157,736 research outputs found
Bayesian inference approach for Full Poincaré Mueller polarimetry
No full text© 2023 Elsevier Ltd.Full Poincare Mueller Polarimetry is a new technique for characterizing samples by means of their Mueller matrix. The method is based on the use of a full Poincare beam as a generator of polarization states. These beams present different polarization states, covering the entire Poincare sphere surface, at different points in the beam cross section. To obtain the Mueller matrix, Stokes parameters are collected at both the entrance and the output of the sample. They are calculated from irradiance measurements at each pixel of a CCD camera for different configurations of the polarization state analyzer. These measurements can be processed in several ways. In this work, we propose to use Bayesian inference, in particular, Markov chain Monte Carlo methods, to obtain, without any prior knowledge of the sample, its Mueller matrix together with its uncertainties. The new approach is tested with experimental measurements of different samples and compared with the real theoretical Mueller matrices. Excellent agreement is observed between the experimental results and the theoretical ones for all the samples tested.Ministerio de Ciencia e Innovación (España)Agencia Estatal de InvestigaciónEuropean CommissionDepto. de ÓpticaDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasInstituto de Física de Partículas y del Cosmos (IPARCOS)TRUEpu
Mueller–Navelet jets at 13 TeV LHC: dependence on dynamic constraints in the central rapidity region
No full textWe study the production of Mueller–Navelet jets at 13 TeV LHC, within collinear factorization and including the BFKL resummation of energy logarithms in the next-to-leading approximation. We calculate several azimuthal correlations for different values of the rapidity separation Y between the two jets and evaluate the effect of excluding those events where, for a given Y, one of the two jets is produced in the central region
In memoriam Monique Barbier-Mueller
No full textMonique Barbier-Mueller (21 novembre 1929-6 août 2019) © Photo Malick Sidibé - Courtesy A. Magnin Monique Barbier-Mueller s’est éteinte il y a près d’un an. Associée à son époux, Jean Paul Barbier-Mueller, elle avait été à l’origine de la création de notre Fondation consacrée à l’étude de la poésie italienne de la Renaissance. C’était en 1998. D’une personnalité discrète, moins exposée que son époux, par caractère et par choix, elle ne l’accompagnait pas moins avec enthousiasme dans ses init..
Mueller-Navelet jets at LHC: BFKL versus high-energy DGLAP
No full textThe production of forward jets separated by a large rapidity gap at LHC, the so-called Mueller-Navelet jets, is a fundamental testfield for perturbative QCD in the high-energy limit. Several analyses have already provided us with evidence about the compatibility of theoretical predictions, based on collinear factorization and BFKL resummation of energy logarithms in the next-to-leading approximation, with the CMS experimental data at 7 TeV of centerof- mass energy. However, the question if the same data can be described also by fixed-order perturbative approaches has not yet been fully answered. In this paper we provide numerical evidence that the mere use of partially asymmetric cuts in the transverse momenta of the detected jets allows for a clear separation between BFKL-resummed and fixed-order predictions in some observables related with the Mueller- Navelet jet production process
100 kHz Mueller polarimeter for laser scanning polarimetric microscopy
No full textA new setup was recently proposed to perform Mueller matrix polarimetry at 100 kHz using a swept laser source, high order retarders and a single channel photodetector. In this communication, we present the implementation of this setup on a laser scanning microscope to perform high speed scanning Mueller microscopy in transmission. Calibration of the instrument is briefly described and precision and stability over time are evaluated. Finally, Mueller images of a manufactured scene are reported. To our best knowledge, this is the first time that Mueller polarimetry is performed using a laser scanning microscope. We further plan to develop confocal/nonlinear/Mueller microscopy from the same setup in order to produce multimodal contrast images of biological samples. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
ANALISIS NO ESTACIONARIO DE LA VARIABILIDAD DE LA FRECUENCIA CARDIACA SOBRE LAS MANIOBRAS DE MUELLER Y VALSALVA
No full textEste trabajo confronta las maniobras de Mueller y Valsalva, antagónicas por naturaleza, la finalidad es establecer el comportamiento de la maniobra de Mueller con respecto a la maniobra de Valsalva debido a que la respuesta fisiológica resultante de la maniobra de Mueller presenta controversia por no tener un patrón característico. Para valorar el balance autonómico por medio del análisis de la variabilidad de la frecuencia cardiaca (VFC), se midieron las series de tiempo de los intervalos RR de diez registros de ECG para ambas maniobras, cada par fue medido en el mismo sujeto. De los datos obtenidos se calcularon índices espectrales y temporales aplicando una distribución tiempo-frecuencia basada en el algoritmo de Fourier llamada Distribución de BornJordan y un análisis derivado de la Teoría del Caos llamado Gráficas de Poincaré o Mapas de Retorno respectivamente. La Distribución de Born-Jordan fue seleccionada dadas sus bondades para el tratamiento de señales transitorias y no estacionarias. Los resultados indican que durante la maniobra de Mueller tiene lugar un aumento de la frecuencia cardiaca en la primera mitad de la maniobra, después se presenta una bradicardia hacia el final y durante la recuperación, por el contrario la maniobra de Valsalva presentó taquicardia durante toda su duración y una bradicardia sólo observada en la recuperación. Por otro lado, durante la fase IV (después de terminar la maniobra) de Valsalva se observa una participación clara del barorreflejo. En contraste la maniobra de Mueller donde el barorreflejo tuvo lugar durante la maniobra. El componente de frecuencia alta de los intervalos RR para la maniobra de Mueller resultó mayor, durante y después de la maniobra, que los valores correspondientes para Valsalva, esto sugiere una mayor actividad parasimpática para la maniobra de Mueller. El patrón característico obtenido de los mapas de retorno de los intervalos RR mostró una gran dispersión en la maniobra de Mueller y una gran concentración en la maniobra de Valsalva. Esto significa una mayor variabilidad de la frecuencia cardiaca en la maniobra de Mueller. Por otro lado, los mapas de retorno evolutivos muestran una alta actividad parasimpática durante Mueller, y es representada por la longitud mayor del eje transversal en la maniobra. En contraste, el coeficiente de correlación (R) fue mayor en la maniobra de Valsalva. La distribución de Born-Jordan reveló durante la maniobra de Mueller componentes de frecuencia superiores a 0.5 HZ, la cual es asociada con la respiración, situación no presente durante la maniobra
Mueller Matrix Imaging and Spectroscopy
No full textThis thesis presents experimental work on the following topics in Mueller matrix polarimetry; instrument design and implementation, and selected applications of liquid crystal based Mueller matrix polarimeters (MMP) and spectroscopic Mueller matrix ellipsometry (MME). In particular MMPs were designed using ferroelectric liquid crystals (FLC) and liquid crystal variable retarders (LCVR) as polarization changing components. The polarimeters were optimized by using genetic algorithms with the system matrix condition numbers as figures of merit. A calibration routine was adapted to calibrate an overdetermined MMP based on LCVRs. The temporal response of the FLC based MMP was studied in order to investigate its potential as a high speed MMP. The FLC based MMP was implemented as an imaging MMP. Applications studied with the imaging MMP were strain mapping in multi crystalline silicon, directional mapping of collagen fibers, polarizing properties of an anisotropic plasmonic polarizer and nematic textures in colloidal dispersions of synthetic clay. Spectroscopic MME was used to study two types of nanopatterned plasmonic samples. Optical and structural properties of biaxial in plane gold nanowires were found through parametrization of the dielectric tensor of the layer. Strong localized surface plasmon resonances (LSPR) were found in the plane normal to the wires and in the plane along the wires. A small resonance was also found in the out of plane direction. The ellipsometric modelling allowed for determining parameters of the local geometry. Anisotropic Cu nanoparticles embedded in mixed oxide (Cu2O and SiO2) nanopillars were also studied using MME. Cu nanoparticles were localized as discs on the top, as droplets inside and as needles on the side of the nanopillars. MME allowed for detecting the splitting of the modes in wavelength and in p− and s−polarized modes originating from the nanoparticle shapes. Finally, measurement and modeling of GaSb nanopillars using spectroscopic MME allowed for the determination of small tilt angles of only a few degrees
Design of Partial Mueller-Matrix Polarimeters for Application-Specific Sensors
No full textAt a particular frequency, most materials and objects of interest exhibit a polarization signature, or Mueller matrix, of limited dimensionality, with many matrix elements either negligibly small or redundant due to symmetry. Robust design of a polarization sensor for a particular material or object of interest, or for an application with a limited set of materials or objects, will adapt to the signature subspace, as well as the available modulators, in order to avoid unnecessary measurements and hardware and their associated budgets, errors, and artifacts. At the same time, measured polarization features should be expressed in the Stokes–Mueller basis to allow use of known phenomenology for data interpretation and processing as well as instrument calibration and troubleshooting. This approach to partial Mueller-matrix polarimeter (pMMP) design begins by defining a vector space of reduced Mueller matrices and an instrument vector representing the polarization modulators and other components of the sensor. The reduced-Mueller vector space is proven to be identical to R15 and to provide a completely linear description constrained to the Mueller cone. The reduced irradiance, the inner product of the reduced instrument and target vectors, is then applied to construct classifiers and tune modulator parameters, for instance to maximize representation of a specific target in a fixed number of measured channels. This design method eliminates the use of pseudo-inverses and reveals the optimal channel compositions to capture a particular signature feature, or a limited set of features, under given hardware constraints. Examples are given for common optical division-of-amplitude (DoA) 2-channel passive and serial/DoT-DoA 4-channel active polarimeters with rotating crystal modulators for classification of targets with diattenuation and depolarization characteristics
Mueller Matrix Imaging and Spectroscopy
No full textThis thesis presents experimental work on the following topics in Mueller matrix polarimetry; instrument design and implementation, and selected applications of liquid crystal based Mueller matrix polarimeters (MMP) and spectroscopic Mueller matrix ellipsometry (MME).
In particular MMPs were designed using ferroelectric liquid crystals (FLC) and liquid crystal variable retarders (LCVR) as polarization changing components. The polarimeters were optimized by using genetic algorithms with the system matrix condition numbers as figures of merit. A calibration routine was adapted to calibrate an overdetermined MMP based on LCVRs. The temporal response of the FLC based MMP was studied in order to investigate its potential as a high speed MMP.
The FLC based MMP was implemented as an imaging MMP. Applications studied with the imaging MMP were strain mapping in multi crystalline silicon, directional mapping of collagen fibers, polarizing properties of an anisotropic plasmonic polarizer and nematic textures in colloidal dispersions of synthetic clay.
Spectroscopic MME was used to study two types of nanopatterned plasmonic samples. Optical and structural properties of biaxial in plane gold nanowires were found through parametrization of the dielectric tensor of the layer. Strong localized surface plasmon resonances (LSPR) were found in the plane normal to the wires and in the plane along the wires. A small resonance was also found in the out of plane direction. The ellipsometric modelling allowed for determining parameters of the local geometry. Anisotropic Cu nanoparticles embedded in mixed oxide (Cu2O and SiO2) nanopillars were also studied using MME. Cu nanoparticles were localized as discs on the top, as droplets inside and as needles on the side of the nanopillars. MME allowed for detecting the splitting of the modes in wavelength and in p− and s−polarized modes originating from the nanoparticle shapes.
Finally, measurement and modeling of GaSb nanopillars using spectroscopic MME allowed for the determination of small tilt angles of only a few degrees.PhD i fysikkPhD in Physic
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