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Polarimetric

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https://www.readbyqxmd.com/read/28092378/opto-valleytronic-imaging-of-atomically-thin-semiconductors
#1
Andre Neumann, Jessica Lindlau, Léo Colombier, Manuel Nutz, Sina Najmaei, Jun Lou, Aditya D Mohite, Hisato Yamaguchi, Alexander Högele
Transition metal dichalcogenide semiconductors represent elementary components of layered heterostructures for emergent technologies beyond conventional optoelectronics. In their monolayer form they host electrons with quantized circular motion and associated valley polarization and valley coherence as key elements of opto-valleytronic functionality. Here, we introduce two-dimensional polarimetry as means of direct imaging of the valley pseudospin degree of freedom in monolayer transition metal dichalcogenides...
January 16, 2017: Nature Nanotechnology
https://www.readbyqxmd.com/read/28059353/optimal-design-and-performance-metric-of-broadband-full-stokes-polarimeters-with-immunity-to-poisson-and-gaussian-noise
#2
Tingkui Mu, Zeyu Chen, Chunmin Zhang, Rongguang Liang
In this paper, the design, optimization and analysis of broadband full-Stokes polarimeters with immunity to both Poisson and Gaussian noise are presented. Different from the commonly-used optimization metrics such as, the condition number (CN), the equally weighted variance (EWV), or the polarimetric modulation efficiency (PME) for Gaussian noise, the optimally balanced condition for Poisson noise (BCPN) is, for the first time, proposed and used as a metric for the optimization of polarimeters. The numerical results show that the polarimeters optimized with the BCPN have immunity to both Poisson and Gaussian noise...
December 26, 2016: Optics Express
https://www.readbyqxmd.com/read/28059173/geometric-phase-shaping-of-terahertz-vortex-beams
#3
Amalya Minasyan, Clément Trovato, Jérôme Degert, Eric Freysz, Etienne Brasselet, Emmanuel Abraham
We propose a topological beam-shaping strategy of terahertz (THz) beams using geometric phase elements made of space-variant birefringent slabs. Quasi-monochromatic THz vortex beams are produced and characterized both in amplitude and phase from the reconstructed real-time two-dimensional imaging of the electric field. Nonseparable superpositions of such vortex beams are also obtained and characterized by two-dimensional polarimetric analysis. These results emphasize the versatility of the spin-orbit electromagnetic toolbox to prepare on-demand structured light endowed with polarization-controlled orbital angular momentum content in the THz domain, which should find many uses in future THz technologies...
January 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28054068/ml-and-ml2-complex-formation-between-ca-ii-and-d-glucose-derivatives-in-aqueous-solutions
#4
Bence Kutus, Dániel Ozsvár, Norbert Varga, István Pálinkó, Pál Sipos
The complex formation equilibria between Ca(2+) ions and six carbohydrate derivatives related to d-glucose was quantitatively characterized by potentiometry, freezing point depression and polarimetry. Complexation could not be observed for d-glucose, while weak association was deduced for d-sorbitol and d-mannitol. Stronger complexes are formed with d-gluconate and d-heptagluconate due to the presence of the carboxylate group. In addition to the plausible 1 : 1 species, the 1 : 2 species can also be detected at higher ligand to metal ratios...
January 5, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28019704/isolation-of-the-major-chiral-compounds-from-bubonium-graveolens-essential-oil-by-hplc-and-absolute-configuration-determination-by-vcd
#5
Mohammed El-Amin Said, Isabelle Bombarda, Jean-Valère Naubron, Pierre Vanloot, Marion Jean, Abdelkrim Cheriti, Nathalie Dupuy, Christian Roussel
The chirality issues in the essential oils (EOs) of leaves and flowers from Bubonium graveolens were addressed by chiral high-performance liquid chromatography (HPLC) with polarimetric detection and vibrational circular dichroism (VCD). The chemical compositions of the crude oils of three samples were established by gas chromatography / mass spectrometry (GC/MS). The well-known cis-chrysanthenyl acetate (1), oxocyclonerolidol (2), and the recently disclosed cis-acetyloxychrysanthenyl acetate (3), the three major chiral compounds, were isolated by preparative HPLC...
December 26, 2016: Chirality
https://www.readbyqxmd.com/read/27995046/a-c-band-broadband-ortho-mode-transducer-for-radioastronomy-polarimetry
#6
Ivan S Ferreira, Camilo Tello, Miguel Bergano, Thyrso Villela, Domingos Barbosa, George F Smoot
BACKGROUND: We describe the design, the construction and performance of a narrow band ortho-mode transducer, currently used in the 5 GHz polarimetric receiver of the Galactic Emission Mapping project. RESULTS: The ortho-mode transducer was designed to achieve a high degree of transmission within the 400 MHz of the GEM band around the 5 GHz (4.8-5.2 GHz). It is composed of a circular-to-square waveguide transition, a septum polarizer, a thin waveguide coupler and a smooth square-to-rectangular waveguide transition with custom waveguide bends to the output ports...
2016: SpringerPlus
https://www.readbyqxmd.com/read/27973824/unusual-chiroptical-properties-of-the-cryptophane-222-skeleton
#7
Delphine Pitrat, Nicolas Daugey, Marion Jean, Nicolas Vanthuyne, Frank Wien, Laurent Ducasse, Nathalie Calin, Thierry Buffeteau, Thierry Brotin
Enantiopure cryptophane-222 derivative (1) devoid of substituents was obtained via high-performance liquid chromatography (HPLC) using chiral stationary phases. The chiroptical properties of 1 were determined from polarimetry, electronic circular dichroism (ECD), synchrotron radiation circular dichroism (SRCD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) experiments and were compared to those of the cryptophane-A (2) derivative. Unusual polarimetric results were obtained for 1 in CHCl3 solvent as the sign of the optical rotation (OR) values changes in the nonresonance region above 365 nm, whereas no change was observed in the CH2Cl2 solvent...
December 15, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27958426/polarimetric-characteristics-of-a-class-of-hyperspectral-radiometers
#8
Marco Talone, Giuseppe Zibordi
The polarimetric characteristics of a class of hyperspectral radiometers commonly applied for above-water radiometry have been investigated by analyzing a sample of sensors. Results indicate polarization sensitivity increasing with wavelength and exhibiting values varying from sensor to sensor. In the case of radiance sensors, the maximum differences increase from approximately 0.4% at 400 nm to 1.3% at 750 nm. In the case of irradiance sensors, due to depolarizing effects of the diffusing collector, the maximum differences between horizontal and vertical polarization sensitivities vary from approximately 0...
December 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27958398/linear-depolarization-of-lidar-returns-by-aged-smoke-particles
#9
Michael I Mishchenko, Janna M Dlugach, Li Liu
We use the numerically exact (superposition) T-matrix method to analyze recent measurements of the backscattering linear depolarization ratio (LDR) for a plume of aged smoke at lidar wavelengths ranging from 355 to 1064 nm. We show that the unique spectral dependence of the measured LDRs can be modeled, but only by assuming expressly nonspherical morphologies of smoke particles containing substantial amounts of nonabsorbing (or weakly absorbing) refractory materials such as sulfates. Our results demonstrate that spectral backscattering LDR measurements can be indicative of the presence of morphologically complex smoke particles, but additional (e...
December 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27910372/far-forward-collective-scattering-measurements-by-fir-polarimeter-interferometer-on-j-text-tokamak
#10
P Shi, J Chen, L Gao, Y Liu, H Liu, Y N Zhou, G Zhuang
The multi-channel three-wave polarimeter-interferometer system on J-TEXT tokamak has been exploited to measure far-forward collective scattering from electron density fluctuations. The diagnostic utilizes far infrared lasers operated at 432 μm with 17-channel vertical chords (3 cm chord spacing), covering the entire cross section of plasma. Scattering laser power is measured using a high-sensitivity Schottky planar diode mixer which can also detect polarimetric and interferometric phase simultaneously. The system provides a line-integrated measurement of density fluctuations with maximum measurable wave number: k⊥max ≤ 2 cm(-1) and time response up to 350 kHz...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910346/initial-measurements-of-plasma-current-and-electron-density-profiles-using-a-polarimeter-interferometer-point-for-long-pulse-operation-in-east-invited
#11
H Q Liu, J P Qian, Y X Jie, W X Ding, D L Brower, Z Y Zou, W M Li, H Lian, S X Wang, Y Yang, L Zeng, T Lan, Y Yao, L Q Hu, X D Zhang, B N Wan
A double-pass, radially viewing, far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique has been implemented for diagnosing the plasma current and electron density profiles in the Experimental Advanced Superconducting Tokamak (EAST). POINT has been operated routinely during the most recent experimental campaign and provides continuous 11 chord line-integrated Faraday effect and density measurement throughout the entire plasma discharge for all heating schemes and all plasma conditions (including ITER relevant scenario development)...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27867715/changes-of-collagen-ultrastructure-in-breast-cancer-tissue-determined-by-second-harmonic-generation-double-stokes-mueller-polarimetric-microscopy
#12
Ahmad Golaraei, Lukas Kontenis, Richard Cisek, Danielle Tokarz, Susan J Done, Brian C Wilson, Virginijus Barzda
Second-harmonic generation (SHG) double Stokes-Mueller polarimetric microscopy is applied to study the alteration of collagen ultrastructure in a tissue microarray containing three pathological human breast cancer types with differently overexpressed estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2). Kleinman symmetry is experimentally validated in breast tissue for 1028 nm laser wavelength and it has been shown that measurements with only linearly polarized incoming and outgoing states can determine molecular nonlinear susceptibility tensor component ratio, average in-plane orientation of collagen fibers and degree of linear polarization of SHG...
October 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/27828395/high-throughput-static-channeled-interference-imaging-spectropolarimeter-based-on-a-savart-polariscope
#13
Chunmin Zhang, Qiwei Li, Tingyu Yan, Tingkui Mu, Yutong Wei
A high throughput static channeled interference imaging spectropolarimeter (CIISP) over 480-960nm spectral range is presented. The CIISP system includes two birefringent retarders and a Savart interferometer employing tempo-spatially mixed modulated mode with no internal moving parts, and offers a robust system and a high optical throughput to resist the instrument noise. The optical layout and operation of the CIISP sensor are presented in addition to the radiometric, spectral and improved polarimetric calibration techniques used with the system...
October 3, 2016: Optics Express
https://www.readbyqxmd.com/read/27828261/polarization-based-material-classification-technique-using-passive-millimeter-wave-polarimetric-imagery
#14
Fei Hu, Yayun Cheng, Liangqi Gui, Liang Wu, Xinyi Zhang, Xiaohui Peng, Jinlong Su
The polarization properties of thermal millimeter-wave emission capture inherent information of objects, e.g., material composition, shape, and surface features. In this paper, a polarization-based material-classification technique using passive millimeter-wave polarimetric imagery is presented. Linear polarization ratio (LPR) is created to be a new feature discriminator that is sensitive to material type and to remove the reflected ambient radiation effect. The LPR characteristics of several common natural and artificial materials are investigated by theoretical and experimental analysis...
November 1, 2016: Applied Optics
https://www.readbyqxmd.com/read/27828066/polarimetric-dehazing-method-for-visibility-improvement-based-on-visible-and-infrared-image-fusion
#15
Jian Liang, Wenfei Zhang, Liyong Ren, Haijuan Ju, Enshi Qu
Polarimetric dehazing methods have proven effective in enhancing the quality of chromatic hazy images. Considering that the infrared radiance has a better capacity for traveling through the haze, in this paper we propose a polarimetric dehazing method based on visible and infrared image fusion to improve the visibility of hazy images, especially for dense haze conditions. Experimental results demonstrate that the visibility of hazy images can be effectively enhanced, and the color information can be finely maintained...
October 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27827966/power-transmission-tower-series-extraction-in-polsar-image-based-on-time-frequency-analysis-and-a-contrario-theory
#16
Dongqing Peng, Haijian Zhang, Wei Guo, Wen Yang
Based on Time-Frequency (TF) analysis and a-contrario theory, this paper presents a new approach for extraction of linear arranged power transmission tower series in Polarimetric Synthetic Aperture Radar (PolSAR) images. Firstly, the PolSAR multidimensional information is analyzed using a linear TF decomposition approach. The stationarity of each pixel is assessed by testing the maximum likelihood ratio statistics of the coherency matrix. Then, based on the maximum likelihood log-ratio image, a Cell-Averaging Constant False Alarm Rate (CA-CFAR) detector with Weibull clutter background and a post-processing operator is used to detect point-like targets in the image...
November 5, 2016: Sensors
https://www.readbyqxmd.com/read/27823782/enantiomeric-fraction-of-styrene-glycol-as-a-biomarker-of-occupational-risk-exposure-to-styrene
#17
J J Lima, A Aguilar, F G Sánchez, A N Díaz
This work reports a new analytical approach for monitoring the enantiomeric ratios of styrene glycol (SG), encountered during the manufacture of plastics, by chiral liquid chromatography and the application as a biomarker for exposure to styrene. The isomers were separated using an AGP column running in the reverse phase and isocratic mode with a mobile phase consisting of 20 mM phosphate buffer saline (pH 4.15) and methanol at a flow rate of 0.8 mL/min. Photometric, polarimetric, and circular dichroism detectors were employed...
February 2017: Chemosphere
https://www.readbyqxmd.com/read/27801462/calcium-complexation-and-acid-base-properties-of-l-gulonate-a-diastereomer-of-d-gluconate
#18
Bence Kutus, Ákos Buckó, Gábor Peintler, István Pálinkó, Pál Sipos
The Ca(ii)-complexation and acid-base properties of l-gulonic acid (HGul), a diastereomer of d-gluconic acid (HGluc) differing only in the configurations of C2 and C5 have been investigated via(1)H and (13)C NMR spectroscopies, Ca-ISE- and pH-potentiometry, polarimetry and freezing point depression. Data obtained for Gul(-)/HGul have been compared with those of Gluc(-)/HGluc. It was found that some properties (acid dissociation constant, the stoichiometry and formation constants of the Ca(ii)-complexes) were insensitive to the difference in the configuration...
November 1, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27782606/three-axis-vector-atomic-magnetometer-utilizing-polarimetric-technique
#19
Swarupananda Pradhan
The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application...
September 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27782551/q-band-4-state-phase-shifter-in-planar-technology-circuit-design-and-performance-analysis
#20
E Villa, J Cagigas, B Aja, L de la Fuente, E Artal
A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90...
September 2016: Review of Scientific Instruments
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