Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"0205 Optical Physics"”.
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Atomic beam techniques in a rubidium vapour cell
… a sealed vapour cell. A velocity selective optical pumping scheme was implemented to enable the detection of atoms of a particular velocity class travelling between two separated laser beams. This represents a new spectroscopic technique, the usefulness of which has been demonstrated through …
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Temperature measurement using rare earth doped fibre fluorescence
Optical fibre sensors have been developed to measure a wide range of parameters and in many circumstances show significant advantages over conventional measurement techniques. This thesis investigates a relatively new method of measuring temperature using optical fibres, known as the fluorescence …
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Microscopic imaging in turbid media
… characteristics (e.g. scattering anisotropy, optical thickness and geometric thickness). The turbid media (samples) used in the work presented in this thesis consist of polystyrene microspheres and semi-skimmed milk suspensions. In particular the work presented in this thesis is concerned with …
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Birefringent Fabry-Perot sensors
… or strain. By using a highly birefringent optical fibre in their cavity, these sensors form two interferometers - one for each polarisation axis. As in the case of other fibre interferometers, each axial interferometer is extremely sensitive to temperature and strain. But this high …
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Remote detection of laser generated ultrasonics by fibre optic interferometer
… fibre optics. There is little problem in using optical fibres for delivery of high power Q-switched pulses to excite acoustic waves in target materials. However, the use of fibre optic interferometers in remote detection of these pulses presents very significant signal to noise problems. This …
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Near-field scanning optical microscopy with laser trapping
… of particle-trapped near-field scanning optical microscopy. This technique is unique in that it relies on the collection of scattered evanescent waves from a sample with a laser-trapped particle. In comparison with the other forms of near-field scanning optical microscopy with a tapered …
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Fibre optic sensor for speed measurement
… in potentially hazardous environments in which optical fibre sensors are more suited. In this thesis the development of a non-intrusive speed measurement sensor, based on optical technology is described. The optical fibre sensor described herein gives an almost instantaneous indication of the …
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A fibre optic based ranging sensor
… techniques have evolved from geometrical to bulk optical or radar methods. There is however a demand for low-cost short to medium range sensors, for operation in potentially hazardous environments, which may be satisfied by optical fibre based sensors. In this thesis the development of an optical …
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Low coherence fibre optic Fabry-Perot sensors suitable for multiplexed strain measurement
… interferometer (WLI) techniques to measure the optical path changes produced in the sensors by the application of strain. Since thermal effects also produce phase changes in the fibre Fabry-Perot interferometer (FFPI) which are indistinguishable from strain changes the investigations have …
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A new vibrational technique for measurement of stress variations in thin films
… literature. This thesis describes a simple all-optical technique for measurement of internal stress in thin films deposited in a vacuum system. The technique is based on a measurement of changes in the modal resonant vibrational frequencies of the substrate/film structure which are caused by …
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Determining rare earth dopant concentrations in optical fibres and waveguides
The fluorescence lifetimes of rare earth-doped fibres and waveguides were studied in this thesis to determine whether the fluorescence lifetime could be used as a means for determining the rare earth concentrations. The performance of rare earth-doped devices is dependent on many parameters, …
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Remote optical excitation and sensing of structural vibration
… is concerned with non-contact techniques for optical excitation of mechanical vibrations in structures and with the use of non-contact fibre optic interferometers for the measurement of parameters which characterise these mechanical vibrations. Taken together, the excitation and sensing …
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Characterisation of optical fibre amplifiers: amplifiers for the 632.8 nm He-Ne wavelength in praseodymium-doped ZBLAN
… in a praseodymium-doped fluorozirconate optical fibre at the 632.8 nm He-Ne wavelength, has been conducted. The optical gain is fundamentally related to the spectroscopic characteristics of praseodymium-doped in a fluorozirconate glass host together with optical fibre parameters, that …
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Low coherence fibre interferometry with a multi-wavelength light source
This thesis describes the results of study of the multi-wavelength low coherence fibre interferometry. The development and performance of the all-fibre interferometric measurement systems utilising multi-wavelength combination sources are described. Principal aspects of the low-coherence sensor …
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Lidar and infrared radiometer studies of stratocumulus clouds
This thesis comprises a study of marine stratocumulus clouds measured by ground-based Lidar and Infrared RADiometry (or LIRAD). The clouds were measured in northwestern Tasmania in the winter of 1993 and summer of 1995 during the Southern Ocean Cloud Experiment (SOCEX). The study done for this …
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Interferometric optical fibre sensor for highway pavements and civil structures
Optical fibres have been used for developing variety of sensing configurations for monitoring a wide range of parameters. This thesis presents the design, construction and characterisation of a new type of single-transducer optical fibre Weigh-ln-Motion (WIM) sensor. The sensor is based on an …
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Temperature and strain sensing using rare earth fluorescence and Bragg gratings in optical fibres
… on rare earth fluorescence and Bragg gratings in optical fibres. The development and performance of simultaneous temperature and strain measurement systems utilising a combined technique of the fluorescence intensity ratio and the Bragg wavelength shift are investigated.
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Microscopic characterisation of fibre Bragg gratings
… is the study of microscopic characterization of optical fibres and fibre Bragg gratings, by the use of a non-invasive microscopic technique, namely differential interference contrast microscopy. The thesis aims to provide detailed information on the structural and optical properties of optical …
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Microscopic characterisation of photonic devices
… presented in this thesis sets out to explore the optical properties of optical fibres by means of non-invasive microscopic techniques such as Differential Interference Contrast (DIC) microscopy. It seeks to provide the fibre optic industrial and research community with an alternative tool that is …
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Energy exchange processes in erbium-doped fluoride glasses
… interest has focused on diode-pumped lasers and optical waveguide amplifiers based on rare earth ions. This thesis is concerned with developing a model, which can explain the population and depopulation processes which are responsible for the spectroscopic behaviour of Er3+ ions in fluoride glass …
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