. Os resultados gerais desta pesquisa mostraram o potencial de sistemas MTLS para pomares de laranja, indicando como a geometria de copa pode ser utilizada na gestão localizada de pomares de laranja.
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Canata, Tatiana Fernanda. "Sistema de mensuração baseado em tecnologia LiDAR para a estimativa de parâmetros de produção de cana-de-açúcar." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-29092017-184829/.
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A participação econômica da cana-de-açúcar (Saccharum spp.) é expressiva no agronegócio brasileiro, especialmente no estado de São Paulo. O monitoramento de produtividade para essa cultura é escasso de soluções consolidadas no nível de pesquisa e comercialmente. Tal monitoramento auxilia na identificação das variabilidades espacial e temporal, além de fornecer subsídio ao gerenciamento agrícola. Como uma alternativa os sensores a laser, abrangidos pela tecnologia LiDAR (Light Detection and Ranging), têm sido utilizados por meio de plataformas aéreas ou terrestes para a estimativa de produtividade de culturas de grãos como milho e trigo, e para o monitoramento de florestas de modo não invasivo. O objetivo deste estudo é a investigação de aplicação do sensor a laser para a cana-de-açúcar em período pré-colheita a partir do desenvolvimento de um sistema de mensuração. O sistema é composto por um sensor a laser, receptor GNSS (Global Navigation Satellite System), uma unidade inercial e um computador portátil. O sensor a laser emite feixes de luz (905 nm) na forma de um único pulso em um plano 2D, a partir desses feixes os valores de distância entre o sensor e o dossel de plantas são calculados durante a trajetória do veículo agrícola. O receptor GNSS com sinal RTK (Real Time Kinematic) foi sincronizado ao sensor a laser para a obtenção da nuvem de pontos, a qual é caracterizada pela alocação de cada ponto impactado pelo feixe de luz nas respectivas coordenadas geográficas. A unidade inercial fornece informações relacionadas à influência da vibração a partir dos dados de oscilação na transversal (roll), lateral (pitch) e longitudinal (yaw). Os equipamentos foram instalados em um suporte de estrutura metálica no trator agrícola e conectados ao computador por meio de protocolos de comunicação. O desenvolvimento do sistema de mensuração envolve a avaliação de sua acurácia utilizando objetos de dimensões pré-estabelecidas e a sua aplicação em áreas experimentais de cana-de-açúcar. São abrangidos dois períodos de estudo, sendo um em 2015 para a área I (0,77 ha) e o segundo em 2016 utilizando as áreas I e II (0,56 ha). A aquisição de dados ocorreu cerca de 10 dias antes da colheita e, em paralelo, foram realizadas as medidas de biometria das plantas. Em 2015 a produtividade foi estimada pela biometria e em 2016 ocorreu a pesagem do material para cada parcela das áreas I e II. Os resultados referentes à avaliação da acurácia do sistema de mensuração demonstraram erros de até 13,0%, o qual não compromete o seu desempenho. A partir dos procedimentos de aquisição e processamento de dados foi possível gerar a nuvem de pontos, realizar a filtragem de dados e extrair as medidas de alturas máxima, média e mediana da vegetação. A influência da vibração no conjunto de dados foi considerada mais expressiva para as condições da área I. A correlação entre o diâmetro de colmos e a produtividade estimada pela biometria na área I em 2015 foi de 0,80. Enquanto que, a correlação entre o diâmetro de colmos e a altura de vegetação indicada pelo sistema de mensuração foi moderada (r=-0,53). Em 2016, para a mesma área, a correlação entre as medidas de altura média e mediana de vegetação obtidas pelo sistema e a produtividade foi de 0,64. Para as condições da área II não foram verificadas correlações entre as medidas de biometria e as alturas de vegetação. O sistema de mensuração utilizando uma plataforma terrestre apresentou desempenho satisfatório em relação à capacidade de detecção da distribuição de plantas de cana-de-açúcar e condizente com as condições das áreas em ambos os períodos de estudo, porém a sua aplicação em áreas com pouca variabilidade espacial apresentou baixa capacidade preditiva de produção de biomassa de cana-de-açúcar.The economic participation of sugarcane (Saccharum spp.) is significant in Brazilian agribusiness, especially in the state of São Paulo. The yield monitoring for this crop is scarce of solutions consolidated at the research and commercial levels. Such monitoring assists for identification of spatial and temporal variability, as well as providing support to the agricultural management. As an alternative laser sensors, covered by LiDAR (Light Detection and Ranging) technology, have been used by aerial or terrestrial platforms for estimating grain crops yield such as corn and wheat, and for noninvasive forest monitoring. The objective of this study is to investigate the laser sensor applications for sugarcane in the pre-harvest period from development of a measurement system. The measurement system consists of a laser sensor, a Global Navigation Satellite System (GNSS) receiver, an inertial unit and a computer. The laser sensor emits light beams (905 nm) in the form of a single pulse in a 2D plane, from these beams the distance values between sensor and canopy were calculated during the trajectory of the agricultural vehicle. The GNSS receiver with RTK (Real Time Kinematic) signal was synchronized to the laser sensor to obtain the point cloud, which is characterized by the allocation of each point impacted by the light beam in the respective geographical coordinates. The inertial unit provides information related to the data influence of the vibration from oscillation in the transversal (roll), lateral (pitch) and longitudinal (yaw). The equipment were installed in a support of metallic structure in the agricultural tractor and connected to the computer through communication protocols. The development of the measurement system involves evaluation of its accuracy using objects of pre-established dimensions and its application in experimental areas of sugarcane. Two periods are covered by this study, one in 2015 for area I (0.77 ha) and the second in 2016 using areas I and II (0.56 ha). The data acquisition occurred about 10 days before sugarcane harvest and, in parallel, the biometrics measurements were carried out. In 2015 sugarcane yield was estimated by biometry and in 2016 material was weighed for each plot of areas I and II. The results regarding evaluation of the measurement system accuracy showed errors up to 13.0%, which does not compromise its performance. From the data acquisition and processing procedures, it was possible the point cloud generation, data filtering performing and extraction of some measurements as maximum, average and median heights of vegetation. The influence of the vibration on data set was considered more expressive for area I conditions. The correlation between stem diameter and yield estimated by biometry in area I in 2015 was 0.80. Meanwhile, the correlation between stem diameter and vegetation height indicated by the measurement system was moderate (r=-0.53). In 2016, for the same area, the correlation between measurements of average and median heights of vegetation obtained by the system and sugarcane yield was 0.64. For area II conditions no correlations were verified between biometrics measurements and vegetation height. The measurement system using a terrestrial platform presented a satisfactory performance in relation to the capacity of detection of sugarcane plants distribution and consistent with areas conditions for both periods of study, however its application in areas with low spatial variability presented reduced predictive capacity of biomass production of sugarcane.