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Sample records for polarization resolved measurements

  1. Depth-resolved measurements with elliptically polarized reflectance spectroscopy

    PubMed Central

    Bailey, Maria J.; Sokolov, Konstantin

    2016-01-01

    The ability of elliptical polarized reflectance spectroscopy (EPRS) to detect spectroscopic alterations in tissue mimicking phantoms and in biological tissue in situ is demonstrated. It is shown that there is a linear relationship between light penetration depth and ellipticity. This dependence is used to demonstrate the feasibility of a depth-resolved spectroscopic imaging using EPRS. The advantages and drawbacks of EPRS in evaluation of biological tissue are analyzed and discussed. PMID:27446712

  2. Spectrally- and polarization-resolved hyper-Rayleigh scattering measurements with polarization-insensitive detection

    NASA Astrophysics Data System (ADS)

    Němec, P.; Pásztor, F.; Brajer, M.; Němec, I.

    2017-04-01

    Determination of the molecular first hyperpolarizability by hyper-Rayleigh scattering (HRS) is usually significantly complicated by a presence of the multiphoton excited fluorescence which has to be separated from HRS to obtain a meaningful values of the hyperpolarizability. We show, by performing a spectrally-resolved measurement, that the intensity and spectral shape of the fluorescence can depend strongly on the fundamental laser wavelength. Consequently, a properly selected excitation wavelength can significantly simplify the process of separation of HRS from the detected signal. We tested the developed experimental setup with a polarization-insensitive detection by measuring HRS generated in water and in aqueous solutions of 2-aminopyrimidine (AMP) and its monocation (HAMP). The effective hyperpolarizability of AMP and HAMP was measured experimentally and compared with that obtained by quantum chemical calculations. The polarization-resolved HRS measurement was performed for AMP and the experimentally obtained depolarization ratio agrees well with that predicted theoretically, which confirms that routine density functional theory computations of static hyperpolarizability tensor components can be considered as a sufficient approach suitable for non-interacting molecules dissolved in water.

  3. Measuring polarization dependent dispersion of non-polarizing beam splitter cubes with spectrally resolved white light interferometry

    NASA Astrophysics Data System (ADS)

    Csonti, K.; Hanyecz, V.; Mészáros, G.; Kovács, A. P.

    2017-06-01

    In this work we have measured the group-delay dispersion of an empty Michelson interferometer for s- and p-polarized light beams applying two different non-polarizing beam splitter cubes. The interference pattern appearing at the output of the interferometer was resolved with two different spectrometers. It was found that the group-delay dispersion of the empty interferometer depended on the polarization directions in case of both beam splitter cubes. The results were checked by inserting a glass plate in the sample arm of the interferometer and similar difference was obtained for the two polarization directions. These results show that to reach high precision, linearly polarized white light beam should be used and the residual dispersion of the empty interferometer should be measured at both polarization directions.

  4. Measurement of orientation and susceptibility ratios using a polarization-resolved second-harmonic generation holographic microscope

    PubMed Central

    Winters, David G.; Smith, David R.; Schlup, Philip; Bartels, Randy A.

    2012-01-01

    Three-dimensional second-harmonic fields, sample orientation, and susceptibility ratios of biological samples are measured using polarization-resolved second-harmonic generation (SHG) microscopy. The three-dimensional (3D) polarization is gathered by measurement of a series of holograms for which excitation and analyzer polarizations are systematically varied, and the 3D SHG field is recovered through numerical back propagation. Harmonophore orientation is resolved in 3D from a sub-set of polarization-resolved SHG holograms. We further expand on previous approaches for the determination of susceptibility ratios, adding the calculation of multiple ratio values to allow intrinsic verification. PMID:23024896

  5. An imaging spectro-polarimeter for measuring hemispherical spectrally resolved down-welling sky polarization

    NASA Astrophysics Data System (ADS)

    Chenault, David B.; Pezzaniti, J. L.; Roche, Michael; Hyatt, Brian

    2016-05-01

    A full sky imaging spectro-polarimeter has been developed that measures spectrally resolved (~2.5 nm resolution) radiance and polarization (𝑠0, 𝑠1, 𝑠2 Stokes Elements) of natural sky down-welling over approximately 2π sr between 400nm and 1000nm. The sensor is based on a scanning push broom hyperspectral imager configured with a continuously rotating polarizer (sequential measurement in time polarimeter). Sensor control and processing software (based on Polaris Sensor Technologies Grave' camera control software) has a straight-forward and intuitive user interface that provides real-time updated sky down-welling spectral radiance/polarization maps and statistical analysis tools.

  6. Spectrally resolved fluorescence lifetime imaging of Nile red for measurements of intracellular polarity

    NASA Astrophysics Data System (ADS)

    Levitt, James A.; Chung, Pei-Hua; Suhling, Klaus

    2015-09-01

    Spectrally resolved confocal microscopy and fluorescence lifetime imaging have been used to measure the polarity of lipid-rich regions in living HeLa cells stained with Nile red. The emission peak from the solvatochromic dye in lipid droplets is at a shorter wavelength than other, more polar, stained internal membranes, and this is indicative of a low polarity environment. We estimate that the dielectric constant, ɛ, is around 5 in lipid droplets and 25<ɛ<40 in other lipid-rich regions. Our spectrally resolved fluorescence lifetime imaging microscopy (FLIM) data show that intracellular Nile red exhibits complex, multiexponential fluorescence decays due to emission from a short lifetime locally excited state and a longer lifetime intramolecular charge transfer state. We measure an increase in the average fluorescence lifetime of the dye with increasing emission wavelength, as shown using phasor plots of the FLIM data. We also show using these phasor plots that the shortest lifetime decay components arise from lipid droplets. Thus, fluorescence lifetime is a viable contrast parameter for distinguishing lipid droplets from other stained lipid-rich regions. Finally, we discuss the FLIM of Nile red as a method for simultaneously mapping both polarity and relative viscosity based on fluorescence lifetime measurements.

  7. Haze and cloud distribution in Uranus' atmosphere based on high-contrast spatially resolved polarization measurements

    NASA Astrophysics Data System (ADS)

    Kostogryz, Nadiia; Berdyugina, Svetlana; Gisler, Daniel; Berkefeld, Thomas

    2017-04-01

    In planetary atmospheres, main sources of opacity are molecular absorption and scattering on molecules, hazes and aerosols. Hence, light reflected from a planetary atmosphere can be linearly polarized. Polarization study of inner solar system planets and exoplanets is a powerful method to characterize their atmospheres, because of a wide range of observable phase angles. For outer solar system planets, observable phase angles are very limited. For instance, Uranus can only be observed up to 3.2 degrees away from conjunctions, and its disk-integrated polarization is close to zero due to the back-scattering geometry. However, resolving the disk of Uranus and measuring the center-to-limb polarization can help constraining the vertical atmospheric structure and the nature of scattering aerosols and particles. In October 2016, we carried out polarization measurements of Uranus in narrow-band filters centered at methane bands and the adjacent continuum using the GREGOR Planet Polarimeter (GPP). The GPP is a high-precision polarimeter and is mounted at the 1.5-m GREGOR solar telescope, which is suitable for observing at night. In order to reach a high spatial resolution, the instrument uses an adaptive-optics system of the telescope. To interpret our measurements, we solve the polarized radiative transfer problem taking into account different scattering and absorption opacities. We calculate the center-to-limb variation of polarization of Uranus' disk in the continuum spectrum and in methane bands. By varying the vertical distribution of haze and cloud layers, we derive the vertical structure of the best-fit Uranus atmosphere.

  8. Wavelength resolved polarized elastic scatter measurements from micron-sized single particles

    NASA Astrophysics Data System (ADS)

    Sivaprakasam, Vasanthi; Czege, Jozsef; Eversole, Jay D.

    2013-05-01

    The goal of this project is to investigate correlations of polarimetric angular scattering patterns from individual aerosol particles with the particles' physical structure and composition. Such signature patterns may be able to provide particle classification capability, such as, for example, discrimination between man-made and naturally occurring aerosols. If successful, this effort could improve current detection methods for biological warfare (BW) agent aerosols. So far, we have demonstrated an experimental arrangement to measure polarization-state resolved, multi-angle, scattering intensities from single aerosol particles on-the-fly. Our novel approach is a radical departure from conventional polarimetric measurement methods, and a key factor is the use of a multiple-order retarder to prepare different polarization states, depending on the wavelength of the incident light. This novel experimental technique uses a supercontinuum light source, an array of optical fibers, an imaging spectrometer and an EMCCD camera to simultaneously acquire wavelength and angle dependent particle light scattering data as a two-dimensional snapshot. Mueller matrix elements were initially measured from individual particles held in an optical trap (at 405 nm). Since particles can be stably trapped for long periods (hours), we were able to change the optical configuration to acquire multiple Mueller matrix element measurements on a single particle. We have computationally modeled these measurements at specific angles, and the comparison with experimental measurements shows good agreement. Similar measurements have also been made on slowly falling particles, and our current efforts are focused on improving experimental technique sufficiently to make such measurements on flowing particles.

  9. Development of a polarization-modulation spectroscopy system for the temporally resolved measurement of linear polarization in plasma emission

    NASA Astrophysics Data System (ADS)

    Yasui, Kenji; Shikama, Taiichi; Higashi, Takanori; Hasuo, Masahiro

    2016-10-01

    A system to measure linear polarization in the HeI 21P-31D emission line (667.8 nm) was developed for application to plasma polarization spectroscopy. To verify the system performance, the normalized Stokes parameters were evaluated. A measurement error of less than 1% with a time resolution of 1 ms was achieved for monochromatic light in the state of complete linear polarization.

  10. Nodal gap detection through polar angle-resolved density of states measurements in uniaxial superconductors

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Yasumasa; Nomoto, Takuya; Ikeda, Hiroaki; Machida, Kazushige

    2016-12-01

    We propose a spectroscopic method to identify the nodal gap structure in unconventional superconductors. This method is best suited for locating the horizontal line node and for pinpointing the isolated point nodes by measuring polar angle (θ ) resolved zero-energy density of states N (θ ) . This is measured by specific heat or thermal conductivity at low temperatures under a magnetic field. We examine a variety of uniaxially symmetric nodal structures, including point and/or line nodes with linear and quadratic dispersions, by solving the Eilenberger equation in vortex states. It is found that (a) the maxima of N (θ ) continuously shift from the antinodal to the nodal direction (θn) as a field increases accompanying the oscillation pattern reversal at low and high fields. Furthermore, (b) local minima emerge next to θn on both sides, except for the case of the linear point node. These features are robust and detectable experimentally. Experimental results of N (θ ) performed on several superconductors, UPd2Al3,URu2Si2,CuxBi2Se3 , and UPt3, are examined and commented on in light of the present theory.

  11. Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

    NASA Astrophysics Data System (ADS)

    van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

    2016-09-01

    Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

  12. Polarization measurement through combination polarizers

    NASA Astrophysics Data System (ADS)

    Bai, Yunfeng; Li, Linjun; He, Zhelong; Liu, Yanwei; Ma, Cheng; Shi, Guang; Liu, Lu

    2014-02-01

    Polarization measurement approaches only using polarizer and grating is present. The combination polarizers consists of two polarizers: one is γ degree with the X axis; the other is along the Y axis. Binary grating is covered by the combination polarizers, and based on Fraunhofer diffraction, the diffraction intensity formula is deduced. The polarization state of incident light can be gotten by fitting the diffraction pattern with the deduced formula. Compared with the traditional polarization measurement method, this measurement only uses polarizer and grating, therefore, it can be applied to measure a wide wavelength range without replacing device in theory.

  13. Time Resolved Spectroscopy of Eclipsing Polars

    NASA Technical Reports Server (NTRS)

    Barrett, Paul

    2005-01-01

    No changes have been made since the last annual progress report was submitted in conjunction with a unilateral NCX. Dr. Barrett was affected by an STScI Reduction in Force (RIF). He is now employed by the Johns Hopkins University and plans to continue his research there. No expenses have been charged to this grant, however the FUSE data for the eclipsing polar V1432 Aql has been received and processed using CALFWSE v3.0.6. The resulting summed spectrum has been used for a preliminary analysis of the interstellar absorption towards V1432 Aql. We find a hydrogen column density of less than 1.5e21 cm^-2. We have used this result in the paper "X-Ray Emission and Optical Polarization of V1432 Aquilae: An Asynchronous Polar" to fix the hydrogen column density in the soft (<0.5 keV) X-ray band when analyzing the XMM-Newton spectra of this polar. This has enabled us to find an accurate temperature for the blackbody component of 88+/-2 eV, which is significantly higher than that of other polars (20 - 40 eV). We hope to complete our analysis of the phase-resolved emission line spectra of V1432 Aql and to prepare the results for publication in a refereed journal. We hope to begin work on this star within the next few months.

  14. Time Resolved Spectroscopy of Eclipsing Polars

    NASA Astrophysics Data System (ADS)

    Barrett, Paul

    2005-09-01

    No changes have been made since the last annual progress report was submitted in conjunction with a unilateral NCX. Dr. Barrett was affected by an STScI Reduction in Force (RIF). He is now employed by the Johns Hopkins University and plans to continue his research there. No expenses have been charged to this grant, however the FUSE data for the eclipsing polar V1432 Aql has been received and processed using CALFWSE v3.0.6. The resulting summed spectrum has been used for a preliminary analysis of the interstellar absorption towards V1432 Aql. We find a hydrogen column density of less than 1.5e21 cm^-2. We have used this result in the paper "X-Ray Emission and Optical Polarization of V1432 Aquilae: An Asynchronous Polar" to fix the hydrogen column density in the soft (<0.5 keV) X-ray band when analyzing the XMM-Newton spectra of this polar. This has enabled us to find an accurate temperature for the blackbody component of 88+/-2 eV, which is significantly higher than that of other polars (20 - 40 eV). We hope to complete our analysis of the phase-resolved emission line spectra of V1432 Aql and to prepare the results for publication in a refereed journal. We hope to begin work on this star within the next few months.

  15. Polarization resolved angular optical scattering of aerosol particles

    NASA Astrophysics Data System (ADS)

    Redding, B.; Pan, Y.; Wang, C.; Videen, G.; Cao, Hui

    2014-05-01

    Real-time detection and identification of bio-aerosol particles are crucial for the protection against chemical and biological agents. The strong elastic light scattering properties of airborne particles provides a natural means for rapid, non-invasive aerosol characterization. Recent theoretical predictions suggested that variations in the polarization dependent angular scattering cross section could provide an efficient means of classifying different airborne particles. In particular, the polarization dependent scattering cross section of aggregate particles is expected to depend on the shape of the primary particles. In order to experimentally validate this prediction, we built a high throughput, sampling system, capable of measuring the polarization resolved angular scattering cross section of individual aerosol particles flowing through an interrogating volume with a single shot of laser pulse. We calibrated the system by comparing the polarization dependent scattering cross section of individual polystyrene spheres with that predicted by Mie theory. We then used the system to study different particles types: Polystyrene aggregates composed 500 nm spheres and Bacillus subtilis (BG, Anthrax simulant) spores composed of elongated 500 nm × 1000 nm cylinder-line particles. We found that the polarization resolved scattering cross section depends on the shape of the constituent elements of the aggregates. This work indicates that the polarization resolved scattering cross section could be used for rapid discrimination between different bio-aerosol particles.

  16. Development of a polarization resolved spectroscopic diagnostic for measurements of the magnetic field in the Caltech coaxial magnetized plasma jet experiment

    NASA Astrophysics Data System (ADS)

    Shikama, Taiichi; Bellan, Paul M.

    2011-11-01

    Measurements of the magnetic field strength in current-carrying magnetically confined plasmas are necessary for understanding the underlying physics governing the dynamical behavior. Such a measurement would be particularly useful in the Caltech coaxial magnetized plasma gun, an experiment used for fundamental studies relevant to spheromak formation, astrophysical jet formation/propagation, solar coronal physics, and the general behavior of twisted magnetic flux tubes that intercept a boundary. In order to measure the field strength in the Caltech experiment, a non-perturbing spectroscopic method is being implemented to observe the Zeeman splitting in the emission spectra. The method is based on polarization-resolving spectroscopy of the Zeeman-split σ components, a technique previously used in both solar and laboratory plasmas. We have designed and constructed an optical system that can simultaneously detect left- and right-circularly polarized emission with both high throughput and small extinction ratio. The system will be used on the 489.5 nm NII line, chosen because of its simple Zeeman structure and minimal Stark broadening.

  17. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures

    PubMed Central

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-01-01

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement. PMID:28327629

  18. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures

    NASA Astrophysics Data System (ADS)

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-03-01

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement.

  19. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures.

    PubMed

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-03-22

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement.

  20. Recoil polarization measurements

    NASA Astrophysics Data System (ADS)

    Brinkmann, Kai-Thomas

    2017-01-01

    Polarization observables in photon-induced meson production off nucleons have long been recognized to hold the promise of a detailed understanding of the excited states in the excitation spectrum of the nucleon. Photon beam and proton target polarization are routinely used at the ELSA facility in the Crystal Barrel/TAPS experiment and have yielded a wealth of data on contributing partial waves and nucleon resonances. A detector study on how to complement these ongoing studies by recoil polarization measurements that offer an orthogonal approach with otherwise unmeasurable observables in the field of non-strange meson photoproduction has been performed. Building on experience with silicon detectors operated in the photon beamline environment, first possible layouts of Si detector telescopes for recoil protons were developed. Various geometries, e.g. Archimedean spiral design of annular sensors, sector shapes and rectangular sensors were studied and have been used during test measurements. A prototype for the recoil polarimeter was built and subjected to performance tests in protonproton scattering at the COSY-accelerator in Jülich.

  1. Time-resolved polarization study of anisotropy in bacteriorhodopsin

    SciTech Connect

    Wan, Chaozhi; Qian, Jun; Johnson, C.K. )

    1990-11-01

    Time-resolved polarization spectroscopy is sensitive to the orientational dynamics of chromophores, and as a result it can be applied to study internal motion in restrictive environments. This paper describes the application of polarization spectroscopy to the photoactive protein bacteriorhodopsin on time scales from picoseconds to hundreds of microseconds. Anisotropy persists in both the ground-state bacteriorhodopsin population and in the photocycle intermediates due to a population bottleneck in the bacteriorhodopsin photocycle. The time dependence of the polarization signal expected for a sequence of intermediates is described and is shown to be sensitive both to population kinetics and to internal motion. The observed time dependence of the polarization signal reveals internal motion in the purple membrane fragments on the time scale of the K {yields} L transition ({approximately} 1 {mu}s). The results are consistent with the known kinetics of the bacteriorhodopsin photocycle. Evidence is also presented and discussed for a decay component on a time scale of < 50 ps.

  2. Forward versus backward polarization-resolved SHG imaging of collagen structure in tissues

    NASA Astrophysics Data System (ADS)

    Teulon, Claire; Gusachenko, Ivan; Latour, Gaël.; Schanne-Klein, Marie-Claire

    2016-03-01

    Second harmonic generation (SHG) is a powerful technique to observe fibrillar collagen without any staining and with a good contrast. More information about the molecular structure of collagen fibrils in tissues and their 3D distribution can be gained with polarization-resolved SHG imaging. Nevertheless, strong focusing is required for effective imaging and light propagation in tissues is complex and not thoroughly understood yet, preventing accurate and reproducible measurements. Theoretical analysis, vectorial numerical simulations and experiments were implemented to understand how the SHG signal builds up and how geometrical parameters affect polarization-resolved measurements in homogeneous collagen-rich tissues.

  3. Information Content Analysis for the Multi-Viewing, Multi-Channel, Multi-Polarization Imaging (3MI) Instrument : Toward Retrieval of Vertically Resolved Cloud Properties from Passive Only Measurements.

    NASA Astrophysics Data System (ADS)

    Riedi, J.; Merlin, G.; Labonnote, L.; Cornet, C.; Ferlay, N.; Desmons, M.; Dubuisson, P.; Parol, F.; Davis, A. B.; Marbach, T.

    2014-12-01

    efforts to obtain vertically resolved information on cloud properties from 3MI passive measurements only. In particular the synergy of multiangle polarization measurements at 443 and 865 nm with Oxygen A-band differential absorption information to retrieve cloud geometrical thickness will be discussed.

  4. Imaging dental sections with polarization-resolved SHG and time-resolved autofluorescence

    NASA Astrophysics Data System (ADS)

    Chen, Jun Huang; Lin, Po-Yen; Hsu, Stephen C. Y.; Kao, Fu-Jen

    2009-02-01

    In this study, we are using two-photon (2-p) excited autofluorescence and second harmonic (SH) as imaging modalities to investigate dental sections that contains the enamel and the dentin. The use of near-infrared wavelengths for multiphoton excitation greatly facilitates the observation of these sections due to the hard tissue's larger index of refraction and highly scattering nature. Clear imaging can be achieved without feature altering preparation procedures of the samples. Specifically, we perform polarization resolving on SH and lifetime analysis on autofluorescence. Polarization resolved SH reflects the preferred orientation of collagen while very different autofluorescence lifetimes are observed from the dentin and the enamel. The origin of 2-p autofluorescence and SH signals are attributed to hydroxyapatite crystals and collagen fibrils, respectively. Hydroxyapatite is found to be present throughout the sections while collagen fibrils exist only in the dentin and dentinoenamel junctions.

  5. Early dental caries detection using a fibre-optic coupled polarization-resolved Raman spectroscopic system.

    PubMed

    Ko, Alex C-T; Hewko, Mark; Sowa, Michael G; Dong, Cecilia C S; Cleghorn, Blaine; Choo-Smith, Lin-P'ing

    2008-04-28

    A new fibre-optic coupled polarization-resolved Raman spectroscopic system was developed for simultaneous collection of orthogonally polarized Raman spectra in a single measurement. An application of detecting incipient dental caries based on changes observed in Raman polarization anisotropy was also demonstrated using the developed fibre-optic Raman spectroscopic system. The predicted reduction of polarization anisotropy in the Raman spectra of caries lesions was observed and the results were consistent with those reported previously with Raman microspectroscopy. The capability of simultaneous collection of parallel- and cross-polarized Raman spectra of tooth enamel in a single measurement and the improved laser excitation delivery through fibre-optics demonstrated in this new design illustrates its future clinical potential.

  6. Early dental caries detection using a fibre-optic coupled polarization-resolved Raman spectroscopic system

    PubMed Central

    Ko, Alex C.-T.; Hewko, Mark; Sowa, Michael G.; Dong, Cecilia C.S.; Cleghorn, Blaine; Choo-Smith, Lin-P’ing

    2008-01-01

    A new fibre-optic coupled polarization-resolved Raman spectroscopic system was developed for simultaneous collection of orthogonally polarized Raman spectra in a single measurement. An application of detecting incipient dental caries based on changes observed in Raman polarization anisotropy was also demonstrated using the developed fibre-optic Raman spectroscopic system. The predicted reduction of polarization anisotropy in the Raman spectra of caries lesions was observed and the results were consistent with those reported previously with Raman microspectroscopy. The capability of simultaneous collection of parallel-and cross-polarized Raman spectra of tooth enamel in a single measurement and the improved laser excitation delivery through fibre-optics demonstrated in this new design illustrates its future clinical potential. PMID:18545331

  7. Improved quantification of collagen anisotropy with polarization-resolved second harmonic generation microscopy.

    PubMed

    Hristu, Radu; Stanciu, Stefan G; Tranca, Denis E; Stanciu, George A

    2017-09-01

    Imaging tissue samples by polarization-resolved second harmonic generation microscopy provides both qualitative and quantitative insights into collagen organization in a label-free manner. Polarization-resolved second harmonic generation microscopy goes beyond simple intensity-based imaging by adding the laser beam polarization component and applying different quantitative metrics such as the anisotropy factor. It thus provides valuable information on collagen arrangement not available with intensity measurements alone. Current established approaches are limited to calculating the anisotropy factor for only a particular laser beam polarization and no general guidelines on how to select the best laser beam polarization have yet been defined. Here, we introduce a novel methodology for selecting the optimal laser beam polarization for characterizing tissues using the anisotropy in the purpose of identifying cancer signatures. We show that the anisotropy factor exhibits a similar laser beam polarization dependence to the second harmonic intensity and we combine it with the collagen orientation index computed by Fast Fourier Transform analysis of the recorded images to establish a framework for choosing the laser beam polarization that is optimal for an accurate interpretation of polarization-resolved second harmonic generation microscopy images and anisotropy maps, and hence a better differentiation between healthy and dysplastic areas. SHG image of skin tissue (a) and a selected area of interest for which we compute the SHG intensity (b) and anisotropy factor (c) dependence on the laser beam polarization and also the FFT spectrum (d) to evaluate the collagen orientation index. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Nonselective and polarization effects in time-resolved optogalvanic spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhechev, D.; Steflekova, V.

    2016-02-01

    Three interfering effects in optogalvanic (OG) spectroscopy are identified in a hollow cathode discharge (HCD) - OG detector. The laser beam is found to generate two nonselective processes, namely photoelectron emission (PE) from the cathode surface with a sub-breakdown bias applied, and nonresonant space ionization. The convolution of these galvanic contributions was determined experimentally as an instrumental function and a deconvolution procedure to determine the actual OG signal was developed. Specific plasma conductance is detected dependent on the polarization of the laser beam irradiating. Linearly/circularly polarized light beam is found to induce OG signals differ in amplitude (and their shape parameters in the time-resolved OG signals (TROGS)). The phenomena coherence and specific conductance are found to be in causal relationship. The additional conductance due to coherent states of atoms manifests itself as an intrinsic instrumental property of OG detector.

  9. Sensitivity of VIIRS Polarization Measurements

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene

    2010-01-01

    The design of an optical system typically involves a sensitivity analysis where the various lens parameters, such as lens spacing and curvatures, to name two parameters, are (slightly) varied to see what, if any, effect this has on the performance and to establish manufacturing tolerances. A sinular analysis was performed for the VIIRS instruments polarization measurements to see how real world departures from perfectly linearly polarized light entering VIIRS effects the polarization measurement. The methodology and a few of the results of this polarization sensitivity analysis are presented and applied to the construction of a single polarizer which will cover the VIIRS VIS/NIR spectral range. Keywords: VIIRS, polarization, ray, trace; polarizers, Bolder Vision, MOXTEK

  10. In vivo multiphoton imaging of the cornea: polarization-resolved second harmonic generation from stromal collagen

    NASA Astrophysics Data System (ADS)

    Latour, G.; Gusachenko, I.; Kowalczuk, L.; Lamarre, I.; Schanne-Klein, M.-C.

    2012-03-01

    Multiphoton microscopy provides specific and contrasted images of unstained collagenous tissues such as tendons or corneas. Polarization-resolved second harmonic generation (SHG) measurements have been implemented in a laserscanning multiphoton microscope. Distortion of the polarimetric response due to birefringence and diattenuation during propagation of the laser excitation has been shown in rat-tail tendons. A model has been developed to account for these effects and correct polarization-resolved SHG images in thick tissues. This new modality is then used in unstained human corneas to access two quantitative parameters: the fibrils orientation within the collagen lamellae and the ratio of the main second-order nonlinear tensorial components. Orientation maps obtained from polarization resolution of the trans-detected SHG images are in good agreement with the striated features observed in the raw images. Most importantly, polarization analysis of the epi-detected SHG images also enables to map the fibrils orientation within the collagen lamellae while epi-detected SHG images of corneal stroma are spatially homogenous and do not enable direct visualization of the fibrils orientation. Depth profiles of the polarimetric SHG response are also measured and compared to models accounting for orientation changes of the collagen lamellae within the focal volume. Finally, in vivo polarization-resolved SHG is performed in rat corneas and structural organization of corneal stroma is determined using epi-detected signals.

  11. Polarization-resolved near-backscattering of airborne aggregates composed of different primary particles.

    PubMed

    Redding, Brandon; Pan, Yong-Le; Wang, Chuji; Cao, Hui

    2014-07-15

    We measured the polarization-resolved angular elastic scattering intensity distribution of aggregates composed of primary particles with different shapes and packing densities in the near-backward directions (155°-180°). Specifically, we compare aggregates composed of spherical polystyrene latex spheres, cylinder-like Bacillus subtilis particles, and Arizona road dust, as well as tryptophan particles. We observe clearly differentiable polarization aspect ratios and find that the negative polarization dip is more pronounced in more densely packed aggregates or particles. This work indicates that the polarization aspect ratio in the near-backward direction may be used as a fingerprint to discriminate between aggregates with the same size and overall shape by differences in their constituent particles.

  12. Polar plot representation of time-resolved fluorescence.

    PubMed

    Eichorst, John Paul; Wen Teng, Kai; Clegg, Robert M

    2014-01-01

    Measuring changes in a molecule's fluorescence emission is a common technique to study complex biological systems such as cells and tissues. Although the steady-state fluorescence intensity is frequently used, measuring the average amount of time that a molecule spends in the excited state (the fluorescence lifetime) reveals more detailed information about its local environment. The lifetime is measured in the time domain by detecting directly the decay of fluorescence following excitation by short pulse of light. The lifetime can also be measured in the frequency domain by recording the phase and amplitude of oscillation in the emitted fluorescence of the sample in response to repetitively modulated excitation light. In either the time or frequency domain, the analysis of data to extract lifetimes can be computationally intensive. For example, a variety of iterative fitting algorithms already exist to determine lifetimes from samples that contain multiple fluorescing species. However, recently a method of analysis referred to as the polar plot (or phasor plot) is a graphical tool that projects the time-dependent features of the sample's fluorescence in either the time or frequency domain into the Cartesian plane to characterize the sample's lifetime. The coordinate transformations of the polar plot require only the raw data, and hence, there are no uncertainties from extensive corrections or time-consuming fitting in this analysis. In this chapter, the history and mathematical background of the polar plot will be presented along with examples that highlight how it can be used in both cuvette-based and imaging applications.

  13. Polarization-Resolved Raman Spectroscopy of Rhenium Disulfide

    NASA Astrophysics Data System (ADS)

    Chenet, Daniel; Aslan, Ozgur; Heinz, Tony; van der Zande, Arend; Hone, James

    2015-03-01

    Rhenium Disulfide (ReS2) is a layered semiconductor with each layer exhibiting a distorted 1T crystal structure. The reduced symmetry of the distorted 1T structure creates anisotropic optical and electrical properties that have been previously studied in bulk films. Herein, we demonstrate anisotropic behavior in its Raman spectra. We then correlate these vibrational modes with polarized absorption measurements in thin films in order to develop a versatile technique for determining the crystal orientation of anisotropic semiconducting thin films.

  14. Polarization Lidar for Shallow Water Depth Measurement

    NASA Astrophysics Data System (ADS)

    Mitchell, S.; Thayer, J. P.

    2011-12-01

    A bathymetric, polarization lidar system transmitting at 532 nanometers is developed for applications of shallow water depth measurement. The technique exploits polarization attributes of the probed water body to isolate surface and floor returns, enabling constant fraction detection schemes to determine depth. The minimum resolvable water depth is no longer dictated by the system's laser or detector pulse width and can achieve better than an order of magnitude improvement over current water depth determination techniques. In laboratory tests, a Nd:YAG microchip laser coupled with polarization optics, a single photomultiplier tube, a constant fraction discriminator and a time to digital converter are used to target various water depths. Measurement of 1 centimeter water depths with an uncertainty of ±3 millimeters are demonstrated using the technique. Additionally, a dual detection channel version of the lidar system is in development, permitting simultaneous measurement of co- and cross-polarized signals scattered from the target water body. This novel approach enables new approaches to designing laser bathymetry systems for shallow depth determination from remote platforms while not compromising deep water depth measurement, supporting comprehensive hydrodynamic studies.

  15. Numerical simulation of polarization-resolved second-harmonic microscopy in birefringent media

    NASA Astrophysics Data System (ADS)

    Gusachenko, Ivan; Schanne-Klein, Marie-Claire

    2013-11-01

    Polarization-resolved second-harmonic microscopy has recently emerged as a valuable technique for in situ imaging of collagen structure in tissues. Nevertheless, collagen-rich tissues such as tendon, ligament, skin dermis, bone, cornea, or artery exhibit a heterogeneous and anisotropic architecture that results in complex optical properties. While experimental evidence of polarization distortions has been reported in various tissues, the physics of second-harmonic imaging within such tissues is not fully understood yet. In this work, we performed numerical simulations of polarization-resolved second-harmonic generation in a strongly focused regime within a birefringent tissue. We show that vectorial components due to strong focusing have a rather small effect on the measurement of the second-harmonic tensorial response, while birefringence and optical dispersion may affect these measurements dramatically. We show indeed that a difference in the focal field distribution for ordinary and extraordinary waves results in different phase-matching conditions, which strongly affects the relative efficacy of second-harmonic generation for different polarizations. These results are of great interest for extracting reliable quantitative parameters from second-harmonic images.

  16. Linear Polarization Measurements of Chromospheric Emission Lines

    NASA Technical Reports Server (NTRS)

    Sheeley, N. R., Jr.; Keller, C. U.

    2003-01-01

    We have used the Zurich Imaging Stokes Polarimeter (ZIMPOL I) with the McMath-Pierce 1.5 m main telescope on Kitt Peak to obtain linear polarization measurements of the off-limb chromosphere with a sensitivity better than 1 x 10(exp -5). We found that the off-disk observations require a combination of good seeing (to show the emission lines) and a clean heliostat (to avoid contamination by scattered light from the Sun's disk). When these conditions were met, we obtained the following principal results: 1. Sometimes self-reversed emission lines of neutral and singly ionized metals showed linear polarization caused by the transverse Zeeman effect or by instrumental cross talk from the longitudinal Zeeman effect in chromospheric magnetic fields. Otherwise, these lines tended to depolarize the scattered continuum radiation by amounts that ranged up to 0.2%. 2. Lines previously known to show scattering polarization just inside the limb (such as the Na I lambda5889 D2 and the He I lambda5876 D3 lines) showed even more polarization above the Sun's limb, with values approaching 0.7%. 3. The O I triplet at lambda7772, lambda7774, and lambda7775 showed a range of polarizations. The lambda7775 line, whose maximum intrinsic polarizability, P(sub max), is less than 1%, revealed mainly Zeeman contributions from chromospheric magnetic fields. However, the more sensitive lambda7772 (P(sub max) = 19%) and lambda7774 (P(sub max) = 29%) lines had relatively strong scattering polarizations of approximately 0.3% in addition to their Zeeman polarizations. At times of good seeing, the polarization spectra resolve into fine structures that seem to be chromospheric spicules.

  17. Linear Polarization Measurements of Chromospheric Emission Lines

    NASA Technical Reports Server (NTRS)

    Sheeley, N. R., Jr.; Keller, C. U.

    2003-01-01

    We have used the Zurich Imaging Stokes Polarimeter (ZIMPOL I) with the McMath-Pierce 1.5 m main telescope on Kitt Peak to obtain linear polarization measurements of the off-limb chromosphere with a sensitivity better than 1 x 10(exp -5). We found that the off-disk observations require a combination of good seeing (to show the emission lines) and a clean heliostat (to avoid contamination by scattered light from the Sun's disk). When these conditions were met, we obtained the following principal results: 1. Sometimes self-reversed emission lines of neutral and singly ionized metals showed linear polarization caused by the transverse Zeeman effect or by instrumental cross talk from the longitudinal Zeeman effect in chromospheric magnetic fields. Otherwise, these lines tended to depolarize the scattered continuum radiation by amounts that ranged up to 0.2%. 2. Lines previously known to show scattering polarization just inside the limb (such as the Na I lambda5889 D2 and the He I lambda5876 D3 lines) showed even more polarization above the Sun's limb, with values approaching 0.7%. 3. The O I triplet at lambda7772, lambda7774, and lambda7775 showed a range of polarizations. The lambda7775 line, whose maximum intrinsic polarizability, P(sub max), is less than 1%, revealed mainly Zeeman contributions from chromospheric magnetic fields. However, the more sensitive lambda7772 (P(sub max) = 19%) and lambda7774 (P(sub max) = 29%) lines had relatively strong scattering polarizations of approximately 0.3% in addition to their Zeeman polarizations. At times of good seeing, the polarization spectra resolve into fine structures that seem to be chromospheric spicules.

  18. Measuring polarization in microlensing events

    NASA Astrophysics Data System (ADS)

    Ingrosso, G.; Calchi Novati, S.; De Paolis, F.; Jetzer, Ph.; Nucita, A. A.; Strafella, F.

    2015-01-01

    We reconsider the polarization of the star light that may arise during microlensing events due to the high gradient of magnification across the atmosphere of the source star, by exploring the full range of microlensing and stellar physical parameters. Since it is already known that only cool evolved giant stars give rise to the highest polarization signals, we follow the model by Simmons et al. to compute the polarization as due to the photon scattering on dust grains in the stellar wind. Motivated by the possibility to perform a polarization measurement during an ongoing microlensing event, we consider the recently reported event catalogue by the Optical Gravitational Lensing Experiment (OGLE) collaboration covering the 2001-2009 campaigns (OGLE-III events), that makes available the largest and more comprehensive set of single-lens microlensing events towards the Galactic bulge. The study of these events, integrated by a Monte Carlo analysis, allows us to estimate the expected polarization profiles and to predict for which source stars and at which time is most convenient to perform a polarization measurement in an ongoing event. We find that about two dozens of OGLE-III events (about 1 per cent of the total) have maximum polarization degree in the range 0.1 < Pmax < 1 per cent, corresponding to source stars with apparent magnitude I ≲ 14.5, being very cool red giants. This signal is measurable by using the FOcal Reducer and low dispersion Spectrograph (FORS2) polarimeter at Very Large Telescope (VLT) telescope with about 1 h integration time.

  19. Time-Resolved Measurements in Optoelectronic Microbioanalysis

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Kossakovski, Dmitri

    2003-01-01

    A report presents discussion of time-resolved measurements in optoelectronic microbioanalysis. Proposed microbioanalytical laboratory-on-a-chip devices for detection of microbes and toxic chemicals would include optoelectronic sensors and associated electronic circuits that would look for fluorescence or phosphorescence signatures of multiple hazardous biomolecules in order to detect which ones were present in a given situation. The emphasis in the instant report is on gating an active-pixel sensor in the time domain, instead of filtering light in the wavelength domain, to prevent the sensor from responding to a laser pulse used to excite fluorescence or phosphorescence while enabling the sensor to respond to the decaying fluorescence or phosphorescence signal that follows the laser pulse. The active-pixel sensor would be turned on after the laser pulse and would be used to either integrate the fluorescence or phosphorescence signal over several lifetimes and many excitation pulses or else take time-resolved measurements of the fluorescence or phosphorescence. The report also discusses issues of multiplexing and of using time-resolved measurements of fluorophores with known different fluorescence lifetimes to distinguish among them.

  20. Time-resolved fluorescence polarization spectroscopy of visible and near infrared dyes in picosecond dynamics

    NASA Astrophysics Data System (ADS)

    Pu, Yang; Alfano, Robert R.

    2015-03-01

    Near-infrared (NIR) dyes absorb and emit light within the range from 700 to 900 nm have several benefits in biological studies for one- and/or two-photon excitation for deeper penetration of tissues. These molecules undergo vibrational and rotational motion in the relaxation of the excited electronic states, Due to the less than ideal anisotropy behavior of NIR dyes stemming from the fluorophores elongated structures and short fluorescence lifetime in picosecond range, no significant efforts have been made to recognize the theory of these dyes in time-resolved polarization dynamics. In this study, the depolarization of the fluorescence due to emission from rotational deactivation in solution will be measured with the excitation of a linearly polarized femtosecond laser pulse and a streak camera. The theory, experiment and application of the ultrafast fluorescence polarization dynamics and anisotropy are illustrated with examples of two of the most important medical based dyes. One is NIR dye, namely Indocyanine Green (ICG) and is compared with Fluorescein which is in visible range with much longer lifetime. A set of first-order linear differential equations was developed to model fluorescence polarization dynamics of NIR dye in picosecond range. Using this model, the important parameters of ultrafast polarization spectroscopy were identified: risetime, initial time, fluorescence lifetime, and rotation times.

  1. A LACK OF RESOLVED NEAR-INFRARED POLARIZATION ACROSS THE FACE OF M51

    SciTech Connect

    Pavel, Michael D.; Clemens, Dan P. E-mail: clemens@bu.edu

    2012-12-20

    The galaxy M51 was observed using the Mimir instrument on the Perkins Telescope to constrain the resolved H-band (1.6 {mu}m) polarization across the galaxy. These observations place an upper limit of P{sub H} < 0.05% on the H-band polarization across the face of M51, at 0.6 arcsec pixel sampling. Even with smoothing to coarser angular resolutions, to reduce polarization uncertainty, the H-band polarization remains undetected. The polarization upper limit at H band, when combined with previous resolved optical polarimetry, rules out a Serkowski-like polarization dependence on wavelength. Other polarization mechanisms cannot account for the observed polarization ratio (P{sub H}/P{sub VRI} {approx}< 0.05) across the face of M51.

  2. Measuring Gravitation Using Polarization Spectroscopy

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Yu, Nan; Maleki, Lute

    2004-01-01

    A proposed method of measuring gravitational acceleration would involve the application of polarization spectroscopy to an ultracold, vertically moving cloud of atoms (an atomic fountain). A related proposed method involving measurements of absorption of light pulses like those used in conventional atomic interferometry would yield an estimate of the number of atoms participating in the interferometric interaction. The basis of the first-mentioned proposed method is that the rotation of polarization of light is affected by the acceleration of atoms along the path of propagation of the light. The rotation of polarization is associated with a phase shift: When an atom moving in a laboratory reference interacts with an electromagnetic wave, the energy levels of the atom are Doppler-shifted, relative to where they would be if the atom were stationary. The Doppler shift gives rise to changes in the detuning of the light from the corresponding atomic transitions. This detuning, in turn, causes the electromagnetic wave to undergo a phase shift that can be measured by conventional means. One would infer the gravitational acceleration and/or the gradient of the gravitational acceleration from the phase measurements.

  3. Polarization-resolved SHG microscopy of rat-tail tendon with controlled mechanical strain

    NASA Astrophysics Data System (ADS)

    Gusachenko, I.; Goulam Houssen, Y.; Tran, V.; Allain, J.-M.; Schanne-Klein, M.-C.

    2013-06-01

    We combined polarization-resolved SHG microscopy with mechanical assays in rat-tail-tendon and measured collagen remodeling upon controlled stretching. This approach aimed to analyze the relationship between macroscopic response and sub-micrometer scale organization of collagen fibrils. We observed a straightening of the crimps followed by a sliding of the fibrils with increasing stretching of the tendon fascicles. Polarization resolution of the SHG images provided complementary information about the orientation dispersion of collagen fibrils within the focal volume and enabled monitoring of collagen remodeling at the sub-micrometer scale. Our approach can be readily generalized to other tissues and should bring new valuable information about biomechanics of microstructured tissues.

  4. Orientation-resolved domain mapping in tetragonal SrTiO3 using polarized Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gray, Dodd J.; Merz, Tyler A.; Hikita, Yasuyuki; Hwang, Harold Y.; Mabuchi, Hideo

    2016-12-01

    We present microscopically resolved, polarized spectroscopy of Raman scattering collected from tetragonal SrTiO3. The anisotropic response of first-order Raman peaks within a single tetragonal domain has been measured. From these data, we assign symmetries to the phonons seen in the first-order Raman spectrum which is normally complicated by uncontrolled domain structure. Using a translation stage, we map the local domain orientation of a 3 -μ m3 crystal volume near the laser focus and compare it to wide-field polarized images. This technique can be performed with readily available instruments and is relevant to the study of a wide range of related materials, interfaces, and devices.

  5. Time Resolved Deposition Measurements in NSTX

    SciTech Connect

    C.H. Skinner; H. Kugel; A.L. Roquemore; J. Hogan; W.R. Wampler; the NSTX team

    2004-08-03

    Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen, and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 {micro}g/cm{sup 2} of deposition, however surprisingly, 15.9 {micro}g/cm{sup 2} of material loss occurred at 7 discharges. The net deposited mass of 13.3 {micro}g/cm{sup 2} matched the mass of 13.5 {micro}g/cm{sup 2} measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition.

  6. Polar Dunes Resolved by the Mars Orbiter Laser Altimeter Gridded Topography and Pulse Widths

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory A.

    2003-01-01

    The Mars Orbiter Laser Altimeter (MOLA) polar data have been refined to the extent that many features poorly imaged by Viking Orbiters are now resolved in densely gridded altimetry. Individual linear polar dunes with spacings of 0.5 km or more can be seen as well as sparsely distributed and partially mantled dunes. The refined altimetry will enable measurements of the extent and possibly volume of the north polar ergs. MOLA pulse widths have been recalibrated using inflight data, and a robust algorithm applied to solve for the surface optical impulse response. It shows the surface root-mean-square (RMS) roughness at the 75-m-diameter MOLA footprint scale, together with a geological map. While the roughness is of vital interest for landing site safety studies, a variety of geomorphological studies may also be performed. Pulse widths corrected for regional slope clearly delineate the extent of the polar dunes. The MOLA PEDR profile data have now been re-released in their entirety (Version L). The final Mission Experiment Gridded Data Records (MEGDR's) are now provided at up to 128 pixels per degree globally. Densities as high as 512 pixels per degree are available in a polar stereographic projection. A large computational effort has been expended in improving the accuracy of the MOLA altimetry themselves, both in improved orbital modeling and in after-the-fact adjustment of tracks to improve their registration at crossovers. The current release adopts the IAU2000 rotation model and cartographic frame recommended by the Mars Cartography Working Group. Adoption of the current standard will allow registration of images and profiles globally with an uncertainty of less than 100 m. The MOLA detector is still operational and is currently collecting radiometric data at 1064 nm. Seasonal images of the reflectivity of the polar caps can be generated with a resolution of about 300 m per pixel.

  7. Polar Dunes Resolved by the Mars Orbiter Laser Altimeter Gridded Topography and Pulse Widths

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory A.

    2003-01-01

    The Mars Orbiter Laser Altimeter (MOLA) polar data have been refined to the extent that many features poorly imaged by Viking Orbiters are now resolved in densely gridded altimetry. Individual linear polar dunes with spacings of 0.5 km or more can be seen as well as sparsely distributed and partially mantled dunes. The refined altimetry will enable measurements of the extent and possibly volume of the north polar ergs. MOLA pulse widths have been recalibrated using inflight data, and a robust algorithm applied to solve for the surface optical impulse response. It shows the surface root-mean-square (RMS) roughness at the 75-m-diameter MOLA footprint scale, together with a geological map. While the roughness is of vital interest for landing site safety studies, a variety of geomorphological studies may also be performed. Pulse widths corrected for regional slope clearly delineate the extent of the polar dunes. The MOLA PEDR profile data have now been re-released in their entirety (Version L). The final Mission Experiment Gridded Data Records (MEGDR's) are now provided at up to 128 pixels per degree globally. Densities as high as 512 pixels per degree are available in a polar stereographic projection. A large computational effort has been expended in improving the accuracy of the MOLA altimetry themselves, both in improved orbital modeling and in after-the-fact adjustment of tracks to improve their registration at crossovers. The current release adopts the IAU2000 rotation model and cartographic frame recommended by the Mars Cartography Working Group. Adoption of the current standard will allow registration of images and profiles globally with an uncertainty of less than 100 m. The MOLA detector is still operational and is currently collecting radiometric data at 1064 nm. Seasonal images of the reflectivity of the polar caps can be generated with a resolution of about 300 m per pixel.

  8. Time-resolved scanning electron microscopy with polarization analysis

    SciTech Connect

    Frömter, Robert Oepen, Hans Peter; Kloodt, Fabian; Rößler, Stefan; Frauen, Axel; Staeck, Philipp; Cavicchia, Demetrio R.; Bocklage, Lars; Röbisch, Volker; Quandt, Eckhard

    2016-04-04

    We demonstrate the feasibility of investigating periodically driven magnetization dynamics in a scanning electron microscope with polarization analysis based on spin-polarized low-energy electron diffraction. With the present setup, analyzing the time structure of the scattering events, we obtain a temporal resolution of 700 ps, which is demonstrated by means of imaging the field-driven 100 MHz gyration of the vortex in a soft-magnetic FeCoSiB square. Owing to the efficient intrinsic timing scheme, high-quality movies, giving two components of the magnetization simultaneously, can be recorded on the time scale of hours.

  9. Conversion of sunflower multiband radiometer polarization measurements to polarization parameters

    NASA Technical Reports Server (NTRS)

    Biehl, Larry L.

    1995-01-01

    The data processing analysis and conversion of polarization measurements to polarization parameters from the Sunflower multiband radiometer is presented in this final report. Included is: (1) the actual data analysis; (2) the comparison of the averaging techniques and the percent polarization derived from the original and averaged I, Q, U parameters; (3) the polarizer angles used in conversion; (4) the Matlab files; (5) the relative ground size, field of view location, and view zenith angles, and (6) the summary of all the sky data for all dates.

  10. Nanosecond Time-Resolved Polarization Spectroscopies: Tools for Probing Protein Reaction Mechanisms

    PubMed Central

    Chen, Eefei; Goldbeck, Robert A.; Kliger, David S.

    2010-01-01

    Polarization methods, introduced in the 1800’s, offered one of the earliest ways to examine protein structure. Since then, many other structure-sensitive probes have been developed, but circular dichroism (CD) remains a powerful technique because of its versatility and the specificity of protein structural information that can be explored. With improvements in time-resolution, from millisecond to picosecond CD measurements, it has proven to be an important tool for studying the mechanism of folding and function in many biomolecules. For example, nanosecond time-resolved CD (TRCD) studies of the sub-microsecond events of reduced cytochrome c folding have provided direct experimental evidence of kinetic heterogeneity, which is an inherent property of the diffusional nature of early folding dynamics on the energy landscape. In addition, TRCD has been applied to the study of many biochemical processes, such as ligand rebinding in hemoglobin and myoglobin and signaling state formation in photoactive yellow protein and prototropin 1 LOV2. The basic approach to TRCD has also been extended to include a repertoire of nanosecond polarization spectroscopies: optical rotatory dispersion (ORD), magnetic CD and ORD, and linear dichroism. This article will discuss the details of the polarization methods used in this laboratory, as well as the coupling of timeresolved ORD with the temperature-jump trigger so that protein folding can be studied in a larger number of proteins. PMID:20438842

  11. RESOLVE for Lunar Polar Ice/Volatile Characterization Mission

    NASA Technical Reports Server (NTRS)

    Sanders, G. B.; Larson, W. E.; Quinn, J. W.; Colaprete, A.; Picard, M.; Boucher, D.

    2011-01-01

    Ever since data from the neutron spectrometer instrument on the Lunar Prospector mission indicated the possibility of significant concentrations of hydrogen at the lunar poles, speculation on the form and concentration of the hydrogen has been debated. The recent impact of the Lunar Crater Observation and Sensing Satellite (LCROSS) along with thermal, topographic, neutron spectrometry, and radar frequency data obtained from the Lunar Reconnaissance Orbiter (LRO) have provided more information suggesting significant amounts of water/ice and other volatiles may be available in the top 1 to 2 meters of regolith at the lunar poles. The next step in understanding what resources are available at the lunar poles is to perform a mission to obtain ground truth. data. To meet this need, the US National Aeronautics and Space Administration (NASA) along with the Canadian Space Agency (CSA) have been working on a prototype payload known as the Regolith & Environment Science and Oxygen & Lunar Volatile Extraction experiment, or RESOLVE.

  12. Spectrally resolved motional Stark effect measurements on ASDEX Upgrade

    SciTech Connect

    Reimer, R.; Dinklage, A.; Wolf, R.; Fischer, R.; Hobirk, J.; Löbhard, T.; Mlynek, A.; Reich, M.; Sawyer, L.; Collaboration: ASDEX Upgrade

    2013-11-15

    A spectrally resolved Motional Stark Effect (MSE) diagnostic has been installed at ASDEX Upgrade. The MSE data have been fitted by a forward model providing access to information about the magnetic field in the plasma interior [R. Reimer, A. Dinklage, J. Geiger et al., Contrib. Plasma Phys. 50, 731–735 (2010)]. The forward model for the beam emission spectra comprises also the fast ion D{sub α} signal [W. W. Heidbrink and G. J. Sadler, Nucl. Fusion 34, 535–615 (1994)] and the smearing on the CCD-chip. The calculated magnetic field data as well as the revealed (dia)magnetic effects are consistent with the results from equilibrium reconstruction solver. Measurements of the direction of the magnetic field are affected by unknown and varying polarization effects in the observation.

  13. Time-resolved Temperature Measurements in SSPX

    SciTech Connect

    Ludington, A R; Hill, D N; McLean, H S; Moller, J; Wood, R D

    2006-08-14

    We seek to measure time-resolved electron temperatures in the SSPX plasma using soft X-rays from free-free Bremsstrahlung radiation. To increase sensitivity to changes in temperature over the range 100-300 eV, we use two photodiode detectors sensitive to different soft X-ray energies. The detectors, one with a Zr/C coating and the other with a Ti/Pd coating, view the plasma along a common line of sight tangential to the magnetic axis of the spheromak, where the electron temperature is a maximum. The comparison of the signals, over a similar volume of plasma, should be a stronger function of temperature than a single detector in the range of Te< 300 eV. The success of using photodiodes to detect changing temperatures along a chord will make the case for designing an array of the detectors, which could provide a time changing temperature profile over a larger portion of the plasma.

  14. Real-time inversion of polarization gate frequency-resolved optical gating spectrograms.

    PubMed

    Kane, Daniel J; Weston, Jeremy; Chu, Kai-Chien J

    2003-02-20

    Frequency-resolved optical gating (FROG) is a technique used to measure the intensity and phase of ultrashort laser pulses through the optical construction of a spectrogram of the pulse. To obtain quantitative information about the pulse from its spectrogram, an iterative two-dimensional phase retrieval algorithm must be used. Current algorithms are quite robust but retrieval of all the pulse information can be slow. Previous real-time FROG trace inversion work focused on second-harmonic-generation FROG, which has an ambiguity in the direction of time, and required digital signal processors (DSPs). We develop a simplified real-time FROG device based on a single-shot geometry that no longer requires DSPs. We use it and apply the principal component generalized projections algorithm to invert polarization gate FROG traces at rates as high as 20 Hz.

  15. Investigation of gravity waves using horizontally resolved radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Stober, G.; Sommer, S.; Rapp, M.; Latteck, R.

    2013-10-01

    The Middle Atmosphere Alomar Radar System (MAARSY) on the island of Andøya in Northern Norway (69.3° N, 16.0° E) observes polar mesospheric summer echoes (PMSE). These echoes are used as tracers of atmospheric dynamics to investigate the horizontal wind variability at high temporal and spatial resolution. MAARSY has the capability of pulse-to-pulse beam steering allowing for systematic scanning experiments to study the horizontal structure of the backscatterers as well as to measure the radial velocities for each beam direction. Here we present a method to retrieve gravity wave parameters from these horizontally resolved radial wind variations by applying velocity azimuth display and volume velocity processing. Based on the observations a detailed comparison of the two wind analysis techniques is carried out in order to determine the zonal and meridional wind as well as to measure first-order inhomogeneities. Further, we demonstrate the possibility to resolve the horizontal wave properties, e.g., horizontal wavelength, phase velocity and propagation direction. The robustness of the estimated gravity wave parameters is tested by a simple atmospheric model.

  16. Investigation of gravity waves using horizontally resolved radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Stober, G.; Sommer, S.; Rapp, M.; Latteck, R.

    2013-06-01

    The Middle Atmosphere Alomar Radar System (MAARSY) on the island Andøya in Northern Norway (69.3° N, 16.0° E) observes polar mesospheric summer echoes (PMSE). These echoes are used as tracers of atmospheric dynamics to investigate the horizontal wind variability at high temporal and spatial resolution. MAARSY has the capability of a pulse-to-pulse beam steering allowing for systematic scanning experiments to study the horizontal structure of the backscatterers as well as to measure the radial velocities for each beam direction. Here we present a method to retrieve gravity wave parameters from these horizontally resolved radial wind variations by applying velocity azimuth display and volume velocity processing. Based on the observations a detailed comparison of the two wind analysis techniques is carried out in order to determine the zonal and meridional wind as well as to measure first order inhomogeneities. Further, we demonstrate the possibility to resolve the horizontal wave properties, e.g. horizontal wavelength, phase velocity and propagation direction. The robustness of the estimated gravity wave parameters is tested by a simple atmospheric model.

  17. TIME-RESOLVED SPECTROSCOPY OF THE POLAR EU CANCRI IN THE OPEN CLUSTER MESSIER 67

    SciTech Connect

    Williams, Kurtis A.; Howell, Steve B.; Bellini, Andrea; Rubin, Kate H. R.; Bolte, Michael E-mail: steve.b.howell@nasa.gov E-mail: psmith@as.arizona.edu E-mail: rubin@mpia.de

    2013-05-15

    We present time-resolved spectroscopic and polarimetric observations of the AM Her system EU Cnc. EU Cnc is located near the core of the old open cluster Messier 67; new proper motion measurements indicate that EU Cnc is indeed a member of the star cluster, and this system therefore is useful to constrain the formation and evolution of magnetic cataclysmic variables. The spectra exhibit two-component emission features with independent radial velocity variations as well as time-variable cyclotron emission indicating a magnetic field strength of 41 MG. The period of the radial velocity and cyclotron hump variations are consistent with the previously known photometric period, and the spectroscopic flux variations are consistent in amplitude with previous photometric amplitude measurements. The secondary star is also detected in the spectrum. We also present polarimetric imaging measurements of EU Cnc that show a clear detection of polarization, and the degree of polarization drops below our detection threshold at phases when the cyclotron emission features are fading or not evident. The combined data are all consistent with the interpretation that EU Cnc is a low-state polar in the cluster Messier 67. The mass function of the system gives an estimate of the accretor mass of M{sub WD} {>=} 0.68 M{sub Sun} with M{sub WD} Almost-Equal-To 0.83 M{sub Sun} for an average inclination. We are thus able to place a lower limit on the progenitor mass of the accreting white dwarf of {>=}1.43 M{sub Sun }.

  18. Prospecting for Polar Volatiles: Results from the Resolve Field

    NASA Technical Reports Server (NTRS)

    Elphic, Richard C.; Colarprete, Anthony; Deans, Matthew C.; Heldman, Jennifer; Sanders, Gerald B.; Larson, William E.

    2013-01-01

    Both the Moon and Mercury evidently host ice and other volatile compounds in cold traps at the planets poles. Determining the form, spatial distribution, and abundance of these volatiles at the lunar poles can help us understand how and when they were delivered and emplaced. This bears directly on the delivery of water and prebiotic compounds to the inner planets over the solar system s history, and also informs plans for utilizing the volatiles as resources for sustained human exploration as well as the commercial development of space. Temperature models and orbital data suggest near-surface volatile concentrations may exist at polar locations not strictly in permanent shadow. Remote operation of a robotic lunar rover mission for the 7-10 days of available sunlight would permit key questions to be answered. But such a short, quick-tempo mission has unique challenges and requires a new concept of operations. Both science and rover operations decisionmaking must be done in real time, requiring immediate situational awareness, data analysis, and decision support tools.

  19. Hierarchical model of fibrillar collagen distribution for polarization-resolved SHG microscopy

    NASA Astrophysics Data System (ADS)

    Tuer, Adam E.; Akens, Margarete K.; Krouglov, Serguei; Sandkuijl, Daaf; Wilson, Brian C.; Whyne, Cari M.; Barzda, Virginijus

    2013-02-01

    A hierarchical model of the organization of fibrillar collagen is developed and its implications on polarization-resolved second harmonic generation (SHG) microscopy are investigated. A "ground-up" approach is employed to develop the theory for understanding of the origin of SHG from fibrillar collagen. The effects of fibril ultrastructure and fibril macroscopic organization on the second-order polarization properties of fibrillar collagen are presented in conjunction with recent ab initio results performed on a collagen triple-helix model (-GLY-PRO-HYP-)n. Various tissues containing fibrillar collagen are quantified using a polarization-resolved SHG technique, termed polarization-in, polarization-out (PIPO) and interpreted in light of the aforementioned theory. The method involves varying the incident laser polarization, while monitoring the SHG intensity through an analyzer. From the SHG polarization data the orientation of the fibers, in biological tissue, can be deduced. Unique PIPO signatures are observed for different rat tissues and interpreted in terms of the collagen composition, fibril ultrastructure, and macroscopic organization. Similarities and discrepancies in the second-order polarization properties of different collagen types and ultrastructures will be presented. PIPO SHG microscopy shows promise in its ability to quantify the organization of collagen in various tissues. The ability to characterize the structure of collagen in various tissue microenvironments will aid in the study of numerous collagen related biological process, including tissue diseases, wound repair, and tumor development and progression.

  20. Automated measurement of polarized bidirectional reflectance

    NASA Technical Reports Server (NTRS)

    Gibbs, Daniel P.; Betty, Chris L.; Fung, Adrian K.; Blanchard, Andrew J.; Irons, James R.; Balsam, William L.

    1993-01-01

    An Automated Bidirectional Reflection Acquisition Measurement System (ABRAMS) has been constructed to facilitate measurement of bidirectional reflectance from soil and vegetative samples in the laboratory. The system illuminates a sample with linearly-polarized laser light, lambda = 632.8 nm, and measures the like- and cross-polarized scattered intensities over half a hemisphere. System design and polarized bidirectional reflectance measurements from a soil sample and SiO2 spherical particles are discussed in this work. It is shown that polarization information in the plane of incidence is useful for identifying certain scattering mechanisms associated with soil reflectance. This is because the like-polarized intensity, Ivv, is influenced by single-scattered light and the cross-polarized intensity, IHv, is strongly influenced by multiple-scattered light. For example, comparable levels of Ivv and IHv indicated that the reflectance of soils, is dominated by significant multiple scattering because single scattering causes minimal depolarization in the plane of incidence.

  1. Motionless polarization-resolved second harmonic generation imaging of corneal collagen

    NASA Astrophysics Data System (ADS)

    Breunig, Hans G.; Batista, Ana; Uchugonova, Aisada; König, Karsten

    2015-03-01

    Polarization-resolved second harmonic generation microscopy was used to investigate the collagenous structures of cornea samples in vitro in forward and backward direction. Although structural features appear different in both directions, following an approach by Latour et al. the collagen domain orientation is determined in forward as well as in backward direction, the latter being the only accessible direction for in vivo imaging. The experimental setup enables fast and completely motionless rotation of the polarization direction of 100 fs pulses by a polarization rotation based on a liquid crystal retarder.

  2. Multiscale analysis of polarization-resolved third-harmonic generation microscopy from ordered lipid assemblies

    NASA Astrophysics Data System (ADS)

    Zimmerley, Maxwell; Mahou, Pierre; Débarre, Delphine; Schanne-Klein, Marie-Claire; Beaurepaire, Emmanuel

    2013-03-01

    Nonlinear optical microscopy is a biocompatible avenue for probing ordered molecular assemblies in biological tissues. As in linear optics, the nonlinear optical response from ordered systems is polarization-sensitive. This dependence can be used to identify and characterize local molecular ordering with micrometer-scale 3D resolution in a nonlinear microscope. In particular, third-harmonic generation (THG) microscopy is a nonlinear optical modality sensitive to the electronic nonlinear susceptibility χ(3) of a material. THG microscopy can be used to map χ(3) spatial variations (i.e. material interfaces), and to probe birefringence. In principle, polarization-resolved THG (P-THG) can therefore be used to probe ordered molecular arrays. However, the orientation, distribution, and nonlinear optical properties of the molecules near the beam focus all affect the detected signal. It is therefore necessary to develop a theoretical method which decouples these effects and permits the extraction of orientational information from P-THG images. In this report, we first present P-THG images of model systems (lipid droplets, multilamellar lipid vesicles) and biological tissues (human skin biopsy) which establish that P-THG is sensitive to lipid ordering and that it is maximized when excitation polarization is parallel to the ordered lipid molecules, giving impetus for the development of a thorough theoretical analysis. We then outline a multiscale model spanning the molecular (nm) and ensemble (μm) scales predicting the PTHG signal, consisting of three main steps: (i) calculation of the molecular electronic hyperpolarizability; (ii) determination of the anisotropic χ(3) for various molecular distribution parameters; and (iii) numerical calculations of the P-THG signal from lipid-water interfaces. This analysis links the measured P-THG response to lipid molecular structure and ordering.

  3. Measuring Speed Of Rotation With Two Brushless Resolvers

    NASA Technical Reports Server (NTRS)

    Howard, David E.

    1995-01-01

    Speed of rotation of shaft measured by use of two brushless shaft-angle resolvers aligned so electrically and mechanically in phase with each other. Resolvers and associated circuits generate voltage proportional to speed of rotation (omega) in both magnitude and sign. Measurement principle exploits simple trigonometric identity.

  4. The Primordial Inflation Polarization Explorer: Science from Circular Polarization Measurements

    NASA Astrophysics Data System (ADS)

    Switzer, Eric; Ade, P.; Benford, D. J.; Bennett, C. L.; Chuss, D. T.; Dotson, J. L.; Eimer, J.; Fixsen, D. J.; Halpern, M.; Hinshaw, G. F.; Irwin, K.; Jhabvala, C.; Johnson, B.; Kogut, A. J.; Lazear, J.; Mirel, P.; Moseley, S. H.; Staguhn, J.; Tucker, C. E.; Weston, A.; Wollack, E.

    2014-01-01

    The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne CMB polarimeter designed to constrain the B-mode signature of cosmological inflation. Sequential one-day flights from Northern- and Southern- Hemisphere sites will yield maps of Stokes I, Q, U and V at 200, 270, 350 and 600 GHz over 85% of the sky. The full optical path is cooled to 1.5 K by liquid helium in the ARCADE bucket dewar, and a variable-delay polarization modulator (VPM) at the front of the optics modulates the polarization response. Independent Q and U cameras each have two 32x40 Transition Edge Sensor array receivers. In addition to its primary inflationary science goal, PIPER will also measure the circular (Stokes V) polarization to a depth similar to that of the primary linear polarization. The circular polarization has received relatively little attention in large-area surveys, with constraints from the 1980’s and recent results by the Milan Polarimeter. Astrophysical circular polarization is generally tied to the presence of magnetic fields, either in relativistic plasmas or Zeeman splitting of resonances. These effects are thought to be undetectable at PIPER's frequencies and resolution, despite the depth. The expectation of a null result makes the deep Stokes V map a good cross-check for experimental systematics. More fundamentally, the fact that the sky is expected to be dark in Stokes V makes it a sector sensitive to processes such as Lorentz-violating terms in the standard model or magnetic fields in the CMB era.

  5. Polarization-resolved second harmonic generation microscopy of chiral G-shaped metamaterials

    NASA Astrophysics Data System (ADS)

    Mamonov, Evgeniy A.; Maydykovskiy, Anton I.; Kolmychek, Irina A.; Magnitskiy, Sergey A.; Murzina, Tatiana V.

    2017-08-01

    Chiral planar metamaterials are known for their possibility to show strong nonlinear optical effects such as second harmonic generation (SHG) circular dichroism or asymmetric SHG. The underlying mechanisms are commonly discussed in terms of local field effects and formation of localized SHG sources (so called "hotspots") that are sensitive to the shape and size of meta-atoms. Nevertheless, a full characterization of the polarization state of the nonlinear optical radiation from the hotspots has not been performed until now. Here we present the results of the polarization-resolved second harmonic generation microscopy studies of planar chiral G-shaped metamaterials. We demonstrate that the SHG radiation coming from the hotspots that are localized within a single meta-atom is partially polarized; moreover, the SHG polarization state reveals the chirality of the structure. The observed effects are attributed to the induced plasmonic current oscillations at the fundamental frequency along with the local field distribution.

  6. Time-resolved dynamical Franz-Keldysh effect produced by an elliptically polarized laser

    NASA Astrophysics Data System (ADS)

    Otobe, T.

    2016-10-01

    An analytical formula is reported describing the time-resolved dynamical Franz-Keldysh effect (Tr-DFKE) produced by an elliptically polarized laser at subfemtosecond timescale. The Houston function is assumed as the time-dependent wave function of the parabolic two-band system. For elliptical polarization, the resulting formula exhibits subcycle changes in the optical properties; the modulation of the dielectric function is smaller than that for linear polarization. In contrast, the subcycle modulation of the dielectric function, a significant feature of the Tr-DFKE, disappears for a circularly polarized laser. This analytical formula shows good qualitative agreement with the first-principle calculation employing the time-dependent density functional theory for diamond.

  7. Angle resolved scatter measurement of bulk scattering in transparent ceramics

    NASA Astrophysics Data System (ADS)

    Sharma, Saurabh; Miller, J. Keith; Shori, Ramesh K.; Goorsky, Mark S.

    2015-02-01

    Bulk scattering in polycrystalline laser materials (PLM), due to non-uniform refractive index across the bulk, is regarded as the primary loss mechanism leading to degradation of laser performance with higher threshold and lower output power. The need for characterization techniques towards identifying bulk scatter and assessing the quality. Assessment of optical quality and the identification of bulk scatter have been by simple visual inspection of thin samples of PLMs, thus making the measurements highly subjective and inaccurate. Angle Resolved Scatter (ARS) measurement allows for the spatial mapping of scattered light at all possible angles about a sample, mapping the intensity for both forward scatter and back-scatter regions. The cumulative scattered light intensity, in the forward scatter direction, away from the specular beam is used for the comparison of bulk scattering between samples. This technique employ the detection of scattered light at all angles away from the specular beam directions and represented as a 2-D polar map. The high sensitivity of the ARS technique allows us to compare bulk scattering in different PLM samples which otherwise had similar transmitted beam wavefront distortions.

  8. Fiber-based lensless polarization holography for measuring Jones matrix parameters of polarization-sensitive materials.

    PubMed

    Liu, Xuan; Yang, Yang; Han, Lu; Guo, Cheng-Shan

    2017-04-03

    We report a fiber-based lensless holographic imaging system to realize a single-shot measurement of two dimensional (2-D) Jones matrix parameters of polarization-sensitive materials. In this system, a multi-source lensless off-axis Fresnel holographic recording geometry is adopted, and two optical fiber splitters are used to generate the multiple reference and illumination beams required for recording a four-channel angular-multiplexing polarization hologram (AMPH). Using this system and the method described in this paper, spatially resolved Jones matrix parameters of a polarization-sensitive material can be retrieved from one single-shot AMPH. We demonstrate the feasibility of the method by extracting a 2-D Jones matrix of a composite polarizer. Applications of the method to measure the Jones matrix maps of a stressed polymethyl methacrylate sample and a mica fragment are also presented. Benefit from the fiber-based and lensless off-axis holographic design, the system possesses a quite compact configuration, which provides a feasible approach for development of an integrated and portable system to measure Jones matrix parameters of polarization-sensitive materials.

  9. Spectroscopic approaches to resolving ambiguities of hyper-polarized NMR signals from different reaction cascades.

    PubMed

    Jensen, Pernille Rose; Meier, Sebastian

    2016-02-07

    The influx of exogenous substrates into cellular reaction cascades on the seconds time scale is directly observable by NMR spectroscopy when using nuclear spin polarization enhancement. Conventional NMR assignment spectra for the identification of reaction intermediates are not applicable in these experiments due to the non-equilibrium nature of the nuclear spin polarization enhancement. We show that ambiguities in the intracellular identification of transient reaction intermediates can be resolved by experimental schemes using site-specific isotope labelling, optimised referencing and response to external perturbations.

  10. Polarization resolved near-IR imaging of sound and carious dental enamel

    NASA Astrophysics Data System (ADS)

    Darling, Cynthia L.; Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    A thorough understanding of how polarized near-IR light is reflected from and transmitted through sound and carious dental hard tissues is important for the development of optical imaging devices. New optical imaging tools employing non-ionizing radiation are needed for the detection and assessment of dental caries. In this investigation, an automated system was developed to collect images for the full 16-element Mueller Matrix. The polarized light was controlled by linear polarizers and liquid crystal retarders and the 36 images were acquired as the polarized near-IR light is reflected from the occlusal surface or transmitted through thin sections of extracted human whole teeth. Previous near-IR imaging studies suggest that polarization imaging can be exploited to obtain higher contrast images of early dental caries due to the rapid depolarization of incident polarized light by the highly scattering areas of decay. In this study, the reflectance from tooth occlusal surfaces with demineralization and transmitted light through tooth thin sections with caries lesions were investigated. Major differences in the Mueller matrix elements were observed in both sound and demineralized enamel. This study suggests that polarization resolved optical imaging can be exploited to obtain higher contrast images of dental decay.

  11. Stokes vector based polarization resolved second harmonic microscopy of starch granules

    PubMed Central

    Mazumder, Nirmal; Qiu, Jianjun; Foreman, Matthew R.; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2013-01-01

    We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms a natural photonic crystal structure. By integration over all the solid angle, it will allow very similar SHG quantum efficiency regardless of the angle or the states of incident polarization. Given type I phase matching and the concentric shell structure of a starch granule, one can easily infer the polarization states of the input beam from the resulting SH micrograph. PMID:23577289

  12. Identifying the crystalline orientation of black phosphorus using angle-resolved polarized Raman spectroscopy.

    PubMed

    Wu, Juanxia; Mao, Nannan; Xie, Liming; Xu, Hua; Zhang, Jin

    2015-02-16

    An optical anisotropic nature of black phosphorus (BP) is revealed by angle-resolved polarized Raman spectroscopy (ARPRS), and for the first time, an all-optical method was realized to identify the crystal orientation of BP sheets, that is, the zigzag and armchair directions. We found that Raman intensities of Ag(1), B2g, and Ag(2) modes of BP not only depend on the polarization angle α, but also relate to the sample rotation angle θ. Furthermore, their intensities reach the local maximum or minimum values when the crystalline orientation is along with the polarization direction of scattered light (es). Combining with the angle-resolved conductance, it is confirmed that Ag(2) mode intensity achieves a relative larger (or smaller) local maximum under parallel polarization configuration when armchair (or zigzag) direction is parallel to es. Therefore, ARPRS can be used as a rapid, precise, and nondestructive method to identify the crystalline orientation of BP layers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Phase-resolved Spectroscopy of the Intermediate Polars -- TV Col and V1223 Sgr

    NASA Astrophysics Data System (ADS)

    Long, K.

    The cataclysmic variables called intermediate polars are characterized by magnetic fields that rip material from an accretion disk and funnel it to a WD that is not phase-locked to the binary period of the system. This is a proposal to use FUSE to conduct a time-resolved spectroscopic study to dissect the emission of two long-period intermediate polars, V1223 Sgr and TV Col, with very different inclination angles. These, along with the short-period high-inclination IP EX Hya (already observed with FUSE), comprise the only IPs with accurate distances derived from HST astrometry. We will isolate emission from the photosphere of the WD, the magnetically dominated accretion curtain, and the accretion stream. Having characterized the emission sources, we will explore the physical conditions in these same regions, and develop an integrated picture of these two intermediate polars.

  14. Infrared polarization measurements of Io in 1986

    NASA Technical Reports Server (NTRS)

    Sinton, William M.; Goguen, Jay D.; Nagata, Tetsuya; Ellis, H. Benton, Jr.; Werner, Michael

    1988-01-01

    New polarization measurements of Io were made with two different polarimeters at 3.8 and 4.8 microns. The measurements, at phase angles of about 2 deg, detect the polarization of reflected sunlight at both wavelengths. Only upper limits can be determined for the volcanic activity in 1986, but these limits show that there has been a remarkable decrease in activity, particularly of the Loki volcano, at these short wavelengths. The 1984 data (Goguen and Sinton (1985) are reanalyzed with the new model, which includes polarization of reflected sunlight. The large amount of thermal emission from the Loki volcano in 1984 produced a polarization that was dominant over that of reflected sunlight.

  15. Infrared polarization measurements of Io in 1986

    SciTech Connect

    Sinton, W.M.; Goguen, J.D.; Nagata, T.; Ellis, H.B. Jr.; Werner, M.

    1988-09-01

    New polarization measurements of Io were made with two different polarimeters at 3.8 and 4.8 microns. The measurements, at phase angles of about 2 deg, detect the polarization of reflected sunlight at both wavelengths. Only upper limits can be determined for the volcanic activity in 1986, but these limits show that there has been a remarkable decrease in activity, particularly of the Loki volcano, at these short wavelengths. The 1984 data (Goguen and Sinton (1985) are reanalyzed with the new model, which includes polarization of reflected sunlight. The large amount of thermal emission from the Loki volcano in 1984 produced a polarization that was dominant over that of reflected sunlight. 29 references.

  16. Spatially and spectrally resolved ultra-narrowband TE-polarization absorber based on the guide-mode resonance

    NASA Astrophysics Data System (ADS)

    Liao, Yan-Lin; Zhao, Yan; Zhang, Xingfang; Zhang, Wen; Wang, Zhongzhu

    2017-08-01

    A spatially and spectrally resolved ultra-narrowband absorber with a dielectric grating and metal substrate has been reported. The absorber shows that the absorption rate is more than 0.99 with the absorption bandwidth less than 1.5 nm at normal incidence for TE polarization (electric field is parallel to grating grooves). The angular width of the absorption is about 0.27∘. The wavelength-angle sensitivity and absorption-angle sensitivity are 13.4 nm per degree and 296.3% per degree, respectively. The simulation results also show the spatially and spectrally resolved ultra-narrowband absorption is originated from the guide-mode resonance. In addition, the wavelength-angle sensitivity can be improved by enlarging the grating period according to the guide-mode resonance mechanism. The proposed absorber has potential applications in optical filters, angle measurement and thermal emitters.

  17. Polarization Measurements on SUMI's TVLS Gratings

    NASA Technical Reports Server (NTRS)

    Kobayashi, K.; West, E. A.; Davis, J. M.; Gary, G. A.

    2007-01-01

    We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC). SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV emission lines sensitive to magnetic fields, the CIY line at 155nm and the MgII line at 280nm. The instrument uses a pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on bare aluminum gratings and aluminum/MgF2 coated gratings, at both linear polarizations.

  18. Polarization Sensitive Coherent Raman Measurements of DCVJ

    NASA Astrophysics Data System (ADS)

    Anderson, Josiah; Cooper, Nathan; Lawhead, Carlos; Shiver, Tegan; Ujj, Laszlo

    2014-03-01

    Coherent Raman spectroscopy which recently developed into coherent Raman microscopy has been used to produce label free imaging of thin layers of material and find the spatial distributions of certain chemicals within samples, e.g. cancer cells.(1) Not all aspects of coherent scattering have been used for imaging. Among those for example are special polarization sensitive measurements. Therefore we have investigated the properties of polarization sensitive CARS spectra of a highly fluorescent molecule, DCVJ.(2) Spectra has been recorded by using parallel polarized and perpendicular polarized excitations. A special polarization arrangement was developed to suppress the non-resonant background scattering from the sample. These results can be used to improve the imaging properties of a coherent Raman microscope in the future. This is the first time coherent Raman polarization sensitive measurements have been used to characterize the vibrational modes of DCVJ. 1: K. I. Gutkowski, et al., ``Fluorescence of dicyanovinyl julolidine in a room temperature ionic liquid '' Chemical Physics Letters 426 (2006) 329 - 333 2: Fouad El-Diasty, ``Coherent anti-Stokes Raman scattering: Spectroscopy and microscopy'' Vibrational Spectroscopy 55 (2011) 1-37

  19. Polarization Measurements in Neutral Pion Photoproduction

    SciTech Connect

    C. Jones; Krishni Wijesooriya; B. Fox; Andrei Afanasev; Moscov Amaryan; Konrad Aniol; Stephen Becher; Kamal Benslama; Louis Bimbot; Peter Bosted; Edward Brash; John Calarco; Zhengwei Chai; C. Chang; Ting Chang; Jian-Ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; Domenick Crovelli; Sonja Dieterich; Scott Dumalski; Dipangkar Dutta; Martin Epstein; Kevin Fissum; Salvatore Frullani; Haiyan Gao; Juncai Gao; Franco Garibaldi; Olivier Gayou; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Javier Gomez; Viktor Gorbenko; Ole Hansen; Roy Holt; Jordan Hovdebo; Garth Huber; Kees de Jager; Xiaodong Jiang; Mark Jones; Jim Kelly; Edward Kinney; Edgar Kooijman; Gerfried Kumbartzki; Michael Kuss; John LeRose; Meme Liang; Richard Lindgren; Nilanga Liyanage; Sergey Malov; Demetrius Margaziotis; Pete Markowitz; Kathy McCormick; Dave Meekins; Zein-Eddine Meziani; Robert Michaels; Joe Mitchell; Ludyvine Morand; Charles Perdrisat

    2002-09-26

    We present measurements of the recoil proton polarization for the {sup 1}H(gamma-vector,p-vector)pi{sup 0} reaction for theta{sub c.m.}{sup pi} = 60{sup o}-135{sup o} and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region.

  20. Remote Measurement of Shallow Media Depth Using Polarization Lidar

    NASA Astrophysics Data System (ADS)

    Mitchell, Steven E.

    Active noncontact range measurement sensors transmit electromagnetic radiation onto a remote target and process the received scattered signals to resolve the separation distance, or range, between the sensor and target. For lidar sensors, range is resolved by halving the roundtrip transit time multiplied by the speed of light, accounting for the refractive indices of the transit media. The ranging technique enables remote measurement of depth by resolving the range to sequential surfaces. Depth measurement in the shallow regime has conventionally been limited by the presence of ambiguous, overlapping optical pulses scattered from sequential surfaces. Enhanced performance in the shallow regime has conventionally come at the expense of the increased cost and complexity associated with high performance componentry. The issue of remote shallow depth measurement presents an opportunity for a novel approach to lidar sensor development. In this work, I discuss how the issue of ambiguity in the shallow depth measurement may be addressed by exploiting the polarization orientation of the transmitted and received optical signals, the components of which are modified during the range observation by naturally-occurring phenomena. Conventional pulsed time of flight laser ranging sensors are unable to resolve the shallow depth between overlapping pulses received from sequential surfaces due to operation in the scalar lidar regime, where the intensity of the received scattered signal is measured with no regard for polarization information. Enhanced performance by scalar lidar sensors in the shallow media regime has been conventionally enabled through incorporation of picosecond pulse width lasers and fast photodetectors, along with their associated increase in cost and complexity. The polarization lidar approach to shallow depth measurement developed in the dissertation facilitates the use of common lasers, optics, and detection componentry, making it comparatively less complex

  1. Polarization measurement of laser-accelerated protons

    SciTech Connect

    Raab, Natascha; Engels, Ralf; Engin, Ilhan; Greven, Patrick; Holler, Astrid; Lehrach, Andreas; Maier, Rudolf; Büscher, Markus; Cerchez, Mirela; Swantusch, Marco; Toncian, Monika; Toncian, Toma; Willi, Oswald; Gibbon, Paul; Karmakar, Anupam

    2014-02-15

    We report on the successful use of a laser-driven few-MeV proton source to measure the differential cross section of a hadronic scattering reaction as well as on the measurement and simulation study of polarization observables of the laser-accelerated charged particle beams. These investigations were carried out with thin foil targets, illuminated by 100 TW laser pulses at the Arcturus laser facility; the polarization measurement is based on the spin dependence of hadronic proton scattering off nuclei in a Silicon target. We find proton beam polarizations consistent with zero magnitude which indicates that for these particular laser-target parameters the particle spins are not aligned by the strong magnetic fields inside the laser-generated plasmas.

  2. When measured spin polarization is not spin polarization

    NASA Astrophysics Data System (ADS)

    Dowben, P. A.; Wu, Ning; Binek, Christian

    2011-05-01

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO2 and Cr2O3 illustrate some of the complications which hinders comparisons of spin polarization values.

  3. When measured spin polarization is not spin polarization.

    PubMed

    Dowben, P A; Wu, Ning; Binek, Christian

    2011-05-04

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO(2) and Cr(2)O(3) illustrate some of the complications which hinders comparisons of spin polarization values.

  4. POLRADS: polarization radiance distribution measurement system.

    PubMed

    Voss, Kenneth J; Souaidia, Nordine

    2010-09-13

    While the upwelling radiance distribution in the ocean can be highly polarized, there are few measurements of this parameter in the open ocean. To obtain the polarized in-water upwelling spectral radiance distribution data we have developed the POLRADS instrument. This instrument is based on the NuRADS radiance distribution camera systems in which linear polarizer's have been installed. By combining simultaneous images from three NuRADS instruments, three Stokes parameters (I, Q, U) for the water leaving radiance can be obtained for all upwelling angles simultaneously. This system measures the Stokes parameters Q/I and U/I with a 0.05-0.06 uncertainty and I with a 7-10% uncertainty.

  5. Concept of proton radiography using energy resolved dose measurement.

    PubMed

    Bentefour, El H; Schnuerer, Roland; Lu, Hsiao-Ming

    2016-08-21

    Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams 'proton imaging field' are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

  6. Concept of proton radiography using energy resolved dose measurement

    NASA Astrophysics Data System (ADS)

    Bentefour, El H.; Schnuerer, Roland; Lu, Hsiao-Ming

    2016-08-01

    Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams ‘proton imaging field’ are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

  7. New Measurements of CMB Polarization with SPTpol

    NASA Astrophysics Data System (ADS)

    Henning, Jason; SPTpol Collaboration

    2016-06-01

    All-sky surveys of the primary temperature anisotropies of the Cosmic Microwave Background (CMB) are now cosmic variance limited on large to intermediate scales. To place tighter constraints on cosmology from CMB primary anisotropies we turn to measurements of CMB polarization. Not only is polarization another probe of ΛCDM cosmology, but secondary anisotropies are expected to have low polarized emission, which opens more of the so-called CMB damping tail to cosmological study. In this talk, we present new 150 GHz measurements of the CMB E-mode polarization auto-power and temperature-E-mode cross-power spectra from a 500 deg2 patch of sky observed with the SPTpol instrument, the second-generation receiver installed on the South Pole Telescope. Over a range of spherical harmonic multipoles 50 ≤ l < 10000 we detect 9 acoustic peaks in the E-mode spectrum. With these spectra we constrain ΛCDM cosmology independently from temperature-only measurements, and present new joint constraints with the Planck temperature auto-power spectrum. The CMB is also gravitationally lensed by large-scale structure. We use our high-fidelity map of E-mode polarization, in conjunction with SPTpol maps of B-mode polarization and temperature, to map the lensing potential of the CMB and measure its corresponding power spectrum. Finally, the CMB lensing potential can be combined with our E-mode map to estimate lensing B modes present in our field, which can be delensed to improve constraints on primordial B modes and the energy scale of inflation through the tensor-to-scalar ratio, r.

  8. Polarization-resolved sensing with tilted fiber Bragg gratings: theory and limits of detection

    NASA Astrophysics Data System (ADS)

    Bialiayeu, Aliaksandr; Ianoul, Anatoli; Albert, Jacques

    2015-08-01

    Polarization based sensing with tilted fiber Bragg grating (TFBG) sensors is analysed theoretically by two alternative approaches. The first method is based on tracking the grating transmission for two orthogonal states of linear polarized light that are extracted from the measured Jones matrix or Stokes vectors of the TFBG transmission spectra. The second method is based on the measurements along the system principle axes and polarization dependent loss (PDL) parameter, also calculated from measured data. It is shown that the frequent crossing of the Jones matrix eigenvalues as a function of wavelength leads to a non-physical interchange of the calculated principal axes; a method to remove this unwanted mathematical artefact and to restore the order of the system eigenvalues and the corresponding principal axes is provided. A comparison of the two approaches reveals that the PDL method provides a smaller standard deviation and therefore lower limit of detection in refractometric sensing. Furthermore, the polarization analysis of the measured spectra allows for the identification of the principal states of polarization of the sensor system and consequentially for the calculation of the transmission spectrum for any incident polarization state. The stability of the orientation of the system principal axes is also investigated as a function of wavelength.

  9. Spin-orbit-induced photoelectron spin polarization in angle-resolved photoemission from both atomic and condensed matter targets.

    PubMed

    Heinzmann, Ulrich; Dil, J Hugo

    2012-05-02

    The existence of highly spin polarized photoelectrons emitted from non-magnetic solids as well as from unpolarized atoms and molecules has been found to be very common in many studies over the past 40 years. This so-called Fano effect is based upon the influence of the spin-orbit interaction in the photoionization or the photoemission process. In a non-angle-resolved photoemission experiment, circularly polarized radiation has to be used to create spin polarized photoelectrons, while in angle-resolved photoemission even unpolarized or linearly polarized radiation is sufficient to get a high spin polarization. In past years the Rashba effect has become very important in the angle-resolved photoemission of solid surfaces, also with an observed high photoelectron spin polarization. It is the purpose of the present topical review to cross-compare the spin polarization experimentally found in angle-resolved photoelectron emission spectroscopy of condensed matter with that of free atoms, to compare it with the Rashba effect and topological insulators to describe the influence and the importance of the spin-orbit interaction and to show and disentangle the matrix element and phase shift effects therein.The relationship between the energy dispersion of these phase shifts and the emission delay of photoelectron emission in attosecond-resolved photoemission is also discussed. Furthermore the influence of chiral structures of the photo-effect target on the spin polarization, the interferences of different spin components in coherent superpositions in photoemission and a cross-comparison of spin polarization in photoemission from non-magnetic solids with XMCD on magnetic materials are presented; these are all based upon the influence of the spin-orbit interaction in angle-resolved photoemission.

  10. Data Analysis And Polarization Measurements With GEMS

    NASA Technical Reports Server (NTRS)

    Stohmayer, Tod

    2011-01-01

    The Gravity and Extreme Magnetism SMEX (GEMS) mission was selected by NASA for flight in 2014. GEMS will make the first sensitive survey of X-ray polarization across a wide range of source classes including black hole and neutron star binaries, AGN of different types, rotation and accretion-powered pulsars, magnetars, shell supernova remnants and pulsar wind nebulae. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect. The GEMS detectors image the charge tracks of photoelectrons produced by 2 - 10 keV X-rays. The initial direction of the photoelectron is determined by the linear polarization of the photon. We present an overview of the data analysis challenges and methods for GEMS, including procedures for producing optimally filtered images of the charge tracks and estimating their initial directions. We illustrate our methods using laboratory measurements of polarized and unpolarized X-rays with flight-like detectors as well as from simulated tracks. We also present detailed simulations exploring the statistics of polarization measurements appropriate for GEMS, and make comparisons with previous work.

  11. Optical diagnosis and characterization of dental caries with polarization-resolved hyperspectral stimulated Raman scattering microscopy

    PubMed Central

    Wang, Zi; Zheng, Wei; Hsu, Stephen Chin-Ying; Huang, Zhiwei

    2016-01-01

    We report the utility of a rapid polarization-resolved hyperspectral stimulated Raman scattering (SRS) imaging technique developed for optical diagnosis and characterization of dental caries in the tooth. Hyperspectral SRS images (512 × 512 pixels) of the tooth covering both the fingerprint (800-1800 cm−1) and high-wavenumber (2800-3600 cm−1) regions can be acquired within 15 minutes, which is at least 103 faster in imaging speed than confocal Raman mapping. Hyperspectral SRS imaging uncovers the biochemical distributions and variations across the carious enamel in the tooth. SRS imaging shows that compared to the sound enamel, the mineral content in the body of lesion decreases by 55%; while increasing up to 110% in the surface zone, indicating the formation of a hyper-mineralized layer due to the remineralization process. Further polarized SRS imaging shows that the depolarization ratios of hydroxyapatite crystals (ν1-PO43- of SRS at 959 cm−1) of the tooth in the sound enamel, translucent zone, body of lesion and the surface zone are 0.035 ± 0.01, 0.052 ± 0.02, 0.314 ± 0.1, 0.038 ± 0.02, respectively, providing a new diagnostic criterion for discriminating carious lesions from sound enamel in the teeth. This work demonstrates for the first time that the polarization-resolved hyperspectral SRS imaging technique can be used for quantitatively determining tooth mineralization levels and discriminating carious lesions from sound enamel in a rapid fashion, proving its promising potential of early detection and diagnosis of dental caries without labeling. PMID:27446654

  12. Electronic structure of the topological insulator Bi2Se3 using angle-resolved photoemission spectroscopy: evidence for a nearly full surface spin polarization.

    PubMed

    Pan, Z-H; Vescovo, E; Fedorov, A V; Gardner, D; Lee, Y S; Chu, S; Gu, G D; Valla, T

    2011-06-24

    We performed high-resolution spin- and angle-resolved photoemission spectroscopy studies of the electronic structure and the spin texture on the surface of Bi2Se3, a model TI. By tuning the photon energy, we found that the topological surface state is well separated from the bulk states in the vicinity of kz = Z plane of the bulk Brillouin zone. The spin-resolved measurements in that region indicate a very high degree of spin polarization of the surface state, ~0.75, much higher than previously reported. Our results demonstrate that the topological surface state on Bi2Se3 is highly spin polarized and that the dominant factors limiting the polarization are mainly extrinsic.

  13. Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization

    SciTech Connect

    Pan, Z.H.; Vescovo, E.; Fedorov, A.V.; Gardner, D.; Lee, Y.S.; Chu, S.; Gu, G.D.; Valla, T.

    2011-06-22

    We performed high-resolution spin- and angle-resolved photoemission spectroscopy studies of the electronic structure and the spin texture on the surface of Bi{sub 2}Se{sub 3}, a model TI. By tuning the photon energy, we found that the topological surface state is well separated from the bulk states in the vicinity of k{sub z} = Z plane of the bulk Brillouin zone. The spin-resolved measurements in that region indicate a very high degree of spin polarization of the surface state, {approx}0.75, much higher than previously reported. Our results demonstrate that the topological surface state on Bi{sub 2}Se{sub 3} is highly spin polarized and that the dominant factors limiting the polarization are mainly extrinsic.

  14. Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization

    SciTech Connect

    Z Pan; E Vescovo; A Fedorov; D Gardner; Y Lee; S Chu; G Gu; T Valla

    2011-12-31

    We performed high-resolution spin- and angle-resolved photoemission spectroscopy studies of the electronic structure and the spin texture on the surface of Bi{sub 2}Se{sub 3}, a model TI. By tuning the photon energy, we found that the topological surface state is well separated from the bulk states in the vicinity of k{sub z} = Z plane of the bulk Brillouin zone. The spin-resolved measurements in that region indicate a very high degree of spin polarization of the surface state, {approx}0.75, much higher than previously reported. Our results demonstrate that the topological surface state on Bi{sub 2}Se{sub 3} is highly spin polarized and that the dominant factors limiting the polarization are mainly extrinsic.

  15. Two-Dimensional Subpicosecond Time-Resolved Fluorescence Anisotropy: Optical Kerr-Gating with a Dynamic Polarization Excitation.

    NASA Astrophysics Data System (ADS)

    Fujiwara, Takashige; Romano, Natalie C.; Modarelli, David A.; Lim, Edward C.

    2013-06-01

    With an advent of ultrafast lasers, a number of applications are widely adopted to probe photophysical and photochemical properties of a molecule that occurs in an ultrafast (femtosecond to picosecond) time scale. Intramolecular charge transfer (ICT) or proton transfer in photoexcited electron donor-acceptor (EDA) molecules, for instance, has been a topic of very extensive time-resolved studies for several decades. Time-evolution of an anisotropic property can track dipole orientations or conformational changes in their photoexcited molecular systems, which is of extreme importance to examine its structure and excited-state dynamics rather than probing an isotropic "population change".With this respect, we recently developed a subpicosecond time-resolved 2-D fluorescence anisotropy (TRFA) in which method implements a dynamic alternation of laser polarizations to excite a sample using a photoelastic modulator (PEM). In the combination of an ultrafast optical shutter (Kerr-gating) and a spectrograph that is coupled with a CCD, two signal phases so-obtained dynamically, I_{∥}( t, λ) and I_{⊥}( t, λ), provide a 2-D mapped information on both a wide range for spectra and time-resolved kinetics of photoexcited molecules of interest. From the definition of an anisotropy 2-D TRFA, r (t, λ), is given instantly and even more reliably at a single measurement. In this paper we will present benchmark tests of some target samples to establish performance of TRFA.

  16. GRB Polarization Measurements with CGRO/COMPTEL

    NASA Astrophysics Data System (ADS)

    McConnell, Mark L.; Collmar, Werner

    2016-04-01

    We have embarked on a program to analyze CGRO/COMPTEL data in search for evidence of polarization in both transient sources and in brighter steady sources. We are pursuing this work because of the heightened interest in high energy polarimetry, the recognition that some high energy sources may be highly polarized (thus improving our chances of a making useful measurements), and the ready availability of modern computing resources that provide the ability to carry out more comprehensive simulations in support of the analysis. The only significant work done to date with regards to COMPTEL polarimetry was published almost 20 years ago and used a simplified mass model of COMPTEL for simulating the instrument response. Estimates of the minimum detectable polarization (MDP) near 1 MeV included 30% for a two-week observation of the Crab, as low as 10% for bright GRBs, and as low as 10% for bright solar flares. The data analysis performed at the time led to inconclusive results and suggested some unknown systematic error. We contend that a self-consistent analysis will be feasible with high fidelity simulations, simulations that were not easily generated 20 years ago. Our analysis utilizes the latest GEANT4 simulation tools in conjunction with a high-fidelity mass model of the COMPTEL instrument, and incorporate updated analysis tools originally developed by the COMPTEL collaboration. Given the nine years of COMPTEL data, we expect that this work will likely add to our understanding of the polarization properties of transient sources, such as GRBs and solar flares, as well as brighter steady sources, such as the Crab and Cyg X-1. Here we present results from simulations of the COMPTEL polarization response and examine prospects for studying GRB polarization.

  17. Polarization Lidar for Shallow Water Supraglacial Lake Depth Measurement

    NASA Astrophysics Data System (ADS)

    Mitchell, S.; Adler, J.; Thayer, J. P.; Hayman, M.

    2010-12-01

    A bathymetric, polarization lidar system transmitting at 532 nanometers and using a single photomultiplier tube is developed for applications of shallow water depth measurement, in particular those often found in supraglacial lakes of the ablation zone on the Greenland Ice Sheet. The technique exploits polarization attributes of the probed water body to isolate surface and floor returns, enabling constant fraction detection schemes to determine depth. The minimum resolvable water depth is no longer dictated by the system’s laser or detector pulse width and can achieve better than an order of magnitude improvement over current water depth determination techniques. In laboratory tests, a Nd:YAG microchip laser coupled with polarization optics, a photomultiplier tube, a constant fraction discriminator and a time to digital converter are used to target various water depths, using ice as the floor to simulate a supraglacial lake. Measurement of 1 centimeter water depths with an uncertainty of ±3 millimeters are demonstrated using the technique. This novel technique enables new approaches to designing laser bathymetry systems for shallow depth determination from remote platforms while not compromising deep water depth measurement, and will support comprehensive hydrodynamic studies of supraglacial lakes. Additionally, the compact size and low weight (<15 kg) of the field system currently in development presents opportunities for use in small unmanned aircraft systems (UAS) for large areal surveys of the ablation zone.

  18. Vectorial spin polarization detection in multichannel spin-resolved photoemission spectroscopy using an Ir(001) imaging spin filter

    NASA Astrophysics Data System (ADS)

    Schaefer, Erik D.; Borek, Stephan; Braun, Jürgen; Minár, Ján; Ebert, Hubert; Medjanik, Katerina; Kutnyakhov, Dmytro; Schönhense, Gerd; Elmers, Hans-Joachim

    2017-03-01

    We report on spin- and angular-resolved photoemission spectroscopy using a high-resolution imaging spin filter based on a large Ir(001) crystal enhancing the effective figure of merit for spin detection by a factor of over 103 compared to standard single-channel detectors. Furthermore, we review the spin filter preparation and its lifetime. The spin filter efficiency is mapped on a broad range of scattering energies and azimuthal angles. Large spin filter efficiencies are observed for the spin component perpendicular as well as parallel to the scattering plane depending on the azimuthal orientation of the spin filter crystal. A spin rotator capable of manipulating the spin direction prior to detection complements the measurement of three observables, thus allowing for a derivation of all three components of the spin polarization vector in multichannel spin polarimetry. The experimental results nicely agree with spin-polarized low-energy electron diffraction calculations based on a fully relativistic multiple scattering method in the framework of spin-polarized density functional theory.

  19. Polarization-resolved SHG microscopy in cardiac hypertrophy study (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Zhonghai; Yuan, Cai; Shao, Yonghong; Bradshaw, Amy D.; Borg, Thomas K.; Gao, Bruce Z.

    2017-02-01

    Cardiac hypertrophy, a process initiated by mechanical alterations, is hypothesized to cause long-term molecular-level alteration in the sarcomere lattice, which is the main force-generating component in the heart muscle. This molecular-level alteration is beyond the resolving capacity of common light microscopy. Second harmonic generation (SHG) microscopy has unique capability for visualizing ordered molecular structures in biological tissues without labeling. Combined with polarization imaging technique, SHG microscopy is able to extract structural details of myosin at the molecular level so as to reveal molecular-level alterations that occur during hypertrophy. The myosin filaments are believed to possess C6 symmetry; thus, the nonlinear polarization response relationship between generated second harmonic light I^2ωand incident fundamental light I^ω is determined by nonlinear coefficients, χ_15, χ_31 and χ_33. χ_31/χ_15 is believed to be an indicator of the molecular symmetry of myosin filament, whileχ_33/χ_15represents the intramyosin orientation angle of the double helix. By changing the polarization of the incident light and evaluating the corresponding SHG signals, the molecular structure of the myosin, reflected by the χ coefficients, can be revealed. With this method, we studied the structural properties of heart tissues in different conditions, including those in normal, physiologically hypertrophic (heart tissue from postpartum female rats), and pathologically hypertrophic (heart tissue from transverse-aorta constricted rats) conditions. We found that ratios of χ_31/χ_15 showed no significant difference between heart tissues from different conditions; their values were all close to 1, which demonstrated that Kleinman symmetry held for all conditions. Ratios of χ_33/χ_15 from physiologically or pathologically hypertrophic heart tissues were raised and showed significant difference from those from normal heart tissues, which indicated that

  20. Motion-artifact-robust, polarization-resolved second-harmonic-generation microscopy based on rapid polarization switching with electro-optic Pockells cell and its application to in vivo visualization of collagen fiber orientation in human facial skin.

    PubMed

    Tanaka, Yuji; Hase, Eiji; Fukushima, Shuichiro; Ogura, Yuki; Yamashita, Toyonobu; Hirao, Tetsuji; Araki, Tsutomu; Yasui, Takeshi

    2014-04-01

    Polarization-resolved second-harmonic-generation (PR-SHG) microscopy is a powerful tool for investigating collagen fiber orientation quantitatively with low invasiveness. However, the waiting time for the mechanical polarization rotation makes it too sensitive to motion artifacts and hence has hampered its use in various applications in vivo. In the work described in this article, we constructed a motion-artifact-robust, PR-SHG microscope based on rapid polarization switching at every pixel with an electro-optic Pockells cell (PC) in synchronization with step-wise raster scanning of the focus spot and alternate data acquisition of a vertical-polarization-resolved SHG signal and a horizontal-polarization-resolved one. The constructed PC-based PR-SHG microscope enabled us to visualize orientation mapping of dermal collagen fiber in human facial skin in vivo without the influence of motion artifacts. Furthermore, it implied the location and/or age dependence of the collagen fiber orientation in human facial skin. The robustness to motion artifacts in the collagen orientation measurement will expand the application scope of SHG microscopy in dermatology and collagen-related fields.

  1. Motion-artifact-robust, polarization-resolved second-harmonic-generation microscopy based on rapid polarization switching with electro-optic Pockells cell and its application to in vivo visualization of collagen fiber orientation in human facial skin

    PubMed Central

    Tanaka, Yuji; Hase, Eiji; Fukushima, Shuichiro; Ogura, Yuki; Yamashita, Toyonobu; Hirao, Tetsuji; Araki, Tsutomu; Yasui, Takeshi

    2014-01-01

    Polarization-resolved second-harmonic-generation (PR-SHG) microscopy is a powerful tool for investigating collagen fiber orientation quantitatively with low invasiveness. However, the waiting time for the mechanical polarization rotation makes it too sensitive to motion artifacts and hence has hampered its use in various applications in vivo. In the work described in this article, we constructed a motion-artifact-robust, PR-SHG microscope based on rapid polarization switching at every pixel with an electro-optic Pockells cell (PC) in synchronization with step-wise raster scanning of the focus spot and alternate data acquisition of a vertical-polarization-resolved SHG signal and a horizontal-polarization-resolved one. The constructed PC-based PR-SHG microscope enabled us to visualize orientation mapping of dermal collagen fiber in human facial skin in vivo without the influence of motion artifacts. Furthermore, it implied the location and/or age dependence of the collagen fiber orientation in human facial skin. The robustness to motion artifacts in the collagen orientation measurement will expand the application scope of SHG microscopy in dermatology and collagen-related fields. PMID:24761292

  2. Phase effects due to previous pulses in time-resolved Faraday rotation measurements

    SciTech Connect

    Trowbridge, Christopher J.; Sih, Vanessa

    2015-02-14

    Time-resolved Faraday rotation measurements have proved transformative in the investigation of spin dynamics in semiconductors. In materials with spin lifetimes which are on the order of, or greater than, the laser repetition time, the collective effect of spin polarization due to the whole pump pulse train becomes important. Here, we discuss a relative phase shift which results from these spins. We derive and experimentally validate a closed-form expression which describes this phase shift and characterize it throughout parameter space. A spin lifetime measurement based on this phase shift is described, and we discuss situations in which the model used must be augmented to be applicable.

  3. Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen

    2008-01-01

    A molecular Rayleigh scattering technique is developed to measure time-resolved gas velocity, temperature, and density in unseeded gas flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultipler tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. Mean and rms velocity and temperature fluctuation measurements in both an electrically-heated jet facility with a 10-mm diameter nozzle and also in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA Glenn Research Center are presented.

  4. Identification of stacking faults in silicon carbide by polarization-resolved second harmonic generation microscopy.

    PubMed

    Hristu, Radu; Stanciu, Stefan G; Tranca, Denis E; Polychroniadis, Efstathios K; Stanciu, George A

    2017-07-07

    Although silicon carbide is a highly promising crystalline material for a wide range of electronic devices, extended and point defects which perturb the lattice periodicity hold deep implications with respect to device reliability. There is thus a great need for developing new methods that can detect silicon carbide defects which are detrimental to device functionality. Our experiment demonstrates that polarization-resolved second harmonic generation microscopy can extend the efficiency of the "optical signature" concept as an all-optical rapid and non-destructive set of investigation methods for the differentiation between hexagonal and cubic stacking faults in silicon carbide. This technique can be used for fast and in situ characterization and optimization of growth conditions for epilayers of silicon carbide and similar materials.

  5. Polarization-resolved second-harmonic generation imaging for liver fibrosis assessment without labeling

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Pan, Shiying; Zheng, Wei; Huang, Zhiwei

    2013-10-01

    We apply the polarization-resolved second-harmonic generation (PR-SHG) microscopy to investigate the changes of collagen typings (type I vs type III) and collagen fibril orientations of liver tissue in bile-duct-ligation (BDL) rat models. The PR-SHG results show that the second-order susceptibility tensor ratios (χ31/χ15 and χ33/χ15) of collagen fibers increase with liver fibrotic progression after BDL surgery, reflecting an increase of the type III collagen component with the severity of liver fibrosis; and the square root of the collagen type III to type I ratio linearly correlates (R2 = 0.98) with histopathological scores. Furthermore, the collagen fibril orientations become more random with liver fibrosis transformation as compared to normal liver tissue. This work demonstrates that PR-SHG microscopy has the potential for label-free diagnosis and characterization of liver fibrosis based on quantitative analysis of collagen typings and fibril orientations.

  6. Polarization bispectrum for measuring primordial magnetic fields

    SciTech Connect

    Shiraishi, Maresuke

    2013-11-01

    We examine the potential of polarization bispectra of the cosmic microwave background (CMB) to constrain primordial magnetic fields (PMFs). We compute all possible bispectra between temperature and polarization anisotropies sourced by PMFs and show that they are weakly correlated with well-known local-type and secondary ISW-lensing bispectra. From a Fisher analysis it is found that, owing to E-mode bispectra, in a cosmic-variance-limited experiment the expected uncertainty in the amplitude of magnetized bispectra is 80% improved in comparison with an analysis in terms of temperature auto-bispectrum alone. In the Planck or the proposed PRISM experiment cases, we will be able to measure PMFs with strength 2.6 or 2.2 nG. PMFs also generate bispectra involving B-mode polarization, due to tensor-mode dependence. We also find that the B-mode bispectrum can reduce the uncertainty more drastically and hence PMFs comparable to or less than 1 nG may be measured in a PRISM-like experiment.

  7. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, C.; Steinkamp, J.A.

    1999-06-01

    Time-resolved fluorescence decay measurements are disclosed for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated CW laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes. 12 figs.

  8. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, Chiranjit; Steinkamp, John A.

    1999-01-01

    Time-resolved fluorescence decay measurements for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated cw laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes.

  9. Resolving the biophysics of axon transmembrane polarization in a single closed-form description

    SciTech Connect

    Melendy, Robert F.

    2015-12-28

    When a depolarizing event occurs across a cell membrane there is a remarkable change in its electrical properties. A complete depolarization event produces a considerably rapid increase in voltage that propagates longitudinally along the axon and is accompanied by changes in axial conductance. A dynamically changing magnetic field is associated with the passage of the action potential down the axon. Over 75 years of research has gone into the quantification of this phenomenon. To date, no unified model exist that resolves transmembrane polarization in a closed-form description. Here, a simple but formative description of propagated signaling phenomena in the membrane of an axon is presented in closed-form. The focus is on using both biophysics and mathematical methods for elucidating the fundamental mechanisms governing transmembrane polarization. The results presented demonstrate how to resolve electromagnetic and thermodynamic factors that govern transmembrane potential. Computational results are supported by well-established quantitative descriptions of propagated signaling phenomena in the membrane of an axon. The findings demonstrate how intracellular conductance, the thermodynamics of magnetization, and current modulation function together in generating an action potential in a unified closed-form description. The work presented in this paper provides compelling evidence that three basic factors contribute to the propagated signaling in the membrane of an axon. It is anticipated this work will compel those in biophysics, physical biology, and in the computational neurosciences to probe deeper into the classical and quantum features of membrane magnetization and signaling. It is hoped that subsequent investigations of this sort will be advanced by the computational features of this model without having to resort to numerical methods of analysis.

  10. Resolving the biophysics of axon transmembrane polarization in a single closed-form description

    NASA Astrophysics Data System (ADS)

    Melendy, Robert F.

    2015-12-01

    When a depolarizing event occurs across a cell membrane there is a remarkable change in its electrical properties. A complete depolarization event produces a considerably rapid increase in voltage that propagates longitudinally along the axon and is accompanied by changes in axial conductance. A dynamically changing magnetic field is associated with the passage of the action potential down the axon. Over 75 years of research has gone into the quantification of this phenomenon. To date, no unified model exist that resolves transmembrane polarization in a closed-form description. Here, a simple but formative description of propagated signaling phenomena in the membrane of an axon is presented in closed-form. The focus is on using both biophysics and mathematical methods for elucidating the fundamental mechanisms governing transmembrane polarization. The results presented demonstrate how to resolve electromagnetic and thermodynamic factors that govern transmembrane potential. Computational results are supported by well-established quantitative descriptions of propagated signaling phenomena in the membrane of an axon. The findings demonstrate how intracellular conductance, the thermodynamics of magnetization, and current modulation function together in generating an action potential in a unified closed-form description. The work presented in this paper provides compelling evidence that three basic factors contribute to the propagated signaling in the membrane of an axon. It is anticipated this work will compel those in biophysics, physical biology, and in the computational neurosciences to probe deeper into the classical and quantum features of membrane magnetization and signaling. It is hoped that subsequent investigations of this sort will be advanced by the computational features of this model without having to resort to numerical methods of analysis.

  11. Retinal pigment epithelium pathologies investigated with phase resolved polarization sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Pircher, M.; Goetzinger, E.; Findl, O.; Michels, S.; Geitzenauer, W.; Schmidt-Erfurth, U.; Hitzenberger, C. K.

    2006-02-01

    A polarization sensitive optical coherence tomography (PS-OCT) instrument was used to investigate the retinal pigment epithelium (RPE). The instrument uses the polarization properties of light to record backscattered intensity, retardation and fast axis orientation simultaneously and needs only one measurement per sample location to retrieve these parameters. The polarization state of light backscattered from within the RPE was found to be random. This can be observed in PS-OCT images by random retardation and axis orientation values within the RPE layer. In diseased eyes where the normal retinal structure is corrupted (e.g. RPE atrophy, RPE detachment) the localization of the RPE within OCT images which do not provide polarization information (standard OCT) is rather difficult. Since the RPE is the only structure within the retina to cause this polarization scrambling, PS-OCT can be used for contrast enhancement and enables the exact localization of the RPE in these pathologies. Therefore it is possible to determine if the RPE is still preserved in regions of interest. Furthermore, in patients with RPE atrophy an enhanced penetration depth into the choroid and even into the sclera was observed. Because of birefringence introduced by the sclera the border between choroid and sclera could easily be determined.

  12. Measurement of skin texture through polarization imaging.

    PubMed

    Bargo, P R; Kollias, N

    2010-04-01

    Determination of skin surface texture is of particular importance in the field of dermatology as such measurements can be used for skin diagnostics and evaluation of therapeutic or cosmetic treatments. Profilometry of skin replicas, three-dimensional imaging and computer vision have been successfully used to measure and document skin texture. Nevertheless, the development of a simpler and faster technique may prove to be advantageous in a clinical setting. We propose the use of polarization imaging with high angles of incidence as a simple alternative to measure/document skin texture/roughness. A system based on digital photography and polarization optics was developed to acquire and compute texture images. Optimization of the system configuration was conducted to enhance the contrast for measuring skin roughness. The method was validated against roughness standards and tested in clinical studies. Measurements were made in subjects aged from 9 to 70 years and image analysis was used to evaluate texture. The developed texture scale was shown to correlate closely to the results from clinical assessment and from roughness standards. Frequency domain analysis showed a significantly different power spectrum for the texture images of young subjects when compared with older subjects. The evaluation of texture as a function of age showed that facial skin roughness increased linearly from teenage to 40 years followed by a plateau thereafter. The system proved to be a useful clinical tool for assessing skin texture. The age-related results may indicate that some skin texture features are formed before the age of 40 years.

  13. Resolving and measuring diffusion in complex interfaces: Exploring new capabilities

    SciTech Connect

    Alam, Todd M.

    2015-09-01

    This exploratory LDRD targeted the use of a new high resolution spectroscopic diffusion capabilities developed at Sandia to resolve transport processes at interfaces in heterogeneous polymer materials. In particular, the combination of high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradient (PFG) diffusion experiments were used to directly explore interface diffusion within heterogeneous polymer composites, including measuring diffusion for individual chemical species in multi-component mixtures. Several different types of heterogeneous polymer systems were studied using these HRMAS NMR diffusion capabilities to probe the resolution limitations, determine the spatial length scales involved, and explore the general applicability to specific heterogeneous systems. The investigations pursued included a) the direct measurement of the diffusion for poly(dimethyl siloxane) polymer (PDMS) on nano-porous materials, b) measurement of penetrant diffusion in additive manufactures (3D printed) processed PDMS composites, and c) the measurement of diffusion in swollen polymers/penetrant mixtures within nano-confined aluminum oxide membranes. The NMR diffusion results obtained were encouraging and allowed for an improved understanding of diffusion and transport processes at the molecular level, while at the same time demonstrating that the spatial heterogeneity that can be resolved using HRMAS NMR PFG diffusion experiment must be larger than ~μm length scales, expect for polymer transport within nanoporous carbons where additional chemical resolution improves the resolvable heterogeneous length scale to hundreds of nm.

  14. Study of Microheterogeneity in Acetonitrile-Water Binary Mixtures by using Polarity-Resolved Solvation Dynamics.

    PubMed

    Koley, Somnath; Ghosh, Subhadip

    2015-11-16

    The solvation dynamics of three coumarin dyes with widely varying polarities were studied in acetonitrile-water (ACN-H2O) mixtures across the entire composition range. At low ACN concentrations [ACN mole fractions (X(ACN))≤0.1], the solvation dynamics are fast (<40 ps), indicating a nearly homogeneous environment. This fast region is followed by a sudden retardation of the average solvation time (230-1120 ps) at higher ACN concentrations (X(ACN)≈0.2), thus indicating the onset of nonideality within the mixture that continues until X(ACN)≈0.8. This nonideality regime (X(ACN)≈0.2-0.8) comprises of multiple dye-dependent anomalous regions. At very high ACN concentrations (X(ACN)≈0.8-1), the ACN-H2O mixtures regain homogeneity, with faster solvation times. The source of the inherent nonideality of the ACN-H2O mixtures is a subject of debate. However, a careful examination of the widths of time-resolved emission spectra shows that the origin of the slow dynamics may be due to the diffusion of polar solvent molecules into the first solvation shell of the excited coumarin dipole.

  15. Moisture-insensitive optical fingerprint scanner based on polarization resolved in-finger scattered light.

    PubMed

    Back, Seon-Woo; Lee, Yong-Geon; Lee, Sang-Shin; Son, Geun-Sik

    2016-08-22

    A moisture-insensitive optical fingerprint scanner (FPS) that is based on polarization resolved in-finger light is proposed and realized. Incident visible light, which is selectively fed to a fingerprint sample via a polarization beam splitter (PBS), is deemed to be partially scattered backward by tissues associated with the skin of the finger. The backscattered light is mostly index-guided in the ridge comprising the fingerprint, which has a higher refractive index, and is drastically dispersed in the valley, which is typically filled with water or air and so has a lower index. However, when light reflects directly off the surface of the finger skin, it fundamentally prevents the scanned image from being determined. The proposed FPS produces bright and dark intensity patterns that are alternately created on the surface of the PBS and correspond to the ridges and valleys, respectively. Thus, this method can especially distinguish between a fake synthetic fingerprint and a genuine fingerprint due to its use of in-finger scattered light. The scanner has been rigorously designed by carrying out ray-optic simulations depending on the wavelength, with tissue-induced scattering taken into account. The device was constructed by incorporating a wire-grid type PBS in conjunction with visible LED sources, including blue, green and red. The scanner adopting a blue LED, which exhibits the strongest light scattering, resulted in the best fingerprint image, enabling enhanced fidelity under the wet and dry situations. Finally, a fake synthetic fingerprint could be successfully discriminated.

  16. Performance of Orbital Neutron Instruments for Spatially Resolved Hydrogen Measurements of Airless Planetary Bodies

    PubMed Central

    Elphic, Richard C.; Feldman, William C.; Funsten, Herbert O.; Prettyman, Thomas H.

    2010-01-01

    Abstract Orbital neutron spectroscopy has become a standard technique for measuring planetary surface compositions from orbit. While this technique has led to important discoveries, such as the deposits of hydrogen at the Moon and Mars, a limitation is its poor spatial resolution. For omni-directional neutron sensors, spatial resolutions are 1–1.5 times the spacecraft's altitude above the planetary surface (or 40–600 km for typical orbital altitudes). Neutron sensors with enhanced spatial resolution have been proposed, and one with a collimated field of view is scheduled to fly on a mission to measure lunar polar hydrogen. No quantitative studies or analyses have been published that evaluate in detail the detection and sensitivity limits of spatially resolved neutron measurements. Here, we describe two complementary techniques for evaluating the hydrogen sensitivity of spatially resolved neutron sensors: an analytic, closed-form expression that has been validated with Lunar Prospector neutron data, and a three-dimensional modeling technique. The analytic technique, called the Spatially resolved Neutron Analytic Sensitivity Approximation (SNASA), provides a straightforward method to evaluate spatially resolved neutron data from existing instruments as well as to plan for future mission scenarios. We conclude that the existing detector—the Lunar Exploration Neutron Detector (LEND)—scheduled to launch on the Lunar Reconnaissance Orbiter will have hydrogen sensitivities that are over an order of magnitude poorer than previously estimated. We further conclude that a sensor with a geometric factor of ∼ 100 cm2 Sr (compared to the LEND geometric factor of ∼ 10.9 cm2 Sr) could make substantially improved measurements of the lunar polar hydrogen spatial distribution. Key Words: Planetary instrumentation—Planetary science—Moon—Spacecraft experiments—Hydrogen. Astrobiology 10, 183–200. PMID:20298147

  17. Performance of orbital neutron instruments for spatially resolved hydrogen measurements of airless planetary bodies.

    PubMed

    Lawrence, David J; Elphic, Richard C; Feldman, William C; Funsten, Herbert O; Prettyman, Thomas H

    2010-03-01

    Orbital neutron spectroscopy has become a standard technique for measuring planetary surface compositions from orbit. While this technique has led to important discoveries, such as the deposits of hydrogen at the Moon and Mars, a limitation is its poor spatial resolution. For omni-directional neutron sensors, spatial resolutions are 1-1.5 times the spacecraft's altitude above the planetary surface (or 40-600 km for typical orbital altitudes). Neutron sensors with enhanced spatial resolution have been proposed, and one with a collimated field of view is scheduled to fly on a mission to measure lunar polar hydrogen. No quantitative studies or analyses have been published that evaluate in detail the detection and sensitivity limits of spatially resolved neutron measurements. Here, we describe two complementary techniques for evaluating the hydrogen sensitivity of spatially resolved neutron sensors: an analytic, closed-form expression that has been validated with Lunar Prospector neutron data, and a three-dimensional modeling technique. The analytic technique, called the Spatially resolved Neutron Analytic Sensitivity Approximation (SNASA), provides a straightforward method to evaluate spatially resolved neutron data from existing instruments as well as to plan for future mission scenarios. We conclude that the existing detector--the Lunar Exploration Neutron Detector (LEND)--scheduled to launch on the Lunar Reconnaissance Orbiter will have hydrogen sensitivities that are over an order of magnitude poorer than previously estimated. We further conclude that a sensor with a geometric factor of approximately 100 cm(2) Sr (compared to the LEND geometric factor of approximately 10.9 cm(2) Sr) could make substantially improved measurements of the lunar polar hydrogen spatial distribution.

  18. Improving Earthquake Stress Drop Measurements - What can we Really Resolve?

    NASA Astrophysics Data System (ADS)

    Abercrombie, R. E.; Bannister, S. C.; Fry, B.; Ruhl, C. J.; Kozlowska, M.

    2015-12-01

    Earthquake stress drop is fundamental to understanding the physics of the rupture process. Although it is superficially simple to calculate an estimate of stress drop from the corner frequency of the radiated spectrum, it is much harder to be certain that measurements are reliable and accurate. The same is true of other measurements of stress drop and radiated energy. The large number of studies of earthquake stress drop, the high variability in results (~0.1-100 MPa), the large uncertainties, and the ongoing scaling controversy are evidence for this. We investigate the resolution and uncertainties of stress drops calculated using an empirical Green's function (EGF) approach. Earthquakes in 3 sequences at Parkfield, California are recorded by multiple borehole stations and have abundant smaller earthquakes to use as EGFs (Abercrombie, 2014). The earthquakes in the largest magnitude cluster (M~2.1) exhibit clear temporal variation of stress drop. Independent studies obtained a similar pattern implying that it is resolvable for these well-recorded, simple sources. The borehole data reveal a similar temporal pattern for another sequence, not resolvable in an earlier study using surface recordings. The earthquakes in the third sequence have complex sources; corner frequency measurements for this sequence are highly variable and poorly resolved. We use the earthquakes in the first cluster to quantify the uncertainties likely to arise in less optimal settings. The limited signal bandwidth and the quality of the EGF assumption are major sources of error. Averaging across multiple stations improves the resolution, as does using multiple good EGFs (Abercrombie, 2015). We adapt the approach to apply to larger data sets. We focus on New Zealand, with the aim of resolving stress drop variability in a variety of tectonic settings. We investigate stacking over stations and multiple EGFs, and compare earthquakes (M~3-6) from both the overlying and the subducting plates.

  19. Measuring receptor recycling in polarized MDCK cells.

    PubMed

    Gallo, Luciana; Apodaca, Gerard

    2015-01-01

    Recycling of proteins such as channels, pumps, and receptors is critical for epithelial cell function. In this chapter we present a method to measure receptor recycling in polarized Madin-Darby canine kidney cells using an iodinated ligand. We describe a technique to iodinate transferrin (Tf), we discuss how (125)I-Tf can be used to label a cohort of endocytosed Tf receptor, and then we provide methods to measure the rate of recycling of the (125)I-Tf-receptor complex. We also show how this approach, which is easily adaptable to other proteins, can be used to simultaneously measure the normally small amount of (125)I-Tf transcytosis and degradation.

  20. Photonic polarization gears for ultra-sensitive angular measurements.

    PubMed

    D'Ambrosio, Vincenzo; Spagnolo, Nicolò; Del Re, Lorenzo; Slussarenko, Sergei; Li, Ying; Kwek, Leong Chuan; Marrucci, Lorenzo; Walborn, Stephen P; Aolita, Leandro; Sciarrino, Fabio

    2013-01-01

    Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a 'photonic gear', converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a 'super-resolving' Malus' law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high 'gear ratio' m boosts the current state of the art of optical non-contact angular measurements by almost two orders of magnitude.

  1. Dual spectrally resolved interferometry to improve measurement range

    NASA Astrophysics Data System (ADS)

    Seo, Y. B.; Kim, B. K.; Joo, K.-N.

    2015-05-01

    In this investigation, a simple optical configuration and technique to improve the performance of spectrally-resolved interferometry (SRI) is proposed and experimentally verified. SRI has the fundamental limitation in the measurement range caused by the spectral bandwidth of an optical source and the spectral resolution of a spectrometer to detect the spectral interference density. Especially, the minimum measurable range of SRI is determined by the bandwidth of the source and this minimum measurable range becomes a dead zone in SRI. The proposed method can eliminate the dead zone without the minimum measurable distance and extend the measurable range of spectrally resolved interferometry (SRI) twice based on the bandwidth separation by a dichroic beam splitter (DBS). The benefit of this dichroic SRI is that it can be simply implemented with a DBS and another reference mirror from the typical SRI. Feasibility experiments were performed to verify the principle of the dichroic SRI and the result confirmed the effectiveness of this method as the extended measuring range.

  2. Picosecond time-resolved measurements of dense plasma line shifts

    DOE PAGES

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; ...

    2017-06-13

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1s2p–1s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al Heα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing red shift for electron densities of 1 to 5 × 1023 cm–3. Furthermore, the measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion sphere model.

  3. A new approach to highly resolved measurements of turbulent flow

    NASA Astrophysics Data System (ADS)

    Puczylowski, J.; Hölling, A.; Peinke, J.; Bhiladvala, R.; Hölling, M.

    2015-05-01

    In this paper we present the design and principle of a new anemometer, namely the 2d-Laser Cantilever Anemometer (2d-LCA), which has been developed for highly resolved flow speed measurements of two components (2d) under laboratory conditions. We will explain the working principle and demonstrate the sensor’s performance by means of comparison measurements of wake turbulence with a commercial X-wire. In the past we have shown that the 2d-LCA is capable of being applied in liquid and particle-laden domains, but we also believe that other challenging areas of operation such as near-wall flows can become accessible.

  4. Picosecond time-resolved measurements of dense plasma line shifts

    NASA Astrophysics Data System (ADS)

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; Golovkin, I. E.; Mileham, C.; Begishev, I. A.; Froula, D. H.

    2017-06-01

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1 s 2 p -1 s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al H eα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing redshift for electron densities of 1 -5 ×1023c m-3 . The measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion-sphere model.

  5. Nanosecond-resolved temperature measurements using magnetic nanoparticles.

    PubMed

    Xu, Wenbiao; Liu, Wenzhong; Zhang, Pu

    2016-05-01

    Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

  6. Nanosecond-resolved temperature measurements using magnetic nanoparticles

    SciTech Connect

    Xu, Wenbiao; Zhang, Pu; Liu, Wenzhong

    2016-05-15

    Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

  7. Super-resolving interference without intensity-correlation measurement

    NASA Astrophysics Data System (ADS)

    Cao, De-Zhong; Xu, Bao-Long; Zhang, Su-Heng; Wang, Kaige

    2015-05-01

    The high-order intensity correlation function of N -photon interference with thermal light observed in a recent experiment [S. Oppel, T. Büttner, P. Kok, and J. von Zanthier, Phys. Rev. Lett. 109, 233603 (2012), 10.1103/PhysRevLett.109.233603] is analyzed. The terms in the expansion of the N th -order correlation function are put into three groups. One group contributes a homogeneous background. Both of the other two contribute (N -1 ) -fold super-resolving fringes. In principle they correspond to coherent and incoherent superpositions of classical optical fields, respectively. Therefore similar super-resolving fringes can be obtained without intensity-correlation measurements. We report the experimental results of the coherent and incoherent super-resolving diffraction fringes, which are observed directly in the intensity distribution. The N -1 sources in both the coherent and incoherent cases are set in certain definite positions. In the coherent case, moreover, the phase difference between two adjacent source fields is π . The fringe visibility is unity in the incoherent case, while it decreases as N increases in the incoherent case.

  8. Time-resolved measurements of equilibrium profiles in MST

    NASA Astrophysics Data System (ADS)

    Deng, B. H.; Brower, D. L.; Ding, W. X.; Yates, T. F.; Anderson, J. K.; Caspary, K.; McCollam, K. J.; Prager, S. C.; Reusch, J. A.; Sarff, J. S.; Craig, D.

    2007-11-01

    Based on the high-speed, three-wave, far-infrared polarimeter-interferometer measurement of Bpol profiles and external coil measurements of Btave and Btw, a new method is developed to derive Btor and other equilibrium profiles (J// and q) with high time resolution. Using Faraday's law, the inductive electric field (E//) profile is also deduced from the temporal derivatives of the time-resolved magnetic field profiles. The derived B(0) values have excellent agreement with direct measurements using a Motional Stark Effect (MSE) diagnostic. Evolution of equilibrium profiles during single sawtooth events in MST, both the slow linear ramp and crash phases, are presented. Profile scaling with plasma current Ip and reversal parameter F is also explored. MHD stability is tested from the spatial gradients of the J// and q profiles, and correlation with fluctuation mode amplitude is investigated. Future improvements to equilibrium reconstruction are expected by measuring Btor(r,t) directly via Cotton-Mouton interferometry.

  9. Polarization Transfer Measurements in the Fluorino

    NASA Astrophysics Data System (ADS)

    Huang, Weidong

    The charge exchange (p,n) reaction at intermediate bombarding energies (100-200 MeV) is a powerful tool to study both the effective nucleon-nucleus interaction and nuclear structure. The (p,n) reaction can induce both Garnow-Teller (GT) transitions (transitions that involve the change of the nucleon spin and isospin) and Fermi (F) transitions (that involve only the change of the isospin projection). These transitions are directly related to natural beta-decay, a process already well understood. The ratio of GT to Fermi transition strength in the (p,n) reaction plays a very important role in extracting nuclear structure information from the (p,n) spectra, especially for odd-mass nuclei where the Fermi transition is mixed with the GT transition. Standard DWIA theory predicts that this ratio is "universal" to all nuclei, i.e., it is characteristic of the reaction and not of the structure. Early cross section measurement studies have revealed that some odd-mass nuclei have anomalously "larger" unit cross sections, sigma(GT)/B(GT), based on the GT/F strength ratio empirically determined from even-mass nuclei. The problem, however, can not be solved from cross section measurements alone. Direct light can be shed on these issues with the measurement of the spin transfer coefficient D_{NN} of (p,n) reactions using a polarized proton beam. The measured value of D_{NN} provides an independent measure of the GT/F strength ratio. Measurements were made for ^{19}F and ^{39}K targets at 120 MeV and 160 MeV at Indiana University Cyclotron Facility. The neutron energy was measured by the time-of-flight technique with a 75 meter neutron flight path. The neutron polarization was measured by a two plane neutron polarimeter. The experimental results, along with other data, suggest that the GT/F strength ratio for these odd-mass nuclei are larger than the systematic values found for even-mass nuclei. The larger ratio also implies bigger unit cross sections for these nuclei, and

  10. Seasonal and solar-cycle variations of polar magnetic fields resolved via eigenanalysis and graph theory

    NASA Astrophysics Data System (ADS)

    Shore, Robert; Freeman, Mervyn; Gjerloev, Jesper

    2017-04-01

    We apply the meteorological analysis method of Empirical Orthogonal Functions (EOF) to ground magnetometer measurements, and subsequently use graph theory to classify the results. The EOF method is used to characterise and separate contributions to the variability of the Earth's external magnetic field (EMF) in the northern polar region. EOFs decompose the noisy EMF data into a small number of independent spatio-temporal basis functions, which collectively describe the majority of the magnetic field variance. We use these basis functions (computed monthly) to infill where data are missing, providing a self-consistent description of the EMF at 5-minute resolution spanning 1997—2009 (solar cycle 23). Each of the EOF basis functions can typically be associated with one of the Disturbance Polar (DP)-type current systems (e.g. DP2, DP1, DPY, NBZ), or with the motion of these systems. This association allows us to describe the varying behaviour of the current systems over the 144 months (i.e. 1997—2009) of our reanalysis. However, the EOF basis functions are (by definition) ranked by their contribution to the total variance, and thus a given current system may be described by a different rank of basis vector from month to month. We use graph theory to find clusters of quantifiably-similar spatial basis functions, and thereby track a given pattern throughout the span of 144 months. Via this method, we present the seasonal and solar cycle variations in the polar current systems.

  11. Spatially resolved heat release rate measurements in turbulent premixed flames

    SciTech Connect

    Ayoola, B.O.; Kaminski, C.F.; Balachandran, R.; Mastorakos, E.; Frank, J.H.

    2006-01-01

    Heat release rate is a fundamental property of great importance for the theoretical and experimental elucidation of unsteady flame behaviors such as combustion noise, combustion instabilities, and pulsed combustion. Investigations of such thermoacoustic interactions require a reliable indicator of heat release rate capable of resolving spatial structures in turbulent flames. Traditionally, heat release rate has been estimated via OH or CH radical chemiluminescence; however, chemiluminescence suffers from being a line-of-sight technique with limited capability for resolving small-scale structures. In this paper, we report spatially resolved two-dimensional measurements of a quantity closely related to heat release rate. The diagnostic technique uses simultaneous OH and CH{sub 2}O planar laser-induced fluorescence (PLIF), and the pixel-by-pixel product of the OH and CH{sub 2}O PLIF signals has previously been shown to correlate well with local heat release rates. Results from this diagnostic technique, which we refer to as heat release rate imaging (HR imaging), are compared with traditional OH chemiluminescence measurements in several flames. Studies were performed in lean premixed ethylene flames stabilized between opposed jets and with a bluff body. Correlations between bulk strain rates and local heat release rates were obtained and the effects of curvature on heat release rate were investigated. The results show that the heat release rate tends to increase with increasing negative curvature for the flames investigated for which Lewis numbers are greater than unity. This correlation becomes more pronounced as the flame gets closer to global extinction.

  12. Time-resolved x-ray magnetic circular dichroism study of ultrafast demagnetization in a CoPd ferromagnetic film excited by circularly polarized laser pulse

    NASA Astrophysics Data System (ADS)

    López-Flores, Víctor; Arabski, Jacek; Stamm, Christian; Halté, Valérie; Pontius, Niko; Beaurepaire, Eric; Boeglin, Christine

    2012-07-01

    The magnetization dynamics of CoPd films excited by circularly polarized ultrashort laser pulses is studied by time-resolved x-ray magnetic circular dichroism. In those films the ultrafast dynamics measured at the Co-L3 edge is strongly sensitive to the orbital magnetic moment Lz. The amount of angular momentum transferred by the circularly polarized ultrashort laser pulses to the ferromagnetic films is evaluated to ±0.1 ℏ/atom, which is above the detection limit of the experiment. Despite this, no polarization-dependent difference on the magnetization dynamics could be evidenced. These results are explained by ultrafast electronic relaxation mechanisms of the transferred angular momentum, faster than ˜100 fs. This experiment sets the methodology as well as an upper time limit for determination of angular momentum relaxation processes.

  13. Measurement of the polarization effects of an instrument using partially polarized light

    NASA Technical Reports Server (NTRS)

    Howell, B. J.

    1979-01-01

    Accuracy of a radiometer is adversely affected by scene polarization if the receiving optical system is sensitive to polarization. It is therefore necessary to specify and measure the sensitivity of the system to polarized light. The Mueller-Stokes matrix of an instrument may be determined experimentally and used to predict the effects of the instrument on any beam. The specification of a maximum polarization sensitivity stated in terms of the degree of polarization produced in an unpolarized beam can be experimentally verified even though an unpolarized beam is not available in the laboratory for direct measurement.

  14. Experimental Time Resolved Electron Beam Temperature Measurements Using Bremsstrahlung Diagnostics

    SciTech Connect

    Menge, P.R.; Maenchen, J.E.; Mazarakis, M.G.; Rosenthal, S.E.

    1999-06-25

    Electron beam temperature, {beta}{perpendicular} (= v{perpendicular}/v), is important to control for the development of high dose flash radiographic bremsstrahlung sources. At high voltage (> 5 MV) increasing electron beam temperature has a serious deleterious effect on dose production. The average and time resolved behavior of beam temperature was measured during radiographic experiments on the HERMES III accelerator (10 MV, 50 kA, 70 ns). A linear array of thermoluminescent dosimeters (TLDs) were used to estimate the time integrated average of beam temperature. On and off-axis photoconducting diamond (PCD) detectors were used to measure the time resolved bremsstrahlung dose rate, which is dependent on beam energy and temperature. The beam temperature can be determined by correlating PCD response with accelerator voltage and current and also by analyzing the ratio of PCD amplitudes on and off axis. This ratio is insensitive to voltage and current and thus, is more reliable than utilizing absolute dose rate. The data is unfolded using comparisons with Monte Carlo simulations to obtain absolute beam temperatures. The data taken on HERMES III show abrupt increases in {beta}{perpendicular} midway through the pulse indicating rapid onset of beam instability.

  15. Range-resolved gas concentration measurements using tunable semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Lytkine, A.; Lau, B.; Lim, A.; Jäger, W.; Tulip, J.

    2008-02-01

    A method for range-resolved gas sensing using path-integrated optical systems is presented. The method involves dividing an absorption path into several measurement segments and extracting the gas concentration in each segment from two path-integrated measurements. We implemented the method with tunable lasers (a 1389-nm VCSEL and a 10.9-μm pulsed quantum cascade laser) and a group of retro reflectors (RRs) distributed along absorption paths. Using a rotating mirror with the VCSEL configuration, we could scan a group of seven tape RRs spaced by 10 cm in ˜ 9 ms to extract an H2O concentration profile. Reduced H2O concentrations were recorded in the segments purged with dry air. Hollow corner cube RRs were used in the quantum cascade laser configuration at distances up to 1.1 km from the laser. Two RRs placed at 66 m and 125 m from the laser allowed us to determine H2O concentrations in both segments. The RRs returns were separated due to the different round trip travel time of the 200-ns laser pulse. Novel instruments for range-resolved remote sensing in the atmosphere can be developed for a variety of applications, including monitoring the fluxes of atmospheric pollutants and controlling air quality in populated areas.

  16. Polarization-resolved hyperspectral stimulated Raman scattering microscopy for label-free biomolecular imaging of the tooth

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Zheng, Wei; Hsu, Chin-Ying Stephen; Huang, Zhiwei

    2016-01-01

    We report the development and implementation of a rapid polarization-resolved hyperspectral stimulated Raman scattering (SRS) microscopy technique for label-free biomolecular imaging of the tooth. The hyperspectral SRS imaging technique developed covers both fingerprint (800-1800 cm-1) and high-wavenumber (2800-3600 cm-1) regions for tooth Raman imaging without fluorescence background interference with an imaging speed of <0.3 s per frame of 512 × 512 pixels (˜1 μs per pixel), that is, >106 faster than confocal Raman imaging. Significant differences of hyperspectral SRS spectra among different tooth locations (e.g., dentin, enamel, and dentin-enamel junction) are observed, revealing the biochemical distribution differences across the tooth. Further polarization-resolved SRS imaging shows different polarization dependences related to the molecular orientation differences of various tooth locations. This work demonstrates the potential of polarization-resolved hyperspectral SRS imaging technique developed in rapidly characterizing biochemical structures and compositions as well as biomolecule organizations/orientations of the tooth without labeling.

  17. Seasonal and solar-cycle variations of DP-type polar magnetic fields resolved via EOF analysis

    NASA Astrophysics Data System (ADS)

    Shore, Robert; Freeman, Mervyn; Wild, James; Dorrian, Gareth; Gjerloev, Jesper

    2016-04-01

    We describe our application of the Empirical Orthogonal Function (EOF) method to characterise and separate contributions to the variability of the Earth's external magnetic field (EMF) in the northern polar region, using ground magnetometer measurements. The EOF method analyses the spatio-temporal co-variance of the data to decompose it into dynamically distinct modes (each mode is a pair of spatial and temporal basis vectors). Briefly, the benefits of this analysis method are firstly that a small number of the modes can cumulatively represent most of the variance of the original data, and secondly that the basis vectors are defined by the data. Hence, the structure of the EMF is resolved compactly without a priori assumptions, in contrast to other decomposition methods such as Fourier and spherical harmonic expansions. We present the modes from 11 years (1997 - 2008) of magnetic vector data at 5 minutes resolution, recently collated by the SuperMAG archive of observatory and variometer data. Despite the sparse and irregular station distribution, a complete spatial morphology of the EMF is achieved using a self-consistent iterative infill method. Using a comparison of the temporal behaviour of the modes alongside independent measures of solar-terrestrial coupling, we demonstrate that the leading three modes describe the well-known Disturbance-Polar currents types 2 and 1 (DP2, DP1) and the system of cusp currents (DPY). These three modes account for the majority of the variance of the data - other modes describe the spatial motions of these current systems. The variation in the DP2, DP1 and DPY currents throughout the last solar cycle is presented, and the utility of this database of magnetic perturbations (to which further analysis methods can be applied) is highlighted.

  18. Generation of an axially super-resolved quasi-spherical focal spot using an amplitude-modulated radially polarized beam.

    PubMed

    Lin, Han; Jia, Baohua; Gu, Min

    2011-07-01

    An axially super-resolved quasi-spherical focal spot can be generated by focusing an amplitude-modulated radially polarized beam through a high numerical aperture objective. A method based on the unique depolarization properties of a circular focus is proposed to design the amplitude modulation. The generated focal spot shows a ratio of x:y:z=1:1:1.48 for the normalized FWHM in three dimensions, compared to that of x:y:z=1:0.74:1.72 under linear polarization (in the x direction) illumination. Moreover, the focusable light efficiency of the designed amplitude-modulated beam is 65%, which is more than 3 times higher than the optimized case under linear polarization and thus make the amplitude-modulated radial polarization beam more suitable for a wide range of applications.

  19. Time-resolved aluminium laser-induced plasma temperature measurements

    NASA Astrophysics Data System (ADS)

    Surmick, D. M.; Parigger, C. G.

    2014-11-01

    We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

  20. Measurements of Hygroscopicity- and Size-Resolved Sea Spray Aerosol

    NASA Astrophysics Data System (ADS)

    Phillips, B.; Dawson, K. W.; Royalty, T. M.; Reed, R. E.; Petters, M.; Meskhidze, N.

    2015-12-01

    Atmospheric aerosols play a central role in many environmental processes by influencing the Earth's radiative balance, tropospheric chemistry, clouds, biogeochemical cycles, and visibility as well as adversely impacting human health. Based on their origin, atmospheric aerosols can be defined as anthropogenic or natural. Recent studies have shown that a large fraction of uncertainty in the radiative effects of anthropogenic aerosols is related to uncertainty in natural—background—aerosols. Marine aerosols are of particular interest due to the abundance of oceans covering the Earth's surface. Despite their importance, limited information is currently available for size- and composition-resolved marine aerosol emission fluxes. Our group has designed and built an instrument for measuring the size- and hygroscopicity-resolved sea spray aerosol fluxes. The instrument was first deployed during spring 2015 at the end of the 560 m pier of the US Army Corps of Engineers' Field Research Facility in Duck, NC. Measurements include 200 nm-sized diameter growth factor (hygroscopicity) distributions, sea spray particle flux measurements, and total sub-micron sized aerosol concentration. Ancillary ocean data includes salinity, pH, sea surface temperature, dissolved oxygen content, and relative fluorescence (proxy for [Chl-a]). Hygroscopicity distribution measurements show two broad peaks, one indicative of organics and sulfates and another suggestive of sea salt. The fraction of 200 nm-sized salt particles having hygroscopicity similar to that of sea-spray aerosol contributes up to ~24% of the distribution on days with high-speed onshore winds and up to ~3% on calm days with winds blowing from the continent. However, the total concentration of sea-spray-like particles originating from offshore versus onshore winds was relatively similar. Changes in the relative contribution of sea-salt to number concentration were caused by a concomitant changes in total aerosol concentration

  1. Time-resolved emission spectroscopy of CdSe quantum dots in polar and nonpolar solvents

    NASA Astrophysics Data System (ADS)

    Kloepfer, Jeremiah; Bradforth, Stephen; Nadeau, Jay

    2004-03-01

    Nanocrystal quantum dots (QD) offer the opportunity to study semiconductors in liquid environments. QD biological labels in water are often protected from emission quenching and surface oxidation. We wish to exploit these processes to construct novel "on/off" sensors based on energy and electron transfer. These systems offer the chance to probe the semiconductor surface-solvent interface. Time-correlated-single-photon-counting was used to measure the emission lifetimes of several QD-solvent systems. Typical lifetimes could be divided into fast single exponential ( 100 ps) and slow stretched exponential ( 10 ns) decays. CdSe and ZnS(CdSe) were prepared in non-polar solvents with high quantum yields. QD were solubilized in water with thiol-compounds, polymer/protein coats, and micelles/vesicles. Large changes in the emission profiles of the different systems were observed. Systems in water experienced a reduction in quantum yield and loss of the longtime emission decay. Surface oxidation lead to a recovery of the longtime decay which matched that of the ZnS-capped counterpart in non-polar solvents. Lifetimes of QD in the presence of energy/electron transfer donors/acceptors was measured to test the viability of constructing nanocrystal sensors that exploit these processes.

  2. Measuring the continuum polarization with ESPaDOnS

    NASA Astrophysics Data System (ADS)

    Pereyra, A.; Rodrigues, C. V.; Martioli, E.

    2015-01-01

    Aims: Our goal is to test the feasibility of obtaining accurate measurements of the continuum polarization from high-resolution spectra using the spectropolarimetric mode of ESPaDOnS. Methods: We used the new pipeline OPERA to reduce recent and archived ESPaDOnS data. Several polarization standard stars and science objects were tested for the linear mode. In addition, the circular mode was tested using several objects from the archive with expected null polarization. Synthetic broad-band polarization was computed from the ESPaDOnS continuum polarization spectra and compared with published values (when available) to quantify the accuracy of the instrument. Results: The continuum linear polarization measured by ESPaDOnS is consistent with broad-band polarimetry measurements available in the literature. The accuracy in the degree of linear polarization is around 0.2-0.3% considering the full sample. The accuracy in polarization position angle using the most polarized objects is better than 5°. Consistent with this, the instrumental polarization computed for the circular continuum polarization is also between 0.2-0.3%. Our results suggest that measurements of the continuum polarization using ESPaDOnS are viable and can be used to study many astrophysical objects. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientique of France, and the University of Hawaii.

  3. High resolved velocity measurements using Laser Cantilever Anemometry

    NASA Astrophysics Data System (ADS)

    Puczylowski, Jaroslaw; Hölling, Michael; Peinke, Joachim

    2016-11-01

    We have developed a new anemometer, namely the 2d-LCA (2d-Laser-Cantilever-Anemometer), that is capable of performing high resolved velocity measurements in fluids. The anemometer uses a micostructured cantilever made of silicon as a sensing element. The specific shape and the small dimensions (about 150µm) of the cantilever allow for precise measurements of two velocity component at a temporal resolution of about 150kHz. The angular acceptance range is 180° in total. The 2d-LCA is a simple to use alternative to x-wires and can be used in many areas of operation including measurements in liquids or in particle-laden flows. Unlike hot-wires, the resolution power of the 2d-LCA does not decrease with increasing flow velocity, making it particularly suitable for measurements in high-speed flows. In the recent past new cantilever designs were implemented with the goal to further improve the angular resolution and increase the stability. In addition, we have designed more robust cantilevers for measurements in rough environments such as offshore areas. Successful comparative measurements with hot-wires have been carried out in order to assess the performance of the 2d-LCA.

  4. Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)

    SciTech Connect

    Tobin, James; Yu, Sung Woo; Morton, Simon; Waddill, George; Thompson, Jamie; Neal, James; Spangenberg, Matthais; Shen, T.H.

    2009-05-19

    Highly spin-polarized sources of electrons, Integrated into device design, remain of great interest to the spintronic and magneto-electronic device community Here, the growth of Fe upon GaAs(001) has been studied with photoelectron spectroscopy (PES), including Spin Resolved PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of alpha-Fe(001), with a bcc real space ordering, Is obtained The results will be discussed in light of the possibility of using such films as a spin-polarized source in device applications.

  5. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    SciTech Connect

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  6. Time resolved velocity measurements of unsteady systems using spiral imaging

    NASA Astrophysics Data System (ADS)

    Tayler, Alexander B.; Holland, Daniel J.; Sederman, Andrew J.; Gladden, Lynn F.

    2011-07-01

    Spiral imaging has been assessed as a tool for the measurement of spatially and temporally resolved velocity information for unsteady flow systems. Using experiments and simulated acquisitions, we have quantified the flow artefacts associated with spiral imaging. In particular, we found that despite the adverse effect of in-plane flow on the point spread function, for many physical systems the extent of blurring associated with spiral imaging is marginal because flows represented by high spatial Fourier coefficients, which would be those most affected by the distortion of the point spread function, exist at the physical boundaries of the flow and are therefore associated with much smaller velocities than are characteristic of the bulk flow. The necessity for a flow imaging technique which is robust to the accrual of velocity proportionate phase during imaging was demonstrated in an experimental comparison of spiral imaging and echo-planar imaging (EPI) applied to turbulent flow in a pipe. While the measurements acquired using EPI accrued substantial velocity proportionate phase, those acquired using spiral imaging were not significantly affected. High temporal velocity measurements using spiral imaging were demonstrated on turbulent flow in a pipe (image acquisition time 5.4 ms; 91 frames per second), which enabled the transient behaviour of wall instabilities to be captured. Additionally, the technique was applied to a multiphase flow system, where the wakes behind single rising bubbles were characterised. Spiral imaging thus seems an auspicious basis for the measurement of velocity fields for unsteady flow systems.

  7. Polarization Measurements in High-Energy Deuteron Photodisintegration

    SciTech Connect

    Adam Sarty; Andrei Afanasev; Arunava Saha; Bogdan Wojtsekhowski; Brendan Fox; C. Chang; Cathleen Jones; Charles Glashausser; Charles Perdrisat; Cornelis De Jager; Cornelis de Jager; D. Crovelli; Daniel Simon; David Meekins; Demetrius Margaziotis; Dipangkar Dutta; Edgar Kooijman; Edward Brash; Edward Kinney; Elaine Schulte; Eugene Chudakov; Feng Xiong; Franco Garibaldi; Garth Huber; Gerfried Kumbartzki; Guido Urciuoli; Haiyan Gao; James Kelly; Javier Gomez; Jens-Ole Hansen; Jian-Ping Chen; John Calarco; John LeRose; Jordan Hovdebo; Joseph Mitchell; Juncai Gao; Kamal Benslama; Kathy McCormick; Kevin Fissum; Konrad Aniol; Krishni Wijesooriya; Louis Bimbot; Ludyvine Morand; Luminita Todor; Marat Rvachev; Mark Jones; Martin Epstein; Meihua Liang; Michael Kuss; Moskov Amarian; Nilanga Liyanage; Oleksandr Glamazdin; Olivier Gayou; Paul Ulmer; Pete Markowitz; Peter Bosted; R. Holt; Riad Suleiman; Richard Lindgren; Rikki Roche; Robert Michaels; Roman Pomatsalyuk; Ronald Gilman; Ronald Ransome; Salvatore Frullani; Scott Dumalski; Seonho Choi; Sergey Malov; Sonja Dieterich; Steffen Strauch; Stephen Becher; Steve Churchwell; Ting Chang; Viktor Gorbenko; Vina Punjabi; Xiaodong Jiang; Zein-Eddine Meziani; Zhengwei Chai; Wang Xu

    2001-04-01

    We present measurements of the recoil proton polarization for the d(polarized y, polarized p)n reaction at thetac.m. = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(y,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.

  8. Circularly polarized near-field optical mapping of spin-resolved quantum Hall chiral edge states.

    PubMed

    Mamyouda, Syuhei; Ito, Hironori; Shibata, Yusuke; Kashiwaya, Satoshi; Yamaguchi, Masumi; Akazaki, Tatsushi; Tamura, Hiroyuki; Ootuka, Youiti; Nomura, Shintaro

    2015-04-08

    We have successfully developed a circularly polarized near-field scanning optical microscope (NSOM) that enables us to irradiate circularly polarized light with spatial resolution below the diffraction limit. As a demonstration, we perform real-space mapping of the quantum Hall chiral edge states near the edge of a Hall-bar structure by injecting spin polarized electrons optically at low temperature. The obtained real-space mappings show that spin-polarized electrons are injected optically to the two-dimensional electron layer. Our general method to locally inject spins using a circularly polarized NSOM should be broadly applicable to characterize a variety of nanomaterials and nanostructures.

  9. Accuracy of circular polarization as a measure of spin polarization in quantum dot qubits.

    PubMed

    Pryor, C E; Flatté, M E

    2003-12-19

    A quantum dot spin light emitting diode provides a test of carrier spin injection into a qubit and a means for analyzing carrier spin injection and local spin polarization. Even with 100% spin-polarized carriers the emitted light may be only partially circularly polarized due to the geometry of the dot. We have calculated carrier polarization-dependent optical matrix elements for InAs/GaAs self-assembled quantum dots (SAQDs) for electron and hole spin injection into a range of quantum dot sizes and shapes, and for arbitrary emission directions. Calculations for typical SAQD geometries with emission along [110] show light that is only 5% circularly polarized for spin states that are 100% polarized along [110]. Measuring along the growth direction gives near unity conversion of spin to photon polarization and is the least sensitive to uncertainties in SAQD geometry.

  10. Annually resolved seawater temperature variability of the Sub-polar North Atlantic over the last 1000 years

    NASA Astrophysics Data System (ADS)

    Reynolds, David; Scourse, James; Hall, Ian; Nederbragt, Alexandra; Wanamaker, Alan; Halloran, Paul; Butler, Paul; Richardson, Chris; Eiríksson, Jon; Heinemeier, Jan; Luise Knudsen, Karen

    2015-04-01

    The lack of annually-resolved marine climate records spanning the last millennium constrains our understanding of the natural variability of the global climate system. We present a continuous annually-resolved reconstruction of sub-polar (N Iceland) sea water temperatures (SWT) derived from the 18O analyses of carbonate material drilled from the annually resolved growth increments contained in an absolutely dated master Arctica islandica sclerochronology spanning the period 953-2000. The calibrated SWT reconstruction contains a significant cooling trend over the period 953-1891 (0.1oC per century) and a marked warming trend over the period 1891-2000 (2.3oC per century). The underlying natural variability is controlled by solar irradiance changes modulated by volcanic forcing and internal variability. The modern SWT warming is demonstrated to lie outside the range of natural variability of the last 1000 years consistent with an anthropogenic influence.

  11. Space-time resolved measurements of spontaneous magnetic fields in laser-produced plasma

    SciTech Connect

    Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Borodziuk, S.; Gus'kov, S. Yu.; Dudzak, R.; Dostal, J.; Krousky, E.; Ullschmied, J.; Hrebicek, J.; Medrik, T.; Golasowski, J.; Pfeifer, M.; Skala, J.; Demchenko, N. N.; Korneev, Ph.; Kalal, M.; Renner, O.; Smid, M.; Pisarczyk, P.

    2015-10-15

    The first space-time resolved spontaneous magnetic field (SMF) measurements realized on Prague Asterix Laser System are presented. The SMF was generated as a result of single laser beam (1.315 μm) interaction with massive planar targets made of materials with various atomic numbers (plastic and Cu). Measured SMF confirmed azimuthal geometry and their maximum amplitude reached the value of 10 MG at the laser energy of 250 J for both target materials. It was demonstrated that spatial distributions of these fields are associated with the character of the ablative plasma expansion which clearly depends on the target material. To measure the SMF, the Faraday effect was employed causing rotation of the vector of polarization of the linearly polarized diagnostic beam. The rotation angle was determined together with the phase shift using a novel design of a two-channel polaro-interferometer. To obtain sufficiently high temporal resolution, the polaro-interferometer was irradiated by Ti:Sa laser pulse with the wavelength of 808 nm and the pulse duration of 40 fs. The results of measurements were compared with theoretical analysis.

  12. Time- and polarization-resolved cellular autofluorescence towards quantitative biochemistry on living cells

    NASA Astrophysics Data System (ADS)

    Alfveby, John; TImerman, Randi; Soto Velasquez, Monica P.; Wickramasinghe, Dhanushka W. P. M.; Bartusek, Jillian; Heikal, Ahmed A.

    2014-09-01

    Native coenzymes such as the reduced nicotinamide adenine dinucleotide (NADH) and oxidized flavin adenine dinucleotide play pivotal roles in energy metabolism and a myriad of biochemical reactions in living cells/tissues. These coenzymes are naturally fluorescent and, therefore, have the potential to serve as intrinsic biomarkers for mitochondrial activities, programmed cell death (apoptosis), oxidative stress, aging, and neurodegenerative disease. In this contribution, we employ two-photon fluorescence lifetime imaging microscopy (FLIM) and time-resolved anisotropy imaging of intracellular NADH for quantitative, non-invasive biochemistry on living cells in response to hydrogenperoxide- induced oxidative stress. In contrast with steady-state one-photon, UV-excited autofluorescence, two-photon FLIM is sensitive to both molecular conformation and stimuli-induced changes in the local environment in living cells with minimum photodamage and inherently enhanced spatial resolution. On the other hand, time-resolved, two-photon anisotropy imaging of cellular autofluorescence allows for quantitative assessment of binding state and environmental restrictions on the tumbling mobility of intrinsic NADH. Our measurements reveal that free and enzyme-bound NADH exist at equilibrium, with a dominant autofluorescence contribution of the bound fraction in living cells. Parallel studies on NADH-enzyme binding in controlled environments serve as a point of reference in analyzing autofluorescence in living cells. These autofluorescence-based approaches complement the conventional analytical biochemistry methods that require the destruction of cells/tissues, while serving as an important step towards establishing intracellular NADH as a natural biomarker for monitoring changes in energy metabolism and redox state of living cells in response to environmental hazards.

  13. Novel polarization-sensitive micropulse lidar measurement technique.

    PubMed

    Flynn, Connor J; Mendoza, Albert; Zheng, Yunhui; Mathur, Savyasachee

    2007-03-19

    Polarization-sensitive detection of elastic backscattered light is useful for detection of cloud phase and depolarizing aerosols. The U.S. Department of Energy's Atmospheric Radiation Measurement Program has deployed micropulse lidar (MPL) for over a decade, but without polarized detection. Adding an actively-controlled liquid crystal retarder provides the capability to identify depolarizing particles by alternately transmitting linearly and circularly polarized light. This represents a departure from established techniques, which transmit exclusively linear polarization or exclusively circular polarization. Mueller matrix calculations yield simple relationships between the well-known linear depolarization ratio delta(linear), the circular depolarization ratio delta(circ), and this MPL depolarization ratio delta(MPL).

  14. Measurement of complex ultrashort laser pulses using frequency-resolved optical gating

    NASA Astrophysics Data System (ADS)

    Xu, Lina

    This thesis contains three components of research: a detailed study of the performance of Frequency-Resolved Optical Gating (FROG) for measuring complex ultrashort laser pulses, a new method for measuring the arbitrary polarization state of an ultrashort laser pulse using Tomographic Ultrafast Retrieval of Transverse Light E-fields (TURTLE) technique, and new approach for measuring two complex pulses simultaneously using PG blind FROG. In recent decades, many techniques for measuring the full intensity and phase of ultrashort laser pulses have been proposed. These techniques include: Spectral Interferometry (SI)[1], Temporal Analysis by Dispersing a Pair of Light E-Field (TADPOLE)[2], Spectral Phase Interferometry for direct electric-field reconstruction (SPIDER)[3], and Frequency-Resolved Optical Gating (FROG)[4]. Each technique is actually a class of techniques that includes different variations on the original idea, such as SEA-SPIDER[5], ZAP SPIDER[6] are two variations of SPIDER. But most of these techniques for measuring ultrashort laser pulses either do not yield the complete time-dependent intensity and phase (e.g., autocorrelation), can at best only measure simple pulses (e.g., SPIDER), or need well characterized reference pulse. In this thesis, we compare the performance of three versions of FROG: second-harmonic-generation (SHG) FROG, polarization-gate (PG) FROG, and cross-correlation FROG (XFROG), the last of which requires a well-characterized reference pulse. We found that the XFROG algorithm converged in all cases and required only one initial guess. The PG FROG algorithm converged for 99% of the moderately complex pulses that we tried, and for over 95% of the most complex pulses (TBP ˜ 100). And the SHG FROG algorithm converged for 95% of the pulses that we tried and for over 80% of the most complex pulses. After some analysis, we found that noise filtering and adding more sampling points to the FROG trace solved the non-converging problems and we

  15. Cell growth characteristics from angle- and polarization-resolved light scattering: Prospects for two-dimensional correlation analysis

    NASA Astrophysics Data System (ADS)

    Herran Cuspinera, Roxana M.; Hore, Dennis K.

    2016-11-01

    We highlight the potential of generalized two-dimensional correlation analysis for the fingerprinting of cell growth in solution monitored by light scattering, where the synchronous and asynchronous responses serve as a sensitive marker for the effect of growth conditions on the distribution of cell morphologies. The polarization of the scattered light varies according to the cell size distribution, and so the changes in the polarization over time are an excellent indicator of the dynamic growth conditions. However, direct comparison of the polarization-, time-, and angle-resolved signals between different experiments is hindered by the subtle changes in the data, and the inability to easily adapt models to account for these differences. Using Mie scattering simulations of different growth conditions, and some preliminary experimental data for a single set of conditions, we illustrate that correlation analysis provides rapid and sensitive qualitative markers of growth characteristics.

  16. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  17. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  18. Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

    SciTech Connect

    Fischer, W.; Bazilevsky, A.

    2011-08-18

    The development of polarization profiles are the primary reason for the loss of average polarization. Polarization profiles have been parametrized with a Gaussian distribution. We derive the effect of 3-dimensional polarization profiles on the measured polarization in polarimeters, as well as the observed polarization and the figure of merit in single and double spin experiments. Examples from RHIC are provided. The Relativistic Heavy Ion Collider (RHIC) is the only collider of spin polarized protons. During beam acceleration and storage profiles of the polarization P develop, which affect the polarization measured in a polarimeter, and the polarization and figure of merit (FOM) in colliding beam experiments. We calculate these for profiles in all dimensions, and give examples for RHIC. Like in RHIC we call the two colliding beams Blue and Yellow. We use the overbar to designate intensity-weighted averages in polarimeters (e.g. {bar P}), and angle brackets to designate luminosity-weighted averages in colliding beam experiments (e.g.

    ).

  19. Measuring the Polar Mesosphere With Radio Telescopes

    NASA Astrophysics Data System (ADS)

    Martin, C. L.; Burrows, S. M.

    2004-12-01

    The 1957 IGY launched a program of upper atmosphere observations that continues to this day. However in 1957, observations of the upper atmosphere were limited to the tools available at the time. As we head toward the 2007 IPY we can take advantage of the tools developed in the past 50 years to continue and expand upon this extensive dataset, as well as consider novel uses for the tools already available on the continent. Over the past ten years, the polar plateau has been established as one of the preeminent sites on Earth from which to perform radio astronomy observations at frequencies ranging from 100 to 2000 GHz. As a by-product of their astronomical observations, these telescopes often collect high quality aeronomy data that is frequently overlooked. By using data from a radio telescope located at the Amundsen-Scott South Pole Station, we have measured the J=2 -> 1 (230 GHz), J=4-> 3 (461 GHz), and J=7 -> 6 (807 GHz) rotational transitions of carbon monoxide (CO) at altitudes from 50 to 90 km above the Earth's surface. These high frequency data provide a surprisingly high resolution window into the dynamics and structure of the mesosphere. With a time series extending over multiple years, these data allow us to study the dynamics of an altitude range difficult to access with other methods. The IPY provides us with an opportunity to expand these interdisciplinary collaborations and use the resources invested in the Antarctic continent to further the scientific aims of a broad range of researchers.

  20. Spatially resolved Hall effect measurement in a single semiconductor nanowire.

    PubMed

    Storm, Kristian; Halvardsson, Filip; Heurlin, Magnus; Lindgren, David; Gustafsson, Anders; Wu, Phillip M; Monemar, Bo; Samuelson, Lars

    2012-11-01

    Efficient light-emitting diodes and photovoltaic energy-harvesting devices are expected to play an important role in the continued efforts towards sustainable global power consumption. Semiconductor nanowires are promising candidates as the active components of both light-emitting diodes and photovoltaic cells, primarily due to the added freedom in device design offered by the nanowire geometry. However, for nanowire-based components to move past the proof-of-concept stage and be implemented in production-grade devices, it is necessary to precisely quantify and control fundamental material properties such as doping and carrier mobility. Unfortunately, the nanoscale geometry that makes nanowires interesting for applications also makes them inherently difficult to characterize. Here, we report a method to carry out Hall measurements on single core-shell nanowires. Our technique allows spatially resolved and quantitative determination of the carrier concentration and mobility of the nanowire shell. As Hall measurements have previously been completely unavailable for nanowires, the experimental platform presented here should facilitate the implementation of nanowires in advanced practical devices.

  1. Spatially resolved contrast measurement of diffractive micromirror arrays

    NASA Astrophysics Data System (ADS)

    Sicker, Cornelius; Heber, Jörg; Berndt, Dirk; Rückerl, Florian; Tinevez, Jean-Yves; Shorte, Spencer; Wagner, Michael; Schenk, Harald

    2015-02-01

    Diffractive micromirror arrays (MMA) are a special class of optical MEMS, serving as spatial light modulators (SLM) that control the phase of reflected light. Since the surface profile is the determining factor for an accurate phase modulation, high-precision topographic characterization techniques are essential to reach highest optical performance. While optical profiling techniques such as white-light interferometry are still considered to be most suitable to this task, the practical limits of interferometric techniques start to become apparent with the current state of optical MEMS technology. Light scatter from structured surfaces carries information about their topography, making scatter techniques a promising alternative. Therefore, a spatially resolved scatter measurement technique, which takes advantage of the MMA's diffractive principle, has been implemented experimentally. Spectral measurements show very high contrast ratios (up to 10 000 in selected samples), which are consistent with calculations from micromirror roughness parameters obtained by white-light interferometry, and demonstrate a high sensitivity to changes in the surface topography. The technique thus seems promising for the fast and highly sensitive characterization of diffractive MMAs.

  2. Angle-resolved photoemission with circularly polarized light in the nodal mirror plane of underdoped Bi2Sr2CaCu2O8+δ superconductor

    DOE PAGES

    He, Junfeng; Mion, Thomas R.; Gao, Shang; ...

    2016-10-31

    Unraveling the nature of pseudogap phase in high-temperature superconductors holds the key to understanding their superconducting mechanisms and potentially broadening their applications via enhancement of their superconducting transition temperatures. Angle-resolved photoemission spectroscopy (ARPES) experiments using circularly polarized light have been proposed to detect possible symmetry breaking state in the pseudogap phase of cuprates. Here, the presence (absence) of an electronic order which breaks mirror symmetry of the crystal would in principle induce a finite (zero) circular dichroism in photoemission. Different orders breaking reflection symmetries about different mirror planes can also be distinguished by the momentum dependence of the measured circularmore » dichroism.« less

  3. Resolving spectral information from time domain induced polarization data through 2-D inversion

    NASA Astrophysics Data System (ADS)

    Fiandaca, Gianluca; Ramm, James; Binley, Andrew; Gazoty, Aurélie; Christiansen, Anders Vest; Auken, Esben

    2013-02-01

    analysis of the model parameters. With this new algorithm, in situ TD IP measurements give access to the spectral content of the polarization processes, opening up new applications in environmental and hydrogeophysical investigations.

  4. Time-Resolved Measurements of Carbon Nanotube and Nanohorn Growth

    NASA Astrophysics Data System (ADS)

    Geohegan, David

    2005-11-01

    Mechanisms for carbon nanotube growth have been investigated for both laser vaporization (LV) and chemical vapor deposition (CVD) synthesis techniques through the use of time-resolved, in situ laser-based diagnostics for the measurement of absolute growth rates. Optimization of both the production of loose single-wall carbon nanotubes (SWNTs) by LV and the sustained growth of mm-long, vertically-aligned carbon nanotube arrays (VANTAs) by CVD are described. For SWNT growth by laser co-vaporization of carbon and trace metal catalysts at high (1200 C) temperatures, nanotubes are found to grow at ˜ 1--5 microns/second to lengths of only several microns, as determined by gated-ICCD imaging and laser spectroscopy of the plume of ejected material. Efforts to scale the LV production of SWNTs utilizing an industrial Nd:YAG laser (600 W average power, 1-500 Hz repetition rate, 0.5-10ms pulse width) are described. In addition to vaporizing material at much higher rates, the high-power laser irradiation provides sufficient plasma plume density and temperature to enable the growth of novel single-wall carbon nanohorn (SWNH) structures without the need for metal catalysts in the target. Applications of these SWNH structures as metal catalyst supports will be discussed. Through the application of time-resolved reflectivity and direct imaging, CVD growth of VANTAs from hydrocarbon gases at sustained rates of 0.2 -- 0.5 microns/second have been directly measured over millimeters of length at lower (˜ 700 C) temperatures. Now, through a new laser-CVD setup at the ALPS (Advanced Laser Processing and Synthesis) facility at ORNL, high-power laser heating is being employed for the fast and position-controlled growth of carbon nanotubes on substrates. In situ fast optical pyrometry is employed to record the rapid thermal processing of metal-catalyst-prepared substrates to investigate the nucleation and early growth behavior of CVD-grown nanotubes. New nanotube growth and tunable Raman

  5. Temporally and spatially resolved photoluminescence investigation of (112{sup ¯}2) semi-polar InGaN/GaN multiple quantum wells grown on nanorod templates

    SciTech Connect

    Liu, B.; Smith, R.; Athanasiou, M.; Yu, X.; Bai, J.; Wang, T.

    2014-12-29

    By means of time-resolved photoluminescence (PL) and confocal PL measurements, temporally and spatially resolved optical properties have been investigated on a number of In{sub x}Ga{sub 1−x}N/GaN multiple-quantum-well (MQW) structures with a wide range of indium content alloys from 13% to 35% on (112{sup ¯}2) semi-polar GaN with high crystal quality, obtained through overgrowth on nanorod templates. With increasing indium content, the radiative recombination lifetime initially increases as expected, but decreases if the indium content further increases to 35%, corresponding to emission in the green spectral region. The reduced radiative recombination lifetime leads to enhanced optical performance for the high indium content MQWs as a result of strong exciton localization, which is different from the behaviour of c-plane InGaN/GaN MQWs, where quantum confined Stark effect plays a dominating role in emission process.

  6. Millimeter wave passive components for polarization measurements

    NASA Astrophysics Data System (ADS)

    Peverini, O. A.; Baralis, M.; Tascone, R.; Trinchero, D.; Olivieri, A.; Carretti, E.; Cortiglioni, S.

    2002-03-01

    The Stokes parameters of the polarized sky emission are detected by a correlation unit called Hybrid Phase Discriminator (HPD), which uses signals obtained by an Ortho-mode Transducer (OMT). In the millimeter wave range and for rather large bandwidths, heterodyne receivers are not applicable, and the correlation units have to work at the frequency of the radiometer. This contribution deals with a Ka-band prototype of a new configuration of waveguide HPD, which presents a high degree of sensitivity for the detection of linearly polarized radiation. .

  7. Measurement of ocular counterrolling /OCR/ by polarized light

    NASA Technical Reports Server (NTRS)

    Kenyon, R. V.; Lichtenberg, B. K.

    1982-01-01

    The assessment of the activation of the otolith gravitoinertial sensors in the vestibular system of the inner ear may be accomplished by observing the occular counterrolling (OCR) movements which rotate the eyes about the line of sight. A method is presented for the continuous measurement of OCR by means of polarized light, a system of polarizers, and a contact lens. A polarized hard contact lens is placed between two soft lenses before application to the eye, and the measured phase difference between the incident rotating polarized light and the reflected light from this lens provides readings uncontaminated by other eye movement modes.

  8. Proton Form Factor Measurements Using Polarization Method: Beyond Born Approximation

    SciTech Connect

    Pentchev, Lubomir

    2008-10-13

    Significant theoretical and experimental efforts have been made over the past 7 years aiming to explain the discrepancy between the proton form factor ratio data obtained at JLab using the polarization method and the previous Rosenbluth measurements. Preliminary results from the first high precision polarization experiment dedicated to study effects beyond Born approximation will be presented. The ratio of the transferred polarization components and, separately, the longitudinal polarization in ep elastic scattering have been measured at a fixed Q{sup 2} of 2.5 GeV{sup 2} over a wide kinematic range. The two quantities impose constraints on the real part of the ep elastic amplitudes.

  9. Measurement of ocular counterrolling /OCR/ by polarized light

    NASA Technical Reports Server (NTRS)

    Kenyon, R. V.; Lichtenberg, B. K.

    1982-01-01

    The assessment of the activation of the otolith gravitoinertial sensors in the vestibular system of the inner ear may be accomplished by observing the occular counterrolling (OCR) movements which rotate the eyes about the line of sight. A method is presented for the continuous measurement of OCR by means of polarized light, a system of polarizers, and a contact lens. A polarized hard contact lens is placed between two soft lenses before application to the eye, and the measured phase difference between the incident rotating polarized light and the reflected light from this lens provides readings uncontaminated by other eye movement modes.

  10. Time-resolved optical spectroscopy measurements of shocked liquid deuterium

    NASA Astrophysics Data System (ADS)

    Bailey, J. E.; Knudson, M. D.; Carlson, A. L.; Dunham, G. S.; Desjarlais, M. P.; Hanson, D. L.; Asay, J. R.

    2008-10-01

    Time-resolved optical spectroscopy has been used to measure the shock pressure steadiness, emissivity, and temperature of liquid deuterium shocked to 22-90 GPa. The shock was produced using magnetically accelerated flyer plate impact, and spectra were acquired with a suite of four fiber-optic-coupled spectrometers with streak camera detectors. The shock pressure changes by an average of -1.2% over the 10-30 ns cell transit time, determined from the relative changes in the shock front self-emission with time. The shock front reflectivity was measured from 5140Å and 5320Å laser light reflected from the D2 shock. The emissivity inferred from the reflectivity measurements was in reasonably good agreement with quantum molecular dynamics simulation predictions. The spectral radiance wavelength dependence was found to agree well (average normalized χ2=1.6 ) with a Planckian multiplied by the emissivity. The shock front temperature was determined from the emissivity and the wavelength-dependent shock self-emission. Thirty-seven temperature measurements spanning the 22-90 GPa range were accumulated. The large number of temperature measurements enables a comparison of the scatter in the data with expectations for a Gaussian distribution. This facilitates determination of uncertainties that incorporate both apparatus contributions and otherwise unquantified systematic effects that cause self-emission variations from one experiment to another. Agreement between temperatures determined from the absolute spectral radiance and from the relative shape of the spectrum further substantiates the absence of systematic biases. The weighted mean temperature uncertainties were as low as ±3-4% , enabling the discrimination between competing models for the D2 equation of state (EOS). The temperature results agree well with models that predict a maximum compression of ˜4.4 . Softer models that predict approximately sixfold compression are inconsistent with the data to a very high

  11. Design of a Device for Sky Light Polarization Measurements

    PubMed Central

    Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

    2014-01-01

    Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky. PMID:25196003

  12. [Research on New Type of Spectral Modulation Polarization Measurement Technology].

    PubMed

    Zhao, Jia; Zhou, Feng; Li, Huan; Zhao, Hai-bo

    2015-10-01

    Spectral Modulation Polarization Measurement technology (SMPM) is a new type of polarization modulation technology, with an achromatic /4 retarder, a multiple-order retarder and a polarizer the polarization information of incident light can be encoded into the spectral dimension, sinusoidal which amplitude scales with the degree of the linear polarization and phase scales with the angle of the linear polarization can be acquired directly. With a dedicated algorithm for the modulated spectrum, we can get degree and angle of the linear polarization, spectral information and radiation information of the target. This paper expounds the basic principle of SMPM and concrete implementation scheme is proposed. Demodulation algorithm is designed before experimental platform are set up. Experiment which verified the correctness on the SMPM has carried on. The experimental results show the correctness and feasibility of SMPM. Compared with traditional polarization modulate techniques no moving parts and electronic components are including in this scheme. It's also has the advantages of compact and low mass. We can get all the polarization information through one single measurement rather than get Stokes parameters for further calculations. This study provides a new kind of technological approaches for the development of new space polarization detecting sensor.

  13. Design of a device for sky light polarization measurements.

    PubMed

    Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

    2014-08-14

    Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky.

  14. Polarization Measurements in Photoproduction with CEBAF Large Acceptance Spectrometer

    SciTech Connect

    E. Pasyuk

    2010-05-01

    A significant part of the experimental program in Hall-B of the Jefferson Lab is dedicated to the studies of the structure of baryons. CEBAF Large Acceptance Spectrometer (CLAS), availability of circularly and linearly polarized photon beams and recent addition of polarized targets provides remarkable opportunity for single, double and in some cases triple polarization measurements in photoproduction. An overview of the experiments will be presented.

  15. SAMRAI: A novel variably polarized angle-resolved photoemission beamline in the VUV region at UVSOR-II

    SciTech Connect

    Kimura, Shin-Ichi; Ito, Takahiro; Hosaka, Masahito; Katoh, Masahiro; Sakai, Masahiro; Nakamura, Eiken; Kondo, Naonori; Horigome, Toshio; Hayashi, Kenji; Goto, Tomohiro; Ejima, Takeo; Soda, Kazuo

    2010-05-15

    A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a {+-}18 deg. acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directly led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (h{nu}/{Delta}h{nu}) and photon flux of the monochromator are typically 1x10{sup 4} and 10{sup 12} photons/s, respectively, with a 100 {mu}m exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.

  16. SAMRAI: a novel variably polarized angle-resolved photoemission beamline in the VUV region at UVSOR-II.

    PubMed

    Kimura, Shin-Ichi; Ito, Takahiro; Sakai, Masahiro; Nakamura, Eiken; Kondo, Naonori; Horigome, Toshio; Hayashi, Kenji; Hosaka, Masahito; Katoh, Masahiro; Goto, Tomohiro; Ejima, Takeo; Soda, Kazuo

    2010-05-01

    A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a +/-18 degrees acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directly led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (hnu/Deltahnu) and photon flux of the monochromator are typically 1 x 10(4) and 10(12) photons/s, respectively, with a 100 microm exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.

  17. Genomic evidence for island population conversion resolves conflicting theories of polar bear evolution.

    PubMed

    Cahill, James A; Green, Richard E; Fulton, Tara L; Stiller, Mathias; Jay, Flora; Ovsyanikov, Nikita; Salamzade, Rauf; St John, John; Stirling, Ian; Slatkin, Montgomery; Shapiro, Beth

    2013-01-01

    Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize.

  18. Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution

    PubMed Central

    Cahill, James A.; Green, Richard E.; Fulton, Tara L.; Stiller, Mathias; Jay, Flora; Ovsyanikov, Nikita; Salamzade, Rauf; St. John, John; Stirling, Ian; Slatkin, Montgomery; Shapiro, Beth

    2013-01-01

    Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize. PMID:23516372

  19. NASA's Lunar Polar Ice Prospector, RESOLVE: Mission Rehearsal in Apollo Valley

    NASA Technical Reports Server (NTRS)

    Larson, William E.; Picard, Martin; Quinn, Jacqueline; Sanders, Gerald B.; Colaprete, Anthony; Elphic, Richard C.

    2012-01-01

    After the completion of the Apollo Program, space agencies didn't visit the moon for many years. But then in the 90's, the Clementine and Lunar Prospector missions returned and showed evidence of water ice at the poles. Then in 2009 the Lunar Crater Observation and Sensing Satellite indisputably showed that the Cabeus crater contained water ice and other useful volatiles. Furthermore, instruments aboard the Lunar Reconnaissance Orbiter (LRO) show evidence that the water ice may also be present in areas that receive several days of continuous sunlight each month. However, before we can factor this resource into our mission designs, we must understand the distribution and quantity of ice or other volatiles at the poles and whether it can be reasonably harvested for use as propellant or mission consumables. NASA, in partnership with the Canadian Space Agency (CSA), has been developing a payload to answer these questions. The payload is named RESOLVE. RESOLVE is on a development path that will deliver a tested flight design by the end of 2014. The team has developed a Design Reference Mission using LRO data that has RESOLVE landing near Cabeus Crater in May of2016. One of the toughest obstacles for RESOLVE's solar powered mission is its tight timeline. RESOLVE must be able to complete its objectives in the 5-7 days of available sunlight. The RESOLVE team must be able to work around obstacles to the mission timeline in real time. They can't afford to take a day off to replan as other planetary missions have done. To insure that this mission can be executed as planned, a prototype version of RESOLVE was developed this year and tested at a lunar analog site on Hawaii, known as Apollo Valley, which was once used to train the Apollo astronauts. The RESOLVE team planned the mission with the same type of orbital imagery that would be available from LRO. The simulation team prepositioned a Lander in Apollo Valley with RESOLVE on top mounted on its CSA rover. Then the mission

  20. Polar Wind Measurements with TIDE/PSI and HYDRA on the Polar Spacecraft

    NASA Technical Reports Server (NTRS)

    Su, Y. J.; Horwitz, J. L.; Moore, Thomas E.; Giles, Barbara L.; Chandler, Michael O.; Craven, Paul D.; Chang, S.-W.; Scudder, J.

    1998-01-01

    The Thermal Ion Dynamics Experiment (TIDE) on the POLAR spacecraft has allowed sampling of the three-dimensional ion distributions with excellent energy, angular, and mass resolution. The companion Plasma Source Instrument, when operated, allows sufficient diminution of the electric potential to observe the polar wind at very high altitudes. In this presentation, we will describe the results of polar wind characteristics H+, He+, and 0+ as observed by TIDE at 5000 km and 8 RE altitudes. The relationship of the polar wind parameters with the solar zenith angle and with the day-night distance in the Solar Magnetic coordinate system will also be presented. We will compare these measurements with recent simulations of the photoelectron-driven polar wind using a couple fluid-semikinetic model. In addition, we will compare these polar wind observations with low-energy electrons sampled by the HYDRA experiment on POLAR to examine possible effects of the polar rain and photoelectrons and hopefully explain the large ion outflow velocity variations at POLAR apogee.

  1. Polar Wind Measurements with TIDE/PSI and HYDRA on the Polar Spacecraft

    NASA Technical Reports Server (NTRS)

    Su, Y. J.; Horwitz, J. L.; Moore, Thomas E.; Giles, Barbara L.; Chandler, Michael O.; Craven, Paul D.; Chang, S.-W.; Scudder, J.

    1998-01-01

    The Thermal Ion Dynamics Experiment (TIDE) on the POLAR spacecraft has allowed sampling of the three-dimensional ion distributions with excellent energy, angular, and mass resolution. The companion Plasma Source Instrument, when operated, allows sufficient diminution of the electric potential to observe the polar wind at very high altitudes. In this presentation, we will describe the results of polar wind characteristics H+, He+, and 0+ as observed by TIDE at 5000 km and 8 RE altitudes. The relationship of the polar wind parameters with the solar zenith angle and with the day-night distance in the Solar Magnetic coordinate system will also be presented. We will compare these measurements with recent simulations of the photoelectron-driven polar wind using a couple fluid-semikinetic model. In addition, we will compare these polar wind observations with low-energy electrons sampled by the HYDRA experiment on POLAR to examine possible effects of the polar rain and photoelectrons and hopefully explain the large ion outflow velocity variations at POLAR apogee.

  2. Time-resolved spectropolarimetric observations of polars WX LMi and BY Cam

    NASA Astrophysics Data System (ADS)

    Tutar Özdarcan, D.; Smith, P. S.; Keskin, V.

    2017-07-01

    Time-series spectropolarimetric observations of polar WX LMi and asynchronous polar BY Cam are presented. Magnetic field properties, radial velocities and optical polarization are investigated via consecutive observations with good phase sampling during a single orbital cycle. Both systems are found to have a decentred dipole magnetic field configuration. One of the poles of WX LMi has a field strength of 49 MG, while the other pole may have possible field strengths of 69, 104 or 207 MG, depending on the harmonic numbers of the cyclotron humps observed in the circularly polarized spectrum. For BY Cam, a field strength of 168 MG is found for one of the poles, while field strengths of 70, 160 or 212 MG are possible for the other pole.

  3. Polarization-ratio reflectance measurements in the extreme ultraviolet.

    PubMed

    Brimhall, N; Heilmann, N; Ware, M; Peatross, J

    2009-05-01

    We demonstrate a technique for determining optical constants of materials in the extreme UV from the ratio of p-polarized to s-polarized reflectance. The measurements are based on laser-generated high-order harmonics, which have easily rotatable linear polarization but that are prone to brightness fluctuations and systematic drifts during measurement. Rather than measure the absolute reflectance, we extract the optical constants of a material from the ratio of p-polarized to s-polarized reflectance at multiple incident angles. This has the advantage of dividing out long-term fluctuations and possible systematic errors. We show that the reflectance ratio is as sensitive as the absolute reflectance to material optical properties.

  4. McDONALD OBSERVATORY ARCHIVE OF OPTICAL LINEAR POLARIZATION MEASUREMENTS

    SciTech Connect

    Wills, Beverley J.; Wills, D.; Breger, M.

    2011-06-01

    We present 990 previously unpublished optical linear polarization measurements of quasars, active galactic nuclei, and some stars observed for interstellar polarization. The observations, covering the period 1981-2000, were made with McDonald Observatory's 2.1 m Struve reflector and the Breger photopolarimeter.

  5. Polarization measurements in high-energy deuteron photodisintegration.

    PubMed

    Wijesooriya, K; Afanasev, A; Amarian, M; Aniol, K; Becher, S; Benslama, K; Bimbot, L; Bosted, P; Brash, E; Calarco, J; Chai, Z; Chang, C C; Chang, T; Chen, J P; Choi, S; Chudakov, E; Churchwell, S; Crovelli, D; Dieterich, S; Dumalski, S; Dutta, D; Epstein, M; Fissum, K; Fox, B; Frullani, S; Gao, H; Gao, J; Garibaldi, F; Gayou, O; Gilman, R; Glamazdin, S; Glashausser, C; Gomez, J; Gorbenko, V; Hansen, O; Holt, R J; Hovdebo, J; Huber, G M; de Jager, C W; Jiang, X; Jones, C; Jones, M K; Kelly, J; Kinney, E; Kooijman, E; Kumbartzki, G; Kuss, M; LeRose, J; Liang, M; Lindgren, R; Liyanage, N; Malov, S; Margaziotis, D J; Markowitz, P; McCormick, K; Meekins, D; Meziani, Z E; Michaels, R; Mitchell, J; Morand, L; Perdrisat, C F; Pomatsalyuk, R; Punjabi, V; Ransome, R D; Roche, R; Rvachev, M; Saha, A; Sarty, A; Schulte, E C; Simon, D; Strauch, S; Suleiman, R; Todor, L; Ulmer, P E; Urciuoli, G M; Wojtsekhowski, B; Xiong, F; Xu, W

    2001-04-02

    We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p(y) vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(gamma,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.

  6. Measurements of optical polarization properties in dental tissues and biomaterials

    NASA Astrophysics Data System (ADS)

    Fernández-Oliveras, Alicia; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María M.

    2011-05-01

    Since biological tissues can have the intrinsic property of altering the polarization of incident light, optical polarization studies are important for a complete characterization. We have measured the polarized light scattered off of different dental tissues and biomaterials for a comparative study of their optical polarization property. The experimental setup was composed by a He-Ne laser, two linear polarizers and a detection system based on a photodiode. The laser beam was passed through one linear polarizer placed in front of the sample, beyond which the second linear polarizer (analyzer) and the photodiode detector were placed. First, the maximum laser-light intensity (reference condition) was attained without the sample in the laser path. Then, the sample was placed between the two polarizers and the polarization shift of the scattered laser light was determined by rotating the analyzer until the reference condition was reached. Two dental-resin composites (nanocomposite and hybrid) and two human dental tissues (enamel and dentine) were analyzed under repeatability conditions at three different locations on the sample: 20 measurements of the shift were taken and the average value and the uncertainty associated were calculated. For the human dentine the average value of the polarization shift found was 7 degrees, with an associated uncertainty of 2 degrees. For the human enamel and both dental-resin composites the average shift values were found to be similar to their corresponding uncertainties (2 degrees). The results suggest that although human dentine has notable polarization properties, dental-resin composites and human enamel do not show significant polarization shifts.

  7. Novel polarization-sensitive micropulse lidar measurement technique

    SciTech Connect

    Flynn, Connor J.; Mendoza, Albert; Zheng, Yunhui; Mathur, Savyasachee

    2007-03-19

    Polarization-sensitive detection of elastic backscatter is useful for detection of cloud phase and depolarizing aerosols. The U.S. DOE Atmospheric Radiation Measurements (ARM) Program has deployed micropulse lidar (MPL) for over a decade, but without polarized detection. Adding an actively-controlled liquid crystal retarder provides the capability to identify depolarizing particles by alternately transmitting linearly and circularly polarized light. This represents a departure from established techniques which transmit exclusively linear polarization or exclusively circular polarization. Mueller matrix calculations yield simple relationships between the well-known linear depolarization ratio δlinear, the circular depolarization ratio δcirc, and the hybrid MPL depolarization ratio δMPL. This research was supported by the Office of Biological and Environmental Research of the U.S. Department of Energy as part of the Atmospheric Radiation Measurement Program.

  8. Diffraction and polarization effects in Earth radiation budget measurements.

    PubMed

    Mahan, J R; Barki, A R; Priestley, K J

    2016-12-01

    Thermal radiation emitted and reflected from the Earth and viewed from near-Earth orbit may be characterized by its spectral distribution, its degree of coherence, and its state of polarization. The current generation of broadband Earth radiation budget instruments has been designed to minimize the effect of diffraction and polarization on science products. We used Monte Carlo ray-trace (MCRT) models that treat individual rays as quasi-monochromatic, polarized entities to explore the possibility of improving the performance of such instruments by including measures of diffraction and polarization during calibration and operation. We have demonstrated that diffraction and polarization sensitivity associated with typical Earth radiation budget instrument design features has a negligible effect on measurements.

  9. The First Measurement of Vector Polarization Transfers in the Reaction Polarized Proton - Proton ---> Polarized Deuteron - Positive Pion.

    NASA Astrophysics Data System (ADS)

    Turpin, Stephen Edward

    A novel technique for measuring the vector polarization of scattered deuterons using the stripping reaction was developed and investigated in an experiment at the Clinton P. Anderson Meson Physics Facility (Los Alamos) measuring the vector polarization transfer parameters in the reaction p(' )p (--->) d(' )(pi)('+) at 800 MeV. The parameters P, K(,NN), and combinations of K(,SS) and K(,SL) and of K(,LS) and K(,LL) were measured at 5 angles to a statistical precision of less than 0.08 and with systematic uncertainties less than 0.05.

  10. Polarization-resolved evanescent wave scattering from gold-coated tilted fiber gratings.

    PubMed

    Shen, Changyu; Zhou, Wenjun; Albert, Jacques

    2014-03-10

    The scatterings of TE- and TM-polarized evanescent wave on the surface of a tilted fiber Bragg grating (TFBG) with a 50 nm thick gold coating were investigated experimentally by observing radiation patterns from discontinuities in the coating. The scattering intensity for TM-polarized light is larger than for TE light when the evanescent wave propagates from the coating towards the discontinuity. The opposite occurs for light propagating from an uncoated section towards the coating edge. However in the latter case the scattering is much weaker. These results confirm that cladding modes with TE and TM polarization can be excited selectively with a TFBG, and that they scatter light differentially at discontinuities. These results are used to propose a simple polarimeter design based on total scattered light intensity monitoring.

  11. Field-resolved measurement of reaction-induced spectral densities by polarizability response spectroscopy

    NASA Astrophysics Data System (ADS)

    Moran, Andrew M.; Nome, Rene A.; Scherer, Norbert F.

    2007-11-01

    The experimental design and theoretical description of a novel five-pulse laser spectroscopy is presented with an application to a pyridinium charge transfer complex in acetonitrile and methanol. In field-resolved polarizability response spectroscopy (PORS), an electronically resonant laser pulse first excites a solvated chromophore (reactant) and off-resonant Raman spectra of the resulting nuclear motions are measured as a function of the reaction time. The present apparatus differs from our earlier design by performing the Raman probe measurement (with fixed pulse delays) in the frequency domain. In addition, the full electric fields of the signals are measured by spectral interferometry to separate nonresonant and Raman responses. Our theoretical model shows how the PORS signal arises from nuclear motions that are displaced/driven by the photoinduced reaction. The field-resolved off-resonant (of the solute's electronic transitions) probing favors detection of solvent (as opposed to solute) dynamics coupled to the reaction. The sign of the signal represents the relative strengths of polarization responses associated with the ground and photoexcited solutions. Signatures of nonresonant and PORS signal contributions to the experimental results are analyzed with numerical calculations based on a theoretical model we have developed for reaction-induced PORS. Our model identifies two mechanisms of PORS signal generation: (i) structural relaxation induced resonance; (ii) dephasing induced resonance. In the charge transfer reaction investigated, the solvent-dependent and time-evolving (solvent) polarizability spectral density (PSD) is readily obtained. The general trend of an initial broadband inertial nuclear response followed by a decrease in the linewidth of the PSD establishes that the measured PSD is inconsistent with the approximation of a linear response. Furthermore, the explicit time evolution of the PSD is important for properly describing solvent control of

  12. Polarization lidar measurements of honeybees for locating buried landmines

    NASA Astrophysics Data System (ADS)

    Shaw, Joseph A.; Seldomridge, Nathan L.; Dunkle, Dustin L.; Nugent, Paul W.; Spangler, Lee H.; Churnside, James H.; Wilson, James W.; Bromenshenk, Jerry J.; Henderson, Colin B.

    2005-08-01

    A polarization-sensitive lidar was used to detect honeybees trained to locate buried landmines by smell. Lidar measurements of bee location agree reasonably well with maps of chemical plume strength and bee density determined by visual and video counts, indicating that the bees are preferentially located near the explosives and that the lidar identifies the locations of higher bee concentration. The co-polarized lidar backscatter signal is more effective than the cross-polarized signal for bee detection. Laboratory measurements show that the depolarization ratio of scattered light is near zero for bee wings and up to approximately thirty percent for bee bodies.

  13. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    SciTech Connect

    Kortright, J.B.; Rice, M.; Hussain, Z.

    1997-04-01

    Growing interest in utilizing circular polarization prompted the design of bend-magnet beamline 9.3.2 at the Advanced Light Source, covering the 30-1500 eV spectral region, to include vertical aperturing capabilities for optimizing the collection of circular polarization above and below the orbit plane. After commissioning and early use of the beamline, a multilayer polarimeter was used to characterize the polarization state of the beam as a function of vertical aperture position. This report partially summarizes the polarimetry measurements and compares results with theoretical calculations intended to simulate experimental conditions.

  14. Polarized Reflectance Measurement of Burned Skin Tissues

    NASA Astrophysics Data System (ADS)

    de Pedro, Hector Michael; Chang, Chuan-I.; Zarnani, Faranak; Glosser, Robert; Maas, D.; Idris, A.

    2011-10-01

    In the US, there are over 400,000 burn victims with 3,500 deaths in 2010. Recent evidence suggests that early removal of burn tissues can significantly increase the success of their recovery, since burns continue to spread and damage surrounding tissues after hours of injury. The rationale behind this procedure is that burns trigger the body's immune system to overreact, causing additional damage. Therefore, it is important to distinguish burn areas so that it can be removed. The problem with this is that it is difficult to recognize the margins of the burn area. In our project, we use polarized reflectance as a tool to identify the burned tissues from unburned ones.

  15. Dissection of rovibronic band structure by polarization-resolved degenerate four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Bracamonte, Alfredo E.; Vaccaro, Patrick H.

    2003-07-01

    Judicious selection of polarization characteristics in degenerate four-wave mixing (DFWM) spectroscopy is shown to provide a facile and robust means for discriminating rovibronic features according to their changes in rotational angular momentum, ΔJ. Building upon a perturbative (weak-field) treatment of the resonant DFWM response, theoretical analyses are presented for a collinear arrangement of linearly polarized electromagnetic waves that interact with an isotropic ensemble of gas-phase target molecules. The polarization unit vectors for two input fields (E1 and E3) are presumed to be fixed along the Y-axis (φ1=φ3=π/2), while the remaining incident field (E2) has its orientation within the transverse X-Y plane specified by angular coordinate φ2. For φ2=π/4, complete elimination of high-J Q-branch (ΔJ=0) and P-/R-branch (ΔJ=±1) structure is found to occur when the detected direction of linear polarization is switched between the limiting values of φ4,Q=-18.43° and φ4,P/R=+26.57°, respectively. These predictions are corroborated experimentally by probing the tunneling-split origin region of the tropolone à 1B2-X˜ 1A1 (π*←π) absorption system under ambient, bulk-gas conditions. Other polarization-based schemes for rovibronic branch suppression are discussed as are the effects incurred by (strong-field) optical saturation phenomena. The implementations of DFWM suggested by this work should prove useful for dissecting and unraveling the congested spectra often exhibited by massive polyatomic species.

  16. Polarization-resolved photoluminescence study of individual GaN nanowires grown by catalyst-free molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Schlager, John B.; Sanford, Norman A.; Bertness, Kris A.; Barker, Joy M.; Roshko, Alexana; Blanchard, Paul T.

    2006-05-01

    Polarization- and temperature-dependent photoluminescence (PL) measurements were performed on individual GaN nanowires. These were grown by catalyst-free molecular beam epitaxy on Si(111) substrates, ultrasonically removed, and subsequently dispersed on sapphire substrates. The wires were typically 5-10μm in length, c-axis oriented, and 30-100nm in diameter. Single wires produced sufficient emission intensity to enable high signal-to-noise PL data. Polarized PL spectra differed for the σ and π polarization cases, illustrating the polarization anisotropy of the exciton emission associated with high-quality wurtzite GaN. This anisotropy in PL emission persisted even up to room temperature (4-296K). Additionally, the nanowire PL varied with excitation intensity and with (325nm) pump exposure time.

  17. Characterizing the kinetics of suspended cylindrical particles by polarization measurements

    NASA Astrophysics Data System (ADS)

    Liao, Ran; Ou, Xueheng; Ma, Hui

    2015-09-01

    Polarization has promising potential to retrieve the information of the steady samples, such as tissues. However, for the fast changing sample such as the suspended algae in the water, the kinetics of the particles also influence the scattered polarization. The present paper will show our recent results to extract the information about the kinetics of the suspended cylindrical particles by polarization measurements. The sample is the aqueous suspension of the glass fibers stirred by a magnetic stirrer. We measure the scattered polarization of the fibers by use of a simultaneous polarization measurement system and obtain the time series of two orthogonal polarization components. By use of correlation analysis, we obtain the time parameters from the auto-correlation functions of the polarization components, and observe the changes with the stirring speeds. Results show that these time parameters indicate the immigration of the fibers. After discussion, we find that they may further characterize the kinetics, including the translation and rotation, of the glass fibers in the fluid field.

  18. The laboratory methods of induced polarization measurement of manganese sample

    NASA Astrophysics Data System (ADS)

    Adhiguna, D.; Handayani, G.

    2015-09-01

    Metallic minerals are polarizable. The polarizable property can be used as the basis for metallic minerals exploration process. By use of induced polarization method, we observed polarization phenomenon that occur in metallic material. In this study, physical events were observed that occur in rocks containing manganese minerals using induced polarization method. Induced polarization method is a geophysical method that is based on the principle of electrical charging and discharging of a capacitor which is applied to the rock. By using the method of induced polarization, chargeability values can be determined for the rock. Chargeability is one of the important properties of metal material. Measurement on this research will be done in two different ways to determine the induced events that occurred in both methods.

  19. Polarization dependence of Z-scan measurement: theory and experiment.

    PubMed

    Yan, Xiao-Qing; Liu, Zhi-Bo; Zhang, Xiao-Liang; Zhou, Wen-Yuan; Tian, Jian-Guo

    2009-04-13

    Here we report on an extension of common Z-scan method to arbitrary polarized incidence light for measurements of anisotropic third-order nonlinear susceptibility in isotropic medium. The normalized transmittance formulas of closed-aperture Z-scan are obtained for linearly, elliptically and circularly polarized incidence beam. The theoretical analysis is examined experimentally by studying third-order nonlinear susceptibility of CS2 liquid. Results show that the elliptically polarized light Z-scan method can be used to measure simultaneously the two third-order nonlinear susceptibility components chi(3)(xyyx) and chi(3)(xxyy). Furthermore, the elliptically polarized light Z-scan measurements of large nonlinear phase shift are also analyzed theoretically and experimentally.

  20. Extended wavelength anisotropy resolved multidimensional emission spectroscopy (ARMES) measurements: better filters, validation standards, and Rayleigh scatter removal methods

    NASA Astrophysics Data System (ADS)

    Casamayou-Boucau, Yannick; Ryder, Alan G.

    2017-09-01

    Anisotropy resolved multidimensional emission spectroscopy (ARMES) provides valuable insights into multi-fluorophore proteins (Groza et al 2015 Anal. Chim. Acta 886 133-42). Fluorescence anisotropy adds to the multidimensional fluorescence dataset information about the physical size of the fluorophores and/or the rigidity of the surrounding micro-environment. The first ARMES studies used standard thin film polarizers (TFP) that had negligible transmission between 250 and 290 nm, preventing accurate measurement of intrinsic protein fluorescence from tyrosine and tryptophan. Replacing TFP with pairs of broadband wire grid polarizers enabled standard fluorescence spectrometers to accurately measure anisotropies between 250 and 300 nm, which was validated with solutions of perylene in the UV and Erythrosin B and Phloxine B in the visible. In all cases, anisotropies were accurate to better than ±1% when compared to literature measurements made with Glan Thompson or TFP polarizers. Better dual wire grid polarizer UV transmittance and the use of excitation-emission matrix measurements for ARMES required complete Rayleigh scatter elimination. This was achieved by chemometric modelling rather than classical interpolation, which enabled the acquisition of pure anisotropy patterns over wider spectral ranges. In combination, these three improvements permit the accurate implementation of ARMES for studying intrinsic protein fluorescence.

  1. Intrinsic spin polarized electronic structure of CrO{sub 2} epitaxial film revealed by bulk-sensitive spin-resolved photoemission spectroscopy

    SciTech Connect

    Fujiwara, Hirokazu; Sunagawa, Masanori; Kittaka, Tomoko; Terashima, Kensei; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2015-05-18

    We have performed bulk-sensitive spin-resolved photoemission spectroscopy in order to clarify the intrinsic spin-resolved electronic states of half-metallic ferromagnet CrO{sub 2}. We used CrO{sub 2} epitaxial films on TiO{sub 2}(100), which shows a peak at 1 eV with a clear Fermi edge, consistent with the bulk-sensitive PES spectrum for CrO{sub 2}. In spin-resolved spectra at 40 K, while the Fermi edge was observed in the spin up (majority spin) state, no states at the Fermi level (E{sub F}) with an energy gap of 0.5 eV below E{sub F} were observed in the spin down (minority spin) state. At 300 K, the gap in the spin down state closes. These results are consistent with resistivity measurements and magnetic hysteresis curves of the fabricated CrO{sub 2} film, constituting spectroscopic evidence for the half-metallicity of CrO{sub 2} at low temperature and reducing the spin polarization at room temperature. We also discuss the electron correlation effects of Cr 3d.

  2. Measurement of spin observables using a storage ring with polarized beam and polarized internal gas target

    SciTech Connect

    Lee, K.; Miller, M.A.; Smith, A.; Hansen, J.; Bloch, C.; van den Brand, J.F.J.; Bulten, H.J.; Ent, R.; Goodman, C.D.; Jacobs, W.W.; Jones, C.E.; Korsch, W.; Leuschner, M.; Lorenzon, W.; Marchlenski, D.; Meyer, H.O.; Milner, R.G.; Neal, J.S.; Pancella, P.V.; Pate, S.F.; Pitts, W.K.; von Przewoski, B.; Rinckel, T.; Sowinski, J.; Sperisen, F.; Sugarbaker, E.; Tschalaer, C.; Unal, O.; Zhou, Z. Indiana University Cyclotron Facility, Bloomington, Indiana 47405 MIT-Bates Linear Accelerator Center and Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 University of Wisconsin enMadison, Madison, Wisconsin 53706 The Ohio State University, Columbus, Ohio 43210 Western Michigan University, Kalamazoo, Michigan 49007 )

    1993-02-08

    We report the first measurement of analyzing powers and spin correlation parameters using a storage ring with both beam and internal target polarized. Spin observables were measured for elastic scattering of 45 and 198 MeV protons from polarized [sup 3]He nuclei in a new laser-pumped internal gas target at the Indiana University Cyclotron Facility Cooler Ring. Scattered protons and recoil [sup 3]He nuclei were detected in coincidence with large acceptance plastic scintillators and silicon detectors. The internal-target technique demonstrated in this experiment has broad applicability to the measurement of spin-dependent scattering in nuclear and particle physics.

  3. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    SciTech Connect

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  4. Horizontally resolved structures of polar mesospheric echoes obtained with the Middle Atmosphere Alomar Radar System

    NASA Astrophysics Data System (ADS)

    Latteck, Ralph; Zecha, Marius; Rapp, Markus; Stober, Gunter; Singer, Werner

    2012-07-01

    Polar Mesosphere Summer Echoes have been observed in Andenes/Norway (69°N, 16°E) for more than 18 years using the Alomar SOUSY and the ALWIN VHF radars. In 2011 the Leibniz-Institute of Atmospheric Physics in Kühlungsborn completed the installation of the Middle Atmosphere Alomar Radar System ({MAARSY}). The new radar is designed for atmospheric studies from the troposphere up to the lower thermosphere, especially for the investigation of horizontal structures of polar mesospheric echoes. The system is composed of an active phased antenna consisting of 433 array elements and an identical number of transceiver modules individually controllable in frequency, phase, and output power on a pulse-to-pulse basis. This arrangement allows very high flexibility of beam forming and beam steering with a symmetric 3.6° small radar beam and arbitrary beam pointing directions down to 30° off-zenith. The monitoring of polar mesosphere echoes using a vertical pointed radar beam has been continued already during the construction period of MAARSY in order to complete the long term data base available for Andenes. Additionally first multi-beam scanning experiments using up to 97 beams quasi-simultaneously in the mesosphere have been carried out during several campaigns starting in summer 2010. Sophisticated wind analysis methods such as an extended velocity azimuth display have been applied to retrieve additional parameters from the wind field, e.g. horizontal divergence, vertical velocity, stretching and shearing deformation. The results provide a first insight into the strong horizontal variability of scattering structures occurring in the polar mesosphere over Andenes during summer and winter time. The implementation of interferometric radar imaging methods offers further improvement of the horizontal and the vertical resolution.

  5. A Rotating Source Polarization Measurement Technique Using Two Circularly Polarized Antennas

    DTIC Science & Technology

    2016-07-15

    level opposite polarization signal. However, the DFT resolution can be artificially increased by appending to the measured data, precisely M-1 copies... appending to the original data M − 1 copies of the measurements. The expanded data set es21 contains MN samples, that is es21(n+Nm) = s21(n), n = 1, 2

  6. Liquid temperature measurement method in microchannels by using fluorescence polarization

    NASA Astrophysics Data System (ADS)

    Tatsumi, Kazuya; Hsu, Chi Hsuan; Suzuki, Atsushi; Nakabe, Kazuyoshi

    2017-07-01

    A novel optical method that can measure fluid temperature at the microscopic scale by measuring fluorescence polarization is described in this paper. The measurement is much less influenced by fluorescence quenching effects, which is a significant issue in conventional laser-induced fluorescence methods. Therefore, the effects of the other properties of the fluid can be reduced considerably in the proposed method, thus has the potential of leading to greater reliability in measuring the temperature. An experiment was performed in a microchannel flow by using fluorescent molecule probes. The relationship between the fluid temperature and the measured fluorescence polarization degree is evaluated to derive the correlation curve. In addition, the effects of the fluid viscosity and fluid pH on the fluorescence polarization degree are discussed to evaluate the influence of the quenching effects. The results showed that the fluorescence polarization is considerably less sensitive to the quenching factors as compared with the fluorescence intensity measurements. Furthermore, a strong linear correlation between the polarization degree and the fluid temperature was obtained. This relationship agreed well with the theoretical one qualitatively and confirmed the validity of the measurements and feasibility of the proposed method.

  7. Preferential alignment of birefringent tissue measured with polarization sensitive techniques

    NASA Astrophysics Data System (ADS)

    Ramella-Roman, J. C.; Ruiz, T.; Ghassemi, P.; Travis, T. E.; Shupp, J. W.; Chue-Sang, J.; Bai, Y.

    2015-02-01

    Assessing collagen alignment is of interest when evaluating a therapeutic strategy and evaluating its outcome in scar management. In this work we introduce a theoretical and experimental methodology for the quantification of collagen and birefringent media alignment based on polarized light transport. The technique relies on the fact that these materials exhibit directional anisotropy. A polarized Monte Carlo model and a spectro-polarimetric imaging system were devised to predict and measure the impact of birefringence on an impinging polarized light beam. Experiments conducted on birefringent phantoms, and biological samples consisting of highly packed parallel birefringent fibers, showed a good agreement with the analytical results.

  8. Radiation measurements from polar and geosynchronous satellites

    NASA Technical Reports Server (NTRS)

    Vonderhaar, T. H.

    1973-01-01

    During the 1960's, radiation budget measurements from satellites have allowed quantitative study of the global energetics of our atmosphere-ocean system. A continuing program is planned, including independent measurement of the solar constant. Thus far, the measurements returned from two basically different types of satellite experiments are in agreement on the long term global scales where they are most comparable. This fact, together with independent estimates of the accuracy of measurement from each system, shows that the energy exchange between earth and space is now measured better than it can be calculated. Examples of application of the radiation budget data were shown. They can be related to the age-old problem of climate change, to the basic question of the thermal forcing of our circulation systems, and to the contemporary problems of local area energetics and computer modeling of the atmosphere.

  9. Measuring the influence of aerosols and albedo on sky polarization.

    PubMed

    Kreuter, A; Emde, C; Blumthaler, M

    2010-11-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

  10. Measuring the influence of aerosols and albedo on sky polarization

    PubMed Central

    Kreuter, A.; Emde, C.; Blumthaler, M.

    2010-01-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05–0.5 and 0.1–0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error. PMID:24068851

  11. Temporally resolved plasma composition measurements by collective Thomson scattering in TEXTOR (invited)

    SciTech Connect

    Stejner, M.; Korsholm, S. B.; Nielsen, S. K.; Salewski, M.; Leipold, F.; Michelsen, P. K.; Meo, F.; Bindslev, H.; Moseev, D.; Buerger, A.; Kantor, M.; Baar, M. de

    2012-10-15

    Fusion plasma composition measurements by collective Thomson scattering (CTS) were demonstrated in recent proof-of-principle measurements in TEXTOR [S. B. Korsholm et al., Phys. Rev. Lett. 106, 165004 (2011)]. Such measurements rely on the ability to resolve and interpret ion cyclotron structure in CTS spectra. Here, we extend these techniques to enable temporally resolved plasma composition measurements by CTS in TEXTOR, and we discuss the prospect for such measurements with newly installed hardware upgrades for the CTS system on ASDEX Upgrade.

  12. Radiation measurements from polar and geosynchronous satellites

    NASA Technical Reports Server (NTRS)

    Vonderhaar, T. H.

    1971-01-01

    Measurements of the earth's radiation budget, its climatology and its interannual variation, are described briefly. In addition, preliminary results are given on ocean energy transports, specific large scale and local radiation budget anamolies, and studies of the separate radiation budgets of the atmosphere and ocean. Initial work in preparation for additional radiation budget measurements from EOS and ATS satellites is described. A radiation budget system simulation program and several smaller projects (including a radiance normalization technique) are also mentioned. First annual global maps of the earth's radiation budget as measured from Nimbus 3 are included.

  13. A new measurement of electron transverse polarization in polarized nuclear β-decay

    NASA Astrophysics Data System (ADS)

    Kawamura, H.; Akiyama, T.; Hata, M.; Hirayama, Y.; Ikeda, M.; Ikeda, Y.; Ishii, T.; Kameda, D.; Mitsuoka, S.; Miyatake, H.; Nagae, D.; Nakaya, Y.; Ninomiya, K.; Nitta, M.; Ogawa, N.; Onishi, J.; Seitaibashi, E.; Tanaka, S.; Tanuma, R.; Totsuka, Y.; Toyoda, T.; Watanabe, Y. X.; Murata, J.

    2017-03-01

    The Mott polarimetry for T-violation (MTV) experiment tests time-reversal symmetry in polarized nuclear β-decay by measuring an electron’s transverse polarization as a form of angular asymmetry in Mott scattering using a thin metal foil. A Mott scattering analyzer system developed using a tracking detector to measure scattering angles offers better event selectivity than conventional counter experiments. In this paper, we describe a pilot experiment conducted at KEK-TRIAC using a prototype system with a polarized 8Li beam. The experiment confirmed the sound performance of our Mott analyzer system to measure T-violating triple correlation (R correlation), and therefore recommends its use in higher-precision experiments at the TRIUMF-ISAC.

  14. POLVSM (Polarized Volume Scattering Meter) instrument: an innovative device to measure the directional and polarized scattering properties of hydrosols.

    PubMed

    Chami, Malik; Thirouard, Alexandre; Harmel, Tristan

    2014-10-20

    An innovative instrument dedicated to the multispectral measurements of the directional and polarized scattering properties of the hydrosols, so-called POLVSM, is described. The instrument could be used onboard a ship, as a benchtop instrument, or at laboratory. The originality of the POLVSM concept relies on the use of a double periscopic optical system whose role is (i) to separate the plane containing the light source from the scattering plane containing the sample and the receiver and (ii) to prevent from any specularly reflected light within the sample chamber. As a result, a wide range of scattering angle, namely from 1° to 179°, is covered by the detector. Another originality of the instrument is to measure the Mueller scattering matrix elements, including the degree of polarization. A relevant calibration procedure, which could be of great interest as well for other instruments, is proposed to convert the raw data into physical units. The relative uncertainty in POLVSM data was determined at ± 4.3%. The analysis of measurements of the volume scattering function and degree of polarization performed under controlled conditions for samples dominated either by inorganic hydrosols or phytoplankton monospecific species showed a good consistency with literature, thus confirming the good performance of the POLVSM device. Comparisons of POLVSM data with theoretical calculations showed that Mie theory could reproduce efficiently the measurements of the VSF and degree of polarization for the case of inorganic hydrosols sample, despite the likely non sphericity of these particles as revealed by one of the element of the Mueller matrix. Our results suggested as well that a sophisticated modeling of the heterogeneous internal structure of living cells, or at least, the use of layered sphere models, is needed to correctly predict the directional and polarized effects of phytoplankton on the oceanic radiation. The relevance of performing angularly resolved measurements

  15. Radiation measurements from polar and geosynchronous satellites

    NASA Technical Reports Server (NTRS)

    Vonderhaar, T. H.; Kidder, S. Q.; Hillger, D. W.; Ellis, J. S.

    1978-01-01

    The following topics are discussed: (1) cloud effects in climate determination; (2) annual variation in the global heat balance of the earth; (3) the accuracy of precipitation estimates made from passive microwave measurements from satellites; (4) seasonal oceanic precipitation frequencies; (5) determination of mesoscale temperature and moisture fields over land from satellite radiance measurements; and (6) Nimbus 6 scanning microwave spectrometer data evaluation for surface wind and pressure components in tropical storms.

  16. [Accuracy analysis on a sort of polarized measurement in remote sensing].

    PubMed

    Chen, Li-gang; Hong, Jin; Qiao, Yan-li; Sun, Xiao-bing; Wang, Yuan-jun

    2008-10-01

    Angular error of polarizer in polarimetric measurement is an important element affecting the measurement accuracy of degree of polarization, so angular error of polarizer should be considered in remote sensing of high-accuracy quantitative polarization. Simulation study shows that polarimetric measurement is relative to the polarization state (polarization angle or degree of polarization) of incident light in a specific measurement system of polarization. In the measurement mode of polarizer setting (0 degree, 60 degrees, 120 degrees), there is a maximum error of polarization measurement at the 0 degree or 180 degrees polarization angle while a minimum error at the 30 degrees, 90 degrees and 150 degrees polarization angle; In the measurement mode of polarizer setting (0 degree, 45 degrees, 90 degrees), there is a maximum error of polarization measurement near the 45 degrees polarization angle while a minimum error at the 0 degree, 90 degrees and 135 degrees polarization angle. The larger degree of polarization of incident light often contributes to the bigger measurement error except for incident light with several polarization angles. So the polarization measurement may be evaluated by the average degree of polarizatioo of linearly polarized light introduced in this paper. It is indicated that the measurement mode of polarizer setting (0 degree, 60 degrees, 120 degrees) is better than that of (0 degree, 45 degrees, 90 degrees).

  17. Apparatus and method for measuring electrostatic polarization

    DOEpatents

    Hahn, Erwin L.; Clarke, John; Sloater, Tycho; Hilbert, Claude; Heaney, Michael B.

    1989-01-01

    An apparatus and method for measuring the electric properties of solid matter which provides data for determining the polarizability of the electron distributions contained therein is disclosed. A sample of the solid to be studied is placed between the plates of a capacitor where it acts as a dielectric. The sample is excited by the interaction of electromagnetic radiation with an atomic species contained in the sample. The voltage induced across the capacitor is then measured as a function of time with the aid of a high Q circuit tuned to a frequency related to the frequency of the applied electromagnetic energy.

  18. Polarization and position measurements of Type III bursts

    NASA Technical Reports Server (NTRS)

    Suzuki, S.; Sheridan, K. V.; Dulk, G. A.

    1980-01-01

    The positional and polarization characteristics of Type III bursts in the range 24-220 MHz as measured by the Culgoora radioheliograph, spectrograph and spectropolarimeter are reported. The study includes 997 bursts which are of two classes: fundamental-harmonic (F-H) pairs and 'structureless' bursts with no visible F-H structure, and concentrates on the polarization of the bursts and the variation of polarization from centre to limb. The observed centre-to-limb decrease in polarization approximately follows a cosine law. This decrease is not as predicted by simple theory but is consistent with other observations which imply that open field lines from an active region diverge strongly. The observed o-mode polarization of harmonic radiation implies that the wave vectors of Langmuir waves are always parallel, within about 20 deg, to the magnetic field, while the constancy of H polarization with frequency implies that the ratio of gyromagnetic to plasma frequency, the Alfven speed and the plasma beta are constant with height on the open field lines above an active region. Finally, it is inferred that some factor, in addition to the magnetic field strength, controls the polarization of F radiation.

  19. Process and apparatus for measuring degree of polarization and angle of major axis of polarized beam of light

    DOEpatents

    Decker, Derek E.; Toeppen, John S.

    1994-01-01

    Apparatus and process are disclosed for calibrating measurements of the phase of the polarization of a polarized beam and the angle of the polarized optical beam's major axis of polarization at a diagnostic point with measurements of the same parameters at a point of interest along the polarized beam path prior to the diagnostic point. The process is carried out by measuring the phase angle of the polarization of the beam and angle of the major axis at the point of interest, using a rotatable polarizer and a detector, and then measuring these parameters again at a diagnostic point where a compensation apparatus, including a partial polarizer, which may comprise a stack of glass plates, is disposed normal to the beam path between a rotatable polarizer and a detector. The partial polarizer is then rotated both normal to the beam path and around the axis of the beam path until the detected phase of the beam polarization equals the phase measured at the point of interest. The rotatable polarizer at the diagnostic point may then be rotated manually to determine the angle of the major axis of the beam and this is compared with the measured angle of the major axis of the beam at the point of interest during calibration. Thereafter, changes in the polarization phase, and in the angle of the major axis, at the point of interest can be monitored by measuring the changes in these same parameters at the diagnostic point.

  20. Effect of noise on Frequency-Resolved Optical Gating measurements of ultrashort pulses

    SciTech Connect

    Fittinghoff, D.N.; DeLong, K.W.; Ladera, C.L.; Trebino, R.

    1995-02-01

    We study the effects of noise in Frequency-Resolved Optical Gating measurements of ultrashort pulses. We quantify the measurement accuracy in the presence of additive, muliplicative, and quantization noise, and discuss filtering and pre-processing of the data.

  1. SIMULTANEOUS MEASUREMENT OF CIRCULAR DICHROISM AND FLUORESCENCE POLARIZATION ANISOTROPY.

    SciTech Connect

    SUTHERLAND,J.C.

    2002-01-19

    Circular dichroism and fluorescence polarization anisotropy are important tools for characterizing biomolecular systems. Both are used extensively in kinetic experiments involving stopped- or continuous flow systems as well as titrations and steady-state spectroscopy. This paper presents the theory for determining circular dichroism and fluorescence polarization anisotropy simultaneously, thus insuring the two parameters are recorded under exactly the same conditions and at exactly the same time in kinetic experiments. The approach to measuring circular dichroism is that used in almost all conventional dichrographs. Two arrangements for measuring fluorescence polarization anisotropy are described. One uses a single fluorescence detector and signal processing with a lock-in amplifier that is similar to the measurement of circular dichroism. The second approach uses classic ''T'' format detection optics, and thus can be used with conventional photon-counting detection electronics. Simple extensions permit the simultaneous measurement of the absorption and excitation intensity corrected fluorescence intensity.

  2. Measurement of Small Optical Polarization Rotations

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2009-01-01

    When data with and without an optically active sample are acquired simultaneously while one manually rotates the analyser, the graph of the first signal versus the second one is an ellipse whose shape shows the phase shift between the two signals; this shift is twice the optical rotation. There is no need to measure the rotation of the analyser or…

  3. Measurement of Small Optical Polarization Rotations

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2009-01-01

    When data with and without an optically active sample are acquired simultaneously while one manually rotates the analyser, the graph of the first signal versus the second one is an ellipse whose shape shows the phase shift between the two signals; this shift is twice the optical rotation. There is no need to measure the rotation of the analyser or…

  4. CIV Polarization Measurements Using a Vacuum Ultraviolet Fabry Perot

    NASA Technical Reports Server (NTRS)

    West, Edward A.

    2009-01-01

    Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry Perot that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Perot.

  5. Polarization-resolved simulations of multiple-order rainbows using realistic raindrop shapes

    NASA Astrophysics Data System (ADS)

    Haußmann, Alexander

    2016-05-01

    This paper presents selected results of a simulation study of the first five (primary-quinary) rainbow orders based on a realistic, size-dependent shape model for falling raindrops, taking into account that the drops' bottom part is flattened to higher degree than the dome-like top part. Moreover, broad drop size distributions are included in the simulations, as it is one goal of this paper to analyze, whether the predicted amplification and attenuation patterns for higher-order rainbows, as derived from previous simulations with monodisperse drop sizes, will still be pronounced under the conditions of natural rainfall. Secondly, deviations of the multiple rainbow orders' polarization state from the reference case of spherical drops are discussed. It is shown that each rainbow order may contain a small amount of circularly polarized light due to total internal reflections. Thirdly, it is investigated, how the conditions that generate twinned primary rainbows will affect the higher orders. For the simulations, geometric-optic ray tracing of the full Stokes vector as well as an approximate approach using appropriately shifted Debye series data is applied.

  6. Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements.

    PubMed

    Olivier, Michel; Gagnon, Marc-Daniel; Habel, Joé

    2016-02-28

    When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

  7. Hubble Space Telescope NICMOS Polarization Measurements of OMC-1

    NASA Technical Reports Server (NTRS)

    Simpson, Janet P.; Colgan, Sean W. J.; Erickson, Edwin F.; Burton, Michael G.; Schultz, A. S. B.

    2006-01-01

    We present 2 micrometer polarization measurements of positions in the BN region of the Orion Molecular Cloud (OMC-1) made with NICMOS Camera 2 (0.2" resolution) on Hubble Space Telescope. Our goals are to seek the sources of heating for IRc2, 3, 4, and 7, identify possible young stellar objects (YSOs), and characterize the grain alignment in the dust clouds along the lines-of-sight to the stars. Our results are as follows: BN is approximately 29% polarized by dichroic absorption and appears to be the illuminating source for most of the nebulosity to its north and up to approximately 5" to its south. Although the stars are probably all polarized by dichroic absorption, there are a number of compact, but non-point-source, objects that could be polarized by a combination of both dichroic absorption and local scattering of star light. We identify several candidate YSOs, including an approximately edge-on bipolar YSO 8.7" east of BN, and a deeply-embedded IRc7, all of which are obviously self-luminous at mid-infrared wavelengths and may be YSOs. None of these is a reflection nebula illuminated by a star located near radio source I, as was previously suggested. Other IRc sources are clearly reflection nebulae: IRc3 appears to be illuminated by IRc2-B or a combination of the IRc2 sources, and IRc4 and IRc5 appear to be illuminated by an unseen star in the vicinity of radio source I, or by Star n or IRc2-A. Trends in the magnetic field direction are inferred from the polarization of the 26 stars that are bright enough to be seen as NICMOS point sources. Their polarization ranges from N less than or equal to 1% (all stars with this low polarization are optically visible) to greater than 40%. The most polarized star has a polarization position angle different from its neighbors by approximately 40 degrees, but in agreement with the grain alignment inferred from millimeter polarization measurements of the cold dust cloud in the southern part of OMC-1. The polarization

  8. Traceability study of optical fiber degree of polarization (DOP) measurement

    NASA Astrophysics Data System (ADS)

    Xu, Nan; Li, Jianwei; Li, Jian; Zhang, Zhixin

    2013-09-01

    Degree of polarization (DOP) is an important physical quantity for describing the optical polarization effect and is widely applied in optical fiber communication, optical fiber gyro and the related technologies. Currently, the optical polarization degree tester for the purpose of communication uses mainly two kinds of measurement methods: Stokes vector method and extremum method. At present, there isn't a standard to measure the accuracy and consistency of DOP parameter measurement by the devices listed above, affecting seriously the application of DOP parameter measurement in the fields of optical fiber gyro and optical fiber communication. So, it is urgent to table the accurate guarantees to trace the source of quantitative values of the DOP measuring devices and testers. In this paper, the polarization beam combination method is raised to research and manufacture the standard optical fiber light source device with the variable DOP, and an indicated error measurement has been conducted for a DOP meter. A kind of standard optical fiber light source device that uses a single light source to realize the variable DOP is put forward. It is used to provide the accurate and variable optical fiber polarization degree light with a scope of 0~100%. It is used to calibrate the DOP meters and widely applied in the field of national defense and optical communication fields. By using the standard optical power meter, DOP value by which the optical power meter calculates the optical signal can be measured, which will be used ultimately for calibration of the DOP meter. A measurement uncertainty of 0.5% is obtained using the polarization beam combination method.

  9. Measuring the Polarized CMB with ACT

    NASA Astrophysics Data System (ADS)

    Staggs, Suzanne

    2016-06-01

    The Atacama Cosmology Telescope is a special-purpose 6m telescope designed for cosmic microwave background (CMB) measurements at arcminute resolution. We will describe recent results using the second-generation camera called ACTPol. The camera comprises three sets of optics and detectors. Two operate at 150 GHz, and the third is the first multichroic detector array deployed for the CMB. The latter operates at 90 and 150 GHz.

  10. Spectroscopic ellipsometer based on direct measurement of polarization ellipticity

    SciTech Connect

    Watkins, Lionel R.

    2011-06-20

    A polarizer-sample-Wollaston prism analyzer ellipsometer is described in which the ellipsometric angles {psi} and {Delta} are determined by direct measurement of the elliptically polarized light reflected from the sample. With the Wollaston prism initially set to transmit p- and s-polarized light, the azimuthal angle P of the polarizer is adjusted until the two beams have equal intensity. This condition yields {psi}={+-}P and ensures that the reflected elliptically polarized light has an azimuthal angle of {+-}45 deg. and maximum ellipticity. Rotating the Wollaston prism through 45 deg. and adjusting the analyzer azimuth until the two beams again have equal intensity yields the ellipticity that allows {Delta} to be determined via a simple linear relationship. The errors produced by nonideal components are analyzed. We show that the polarizer dominates these errors but that for most practical purposes, the error in {psi} is negligible and the error in {Delta} may be corrected exactly. A native oxide layer on a silicon substrate was measured at a single wavelength and multiple angles of incidence and spectroscopically at a single angle of incidence. The best fit film thicknesses obtained were in excellent agreement with those determined using a traditional null ellipsometer.

  11. Measuring political polarization: Twitter shows the two sides of Venezuela

    NASA Astrophysics Data System (ADS)

    Morales, A. J.; Borondo, J.; Losada, J. C.; Benito, R. M.

    2015-03-01

    We say that a population is perfectly polarized when divided in two groups of the same size and opposite opinions. In this paper, we propose a methodology to study and measure the emergence of polarization from social interactions. We begin by proposing a model to estimate opinions in which a minority of influential individuals propagate their opinions through a social network. The result of the model is an opinion probability density function. Next, we propose an index to quantify the extent to which the resulting distribution is polarized. Finally, we apply the proposed methodology to a Twitter conversation about the late Venezuelan president, Hugo Chávez, finding a good agreement between our results and offline data. Hence, we show that our methodology can detect different degrees of polarization, depending on the structure of the network.

  12. Verdet constant dispersion measurement using polarization-stepping techniques.

    PubMed

    Flores, Jorge L; Ferrari, José A

    2008-08-20

    We present a novel method for measuring the Verdet constant dispersion. The proposed method involves spectral polarimetric measurements using three (or more) polarization steps. The procedure has formal similarity with the phase-shifting interferometry (PSI). Thus the Verdet constant in the desired spectral range can be retrieved using well-known PSI algorithms. Validation experiments are presented.

  13. First Steps in Tensor Polarization Measurement using the DMR Lineshape

    NASA Astrophysics Data System (ADS)

    Keller, Dustin

    2016-02-01

    The first steps to investigate the tensor polarization measurement with uncertainty is outlined. The objective is to look into possible measurements of the deuteron alignment given an arbitrary lineshape that was distorted by a modulated RF field of know frequency range with respect to each absorption line.

  14. X-ray Polarization Measurements at Relativistic Laser Intensities

    SciTech Connect

    Beiersdorfer, P; Shepherd, R; Mancini, R C; Chen, H; Dunn, J; Keenan, R; Kuba, J; Patel, P K; Ping, Y; Price, D F; Widmann, K

    2004-03-20

    An effort has been started to measure the short pulse laser absorption and energy partition at relativistic laser intensities up to 10{sup 21} W/cm{sup 2}. Plasma polarization spectroscopy is expected to play an important role in determining fast electron generation and measuring the electron distribution function.

  15. Determination of the absolute carrier-envelope phase by angle-resolved photoelectron spectra of Ar by intense circularly polarized few-cycle pulses

    NASA Astrophysics Data System (ADS)

    Fukahori, Shinichi; Ando, Toshiaki; Miura, Shun; Kanya, Reika; Yamanouchi, Kaoru; Rathje, Tim; Paulus, Gerhard G.

    2017-05-01

    The angle-resolved photoelectron spectra of Ar are recorded using intense circularly polarized near-infrared few-cycle laser pulses, and the effect of the depletion of Ar atoms by the ionization and the effect of the Coulombic potential are examined by the classical trajectory Monte Carlo simulations. On the basis of the comparison between the experimental and theoretical photoelectron spectra, a procedure for estimating the absolute carrier-envelope phase (CEP) of the few-cycle laser pulses interacting with atoms and molecules is proposed. It is confirmed that the absolute CEP can securely be estimated without any numerical calculations once the angular distribution of the yield of photoelectrons having the kinetic energy larger than 30 eV is measured with the peak laser intensity in the range between 1 ×1014 and 5 ×1014W /c m2 .

  16. Measurement of polarization with the Degree Angular Scale Interferometer.

    PubMed

    Leitch, E M; Kovac, J M; Pryke, C; Carlstrom, J E; Halverson, N W; Holzapfel, W L; Dragovan, M; Reddall, B; Sandberg, E S

    Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was approximately 400,000 years old. The three most fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station.

  17. Measurement of polarization with the Degree Angular Scale Interferometer

    NASA Astrophysics Data System (ADS)

    Leitch, E. M.; Kovac, J. M.; Pryke, C.; Carlstrom, J. E.; Halverson, N. W.; Holzapfel, W. L.; Dragovan, M.; Reddall, B.; Sandberg, E. S.

    2002-12-01

    Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was ~400,000 years old. The three most fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station.

  18. Calculation of the vibrationally resolved, circularly polarized luminescence of d-camphorquinone and (S,S)-trans-beta-hydrindanone.

    PubMed

    Pritchard, Benjamin; Autschbach, Jochen

    2010-08-02

    Circularly polarized luminescence (CPL), the differential emission of left- and right-handed circularly polarized light from a molecule, is modeled by using time-dependent density functional theory. Calculations of the CPL spectra for the first electronic excited states of d-camphorquinone and (S,S)-trans-beta-hydrindanone under the Franck-Condon approximation and using various functionals are presented, as well as calculations of absorption, emission, and circular dichroism spectra. The functionals B3LYP, BHLYP, and CAM-B3LYP are employed, along with the TZVP and aug-cc-pVDZ Gaussian-type basis sets. For the lowest-energy transitions, all functionals and basis sets perform comparably, with the long-range-corrected CAM-B3LYP better reproducing the excitation energy of camphorquinone but leading to a blue shift with respect to experiment for hydrindanone. The vibrationally resolved spectra of camphorquinone are very well reproduced in terms of peak location, widths, shapes, and intensities. The spectra of hydrindanone are well reproduced in terms of overall envelope shape and width, as well as the lack of prominent vibrational structure in the emission and CPL spectra. Overall the simulated spectra compare well with experiment, and reproduce the band shapes, emission red shifts, and presence or absence of visible vibrational fine structure.

  19. Very efficient spin polarization analysis (VESPA): new exchange scattering-based setup for spin-resolved ARPES at APE-NFFA beamline at Elettra.

    PubMed

    Bigi, Chiara; Das, Pranab K; Benedetti, Davide; Salvador, Federico; Krizmancic, Damjan; Sergo, Rudi; Martin, Andrea; Panaccione, Giancarlo; Rossi, Giorgio; Fujii, Jun; Vobornik, Ivana

    2017-07-01

    Complete photoemission experiments, enabling measurement of the full quantum set of the photoelectron final state, are in high demand for studying materials and nanostructures whose properties are determined by strong electron and spin correlations. Here the implementation of the new spin polarimeter VESPA (Very Efficient Spin Polarization Analysis) at the APE-NFFA beamline at Elettra is reported, which is based on the exchange coupling between the photoelectron spin and a ferromagnetic surface in a reflectometry setup. The system was designed to be integrated with a dedicated Scienta-Omicron DA30 electron energy analyzer allowing for two simultaneous reflectometry measurements, along perpendicular axes, that, after magnetization switching of the two targets, allow the three-dimensional vectorial reconstruction of the spin polarization to be performed while operating the DA30 in high-resolution mode. VESPA represents the very first installation for spin-resolved ARPES (SPARPES) at the Elettra synchrotron in Trieste, and is being heavily exploited by SPARPES users since autumn 2015.

  20. Monochromatic Measurements of the JPSS-1 VIIRS Polarization Sensitivity

    NASA Technical Reports Server (NTRS)

    McIntire, Jeff; Moyer, David; Brown, Steven W.; Lykke, Keith R.; Waluschka, Eugene; Oudrari, Hassan; Xiong, Xiaoxiong

    2016-01-01

    Polarization sensitivity is a critical property that must be characterized for spaceborne remote sensing instruments designed to measure reflected solar radiation. Broadband testing of the first Joint Polar-orbiting Satellite System (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS) showed unexpectedly large polarization sensitivities for the bluest bands on VIIRS (centered between 400 and 600 nm). Subsequent ray trace modeling indicated that large diattenuation on the edges of the bandpass for these spectral bands was the driver behind these large sensitivities. Additional testing using the National Institute of Standards and Technologies Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources was added to the test program to verify and enhance the model. The testing was limited in scope to two spectral bands at two scan angles; nonetheless, this additional testing provided valuable insight into the polarization sensitivity. Analysis has shown that the derived diattenuation agreed with the broadband measurements to within an absolute difference of about0.4 and that the ray trace model reproduced the general features of the measured data. Additionally, by deriving the spectral responsivity, the linear diattenuation is shown to be explicitly dependent on the changes in bandwidth with polarization state.

  1. Information On Tropospheric Ozone From Space Borne Polarization Measurements

    NASA Astrophysics Data System (ADS)

    Hasekamp, O. P.; Landgraf, J.

    Tropospheric ozone retrieval from reflectance spectra is an important issue for many current and future satellite instruments.However, it is difficult to distinguish between stratospheric and tropospheric ozone on the basis of reflectance spectra only, because the reflectance is a quantity that is more sensitive to stratospheric ozone than to tro- pospheric ozone. In this paper we show that satellite measurements of the state of polarization of backscattered light contain valuable additional information on tropo- spheric ozone. The reason for this is the high sensitivity of the state of polarization to tropospheric ozone. This is because the state of polarization is most sensitive to ozone at that altitude where most scattering takes place, which is in the troposphere for wavelengths >300 nm. Retrievals performed on synthetic GOME-2 data show that the vertical resolution of the tropospheric ozone profile is significantly improved if a polarization measurement is used in addition to the reflectance spectrum. Prob- lems that are currently encountered in tropospheric ozone retrieval from reflectance spectra may be solved by using additional polarization measurements.

  2. Monochromatic Measurements of the JPSS-1 VIIRS Polarization Sensitivity

    NASA Technical Reports Server (NTRS)

    McIntire, Jeff; Moyer, David; Brown, Steven W.; Lykke, Keith R.; Waluschka, Eugene; Oudrari, Hassan; Xiong, Xiaoxiong

    2016-01-01

    Polarization sensitivity is a critical property that must be characterized for spaceborne remote sensing instruments designed to measure reflected solar radiation. Broadband testing of the first Joint Polar-orbiting Satellite System (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS) showed unexpectedly large polarization sensitivities for the bluest bands on VIIRS (centered between 400 and 600 nm). Subsequent ray trace modeling indicated that large diattenuation on the edges of the bandpass for these spectral bands was the driver behind these large sensitivities. Additional testing using the National Institute of Standards and Technologies Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources was added to the test program to verify and enhance the model. The testing was limited in scope to two spectral bands at two scan angles; nonetheless, this additional testing provided valuable insight into the polarization sensitivity. Analysis has shown that the derived diattenuation agreed with the broadband measurements to within an absolute difference of about0.4 and that the ray trace model reproduced the general features of the measured data. Additionally, by deriving the spectral responsivity, the linear diattenuation is shown to be explicitly dependent on the changes in bandwidth with polarization state.

  3. A high accuracy broadband measurement system for time resolved complex bioimpedance measurements.

    PubMed

    Kaufmann, S; Malhotra, A; Ardelt, G; Ryschka, M

    2014-06-01

    Bioimpedance measurements are useful tools in biomedical engineering and life science. Bioimpedance is the electrical impedance of living tissue and can be used in the analysis of various physiological parameters. Bioimpedance is commonly measured by injecting a small well known alternating current via surface electrodes into an object under test and measuring the resultant surface voltages. It is non-invasive, painless and has no known hazards. This work presents a field programmable gate array based high accuracy broadband bioimpedance measurement system for time resolved bioimpedance measurements. The system is able to measure magnitude and phase of complex impedances under test in a frequency range of about 10-500 kHz with excitation currents from 10 µA to 5 mA. The overall measurement uncertainties stay below 1% for the impedance magnitude and below 0.5° for the phase in most measurement ranges. Furthermore, the described system has a sample rate of up to 3840 impedance spectra per second. The performance of the bioimpedance measurement system is demonstrated with a resistor based system calibration and with measurements on biological samples.

  4. Magnetoelectroluminescence of organic heterostructures: Analytical theory and spectrally resolved measurements

    SciTech Connect

    Liu, Feilong; Kelley, Megan R.; Crooker, Scott A.; Nie, Wanyi; Mohite, Aditya D.; Ruden, P. Paul; Smith, Darryl L.

    2014-12-22

    The effect of a magnetic field on the electroluminescence of organic light emitting devices originates from the hyperfine interaction between the electron/hole polarons and the hydrogen nuclei of the host molecules. In this paper, we present an analytical theory of magnetoelectroluminescence for organic semiconductors. To be specific, we focus on bilayer heterostructure devices. In the case we are considering, light generation at the interface of the donor and acceptor layers results from the formation and recombination of exciplexes. The spin physics is described by a stochastic Liouville equation for the electron/hole spin density matrix. By finding the steady-state analytical solution using Bloch-Wangsness-Redfield theory, we explore how the singlet/triplet exciplex ratio is affected by the hyperfine interaction strength and by the external magnetic field. In order to validate the theory, spectrally resolved electroluminescence experiments on BPhen/m-MTDATA devices are analyzed. With increasing emission wavelength, the width of the magnetic field modulation curve of the electroluminescence increases while its depth decreases. Furthermore, these observations are consistent with the model.

  5. Magnetoelectroluminescence of organic heterostructures: Analytical theory and spectrally resolved measurements

    DOE PAGES

    Liu, Feilong; Kelley, Megan R.; Crooker, Scott A.; ...

    2014-12-22

    The effect of a magnetic field on the electroluminescence of organic light emitting devices originates from the hyperfine interaction between the electron/hole polarons and the hydrogen nuclei of the host molecules. In this paper, we present an analytical theory of magnetoelectroluminescence for organic semiconductors. To be specific, we focus on bilayer heterostructure devices. In the case we are considering, light generation at the interface of the donor and acceptor layers results from the formation and recombination of exciplexes. The spin physics is described by a stochastic Liouville equation for the electron/hole spin density matrix. By finding the steady-state analytical solutionmore » using Bloch-Wangsness-Redfield theory, we explore how the singlet/triplet exciplex ratio is affected by the hyperfine interaction strength and by the external magnetic field. In order to validate the theory, spectrally resolved electroluminescence experiments on BPhen/m-MTDATA devices are analyzed. With increasing emission wavelength, the width of the magnetic field modulation curve of the electroluminescence increases while its depth decreases. Furthermore, these observations are consistent with the model.« less

  6. Magnetoelectroluminescence of organic heterostructures: Analytical theory and spectrally resolved measurements

    NASA Astrophysics Data System (ADS)

    Liu, Feilong; Kelley, Megan R.; Crooker, Scott A.; Nie, Wanyi; Mohite, Aditya D.; Ruden, P. Paul; Smith, Darryl L.

    2014-12-01

    The effect of a magnetic field on the electroluminescence of organic light emitting devices originates from the hyperfine interaction between the electron/hole polarons and the hydrogen nuclei of the host molecules. In this paper, we present an analytical theory of magnetoelectroluminescence for organic semiconductors. To be specific, we focus on bilayer heterostructure devices. In the case we are considering, light generation at the interface of the donor and acceptor layers results from the formation and recombination of exciplexes. The spin physics is described by a stochastic Liouville equation for the electron/hole spin density matrix. By finding the steady-state analytical solution using Bloch-Wangsness-Redfield theory, we explore how the singlet/triplet exciplex ratio is affected by the hyperfine interaction strength and by the external magnetic field. To validate the theory, spectrally resolved electroluminescence experiments on BPhen/m-MTDATA devices are analyzed. With increasing emission wavelength, the width of the magnetic field modulation curve of the electroluminescence increases while its depth decreases. These observations are consistent with the model.

  7. Wavelength-resolved measurements of fluorescence lifetime of indocyanine green

    NASA Astrophysics Data System (ADS)

    Gerega, Anna; Zolek, Norbert; Soltysinski, Tomasz; Milej, Daniel; Sawosz, Piotr; Toczylowska, Beata; Liebert, Adam

    2011-06-01

    We study fluorescence lifetime of indocyanine green (ICG) using femtosecond laser and sensitive detection based on time-correlated single-photon counting. A time-resolved multichannel spectral system is constructed and applied for determination of the fluorescence lifetime of the ICG in different solvents. Emission properties of ICG in water, milk, and 1% intralipid solution are investigated. Fluorescence of the fluorophore of different concentrations (in a range of 1.7-160 μM) dissolved in different solutions is excited by femtosecond pulses generated with the use of Ti:Sa laser tuned within the range of 740-790 nm. It is observed that fluorescence lifetime of ICG in water is 0.166 +/- 0.02 ns and does not depend on excitation and emission wavelengths. We also show that for the diffusely scattering solvents (milk and intralipid), the lifetime may depend on the dye concentration (especially for large concentrations of ICG). This effect should be taken into account when analyzing changes in the mean time of arrival of fluorescence photons excited in ICG dissolved in such optically turbid media.

  8. Polar Second-Harmonic Imaging to Resolve Pure and Mixed Crystal Phases along GaAs Nanowires.

    PubMed

    Timofeeva, Maria; Bouravleuv, Alexei; Cirlin, George; Shtrom, Igor; Soshnikov, Ilya; Reig Escalé, Marc; Sergeyev, Anton; Grange, Rachel

    2016-10-12

    In this work, we report an optical method for characterizing crystal phases along single-semiconductor III-V nanowires based on the measurement of polarization-dependent second-harmonic generation. This powerful imaging method is based on a per-pixel analysis of the second-harmonic-generated signal on the incoming excitation polarization. The dependence of the second-harmonic generation responses on the nonlinear second-order susceptibility tensor allows the distinguishing of areas of pure wurtzite, zinc blende, and mixed and rotational twins crystal structures in individual nanowires. With a far-field nonlinear optical microscope, we recorded the second-harmonic generation in GaAs nanowires and precisely determined their various crystal structures by analyzing the polar response for each pixel of the images. The predicted crystal phases in GaAs nanowire are confirmed with scanning transmission electron and high-resolution transmission electron measurements. The developed method of analyzing the nonlinear polar response of each pixel can be used for an investigation of nanowire crystal structure that is quick, sensitive to structural transitions, nondestructive, and on-the-spot. It can be applied for the crystal phase characterization of nanowires built into optoelectronic devices in which electron microscopy cannot be performed (for example, in lab-on-a-chip devices). Moreover, this method is not limited to GaAs nanowires but can be used for other nonlinear optical nanostructures.

  9. Single-shot dual-polarization holography: measurement of the polarization state of a magnetic sample

    NASA Astrophysics Data System (ADS)

    Khodadad, Davood; Amer, Eynas; Gren, Per; Melander, Emil; Hällstig, Emil; Sjödahl, Mikael

    2015-08-01

    In this paper a single-shot digital holographic set-up with two orthogonally polarized reference beams is proposed to achieve rapid acquisition of Magneto-Optical Kerr Effect images. Principles of the method and the background theory for dynamic state of polarization measurement by use of digital holography are presented. This system has no mechanically moving elements or active elements for polarization control and modulation. An object beam is combined with two reference beams at different off-axis angles and is guided to a detector. Then two complex fields (interference terms) representing two orthogonal polarizations are recorded in a single frame simultaneously. Thereafter the complex fields are numerically reconstructed and carrier frequency calibration is done to remove aberrations introduced in multiplexed digital holographic recordings. From the numerical values of amplitude and phase, a real time quantitative analysis of the polarization state is possible by use of Jones vectors. The technique is demonstrated on a magnetic sample that is a lithographically patterned magnetic microstructure consisting of thin permalloy parallel stripes.

  10. Resolving stress tensor components in space from polarized Raman spectra: polycrystalline alumina.

    PubMed

    Pezzotti, Giuseppe; Zhu, Wenliang

    2015-01-28

    A method of Raman spectroscopic analysis has been proposed for evaluating tensorial stress fields stored in alumina polycrystals with a corundum structure (α-Al2O3). Raman selection rules for all the vibrational modes of the structure were expanded into explicit functions of both 3 Euler angles in space and 4 Raman tensor elements (RTE) of corundum. A theoretical treatment was then worked out according to the phonon deformation potential (PDP) formalism, which explicitly expressed the changes in force constants under stress in matricial form. Close-form solutions could be obtained for the matrix eigenvalues as a function of 9 unknown variables, namely 6 independent stress tensor components and 3 Euler angles in space, the latter parameters being representatives of local crystal orientation. Successively, two separate sets of Raman calibration experiments were performed for the determination of both RTE and PDP constants of the corundum structure of alumina. Calibration experiments provided a quantitative frame to the newly developed Raman formalism. Polarized Raman spectra were systematically recorded in both single-crystalline and polycrystalline samples, with both A1g and Eg vibrational bands being characterized. Regarding polycrystalline samples, a validation of the proposed Raman method could be done through a comparison between Raman and fluorescence data collected at the same locations across an alumina/metal interface embedded in a steeply graded residual stress field.

  11. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

    NASA Astrophysics Data System (ADS)

    Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I.; Nekrasov, E. S.

    2016-03-01

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from -40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  12. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure.

    PubMed

    Balzovsky, E V; Buyanov, Yu I; Koshelev, V I; Nekrasov, E S

    2016-03-01

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from -40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  13. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

    SciTech Connect

    Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I. Nekrasov, E. S.

    2016-03-15

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from −40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  14. Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

    PubMed

    Nachtigall, Paul E; Supin, Alexander Y; Amundin, Mats; Röken, Bengt; Møller, Thorsten; Mooney, T Aran; Taylor, Kristen A; Yuen, Michelle

    2007-04-01

    While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

  15. Time Resolved Measurements and Reactive Pathways of Hypergolic Bipropellant Combustion

    DTIC Science & Technology

    2006-03-31

    MEASUREMENTS AND REACTIVE PATHWAYS OF HYPERGOLIC BIPROPELLANT COMBUSTION Dr. James E. Smith Jr. DAAD19-02-1-0356 University of Alabama in Huntsville 301...ignition and combustion of hypergolic propellants from high-speed visualization and combustion diagnostics. The laser diagnostic system for the measurement...of hypergolic droplet mixing and combustion was further developed by controlling many relevant factors. These include: droplet size, impact, and

  16. Some problems in the measurement of the frequency-resolving ability of hearing.

    PubMed

    Supin, A Ya

    2005-10-01

    Despite the detailed development of masking methods for measurement of the frequency selectivity of hearing, these measurements are hardly used for diagnostic purposes because they are time-consuming and because of the uncertain extrapolation of the results to the perception of complex spectral patterns. A method for the direct measurement of the spectral resolving ability of hearing using test signals with rippled spectra is proposed. These measurements showed 1) that the resolving ability of the auditory system in terms of discriminating complex spectra is greater than that suggested by the acuity of auditory frequency filters; 2) that changes in the acuity of frequency auditory filters associated with sound intensity hardly affect the ability to resolve complex spectra; 3) that the effects of interference on frequency-resolving ability do not lead to decreases in the spectral contrast of signals due to superimposition of noise.

  17. Polarized radio emission from extensive air showers measured with LOFAR

    SciTech Connect

    Schellart, P.; Buitink, S.; Corstanje, A.; Enriquez, J.E.; Falcke, H.; Hörandel, J.R.; Krause, M.; Nelles, A.; Rachen, J.P.; Veen, S. ter; Thoudam, S.

    2014-10-01

    We present LOFAR measurements of radio emission from extensive air showers. We find that this emission is strongly polarized, with a median degree of polarization of nearly 99%, and that the angle between the polarization direction of the electric field and the Lorentz force acting on the particles, depends on the observer location in the shower plane. This can be understood as a superposition of the radially polarized charge-excess emission mechanism, first proposed by Askaryan and the geomagnetic emission mechanism proposed by Kahn and Lerche. We calculate the relative strengths of both contributions, as quantified by the charge-excess fraction, for 163 individual air showers. We find that the measured charge-excess fraction is higher for air showers arriving from closer to the zenith. Furthermore, the measured charge-excess fraction also increases with increasing observer distance from the air shower symmetry axis. The measured values range from (3.3± 1.0)% for very inclined air showers at 25 m to (20.3± 1.3)% for almost vertical showers at 225 m. Both dependencies are in qualitative agreement with theoretical predictions.

  18. A One Billion Year Martian Climate Model: The Importance of Seasonally Resolved Polar Caps and the Role of Wind

    NASA Technical Reports Server (NTRS)

    Armstrong, J. C.; Leovy, C. B.; Quinn, T. R.; Haberle, R. M.; Schaeffer, J.

    2003-01-01

    Wind deflation and deposition are powerful agents of surface change in the present Mars climate regime. Recent studies indicate that, while the distribution of regions of potential deflation (or erosion) and deposition is remarkably insensitive to changes in orbital parameters (obliquity, timing of perihelion passage, etc.), rates of aeolian surface modification may be highly sensitive to these parameters even if the atmospheric mass remains constant. But previous work suggested the atmospheric mass is likely to be sensitive to obliquity, especially if a significant mass of carbon dioxide can be stored in the regolith or deposited in the form of massive polar caps. Deflation and erosion are highly sensitive to surface pressure, so feedback between orbit variations and surface pressure can greatly enhance the sensitivity of aeolian modification rates to orbital parameters. We used statistics derived from a 1 Gyr orbital integration of the spin axis of Mars, coupled with 3D general circulation models (GCMs) at a variety of orbital conditions and pressures, to explore this feedback. We also employed a seasonally resolved 1D energy balance model to illuminate the gross characteristics of the longterm atmospheric evolution, wind erosion and deposition over one billion years. We find that seasonal polar cycles have a critical influence on the ability for the regolith to release CO2 at high obliquities, and find that the atmospheric CO2 actually decreases at high obliquities due to the cooling effect of polar deposits at latitudes where seasonal caps form. At low obliquity, the formation of massive, permanent polar caps depends critically on the values of the frost albedo, A(sub frost), and frost emissivity, E(sub frost). Using our 1D model with values of A(sub frost) = 0.67 and E(sub frost) = 0.55, matched to the NASA Ames GCM results, we find that permanent caps only form at low obliquities (< 10 degrees). Thus, contrary to expectations, the Martian atmospheric pressure

  19. A One Billion Year Martian Climate Model: The Importance of Seasonally Resolved Polar Caps and the Role of Wind

    NASA Technical Reports Server (NTRS)

    Armstrong, J. C.; Leovy, C. B.; Quinn, T. R.; Haberle, R. M.; Schaeffer, J.

    2003-01-01

    Wind deflation and deposition are powerful agents of surface change in the present Mars climate regime. Recent studies indicate that, while the distribution of regions of potential deflation (or erosion) and deposition is remarkably insensitive to changes in orbital parameters (obliquity, timing of perihelion passage, etc.), rates of aeolian surface modification may be highly sensitive to these parameters even if the atmospheric mass remains constant. But previous work suggested the atmospheric mass is likely to be sensitive to obliquity, especially if a significant mass of carbon dioxide can be stored in the regolith or deposited in the form of massive polar caps. Deflation and erosion are highly sensitive to surface pressure, so feedback between orbit variations and surface pressure can greatly enhance the sensitivity of aeolian modification rates to orbital parameters. We used statistics derived from a 1 Gyr orbital integration of the spin axis of Mars, coupled with 3D general circulation models (GCMs) at a variety of orbital conditions and pressures, to explore this feedback. We also employed a seasonally resolved 1D energy balance model to illuminate the gross characteristics of the longterm atmospheric evolution, wind erosion and deposition over one billion years. We find that seasonal polar cycles have a critical influence on the ability for the regolith to release CO2 at high obliquities, and find that the atmospheric CO2 actually decreases at high obliquities due to the cooling effect of polar deposits at latitudes where seasonal caps form. At low obliquity, the formation of massive, permanent polar caps depends critically on the values of the frost albedo, A(sub frost), and frost emissivity, E(sub frost). Using our 1D model with values of A(sub frost) = 0.67 and E(sub frost) = 0.55, matched to the NASA Ames GCM results, we find that permanent caps only form at low obliquities (< 10 degrees). Thus, contrary to expectations, the Martian atmospheric pressure

  20. Angle-resolved photoemission with circularly polarized light in the nodal mirror plane of underdoped Bi2Sr2CaCu2O8+δ superconductor

    NASA Astrophysics Data System (ADS)

    He, Junfeng; Mion, Thomas R.; Gao, Shang; Myers, Gavin T.; Arita, Masashi; Shimada, Kenya; Gu, G. D.; He, Rui-Hua

    2016-10-01

    Unraveling the nature of pseudogap phase in high-temperature superconductors holds the key to understanding their superconducting mechanisms and potentially broadening their applications via enhancement of their superconducting transition temperatures. Angle-resolved photoemission spectroscopy (ARPES) experiments using circularly polarized light have been proposed to detect possible symmetry breaking state in the pseudogap phase of cuprates. The presence (absence) of an electronic order which breaks mirror symmetry of the crystal would in principle induce a finite (zero) circular dichroism in photoemission. Different orders breaking reflection symmetries about different mirror planes can also be distinguished by the momentum dependence of the measured circular dichroism. Here, we report ARPES experiment on an underdoped Bi2Sr2CaCu2O8+δ (Bi2212) superconductor in the Γ (0,0)-Y (π,π) nodal mirror plane using circularly polarized light. No circular dichroism is observed on the level of ˜2% at low temperature, which places a clear constraint on the forms of possible symmetry breaking orders in this sample. Meanwhile, we find that the geometric dichroism remains substantial very close to its perfect extinction such that a very small sample angular offset is sufficient to induce a sizeable dichroic signal. It highlights the importance to establish a perfect extinction of geometric dichroism as a prerequisite for the identification of any intrinsic circular dichroism in this material.

  1. Measuring ultrashort pulses using frequency-resolved optical gating

    SciTech Connect

    Trebino, R.

    1993-12-01

    The purpose of this program is the development of techniques for the measurement of ultrafast events important in gas-phase combustion chemistry. Specifically, goals of this program include the development of fundamental concepts and spectroscopic techniques that will augment the information currently available with ultrafast laser techniques. Of equal importance is the development of technology for ultrafast spectroscopy. For example, methods for the production and measurement of ultrashort pulses at wavelengths important for these studies is an important goal. Because the specific vibrational motion excited in a molecule depends sensitively on the intensity, I(t), and the phase, {psi}(t), of the ultrashort pulse used to excite the motion, it is critical to measure both of these quantities for an individual pulse. Unfortunately, this has remained an unsolved problem for many years. Fortunately, this year, the authors present a technique that achieves this goal.

  2. Spatially-Resolved System for Polarimetric Measurements at Subwavelength Scales

    DTIC Science & Technology

    2009-09-24

    8217 Cj>a:: .. nao .-. ic lie "•eepe no.eve-t ippei :can-«i see be c.-. \\ stepoe: TOIO- :Uje j-" rr-lri-je. Elecii ca conntctor: seep 32’ \\ ::eppe...involve performing near-field tomographic reconstruction, measuring low refractive index contrast materials , measuring the polarimetric response of...field tomography: The fields from an NSOM scan penetrate a finite depth into the material , giving one the ability to see structures below the surface of

  3. Laser-induced birefringence measurements by quantitative polarized-phase microscopy.

    PubMed

    Doualle, Thomas; Ollé, Alexandre; Cormont, Philippe; Monneret, Serge; Gallais, Laurent

    2017-04-15

    A technique that provides quantitative and spatially resolved retardance measurement is studied for application to laser-induced modification in transparent materials. The method is based on the measurement of optical path differences between two wavefronts carrying different polarizations, measured by a wavefront sensor placed in the image plane of a microscope. We have applied the technique to the investigation of stress distribution induced by CO2 laser processing of fused silica samples. By comparing experiments to the results of thermomechanical simulations we demonstrate quantitative agreement between measurements and simulations of optical retardance. The technique provides an efficient and simple way to measure retardance of less than 1 nm with a diffraction-limited spatial resolution in transparent samples, and coupled to thermomechanical simulations it gives access to birefringence distribution in the sample.

  4. Precise polarization measurements via detection of compton scattered electrons

    SciTech Connect

    Tvaskis, Vladas; Dutta, Dipangkar; Gaskell, David J.; Narayan, Amrendra

    2014-01-01

    The Qweak experiment at Jefferson Lab aims to make a 4% measurement of the parity-violating asymmetry in elastic scattering at very low Q{sup 2} of a longitudinally polarized electron beam off a proton target. One of the dominant experimental systematic uncertainties in Qweak will result from determining the beam polarization. A new Compton polarimeter was installed in the fall of 2010 to provide a non-invasive and continuous monitoring of the electron beam polarization in Hall C at Jefferson Lab. The Compton-scattered electrons are detected in four planes of diamond micro-strip detectors. We have achieved the design goals of <1% statistical uncertainty per hour and expect to achieve <1% systematic uncertainty.

  5. Scatter polarization measurements with a mueller matrix imaging polarimeter.

    SciTech Connect

    Chipman, Russell A.; DeBoo, Brian

    2004-08-01

    A Mueller matrix imaging polarimeter is used to acquire polarization-sensitive images of seven different manmade samples in multiple scattering geometries. Successive Mueller matrix images of a sample with changing incidence and scatter angles are used to develop a Mueller matrix bidirectional reflectance distribution function for the sample in one plane of measurement. The Mueller matrix bidirectional reflectance distribution functions are compared, and patterns are noted. The most significant data for the scattering samples measured occurs along the diagonal of the respective Mueller matrices, indicating significant depolarization effects. Reduced depolarization data in the form of the average degree of polarization (of exiting light) for each sample is examined as a function of changing scattering geometry. Five of seven manmade samples exhibit an inverted Gaussian profile of depolarization with changing scattering geometry, the shape of which may prove useful for measuring sample properties (e.g. roughness) and for classifying or categorizing samples in a remote sensing scheme. Depolarization differences for each sample in response to changing incident polarization states are also examined, and a new metric, the degree of polarization surface, has been developed to visualize all such data simultaneously.

  6. X-ray Polarization Potential and Measurement Feasibility

    NASA Astrophysics Data System (ADS)

    Hebb Swank, Jean; Kallman, T. R.; Strohmayer, T. E.; Jahoda, K.; Deines-Jones, P.; Black, K.; Hill, J.

    2007-05-01

    Constructing physical models for compact X-ray sources is a goal of many measurements of their spectral and timing properties. Understanding the astrophysical roles of black holes and neutron stars and using them to test questions of fundamental physics are hampered by model uncertainties, so the as-yet unused information of polarization beckons as an arbiter. Polarimeters have recently been proposed for missions of every size, from balloons to Xeus. Thepredictions of polarization for models of the X-rays from stellar black holes, active galactic nuclei, and neutron stars are reviewed. Polarization could identify that emission is from a disk and passes over a black hole in the high soft state and that fluorescent and reflected radiation in a quasar does so also, even tracing flares. It would make a significant contribution to the study of strong gravity. It could determine whether low hard state coronae are the base of an outflow or jet and help determine how much gas is diverted from the black hole. Polarization's diagnostic power for spin and emission region information of both rotation powered and accreting pulsars with strong magnetic fields has long been known and the energy dependent effects of vacuum polarization in thermally emitting neutron stars are well studied. Soft Gamma Repeaters and Anomalous X-ray Pulsars are both now identified as Magnetars with the strongest implied magnetic fields. Polarization could determine the evolution of their apparently shifting field geometry. We compare predictions of current models with what could be measured using different photoelectron tracking detectors behind telescopes suitable for a SMEX and for Constellation X. Time projection chamber detectors have high quantum efficiency compared to imaging gas pixel detectors and would be suitable for studying compact objects. We also consider the relative merits of other types of polarimeters with respect to comparative sensitivity limits.

  7. Highly Resolved Aerosol Measurements from High Altitude Platforms

    NASA Technical Reports Server (NTRS)

    Wilson, James Charles

    1999-01-01

    The University of Denver agreed to develop and fabricate two instruments for the characterization of submicron aerosol. The instruments were to be light weight for use on remotely-piloted aircraft or balloons. The instruments were to provide accurate size measurements of size distributions in the size range from 0.07 to 2 micrometers in diameter and concentration measurements in the size range approximately 0.01 to 2 micrometers in diameter. The instruments constructed under this cooperative agreement respond quite nearly as expected and meet the objective of being light and compact. One has been used for ground based and low altitude studies and the other will be deployed in high altitude studies this winter.

  8. Super-resolving phase measurements with a multiphoton entangled state.

    PubMed

    Mitchell, M W; Lundeen, J S; Steinberg, A M

    2004-05-13

    Interference phenomena are ubiquitous in physics, often forming the basis of demanding measurements. Examples include Ramsey interferometry in atomic spectroscopy, X-ray diffraction in crystallography and optical interferometry in gravitational-wave studies. It has been known for some time that the quantum property of entanglement can be exploited to perform super-sensitive measurements, for example in optical interferometry or atomic spectroscopy. The idea has been demonstrated for an entangled state of two photons, but for larger numbers of particles it is difficult to create the necessary multiparticle entangled states. Here we demonstrate experimentally a technique for producing a maximally entangled three-photon state from initially non-entangled photons. The method can in principle be applied to generate states of arbitrary photon number, giving arbitrarily large improvement in measurement resolution. The method of state construction requires non-unitary operations, which we perform using post-selected linear-optics techniques similar to those used for linear-optics quantum computing.

  9. Tissue oxygenation and haemodynamics measurement with spatially resolved NIRS

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Scopesi, F.; Serra, G.; Sun, J. W.; Rolfe, P.

    2010-08-01

    We describe the use of Near Infrared Spectroscopy (NIRS) for the non-invasive investigation of changes in haemodynamics and oxygenation of human peripheral tissues. The goal was to measure spatial variations of tissue NIRS oxygenation variables, namely deoxy-haemoglobin (HHb), oxy-haemoglobin (HbO2), total haemoglobin (HbT), and thereby to evaluate the responses of the peripheral circulation to imposed physiological challenges. We present a skinfat- muscle heterogeneous tissue model with varying fat thickness up to 15mm and a Monte Carlo simulation of photon transport within this model. The mean partial path length and the mean photon visit depth in the muscle layer were derived for different source-detector spacing. We constructed NIRS instrumentation comprising of light-emitting diodes (LED) as light sources at four wavelengths, 735nm, 760nm, 810nm and 850nm and sensitive photodiodes (PD) as the detectors. Source-detector spacing was varied to perform measurements at different depths within forearm tissue. Changes in chromophore concentration in response to venous and arterial occlusion were calculated using the modified Lambert-Beer Law. Studies in fat and thin volunteers indicated greater sensitivity in the thinner subjects for the tissue oxygenation measurement in the muscle layer. These results were consistent with those found using Monte Carlo simulation. Overall, the results of this investigation demonstrate the usefulness of the NIRS instrument for deriving spatial information from biological tissues.

  10. Response Surface Methods for Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatial ly-re solved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/-30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-light, inflatable space antenna at NASA Langley Research Center.

  11. On the Statistical Analysis of X-ray Polarization Measurements

    NASA Technical Reports Server (NTRS)

    Strohmayer, T. E.; Kallman, T. R.

    2013-01-01

    In many polarimetry applications, including observations in the X-ray band, the measurement of a polarization signal can be reduced to the detection and quantification of a deviation from uniformity of a distribution of measured angles of the form alpha plus beta cosine (exp 2)(phi - phi(sub 0) (0 (is) less than phi is less than pi). We explore the statistics of such polarization measurements using both Monte Carlo simulations as well as analytic calculations based on the appropriate probability distributions. We derive relations for the number of counts required to reach a given detection level (parameterized by beta the "number of sigma's" of the measurement) appropriate for measuring the modulation amplitude alpha by itself (single interesting parameter case) or jointly with the position angle phi (two interesting parameters case). We show that for the former case when the intrinsic amplitude is equal to the well known minimum detectable polarization (MDP) it is, on average, detected at the 3sigma level. For the latter case, when one requires a joint measurement at the same confidence level, then more counts are needed, by a factor of approximately equal to 2.2, than that required to achieve the MDP level. We find that the position angle uncertainty at 1sigma confidence is well described by the relation sigma(sub pi) equals 28.5(degrees) divided by beta.

  12. Arbitrarily high super-resolving phase measurements at telecommunication wavelengths

    SciTech Connect

    Kothe, Christian; Bjoerk, Gunnar; Bourennane, Mohamed

    2010-06-15

    We present two experiments that achieve phase super-resolution at telecommunication wavelengths. One of the experiments is realized in the space domain and the other is realized in the time domain. Both experiments show high visibility and are performed with standard lasers and single-photon detectors. The first experiment uses six-photon coincidences, whereas the latter experiment needs no coincidence measurements, is easy to perform, and achieves, in principle, arbitrarily high phase super-resolution. Here, we demonstrate a 30-fold increase of the resolution. We stress that neither entanglement nor joint detection is needed in these experiments, which demonstrates that neither is necessary to achieve phase super-resolution.

  13. Time-resolved fluorescence measurements of actin-phalloidin interactions

    NASA Astrophysics Data System (ADS)

    Helms, Michael K.; French, Todd E.

    2000-03-01

    Compounds that interact with the cytoskeleton affect mobility and division, making them useful for treatment of certain types of cancer. Actin binding drugs such as the phallotoxins (small, bicyclic peptides) bind to and stabilize actin polymers (F-actin) without binding to actin monomers (G-actin). It has been shown that the intensity of fluorescently labeled phallotoxins such as fluorescein- phalloidin and rhodamine-phalloidin increases upon bind F- actin. We used LJL BioSystems' new FLAReTM technology to measure excited state lifetime changes of fluorescein- phalloidin and rhodamine-phalloidin upon binding to F- actin.

  14. On the Statistical Analysis of X-Ray Polarization Measurements

    NASA Astrophysics Data System (ADS)

    Strohmayer, T. E.; Kallman, T. R.

    2013-08-01

    In many polarimetry applications, including observations in the X-ray band, the measurement of a polarization signal can be reduced to the detection and quantification of a deviation from uniformity of a distribution of measured angles of the form A + Bcos 2(phi - phi0) (0 < phi < π). We explore the statistics of such polarization measurements using Monte Carlo simulations and χ2 fitting methods. We compare our results to those derived using the traditional probability density used to characterize polarization measurements and quantify how they deviate as the intrinsic modulation amplitude grows. We derive relations for the number of counts required to reach a given detection level (parameterized by β the "number of σ's" of the measurement) appropriate for measuring the modulation amplitude a by itself (single interesting parameter case) or jointly with the position angle phi (two interesting parameters case). We show that for the former case, when the intrinsic amplitude is equal to the well-known minimum detectable polarization, (MDP) it is, on average, detected at the 3σ level. For the latter case, when one requires a joint measurement at the same confidence level, then more counts are needed than what was required to achieve the MDP level. This additional factor is amplitude-dependent, but is ≈2.2 for intrinsic amplitudes less than about 20%. It decreases slowly with amplitude and is ≈1.8 when the amplitude is 50%. We find that the position angle uncertainty at 1σ confidence is well described by the relation σphi = 28.°5/β.

  15. [A method for time-resolved laser-induced breakdown spectroscopy measurement].

    PubMed

    Pan, Cong-Yuan; Han, Zhen-Yu; Li, Chao-Yang; Yu, Yun-Si; Wang, Sheng-Bo; Wang, Qiu-Ping

    2014-04-01

    Laser-Induced Breakdown Spectroscopy (LIBS) is strongly time related. Time-resolved LIBS measurement is an important technique for the research on laser induced plasma evolution and self-absorption of the emission lines. Concerning the temporal characteristics of LIBS spectrum, a method is proposed in the present paper which can achieve micros-scale time-resolved LIBS measurement by using general ms-scale detector. By setting different integration delay time of the ms-scale spectrum detector, a series of spectrum are recorded. And the integration delay time interval should be longer than the worst temporal precision. After baseline correction and spectrum fitting, the intensity of the character line was obtained. Calculating this intensity with differential method at a certain time interval and then the difference value is the time-resolved line intensity. Setting the plasma duration time as X-axis and the time-resolved line intensity as Y-axis, the evolution curve of the character line intensity can be plotted. Character line with overlap-free and smooth background should be a priority to be chosen for analysis. Using spectrometer with ms-scale integration time and a control system with temporal accuracy is 0.021 micros, experiments carried out. The results validate that this method can be used to characterize the evolution of LIBS characteristic lines and can reduce the cost of the time-resolved LIBS measurement system. This method makes high time-resolved LIBS spectrum measurement possible with cheaper system.

  16. Effects of spin diffusion on electron spin relaxation time measured with a time-resolved microscopic photoluminescence technique

    SciTech Connect

    Ikeda, Kazuhiro Kawaguchi, Hitoshi

    2015-02-07

    We performed measurements at room temperature for a GaAs/AlGaAs multiple quantum well grown on GaAs(110) using a time-resolved microscopic photoluminescence (micro-PL) technique to find what effects spin diffusion had on the measured electron spin relaxation time, τ{sub s}, and developed a method of estimating the spin diffusion coefficient, D{sub s}, using the measured data and the coupled drift-diffusion equations for spin polarized electrons. The spatial nonuniformities of τ{sub s} and the initial degree of electron spin polarization caused by the pump intensity distribution inside the focal spot were taken into account to explain the dependence of τ{sub s} on the measured spot size, i.e., a longer τ{sub s} for a smaller spot size. We estimated D{sub s} as ∼100 cm{sup 2}/s, which is similar to a value reported in the literature. We also provided a qualitative understanding on how spin diffusion lengthens τ{sub s} in micro-PL measurements.

  17. Time Resolved Measurements of Primary Biogenic Aerosol Particles in Amazonia

    NASA Astrophysics Data System (ADS)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2009-04-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the Amazonian Aerosol Characterization Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. This presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 µm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as "viable aerosols" or "fluorescent bioparticles" (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. Data from the UVAPS were averaged over 5 minute time intervals. The presence of bioparticles in the observed size range has been

  18. Laboratory polarized phase curve measurement of airless body analog materials

    NASA Astrophysics Data System (ADS)

    Jiang, Te; Chen, Lei; Yang, Yazhou; Zhang, Hao; Liu, Yan; Ma, Pei; Zheming, Jianxiong

    2017-06-01

    When Sun light is incident on surfaces of airless bodies the reflected radiation is often found to be more polarized in the direction perpendicular to the scattering plane than in the parallel direction at small phase angle. This so-called negative polarization effect may be quantitatively characterized by several parameters of the polarized phase curve (PPC) such as the minimum degree of polarization (DOP) (Pmin), the inversion angle where the DOP changes its sign (alpha_inv), and the slope of the PPC near alpha_inv (h). Currently these parameters are believed to be complementary to spectroscopic data in revealing asteroid surface compositions and physical properties. Because of the paucities of laboratory experiments on analog materials, there are many open questions in interpretations of observational data. For example, earlier studies show that bare rocks, fine dust and rubble piles are located in different regions in the parameter space spanned by Pmin and alpha_inv, while recent observational results tend to support the idea that the locations are more related to surface mineralogy and chemical compositions; the compositions of F asteroids and the Barbarians with smallest and largest inversion angles. How much information on space weathering can polarization provide? To answer these questions, we have set up a three wavelength light scattering system to measure analog materials with different physical properties. The system can measure the Mueller matrices of packed surfaces from 2 to 135 deg. phase angle. We present measurement results on typical pure minerals with refractive indices varying from 1.4 to 2.4, both in bulk and grains, to understand the effects of refractive index on Pmin, alpha_inv and h. Olivine and pyroxene grains and their mixtures, both original and irradiated by a 1064 nm pulse laser at different energy levels in a vacuum chamber, are used to simulate asteroid surface materials with varying degrees of space weathering. Their reflectance

  19. Marine fluorescence from high spectrally resolved satellite measurements

    NASA Astrophysics Data System (ADS)

    Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

    2014-05-01

    When chlorophyll molecules absorb light, most of this energy is transformed into chemical energy in a process of photosynthesis. However, a fraction of the energy absorbed is reemitted as fluorescence. As a result of its relationship to photosynthetic e?ciency, information about chlorophyll fluorescence can be used to assess the physiological state of phytoplankton (Falkowski and Kolber,1995). In-situ measurements of chlorophyll fluorescence are widespread in physiological and ecophysiological studies. When retrieved from space, chlorophyll fluorescence can improve our knowledge of global biogeochemical cycles and phytoplankton productivity (Behrenfeld et al., 2009; Huot et al., 2013) by providing high coverage and periodicity. So far, the only satellite retrieval of sun-induced marine fluorescence, Fluorescence Line Height (FLH), was designed for MODIS (Abbott and Letelier, 1999), and later also applied to the similar sensor MERIS (Gower et al., 2004). However, it could so far not be evaluated on global scale. Here, we present a different approach to observe marine chlorophyll fluorescence, based on the Differential Optical Absorption Spectroscopy (DOAS) technique (Perner and Platt, 1979) applied to the hyperspectral data from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Global Ozone Monitoring Experiment-2 (GOME-2). Since fluorescence, as a trans-spectral process, leads to the shift of the wavelength of the radiation, it can be observed in the filling-in of Fraunhofer lines. In our retrieval, we evaluate the filling-in of the Zeeman triplet Fraunhofer line FeI at 684.3 nm, which is located very close to the emission peak of marine fluorescence (~685 nm). In order to conduct the chlorophyll fluorescence retrieval with the DOAS method, we calculated the reference spectra for chlorophyll fluorescence, based on simulations performed with the coupled ocean-atmosphere radiative transfer model SCIATRAN (Rozanov et al., 2014

  20. Functional and shunt states of bacteriorhodopsin resolved by 250 GHz dynamic nuclear polarization-enhanced solid-state NMR.

    PubMed

    Bajaj, Vikram S; Mak-Jurkauskas, Melody L; Belenky, Marina; Herzfeld, Judith; Griffin, Robert G

    2009-06-09

    Observation and structural studies of reaction intermediates of proteins are challenging because of the mixtures of states usually present at low concentrations. Here, we use a 250 GHz gyrotron (cyclotron resonance maser) and cryogenic temperatures to perform high-frequency dynamic nuclear polarization (DNP) NMR experiments that enhance sensitivity in magic-angle spinning NMR spectra of cryo-trapped photocycle intermediates of bacteriorhodopsin (bR) by a factor of approximately 90. Multidimensional spectroscopy of U-(13)C,(15)N-labeled samples resolved coexisting states and allowed chemical shift assignments in the retinylidene chromophore for several intermediates not observed previously. The correlation spectra reveal unexpected heterogeneity in dark-adapted bR, distortion in the K state, and, most importantly, 4 discrete L substates. Thermal relaxation of the mixture of L's showed that 3 of these substates revert to bR(568) and that only the 1 substate with both the strongest counterion and a fully relaxed 13-cis bond is functional. These definitive observations of functional and shunt states in the bR photocycle provide a preview of the mechanistic insights that will be accessible in membrane proteins via sensitivity-enhanced DNP NMR. These observations would have not been possible absent the signal enhancement available from DNP.

  1. Polarization-Resolved Raman Study of Bulk-like and Davydov-Induced Vibrational Modes of Exfoliated Black Phosphorus.

    PubMed

    Phaneuf-L'Heureux, Anne-Laurence; Favron, Alexandre; Germain, Jean-Francis; Lavoie, Patrick; Desjardins, Patrick; Leonelli, Richard; Martel, Richard; Francoeur, Sebastien

    2016-12-14

    Owing to its crystallographic structure, black phosphorus is one of the few 2D materials expressing strongly anisotropic optical, transport, and mechanical properties. We report on the anisotropy of electron-phonon interactions through a polarization-resolved Raman study of the four vibrational modes of atomically thin black phosphorus (2D phosphane): the three bulk-like modes Ag(1), B2g, and Ag(2) and the Davydov-induced mode labeled Ag(B2u). The complex Raman tensor elements reveal that the relative variation in permittivity of all Ag modes is irrespective of the atomic motion involved lowest along the zigzag direction, the basal anisotropy of these variations is most pronounced for Ag(2) and Ag(B2u), and interlayer interactions in multilayer samples lead to reduced anisotropy. The bulk-forbidden Ag(B2u) mode appears for n ≥ 2 and quickly subsides in thicker layers. It is assigned to a Davydov-induced IR to Raman conversion of the bulk IR mode B2u and exhibits characteristics similar to Ag(2). Although this mode is expected to be weak, an electronic resonance significantly enhances its Raman efficiency such that it becomes a dominant mode in the spectrum of bilayer 2D phosphane.

  2. Transmission grating based extreme ultraviolet imaging spectrometer for time and space resolved impurity measurements.

    PubMed

    Kumar, Deepak; Stutman, Dan; Tritz, Kevin; Finkenthal, Michael; Tarrio, Charles; Grantham, Steven

    2010-10-01

    A free standing transmission grating based imaging spectrometer in the extreme ultraviolet range has been developed for the National Spherical Torus Experiment (NSTX). The spectrometer operates in a survey mode covering the approximate spectral range from 30 to 700 Å and has a resolving capability of δλ/λ on the order of 3%. Initial results from space resolved impurity measurements from NSTX are described in this paper.

  3. The effect of incident light polarization on spectralon BRDF measurements

    NASA Astrophysics Data System (ADS)

    Georgiev, Georgi T.; Butler, James J.

    2004-11-01

    Many satellite instruments operating in the reflective solar wavelength region between 400nm and 2500nm require accurate and precise determination of the Bidirectional Reflectance Distribution Function (BRDF) of Spectralon diffusers used in their pre-flight and on-orbit calibrations. Calibration measurements of the BRDF of a laboratory optical grade Spectralon diffuse target at different incident polarized light in ultraviolet and visible is presented. The Spectralon diffuser was measured using P and S incident polarized light and over a range of incident and scatter angles from 0 to 60 degrees. The experimental data were obtained using the out-of-plane optical scatterometer located in NASA's Goddard Space Flight Center's Diffuse Calibration Facility's. The typical measurement uncertainty of reported BRDF measurements is 0.7 % (k=1). It is shown how BRDF of Spectralon at P and S polarization of the incident light depends on the incident and scatter angles and on wavelengths. The difference is significant, depends strongly on the incident and scatter angles can be as high as 5.7% at 60 deg incident, 60 deg scatter zenith and 0 deg scatter azimuth angles

  4. Dynamic phase measurements based on a polarization Michelson interferometer employing a pixelated polarization camera

    NASA Astrophysics Data System (ADS)

    Serrano-Garcia, David I.; Otani, Yukitoshi

    2017-02-01

    We implemented an interferometric configuration capable of following a phase variation in time. By using a pixelated polarization camera, the system is able to retrieve the phase information instantaneously avoiding the usage of moving components and the necessity of an extra replication method attached at the output of the interferometer. Taking into account the temporal stability obtained from the system, a spatial-temporal phase demodulation algorithm can be implemented on frequency domain for the dynamic phase measurement. Spatial resolution is analyzed experimentally using a USAF pattern, and dynamic phase measurements were done on air and water medium variations due to a jet flame and a living fish as a biological sample, respectively.

  5. High time resolved electron temperature measurements by using the multi-pass Thomson scattering system in GAMMA 10/PDX

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Masayuki; Yasuhara, Ryo; Ohta, Koichi; Chikatsu, Masayuki; Shima, Yoriko; Kohagura, Junko; Sakamoto, Mizuki; Nakashima, Yousuke; Imai, Tsuyoshi; Ichimura, Makoto; Yamada, Ichihiro; Funaba, Hisamichi; Minami, Takashi

    2016-11-01

    High time resolved electron temperature measurements are useful for fluctuation study. A multi-pass Thomson scattering (MPTS) system is proposed for the improvement of both increasing the TS signal intensity and time resolution. The MPTS system in GAMMA 10/PDX has been constructed for enhancing the Thomson scattered signals for the improvement of measurement accuracy. The MPTS system has a polarization-based configuration with an image relaying system. We optimized the image relaying optics for improving the multi-pass laser confinement and obtaining the stable MPTS signals over ten passing TS signals. The integrated MPTS signals increased about five times larger than that in the single pass system. Finally, time dependent electron temperatures were obtained in MHz sampling.

  6. Influence of vibration disturbance during polarization coupling measurement of polarization-maintaining fiber.

    PubMed

    Guo, Zhenwu; Zhang, Hongxia; Chen, Xinwei; Jia, Dagong; Liu, Tiegen

    2011-07-10

    The principle of the mode cross coupling in polarization-maintaining fiber based on white-light interferometry was analyzed. The method of measuring the polarization mode coupling with a spatial Michelson interferometer was presented. Analysis and emulation were carried out for the vibration disturbance signal caused by the mechanical scanning and the influence the vibration imposed on the judgment of coupling intensity. The interference signal envelope is extracted by a Hilbert transform and fitted by a Gaussian least-squares method under the different scanning speed. It is indicated that the detection accuracy varies with the vibration amplitude, which varies with scanning speed. The best scanning speed of the system should be from 0.7 mm/s to 0.9 mm/s to achieve the minimum detection error.

  7. The Sky Polarization Observatory (SPOrt): a project to measure the diffused sky polarization from the International Space Station Alpha (ISSA)

    NASA Astrophysics Data System (ADS)

    Cortiglioni, S.

    1999-07-01

    The Sky Polarization Observatory (SPOrt), a project to measure the diffused sky polarization in the frequency range of 22-90 GHz from the International Space Station, is described in its current configuration. Some preliminary considerations about the general topic of polarization in radiometric observations are made, in order to introduce the importance of polarimetric measurements in the more general context of Cosmic Microwave Background observations. The International Space Station is also introduced as a quite good opportunity to address such problematics.

  8. Generalized Mueller matrix method for polarization mode dispersion measurement in a system with polarization-dependent loss or gain.

    PubMed

    Dong, H; Shum, P; Yan, M; Zhou, J Q; Ning, G X; Gong, Y D; Wu, C Q

    2006-06-12

    A generalized Mueller matrix method (GMMM) is proposed to measure the polarization mode dispersion (PMD) in an optical fiber system with polarization-dependent loss or gain (PDL/G). This algorithm is based on the polar decomposition of a 4X4 matrix which corresponds to a Lorentz transformation. Compared to the generalized Poincaré sphere method, the GMMM can measure PMD accurately with a relatively larger frequency step, and the obtained PMD data has very low noise level.

  9. POLARBEAR-2: an instrument for CMB polarization measurements

    NASA Astrophysics Data System (ADS)

    Inoue, Y.; Ade, P.; Akiba, Y.; Aleman, C.; Arnold, K.; Baccigalupi, C.; Barch, B.; Barron, D.; Bender, A.; Boettger, D.; Borrill, J.; Chapman, S.; Chinone, Y.; Cukierman, A.; de Haan, T.; Dobbs, M. A.; Ducout, A.; Dünner, R.; Elleflot, T.; Errard, J.; Fabbian, G.; Feeney, S.; Feng, C.; Fuller, G.; Gilbert, A. J.; Goeckner-Wald, N.; Groh, J.; Hall, G.; Halverson, N.; Hamada, T.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Hill, C.; Holzapfel, W. L.; Hori, Y.; Howe, L.; Irie, F.; Jaehnig, G.; Jaffe, A.; Jeong, O.; Katayama, N.; Kaufman, J. P.; Kazemzadeh, K.; Keating, B. G.; Kermish, Z.; Keskitalo, R.; Kisner, T. S.; Kusaka, A.; Le Jeune, M.; Lee, A. T.; Leon, D.; Linder, E. V.; Lowry, L.; Matsuda, F.; Matsumura, T.; Miller, N.; Mizukami, K.; Montgomery, J.; Navaroli, M.; Nishino, H.; Paar, H.; Peloton, J.; Poletti, D.; Puglisi, G.; Raum, C. R.; Rebeiz, G. M.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Rotermund, K. M.; Segawa, Y.; Sherwin, B. D.; Shirley, I.; Siritanasak, P.; Stebor, N.; Stompor, R.; Suzuki, J.; Suzuki, A.; Tajima, O.; Takada, S.; Takatori, S.; Teply, G. P.; Tikhomirov, A.; Tomaru, T.; Whitehorn, N.; Zahn, A.; Zahn, O.

    2016-07-01

    POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment that will be located in the Atacama highland in Chile at an altitude of 5200 m. Its science goals are to measure the CMB polarization signals originating from both primordial gravitational waves and weak lensing. PB-2 is designed to measure the tensor to scalar ratio, r, with precision σ(r) > 0:01, and the sum of neutrino masses, Σmz, with σ(Σmv) < 90 meV. To achieve these goals, PB-2 will employ 7588 transition-edge sensor bolometers at 95 GHz and 150 GHz, which will be operated at the base temperature of 250 mK. Science observations will begin in 2017.

  10. Distributed measurement of birefringence dispersion in polarization-maintaining fibers.

    PubMed

    Tang, Feng; Wang, Xiang-Zhao; Zhang, Yimo; Jing, Wencai

    2006-12-01

    A new method to measure the birefringence dispersion in high-birefringence polarization-maintaining fibers is presented using white-light interferometry. By analyzing broadening of low-coherence interferograms obtained in a scanning Michelson interferometer, the birefringence dispersion and its variation along different fiber sections are acquired with high sensitivity and accuracy. Birefringence dispersions of two PANDA fibers at their operation wavelength are measured to be 0.011 ps/(km nm) and 0.018 ps/(km nm), respectively. Distributed measurement capability of the method is also verified experimentally.

  11. Muon polarization in the MEG experiment: predictions and measurements

    DOE PAGES

    Baldini, A. M.; Bao, Y.; Baracchini, E.; ...

    2016-04-22

    The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process μ+→e+γ. We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Pμ=-1 by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be Pμ= -0.86 ± 0.02 (stat)more » $$+0.05\\atop{-0.06}$$ (syst) at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our μ+→e+γ search induced by the muon radiative decay: μ+→e+$$\\bar{v}$$μνeγ.« less

  12. Muon polarization in the MEG experiment: predictions and measurements

    SciTech Connect

    Baldini, A. M.; Bao, Y.; Baracchini, E.; Bemporad, C.; Berg, F.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Cavoto, G.; Cei, F.; Chiarello, G.; Chiri, C.; Bari, A. De; Gerone, M. De; D’Onofrio, A.; Dussoni, S.; Fujii, Y.; Galli, L.; Gatti, F.; Grancagnolo, F.; Grassi, M.; Graziosi, A.; Grigoriev, D. N.; Haruyama, T.; Hildebrandt, M.; Hodge, Z.; Ieki, K.; Ignatov, F.; Iwamoto, T.; Kaneko, D.; Kang, T. I.; Kettle, P. -R.; Khazin, B. I.; Khomutov, N.; Korenchenko, A.; Kravchuk, N.; Lim, G. M. A.; Mihara, S.; Molzon, W.; Mori, Toshinori; Mtchedlishvili, A.; Nakaura, S.; Nicolò, D.; Nishiguchi, H.; Nishimura, M.; Ogawa, S.; Ootani, W.; Panareo, M.; Papa, A.; Pepino, A.; Piredda, G.; Pizzigoni, G.; Popov, A.; Renga, F.; Ripiccini, E.; Ritt, S.; Rossella, M.; Rutar, G.; Sawada, R.; Sergiampietri, F.; Signorelli, G.; Tassielli, G. F.; Tenchini, F.; Uchiyama, Y.; Venturini, M.; Voena, C.; Yamamoto, A.; Yoshida, K.; You, Z.; Yudin, Yu. V.

    2016-04-22

    The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process μ+→e+γ. We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Pμ=-1 by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be Pμ= -0.86 ± 0.02 (stat) $+0.05\\atop{-0.06}$ (syst) at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our μ+→e+γ search induced by the muon radiative decay: μ+→e+$\\bar{v}$μνeγ.

  13. Muon polarization in the MEG experiment: predictions and measurements

    NASA Astrophysics Data System (ADS)

    Baldini, A. M.; Bao, Y.; Baracchini, E.; Bemporad, C.; Berg, F.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Cavoto, G.; Cei, F.; Chiarello, G.; Chiri, C.; Bari, A. De; Gerone, M. De; D'Onofrio, A.; Dussoni, S.; Fujii, Y.; Galli, L.; Gatti, F.; Grancagnolo, F.; Grassi, M.; Graziosi, A.; Grigoriev, D. N.; Haruyama, T.; Hildebrandt, M.; Hodge, Z.; Ieki, K.; Ignatov, F.; Iwamoto, T.; Kaneko, D.; Kang, T. I.; Kettle, P.-R.; Khazin, B. I.; Khomutov, N.; Korenchenko, A.; Kravchuk, N.; Lim, G. M. A.; Mihara, S.; Molzon, W.; Mori, Toshinori; Mtchedlishvili, A.; Nakaura, S.; Nicolò, D.; Nishiguchi, H.; Nishimura, M.; Ogawa, S.; Ootani, W.; Panareo, M.; Papa, A.; Pepino, A.; Piredda, G.; Pizzigoni, G.; Popov, A.; Renga, F.; Ripiccini, E.; Ritt, S.; Rossella, M.; Rutar, G.; Sawada, R.; Sergiampietri, F.; Signorelli, G.; Tassielli, G. F.; Tenchini, F.; Uchiyama, Y.; Venturini, M.; Voena, C.; Yamamoto, A.; Yoshida, K.; You, Z.; Yudin, Yu. V.

    2016-04-01

    The MEG experiment makes use of one of the world's most intense low energy muon beams, in order to search for the lepton flavour violating process μ + → e+ γ . We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be P_{μ } = -1 by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be P_{μ } = -0.86 ± 0.02 (stat) { }^{+ 0.05}_{-0.06} (syst) at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our {μ ^+ → e^+ γ } search induced by the muon radiative decay: μ + → e+ bar{ν }_{μ } ν _e γ.

  14. Hydrogen bond stabilities in membrane-reconstituted alamethicin from amide-resolved hydrogen-exchange measurements.

    PubMed

    Dempsey, C E; Handcock, L J

    1996-04-01

    Amide-resolved hydrogen-deuterium exchange-rate constants were measured for backbone amides of alamethicin reconstituted in dioleoylphosphatidylcholine vesicles by an exchange-trapping method combined with high-resolution nuclear magnetic resonance spectroscopy. In vesicles containing alamethicin at molar ratios between 1:20 and 1:100 relative to lipid, the exchange-rate constants increased with increasing volume of the D20 buffer in which the vesicles were suspended, indicating that exchange under these conditions is dominated by partitioning of the peptide into the aqueous phase. This was supported by observation of a linear relationship between the exchange-rate constants for amides in membrane-reconstituted alamethicin and those for amides in alamethicin dissolved directly into D2O buffer. Significant protection of amides from exchange with D2O buffer in membrane-reconstituted alamethicin is interpreted in terms of stabilization by helical hydrogen bonding. Under conditions in which amide exchange occurred by partitioning of the peptide into solution, only lower limits for hydrogen-bond stabilities in the membrane were determined; all the potentially hydrogen-bonded amides of alamethicin are at least 1000-fold exchange protected in the membrane-bound state. When partitioning of alamethicin into the aqueous phase was suppressed by hydration of reconstituted vesicles in a limiting volume of water [D2O:dioleoylphosphatidylcholine:alamethicin; 220:1:0.05; (M:M:M)], the exchange-protection factors exhibited helical periodicity with highly exchange-protected, and less well-protected, amides on the nonpolar and polar helix faces, respectively. The exchange data indicate that, under the conditions studied, alamethicin adopts a stable helical structure in DOPC bilayers in which all the potentially hydrogen-bonded amides are stabilized by helical hydrogen bonds. The protection factors define the orientation of the peptide helix with respect to an aqueous phase, which is

  15. Development of point-contact spectrometer for spin polarization measurements

    NASA Astrophysics Data System (ADS)

    Shiga, M.; Nishimura, N.; Takata, H.; Inagaki, Y.; Kambara, H.; Tenya, K.; Kawae, T.

    2017-09-01

    We construct a “needle-anvil” type point-contact spectrometer for spin polarization measurements, which is installed in a 4He-cryostat. Two types of piezo devices are used to control the contact size precisely between a sample ferromagnet and a superconductor. An attocube piezo-based positioner is mounted for coarse movement of the tip, while a stacked-type piezo device is used for fine control of the contact size. This enables to change the contact size between the tip and sample from sub micro-meters to atomic-size contacts continuously. By suppressing thermal flow into the sample space and mechanical vibration, we can keep the contact over hours, enabling the precision measurements. To examine the performance of the spectrometer, we study the spin polarization of polycrystalline SrRuO3 with the point-contact Andreev reflection measurements. The polarization is estimated to be ∼0.59 at the clean limit of the interface, which is consistent with previous study.

  16. Cluster mass fraction and size distribution determined by fs-time-resolved measurements

    NASA Astrophysics Data System (ADS)

    Gao, Xiaohui; Wang, Xiaoming; Shim, Bonggu; Arefiev, Alexey; Tushentsov, Mikhail; Breizman, Boris; Downer, Mike

    2009-11-01

    Characterization of supersonic gas jets is important for accurate interpretation and control of laser-cluster experiments. While average size and total atomic density can be found by standard Rayleigh scatter and interferometry, cluster mass fraction and size distribution are usually difficult to measure. Here we determine the cluster fraction and the size distribution with fs-time-resolved refractive index and absorption measurements in cluster gas jets after ionization and heating by an intense pump pulse. The fs-time-resolved refractive index measured with frequency domain interferometer (FDI) shows different contributions from monomer plasma and cluster plasma in the time domain, enabling us to determine the cluster fraction. The fs-time-resolved absorption measured by a delayed probe shows the contribution from clusters of various sizes, allowing us to find the size distribution.

  17. Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating.

    PubMed

    Delong, K W; Ladera, C L; Trebino, R; Kohler, B; Wilson, K R

    1995-03-01

    Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms.

  18. Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating

    SciTech Connect

    DeLong, K.W.; Ladera, C.L.; Trebino, R.; Kohler, B.; Wilson, K.R.

    1995-03-01

    Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms.

  19. Time resolved measurement of charged particle distributions at electrodes in rf and pulsed plasma discharges

    NASA Astrophysics Data System (ADS)

    Gahan, David; Scullin, Paul; Dolinaj, Boris; O Sullivan, Donal; Hopkins, Mike

    2011-10-01

    Retarding field energy analyzers (RFEAs) are commonly used to measure the ion energy distribution function (IEDF) in plasma reactors. When deployed on grounded surfaces the RFEA design can be relatively simple due to the absence of large voltages. At biased surfaces the RFEA design is more complex. Filtering techniques need to be implemented to ensure the RFEA floats at the substrate holder potential. In cases where the discharge and/or substrate holder are driven with a pulsed bias the time resolved IEDFs through the pulse cycle are desirable. Time resolved measurements at a pulsed bias surface are more complicated, mainly because of the need to incorporate low pass filters with high input impedance to allow the RFEA to float at the bias potential. Here, we present a summary of the time resolved measurement capabilities of a RFEA in pulsed plasmas. Time resolved energy distributions of charged species are measured at the grounded electrode in capacitively coupled plasmas. The time resolved IEDFs at a biased electrode are also measured. The RFEA body is allowed to float at the bias potential using low pass filters and a novel technique is implemented to allow time resolution of the IEDF during the bias period. Time resolution of 100ns, at frequencies up to 500 kHz is demonstrated.

  20. Time-resolved measurement of Landau-Zener tunneling in periodic potentials.

    PubMed

    Zenesini, A; Lignier, H; Tayebirad, G; Radogostowicz, J; Ciampini, D; Mannella, R; Wimberger, S; Morsch, O; Arimondo, E

    2009-08-28

    We report time-resolved measurements of Landau-Zener tunneling of Bose-Einstein condensates in accelerated optical lattices, clearly resolving the steplike time dependence of the band populations. Using different experimental protocols we were able to measure the tunneling probability both in the adiabatic and in the diabatic bases of the system. We also experimentally determine the contribution of the momentum width of the Bose condensates to the temporal width of the tunneling steps and discuss the implications for measuring the jump time in the Landau-Zener problem.

  1. Time-Resolved Measurement of Landau-Zener Tunneling in Periodic Potentials

    SciTech Connect

    Zenesini, A.; Radogostowicz, J.; Ciampini, D.; Mannella, R.; Arimondo, E.; Lignier, H.; Morsch, O.; Tayebirad, G.; Wimberger, S.

    2009-08-28

    We report time-resolved measurements of Landau-Zener tunneling of Bose-Einstein condensates in accelerated optical lattices, clearly resolving the steplike time dependence of the band populations. Using different experimental protocols we were able to measure the tunneling probability both in the adiabatic and in the diabatic bases of the system. We also experimentally determine the contribution of the momentum width of the Bose condensates to the temporal width of the tunneling steps and discuss the implications for measuring the jump time in the Landau-Zener problem.

  2. Two-dimensional time resolved measurements of toroidal velocity correlated with density blobs in magnetized plasmas

    SciTech Connect

    Labit, B.; Furno, I.; Fasoli, A.; Podesta, M.

    2008-08-15

    A new method for toroidal velocity measurements with Mach probes is presented. This technique is based on the conditional sampling technique, the triggering events being density blobs. A reconstruction of the time resolved two-dimensional profile of electron density, electron temperature, plasma potential, and toroidal velocity is possible with a single point measurement on a shot-to-shot basis.

  3. Polarization measurements through space-to-ground atmospheric propagation paths by using a highly polarized laser source in space.

    PubMed

    Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo

    2009-12-07

    The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. An existing Japanese laser communication satellite and optical ground station were used to measure Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite. As a result, the polarization was preserved within an rms error of 1.6 degrees, and the degree of polarization was 99.4+/-4.4% through the space-to-ground atmosphere. These results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography worldwide in the future.

  4. Superthermal electron distribution measurements from polarized electron cyclotron emission

    SciTech Connect

    Luce, T.C.; Efthimion, P.C.; Fisch, N.J.

    1988-06-01

    Measurements of the superthermal electron distribution can be made by observing the polarized electron cyclotron emission. The emission is viewed along a constant magnetic field surface. This simplifies the resonance condition and gives a direct correlation between emission frequency and kinetic energy of the emitting electron. A transformation technique is formulated which determines the anisotropy of the distribution and number density of superthermals at each energy measured. The steady-state distribution during lower hybrid current drive and examples of the superthermal dynamics as the runaway conditions is varied are presented for discharges in the PLT tokamak. 15 refs., 8 figs.

  5. Time-resolved measurement of internal conversion dynamics in strong-field molecular ionization

    NASA Astrophysics Data System (ADS)

    Tagliamonti, Vincent; Kaufman, Brian; Zhao, Arthur; Rozgonyi, Tamás; Marquetand, Philipp; Weinacht, Thomas

    2017-08-01

    We time-resolve coupled electronic and nuclear dynamics during strong-field molecular ionization by measuring the momentum-resolved photoelectron yield as a function of pump-probe delay for a pair of strong-field laser pulses. The sub-10-fs pulses are generated using a specially designed ultrafast optical pulse shaper and the electrons are measured using velocity map imaging. Our measurements, in conjunction with calculations that solve the time-dependent Schrödinger equation, allow us to time-resolve resonance-enhanced strong-field ionization and break it down into three basic steps: (1) Stark-shifted resonant excitation of a high-lying neutral state of the molecule, (2) nonadiabatic dynamics (internal conversion) in which multiple electronic states are coupled, and (3) coupling to the continuum (ionization).

  6. Super-resolved pure-transverse focal fields with an enhanced energy density through focus of an azimuthally polarized first-order vortex beam.

    PubMed

    Li, Xiangping; Venugopalan, Priyamvada; Ren, Haoran; Hong, Minghui; Gu, Min

    2014-10-15

    We report on the experimental demonstration of super-resolved pure-transverse focal fields through focusing an azimuthally polarized first-order vortex (FOV) beam. The optimized confinement of focal fields by creating constructive interference through the superposition of the FOV on an azimuthally polarized beam is observed by both a scanning near-field microscope and a two-photon fluorescence microscope. An enhanced peak intensity of the focal spot by a factor of 1.8 has been observed compared with that of the unmodulated azimuthally polarized beam. The super-resolved and pure-transverse focal fields with a 31% reduced focal area determined by the full-width at half-maximum compared to that of tightly focused circular polarization is experimentally corroborated. This superiority over the circular polarization stands for any numerical aperture greater than 0.4. This technique holds the potential for applications requiring subwavelength resolution and pure-transverse fields such as high-density optical data storage and high-resolution microscopy.

  7. USGS Polar Temperature Logging System, Description and Measurement Uncertainties

    USGS Publications Warehouse

    Clow, Gary D.

    2008-01-01

    This paper provides an updated technical description of the USGS Polar Temperature Logging System (PTLS) and a complete assessment of the measurement uncertainties. This measurement system is used to acquire subsurface temperature data for climate-change detection in the polar regions and for reconstructing past climate changes using the 'borehole paleothermometry' inverse method. Specifically designed for polar conditions, the PTLS can measure temperatures as low as -60 degrees Celsius with a sensitivity ranging from 0.02 to 0.19 millikelvin (mK). A modular design allows the PTLS to reach depths as great as 4.5 kilometers with a skid-mounted winch unit or 650 meters with a small helicopter-transportable unit. The standard uncertainty (uT) of the ITS-90 temperature measurements obtained with the current PTLS range from 3.0 mK at -60 degrees Celsius to 3.3 mK at 0 degrees Celsius. Relative temperature measurements used for borehole paleothermometry have a standard uncertainty (urT) whose upper limit ranges from 1.6 mK at -60 degrees Celsius to 2.0 mK at 0 degrees Celsius. The uncertainty of a temperature sensor's depth during a log depends on specific borehole conditions and the temperature near the winch and thus must be treated on a case-by-case basis. However, recent experience indicates that when logging conditions are favorable, the 4.5-kilometer system is capable of producing depths with a standard uncertainty (uZ) on the order of 200-250 parts per million.

  8. Direct Measurement of the Resolving Power of X-ray CT System in SPring-8

    SciTech Connect

    Uesugi, Kentaro; Suzuki, Yoshio; Takano, Hidekazu; Yagi, Naoto

    2004-05-12

    Resolving power of high spatial resolution X-ray computed tomography (CT) system was evaluated by taking CT images of artificial test patterns at BL47XU in SPring-8 (SP-{mu}CT BL47XU). The system consists of an in-vacuum type undulator, a double crystal monochromator cooled with liquid nitrogen, a high precision sample stages and a high spatial resolution X-ray detector. For the precise measurement of the resolving power, the artificial test patterns of Cu/Al concentric multilayer were fabricated by DC sputtering deposition at AIST Kansai. 7 or 5 layers of Cu/Al are deposited by period of 2 {mu}m and 1 {mu}m. Therefore the resolving power could be measured at 4 {mu}m and 2 {mu}m with each test pattern. It was confirmed that the system had a resolving power of 2 {mu}m at 15keV from the CT images of test patterns. The resolution is not independent on the used energy. At 30keV, the resolving power was slightly poorer than 2 {mu}m. The result was consistent with the point spread functions of the high resolution detector measured by focused micro-beam.

  9. Direct measurement of the dielectric polarization properties of DNA

    PubMed Central

    Cuervo, Ana; Dans, Pablo D.; Carrascosa, José L.; Orozco, Modesto; Gomila, Gabriel; Fumagalli, Laura

    2014-01-01

    The electric polarizability of DNA, represented by the dielectric constant, is a key intrinsic property that modulates DNA interaction with effector proteins. Surprisingly, it has so far remained unknown owing to the lack of experimental tools able to access it. Here, we experimentally resolved it by detecting the ultraweak polarization forces of DNA inside single T7 bacteriophages particles using electrostatic force microscopy. In contrast to the common assumption of low-polarizable behavior like proteins (εr ∼ 2–4), we found that the DNA dielectric constant is ∼8, considerably higher than the value of ∼3 found for capsid proteins. State-of-the-art molecular dynamic simulations confirm the experimental findings, which result in sensibly decreased DNA interaction free energy than normally predicted by Poisson–Boltzmann methods. Our findings reveal a property at the basis of DNA structure and functions that is needed for realistic theoretical descriptions, and illustrate the synergetic power of scanning probe microscopy and theoretical computation techniques. PMID:25136104

  10. Coronal magnetic fields from the inversion of linear polarization measurements

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Lin, Haosheng; Kuhn, Jeff

    2010-02-01

    Real 3-D coronal magnetic field reconstruction is expected to be made based on the technologies of IR spectrometry and tomography, in which the data from other wavelengths can be used as critical reference. Our recent studies focused on this issue are briefly reviewed in this paper. Liu & Lin (2008) first evaluated the validity of potential field source surface model applied to one of five limb regions in the corona by comparing the theoretical polarization maps with SOLARC observations in the IR Fe XIII 10747 Å forbidden coronal emission line (CEL). The five limb coronal regions were then studied together in order to study the spatial relation between the bright EUV features on the solar disk and the inferred IR emission sources, which were obtained from the inversion of the SOLARC linear polarization (LP) measurements (Liu 2009). The inversion for each fiber data in the field of view was made by finding the best location where the difference between the synthesized and the observed polarizations reaches the minimum in the integration path along the line of sight. We found a close relationship between the inferred IR emission source locations and the EUV strong emission positions.

  11. Polarizers, optical bridges, and Sagnac interferometers for nanoradian polarization rotation measurements

    NASA Astrophysics Data System (ADS)

    Rowe, A. C. H.; Zhaksylykova, I.; Dilasser, G.; Lassailly, Y.; Peretti, J.

    2017-04-01

    The ability to measure nanoradian polarization rotations, θF, in the photon shot noise limit is investigated for partially crossed polarizers (PCP), a static Sagnac interferometer, and an optical bridge, each of which can in principle be used in this limit with near equivalent figures-of-merit (FOM). In practice a bridge to PCP/Sagnac source noise rejection ratio of 1 /4 θF2 enables the bridge to operate in the photon shot noise limit even at high light intensities. The superior performance of the bridge is illustrated via the measurement of a 3 nrad rotation arising from an axial magnetic field of 0.9 nT applied to a terbium gallium garnet. While the Sagnac is functionally equivalent to the PCP in terms of the FOM, unlike the PCP it is able to discriminate between rotations with different time (T) and parity (P) symmetries. The Sagnac geometry implemented here is similar to that used elsewhere to detect non-reciprocal (T ¯ P ) rotations like those due to the Faraday effect. Using a Jones' matrix approach, novel Sagnac geometries uniquely sensitive to non-reciprocal T P ¯ (e.g. magneto-electric or magneto-chiral) rotations, as well as to reciprocal rotations (e.g. due to linear birefringence, TP, or to chirality, T P ¯ ) are proposed.

  12. 3D measurements in the polar mesosphere using coherent radar imaging

    NASA Astrophysics Data System (ADS)

    Zecha, M.; Sommer, S.; Rapp, M.; Stober, G.; Latteck, R.

    2012-12-01

    Radars provide the opportunity of continuous measurements in the interesting area of the polar mesosphere. Usually the spatial resolution of measurements by pulsed VHF radars is limited by the radar beam width, transmitting pulse length, and sampling time. Due to these technical restrictions the typical small-scale structures in the mesosphere often cannot be resolved. Furthermore the quality of the estimation of dynamic atmosphere parameters is reduced if the position and direction of scatter returns cannot determined exactly. Radar interferometry methods have been developed to reduce these limitations. The coherent radar imaging method gives a high resolving image of the scatter structure insight the radar beam volume. In recent years the VHF radar MAARSY was installed in Andenes/Norway (69°N). This new radar was designed to allow improved three-dimensional observations in the atmosphere. It consists of 433 Yagis and allows a minimum beam width of about 4 degree. The beam direction can be changed pulse-by-pulse freely in azimuth angle and practicable up to 40 degree in zenith angle. The pulse length can be varied from a couple of km down to 50 m. Up to 16 receiving channels of spaced antennas can be used. In this presentation we show the detection of the angles-of-arrival of radar echoes and the correction of the wind measurements. We demonstrate the improvement of measurement results by using coherent radar imaging. The differences to the results of conventional methods depend on the beam width, range resolution, antenna distances, and beam tilting. We show that the application of interferometry is necessary to improve considerably the quality of 3D-measurement results. Furthermore we demonstrate the synthesis of high resolved images to get a real 3D image of the mesosphere.

  13. FIRST DIRECT MEASUREMENTS OF TRANSVERSE WAVES IN SOLAR POLAR PLUMES USING SDO/AIA

    SciTech Connect

    Thurgood, J. O.; Morton, R. J.; McLaughlin, J. A.

    2014-07-20

    There is intense interest in determining the precise contribution of Alfvénic waves propagating along solar structures to the problems of coronal heating and solar wind acceleration. Since the launch of SDO/AIA, it has been possible to resolve transverse oscillations in off-limb solar polar plumes and recently McIntosh et al. concluded that such waves are energetic enough to play a role in heating the corona and accelerating the fast solar wind. However, this result is based on comparisons to Monte Carlo simulations and confirmation via direct measurements is still outstanding. Thus, this Letter reports on the first direct measurements of transverse wave motions in solar polar plumes. Over a four hour period, we measure the transverse displacements, periods, and velocity amplitudes of 596 distinct oscillations observed in the 171 Å channel of SDO/AIA. We find a broad range of non-uniformly distributed parameter values which are well described by log-normal distributions with peaks at 234 km, 121 s, and 8 km s{sup –1}, and mean and standard deviations of 407 ± 297 km, 173 ± 118 s, and 14 ± 10 km s{sup –1}. Within standard deviations, our direct measurements are broadly consistent with previous results. However, accounting for the whole of our observed non-uniform parameter distribution we calculate an energy flux of 9-24 W m{sup –2}, which is 4-10 times below the energy requirement for solar wind acceleration. Hence, our results indicate that transverse magnetohydrodynamic waves as resolved by SDO/AIA cannot be the dominant energy source for fast solar wind acceleration in the open-field corona.

  14. Measurements of the polarization observables IS and Ic for γp→pπ+π- using the clas spectr

    NASA Astrophysics Data System (ADS)

    Hanretty, Charles; CLAS Collaboration

    2012-04-01

    Constituent Quark Models predict an excited baryon spectrum much richer in resonances than that which has been observed experimentally, the so-called missing resonance problem. Evidence for the production of these short-lived states may come about through measurements of quantities called polarization observables. These observables occur when the constraint of polarization is imposed on the reactions and are highly sensitive to resonance production. The expected sequential decay of these N* resonances via πΔ and NΔ intermediate states makes the double pion final state an attractive final state to study to reveal these missing resonances. In recent years, both single-and double-polarization experiments have been carried out as part of the N* program at Jefferson Lab in Newport News, Virginia with the goal of resolving this missing resonance problem. One such polarized photoproduction experiment used linearly polarized photons incident on an unpolarized LH2 target. The analysis of γp→pπ+π- reactions found in these polarized photoproduction data using the power of a kinematic fitter results in highly accurate measurements of these observables. The analysis of this pπ+π- final state and the extraction of two such observables, IS and Ic, will be discussed.

  15. Data processing workflow for time of flight polarized neutrons inelastic measurements

    NASA Astrophysics Data System (ADS)

    Savici, Andrei T.; Zaliznyak, Igor A.; Ovidiu Garlea, V.; Winn, Barry

    2017-06-01

    We discuss the data processing workflow for polarized neutron scattering measurements performed at HYSPEC [1] spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The effects of the focusing Heusler crystal polarizer and the wide- angle supermirror transmission polarization analyzer are added to the data processing flow of the non-polarized case. The implementation is done using the Mantid [2] software package.

  16. Data processing workflow for time of flight polarized neutrons inelastic measurements

    SciTech Connect

    Savici, Andrei T; Zaliznyak, Igor; Garlea, Vasile O; Winn, Barry L

    2017-01-01

    We discuss the data processing workflow for polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The effects of the focusing Heusler crystal polarizer and the wide-angle supermirror transmission polarization analyzer are added to the data processing flow of the non-polarized case. The implementation is done using the Mantid software package.

  17. A technique for measuring vertically and horizontally polarized microwave brightness temperatures using electronic polarization-basis rotation

    NASA Technical Reports Server (NTRS)

    Gasiewski, Albin J.

    1992-01-01

    This technique for electronically rotating the polarization basis of an orthogonal-linear polarization radiometer is based on the measurement of the first three feedhorn Stokes parameters, along with the subsequent transformation of this measured Stokes vector into a rotated coordinate frame. The technique requires an accurate measurement of the cross-correlation between the two orthogonal feedhorn modes, for which an innovative polarized calibration load was developed. The experimental portion of this investigation consisted of a proof of concept demonstration of the technique of electronic polarization basis rotation (EPBR) using a ground based 90-GHz dual orthogonal-linear polarization radiometer. Practical calibration algorithms for ground-, aircraft-, and space-based instruments were identified and tested. The theoretical effort consisted of radiative transfer modeling using the planar-stratified numerical model described in Gasiewski and Staelin (1990).

  18. Measurement of W Boson Polarization in Top Quark Decay

    SciTech Connect

    Vickey, Trevor Neil

    2004-01-01

    A measurement of the polarization of the W boson from top quark decay is an excellent test of the V-A form of the charged-current weak interaction in the standard model. Since the longitudinal W boson is intimately related to the electroweak symmetry breaking mechanism, and the standard model gives a specific prediction for the fraction of longitudinal W bosons from top decays, it is of particular interest for study. This thesis presents a measurement of W boson polarization in top quark decays through an analysis of the cosθ* distribution in the lepton-plus-jets channel of t$\\bar{t}$ candidate events from p$\\bar{p}$ collisions at √s = 1.96 TeV. This measurement uses an integrated luminosity of ~ 162 pb-1 of data collected with the CDF Run II detector, resulting in 31 t$\\bar{t}$ candidate events with at least one identified b jet. Using a binned likelihood fit to the cosθ* distribution from the t$\\bar{t}$ candidate events found in this sample, the fraction of W bosons with longitudinal polarization is determined to be F0 = 0.99$+0.29\\atop{-0.35}$stat.) ± 0.19(syst.), F0 > 0.33 @ 95% CL. This result is consistent with the standard model prediction, given a top quark mass of 174.3 GeV/c2, of F0 = 0.701 ± 0.012.

  19. Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24

    NASA Technical Reports Server (NTRS)

    Karna, N.; Webber, S.A. Hess; Pesnell, W.D.

    2014-01-01

    An analysis of solar polar coronal hole (PCH) areas since the launch of the Solar Dynamics Observatory (SDO) shows how the polar regions have evolved during Solar Cycle 24. We present PCH areas from mid-2010 through 2013 using data from the Atmospheric Imager Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard SDO. Our analysis shows that both the northern and southern PCH areas have decreased significantly in size since 2010. Linear fits to the areas derived from the magnetic-field properties indicate that, although the northern hemisphere went through polar-field reversal and reached solar-maximum conditions in mid-2012, the southern hemisphere had not reached solar-maximum conditions in the polar regions by the end of 2013. Our results show that solar-maximum conditions in each hemisphere, as measured by the area of the polar coronal holes and polar magnetic field, will be offset in time.

  20. Photonic polarization gears for ultra-sensitive angular measurements

    PubMed Central

    D'Ambrosio, Vincenzo; Spagnolo, Nicolò; Del Re, Lorenzo; Slussarenko, Sergei; Li, Ying; Kwek, Leong Chuan; Marrucci, Lorenzo; Walborn, Stephen P.; Aolita, Leandro; Sciarrino, Fabio

    2013-01-01

    Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a ‘photonic gear’, converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a ‘super-resolving’ Malus’ law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high ‘gear ratio’ m boosts the current state of the art of optical non-contact angular measurements by almost two orders of magnitude. PMID:24045270

  1. Positive and negative polarity contrast sensitivity measuring app.

    PubMed

    Hwang, Alex D; Peli, Eli

    2016-01-01

    Contrast sensitivity (CS) quantifies an observer's ability to detect the smallest (threshold) luminance difference between a target and its surrounding. In clinical settings, printed letter contrast charts are commonly used, and the contrast of the letter stimuli is specified by the Weber contrast definition. Those paper-printed charts use negative polarity contrast (NP, dark letters on bright background) and are not available with positive polarity contrast (PP, bright letters on dark background), as needed in a number of applications. We implemented a mobile CS measuring app supporting both NP and PP contrast stimuli that mimic the paper charts for NP. A novel modified Weber definition was developed to specify the contrast of PP letters. The validity of the app is established in comparison with the paper chart. We found that our app generates more accurate and a wider range of contrast stimuli than the paper chart (especially at the critical high CS, low contrast range), and found a clear difference between NP and PP CS measures (CSNP>CSPP) despite the symmetry afforded by the modified Weber contrast definition. Our app provides a convenient way to measure CS in both lighted and dark environments.

  2. Positive and negative polarity contrast sensitivity measuring app

    PubMed Central

    Hwang, Alex D.; Peli, Eli

    2017-01-01

    Contrast sensitivity (CS) quantifies an observer’s ability to detect the smallest (threshold) luminance difference between a target and its surrounding. In clinical settings, printed letter contrast charts are commonly used, and the contrast of the letter stimuli is specified by the Weber contrast definition. Those paper-printed charts use negative polarity contrast (NP, dark letters on bright background) and are not available with positive polarity contrast (PP, bright letters on dark background), as needed in a number of applications. We implemented a mobile CS measuring app supporting both NP and PP contrast stimuli that mimic the paper charts for NP. A novel modified Weber definition was developed to specify the contrast of PP letters. The validity of the app is established in comparison with the paper chart. We found that our app generates more accurate and a wider range of contrast stimuli than the paper chart (especially at the critical high CS, low contrast range), and found a clear difference between NP and PP CS measures (CSNP>CSPP) despite the symmetry afforded by the modified Weber contrast definition. Our app provides a convenient way to measure CS in both lighted and dark environments. PMID:28649669

  3. Absolute Spatially- and Temporally-Resolved Optical Emission Measurements of rf Glow Discharges in Argon

    PubMed Central

    Djurović, S.; Roberts, J. R.; Sobolewski, M. A.; Olthoff, J. K.

    1993-01-01

    Spatially- and temporally-resolved measurements of optical emission intensities are presented from rf discharges in argon over a wide range of pressures (6.7 to 133 Pa) and applied rf voltages (75 to 200 V). Results of measurements of emission intensities are presented for both an atomic transition (Ar I, 750.4 nm) and an ionic transition (Ar II, 434.8 nm). The absolute scale of these optical emissions has been determined by comparison with the optical emission from a calibrated standard lamp. All measurements were made in a well-defined rf reactor. They provide detailed characterization of local time-resolved plasma conditions suitable for the comparison with results from other experiments and theoretical models. These measurements represent a new level of detail in diagnostic measurements of rf plasmas, and provide insight into the electron transport properties of rf discharges. PMID:28053464

  4. Resolving the 180-degree ambiguity in vector magnetic field measurements: The 'minimum' energy solution

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.

    1994-01-01

    I present a robust algorithm that resolves the 180-deg ambiguity in measurements of the solar vector magnetic field. The technique simultaneously minimizes both the divergence of the magnetic field and the electric current density using a simulated annealing algorithm. This results in the field orientation with approximately minimum free energy. The technique is well-founded physically and is simple to implement.

  5. Resolving the 180-degree ambiguity in vector magnetic field measurements: The 'minimum' energy solution

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.

    1994-01-01

    I present a robust algorithm that resolves the 180-deg ambiguity in measurements of the solar vector magnetic field. The technique simultaneously minimizes both the divergence of the magnetic field and the electric current density using a simulated annealing algorithm. This results in the field orientation with approximately minimum free energy. The technique is well-founded physically and is simple to implement.

  6. Spatially-resolved spectroscopic technique for measuring optical properties of food

    USDA-ARS?s Scientific Manuscript database

    Quantification of optical properties is important to understand light interaction with biological materials, and to develop effective optical sensing techniques for property characterization and quality measurement of food products. This chapter reviews spatially-resolved method, with the focus on f...

  7. Measurement of Inner Bremsstrahlung in Polarized Muon Decay with MEG

    NASA Astrophysics Data System (ADS)

    Adam, J.; Bai, X.; Baldini, A. M.; Baracchini, E.; Bemporad, C.; Boca, G.; Cattaneo, P. W.; Cavoto, G.; Cei, F.; Cerri, C.; de Bari, A.; De Gerone, M.; Doke, T.; Dussoni, S.; Egger, J.; Fratini, K.; Fujii, Y.; Galli, G.; Gallucci, L.; Gatti, F.; Golden, B.; Grassi, M.; Grigoriev, D. N.; Haruyama, T.; Hildebrandt, M.; Hisamatsu, Y.; Ignatov, F.; Iwamoto, T.; Kettle, P.-R.; Khazin, B. I.; Kiselev, O.; Korenchenko, A.; Kravchuk, N.; Maki, A.; Mihara, S.; Molzon, W.; Mori, T.; Mzavia, D.; Natori, H.; Nicolò, D.; Nishiguchi, H.; Nishimura, Y.; Ootani, W.; Panareo, M.; Papa, A.; Pazzi, R.; Piredda, G.; Popov, A.; Renga, F.; Ritt, S.; Rossella, M.; Sawada, R.; Sergiampietri, F.; Signorelli, G.; Suzuki, S.; Tenchini, F.; Topchyan, C.; Uchiyama, Y.; Valle, R.; Voena, C.; Xiao, F.; Yamada, S.; Yamamoto, A.; Yamashita, S.; Yudin, Yu. V.; Zanello, D.

    2014-03-01

    A muon decay accompanied by a photon through the inner Bremmstrahlung process (μ→eννbarγ, radiative muon decay) produces a time-correlated pair of positron and photon which becomes one of the main backgrounds in the search for μ→eγ decay. This channel is also an important probe of timing calibration and cross-check of whole the experiment. We identified a large sample (∼ 13000) of radiative muon decays in MEG data sample. The measured branching ratio in a region of interest in the μ→eγ search is consistent with the standard model prediction. It is also the first measurement of the decay from polarized muons. The precision measurement of this mode enables us to use it as one of the normalization channels of μ→eγ decay successfully reducing its uncertainty to less than 5%.

  8. Single shot, temporally and spatially resolved measurements of fast electron dynamics using a chirped optical probe

    NASA Astrophysics Data System (ADS)

    Green, J. S.; Murphy, C. D.; Booth, N.; Dance, R. J.; Gray, R. J.; MacLellan, D. A.; McKenna, P.; Rusby, D.; Wilson, L.

    2014-03-01

    A new approach to rear surface optical probing is presented that permits multiple, time-resolved 2D measurements to be made during a single, ultra-intense ( > 1018 W cm-2) laser-plasma interaction. The diagnostic is capable of resolving rapid changes in target reflectivity which can be used to infer valuable information on fast electron transport and plasma formation at the target rear surface. Initial results from the Astra-Gemini laser are presented, with rapid radial sheath expansion together with detailed filamentary features being observed to evolve during single shots.

  9. Subpicosecond measurements of polar solvation dynamics: Coumarin 153 revisited

    SciTech Connect

    Horng, M.L.; Gardecki, J.A.; Papazyan, A.; Maroncelli, M.

    1995-11-30

    Time-resolved emission measurements of the solute coumarin 153 (C153) are used to probe the time dependence of solvation in 24 common solvents at room temperature. Significant improvements in experimental time resolution ({approx}100 fs instrument response) as well as corresponding improvements in analysis methods provide confidence that all of the spectral evolution (including both the inertial and the diffusive parts of the response) are observed in these measurements. Extensive data concerning the steady-state solvatochromism of C153, coupled to an examination of the effects of vibrational relaxation, further demonstrate that the spectral dynamics being observed accurately monitor the dynamics of nonspecific solvation. Comparisons to theoretical predictions show that models based on the dielectric response of the pure solvent provide a semiquantitative understanding of the dynamics observed. 156 refs., 26 figs., 5 tabs.

  10. Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements

    NASA Astrophysics Data System (ADS)

    Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.

    2013-04-01

    Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a

  11. SAM 2 measurements of the polar stratospheric aerosol, volume 5

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Brandl, D.

    1985-01-01

    The Stratospheric Aerosol Measurement (SAM) 2 sensor is aboard the Earth-orbiting Nimbus 7 spacecraft providing extinction measurements of the Antarctic and Arctic stratospheric aerosol with a vertical resolution of 1 km. Representative examples and weekly averages of aerosol data and corresponding temperature profiles for the time and place of each SAM 2 mesurement (Oct. 1980 through Apr. 1981) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted and weekly aerosol optical depths are calculated. Seasonal variations and variations in space (altitude and longitude) for both polar regions are easily seen. Stratospheric optical depths are 0.002 to 0.003 for the Antarctic region and 0.005 to 0.006 at the beginning to 0.002 to 0.003 at the end of the time period for the Arctic region. The Northern Hemisphere values are quite large due mainly to the eruption of Mount St. Helens (46.2 deg N, 122.2 deg W) in May 1980. Polar stratospheric clouds at altitudes of about 20 km were observed during the Arctic winter. A ready-to-use format containing a representative sample of the fifth 6 months of data to be used in atmospheric and climatic studies is presented.

  12. Measuring A{sub b} with polarized beams at SLC

    SciTech Connect

    Junk, T.R.; SLD Collaboration

    1994-05-01

    We present the first direct measurement of the left-right asymmetry of b-quarks from the decay of Z{sup 0} bosons produced in the annihilation of longitudinally polarized electrons and unpolarized positrons in the SLD at the SLC. Two complementary techniques are presented: (1) Z{sup 0} {yields} b{bar b} decays are tagged using track impact parameters measured with a CCD-based vertex detector with b {minus} {bar b} discrimination provided by momentum-weighted track charge; (2) Semileptonic b-decays are tagged using high (P, P{sub T}) muons and electrons with b {minus} {bar b} discrimination provided by the lepton charge. In our 1993 sample of {approximately}50,000 Z{sup 0} decays having a luminosity-weighted average e{sup {minus}} polarization of (62.6{plus_minus}1.2)%, we find the following preliminary results: A{sub b}(track charge) = 1.01{plus_minus}0.12(stat) {plus_minus}0.14(sys), A{sub b}(muons) = 0.94{plus_minus}0.25(stat){plus_minus}0.11(sys), and A{sub b}(electrons) 0.99{plus_minus}0.27(stat){plus_minus} 0.19(sys).

  13. Passive measurement and interpretation of polarized microwave brightness temperatures

    NASA Technical Reports Server (NTRS)

    Gasiewski, A. J.; Kunkee, D. B.; Piepmeier, J. R.

    1995-01-01

    The goal of this project is to develop satellite-based observational techniques for measuring both oceanic and atmospheric variables using passive polarimetric radiometry. Polarimetric radiometry offers a potential alternative to radar scatterometry in observing global ocean surface wind direction from satellites. Polarimetric radiometry might also provide a means of detecting cell-top ice in convective storms by virtue of the polarizing properties of oriented ice particles, and thus facilitate estimation of the phase of the storm. The project focuses on the development of polarimetric microwave radiometers using digital cross-correlators for obtaining precise measurements of all four Stokes' parameters. As part of the project a unique four-band polarimetric imaging radiometer, the Polar Scanning Radiometer (PSR), is being designed for use on the NASA DC-8 aircraft. In addition to providing an aircraft-based demonstration of digital correlation technology the PSR will significantly enhance the microwave imaging capability of the existing suite of DC-8 instruments. During the first grant year excellent progress has been made in the following areas: (1) demonstrating digital correlation radiometry, (2) fabricating aircraft-qualified correlators for use in the PSR, and (3) modeling observed SSM/I brightness signatures of ocean wind direction.

  14. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

    SciTech Connect

    Haugh, M. J. Jacoby, K. D.; Wu, M.; Loisel, G. P.

    2014-11-15

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  15. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals.

    PubMed

    Haugh, M J; Wu, M; Jacoby, K D; Loisel, G P

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  16. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystalsa)

    NASA Astrophysics Data System (ADS)

    Haugh, M. J.; Wu, M.; Jacoby, K. D.; Loisel, G. P.

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  17. Measuring the X-ray Resolving Power of Bent Potassium Acid Phthalate Diffraction Crystals

    SciTech Connect

    Haugh, M. J.; Wu, M.; Jacoby, K. D.; Loisel, G. P.

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories (SNL) in Albuquerque, NM. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a dual goniometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  18. Evaluation of a novel fiber probe for spatially and spectrally resolved reflectance measurements of turbid media

    NASA Astrophysics Data System (ADS)

    Andree, Stefan; Luckmann, Heiko; Reble, Carina; Gersonde, Ingo; Helfmann, Jürgen

    2011-07-01

    A novel fiber probe for spatially resolved reflectance measurements is presented, which uses simultaneously read-out spectrometers for each source-detector separation. Therefore, with this fiber probe and a Monte Carlo simulation, it is possible to determine spectrally resolved absorption and reduced scattering coefficients from various skinsites. The absolute calibration is done by using an integrating sphere but a phantom based calibration procedure was undertaken to compare the results of different calibration techniques. For tissue measurements, a standard SMA adaptor with a one inch diameter face can be used to provide a stable base for placing the probe onto the tissue and the possibility to apply pressure. The evaluation process was carried out by comparing the measured absorption and scattering of silicone and liquid phantoms to their reference values, obtained by integrating sphere spectroscopy. In addition, preliminary skin measurements are presented.

  19. [Some problems in measuring the frequency-resolving power of hearing].

    PubMed

    Supin, A Ia

    2004-08-01

    In spite of detailed elaboration of masking methods of measuring the frequency selectivity of hearing, such measurements actually are not in use for diagnostics purpose because of their time-consumption and ambiguity of extrapolation of the results to perception of complex sound spectrum patterns. A method of direct measuring of spectrum resolving power using rippled-noise test, is suggested. Results of measurements have shown that the actual ability of hearing to discriminate complex sound spectra is higher than that predicted by acuteness of auditory frequency filters: dependence of acuteness of auditory frequency filters on sound level does not influence the ability to discriminate complex spectra; and the influence on interfering noise on the frequency resolving power can not be explained by a decrease of the spectral contrast by the spread of excitation.

  20. Measurement of parameters of polarization in the living human eye using imaging polarimetry.

    PubMed

    Bueno, J M

    2000-01-01

    An imaging polarimeter using liquid-crystal variable retarders (Bueno, J. M., Artal, P. (1999). Double-pass imaging polarimetry in the human eye. Optics Letters, 24, 64-66) has been used to study the parameters of polarization in the living human eye. Retardation introduced by birefringent structures of the eye has been calculated by using a spatially resolved collection of Mueller matrices obtained from series of 16 double-pass retinal images. Results for images with a 2-mm pupil diameter show that although the retardation introduced by the eye in a double-pass varies among individuals, at the central cornea the slow axis is directed along the upper-temporal to lower-nasal line and the ellipticity is close to zero, which indicates the presence of linear birefringence. As pupil size increased, the measured retardation also increased, while ocular birefringence remained linear and azimuthal angle changed without a clear tendency.

  1. Frequency-resolved noise figure measurements of phase (in)sensitive fiber optical parametric amplifiers.

    PubMed

    Malik, R; Kumpera, A; Lorences-Riesgo, A; Andrekson, P A; Karlsson, M

    2014-11-17

    We measure the frequency-resolved noise figure of fiber optical parametric amplifiers both in phase-insensitive and phase-sensitive modes in the frequency range from 0.03 to 3 GHz. We also measure the variation in noise figure due to the degradation in pump optical signal to noise ratio and also as a function of the input signal powers. Noise figure degradation due to stimulated Brillouin scattering is observed.

  2. Novel technique for measuring the vector polarization of a deuteron

    SciTech Connect

    Bonner, B.E.; McNaughton, M.W.; van Dyck, O.B.; Turpin, S.E.; Hollas, C.L.; Cremans, D.J.; Riley, P.J.; Rodebaugh, R.F.; Aas, B.; Weston, G.S.

    1983-01-01

    The usual method of double scattering that is employed for measuring the vector polarization (P = 2/..sqrt..3 it/sub 11/) of final state deuterons in a reaction is to use the appreciable analyzing power available for certain angular regions of elastic scattering or deuteron initiated reactions. For increasing deuteron energies the cross section and/or analyzing power for such processes generally decreases, thus limiting the utility of this technique at intermediate energies. We recently developed a method for measuring it/sub 11/ and demonstrated its validity for deuterons in the energy range 500 to 600 MeV. The technique should be applicable for deuteron energies in the range 400 MeV to a few GeV. A brief description of the technique is given.

  3. Neutron Polarization Measurements with a 3He Spin Filter for the NPDGamma Experiment

    NASA Astrophysics Data System (ADS)

    Musgrave, Matthew

    2012-10-01

    The Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS) provides a pulsed beam of polarized cold neutrons for the NPDGamma experiment which intends to measure the parity violating asymmetry in the emitted gamma rays from the capture of polarized neutrons on protons in a para-hydrogen target. The neutrons are polarized by a multi-channel super mirror polarizer, and the polarization of each neutron pulse can be flipped with an RF spin rotator. The accuracy of the NPDGamma experiment and various commissioning experiments is dependent on the polarization of the neutron beam and the efficiency of the RF spin rotator. These parameters are measured with a polarized 3He spin filter at multiple points in the beam cross section and with multiple 3He polarizations. The measured neutron polarization is compared to a McStas model to validate our results and our beam averaging technique. The analysis methods, background effects, and results will be discussed.

  4. Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics

    PubMed Central

    Gorfman, S.; Simons, H.; Iamsasri, T.; Prasertpalichat, S.; Cann, D. P.; Choe, H.; Pietsch, U.; Watier, Y.; Jones, J. L.

    2016-01-01

    Structure-property relationships in ferroelectrics extend over several length scales from the individual unit cell to the macroscopic device, and with dynamics spanning a broad temporal domain. Characterizing the multi-scale structural origin of electric field-induced polarization reversal and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice strain and, for the first time, polarization reversal during in-situ electrical perturbation. This technique is demonstrated for BaTiO3-BiZn0.5Ti0.5O3 (BT-BZT) polycrystalline ferroelectrics, a prototypical lead-free piezoelectric with an ambiguous switching mechanism. This combines the benefits of spectroscopic and diffraction-based measurements into a single and robust technique with time resolution down to the ns scale, opening a new door to in-situ structure-property characterization that probes the full extent of the ferroelectric behaviour. PMID:26864859

  5. Microlensed dual-fiber probe for depth-resolved fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Choi, Hae Young; Ryu, Seon Young; Kim, Jae Young; Kim, Geon Hee; Park, Seong Jun; Lee, Byeong Ha; Chang, Ki Soo

    2011-07-01

    We propose and demonstrate a compact microlensed dual-fiber probe that has a good collection efficiency and a high depth-resolution ability for fluorescence measurements. The probe is formed with a conventional fusion splicer creating a common focusing lens on two fibers placed side by side. The collection efficiency of the fabricated probe was evaluated by measuring the fluorescence signal of a fresh ginkgo leaf. It was shown experimentally that the proposed probe could effectively collect the fluorescence signal with a six-fold increase compared to that of a general flat-tipped probe. The beam propagation method was used to design a probe with an optimized working distance and an improved resolving depth. It was found that the working distance depends mainly on the radius of curvature of the lens, whereas the resolving depth is determined by the core diameters of the illumination and collection fibers. The depth-resolved ability of probes with working distances of ~100 μm and 300 μm was validated by using a two-layer tissue phantom. The experimental results demonstrate that the microlensed dual-fiber probe has the potential to facilitate depth-resolved fluorescence detection of epithelial tissue.

  6. Phase-resolved surface pressure and heat-transfer measurements on the blade of a two-stage turbine

    SciTech Connect

    Dunn, M.G.; Haldeman, C.W. Jr.

    1995-12-01

    Phase-resolved surface pressure, and unsteady pressure measurements are reported for the first-stage blade row of the Space Shuttle Main Engine two-stage fuel-side turbine. Measurements were made at 10, 50, and 90 percent span on both the pressure and suction surfaces of the blade. Phase-resolved and unsteady heat-flux measurements are also reported.

  7. Towards Measurement of the Time-resolved Heat Release of Protein Conformation Dynamics

    NASA Technical Reports Server (NTRS)

    Puchalla, Jason; Adamek, Daniel; Austin, Robert

    2004-01-01

    We present a way to observe time-resolved heat release using a laminar flow diffusional mixer coupled with a highly sensitive infrared camera which measures the temperature change of the solvent. There are significant benefits to the use of laminar flow mixers for time-resolved calorimetry: (1) The thermal signal can be made position and time- stationary to allow for signal integration; (2) Extremely small volumes (nl/s) of sample are required for a measurement; (3) The same mixing environment can be observed spectroscopically to obtain state occupation information; (4) The mixer allows one to do out of equilibrium dynamic studies. The hope is that these measurements will allow us probe the non-equilibrium thermodynamics as a protein moves along a free energy trajectory from one state to another.

  8. Towards Measurement of the Time-resolved Heat Release of Protein Conformation Dynamics

    NASA Technical Reports Server (NTRS)

    Puchalla, Jason; Adamek, Daniel; Austin, Robert

    2004-01-01

    We present a way to observe time-resolved heat release using a laminar flow diffusional mixer coupled with a highly sensitive infrared camera which measures the temperature change of the solvent. There are significant benefits to the use of laminar flow mixers for time-resolved calorimetry: (1) The thermal signal can be made position and time- stationary to allow for signal integration; (2) Extremely small volumes (nl/s) of sample are required for a measurement; (3) The same mixing environment can be observed spectroscopically to obtain state occupation information; (4) The mixer allows one to do out of equilibrium dynamic studies. The hope is that these measurements will allow us probe the non-equilibrium thermodynamics as a protein moves along a free energy trajectory from one state to another.

  9. Spectrum Resolving Power of Hearing: Measurements, Baselines, and Influence of Maskers

    PubMed Central

    Supin, Alexander Ya.

    2011-01-01

    Contemporary methods of measurement of frequency resolving power in the auditory system are reviewed. Majority of classical methods are based on the frequency-selective masking paradigm and require multi-point measurements (a number of masked thresholds should be measured to obtain a single frequency-tuning estimate). Therefore, they are rarely used for practical needs. As an alternative approach, frequency-selective properties of the auditory system may be investigated using probes with complex frequency spectrum patterns, in particular, rippled noise that is characterized by a spectrum with periodically alternating maxima and minima. The maximal ripple density discriminated by the auditory system is a convenient measure of the spectrum resolving power (SRP). To find the highest resolvable ripple density, a phase-reversal test has been suggested. Using this technique, normal SRP, its dependence on probe center frequency, spectrum contrast, and probe level were measured. The results were not entirely predictable by frequency-tuning data obtained by masking methods. SRP is influenced by maskers, with on- and off-frequency maskers influencing SRP very differently. Dichotic separation of the probe and masker results in almost complete release of SRP from influence of maskers. PMID:26557320

  10. Spectrum Resolving Power of Hearing: Measurements, Baselines, and Influence of Maskers.

    PubMed

    Supin, Alexander Ya

    2011-07-01

    Contemporary methods of measurement of frequency resolving power in the auditory system are reviewed. Majority of classical methods are based on the frequency-selective masking paradigm and require multi-point measurements (a number of masked thresholds should be measured to obtain a single frequency-tuning estimate). Therefore, they are rarely used for practical needs. As an alternative approach, frequency-selective properties of the auditory system may be investigated using probes with complex frequency spectrum patterns, in particular, rippled noise that is characterized by a spectrum with periodically alternating maxima and minima. The maximal ripple density discriminated by the auditory system is a convenient measure of the spectrum resolving power (SRP). To find the highest resolvable ripple density, a phase-reversal test has been suggested. Using this technique, normal SRP, its dependence on probe center frequency, spectrum contrast, and probe level were measured. The results were not entirely predictable by frequency-tuning data obtained by masking methods. SRP is influenced by maskers, with on- and off-frequency maskers influencing SRP very differently. Dichotic separation of the probe and masker results in almost complete release of SRP from influence of maskers.

  11. Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

    DOE PAGES

    MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.; ...

    2016-09-22

    We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer was used to obtain spatially-resolved measurements of Ti K-more » $$\\alpha$$ emission. Density profiles were measured from K-$$\\alpha$$ intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-$$\\alpha$$ spectra to spectra from CRETIN simulations. This study shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.« less

  12. Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

    SciTech Connect

    MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.; Scott, H. A.; Biener, M. M.; Fein, J. R.; Fournier, K. B.; Gamboa, E. J.; Kemp, G. E.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J. -E.; Wan, W. C.; Drake, R. P.

    2016-09-22

    We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer was used to obtain spatially-resolved measurements of Ti K-$\\alpha$ emission. Density profiles were measured from K-$\\alpha$ intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-$\\alpha$ spectra to spectra from CRETIN simulations. This study shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.

  13. Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

    SciTech Connect

    MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.; Scott, H. A.; Biener, M. M.; Fein, J. R.; Fournier, K. B.; Gamboa, E. J.; Kemp, G. E.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J. -E.; Wan, W. C.; Drake, R. P.

    2016-09-22

    We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer was used to obtain spatially-resolved measurements of Ti K-$\\alpha$ emission. Density profiles were measured from K-$\\alpha$ intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-$\\alpha$ spectra to spectra from CRETIN simulations. This study shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.

  14. Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

    SciTech Connect

    MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.; Scott, H. A.; Biener, M. M.; Fein, J. R.; Fournier, K. B.; Gamboa, E. J.; Kemp, G. E.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J. -E.; Wan, W. C.; Drake, R. P.

    2016-09-28

    We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer obtained spatially resolved measurements of Ti K-α emission. Density profiles were measured from K-α intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-α spectra to spectra from CRETIN simulations. This work shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.

  15. Measurements of acetylene in air extracted from polar ice cores

    NASA Astrophysics Data System (ADS)

    Nicewonger, M. R.; Aydin, M.; Montzka, S. A.; Saltzman, E. S.

    2016-12-01

    Acetylene (ethyne) is a non-methane hydrocarbon emitted during combustion of fossil fuels, biofuels, and biomass. The major atmospheric loss pathway of acetylene is oxidation by hydroxyl radical with a lifetime estimated at roughly two weeks. The mean annual acetylene levels over Greenland and Antarctica are 250 ppt and 20 ppt, respectively. Firn air measurements suggest atmospheric acetylene is preserved unaltered in polar snow and firn. Atmospheric reconstructions based on firn air measurements indicate acetylene levels rose significantly during the twentieth century, peaked near 1980, then declined to modern day levels. This historical trend is similar to that of other fossil fuel-derived non-methane hydrocarbons. In the preindustrial atmosphere, acetylene levels should primarily reflect emissions from biomass burning. In this study, we present the first measurements of acetylene in preindustrial air extracted from polar ice cores. Air from fluid and dry-drilled ice cores from Summit, Greenland and WAIS-Divide Antarctica is extracted using a wet-extraction technique. The ice core air is analyzed using gas chromatography and high-resolution mass spectrometry. Between 1400 to 1800 C.E., acetylene levels over Greenland and Antarctica varied between roughly 70-120 ppt and 10-30 ppt, respectively. The preindustrial Greenland acetylene levels are significantly lower than modern levels, reflecting the importance of northern hemisphere fossil fuel sources today. The preindustrial Antarctic acetylene levels are comparable to modern day levels, indicating similar emissions in the preindustrial atmosphere, likely from biomass burning. The implications of the preindustrial atmospheric acetylene records from both hemispheres will be discussed.

  16. Angular Scattering Reflectance and Polarization Measurements of Candidate Regolith Materials Measured in the Laboratory

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Boryta, Mark D.; Hapke, Bruce W.; Shkuratov, Yuriy; Vandervoort, Kurt; Vides, Christina L.

    2016-10-01

    The reflectance and polarization of light reflected from a solar system object indicates the chemical and textural state of the regolith. Remote sensing data are compared to laboratory angular scattering measurements and surface properties are determined.We use a Goniometric Photopolarimeter (GPP) to make angular reflectance and polarization measurements of particulate materials that simulate planetary regoliths. The GPP employs the Helmholtz Reciprocity Principle ( 2, 1) - the incident light is linearly polarized - the intensity of the reflected component is measured. The light encounters fewer optical surfaces improving signal to noise. The lab data are physically equivalent to the astronomical data.Our reflectance and polarization phase curves of highly reflective, fine grained, media simulate the regolith of Jupiter's satellite Europa. Our lab data exhibit polarization phase curves that are very similar to reports by experienced astronomers (4). Our previous reflectance phase curve data of the same materials agree with the same astronomical observers (5). We find these materials exhibit an increase in circular polarization ratio with decreasing phase angle (3). This suggests coherent backscattering (CB) of photons in the regolith (3). Shkuratov et al.(3) report that the polarization properties of these particulate media are also consistent with the CB enhancement process (5). Our results replicate the astronomical data indicating Europa's regolith is fine-grained, high porous with void space exceeding 90%.1. Hapke, B. W. (2012). ISBN 978-0-521-88349-82. Minnaert, M. (1941).Asrophys. J., 93, 403-410.3. Nelson, R. M. et al. (1998). Icarus, 131, 223-230.4. Rosenbush, V. et al. (2015). ISBN 978-1-107-04390-9, pp 340-359.5. Shkuratov, Yu. et al. (2002) Icarus 159, 396-416.

  17. Electroweak coupling measurements from polarized Bhabha scattering at SLD

    SciTech Connect

    Pitts, K.T.; SLD Collaboration

    1994-09-01

    The cross section for Bhabah scattering (e{sup +}e{sup {minus}} {yields} e{sup +}e{sup {minus}}) with polarized electrons at the center of mass energy of the Z{sup 0} resonance has been measured with the SLD experiment at the SLAC Linear Collider (SLC) during the 1992--1993 runs. The first measurement of the left-right asymmetry in Bhabah scattering (A{sub LR}{sup e+}e{sup {minus}} ({theta})) is presented. From A{sub LR}{sup e+}{sup {minus}} ({Theta}) the effective weak mixing angle is measured to be sin{sup 2}{theta}{sub W}{sup eff} = 0.2245{plus_minus}0.0010. When combined with the measurement of A{sub LR}, the effective electron couplings are measured to be v{sub e} = {minus}0.0414{plus_minus}0.0020 and a{sub e} = {minus}0.4977{plus_minus}0.0045.

  18. Circularly polarized optical heterodyne interferometer for optical activity measurement of a quartz crystal.

    PubMed

    Chou, Chien; Kuo, Wen-Chuan; Han, Chien-Yuan

    2003-09-01

    Phase retardation between two orthogonal circularly polarized light waves that propagate in an optical active medium is proportional to its optical activity. The measurement of optical activity of a quartz depolarizer in terms of the phase difference of two orthogonal circularly polarized waves is proposed. A circularly polarized optical heterodyne interferometer with a Zeeman laser to measure the optical activity of a quartz crystal is demonstrated experimentally. The accuracy of the measurement is discussed. In addition, the effect of elliptical polarization and nonorthogonality of linearly polarized light waves of a Zeeman laser on the optical activity measurement is analyzed.

  19. Time and Space Resolved Heat Transfer Measurements Under Nucleate Bubbles with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho

    2003-01-01

    Investigations into single bubble pool boiling phenomena are often complicated by the difficulties in obtaining time and space resolved information in the bubble region. This usually occurs because the heaters and diagnostics used to measure heat transfer data are often on the order of, or larger than, the bubble characteristic length or region of influence. This has contributed to the development of many different and sometimes contradictory models of pool boiling phenomena and dominant heat transfer mechanisms. Recent investigations by Yaddanapyddi and Kim and Demiray and Kim have obtained time and space resolved heat transfer information at the bubble/heater interface under constant temperature conditions using a novel micro-heater array (10x10 array, each heater 100 microns on a side) that is semi-transparent and doubles as a measurement sensor. By using active feedback to maintain a state of constant temperature at the heater surface, they showed that the area of influence of bubbles generated in FC-72 was much smaller than predicted by standard models and that micro-conduction/micro-convection due to re-wetting dominated heat transfer effects. This study seeks to expand on the previous work by making time and space resolved measurements under bubbles nucleating on a micro-heater array operated under constant heat flux conditions. In the planned investigation, wall temperature measurements made under a single bubble nucleation site will be synchronized with high-speed video to allow analysis of the bubble energy removal from the wall.

  20. Time-Resolved Optical Measurements of Fuel-Air Mixedness in Windowless High Speed Research Combustors

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet

    1998-01-01

    Fuel distribution measurements in gas turbine combustors are needed from both pollution and fuel-efficiency standpoints. In addition to providing valuable data for performance testing and engine development, measurements of fuel distributions uniquely complement predictive numerical simulations. Although equally important as spatial distribution, the temporal distribution of the fuel is an often overlooked aspect of combustor design and development. This is due partly to the difficulties in applying time-resolved diagnostic techniques to the high-pressure, high-temperature environments inside gas turbine engines. Time-resolved measurements of the fuel-to-air ratio (F/A) can give researchers critical insights into combustor dynamics and acoustics. Beginning in early 1998, a windowless technique that uses fiber-optic, line-of-sight, infrared laser light absorption to measure the time-resolved fluctuations of the F/A (refs. 1 and 2) will be used within the premixer section of a lean-premixed, prevaporized (LPP) combustor in NASA Lewis Research Center's CE-5 facility. The fiber-optic F/A sensor will permit optical access while eliminating the need for film-cooled windows, which perturb the flow. More importantly, the real-time data from the fiber-optic F/A sensor will provide unique information for the active feedback control of combustor dynamics. This will be a prototype for an airborne sensor control system.

  1. High-accuracy time- and space-resolved Stark shift measurements

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1996-07-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.

  2. High-accuracy absolute distance measurement with a mode-resolved optical frequency comb

    NASA Astrophysics Data System (ADS)

    Voigt, Dirk; van den Berg, Steven A.; Lešundák, Adam; van Eldik, Sjoerd; Bhattacharya, Nandini

    2016-04-01

    Optical interferometry enables highly accurate non-contact displacement measurement. The optical phase ambiguity needs to be resolved for absolute distance ranging. In controlled laboratory conditions and for short distances it is possible to track a non-interrupted displacement from a reference position to a remote target. With large distances covered in field applications this may not be feasible, e.g. in structure monitoring, large scale industrial manufacturing or aerospace navigation and attitude control. We use an optical frequency comb source to explore absolute distance measurement by means of a combined spectral and multi-wavelength homodyne interferometry. This relaxes the absolute distance ambiguity to a few tens of centimeters, covered by simpler electronic distance meters, while maintaining highly accurate optical phase measuring capability. A virtually imaged phased array spectrometer records a spatially dispersed interferogram in a single exposure and allows for resolving the modes of our near infrared comb source with 1 GHz mode separation. This enables measurements with direct traceability of the atomic clock referenced comb source. We observed agreement within 500 nm in comparison with a commercial displacement interferometer for target distances up to 50 m. Furthermore, we report on current work toward applicability in less controlled conditions. A filter cavity decimates the comb source to an increased mode separation larger than 20 GHz. A simple grating spectrometer then allows to record mode-resolved interferograms.

  3. High-accuracy time- and space-resolved Stark shift measurements (invited)

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1997-01-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. We use simultaneous two-dimensional space- and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion, and sensitivity. A semiautomated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {plus_minus}2{percent}{endash}4{percent}. Detailed tests of the procedure confirm that the uncertainty in the wavelength-shift error bars is less than {plus_minus}20{percent}. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain three-dimensional space- and time-resolved measurements of the electric and magnetic fields is in progress. {copyright} {ital 1997 American Institute of Physics.}

  4. Polarization Lidar for High Precision Water Depth Measurements of Glacial Melt Water

    NASA Astrophysics Data System (ADS)

    Barton-Grimley, R. A.; Thayer, J. P.; Koenig, L.; Moussavi, M. S.; Gisler, A.; Crowley, G.

    2016-12-01

    In the past decade, warming temperatures over the GrIS have significantly increased the surface melt flowing through the supraglacial hydrologic system - melt ponds, lakes, and rivers - all playing a crucial role in the mass loss of land ice. The smaller melt ponds, rivers and streams on the ice sheets, which evacuate more water than is contained in the larger lakes [Smith et al., 2015], are not sufficiently measured to quantify melt. Scientific requirements established by the cryospheric community call for hydrographic lidar measurements with water depth accuracy better than ±10 cm over meter-scale depths during the melt season. Lakes observed in Southwest, Greenland were on average 2-3 meters deep with maxima near 8 m. Stream depths ranged from 0.6 to 3.4 m with a mean depth of 2.0 m [Moussavi et al., 2016, Pope et al., 2016 and Smith et al., 2015]. In response, a 532nm topographic/hydrographic lidar demonstrator implementing a novel measurement scheme has been developed. The lab demonstrator isolates water surface and ice substrate returns using polarization scattering attributes, and fast timing, to range resolve the two surfaces at centimeter precision. Results of the lidar demonstrator on polarization properties of surface water roughness and varied ice substrates expected during measurement of supraglacial streams, rivers, and shallow melt ponds will be presented. Demonstrating the measurement techniques in a number of controlled scenarios, necessary for understanding the subsequent instrument response, provides a baseline for future measurements in flow regimes that include stream cross-sectional area and discharge estimates. Supporting analysis indicates benefits in system scalability, applicability, and adaptability using this lidar technique, and offers the means to accurately quantify the predominantly shallow, melt ponds, sinuous rivers, and streams that are not currently identifiable from satellite imagery.

  5. Probing the radio emission from air showers with polarization measurements

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giammarchi, M.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; PeÂķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcǎu, O.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Pierre Auger Collaboration

    2014-03-01

    The emission of radio waves from air showers has been attributed to the so-called geomagnetic emission process. At frequencies around 50 MHz this process leads to coherent radiation which can be observed with rather simple setups. The direction of the electric field induced by this emission process depends only on the local magnetic field vector and on the incoming direction of the air shower. We report on measurements of the electric field vector where, in addition to this geomagnetic component, another component has been observed that cannot be described by the geomagnetic emission process. The data provide strong evidence that the other electric field component is polarized radially with respect to the shower axis, in agreement with predictions made by Askaryan who described radio emission from particle showers due to a negative charge excess in the front of the shower. Our results are compared to calculations which include the radiation mechanism induced by this charge-excess process.

  6. Global polarization measurement in Au+Au collisions

    SciTech Connect

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev,V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2007-08-02

    The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.

  7. Characterization of Polar Mesospheric Clouds Using Infrared Measurements From HALOE

    NASA Technical Reports Server (NTRS)

    Hervig, Mark E.

    2002-01-01

    Measurements from the Halogen Occultation Experiment (HALOE) revealed the infrared signature of polar mesospheric clouds (PMCs), for the first time, HALOE PMC observations at eight wavelengths (2.45 - 10 microns) show remarkable agreement with model PMC spectra based on ice particle extinction, and thus provide the first confirmation that water ice is the primary component of PMCs. Because PMCs respond to changes in temperature and water vapor, they are considered an indicator of global climate change. We propose to further the understanding of PMCs using a decade of infrared measurements form HALOE. This effort will characterize PMC spectral properties, extinction profiles, and size distributions. Using this information, HALOE measurements will be used to make simultaneous retrievals of H2O, O3, and temperature, in the presence of PMCs. The simultaneous retrievals of particle properties, H2O, O3, and temperature will be used with HALOE NO data to provide a significant step forward in the knowledge of PMC characteristics and formation conditions. We will challenge fundamental theories of PMC formation, and investigate changes in PMC properties and related conditions over the length of the HALOE measurement record. HALOE has been operating without flaw since it was launched on October 11, 1991. Consequently, ten southern and ten northern PMC seasons have been observed thus far, providing a wealth of data for the study of PMCs and related parameters.

  8. Characterization of Polar Mesospheric Clouds Using Infrared Measurements from HALOE

    NASA Technical Reports Server (NTRS)

    Hervig, Mark E.

    2002-01-01

    Measurements from the Halogen Occultation Experiment (HALOE) revealed the infrared signature of polar mesospheric clouds (PMCs), for the first time, HALOE PMC observations at eight wavelengths (2.45 - 10 microns) show remarkable agreement with model PMC spectra based on ice particle extinction, and thus provide the first confirmation that water ice is the primary component of PMCs. Because PMCs respond to changes in temperature and water vapor, they are considered an indicator of global climate change. We propose to further the understanding of PMCs using a decade of infrared measurements form HALOE. This effort will characterize PMC spectral properties, extinction profiles, and size distributions. Using this information, HALOE measurements will be used to make simultaneous retrievals of H2O3, and temperature, in the presence of PMCs. The simultaneous retrievals of particle properties, H2O3, and temperature will be used with HALOE NO data to provide a significant step forward in the knowledge of PMC characteristics and formation conditions. We will challenge fundamental theories of PMC formation, and investigate changes in PMC properties and related conditions over the length of the HALOE measurement record. HALOE has been operating without flaw since it was launched on October 11, 1991. Consequently, ten southern and ten northern PMC seasons have been observed thus far, providing a wealth of data for the study of PMC and related parameters.

  9. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement.

    PubMed

    van den Berg, Steven A; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-09-30

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10(-8) for a distance of 50 m.

  10. The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

    NASA Astrophysics Data System (ADS)

    Walsh, D. A.; Snedden, E. W.; Jamison, S. P.

    2015-05-01

    The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.

  11. The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

    SciTech Connect

    Walsh, D. A. Snedden, E. W.; Jamison, S. P.

    2015-05-04

    The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.

  12. Time-resolved measurements of the laser burn-through of thin foils

    SciTech Connect

    Murdoch, J.W.; Kilkenny, J.D.; Gray, D.R.; Toner, W.T.

    1981-11-01

    New time-and-space-resolved measurements of the burn-through of 0.05--0.34 ..mu..m thick plastic foils irradiated with 100 psec, 1.06 ..mu..m laser pulses at approximately 10/sup 16/ Wcm/sup -1/ are presented. Comparison of the time history of the transparency of the foils with analytic and computational models suggests that the targets do not transmit until the density is well below the critical density. Comparison of the space-resolved burn-through measurements with an analytic model suggests that lateral thermal conduction is negligible. It is proposed that ion turbulence may be responsible for the high absorption and low thermal conductivity.

  13. An electron energy loss spectrometer based streak camera for time resolved TEM measurements.

    PubMed

    Ali, Hasan; Eriksson, Johan; Li, Hu; Jafri, S Hassan M; Kumar, M S Sharath; Ögren, Jim; Ziemann, Volker; Leifer, Klaus

    2017-05-01

    We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100ns and 10μs. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement

    PubMed Central

    van den Berg, Steven. A.; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-01-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10−8 for a distance of 50 m. PMID:26419282

  15. Calibrating 100 Years of Polar Faculae Measurements: Implications for the Evolution of the Heliospheric Magnetic Field

    NASA Astrophysics Data System (ADS)

    Muñoz-Jaramillo, Andrés; Sheeley, Neil R.; Zhang, Jie; DeLuca, Edward E.

    2012-07-01

    Although the Sun's polar magnetic fields are thought to provide important clues for understanding the 11 year sunspot cycle, including the observed variations of its amplitude and period, the current database of high-quality polar field measurements spans relatively few sunspot cycles. In this paper, we address this deficiency by consolidating Mount Wilson Observatory polar faculae data from four data reduction campaigns, validating it through a comparison with facular data counted automatically from Michelson Doppler Imager (MDI) intensitygrams, and calibrating it against polar field measurements taken by the Wilcox Solar Observatory and average polar field and total polar flux calculated using MDI line-of-sight magnetograms. Our results show that the consolidated polar facular measurements are in excellent agreement with both polar field and polar flux estimates, making them an ideal proxy to study the evolution of the polar magnetic field. Additionally, we combine this database with sunspot area measurements to study the role of the polar magnetic flux in the evolution of the heliospheric magnetic field (HMF). We find that there is a strong correlation between HMF and polar flux at solar minimum and that, taken together, polar flux and sunspot area are better at explaining the evolution of the HMF during the last century than sunspot area alone.

  16. CALIBRATING 100 YEARS OF POLAR FACULAE MEASUREMENTS: IMPLICATIONS FOR THE EVOLUTION OF THE HELIOSPHERIC MAGNETIC FIELD

    SciTech Connect

    Munoz-Jaramillo, Andres; DeLuca, Edward E.; Sheeley, Neil R.; Zhang, Jie E-mail: edeluca@cfa.harvard.edu E-mail: jzhang7@gmu.edu

    2012-07-10

    Although the Sun's polar magnetic fields are thought to provide important clues for understanding the 11 year sunspot cycle, including the observed variations of its amplitude and period, the current database of high-quality polar field measurements spans relatively few sunspot cycles. In this paper, we address this deficiency by consolidating Mount Wilson Observatory polar faculae data from four data reduction campaigns, validating it through a comparison with facular data counted automatically from Michelson Doppler Imager (MDI) intensitygrams, and calibrating it against polar field measurements taken by the Wilcox Solar Observatory and average polar field and total polar flux calculated using MDI line-of-sight magnetograms. Our results show that the consolidated polar facular measurements are in excellent agreement with both polar field and polar flux estimates, making them an ideal proxy to study the evolution of the polar magnetic field. Additionally, we combine this database with sunspot area measurements to study the role of the polar magnetic flux in the evolution of the heliospheric magnetic field (HMF). We find that there is a strong correlation between HMF and polar flux at solar minimum and that, taken together, polar flux and sunspot area are better at explaining the evolution of the HMF during the last century than sunspot area alone.

  17. Time-resolved measurements of Cooper-pair radiative recombination in InAs quantum dots

    SciTech Connect

    Mou, S. S.; Nakajima, H.; Kumano, H.; Suemune, I.; Irie, H.; Asano, Y.; Akahane, K.; Sasaki, M.; Murayama, A.

    2015-08-21

    We studied InAs quantum dots (QDs) where electron Cooper pairs penetrate from an adjacent niobium (Nb) superconductor with the proximity effect. With time-resolved luminescence measurements at the wavelength around 1550 nm, we observed luminescence enhancement and reduction of luminescence decay time constants at temperature below the superconducting critical temperature (T{sub C}) of Nb. On the basis of these measurements, we propose a method to determine the contribution of Cooper-pair recombination in InAs QDs. We show that the luminescence enhancement measured below T{sub C} is well explained with our theory including Cooper-pair recombination.

  18. Study of femtosecond laser spectrally resolved interferometry distance measurement based on excess fraction method

    NASA Astrophysics Data System (ADS)

    Ji, Rongyi; Hu, Kun; Li, Yao; Gao, Shuyuan; Zhou, Weihu

    2017-02-01

    Spectrally resolved interferometry (SRI) technology is a high precision laser interferometry technology, whose short non-ambiguity range (NAR) increases the precision requirement of pre-measurement in absolute distance measurement. In order to improve NAR of femtosecond laser SRI, the factors affecting NAR are studied in measurement system, and synthetic NAR method is presented based on excess fraction method to solve this question. A theoretical analysis is implemented and two Fabry-Perot Etalons with different free spectral range are selected to carry out digital simulation experiments. The experiment shows that NAR can be improved using synthetic NAR method and the precision is the same with that of fundamental femtosecond laser SRI.

  19. Dichroic spectrally-resolved interferometry to overcome the measuring range limit

    NASA Astrophysics Data System (ADS)

    Joo, Ki-Nam

    2015-09-01

    In this investigation, a simple method to eliminate the dead zone without the minimum measurable distance and extend the measurable range of spectrally resolved interferometry (SRI) twice based on the bandwidth separation by a dichroic beam splitter (DBS) is proposed. The main advantage of this dichroic SRI is that it can be simply implemented with a dichroic beam splitter and another reference mirror from the typical SRI. Feasibility experiments were performed to verify the principle of the dichroic SRI and the result confirmed the effectiveness of this method as the extended measuring range. Some practical error sources are considered and the alternative solutions are also discussed.

  20. Exciton diffusion lengths of organic semiconductor thin films measured by spectrally resolved photoluminescence quenching

    NASA Astrophysics Data System (ADS)

    Lunt, Richard R.; Giebink, Noel C.; Belak, Anna A.; Benziger, Jay B.; Forrest, Stephen R.

    2009-03-01

    We demonstrate spectrally resolved photoluminescence quenching as a means to determine the exciton diffusion length of several archetype organic semiconductors used in thin film devices. We show that aggregation and crystal orientation influence the anisotropy of the diffusion length for vacuum-deposited polycrystalline films. The measurement of the singlet diffusion lengths is found to be in agreement with diffusion by Förster transfer, whereas triplet diffusion occurs primarily via Dexter transfer.

  1. Frequency-resolved optical-gating measurements of ultrashort pulses using surface third-harmonic generation

    SciTech Connect

    Tsang, T.; Krumbuegel, M.A.; DeLong, K.W.; Fittinghoff, D.N.; Trebino, R.

    1996-09-01

    We demonstrate what is to our knowledge the first frequency-resolved optical gating (FROG) technique to measure ultrashort pulses from an unamplified Ti:sapphire laser oscillator without direction-of-time ambiguity. This technique utilizes surface third-harmonic generation as the nonlinear-optical effect and, surprisingly, is the most sensitive third-order FROG geometry yet. {copyright} {ital 1996 Optical Society of America.}

  2. Diagnostics of the efficiency of surface plasmon-polariton excitation by quantum dots via polarization measurements of the output radiation

    SciTech Connect

    Kukushkin, V. A.; Baidus, N. V.; Zdoroveishchev, A. V.

    2015-06-15

    It is demonstrated that the efficiency of surface plasmon-polariton excitation at a metal-semiconductor interface by active quantum dots can be determined from measurements of the polarization characteristics of the output radiation. Experimentally, the proposed diagnostic method is based on finding the ratio of the intensities of the output radiation with polarizations orthogonal and parallel to the nanoheterostructure plane for two different distances between the quantum-dot layer and the metal-semiconductor interface. These data are then used to obtain the unknown parameters in the proposed mathematical model which makes it possible to calculate the rate of surface plasmon-polariton excitation by active quantum dots. As a result, this rate can be determined without complicated expensive equipment for fast time-resolved measurements.

  3. Measurement of p{sub zz} of the laser-driven polarized deuterium target

    SciTech Connect

    Jones, C.E.; Coulter, K.P.; Holt, R.J.; Poelker, M.; Potterveld, D.P.; Kowalczyk, R.S.; Buchholz, M.; Neal, J.; van den Brand, J.F.J.

    1993-08-01

    The question of whether nuclei are polarized as a result of H-H (D-D) spin-exchange collisions within the relatively dense gas of a laser-driven source of polarized hydrogen (deuterium) can be addressed directly by measuring the nuclear polarization of atoms from the source. The feasibility of using a polarimeter based on the D + T {yields} n + {sup 4}He reaction to measure the tensor polarization of deuterium in an internal target fed by the laser-driven source has been tested. The device and the measurements necessary to test the spin-exchange polarization theory are described.

  4. SAM 2 measurements of the polar stratospheric aerosol, volume 2

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Brandl, D.

    1986-01-01

    The Stratospheric Aerosol Measurement (SAM) 2 sensor aboard Nimbus 7 is providing extinction measurements of Antarctic and Arctic stratospheric aerosols with a vertical resolution of 1 km. Representative examples and weekly averages including corresponding temperature profiles provided by NOAA for the time and place of each SAM 2 measurement (Oct. 1981 - Apr. 1982) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted, and aerosol optical depths are calculated for each week. Typical values of aerosol extinction at 1.0 micron in the main lower stratospheric aerosol layer for this time period are 2 to 4 times 10 to the -4 power/km. for the Antarctic region and 0.5 to 1 times 10 to the -3 power/km. for the Arctic region. Stratospheric optical depths are about 0.001 to 0.004 for the Antarctic region and 0.003 to 0.004 at the beginning to about 0.006 at the end of the time period for the Arctic region. Polar stratospheric clouds (PSC's) were observed during the Arctic winter, as expected. This report provides, in a ready-to-use format, a representative sample of the seventh semester of data to be used in atmospheric and climatic studies.

  5. Polarization-Sensitive Measurements Of Magnetic Fields In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, Showera; Wallace, Matthew S.; Neill, Paul; Presura, Radu

    2016-10-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult in this regime because the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Using an idea proposed by Tessarin et al. (2011), we have measured the field in magnetized laser plasmas and in the current-driven exploding wire plasmas. Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator, and for wire array plasmas driven by the 1 MA configuration of the Zebra generator. We explore the response of the Al III 4s 2S1/2- 4p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma in two orthogonal polarizations. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength was measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES Grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  6. Spin-resolved magnetic studies of BCT Fe/Mn/BCT Fe(1 0 0)/FCC Pd(1 0 0) films using scanning ion microscopy with polarization analysis

    NASA Astrophysics Data System (ADS)

    Li, Jian; Rau, Carl

    2005-02-01

    We report on spin-resolved magnetic studies of wedge-shaped, epitaxial BCT Fe/Mn/BCT Fe(1 0 0)/FCC Pd(1 0 0) films by using scanning ion microscopy with polarization analysis (SIMPA) and magneto-optical Kerr effect (MOKE). SIMPA is used to perform in situ spin-resolved magnetic domain imaging, and MOKE is utilized to study magnetic hysteresis loops. Fe/Mn/Fe films are deposited on well-prepared, atomically flat Pd(1 0 0) substrates. Medium energy electron diffraction (MEED) and Auger electron spectroscopy (AES) are used for detailed studies of growth modes, surface and interface structures. Various non-uniform, curling domain and domain wall structures, which are strongly affected by canted magnetic couplings, are found.

  7. Development of Two-Photon Pump Polarization Spectroscopy Probe Technique Tpp-Psp for Measurements of Atomic Hydrogen .

    NASA Astrophysics Data System (ADS)

    Satija, Aman; Lucht, Robert P.

    2015-06-01

    Atomic hydrogen (H) is a key radical in combustion and plasmas. Accurate knowledge of its concentration can be used to better understand transient phenomenon such as ignition and extinction in combustion environments. Laser induced polarization spectroscopy is a spatially resolved absorption technique which we have adapted for quantitative measurements of H atom. This adaptation is called two-photon pump, polarization spectroscopy probe technique (TPP-PSP) and it has been implemented using two different laser excitation schemes. The first scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-3P levels using a circularly polarized 656-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 656 nm. As a result, the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. The laser beams were created by optical parametric generation followed by multiple pulse dye amplification stages. This resulted in narrow linewidth beams which could be scanned in frequency domain and varied in energy. This allowed us to systematically investigate saturation and Stark effect in 2S-3P transitions with the goal of developing a quantitative H atom measurement technique. The second scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-4P transitions using a circularly polarized 486-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 486 nm. As a result the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. A dye laser was pumped by third harmonic of a Nd:YAG laser to create a laser beam

  8. Velocity and Temperature Measurement in Supersonic Free Jets Using Spectrally Resolved Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    Panda, J.; Seasholtz, R. G.

    2004-01-01

    The flow fields of unheated, supersonic free jets from convergent and convergent-divergent nozzles operating at M = 0.99, 1.4, and 1.6 were measured using spectrally resolved Rayleigh scattering technique. The axial component of velocity and temperature data as well as density data obtained from a previous experiment are presented in a systematic way with the goal of producing a database useful for validating computational fluid dynamics codes. The Rayleigh scattering process from air molecules provides a fundamental means of measuring flow properties in a non-intrusive, particle free manner. In the spectrally resolved application, laser light scattered by the air molecules is collected and analyzed using a Fabry-Perot interferometer (FPI). The difference between the incident laser frequency and the peak of the Rayleigh spectrum provides a measure of gas velocity. The temperature is measured from the spectral broadening caused by the random thermal motion and density is measured from the total light intensity. The present point measurement technique uses a CW laser, a scanning FPI and photon counting electronics. The 1 mm long probe volume is moved from point to point to survey the flow fields. Additional arrangements were made to remove particles from the main as well as the entrained flow and to isolate FPI from the high sound and vibration levels produced by the supersonic jets. In general, velocity is measured within +/- 10 m/s accuracy and temperature within +/- 10 K accuracy.

  9. Method for using polarization gating to measure a scattering sample

    DOEpatents

    Baba, Justin S.

    2015-08-04

    Described herein are systems, devices, and methods facilitating optical characterization of scattering samples. A polarized optical beam can be directed to pass through a sample to be tested. The optical beam exiting the sample can then be analyzed to determine its degree of polarization, from which other properties of the sample can be determined. In some cases, an apparatus can include a source of an optical beam, an input polarizer, a sample, an output polarizer, and a photodetector. In some cases, a signal from a photodetector can be processed through attenuation, variable offset, and variable gain.

  10. Quantitative C2H2 measurements in sooty flames using mid-infrared polarization spectroscopy

    NASA Astrophysics Data System (ADS)

    Sun, Z. W.; Li, Z. S.; Li, B.; Alwahabi, Z. T.; Aldén, M.

    2010-10-01

    Quantitative measurements of acetylene (C2H2) molecules as a combustion intermediate species in a series of rich premixed C2H4/air flames were non-intrusively performed, spatially resolved, using mid-infrared polarization spectroscopy (IRPS), by probing its fundamental ro-vibrational transitions. The flat sooty C2H4/air premixed flames with different equivalence ratios varying from 1.25 to 2.50 were produced on a 6 cm diameter porous-plug McKenna type burner at atmospheric pressure, and all measurements were performed at a height of 8.5 mm above the burner surface. IRPS excitation scans in different flame conditions were performed and rotational line-resolved spectra were recorded. Spectral features of acetylene molecules were readily recognized in the spectral ranges selected, with special attention to avoid the spectral interference from the large amount of coexisting hot water and other hydrocarbon molecules. On-line calibration of the optical system was performed in a laminar C2H2/N2 gas flow at ambient conditions. Using the flame temperatures measured by coherent anti-Stokes Raman spectroscopy in a previous work, C2H2 mole fractions in different flames were evaluated with collision effects and spectral overlap between molecular line and laser source being analyzed and taken into account. C2H2 IRPS signals in two different buffering gases, N2 and CO2, had been investigated in a tube furnace in order to estimate the spectral overlap coefficients and collision effects at different temperatures. The soot-volume fractions (SVF) in the studied flames were measured using a He-Ne laser-extinction method, and no obvious degrading of the IRPS technique due to the sooty environment has been observed in the flame with SVF up to ˜2×10-7. With the increase of flame equivalence ratios not only the SVF but also the C2H2 mole fractions increased.

  11. When combined X-ray and polarized neutron diffraction data challenge high-level calculations: spin-resolved electron density of an organic radical.

    PubMed

    Voufack, Ariste Bolivard; Claiser, Nicolas; Lecomte, Claude; Pillet, Sébastien; Pontillon, Yves; Gillon, Béatrice; Yan, Zeyin; Gillet, Jean Michel; Marazzi, Marco; Genoni, Alessandro; Souhassou, Mohamed

    2017-08-01

    Joint refinement of X-ray and polarized neutron diffraction data has been carried out in order to determine charge and spin density distributions simultaneously in the nitronyl nitroxide (NN) free radical Nit(SMe)Ph. For comparison purposes, density functional theory (DFT) and complete active-space self-consistent field (CASSCF) theoretical calculations were also performed. Experimentally derived charge and spin densities show significant differences between the two NO groups of the NN function that are not observed from DFT theoretical calculations. On the contrary, CASSCF calculations exhibit the same fine details as observed in spin-resolved joint refinement and a clear asymmetry between the two NO groups.

  12. ICESat's Laser Measurements of Polar Ice, Atmosphere, Ocean, and Land

    NASA Technical Reports Server (NTRS)

    Zwally, H. J.; Schutz, B.; Abdalati, W.; Abshire, J.; Bentley, C.; Brenner, A.; Bufton, J.; Dezio, J.; Hancock, D.; Harding, D.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The Ice, Cloud and Land Elevation Satellite (ICESat) mission will measure changes in elevation of the Greenland and Antarctic ice sheets as part of NASA's Earth Observing System (EOS) of satellites. Time-series of elevation changes will enable determination of the present-day mass balance of the ice sheets, study of associations between observed ice changes and polar climate, and estimation of the present and future contributions of the ice sheets to global sea level rise. Other scientific objectives of ICESat include: global measurements of cloud heights and the vertical structure of clouds and aerosols; precise measurements of land topography and vegetation canopy heights; and measurements of sea ice roughness, sea ice thickness, ocean surface elevations, and surface reflectivity. The Geoscience Laser Altimeter System (GLAS) on ICESat has a 1064 nm laser channel for surface altimetry and dense cloud heights and a 532 nm lidar channel for the vertical distribution of clouds and aerosols. The accuracy of surface ranging is 10 cm, averaged over 60 m diameter laser footprints spaced at 172 m along-track. The orbital altitude will be around 600 km at an inclination of 94 deg with a 183-day repeat pattern. The onboard GPS receiver will enable radial orbit determinations to better than 5 cm, and star-trackers will enable footprints to be located to 6 m horizontally. The spacecraft attitude will be controlled to point the laser beam to within +/- 35 m of reference surface tracks at high latitudes. ICESat is designed to operate for 3 to 5 years and should be followed by successive missions to measure ice changes for at least 15 years.

  13. A split beam method for measuring time-resolved circular dichroism

    NASA Astrophysics Data System (ADS)

    Wenzel, Stephan; Buss, Volker

    1997-04-01

    An improvement to the Lewis-Kliger method for measuring transient circular dichroism on the nanosecond time scale is described. The method uses a single-probe beam that is split into two different beams of plane polarized light entering the sample and a retarder from opposite directions in different succession. Rochon polarizers are used as high-quality polarizing beam splitters to select the slow axis component of the emerging elliptical polarized light beams. The intensities of the light beams are determined by an imaging spectrograph coupled to an intensified charge coupled device detector. The split beam method reduces the need for very precise calibration of the central strain plate acting as a retarder and controlling the ellipticity of the probe light. The necessary calculations are simple and can be shown to be equivalent to the formulas derived by Lewis and Kliger. The static CD spectrum of vitamin B12 is presented and compared to a spectrum obtained with a commercial instrument and standard technique. The time resolution of the instrument is demonstrated by observation of photobleaching of carbon monoxy myoglobin from horse heart muscle.

  14. Measuring X-Ray Polarization in the Presence of Systematic Effects: Known Background

    NASA Technical Reports Server (NTRS)

    Elsner, Ronald F.; O'Dell, Stephen L.; Weisskopf, Martin C.

    2012-01-01

    The prospects for accomplishing x-ray polarization measurements of astronomical sources have grown in recent years, after a hiatus of more than 37 years. Unfortunately, accompanying this long hiatus has been some confusion over the statistical uncertainties associated with x-ray polarization measurements of these sources. We have initiated a program to perform the detailed calculations that will offer insights into the uncertainties associated with x-ray polarization measurements. Here we describe a mathematical formalism for determining the 1- and 2-parameter errors in the magnitude and position angle of x-ray (linear) polarization in the presence of a (polarized or unpolarized) background. We further review relevant statistics including clearly distinguishing between the Minimum Detectable Polarization (MDP) and the accuracy of a polarization measurement.

  15. Measuring x-ray polarization in the presence of systematic effects: known background

    NASA Astrophysics Data System (ADS)

    Elsner, Ronald F.; O'Dell, Stephen L.; Weisskopf, Martin C.

    2012-09-01

    The prospects for accomplishing x-ray polarization measurements of astronomical sources have grown in recent years, after a hiatus of more than 37 years. Unfortunately, accompanying this long hiatus has been some confusion over the statistical uncertainties associated with x-ray polarization measurements of these sources. We have initiated a program to perform the detailed calculations that will offer insights into the uncertainties associated with x-ray polarization measurements. Here we describe a mathematical formalism for determining the 1- and 2-parameter errors in the magnitude and position angle of x-ray (linear) polarization in the presence of a (polarized or unpolarized) background. We further review relevant statistics—including clearly distinguishing between the Minimum Detectable Polarization (MDP) and the accuracy of a polarization measurement.

  16. Investigation on Surface Polarization of Al2O3-capped GaN/AlGaN/GaN Heterostructure by Angle-Resolved X-ray Photoelectron Spectroscopy.

    PubMed

    Duan, Tian Li; Pan, Ji Sheng; Wang, Ning; Cheng, Kai; Yu, Hong Yu

    2017-08-17

    The surface polarization of Ga-face gallium nitride (GaN) (2 nm)/AlGaN (22 nm)/GaN channel (150 nm)/buffer/Si with Al2O3 capping layer is investigated by angle-resolved X-ray photoelectron spectroscopy (ARXPS). It is found that the energy band varies from upward bending to downward bending in the interface region, which is believed to be corresponding to the polarization variation. An interfacial layer is formed between top GaN and Al2O3 due to the occurrence of Ga-N bond break and Ga-O bond forming during Al2O3 deposition via the atomic layer deposition (ALD). This interfacial layer is believed to eliminate the GaN polarization, thus reducing the polarization-induced negative charges. Furthermore, this interfacial layer plays a key role for the introduction of the positive charges which lead the energy band downward. Finally, a N2 annealing at 400 °C is observed to enhance the interfacial layer growth thus increasing the density of positive charges.

  17. Polarization-resolved terahertz third-harmonic generation in a single-crystal superconductor NbN: Dominance of the Higgs mode beyond the BCS approximation

    NASA Astrophysics Data System (ADS)

    Matsunaga, Ryusuke; Tsuji, Naoto; Makise, Kazumasa; Terai, Hirotaka; Aoki, Hideo; Shimano, Ryo

    2017-07-01

    Recent advances in time-domain terahertz (THz) spectroscopy have unveiled that resonantly enhanced strong THz third-harmonic generation (THG) mediated by the collective Higgs amplitude mode occurs in s -wave superconductors, where charge-density fluctuations (CDFs) have been shown to also contribute to the nonlinear third-order susceptibility. It has been theoretically proposed that the nonlinear responses of Higgs and CDF exhibit essentially different polarization dependences. Here we experimentally discriminate the two contributions by polarization-resolved intense THz transmission spectroscopy for a single-crystal NbN film. The result shows that the resonant THG in the transmitted light always appears in the polarization parallel to that of the incident light with no appreciable polarization-angle dependence relative to the crystal axis. When we compare this with the theoretical calculation here with the BCS approximation and the dynamical mean-field theory for a model of NbN constructed from first principles, the experimental result strongly indicates that the Higgs mode rather than the CDF dominates the THG resonance in NbN. A possible mechanism for this is the retardation effect in the phonon-mediated pairing interaction beyond BCS.

  18. Investigation on Surface Polarization of Al2O3-capped GaN/AlGaN/GaN Heterostructure by Angle-Resolved X-ray Photoelectron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Duan, Tian Li; Pan, Ji Sheng; Wang, Ning; Cheng, Kai; Yu, Hong Yu

    2017-08-01

    The surface polarization of Ga-face gallium nitride (GaN) (2 nm)/AlGaN (22 nm)/GaN channel (150 nm)/buffer/Si with Al2O3 capping layer is investigated by angle-resolved X-ray photoelectron spectroscopy (ARXPS). It is found that the energy band varies from upward bending to downward bending in the interface region, which is believed to be corresponding to the polarization variation. An interfacial layer is formed between top GaN and Al2O3 due to the occurrence of Ga-N bond break and Ga-O bond forming during Al2O3 deposition via the atomic layer deposition (ALD). This interfacial layer is believed to eliminate the GaN polarization, thus reducing the polarization-induced negative charges. Furthermore, this interfacial layer plays a key role for the introduction of the positive charges which lead the energy band downward. Finally, a N2 annealing at 400 °C is observed to enhance the interfacial layer growth thus increasing the density of positive charges.

  19. Resolving three-dimensional surface displacements from InSAR measurements: A review

    NASA Astrophysics Data System (ADS)

    Hu, J.; Li, Z. W.; Ding, X. L.; Zhu, J. J.; Zhang, L.; Sun, Q.

    2014-06-01

    One-dimensional measurement along the Line-Of-Sight (LOS) direction has greatly limited the capability of InSAR technique in the investigation of surface displacements and their dynamics. In recent years, great efforts have been made to resolve complete three-dimensional (3-D) displacements from InSAR measurements. This contribution is intended to provide a systematic review of the progress achieved in this field. Based on an analysis of the InSAR LOS measurements, we first cover two commonly used techniques, i.e., Offset-Tracking and multi-aperture InSAR (MAI), with which the surface displacement in the azimuth direction can be measured together with the LOS displacement. Several methods for mapping 3-D displacements using InSAR measurements are subsequently presented and categorized into three groups: (i) combination of multi-pass LOS and azimuth measurements; (ii) integration of InSAR and GPS data; and (iii) prior information assisted approaches. The strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3-D displacement mapping cases, in hope to provide a useful guidance in choosing a suitable approach accordingly. Finally, suggestions for resolving the challenging issues and outlook of future research are given.

  20. Analysis of visual acuity and motion resolvability as measures for optimal visual perception of the workspace.

    PubMed

    Janabi-Sharifi, Farrokh; Vakanski, Aleksandar

    2011-03-01

    For working tasks with high visual demand, ergonomic design of the working stations requires defining criteria for comparative evaluation and analysis of the visual perceptibility in different regions of the workspace. This paper provides kinematic models of visual acuity and motion resolvability as adopted measures of visual perceptibility of the workspace. The proposed models have been examined through two sets of experiments. The first experiment is designed to compare the models outputs with those from experiments. Time measurements of the participants' response to visual events are employed for calculation of the perceptibility measures. The overall comparison results show similar patterns and moderate statistical errors of the measured and kinematically modeled values of the parameters. In the second experiment, the proposed set of visual perceptibility measures are examined for a simulated industrial task of inserting electronic chips into slots of a working table, resembling a fine assembly line of transponders manufacturing. The results from ANOVA tests for the visual acuity and the motion resolvability justify the postures adopted by the participants using visual perceptibility measures for completing the insertion tasks. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  1. Time and Space Resolved Heat Flux Measurements During Nucleate Boiling with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Yerramilli, Vamsee K.; Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho

    2005-01-01

    The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work was to acquire time and space resolved temperature distributions under nucleating bubbles on a constant heat flux surface using a microheater array with 100x 100 square microns resolution, then numerically determine the wall to liquid heat flux. This data was then correlated with high speed (greater than l000Hz) visual recordings of The bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that microlayer evaporation and contact line heat transfer are not major heat transfer mechanisms for bubble growth. The dominant heat transfer mechanism appears to be transient conduction into the liquid as the liquid rewets the wall during the bubble departure process.

  2. Time-resolved wave profile measurements in copper to Megabar pressures

    SciTech Connect

    Chhabildas, L C; Asay, J R

    1981-01-01

    Many time-resolved techniques have been developed which have greatly aided in the understanding of dynamic material behavior such as the high pressure-dynamic strength of materials. In the paper, time-resolved measurements of copper (at shock-induced high pressures and temperatures) are used to illustrate the capability of using such techniques to investigate high pressure strength. Continuous shock loading and release wave profiles have been made in copper to 93 GPa using velocity interferometric techniques. Fine structure in the release wave profiles from the shocked state indicates an increase in shear strength of copper to 1.5 GPa at 93 GPa from its ambient value of 0.08 GPa.

  3. Design and calibration of hot-electron spectrometer array for angle-resolved measurement

    NASA Astrophysics Data System (ADS)

    Liu, Huiya; An, Honghai; Shen, Jie; Kang, Ning; Zhou, Shenlei; Lei, Anle; Lin, Zunqi

    2017-05-01

    A hot-electron spectrometer array with two-dimensional distribution has been designed with a wide-angle range and high-energy resolution to measure the spatially resolved electron spectra for high-power-laser plasma interaction experiments. It consisted of 19 identical electron spectrometers set in three directions with an interval of 10°. Each electron spectrometer was designed with a uniform magnetic field to detect electrons in the range from 20 to 500 keV. The spectrometers were calibrated using electrons from an accelerator. In an experiment, the spatially resolved electron energy spectra, which approximately had a Maxwell distribution, were obtained from an aluminum foil target irradiated by a 0.53-μm laser pulse.

  4. Number-resolved master equation approach to quantum measurement and quantum transport

    NASA Astrophysics Data System (ADS)

    Li, Xin-Qi

    2016-08-01

    In addition to the well-known Landauer-Büttiker scattering theory and the nonequilibrium Green's function technique for mesoscopic transports, an alternative (and very useful) scheme is quantum master equation approach. In this article, we review the particle-number ( n)-resolved master equation ( n-ME) approach and its systematic applications in quantum measurement and quantum transport problems. The n-ME contains rich dynamical information, allowing efficient study of topics such as shot noise and full counting statistics analysis. Moreover, we also review a newly developed master equation approach (and its n-resolved version) under self-consistent Born approximation. The application potential of this new approach is critically examined via its ability to recover the exact results for noninteracting systems under arbitrary voltage and in presence of strong quantum interference, and the challenging non-equilibrium Kondo effect.

  5. Polarization-Fizeau interferometer enabling phase measurement with reduced uncertainty

    NASA Astrophysics Data System (ADS)

    Fütterer, G.

    2017-06-01

    A Fizeau interferometer is significantly less sensitive to vibrations and air turbulence than other types of interferometers. This is due to the common path of the reference wave front and the object wave front. A common path arrangement offers the opportunity to reduce systematic errors of the measured phase of the surface under test (SUT). That is why Fizeau type interferometers are most commonly used to test e.g. plane surfaces, spheres or aspheres. A reduced uncertainty of the measured phase distribution can be obtained if the reference surface is placed close to the SUT. Multiple beam reflections will produce interference fringes, which are not sinusoidal. Furthermore, the discrete intensity distribution depends on the reflectance of the reference surface and the reflectance of the SUT. Some surfaces to be tested show significant variations of the local reflectance, e.g. lithographic masks with 0.05 <= r(x,y) <= 0.95. Thus, the inherent potential of phase shifting algorithms cannot be used. A modification of the reference surface can be applied. An on-axis polarization beam splitter, which is placed in the plane of the reference surface, separates the two surfaces, which are imaged onto the detector. Thus, true two beam interference can be obtained. The potential of phase shifting algorithms can be used. The interference contrast is high, even if large local variations of r(x,y) are present. In addition, high speed operation is enabled. The embodiment of a modified Fizeau type interferometer will be described.

  6. Subkelvin spin polarized STM: measuring magnetization curves of individual adatoms

    NASA Astrophysics Data System (ADS)

    Wiebe, Jens

    2008-03-01

    Magnetic nanostructures consisting of a few atoms on non-magnetic substrates are explored as model systems for miniaturized data storage devices and for the implementation of novel spin-based computation techniques. Since these nanostructures are well defined and controllable on the atomic scale, they are ideally suited to study the fundamentals of magnetic interactions. We used spin polarized scanning tunneling spectroscopy at subkelvin temperatures to image the magnetization of individual adatoms as a function of an external magnetic field. This allows to directly measure their magnetic interactions at very low energy scale. We will present the design of the 300mK STM [1] and then focus on the results. Interestingly, Co atoms on Pt(111) behave paramagnetic even at very low temperatures, 300 times smaller than the previously reported giant barrier between up and down spin [2]. A peculiar variation in the saturation flux density, which is measured for each atom, is found. This is attributed to their mutual indirect exchange via the substrate electrons. Indeed, we observe an interaction between the adatom and a Co monolayer stripe oscillating with distance between ferromagnetic and antiferromagnetic coupling on the scale of the Fermi wavelength. [1] J. Wiebe et al., Rev. Sci. Instrum. 75, 4871 (2004). [2] P. Gambardella et al., Science 300, 1130 (2003).

  7. Spin-isospin responses in Nuclei via polarization measurements

    NASA Astrophysics Data System (ADS)

    Sakai, Hide

    2001-06-01

    High quality (p, n) data obtained by NTOF+NPOL2 facility at RCNP were presented. From the measurement of 90Zr(p,n) reaction at 295 MeV, the quenching value for the Gamow-Teller transition in terms of the Ikeda's sum rule of Sβ--Sβ+=3(N-Z) is derived as 0.90+/-0.05. By using this quenching value, the Landau-Migdal parameters representing short-range correlation in isospin-spin interactions are deduced as (gNN',gNΔ')=(0.6,0.2). This small gNΔ' value favors the pion condensation. The complete set of the polarization transfer coefficients, DLL', DSS', DNN', DLS' and DSL', for the (p, n) quasi-elastic scattering has been measured at 350 MeV. The spin-longitudinal cross section IDq(~RL) and the spin-transverse cross section IDp(~RT) are deduced. IDq is found to be consistent with the DWIA+RPA calculation with (gNN',gNΔ')=(0.6,0.3). This result supports strongly the existence of the pionic enhancement in nuclei. .

  8. Beyond Single-Wavelength SHG Measurements: Spectrally-Resolved SHG Studies of Tetraphosphonate Ester Coordination Polymers.

    PubMed

    Zaręba, Jan K; Białek, Michał J; Janczak, Jan; Nyk, Marcin; Zoń, Jerzy; Samoć, Marek

    2015-11-16

    Powder second-harmonic generation (SHG) efficiencies are usually measured at single wavelengths. In the present work, we provide a proof of concept of spectrally resolved powder SHG measured for a newly obtained series of three non-centrosymmetric coordination polymers (CPs). CPs are constructed from tetrahedral linker-tetraphenylmethane-based tetraphosphonate octaethyl ester and cobalt(II) ions of mixed, octahedral (Oh), and tetrahedral (Td), geometries and different sets of donors (CoO6 vs CoX3O). Isostructurality of the obtained materials allowed for the determination of anion-dependent tunability of SHG optical spectra and their relationship with solid-state absorption spectra.

  9. Spatially resolving variations in giant magnetoresistance, undetectable with four-point probe measurements, using infrared microspectroscopy

    SciTech Connect

    Kelley, C. S.; Thompson, S. M.; Illman, M. D.; LeFrancois, S.; Dumas, P.

    2012-10-15

    Magnetorefractive infrared (IR) microspectroscopy is demonstrated to resolve spatial variations in giant magnetoresistance (GMR) and, by modelling, provide an insight into the origin of the variations. Spatial variations are shown to be masked in conventional four-point probe electrical or IR spectral measurements. IR microspectroscopy was performed at the SMIS beamline at the SOLEIL synchrotron, modified to enable measurements in magnetic fields. A GMR gradient was induced in a CoFe/Cu multilayer sample by annealing in a temperature gradient. Modelling revealed that variations in GMR at 900 Oe could be attributed to local variations in interlayer coupling locally changing the switching field.

  10. Mathematical Relationships Between Two Sets of Laser Anemometer Measurements for Resolving the Total Velocity Vector

    NASA Technical Reports Server (NTRS)

    Owen, Albert K.

    1993-01-01

    The mathematical relations between the measured velocity fields for the same compressor rotor flow field resolved by two fringe type laser anemometers at different observational locations are developed in this report. The relations allow the two sets of velocity measurements to be combined to produce a total velocity vector field for the compressor rotor. This report presents the derivation of the mathematical relations, beginning with the specification of the coordinate systems and the velocity projections in those coordinate systems. The vector projections are then transformed into a common coordinate system. The transformed vector coordinates are then combined to determine the total velocity vector. A numerical example showing the solution procedure is included.

  11. The 7BM beamline at the APS: a facility for time-resolved fluid dynamics measurements

    PubMed Central

    Kastengren, Alan; Powell, Christopher F.; Arms, Dohn; Dufresne, Eric M.; Gibson, Harold; Wang, Jin

    2012-01-01

    In recent years, X-ray radiography has been used to probe the internal structure of dense sprays with microsecond time resolution and a spatial resolution of 15 µm even in high-pressure environments. Recently, the 7BM beamline at the Advanced Photon Source (APS) has been commissioned to focus on the needs of X-ray spray radiography measurements. The spatial resolution and X-ray intensity at this beamline represent a significant improvement over previous time-resolved X-ray radiography measurements at the APS. PMID:22713903

  12. Measurements of Turbulent Convection Speeds in Multistream Jets Using Time-Resolved PIV

    NASA Technical Reports Server (NTRS)

    Bridges, James; Wernet, Mark P.

    2017-01-01

    Convection speeds of turbulent velocities in jets, including multi-stream jets with and without flight stream, were measured using an innovative application of time-resolved particle image velocimetry. The paper describes the unique instrumentation and data analysis that allows the measurement to be made. Extensive data is shown that relates convection speed, mean velocity, and turbulent velocities for multiple jet cases. These data support the overall observation that the local turbulent convection speed is roughly that of the local mean velocity, biased by the relative intensity of turbulence.

  13. Phase-resolved measurements of ion velocity in a radio-frequency sheath.

    PubMed

    Jacobs, Brett; Gekelman, Walter; Pribyl, Pat; Barnes, Michael

    2010-08-13

    The time-dependent argon-ion velocity distribution function above and within the plasma sheath of an rf-biased substrate has been measured using laser-induced fluorescence in a commercial plasma processing tool. Discharge parameters were such that the 2.2 MHz rf-bias period was on the order of the ion transit time through the sheath (τ{ion}/τ{rf}=0.3). This work embodies the first time-resolved measurement of ion velocity distribution functions within an rf-biased sheath over a large area (30 cm diameter) silicon wafer substrate.

  14. Time resolved temperature measurement of polymer surface irradiated by mid-IR free electron laser

    NASA Astrophysics Data System (ADS)

    Araki, Mitsunori; Chiba, Tomoyuki; Oyama, Takahiro; Imai, Takayuki; Tsukiyama, Koichi

    2017-08-01

    We have developed the time-resolved temperature measurement system by using a radiation thermometer FLIR SC620. Temporal temperature profiles of an acrylic resin surface by the irradiation of infrared free electron laser (FEL) pulse were recorded in an 8 ms resolution to measure an instantaneous temperature rise and decay profile. Under the single-shot condition, a peak temperature defined as the temperature jump from the ambient temperature was found to be proportional to the absorbance. Under the multi-shot condition, the temperature accumulation was found to reach a roughly constant value where the supply and release of the heat is balanced.

  15. A technique for measurement of vector and tensor polarization in solid spin one polarized targets

    SciTech Connect

    Kielhorn, W.F.

    1991-06-01

    Vector and tensor polarizations are explicitly defined and used to characterize the polarization states of spin one polarized targets, and a technique for extracting these polarizations from nuclear magnetic resonance (NMR) data is developed. This technique is independent of assumptions about spin temperature, but assumes the target's crystal structure induces a quadrupole interaction with the spin one particles. Analysis of the NMR signals involves a computer curve fitting algorithm implemented with a fast Fourier transform method which speeds and simplifies curve fitting algorithms used previously. For accurate curve fitting, the NMR electronic circuit must be modeled by the fitting algorithm. Details of a circuit, its model, and data collected from this circuit are given for a solid deuterated ammonia target. 37 refs., 19 figs., 3 tabs.

  16. Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance.

    PubMed

    Barnes, Michael P; Greer, Peter B

    2016-03-01

    In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX linacs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015). PACS number(s): 87.55.Qr.

  17. Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance.

    PubMed

    Barnes, Michael P; Greer, Peter B

    2016-03-08

    In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX lin-acs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015).

  18. On the limitations of geomagnetic measures of interplanetary magnetic polarity

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Rosenberg, R. L.

    1974-01-01

    The maximum attainable accuracy in inferring the interplanetary magnetic polarity from polar cap magnetograms is about 88%. This is achieved in practice, when high-latitude polar cap stations are used during local summer months, and the signature in the ground records is strong. An attempt by Svalgaard (1972) to use this effect to infer an index of interplanetary magnetic polarity back to 1926 has not been so successful. Furthermore, some of the properties of the index have changed with time. Prior to 1963, the inferred polarities are strongly dependent on geomagnetic activity, while after this time they are not. Thus, this index should not be used to separate solar-magnetic from solar-activity effects prior to 1963.

  19. Spectral induced polarization (SIP) measurement of NAPL contaminated soils

    NASA Astrophysics Data System (ADS)

    Schwartz, N.; Huisman, J. A.; Furman, A.

    2010-12-01

    The potential applicability of spectral induce polarization (SIP) as a tool to map NAPLs (non aqueous phase liquids) contaminants at the subsurface lead researchers to investigate the electric signature of those contaminant on the spectral response. However, and despite the cumulative efforts, the effect of NAPL on the electrical properties of soil, and the mechanisms that control this effect are largely unknown. In this work a novel experiment is designed to further examine the effect of NAPL on the electrical properties of partially saturated soil. The measurement system that used is the ZEL-SIP04 impedance meter developed at the Forschungszentrum Julich, Germany. The system accurately (nominal phase precision of 0.1 mrad below 1 kHz) measures the phase and the amplitude of a material possessing a very low polarization (such as soil). The sample holder has a dimension of 60 cm long and 4.6 cm in diameter. Current and potential electrodes were made of brass, and while the current electrodes were inserted in full into the soil, the contact between the potential electrode and the soil was made through an Agarose bridge. Two types of soils were used: clean quartz sand, and a mixture of sand with clean Bentonite. Each soil (sandy or clayey) was mixed with water to get saturation degree of 30%. Following the mixture with water, NAPL was added and the composite were mixed again. Packing was done by adding and compressing small portions of the soil to the column. A triplicate of each mixture was made with a good reproducible bulk density. Both for the sandy and clayey soils, the results indicate that additions of NAPL decrease the real part of the complex resistivity. Additionally, for the sandy soil this process is time depended, and that a further decrease in resistivity develops over time. The results are analyzed considering geometrical factors: while the NAPL is electrically insulator, addition of NAPL to the soil is expected to increase the connectivity of the

  20. Cross-relaxation mechanism for the formation of nuclear polarization: a quantitative time-resolved CIDNP study

    NASA Astrophysics Data System (ADS)

    Morozova, O. B.; Tsentalovich, Yu. P.; Yurkovskaya, A. V.; Sagdeev, R. Z.

    1995-12-01

    The kinetics of the nuclear polarization formed during the photolysis of acetone in isopropanol- d8 were analyzed quantitatively. Model calculations show that the spin-selective recombination of radicals gives rise to the electron polarization and, with regard to the electron-nuclear cross-relaxation, are adequate to describe the formation of the net nuclear polarization of the reaction products even if the solution contains only one type of radical. For the 2-hydroxy-2-propyl radicals at a magnetic field of 7 T, fitting the theoretical results to the experimental data gives the electron relaxation time T1e = 1.0 ± 0.2 μs and the cross-relaxation time Tx = 92 ± 18 μs.

  1. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    SciTech Connect

    Spethmann, A. Trottenberg, T. Kersten, H.

    2015-01-15

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  2. Highly precise and accurate terahertz polarization measurements based on electro-optic sampling with polarization modulation of probe pulses.

    PubMed

    Nemoto, Natsuki; Higuchi, Takuya; Kanda, Natsuki; Konishi, Kuniaki; Kuwata-Gonokami, Makoto

    2014-07-28

    We have developed an electro-optic (EO) sampling method with polarization modulation of probe pulses; this method allows us to measure the direction of a terahertz (THz) electric-field vector with a precision of 0.1 mrad in a data acquisition time of 660 ms using a 14.0-kHz repetition rate pulsed light source. Through combination with a THz time-domain spectroscopy technique, a time-dependent two-dimensional THz electric field was obtained. We used a photoelastic modulator for probe-polarization modulation and a (111)-oriented zincblende crystal as the EO crystal. Using the tilted pulse front excitation method with stable regeneratively amplified pulses, we prepared stable and intense THz pulses and performed pulse-by-pulse analog-to-digital conversion of the signals. These techniques significantly reduced statistical errors and enabled sub-mrad THz polarization measurements. We examined the performance of this method by measuring a wire-grid polarizer as a sample. The present method will open a new frontier of high-precision THz polarization sensitive measurements.

  3. A comparison of magnetic resonance methods for spatially resolved T2 distribution measurements in porous media

    NASA Astrophysics Data System (ADS)

    Vashaee, S.; Marica, F.; Newling, B.; Balcom, B. J.

    2015-05-01

    Naturally occurring porous media are usually characterized by a distribution of pore sizes. If the material is fluid saturated, the 1H magnetic resonance (MR) signal depends on the pore size, the surface relaxivity and the fluid itself. Measurement of the transverse relaxation time T2 is a well-established technique to characterize material samples by means of MR. T2 distribution measurements, including T2 distribution mapping, are widely employed in clinical applications and in petroleum engineering. T2 distribution measurements are the most basic measurement employed to determine the fluid-matrix properties in MR core analysis. Three methods for T2 distribution mapping, namely spin-echo single point imaging (SE-SPI), DANTE-Z Carr-Purcell-Meiboom-Gill (CPMG) and adiabatic inversion CPMG are compared in terms of spatial resolution, minimum observable T2 and sensitivity. Bulk CPMG measurement is considered to be the gold standard for T2 determination. Bulk measurement of uniform samples is compared to the three spatially resolved measurements. SE-SPI is an imaging method, which measures spatially resolved T2s in samples of interest. A variant is introduced in this work that employs pre-equalized magnetic field gradient waveforms and is therefore able to measure shorter T2s than previously reported. DANTE-Z CPMG and adiabatic inversion CPMG are faster, non-imaging, local T2 distribution measurements. The DANTE-Z pulse train and adiabatic inversion pulse are compared in terms of T1 or T2 relaxation time effects during the RF pulse application, minimum pulse duration, requisite RF pulse power, and inversion profile quality. In addition to experimental comparisons, simulation results are presented.

  4. Measuring molecular reorientation at liquid surfaces with time-resolved sum-frequency spectroscopy: a theoretical framework.

    PubMed

    Nienhuys, Han-Kwang; Bonn, Mischa

    2009-05-28

    A theoretical framework is presented for the design and analysis of ultrafast time- and polarization-resolved surface vibrational spectroscopy, aimed at elucidating surface molecular reorientational motion in real time. Vibrational excitation with linearly polarized light lifts the azimuthal symmetry of the surface transition-dipole distribution, causing marked, time-dependent changes in the surface sum-frequency generation (SFG) intensity. The subsequent recovery of the SFG signal generally reflects both vibrational relaxation and reorientational motion of surface molecules. We present experimental schemes that allow direct quantification of the time scale of surface molecular reorientational diffusive motion.

  5. Rotation of plasma membrane proteins measured by polarized fluorescence depletion

    NASA Astrophysics Data System (ADS)

    Barisas, B. George; Rahman, Noorul A.; Yoshida, Thomas M.; Roess, Deborah A.

    1990-05-01

    We have implemented a new laser microscopic method, polarized fluorescence depletion (PFD), for measuring the rotational dynamics of functional membrane proteins on individual, microscopically selected cells under physiological conditions. This method combines the long lifetimes of triplet-state probes with the sensitivity of fluorescence detection to measure macromolecular rotational correlation times from 10 microsec to > 1 ms. As examples, the rotational correlation time of Fc receptors (FcR) on the surface of 2H3 rat basophilic leukemia cells is 79.9 4.4 microsec at 4°C when labeled with eosin conjugates of IgE. This value is consistent with the known 100 kDa receptor size. When labeled with intact F4 anti-FcR monoclonal antibody, the rotational correlation time for FcER is increased about 2-fold to 170.8 +/- 6.5 microsec, consistent with receptor dimer formation on the plasma membrane and with the ability of this antibody to form FcER dimers on 2H3 cell surfaces. We have also examined the rotational diffusion of the luteinizing hormone receptor on plasma membranes of small ovine luteal cells. Luteinizing hormone receptors (LHR), when occupied by ovine luteinizing hormone (oLH), have a rotational correlation time of 20.5 +/- 0.1 microsec at 4°C. When occupied by human chorionic gonadotropin (hCG), LHR have a rotational correlation time of 46.2 +/- 0.4 microsec suggesting that binding of hCG triggers additional LHR interactions with plasma membrane proteins. Together these studies suggest the utility of PFD measurements in assessing molecular size and molecular association of membrane proteins on individual cells. Relative advantages of time- and frequency-domain implementations of PFD are also discussed.

  6. Depth-resolved photothermal optical coherence tomography by local optical path length change measurement (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Makita, Shuichi; Hong, Young-Joo; Li, En; Yasuno, Yoshiaki

    2016-03-01

    Photothermal OCT has been emerged to contrast absorbers in biological tissues. The tissues response to photothermal excitation as change of thermal strain and refractive index. To resolve the depth of absorption agents, the measurements of the local thermal strain change and local refractive index change due to photothermal effect is required. In this study, we developed photothermal OCT for depth-resolved absorption contrast imaging. The phase-resolved OCT can measure the axial strain change and local refractive index change as local optical path length change. A swept-source OCT system is used with a wavelength swept laser at 1310 nm with a scanning rate of 50 kHz. The sensitivity of 110 dB is achieved. At the sample arm, the excitation beam from a fiber-coupled laser diode of 406 nm wavelength is combined with the OCT probe beam co-linearly. The slowly modulated excitation beam around 300 Hz illuminate biological tissues. M-mode scan is applied during one-period modulation duration. The local optical path length change is measured by temporal and axial phase difference. The theoretical prediction of the photothermal response is derived and in good agreement with experimental results. In the case of slow modulation, the delay of photothermal response can be neglected. The local path length changes are averaged over the half period of the excitation modulation, and then demodulated. This method exhibits 3-dB gain in the sensitivity of the local optical path length change measurement over the direct Fourier transform method. In vivo human skin imaging of endogenous absorption agent will be demonstrated.

  7. Two-color-absorption sensor for time-resolved measurements of gasoline concentration and temperature.

    PubMed

    Pyun, Sung Hyun; Porter, Jason M; Jeffries, Jay B; Hanson, Ronald K; Montoya, Juan C; Allen, Mark G; Sholes, Kevin R

    2009-11-20

    A midinfrared absorption sensor for crank-angle-resolved in-cylinder measurements of gasoline concentration and gas temperature for spark-ignition internal-combustion engines is reported, and design considerations and validation testing in the controlled environments of a heated cell and shock-heated gases are discussed. Mid-IR laser light was tuned to transitions in the strong absorption bands associated with C-H stretching vibration near 3.4 microm, and time-resolved fuel vapor concentration and gas temperature were determined simultaneously from the absorption at two different wavelengths. These two infrared laser wavelengths were simultaneously produced by difference-frequency generation, which combines a near-IR signal laser with two near-IR pump lasers in a periodically poled lithium niobate crystal. Injection current modulation of the pump lasers produced intensity modulation of the mid-IR, which allowed the transmitted signals from the two laser wavelengths to be detected on a single detector and separated by frequency demultiplexing. Injection current modulation produced a wavelength modulation synchronous with the intensity modulation for each of the laser wavelengths, and accurate measurement of the gasoline absorption signal required the effects of wavelength modulation to be considered. Validation experiments were conducted for a single-component hydrocarbon fuel (2,2,4-trimethyl-pentane, commonly known as iso-octane) and a gasoline blend in a heated static cell (300 < or = T < or = 600 K) and behind planar shock waves (600 < T < 1100 K) in a shock tube. With a bandwidth of 10 kHz, the measured fuel concentrations agreed within 5% RMS and the measured temperature agreed within 3% RMS to the known values. The 10 kHz bandwidth is sufficient to resolve 1 crank-angle degree at 1600 RPM.

  8. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    NASA Astrophysics Data System (ADS)

    Burris, J.; Sun, X.

    2011-12-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be >~20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (<~0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels. An assessment of the technique, discussions of measurement precision and error sources as well as preliminary data will be presented.

  9. Time-Resolved Langmuir Probe Measurements in an Ionized PVD System

    NASA Astrophysics Data System (ADS)

    Juliano, D. R.; Hayden, D. B.; Ruzic, D. N.

    1997-10-01

    The experimental apparatus consists of a commercial-scale magnetron (Donated by Materials Research Corporation) with an RF coil between the target and substrate holder. This coil creates a secondary inductive plasma that ionizes a significant portion of the sputter flux en route from target to substrate. Ionization of the metal atoms that make up the sputter flux is highly sensitive to the high energy tail of the electron energy distribution, which in turn is highly dependent on the background gas mixture. Since there is some capacitive coupling from the coil this high energy population could change through the RF cycle. Time-averaged Langmuir probe measurements would not reveal either the extent of this high energy population or its time dependence. Further, if the probe voltage were held constant for such time-resolved measurements, they would yield incorrect results. At probe voltages above the plasma potential minimum the sheath is disrupted so that at points in the phase for which the probe voltage is below plasma potential the data is invalid. Therefore in order to take valid measurements at all phase points, it is necessary for the probe voltage to follow the RF variation in plasma potential. Using such a system, we have made time-resolved Langmuir probe measurements. Current-voltage traces as a function of phase then reveal plasma parameters as a function of time over the RF cycle for various background gases and operating parameters.

  10. Atomically-resolved mapping of polarization and electric fields across ferroelectric-oxide interfaces by Z-contrast imaging

    SciTech Connect

    Chang, Hye Jung; Kalinin, Sergei; Morozovska, A. N.; Huijben, Mark; Chu, Ying-Hao; Yu, P; Ramesh, R.; Eliseev, E. A.; Svechnikov, S. V.; Pennycook, Stephen J; Borisevich, Albina Y

    2011-01-01

    Direct atomic displacement mapping at ferroelectric interfaces by aberration corrected scanning transmission electron microscopy(STEM) (a-STEM image, b-corresponding displacement profile) is combined with Landau-Ginsburg-Devonshire theory to obtain the complete interface electrostatics in real space, including separate estimates for the polarization and intrinsic interface charge contributions.

  11. Accurate measurement of the residual birefringence in VECSEL: Towards understanding of the polarization behavior under spin-polarized pumping.

    PubMed

    Frougier, Julien; Baili, Ghaya; Sagnes, Isabelle; Dolfi, Daniel; George, Jean-Marie; Alouini, Mehdi

    2015-04-20

    In this paper we report birefringence measurements of an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well (MQWs) Vertical External Cavity Surface Emitting Laser (VECSEL) in oscillating conditions. The proposed technique relies on the measurement in the microwave domain of the beatnote between the oscillating mode and the amplified spontaneous emission of the cross-polarized non-lasing field lying in the following longitudinal mode. This technique is shown to offer extremely high sensitivity and accuracy enabling to track the amount of residual birefringence according to the laser operation conditions. The experience fits within the broader framework of polarization selection in spin-injected lasers.

  12. Development of Multi-Field of view-Multiple-Scattering-Polarization Lidar : analysis of angular resolved backscattered signals

    NASA Astrophysics Data System (ADS)

    Makino, T.; Okamoto, H.; Sato, K.; Tanaka, K.; Nishizawa, T.; Sugimoto, N.; Matsui, I.; Jin, Y.; Uchiyama, A.; Kudo, R.

    2014-12-01

    We have developed a new type of ground-based lidar, Multi-Field of view-Multiple-Scattering-Polarization Lidar (MFMSPL), to analyze multiple scattering contribution due to low-level clouds. One issue of the ground based lidar is the limitation of optical thickness of about 3 due to the strong attenuation in the lidar signals so that only the cloud bottom part can be observed. In order to overcome the problem, we have proposed the MFMSPL that has been designed to observe similar degree of multiple scattering contribution expected from space-borne lidar CALIOP on CALIPSO satellite. The system consists of eight detectors; four telescopes for parallel channels and four for perpendicular channels. The four pairs of telescope have been mounted with four different off-beam angles, ranging from -5 to 35mrad, where the angle is defined as the one between the direction of laser beam and the direction of telescope. Consequently, similar large foot print (100m) as CALIOP can be achieved in the MFMSPL observations when the altitude of clouds is located at about 1km. The use of multi-field of views enables to measure depolarization ratio from optically thick clouds. The outer receivers attached with larger angles generally detect backscattered signals from clouds located at upper altitudes due to the enhanced multiple scattering compared with the inner receiver that detects signals only from cloud bottom portions. Therefore the information of cloud microphysics from optically thicker regions is expected by the MFMSPL observations compared with the conventional lidar with small FOV. The MFMSPL have been continuously operated in Tsukuba, Japan since June 2014.Initial analyses have indicated expected performances from the theoretical estimation by backward Monte-Carlo simulations. The depolarization ratio from deeper part of the clouds detected by the receiver with large off-beam angle showed much larger values than those from the one with small angle. The calibration procedures

  13. Measuring Spatially Resolved Collective Ionic Transport on Lithium Battery Cathodes Using Atomic Force Microscopy.

    PubMed

    Mascaro, Aaron; Wang, Zi; Hovington, Pierre; Miyahara, Yoichi; Paolella, Andrea; Gariepy, Vincent; Feng, Zimin; Enright, Tyler; Aiken, Connor; Zaghib, Karim; Bevan, Kirk H; Grutter, Peter

    2017-07-12

    One of the main challenges in improving fast charging lithium-ion batteries is the development of suitable active materials for cathodes and anodes. Many materials suffer from unacceptable structural changes under high currents and/or low intrinsic conductivities. Experimental measurements are required to optimize these properties, but few techniques are able to spatially resolve ionic transport properties at small length scales. Here we demonstrate an atomic force microscope (AFM)-based technique to measure local ionic transport on LiFePO4 to correlate with the structural and compositional analysis of the same region. By comparing the measured values with density functional theory (DFT) calculations, we demonstrate that Coulomb interactions between ions give rise to a collective activation energy for ionic transport that is dominated by large phase boundary hopping barriers. We successfully measure both the collective activation energy and the smaller single-ion bulk hopping barrier and obtain excellent agreement with values obtained from our DFT calculations.

  14. Polarized fluorescence measurements on ordered photosynthetic antenna complexes

    PubMed Central

    van Amerongen, H.; van Haeringen, B.; van Gurp, M.; van Grondelle, R.

    1991-01-01

    We have used a new and relatively easy approach to study the pigment-organization in chlorosomes from the photosynthetic bacterium Chloroflexus aurantiacus and in B800-850 antenna complexes of the photosynthetic purple bacterium Rhodobacter sphaeroides. These particles were embedded in compressed and uncompressed gels and the polarized fluorescence was determined in a 90° setup. Assuming both a rotational symmetric distribution of the particles in the gel and of the transition dipole moments in the particles, the order parameters and , describing the orientation of the symmetry axis of the particles with respect to the direction of gel expansion can be determined. Moreover, the direction parameters, describing the orientation of the absorption and emission dipole moments with respect to the symmetry axis of the particles can be obtained. The value of is essential for quantitative interpretation of linear dichroism measurements and usually it is estimated from theoretical approaches, which may lead to incorrect results. For the rod-like chlorosomes the value of appears to be the same as predicted by the theoretical approach of Ganago, A. O., M. V. Fok, I. A. Abdourakhmanov, A. A. Solov'ev, and Yu. E. Erokhin (1980. Mol. Biol. [Mosc.]. 14:381-389). The agreement with linear dichroism results, analyzed with this theoretical approach shows that the transition dipole moments are indeed in good approximation distributed in a rotationally symmetric way around the long axis of the chlorosomes. Moreover, it appears those BChl c molecules, which fluoresce, are oriented in the same way with respect to the symmetry axis as the rest of these pigments, with the dipole moments close to parallel to the long axis. The B800-850 complexes appear to orient like discs, whereas the transition dipoles of the BChl a 800- and 850-nm bands are oriented almost perpendicular to the symmetry axis. These findings are in agreement with the minimal model for these complexes

  15. The sensitivity to polarization in stratospheric aerosol retrievals from limb scattered sunlight measurements

    NASA Astrophysics Data System (ADS)

    Elash, B. J.; Bourassa, A. E.; Rieger, L. A.; Dueck, S. R.; Zawada, D. J.; Degenstein, D. A.

    2017-03-01

    Satellite measurements of limb scattered sunlight at visible and near infrared wavelengths have been used successfully for several years to retrieve the vertical profile of stratospheric aerosol extinction coefficient. The existing satellite measurements are of the total radiance, with very little knowledge or impact of the polarization state of the limb radiance. Recently proposed instrument concepts for stratospheric aerosol profiling have been designed to measure the linearly polarized radiance. Yet, to date, the impact of the polarized measurement on the retrievals has not been systematically studied. Here we use a fully spherical, multiple scattering radiative transfer model to perform a sensitivity study on the effects of the polarized measurement on stratospheric aerosol extinction retrievals through specific investigations of the aerosol signal fraction in polarized measurements, potential retrieval bias, and achievable precision. In this study,we simulate both total and linearly polarized measurements, for a wide range of limb viewing geometries that are encountered in typical low earth orbits and for various aerosol loading scenarios. The orientation of the linear polarization with respect to the horizon is also studied. Taking into account instrument signal to noise levels it is found that in general, the linear polarization can be used as effectively as the total radiance measurement, with consideration of instrument signal to noise capabilities; however the horizontal polarization is more promising in terms of signal magnitude.

  16. Dispersion measurement on chirped mirrors at arbitrary incidence angle and polarization state (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kovacs, Mate; Somoskoi, Tamas; Seres, Imre; Borzsonyi, Adam; Sipos, Aron; Osvay, Károly

    2017-05-01

    The optical elements of femtosecond high peak power lasers have to fulfill more and more strict requirements in order to support pulses with high intensity and broad spectrum. In most cases chirped pulse amplification scheme is used to generate high peak power ultrashort laser pulses, where a very precise control of spectral intensity and spectral phase is required in reaching transform-limited temporal shape at the output. In the case of few cycle regime, the conventional bulk glass, prism-, grating- and their combination based compressors are not sufficient anymore, due to undesirable nonlinear effects in their material and proneness to optical damages. The chirped mirrors are also commonly used to complete the compression after a beam transport system just before the target. Moreover, the manufacturing technology requires quality checks right after production and over the lifetime of the mirror as well, since undesired deposition on the surface can lead alteration from the designed value over a large part of the aperture. For the high harmonic generation, polarization gating technology is used to generate single attosecond pulses [1]. In this case the pulse to be compressed has various polarization state falling to the chirped mirrors. For this reason, it is crucial to measure the dispersion of the mirrors for the different polarization states. In this presentation we demonstrate a simple technique to measure the dispersion of arbitrary mirror at angles of incidence from 0 to 55 degree, even for a 12" optics. A large aperture 4" mirror has been scanned over with micrometer accuracy and the dispersion property through the surface has been investigated with a stable interference fringes in that robust geometry. We used Spectrally Resolved Interferometry, which is based on a Michaelson interferometer and a combined visible and infrared spectrometer. Tungsten halogen lamp with 10 mW coupled optical power was used as a white-light source so with the selected

  17. A sensitive time-resolved radiation pyrometer for shock-temperature measurements above 1500 K

    NASA Technical Reports Server (NTRS)

    Boslough, Mark B.; Ahrens, Thomas J.

    1989-01-01

    The general design, calibration, and performance of a new high-sensitivity radiation pyrometer are described. The pyrometer can determine time-resolved temperatures (as low as 1500 K) in shocked materials by measuring the spectral radiance of light emitted from shocked solid samples in the visible and near-infrared wavelength range (0.5-1.0 micron). The high sensitivity of the radiation pyrometer is attributed to the large angular aperture (0.06 sr), the large bandwidth per channel (up to 0.1 micron), the large photodiode detection areas (1.0 sq cm), and the small number of calibrated channels (4) among which light is divided.

  18. Molecular diffusivity measurement through an alumina membrane using time-resolved fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Kennard, Raymond; DeSisto, William J.; Mason, Michael D.

    2010-11-01

    We present a simple fluorescence imaging method for measuring the time-resolved concentration of a fluorescent molecule diffusing through an anodic alumina membrane with a pore diameter of 20 nm. From the concentration breakthrough curve, the molecular diffusivity of the fluorophore was extracted. The experimentally determined diffusivity was three orders of magnitude lower than reported bulk values. Due to the relative simplicity and ease of use, this method can be applied to provide fundamental information for biomolecular separations applications. One feature of this method is the high sensitivity at intercellular volumes broadening its application to drug delivery and controlled cell growth.

  19. Hydrogen tracer diffusion in LiBH4 measured by spatially resolved Raman spectroscopy.

    PubMed

    Borgschulte, A; Gremaud, R; Łodziana, Z; Züttel, A

    2010-05-21

    The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectroscopy. The measurements give direct evidence of a macroscopic diffusion of BH ions as well as atomic exchange of hydrogen between the anions. An effective tracer diffusion coefficient of deuterium in LiBH(4) of D approximately 7 x 10(-14) m(2) s(-1) at 473 K is derived. The direct exchange rate of hydrogen between BH(4) units is 10 orders of magnitude slower, i.e. the relatively fast effective hydrogen diffusion has its origin in the fast diffusion of BH(4) units.

  20. Radiative lifetime measurements of some Gd I levels by time-resolved laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Shang, Xue; Zhou, Chunxiao; Dai, Zhenwen

    2017-04-01

    Natural radiative lifetimes for 27 excited levels of Gd I in the energy range from 28215.140 to 43963.900 cm-1 were measured using time-resolved laser-induced fluorescence (TR-LIF) technique in an atom beam produced by laser-induced plasma. All the lifetimes obtained in this paper range from 8.4 to 833 ns with the uncertainties within ten percent. A comparison with a few previously reported values was performed and good agreement between them was achieved. To our best knowledge, 18 lifetimes of Gd I are reported for the first time.

  1. Time-resolved energy spectrum measurement of a linear induction accelerator with the magnetic analyzer

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Jiang, Xiao-Guo; Yang, Guo-Jun; Chen, Si-Fu; Zhang, Zhuo; Wei, Tao; Li, Jin

    2015-01-01

    We recently set up a time-resolved optical beam diagnostic system. Using this system, we measured the high current electron beam energy in the accelerator under construction. This paper introduces the principle of the diagnostic system, describes the setup, and shows the results. A bending beam line was designed using an existing magnetic analyzer with a 300 mm-bending radius and a 60° bending angle at hard-edge approximation. Calculations show that the magnitude of the beam energy is about 18 MeV, and the energy spread is within 2%. Our results agree well with the initial estimates deduced from the diode voltage approach.

  2. Time-resolved voltage measurements of Z-pinch radiation sources with a vacuum voltmeter

    SciTech Connect

    Murphy, D. P.; Allen, R. J.; Weber, B. V.; Commisso, R. J.; Apruzese, J. P.; Phipps, D. G.; Mosher, D.

    2008-10-15

    A vacuum-voltmeter (VVM) was fielded on the Saturn pulsed power generator during a series of argon gas-puff Z-pinch shots. Time-resolved voltage and separately measured load current are used to determine several dynamic properties as the load implodes, namely, the inductance, L(t), net energy coupled to the load, E{sub coupled}(t), and the load radius, r(t). The VVM is a two-stage voltage divider, designed to operate at voltages up to 2 MV. The VVM is presently being modified to operate at voltages up to 6 MV for eventual use on the Z generator.

  3. Time-Resolved Voltage Measurements of Imploding Radiation Sources at 6 MA with a Vacuum Voltmeter

    DTIC Science & Technology

    2007-06-01

    Communications/Titan Group, Reston, VA 20190 USA Abstract A vacuum -voltmeter[1] (VVM) was fielded on the Saturn pulsed -power generator during a series...electrons causing the VVM insulator stack to flashover . Metal Shield e 0 1 2 3 4 5 6 7 8 9 10 100 200 300 40 Figure 8. Saturn gas-puff shot 3565 data...TIME-RESOLVED VOLTAGE MEASUREMENTS OF IMPLODING RADIATION SOURCES AT 6 MA WITH A VACUUM VOLTMETER ∗ D. P. Murphyξ, B. V. Weber, R. J. Commisso, J

  4. SPOrt: an experiment aimed at measuring the large scale cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Carretti, Ettore; Cortiglioni, Stefano; Bernardi, Gianni; Cecchini, Stefano; Macculi, Claudio; Sbarra, Carla; Monari, Jader; Orfei, Alessandro; Poloni, Marco; Poppi, Sergio; Boella, Giuliano; Bonometto, Silvio; Gervasi, Massimo; Sironi, Giorgio; Zannoni, Mario; Tucci, Marco; Baralis, Massino; Peverini, Oscar A.; Tascone, Riccardo; Virone, Giuseppe; Fabbri, Roberto; Nicastro, Luciano; Ng, Kin-Wang; Razin, V. A.; Vinyajkin, Evgenij N.; Sazhin, Mikhail V.; Strukov, Igor A.

    2003-02-01

    SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the International Space Station during Early Utilization Phase aimed at measuring the microwave polarized emission with FWHM = 7 deg, in the frequency range 22-90 GHz. The Galactic polarized emission can be observed at the lower frequencies and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where contaminants are expected to be less important. The extremely low level of the CMB Polarization signal calls for intrinsically stable radiometers. The SPOrt instrument is expressly devoted to CMB polarization measurements and the whole design has been optimized for minimizing instrumental polarization effects. In this contribution we present the receiver architecture based on correlation techniques, the analysis showing its intrinsic stability and the custom hardware development carried out to detect such a low signal.

  5. Polarized Imaging Nephelometer for Field and Aircraft Measurements of Aerosol Phase Function

    NASA Astrophysics Data System (ADS)

    Dolgos, G.; Martins, J.

    2012-12-01

    Aerosols have a significant impact on the radiative balance and water cycle of our planet through influencing atmospheric radiation. Remote sensing of aerosols relies on scattering phase matrix information to retrieve aerosol properties with frequent global coverage. At the Laboratory for Aerosols, Clouds and Optics (LACO) at the University of Maryland, Baltimore County we developed a new technique to directly measure the aerosol phase function and the degree of linear polarization of the scattered light (two elements of the phase matrix). We designed and built a portable instrument called the Polarized Imaging Nephelometer (PI-Neph). The PI-Neph successfully participated in dozens of flights of the NASA Development and Evaluation of satellite ValidatiOn Tools by Experimenters (DEVOTE) project and the Deep Convective Clouds and Chemistry (DC3) project. The ambient aerosol enters the PI-Neph through an inlet and the sample is illuminated by laser light (wavelength of 532 nm); the scattered light is imaged by a stationary wide field of view camera in the scattering angle range of 2° to 178°. (In some cases stray light limited the scattering angle range to 3° to 176°). The PI-Neph measurement of phase function and the AERONET (AErosol RObotic NETwork) retrievals have already been compared in some cases when the aircraft spiraled over AERONET sites, for example at NASA's Wallops Flight Facility, on October 18 2011, as shown in Figure 1. The differences between the PI-Neph and the AERONET retrievals can be attributed to differences between the ambient size distribution and the one sampled inside the aircraft. The data that is resolved with respect to scattering angle is used to compute the volume scattering coefficient. The above mentioned October 18 flight data showed good agreement between the PI-Neph measurements of volume scattering coefficient and the parallel TSI integrating nephelometer measurements. On average the TSI measurements were 1.02 times the PI

  6. Subcellular localization-dependent changes in EGFP fluorescence lifetime measured by time-resolved flow cytometry

    PubMed Central

    Gohar, Ali Vaziri; Cao, Ruofan; Jenkins, Patrick; Li, Wenyan; Houston, Jessica P.; Houston, Kevin D.

    2013-01-01

    Intracellular protein transport and localization to subcellular regions are processes necessary for normal protein function. Fluorescent proteins can be fused to proteins of interest to track movement and determine localization within a cell. Currently, fluorescence microscopy combined with image processing is most often used to study protein movement and subcellular localization. In this contribution we evaluate a high-throughput time-resolved flow cytometry approach to correlate intracellular localization of human LC3 protein with the fluorescence lifetime of enhanced green fluorescent protein (EGFP). Subcellular LC3 localization to autophagosomes is a marker of the cellular process called autophagy. In breast cancer cells expressing native EGFP and EGFP-LC3 fusion proteins, we measured the fluorescence intensity and lifetime of (i) diffuse EGFP (ii) punctate EGFP-LC3 and (iii) diffuse EGFP-ΔLC3 after amino acid starvation to induce autophagy-dependent LC3 localization. We verify EGFP-LC3 localization with low-throughput confocal microscopy and compare to fluorescence intensity measured by standard flow cytometry. Our results demonstrate that time-resolved flow cytometry can be correlated to subcellular localization of EGFP fusion proteins by measuring changes in fluorescence lifetime. PMID:24010001

  7. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    DOE PAGES

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; ...

    2016-01-27

    In research and industrial environments, additive manufacturing (AM) of metals and alloys is becoming a pervasive technology, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al–Cu and Al–Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid–liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. We observed microstructure evolution, solidification product, andmore » presence of a morphological instability at the solid–liquid interface in the Al–4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.« less

  8. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    NASA Technical Reports Server (NTRS)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

  9. Space-resolved fluorescence spectroscopic measurements with an optical fiber probe

    NASA Astrophysics Data System (ADS)

    Li, Enbang; Qiu, Hialin

    2008-12-01

    By monitoring of the emitted signal from a sample while varying the excitation wavelength, emission wavelength or both of them, fluorescence spectroscopy has become a powerful diagnostic technology. Fluorescence spectrometers can be used to measure and record the fluorescence spectra of a given sample, and have been successfully applied in different areas including biology, biochemistry, chemistry, medicine, environmental science, material science, food industry, and pharmaceutical industry. In order to increase the flexibility and applicability of conventional fluorescence spectrometers, we design an optic fiber probe for conducting the UV/Vis excitation light to a sample under study, and for collecting the fluorescence produced by the sample. Different excitation/emission fiber bundle arrangements have been fabricated and their performances have been evaluated and compared. Fiber adaptors which can be used for different commercial fluorescence spectrometers are also developed. In order to achieve space-resolved fluorescence spectroscopic measurements, we connect the fiber probe to a microscope which is mounted on a 3D traverse stage. Experiments and measurement results using the space-resolved fiber optic fluorescence spectrometer are presented in this paper.

  10. The Dosepix detector—an energy-resolving photon-counting pixel detector for spectrometric measurements

    NASA Astrophysics Data System (ADS)

    Zang, A.; Anton, G.; Ballabriga, R.; Bisello, F.; Campbell, M.; Celi, J. C.; Fauler, A.; Fiederle, M.; Jensch, M.; Kochanski, N.; Llopart, X.; Michel, N.; Mollenhauer, U.; Ritter, I.; Tennert, F.; Wölfel, S.; Wong, W.; Michel, T.

    2015-04-01

    The Dosepix detector is a hybrid photon-counting pixel detector based on ideas of the Medipix and Timepix detector family. 1 mm thick cadmium telluride and 300 μm thick silicon were used as sensor material. The pixel matrix of the Dosepix consists of 16 x 16 square pixels with 12 rows of (200 μm)2 and 4 rows of (55 μm)2 sensitive area for the silicon sensor layer and 16 rows of pixels with 220 μm pixel pitch for CdTe. Besides digital energy integration and photon-counting mode, a novel concept of energy binning is included in the pixel electronics, allowing energy-resolved measurements in 16 energy bins within one acquisition. The possibilities of this detector concept range from applications in personal dosimetry and energy-resolved imaging to quality assurance of medical X-ray sources by analysis of the emitted photon spectrum. In this contribution the Dosepix detector, its response to X-rays as well as spectrum measurements with Si and CdTe sensor layer are presented. Furthermore, a first evaluation was carried out to use the Dosepix detector as a kVp-meter, that means to determine the applied acceleration voltage from measured X-ray tubes spectra.

  11. Time-resolved particle velocity measurements at impact velocities of 10 km/s

    SciTech Connect

    Furnish, M.D.; Chhabildas, L.C.; Reinhart, W.D.

    1998-08-01

    Hypervelocity launch capabilities (9--16 km/s) with macroscopic plates have become available in recent years. It is now feasible to conduct instrumented plane-wave tests using this capability. Successfully conducting such tests requires a planar launch and impact at hypervelocities, appropriate triggering for recording systems, and time-resolved measurements of motion or stress at a particular point or set of points within the target or projectile during impact. The authors have conducted the first time-resolved wave-profile experiments using velocity interferometric techniques at impact velocities of 10 km/s. These measurements show that aluminum continues to exhibit normal release behavior to 161 GPa shock pressure, with complete loss of strength of the shocked state. These experiments have allowed a determination of shock-wave window transparency in conditions produced by a hypervelocity impact. In particular, lithium fluoride appears to lose transparency at a shock stress of 200 GPa; this appears to be the upper limit for conventional wave profile measurements using velocity interferometric techniques.

  12. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    SciTech Connect

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-01-27

    In research and industrial environments, additive manufacturing (AM) of metals and alloys is becoming a pervasive technology, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al–Cu and Al–Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid–liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. We observed microstructure evolution, solidification product, and presence of a morphological instability at the solid–liquid interface in the Al–4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  13. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-03-01

    Additive manufacturing (AM) of metals and alloys is becoming a pervasive technology in both research and industrial environments, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al-Cu and Al-Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid-liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. The observed microstructure evolution, solidification product, and presence of a morphological instability at the solid-liquid interface in the Al-4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  14. Circular dichroism in the angle-resolved photoemission spectrum of the high-temperature Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} superconductor: can these measurements be interpreted as evidence for time-reversal symmetry breaking?

    PubMed

    Arpiainen, V; Bansil, A; Lindroos, M

    2009-08-07

    We report first-principles computations of the angle-resolved photoemission response with circularly polarized light in Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} for the purpose of delineating contributions to the circular dichroism resulting from distortions and modulations of the crystal lattice. Comparison with available experimental results shows that the measured circular dichroism from antinodal mirror planes is reproduced in quantitative detail in calculations employing the average orthorhombic crystal structure. We thus conclude that the existing angle-resolved photoemission measurements can be understood essentially within the framework of the conventional picture, without the need to invoke unconventional mechanisms.

  15. Identifiability analysis of rotational diffusion tensor and electronic transition moments measured in time-resolved fluorescence depolarization experiment.

    PubMed

    Szubiakowski, Jacek P

    2014-06-14

    The subject of this paper is studies of the deterministic identifiability of molecular parameters, such as rotational diffusion tensor components and orientation of electronic transition moments, resulting from the time-resolved fluorescence anisotropy experiment. In the most general case considered, a pair of perpendicularly polarized emissions enables the unique determination of all the rotational diffusion tensor's principal components. The influence of the tensor's symmetry and the associated degeneration of its eigenvalues on the identifiability of the electronic transitions moments is systematically investigated. The analysis reveals that independently of the rotational diffusion tensor's symmetry, the transition moments involved in photoselection and emission processes cannot be uniquely identified without a priori information about their mutual orientation or their orientation with respect to the principal axes of the tensor. Moreover, it is shown that increasing the symmetry of the rotational diffusion tensor deteriorates the degree of the transition moments identifiability. To obtain these results analytically, a novel approach to solve bilinear system of equations for Markov parameters is applied. The effect of the additional information, obtained from fluorescence measurements for different molecular mobilities, to improve the identifiability at various levels of analysis is shown. The effectiveness and reliability of the target analysis method for experimental determination of the molecular parameters is also discussed.

  16. Identifiability analysis of rotational diffusion tensor and electronic transition moments measured in time-resolved fluorescence depolarization experiment

    SciTech Connect

    Szubiakowski, Jacek P.

    2014-06-14

    The subject of this paper is studies of the deterministic identifiability of molecular parameters, such as rotational diffusion tensor components and orientation of electronic transition moments, resulting from the time-resolved fluorescence anisotropy experiment. In the most general case considered, a pair of perpendicularly polarized emissions enables the unique determination of all the rotational diffusion tensor's principal components. The influence of the tensor's symmetry and the associated degeneration of its eigenvalues on the identifiability of the electronic transitions moments is systematically investigated. The analysis reveals that independently of the rotational diffusion tensor's symmetry, the transition moments involved in photoselection and emission processes cannot be uniquely identified without a priori information about their mutual orientation or their orientation with respect to the principal axes of the tensor. Moreover, it is shown that increasing the symmetry of the rotational diffusion tensor deteriorates the degree of the transition moments identifiability. To obtain these results analytically, a novel approach to solve bilinear system of equations for Markov parameters is applied. The effect of the additional information, obtained from fluorescence measurements for different molecular mobilities, to improve the identifiability at various levels of analysis is shown. The effectiveness and reliability of the target analysis method for experimental determination of the molecular parameters is also discussed.

  17. Comparison of physicochemical and gas chromatographic polarity measures for simple organic compounds.

    PubMed

    Héberger, Károly; Zenkevich, Igor G

    2010-04-23

    The comparison of different polarity measures (parameters, descriptors, variables, scales, etc.) indicates that evaluation of interrelations between these measures is important for better understanding and interpretation of chemical and/or analytical data, especially for chromatographic separation. The best linear correlation between gas chromatographic and non-chromatographic polarity descriptors is revealed for the first time: this pair of variables is the difference of gas chromatographic retention indices on standard polar and non-polar phases as well as the difference between non-dimensional indices of boiling points (known in chromatography since mid-1980s as dispersion indices) and indices of molar refractions. The correlation helps chromatographers to find preferable chemical variables (features) to understand better the separation phenomena and to find better correlations in QSRR models. Principal component analysis (PCA) of ten frequently applied polarity measures shows their similarity and, at the same time, it shows the absence of anomalies within the set of simple organic molecules. A novel ranking method for ten polarity parameters points out that the two most informative polarity measures are (i) the non-dimensional index for boiling point and (ii) the difference in chromatographic retention indices on standard polar and non-polar stationary phases. On the other hand, the hydrophobicity parameter, log P, sometimes considered as polarity parameter in HPLC seems to be the worst one in description of "polarity" in gas chromatography. Surprisingly, such polarity measures like dipole moment and permittivity used often in organic chemistry does not provide the best correlation with gas chromatographic polarity measures.

  18. Polarization and Color Filtering Applied to Enhance Photogrammetric Measurements of Reflective Surfaces

    NASA Technical Reports Server (NTRS)

    Wells, Jeffrey M.; Jones, Thomas W.; Danehy, Paul M.

    2005-01-01

    Techniques for enhancing photogrammetric measurement of reflective surfaces by reducing noise were developed utilizing principles of light polarization. Signal selectivity with polarized light was also compared to signal selectivity using chromatic filters. Combining principles of linear cross polarization and color selectivity enhanced signal-to-noise ratios by as much as 800 fold. More typical improvements with combining polarization and color selectivity were about 100 fold. We review polarization-based techniques and present experimental results comparing the performance of traditional retroreflective targeting materials, cornercube targets returning depolarized light, and color selectivity.

  19. Quantitative time-resolved measurement of membrane protein-ligand interactions using microcantilever array sensors.

    PubMed

    Braun, Thomas; Ghatkesar, Murali Krishna; Backmann, Natalija; Grange, Wilfried; Boulanger, Pascale; Letellier, Lucienne; Lang, Hans-Peter; Bietsch, Alex; Gerber, Christoph; Hegner, Martin

    2009-03-01

    Membrane proteins are central to many biological processes, and the interactions between transmembrane protein receptors and their ligands are of fundamental importance in medical research. However, measuring and characterizing these interactions is challenging. Here we report that sensors based on arrays of resonating microcantilevers can measure such interactions under physiological conditions. A protein receptor--the FhuA receptor of Escherichia coli--is crystallized in liposomes, and the proteoliposomes then immobilized on the chemically activated gold-coated surface of the sensor by ink-jet spotting in a humid environment, thus keeping the receptors functional. Quantitative mass-binding measurements of the bacterial virus T5 at subpicomolar concentrations are performed. These experiments demonstrate the potential of resonating microcantilevers for the specific, label-free and time-resolved detection of membrane protein-ligand interactions in a micro-array format.

  20. Velocity Field Measurements of Human Coughing Using Time Resolved Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Khan, T.; Marr, D. R.; Higuchi, H.; Glauser, M. N.

    2003-11-01

    Quantitative fluid mechanics analysis of human coughing has been carried out using new Time Resolved Particle Image Velocimetry (TRPIV). The study involves measurement of velocity vector time-histories and velocity profiles. It is focused on the average normal human coughing. Some work in the past on cough mechanics has involved measurement of flow rates, tidal volumes and sub-glottis pressure. However, data of unsteady velocity vector field of the exiting highly time-dependent jets is not available. In this study, human cough waveform data are first acquired in vivo using conventional respiratory instrumentation for various volunteers of different gender/age groups. The representative waveform is then reproduced with a coughing/breathing simulator (with or without a manikin) for TRPIV measurements and analysis. The results of this study would be useful not only for designing of indoor air quality and heating, ventilation and air conditioning systems, but also for devising means of protection against infectious diseases.

  1. Time Resolved Detectors and Measurements for Accelerators and Beamlines at the Australian Synchrotron

    NASA Astrophysics Data System (ADS)

    Boland, M. J.; Rassool, R. P.; LeBlanc, G. S.; Peake, D. J.; Sobott, B. A.; Lee, V.; Schubert, A.; Kirby, N.

    2010-06-01

    Time resolved experiments require precision timing equipment and careful configuration of the machine and the beamline. The Australian Synchrotron has a state of the art timing system that allows flexible, real-time control of the machine and beamline timing parameters to target specific electron bunches. Results from a proof-of-principle measurement with a pulsed laser and a streak camera on the optical diagnostic beamline will be presented. The timing system was also used to fast trigger the PILATUS detector on an x-ray beamline to measure the fill pattern dependent effects of the detector. PILATUS was able to coarsely measure the fill pattern in the storage ring which implies that fill pattern intensity variations need to be corrected for when using the detector in this mode.

  2. Time Resolved Detectors and Measurements for Accelerators and Beamlines at the Australian Synchrotron

    SciTech Connect

    Boland, M. J.; Rassool, R. P.; Peake, D. J.; Sobott, B. A.; Lee, V.; Schubert, A.; LeBlanc, G. S.; Kirby, N.

    2010-06-23

    Time resolved experiments require precision timing equipment and careful configuration of the machine and the beamline. The Australian Synchrotron has a state of the art timing system that allows flexible, real-time control of the machine and beamline timing parameters to target specific electron bunches. Results from a proof-of-principle measurement with a pulsed laser and a streak camera on the optical diagnostic beamline will be presented. The timing system was also used to fast trigger the PILATUS detector on an x-ray beamline to measure the fill pattern dependent effects of the detector. PILATUS was able to coarsely measure the fill pattern in the storage ring which implies that fill pattern intensity variations need to be corrected for when using the detector in this mode.

  3. Spatially Resolved Measurements of a Double Layer in an Argon Helicon Plasma

    NASA Astrophysics Data System (ADS)

    Aguirre, Evan; Siddiqui, Umair; McKee, John; Scime, Earl

    2015-11-01

    We report 2-dimensional, spatially resolved observations of a double layer in an expanding helicon plasma. These new measurements investigate the origins of previously observed multiple ion beam populations in the downstream plasma. We use Laser Induced Fluorescence (LIF) to measure the ion velocity distribution functions (IVDFs) of argon ions and neutrals both parallel and perpendicular to the background magnetic field and an rf-compensated Langmuir probe to determine the local plasma potential. These are the first multi-dimensional LIF measurements of ion acceleration in a current-free double layer and were obtained with a recently installed, internal scanning probe system in the HELIX-LEIA experimental facility. This work is supported by US National Science Foundation grant number PHY-1360278.

  4. Acoustic detection of resonance-enhanced multiphoton ionization for spatially resolved temperature measurement.

    PubMed

    Wu, Yue; Gragston, Mark; Zhang, Zhili

    2017-09-01

    In this Letter, acoustic detection of resonance-enhanced multiphoton ionization (A-REMPI) is characterized and used to measure spatially resolved O2 rotational temperature in air. The acoustic signal is generated using O2 REMPI in air and is detected by a single microphone operating within the audible range. Compared to electron number measurements by coherent microwave scattering, nonlinear light absorption and subsequent local pressure perturbation are captured by the microphone. A typical acoustic cycle of compression and rarefication of the acoustic wave is observed in the A-REMPI. Since the pressure perturbation can be regarded as close to thermodynamic equilibrium, the rotational temperature measured by A-REMPI is lower and closer to the realistic condition.

  5. Cellular organization and substructure measured using angle-resolved low-coherence interferometry.

    PubMed Central

    Wax, Adam; Yang, Changhuei; Backman, Vadim; Badizadegan, Kamran; Boone, Charles W; Dasari, Ramachandra R; Feld, Michael S

    2002-01-01

    We measure the organization and substructure of HT29 epithelial cells in a monolayer using angle-resolved low-coherence interferometry. This new technique probes cellular structure by measuring scattered light, as in flow cytometry, but offers an advantage in that the structure can be examined in situ, avoiding the need to disrupt the cell monolayer. We determine the size distribution of the cell nuclei by fitting measured light-scattering spectra to the predictions of Mie theory. In addition, we obtain information about the cellular organization and substructure by examining the spatial correlations within the monolayer. A remarkable finding is that the spatial correlations over small length scales take the form of an inverse power law, indicating the fractal nature of the packing of the subcellular structures. We also identify spatial correlations on a scale large compared with the size of a cell, indicating an overlying order within the monolayer. PMID:11916880

  6. Spectral and time-resolved measurements of marine oil pollution by YAG laser fluorosensor

    NASA Astrophysics Data System (ADS)

    Yamagishi, Susumu; Hitomi, Kazuo; Yamanouchi, Hiroshi

    1998-08-01

    This paper describes a compact imaging lidar system capable of detecting fluorescence of substances excited by the third harmonic generator of the YAG laser using CCD camera with gated image intensifier. The system mounted on a small airplane or ships will provide the spreading image of oil spills and classification of substances for clean-up operations. From image data of the water Raman scatters, we present a method to measure the extinction coefficients for the oil film thickness measurement. As the reference to interpret the data obtained in the field, the time-resolved fluorescence characteristics of fuel oils and industrial chemical substances were measured with a streak scope in the laboratory within the wavelength of 350 to 575 nm and with decay time up to 500 ns.

  7. Protein analysis by time-resolved measurements with an electro-switchable DNA chip

    PubMed Central

    Langer, Andreas; Hampel, Paul A.; Kaiser, Wolfgang; Knezevic, Jelena; Welte, Thomas; Villa, Valentina; Maruyama, Makiko; Svejda, Matej; Jähner, Simone; Fischer, Frank; Strasser, Ralf; Rant, Ulrich

    2013-01-01

    Measurements in stationary or mobile phases are fundamental principles in protein analysis. Although the immobilization of molecules on solid supports allows for the parallel analysis of interactions, properties like size or shape are usually inferred from the molecular mobility under the influence of external forces. However, as these principles are mutually exclusive, a comprehensive characterization of proteins usually involves a multi-step workflow. Here we show how these measurement modalities can be reconciled by tethering proteins to a surface via dynamically actuated nanolevers. Short DNA strands, which are switched by alternating electric fields, are employed as capture probes to bind target proteins. By swaying the proteins over nanometre amplitudes and comparing their motional dynamics to a theoretical model, the protein diameter can be quantified with Angström accuracy. Alterations in the tertiary protein structure (folding) and conformational changes are readily detected, and even post-translational modifications are revealed by time-resolved molecular dynamics measurements. PMID:23839273

  8. Highly resolved HSQC experiments for the fast and accurate measurement of homonuclear and heteronuclear coupling constants

    NASA Astrophysics Data System (ADS)

    Souza, Alexandre A.; Gil, Roberto R.; Parella, Teodor

    2017-09-01

    A number of J-upscaled NMR experiments are currently available to measure coupling constants along the indirect F1 dimension of a 2D spectrum. A major drawback is the limited F1 digital resolution that requires long acquisition times in order to achieve reasonably accurate measures. Here is shown how high levels of F1 digital resolution in a multiple-purpose HSQC experiment can be easily achieved by implementing a general J/δ-scaling strategy. In particular, a set of new J-resolved HSQC experiments is presented for a faster and much more accurate J determination in small molecules. Several options and practical aspects are discussed and exemplified by measuring the magnitude and/or the sign of several homo- and heteronuclear coupling constants in one shot.

  9. Characterizing the micro structure and kinetics of fast changing samples by simultaneous polarization measurements

    NASA Astrophysics Data System (ADS)

    Liao, Ran; He, Honghui; Zeng, Nan; Ma, Hui

    2015-03-01

    Taking accurate measurements of the state of polarization (SOP) is the key for the success of polarization sensitive techniques which can provide rich information on the microstructure of complex scattering media, such as biological tissues. For static or slow varying samples, SOP measurements can be achieved by time-sequential recoding of different polarization components controlled by rotating polarizers and wave plates or temporal modulation devices such as photoelastic modulators or liquid crystal variable retarders. When the sample is moving or changing its status quickly, polarization components recoded at different time may correspond to different SOPs, which can lead to significant errors in the final results. Simultaneous polarization measurements are necessary for probing such dynamic samples. In this paper, using the simultaneously recorded polarization components, we are able to mimic time sequential polarization schemes and evaluate the errors. The results show that the kinetics of the sample will affect the systematic error and an increase in the statistical errors of the measured degree of polarization (DOP). We change the kinetics of samples with different stirring speed, which is indicated by the characteristic time of the auto-correlation function. It is also demonstrated that the simultaneously recorded polarization components reveals additional information on the orientation of fibrous scatterers as well as their translation and rotation kinetics.

  10. Aircraft Measurements of Aerosol Phase Matrix Elements by the Polarized Imaging Nephelometer (Invited)

    NASA Astrophysics Data System (ADS)

    Dolgos, G.; Martins, J.; Espinosa, R.; Dubovik, O.; Beyersdorf, A. J.; Ziemba, L. D.; Hair, J. W.

    2013-12-01

    Aerosols have a significant impact on the radiative balance and water cycle of our planet through influencing atmospheric radiation. Remote sensing of aerosols relies on scattering phase matrix information to retrieve aerosol properties with frequent global coverage, the assumed phase matrices must be validated by measurements. At the Laboratory for Aerosols, Clouds and Optics (LACO) at the University of Maryland, Baltimore County (UMBC) we developed a new technique to directly measure the aerosol phase function (P11), the degree of linear polarization of the scattered light (-P12/P11), and the volume scattering coefficient (SCAT). We designed and built a portable instrument called the Polarized Imaging Nephelometer (PI-Neph), shown in Figure 1 (a). The PI-Neph successfully participated in dozens of flights of the NASA Development and Evaluation of satellite ValidatiOn Tools by Experimenters (DEVOTE) project and the Deep Convective Clouds and Chemistry (DC3) project and the January and February deployment of the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (Discover-AQ) mission. The ambient aerosol enters the PI-Neph through an inlet and the sample is illuminated by laser light (wavelength of 532 nm); the scattered light is imaged by a stationary wide field of view camera in the scattering angle range of 2° to 178° (in some cases stray light limited the scattering angle range to 3° to 176°). Data for P11, P12, and SCAT were taken every 12 seconds, example datasets from DEVOTE of P11 times SCAT are shown on Figure 1 (b). The talk will highlight results from the three field deployments and will show microphysical retrievals from the scattering data. The size distribution and the average complex refractive index of the ambient aerosol ensemble can be retrieved from the data by an algorithm similar to that of AERONET, as illustrated in Figure 1 (c). Particle sphericity can potentially be

  11. Comparison of vertical resolved leaf area index measurements in an open canopy savannah-type forest

    NASA Astrophysics Data System (ADS)

    Piayda, Arndt; Cuntz, Matthias; Dubbert, Maren; Werner, Christiane; Pereira, Joao S.

    2013-04-01

    Leaf area index (LAI) is a very important vegetation parameter in soil-vegetation-atmosphere exchange modeling. To represent the structure of ecosystems in vertically distributed modeling, vertical resolved LAI distributions as well as vertically and angular gap fraction (Pgap) distributions are needed, but rarely available. Additionally, former studies neglect woody plant components when using light interception or digital photography based methods for LAI or Pgap observations. This can lead to significantly biased results, particularly in semi-arid savannah-type ecosystems with low LAI values. The objective of this study is to compare three non-destructive LAI measurement techniques in a sparse savannah-type cork oak canopy in central Portugal in order to derive vertically resolved LAI as well as vertically and angular resolved Pgap. Since established canopy analyzers, such as the LAI-2000, rely on diffuse light conditions, which are rarely realized in semi-arid regions, we also employed fast, digital cover photography (DCP) working independently from diffuse light conditions. We used vertical and angular distributed DCP and applied object-based image analysis techniques to exclude woody plant components from Pgap estimation and LAI determination. We compared the results with vertically distributed LAI-2000 measurements, and additionally with vertical estimates based on easily measurable forest canopy parameters. We employed bootstrap resampling methods to determine the accuracy of all measurements depending on sample size. Leaf inclination measurements indicate planophile leaf orientation. Thus LAI was calculated with Pgap and the leaf inclination information. This led to a spatial averaged LAI of 0.52 +- 0.06 for DCP while LAI-2000 measurements resulted in 0.67 +- 0.07. Uncertainty bounds of LAI converge much faster with increasing sample size for the DCP than for the LAI-2000. This allows a more efficient sampling design, which is of great importance in

  12. Time-Resolved Single-State Measurements of the Electronic Structure of Isochoric Heated Copper

    SciTech Connect

    Nelson, A J; Dunn, J; Widmann, K; Ao, T; Ping, Y; Hunter, J; Ng, A

    2004-10-22

    Time-resolved x-ray photoelectron spectroscopy is used to probe the non-steady-state evolution of the valence band electronic structure of laser heated ultra-thin (50 nm) Cu. Single-shot x-ray laser induced time-of-flight photoelectron spectroscopy with picosecond time resolution is used in conjunction with optical measurements of the disassembly dynamics that have shown the existence of a metastable liquid phase in fs-laser heated Cu foils persisting 4-5 ps. This metastable phase is studied using a 527 nm wavelength 400 fs laser pulse containing 0.1-2.5 mJ laser energy focused in a large 500 x 700 {micro}m{sup 2} spot to create heated conditions of 0.07-1.8 x 10{sup 12} W cm{sup -2} intensity. Valence band photoemission spectra showing the changing occupancy of the Cu 3d level with heating are presented. These are the first picosecond x-ray laser time-resolved photoemission spectra of laser-heated ultra-thin Cu foil showing changes in electronic structure. The ultrafast nature of this technique lends itself to true single-state measurements of shocked and heated materials.

  13. Time resolved measurements of rigid fiber dispersion in near homogeneous isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Sabban, Lilach; Cohen, Asaf; van Hout, Rene; Empfl Environmental Multi-Phase Flow Laboratory Team

    2013-11-01

    Time resolved, planar particle image velocimetry (PIV, 3kHz) and two-orthogonal view, digital holographic cinematography (2kHz) was used to measure 3D fiber trajectories/orientation dynamics in near homogeneous isotropic air turbulence (HIT) with dilute suspended fibers. The PIV covered a field of view of 6 × 12 mm2 and the holography a volume of interest of 173 mm3, positioned at the center of the chamber. HIT (Reλ = 144) was generated in the center of a 403 cm3 cube by eight woofers mounted on each of its corners. Three different nylon fibers having a length of 0.5 mm and diameter of 10, 14 and 19 μm were released from the top of the chamber. Fibers had Stokes numbers of order one and are expected to accumulate in regions of low vorticity and settle along a path of local minimal drag. Fiber 3D trajectories/orientations have been obtained from the holography measurements and orientational/translational dispersion coefficients will be presented. In addition the flow field in the vicinity of tracked fibers has been resolved by the PIV, and results on fluid and fiber accelerations and position correlation with in-plane strain rate and out-of-plane vorticity will be presented.

  14. Optical characterisation of gold films for time-resolved reflectance thermometry measurements

    NASA Astrophysics Data System (ADS)

    Music, Jasmina; White, Thomas G.; Chapman, David J.; Eakins, Daniel E.

    2015-06-01

    The measurement of temperature represents a long-standing challenge within the field of high-pressure science. Recently, a promising time-resolved reflectance thermometry technique employing embedded gold films has been demonstrated. As an active diagnostic, reflectance thermometry is well suited for dynamic experiments generating temperatures below 1000K, where passive diagnostics such as pyrometry become infeasible due to the transient states created. A critical component of the reflectance thermometry technique is a robust optical characterisation of the gold films, decoupling the thermal and pressure contributions. Additionally, the optical properties of gold vary with both sample preparation and thermal history. With a view towards the development of a spatially-resolved reflectance thermometry technique for temperature measurement, we report the optical characterisation of a range of commercially available or deposited thin film gold samples. Reflectance spectroscopy was performed on the gold films as a function of temperature from ambient conditions to 400K, and as a function of pressure using a diamond anvil cell. The experimental data are fitted to a simple phenomenological Drude model paving the way for the calibrated films to be used during future dynamic experiments.

  15. Time resolved measurements of particle lift off from the wall in a turbulent water channel flow

    NASA Astrophysics Data System (ADS)

    van Hout, Rene; Rabencov, Boris; Arca, Javier

    2011-11-01

    Time-Resolved Particle Image Velocimetry (TR-PIV) and digital holography measurements were carried out in a dilute particle-laden flow tracking both Polystyrene Spheres (PS, ~0.583 mm, d+ ~ 10) as well as resolving the instantaneous velocity field of the turbulent flow. Measurements were performed in a closed loop, transparent, square channel facility (50x50 mm2) at 127.5cm from the inlet with bulk water velocity 0.3 m/s (Reh = 7353) and friction velocity 0.0174 m/s. Data were captured at 1 kHz, corresponding to a time scale 5x smaller than the flow's viscous scale. Single view digital holographic cinematography was used to track the 3D PS motion inside the VOI (17x17x50 mm3) including the wall bottom. TR-PIV in a vertical plane (29.3x29.3 mm2) oriented along the channel's centerline imaged PS together with flow tracers. Discrimination was based on their size difference. Instantaneous sequences of PS plotted on the spatial velocity, vorticity and swirling strength maps showed the effect of turbulent flow structures and resulting particle movement. Results are presented for particles that lift off from the bottom wall as a result of complex interaction with ejection and sweep motions.

  16. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    SciTech Connect

    Kraus, D.; Barbrel, B.; Falcone, R. W.; Vorberger, J.; Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M.; Gericke, D. O.; Wünsch, K.; Bachmann, B.; Döppner, T.; Bagnoud, V.; Blažević, A.; and others

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  17. Time resolved, near wall PIV measurements in a high Reynolds number turbulent pipe flow

    NASA Astrophysics Data System (ADS)

    Willert, C.; Soria, J.; Stanislas, M.; Amili, O.; Bellani, G.; Cuvier, C.; Eisfelder, M.; Fiorini, T.; Graf, N.; Klinner, J.

    2016-11-01

    We report on near wall measurements of a turbulent pipe flow at shear Reynolds numbers up to Reτ = 40000 acquired in the CICLoPE facility near Bologna, Italy. With 900 mm diameter and 110 m length the facility offers a well-established turbulent flow with viscous length scales ranging from y+ = 85 μ m at Reτ = 5000 to y+ = 11 μ m at Reτ = 40000 . These length scales can be resolved with a high-speed PIV camera at image magnification near unity. For the measurement the light of a high-speed, double-pulse laser is focused into a 300 μ m thin light sheet that is introduced radially into the pipe. The light scattered by 1 μ m water-glycerol droplet seeding is observed from the side by the camera via a thin high-aspect ratio mirror with a field of view covering 20mm in wall-normal and 5mm in stream-wise direction. Statistically converged velocity profiles could be achieved using 70000 samples per sequence acquired at low laser repetition rates (100Hz). Higher sampling rates of 10 kHz provide temporally coherent data from which frequency spectra can be derived. Preliminary analysis of the data shows a well resolved inner peak that grows with increasing Reynolds number. (Project funding through EuHIT - www.euhit.org)

  18. Time-resolved measurement technique for pulsed electron beam envelope basing on framing and streaking principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Yang, Zhi-Yong; Zhang, Huang; Wang, Yi

    2016-01-01

    The time-resolved electron beam envelope parameters, including cross sectional distribution and beam centroid position, are very important for the study of beam transmission characteristics in a magnetic field and for verifying the rationality of the magnetic field parameters employed. One kind of high time-resolved beam envelope measurement system has recently been developed, constituted of a high-speed framing camera and a streak camera. It can obtain three panoramic images of the beam and time continuous information along the given beam profile simultaneously. Recently obtained data has proved that several fast vibrations of the beam envelope along the diameter direction occur during the front and the tail parts of the electron beam. The vibration period is several nanoseconds. The effect of magnetic field on the electron beam is also observed and verified. Beam debugging experiments have proved that the existing beam transmission design is reasonable and viable. This beam envelope measurement system will establish a good foundation for beam physics research. Supported by National Natural Science Foundation of China (10675104, 11375162)

  19. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scatteringa)

    NASA Astrophysics Data System (ADS)

    Kraus, D.; Vorberger, J.; Helfrich, J.; Gericke, D. O.; Bachmann, B.; Bagnoud, V.; Barbrel, B.; Blažević, A.; Carroll, D. C.; Cayzac, W.; Döppner, T.; Fletcher, L. B.; Frank, A.; Frydrych, S.; Gamboa, E. J.; Gauthier, M.; Göde, S.; Granados, E.; Gregori, G.; Hartley, N. J.; Kettle, B.; Lee, H. J.; Nagler, B.; Neumayer, P.; Notley, M. M.; Ortner, A.; Otten, A.; Ravasio, A.; Riley, D.; Roth, F.; Schaumann, G.; Schumacher, D.; Schumaker, W.; Siegenthaler, K.; Spindloe, C.; Wagner, F.; Wünsch, K.; Glenzer, S. H.; Roth, M.; Falcone, R. W.

    2015-05-01

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  20. Measurements of the concentration of organic solutions by femtosecond time-resolved ERE-CARS

    NASA Astrophysics Data System (ADS)

    He, Ping; Wang, Ming; Wang, HuiLi; Fan, RongWei; Chen, DeYing; Yu, Xin; Wang, JiaLing; Jiang, YuGang

    2012-10-01

    A variant of all-resonant CARS named electronic-resonant enhancement CARS (ERE-CARS) is applied to measure the methanol-water solution concentration at room temperature. The measurements are performed using the ERE-CARS signal of the Raman vibrations near the C—H stretching modes (at 2835 and 2942 cm-1) in methanol. By changing the timing ( t>0) of the laser pulses of this non-degenerate four wave mixing technique, the concentration information based on the vibrational dynamics of the C—H bonds can be successfully detected as the frequency-spread dephasing rate during the first few hundred fs in the ERE-CARS signal with high sensitivity and accuracy. Femtosecond time-resolved ERE-CARS technique is applied to the concentration analysis of a mixture of the organic solution. This investigation indicates that femtosecond time-resolved ERE-CARS technique might be a powerful tool for real-time detection for solution concentration of different liquids.

  1. Time and Space Resolved Wall Temperature Measurements during Nucleate Boiling with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Yerramilli, Vamsee K.; Kim, Jungho

    2005-01-01

    The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work is to acquire time and space resolved temperature distributions under nucleate bubbles on a constant heat flux surface. This was performed using a microheater array with 100 micron resolution that allowed effectively simultaneous measurements of surface temperature while supplying a constant dissipative heat flux. This data is then correlated with high speed (> 1000Hz) visual recordings of the bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that a significant source of energy during bubble nucleation and initial growth is the superheated layer around the bubble. Bubble coalescence was not observed to decrease surface temperature as significantly as bubble departure from the surface. Since bubble departure is typically followed by a sharp increase in the heater surface temperature, it is surmised that the departing bubble effectively removes the superheated layer, allowing a high local heat transfer rate with the bulk fluid through transient conduction/micro-convection during rewetting.

  2. Spirally polarized beams for polarimetry measurements of deterministic and homogeneous samples

    NASA Astrophysics Data System (ADS)

    de Sande, Juan Carlos González; Santarsiero, Massimo; Piquero, Gemma

    2017-04-01

    The use of spirally polarized beams (SPBs) in polarimetric measurements of homogeneous and deterministic samples is proposed. Since across any transverse plane such beams present all possible linearly polarized states at once, the complete Mueller matrix of deterministic samples can be recovered with a reduced number of measurements and small errors. Furthermore, SPBs present the same polarization pattern across any transverse plane during propagation, and the same happens for the field propagated after the sample, so that both the sample plane and the plane where the polarization of the field is measured can be chosen at will. Experimental results are presented for the particular case of an azimuthally polarized beam and samples consisting of rotated retardation plates and linear polarizers.

  3. Fundamental measurement by in-line typed high-precision polarization lidar

    NASA Astrophysics Data System (ADS)

    Shiina, Tatsuo; Miyamoto, Masakazu; Umaki, Dai; Noguchi, Kazuo; Fukuchi, Tetsuo

    2008-12-01

    An in-line typed new concept lidar system for high precision polarization measurement was developed. A specially designed polarization-independent optical circulator, which was composed by Gran laser prisms and highly transparent Faraday rotators, was developed. Its isolation between the orthogonal polarizations was improved up to more than 30 dB. It is sufficient to detect small rotation of the polarization plane of the propagating beam caused by lightning discharges due to the Faraday effect. The rotation angle of the polarization plane is estimated by the differential detection between the orthogonal polarization components of the lidar echoes. The in-line optics enables near range measurement from the near range of >30 m with the narrow field of view of 0.17 mrad. The fundamental measurements of lidar echoes in near and far fields, and low cloud activities were examined.

  4. Magnetic Field Structure in Molecular Clouds by Polarization Measurements

    NASA Astrophysics Data System (ADS)

    Chen, W. P.; Su, B. H.; Eswaraiah, C.; Pandey, A. K.; Wang, C. W.; Lai, S. P.; Tamura, M.; Sato, S.

    2015-03-01

    We report on a program to delineate magnetic field structure inside molecular clouds by optical and infrared polarization observations. An ordered magnetic field inside a dense cloud may efficiently align the spinning dust grains to cause a detectable level of optical and near-infrared polarization of otherwise unpolarized background starlight due to dichroic extinction. The near-infrared polarization data were taken by SIRPOL mounted on IRSF in SAAO. Here we present the SIRPOL results in RCW 57, for which the magnetic field is oriented along the cloud filaments, and in Carina Nebula, for which no intrinsic polarization is detected in the turbulent environment. We further describe TRIPOL, a compact and efficient polarimer to acquire polarized images simultaneously at g', r', and i' bands, which is recently developed at Nagoya University for adaption to small-aperture telescopes. We show how optical observations probe the translucent outer parts of a cloud, and when combining with infrared observations probing the dense parts, and with millimeter and submillimeter observations to sutdy the central embedded protostar, if there is one, would yield the magnetic field structure on different length scales in the star-formation process.

  5. Vacuum-Based Time-Resolved Photoluminescence Measurement System Provides New Capability (Fact Sheet)

    SciTech Connect

    Not Available

    2011-11-01

    New measurement capability measures semiconductor minority-carrier lifetimes in conditions that simulate thin-film photovoltaic manufacturing environments. National Renewable Energy Laboratory (NREL) scientists have developed a new capability for measuring time-resolved photoluminescence (TRPL) in controlled environments, including under high vacuum and at elevated temperatures. This system enables the simulation of conditions in a thin-film photovoltaic (PV) manufacturing line. NREL's work in recent years has demonstrated a clear correlation between minority-carrier lifetime and thin-film PV device performance. Hence, the thin-film PV industry-both CIGS and CdTe-has a high level of interest for in-line metrology using NREL's TRPL system. The system, shown below, couples femtosecond laser pulses with optical fibers while avoiding spectral or temporal broadening over a wide range of wavelengths. The optics are designed to collect and couple the TRPL signal into the same fiber used to deliver the laser pulses. The capability is coupled into a high-vacuum chamber that can heat samples to 500 C or higher and expose them to reactive ambients. This tool will allow NREL to partner with industry to evaluate TRPL as a diagnostic at multiple stages of the manufacturing process and determine correlations to final module efficiency. The TRPL system has the potential to significantly improve manufacturing yield and throughput of current thin-film PV manufacturers. NREL developed a time-resolved photoluminescence (TRPL) system that can operate under high vacuum and at high temperatures. Thin-film PV performance can be better assessed because of its clear correlation with minority-carrier lifetime, which can be measured by NREL's TRPL system. Photovoltaic thin-film makers will be able to measure in-line TRPL at various stages of the manufacturing process, potentially leading to improved yield and throughput.

  6. Measurement of the stress state of materials by reflection of polarization-modulated light

    NASA Astrophysics Data System (ADS)

    Kniazkov, A. V.

    2017-02-01

    A method for measuring mechanical stresses of photoelastic materials from the difference between the reflection coefficients of orthogonally polarized light waves incident on the surface of the stressed medium is considered. Comparative results of measurements of the stress state of polymethylmethacrylate in the conventional transmission polarization optical scheme and by the proposed refraction method are presented. A case of normal light incidence is considered.

  7. Measurement of the tensor polarization in electron-deuteron elastic scattering

    SciTech Connect

    Schulze, M.E.; Beck, D.; Farkhondeh, M.; Gilad, S.; Goloskie, R.; Holt, R.J.; Kowalski, S.; Laszewski, R.M.; Leitch, M.J.; Moses, J.D.

    1984-02-20

    This paper reports the first measurement of the tensor polarization t/sub 20/ in e-d elastic scattering. The polarization of the recoil deuterons was measured for two values of momentum transfer, q = 1.74 and 2.03 fm/sup -1/, with a high-efficiency polarimeter. The results are in good agreement with reasonable models for the deuteron.

  8. In Situ, Time-Resolved Accelerator Grid Erosion Measurements in the NSTAR 8000 Hour Ion Engine Wear Test

    NASA Technical Reports Server (NTRS)

    Sovey, J.

    1997-01-01

    Time-resolved, in situ measurements of the charge exchange ion erosion pattern on the downstream face of the accelerator grid have been made during an ongoin wear test of the NSTAR 30 cm ion thruster.

  9. Polarization-sensitive optical coherence tomography measurements with different phase modulation amplitude when using continuous polarization modulation

    NASA Astrophysics Data System (ADS)

    Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

    2012-01-01

    We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.

  10. Hemodynamic measurements in deep brain tissues of humans by near-infrared time-resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroaki; Oda, Motoki; Yamaki, Etsuko; Suzuki, Toshihiko; Yamashita, Daisuke; Yoshimoto, Kenji; Homma, Shu; Yamashita, Yutaka

    2014-03-01

    Using near-infrared time-resolved spectroscopy (TRS), we measured the human head in transmittance mode to obtain the optical properties, tissue oxygenation, and hemodynamics of deep brain tissues in 50 healthy adult volunteers. The right ear canal was irradiated with 3-wavelengths of pulsed light (760, 795, and 835nm), and the photons passing through the human head were collected at the left ear canal. Optical signals with sufficient intensity could be obtained from 46 of the 50 volunteers. By analyzing the temporal profiles based on the photon diffusion theory, we successfully obtained absorption coefficients for each wavelength. The levels of oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), total hemoglobin (tHb), and tissue oxygen saturation (SO2) were then determined by referring to the hemoglobin spectroscopic data. Compared with the SO2 values for the forehead measurements in reflectance mode, the SO2 values of the transmittance measurements of the human head were approximately 10% lower, and tHb values of the transmittance measurements were always lower than those of the forehead reflectance measurements. Moreover, the level of hemoglobin and the SO2 were strongly correlated between the human head measurements in transmittance mode and the forehead measurements in the reflectance mode, respectively. These results demonstrated a potential application of this TRS system in examining deep brain tissues of humans.

  11. Comparisons of wind speed retrieval methods on C-band multi-polarization SAR measurements

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan; Wang, Difeng

    2014-10-01

    This paper compares the wind speed retrieval methods on C-band multi-polarization SAR measurements to find out the most appropriate one for each polarization data. The RADARSAT-2 SAR quad-polarization (VV+HH+VH+HV) data and NDBC buoy wind data were collocated. For VVpolarization, the retrieved wind speed are compared among four geophysical model function (GMF). For HH polarization, the retrieved wind speed are compared among four polarization ratio model (PR) based on CMOD5 GMF. For VH polarization, the retrieved wind speed are compared between two linear models. Comparisons show all of three polarimetric SAR data have the ability of retrieving wind speed. Based on the error analysis, the commendatory methods are proposed for each polarization.

  12. Polarization measurement of free electron laser pulses in the VUV generated by the variable polarization source FERMI

    NASA Astrophysics Data System (ADS)

    Finetti, P.; Allaria, E.; Diviacco, B.; Callegari, C.; Mahieu, B.; Viefhaus, J.; Zangrando, M.; De Ninno, G.; Lambert, G.; Ferrari, E.; Buck, J.; Ilchen, M.; Vodungbo, B.; Mahne, N.; Svetina, C.; Spezzani, C.; Di Mitri, S.; Penco, G.; Trovò, M.; Fawley, W. M.; Rebernik, P.; Gauthier, D.; Grazioli, C.; Coreno, M.; Ressel, B.; Kivimäki, A.; Mazza, T.; Glaser, L.; Scholz, F.; Seltmann, J.; Gessler, P.; Grünert, J.; De Fanis, A.; Meyer, M.; Knie, A.; Moeller, S. P.; Raimondi, L.; Capotondi, F.; Pedersoli, E.; Plekan, O.; Danailov, M.; Demidovich, A.; Nikolov, I.; Abrami, A.; Gautier, J.; Lüning, J.; Zeitoun, P.; Giannessi, L.

    2014-09-01

    FERMI, based at Elettra (Trieste, Italy) is the first free electron laser (FEL) facility operated for user experiments in seeded mode. Another unique property of FERMI, among other FEL sources, is to allow control of the polarization state of the radiation. Polarization dependence in the study of the interaction of coherent, high field, short-pulse ionizing radiation with matter, is a new frontier with potential in a wide range of research areas. The first measurement of the polarization-state of VUV light from a single-pass FEL was performed at FERMI FEL-1 operated in the 52 nm-26 nm range. Three different experimental techniques were used. The experiments were carried out at the end-station of two different beamlines to assess the impact of transport optics and provide polarization data for the end user. In this paper we summarize the results obtained from different setups. The results are consistent with each other and allow a general discussion about the viability of permanent diagnostics aimed at monitoring the polarization of FEL pulses.

  13. Polarized Imaging Nephelometer Scattering Measurements from the Winter of 2013 Discover-AQ Field Mission

    NASA Astrophysics Data System (ADS)

    Espinosa, R.; Martins, J.; Dolgos, G.; Dubovik, O.; Ziemba, L. D.; Beyersdorf, A. J.

    2013-12-01

    After greenhouse gases, aerosols are thought to have the largest contribution to the total radiative forcing of the atmosphere, but they are frequently cited as the single largest source of uncertainty among all anthropogenic radiative forcing components. Remote sensing allows global measurements of aerosol properties, however validation of these measurements are crucial, and their retrieval algorithms require climatological assumptions that must be first measured in situ. In situ instruments are also needed to supplement remote sensing measurements, which frequently have a relatively low spatial resolution, particularly when assessing surface air quality. The Laboratory for Aerosols, Clouds and Optics (LACO) at the University of Maryland Baltimore County (UMBC) has developed an instrument called the Polarized Imaging NEPHelometer (PI-Neph) to significantly aid in situ particle optical scattering measurements. The PI-Neph is based on a novel polar nephelometer design that uses a high-powered laser and wide field of view optical detection system (CCD camera) to measure the intensity of scattered laser light as a function of scattering angle. This allows for the measurement of scattering coefficient, phase function and polarized phase function over an angular range of 2 to 178 degrees with an angular resolution of less than half of a degree. This simple layout also permits the construction of an instrument that is compact enough to be flown on a variety of airborne platforms. PI-Neph measurements have been validated by a variety of methods since its completion in the fall of 2011. Measurements of mono-disperse polystyrene spheres have yielded results that are in close agreement with Mie theory, while scattering coefficient measurements made in parallel with commercially available integrating nephelometers from TSI have agreed to within 5%. The PI-Neph has successfully participated in several field experiments, most recently completing the January/February portion of

  14. Spatially resolved bolometric measurement and electron temperature measurement using diode arrays

    SciTech Connect

    Koguchi, H.; Shimada, T.; Asai, T.; Yagi, Y.; Hirano, Y.; Sakakita, H.

    2004-10-01

    In this article, the measurement system for the total radiation and electron temperature profiles to be installed in a reversed-field pinch machine, toroidal pinch experiment, RX [TPE-RX, R/a=1.72/0.45 m, Ipmeasure the plasma radiation and electron temperature profiles using three sets of diode arrays. Each array can measure radiation along 20 lines of sight and the radial profile of the radiation. One set of the arrays is used for the bolometric measurement in the range from visible light to soft x-ray. Two sets of the arrays are used for the soft-x ray and electron temperature measurements employing a double-filter method. We will use this system to investigate the plasma-wall interaction, radiation loss, and confinement properties in the core plasma region. We will extend the use of this system for tomographic analysis of electron temperature, a concept of which is also presented.

  15. Super-resolving power and tunneling as cases of "weak measurement"

    NASA Astrophysics Data System (ADS)

    Cacciari, Ilaria; Mugnai, Daniela; Ranfagni, Anedio

    2017-01-01

    A way for transferring the results obtained with super-gain antennas to optical systems, in order to increase their resolving power, was proposed by Toraldo di Francia in 1952. Recent experimental work performed in the microwave range has confirmed the correctness of the theoretical predictions, which could even seem to be in contradiction with the uncertainty principle. Here we propose a simple way to overcome this contradiction based on the "weak measurement" theory. This theory was originally proposed for quantum-mechanical systems, and represents a powerful tool for interpreting even a variety of classical situations. We demonstrate that the results obtained by means of electromagnetic analysis are confirmed by a "weak measurement" interpretation. Moreover, even the case of tunneling in the microwave range has been considered in the light of such a theory.

  16. Spatially resolved, in situ potential measurements through porous electrodes as applied to fuel cells.

    PubMed

    Hess, Katherine C; Epting, William K; Litster, Shawn

    2011-12-15

    We report the development and use of a microstructured electrode scaffold (MES) to make spatially resolved, in situ, electrolyte potential measurements through the thickness of a polymer electrolyte fuel cell (PEFC) electrode. This new approach uses a microfabricated apparatus to analyze the coupled transport and electrochemical phenomena in porous electrodes at the microscale. In this study, the MES allows the fuel cell to run under near-standard operating conditions, while providing electrolyte potential measurements at discrete distances through the electrode's thickness. Here we use spatial distributions of electrolyte potential to evaluate the effects of Ohmic and mass transport resistances on the through-plane reaction distribution for various operating conditions. Additionally, we use the potential distributions to estimate the ionic conductivity of the electrode. Our results indicate the in situ conductivity is higher than typically estimated for PEFC electrodes based on bulk polymer electrolyte membrane (PEM) conductivity.

  17. Spatially resolved measurements in a liquid metal flow with Lorentz force velocimetry

    NASA Astrophysics Data System (ADS)

    Heinicke, Christiane

    2013-06-01

    Velocity measurements inside metal melt flows are important for many laboratory and industrial applications in metallurgy but remain experimentally challenging. Only few techniques are viable for the measurement of mean flow velocities inside hot and aggressive materials. One of them is the previously studied electromagnetic contact-free Lorentz force velocimetry. However, the desire to resolve velocities spatially has not been satisfied so far. In the work presented here, spatial resolution is reached with a Lorentz force flow meter (LFF) by implementing a permanent magnet whose dimensions are significantly smaller than that of the flow under investigation. It is shown on a straight square duct flow that such a flow meter is capable of distinguishing obstacles in the flow and the resulting modified flow structures. The spatial resolution of the LFF is demonstrated to be at least on the order of 3 cm with a 1 cm magnet cube.

  18. Time-resolved and time-scale adaptive measures of spike train synchrony.

    PubMed

    Kreuz, Thomas; Chicharro, Daniel; Greschner, Martin; Andrzejak, Ralph G

    2011-01-30

    A wide variety of approaches to estimate the degree of synchrony between two or more spike trains have been proposed. One of the most recent methods is the ISI-distance which extracts information from the interspike intervals (ISIs) by evaluating the ratio of the instantaneous firing rates. In contrast to most previously proposed measures it is parameter free and time-scale independent. However, it is not well suited to track changes in synchrony that are based on spike coincidences. Here we propose the SPIKE-distance, a complementary measure which is sensitive to spike coincidences but still shares the fundamental advantages of the ISI-distance. In particular, it is easy to visualize in a time-resolved manner and can be extended to a method that is also applicable to larger sets of spike trains. We show the merit of the SPIKE-distance using both simulated and real data. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Spectrally-resolved measurement of concentrated light distributions for Fresnel lens concentrators.

    PubMed

    Besson, P; White, P McVey; Dominguez, C; Voarino, P; Garcia-Linares, P; Lemiti, M; Schriemer, H; Hinzer, K; Baudrit, M

    2016-01-25

    A test method that measures spectrally resolved irradiance distribution for a concentrator photovoltaic (CPV) optical system is presented. In conjunction with electrical I-V curves, it is a means to visualize and characterize the effects of chromatic aberration and nonuniform flux profiles under controllable testing conditions. The indoor characterization test bench, METHOD (Measurement of Electrical, Thermal and Optical Devices), decouples the temperatures of the primary optical element (POE) and the cell allowing their respective effects on optical and electrical performance to be analysed. In varying the temperature of the POE, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle and multi-junction current matching profiles can be quantified. This work presents the calibration procedures to accurately image the spectral irradiance distribution of a CPV system and a study of system behavior over lens temperature.

  20. The MRSt for time-resolved measurements of the neutron spectrum at the NIF

    NASA Astrophysics Data System (ADS)

    Frenje, J.; Gatu Johnson, M.; Li, C.; Seguin, F.; Petrasso, R.; Hilsabeck, T.; Kilkenny, J.; Bionta, R.; Cerjan, C.

    2015-11-01

    Information about the time evolution of inertial-confinement-fusion fuel assembly and hot-spot formation can be obtained with the next-generation Magnetic Recoil Spectrometer (MRS) for time-resolved measurements of the neutron spectrum. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometers for ICF applications, as it will provide simultaneously information about the burn history and ρR -Ti trajectory during burn. As the peak burn generally occurs before and after peak compression in failed and ignited implosions, respectively, an MRSt measurement of the relative timing of these events will be critical for assessing implosion dynamics. This work was supported in part by the U.S. DOE, LLNL and LLE.