Dissertations / Theses on the topic 'Polarimetrie'

Soil conditions under vegetation cover and their spatial and temporal variations from point to catchment scale are crucial for understanding hydrological processes within the vadose zone, for managing irrigation and consequently maximizing yield by precision farming. Soil moisture and soil roughness are the key parameters that characterize the soil status. In order to monitor their spatial and temporal variability on large scales, remote sensing techniques are required. Therefore the determination of soil parameters under vegetation cover was approached in this thesis by means of (multi-angular) polarimetric SAR acquisitions at a longer wavelength (L-band, lambda=23cm). In this thesis, the penetration capabilities of L-band are combined with newly developed (multi-angular) polarimetric decomposition techniques to separate the different scattering contributions, which are occurring in vegetation and on ground. Subsequently the ground components are inverted to estimate the soil characteristics. The novel (multi-angular) polarimetric decomposition techniques for soil parameter retrieval are physically-based, computationally inexpensive and can be solved analytically without any a priori knowledge. Therefore they can be applied without test site calibration directly to agricultural areas. The developed algorithms are validated with fully polarimetric SAR data acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR) for three different study areas in Germany. The achieved results reveal inversion rates up to 99% for the soil moisture and soil roughness retrieval in agricultural areas. However, in forested areas the inversion rate drops significantly for most of the algorithms, because the inversion in forests is invalid for the applied scattering models at L-band. The validation against simultaneously acquired field measurements indicates an estimation accuracy (root mean square error) of 5-10vol.% for the soil moisture (range of in situ values: 1-46vol.%) and of 0.37-0.45cm for the soil roughness (range of in situ values: 0.5-4.0cm) within the catchment. Hence, a continuous monitoring of soil parameters with the obtained precision, excluding frozen and snow covered conditions, is possible. Especially future, fully polarimetric, space-borne, long wavelength SAR missions can profit distinctively from the developed polarimetric decomposition techniques for separation of ground and volume contributions as well as for soil parameter retrieval on large spatial scales.
Zur Verbesserung der hydrologischen Abflussmodellierung, der Flutvorhersage, der gezielten Bewässerung von landwirtschaftlichen Nutzflächen und zum Schutz vor Ernteausfällen ist die Bestimmung der Bodenfeuchte und der Bodenrauhigkeit von grosser Bedeutung. Aufgrund der hohen zeitlichen sowie räumlichen Dynamik dieser Bodenparameter ist eine flächenhafte Erfassung mit hoher Auflösung und in kurzen zeitlichen Abständen notwendig. In situ Messtechniken stellen eine sehr zeit- und personalaufwändige Alternative dar, deshalb werden innovative Fernerkundungsverfahren mit aktivem Radar erprobt. Diese Aufnahmetechniken sind von Wetter- und Beleuchtungsverhältnissen unabhängig und besitzen zudem die Möglichkeit, abhängig von der Wellenlänge, in Medien einzudringen. Mit dem in dieser Arbeit verwendeten polarimetrischen Radar mit synthetischer Apertur (PolSAR) werden die Veränderungen der Polarisationen ausgewertet, da diese aufgrund der physikalischen Eigenschaften der reflektierenden Medien objektspezifisch verändert und gestreut werden. Es kann dadurch ein Bezug zwischen der empfangenen Radarwelle und den dielektrischen Eigenschaften (Feuchtegehalt) sowie der Oberflächengeometrie (Rauhigkeit) des Bodens hergestellt werden. Da vor allem in den gemässigten Klimazonen die landwirtschaftlichen Nutzflächen die meiste Zeit des Jahres mit Vegetation bestanden sind, wurden in dieser Dissertation Verfahren entwickelt, um die Bodenfeuchte und die Bodenrauhigkeit unter der Vegetation erfassen zu können. Um die einzelnen Rückstreubeiträge der Vegetation und des Bodens voneinander zu trennen, wurde die Eindringfähigkeit von längeren Wellenlängen (L-band, lambda=23cm) mit neu entwickelten (multi-angularen) polarimetrischen Dekompositionstechniken kombiniert, um die Komponente des Bodens zu extrahieren und auszuwerten. Für die Auswertung wurden polarimetrische Streumodelle benutzt, um die Bodenkomponente zu modellieren und dann mit der extrahierten Bodenkomponente der aufgenommenen Daten zu vergleichen. Die beste Übereinstimmung von Modell und Daten wurde als die gegebene Bodencharakteristik gewertet und dementsprechend invertiert. Die neu entwickelten, polarimetrischen Dekompositionstechniken für langwelliges polarimetrisches SAR basieren auf physikalischen Prinzipien, benötigen wenig Rechenzeit, erfordern keine Kalibrierung und sind ohne Verwendung von a priori Wissen analytisch lösbar. Um die entwickelten Algorithmen zu testen, wurden in drei verschiedenen Untersuchungsgebieten in Deutschland mit dem flugzeuggetragenen E-SAR Sensor des Deutschen Zentrums für Luft- und Raumfahrt (DLR) polarimetrische SAR Daten aufgenommen. Die Auswertungen der PolSAR Daten haben bestätigt, dass die besten Invertierungsergebnisse mit langen Wellenlängen erzielt werden können (L-Band). Des Weiteren konnten bei der Bestimmung der Bodenfeuchte und der Bodenrauhigkeit hohe Inversionsraten erreicht werden (bis zu 99% der Untersuchungsfläche). Es hat sich gezeigt, dass die polarimetrischen Streumodelle bei der gegebenen Wellenlänge nicht für bewaldete Gebiete geeignet sind, was die Anwendbarkeit des Verfahrens auf landwirtschaftliche Nutzflächen einschränkt. Die Validierung mit Bodenmessungen in den Untersuchungsgebieten, die zeitgleich zu den PolSAR Aufnahmen durchgeführt wurden, hat ergeben, dass eine kontinuierliche Beobachtung des Bodenzustandes (ausgenommen in Zeiten mit gefrorenem oder Schnee bedecktem Boden) mit einer Genauigkeit (Wurzel des mittleren quadratischen Fehlers) von 5-10vol.% für die Bodenfeuchte (in situ Messbereich: 1-46vol.%) und von 0.37-0.45cm für die Bodenrauhigkeit (in situ Messbereich: 0.5-4.0cm) möglich ist. Besonders künftige Fernerkundungsmissionen mit langwelligem, voll polarimetrischem SAR können von den entwickelten Dekompositionstechniken profitieren, um die Vegetationskomponente von der Bodenkomponente zu trennen und die Charakteristik des Oberbodens flächenhaft zu bestimmen.

Le travail effectue propose une extension de la theorie de la polarimetrie radar, elaboree pour des systemes de mesures monostatiques, vers une theorie applicable a des systemes de mesures bistatiques. L'objectif de cette etude est de fournir des outils permettant de decrire les cibles dans le but de les caracteriser, de les classifier, voire de les identifier. Toute cible peut etre consideree, suivant sa structure, comme un modificateur plus ou moins fort de l'etat de polarisation de l'onde emise, vis-a-vis de l'onde diffusee. Elle est modelisee par une matrice, appelee matrice de diffusion. La volonte de detecter des cibles dites furtives accroit l'interet de mesurer la polarisation de l'onde diffusee, car ces cibles depolarisent generalement fortement et ne sont pas reperables par des radars scalaires. De plus, certaines cibles ne diffusent qu'un speculaire dans la direction de propagation-avant et seul un radar en configuration bistatique pourra les detecter. L'approche choisie pour fonder la theorie de la polarimetrie radar repose sur la decomposition de la matrice de diffusion bistatique en la somme d'une matrice symetrique et d'une matrice antisymetrique. La matrice symetrique permet de conserver les proprietes du cas monostatique, alors que la matrice antisymetrique denote le caractere purement bistatique de la configuration du systeme de mesures. Dans notre etude, nous nous sommes inspires de la demarche proposee par j. R. Huynen lors de l'elaboration de la theorie de la polarimetrie radar monostatique. Nous avons defini sept nouveaux parametres bistatiques fonction des elements de la matrice de diffusion bistatique. Ils viennent s'ajouter aux neuf parametres de huynen dependant de la partie symetrique. Ces seize parametres permettent alors de specifier la matrice de kennaugh. Cinq nouvelles equations de cibles bistatiques ont ete etablies, leur nombre total s'elevant ainsi a neuf. Ces neuf relations independantes, liant entre eux les seize parametres bistatiques, se construisent directement a l'aide du diagramme structurel bistatique d'une cible, appele aussi berlingot, que nous avons defini. Quatorze etats de polarisation caracteristiques de la cible sont proposes et leurs vecteurs de jones sont determines. Les positions relatives de ces points, visualisees sur la sphere de poincare, forment la fourchette de polarisation bistatique qui est geometriquement definie par six angles. Ces angles constituent, avec la puissance maximale copolarisee liee au rayon de la sphere de poincare, les parametres d'euler bistatiques. Une premiere approche de l'etude phenomenologique bistatique, reposant sur differentes cibles canoniques, est presentee. Les evolutions des seize parametres bistatiques suivant differentes configurations sont visualisees. Enfin, dans l'hypothese d'une mise en oeuvre d'une campagne de mesures bistatiques et polarimetriques de cibles, plusieurs methodes de calibration bistatiques sont presentees.

Cette thèse a été consacrée au développement et à la mise en oeuvre d’un imageur polarimétrique de Müller installé sur un colposcope standard dans le but de diagnostiquer invivo des lésions précancéreuses du col utérin.Ce travail s’est appuyé sur le développement réalisé durant les dix dernières années au LPICM à l'École polytechnique d’une nouvelle technologie d'imagerie médicale non invasive et a priori adaptée à la détection précoce du cancer : l’imagerie polarimétrique
This thesis was devoted to the development and the implementation of a polarimetric imager of Müller installed on a standard colposcope in order to diagnose invivo precancerous lesions of the cervix.This work was based on the development carried out during the last ten years at the LPICM at the Ecole polytechnique of a new non-invasive medical imaging technology and a priori adapted to the early detection of cancer: polarimetric imaging

Diese (Doktor)arbeit beschäftigt sich mit Radar-Polarimetrie, insbesondere mit der Untersuchung der Eigenschaften von polarimetrischen Variablen, die potenziellen Nutzen für die Radar-Meteorologie haben. Für den Einsatz in Dual-Polarisations-Radargeräten wird der Polarisationsgrad analysiert. Diese Variable wird in künftigen operationellen Radargeräten verfügbar sein. Der Polarisationsgrad hängt vom transmittierten Polarisationszustand und in weiterer Folge auch vom Betriebsmodus des Radargeräts ab. Der Hauptbetriebsmodus von operationellen Radargeräten sendet und empfängt gleichzeitig sowohl die horizontale als auch die vertikale Komponente. Der sekundäre Betriebsmodus sendet und empfängt simultan die horizontal polarisierte Komponente. In dieser Arbeit werden beide Polarisationsgrade untersucht. Da operationelle Systeme derzeit auf den Dual-Polarisationsmodus aufgerüstet werden, sollte künftig die Anwendungsmöglichkeiten von vollpolarimetrischen Wetterradarsystemen untersucht werden. Aus allen Variablen, die in diesem Betriebsmodus zur Verfügung stehen, wurde die Entropie (des gemessen Objektes) ausgewählt und wegen seiner engen Beziehung zum Polarisationsgrad näher untersucht
The present doctoral thesis deals with radar polarimetry, namely with the investigation of properties of polarimetric variables potentially useful in radar meteorology. For use with dual-polarization radars, the degree of polarization is analyzed. This variable is available to planned operational radars. The degree of polarization is dependent on transmit polarization state and, consequently, it is dependent on the radar system operating mode. The primary operating mode of operational radars consists in simultaneous transmission and simultaneous receive of both horizontal and vertical components. The secondary operating mode consists of horizontal transmission and simultaneous receive. Both degrees of polarization are investigated in this thesis. Also, as operational systems are being updated to dual-polarization, research should start investigating the capabilities of fully polarimetric weather radar systems. Among the numerous variables available from this operating mode, the target entropy was chosen for investigation, also because of its close relation to the degree of polarization

Utilisation d'un polarimetre photoelectrique monocanal, dans le domaine visible et uv, pour l'observation de l'enveloppe de poussieres de deux supergeantes rouges, des poussieres contenues dans 5 nebuleuses planetaires et des bandes moleculaires de fluorescence des cometes de halley et de hartley-good

Le cea/dapnia travaille a la conception d'un nouveau type de polarimetre compton pour l'experience happex a cebaf. Cet instrument est base sur l'utilisation d'un resonateur optique qui permet une recirculation de la lumiere pour obtenir une grande densite de photons polarises au point d'interaction compton. Ce travail de these est la premiere etude pour un tel instrument. Il enonce les caracteristiques d'une cavite optique permettant une mesure rapide de la polarisation. Mes contributions aux essais de prototypes sont detaillees. Un gain en puissance > 160 a ete obtenu avec des miroirs de qualite modeste. Des mesures concernant l'asservissement en frequence du laser, le couplage optique du faisceau laser avec la cavite et la caracterisation de la puissance intra-cavite y sont egalement decrite. La conclusion indiaue les differentes etapes qu'il reste a franchir avant de pouvoir installer une telle cavite sur la ligne faisceau de cebaf.

Die Arbeit beschreibt die Analyse von Beobachtungen zweier Sonnenflecken in zweidimensionaler Spektro-Polarimetrie. Die Daten wurden mit dem Fabry-Pérot-Interferometer der Universität Göttingen am Vakuum-Turm-Teleskop auf Teneriffa erfasst. Von der aktiven Region NOAA 9516 wurde der volle Stokes-Vektor des polarisierten Lichts in der Absorptionslinie bei 630,249 nm in Einzelaufnahmen beobachtet, und von der aktiven Region NOAA 9036 wurde bei 617,3 nm Wellenlänge eine 90-minütige Zeitserie des zirkular polarisierten Lichts aufgezeichnet. Aus den reduzierten Daten werden Ergebniswerte für Intensität, Geschwindigkeit in Beobachtungsrichtung, magnetische Feldstärke sowie verschiedene weitere Plasmaparameter abgeleitet. Mehrere Ansätze zur Inversion solarer Modellatmosphären werden angewendet und verglichen. Die teilweise erheblichen Fehlereinflüsse werden ausführlich diskutiert. Das Frequenzverhalten der Ergebnisse und Abhängigkeiten nach Ort und Zeit werden mit Hilfe der Fourier- und Wavelet-Transformation weiter analysiert. Als Resultat lässt sich die Existenz eines hochfrequenten Bandes für Geschwindigkeitsoszillationen mit einer zentralen Frequenz von 75 Sekunden (13 mHz) bestätigen. In größeren photosphärischen Höhen von etwa 500 km entstammt die Mehrheit der damit zusammenhängenden Schockwellen den dunklen Anteilen der Granulen, im Unterschied zu anderen Frequenzbereichen. Die 75-Sekunden-Oszillationen werden ebenfalls in der aktiven Region beobachtet, vor allem in der Lichtbrücke. In den identifizierten Bändern oszillatorischer Power der Geschwindigkeit sind in einer dunklen, penumbralen Struktur sowie in der Lichtbrücke ausgeprägte Strukturen erkennbar, die sich mit einer Horizontalgeschwindigkeit von 5-8 km/s in die ruhige Sonne bewegen. Diese zeigen einen deutlichen Anstieg der Power, vor allem im 5-Minuten-Band, und stehen möglicherweise in Zusammenhang mit dem Phänomen der „Evershed-clouds“. Eingeschränkt durch ein sehr geringes Signal-Rausch-Verhältnis und hohe Fehlereinflüsse werden auch Magnetfeldvariationen mit einer Periode von sechs Minuten am Übergang von Umbra zu Penumbra in der Nähe einer Lichtbrücke beobachtet. Um die beschriebenen Resultate zu erzielen, wurden bestehende Visualisierungsverfahren der Frequenzanalyse verbessert oder neu entwickelt, insbesondere für Ergebnisse der Wavelet-Transformation.
The publication describes the analysis of two sunspot observations in two-dimensional spectropolarimetry. The data was obtained with the Fabry-Pérot-interferometer of Göttingen University at the German Vacuum Tower Telescope on Tenerife. Of the active region NOAA 9516 the full Stokes vector of polarised light was observed in the absorption line at 630.249 nm in single scans. A ninety minute time series of circular polarised light of the active region NOAA 9036 was observed at 617.3 nm wavelength. From the reduced data results for intensity, line-of-sight velocity, magnetic field strength as well as several other plasma parameters are inferred. Different approaches to solar atmosphere model inversion are applied and compared. The significant influence of errors is discussed in detail. The frequency behaviour of the results and spatial and temporal dependencies are further analysed by Fourier and wavelet transformation. As a result the existence of a high frequency band of velocity oscillations with a central frequency of about 75-seconds (13 mHz) can be confirmed. In greater heights of about 500 km the majority of the corresponding shock waves are derived from darker parts of the granules in contrast to the dominant five-minute-oscillations. 75-second-oscillations can also be observed in the active region, especially in the light bridge. In the identified bands of oscillatory velocity power, distinct structures become visible in a penumbral dark structure as well as in the light bridge that move into the quiet sun with a horizontal speed of 5-8 km/s. They show an increase in power, mostly 5-minute-band, and may be related to the Evershed cloud phenomenon. Under the constraint of a very low signal-to-noise ratio and high error influence, magnetic field variations of a 6-minute period are also observed in an umbral-penumbral transition area close to a light bridge. To derive these results, existing visualisation methods for frequency analysis where improved or newly developed, especially so for wavelet transform results.

Invert syrup is a liquid sweetener, which is produced by sucrose hydrolysis to form fructose and glucose. Important qualitative parameter of invert syrup is the sucrose inversion – weight percentage of invert sugar (sum of fructose and glucose) in invert syrup dry mass. This diploma thesis presents a possibility of sucrose inversion determination by polarimetry in combination with refractometry in invert syrups of 70–78 % dry mass produced at 80 °C and pH 2,4. New relationship describing the sucrose inversion as a function of polarization and refractometric dry mass was determined. The results of sucrose inversion determined using this new relationship were compared to results obtained by HPLC/RI, which was used as a reference method. The difference between these 2 determination methods was 0,1 ± 0,5 %. The new relationship was detemined with reference to the fact, that under the processing conditions, more glucose than fructose is formed. The fructose : glucose concentration ratio formed under processing conditions was observed to be equal 0,96 ± 0,02.

This thesis is devoted to the experimental quantitative characterization of the shape and orientation distribution of ice particles in clouds. The characterization is based on measured and modeled elevation dependencies of the polarimetric parameters differential reflectivity and correlation coefficient. The polarimetric data is obtained using a newly developed 35-GHz cloud radar MIRA-35 with hybrid polarimetric configuration and scanning capabilities. The full procedure chain of the technical implementation and the realization of the setup of the hybrid-mode cloud radar for the shape determination are presented. This includes the description of phase adjustments in the transmitting paths, the introduction of the general data processing scheme, correction of the data for the differences of amplifications and electrical path lengths in the transmitting and receiving channels, the rotation of the polarization basis by 45°, the correction of antenna effects on polarimetric measurements, the determination of spectral polarimetric variables, and the formulation of a scheme to increase the signal-to-noise ratio. Modeling of the polarimetric variables is based on existing backscattering models assuming the spheroidal representation of cloud scatterers. The parameters retrieved from the model are polarizability ratio and degree of orientation, which can be assigned to certain particle orientations and shapes. In the thesis the first quantitative estimations of ice particle shape at the top of liquid-topped clouds are presented. Analyzed ice particles were formed in the presence of supercooled water and in the temperature range from -20 °C to -3 °C. The estimation is based on polarizability ratios of ice particles measured by the MIRA-35 with hybrid polarimetric configuration, manufactured by METEK GmbH. For the study, 22 cases observed during the ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques) field campaign were used. Polarizability ratios retrieved for cloud layers with cloud-top temperatures of about -5, -8, -15, and -20 °C were 1.6, 0.9, 0.6, and 0.9, respectively. Such values correspond to prolate, quasi-isotropic, oblate, and quasi-isotropic particles, respectively. Data from a free-fall chamber were used for the comparison. A good agreement of detected shapes with well-known shape{temperature dependencies observed in laboratories was found.

L'objectif de ce memoire concerne l'amelioration du pouvoir de discrimination des contributeurs elementaires d'une cible radar par l'introduction du concept de la polarimetrie dans le domaine de l'imagerie electromagnetique haute resolution. L'apport du concept de la polarimetrie dans l'analyse fine de la signature d'une cible a permis de developper une methode originale permettant d'obtenir une image qui soit optimale dans la discrimination des zones brillantes, en realisant une adaptation des etats de polarisation de l'onde emise a la sensibilite maximale de la cible afin que celle-ci retrodiffuse le maximum d'energie. La reconstruction de la matrice de retrodiffusion spatiale a ete amelioree, grace au developpement d'une methode d'analyse harmonique basee sur l'utilisation des fonctions d'ondes spheroidales discretes, etendues au cas bi-dimensionnel. En parallele a cette etude sont venus se greffer les problemes classiques de la reconnaissance, consistant a determiner les caracteristiques physiques et geometriques de la cible qui sont a l'origine des zones brillantes localisees sur les images radar. A partir de la theorie phenomenologique des cibles radar, enoncee par j. R. Huynen, une methode originale de classification a ete definie, basee sur l'utilisation des modeles de reseaux neuronaux

L'objectif general de ce travail etait d'etudier l'apport de l'analyse polarimetrique de la lumiere diffusee, a 10,6 m, a la comprehension des mecanismes d'interaction du rayonnement electromagnetique avec le milieu, et partant, a la modelisation de cette reflexion diffuse, dans le cas des sols nus consideres comme milieux granulaires. Pour ce faire, un systeme de mesure original bistatique (polarimetre) a ete mis au point, ainsi qu'une methode de calibration et une technique de mesure, demontrant la faisabilite et l'interet de l'analyse polarimetrique des milieux denses granulaires dans l'infrarouge thermique. L'etude des matrices de mueller mesurees pour un large choix d'echantillons via les matrices de coherences qui leurs sont associees montre une valeur propre dominante. Ceci a permis de mettre en evidence une interaction locale de type fresnel pour les sols naturels. Afin de mieux cerner la nature et l'importance des mecanismes d'interaction secondaires, une nouvelle methode de decomposition des matrices de mueller experimentales est proposee. Partant de cette observation, une approche basee sur le transfert radiatif vectoriel fut adoptee pour presenter un modele completement vectoriel. Le modele propose prend en compte de facon simple la depolarisation et la retrodiffusion observees dans le plan principal et autour de l'angle de phase nul. La comparaison du modele avec des mesures absolue ainsi qu'avec le modele de hapke est excellente

Disertační práce pojednává o polarizačních nedokonalostech optických komponentů, které jsou využívány ke kontrole a k transformaci polarizačního stavu světla. Získané teoretické výsledky jsou pak využity ve vybraných aplikacích, jež ke své činnosti využívají právě polarizace světla. Konkrétně se jedná o zařízení měřící vibrace oscilujících objektů, dále o interferenční měření dvojlomu v transparentních materiálech a konečně, o vybraná témata z optické kvantové komunikace.

Im Rahmen der Aktivitäten des ITG Fachausschusses 7.5 „Wellenausbreitung“ im VDE wird eine Fachtagung auf dem Gebiet Wellenausbreitung bei Funk-, Mikrowellensystemen und Navigation vom 4. – 5. Juli 2007 in Chemnitz abgehalten. Die Tagungsphilosophie betont den gemeinsamen Nenner der Wellenausbreitung in diversen Bereichen wie Mikrowellensensorik und Mikrowellensystemen. Bei der Fachtagung sind zusätzlich zu den Beiträgen der Fachausschussmitglieder, die zur Information über die Fachausschussaktivitäten dienen, auch Übersichtsvorträge und Diskussions-Sitzungen vorgesehen. Dem Leitthema zugeordnet, werden die folgenden Themen aus Fernerkundung, Kommunikation und Navigation besonders berücksichtigt: Mikrowellenausbreitung in der Kommunikation und Mikrowellensensorik - Gleichwellennetz - Digitale Übertragung - Mehrwegeausbreitung - Mehrfachnutzung - Innen-Gebäude-Übertragung - Mittelwellenausbreitung - Mobilfunk Nutzung und Anwendung in der Mikrowellensensorik - Radar-Polarimetrie - Bistatische und Multistatische Radarverfahren - Polarimetrische und Multistatische Interferometrie - Multiparameter-Wetterradar-Verfahren - Automobil- und Flugzeugradar - Kalibrierung - Biologische Effekte der EM-Strahlung
The ITG section 7.5 „Wellenausbreitung“ within the VDE (German Association for Electrical, Electronic & Information Technologies) is organising a conference on Wave Propagation in Communication, Microwave Systems and Navigation to be held during 4th and 5th of July 2007 in Chemnitz, Germany. The conference philosophy is to emphasize the commonalty between propagation aspects of microwave remote sensing sensors and microwave systems at large. In addition to the contributions from the members of ITG section 7.5, planned are review presentations and discussion sessions. The following topics of Remote Sensing, Communication and Navigation are eligible for presentation: Microwave Propagation in Communication and Microwave Sensors - Band Shared Broadcasting - Multi-Path Propagation - Digital Broadcasting - MIMO Systems and Reuse - Indoor Propagation - Medium Wave Propagation - Mobile Communication Applications of Microwave Sensors - Radar Polarimetry - Bistatic and Multistatic Radar - Polarimetric and Multistatic Interferometry - Multi-Parameter Weather Radar Systems - Automotive and Airborne Radars - System Calibration - Biological Effects of EM-Radiation

El índice de refracción (RI) es un parámetro físico que proporciona información sobre la propagación de la luz a través de una muestra y está relacionado con algunas propiedades ópticas y eléctricas del medio. El RI es una propiedad intrínseca de los materiales, pero en muchos casos, cambios en la materia producidos por interacciones físicas o químicas, pueden producir una modificación de su valor, como, por ejemplo, debido a variaciones de temperatura, estrés mecánico o cambios en su composición química. Otros materiales pueden presentar diferentes valores de RI dependiendo de la dirección de propagación de la luz, como es el caso de los materiales anisótropos. Existen múltiples aplicaciones en diferentes campos, como biología, farmacología, mineralogía o caracterización de materiales, donde el valor de RI puede proporcionar información de gran utilidad. En esta tesis, hemos desarrollado un método óptico para caracterizar los índices de refracción de muestras dieléctricas isótropas y cristales anisótropos uniáxicos. Una ventaja de nuestro método es que es capaz de medir el RI en materiales en fase sólida o líquida y superficies planas o no-planas, iluminando la muestra en reflexión. Esto nos permitiría caracterizar elementos ópticos ya integrados en sistemas ópticos. La caracterización del índice de refracción in situ es hoy en día un problema por resolver, de gran interés para la industria y la investigación. La principal motivación de este trabajo es caracterizar las lentes integradas en sistemas ópticos, para las que no existe un método estándar. Hemos diseñado e implementado por primera vez, un microscopio conoscópico de Mueller que trabaja en reflexión para medir los RIs de varias muestras, independientemente de su superficie. En particular, medimos la matriz de Mueller de cualquier muestra dieléctrica mediante un polarímetro de Mueller completo y un objetivo de gran apertura numérica (HNAO). Como consecuencia, se obtiene un haz de luz polarizado y altamente focalizado que incide sobre la muestra, siendo el tamaño del punto focal más pequeño que la curvatura de la superficie de la muestra, lo que nos permite medir superficies no planas. Gracias al HNAO, el microscopio conoscópico propuesto mide simultáneamente la matriz de Mueller para un gran número de ángulos de incidencia (aquellos dentro del cono iluminando la muestra), sin ningún movimiento mecánico del sistema y obteniendo una gran redundancia de datos. Con una cámara de alta resolución se pueden registrar los diferentes patrones de intensidad correspondientes a distintas configuraciones polarimétricas, y utilizarlos para calcular la imagen de la matriz de Mueller. Hemos desarrollado el modelo matemático que nos permite determinar la matriz de Mueller teórica de la muestra. Éste se basa en los coeficientes de Fresnel, que describen la relación entre los campos eléctricos reflejado y transmitido con el haz incidente, en una interfaz entre diferentes medios. Estos coeficientes dependen, por un lado, del ángulo de incidencia, la polarización y la frecuencia del haz incidente y, por otro lado, de los índices de refracción de ambos medios. El modelo desarrollado se probó realizando una serie de simulaciones y se validó midiendo las características ópticas de matrices de Mueller simulando materiales reales e incluyendo efectos experimentales (ruido, desalineamiento, etc.). Finalmente, se ha utilizado el instrumento para medir la matriz de Mueller de materiales reales. Los diferentes parámetros ópticos del modelo pueden ser ajustados para que la matriz de Mueller teórica coincida con la experimental. Para tal fin, se ha desarrollado un programa de optimización para hallar el mejor ajuste entre simulación y datos experimentales, mediante la minimización de una función de mérito basada en el error cuadrático medio (MSE). El microscopio conoscópico de Mueller ha mostrado su potencial para caracterizar muestras dieléctricas independientemente de su superficie.
Refractive index (RI) provides information about the propagation of light through a specimen and it is related with some optical and electrical properties of materials. In many cases, certain changes in matter can produce a modification of the refractive index, such as, for example, temperature variations, mechanical stress or changes in the chemical composition of the material. Other materials may present different RI values depending on light propagation direction, as is the case of anisotropic materials. Hence, there are multiple applications in different fields such as biology, pharmacology, mineralogy or material characterization, where the RI value can give interesting information. In this thesis, we have developed an optical method to characterize the RIs of dielectric isotropic samples and uniaxial anisotropic crystals. The particularity of our method is to measure, in a reflection configuration, solid or liquid phases and planar or non-planar surfaces, allowing to characterize optical elements already integrated in optical systems. In-situ characterization of the refractive index is nowadays an unsolved problem of interest for industry and research. Particularly, lenses integrated in optical systems are the major motivation of this work, because they may modify their RI value when inserted into devices. Our proposal was to design, implement and use, for the first time, a conoscopic Mueller microscope working in reflection to measure the RIs of several samples with arbitrary surfaces. The working principle of our microscope is based on measuring the angle-resolved Mueller matrix of any dielectric specimen by using a complete Mueller matrix polarimeter and a high numerical aperture objective (HNAO). Under this scenario, a polarized incident light beam is highly focused over the studied sample, being the spot size smaller than the curvature of the sample surface, this allowing us to measure non-planar surfaces. The reflected cone of light passes through the same HNAO, being collimated and then, it is polarimetrically analyzed. Note that the incident and reflected light cones are formed by light rays with different angles of incidence and polarizations. As a consequence, the proposed conoscopic microscope is able to measure the angle-resolved Mueller matrix in reflection at numerous incident angles simultaneously, obtaining data redundancy without any mechanical motion of the set-up. A camera with high-resolution records the different intensity patterns that ultimately are used to calculate the Mueller matrix image. Data redundancy is function of the maximum angle of incidence of the HNAO and the number of pixels of the camera. A mathematical model was developed to theoretically determine the Mueller matrix image. It is based on the Fresnel coefficients that describe the ratio of the reflected and transmitted electric fields to that of the incident beam on an interface between different optical media. These coefficients depend, on the one hand, on the angle of incidence, the polarization and the frequency (or wavelength) of the incident beam and, on the other hand, on the RIs of the media. The model was tested by performing a collection of simulations and we analyzed the validity of the method by measuring the characteristics of different artificial samples. The model parameters, such as the refractive indices can be calculated by fitting them with the experimental data measured with the conoscopic Mueller microscope. An iterative optimization routine was developed in order to find the best-fit parameters that minimize a merit function based on the Mean Squared Error (MSE) between both experimental and simulated Mueller matrix images. The conoscopic Mueller microscope was finally tested by measuring well-known polarimetric samples with different surface forms.

CE TRAVAIL AVAIT POUR OBJECTIF DE MONTRER LA POSSIBILITE D'UTILISER DES METHODES OPTIQUES DANS L'INVESTIGATION BIOPHYSIQUE NON INVASIVE DU SYNDROME CUTANE D'IRRADIATION AIGUË, POUR DES DOSES D'IRRADIATION RELATIVEMENT FAIBLES.
LA PREMIERE PARTIE REVIENT SUR LES MOTIVATIONS QUI ONT ABOUTI AU CHOIX DE LA POLARISATION COMME AGENT DE CONTRASTE DANS LE CADRE DE CETTE ETUDE. NOUS AVONS ALORS OPTE POUR LA POLARIMETRIE DE MUELLER, TECHNIQUE ADAPTEE A L'ETUDE D'UN MILIEU DEPOLARISANT TEL QUE LA PEAU.
LA DEUXIEME PARTIE POSE LES BASES THEORIQUES DANS L'INTERPRETATION DES RESULTATS OBTENUS A PARTIR DE LA MESURE DE LA MATRICE DE MUELLER D'UN MILIEU. LA LECTURE DE CETTE DERNIERE N'ETANT PAS IMMEDIATE, UN ALGORITHME DE DECOMPOSITION ET DE CLASSIFICATION DES MATRICES DE MUELLER DEPOLARISANTES ET NON DEPOLARISANTES A ETE DEVELOPPE. CELUI-CI EST VALIDE SUR UNE SERIE D'ECHANTILLONS DE NATURES TRES DIVERSES.
LA TROISIEME PARTIE PRESENTE LE POLARIMETRE ET LES RESULTATS, ANGULAIRES ET SPECTRAUX, OBTENUS SUR DES ECHANTILLONS DE PEAU IRRADIES OU IL N'Y A AUCUN SIGNE CLINIQUE VISIBLE. EN UTILISANT L'ALGORITHME PRECEDENT NOUS AVONS MIS EN EVIDENCE DEUX AGENTS DE CONTRASTE POLARIMETRIQUE QUI SEULS OU COMBINES APPORTENT UNE INFORMATION SUR LE TAUX D'IRRADIATION. CES RESULTATS SONT CONFORTES PAR UNE ETUDE HISTOLOGIQUE MENEE EN PARALLELE PAR L'IRSN. NOUS AVONS AINSI MONTRE QUE LA POLARISATION PEUT ETRE UN AGENT DE CONTRASTE POUR DE FAIBLES DOSES D'IRRADIATION.
LA DERNIERE PARTIE MONTRE L'INTERET D'UTILISER EN COMPLEMENT A LA POLARIMETRIE UNE METHODOLOGIE D'OPTIQUE COHERENTE (SPECKLE, TOMOGRAPHIE PAR COHERENCE OPTIQUE) POUR LOCALISER LES ALTERATIONS CUTANEES.

Dans un contexte ou la comprehension des mecanismes d'interaction d'une onde avec un objet s'avere indispensable pour ameliorer la furtivite d'une cible, la diversite polarimetrique constitue un element supplementaire d'analyse d'une scene electromagnetique. Dans ce memoire, nous nous attachons a evaluer l'apport des outils polarimetriques dans la caracterisation de cibles en chambre anechoique, apres avoir caracterise la sensibilite de ces outils vis a vis des erreurs systematiques et des erreurs statistiques. Apres un rappel des methodes de modelisation et de visualisation des interactions entre une onde et un objet et l'introduction des outils polarimetriques, nous developpons une methode applicable a toute matrice de diffraction pour evaluer la robustesse de ces outils vis a vis des imperfections du processus de calibration. Les resultats obtenus designent la decomposition de cameron comme l'outil le plus robuste. Cette etude s'est concretisee par le developpement d'un logiciel dedie a la calibration et au pilotage d'un systeme de mesure. Nous proposons et validons ensuite un modele statistique de la matrice de diffraction, d'abord dans le domaine frequentiel, puis dans le domaine des images holographiques. Nous mettons en evidence l'instabilite potentielle de certains parametres polarimetriques et identifions les cibles a l'origine de cette instabilite. Apres avoir souligne la difficulte d'utilisation des parametres de huynen, nous presentons un outil de prediction de la sensibilite des parametres de huynen. Nous utilisons enfin les outils polarimetriques pour etudier la retrodiffusion par une cible complexe et la diffraction par une cavite. Nous insistons sur le risque que represente une utilisation systematique de ces outils, qui se revelent etre surtout adaptes a l'identification de phenomenes electromagnetiques specifiques

To date only very few bistatic measurements (airborne or in controlled laboratories) have been reported. Therefore most of the current remote sensing methods are still focused on monostatic (backscatter) measurements. These methods, based on theoretical, empirical or semi-empirical models, enable the estimation of soil roughness and the soil humidity (dielectric constant). For the bistatic case only theoretical methods have been developed and tested with monostatic data. Hence, there still remains a vital need to gain of experience and knowledge about bistatic methods and data. The main purpose of this thesis is to estimate the soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the experimental part, bistatic X-band measurements, which have been recorded in the Bistatic Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute, will be presented. The bistatic measurement sets are composed of soils with different statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity) system. The BMF has been calibrated using the Isolated Antenna Calibration Technique (IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh water. In the second part, bistatic surface scattering analyses of the calibrated data set were discussed. Then, the specular algorithm was used to estimate the soil moisture of two surface roughnesses (rough and smooth) has been reported. A new technique using the coherent term of the Integral Equation Method (IEM) to estimate the soil roughness was presented. Also, the sensitivity of phase and reflectivity with regard to moisture variation in the specular direction was evaluated. Finally, the first results and validations of bistatic radar polarimetry for the specular case of surface scattering have been introduced
Aktuell sind nur sehr wenige Messungen mit bistatischem Radar durchgeführt worden, sei es von Flugzeuggetragenen Systemen oder durch spezielle Aufbauten im Labor. Deshalb basieren die meisten der bekannten Methoden zur Fernerkundung mit Radar auf monostatis-chen Messungen der Rückstreuung des Radarsignals. Diese Methoden, die auf theoretischen, empirischen oder halb-empirischen Modellen basieren, ermöglichen die Schätzung der Oberfächenrauhigkeit und die Bodenfeuchtigkeit (Dielektrizitätskonstante). Im bistatischen Fall wurden bisher nur theoretische Modelle entworfen, die mittels monostatischer Messungen getestet wurden. Aus diesem Grund ist es von großer Bedeutung, Erfahrung und Wissen über die physikalischen Effekte in bistatischen Konfigurationen zu sammeln. Das Hauptziel der vorliegenden Dissertation ist es, anhand vollpolarimetrischer, bistatischer Radarmessungen die Oberfächenrauhigkeit und Bodenfeuchtigkeit zu bestimmen. Im experimentellen Teil der Arbeit werden die Ergebnisse bistatischer Messungen präsentiert, die in der Bistatic Measurement Facility (BMF) des DLR Oberpfaffenhofen aufgenommen wurden. Die Datensätze umfassen Messungen von Böden unterschiedlicher statistischer Rauhigkeit und Feuchtigkeit, die mittels eines Time Domain Reflectivity (TDR) Systems bestimmt werden. Zur Kalibration des BMF wurde die Isolated Antenna Calibration Technique (IACT) verwendet und anhand der Messung der Reflektivität von Wasser überprüft. Im zweiten Teil der vorliegenden Arbeit wird anhand der kalibrierten Daten eine Analyse der Oberflächenstreuung in bistatischen Konfigurationen vorgenommen. Im Anschluss daran wird mittels des Specular Algorithm eine Schätzung der Bodenfeuchte zweier Proben unter- schiedlicher Rauhigkeit (rau und fein) durchgeführt. Ein neues Verfahren zur Schätzung der Oberfächenrauhigkeit, das auf dem kohärenten Term der Integral Equation Method (IEM) basiert, wurde eingeführt. Daneben wird die Empfindlichkeit der Phase sowie der Reflektivität des vorwärtsgestreuten Signals gegenüber Veränderungen der Bodenfeuchtigkeit analysiert. Schließlich werden erste Ergebnisse und Validierungen bistatischer Radarpolarimetrie für den Fall der Vorwärtsstreuung präsentiert

Des de la invenció del microscopi al segle XVII, l’ús de tecnologies d’imatge ha estat fonamental per a l’estudi de teixits biològics. Al llarg dels segles, s’han anat desenvolupant i implementant noves tecnologies d’imatge per tal de millorar la visualització del teixits biològics i facilitar la comprensió de la seva estructura a partir de la mesura d’algunes de les seves propietats físiques. En aquest context, la polarimetria és una interessant tècnica òptica no invasiva que s’ha utilitzat per a la millora d’imatges en diversos camps com l’astronomia, la teledetecció i la caracterització de materials. A més, la polarimetria es pot combinar amb altres tècniques òptiques per millorar, encara més, la visualització de mostres. La polarimetria compren un conjunt de mètodes òptics basats en mesurar la polarització de la llum i com aquesta varia a l’interactuar amb les mostres. En aquesta tesi, s’estudien, s’implementen experimentalment i s’apliquen per primera vegada en l’anàlisi de teixits biològics alguns mètodes polarimètrics recentment proposats en la literatura (així com de nous) per tal de millorar la visualització de teixits animals i vegetals. En l’àmbit de la biomedicina, el potencial d’utilitzar la polarització està demostrat en una gran varietat d’estudis. Aquests estudis solen basar-se en dos grups de tècniques polarimètriques: tècniques anomenades Portes de Polarització (de l’anglès “Polarization Gating”) i tècniques basades en la matriu de Mueller. En aquesta tesi, s’investiga la relació que hi ha entre aquests dos grups de tècniques polarimètriques i proposem un nou mètode polarimètric més general que permet analitzar diferents configuracions de “Polarization Gating” a partir de la mesura experimental d’una sola matriu de Mueller. Respecte els estudis biomèdics basats en la matriu de Mueller, diferents propietats polarimètriques (diatenuació, retard i despolarització) són analitzades en base a observables per tal d’obtenir informació física relacionada amb l’estructura dels teixits biològics i també per incrementar la seva visualització. En aquests estudis, el retard és analitzat en profunditat mitjançant la descomposició de Lu-Chipman i el càlcul del retard lineal, el retard circular, i l’orientació de l’eix ràpid, entre d’altres. En canvi, l’anàlisi de la despolarització es restringeix al càlcul d’observables que quantifiquen la despolarització global de les mostres i no permeten l’estudi d’informació més específica, com poden ser possibles anisotropies en aquest procés de despolarització. Per aquest motiu, en aquesta tesi s’estudien diferents observables que descriuen amb més detall les propietats de despolarització de la mostra per, posteriorment, ser aplicats per millorar la visualització dels teixits animals mesurats. En aquest sentit, uns observables anomenats Índexs de Puresa Polarimètrica (de l’anglès “Indices of Polarimetric Purity”) són aplicats en l’estudi de teixits d’origen animal. Aquests observables són utilitzats per millorar la visualització dels teixits, revelant certes estructures ocultes en els canals de despolarització estàndard, i també per classificar diferents teixits d’origen animal amb una millor eficiència. Finalment, també estudiem l’ús de la polarització per a l’anàlisi de teixits d’origen vegetal. A diferència dels teixits d’origen animal, la polarimetria és molt menys utilitzada en l’anàlisi de plantes, sent els mètodes basats en la matriu de Mueller molt poc usats. Per aquesta raó, en aquesta tesi s’estudia el potencial de la polarimetria de Mueller per a l’anàlisi de teixits d’origen vegetal i es comparen els resultats amb els obtinguts amb algunes tècniques polarimètriques i no polarimètriques comunament utilitzades. Com a resultat, la polarimetria de Mueller és un mètode polarimètric òptim per a l’obtenció d’imatges de teixits d’origen vegetal que, a més a més, es pot utilitzar com una eina complementària a les altres tècniques òptiques no polarimètriques.
Desde la invención del microscopio en el siglo XVII, el uso de tecnologías de imagen ha sido fundamental para el estudio de tejidos biológicos. A lo largo de los siglos, se han desarrollado e implementado nuevas tecnologías de imágenes para mejorar la visualización de los tejidos biológicos y facilitar la comprensión de su estructura a partir de la medición de algunas de sus propiedades físicas. En este contexto, la polarimetría es una interesante técnica óptica no invasiva que se ha utilizado para la mejora de imágenes en diversos campos como la astronomía, la teledetección y la caracterización de materiales. Además, la polarimetría se puede combinar con otras técnicas ópticas para mejorar aún más la visualización de muestras. La polarimetría comprende un grupo de métodos ópticos que se basan en medir la polarización de la luz y cómo esta varía al interactuar con las muestras. En esta tesis, se estudian, se implementan experimentalmente y se aplican por primera vez en el análisis de tejidos biológicos algunos métodos polarimétricos propuestos recientemente en la literatura (así como nuevos) para mejorar la visualización de tejidos animales y vegetales. En el campo de la biomedicina, el potencial de la polarimetría se demuestra en una amplia variedad de estudios. Estos estudios se basan generalmente en dos grupos de técnicas polarimétricas: técnicas denominadas Puertas de Polarización (del inglés “Polarización Gating”) y técnicas basadas en matrices de Mueller. En esta tesis, investigamos la relación entre estos dos grupos de técnicas polarimétricas y proponemos un nuevo método polarimétrico más general que permite el análisis de diferentes configuraciones de “Polarization Gating” a partir de la medida experimental de una única matriz de Mueller. Respecto a los estudios biomédicos basados en la matriz de Mueller, diferentes propiedades polarimétricas (diatenuación, retardo y despolarización) son analizadas a partir de un grupo de observables para obtener información física relacionada con la estructura de los tejidos biológicos y también para mejorar su visualización. En estos estudios, el retardo es analizado en profundidad mediante la descomposición de Lu-Chipman y el cálculo del retardo lineal, el retardo circular y la orientación del eje rápido, entre otros. Por el contrario, el análisis de la despolarización se restringe al cálculo de observables que cuantifican la despolarización global de las muestras y no permiten el estudio de información más específica, como pueden ser posibles anisotropías en ese proceso de despolarización. Por ello, en esta tesis se estudian diferentes observables que describen con más detalle las propiedades de despolarización de la muestra para, posteriormente, ser aplicados para mejorar la visualización de los tejidos animales medidos. En ese sentido, los parámetros denominados Índices de Pureza Polarimétrica (del inglés “Indices of Polarimetric Purity”) se aplican para inspeccionar los tejidos de origen animal. Estos observables de despolarización se utilizan para mejorar la visualización de tejidos, revelando ciertas estructuras ocultas en canales de despolarización estándar, y también para clasificar con mayor eficiencia diferentes tejidos de origen animal. Finalmente, también estudiamos el uso de la polarimetría para el análisis de tejidos de origen vegetal. A diferencia de los tejidos de origen animal, la polarimetría se utiliza mucho menos en el ámbito del análisis de plantas, siendo las técnicas basadas en Mueller muy poco utilizadas. Por este motivo, esta tesis estudia el potencial de la polarimetría de Mueller para el análisis de tejidos de origen vegetal y compara los resultados obtenidos con los obtenidos con algunas técnicas polarimétricas y no polarimétricas de uso común. Como resultado, la polarimetría de Mueller es un método polarimétrico óptimo para la obtención de imágenes no invasivas de tejidos de origen vegetal que, además, puede utilizarse como herramienta complementaria a otras técnicas ópticas no polarimétricas.
Since the invention of the microscope in the 17th century, the use of imaging technologies has been fundamental in the study of biological tissues. Over the centuries, new imaging technologies have been developed and implemented to enhance the visualization of tissues and ease the understanding of their structure from the measurement of some of their physical properties. In that context, polarimetry is an interesting non-contact and non-invasive optical technique that has been used for image enhancement in a wide range of fields such as astronomy, remote sensing, and characterization of materials. Moreover, polarimetry can be combined with other optical techniques to further improve the visualization of samples. Polarimetry comprises a group of optical methods that are based on measuring the polarization of light and how it varies when interacting with samples. In this thesis, some polarimetric methods recently proposed in the literature (as well as new ones) are studied, experimentally implemented, and applied for the first time in the analysis of biological tissues to improve the visualization of animal and plant tissues. In the field of biomedicine, the potential of polarimetry is demonstrated in a wide variety of studies. These studies are usually based on two groups of polarimetric techniques: Polarization Gating techniques and Mueller matrix-based techniques. In this thesis, we investigate the relationship between these two groups of polarimetric techniques and we propose a new generalized polarimetric method that allows the analysis of different Polarization Gating configurations from a single Mueller matrix measurement. Concerning to the biomedical studies based on the Mueller matrix, different polarimetric properties (diattenuation, retardance, and depolarization) are analyzed from a group of observables to obtaining physical information related to the structure of biological tissues and also to enhance their visualization. In these studies, retardance is completely studied through the Lu-Chipman decomposition and the calculation of the linear retardance, the circular retardance, and the orientation of the fast axis, among others. By contrast, the analysis of depolarization content is restricted to the calculation of observables that quantify the overall depolarization of samples and do not allow the study of more specific information, as can be possible anisotropies in that depolarization process. For that reason, in this thesis, different observables that further describe the depolarization properties of the sample are studied to, afterwards, be applied for visualization enhancement of the measured animal tissues. In that sense, the parameters called Indices of Polarimetric Purity are applied to inspect animal tissues. These depolarizing observables are used to improve tissue visualization, revealing certain structures hidden in standard depolarization channels, and also to classify, with improved efficiency, different animal tissues. Finally, we also study the use of polarimetry for the analysis of plant tissues. Unlike animal tissues, polarimetry is much less used in the plant analysis framework, being Mueller-based techniques scarcely used. For this reason, this thesis studies the potential of Mueller polarimetry for plant tissue analysis and compares the obtained results with those obtained with some commonly used polarimetric and non-polarimetric techniques. As a result, Mueller polarimetry is an optimal polarimetric method for obtaining non-invasive images of plant tissues that, in addition, can be used as a complementary tool to other non-polarimetric optical techniques.
Universitat Autònoma de Barcelona. Programa de Doctorat en Física

To date only very few bistatic measurements (airborne or in controlled laboratories) have been reported. Therefore most of the current remote sensing methods are still focused on monostatic (backscatter) measurements. These methods, based on theoretical, empirical or semi-empirical models, enable the estimation of soil roughness and the soil humidity (dielectric constant). For the bistatic case only theoretical methods have been developed and tested with monostatic data. Hence, there still remains a vital need to gain of experience and knowledge about bistatic methods and data. The main purpose of this thesis is to estimate the soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the experimental part, bistatic X-band measurements, which have been recorded in the Bistatic Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute, will be presented. The bistatic measurement sets are composed of soils with different statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity) system. The BMF has been calibrated using the Isolated Antenna Calibration Technique (IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh water. In the second part, bistatic surface scattering analyses of the calibrated data set were discussed. Then, the specular algorithm was used to estimate the soil moisture of two surface roughnesses (rough and smooth) has been reported. A new technique using the coherent term of the Integral Equation Method (IEM) to estimate the soil roughness was presented. Also, the sensitivity of phase and reflectivity with regard to moisture variation in the specular direction was evaluated. Finally, the first results and validations of bistatic radar polarimetry for the specular case of surface scattering have been introduced.
Aktuell sind nur sehr wenige Messungen mit bistatischem Radar durchgeführt worden, sei es von Flugzeuggetragenen Systemen oder durch spezielle Aufbauten im Labor. Deshalb basieren die meisten der bekannten Methoden zur Fernerkundung mit Radar auf monostatis-chen Messungen der Rückstreuung des Radarsignals. Diese Methoden, die auf theoretischen, empirischen oder halb-empirischen Modellen basieren, ermöglichen die Schätzung der Oberfächenrauhigkeit und die Bodenfeuchtigkeit (Dielektrizitätskonstante). Im bistatischen Fall wurden bisher nur theoretische Modelle entworfen, die mittels monostatischer Messungen getestet wurden. Aus diesem Grund ist es von großer Bedeutung, Erfahrung und Wissen über die physikalischen Effekte in bistatischen Konfigurationen zu sammeln. Das Hauptziel der vorliegenden Dissertation ist es, anhand vollpolarimetrischer, bistatischer Radarmessungen die Oberfächenrauhigkeit und Bodenfeuchtigkeit zu bestimmen. Im experimentellen Teil der Arbeit werden die Ergebnisse bistatischer Messungen präsentiert, die in der Bistatic Measurement Facility (BMF) des DLR Oberpfaffenhofen aufgenommen wurden. Die Datensätze umfassen Messungen von Böden unterschiedlicher statistischer Rauhigkeit und Feuchtigkeit, die mittels eines Time Domain Reflectivity (TDR) Systems bestimmt werden. Zur Kalibration des BMF wurde die Isolated Antenna Calibration Technique (IACT) verwendet und anhand der Messung der Reflektivität von Wasser überprüft. Im zweiten Teil der vorliegenden Arbeit wird anhand der kalibrierten Daten eine Analyse der Oberflächenstreuung in bistatischen Konfigurationen vorgenommen. Im Anschluss daran wird mittels des Specular Algorithm eine Schätzung der Bodenfeuchte zweier Proben unter- schiedlicher Rauhigkeit (rau und fein) durchgeführt. Ein neues Verfahren zur Schätzung der Oberfächenrauhigkeit, das auf dem kohärenten Term der Integral Equation Method (IEM) basiert, wurde eingeführt. Daneben wird die Empfindlichkeit der Phase sowie der Reflektivität des vorwärtsgestreuten Signals gegenüber Veränderungen der Bodenfeuchtigkeit analysiert. Schließlich werden erste Ergebnisse und Validierungen bistatischer Radarpolarimetrie für den Fall der Vorwärtsstreuung präsentiert.

Ever since automobiles became affordable for the average American, with the introduction of the Ford Model T in 1908, making driving safer has been a priority. While driver intoxication and distraction are the leading causes of automotive fatalities, poor road conditions increase the frequency and deadliness of these incidents. Monitoring road conditions for thousands of miles of road is a huge undertaking, one too large for human surveillance. Automated systems capable of detecting and reacting to dangerous road conditions would be life-saving. These systems could be mounted to the sides of road and notify an operator of conditions in real-time. Drivers could be warned, action taken, and many lives saved. This thesis investigated the science behind polarimetric road ice detection systems. Laboratory Mueller matrix measurements of a simulated road under differing surface conditions were collected searching for a discriminatory polarization property. These Mueller matrices were decomposed into depolarization, diattenuation, and retardance. Individual sample surface polarization properties were then calculated from these three unique matrices and compared. Simulated road samples were measured under many wavelengths and angles, which gave us a larger data library from which to observe trends. Specular and off-specular reflection responses of each sample were also collected. Four polarization properties stood out for having high separation between dry and iced measurements: Depolarization Index, Linear Diattenuation, Linear Polarizance, and Linear Retardance. Through our investigation polarimetric ice detection is possible. Continued research of the polarization properties of road ice can result in the development of a road ice detection system. Proposed deployment methods of such a system have been outlined following the analysis of the data collected in this experiment. Not only is polarimetric ice detection an exciting and novel use of polarization, it has the potential to improve road safety through real-time ice response measures.

A linha de instabilidade (LI) pré-frontal que atingiu a Região Metropolitana de São Paulo em 26 de abril de 2007 foi monitorada e analisada por meio de medições de superfície, altitude, radar e satélite. As análises indicam que havia ambiente sinótico favorável para a formação e manutenção da LI. Na região de formação da LI havia ar relativamente quente e úmido em baixos níveis e ar relativamente frio e seco em níveis médios com convergência de massa em baixos níveis e divergência em altos níveis, além de gradiente de temperatura produzido pela aproximação do sistema frontal. A LI foi monitorada pelo radar meteorológico MXPOL e permitiu a avaliação dinâmica e microfísica do sistema. Esta última realizada por meio da classificação de hidrometeororos com as variáveis polarimétricas medidas com o MXPOL. Preliminarmente, os dados de refletividade diferencial (ZDR) e refletividade efetiva (Z) foram consistidos por meio do método da autoconsistência (Vivekanadan et al., 2003), entre essas duas variáveis e a fase diferencial específica (KDP). Removido os viéses de ZDR (-0,36 dB) e da refletividade efetiva (-0,46 dBZ), a classificação de hidrometeoros, em dezessete categorias (gotículas a granizo, insetos, ecos de terreno e de segunda viagem), foi realizada pelo método de lógica fuzzy (Vivekanadan et al., 2003). A classificação de hidrometeoros foi realizada em planos de elevação constante (PPI). Os tipos e estratificação de hidrometeoros são compatíveis com estudos anteriores. Por exemplo, a banda brilhante foi classificada com uma região de mistura de gelo e gotas líquidas com predominância de gotas abaixo e cristais de gelo acima desta. A dinâmica interna da LI foi avaliada por meio da velocidade radial e evidenciou um jato de baixos níveis, convergência ciclônica na dianteira do sistema, e divergência em altos níveis, entre outras características. O rápido deslocamento da LI resultou em precipitação de 7 mm e rajadas de vento de 18 m s-1. Assim, o impacto mais significativo desse sistema na RMSP foi produzido pelo vento.
A prefrontal squal line (LI) that reached tne metropolitan area of São Paulo on April 26 2007 was monitored and analyzed by means of of surface and upper air measurements, weather radar and satellite data. Analyses indicate a favorable synoptic environment to form and sustain the LI. In its genesis region there was relatively warm and moiture air near the surface and relatively cold and dry air aloft with mass convergence below and divergence aloft, as well as temperature gradient along its path induced by the associated cold front. This LI was measured with the MXPOL weather radar and allowed a mesoscale dynamic analysis as well as a microphysics of this weather system. The later was performed by means of a hydrometeor classification with the polarimetric data sets of MXPOL. Initially, the differential reflectivity (ZDR) and the efective reflectivity (Z) were corrected by the selfconsistency method (Vivekanandan et al., 2003) together with the specific diferrential phase (KDP). Ounce removed the ZDR (-0,36 dB) and Z (-0,46 dBZ) biases, the hydrometeoro classification (small drops to hail, insects, ground clutter and second trip echoes) was carrie out by the fuzzy logic method (Vivekanadan et al., 2003). The hydrometeor classification was made at constant elevation angles (PPI) across the LI. The hydrometeoro types are compatible to similar studies. For instance, the bright band was classified as a region mixed phase with drops below and ice crystals aboce it. The LI internal dynamics was analyzed with the help of the radial velocity and indicated a low level jet, cyclonic convergence at the leading edge and divergence aloft at the convective band, among other features. This fast moving LI produced 7 mm of rainfall and wind gust of 18 m s-1. Its most significant impact over RMSP was caused by the wind intensity.

Alors que toutes les experiences de violation de la parite (pv) dans les transitions atomiques tres interdites utilisent jusqu'ici la detection par fluorescence, notre experience est de type pompe-sonde avec detection du signal pv directement sur un faisceau sonde transmis. Un faisceau laser impulsionnel de polarisation lineaire ,#1 excite les atomes de cesium sur la transition 6s-7s dans un champ electrique colineaire e k#e#x. Le faisceau sonde (k#p#r k#e#x) de polarisation lineaire ,#2 accorde sur la transition 7s-6p#3#/#2 est amplifie. La petite (10#-#6) asymetrie dans le gain qui depend du sens du triedre (e, ,#1, ,#2) est la manifestation de l'effet pv. On la mesure par une apparente rotation de la polarisation sonde, impaire en e, dans un polarimetre utilise en mode equilibre. La mise en oeuvre de nouveaux criteres de selection nous permet de discriminer le vrai signal pv de fausses rotations dues a des interferences electromagnetiques, aux effets geometriques, aux imperfections des polarisations pompe et sonde, ou a la presence de champs electriques ou magnetiques transverses. Ces criteres de selection exploitent la symetrie du signal pv - dichroisme lineaire - et la symetrie de revolution de l'experience. Ceci permet non seulement de rejeter de faux signaux mais aussi d'identifier les mecanismes en jeu, la nature des defauts et de determiner leur grandeur. Le rapport signal-sur-bruit actuel permet d'entreprendre des mesures pv a la precision statistique de 10%. Une mesure a 1% necessite des ameliorations. Nous avons demontre deux voies possibles. La premiere exploite l'amplification de l'asymetrie a fort gain, l'un des atouts majeurs de notre methode de detection basee sur l'emission stimulee. La seconde combine l'augmentation de l'intensite sonde incidente et l'usage d'une lame dichroique amplifiant de petites rotations de polarisation.

Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is improved by 300% over a conventional dual rotating retarder Mueller matrix polarimeter. Reconstruction results from the physical instrument are presented, and issues with the implemented system design are discussed.

Estrelas Be são reconhecidas pela sua rápida rotação e pulsação não radial. São as únicas estrelas da Sequência Principal que apresentam discos circunstelares, os quais são formados por meio de processos ainda não completamente compreendidos. A modelagem das forças que atuam neste sistema conduz a previsões teóricas sobre a estrutura do disco que podem ser comparadas com dados observacionais. Podemos estudar as propriedades físicas dos discos de estrelas Be pelo efeito que a luz estelar sofre ao passar por eles, por exemplo, modelando a transferência radiativa. Neste ponto, a polarização surge como uma ferramenta muito útil para a investigação destes discos, permitindo a determinação de quantidades físicas importantes do sistema, como a densidade numérica de partículas e o ângulo de inclinação. Uma variabilidade intrigante observada em estrelas Be é a transição aperiódica entre uma fase B normal (sem disco) e uma fase Be (com disco). Estudos de monitoramento recentes encontraram, a partir da análise da polarização intrínseca decorrente da transição entre estas fases, uma relação significante entre a mudança da polarização através do salto de Balmer versus a polarização na banda V, fazendo surgir uma estrutura em loop como função do tempo, no assim denominado Diagrama Cor-Polarização. Neste trabalho, apresentamos uma análise do Diagrama Cor-Polarização por meio de modelos diversos. Fazemos uso do Disco de Decréscimo Viscoso que é o paradigma atual para explicar a formação e evolução dos discos de estrelas Be. Com isso, visamos determinar como a polarimetria pode contribuir para a compreensão dos mecanismos fundamentais envolvidos no processo de formação e dissipação do disco.
Be stars are recognized by their rapid rotation and non-radial pulsation. They are the only stars in the Main Sequence that have circumstellar disks that are formed by processes not yet fully understood. The modeling of the forces acting on this system leads to theoretical predictions about the structure of the disk that can be compared to observational data. We can study physical the properties of Be disks by modeling how stellar light is reprocessed by them. This requires solving the detailed radiative transfer problem involved. In this point, the study of polarization arise as a useful tool to investigate these disks, allowing for the determination of important physical quantities of the system, such as the particle number density and inclination angle. An intriguing variability observed in Be stars is the aperiodic transition between a B normal phase (without disk) to a Be phase (with disk). Recent monitoring studies found, from the analysis of the intrinsic polarization arising of the transition between these phases, a significant relation between the polarization change through the Balmer jump versus the V-Band polarization, giving rise to a loop structure as a function of time, in the so-called Color-Polarization Diagram. This work presents an analysis of the Color-Polarization Diagram by several models. We make use of the Viscous Decretion Disk Model, which assumes the existence of some injection mechanism of material at keplerian velocities in the disk base, where the turbulent viscosity acts carrying angular momentum from de inner parts to the outer regions. With this, we aimed to extend our knowledge about the fundamental mechanisms involved in the formation and dissipation processes of the disk.

Orientador: Celio Pasquini
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Dois novos instrumentos analíticos, sem o uso de partes móveis, para obtenção de medidas polarimétricas nas regiões do visível (VIS) e infravermelho próximo (NIR) são descritos. Esses equipamentos consistem de um Polarímetro VIS/NIR com fonte de radiação tipo laser de diodo (532 nm, 650 nm e 1064 nm) e um Espectropolarímentro VIS dedicado à obtenção de curva de Dispersão Óptica Rotatória (ORD) e de espectro de absorção, simultaneamente. O método de determinação da rotação óptica empregado nos instrumentos utiliza a equação a = (45 - b)°, onde b é determinado pela função arco tangente da razão dos campos elétricos dos dois feixes produzidos pelo analisador, o qual é constituído por um cristal birrefringente. No desenvolvimento do polarímetro foram avaliados dois analisadores, Glan Laser e Cristal de Wollaston. O instrumento apresentou precisão de 0,003°, e o uso do Cristal de Wollaston permitiu torná-lo mais robusto e compacto, possibilitando que o equipamento possa, eventualmente, ser empregado em controle de qualidade de processos industriais. O espectropolarímetro utiliza um Filtro Óptico Acústico Sintonizável (AOTF), que opera na região do visível (450 nm a 800 nm), como monocromador e analisador simultaneamente, e com características inéditas para esse tipo de equipamento. A melhor precisão, de 0,009°, foi verificada para a media de 20 varreduras. Quando o instrumento é empregado para medida de rotação óptica na presença de uma espécie absorvente, a curva de ORD é imune a absorbância de até 0,3. Estes equipamentos contribuem para o avanço da área da polarimetria, uma vez que apresentam configurações inovadoras que as diferenciam dos equipamentos comercialmente disponíveis, pois nestes, os analisadores são girados mecanicamente para a determinação do ângulo de rotação do plano da radiação polarizada
Abstract: Two new analytical instruments, which preclude of any moving parts, are described to obtain polarimetric measurements in the visible (VIS) and near-infrared (NIR) spectral regions. These instruments consist of a VIS/NIR polarimeter with diode lasers as radiation source (532, 650 and 1064 nm) and a VIS spectropolarimeter aimed at simultaneously obtaining the optical rotatory dispersion (ORD) curve and absorption spectrum of samples. The method employed to determine the optical rotation in both instruments uses the equation a = (45 - b)°, where b given by arc tangent function ratio between the electrical fields of the beams produced by the polarization analyzer element, made of a birefringent crystal. The polarimeter design was evaluated using two analyzers, a Glan Laser and a Wollaston crystal. The instrument is capable of attaining a repeatability of 0.003°, and, when it uses a Wollaston crystal, to become an instrument more compact and robust, which could be used for in-line measurements of industrial processes. The spectropolarimeter employs an Acousto-Optical Tunable Filter (AOTF) operating as a wavelength selector in visible region (450-800 nm) and polarization analyzer element. This instrument is capable of generating absorption and optical rotation spectra of samples simultaneously, a new characteristic, considering this type of equipment. The repeatability of 0.009° was obtained for the average of 20 scans. When the optical rotation is measured in the presence of absorbent substance the ORD curve is immune to a maximum absorbance of 0.3. The instruments contribute to an important advance in polarimetry, as they show innovative designs, distinct from commercially available instruments, where the analyzers are rotated mechanically, aiming at the determination of the angle of the polarization plane
Doutorado
Quimica Analitica
Doutora em Ciências

Thesis (M.S. in Electronic Warfare System Engineering)--Naval Postgraduate School, March 2007.
Thesis Advisor(s): Alfred W. Cooper. "March 2007." Includes bibliographical references (p. 101-102). Also available in print.

The ITG section 7.5 "Wellenausbreitung" within the VDE (German Association for Electrical, Electronic & Information Technologies) organised a conference on Wave Propagation in Communication, Microwave Systems and Navigation which was held during 25th - 27th of November 2009 in Chemnitz, Germany. The conference philosophy is to emphasize the commonalty between propagation aspects of microwave remote sensing sensors and microwave systems at large. The following topics of Remote Sensing, Communication and Navigation are eligible for presentation: Microwave Propagation in Communication and Microwave Sensors - Satellite Communications - Multi-Path Propagation - Indoor Propagation - Digital Broadcast Planning - MIMO Systems and Reuse - Ionospheric Propagation - Urban Communication - Microwave Measurements in Propagation Applications of Microwave Sensors - Radar Polarimetry - Bistatic and Multistatic Radar - Polarimetric and Multistatic Interferometry - Multi-Parameter Weather Radar Systems - Automotive and Airborne Radars - System Calibration - Biological Effects of EM-Radiation - Wave Modulation Remote Sensing Radars Antenna Design and Measurements
Im Rahmen der Aktivitäten des ITG-Fachausschusses 7.5 "Wellenausbreitung" im VDE wurde eine Fachtagung auf dem Gebiet Wellenausbreitung bei Funk-, Mikrowellensystemen und Navigation vom 25. - 27. November 2009 in Chemnitz abgehalten. Die Tagungsphilosophie betont den gemeinsamen Nenner der Wellenausbreitung in diversen Bereichen wie Mikrowellensensorik und Mikrowellensystemen. Dem Leitthema zugeordnet, werden die folgenden Themen aus Fernerkundung, Kommunikation und Navigation besonders berücksichtigt. Mikrowellenausbreitung in der Kommunikation und Mikrowellensensorik - Satellitenkommunikation - Mehrwegeausbreitung - Innen-Gebäude-Übertragung - Frequenzplanung für den digitalen Rundfunk - MIMO Systeme - Wellenausbreitung in der Ionosphäre - urbane Kommunikation - Mikrowellenmessungen der Wellenausbreitung Nutzung und Anwendung in der Mikrowellensensorik - Radar-Polarimetrie - Bistatische und Multistatische Radarverfahren - Polarimetrische und Multistatische Interferometrie - Multiparameter-Wetterradar-Verfahren - Automobil- und Flugzeugradar - Systemkalibrierung - Biologische Effekte der EM-Strahlung - Antennenentwicklung und -messungen für wellenmodulierte Fernerkundungsradare

This thesis investigated the science behind polarimetric road ice detection systems. Laboratory Mueller matrix measurements of a simulated road under differing surface conditions were collected searching for a discriminatory polarization property. These Mueller matrices were decomposed into depolarization, diattenuation, and retardance. Individual sample surface polarization properties were then calculated from these three unique matrices and compared. Specular and off-specular reflection responses of each sample were collected. Four polarization properties stood out for having high separation between dry and iced measurements: Depolarization Index, Linear Diattenuation, Linear Polarizance, and Linear Retardance.

Through our investigation polarimetric ice detection is possible. Continued research of the polarization properties of road ice can result in the development of a road ice detection system. Proposed deployment methods of such a system have been outlined following the analysis of the data collected in this experiment.

La polarimetria proporciona informació crucial en nombroses aplicacions en diferents camps, com en la medicina, la biologia, la teledetecció, la caracterització de materials, l’astronomia, etc. Els polarímetres són els instruments bàsics per a la metrologia de polarització. Nombroses arquitectures de polarímetres han estat analitzades en la literatura, cada una d’elles presenta les seves desavantatges i avantatges. En general, els paràmetres del muntatge del polarímetre són optimitzats per tal de reduir l’amplificació del soroll present en les mesures radiomètriques fins a la mesura final de polarització. D'altra banda, els errors experimentals, com una desalineació o un calibratge erroni, ocasionen una reducció de la precisió del polarímetre en la mesura del contingut polarimètric. Recentment, els dispositius de cristall líquid s'han introduït en les arquitectures de polarímetres, aprofitant les seves atractives característiques de canviar les seves propietats òptiques de manera dinàmica i ràpida. Degut a que les arquitectures basades en cristalls líquids no tenen parts mòbils, s'eviten errors experimentals relacionats amb moviments mecànics, i aquells errors deguts a desalineaments poden ser significativament reduïts després d'un calibratge del sistema complet. Aquesta tesi s'emmarca en el camp de la polarimetria, centrant-se en el disseny òptic, optimització, anàlisi i comparativa de polarímetres basats en materials que presenten anisotropia d’índex de refracció. En concret, es revisen algunes arquitectures de polarímetres conegudes basades en cristalls líquids existents en la literatura, s’introdueixen algunes variants als dissenys d’aquests polarímetres per tal de millorar alguns aspectes del seu funcionament, com ara la minimització de soroll, i es presenten nous dissenys de polarímetres basats en cristalls líquids. Concretament, s'utilitzen tres tipus diferents de làmines de cristall líquid: amb estructura paral·lela, amb estructura helicoïdal i ferroelèctriques. A més, es presenta un nou polarímetre estàtic capaç de mesurar qualsevol estat de polarització. Aquesta última arquitectura es basa en el fenomen de la refracció cònica que es produeix quan la llum es propaga al llarg d'un dels eixos òptics d'un cristall biàxic. Per a cada prototip de polarímetre es duu a terme una anàlisi completa del seu disseny, que inclou una optimització de soroll, estudi de robustesa, anàlisi de tolerància, així com també es detalla la implementació del polarímetre, incloent el seu calibratge i mesures experimentals. Es realitza una comparativa entre els diferents prototips implementats, donant una revisió molt valuosa de les principals característiques dels polarímetres basats en cristalls líquids, així com el polarímetre basat en la refracció cònica. A partir d'aquesta comparativa, es selecciona el millor candidat per a la polarimetria d'imatge. Finalment, en aquesta tesi es proposa un nou muntatge experimental que combina un polarímetre d'imatge i un mòdul utilitzat per a aconseguir imatges amb una resolució sub-píxel en un sistema en què la resolució està limitada per la grandària del píxel del detector. Es proporcionen resultats experimentals crucials, validant la millora de la resolució espaial aconseguida en les imatges de polarització.
Polarimetry provides crucial information in many applications in diverse fields, including medicine, biology, remote sensing, material characterization, astronomy, etc. Polarimeters are the basic instruments for polarization metrology. Several polarimeters architectures have been analyzed in the literature, each one presenting its own drawbacks and strengths. In general, the parameters of the polarimeter set-up are optimized in order to reduce the amplification of noise present at the radiometric measurements to the final polarization measurement. Moreover, experimental errors, as misalignment or miscalibration, lead to a polarimeter accuracy reduction to the measure of such polarization content. Recently, liquid crystal (LC) devices have been introduced in polarimeters architectures, taking advantage of their appealing features of changing their optical properties dynamically and at high rates. Because architectures based on LC have no moving parts, experimental errors related to mechanical movements are avoided, and those due to misalignments may be significantly reduced after a calibration of the whole system. This thesis is framed in the field of polarimetry, focusing on the optical design, optimization, analysis and comparative of polarimeters based on materials presenting index anisotropy. In particular, it reviews some existing LC based polarimeter architectures popular in the literature, introduces some variants to those polarimeter layouts in order to improve some aspects in their performance such as noise minimization, and presents new designs of LC based polarimeters. In particular, we use three different types of LC cells: parallel aligned nematic, twisted nematic and ferroelectric. Moreover, it presents a new static polarimeter able to measure any state of polarization. This last architecture is based on the conical refraction (CR) phenomenon occurring when light propagates along one of the optical axes of a biaxial crystal. For each polarimeter prototype we conduct a comprehensive analysis of its design, including a noise optimization, robustness study, tolerance analysis, as well as we detail the implementation of the polarimeter, including its experimental calibration and measurements. A comparative between the different implemented prototypes is conducted, giving a very valuable review of the main features of LC based polarimeters as well as the CR based polarimeter. From this comparative, the best candidate for imaging polarimetry is selected. Finally, in this thesis it is proposed a new experimental configuration which combines an imaging polarimeter and a module used to achieve sub-pixel-resolution imaging in a system where the resolution is limited by detector pixel size. Crucial experimental results are provided, validating the resolution enhancement achieved in polarization images.

The McGill University S-Band radar has been upgraded in 1999 to dual-polarization capability. The transmission and reception of horizontally and vertically polarized electromagnetic waves provide new parameters that are sensitive to the hydrometeor shapes and other characteristics in the radar resolution volume. As a result, the retrieval of microphysical properties of weather events can be improved.
In this work, we studied the reliability of the polarization data obtained by the fast scanning radar. Measurements from different precipitation systems are analyzed to study how this new information can be exploited for operational purposes. The work done shows a great potential for particle typing and microphysical retrievals. However, the possible use of orthogonal polarization for measuring precipitation remains ambiguous.

The generation and control of linearly and circularly polarized light in the far ultraviolet (FUV) and extreme ultraviolet (EUV) spectral regions are required in different frontiers research and technological areas ranging from material science, where the nature of the beam plays a fundamental role in the light-matter interaction, to optical components developments including devices for manipulation of the light polarization state. This has pushed researchers to examine and outline new optical elements as optical polarizers and quarter-wave retarders (QWRs) specifically designed for this spectral range and thought to be used in proper optical arrangements in order to provide valuable information about physical and optical properties of materials and optical coatings. In this thesis, we present an EUV reflectometer facility located in the Institute for Photonics and Nanotechnologies-CNR Padua (Italy) which was implemented for polarimetric measurements within a suitably wide spectral range (90-160 nm) where some important spectral emission lines are, as the hydrogen Lyman alpha 121.6 and Oxygen VI (103.2 nm) lines. The development part focuses on the design and fabrication of an optical linear polarizer based on four reflection gold-coated mirrors to be inserted in the EUV reflectometer optical path. In this way, the facility can be used as an EUV spectroscopic ellipsometric system. The robustness of the methodology and the system were tested to characterize the optical and structural properties of a single layer aluminum mirror as quarter wave retarder (QWR) by deriving its amplitude component tanψ=r_p/r_s and phase difference δ. The second part of the thesis comes from the desire to explore new optical materials employed as a capping layer for optical coatings in the far ultraviolet (FUV) and extreme ultraviolet (EUV) spectral regions. The materials are mostly absorptive in these spectral regions, thus the availability of high-performance optical coatings for the short wavelengths is quite restricted for this reason. In this part, we present a phase retarder optical component based on SnTe/Al bilayer covering the spectral range between 80 nm and 160 nm. The measurements have been performed using an EUV reflectometer facility improved for ellipsometric measurements. The specimen has been fully characterized at hydrogen Lyman–alpha line (121.6 nm) in terms of reflectance and ellipsometric parameters, i.e. the ratio r, ratio of the Fresnel coefficient, and the phase difference δ introduced between the -s and -p reflected components. To our knowledge, such structure based on SnTe haven’t been studied as capping layer for a wide spectral range in the vacuum ultraviolet, although the throughputs are not those expected for this structure. The drop-in performances are attributed to the carbon contamination on the sample surface identified by additional reflectance measurements at 160 nm wavelength. The results also confirm the potentialities and the advantages of such non-invasive optical approach. Lastly, the whole system consisting of the reflectometer and the polarizer could be particularly useful as diagnostic tools in EUV ellipsometry field. The system can be a relatively simple complement to large-scale facilities and can be applied to test optical components by deriving their efficiency, determining the Mueller Matrix terms, and even to the analysis of optical surface and interface properties of thin films. In addition, the QWRs developed in this framework could be used in other experimental applications for generating EUV radiation beams of suitable polarization, for characterizing and controlling the polarization state of EUV radiation beams and to be inserted in an ellipsometric scheme in order to characterize optical devices.
La generazione e il controllo di luce polarizzata linearmente e circolarmente nell’ ultravioletto da vuoto (VUV) e nell’estremo ultravioletto (EUV) è argomento di grande interesse in diversi ambiti tecnologici e di ricerca, che riguardano la fisica solare, la scienza dei materiali e lo sviluppo di componenti ottici, inclusi dispositivi per la manipolazione dello stato di polarizzazione della luce. Questo ha spinto i ricercatori ad esaminare e disegnare ritardatori di fase, polarizzatori e lamine al quarto d’onda, specificamente progettati per questa regione spettrale e pensati per essere usati in diverse configurazioni ellissometriche al fine di fornire preziose informazioni sulle proprietà fisiche e ottiche di materiali e rivestimenti ottici. In questa tesi, presentiamo l’implementazione di un riflettometro EUV, già presente presso l'Istituto di fotonica e Nanotecnologie-CNR di Padova (Italia), recentemente implementato e testato per misure polarimetriche in una banda spettrale ampia, compresa tra i 90 e i 160 nm, di grande interesse per la fisica solare. La prima parte del lavoro descrive lo sviluppo, la progettazione e la fabbricazione di un polarizzatore lineare ottico costituito da quattro specchi in oro opportunamente assemblati. Il dispositivo è stato accoppiato al riflettometro EUV in modo da permettere l’utilizzo dell’intero sistema per analisi ellissometriche nell’EUV. La robustezza della metodologia sperimentale è stata poi validata per caratterizzare le proprietà ottiche e strutturali di uno specchio di alluminio mono-strato proposto come lamina al quarto d’onda broadband. Per questo specchio, sono stati derivati i due parametri ellissometrici caratteristici tanψ=r_p/r_s e δ, la differenza di fase. La seconda parte della tesi tratta, invece, lo sviluppo e la progettazione di lamine al quarto d’onda broadband innovative. Le attività nell'ambito di questo argomento includono la ricerca di nuovi materiali, la simulazione numerica e la caratterizzazione. A tale scopo, sono state studiate le proprietà di una lamina al quarto d’onda basata su SnTe/Al, per la quale il SnTe è stato utilizzato come strato protettivo al fine di migliorare la stabilità e l'efficienza, contro l’ossidazione e la contaminazione proprie dell’alluminio. Il campione è stato caratterizzato attraverso misure di tipo polarimetrico e di riflettanza. Le lamine al quarto d’onda sviluppate in questo contesto potrebbero essere utilizzate in altre applicazioni sperimentali per la generazione, la caratterizzazione e il controllo di luce polarizzata nell’ EUV. L'intero strumento, composto dal riflettometro e dal polarizzatore, è a tutti gli effetti un sistema ellissometrico nell’ EUV. Lo si propone in maniera complementare a large scale facility per testare componenti ottici disegnati per l’EUV, per lo studio di coating e di interfacce di film sottili.