The Experts below are selected from a list of 25203 Experts worldwide ranked by ideXlab platform
Francois Goudail - One of the best experts on this subject based on the ideXlab platform.
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maximum likelihood method for calibration of mueller Polarimeters in reflection configuration
Applied Optics, 2013Co-Authors: Haofeng Hu, Enric Garciacaurel, Guillaume Anna, Francois GoudailAbstract:We address calibration of Mueller Polarimeters in the presence of noise. We compare an extension of the eigenvalue calibration method (ECM) and a maximum likelihood (ML) method. The performances of these two calibration methods are investigated with numerical simulations and real experiments on a broadband infrared Polarimeter. It is found that the ML method is superior to the extended ECM in terms of calibration precision and can be used at lower signal-to-noise ratio.
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optimal mueller matrix estimation in the presence of poisson shot noise
Optics Express, 2012Co-Authors: Guillaume Anna, Francois GoudailAbstract:We address the optimization of Mueller Polarimeters in the presence of additive Gaussian noise and signal-dependent shot noise, which are two dominant types of noise in most imaging systems. We propose Polarimeter architectures in which the noise variances on each coefficient of the Mueller matrix are equalized and independent of the observed matrices.
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Optimal Mueller matrix estimation in the presence of additive Gaussian or Poisson shot noise
Optics Express, 2012Co-Authors: Guillaume Anna, Francois GoudailAbstract:We address the optimization of Mueller Polarimeters in the presence of additive Gaussian noise and signal-dependent shot noise, which are two dominant types of noise in most imaging systems. We propose Polarimeter architectures in which the noise variances on each coefficient of the Mueller matrix are equalized and independent of the observed matrices.
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noise minimization and equalization for stokes Polarimeters in the presence of signal dependent poisson shot noise
Optics Letters, 2009Co-Authors: Francois GoudailAbstract:We address the optimization of Stokes Polarimeters in the presence of signal-dependent shot noise, which is the dominant type of noise in certain imaging systems. We show that in some precise sense, the Polarimeters optimal for additive noise are also optimal for such noise and propose Polarimeter architectures in which noise variances are equalized and independent of the input polarization state.
Charles F Lacasse - One of the best experts on this subject based on the ideXlab platform.
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Maximum bandwidth snapshot channeled imaging Polarimeter with polarization gratings
Polarization: Measurement Analysis and Remote Sensing XII, 2016Co-Authors: Charles F Lacasse, Michael W. Kudenov, Brian J. Redman, Julia M. CravenAbstract:Compact snapshot imaging Polarimeters have been demonstrated in literature to provide Stokes parameter estimations for spatially varying scenes using polarization gratings. However, the demonstrated system does not employ aggressive modulation frequencies to take full advantage of the bandwidth available to the focal plane array. A snapshot imaging Stokes Polarimeter is described and demonstrated through results. The simulation studies the challenges of using a maximum bandwidth configuration for a snapshot polarization grating based Polarimeter, such as the fringe contrast attenuation that results from higher modulation frequencies. Similar simulation results are generated and compared for a microgrid Polarimeter. Microgrid Polarimeters are instruments where pixelated polarizers are superimposed onto a focal plan array, and this is another type of spatially modulated Polarimeter, and the most common design uses a 2x2 super pixel of polarizers which maximally uses the available bandwidth of the focal plane array.
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spectral density response functions for modulated Polarimeters
Applied Optics, 2015Co-Authors: Charles F Lacasse, Oscar G Rodriguezherrera, Russell A. ChipmanAbstract:Conventional imaging devices are often compared using their optical transfer functions (OTFs) in space and their impulse responses in time. Modulated Polarimeters cannot be directly compared this way, since they are frequency multiplexed. Here we define a spectral density response function that describes how the spectral density matrix of the Stokes parameters for an object transfers through a modulated Polarimeter. This response function facilitates the objective comparison of Polarimeters in a way that is analogous to the OTF for conventional imaging systems. The spectral density response is used to calculate a Wiener filter for a rotating analyzer Polarimeter as an example of filter optimization for modulated polarimetry.
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liquid crystal polymer full stokes division of focal plane Polarimeter
Optics Express, 2012Co-Authors: Graham Myhre, Weiliang Hsu, Alba Peinado, Charles F Lacasse, Neal Ock, Russell A Chipma, Stanley PauAbstract:A division-of-focal-plane Polarimeter based on a dichroic dye and liquid crystal polymer guest-host system is presented. Two Stokes Polarimeters are demonstrated: a linear Stokes and the first ever Full-Stokes division-of-focal-plane Polarimeter. The fabrication, packaging, and characterization of the systems are presented. Finally, optimized Polarimeter designs are discussed for future works.
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role of the null space of the drm in the performance of modulated Polarimeters
Optics Letters, 2012Co-Authors: Charles F Lacasse, Russell A. ChipmanAbstract:Imaging Polarimeters infer the spatial distribution of the polarization state of the optical field as a function of time and/or wavelength. A Polarimeter indirectly determines the polarization state by first modulating the intensity of the light field and then demodulating the measured data to infer the polarization parameters. This Letter considers passive Stokes parameter Polarimeters and their inversion methods. The most widely used method is the data reduction matrix (DRM), which builds up a matrix equation that can be inverted to find the polarization state from a set of intensity measurements. An alternate strategy uses linear system formulations that allow band limited reconstruction through a filtering perspective. Here we compare these two strategies for overdetermined Polarimeters and find that design of the null space of the inversion operator provides degrees of freedom to optimize the trade off between accuracy and signal-to-noise ratio. We further describe adaptive filtering techniques that could optimize the reconstruction for a particular experimental configuration. This Letter considers time-varying Stokes parameters, but the methods apply equally to Polarimeters that are modulated in space or in wavelength.
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band limited data reconstruction in modulated Polarimeters
Optics Express, 2011Co-Authors: Charles F Lacasse, Russell A. ChipmanAbstract:Data processing for sequential in time Polarimeters based on the Data Reduction Matrix technique yield polarization artifacts in the presence of time varying signals. To overcome these artifacts, Polarimeters are designed to operate at higher and higher speeds. In this paper we describe a band limited reconstruction algorithm that allows the measurement and processing of temporally varying Stokes parameters without artifacts. An example Polarimeter consisting of a rotating retarder and polarizer is considered, and conventional processing methods are compared to a band limited reconstruction algorithm for the example Polarimeter. We demonstrate that a significant reduction in error is possible using these methods.
Russell A. Chipman - One of the best experts on this subject based on the ideXlab platform.
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Advances in modeling Polarimeter performance
Polarization Science and Remote Sensing VIII, 2017Co-Authors: Russell A. ChipmanAbstract:Artifacts in Polarimeters are apparent polarization features which are not real but result from the systematic errors in the Polarimeter. The polarization artifacts are different between division of focal plane, spectral, and time modulation Polarimeters. Artifacts result from many sources such as source properties, micropolarizer arrays, coatings issues, vibrations, and stress birefringence. A modeling examples of polarization artifacts due to a micro-polarizer array Polarimeter is presented.
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spectral density response functions for modulated Polarimeters
Applied Optics, 2015Co-Authors: Charles F Lacasse, Oscar G Rodriguezherrera, Russell A. ChipmanAbstract:Conventional imaging devices are often compared using their optical transfer functions (OTFs) in space and their impulse responses in time. Modulated Polarimeters cannot be directly compared this way, since they are frequency multiplexed. Here we define a spectral density response function that describes how the spectral density matrix of the Stokes parameters for an object transfers through a modulated Polarimeter. This response function facilitates the objective comparison of Polarimeters in a way that is analogous to the OTF for conventional imaging systems. The spectral density response is used to calculate a Wiener filter for a rotating analyzer Polarimeter as an example of filter optimization for modulated polarimetry.
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role of the null space of the drm in the performance of modulated Polarimeters
Optics Letters, 2012Co-Authors: Charles F Lacasse, Russell A. ChipmanAbstract:Imaging Polarimeters infer the spatial distribution of the polarization state of the optical field as a function of time and/or wavelength. A Polarimeter indirectly determines the polarization state by first modulating the intensity of the light field and then demodulating the measured data to infer the polarization parameters. This Letter considers passive Stokes parameter Polarimeters and their inversion methods. The most widely used method is the data reduction matrix (DRM), which builds up a matrix equation that can be inverted to find the polarization state from a set of intensity measurements. An alternate strategy uses linear system formulations that allow band limited reconstruction through a filtering perspective. Here we compare these two strategies for overdetermined Polarimeters and find that design of the null space of the inversion operator provides degrees of freedom to optimize the trade off between accuracy and signal-to-noise ratio. We further describe adaptive filtering techniques that could optimize the reconstruction for a particular experimental configuration. This Letter considers time-varying Stokes parameters, but the methods apply equally to Polarimeters that are modulated in space or in wavelength.
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band limited data reconstruction in modulated Polarimeters
Optics Express, 2011Co-Authors: Charles F Lacasse, Russell A. ChipmanAbstract:Data processing for sequential in time Polarimeters based on the Data Reduction Matrix technique yield polarization artifacts in the presence of time varying signals. To overcome these artifacts, Polarimeters are designed to operate at higher and higher speeds. In this paper we describe a band limited reconstruction algorithm that allows the measurement and processing of temporally varying Stokes parameters without artifacts. An example Polarimeter consisting of a rotating retarder and polarizer is considered, and conventional processing methods are compared to a band limited reconstruction algorithm for the example Polarimeter. We demonstrate that a significant reduction in error is possible using these methods.
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optimization of mueller matrix Polarimeters in the presence of error sources
Optics Express, 2008Co-Authors: K Twietmeyer, Russell A. ChipmanAbstract:Methods are presented for optimizing the design of Mueller matrix Polarimeters and and in particular selecting the retardances and orientation angles of polarization components to ensure accurate reconstruction of a sample’s Mueller matrix in the presence of error sources. Metrics related to the condition number and to the singular value decomposition are used to guide the design process for Mueller matrix Polarimeters with the goal of specifying polarization elements, comparing Polarimeter configurations, estimating Polarimeter errors, and compensating for known error sources. The use of these metrics is illustrated with analyses of two example Polarimeters: a dual rotating retarder Polarimeter, and a dual variable retarder Polarimeter.
Henric Krawczynski - One of the best experts on this subject based on the ideXlab platform.
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analyzing the data from x ray Polarimeters with stokes parameters
Astroparticle Physics, 2015Co-Authors: F Kislat, Brian Clark, M Beilicke, Henric KrawczynskiAbstract:Abstract X-ray polarimetry promises to deliver unique information about the geometry of the inner accretion flow of astrophysical black holes and the nature of matter and electromagnetism in and around neutron stars. In this paper, we discuss the possibility to use Stokes parameters – a commonly used tool in radio, infrared, and optical polarimetry – to analyze the data from X-ray Polarimeters such as scattering Polarimeters and photoelectric effect Polarimeters, which measure the linear polarization of the detected X-rays. Based on the azimuthal scattering angle (in the case of a scattering Polarimeter) or the azimuthal component of the angle of the electron ejection (in the case of a photoelectric effect Polarimeter), the Stokes parameters can be calculated for each event recorded in the detector. Owing to the additive nature of Stokes parameters, the analysis reduces to adding the Stokes parameters of the individual events and subtracting the Stokes parameters characterizing the background (if present). The main strength of this kind of analysis is that the errors on the Stokes parameters can be computed easily and are well behaved – in stark contrast of the errors on the polarization fraction and polarization direction. We demonstrate the power of the Stokes analysis by deriving several useful formulae, e.g. the expected error on the polarization fraction and polarization direction for a detection of NS signal and NBG background events, the optimal observation times of the signal and background regions in the presence of non-negligible background contamination of the signal, and the minimum detectable polarization (MDP) that can be achieved when following this prescription.
Alba Peinado - One of the best experts on this subject based on the ideXlab platform.
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liquid crystal polymer full stokes division of focal plane Polarimeter
Optics Express, 2012Co-Authors: Graham Myhre, Weiliang Hsu, Alba Peinado, Charles F Lacasse, Neal Ock, Russell A Chipma, Stanley PauAbstract:A division-of-focal-plane Polarimeter based on a dichroic dye and liquid crystal polymer guest-host system is presented. Two Stokes Polarimeters are demonstrated: a linear Stokes and the first ever Full-Stokes division-of-focal-plane Polarimeter. The fabrication, packaging, and characterization of the systems are presented. Finally, optimized Polarimeter designs are discussed for future works.
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optimized stokes Polarimeters based on a single twisted nematic liquid crystal device for the minimization of noise propagation
Applied Optics, 2011Co-Authors: Alba Peinado, Josep Vidal, Claudio Iemmi, Angel Lizana, Juan CamposAbstract:This work evidences the suitability of applying a single twisted nematic liquid-crystal (TN-LC) device to obtain dynamic Polarimeters with high accuracy and repeatability. Different Stokes Polarimeter setups based on a TN-LC device are optimized, leading to the minimization of the noise propagated from intensity measurements to the Stokes vector calculations. To this aim, we revise the influence of working out of normal incidence and of performing a double pass of the light beam through the LC device. In addition, because transmissive TN-LC devices act as elliptical retarders, an extra study is performed. It analyzes the influence of projecting the light exiting from the TN-LC device over elliptical states of polarization. Finally, diverse optimized Polarimeters are experimentally implemented and validated by measuring different states of partially and fully polarized light. The analysis is conducted both for monochromatic (He–Ne laser) and LED light sources, proving the potential of Polarimeters based on a single TN-LC device.
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Study of Polarimeters based on liquid crystal panels
International Conference on Applications of Optics and Photonics, 2011Co-Authors: Alba Peinado, Josep Vidal, Claudio Iemmi, Angel Lizana, Juan CamposAbstract:In this work, we conduct a thoroughly comparison between different Stokes Polarimeters based on Liquid Crystal Displays: Polarimeters based on a single Twisted Nematic Liquid Crystal panel and on two Parallel Aligned Liquid Crystal panels. We carry out an optimization of the different polarimetric systems in order to reduce the noise propagation when measuring the polarization. In addition, we implement the three best optimized Polarimeters. The experimental results are provided and discussed. We demonstrate that by performing an accurately optimization of a dynamic Stokes Polarimeter based on a single Twisted Nematic Liquid Crystal panel, we achieve results close to those obtained by Polarimeters based on two Parallel Aligned Liquid Crystal panels.
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Complete Stokes Polarimeters based on liquid crystal displays
Optics and Photonics for Information Processing IV, 2010Co-Authors: Alba Peinado, Josep Vidal, Claudio Iemmi, Angel Lizana, Juan CamposAbstract:In this work, we present the design, optimization and experimental implementation of complete Stokes Polarimeters based on parallel aligned and twisted nematic liquid crystal displays. The liquid crystal elements are used as variable retarders whose retardance depends on the addressed voltage. By including this type of anisotropic devices in the Polarimeter design we obtain some benefits when compared to mechanical Polarimeters. For example, they allow to avoid the corresponding uncertainty due to mechanical movement. In addition, among the different Polarimeter configurations provided by the Polarimeter design, we have also applied an optimization procedure based on the minimization of different mathematical indicators (as the condition number or the equally weighted variance) in order to minimize the error amplification from the radiometric measurements to the solution. Finally, the optimized Polarimeters are experimentally implemented and tested. In the implementation process, the eigenvalues method (a rigorous calibration procedure) is used.
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optimization and performance criteria of a stokes Polarimeter based on two variable retarders
Optics Express, 2010Co-Authors: Alba Peinado, Josep Vidal, Claudio Iemmi, Angel Lizana, Juan CamposAbstract:In this paper we present the analysis, optimization and implementation of several Stokes Polarimeter configurations based on a set-up including two variable retarders. The Polarimeter analysis is based on the Mueller-Stokes formalism, and as a consequence, it is suitable to deal with depolarized light. Complete Stokes Polarimeters are optimized by minimizing the amplification of simulated errors into the final solution. Different indicators useful to achieve this aim, as the condition number or the equally weighted variance, are compared in this paper. Moreover, some of the optimized Polarimeters are experimentally implemented and it is studied the influence of small deviations from the theoretical ones on the amplification of the Stokes component error. In addition, the benefit of using incomplete Polarimeters, when detecting specific ranges of states of polarization, is discussed.
