UWB technology has been developing in imaging applications. For security imaging applications, it is vital to detect and image metallic targets concealed in bag at airports, subway stations or other public environments. To reduce the cost of the deployment of X-ray machines, a novel UWB imaging system has been developed, including the design of the UWB rotating antenna array, the design of RF circuits and the implementation of the two-dimensional delay-and-sum (DAS) image reconstruction method. Two types of UWB antennas, the circular-edge antipodal Vivaldi antenna and the corrugated balanced antipodal Vivaldi antenna (BAVA) have been designed and studied in both frequency domain and time domain. Both of them can work across UWB frequency range from 3.1 GHz to 10.6 GHz, and have directional radiation patterns. The corrugated BAVA with smaller physical size has been improved to have a relative high gain around 7 dBi across the operating frequency range. It also causes less distortion to signals in the time domain. So the corrugated BAVA is used as the antenna element in the UWB rotating antenna array. The UWB rotating antenna array comprises one central transmitting antenna and four receiving antennas. The receiving antennas, which rotate around the central transmitting antenna, are placed side-by-side on a straight arm. The equivalent antenna elements in space are increased by the rotation of the antenna array. The two-dimensional image reconstruction method has been developed based on DAS algorithm. This UWB imaging system can detect and reconstruct the image of the single and pairs of metallic targets concealed in bag. The smallest single target with the size of 4 cm × 4 cm × 1 cm can be reconstructed in images at a maximum distance of 30 cm away from the system. It can achieve 6 cm in cross-range resolution and 15 cm in down-range resolution. Therefore, the feasibility of the proposed UWB imaging system has been proved.

Imaging of biomolecules on the nano-scale is a crucial developing technology with major implications for our understanding of biological systems and for detection and therapy of disease. Plasmonic nanoparticles are a key optical contrast agent whose signal is generated by the collective oscillation of electrons in the metal particle. The resonance behavior of the electrons depends strongly on the arrangement of neighboring nanoparticles in a structure. This property may be exploited in imaging applications to report information on nanoscale morphology of targeted biomolecules. While the effect of plasmon resonance coupling has been studied in dimers and linear arrays of nanoparticles, this phenomenon remains largely unexplored in the case of 2D and 3D assemblies which are important in molecular cell imaging. This dissertation demonstrates how the optical signal from assemblies of gold nanoparticles can be related to nanoscale morphology in cellular imaging systems. First, the scattering spectra from live cells labeled with gold nanoparticles were collected and compared to the nanoscale arrangement of the particles in the same cells as determined by electron micrograph. Then, trends in scattering spectra with respect to nanoparticle arrangement were analyzed using a model system that allowed precise control over arrangement of nanoparticles. Several approaches to creating these model systems are discussed including biochemical linking, capillary assembly of colloidal particles, and direct deposition of gold onto substrates patterned by electron beam lithography. Spectral properties of the assemblies including peak position, width, and intensity are gathered and related to model variables including interparticle gap and overall particle number. It is shown that the redshift in the scattering spectra from nanoparticle assemblies is derived from both the particle number and the gap and is due to near-field coupling of particles as well as phase retardation of the scattered wave. The redshift behavior saturates as the number of particles in the aggregate increases but the saturation point depends strongly on interparticle gap. The drastic dependence of the red-shift saturation on the gap between nanoparticles has not been previously described; this phenomenon can have significant impact on the development of nanoparticle contrast agents and plasmonic sensor arrays. / text

Cette thèse étudie l’intérêt de la mesure de la diffusion cohérente de rayons X dans le cadre de l’imagerie du sein à des fins de diagnostic. Aujourd'hui, la plupart des systèmes d'imagerie médicale par rayons X exploitent le rayonnement transmis à travers les tissus. C’est le cas pour la mammographie, qui est la modalité d’imagerie du sein la plus courante. L'apparition récente de détecteurs résolus en énergie, à base de semi-conducteurs notamment, permet cependant d'envisager l'exploitation en milieu clinique d'un autre phénomène : le rayonnement diffusé cohérent. La mesure de spectres de diffusion peut apporter de nouvelles informations liées à la structure moléculaire des tissus examinés pour mieux les caractériser et ainsi améliorer le diagnostic final. Deux modalités sont envisagées : la détection in vivo de tumeurs du sein, à la suite d’une mammographie présentant un résultat suspect ou l'analyse de biopsie.Le système de mesure de diffusé développé lors de cette thèse exploite les détecteurs résolus en énergie de type CdZnTe, ces derniers présentant des caractéristiques (résolution en énergie, sensibilité, résolution spatiale, compacité) prometteuses pour une utilisation en condition clinique. Il se base par ailleurs sur la pixellisation du détecteur afin de proposer une modalité d’imagerie permettant de caractériser les matériaux ou tissus traversés dans une direction sans translation ni rotation.Cette thèse propose ainsi une étude complète de ce système, articulée autour de trois grandes parties : modélisation puis simulation du système de mesure, développement du traitement des données mesurées par le détecteur afin d’imager et caractériser l’échantillon analysé et enfin, dimensionnement d’un banc expérimental plus complexe intégrant un détecteur complet et un système de collimation multifente. Ces trois parties font par ailleurs l’objet de validations expérimentales associées. / This thesis studies the interest of measuring the coherent scattering of X-rays for breast diagnosis imaging. Nowadays, most of X-ray-based medical imaging techniques use the information of X-rays attenuation through the tissues. It is the case for mammography, the most common breast imaging modality. The recent emergence of energy resolved detectors (based on semiconductors in particular) allows to consider using another phenomenon: the coherent X-ray scattering. Measurement of diffracted spectra can provide new information related to the molecular structure of the examined tissues, in order to improve their characterization and therefore improve the final diagnosis. Two modalities are considered: the breast cancer detection in vivo, following a suspicious mammography result, or biopsy analysis.The coherent scattering measurement system developed during this thesis work uses energy-resolved CdZnTe-based detectors, these detectors combining performances (energy resolution, sensitivity, spatial resolution, and compactness) promising for clinical application. This system is also based on the detector pixelation, which allows to provide an imaging modality capable of characterizing analyzed materials or tissues in one direction without any translation or rotation.A complete study of the measurement system is proposed in this thesis, structured in three main parts: modeling and simulation of the system, development of the processing of the data measured by the detector in order to image and characterize the analyzed sample and finally, designing of a new and more complex experimental setup based on a whole detector and multislit collimation system. An experimental validation is proposed for each of these three parts.

For the past several decades, challenges in the detection and collection of latent prints exposed to harsh environmental conditions have inspired research in pretreatment methods prior to the application of chemical, physical, or optical-based enhancement techniques. Some of the difficulties associated with processing degraded latent prints are attributed to dehydration, alterations in chemical composition, and physical disturbance of ridge detail. This study seeks to investigate the effectiveness of humidity, cyanoacrylate fuming method (CFM), and a reflected ultraviolet imaging system (RUVIS) on the detection and collection of aged latent palmprints. Prints were exposed to air flow and ultraviolet (UV) light for a period of 0 to 28 days, and subsequently treated with either cool or warm humidity and CFM. RUVIS was then utilized to detect and capture friction ridge detail after each treatment step. Improvements in RUVIS detection between treatments were evaluated based on four response factors: minutiae count, percent print recovery, ridge thickness and contrast. By measuring these factors, each latent print photograph was able to be converted to quantifiable data to facilitate statistical analysis of potential differences or improvements between treatments. The results demonstrate that the application of 80% relative humidity successfully revived aged latent palmprints across all factors. The combined effect of humidity followed v by CFM treatment and RUVIS detection was greatest for minutiae count and ridge thickness, while percent print recovery and contrast demonstrated more modest improvements when compared to control prints. Additionally, cool temperature treatments outperformed warm temperature treatments across all factors except contrast. The data therefore suggest that to achieve print rejuvenation and overall improvements in RUVIS detection, combined cool humidity and CFM is more effective than humidity alone. The data also indicate a potential correlation between temperature treatments and latent print age. Warm humidity combined with CFM appeared to best enhance RUVIS images on fresher prints of a few days to one week old, while cool humidity and CFM appeared to maximally enhance RUVIS images on prints of several weeks old.

During the DARPA SCENICC program, J. Ford, et al., demonstrated that CFBs provide a compelling route to compact, wide angle imagers. Monocentric lenses readily provide diffraction-limited images over wide field but onto a hemispherically curved image surface. They demonstrated visible CFBs can be tapered, cut and polished to relay curved images to flat sensors. We have shown that this provides a volumetric imaging efficiency a hundredfold larger than bulk optics can produce; a hundred times the resolution in the same volume or a hundred times less volume for the same resolution. Ford's work leveraged commercial fiber bundles available for the visible spectrum based on silica. We have developed hybrid fiber bundles using step-index confinement between chalcogenide glass cores and polymer cladding with high index-contrast. The high contrast is necessary to provide tight confinement to the high-index As-Se core with minimal crosstalk between closely spaced cores. Tight confinement also minimizes absorption losses in the PEI polymer cladding. The high contrast of this system also provides a large NA to optimize coupling into the CFB from fast lenses. We introduce disorder into the core radius as a mechanism to further decouple adjacent cores, reduce crosstalk and increase fill-factor. We present coupled-mode theory, modal crosstalk superposition, and finite-element modelling to quantify coupling losses and crosstalk as a function of geometry and disorder. We fabricated preforms, drew small fiber bundles and characterized optical properties of the bundles to aid scale-up to megapixel MWIR CFBs.

No description available.

Cette thèse s'inscrit dans le cadre de la mission spatiale Rosetta et porte sur les propriétés spectrophotométriques de la comète 67P/Churyumov-Gerasimenko à l’aide de l’instrument OSIRIS. Cet instrument est composé de deux caméras pour les observations du noyau et de la coma de la comète. Elles permettent d’acquérir des images avec des filtres qui opèrent dans la gamme du proche UV au proche IR. Dans un premier temps, j'ai analysé les courbes spectrophotométriques des taches claires qui sont apparues sur le noyau de la comète. Une étude comparative de celles-ci grâce aux données du spectro-imageur VIRTIS a ainsi permis de constater que les taches claires sont liées à la glace de H2O. Dans un second temps, j’ai entrepris une étude spectrophotométrique de la région Khonsu, qui a mis en évidence les variations saisonnières de la pente spectrale de différents terrains. Par la suite, j’ai élargi mon analyse des taches à tout le noyau de la comète. J’ai détecté plus de 50 taches claires dues à la présence de glace de H2O et j’ai produit une carte pour repérer leurs emplacements sur le noyau, afin d’étudier plus en détail leur répartition et leur évolution au cours de temps. Ceci m’a permis d’identifier quatre types de taches regroupés en fonction de leur morphologie et de constater qu'elles sont dues à différentes sources d'activité cométaire. / This thesis is based on the spectrophotometric properties of the comet 67P/Churyumov-Gerasimenko, using the OSIRIS instrument of Rosetta space mission. Composed of two scientific cameras to observe the nucleus and the coma of the comet, OSIRIS images are acquired with multiple filters, that span the near-UV to near-IR wavelength range. They were used to study the spectrophotometric curves of the exposed bright features that appeared on the surface of the cometary nucleus, leading to a comparative study, that was carried out in collaboration with the VIRTIS spectro-imager aboard Rosetta, that demonstrated, that these exposures are related to H2O ice, using its absorption band located at 2 microns. The thesis further details a spectrophotometric study of the Khonsu region in the southern latitudes of the comet, where the seasonal variation of the spectral slope of different types of terrains is explored. Finally, the results of an extended survey of exposed bright features are presented. More than 50 individual features are presented under four morphologies along with an albedo calculation, suggesting that different activity sources are responsible for their appearance on the nucleus.

The research uses cameras mounted to a vehicle to capture geotagged images while conducting a transect survey. The images from two capture dates were manually classified into different classes of previous crop, tillage systems, residue cover, and cover crop utilization. The raw data was compared against the Indiana Cropland Transect Survey and the USDA-NASS Cropland Data Layer. The symmetric Kullback-Liebler divergence method was used to compared the distributions looking for similarities. <div><br></div><div>The manually classified data was then used to build satellite segmentation models using artificial neural networks , decision trees, k nearest neighbors, random forests, and support vector machine methods. The models were compared using overall accuracy, kappa coefficient, specificity, sensitivity, positive prediction value, and negative prediction value. The best model for each category of previous crop, tillage system, residue cover, and cover crop was used to segment a Sentenial-2 imagery downloaded from Copernicus Open Access hub. The results of the segment were compared by looking at the agreement at individual pixel locations from the segmented raster to the manually classified data and the Indiana Cropland Transect Survey. </div><div><br></div><div>Finally, all the images captured were used to being the development of a automated image classifier using nested convolutional neural networks (CNN). A small set of images was used to build the CNN. That model when then make prediction on new unclassified images. The predictions were manually checked. The check images were used to the to build the training and validation pools for the models. The first network divided the images into field or not field.</div><div>The second branch was field images divided in to images containing green growing plants of brown dead plants or residues. The final branch was determining the amount of surface cover left on a field. The results from each run of the training process were saved and used to assess model performance looking at accuracy and loss.</div>

A repetitividade dos golpes em uma partida de tênis pode sobrecarregar a musculatura do punho e predispor a lesões, como a epicondilite lateral. A presente pesquisa propõe o uso de visão computacional para a obtenção de imagens tridimensionais reconstruídas, valores de forças atuantes em grupos musculares e articulações específicas e posições, velocidades e acelerações. O objetivo deste estudo é propor um método para descrever as características biomecânicas dos movimentos do punho durante a prática do tênis de campo, segundo as técnicas de punho rígido, a partir de parâmetros dinâmicos e cinemáticos, segundo variáveis físicas e antropométricas. Um indivíduo do sexo masculino, que possuí domínio das técnicas analisadas, realizou cinco sequências do movimento forehand em um laboratório de análise do movimento. Foi utilizado um sistema de aquisição de imagens (Qualisys Motion Capture Systems) que permitiu a reconstrução tridimensional dos movimentos dos segmentos. A partir de dados obtidos, através do sistema, verificou-se que os torques encontrados nos três eixos de movimento do punho, correspondentes aos movimentos de pronação, desvio ulnar e flexão de punho, apresentam magnitudes de 1.11 Nm, 3.98 Nm e 7.68 Nm, respectivamente. Verificou-se o maior valor de torque em torno do eixo z (flexão do punho), que será sustentado pela musculatura extensora de punho. A sobrecarga repetitiva dessa musculatura pode desencadear a epicondilite lateral. / The repeatability of the hitting in a tennis match can overload the muscles of the wrist and predispose to injury, such as lateral epicondylitis. This research proposes the use of computer vision for obtaining reconstructed three-dimensional images, active forces values in specific joints and muscle groups and positions, velocities and accelerations. The objective of this study is to propose a method to describe the biomechanical characteristics of the movements of the wrist during the practice of court tennis, using static wrist techniques, from kinematic and dynamic parameters, according to physical and anthropometric variables. A male person, who possess mastery of the techniques analyzed, held five forehand motion sequences in a laboratory analysis of the movement. It was used an image acquisition system (Qualisys Motion Capture Systems) that allowed the three-dimensional reconstruction of the movements of the segments. From the data obtained, through the system, it was found the torques in the three axes of motion of the wrist, corresponding to the movements of pronation, wrist flexion and ulnar deviation, which presented magnitudes of 1.11 Nm, 3.98 Nm and 7.68 Nm, respectively. It was found the greatest value of torque around the z axis (wrist flexion), which will be sustained by the extensor muscle of wrist. Repetitive overload of this muscle can unleash the epicondylitis.

A repetitividade dos golpes em uma partida de tênis pode sobrecarregar a musculatura do punho e predispor a lesões, como a epicondilite lateral. A presente pesquisa propõe o uso de visão computacional para a obtenção de imagens tridimensionais reconstruídas, valores de forças atuantes em grupos musculares e articulações específicas e posições, velocidades e acelerações. O objetivo deste estudo é propor um método para descrever as características biomecânicas dos movimentos do punho durante a prática do tênis de campo, segundo as técnicas de punho rígido, a partir de parâmetros dinâmicos e cinemáticos, segundo variáveis físicas e antropométricas. Um indivíduo do sexo masculino, que possuí domínio das técnicas analisadas, realizou cinco sequências do movimento forehand em um laboratório de análise do movimento. Foi utilizado um sistema de aquisição de imagens (Qualisys Motion Capture Systems) que permitiu a reconstrução tridimensional dos movimentos dos segmentos. A partir de dados obtidos, através do sistema, verificou-se que os torques encontrados nos três eixos de movimento do punho, correspondentes aos movimentos de pronação, desvio ulnar e flexão de punho, apresentam magnitudes de 1.11 Nm, 3.98 Nm e 7.68 Nm, respectivamente. Verificou-se o maior valor de torque em torno do eixo z (flexão do punho), que será sustentado pela musculatura extensora de punho. A sobrecarga repetitiva dessa musculatura pode desencadear a epicondilite lateral. / The repeatability of the hitting in a tennis match can overload the muscles of the wrist and predispose to injury, such as lateral epicondylitis. This research proposes the use of computer vision for obtaining reconstructed three-dimensional images, active forces values in specific joints and muscle groups and positions, velocities and accelerations. The objective of this study is to propose a method to describe the biomechanical characteristics of the movements of the wrist during the practice of court tennis, using static wrist techniques, from kinematic and dynamic parameters, according to physical and anthropometric variables. A male person, who possess mastery of the techniques analyzed, held five forehand motion sequences in a laboratory analysis of the movement. It was used an image acquisition system (Qualisys Motion Capture Systems) that allowed the three-dimensional reconstruction of the movements of the segments. From the data obtained, through the system, it was found the torques in the three axes of motion of the wrist, corresponding to the movements of pronation, wrist flexion and ulnar deviation, which presented magnitudes of 1.11 Nm, 3.98 Nm and 7.68 Nm, respectively. It was found the greatest value of torque around the z axis (wrist flexion), which will be sustained by the extensor muscle of wrist. Repetitive overload of this muscle can unleash the epicondylitis.