Dissertations / Theses: 'Speckle'

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Andersson, Angelica. "Combined speckle interferometry and speckle correlation for non-destructive testing." Licentiate thesis, Luleå tekniska universitet, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17020.

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When a sample is studied during loading in a tensile test machine, the sample is often exposed to rigid body motions during loading at the same time as it deforms due to tension. Therefore, the small deformation field is hard, or impossible, to measure when it is overlaid by a large motion. The large rigid body motions can be measured with methods like speckle correlation (also called digital speckle photography, DSP), but the results might be of too poor accuracy to resolve the deformation field. Interferometric methods on the other hand might measure the deformation field but the rigid body motion makes the fringes disappear. In this thesis a method is presented that makes it possible to master such measuring situations, by a combination of speckle correlation and speckle interferometry (also called TV holography, ESPI or DSPI). Both theory and experiments are presented. It is shown that speckle correlation can determine the speckle motion in the recording in order to determine the small deformation field in the interferometric algorithm. Speckle correlation can also be used to determine the amount of shear in shearography allowing a quantitative determination of the spatial derivative of the deformation field.
Godkänd; 2000; 20070318 (ysko)

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Grantham, Stephen Gary. "Digital speckle radiography." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619648.

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Alaimo, M. D. "Heterodyne speckle velocimetry." Doctoral thesis, Università degli Studi di Milano, 2007. http://hdl.handle.net/2434/61272.

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

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

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Evanschitzky, Peter. "Simulationsgestützte Oberflächendiagnostik mittels Speckle-Interferometrie." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965479129.

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An, Wei. "Industrial applications of speckle techniques." Doctoral thesis, KTH, Production Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3342.

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Syratt, Richard William. "Angular correlations of speckle patterns." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261820.

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Rodrigues, Silvestre. "Efeito estocastico em Speckle dinamico." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257030.

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Orientadores: Inacia Maria Dal Fabbro, Roberto Alves Braga Junior
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
Made available in DSpace on 2018-08-09T03:56:10Z (GMT). No. of bitstreams: 1 Rodrigues_Silvestre_D.pdf: 5874424 bytes, checksum: f82d98473ad716d4bbdd08a46b90d886 (MD5) Previous issue date: 2007
Resumo: Este trabalho tem por objetivo contribuir para o desenvolvimento de uma metodologia de análise de vitalidade de tecidos vivos, por meio de um modelo estocástico destinado a interpretar e quantificar Padrão associadas ao fenômeno conhecido como biospeckle ou speckle dinâmico, e geradas a partir da interação de luz coerente com materiais biológicos ou com sistemas particulados passíveis de fenômenos dinâmicos, à semelhança do movimento browniano. O biospeckle é formado pela mudança do padrão de interferência quando a luz coerente incide no tecido biológico ou no sistema particulado, gerando Padrão que podem ser observadas e apropriadamente capturadas. O material biológico tanto quanto o sistema particulado exibem transformações superficiais e internas ao longo do tempo, apresentando-se à luz coerente como uma rede de difração dinâmica. Através de tratamento digital das Padrão coletadas para retratação do fenômeno, é possível diferenciar níveis de atividades biológicas nos tecido em estudo. A análise de Padrão associadas ao biospeckle apresenta um comportamento típico estocástico, sugerindo um estudo estatístico probabilístico do comportamento da padrão, seja por movimento browniano, entropia ou outro modelo aplicável a fenômenos aleatórios. Para o estudo desses fenômenos, este trabalho abordou a viabilidade de sementes, senescência de tecidos biológicos, além de uma simulação de movimento browniano com sistemas particulados. Os resultados mostraram que as Padrão geradas pelo método STS (Spatial Temporal Speckle) se comportam de maneira totalmente aleatória, sendo difícil eleger um modelo que possa quantificar essas Padrão. Ao contrário, nas Padrão geradas pelo método MOC (Matriz de Ocorrência), o efeito ¿caos¿ observado nas Padrão anteriores é minimizado, tornando-se então passíveis de serem quantificadas pela entropia, que gerou um padrão semelhante ao apresentado pelo método denominado ¿Momento de Inércia¿. Palavras Chaves: Imagens, sementes, senescência
Abstract: This research work had the objective of contributing to the development of a methodology applicable to biological tissues vitality analysis by means of a stochastic model. The conceived and tested model is able to interpret as well as to quantify the biospeckle images generated on living tissues. The biospeckle or dynamic speckle phenomenon is generated from the interaction of a coherent light with living tissues or with body surface exhibiting certain kinds of activities. In other words, the biospeckle phenomenon is observed when interfering patterns generated by the incidence of coherent light on a surface exhibiting some kind of dynamic or biological activities change at certain rate. Biological tissues, as well as particles in suspension exhibit dynamic activities, similar to brownian motion, acting as a dynamic diffraction grid to the coherent light. By capturing and processing biospeckle images it is possible to differentiate levels of biological or dynamic activities in the body under study. Dynamic speckle image analysis presents a typical stochastic behavior, suggesting a probabilistic statistical study of image behavior, as brownian motion, entropy or other kind of model associated to random phenomenon. Toward that sense, seed viability analysis, vegetative tissue senescence, as well as brownian motion simulation tests had been carried out. Results indicate that STS (Spatial Temporal Speckle) images show random behavior, impeding quantitative analysis. In opposition, MOC (Matrix Occurrence) images or occurrence matrix, where the chaos effect is minimized, are susceptible to quantifying analysis, similarly to the ¿moment of inertia¿ method. Key words: Image, seed, senescence
Doutorado
Maquinas Agricolas
Doutor em Engenharia Agrícola

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Conrad, III Dallis G. "Speckle Statistics of Articulating Objects." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1320673424.

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Gebhardt, Mark William Dewdney. "Speckle reduction in SAR imagery." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/18786.

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Synthetic Aperture Radar (SAR) is a popular tool for airborne and space-borne remote sensing. Inherent to SAR imagery is a type of multiplicative noise known as speckle. There are a number of different approaches which may be taken in order to reduce the amount of speckle noise in SAR imagery. One of the approaches is termed post image formation processing and this is the main concern of this thesis. Background theory relevant to the speckle reduction problem is presented. The physical processes which lead to the formation of speckle are investigated in order to understand the nature of speckle noise. Various statistical properties of speckle noise in different types of SAR images are presented. These include Probability Distribution Functions as well as means and standard deviations. Speckle is considered as a multiplicative noise and a general model is discussed. The last section of this chapter deals with the various approaches to speckle reduction. Chapter three contains a review of the literature pertaining to speckle reduction. Multiple look methods are covered briefly and then the various classes of post image formation processing are reviewed. A number of non-adaptive, adaptive and segmentation-based techniques are reviewed. Other classes of technique which are reviewed include Morphological filtering, Homomorphic processing and Transform domain methods. From this review, insights can be gained as to the advantages and disadvantages of various methods. A number of filtering algorithms which are either promising, or are representative of a class of techniques, are chosen for implementation and analysis.

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Riechert, Falko. "Speckle reduction in projection systems." Karlsruhe Univ.-Verl. Karlsruhe, 2009. http://d-nb.info/997279346/04.

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Mosayebi, Mahshad. "Digital Laser Speckle Image Correlation." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2131.

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This thesis examines the feasibility of combining Digital Image Correlation (DIC) with laser speckle based methods to form a new hybrid deformation measurement method called Digital Laser Speckle Image Correlation (DilSIC). Consequently, this method does not require any sample preparation and allows for the measurement of displacement of micro structures in addition to large displacements. In this technique, a coherent 30mW-632nm laser beam is expanded with 40X lens and then illuminated on the target surface to produce a fine, homogenous laser speckle pattern. Images were captured before and after deformation due to external load and the whole field displacement and strain were determined by the DIC method. This technique could measure displacement less than 30-μm with high accuracy when a 120mm × 80mm area of the surface was inspected. Up to 10% strain was measured by this technique with high accuracy during the whole range. Eventually the sub-surface crack was located successfully, which is a revolutionary achievement in NDT optical methods. This method was tested in different material, with different roughness. Aluminum sheet and rubber material were used mostly. This method could broaden the capability of displacement measurement and subsurface crack detection in wide range of materials.

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Purde, Andreas. "Speckle-Interferometrie zur Formvermessung unstetiger Oberflächen." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980540798.

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Riemenschneider, Markus. "Echtzeitvermessung dreidimensionaler Objekte mittels Speckle-Interferometrie." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973065346.

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Cristea, Anca. "Ultrasound tissue characterization using speckle statistics." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10329.

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L'objectif de la caractérisation des tissus par ultrasons ou ‘Quantitative Ultrasound (QUS)’ est de différencier les tissus pathologiques en associant les paramètres d’un modèle aux caractéristiques physiques du tissu. L'usage exclusif des ultrasons pour obtenir un diagnostic peut garantir que le patient ne subira pas une procédure invasive (e.g. une biopsie), utilisant des rayonnements ionisants (e.g. la tomographie) ou même inconfortable et coûteuse (e.g. IRM). Les méthodes de QUS extraient des informations sur la microstructure du tissu à partir du contenu spectral ou temporel des signaux ultrasonores. Le signal temporel radiofréquence (RF) et son enveloppe sont d'intérêt à cause du speckle crée par l’interférence des ondes, qui peut être modélisé par des distributions statistiques. Ce travail propose d'explorer la possibilité d'obtenir des estimations QUS fiables en utilisant des distributions statistiques comme modèles pour le speckle ultrasonore. Les estimations sont constituées des paramètres des distributions respectives et dépendent de la densité de diffuseurs dans le milieu. L’évaluation s’effectue sur des images simulées, des fantômes de particules et des biofantômes. Dans la première partie, la distribution Gaussienne Généralisée est utilisée pour modéliser le signal RF, et la distribution de Nakagami est utilisée pour modéliser son enveloppe. Les deux distributions sont limitées à discriminer les milieux avec une faible densité de diffuseurs, parce que les valeurs de leurs paramètres de forme saturent pour un speckle pleinement développé. Par conséquent, puisque la formation du speckle pleinement développé dépend de la résolution du système d'imagerie, la caractérisation peut se faire seulement à de très hautes résolutions, correspondant à des hautes fréquences qui ne sont pas communes en échographie clinique. Une application du modèle de Nakagami sur l’image crée par la seconde harmonique montre le potentiel du paramètre de forme de Nakagami en tant que mesure de la nonlinéarité du milieu. Dans la deuxième partie, l'enveloppe a été modélisée en utilisant la distribution K-Homodyne. Le paramètre de regroupement des diffuseurs α permet de discriminer entre les milieux denses jusqu’à une limite supérieure à celle du paramètre de Nakagami. Pourtant, cette limite est difficile à estimer avec précision, parce que les valeurs caractéristiques pour le speckle pleinement développé sont affectées par un biais et une variance élevés. Le biais et la variance peuvent être améliorés en augmentant la quantité de données utilisée pour l’estimation. Dans la dernière partie, une technique de déconvolution spécialement conçue pour la caractérisation des tissus a été évaluée. Des essais exhaustifs ont montré qu’elle n’est pas suffisamment robuste pour une application clinique, puisque les images déconvoluées ne sont pas fidèles à la réflectivité originale du milieu
The purpose of ultrasound tissue characterization or Quantitative Ultrasound (QUS) is to differentiate between tissue pathologies by associating model parameters to physical tissue features. The exclusive use of ultrasound for diagnosis would guarantee that the patient does not undergo a procedure that is invasive (e.g. a biopsy), using ionizing radiation (e.g. tomography) or simply uncomfortable and expensive (e.g. MRI). QUS methods extract information on the tissue microstructure from the temporal or spectral content of the acquired ultrasound signals. The temporal radiofrequency (RF) signal and its envelope are of interest because of the speckle patterns created by wave interference, which can be modeled by statistical distributions. The present work proposes to explore the possibility of obtaining reliable QUS estimates by using statistical distributions as models for ultrasound speckle. The estimates consist in the parameters of the respective distributions and are indicators of the scatterer density in the medium. The evaluation is conducted on simulated images, particle phantoms and biophantoms. In the first part, the Generalized Gaussian distribution is used to model the RF signal, and the Nakagami distribution is used to model its envelope. The two distributions show limitations in discriminating media with high scatterer densities, as the values of their shape parameters saturate in the fully developed speckle regime. Therefore, since the formation of fully developed speckle depends on the resolution of the imaging system, characterization can be done only at very high resolutions, corresponding to high frequencies that are not common in clinical ultrasound. An application of the Nakagami model on the second harmonic image shows the potential of the Nakagami shape parameter as a measure of the nonlinearity of the medium. In the second part, the echo envelope was modeled using the Homodyned-K distribution. The scatterer clustering parameter α allows the discrimination of dense media up to a concentration that is higher than the one that limits the Nakagami distribution. However, this limit is difficult to estimate precisely, because the values of α that are characteristic for fully developed speckle suffer from large estimation bias and variance. The bias and the variance can be improved by performing the estimation on a very large amount of data. In the final part, a deconvolution technique designed specifically for ultrasound tissue characterization has been analyzed. Extensive testing has shown it to not be sufficiently robust for clinical applications, since the deconvolved images are not reliable in terms of fidelity to the original reflectivity of the medium

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Li, Yikang. "Comparative study of speckle reduction approaches." Thesis, The George Washington University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1537954.

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The speckle reduction is an important problem in coherent imaging, such as synthetic aperture radar or ultrasound imagery. There are several well-known speckle filters for reducing speckle in coherent images. However, different speckle filters will have their own advantages and disadvantages. The performance of speckle filter depends strongly on the speckle and scene models that are used as the basis for filter development. In this thesis, we will compare four different approaches, Lee filter, Kuan filter, Frost filter and Improved Sigma filter for speckle reduction. This thesis will further describe the Improved Sigma filter since it is a new type of speckle filter for coherent images. We will apply these four speckle filters to our synthesized one-look amplitude synthetic aperture radar (SAR) image to reduce speckle noise. In order to compare these different speckle filters, the simulated SAR image data are used quantitatively to analyze these speckle filters. In addition, we will show their advantages and disadvantages in reducing speckle noise. Unlike the original Sigma filter, which has deficiencies in causing biased estimation and in depressing strong reflected targets, the Improved Sigma filter is more efficient when applied on simulated SAR image data.

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Balboa, I. "Low coherence fibre optic speckle interferometry." Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341038.

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Ugarte, La Torre Diego Renato. "Implementation of a speckle-based spectrometer." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/7088.

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Existen diversos métodos para medir la longitud de onda de la luz. Uno de estos métodos está basado en la relación que existe entre la longitud de onda y los patrones de moteado. La implementación de este método consiste en hacer ingresar luz con un ancho espectral peque˜no sobre un extremo de una fibra óptica multimodal, para generar patrones de moteado a la salida de la fibra óptica. Estos patrones de moteado se relacionan con las longitudes de onda que contiene la luz que ingresa a la fibra óptica. En el presente trabajo se propone una nueva implementación que consiste en usar una pantalla de cristal líquido (LCD) en vez de una fibra óptica, para obtener patrones de moteados m´as estables frente a las vibraciones mecánicas a las que está expuesto el arreglo experimental. Los resultados indicaron que es posible implementar el método usando LCDs. Estos dispositivos ofrecen una mayor resistencia al ruido mecánico y mejoran la reproducibilidad de los patrones de moteado generados.
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Khodadad, Davood. "Multiplexed Digital Holography incorporating Speckle Correlation." Doctoral thesis, Luleå University of Technology, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-55810.

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In manufacturing industry there is a high demand for on line quality control to minimize therisk of incorrectly produced objects. Conventional contact measurement methods are usuallyslow and invasive, meaning that they cannot be used for soft materials and for complexshapes without influencing the controlled parts. In contrast, interferometry and digitalholography in combination with computers become faster, more reliable and highly accurateas an alternative non-contact technique for industrial shape evaluation. For example in digitalholography, access to the complex wave field and the possibility to numerically reconstructholograms in different planes introduce a new degree of flexibility to optical metrology. Withdigital holography high resolution and precise three dimensional (3D) images of themanufactured parts can be generated. This technique can also be used to capture data in asingle exposure, which is important when doing measurements in a disturbed environment. The aim of this thesis is devoted to the theoretical and experimental development of shapeand deformation measurements. To perform online process control of free-formmanufactured objects, the measured shape is compared with the CAD-model to obtaindeviations. To do this, a new technique to measure surface gradients and shape based onsingle-shot multiplexed dual-wavelength digital holography and image correlation of speckledisplacements is demonstrated. Based on an analytical relation between phase gradients andspeckle displacements it is shown that an object is retrieved uniquely to shape, position anddeformation without the unwrapping problems that usually appear in dual-wavelengthholography. The method is first demonstrated using continues-wave laser light from twotemperature controlled laser diodes operating at 640 nm. Then a specially designed dual corediode pumped fiber laser that produces pulsed light with wavelengths close to 1030 nm isused. In addition, a Nd:YAG laser with the wavelength of 532 nm is used for 3D deformationmeasurements. One significant problem when using the dual-wavelength single-shot approach is that phaseambiguities are built in to the system that needs to be corrected. An automatic calibrationscheme is therefore required. The intrinsic flexibility of digital holography gives a possibilityto compensate these aberrations and to remove errors, fully numerically without mechanicalmovements. In this thesis I present a calibration method which allows multiplexed singleshotonline shape evaluation in a disturbed environment. It is shown that phase maps andspeckle displacements can be recovered free of chromatic aberrations. This is the first time that a multiplexed single-shot dual-wavelength calibration is reported by defining a criteria tomake an automatic procedure. Further, Digital Speckle Photography (DSP) is used for the full field measurement of 3Ddeformations. In order to do 3D deformation measurement, usually multi-cameras andintricate set-up are required. In this thesis I demonstrate the use of only one single camera torecord four sets of speckle patterns recorded by illuminating the object from four differentdirections. In this manner, meanwhile 3D speckle displacement is calculated and used for themeasurement of the 3D deformations, wrapping problems are also avoided. Further, the samescale of speckle images of the surface for all four images is guaranteed. Furthermore, a needfor calibration of the 3D deformation measurement that occurs in the multi-camera methods,is removed. By the results of the presented work, it is experimentally verified that the multiplexed singleshotdual wavelength digital holography and numerically generated speckle images can beused together with digital speckle correlation to retrieve and evaluate the object shape. Usingmultidirectional illumination, the 3D deformation measurements can also be obtained. Theproposed method is robust to large phase gradients and large movements within the intensitypatterns. The advantage of the approach is that, using speckle displacements, shape anddeformation measurements can be performed even though the synthetic wavelength is out ofthe dynamic range of the object deformation and/or height variation.

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Jin, Song. "Bispectral reconstruction of speckle-degraded images /." Online version of thesis, 1992. http://hdl.handle.net/1850/11230.

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CREATH, KATHERINE. "DIGITAL SPECKLE-PATTERN INTERFEROMETRY (OPTICAL TESTING)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188115.

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A digital speckle-pattern interferometer was built utilizing a 100 x 100 element Reticon diode array interfaced to an HP-9836C desk-top computer. A single-mode optical fiber mounted in the center of the system's aperture stop creates a spherical-wave reference beam. Secondary interference fringes are calculated inside the computer by subtracting speckle patterns before and after a deformation, and squaring this difference. This technique has been shown superior to that of taking the absolute value of the difference. The traditional vibrational observation technique of low-pass filtering a single speckle pattern and squaring the result is emulated in software. It is compared to four other vibration observation techniques. A new technique records the self-interference terms in a reference frame, and subtracts these from the time-averaged vibration data. It provides very good fringe contrast for moderately unstable objects, as well as interferometers which have not been optimized to minimize self-interference terms. The best vibration fringe contrast is obtained by subtracting two time-averaged speckle patterns of a single object resonance. One exposure has a relative π phase-shift between object and reference beams to cancel self-interference terms. This last technique is not real-time; whereas, the new technique is. Double-exposure speckle interferograms are averaged using a technique which utilizes a stepping motor to change the object illumination angle. Results of averaging deformation measurements and double-exposure vibration techniques show a large increase in fringe contrast with an accompanying reduction in speckle noise. Quantitative measurements of object deformations is demonstrated by applying phase-shifting interferometry techniques. A deformation's phase is found by subtracting modulo 2π phases measured for each object state. Phase discontinuities are removed with the aid of noise reduction algorithms. Limitations are low intensity modulation as the phase is shifted, and speckle decorrelation during object deformation. It is shown that 10 waves of object deformation are measurable to λ/10 across the detector array. The double-exposure phase-measurement technique works well and is applicable to many different metrological measurements. To show the versatility of this technique, an optically smooth surface is contoured using two illumination wavelengths.

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Newberry, Shawn. "Laser Speckle Patterns with Digital Image Correlation." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2885.

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Digital Laser Speckle Image Correlation (DiLSIC) is a technique that utilizes a laser generated speckle pattern with Digital Image Correlation (DIC). This technology eliminates the need to apply an artifact speckle pattern to the surface of the material of interest, and produces a finer speckle pattern resulting in a more sensitive analysis. This investigation explores the parameters effecting laser speckle patterns for DIC and studies DiLSIC as a tool to measure surface strain and detect subsurface defects on pressure vessels. In this study a 632.8 nm 30 mW neon-helium laser generated the speckle pattern by passing through the objective end of an objective lens. All experiments took place in a lab setting on a high performance laminar flow stabilizer optical table.This investigation began with a deeper look at the camera settings that effect the effectiveness of using laser speckles with DIC. The first studies were concentrated on the aperture size (f-stop), shutter speed, and gain (ISO) of the camera. Through a series of zero-correlation studies, translation tests, and settings studies, it was discovered that, much like white light DIC, an increased gain allowed for more noise and less reliable measurements when using DiLSIC. It was shown that the aperture size and shutter speed will largely depend on the surface composition of the material, and that these factors should be investigated with each new sample of different surface finish.To determine the feasibility of using DiLSIC on pressure vessels two samples were acquired. The first was a standard ASTM filament wound composite pressure vessel (CPV) which had an upper load limit of 40 psi. The second was a plastic vessel that had internal subsurface defects added with the use of an air pencil grinder. Both vessels were put under a pressure load with the use of a modified air compressor that allowed for multiple loading cycles through the use of a pressure relief valve. The CPV was mapped out in 10-degree increments between the 90° and 180° markings that were on the pressure vessel, occurring in three areas, each one inch apart. The CPV had a pressure load applied to at 10, 20, 30,and 40 psi. DiLSIC was able to measure increasing displacement with increased loading on the surface of the CPV, however with a load limit of 40 psi no strains were detected. The plastic vessel had known subsurface defects, and these areas were the focus of the investigation. The plastic vessel was loaded with a pressure load at 5, 10, 12, 15, 17, and 20 psi. The 5 psi loaded image was used as a reference image for the correlation and decorrelation consistently occurred at 20 psi. This investigation proved that DiLSIC can detect and locate subsurface defects through strain measurement. The results were verified with traditional white light DIC, which also showed that the subsurface defects on pressure vessels were detectable. The DIC and DiLSIC results did not agree on maximum strain measurement, with the DiLSIC prediciting much larger strains than traditional DIC. This is due to the larger effect out-of-plane displacement has on DiLSIC. DiLSIC was able to detect subsurface defects on a pressure vessel. The median measured hoop strain was in agreement for DiLSIC, DIC and the predicted hoop strain for a wall thickness of 0.1 inches. However, DiLSIC also produced unreliable maximum strain measurements. This technique shows potential for future applications, but more investigations will be needed to implement it for industrial use. A full investigation into the parameters surrounding this technique, and the factors that contribute the most to added noise and unreliability should be conducted. This technology is being developed by multiple entities and shows promising results, and once further advanced could be a useful tool for rapid surface strain measurement and subsurface defect detection in nondestructive evaluation applications. Therefore, it is recommended to continue further investigations into this technology and its applications.

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Welde, Kristine. "Investigation of methods for speckle contrast reduction." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10045.

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Speckle arises when coherent light is reflected from a rough screen and observed by an intensity detector with a finite aperture. Because speckle causes serious image degradation when lasers are used as light sources in e.g. projectors, methods for reducing the speckle contrast need to be developed. Different speckle contrast reduction methods are investigated in this thesis, such as a rotating diffuser and a sinusoidal rotating grating. In addition, speckle simulations with the optical system design software ZEMAX has been explored. A setup consisting of a 4-f imaging system with a rotating diffuser in the Fourier plane was developed in order to decide whether or not it is advantageous to perform speckle reduction in the Fourier plane. Hence, measurement series were performed with the rotating diffuser placed at different positions in the 4-f imaging system for comparison. Measurement series were executed both with an empty object plane and with a lens in it to spread the light in the Fourier plane. Placing a rotating diffuser in the Fourier plane does not appear to be effective for speckle contrast reduction. The last setup investigated was a transmissive spatial light modulator (SLM) placed in the beam path. Sinusoidal rotating gratings created by means of gray levels, to simulate a potential modulator based on a deformable polymer layer, were implemented on the SLM. The gratings were rotated around their centers, and in a spiral in order to reduce the speckle contrast. For the first method the modulator speckle contrast was 34% for N = 18 averaged images, and for the second method it was 31% for N = 36 averaged images, both with a grating period of 4 pixels. Due to the drawbacks of the SLM optimal results were not achieved, but the SLM is useful for a proof-of-concept. Further measurements should be performed for this promising, novel method based on a true sinusoidal grating.

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Narges, Afsham. "Speckle tracking for 3D freehand ultrasound reconstruction." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50851.

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The idea of full six degree-of-freedom tracking of ultrasound images solely based on speckle information has been a long term research goal. It would eliminate the need for any additional tracking hardware and reduces cost and complexity of ultrasound imaging system, while providing the benefits of three-dimensional imaging. Despite its significant promise, speckle tracking has proven challenging due to several reasons including the dependency on a rare kind of speckle pattern in real tissue, underestimation in the presence of coherency or specular reflection, ultrasound beam profile spatial variations, need for RF (Radio Frequency) data, and artifacts produced by out-of-plane rotation. So, there is a need to improve the utility of freehand ultrasound in clinics by developing techniques to tackle these challenges and evaluate the applicability of the proposed methods for clinical use. We introduce a model-fitting method of speckle tracking based on the Rician Inverse Gaussian (RiIG) distribution. We derive a closed-form solution of the correlation coefficient of such a model, necessary for speckle tracking. In this manner, it is possible to separate the effect of the coherent and the non-coherent part of each patch. We show that this will increase the accuracy of the out-of-plane motion estimation. We also propose a regression-based model to compensate for the spatial changes of the beam profile. Although RiIG model fitting increases the accuracy, it is only applicable on ultrasound sampled RF data and computationally expensive. We propose a new framework to extract speckle/noise directly from B-mode images and perform speckle tracking on the extracted noise. To this end, we investigate and develop Non-Local Means (NLM) denoising algorithm based on a prior noise formation model. Finally, in order to increase the accuracy of the 6-DoF transform estimation, we propose a new iterative NLM denoising filter for the previously introduced RiIG model based on a new NLM similarity measure definition. The local estimation of the displacements are aggregated using Stein’s Unbiased Risk Estimate (SURE) over the entire image. The proposed filter-based speckle tracking algorithm has been evaluated in a set of ex vivo and in vivo experiments.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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26

Shih, YiChang. "Laser speckle photography for surface tampering detection." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75686.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-61).
It is often desirable to detect whether a surface has been touched, even when the changes made to that surface are too subtle to see in a pair of before and after images. To address this challenge, we introduce a new imaging technique that combines computational photography and laser speckle imaging. Without requiring controlled laboratory conditions, our method is able to detect surface changes that would be indistinguishable in regular photographs. It is also mobile and does not need to be present at the time of contact with the surface, making it well suited for applications where the surface of interest cannot be constantly monitored. Our approach takes advantage of the fact that tiny surface deformations cause phase changes in reflected coherent light which alter the speckle pattern visible under laser illumination. We take before and after images of the surface under laser light and can detect subtle contact by correlating the speckle patterns in these images. A key challenge we address is that speckle imaging is very sensitive to the location of the camera, so removing and reintroducing the camera requires high-accuracy viewpoint alignment. To this end, we use a combination of computational rephotography and correlation analysis of the speckle pattern as a function of camera translation. Our technique provides a reliable way of detecting subtle surface contact at a level that was previously only possible under laboratory conditions. With our system, the detection of these subtle surface changes can now be brought into the wild.
by YiChang Shih.
S.M.

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27

Binder, Bradley Thomas 1960. "Laser radar tomography--the effects of speckle." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/34312.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.
Vita.
Includes bibliographical references (leaves 165-169).
by Bradley Thomas Binder.
Ph.D.

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28

Shilpiekandula, Vijay 1979. "A laser speckle based position sensing technique." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27131.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 129-131).
This thesis presents the design and development of a novel laser-speckle-based position sensing technique. In our prototype implementation, a He-Ne laser beam is directed at the surface of an air-bearing spindle. An imaging system is set up to capture speckle patterns scattered from the spindle surface. These patterns are highly correlated over small angular displacements of the spindle. We use correlation-based image-processing algorithms to measure offsets between the speckle patterns. These offsets are calibrated against the counts of a commercial incremental optical encoder. A custom-built bicell photointerrupter unit is used as a reference sensor for the incremental optical encoder. To test for the control performance of this speckle-based sensor, we have constructed a transmission drive to run the air-bearing spindle. Our speckle-based metrology system is able to run at update rates of 10 Hz with a measured closed loop -3 dB bandwidth of about 2 Hz. Using a real-time processor interfaced with a desktop PC, we have implemented a novel algorithm that interpolates position estimates with respect to two pre-stored global images. We predict that this technique can potentially achieve resolutions of 0.1 [mu]m for translational and 5 [mu]rad for rotational motion. The limitation of our current implementation is the low update rates resulting from the time-intensive nature of correlation-based methods. Possible methods to overcome this limitation are addressed and ideas for follow-on work are presented.
by Vijay Shilpiekandula.
S.M.

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29

Torres-Munoz, Keshia Nicole. "Regulation of Mitosis by Nuclear Speckle Proteins." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341028309.

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Scheffold, Frank. "Speckle-Korrelationen und universelle Leitwertfluktuationen von Licht /." Konstanz : Hartung-Gorre, 1998. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB7215611.

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31

Porter, Matthew Stanton. "Soft x-ray speckle from rough surfaces /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9957568.

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Thesis (Ph. D.)--University of Oregon, 2000.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 100-104). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9957568.

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32

Lin, Haibo Yu Ping. "Speckle mechanism in holographic optical coherence imaging." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6184.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Ping Yu. Vita. Includes bibliographical references.

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33

Mesquita, da Costa Kassiana. "Filtragem interagente de imagens com ruído speckle." Universidade Federal de Pernambuco, 2004. https://repositorio.ufpe.br/handle/123456789/2593.

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Made available in DSpace on 2014-06-12T15:59:32Z (GMT). No. of bitstreams: 2 arquivo5160_1.pdf: 4852221 bytes, checksum: 00af0b636289f3973abc1f5ce9bce923 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004
O ru´ıdo speckle aparece em imagens com iluminac¸ ao coerente, tais como, sonar, laser, ultra-sonografia e radar de abertura sint´etica (Synthentic Aperture Radar SAR). Existem diversas t´ecnicas para reduc¸ ao de ru´ıdo speckle. Este trabalho propoem uma metodologia que permite a utilizac¸ ao destas t´ecnicas a fim de produzir uma imagem filtrada. Esta imagem filtrada ´e obtida combinando pontualmente de forma linear as t´ecnicas j ´a dispon´ıveis. Os coeficientes da combinac¸ ao linear s ao encontrados tal que satisfac¸am aproximadamente as expectativas do usu´ario. A t´ecnica ´e denominada Filtragem Interagente, desde que as expectativas do usu´ario s ao expressas atrav´es das especificac¸ oes das regi oes de interesse e dos valores desejados associados a cada regi ao de interesse. A t´ecnica ´e implementada na linguagem IDL e integrada ao ENVI, uma plataforma de processamento de imagens. A proposta ´e avaliada em imagens sint´etica e real SAR utilizando duas medidas de qualidade, o erro m´edio quadr ´atico normalizado (NMSE - Normalized Mean Square Error) e o n ´umero equivalente de visadas (ENL - Equivalent Number of Looks), sob o crit´erio da relac¸ ao sinal-ru´ıdo (SNR Signal-to-Noise Ratio). Os resultados quantitativos e qualitativos obtidos s ao superiores aos obtidos com filtros cl ´assicos redutores de ru´ıdo speckle e as imagens obtidas satisfazem as expectativas do usu´ario.

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34

Saif, Babak Nasser. "Simultaneous phase shifted digital speckle pattern interferometry." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280499.

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The James Webb Space Telescope (JWST) is an anastigmatic, segmented cryogenic telescope. The stability of the primary mirror back-plane is a major concern in co-phasing the telescope and in the longer term stability of its image quality. The back-plane is a 6.6 meter structure constructed of carbon fiber, and is therefore a "diffuse" object, an object with surface roughness larger than the wavelength of the light. For this reason classical interferometeric measurements will not work. The objective is to design and characterize a Simultaneous phase shifted Digital Speckle Pattern Interferometer (SDSPI) that has the most potential to measure the JWST back plane structure within the required accuracy (15 nm RMS out-of-plane motion). SDSPI interferometry is a method of measuring the back-plane deformations that has the potential of reaching the required accuracy in the presence of vibrations within cryogenic chambers. 4D Technology Corporation, in Tucson, Arizona has an instantaneous phase shifted interferometer (PhaseCam) that is modified to a SDSPI interferometer. Repeatability, dynamic range, and accuracy of the SDSPI is characterized by measuring a 5cm x 5cm back-plane structure made of carbon fiber.

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35

Pascucci, Marco. "Super-resolution microscopy by saturated speckle illumination." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB100.

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36

LIETZAU, KAI-HENNING. "Electronic speckle pattern interferometry for cancer research." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2015. http://hdl.handle.net/2108/202465.

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The determination of mechanical properties is a topic of on-going research and has over the years provided new insights regarding complex biochemical processes such as the cell cycle, the progression of diseases and even influenced new forms of therapeutically treatment. However, this field of biomechanical research strongly depends on the analysis of biological samples and their mechanical behavior under stress. In order to achieve reliable results, a high resolution measurement technology and a gentle stimulation method are needed to examine the samples as close as possible to their original condition. Therefore, the content of this work discusses the concept of a new potential technical approach, which introduces the electronic speckle pattern interferometry (ESPI) to this field of application. The ESPI is an optical laser based technique which is capable to determine deformations with a very high axial resolution. However, since this technique is commonly applied for the analyzation of macroscopic sample, additional modifications are required. Therefore, a first concept of such an adapted ESPI system is presented within this work as well as a modified experimental setup. This setup has been furthermore used to analyze the mechanical response of biological specimen in terms of a first proof of concept. As biological specimen adhesive HeLa cells have been cultured on silicon substrates and incubated with magnetic nanoparticles. These so called magnetites have been furthermore prepared with two different coatings in order to improve the uptake. After this preparation, the nanoparticles have been externally stimulated by applying an electromagnetic field, which in consequence caused a displacement of the cellular body. A variety of experiments have been carried out in order to validate the experimental setup as well as the applied method of excitation. Each experiment has been designed to focus on one specific process or preparation parameter such as the incubation time, the applied concentration of nanoparticles, the different coatings as well as the relative positioning of cell and electromagnet. Additionally the cellular behavior has been also analyzed regarding a prolonged excitation time as well as the repositioning of the cellular body during the relaxation. Based on the obtained results, this work also discusses possible modifications, which would improve the applied system. In conclusion, it has been possible to induce a displacement with the developed excitation technique as well as to determine this deformation with the presented ESPI setup. Accordingly, the proof of concept can be regarded as successful and therefore introduces the ESPI to the field of biomechanical research.

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37

Johansson, Louise. "Analysis of cartilage surfaces using laser speckle imaging." Thesis, Linköping University, Department of Biomedical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5830.

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An arthroscope is a diagnostic instrument for visualisation of the interior of a joint. By adding a laser to an arthroscope and feeding the images to a computer, one gets an method to measure the structure of the cartilage covering the joint. This gives an added diagnostic value. The laser will create laser speckles and this report covers the basic theories behind this. The anatomy of the joints, the properties of cartilage and the background on the disease arthritis are also covered, as well as the field of surface topography and image processing.

Experiments were performed on three different materials - metals of different definite surface roughness, polymerised collagen and bovine articular cartilage.

The conclusion is that the technique would work, providing that some obstacles could be overcome. The technique itself is very precise and detects nanometric differences in the surface structure, making it extremely interesting for research purposes, such as follow-ups on treatments and studies of arthritis and cartilage repair.

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38

Catheline, Stefan. "INTERFEROMETRIE-SPECKLE ULTRASONORE : APPLICATION A LA MESURE D'ELASTICITE." Phd thesis, Université Paris-Diderot - Paris VII, 1998. http://tel.archives-ouvertes.fr/tel-00378129.

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L'objectif de ce travail est de réaliser un outil de mesure de l'élasticité des milieux biologiques. L'idée est d'employer les ultrasons pour détecter des ondes de cisaillement générées par un « coup » acoustique de basse fréquence (10-500 Hz) au moyen d'un piston. Cette onde contient des informations sur la nature viscoélastique du solide dans lequel elle se propage. Si les ultrasons dans les milieux biologiques sont bien maîtrisés, ce n'est pas le cas des ondes de cisaillements. Par conséquent la réalisation de cet outil nécessite une meilleure compréhension des ondes de basse fréquence. Dans ce manuscrit, nous montrons que les mesures effectuées par les méthodes ultrasonores actuelles fondées sur le même principe (sonoélasticité), subissent des effets de réflexions d'ondes aux frontières, de diffraction et d'interférence avec une onde longitudinale de basse fréquence. Afin de nous affranchir de ces phénomènes, nous avons élaboré une méthode appelée « élastographie impulsionnelle ». Appliquée à un fantôme d'agar-gélatine, à un muscle et à un produit laitier, elle permet de détecter des ondes de cisaillement se propageant aux vitesses respectives de 2.7, 5.3 et 0.5 m.s-1. L'élasticité de cisaillement et la viscosité de cisaillement sont déduites des mesures de vitesse et d'atténuation de l'onde. Nous montrons enfin que les ondes de basse fréquence sont détectées en champ proche ou en champ intermédiaire. Les diagrammes de directivité de Miller et Pursey en champ lointain sont moins aptes à rendre compte du champ de déplacement que les fonctions de Green dans les solides. L'ensemble des résultats contenus dans ce mémoire autorise à penser que l'élastographie impulsionnelle puissent devenir un outil utile en rhéologie et en médecine.

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39

Cheng, Yan Don. "Underwater acoustic imaging image reconstruction using speckle interferometry." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1176841747.

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40

Mo, Ning. "Mechanical characterisation of bone with laser speckle photography." Thesis, Queen Mary, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339170.

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41

Martin, Peter. "Uncertainty due to speckle noise in laser vibrometry." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7139.

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This thesis presents fundamental research in the field of laser vibrometry for the application to vibration measurements. A key concern for laser vibrometry is the effect of laser speckle which appears when a coherent laser beam scatters from an optically rough surface. The laser vibrometer is sensitive to changes in laser speckle which result from surface motions not in the direction of the incident beam. This adds speckle noise to the vibrometer output which can be indistinguishable from the genuine surface vibrations. This has been termed ‘pseudo-vibration' and requires careful data interpretation by the vibration engineer. This research has discovered that measurements from smooth surfaces, even when no identifiable speckle pattern is generated, can produce noise and therefore reference to speckle noise, in such circumstances, is inappropriate. This thesis has, therefore, adopted the more general term of pseudo-vibration to include noise generated from any surface roughness or treatment, i.e. including but not limited to speckle noise. This thesis develops and implements novel experimental methods to quantify pseudovibration sensitivities (transverse, tilt and rotation sensitivity) with attention focussed on commercially available laser vibrometers and consideration is given to a range of surface roughnesses and treatments. It investigates, experimentally, the fundamental behaviour of speckles and attempts to formulate, for the first time, a relationship between changes in intensity to pseudo-vibration sensitivity levels. The thesis also develops and implements models for computational simulation of pseudo-vibrations using the fundamental behaviour of speckles. The combination of experimentation and simulation improves current understanding of the pseudo-vibration mechanisms and provides the vibration engineer with a valuable resource to improve data interpretation. Two experimental methods of quantifying pseudo-vibration sensitivity are developed and successfully applied in the evaluation of transverse, tilt and rotation sensitivity for two models of commercial laser vibrometer. These evaluations cover both single beam (translational vibration measurement) and parallel beam (for angular vibration measurement) modes. The first method presented requires correction of the vibrometer measurement with an independent measurement of genuine velocity to produce an iii apparent velocity dominated by the required noise components. The second method requires a differential measurement using two vibrometers to cancel common components such as genuine velocity, leaving only uncorrelated noise from each measurement in the resulting apparent velocity. In each case, a third measurement is required of the surface motion component causing pseudo-vibration and this is used to normalise the apparent velocity. Pseudo-vibration sensitivity is then presented as a map showing the spectral shape of the noise, as a mean and standard deviation of harmonic peaks in the map and as a total rms level across a defined bandwidth. The simulations employ a novel and effective approach to modelling speckle evolution. Transverse and tilt sensitivity are predicted for the first time and are verified by the experimental study. They provide the vibration engineer with the potential to estimate pseudo-vibrations using a simple piece of software. The laser beam spot diameter has a large influence on the pseudo-vibration sensitivity. Transverse sensitivity has been quantified as around 0.03% and 0.01% (per order) of the transverse velocity of the surface for beam spot diameters of 100 μm and 600 μm respectively. Larger beam spots have been shown to significantly reduce transverse sensitivity and measurements from smoother surfaces have also shown a reduced level of transverse sensitivity. Tilt sensitivity has been quantified at about 0.1 μms-1/degs-1 and 0.3 μms-1/degs-1 (per order) of angular velocity of the surface for beam spot diameters of 100 μm and 600 μm respectively. Smaller beam spot diameters significantly reduce tilt sensitivity. The surface roughness or treatment has been shown to have little effect on the level of tilt sensitivity. Rotation sensitivity has been quantified at approximately 0.6 μms- 1/rads-1 and 1.9μms-1/rads-1 (per order) of rotation velocity of the rotor for 90 μm and 520 μm. Smaller beam spot diameters have shown a significant reduction in rotation sensitivity and measurements on smoother surfaces have shown a reduced rotation sensitivity. Focussing the laser beam approximately on the rotation axis has also shown a significant reduction in rotation sensitivity. Parallel beam rotation sensitivity has been quantified at 0.016 degs-1/rads-1 and it is demonstrated that this can adequately be estimated using the single beam rotation sensitivity.

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Riemenschneider, Markus [Verfasser]. "Echtzeitvermessung dreidimensionaler Objekte mittels Speckle-Interferometrie / Markus Riemenschneider." Aachen : Shaker, 2006. http://d-nb.info/1186582251/34.

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43

Bertthelon, Xavier. "Speckle imaging and image processingapplied to life sciences." Thesis, KTH, Tillämpad fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161746.

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44

Rothberg, Steven Joseph. "Laser speckle studies for vibration and torque measurement." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241481.

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45

Standley, C. "Hardwired data processing applied to stellar Speckle interferometry." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46649.

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46

Borbely, Luiz Alberto. "Medida de rugosidade por correlação angular de speckle." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-14052014-160405/.

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Esse trabalho apresenta o método de correlação angular de speckle. Esse método foi melhorado para ser aplicado na medição de rugosidade na faixa de 30 m a 0,1 m. Um programa de computador foi desenvolvido para processar imagens e calcular a correlação angular, e novas fórmulas matemáticas foram deduzidas.
This work presents the speckle pattem angular correlation method. This method was improving to be applicable in the roughness measuring in the range of 0,1 m to 30 m. A software was developed to process image and to calculate the angular correlation, and new mathematical equations were formulating.

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47

Wan, Abdullah Wan Saffiey. "Analysis of error functions in speckle shearing interferometry." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/33652.

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Electronic Speckle Pattern Shearing Interferometry (ESPSI) or shearography has successfully been used in NDT for slope (δw/δx and/or δw/δy) measurement while strain measurement (δu/δx, δv/δy, δu/δy and δv/δx) is still under investigation This method is well accepted in industrial applications especially in the aerospace industry. Demand of this method is increasing due to complexity of the test materials and objects. ESPSI has successfully performed in NOT only for qualitative measurement whilst quantitative measurement is the current aim of many manufacturers. Industrial use of such equipment is being completed without considering the errors arising from numerous sources, including wavefront divergence. The majority of commercial systems are operated with diverging object illumination wavefronts without considering the curvature of the object illumination wavefront or the object geometry, when calculating the interferometer fringe function and quantifying data. This thesis reports the novel approach in quantified maximum phase change difference analysis for derivative out-of-plane (OOP) and in-plane (IP) cases that propagate from the divergent illumination wavefront compared to collimated illumination.

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48

Catheline, Stefan. "Interférométrie Speckle ultrasonore : application à la mesure d'élasticité." Paris 7, 1998. http://www.theses.fr/1998PA077193.

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49

Galushko, K. S. "Characteristics of «polychromatic speckle fields» and temporal coherence." Thesis, БДМУ, 2021. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18845.

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50

Song, Lipei. "Endoscopic laser speckle contrast analysis for tissue perfusion." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/10923.

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Laser speckle contrast analysis (LASCA), as a method of measuring blood flow speed and tissue perfusion, is a full field imaging technique requiring simple configurations and data processing, which is important for the application in real time in vivo. But LASCA is sensitive to changes in environmental factors. The application in vivo is also limited to superficial detection due to the limitation of the light penetration depth. Therefore this thesis aims to develop an endoscopic LASCA system to extend the access to internal detection and explore the relationship between the contrast and experimental parameters. Firstly the relationship between the contrast and speckle size, flow mode, quantity of stationary scatterers and the signal intensity were investigated. Theoretical models for the relationship between the contrast and the mean intensity of the speckle pattern were deduced and the correction methods were introduced to correct the contrast bias due to the intensity difference. Then a flexible single wavelength endoscopic laser speckle contrast analysis system (ELASCA) was developed using a leached fibre image guide (LFIG). A Butterworth filter and defocus were used to remove the fibre pattern to retrieve the contrast images. This system and the data processing methods were used on a customized phantom demonstrating that this ELASCA system can detect the flow speed changes in an imaging domain. Afterwards a dual-wavelength ELASCA was developed for functional imaging of the blood circulation. The test on a human fingertip and rabbit uterine blood vessels show that this system can monitor the change of blood flow speed and the oxygen saturation introduced by occlusion, in addition to the cardiac pulse and respiration rate. Then a novel application of LASCA to visualize the ultrasound pressure field and the propagation of the shear wave is presented for the application of locating area of interest (AOI) and detecting tissue variation.

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Dissertations / Theses on the topic 'Speckle'

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