Tesi: "Interferometry"

1

Ho, Lap. "High precision short-baseline pointing system using GPS interferometry." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179435242.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Lemes, Andryos da Silva [UNESP]. "Novas configurações de interferômetros de quadratura e de técnicas de detecção de fase óptica baseadas em phase unwrapping." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/111112.

Testo completo

Abstract (sommario):

Made available in DSpace on 2014-12-02T11:16:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-03-27Bitstream added on 2014-12-02T11:20:53Z : No. of bitstreams: 1 000795995.pdf: 2794066 bytes, checksum: f46bd6b9d4e609f70fa6e80ae87f6cae (MD5) Interferômetros ópticos de saída única são muito sensíveis quando operam nas proximidades do ponto de quadratura de fase da sua curva característica de entrada e saída. Entretanto, as flutuações ambientais de baixa frequência produzem derivas aleatórias entre os caminhos ópticos do interferômetro que desviam o ponto quiescente da quadratura, levando ao fenômeno de desvanecimento de sinal. Através de processamento eletrônico de dois sinais interferométricos de saída, defasados a 90º entre si, consegue-se demodular o sinal independentemente das derivas ambientais. Esses interferômetros chamados de interferômetros de quadratura são amplamente utilizados em laboratórios de metrologia, porém, devido à grande quantidade de componentes ópticos normalmente envolvidos, são de difícil alinhamento e de elevado custo. Neste trabalho estuda-se a interferometria homódina de dois feixes em quadratura e as suas complexidades inerentes. Propõe-se uma nova arquitetura, baseada na configuração de Michelson, de alinhamento mais simples e de baixo custo. Descreve-se matematicamente o processo de obtenção dos sinais em quadratura deste arranjo. Também, se explora uma técnica capaz de obter dois sinais interferométricos em quadratura através da configuração tradicional de Michelson explorando-se a distribuição espacial do padrão de franjas. Desenvolve-se, ainda, um novo algoritmo de phase unwrapping aplicável como método de detecção de fase óptica, capaz de reconstruir a forma de onda de sinais de modulação e fornecer a diferença de fase estática entre os braços do interferômetro, quando o sinal de modulação possui valor médio nulo. Testes computacionais são realizados para corroborar na tarefa de evidenciar o potencial da técnica. Por meio do método de demodulação apresentado, em adição com o interferômetro proposto e da técnica explorada, realiza-se testes experimentais em um atuador piezoelétrico ... Optical interferometers with single outputs are very sensitive when operating close to the phase quadrature point of their input-output characteristic curves. However, low frequency environmental fluctuations generate random drifts between the optical paths of the interferometer that deviate the quiescent point from the quadrature condition. This problem causes the phenomenon called signal fading. By electronically processing these two interferometry output signals, shifted by 90º, it is possible to demodulate the signal regardless of environmental drift. These kinds of interferometers, known as quadrature interferometers, are widely used in metrology laboratories, but, due to the large amount of optical components, they are expensive and difficult to design. In this work a low cost homodyne interferometer with two output quadrature beams based on the Michelson configuration is studied, and the procedure to achieve the quadrature signals is mathematically described. Also, a recent technique, not widely known in the literature and that is able to obtain two quadrature signals by using the standard configuration of the Michelson interferometer is explored, exploiting the spatial distribution of the fringe pattern. A new method for optical phase shift demodulation based on phase unwrapping is developed. This approach is able to recover not only the modulation signal waveform, but can also calculate the static phase shift between the interferometer arms when the modulation signal has an average value equal to zero. The method also has the ability to demodulate signals which vary arbitrarily in time. Computational test were done aiming to demonstrate the technique potential. By using this new optical phase shift demodulation method, combined with the proposed interferometer and exploiting the spatial distribution of the fringe pattern, a piezoelectric flextensional actuator is characterized. Displacement versus drive voltage and frequency ...

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Lemes, Andryos da Silva. "Novas configurações de interferômetros de quadratura e de técnicas de detecção de fase óptica baseadas em phase unwrapping /." Ilha Solteira, 2014. http://hdl.handle.net/11449/111112.

Testo completo

Abstract (sommario):

Orientador: Cláudio Kitano Banca: Ricardo Tokio Higuti Banca: Ronny Calixto Carbonari Resumo: Interferômetros ópticos de saída única são muito sensíveis quando operam nas proximidades do ponto de quadratura de fase da sua curva característica de entrada e saída. Entretanto, as flutuações ambientais de baixa frequência produzem derivas aleatórias entre os caminhos ópticos do interferômetro que desviam o ponto quiescente da quadratura, levando ao fenômeno de desvanecimento de sinal. Através de processamento eletrônico de dois sinais interferométricos de saída, defasados a 90º entre si, consegue-se demodular o sinal independentemente das derivas ambientais. Esses interferômetros chamados de interferômetros de quadratura são amplamente utilizados em laboratórios de metrologia, porém, devido à grande quantidade de componentes ópticos normalmente envolvidos, são de difícil alinhamento e de elevado custo. Neste trabalho estuda-se a interferometria homódina de dois feixes em quadratura e as suas complexidades inerentes. Propõe-se uma nova arquitetura, baseada na configuração de Michelson, de alinhamento mais simples e de baixo custo. Descreve-se matematicamente o processo de obtenção dos sinais em quadratura deste arranjo. Também, se explora uma técnica capaz de obter dois sinais interferométricos em quadratura através da configuração tradicional de Michelson explorando-se a distribuição espacial do padrão de franjas. Desenvolve-se, ainda, um novo algoritmo de phase unwrapping aplicável como método de detecção de fase óptica, capaz de reconstruir a forma de onda de sinais de modulação e fornecer a diferença de fase estática entre os braços do interferômetro, quando o sinal de modulação possui valor médio nulo. Testes computacionais são realizados para corroborar na tarefa de evidenciar o potencial da técnica. Por meio do método de demodulação apresentado, em adição com o interferômetro proposto e da técnica explorada, realiza-se testes experimentais em um atuador piezoelétrico... Abstract: Optical interferometers with single outputs are very sensitive when operating close to the phase quadrature point of their input-output characteristic curves. However, low frequency environmental fluctuations generate random drifts between the optical paths of the interferometer that deviate the quiescent point from the quadrature condition. This problem causes the phenomenon called signal fading. By electronically processing these two interferometry output signals, shifted by 90º, it is possible to demodulate the signal regardless of environmental drift. These kinds of interferometers, known as quadrature interferometers, are widely used in metrology laboratories, but, due to the large amount of optical components, they are expensive and difficult to design. In this work a low cost homodyne interferometer with two output quadrature beams based on the Michelson configuration is studied, and the procedure to achieve the quadrature signals is mathematically described. Also, a recent technique, not widely known in the literature and that is able to obtain two quadrature signals by using the standard configuration of the Michelson interferometer is explored, exploiting the spatial distribution of the fringe pattern. A new method for optical phase shift demodulation based on phase unwrapping is developed. This approach is able to recover not only the modulation signal waveform, but can also calculate the static phase shift between the interferometer arms when the modulation signal has an average value equal to zero. The method also has the ability to demodulate signals which vary arbitrarily in time. Computational test were done aiming to demonstrate the technique potential. By using this new optical phase shift demodulation method, combined with the proposed interferometer and exploiting the spatial distribution of the fringe pattern, a piezoelectric flextensional actuator is characterized. Displacement versus drive voltage and frequency ... Mestre

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Nečesal, Daniel. "Fázové zobrazování pod difrakčním limitem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417067.

Testo completo

Abstract (sommario):

Tato diplomová práce se zabývá konstrukcí interferenčních zařízení pro výzkum měření fáze světla na mikro-strukturách a fáze plazmonů na nano-strukturách. V první kapitole je vybudován teoretický základ pro optiku a nano-fotoniku používané v budoucích kapitolách. Následně je popsána interference vln a jejich praktické použití pro prolomení difrakčního limitu pomocí holografie plazmonů. Prvním experimentální sestavou je Machův-Zehnderův holografický mikroskop. Je popsán způsob, jak ho sestavit z běžně dostupných součástek a jak je navržen ovládací software k jeho používání. Následně jsou popsány výsledky naměřené pomocí tohoto zařízení. V poslední kapitole se zaměříme na sestavení holografického SNOM přístroje pro studování plazmonů a jejich interference. Nejdříve popíšeme základní princip a navržení softwaru pro automatizaci měření, pro zrychlení vědeckých postupů. Nakonec předložíme výsledky měření mikroskopu.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Guo, Yifan. "Developments in moire interferometry: carrier pattern technique and vibration insensitive interferometers." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54181.

Testo completo

Abstract (sommario):

Due to the rapid expansion of applications of composite materials, investigations of their properties have greatly increased. Since theoretical and numerical methods have many limitations for anisotropic materials, experimental methods are sometimes the only way to answer the questions. It has been proved that moire interferometry is a powerful technique in the study of composite materials. The high sensitivity and resolution of a measurement technique is the key to determining the properties of a material which has a fine and complicated structure such as fiber reinforced composite laminates. In this paper, a carrier fringe method is introduced to increase the resolution of the fringe gradient in the moire technique. The ability of measurement is extended to the micromechanics region. High strain concentrations and the dramatic displacement variations can be determined by measuring the slopes of carrier fringes. Strain distributions across the plies (with the thickness of 125 μm) in graphite/epoxy composites and strain concentrations in the resin-rich zones (with the thickness of 10 μm) between neighboring plies are revealed by the carrier fringe technique. Three experiments are presented to show the effectiveness of the application of carrier fringes to resolve fringe gradients and obtain strains. The current moire technique is limited to the optical laboratory because it is extremely sensitive to the disturbance of the environment. A vibration with magnitude of 0.2 μm can completely wash out the contrast of a moire fringe pattern. The study has been done in moving moire interferometry off the optical table. Vibration insensitive moire systems are investigated to extend the moire technique to the tests of large structures and using testing machines for loading. Vibration problems are discussed and the new ideas for eliminating vibration effects are presented. Six representative schemes are analyzed and three of these systems are built to perform experiments in rough environments such as on a hydraulic testing machine. The results show the great success of these new systems. Ph. D.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Iacchetta, Alexander S. "Spatio-Spectral Interferometric Imaging and the Wide-Field Imaging Interferometry Testbed." Thesis, University of Rochester, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10936092.

Testo completo

Abstract (sommario):

The light collecting apertures of space telescopes are currently limited in part by the size and weight restrictions of launch vehicles, ultimately limiting the spatial resolution that can be achieved by the observatory. A technique that can overcome these limitations and provide superior spatial resolution is interferometric imaging, whereby multiple small telescopes can be combined to produce a spatial resolution comparable to a much larger monolithic telescope. In astronomy, the spectrum of the sources in the scene are crucial to understanding the material composition of the sources. So, the ultimate goal is to have high-spatial-resolution imagery and obtain sufficient spectral resolution for all points in the scene. This goal can be accomplished through spatio-spectral interferometric imaging, which combines the aperture synthesis aspects of a Michelson stellar interferometer with the spectral capabilities of Fourier transform spectroscopy. Spatio-spectral interferometric imaging can be extended to a wide-field imaging modality, which increases the collecting efficiency of the technique. This is the basis for NASA’s Wide-field Imaging Interferometry Testbed (WIIT). For such an interferometer, there are two light collecting apertures separated by a variable distance known as the baseline length. The optical path in one of the arms of the interferometer is variable, while the other path delay is fixed. The beams from both apertures are subsequently combined and imaged onto a detector. For a fixed baseline length, the result is many low-spatial-resolution images at a slew of optical path differences, and the process is repeated for many different baseline lengths and orientations. Image processing and synthesis techniques are required to reduce the large dataset into a single high-spatial-resolution hyperspectral image. Our contributions to spatio-spectral interferometry include various aspects of theory, simulation, image synthesis, and processing of experimental data, with the end goal of better understanding the nature of the technique. We present the theory behind the measurement model for spatio-spectral interferometry, as well as the direct approach to image synthesis. We have developed a pipeline to preprocess experimental data to remove unwanted signatures in the data and register all image measurements to a single orientation, which leverages information about the optical system’s point spread function. In an experimental setup, such as WIIT, the reference frame for the path difference measured for each baseline is unknown and must be accounted for. To overcome this obstacle, we created a phase referencing technique that leverages point sources within the scene of known separation in order to recover unknown information regarding the measurements in a laboratory setting. We also provide a method that allows for the measurement of spatially and spectrally complicated scenes with WIIT by decomposing them prior to scene projection.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Vieira, Marcio Alexandre Pinto. "Analise vibracional de viga engastada utilizando a tecnica de moire : um estudo de caso." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257093.

Testo completo

Abstract (sommario):

Orientador: Inacio Maria Dal Fabbro Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola Made available in DSpace on 2018-08-08T06:46:24Z (GMT). No. of bitstreams: 1 Vieira_MarcioAlexandrePinto_M.pdf: 3890763 bytes, checksum: ec176daee99c277e022ce62c1efe297e (MD5) Previous issue date: 2005 Resumo: O fenômeno de vibração é de ocorrência comum na mecânica, geralmente associado à membros estruturais assim como elementos de maquinas. Particularmente, no campo da engenharia agrícola, vibração vem associada à ferimentos em vegetais nas operações de campo, que claramente inclui colheita, transporte e processamento. A escolha de membros estruturais simples, como as viga engastada, para validar o método, quando uma estrutura mais complexa for ser considerada. O nome moiré tem sua origem na língua francesa, referindo-se ao padrão de onda formado. O fenômeno é gerado quando telas são sobrepostas, produzindo padrões de ondas ou franjas, que se movem quando suas posições relativas são alteradas. O método selecionado é chamado método geométrico de moiré, que consiste em projetar uma grade sobre a superfície do objeto em estudo e superpor a foto original e a grade deformada. Software's especificos são empregados na análise de imagens. O objetivo do presente trabalho é determinar o deslocamento transversal da linha elástica na Teoria da viga engastada de Euler-Bernoulli, excitada por um excitador eletromagnético, utilizado em analise modal, utilizando a técnica de moiré descrita acima Abstract: Vibration phenomena are of common occurrence in mechanics, generally associated to structural members as well as to machine elements. Particularly, in the field of agricultural engineering, vibration comes also associated to vegetable bruising during field operations, which clearly includes harvesting, transportation and processing. The selection of a simple structural member as a cantilever beam to support the utility of a moiré technique in studying vibration analysis is to validate the method when more complex structures are being considered. Vibration modes of a cantilever beam are easily determined by analytical methods. The name moiré has its origin in the French language, referring to wave like pattern. The phenomenon is generated when screens superposed, producing wave like patterns or fringes, which move when its relative positions are displaced. The selected method is named geometric moiré, which consists in projecting a grid onto the object in study and superposing both, the original and the deformed grid. Specific software's were employed in the image analysis. The objective of the present work is to determine the transversal displacement of the elastic line of Euler-Bernoulli cantilever beam being excited by an electromagnetic varying field using the moiré technique described above. Keywords: vibration, geometric moiré Mestrado Projetos, Desenvolvimento e Otimização de Maquinas Agricolas Mestre em Engenharia Agrícola

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Bins, Leonardo Sant'Anna 1961. "Estimação de fase absoluta e de linha de base em radar interferométrico de abertura sintética com múltiplas antenas." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261023.

Testo completo

Abstract (sommario):

Orientador: Max Henrique Machado Costa Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação Made available in DSpace on 2018-08-24T13:29:51Z (GMT). No. of bitstreams: 1 Bins_LeonardoSant'Anna_D.pdf: 7799361 bytes, checksum: 9e2474fa080f4e6f30dd2971af9cd670 (MD5) Previous issue date: 2014 Resumo: Dois problemas importantes na interferometria SAR (Synthetic Aperture Radar) são a estimação da fase absoluta e das linhas de base. O conhecimento preciso da fase absoluta e das linhas de base são fundamentais para a geração de modelos digitais de superfície ou terreno com alta precisão planimétrica e altimétrica. A estimação de fase absoluta consiste de duas etapas. A primeira etapa efetua o desdobramento da fase, o qual recupera a fase absoluta com os correspondentes múltiplos de 2?. A segunda etapa consiste na estimação do deslocamento de fase, causada pela combinação de erros de sincronização no sistema de aquisição de dados com erros de processamento da Interferometria SAR (InSAR). A estimação de linha de base consiste na determinação da posição da antena escrava relativa à posição da antena mestre (ou antena de referência). As contribuições desta tese consistem na concepção e na implementação de três métodos que se valem de múltiplas antenas (múltiplos interferogramas) para resolver esses dois problemas, como se segue. O primeiro método efetua o método de desdobramento de fase pontual, através do desdobramento de fase iterativo dos interferogramas, seguido da fusão dos mesmos, usando máxima verossimilhança. O segundo método refina a estimação de fase absoluta através da estimação do deslocamento de fase usando múltiplas antenas não colineares. O método se baseia na minimização da distorção geométrica (ou erro relativo) induzida pelo processamento com a presença de deslocamentos de fase com valores diferentes do verdadeiro. Uma das vantagens do método é que ele dispensa a instalação de refletores de canto na região imageada. Por último, um algoritmo do tipo Monte Carlo foi desenvolvido para a determinação das posições relativas das antenas escravas em relação à antena mestre. O método utiliza refletores de canto, cujas posições em campo são conhecidas, para reduzir o erro quadrático médio Abstract: Two important issues in SAR interferometry (InSAR) are absolute phase and baseline estimation. The precise knowledge of these parameters is essential for the production of digital elevation models with high accuracy. The absolute phase estimation can be done in two steps. The first step performs the unwrapping of the phase, which retrieves the 2? multiples of the phase. The second step estimates the phase offset caused by a combination of errors in the acquisition system and in SAR interferometry (InSAR) processing. The baseline estimation determines the relative position of the slave antenna with respect to the master antenna (reference antenna). The contributions of this thesis consist in the design and implementation of three methods that use multiple antennas to address the above issues. The first method performs the unwrapping of the phase in a pixel based fashion, by iteratively unfolding the phase corresponding to each interferograma, followed by maximum likelihood fusion of the unwrapped phases. The second method refines the absolute phase estimation of the first step by incorporating a phase offset estimation based on multiple, noncollinear, antennas. This is achieved by minimizing the geometrical distortion (relative error) in the reconstructed digital elevation model induced by erroneous phase offsets in the interferograms. One advantage of this method is that it does not require the deployment of corner reflector in the area to be imaged. Lastly, the third method deals with baselines estimation. A baseline is determined by the relative positions of the slave and master antennas. The estimation is performed with a greedy stochastic algorithm of Monte Carlo type which uses corner reflectors with precisely known positions. A new position for the slave antenna is accepted when the mean square error of the corner reflector positions is reduced Doutorado Telecomunicações e Telemática Doutor em Engenharia Elétrica

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Ramasubramanian, Srikanth. "Design and development of a portable Moiré interferometer." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3460.

Testo completo

Abstract (sommario):

Thesis (M.S.)--West Virginia University, 2004. Title from document title page. Document formatted into pages; contains x, 132 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 131).

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Featonby, Paul. "Atom interferometry." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390459.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Otto, Markus [Verfasser]. "Time-delay interferometry simulations for the laser interferometer space antenna / Markus Otto." Hannover : Technische Informationsbibliothek (TIB), 2016. http://d-nb.info/1118740769/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Lewitton, Neil. "Multiple transducer synthetic aperture sonar interferometry for emulating SAR interferometry." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5184.

Testo completo

Abstract (sommario):

Includes bibliographical references (p. 77-78 ). Multiple transducer single-pass synthetic aperture sonar interferometry in air is a technique that can emulate topographic mapping techniques that have not been implemented using radar or that are relatively expensive and difficult to obtain in practice for the radar engineer who wishes to test algorithms using suitable data. This dissertation describes the implementation of a 40 kHz synthetic aperture sonar for acquiring radar-like data. Investigations into beamformed synthetic aperture sonar images as well as multiple-baseline sonar interferons resulting from imaging a variety of scenes are presented in this thesis.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Kitano, Cláudio. "Métodos inéditos de interrogação óptica e suas aplicações na medição de grandezas físicas." Ilha Solteira, 2016. http://hdl.handle.net/11449/149249.

Testo completo

Abstract (sommario):

Banca: Amílcar Careli César Banca: Josemir Coelho Santos Banca: Marco Isaías Alayo Chávez Banca: Aparecido Augusto de Carvalho Banca: Ricardo Tokio Higuti Resumo: Neste Texto Sistematizado, o candidato a Livre Docente expõe os principais resultados alcançados em sua trajetória após o doutorado, em termos de atividades de ensino, extensão, administrativas e de pesquisa. Ênfase especial é destinada à análise crítica das atividades de pesquisa e orientação de dissertações e teses junto ao Programa de Pós-Graduação em Engenharia Elétrica - PPGEE, da FE-IS UNESP. O enfoque principal da pesquisa refere-se à proposição teórica e experimental de novas técnicas de detecção de fase óptica empregando-se interferometria laser, e suas aplicações na medição de deslocamentos microscópicos, na caracterização de atuadores piezoelétricos flextensionais e em medições de tensões elétricas elevadas. A motivação para a realização da pesquisa, a exposição dos desafios e as soluções propostas são discutidas. Inserções em outras áreas, que envolvam sensores e sistemas ópticos, bem como, a cooperação com grupos de pesquisas afins, internos e externos à FE-IS UNESP, são apresentadas. No final, discutem-se as pesquisas atuais e as perspectivas futuras

Gli stili APA, Harvard, Vancouver, ISO e altri

14

McMorran, Benjamin James. "Electron Diffraction and Interferometry Using Nanostructures." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194029.

Testo completo

Abstract (sommario):

Here it is demonstrated that nanofabricated structures can be used as electron optical elements in new types of electron interferometers. This enables novel investigations with electrons analogous to experiments in light and atom optics. Far field diffraction from a single nanograting is used to examine the force on a charge moving in close proximity to a surface. Near field diffraction from the nanograting is investigated in a Talbot interferometer. It is found that electron waves form replicas of the grating in free space, and these replicas can be de-magnified using illumination by a converging beam. An electron Lau interferometer has the same grating configuration as the Talbot interferometer, but uses spatially incoherent beams that give rise to drastically different interference behavior. A single optical theory is developed to efficiently model a variety of grating interferometers under a diverse set of illumination conditions, and it is used to understand the experiments described here. Applications for these new interferometers are discussed, as well as possible directions for future research.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Halliday, David Fraser. "Surface wave interferometry." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3976.

Testo completo

Abstract (sommario):

This thesis concerns the application of seismic interferometry to surface waves. Seismic interferometry is the process by which the wavefield between two recording locations is estimated, resulting in new recordings at one location as if a source had been placed at the other. Thus, in surface-wave interferometry, surface waves propagating between two receiver locations are estimated as if one receiver had recorded the response due to a source of surface-wave energy at the other receiver. In global and engineering seismology new surface-wave responses can allow for imaging of the subsurface, and in exploration seismology it has been proposed that these new surface-wave responses can allow for the prediction and removal of socalled ground-roll (surface waves that are treated as noise). This thesis presents a detailed analysis of surface-wave interferometry: using a combination of modelling studies, real-data studies, and theoretical analyses the processes involved in the application of interferometry to complex (both multi-mode and scattered) surface waves are revealed. These analyses identify why surface waves are often dominant in the application of interferometry, where errors may be introduced in the application of surface-wave interferometry, and how interferometry may be processed in such a way as to minimise those (and other) errors. This allows for the proposal of new data-processing strategies in the application of seismic interferometry to surface waves, potentially resulting in improved surface-wave estimates. Much of the work in this thesis focuses on the use of seismic interferometry to predict and subtract surface waves in land-seismic exploration surveys. Using insights from the presented analyses it is shown that seismic surface waves can be successfully predicted and removed from land-seismic data using an interferometric approach. However, the work in this thesis is not only limited to applications in exploration seismology. In addition to the ground-roll removal method, improved estimates of higher-mode and scattered surfaces waves may allow for more advanced imaging algorithms to be used in conjunction with seismic interferometry. Also, as a consequence of the analysis presented a Generalized Optical Theorem for Surface Waves is derived. This highlights a link between seismic interferometry and the optical theorem and may allow for further application of optical theorems in seismology.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Brown, William O. J. "MF radar interferometry." Thesis, University of Canterbury. Physics and Astronomy, 1992. http://hdl.handle.net/10092/8142.

Testo completo

Abstract (sommario):

This thesis describes the development, operation and observations of interferometry experiments on two medium frequency spaced antennae radar operated by the Department of Physics and Astronomy of the University of Canterbury; the 2.4 MHz radar at Birdlings Flat near Christchurch, New Zealand, and the 2.9 MHz radar at Scott Base on Ross Island in the Antarctic. These radars are of a standard design and detect scattering from the D and lower E regions of the ionosphere in the mesosphere and lower thermosphere. The interferometry techniques used were those of temporal, spatial and frequency domain interferometry which provide information on Doppler shifting and the directional and radial distribution of backscattered signals received by the radars. This project represents the first time that these techniques have been operated together on radars of the type used in this project. The techniques were also carried out in conjunction with the standard procedures used on these radars, that of Spaced Antennae Drifts with Full Correlation Analysis (FCA). Various forms of interferometric analyses were carried out and comparisons were made between the results of interferometric analyses and those of more conventional techniques. For example a study was made of the relationship between interferometric and FCA velocities in which it was found that there was good agreement between the two methods, particularly when the scattering region does not change rapidly as it moves. Other analysis techniques investigated included examination of the angular distribution of scattering and aspect sensitivity, the statistical distributions of scattered signals, post beam steering, vertical velocities and momentum fluxes. Frequency domain interferometry provided enhanced measurement of range and the scattering depth or distribution of range of scattered signals. Measurements of scattering depth clearly identified examples of thin layers or localized scatter. These localized scattering events appeared to be associated with either steady flow or long period variations in steady flow, for example with the semidiurnal solar tide. Aside from these events much of the scatter was observed to be anisotropic and also appeared to originate from a number of distributed scattering centres spread horizontally and vertically in a manner consistent with Fresnel scattering models.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Holloway, Alan James. "High-sensitivity interferometry." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/32721.

Testo completo

Abstract (sommario):

High-sensitivity interferometric techniques are considered for non-destructive testing applications. The methods enable quantitative measurement of optical path variations, resulting from dynamic changes within the test object.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Arain, Muzamil Arshad. "INTERFEROMETRY-BASED FREE SPACE COMMUNICATION AND INFORMATION PROCESSING." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3304.

Testo completo

Abstract (sommario):

This dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in the form of holography can be exploited to realize a novel optical scanner called Code Multiplexed Optical Scanner (C-MOS). The C-MOS features large aperture, wide scan angles, 3-D beam control, no moving parts, and high beam scanning resolution. A C-MOS based free space optical transceiver for bi-directional communication has also been experimentally demonstrated. For high speed, large bandwidth, and high frequency operation, an optically implemented reconfigurable RF transversal filter design is presented that implements wide range of filtering algorithms. A number of techniques using heterodyne interferometry via acousto-optic device for optical path length measurements have been described. Finally, a whole new class of interferometric sensors for optical metrology and sensing applications is presented. A non-traditional interferometric output signal processing scheme has been developed. Applications include, for example, temperature sensors for harsh environments for a wide temperature range from room temperature to 1000 degree C. Ph.D. Optics and Photonics Optics

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Stickney, James Arthur. "A theoretical analysis of Bose-Einstein condensate based beamsplitters, interferometers, and transistors." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-032708-124639/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Ito, Masahiro. "Search for supernova induced gravitational wave bursts with optimal filter technique on LIGO science data /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1188882241&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.

Testo completo

Abstract (sommario):

Thesis (Ph. D.)--University of Oregon, 2006. Typescript. Includes vita and abstract. Includes bibliographical references (leaves 113-116). Also available for download via the World Wide Web; free to University of Oregon users.

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Coelho, João de Abreu Barbosa 1984. "Interferência quântica com objetos complexos : o efeito dos graus de liberdade internos." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277248.

Testo completo

Abstract (sommario):

Orientador: Amir Ordacgi Caldeira Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin Made available in DSpace on 2018-08-11T11:04:40Z (GMT). No. of bitstreams: 1 Coelho_JoaodeAbreuBarbosa_M.pdf: 865659 bytes, checksum: f3befbe4283d2213924fdc6a38fda3e0 (MD5) Previous issue date: 2008 Resumo: Nesta dissertação, analisamos o efeito dos graus de liberdade internos de um objeto na dinâmica do seu centro de massa visando a determinar sua relevância para processos de descoerência em experimentos de fenda dupla. Mostramos que esses graus de liberdade se acoplam ao centro de massa na presença de um potencial que quebra a invariância translacional do sistema, e assim fazendo, funcionam como um ambiente que evolui em conjunto com o centro de massa do objeto. Utilizando uma abordagem de espalhamento, calculamos o operador densidade do sistema composto de centro de massa e coordenadas relativas na aproximação de Born para espalhamentos elásticos. Argumentamos como esse operador densidade nos da informção sobre os processos inelásticos e concluímos que, dentro da aproximação de Born, limitações geométricas impedem que os graus de liberdade internos do objeto atuem como um fator relevante para a descoerência Abstract: In this work, we analyze the effect of an object's internal degrees of freedom on its center of mass dynamics in order to determine its relevance to decoherence processes in double slit experiments. We show that these degrees of freedom couple to the center of mass in the presence of a potential that breaks the translational invariance of the system, and in so doing, act as an environment that evolves together with the object's center of mass. Using a scattering approach, we compute the density operator of the system composed of its center of mass and relative coordinates, in the Born approximation, for elastic scattering. We argue how this density operator gives us information about inelastic processes and conclude that, within the Born approximation, geometric constraints prevent the internal degrees of freedom from acting as a relevant factor for decoherence Mestrado Física Clássica e Física Quântica : Mecânica e Campos Mestre em Física

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Preto, André de Oliveira. "Caracterização de materiais por interferometria holografica em cristais fotorrefrativos utilizando lasers de diodo multimodo." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-20072009-094804/.

Testo completo

Abstract (sommario):

Este trabalho apresenta o estudo e o desenvolvimento de dois arranjos de interferometria holográfica utilizando como meio de registro holográfico cristais fotorrefrativos de Bi12TiO20 (BTO). O primeiro arranjo utiliza dois lasers de diodo sintonizáveis, emitindo em comprimentos de onda diferentes, em torno de 660 nm. Neste caso, a imagem holográfica do objeto estudado surge coberta de franjas de interferência que descrevem o relevo de sua superfície. O comprimento de onda sintético, que define a resolução do sistema na análise de superfícies, foi ajustado de modo a adequá-lo ao relevo da superfície estudada. A superfície de dois circuitos integrados e o relevo de uma moeda foram analisados, através de métodos de deslocamento de fase. O segundo arranjo gerou imagens holográficas e interferogramas, também com cristais BTO, através da montagem de Denisiuk para holografia de reflexão. Através da incorporação de um divisor de feixes polarizante, conseguiu-se melhorar a qualidade das imagens holográficas e reduzir o ruído. Medidas de deformação e vibração em pequenos objetos foram realizadas, assim como o estudo da dependência da intensidade do sinal holográfico sobre a orientação do cristal BTO. This work presents the study and the development of two optical setups using Bi12TiO20 (BTO) photorefractive crystals for holographic interferometry. The first one employs two tunable diode lasers emitting at slightly different wavelengths around 660 nm. In this case, the holographic image of the studied object appears modulated by interference contour fringes. The resulting synthetic wavelength which determines the system resolution was selected in order to make it suitable for measuring the surface relief. The surfaces of two integrated circuits and a coin were analyzed with the help of phase shifting methods. The second BTO-based setup generated holographic images and interferograms through the Denisiuk scheme for reflection holography. The interferogram visibility and the optical noise were significantly reduced by using a polarizing beam splitter. Deformation and vibration measurements were performed, and the dependence of the reconstructed wave intensity on the BTO crystal orientation was studied as well.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Ferreira, Merilyn Santos. "Microscopia interferométrica holográfica para a caracterização de microtransdutores." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-14122014-111144/.

Testo completo

Abstract (sommario):

A finalidade deste trabalho é aplicar a técnica de holografia em cristais fotorrefrativos para o estudo de propriedades mecânicas de microdispositivos, garantindo ainda a obtenção de uma geometria de arranjo holográfico simples e compacto. Foram feitas a análise de vibração e a análise de deformação de microdispositivos por meio da interferometria de média temporal e de dupla exposição, respectivamente. Como fontes de luz, foram utilizados diodos laser emitindo em 660nm, e um He-Ne laser emitindo em 632,8nm. Como meio fotorrefrativo de registro holográfico foi utilizado o cristal Bi12TiO20, (BTO) da família das selenitas. Foi proposto um arranjo óptico de holografia de reflexão do tipo Denisiuk, e a este arranjo foi adicionado um conjunto de lentes objetiva e ocular para formar uma configuração de microscópio composto, com o objetivo de obterem-se imagens holográficas de objetos de dimensões microscópicas. A gravação e a reconstrução do holograma se deram simultaneamente, devido à associação do cristal fotorrefrativo a uma câmera CMOS. Desta maneira, a observação dos hologramas foi feita em tempo real. Foram feitas, inicialmente, imagens de dupla exposição de piezorresistores MEMS (microelectromechanical systems), de geometria reduzida (2,96 x 0,6 mm2), e de dispositivos CMUT (Capacitive Micromachined Ultrasonic Transducers) com 640m de diâmetro. Através desta técnica foi possível medir deslocamentos de 0,33m a 4,3m. Foram obtidos também interferogramas de média temporal de cerâmicas e transdutores piezoelétricos, porém, iluminando apenas pequenas regiões destes objetos. Estas imagens mostraram qualidade razoável, indicando que é possível aplicar a técnica de interferometria em média temporal para objetos com amplitude de vibração entre 0,12m e 1,7m. Para investigar as potencialidades microscópicas foram feitas imagens de padrões de teste de resolução, onde foi possível visualizar estruturas com geometrias entre 2mm e 20m. The aim of this work is to apply photorefractive crystals holography technique for the study of mechanical properties of micro-devices; it ensures obtaining a simple and compact geometry of holographic setup. Vibration and deformation analyses of micro-devices were performed using time average and double exposure interferometry, respectively. As light sources, it was used diode lasers emitting at 660nm, and He-Ne laser emitting at 632.8nm. As photorefractive holographic recording medium was used Bi12TiO20 (BTO) crystal, family of selenites. An optical setup of Denisiuk-type reflection holography was proposed, and this setup was added a set of objective and eyepiece lenses to form a compound microscope configuration, in order to obtain holographic images of objects with microscopic dimensions. Recording and reconstruction of the hologram occurred simultaneously, due to the combination of the photorefractive crystal to a CMOS camera. Thus, holograms observation occurs in real time. It was initially performed double exposure images of MEMS (microelectromechanical systems) piezoresistors, with reduced geometry (2.96 x 0.6 mm2), and CMUT (capacitive micromachined ultrasonic transducers) devices with 640m diameter. By this technique was possible measure displacements of 0.33m to 4.3m. Time average interferograms of Ceramics and piezoelectric transducers were also obtained, however, it illuminating only small regions of these objects. These images showed reasonable quality, indicating that it is possible apply the time average technique for objects with vibration amplitude between 0.12m e 1.7m. In order to investigate the microscopic potentialities images of resolution test chart were done, where it was possible to visualize structures with geometries between 20 m and 2mm.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Goltsman, Alexander Mark. "Three Dimensional Interferometric Imaging at Terahertz Frequency for Concealed Object Detection." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/36351.

Testo completo

Abstract (sommario):

This project was born out of the work performed by a group of researchers at the New Jersey Institute of Technology (NJIT) [1] [2] [3] working on interferometric imaging with a spiral array. Their investigation stopped at two dimensional imaging with a two dimensional array. In this thesis, their idea was developed further into the significantly more complex imaging with a three dimensional array. The general design of the NJIT [1] [2] [3] experiment was reproduced, studied, and modified in a manner that was theorized to enhance the experiment with the added ability to perform three dimensional imaging. The NJIT team [1] [2] [3] has developed their experiment to where they were able to accurately perform two dimensional imaging of two sources of equal intensity located at different distances from a spiral array. In this thesis, the equations used for two dimensional imaging are extrapolated into a three dimensional array application. This three dimensional imaging concept is simulated with MATLAB and the results presented and compared to the NJIT experimental results. [1] [2] [3] A proof of concept physical experiment is conducted and the results are compared to the MATLAB simulation. The results show that additional spatial information can be obtained from a three dimensional array that can enhance the information gleaned from images. Master of Science

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Liu, Xiaojun. "A polarized lateral shearing interferometer and application for on-machine form error measurement of engineering surfaces /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20LIUX.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Bunkowski, Alexander. "Laser interferometry with gratings." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=984692312.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Krajewski, Joseph E. "Bridge inspection and interferometry." Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050406-092613/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Neutze, Richard. "Acceleration and optical interferometry." Thesis, University of Canterbury. Physics, 1995. http://hdl.handle.net/10092/6569.

Testo completo

Abstract (sommario):

The influence of acceleration on a number of physical systems is examined. We present a full relativistic treatment of a simple harmonic oscillator with relativistic velocities. The line element for Schwarzschild geometry is expanded in a set of Cartesian coordinates and is shown to be locally equivalent (neglecting curvature) to the line element of a linearly accelerating frame of reference. We consider the rate of a linearly accelerating quantum mechanical clock and the measurement of frequency by non-inertial observers, requiring this measurement to be of finite duration. These analyses demonstrate the standard measurement hypothesis for accelerating observers only approximates the physical behaviour of these systems. We derive the output of an optical ring interferometer in a variety of experimental contexts. A full relativistic reanalysis of the modified Laub drag experiment of Sanders and Ezekiel is performed, correcting a number of errors in their work and giving an overall discrepancy between experiment and theory of 1300 ppm. We examine the behaviour of a ring interferometer containing an accelerating glass sample. Our analysis predicts sideband structure will arise when a glass sample is oscillated along one arm of a Mach-Zehnder interferometer and the resulting output Fourier analysed. We also predict a resonant cavity containing a linearly accelerating glass sample will display optical ringing. A rigorous analysis of a ring interferometer with angular acceleration is presented. This predicts a resonant cavity with angular acceleration will also display optical ringing and demonstrates the beat frequency in a ring laser with angular acceleration is the instantaneous Sagnac beat frequency. Finally, we analyse the optical output of a rotating ring laser with one mirror oscillating, predicting sideband structure in spectra obtained from Fourier analysis of the beat between the opposite beams, and the beat between adjacent modes when the laser has multimode operation.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Stock, Michael. "Broadband interferometry of lightning." Thesis, New Mexico Institute of Mining and Technology, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3684400.

Testo completo

Abstract (sommario):

A lightning interferometer is an instrument which determines the direction to a lightning-produced radio point source by correlating the signal received at two or more antennas. Such instruments have been used with great success for several decades in the study of the physical processes present in a lightning flash. However, previous instruments have either been sensitive to only a narrow radio bandwidth so that the correlation can be done using analog hardware, or have been sensitive to a wide bandwidth but only recorded a short duration of the radiation produced by a lightning flash. In this dissertation, a broad bandwidth interferometer is developed which is capable of recording the VHF radio emission over the entire duration of a lightning flash. In order to best utilize the additional data, the standard processing techniques have been redeveloped from scratch using a digital cross correlation algorithm. This algorithm can and does locate sources as faint as the noise level of the antennas, typically producing 100,000 or more point source locations over the course of a lightning flash. At very low received power levels, the likelihood that a signal received at the antenna will be affected by the environmental noise is substantially higher. For this reason, the processing allows for the integration windows of the cross correlation to be heavily overlapped. In this way, the location of each event can be based on a distribution of windows. Further, noise identification techniques which leverage the heavily overlapped windows have been developed based on: the closure delay, the standard deviation, the correlation amplitude, and the number of contributing windows. The filtration techniques have proven to be very successful at identifying and removing mis-located sources, while removing the minimum number of low amplitude sources which are well located. In the past, lightning interferometers have been limited to using only two perpendicular baselines to determine the direction to each point source. Additional techniques are developed in this dissertation for efficiently computing the image of a point source in the sky using an arbitrary number of antennas in an arbitrary configuration. The multiple baseline techniques further improves the sensitivity and accuracy of the locations provided by broadband interferometers. To demonstrate the usefulness of broadband interferometers, the activity of 6 flashes spanning a diverse selection of lightning flash types are examined in this dissertation. This includes detailed analysis of negative stepped leaders, positive un-stepped leaders, K-changes, and fast positive breakdown. Initial breakdown pulses which are seen at the beginning of the flash are found to be no different than horizontal negative leader steps seen later in the flash. Evidence is found that positive leaders produce VHF radiation, as opposed to all of the radiation in the positive breakdown region being produced by retrograde negative breakdown. The time resolved three-dimensional velocity of 47 K-changes occurring in two flashes is measured. And finally, fast positive breakdown is characterized and found to be produced by a positive streamer process instead of a leader process. Observations made with the instrument showcase the capabilities of a continuous sampling broadband interferometer. The instrument makes possible measurements which were difficult or impossible to obtain in the past, and the preliminary observations allude to many exciting scientific findings to come.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Huang, Jen-Rong. "Optoelectronic speckle shearing interferometry." Thesis, Cranfield University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309680.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Atcha, Hashim. "Optoelectronic speckle pattern interferometry." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282405.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Johnson, N. "Towards single electron interferometry." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1569542/.

Testo completo

Abstract (sommario):

There have been many studies and suggested technological applications using the two dimensional electron system in the GaAs/AlGaAs heterostructure. These have mostly focused on the behaviour of electrons propagating at or close to the Fermi Energy. More recently, one such application of this two dimensional system is for an electron pump, which isolates electrons from the two dimensional electron gas and pumps them individually at energies typically 100 meV above the Fermi energy, using surface gates to create a dynamic quantum dot. This energy regime had been previously unobtainable. We can utilise the high accuracy output of the pump - consistency that each pumped electron has the same properties, to study fundamental single particle physics, and work towards technological schemes, at this high energy. In this work we set out to continue and extend the previous work in this fi eld. We present new measurements that detail an electron detector barrier that we can use both as a sampling oscilloscope, with a bandwidth approaching 100 GHz, or to measure the wavepacket properties of electrons, including their energy and time of arrival with high resolution. After developing and establishing the electron detector, we detail a series of experiments that utilise it to measure the electron velocity, scattering mechanisms and wavepacket size. We show this work maps consistently to theory, and further, we begin to demonstrate control of the electron wavepacket, with the possibility that this hot electron system could have future technological applications. This is all put together in the construction of an interferometer, which seeks to complete our understanding of electrons in this system by measuring coherence of the wavefunction, a key step to demonstrating construction of a prescribed state.

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Harasaki, Akiko. "Improved vertical scanning interferometry." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289148.

Testo completo

Abstract (sommario):

Vertical scanning interferometers are routinely used for the measurement of optical fiber connectors. There are increasing needs for measurements of such items as machined surfaces, contact lenses, paint texture, cell structure, and integrated circuit devices, to name a few. These structures have too much depth, or are too rough, to measure with standard interferometry methods. Phase-measurement interferometry methods are limited to surfaces that do not have any discontinuities larger than one quarter of the operating wavelength. On the other hand, vertical scanning interferometers can be very effective, even though they have low height resolution compared to that of phase-measurement interferometers. Improving the height resolution of vertical scanning interferometers from the point of hardware improvement and signal processing has been one of the major research interests in the surface metrology area. This work provides a new algorithm, which called here "PSI on the Fly" technique, as a solution for improving height resolution of vertical scanning interferometers. This dissertation begins with a review of white-light interference microscopes. The height and lateral resolutions are derived based on scalar diffraction theory. Next, various well-established. algorithms for finding a topographic map of the small object surface are discussed. The work proceeds with a discussion of the phase change upon reflection and its influence on the coherence envelope. Then phase measurement interferometry methods are reviewed. The emphasis is in errors in phase measurement resulting from using a white light source instead of a monochromatic light source as in the usual case. The following chapter describes and examines an often-observed artifact of vertical-scanning interferometry when applied to step heights. The artifact is called "bat wings" because of its appearance. The physical cause of the "bat wings" artifact is discussed through a diffraction model. The next chapter proposes an improved vertical-scanning interferometry algorithm. The method, called here "PSI on the Fly" technique, has been developed by combining regular vertical-scanning interferometry and a monochromatic phase-shifting interferometry technique. The PSI on the Fly technique improves the surface height resolution of vertical scanning interferometry to that of a phase-shifting interferometry measurement. In addition to the resolution improvement, the algorithm also successfully removes the "bat wings" artifact.

Gli stili APA, Harvard, Vancouver, ISO e altri

34

SALA, SIMONE. "QUPLAS: TOWARDS ANTIMATTER INTERFEROMETRY." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/596728.

Testo completo

Abstract (sommario):

Matter-wave interference has been observed for a wide range of objects: from electrons to neutrons and complex molecules. On the other hand, a double-slit-like experiment has never been carried out with positrons (the anti-particle of the electron) or with any other system containing antimatter. This thesis provides the theoretical foundations and experimental results of a Talbot-Lau interferometer specifically designed for this goal. Future applications include the measurement of the gravitational acceleration of positronium, to provide a test of the weak equivalence principle on a matter-antimatter symmetric, purely leptonic system.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Wu, Fang. "Study of fibre-optic interferometric 3-D sensors and frequency-modulated laser diode interferometry." Thesis, Liverpool John Moores University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313162.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Bhatia, Vikram. "Signal processing techniques for optical fiber sensors using white light interferometry." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192009-040440/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Pipia, Luca. "Polarimetric differential SAR Interferometry with ground-based sensors." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/6951.

Testo completo

Abstract (sommario):

Las técnicas de Interferometría Diferencial se basan en la combinación de varias imágenes SAR con distinta separación temporal y permiten la recuperación de las componentes lineales y no-lineales del proceso de deformación ocurrida en el entorno de interés durante el entero periodo de observación. Condición imprescindible para una correcta estimación de los fenómenos geodéticos es la elevada estabilidad de la plataforma que embarca el sensor SAR. Por esta razón, a nivel operativo se utilizan datos SAR satelitales. El objetivo de la Polarimetría SAR es describir el entorno de interés analizando las propiedades de la señal que éste dispersa cuando se utilizan diferentes combinaciones de polarización de las antenas transmisora y receptora, definidas canales polarimétricos. La polarimetría interferométrica SAR junta la capacidad de la polarimetría de separar mecanismos de dispersión independientes con la sensibilidad de la Interferometría a la altura de los correspondientes centros de fase, y permite describir la distribución volumétrica de los dispersores dentro de la escena observada. Debido a la falta de conjuntos de datos polarimétricos SAR satelitales que cubran tramos temporales suficientemente largos, hay aún un gran interés en las mejoras que la polarimetría podría aportar a técnicas ya consolidadas como las de Interferometría Diferencial. La actividad de investigación que se presentará en esta tesis doctoral abarca, por primera vez conjuntamente, las dos áreas de la Polarimetría SAR y de la Interferometría Diferencial utilizando el sensor radar terrestre de corto alcance (gbSAR) desarrollado por la Universitat Politècnica de Catalunyua (UPC). El trabajo constará de dos bloques principales. El primer bloque describirá las técnicas que se han desarrollado para convertir el sistema UPC gbSAR en un instrumento operativo y simplificar la utilización de sus adquisiciones, incluyendo la formulación matemática de los principios de funcionamiento del sistema, la cadena de procesado de los raw data y su calibración polarimétrica, los procedimientos de georeferenciación, y las técnicas de compensación de los artefactos atmosféricos presentes en sus medidas diferenciales. La segunda parte se ocupará de demostrar los beneficios que los datos SAR polarimétricos ofrecen respecto a la medición de un único canal polarimétrico para aplicaciones diferenciales. A fin de llevar a cabo esta tarea, se analizarán los datos gbSAR adquiridos durante una campaña de medidas de un año realizada en el pueblo de Sallent, en Cataluña, afectado por un fenómeno de subsidencia. En esta parte se analizarán tres temas principales. El primero es el comportamiento no estacionario en tiempo del entorno urbano bajo la geometría de observación del sensor terrestre. Se estudiarán en detalle los efectos de su inestabilidad y se propondrá una técnica de filtrado novedosa entallada a las propiedades de los blancos deterministas con el fin de preservar la información de la fase diferencial. El segundo tema abarca el problema de los efectos de troposfera en datos diferenciales con separación temporal superior al mes y de su separación de las variaciones de fase inducidas por el proceso de deformación. El tercer tema es la utilización de toda la información polarimétrica diferencial. Con fin de superar las limitaciones propias de las técnicas DInSAR clásicas, se propondrá un nuevo modelo polarimétrico de dispersión y se demostrarán las ventajas de la nueva formulación enseñando la mejor estimación del proceso de subsidencia en Sallent. En la parte final de este apartado se explorará también el potencial de las técnicas polarimétricas de optimización de la coherencia para aplicaciones diferenciales. Differential SAR interferometry (DInSAR) deals with the combination of multi-temporal SAR images for the estimation of the linear and non-linear components of the deformation process within an area of interest during the whole observation period. A high stability of the platform is required for a reliable estimation of the geodetic phenomena. Accordingly, space-borne SAR images are operatively employed for DInSAR estimation, air-borne DInSAR still constituting a challenging research issue. SAR Polarimetry aims at charactering the illuminated area through the analysis of its response under different combinations of transmitting and receiving antennas polarization, called polarimetric channels. The Polarimetric SAR Interferometry joins the capability of Polarimetry to separate independent scattering mechanisms and the sensitivity of Interferometry to the corresponding phase centers' elevation, making it possible to describe the volumetric distribution of the scatterers within the observed area. Owing to the lack of long-time collections of polarimetric space-borne SAR data, the studies carried out in this research field have been mainly based on air-borne acquisitions. Yet, there is a great expectation for the improvements that polarimetry may bring to assessed single-polarization techniques such as the DinSAR. The research described in this PhD dissertation fills for the first time the gap between SAR Polarimetry and SAR Differential Interferometry through the employment of an X-band ground-based SAR (gbSAR) sensor developed by the Remote Sensing Lab of the Universitat Politècnica de Catalunya (UPC). The work is divided into two main blocks. The first part deals with the algorithms that have been developed to make the UPC system operative and its acquisitions easy to use. Summarily, they include the mathematical formulation of the sensor's working principles, the raw data processing chain and the polarimetric calibration method, the geocoding procedures, and the techniques compensating for the atmospheric artefacts affecting gbSAR zero-baseline acquisitions. The second part is concerned with demonstrating the benefits that polarimetric SAR measurements provide with respect to single-polarization data for differential applications. In order to cope with this task, the data sets acquired during a one-year measurement campaign carried out in the village of Sallent, northeastern Spain, are analyzed. The experiment was focused on monitoring the subsidence phenomenon affecting a district of the village with the UPC gbSAR sensor. Three main issues are here argued. The first one is the time non-stationary behaviors characterizing the urban environment at X-band in the gbSAR observation geometry. Their effects are analyzed in detail and a novel non-stationary filtering technique tailored to deterministic scatterers' properties is introduced to preserve the differential phase information. The second one is the compensation of the troposphere changes in long-time span gbSAR differential interferograms. A new technique is worked out to effectively separate the differential phase variations due to the atmospheric artefacts from the deformation components. The third one is the use of the whole polarimetric differential information. A novel polarimetric differential scattering model is put forward to relax the constraints of an advanced DInSAR technique, the Coherent Pixel Technique, and to propose an innovative polarimetric approach. The advantages offered by Polarimetric DInSAR are demonstrated in terms of quality of the deformation-rate map describing the subsidence phenomenon in Sallent. In the end, the potentials of coherence-optimization techniques for the further improvement of the deformation process estimation are stressed.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Kočí, Radek. "Nejistoty interferometrických měření." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221119.

Testo completo

Abstract (sommario):

This diploma thesis deals with uncertainties of interferometric measurements and methods for their evaluation. In the theoretical part of the thesis, are described interferometers and interferometric measurement techniques. Furthermore, there is presented process of determining the measurement uncertainty using methods GUM and Monte Carlo. In the practical part of the thesis, there are these two methods are used for qualification of measurement uncertainty calculated for the specific interferometer.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Maňka, Tadeáš. "Konstrukce odměřovacího systému pro systém reaktivního iontového leptání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254215.

Testo completo

Abstract (sommario):

The aim of this work is to design fully working measuring system for the reactive ion etching system (RIE). The Michelson interfometer, previously developed in Ústav přístrojové techniky, v.v.i., is used in this work. The theoretical part is aimed at description of interferometric methods for precise measuring of length. In next part the etching proces with RIE is described. In practical part the testing system was constructed from the parts of Thorlabs company . The functionality was controlled with this system and the results of measuring were compared with the profilometer. In next step technical drawings were created and the whole system was made.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Rea, Alexander David. "Fast tip-tilt correction at the MROI and beyond." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708940.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Gordon, James Andrew. "Investigations in preparation for the Magdalena Ridge Observatory Interferometer." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648406.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Galeti, Jose Henrique [UNESP]. "Medição interferométrica de fase óptica através do método de segmentação do sinal amostrado." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/136008.

Testo completo

Abstract (sommario):

Made available in DSpace on 2016-03-07T19:20:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31. Added 1 bitstream(s) on 2016-03-07T19:24:36Z : No. of bitstreams: 1 000858535.pdf: 28861453 bytes, checksum: 71fa8b116bf6f4421bda43fd38b639c9 (MD5) A interferometria óptica é uma técnica amplamente reconhecida por sua sensibilidade extremamente elevada para a medição de diversas grandezas físicas. Em particular, quando aplicada à medição de deslocamentos mecânicos, permite a detecção de movimentos micrométricos e manométricos em sólidos. Nesta dissertação, emprega-se um interferômetro de Michelson homódino para caracterizar atuadores piezoelétricos flextensionais e manipuladores piezoelétricos multi-atuados. Este trabalho se insere na linha de pesquisas desenvolvidas no laboratório de Optoeletrônica da FEIS-UNESP, dedicadas à concepção de novas técnicas de detecção interferométrica de fase óptica. Dentre as diversas famílias de métodos publicados na literatura, os métodos de demodulação baseados na análise do espectro do sinal fotodetectado têm recebido especial atenção na FEIS. Embora eficientes, estes métodos apresentam resolução limitada, não são capazes de caracterizar atuadores não-lineares e operam somente com formas de onda senoidais. Propõe-se, nesta dissertação, um método de detecção de fase óptica denominado de Método de Segmentação do Sinal Amostrado, o qual é implementado no domínio do tempo. Este método, viabilizado pelos importantes recursos das técnicas de processamento digital de sinais, foi potencializado pela automatização das medições. Comparado aos procedimentos aplicados a experimentos anteriores na FEIS, cada medição equivale a 2500 medições no sistema antigo, permitindo o levantamento da curva de linearidade de um atuador com uma única medição. Além dessa, o método apresenta outras vantagens: é homódino, opera em malha-aberta, é imune ao desvanecimento do sinal, tem excelente resolução, ampla faixa dinâmica, opera com dispositivos não-lineares, detecta sinais com formas de onda arbitrárias, permite medir magnitude e fase do deslocamento... A interferometria óptica é uma técnica amplamente reconhecida por sua sensibilidade extremamente elevada para a medição de diversas grandezas físicas. Em particular, quando aplicada à medição de deslocamentos mecânicos, permite a detecção de movimentos micrométricos e manométricos em sólidos. Nesta dissertação, emprega-se um interferômetro de Michelson homódino para caracterizar atuadores piezoelétricos flextensionais e manipuladores piezoelétricos multi-atuados. Este trabalho se insere na linha de pesquisas desenvolvidas no laboratório de Optoeletrônica da FEIS-UNESP, dedicadas à concepção de novas técnicas de detecção interferométrica de fase óptica. Dentre as diversas famílias de métodos publicados na literatura, os métodos de demodulação baseados na análise do espectro do sinal fotodetectado têm recebido especial atenção na FEIS. Embora eficientes, estes métodos apresentam resolução limitada, não são capazes de caracterizar atuadores não-lineares e operam somente com formas de onda senoidais. Propõe-se, nesta dissertação, um método de detecção de fase óptica denominado de Método de Segmentação do Sinal Amostrado, o qual é implementado no domínio do tempo. Este método, viabilizado pelos importantes recursos das técnicas de processamento digital de sinais, foi potencializado pela automatização das medições. Comparado aos procedimentos aplicados a experimentos anteriores na FEIS, cada medição equivale a 2500 medições no sistema antigo, permitindo o levantamento da curva de linearidade de um atuador com uma única medição. Além dessa, o método apresenta outras vantagens: é homódino, opera em malha-aberta, é imune ao desvanecimento do sinal, tem excelente resolução, ampla faixa dinâmica, opera com dispositivos não-lineares, detecta sinais com formas de onda arbitrárias, permite medir magnitude e fase do deslocamento ...

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Galeti, Jose Henrique. "Medição interferométrica de fase óptica através do método de segmentação do sinal amostrado /." Ilha Solteira, 2012. http://hdl.handle.net/11449/136008.

Testo completo

Abstract (sommario):

Orientador: Claudio Kitano Banca: Ricardo Tokio Higuti Banca: Luiz Antônio Perezi Marçal Resumo: A interferometria óptica é uma técnica amplamente reconhecida por sua sensibilidade extremamente elevada para a medição de diversas grandezas físicas. Em particular, quando aplicada à medição de deslocamentos mecânicos, permite a detecção de movimentos micrométricos e manométricos em sólidos. Nesta dissertação, emprega-se um interferômetro de Michelson homódino para caracterizar atuadores piezoelétricos flextensionais e manipuladores piezoelétricos multi-atuados. Este trabalho se insere na linha de pesquisas desenvolvidas no laboratório de Optoeletrônica da FEIS-UNESP, dedicadas à concepção de novas técnicas de detecção interferométrica de fase óptica. Dentre as diversas famílias de métodos publicados na literatura, os métodos de demodulação baseados na análise do espectro do sinal fotodetectado têm recebido especial atenção na FEIS. Embora eficientes, estes métodos apresentam resolução limitada, não são capazes de caracterizar atuadores não-lineares e operam somente com formas de onda senoidais. Propõe-se, nesta dissertação, um método de detecção de fase óptica denominado de "Método de Segmentação do Sinal Amostrado", o qual é implementado no domínio do tempo. Este método, viabilizado pelos importantes recursos das técnicas de processamento digital de sinais, foi potencializado pela automatização das medições. Comparado aos procedimentos aplicados a experimentos anteriores na FEIS, cada medição equivale a 2500 medições no sistema antigo, permitindo o levantamento da curva de linearidade de um atuador com uma única medição. Além dessa, o método apresenta outras vantagens: é homódino, opera em malha-aberta, é imune ao desvanecimento do sinal, tem excelente resolução, ampla faixa dinâmica, opera com dispositivos não-lineares, detecta sinais com formas de onda arbitrárias, permite medir magnitude e fase do deslocamento... Abstract: A interferometria óptica é uma técnica amplamente reconhecida por sua sensibilidade extremamente elevada para a medição de diversas grandezas físicas. Em particular, quando aplicada à medição de deslocamentos mecânicos, permite a detecção de movimentos micrométricos e manométricos em sólidos. Nesta dissertação, emprega-se um interferômetro de Michelson homódino para caracterizar atuadores piezoelétricos flextensionais e manipuladores piezoelétricos multi-atuados. Este trabalho se insere na linha de pesquisas desenvolvidas no laboratório de Optoeletrônica da FEIS-UNESP, dedicadas à concepção de novas técnicas de detecção interferométrica de fase óptica. Dentre as diversas famílias de métodos publicados na literatura, os métodos de demodulação baseados na análise do espectro do sinal fotodetectado têm recebido especial atenção na FEIS. Embora eficientes, estes métodos apresentam resolução limitada, não são capazes de caracterizar atuadores não-lineares e operam somente com formas de onda senoidais. Propõe-se, nesta dissertação, um método de detecção de fase óptica denominado de "Método de Segmentação do Sinal Amostrado", o qual é implementado no domínio do tempo. Este método, viabilizado pelos importantes recursos das técnicas de processamento digital de sinais, foi potencializado pela automatização das medições. Comparado aos procedimentos aplicados a experimentos anteriores na FEIS, cada medição equivale a 2500 medições no sistema antigo, permitindo o levantamento da curva de linearidade de um atuador com uma única medição. Além dessa, o método apresenta outras vantagens: é homódino, opera em malha-aberta, é imune ao desvanecimento do sinal, tem excelente resolução, ampla faixa dinâmica, opera com dispositivos não-lineares, detecta sinais com formas de onda arbitrárias, permite medir magnitude e fase do deslocamento ... Mestre

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Woan, Graham. "Disconnected interferometry at 81.5 MHz." Thesis, University of Cambridge, 1989. https://www.repository.cam.ac.uk/handle/1810/244823.

Testo completo

Abstract (sommario):

Long Baseline Interferometry is a well established technique that enables high angular resolution measurements to be made with a radio interferometer containing independent local oscillators and signal recorders. This Thesis addresses the problems encountered when this technique is applied to low frequency (81.5 MHz) astronomy, and specifically methods of improving its phase stability. The technique is used to reassess existing evidence for the existence of large-scale structure associated with the quasar 3C48, and to give a much better understanding of the structure and behaviour of the supernova remnant Cassiopeia A at low frequencies. Much of the instrumentation used for this work already existed, but in a form unsuitable for measuring phase. The first section of the Thesis shows how these data collection and digital correlator systems could be modified and extended to improve sensitivity and generate true interferometric phase. Two phase calibration schemes are also considered. Firstly, the ‘thin triangle’ method, which uses the closure phase generated by a three-element interferometer to determine the true astronomical phase of a source comprising a single, bright point source and an associated resolvable component. This includes an analysis of how best to determine closure phase when the signal-to-noise ratio on one or more of the baselines is low, and shows techniques based on the ‘triple-product’ method, proposed by Cornwell, to perform best. Secondly, a new method of instrumental stabilisation is introduced and demonstrated, in which the interferometer is calibrated by broadband signals from VHF public broadcast transmitters, which are processed along with the astronomical data. The technique is shown to be capable of removing practically all the instrumental phase drifts usually associated with a long baseline interferometer on baselines up to 100 km. A number of new observations are also presented, mostly made with the stabilised mobile interferometer described above. Firstly of the bright quasar 3C48 to investigate earlier reports of an associated steep-spectrum extended component. These show the importance of considering the effects of confusion in the earlier observations and prompt a critical reassessment of the existing evidence, which is shown to be flawed. Detailed observations of the supernova remnant Cassiopeia A are also presented, with a resolution and sensitivity previously unattained at metre wavelengths. Comparisons with 20 cm VLA data of the same epoch show the remnant to look remarkably similar at the two frequencies, though tentative spectral index measurements indicate that its younger features have slightly steeper spectra than the rest. Furthermore, sensitive observations made on a 128 km baseline show that Cassiopeia A does not contain the steep-spectrum compact component with a flux density of more than 5 Jy reported by many earlier authors. An even deeper search at 408 MHz, this time for pulsed emission from the remnant, puts an upper limit of 80 mJy on the flux density due to any associated pulsar with a period 4 > P > 0.02 sec.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Lay, Oliver Peter. "Astronomical interferometry at submillimetre wavelengths." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/244795.

Testo completo

Abstract (sommario):

This thesis describes my work on the project to connect the James Clerk Maxwell Telescope (JCMT) and the Caltech Submillimeter Observatory (CSO) to form the world's first astronomical interferometer operating at submillimetre wavelengths. Included are my contributions to the technical design and construction of the instrument and to the subsequent debugging and calibration, and my analysis of the data that was obtained from a number of astronomical objects. I was responsible for much of the system that brings the signals from the receivers at each antenna to the digital correlator at the JCMT. A key feature is that the signals are carried extensively in single-mode optical fibre. The design of the delay line system is presented; this helps to equalize the travel times from the source to the correlator by inserting different lengths of optical fibre into the two signal paths. Also described is the use of a microcomputer to control a pair of oscillators, where accurate timing is necessary to ensure that a source is tracked correctly as the Earth rotates. Careful calibration is needed to remove the effects of the instrument from the data. For an interferometer this requires a precise knowledge of many aspects of the system, including, the lengths of the baseline components, thermal drift in the fibre and other components, the deformation of the dishes under gravity, the contribution of the Earth's atmosphere and the complex passband. The techniques used to make these measurements on the JCMT -CSO Interferometer are described. There is also an explanation of how software that I have written processes the raw data from the correlator to give spectra and fluxes. After four rather brief observing sessions, the interferometer is working well and has been used successfully to observe several astronomical sources. Brief descriptions are given of observations and their interpretation for three sources: the recombination-line maser source MWC 349, the black-hole candidate Sagittarius A* at the centre of our galaxy, and the nearby radio-galaxy Centaurus A. This is followed by a more detailed analysis of data for the evolved star VY CMa and observations of discs around young stars. Spectra of the 321 GHz H20 line from VY CMa confirm that maser amplification is responsible for the emission. Continuum emission, spatially offset from the masers, was also detected with the interferometer, as was the CO (3-2) line. These data, particularly the offset continuum, are shown to be incompatible with single-star models for VY CMa. Instead, a binary model is proposed. This also helps to account for many previous observational results. Many protostars are suspected of having accretion discs. The JCMT-CSO Interferometer has resolved the dust continuum emission on scales of < 100 AU for the sources HL Tau and L1551-IRS 5. An analysis of the visibility curves is presented, showing that the emission is extended perpendicular to the outflow direction in each case; radii to half-maximum brightness are determined to be 60 AU and 80 AU respectively. A lower limit to the disc masses of ~0.02 M. is also derived.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Smith, Martin Dignan. "Fibre interferometry for differential measurements." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2913.

Testo completo

Abstract (sommario):

This thesis investigates the use of interferometry as an interrogation technology for the measurement of differential length at two widely separate locations. Differential length measurements are essential and can have many applications in industrial processes, therefore accurate measurements can be a critical. Such differential length measurements can be applied to aspects of differential pressure. Using an all optical fibre approach, the research utilises the effects of light interference for both low coherent and high coherent light sources for the determination of a differential length between individual sensing cavities separated by up to 10’s of meters. The construction of the differential length interrogation system makes use of two Fabry-Perot cavities arranged in a tandem configuration, as a means of determining the differential length between them. Such an arrangement provides a common path through which an optical broadband light source at a central wavelength of 1550 nm can propagate. As a consequence of this configuration, differential lengths are made simply using one single measurement, removing the need to determine each individual length. An additional benefit of this common optical path prevents environmental factors such as temperature and air pressures from affecting the measurement length in question. Using a scanning reference Michelson interferometer to induce an optical path change, low coherence interference effects are present when the optical path length of the differential Fabry-Perot cavities is equal to the optical path length difference in the Michelson interferometer. Using a separate DFB laser light source to illuminate the reference interferometer high coherence interference fringes, present when the optical path length of one interferometer arm is changing due to a piezo fibre stretcher, can be analysed to provide an accurate length determination. Taking into consideration the noise within the system the interrogation technique has a length measurement resolution of 27.43 nm. Demonstrations show that a differential length of 82.539 μm could be measured with an uncertainty of 41.00 nm. Through the characterisation of a deformable silicon diaphragm, it would be possible to construct a sensing system capable of measuring a differential pressure of 1 Pa in 100 kPa. This however would require a 9.13 mm thick diaphragm, with a radius of 0.35 m. Such a diaphragm would be out of the question and so further investigation into reducing the length measurement resolution would need to be carried out.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Noble, Adam. "Sagnac interferometry and fundamental physics." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441781.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Campbell, E. S. "Millimetre and submillimetre bolometric interferometry." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597259.

Testo completo

Abstract (sommario):

I start by presenting simulations of the noise performance of Superconductor-Insulator-Superconductor (SIS) direct detectors, combined with op-amp based readout electronics. This involves the combination of non-linear device modelling, with a detailed noise model of both the SIS junction and the readout-electronics. Using this model, I show that an SIS direct detector can be competitive in terms of noise performance with a transition edge sensor, provided the junction is biased well below the gap, and that the gap is tailored to the observing frequency. I then describe a set of experiments aimed at measuring the noise performance of a tantalum aluminium SIS device combined with op-amp based readout. I compare the results of these experiments with the predictions of my model, and show that they are in excellent agreement. Using the modelling software I have developed, I predict the lowest noise equivalent power achievable with this device as being 1.3 x 10-17W/√Hz, over a video bandwidth of 5 kHz. The expected dynamic range is 91 dB. I also describe the development and testing of the first submillimetre, single-chip, beam combining interferometer. This uses a superconducting chip, on which both the beam combination and detection occur. Two designs of chip were tested, one using a directional coupler for the beam combination, the other using a 90° hybrid. Both designs resulted in the measurement of fringe patterns that agree remarkably well with theory. The final part of this work concerns the development of a new modal theory of interferometry. The aim of this work was to accurately describe the partially coherent behaviour of multi-moded bolometric interferometers. My first attempt uses an approach based on the eigenmodes of the optical system. This was successful, but it became apparent that a more elegant solution existed. This alternative approach introduces the concept of eigenfields. These are the fundamental field distributions associated with an optical system. The can be found using the singular value decomposition, and, as I demonstrate, they allow the accurate simulation of multi-modal bolometric interferometers.

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Clayton, Peter Edward. "Automating the Moire Interferometry technique." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260657.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Spinks, M. J. "Low frequency long baseline interferometry." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372284.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Interferometry"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili