La estructura y componentes del ojo humano hacen que los cambios que se producen sobre el estado de polarización de la luz que emerge de él, tras realizar un doble paso y sufrir una reflexión en la retina, sean complejos y a priori poco predecibles. Esos cambios pueden influir en los resultados obtenidos con dispositivos que analizan la luz reflejada en la retina. Para conocer mejor los cambios que el ojo origina sobre un haz que lo atraviesa y los fenómenos a los que da lugar, se ha llevado a cabo un estudio de la calidad de imagen retiniana en función de los estados de polarización, así como un estudio espacial de los distintos parámetros de polarización a partir del cálculo de matrices de Mueller. Teniendo como base el método de doble paso, se ha diseñado y construido un polarímetro de imagen que utiliza retardadores variables de cristal líquido en los brazos generador y analizador. Con este dispositivo se han registrado series de dieciséis imágenes de doble paso correspondientes a las combinaciones independientes de estados de polarización de entrada y salida. Los resultados para varios sujetos muestran que la calidad de imagen depende en gran medida del estado de polarización de salida. Sin embargo, la influencia de la polarización de entrada, calculada usando matrices de Mueller espacialmente resueltas, juega un papel poco significativo. Por otra parte, el estudio polarimétrico de las imágenes de doble paso muestra que (1) la parte central de las imágenes tiene un grado de polarización del 80% frente a un 25% en la periferia; (2) el retardo introducido depende del observador, aunque la birrefringencia que presenta el ojo es lineal; (3) el dicroísmo es coherente con la longitud de onda empleada y (4) el valor de la polarizancia indica la existencia de cierta birrefringencia circular. / The structure and components of the human eye make changes produced on the polarization state of the light emerging from it after a double-pass through ocular media and a reflection in the retina be complicated and hardly predectible. Those changes can influence on the results obtained with any device analyzing the light reflected in the retina. A study of the retinal image quality as a function of the polarization state has been performed. A spatially resolved polarimetric study of different polarization parameters using Mueller-matrices was also performed. An imaging polarimeter adapted to an ophthalmoscopic double-pass apparatus using two ellectronically controlled liquid-crystal variable retarders has been developed. Series of sixteen double-pass images corresponding to independent combinations generator-analyzer have been recorded. Results obtained for several subjects show that the estimation of the image quality depends strongly on the polarization state in the exit pathway. However, the influence of the entrance polarization, calculated using spatially resolved Mueller-matrices is nearly negligible. On the other hand, the polarimetric study of double-pass images shows that (1) the light forming the central part of the images presents a degree of polarization of 80% while this is reduced to around 25% for the light in the skirts; (2) the retardation introduced by the eye in a double-pass is quite dependent on observers, although the birefringence is linear; (3) the dicroism is coherent with the wavelength used, and (4) the value of the polarizance indicates the existency of circular birrefringence.

Au cours des dernières vingt années, le domaine de l'imagerie biomédicale a été largement développé. Dans ce cadre, cette thèse vise à la conception et à la réalisation d'un nouveau dispositif exploitant la longueur d'onde et l'état polarimétrique d'un faisceau lumineux. L'objectif final de cette méthode optique est l'application au diagnostic biomédical précoce, et plus particulièrement dans le domaine de la dermatologie. Il est important de rappeler que le milieu analysé ne subit ni biopsie ni injection d'agent de contraste. Ainsi, cette technique est non invasive et s'effectue sans contact. Par ailleurs, comme souvent en ce qui concerne l'optique visible, ce système est à faible coût et la calibration demeure relativement accessible; ce qui en fait un dispositif très bien adapté à l'utilisation en routine médicale a l'instar des sondes optiques qui équipent les saturomètres actuels. Dans une première partie de ce manuscrit, les méthodes mathématiques dites de "Stokes" et de "Mueller" sont présentées. Ceci nous permet d'introduire aisément la description de notre système polarimétrique ainsi que le calcul du degré de polarisation (DOP). Nous réservons tout un chapitre du manuscrit à la calibration du dispositif, à l'évaluation de ses possibilités ainsi qu'à ses limites théoriques et expérimentales. Ce protocole permet donc la mesure du degré de polarisation linéaire, circulaire et elliptique de tout système en rétrodiffusion. Ajoutons que cette mesure s'effectue en multispectrale suivant trois canaux bien définies (rouge, vert et bleu) et le tout en quasi temps-réel, c'est-à-dire a un rythme d'environ 12 images par seconde en pleine résolution. Le DOP, défini comme la différence normalisée des composante orthogonales du champ électrique, est étudiée et corrélé aux propriétés optique de diffusion des systèmes étudiés. Dans un premier temps, en nous appuyant sur une simulation de type Monte Carlo, le dispositif est validé sur de classiques solutions de billes de latex. Nous présenterons ensuite nos premiers résultats sur des images de peau effectuées in-vivo et ceci, sur un échantillon d'une trentaine d'individus. Nous dégageons ainsi les applications potentielles ainsi que les limites de ce dispositif concernant par exemple les signatures de différents phénomènes tels que brulures, cicatrices et naevus. Enfin, une conclusion et les perspectives de ce travail sont énoncées / (…) The domain of the biomedical imaging was widely developed. In this context, this thesis aims at the conception and at the realization of a new plan exploiting the wavelength and the state polarimétrique of a beam of light. The final goal of this optical method is the application in the early biomedical diagnosis, and more particularly in the field of the dermatology. It is important to call back that the analyzed environment does not undergo either biopsy or agent's injection of contrast. So, this technique is not invasive and is made without contact. Besides, as often as regards the visible optics, this system is low-cost and the calibration remains relatively accessible; What makes a device very well adapted to the use in medical routine has the instar of the optical probes which equip the current saturomètres. In a first part of this manuscript, the mathematical methods said about "Stokes" and about "Mueller" are presented. This allows us to introduce easily the description of our system polarimétrique as well as the calculation of the degree of polarization (DOP). We reserve a whole chapter of the manuscript for the calibration of the plan, for the evaluation of its possibilities as well as for his theoretical and experimental limits. This protocol thus allows the measure of the degree of linear, circular and elliptic polarization of any system rétrodiffusion. Let us add that this measure is made in multispectral according to three channels defined well (red, green and blue) and quite there almost time - reality, that is has a rhythm about 12 images per second in full resolution. The DOP, defined as the difference normalized of component orthogonal of the electric field, is studied and correlated in the properties optics of distribution of the studied systems

Les spin-lasers sont des dispositifs semi-conducteurs dans lesquels les processus de recombinaison radiative impliquant des porteurs polarisés en spin résultent en une émission de photons polarisés circulairement. Néanmoins, des anisotropies linéaires supplémentaires dans la cavité conduisent généralement à une émission laser préférentiellement polarisée linéairement et à un éventuel couplage entre modes. Dans cette thèse, une méthode générale pour la modélisation de lasers à semi-conducteurs tels que laser à surface verticale (externe) à cavité et contenant des puits quantiques multiples et impliquant des anisotropies pouvant révéler (i) une biréfringence linéaire locale due au champ de déformation à la surface ou (ii) une biréfringence dans les puits quantiques due au couplage d'amplitude de phase provenant de la réduction du D2d biaxial au groupe de symétrie C2v aux interfaces semiconductrices ternaires III-V. Une nouvelle méthode récursive à matrice S de diffusion est mise en œuvre en utilisant un tenseur de gain dérivé analytiquement des équations de Maxwell-Bloch. Il permet de modéliser les propriétés de l'émission (seuil, polarisation, dédoublement de mode) du laser avec plusieurs zones actives à puits quantiques en recherchant les modes propres résonnants de la cavité. La méthode est démontrée sur des structures laser réelles et est utilisée pour l'extraction de tenseurs de permittivité optique de déformation de surface et de puits quantiques en accord avec des expériences. La méthode est généralisée pour trouver les modes propres au laser dans le cas le plus général des pompes polarisées circulaires (déséquilibre entre les canaux de spin-up et de spin-down) et le dichroïsme à gain linéaire. De plus, la mesure de la matrice de Mueller 4x4 complète pour des angles d'incidence multiples et des angles azimutaux dans le plan a été utilisée pour l'extraction de tenseurs de permittivité optique de couches contraintes superficielles et de puits quantiques. Une telle dépendance spectrale des éléments tensoriels optiques est cruciale pour la modélisation des modes propres du laser de spin, les conditions de résonance, et aussi pour la compréhension des sources d'anisotropies de structure. / Spin-lasers are semiconductor devices in which the radiative recombination processes involving spin-polarized carriers result in an emission of circularly polarized photons. Nevertheless, additional linear in-plane anisotropies in the cavity generally lead in preferential linearly-polarized laser emission and to possible coupling between modes. In this thesis, a general method for the modeling of semiconductor laser such as vertical-(external)-cavity surface-emitting laser containing multiple quantum wells and involving anisotropies that may reveal i) a local linear birefringence due to the strain field at the surface or ii) a birefringence in quantum wells (QWs) due to phase amplitude coupling originating from the reduction of the biaxial D2d to the C2v symmetry group at the III-V ternary semiconductor interfaces. A novel scattering S-matrix recursive method is implemented using a gain tensor derived analytically from the Maxwell-Bloch equations. It enables to model the properties of the emission (threshold, polarization, mode splitting) from the laser with multiple quantum well active zones by searching for the resonant eigenmodes of the cavity. The method is demonstrated on real laser structures and is used for the extraction of optical permittivity tensors of surface strain and quantum wells in agreement with experiments. The method is generalized to find the laser eigenmodes in the most general case of circular polarized pumps (unbalance between the spin-up and spin-down channels) and linear gain dichroism. In addition, the measurement of full 4x4 Mueller matrix for multiple angles of incidence and in-plane azimuthal angles has been used for extraction of optical permittivity tensors of surface strained layers and quantum wells. Such spectral dependence of optical tensor elements are crucial for modeling of spin-laser eigenmodes, resonance conditions, and also for understanding of sources of structure anisotropies.

Master of Music / Department of Music / Gary C. Mortenson / This Master’s report contains biographical, historical, and theoretical analysis as well as stylistic and technical considerations for the four works performed for the author’s Master’s recital on April 29th, 2009. The works are Handel’s aria “Let the Bright Seraphim” from Samson, Franz Joseph Haydn’s Concerto for Trumpet in E Flat Major, Karl Jenkins’ Salm o Dewi Sant, and Erik Morales’ Concerto for Trumpet in C and Piano.

The Polarizer-Sample-Analyzer (PSA) arrangement with the optical components P and A rotating with a fixed speed ratio (3:1) was originally introduced to determine nine Mueller matrix elements from Fourier analysis of the output signal of a photodetector. The arrangement is modified to the P'PSAA' arrangement where P' and A' represent fixed polarizers that are added at both ends with the speed ratio of the rotating components (P and A) remaining the same as before. After determination of the partial Mueller matrix in the ideal case, azimuthal offsets and imperfection parameters are introduced in the straight-through configuration and the imperfection parameters are determined from the Fourier coefficients. Finally, the sample is reintroduced and the full Mueller matrix elements are calculated to show the deviation from the ideal case and their dependency on the offsets and imperfection parameters.

Este estudo abordou os aspectos teóricos e experimentais relacionados ao desenvolvimento de um sistema de tomografia por coerência óptica (OCT) no domínio de Fourier sensível à polarização (PS-FD-OCT) e a sua utilização na determinação da Matriz de Mueller (MM-OCT). O estudo iniciou-se com uma revisão bibliográfica que abordou desde os primeiros estudos relacionados à técnica até o estado da arte, bem como o formalismo matemático da interferometria de baixa coerência no domínio espectral e polarização da luz. Realizaram-se estudos baseados em simulação numérica sobre três tipos diferentes de algoritmos, responsáveis pela recuperação do sinal de espalhamento, sendo eles: a Transformada de Fourier Direta; Interpolação e Zero-Filling. Ao fim dessa etapa concluiu-se que o algoritmo Zero-Filling 2N apresentou melhores características quando comparado aos outros algoritmos. Na parte experimental, primeiramente, diferentes arranjos OCT foram montados e medidas realizadas para verificação aspectos relacionados à teoria. Consecutivamente, utilizando uma amostra polimérica, realizaram-se imagens de birrefringência, que permitiram a determinação da birrefringência da amostra quantitativamente. Finalmente, imagens em diferentes estados de polarização foram realizadas, através delas determinou-se as imagens referentes aos elementos das Matrizes de Mueller, que foram analisadas individualmente. / This study approached theoretical and experimental aspects related with the development of a polarization sensitive, Fourier domain, optical coherence tomography system (PS-FD-OCT) and its utilization on the Mueller Matrix determination. This work began with a bibliographic revision, which describes since the early studies to the actual state of the art of the technique. The mathematical formalism of Fourier domain low coherence interferometry and light polarization was performed as well. Studies based on numerical simulations, of three different algorithm types, responsible to recover the scattering profile, were done. The implemented algorithms were: Direct Fourier Transform, Interpolation and Zero-Filling. By the end of the simulation study, was possible to conclude that the algorithm Zero-Filling 2N presented better characteristics when compared with the others. In the experimental part, firstly different OCT setups were assembled and measurements were done in order to verify aspects related with the theory. Then, using a polymeric sample, birefringence images were performed, which allowed determining the sample birefringence quantitatively. Finally, images taken of different polarization states were collected, and through then images related with the Mueller Matrix elements were calculated, which were analyzed individually.

The 2016 American presidential election sent shockwaves through the world. Hillary Clinton the candidate that most experts predicted where going to win was beaten by a boisterous real estate developer from New York, Donald Trump. The language employed by president Trump both during and after his presidential campaign has been highly controversial, especially with the allusion to different forms of conspiracy theories. This essay investigates how Donald Trump alludes to conspiracy theories in relation to the Mueller investigation.

Avec la diminution constante de la taille des transistors dans la microélectronique, les outils de caractérisation doivent être de plus en plus précis et doivent fournir un débit de plus en plus élevé. La fabrication de semi-conducteurs étant un processus couche par couche, le positionnement précis de la pile est crucial. Le mauvais alignement de la pile est appelé overlay, et nous proposons ici un nouvel instrument et une nouvelle méthode pour caractériser avec précision l'overlay en mesurant une cible unique construite dans les lignes de découpe. La méthode utilise les propriétés fondamentales de symétrie de la matrice de Mueller mesurée dans le plan focal arrière d'un objectif de microscope à grande ouverture numérique et permet une caractérisation de l'overlay avec une incertitude de mesure totale de 2nm. Après une brève introduction à la polarisation et la matrice de Mueller, nous décrivons la nouvelle conception de l'instrument et son étalonnage complet. Le corps principal de ce manuscrit est dédié à la caractérisation de l'overlay, mais les applications de cet instrument sont très diverses aussi détaillerons nous comment notre instrument peut apporter des pistes pour la caractérisation et la compréhension de l'auto-organisation de l'exosquelette des scarabées. Ces coléoptères présentent un très fort dichroïsme circulaire et de nombreux groupes de recherche dans le monde entier essaient d'imiter leur exosquelette. Nous concluons ce manuscrit par un bref aperçu des principales perspectives pour notre instrument.

Measuring the Mueller matrix with optical coherence tomography (OCT) makes it possible to acquire the complete polarization properties of scattering media with three-dimensional spatial resolution. We first proved that the measured degree-of-polarization (DOP) of the backscattered light by OCT remains unity-a conclusion that validated the use of Jones calculus in OCT. A multi-channel Mueller-matrix OCT system was then built to measure the Jones-matrix, which can be transformed into a Mueller matrix, images of scattering biological tissues accurately with single depth scan. We showed that when diattenuation is negligible, the round-trip Jones matrix represents a linear retarder, which is the foundation of conventional PS-OCT, and can be calculated with a single incident polarization state although the one-way Jones matrix generally represents an elliptical retarder; otherwise, two incident polarization states are needed. We discovered the transpose symmetry in the roundtrip Jones matrix, which is critical for eliminating the arbitrary phase difference between the two measured Jones vectors corresponding to the two incident polarization states to yield the correct Jones matrix. We investigated the various contrast mechanisms provided by Mueller-matrix OCT. Our OCT system for the first time offers simultaneously comprehensive polarization contrast mechanisms including the amplitude of birefringence, the orientation of birefringence, and the diattenuation in addition to the polarization-independent intensity contrast, all of which can be extracted from the measured Jones or the equivalent Mueller matrix. The experimental results obtained from rat skin samples, show that Mueller OCT provides complementary structural and functional information on biological samples and reveal that polarization contrast is more sensitive to thermal degeneration of biological tissues than amplitude-based contrast. Finally, an optical-fiber-based multi-channel Mueller-matrix OCT was built and a new rigorous algorithm was developed to retrieve the calibrated polarization properties of a sample. For the first time to our knowledge, fiber-based polarization-sensitive OCT was dynamically calibrated to eliminate the polarization distortion caused by the single-mode optical fiber in the sample arm, thereby overcoming a key technical impediment to the application of optical fibers in this technology.

Ellipsometry is an optical technique used for studies of thin films and surfaces. The technique is based on measurement and analysis of the changes in the state of polarization that occur when polarized light is reflected on a sample surface. The multichannel Mueller matrix ellipsometer is a new system that is about to enter the commercial market. It can measure the full 4x4 Mueller matrix of a sample. The Laboratory of Applied Optics at the Department of Physics, Chemistry and Biology at Linköpings University has purchased one such multichannel Mueller matrix ellipsometer, called RC2, from J.A. Woollam Co., Inc. This project has the objective to investigate potentials and limitations of this new ellipsometer. This is done by comparing measurements carried out on RC2 with similar measurements made on a different, well known ellipsometer system, the VASE ellipsometer. A study of the theoretical background of ellipsometry has been made including a description of the Jones formalism of describing optical properties as well as the Stokes/ Mueller formalism. A short theoretical description of the RC2 principles, in order to better understand the new ellipsometer is also given. Measurements have been made on samples of varying complexity, including isotropic and anisotropic samples with in-plane anisotropy and out-of-plane anisotropy. On samples with no depolarization there should be no difference between the two ellipsometers. As can be seen in the experimental results there is some difference, but very little. Both for the isotropic samples, where Δ and ψ have been measured, and anisotropic, where the full Mueller matrix has been measured, we find a good match between VASE and RC2. When the samples are depolarizing, we expect to see a difference in the Mueller matrix. We do notice a significant difference in the measurements on tilted nanometer rods of TiO2, which has an advanced nano-structure in the upper layer. We can thus conclude that samples with depolarizing properties reveal this when measured with the new RC2 ellipsometer.