On the nucleon–nucleon scattering phase shifts through ...
Indian Academy of Sciences (India)
The constructed equivalent Yamaguchi potential fits the S-wave scattering phase shifts from. 0 to 300 MeV. At the same time they have also parametrized Hulthen potential to fit the deuteron binding energy and S-wave scattering length. Since its appearance, the. Pramana – J. Phys., Vol. 81, No. 6, December 2013. 959 ...
On the nucleon–nucleon scattering phase shifts through ...
Indian Academy of Sciences (India)
By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and ...
Nonuniqueness of the Phase Shift in Central Scattering due to Monodromy
Dullin, Holger R.; Waalkens, Holger
2008-01-01
Scattering at a central potential is completely characterized by the phase shifts which are the differences in phase between outgoing scattered and unscattered partial waves. In this Letter, it is shown that, for 2D scattering at a repulsive central potential, the phase shift cannot be uniquely
Scattering phase shift for elastic two pion scattering and the rho resonance in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Gutzwiller, Simone
2012-10-08
In this thesis we use lattice QCD to compute scattering phase shifts for elastic two-pion scattering in the isospin I=1 channel. Using Luescher's formalism, we derive the scattering phase shifts for different total momenta of the two-pion system in a non-rest frame. Furthermore we analyse the symmetries of the non-rest frame lattices and construct 2-pion and rho operators transforming in accordance with these symmetries. The data was collected for a 32{sup 3} x 64 and a 40{sup 3} x 64 lattice with N{sub f}=2 clover improved Wilson fermions at a pion mass around 290 MeV and a lattice spacing of about 0.072 fm.
Li, Yongqian; An, Qi; Li, Xiaojuan; Zhang, Lixin
2017-05-01
A high-accuracy Brillouin frequency shift (BFS) measurement system for vector Brillouin optical time-domain analysis-based temperature sensor is proposed, in which double sideband modulation is used and the stimulated Brillouin scattering (SBS) gain and loss processes work together to generate a superimposed SBS phase-shift spectrum. The measurement principle is analyzed by mathematical modeling and the proof-of-concept experiment is performed by using a 100-m long standard single-mode fiber. The theoretical and experimental results reveal that the temperature sensitivity of BFS obtained from the measured SBS phase-shift spectrum is 1.059 MHz/°C, and the measurement error of temperature is only half that in traditional single sideband-based system, which indicates that the proposed technique can realize high-accuracy temperature measurement and have huge potential in the field of long-distance and high-accuracy sensing.
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Huber, H.; Lun, D.R.; Allen, L.J.; Amos, K.
1997-06-01
The requirements that the scattering functions for quantal scattering at energies below the first inelastic threshold be unitary and analytic have been used to establish a process that gives the complex scattering amplitudes from differential cross sections. From those amplitudes scattering phase shifts have been deduced by Legendre integration. The effects of the natural ambiguity of the phase of the scattering phase shifts have been deduced by Legendre integration. The effects of the natural ambiguity of the phase of the scattering amplitude, under conditions for which uniqueness and (numerical) stability of solutions are not assured, also have been developed to specify the scattering phase shifts can give stable nonspurious results. The scattering of electrons from He atoms for incident energies ranging from 1.5 to 19 eV are considered as an example of the procedure. Phase shift analyses of that data have been made with a variety of other techniques to allow a comparative study of these results and of sets with which are associated fits to cross sections that are statistically significant. 18 refs., 2 tabs., 8 figs.
Solution of the Cox-Thompson inverse scattering problem using finite set of phase shifts
Apagyi, B; Scheid, W
2003-01-01
A system of nonlinear equations is presented for the solution of the Cox-Thompson inverse scattering problem (1970 J. Math. Phys. 11 805) at fixed energy. From a given finite set of phase shifts for physical angular momenta, the nonlinear equations determine related sets of asymptotic normalization constants and nonphysical (shifted) angular momenta from which all quantities of interest, including the inversion potential itself, can be calculated. As a first application of the method we use input data consisting of a finite set of phase shifts calculated from Woods-Saxon and box potentials representing interactions with diffuse or sharp surfaces, respectively. The results for the inversion potentials, their first moments and asymptotic properties are compared with those provided by the Newton-Sabatier quantum inversion procedure. It is found that in order to achieve inversion potentials of similar quality, the Cox-Thompson method requires a smaller set of phase shifts than the Newton-Sabatier procedure.
Adas, Sonya; Meyers, Lisa; Caragiu, Mellita
2009-04-01
In a typical Low-Energy Electron Diffraction (LEED) investigation of a crystal surface, the electrons probing the surface are scattered by the atoms in the sample. The scattering process introduces phase shifts in the waves associated to the incoming electrons. An investigation of how these phase shifts influence the results of a LEED calculation are presented for the fairly complicated Cu(511) stepped surface. The phase shifts have been calculated using the Barbieri/Van Hove Phase Shift Package. The phase shifts considered correspond to copper atoms arranged in various planes of the copper crystal: (100), (111), and a close approximation of the (511) plane.
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Gashi, A.; Matsinos, E.; Oades, G.C. E-mail: gco@ifa.au.dk; Rasche, G.; Woolcock, W.S
2001-04-09
We calculate for the s-, p{sub 1/2}- and p{sub 3/2}-waves the electromagnetic corrections which must be subtracted from the nuclear phase shifts obtained from the analysis of low-energy {pi}{sup +}p elastic scattering data, in order to obtain hadronic phase shifts. The calculation uses relativised Schroedinger equations containing the sum of an electromagnetic potential and an effective hadronic potential. We compare our results with those of previous calculations and estimate the uncertainties in the corrections.
Electromagnetic corrections to the hadronic phase shifts in low energy pi sup + p elastic scattering
Gashi, A; Oades, G C; Rasche, G; Woolcock, W S
2001-01-01
We calculate for the s-, p sub 1 sub / sub 2 - and p sub 3 sub / sub 2 -waves the electromagnetic corrections which must be subtracted from the nuclear phase shifts obtained from the analysis of low-energy pi sup + p elastic scattering data, in order to obtain hadronic phase shifts. The calculation uses relativised Schroedinger equations containing the sum of an electromagnetic potential and an effective hadronic potential. We compare our results with those of previous calculations and estimate the uncertainties in the corrections.
An energy-dependent phase shift analysis of low-energy proton-deuteron elastic scattering
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Black, T.-C.; Karwowski, H.-J.; Ludwig, E.-J. [North Carolina Univ., Chapel Hill (United States). Dept. of Physics and Astronomy]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Kievsky, A.; Rosati, S.; Viviani, M. [Istituto Nazionale di Fisica Nucleare, Piazza Torricelli 2, 56100 Pisa (Italy)
1998-03-02
An energy dependent phase shift analysis of p+d elastic scattering below the deuteron breakup threshold has been conducted. The phases are fit directly to the data with a Monte Carlo Markov chain algorithm after being sampled from a parameter space which is constrained to satisfy the Coulomb-modified effective range expansion. The mixing parameters are required to obey analyticity constraints. The overall fit in the preliminary analysis reported here was satisfactory, giving a {chi}{sup 2}/datum of about 2.5. The analysis indicates the existence of a singularity in the spin-doublet S-wave effective range function. The inferred value of the quartet S-wave scattering length is in excellent quantitative agreement with theoretical predictions. Small changes to the theoretical P-wave phase shifts and somewhat larger changes to the theoretical J=1/2 mixing parameters are required to reproduce the p+d data. (orig.) 9 refs.
Phase-shift analysis of low-energy {pi}{sup +}/-p elastic-scattering data
Energy Technology Data Exchange (ETDEWEB)
Matsinos, E. [Varian Medical Systems Imaging Laboratory GmbH, Taefernstrasse 7, CH-5405 Baden-Daettwil (Switzerland)]. E-mail: evangelos.matsinos@varian.com; Woolcock, W.S. [Department of Theoretical Physics, IAS, Australian National University, Canberra, ACT 0200 (Australia); Oades, G.C. [Institute of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Rasche, G. [Institut fuer Theoretische Physik der Universitaet, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland); Gashi, A. [Mediscope AG, Alfred Escher-Str. 27, CH-8002 Zurich (Switzerland)
2006-10-30
Using electromagnetic corrections previously calculated by means of a potential model, we have made a phase-shift analysis of the {pi}{sup +}/-p elastic-scattering data up to a pion laboratory kinetic energy of 100 MeV. The hadronic interaction was assumed to be isospin invariant. We found that it was possible to obtain self-consistent databases by removing very few measurements. A pion-nucleon model, based on s- and u-channel diagrams with N and {delta} in the intermediate states, and {sigma} and {rho} t-channel exchanges, was fitted to the elastic-scattering database obtained after the removal of the outliers. The model-parameter values showed an impressive stability when the database was subjected to different criteria for the rejection of experiments. Our result for the pseudovector {pi}NN coupling constant (in the standard form) is 0.0733+/-0.0014. The six hadronic phase shifts up to 100 MeV are given in tabulated form. We also give the values of the s-wave scattering lengths and the p-wave scattering volumes. Big differences in the s-wave part of the interaction were observed when comparing our hadronic phase shifts with those of the current GWU solution. We demonstrate that the hadronic phase shifts obtained from the analysis of the elastic-scattering data cannot reproduce the measurements of the {pi}{sup -}p charge-exchange reaction, thus corroborating past evidence that the hadronic interaction violates isospin invariance. Assuming the validity of the result obtained within the framework of chiral perturbation theory, that the mass difference between the u- and the d-quark has only a very small effect on the isospin invariance of the purely hadronic interaction, the isospin-invariance violation revealed by the data must arise from the fact that we are dealing with a hadronic interaction which still contains residual effects of electromagnetic origin.
Ramírez Suárez, O. L.; Sparenberg, J.-M.
2017-09-01
We introduce a simplified effective-range function for charged nuclei, related to the modified K matrix but differing from it in several respects. Negative-energy zeros of this function correspond to bound states. Positive-energy zeros correspond to resonances and "echo poles" appearing in elastic-scattering phase-shifts, while its poles correspond to multiple-of-π phase shifts. Padé expansions of this function allow one to parametrize phase shifts on large energy ranges and to calculate resonance and bound-state properties in a very simple way, independently of any potential model. The method is first tested on a d -wave 12C+α potential model. It is shown to lead to a correct estimate of the subthreshold-bound-state asymptotic normalization constant (ANC) starting from the elastic-scattering phase shifts only. Next, the 12C+α experimental p -wave and d -wave phase shifts are analyzed. For the d wave, the relatively large error bars on the phase shifts do not allow one to improve the ANC estimate with respect to existing methods. For the p wave, a value agreeing with the 12C(6Li,d )16O transfer-reaction measurement and with the recent remeasurement of the 16Nβ -delayed α decay is obtained, with improved accuracy. However, the method displays two difficulties: the results are sensitive to the Padé-expansion order and the simplest fits correspond to an imaginary ANC, i.e., to a negative-energy "echo pole," the physical meaning of which is still debatable.
Perim de Faria, Julia; Bundke, Ulrich; Onasch, Timothy B.; Freedman, Andrew; Petzold, Andreas
2016-04-01
The necessity to quantify the direct impact of aerosol particles on climate forcing is already well known; assessing this impact requires continuous and systematic measurements of the aerosol optical properties. Two of the main parameters that need to be accurately measured are the aerosol optical depth and single scattering albedo (SSA, defined as the ratio of particulate scattering to extinction). The measurement of single scattering albedo commonly involves the measurement of two optical parameters, the scattering and the absorption coefficients. Although there are well established technologies to measure both of these parameters, the use of two separate instruments with different principles and uncertainties represents potential sources of significant errors and biases. Based on the recently developed cavity attenuated phase shift particle extinction monitor (CAPS PM_{ex) instrument, the CAPS PM_{ssa instrument combines the CAPS technology to measure particle extinction with an integrating sphere capable of simultaneously measuring the scattering coefficient of the same sample. The scattering channel is calibrated to the extinction channel, such that the accuracy of the single scattering albedo measurement is only a function of the accuracy of the extinction measurement and the nephelometer truncation losses. This gives the instrument an accurate and direct measurement of the single scattering albedo. In this study, we assess the measurements of both the extinction and scattering channels of the CAPS PM_{ssa through intercomparisons with Mie theory, as a fundamental comparison, and with proven technologies, such as integrating nephelometers and filter-based absorption monitors. For comparison, we use two nephelometers, a TSI 3563 and an Aurora 4000, and two measurements of the absorption coefficient, using a Particulate Soot Absorption Photometer (PSAP) and a Multi Angle Absorption Photometer (MAAP). We also assess the indirect absorption coefficient
Scattering phase-shift formulas for mesons and baryons in elongated boxes
Lee, Frank X.; Alexandru, Andrei
2017-09-01
We derive Lüscher phase-shift formulas for two-particle states in boxes elongated in one of the dimensions. Such boxes offer a cost-effective way of varying the relative momentum of the particles. Boosted states in the elongated direction, which allow wider access to energies, are also considered. The formulas for the various scenarios (moving and zero-momentum states in cubic and elongated boxes) are compared, and relations between them are clarified. The results are applicable to a wide set of meson-meson and meson-baryon elastic scattering processes, with the two-particle system having equal or unequal masses.
Fukutake, Naoki
2016-03-01
Coherent Raman scattering microspectroscopy, which includes coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microspectroscopy, permits label-free hyperspectral imaging. We report the theoretical study of the phase-shift effect of the impulse response function on the spectral and image-forming properties of coherent Raman scattering microspectroscopy. We show that the spectrum and image are influenced by not only the NA of objective for excitation (NA(ex)) but also that for signal collection (NA(col)), in association with the phase-shift effect. We discuss that, under the condition NA(ex)≠NA(col), both the spectrum and the image become deformed by the phase-shift effect, which can be applied to the direct measurement of the imaginary part of the nonlinear susceptibility in CARS spectroscopy. We point out that, even in SRS microscopy, the nonresonant background can contribute to the image formation and cause the artifact in the image.
Finite volume treatment of pi pi scattering and limits to phase shifts extraction from lattice QCD
Albaladejo, M; Oset, E; Rios, G; Roca, L
2012-01-01
We study theoretically the effects of finite volume for pipi scattering in order to extract physical observables for infinite volume from lattice QCD. We compare three different approaches for pipi scattering (lowest order Bethe-Salpeter approach, N/D and inverse amplitude methods) with the aim to study the effects of the finite size of the box in the potential of the different theories, specially the left-hand cut contribution through loops in the crossed t,u-channels. We quantify the error made by neglecting these effects in usual extractions of physical observables from lattice QCD spectra. We conclude that for pipi phase-shifts in the scalar-isoscalar channel up to 800 MeV this effect is negligible for box sizes bigger than 2.5m_pi^-1 and of the order of 5% at around 1.5-2m_pi^-1. For isospin 2 the finite size effects can reach up to 10% for that energy. We also quantify the error made when using the standard Luscher method to extract physical observables from lattice QCD, which is widely used in the lite...
Tables of phase shifts and experimental observables for p-/sup 4/He elastic scattering. [0 to 17 MeV
Energy Technology Data Exchange (ETDEWEB)
Dodder, D.C.; Hale, G.M.; Jarmie, N.; Witte, K.
1976-06-01
These tables contain calculated phase shifts and experimental observables for p-/sup 4/He elastic scattering from 0 to 17 MeV. The phase shifts are given at intervals suitable for linear interpolation.
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Wang, A.Z.F.
1977-11-01
The physical and chemical properties of metastable rare gas atoms are discussed and summarized. This is followed by a detailed examination of the various possible pathways whereby the metastable's excess electronic energy can be dissipated. The phenomenon of chemi-ionization is given special emphasis, and a theoretical treatment based on the use of complex (optical) potential is presented. This is followed by a discussion on the unique advantages offered by elastic differential cross section measurements in the apprehension of the fundamental forces governing the ionization process. The methodology generally adopted to extract information about the interaction potential for scattering data is also systematically outlined. Two widely studied chemi-ionization systems are then closely examined in the light of accurate differential cross section measurements obtained in this work. The first system is He(2/sup 3/S) + Ar for which one can obtain an interaction potential which is in good harmony with the experimental results of other investigators. The validity of using the first-order semiclassical approximation for the phase shifts calculation in the presence of significant opacities is also discussed. The second reaction studied is He*+D/sub 2/ for which measurements were made on both spin states of the metastable helium. A self-consistent interaction potential is obtained for the triplet system, and reasons are given for not being able to do likewise for the singlet system. The anomalous hump proposed by a number of laboratories is analyzed. Total elastic and ionization cross sections as well as rate constants are calculated for the triplet case. Good agreement with experimental data is found. Finally, the construction and operation of a high power repetitively pulsed nitrogen laser pumped dye laser system is described in great details. Details for the construction and operation of a flashlamp pumped dye laser are likewise given.
Marston, Philip L; Zhang, Likun
2017-05-01
When investigating the radiation forces on spheres in complicated wave-fields, the interpretation of analytical results can be simplified by retaining the s-function notation and associated phase shifts imported into acoustics from quantum scattering theory. For situations in which dissipation is negligible, as taken to be the case in the present investigation, there is an additional simplification in that partial-wave phase shifts become real numbers that vanish when the partial-wave index becomes large and when the wave-number-sphere-radius product vanishes. By restricting attention to monopole and dipole phase shifts, transitions in the axial radiation force for axisymmetric wave-fields are found to be related to wave-field parameters for traveling and standing Bessel wave-fields by considering the ratio of the phase shifts. For traveling waves, the special force conditions concern negative forces while for standing waves, the special force conditions concern vanishing radiation forces. An intermediate step involves considering the functional dependence on phase shifts. An appendix gives an approximation for zero-force plane standing wave conditions. Connections with early investigations of acoustic levitation are mentioned and some complications associated with viscosity are briefly noted.
Omelaenko, A S
2002-01-01
From the data of the P sub 3 sub 3 amplitude of several pi N elastic-scattering analyses the DELTA(1232)-pole characteristics are determined in the framework of a resonance model. The approximate analytical expression connecting the residue with a background value is obtained. The estimations have corroborated the small value of the non-resonant part of the phase shift being essentially different from the one calculated by the current algebra and the effective Lagrangian theory. This contradiction is removed in a modified variant of the resonance model developed by taking into account the quadratic term in the expansion of the Jost function in a series at the pole point. In comparison with the traditional model the pole coordinates and phase shift of the residue have been changed a little but its absolute value has increased by about 20%
Batley, J Richard; Kalmus, George Ernest; Lazzeroni, C; Munday, D J; Slater, M W; Wotton, S A; Arcidiacono, R; Bocquet, G; Cabibbo, Nicola; Ceccucci, A; Cundy, Donald C; Falaleev, V; Fidecaro, Maria; Gatignon, L; Gonidec, A; Kubischta, Werner; Norton, A; Maier, A; Patel, M; Peters, A; Balev, S; Frabetti, P L; Goudzovski, E; Khristov, P Z; Kekelidze, V; Kozhuharov, V; Litov, L; Madigozhin, D T; Marinova, E; Molokanova, N; Polenkevich, I; Potrebenikov, Yu; Stoynev, S; Zinchenko, A; Monnier, E; Swallow, E; Winston, R; Rubin, P; Walker, A; Baldini, W; Cotta-Ramusino, A; Dalpiaz, P; Damiani, C; Fiorini, M; Gianoli, A; Martini, M; Petrucci, F; Savrié, M; Scarpa, M; Wahle, H; Bizzeti, A; Calvetti, M; Celeghini, E; Iacopini, E; Lenti, M; Martelli, F; Ruggiero, G; Veltri, M; Behler, M; Eppard, K; Kleinknecht, K; Marouelli, P; Masetti, L; Moosbrugger, U; Morales-Morales, C; Renk, B; Wache, M; Wanke, R; Winhart, A; Coward, D; Dabrowski, A; Fonseca-Martin, T; Shieh, M; Szleper, M; Velasco, M; Wood, M D; Anzivino, Giuseppina; Cenci, P; Imbergamo, E; Nappi, A; Pepé, M; Petrucci, M C; Piccini, M; Raggi, M; Valdata-Nappi, M; Cerri, C; Collazuol, G; Costantini, F; Di Lella, L; Doble, N; Fantechi, R; Fiorini, L; Giudici, S; Lamanna, G; Mannelli, I; Michetti, A; Pierazzini, G; Sozzi, M; Bloch-Devaux, B; Cheshkov, C; Chèze, J B; De Beer, M; Derré, J; Marel, Gérard; Mazzucato, E; Peyaud, B; Vallage, B; Holder, M; Ziolkowski, M; Bifani, S; Biino, C; Cartiglia, N; Clemencic, M; Goy-Lopez, S; Marchetto, F; Dibon, Heinz; Jeitler, Manfred; Markytan, Manfred; Mikulec, I; Neuhofer, G; Widhalm, L
2008-01-01
We report results from a new measurement of the K_{e4} decay K^{+-} -> \\pi^+ \\pi^- e^{+-} v by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F, G, H) and pi pi scattering phase shift delta00-delta11 have been measured using a model-independent method and their variation with the pi pi mass has been investigated. Thanks to a sizeable acceptance at large pi pi mass, a low background and a very good resolution, an improved accuracy (+- 0.006 stat +- 0.002 syst), a factor two better than in the previous measurement, is reached when extracting the pi pi scattering length a00.
Orlov, Yu. V.; Irgaziev, B. F.; Nabi, Jameel-Un
2017-08-01
A new algorithm for the asymptotic nuclear coefficients calculation, which we call the Δ method, is proved and developed. This method was proposed by Ramírez Suárez and Sparenberg (arXiv:1602.04082.) but no proof was given. We apply it to the bound state situated near the channel threshold when the Sommerfeld parameter is quite large within the experimental energy region. As a result, the value of the conventional effective-range function Kl(k2) is actually defined by the Coulomb term. One of the resulting effects is a wrong description of the energy behavior of the elastic scattering phase shift δl reproduced from the fitted total effective-range function Kl(k2) . This leads to an improper value of the asymptotic normalization coefficient (ANC) value. No such problem arises if we fit only the nuclear term. The difference between the total effective-range function and the Coulomb part at real energies is the same as the nuclear term. Then we can proceed using just this Δ method to calculate the pole position values and the ANC. We apply it to the vertices 4He+12C ↔16O and 3He+4He↔7Be . The calculated ANCs can be used to find the radiative capture reaction cross sections of the transfers to the 16O bound final states as well as to the 7Be.
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Arnecke, Florian
2009-01-19
In this thesis we have studied the threshold behaviour od scattering phases in attactive, singular potentials proportional to -1/r{sup {alpha}}, {alpha}>2, in two and three dimensions. Total absorption on the surface was described by incoming boundary condition in form of WKB waves, so that the scattering phase {delta}(k) is because of the particle loss a complex quantity and the S matrix no longer unitary. As application example we use the scattering behaviour of ultracold atoms on an absorbing sphere. The parameters were so chosen that they correspond to those of metastable helium (2{sup 3}S) atoms respectively sodium atoms in the ground state and a radius of the sphere of 200 respectively 2000 a. u. The final chapter presents a survey about the scattering on a circularly symmetric potential in two dimensions.
Instantaneous phase shifting deflectometry.
Trumper, Isaac; Choi, Heejoo; Kim, Dae Wook
2016-11-28
An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone ® 6. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using Fourier techniques. Along with experimental data showing the capabilities of the instantaneous deflectometry system, a quantitative comparison with the Fourier transform profilometry method, which is a distinct phase measuring method from the phase shifting approach, is presented. Sources of error, nonlinear color-multiplexing induced error correction, and hardware limitations are discussed.
Guo, Zhi-Hui; Liu, Liuming; Meißner, Ulf-G.; Oller, J. A.; Rusetsky, A.
2017-03-01
We investigate the a0(980 ) resonance within chiral effective field theory through a three-coupled-channel analysis, namely, π η , K K ¯, and π η'. A global fit to recent lattice finite-volume energy levels from π η scattering and relevant experimental data on a π η event distribution and the γ γ →π η cross section is performed. Both the leading and next-to-leading-order analyses lead to similar and successful descriptions of the finite-volume energy levels and the experimental data. However, these two different analyses yield different π η scattering phase shifts for the physical masses for the π , K , η , and η' mesons. The inelasticities, the pole positions in the complex energy plane, and their residues are calculated both for unphysical and physical meson masses.
New high statistics measurement of Ke4 decay form factors and ππ scattering phase shifts
Batley, J. R.; Culling, A. J.; Kalmus, G.; Lazzeroni, C.; Munday, D. J.; Slater, M. W.; Wotton, S. A.; Arcidiacono, R.; Bocquet, G.; Cabibbo, N.; Ceccucci, A.; Cundy, D.; Falaleev, V.; Fidecaro, M.; Gatignon, L.; Gonidec, A.; Kubischta, W.; Norton, A.; Maier, A.; Patel, M.; Peters, A.; Balev, S.; Frabetti, P. L.; Goudzovski, E.; Hristov, P.; Kekelidze, V.; Kozhuharov, V.; Litov, L.; Madigozhin, D.; Marinova, E.; Molokanova, N.; Polenkevich, I.; Potrebenikov, Y.; Stoynev, S.; Zinchenko, A.; Monnier, E.; Swallow, E.; Winston, R.; Rubin, P.; Walker, A.; Baldini, W.; Cotta Ramusino, A.; Dalpiaz, P.; Damiani, C.; Fiorini, M.; Gianoli, A.; Martini, M.; Petrucci, F.; Savrié, M.; Scarpa, M.; Wahl, H.; Bizzeti, A.; Calvetti, M.; Celeghini, E.; Iacopini, E.; Lenti, M.; Martelli, F.; Ruggiero, G.; Veltri, M.; Behler, M.; Eppard, K.; Kleinknecht, K.; Marouelli, P.; Masetti, L.; Moosbrugger, U.; Morales Morales, C.; Renk, B.; Wache, M.; Wanke, R.; Winhart, A.; Coward, D.; Dabrowski, A.; Fonseca Martin, T.; Shieh, M.; Szleper, M.; Velasco, M.; Wood, M. D.; Anzivino, G.; Cenci, P.; Imbergamo, E.; Nappi, A.; Pepe, M.; Petrucci, M. C.; Piccini, M.; Raggi, M.; Valdata-Nappi, M.; Cerri, C.; Collazuol, G.; Costantini, F.; Dilella, L.; Doble, N.; Fantechi, R.; Fiorini, L.; Giudici, S.; Lamanna, G.; Mannelli, I.; Michetti, A.; Pierazzini, G.; Sozzi, M.; Bloch-Devaux, B.; Cheshkov, C.; Chèze, J. B.; de Beer, M.; Derré, J.; Marel, G.; Mazzucato, E.; Peyaud, B.; Vallage, B.; Holder, M.; Ziolkowski, M.; Bifani, S.; Biino, C.; Cartiglia, N.; Clemencic, M.; Goy Lopez, S.; Marchetto, F.; Dibon, H.; Jeitler, M.; Markytan, M.; Mikulec, I.; Neuhofer, G.; Widhalm, L.
2008-04-01
We report results from a new measurement of the Ke4 decay K±→π+π-e±ν by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670 000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F,G,H) and ππ phase difference (δ=δs-δp) have been measured in ten independent bins of the ππ mass spectrum to investigate their variation. A sizeable acceptance at large ππ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the ππ scattering lengths a0 0 and a0 2. Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (a0 0,a0 2): a0 0=0.233±0.016stat±0.007syst,a0 2=-0.0471±0.011stat±0.004syst. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory.
Energy Technology Data Exchange (ETDEWEB)
Franz Gross; Alfred Stadler
2008-02-11
Using the covariant spectator theory (CST), we present two one boson exchange kernels that have been successfully adjusted to fit the 2007 world $np$ data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a chi2/N = 1.06. The other model (designated WJC-2) has only 15 parameters and fits with a chi2/N = 1.12. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire data base, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 data base is presented.
Phase-shifted response of plasmonic nanostructures
DEFF Research Database (Denmark)
Nerkararyan, Khachatur V.; Yezekyan, Torgom S.; Bozhevolnyi, Sergey I.
2017-01-01
We analyze the dynamics of a quantum dipole emitter (QDE) illuminated by a resonant electromagnetic field and placed close to a metal nanostructure, whose response to the incident field is phase shifted by 3π/2 (-π/2). It is found that, due to the phase shift in a field scattered by the nanostruc......We analyze the dynamics of a quantum dipole emitter (QDE) illuminated by a resonant electromagnetic field and placed close to a metal nanostructure, whose response to the incident field is phase shifted by 3π/2 (-π/2). It is found that, due to the phase shift in a field scattered...... by the nanostructure (and acting on the QDE along with the incident field), QDE dynamics is characterized by a fast QDE transition to the excited state followed by relaxation to a stable superposition (of the excited and ground states) with a close to 1 probability of the QDE to be found in the excited state. We...
Energy Technology Data Exchange (ETDEWEB)
Cha, Moon Hoe [Kangwon National University, Chunchon (Korea, Republic of)
2006-10-15
A phase shift analysis for the {sup 12}C+{sup 12}C system in the range E{sub lab} = 240 to 2400 MeV is performed by using the parametrized phase shift model. The diffractive oscillatory structures observed at forward angles are explained due to the strong interference between the near- and the far-side scattering amplitudes. The negative minima in the deflection curves occurring at angles {theta}{sub nucl} =- 49.92 .deg. {approx} -0.51 .deg. corresponding to energies E{sub lab} = 240 {approx} 2400 MeV, respectively, are shown to indicate the presences of nuclear rainbows. The partial reaction cross-sections are found to increase linearly up to some peak values and thereafter to decrease quadratically to zero. The peak values of partial reaction cross-section are shown to become smaller as the incident energy increases. Since the strong absorption radius becomes smaller as the incident energy decreases, the nuclear density distributions of the {sup 12}C+{sup 12}C system at higher energies are shown to have more overlaps than those at lower energies.
Discrete ambiguities in phase-shift analysis
Heemskerk, A.C.; Kok, L.P.; Roo, M. de
1975-01-01
In two practical examples (Î±-3He and Î±-Î± scattering) we investigate to what extent the elastic amplitude above the first inelastic threshold, determined from phase-shift analysis, is subject to ambiguity. We find that it is extremely difficult to determine the correct physical amplitude uniquely.
Froggatt, C D
1975-01-01
Using extrapolated pi /sup +/ pi /sup -/ moments from amplitude analysis of the 17 GeV/c CERN-Munich experiment on pi /sup -/p to pi /sup +/=/sup -/n the authors attempt to reduce phase-shift ambiguities by imposing fixed-t and fixed-u analyticity. Their solution agrees qualitatively with semi-local duality. They also perform a phase-shift analysis by constraining the results to be compatible with the fixed-t (-u) amplitudes. A smooth phase-shift solution is obtained showing a clear rho ' signal. (20 refs).
Geometric phase shifting digital holography.
Jackin, Boaz Jessie; Narayanamurthy, C S; Yatagai, Toyohiko
2016-06-01
A new phase shifting digital holographic technique using a purely geometric phase in Michelson interferometric geometry is proposed. The geometric phase in the system does not depend upon either optical path length or wavelength, unlike dynamic phase. The amount of geometric phase generated is controllable through a rotating wave plate. The new approach has unique features and major advantages in holographic measurement of transparent and reflecting three-dimensional (3D) objects. Experimental results on surface shape measurement and imaging of 3D objects are presented using the proposed method.
Froggatt, C D
1977-01-01
For pt.I see ibid., vol.104, p.186 (1976). The authors present final results for a pi pi phase-shift analysis based on extrapolated moments obtained from the 17 GeV/c CERN-Munich experiment on pi /sup -/p to pi /sup +/ pi /sup -/n. Compared to the previous publication the final results show no important qualitative change but the numerical accuracy is considerably improved as a result of using modified techniques both in the fixed-momentum transfer analysis and in the phase-shift analysis. As a result, various diseases of the old solution have been cured. They analyze in some detail the coupling of the rho '(1600) to 2 pi , clearly seen in the solution. It is argued that the technique has solved the phase-shift ambiguities previously obtained and details are given of the solution which has a very good chi /sup 2/ to the data as well as a high numerical consistency with fixed-t, fixed-u and fixed-s analyticity. (19 refs).
Crichton's phase-shift ambiguity
Atkinson, D.; Johnson, P.W.; Mehta, N.; Roo, M. de
1973-01-01
A re-examination of the SPD phase-shift ambiguity is made with a view to understanding certain singular features of the elastic unitarity constraint. An explicit solution of Crichton's equations is presented, and certain features of this solution are displayed graphically. In particular, it is shown
Phase-function method for Coulomb-distorted nuclear scattering
Energy Technology Data Exchange (ETDEWEB)
Sett, G.C.; Laha, U.; Talukdar, B.
1988-09-21
The phase-function method is very effective in treating quantum mechanical scattering problems for short-range local potentials. We adapt the phase method to deal with Coulomb plus Graz non-local separable potentials and derive a closed-form expression for the scattering phase shift. Our approach to the problem circumvents in a rather natural way the typical difficulties of incorporating the Coulomb interaction in a nuclear phase-shift calculation. We demonstrate the usefulness of our constructed expression by means of a model calculation.
Controllable optical phase shift over one radian from a single isolated atom.
Jechow, A; Norton, B G; Händel, S; Blūms, V; Streed, E W; Kielpinski, D
2013-03-15
Fundamental optics such as lenses and prisms work by applying phase shifts of several radians to incoming light, and rapid control of such phase shifts is crucial to telecommunications. However, large, controllable optical phase shifts have remained elusive for isolated quantum systems. We have used a single trapped atomic ion to induce and measure a large optical phase shift of 1.3±0.1 radians in light scattered by the atom. Spatial interferometry between the scattered light and unscattered illumination light enables us to isolate the phase shift in the scattered component. The phase shift achieves the maximum value allowed by atomic theory over the accessible range of laser frequencies, pointing out new opportunities in microscopy and nanophotonics. Single-atom phase shifts of this magnitude open up new quantum information protocols, in particular long-range quantum phase-shift-keying cryptography.
Light scattering near phase transitions
Cummins, HZ
1983-01-01
Since the development of the laser in the early 1960's, light scattering has played an increasingly crucial role in the investigation of many types of phase transitions and the published work in this field is now widely dispersed in a large number of books and journals.A comprehensive overview of contemporary theoretical and experimental research in this field is presented here. The reviews are written by authors who have actively contributed to the developments that have taken place in both Eastern and Western countries.
Homogeneous illusion device exhibiting transformed and shifted scattering effect
Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue
2016-06-01
Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.
$I=1$ and $I=2$ $π-π$ scattering phase shifts from $N_{\\mathrm{f}} = 2+1$ lattice QCD
DEFF Research Database (Denmark)
Bulava, John; Fahy, Brendan; Hörz, Ben
2016-01-01
The $I=1$ $p$-wave and $I=2$ $s$-wave elastic $\\pi$-$\\pi$ scattering amplitudes are calculated from a first-principles lattice QCD simulation using a single ensemble of gauge field configurations with $N_{\\mathrm{f}} = 2+1$ dynamical flavors of anisotropic clover-improved Wilson fermions. This en...
Dynamic phase extraction in phase-shifted shearography
Hou, Yuanyuan; Xu, Jiancheng
2016-03-01
Phase-shifted shearography needs to extract dynamic phase of the measured object after loading, so an algorithm for dynamic phase extraction in phase-shifted shearography is proposed to analyze the speckle patterns with random phase shifts. By using correlation method, the fringe patterns with random phase shifts are obtained from the speckle patterns with random phase shifts. Then the dynamic phase distributions are extracted from one set of random phase-shifted fringe patterns by principle component analysis. The experimental results show that the extracted phases are accurate and efficient. The proposed method is non-iterative and has no strict requirement for the spatial-carrier frequency of fringe patterns, so it is suitable for dynamic shearing speckle interferometry.
Phase shift of sinusoidally alternating colored stimuli
Walraven, P.L.; Leebeek, H.J.
1964-01-01
In order to avoid luminance flicker at equal luminance of two alternating colored stimuli de Lange found that a phase shift of the stimuli with respect to each other has to be introduced. This compensation for the phase shift occurring in the retina-cortex system has been measured for a large number
Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses
Energy Technology Data Exchange (ETDEWEB)
Alekseev, A E [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino branch, Fryazino, Moscow Region (Russian Federation); Vdovenko, V S; Sergachev, I A; Simikin, D E [OOO " Petrofaiber" , Russia, Tula region, Novomoskovsk (Russian Federation); Gorshkov, B G [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Potapov, V T [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino Branch, Fryazino, Moscow region (Russian Federation)
2014-10-31
We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)
Phase shifting interferometry from two normalized interferograms with random tilt phase-shift.
Liu, Fengwei; Wu, Yongqian; Wu, Fan
2015-07-27
We propose a novel phase shifting interferometry from two normalized interferograms with random tilt phase-shift. The determination of tilt phase-shift is performed by extracting the tilted phase-shift plane from the phase difference of two normalized interferograms, and with the calculated tilt phase-shift value the phase distribution can be retrieved from the two normalized frames. By analyzing the distribution of phase difference and utilizing special points fitting method, the tilted phase-shift plane is extracted in three different cases, which relate to different magnitudes of tilts. Proposed method has been applied to simulations and experiments successfully and the satisfactory results manifest that proposed method is of high accuracy and high speed compared with the three step iterative method. Additionally, both open and closed fringe can be analyzed with proposed method. What's more, it cannot only eliminate the small tilt-shift error caused by slight vibration in phase-shifting interferometry, but also detect the large tilt phase-shift in phase-tilting interferometry. Thus, it will relaxes the requirements on the accuracy of phase shifter, and the costly phase shifter may even be useless by applying proposed method in high amplitude vibrated circumstance to achieve high-precision analysis.
Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt
2007-01-01
We show a novel technique to distinguish between Doppler shifted and unshifted light in multiple scattering experiments on mixed static and dynamic media. With a phase modulated low coherence Mach- Zehnder interferometer, optical path lengths of shifted and unshifted light and path length dependent
Liu, Qian; Wang, Yang; Ji, Fang; He, Jianguo
2013-11-01
A spatial frequency domain method is presented to deal with tilt-shift errors and random phase shift in temporal phase-shift interferometry. The proposed method determines tilt shift and phase shift by analyzing positions and phase variances of sidebands in spatial frequency domain. The method is computationally fast for it is noniterative and needs only one 2D Fourier transform for each spatial carrier interferogram. No initial estimations are required and no ambiguous results are generated with the proposed method. Simulations indicate that the proposed method could detect tilt shift and piston phase shift with high accuracy. Results of experiments conducted in the presence of vibration demonstrate that the proposed method could alleviate fluctuations in the retrieved phase map. The method could be applied to interferometers that are uncalibrated or with an unbalanced piezoelectric transducer, besides interferometers in unsteady conditions.
Cavity Attenuated Phase Shift (CAPS) Monitor Instrument Handbook
Energy Technology Data Exchange (ETDEWEB)
Sedlacek, Arthur J. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2016-04-01
The CAPS PMex monitor is a cavity attenuated phase shift extinction instrument. It operates as an optical extinction spectrometer, using a visible-light-emitting diode (LED) as the light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector. Its efficacy is based on the fact that aerosols are broadband scatterers and absorbers of light.
Data for phase angle shift with frequency
Directory of Open Access Journals (Sweden)
T. Paul
2016-06-01
Full Text Available Phase angle shift between the current and voltage with frequency has been reported for a single phosphoric acid fuel cell in the cell temperature from 100 °C to 160 °C and the humidifier temperature from 40 °C to 90 °C. An electrochemical workbench is employed to find the shift. The figure of phase angle shift shows a peak in high humidifier temperatures. The peak in phase angle shift directs to lower frequency side with decreasing humidifier temperature. The estimation of electrochemical reaction time is also evaluated in the humidifier temperature zone from 50 °C to 90 °C.
Phase-shift binary digital holography.
Horisaki, Ryoichi; Tahara, Tatsuki
2014-11-15
We propose phase-shift digital holography (DH) with a one-bit image sensor. In this method, the propagating complex field from an object is binarized by a one-bit sensor using a phase-shifter. The complex field on the hologram plane is then calculated with the one-bit image data. The object field is recovered via Fresnel back-propagation of the calculated hologram and filtering to suppress some artifacts caused by the binarization. The concept was demonstrated in preliminary experiments by using a synthetically binarized hologram with single-shot and multi-shot phase-shift DH.
Phase shifting profilometry with optical vortices
Sokolenko, B.; Poletaev, D.; Halilov, S.
2017-11-01
In this work we review principles and applications of a method of phase shifting profilometry with using of optical vortices imbedded into the probe beam. High spatial resolution caused by vortex phase sensitivity is analysable to retrieve the 2D and 3D shape of optically transparent and reflecting surfaces with exceeding of optical diffraction limit. This method applicable for non-destructive testing of thin films, live cells and biological tissues in real-time regime. Automatic processing of vortex interferograms with vortex phase shift analysis allow to achieve a vertical resolution down to 1,75 nm.
Robust phase-shift estimation method for statistical generalized phase-shifting digital holography.
Yoshikawa, Nobukazu; Shiratori, Takaaki; Kajihara, Kazuki
2014-06-16
We propose a robust phase-shift estimation method for statistical generalized phase-shifting digital holography using a slightly off-axis optical configuration. The phase randomness condition in the Fresnel diffraction field of an object can be sufficiently established by the linear phase factor of the oblique incident reference wave. Signed phase-shift values can be estimated with a statistical approach regardless of the statistical properties of the Fresnel diffraction field of the object. We present computer simulations and optical experiments to verify the proposed method.
Phase-shifting structures for isolated features
Garofalo, Joseph G.; Kostelak, Robert L.; Yang, Tungsheng
1991-07-01
The technique for improving optical projection-system resolution by phase-shifting alternate apertures of a periodic grating was introduced in 1982. This halves the frequency content of the image passing through the optics and should therefore double the effective resolution of such patterns. Unfortunately, as feature separation increases, the efficacy of this method diminishes. Previous work applying a similar approach to isolated features involves introducing minute, non-printable, phase-shifted assist slots around the desired feature. The diffraction side-lobes of these slots constructively interfere with the center lobe of the primary aperture. The resolution enhancement afforded be this technique is limited by the printability of the assist slots. This restraint also dictates 1X-size reticle feature dimensions and the employment of high contrast imaging resists. A new approach entails significantly oversizing the desired feature and introducing a phase-shifting region around the periphery. This type of structure affords substantial focus-exposure improvements and may either be fabricated in a single-level, self-aligned scheme or by a two-level exposure with conventional e-beam tools since the phase-shifting regions are on the order of 1 micrometers (reticle dimensions). Extensive modeling of this structure for isolated contact holes and spaces explores the myriad of trade- offs involved in an optimum design. Mask-fabrication tolerances, such as phase-shift uniformity, are also investigated. It is shown that the focus-exposure window enlarges as the overall structure dimensions increase. The degree of enhancement must therefore by weighed against packing density restrictions. Also, the structure suffers, to some degree, from the effect of side-lobes. However, for a given side-lobe intensity, this technique yields enhancements superior to the assist-slot approach. As is typical of phase-shifted systems, performance is improved as the partial coherence ((sigma
Accurate phase-shift velocimetry in rock.
Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M
2016-06-01
Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. Copyright © 2016. Published by Elsevier Inc.
Geometric phase shifts in biological oscillators.
Tourigny, David S
2014-08-21
Many intracellular processes continue to oscillate during the cell cycle. Although it is not well-understood how they are affected by discontinuities in the cellular environment, the general assumption is that oscillations remain robust provided the period of cell divisions is much larger than the period of the oscillator. Here, I will show that under these conditions a cell will in fact have to correct for an additional quantity added to the phase of oscillation upon every repetition of the cell cycle. The resulting phase shift is an analogue of the geometric phase, a curious entity first discovered in quantum mechanics. In this letter, I will discuss the theory of the geometric phase shift and demonstrate its relevance to biological oscillations. Copyright © 2014 Elsevier Ltd. All rights reserved.
Phase-Shifting Zernike Interferometer Wavefront Sensor
Wallace, J. Kent; Rao, Shanti; Jensen-Clemb, Rebecca M.; Serabyn, Gene
2011-01-01
The canonical Zernike phase-contrast technique1,2,3,4 transforms a phase object in one plane into an intensity object in the conjugate plane. This is done by applying a static pi/2 phase shift to the central core (approx. lambda/D) of the PSF which is intermediate between the input and output planes. Here we present a new architecture for this sensor. First, the optical system is simple and all reflective. Second, the phase shift in the central core of the PSF is dynamic and or arbitrary size. This common-path, all-reflective design makes it minimally sensitive to vibration, polarization and wavelength. We review the theory of operation, describe the optical system, summarize numerical simulations and sensitivities and review results from a laboratory demonstration of this novel instrument
The Phase Shift in the Jumping Ring
Jeffery, Rondo N.; Amiri, Farhang
2008-01-01
The popular physics demonstration experiment known as Thomson's Jumping Ring (JR) has been variously explained as a simple example of Lenz's law, or as the result of a phase shift of the ring current relative to the induced emf. The failure of the first-quadrant Lenz's law explanation is shown by the time the ring takes to jump and by levitation.…
Study of the triplet periodicity phase shifts in genes.
Korotkov, Eugene V; Korotkova, Maria A
2010-03-25
The definition of a phase shift of triplet periodicity (TP) is introduced. The mathematical algorithm for detection of TP phase shift of nucleotide sequences has been developed. Gene sequences from Kegg-46 data bank were analyzed with a purpose of searching genes with a phase shift of TP. The presence of a phase shift of triplet periodicity has been shown for 318329 genes (approximately 10% from the number of genes in Kegg-46). We suppose that shifts of the TP phase may indicate the shifts of reading frame (RF) in genes. A relationship between the phase shifts of TP and the frame shifts in genes is discussed.
Quantum illumination reveals phase-shift inducing cloaking.
Las Heras, U; Di Candia, R; Fedorov, K G; Deppe, F; Sanz, M; Solano, E
2017-08-24
In quantum illumination entangled light is employed to enhance the detection accuracy of an object when compared with the best classical protocol. On the other hand, cloaking is a stealth technology based on covering a target with a material deflecting the light around the object to avoid its detection. Here, we propose a quantum illumination protocol especially adapted to quantum microwave technology. This protocol seizes the phase-shift induced by some cloaking techniques, such as scattering reduction, allowing for a 3 dB improvement in the detection of a cloaked target. The method can also be employed for the detection of a phase-shift in bright environments in different frequency regimes. Finally, we study the minimal efficiency required by the photocounter for which the quantum illumination protocol still shows a gain with respect to the classical protocol.
Performance of Equal Phase-Shift Search for One Iteration
D. Li; Chen, J. P.; Huang, H.; X. Li
2006-01-01
Grover presented the phase-shift search by replacing the selective inversions by selective phase shifts of $\\pi /3$. In this paper, we investigate the phase-shift search with general equal phase shifts. We show that for small uncertainties, the failure probability of the Phase-$\\pi /3$ search is smaller than the general phase-shift search and for large uncertainties, the success probability of the large phase-shift search is larger than the Phase-$\\pi /3$ search. Therefore, the large phase-sh...
Michelson interferometer based spatial phase shift shearography.
Xie, Xin; Yang, Lianxiang; Xu, Nan; Chen, Xu
2013-06-10
This paper presents a simple spatial phase shift shearography based on the Michelson interferometer. The Michelson interferometer based shearographic system has been widely utilized in industry as a practical nondestructive test tool. In the system, the Michelson interferometer is used as a shearing device to generate a shearing distance by tilting a small angle in one of the two mirrors. In fact, tilting the mirror in the Michelson interferometer also generates spatial frequency shift. Based on this feature, we introduce a simple Michelson interferometer based spatial phase shift shearography. The Fourier transform (FT) method is applied to separate the spectrum on the spatial frequency domain. The phase change due to the loading can be evaluated using a properly selected windowed inverse-FT. This system can generate a phase map of shearography by using only a single image. The effects of shearing angle, spatial resolution of couple charge device camera, and filter methods are discussed in detail. The theory and the experimental results are presented.
Phase-locking in cascaded stimulated Brillouin scattering
Büttner, Thomas F S; Steel, M J; Hudson, Darren D; Eggleton, Benjamin J
2015-01-01
Cascaded stimulated Brillouin scattering (SBS) is a complex nonlinear optical process that results in the generation of several optical waves that are frequency shifted by an acoustic resonance frequency. Four-wave mixing (FWM) between these Brillouin shifted optical waves can create an equally spaced optical frequency comb with a stable spectral phase, i.e. a Brillouin frequency comb (BFC). Here, we investigate phase-locking of the spectral components of BFCs, considering FWM interactions arising from the Kerr-nonlinearity as well as from coupling by the acoustic field. Deriving for the first time the coupled-mode equations that include all relevant nonlinear interactions, we examine the contribution of the various nonlinear processes to phase-locking, and show that different regimes can be obtained that depend on the length scale on which the field amplitudes vary.
Energy phase shift as mechanism for catalysis
Beke-Somfai, Tamás
2012-05-01
Catalysts are agents that by binding reactant molecules lower the energy barriers to chemical reaction. After reaction the catalyst is regenerated, its unbinding energy recruited from the environment, which is associated with an inevitable loss of energy. We show that combining several catalytic sites to become energetically and temporally phase-shifted relative to each other provides a possibility to sustain the overall reaction by internal \\'energy recycling\\', bypassing the need for thermal activation, and in principle allowing the system to work adiabatically. Using an analytical model for superimposed, phase-shifted potentials of F 1-ATP synthase provides a description integrating main characteristics of this rotary enzyme complex. © 2012 Elsevier B.V. All rights reserved.
Almehed, S
1972-01-01
The authors CERN-EXP phase-shift analysis (see abstr. A15865 of 1968) has been redone with 2/sup 1///sub 2/ times more experimental data (11550 points). The results differ mainly in being even smoother. Most of the previous resonance candidates are strengthened, and four possible new ones above 2 GeV suggested. However, the D/sub 13/(1700) required by the quark model is still absent. (48 refs).
Phase-shifting interferometer for surface inspection
Tam, Siu Chung; Low, Beng-Yew; Chua, Hock-Chuan; Ho, Anthony T. S.; Neo, Wah-Peng
1997-08-01
A phase-shifting Twyman-Green interferometer has been constructed. Using three consecutively captured interferograms, the phase profile of a reflective surface can be determined. Results using various fringe processing techniques are compared. These methods include uniform averaging, Gaussian mask and spin filtering. For simulated fringes superimposed with random noise and fixed-pattern noise, it has been observed that a combination of weighted averaging and spin filtering could generate the best results. The computerized system has been applied to the measurement of the form errors of a silicon wafer and a cosmetic mirror, respectively. The root-mean-square error of the wafer is determined to be 11.13 nm.
Phase-step retrieval for tunable phase-shifting algorithms
Ayubi, Gastón A.; Duarte, Ignacio; Perciante, César D.; Flores, Jorge L.; Ferrari, José A.
2017-12-01
Phase-shifting (PS) is a well-known technique for phase retrieval in interferometry, with applications in deflectometry and 3D-profiling, which requires a series of intensity measurements with certain phase-steps. Usually the phase-steps are evenly spaced, and its knowledge is crucial for the phase retrieval. In this work we present a method to extract the phase-step between consecutive interferograms. We test the proposed technique with images corrupted by additive noise. The results were compared with other known methods. We also present experimental results showing the performance of the method when spatial filters are applied to the interferograms and the effect that they have on their relative phase-steps.
Using phase for radar scatterer classification
Moore, Linda J.; Rigling, Brian D.; Penno, Robert P.; Zelnio, Edmund G.
2017-04-01
Traditional synthetic aperture radar (SAR) systems tend to discard phase information of formed complex radar imagery prior to automatic target recognition (ATR). This practice has historically been driven by available hardware storage, processing capabilities, and data link capacity. Recent advances in high performance computing (HPC) have enabled extremely dense storage and processing solutions. Therefore, previous motives for discarding radar phase information in ATR applications have been mitigated. First, we characterize the value of phase in one-dimensional (1-D) radar range profiles with respect to the ability to correctly estimate target features, which are currently employed in ATR algorithms for target discrimination. These features correspond to physical characteristics of targets through radio frequency (RF) scattering phenomenology. Physics-based electromagnetic scattering models developed from the geometrical theory of diffraction are utilized for the information analysis presented here. Information is quantified by the error of target parameter estimates from noisy radar signals when phase is either retained or discarded. Operating conditions (OCs) of signal-tonoise ratio (SNR) and bandwidth are considered. Second, we investigate the value of phase in 1-D radar returns with respect to the ability to correctly classify canonical targets. Classification performance is evaluated via logistic regression for three targets (sphere, plate, tophat). Phase information is demonstrated to improve radar target classification rates, particularly at low SNRs and low bandwidths.
Composite phase-shifting algorithm for absolute phase measurement
Zhang, Song
2012-11-01
This paper presents a method to recover absolute phase by using only four images: three phase-shifted patterns and one stair pattern. The stair pattern is designed in such a way that the stair changes are perfectly aligned with the phase jumps, and thus absolute phase can be recovered by referring to the stair pattern. Due to system noises and camera and/or projector blurring, a computational framework is also proposed. Because this technique only requires four fringe images for absolute phase recovery, it has the merit of measurement speed. And since the absolute phase is obtained, this technique is suitable for measuring step-height objects. We have developed a digital fringe projection system to verify the performance of the proposed technique.
Beam splitter phase shifts: Wave optics approach
Agnesi, Antonio; Degiorgio, Vittorio
2017-10-01
We investigate the phase relationships between transmitted and reflected waves in a lossless beam splitter having a multilayer structure, using the matrix approach as outlined in classical optics books. Contrarily to the case of the quantum optics formalism generally employed to describe beam splitters, these matrices are not unitary. In this note we point out the existence of general relations among the elements of the transfer matrix that describes the multilayer beam splitter. Such relations, which are independent of the detailed structure of the beam splitter, fix the phase shifts between reflected and transmitted waves. It is instructive to see how the results obtained by Zeilinger by using spinor algebra and Pauli matrices can be easily derived from our general relations.
Zhou, Jianyang; Zhao, Daomu
2017-05-01
Within the accuracy of the first-order Born approximation, the spectral shifts and spectral switches produced by the scattering of an electromagnetic light wave from a random hollow scatterer with adjustable shell thickness have been investigated. The effects of the properties of the scatterer and the incident light wave on the far-zone scattered spectrum have been discussed in detail by using numerical examples. It is shown that, as the scattering angle increases, the scattered spectrum will split into two peaks, and subsequently the two peaks will make a rapid transition as a spectral switch. The position at which the spectral switch occurs is affected by the shell thickness, the outer and inner correlation lengths of the scatterer as well as the polarization of the incident light. Besides, the polarization of the incident light also has an impact on the spectral width of the scattered field.
Phase-shift feedback cavity ring-down spectroscopy.
Hovde, Chris; Gomez, Anthony L
2015-06-10
Phase-shift cavity-enhanced techniques have been used to measure optical losses with relatively simple electronics. Instead of measuring the phase shift, in this work the intensity modulation frequency is varied using feedback to keep the phase shift locked to a target value. The modulation frequency then becomes a signal from which cavity losses can be estimated. The technique is applied with a super luminescent diode to measure losses resulting from the addition of acetylene to a cavity containing nitrogen at ambient temperature and pressure. The technique, phase-shift feedback cavity ring down, is compared to phase-shift cavity ring-down spectroscopy.
Varghese, B; Rajan, V; van Leeuwen, T G; Steenbergen, W
2007-10-01
We show a novel technique to distinguish between Doppler shifted and unshifted light in multiple scattering experiments on mixed static and dynamic media. With a phase modulated low coherence Mach- Zehnder interferometer, optical path lengths of shifted and unshifted light and path length dependent Doppler broadening are measured in a two-layer tissue phantom, with a superficial static layer of different thickness covering a semi-infinite dynamic medium having identical optical properties. No Doppler broadening is observed until a certain optical path length depending on the thickness of the superficial static layer. From the minimum optical path length corresponding to the Doppler-shifted light the thickness of the static layer that overlies the dynamic layer can be estimated. Validation of the experimentally determined thickness of the static layer is done with the Doppler Monte Carlo technique. This approach has potential applications in discriminating between statically and dynamically scattered light in the perfusion signal and in determining superficial burn depths.
Fizeau simultaneous phase-shifting interferometry based on extended source
Wang, Shanshan; Zhu, Qiudong; Hou, Yinlong; Cao, Zheng
2016-09-01
Coaxial Fizeau simultaneous phase-shifting interferometer plays an important role in many fields for its characteristics of long optical path, miniaturization, and elimination of reference surface high-frequency error. Based on the matching of coherence between extended source and interferometer, orthogonal polarization reference wave and measurement wave can be obtained by Fizeau interferometry with Michelson interferometer preposed. Through matching spatial coherence length between preposed interferometer and primary interferometer, high contrast interference fringes can be obtained and additional interference fringes can be eliminated. Thus, the problem of separation of measurement and reference surface in the common optical path Fizeau interferometer is solved. Numerical simulation and principle experiment is conducted to verify the feasibility of extended source interferometer. Simulation platform is established by using the communication technique of DDE (dynamic data exchange) to connect Zemax and Matlab. The modeling of the extended source interferometer is realized by using Zemax. Matlab codes are programmed to automatically rectify the field parameters of the optical system and conveniently calculate the visibility of interference fringes. Combined with the simulation, the experimental platform of the extended source interferometer is established. After experimental research on the influence law of scattering screen granularity to interference fringes, the granularity of scattering screen is determined. Based on the simulation platform and experimental platform, the impacts on phase measurement accuracy of the imaging system aberration and collimation system aberration of the interferometer are analyzed. Compared the visibility relation curves between experimental measurement and simulation result, the experimental result is in line with the theoretical result.
Xie, Dongzhuo; Zhao, Dongliang; Yang, Yong; Zhai, Hongchen
2017-06-01
This paper presents a phase-shift extraction method for blind phase-shifting holography applications based on the quotient of inner products. The method only requires acquiring three-frame holograms with arbitrary unequal phase-shift values and the intensity of the reference wave, without requiring the object wave intensity. Two phase shift values can be extracted precisely using the algorithm, which can remove the background noise and DC component effects. Both simulated and experimental results have demonstrated the phase step retrieval accuracy and the feasibility of reconstructing the complex amplitude of the object wave.
A self-tuning phase-shifting algorithm for interferometry.
Estrada, Julio C; Servin, Manuel; Quiroga, Juan A
2010-02-01
In Phase Stepping Interferometry (PSI) an interferogram sequence having a known, and constant phase shift between the interferograms is required. Here we take the case where this constant phase shift is unknown and the only assumption is that the interferograms do have a temporal carrier. To recover the modulating phase from the interferograms, we propose a self-tuning phase-shifting algorithm. Our algorithm estimates the temporal frequency first, and then this knowledge is used to estimate the interesting modulating phase. There are several well known iterative schemes published before, but our approach has the unique advantage of being very fast. Our new temporal carrier, and phase estimator is capable of obtaining a very good approximation of their temporal carrier in a single iteration. Numerical experiments are given to show the performance of this simple yet powerful self-tuning phase shifting algorithm.
Phase shifts and the second virial coefficient for a partially ionized hydrogen plasma
Energy Technology Data Exchange (ETDEWEB)
Omarbakiyeva, Y.A. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); IETP, al-Farabi Kazakh National University, 96a Tole bi str., 050012 Almaty (Kazakhstan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); Ramazanov, T.S. [IETP, al-Farabi Kazakh National University, 96a Tole bi str., 050012 Almaty (Kazakhstan)
2009-12-15
The influence of the interaction of electrons with hydrogen atoms on the thermodynamical properties of dense plasmas is investigated using a virial expansion approach. The second virial coefficient for the electron-atom interaction is obtained from the Beth-Uhlenbeck formula. Elastic scattering phase shifts are calculated with the help of the phase function method for different polarization potential models. Results for the second virial coefficient are given that take into account both the bound state part and the scattering state contribution (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Phase-Shift Interferometry with a Digital Photocamera
Vannoni, Maurizio; Trivi, Marcelo; Molesini, Giuseppe
2007-01-01
A phase-shift interferometry experiment is proposed, working on a Twyman-Green optical configuration with additional polarization components. A guideline is provided to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses. (Contains 5 figures.)
Phase-shift amplification for precision measurements without nonclassical states
Luis Aina, Alfredo
2002-01-01
We propose a practical arrangement that allows one to reach the Heisenberg limit in precision phase-shift measurements. This is achieved via phase-shift amplification. The arrangement we propose is based on experimental processes already carried out and does not require the use of any special quantum state.
Rigorous 3D simulation of phase defects in alternating phase-shifting masks
Pistor, Thomas V.
2002-03-01
A study of both the printability and inspectability of phase defects in alternating phase-shifting masks is made using rigorous FDTD simulation of mask topography and vector-based models for optical imaging that account for the angular dependence of the mask scattering coefficients and high numerical aperture effects. Aerial images inside the photoresist are calculated through focus under typical 193nm stepper imaging conditions in order to assess the effects of size, phase, location and shape on the printability of phase bump defects. Defects located adjacent to the vertical sidewalls of the phase shifter are found to affect CD more than defects located in the center of the phase shifter. Defect shape does not appear to be a strong factor in printability. Aerial images and difference signals for various defects under mask transmission-imaging inspection conditions are calculated. A study of illumination pupil effects in mask inspection is presented. Defect visibility when varying defect size and position is investigated. Defects close to the phase shifter vertical sidewall are less visible. Defects are observed to be more visible when the mask is defocused. An investigation of illumination effects show that coherent systems can see defects better than incoherent systems, while certain incident plane waves are found to 'see' a particular defect better than others.
Realizing total reciprocity violation in the phase for photon scattering.
Deák, László; Bottyán, László; Fülöp, Tamás; Merkel, Dániel Géza; Nagy, Dénes Lajos; Sajti, Szilárd; Schulze, Kai Sven; Spiering, Hartmut; Uschmann, Ingo; Wille, Hans-Christian
2017-02-22
Reciprocity is when wave or quantum scattering satisfies a symmetry property, connecting a scattering process with the reversed one. While reciprocity involves the interchange of source and detector, it is fundamentally different from rotational invariance, and is a generalization of time reversal invariance, occurring in absorptive media as well. Due to its presence at diverse areas of physics, it admits a wide variety of applications. For polarization dependent scatterings, reciprocity is often violated, but violation in the phase of the scattering amplitude is much harder to experimentally observe than violation in magnitude. Enabled by the advantageous properties of nuclear resonance scattering of synchrotron radiation, we have measured maximal, i.e., 180-degree, reciprocity violation in the phase. For accessing phase information, we introduced a new version of stroboscopic detection. The scattering setting was devised based on a generalized reciprocity theorem that opens the way to construct new types of reciprocity related devices.
In vivo optical path lengths and path length resolved doppler shifts of multiply scattered light.
Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G; Steenbergen, Wiendelt
2010-11-01
In laser Doppler measurements, perfusion values averaged over different and basically unknown path lengths are recorded. To facilitate quantitative path length resolved perfusion measurements, we developed a phase modulated Mach-Zehnder interferometer with spatially separated fibers for illumination and detection. The goal of this study is to measure in vivo optical path lengths and path length resolved Doppler shifts and to compare these with conventional laser Doppler perfusion measurements. With a phase modulated Mach-Zehnder interferometer, we performed path length resolved perfusion measurements on human skin and its variations to external stimuli and compared these with conventional laser Doppler perfusion measurements. The method was evaluated in three human subjects on the dorsal side of the forearm to establish inter-individual within-site variations. Measurements were performed at three different locations of one individual for observing intra-individual inter-site variations resulting from the heterogeneity of the tissue, both in the static matrix and in the microvascular architecture of the skin. In all measurements, perfusion was simultaneously measured with a conventional laser Doppler perfusion monitor. In this study, we show the first results of path length resolved perfusion measurements in skin and its variations to occlusion and Capsicum cream provocation. From our data, we deduced the Doppler shifted fraction of photons, which is related to the blood volume, and the path length dependent average Doppler shift, which is related to the mean velocities of red blood cells. The Doppler shifted fraction of photons is decreased from 28% to 18% during occlusion and increases to 41% when capsicum cream was applied to the skin. Inter- and intra-individual inter-site measurements demonstrated variations in optical path length distributions and path length resolved Doppler shifts. The Doppler shifted fraction of photons measured on the fingertip is about 38
Recurrence phase shift in Fermi-Pasta-Ulam nonlinear dynamics
Energy Technology Data Exchange (ETDEWEB)
Devine, N., E-mail: nnd124@rsphysse.anu.edu.au [Optical Sciences Group, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Ankiewicz, A. [Optical Sciences Group, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Genty, G. [Tampere University of Technology, Optics Laboratory, FI-33101 Tampere (Finland); Dudley, J.M. [Institut FEMTO-ST UMR 6174 CNRS/Universite de Franche-Comte, Besancon (France); Akhmediev, N. [Optical Sciences Group, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)
2011-11-07
We show that the dynamics of Fermi-Pasta-Ulam recurrence is associated with a nonlinear phase shift between initial and final states that are otherwise identical, after a full growth-return cycle. The properties of this phase shift are studied for the particular case of the self-focussing nonlinear Schroedinger equation, and we describe the magnitude of the phase shift in terms of the system parameters. This phase shift, accumulated during the nonlinear recurrence cycle, is a previously-unremarked feature of the Fermi-Pasta-Ulam problem, and we anticipate its wide significance as an essential feature of related dynamics in other systems. -- Highlights: → The dynamics of FPU recurrence is associated with a phase shift between initial and final states. → The properties of this phase shift are studied for the self-focussing NLS equation. → This phase shift is a previously-unremarked feature of the FPU growth-return cycle. → We anticipate its wide significance as an essential feature of related dynamics in other systems.
Cheema, M Imran; Hayat, Ahmad A; Peter, Yves-Alain; Armani, Andrea M; Kirk, Andrew G
2012-01-01
Optical resonant microcavities with ultra high quality factors are widely used for biosensing. Until now, the primary method of detection has been based upon tracking the resonant wavelength shift as a function of biological events. One of the sources of noise in all resonant-wavelength shift measurements is the noise due to intensity fluctuations of the laser source. An alternative approach is to track the change in the quality factor of the optical cavity by using phase shift cavity ring down spectroscopy, a technique which is insensitive to the intensity fluctuations of the laser source. Here, using biotinylated microtoroid resonant cavities, we show simultaneous measurement of the quality factor and the wavelength shift by using phase shift cavity ring down spectroscopy. These measurements were performed for disassociation phase of biotin-streptavidin reaction. We found that the disassociation curves are in good agreement with the previously published results. Hence, we demonstrate not only the applicatio...
Raman scattering study of the phase transition in wet-spun films of lithium hyaluronate
Reineck, I.; Suleski, T. J.; Lee, S. A.; Rupprecht, A.
2002-03-01
Raman scattering experiments have been performed on wet-spun films of lithium hyaluronate as a function of relative humidity (RH). Near 84 percent RH several of the internal Raman modes, but not all, are observed to shift to different frequencies. These data indicate these modes are affected by the phase transition known to occur near this RH. The frequencies of the effected Raman modes return to their "normal" value after the phase transition has been passed.
The role of optical filtering in microwave phase shifting.
O Dúill, Seán; Shumakher, Evgeny; Eisenstein, Gadi
2010-07-01
We highlight the importance of the delay arising from optical filters in slow-light-based microwave phase shifting systems. We calculate the filter delay numerically from the measured amplitude response by using the well-known Kramers-Kronig relations. The complex filter transmission response is then incorporated within a numerical model with which we explain phase shifting results obtained from experiments employing semiconductor optical amplifiers as slow light elements.
SIMULATION OF CHARACTERISTICS OF DUAL-CORE PHASE SHIFTING TRANSFORMER
Directory of Open Access Journals (Sweden)
Kalinin L.P.
2014-04-01
Full Text Available The role and importance of phase shifting transformers are increased as a result of the further development of integrated power systems. This gives the rise to new technical solutions which entails the necessity of comparison of new developments with existing. The article consider the technical characteristics of dual-core phase shifting transformer which later will be used as a basis for comparison with other competing options and assess of their technical efficiency.
Phase-shift treatment for tinnitus of cochlear origin.
Meeus, Olivier; Heyndrickx, Karen; Lambrechts, Peggy; De Ridder, Dirk; Van de Heyning, Paul
2010-06-01
Phase-shift treatment is a new tinnitus therapy that aims at sound cancelling. This technique is based on a theory advocating that the induction of a sound wave with a 180 degrees phase-shift compared to the sound experienced by the patient could result in sound cancelling, likely by negation of the cortical perception of tinnitus or residual inhibition, which can be partial or complete. The aim of our study is to compare the effect of phase-shifting generated by the tinnitus phase-out device between pure tone tinnitus patients (PTP) and narrow band noise tinnitus patients (NBNP). In present comparative study, we explore the effects of phase-shifting during 6 weeks of phase-out therapy in PTP and NBNP. Thirty-five tinnitus patients were included in the study. Twenty-one patients had pure tone tinnitus and 14 patients had narrow band noise tinnitus. The effects on tinnitus were assessed using three separate visual analogue scales (VAS), the tinnitus questionnaire, the hyperacusis questionnaire, the Beck depression inventory, a categorical scale and audiometric measurements. While no differences in VAS were seen after therapy in NBNP, tinnitus increase could be demonstrated in PTP. This increase could be demonstrated for tinnitus loudness (p = 0.002) and tinnitus annoyance (p = 0.014). In conclusion, implementation of phase-shifting did not lead to significant sound cancelling. Our results are discussed and compared to previous studies investigating the effects of phase-out in tinnitus patients.
Backward dispersion relations and pion-/sup 4/He phase-shift analyses
Dumbrajs, O V
1979-01-01
The usefulness of backward dispersion relations in nuclear physics is discussed. As an example, pion-/sup 4/He elastic scattering is considered. It is shown how the use of backward dispersion relations can help in reducing ambiguities of phase-shift analyses. In particular, the solution with the S-wave changing sign twice between 150 and 260 MeV and with the real part of the backward scattering amplitude becoming positive at approximately 140 MeV and exhibiting resonating behaviour has been suggested as the most probable one. (8 refs).
Spectral phase-shift detection of surface plasmon resonance
Duliakova, M.; Hlubina, P.; Ciprian, D.
2016-12-01
A two-step spectral interferometric technique to detect the spectral phase shift of surface plasmon resonance (SPR) in the Kretschmann configuration is proposed and demonstrated. The technique utilizes a polarimetry setup to record two channeled spectra, one including reflection of p- and s-polarized waves from an SPR structure for air when the SPR phenomenon does not occur, and the other one for an analyte when the SPR phenomenon occurs. The channeled spectra are used to detect the SPR spectral phase shift and first, an SF10 glass prism and a gold coated SF10 slide with a chromium adhesion layer is used to measure the SPR phase shift for aqueous solutions of ethanol. In addition, the position of a sharp maximum in the spectral derivative of the SPR phase shift is measured as a function of the analyte parameter. Second, the setup with a gold coated SF10 glass prism is used to measure the SPR phase shift for the same analyte. It is revealed that the detection accuracy of the measurement of the spectral derivative of the SPR phase shift in the second setup is lower than that in the first setup. For the first case, the measurements are accompanied by theoretical modeling of the SPR responses using the material dispersion characteristics.
Preparation of spin squeezed atomic states by optical phase shift measurement
Bouchoule, Isabelle; Moelmer, Klaus
2002-01-01
In this paper we present a state vector analysis of the generation of atomic spin squeezing by measurement of an optical phase shift. The frequency resolution is improved when a spin squeezed sample is used for spectroscopy in place of an uncorrelated sample. When light is transmitted through an atomic sample some photons will be scattered out of the incident beam, and this has a destructive effect on the squeezing. We present quantitative studies for three limiting cases: the case of a sampl...
Digital shearography with in situ phase shift calibration
Wu, Sijin; Zhu, Lianqing; Feng, Qibo; Yang, Lianxiang
2012-09-01
Precise measurement of the spatial derivative of displacement using digital shearography depends on well-calibrated phase shifts. However, due to time drift or a change in the position of the phase shifter, the previously calibrated results may not be applicable for the measurements. In this paper, we introduce a Michelson-interferometer-based digital shearographic setup, with an in situ phase shift calibration, that precisely measures the displacement derivatives. For the optical arrangement, a small number of optical parts are introduced into the existing Michelson interferometer to carry out the in situ calibration of the phase shifter. The calibration can be carried out anytime without changing the optical arrangement. This feature easily recalibrates the digital shearography, eliminating the influence of the phase shift error.
Binary phase-shift keying by coupling modulation of microrings.
Sacher, Wesley D; Green, William M J; Gill, Douglas M; Assefa, Solomon; Barwicz, Tymon; Khater, Marwan; Kiewra, Edward; Reinholm, Carol; Shank, Steven M; Vlasov, Yurii A; Poon, Joyce K S
2014-08-25
We propose a coupling-modulated microring in an add-drop configuration for binary phase-shift keying (BPSK), where data is encoded as 0 and π radian phase-shifts on the optical carrier. The device uses the π radian phase-flip across the zero coupling point in a 2 × 2 Mach-Zehnder interferometer coupler to produce the modulation. The coupling-modulated microring combines the drive power reduction of resonant modulators with the digital phase response of Mach-Zehnder BPSK modulators. A proof-of-concept device was demonstrated in silicon-on-insulator, showing differential binary phase-shift keying operation at 5 and 10 Gb/s.
Phase-shift correlation method for accurate phase difference estimation in range finder.
Liu, Yu-Zhou; Zhao, Bin
2015-04-10
High-precision phase-difference measurement is a key technology for a phase-shift laser range finder. In order to improve the estimation accuracy of phase difference between two sinusoidal signals with identical frequency, the phase-shift correlation method is described. Theoretical analysis shows that the conventional cross-correlation method will bring notable deviations when the true phase difference is close to 0° or 180° in the presence of noise. For reducing the influence of noise, two step calculations--phase-shift autocorrelation and phase-shift cross correlation--are used in the phase-shift correlation method. The estimation bias is eliminated by phase-shift autocorrelation in which the autocorrelation is calculated between the 2π phase-shifted signal and the original signal, and the periodic errors are eliminated by phase-shift cross correlation in which the phase difference is estimated when the true phase difference is near 90° or 270°. The effect of frequency drift on the phase difference is also discussed. The experiment results show that the maximum error of the conventional method is about 0.15°, while the estimation error of our proposed method is much less than 0.01° under the same conditions.
Arbel, Elad; Bilenca, Alberto
2015-07-01
Conventional low-magnification phase-contrast microscopy is an invaluable, yet a qualitative, imaging tool for the interrogation of transparent objects over a mesoscopic millimeter-scale field-of-view in physical and biological settings. Here, we demonstrate that introducing a compact, unbalanced phase-shifting Michelson interferometer into a standard reflected brightfield microscope equipped with low-power infinity-corrected objectives and white light illumination forms a phase mesoscope that retrieves remotely and quantitatively the reflection phase distribution of thin, transparent, and weakly scattering samples with high temporal (1.38 nm) and spatial (0.87 nm) axial-displacement sensitivity and micrometer lateral resolution (2.3 μm) across a mesoscopic field-of-view (2.25 × 1.19 mm2). Using the system, we evaluate the etch-depth uniformity of a large-area nanometer-thick glass grating and show quantitative mesoscopic maps of the optical thickness of human cancer cells without any area scanning. Furthermore, we provide proof-of-principle of the utility of the system for the quantitative monitoring of fluid dynamics within a wide region.
A difference phase-shift keying signal synchronizer
Makogon, V. P.; Kramar, VA
2017-01-01
The paper deals with a simultaneous implementation of the frame and bit synchronizations in the different phase-shift keying signal telecommunication networks. The synchronizer device model allowing synchronizing to the detection phase, taking into account the delivery of signals difference encoding, is presented.
Measurement of Phase Shift by Using a DSP
Directory of Open Access Journals (Sweden)
Petr KOČÍ
2009-06-01
Full Text Available The paper deals with design of the computer system for measurements of the phase shift between two harmonic signals using the Digital Signal Processor (DSP. The introducing part of the paper describes properties of the harmonic signals and the Hilbert transform. Concerning the Hilbert transform their two methods for computing, one is based on the Fourier transform while the second one benefits from the digital filters. The submitted paper deals with mentioned two methods for the phase evaluation as well. The phase shift between two harmonics signals is useful for rotors balancing. The algorithm of rotor balancing requires the amplitude of both the signals as well.
Resampling masks for phase-shifting digital holography
Zhang, Wenhui; Cao, Liangcai; Zhang, Hao; Zong, Song; Jin, Guofan
2016-10-01
Holographic imaging is degraded severely by the speckle or incoherent noise. In this work, resampling mask method based on phase-shifting digital holography is proposed to reduce the reconstruction noise. The zero-order and the conjugate term of the hologram can be eliminated with four-step phase-shifting digital holography (PSDH). The complex amplitude of the object after propagation can be calculated by the phase-shifting algorithm. A phase-only spatial light modulator is used to realize PSDH in the experiment. The complex amplitude is encoded into several parts by resampling masks. A high quality reconstruction image with low noise is achieved through the superposition of the individually reconstruction of coded complex amplitudes. The experiment data go well with the asymptotic function. This method can be used for digital holographic imaging of the biological samples and microstructures. Experimental results prove the feasibility of this proposed method.
Spin-electric Berry phase shift in triangular molecular magnets
Azimi Mousolou, Vahid; Canali, C. M.; Sjöqvist, Erik
2016-12-01
We propose a Berry phase effect on the chiral degrees of freedom of a triangular magnetic molecule. The phase is induced by adiabatically varying an external electric field in the plane of the molecule via a spin-electric coupling mechanism present in these frustrated magnetic molecules. The Berry phase effect depends on spin-orbit interaction splitting and on the electric dipole moment. By varying the amplitude of the applied electric field, the Berry phase difference between the two spin states can take any arbitrary value between zero and π , which can be measured as a phase shift between the two chiral states by using spin-echo techniques. Our result can be used to realize an electric-field-induced geometric phase-shift gate acting on a chiral qubit encoded in the ground-state manifold of the triangular magnetic molecule.
Polarization phase-shifting cyclic Jamin shearing interferometer
Wang, Lijuan; Liu, Liren; Sun, Jianfeng; Zhou, Yu; Dai, Enwen; Wu, Yapeng
2012-10-01
In the inter-satellite laser communication, the laser beam transmitted from the optical terminals is required to be highly collimated and its divergence approaches diffraction-limit. For testing the diffraction-limit wavefront, a polarization phase-shifting cyclic Jamin shearing interferometer is proposed. It is composed of a Jamin plate with a PBS film coated on its front surface, a right-angle prism reflecting beams two times, a shearing plate shearing beams by its rotation and a polarization phase shifter. The laser beam to be test is incident on the Jamin plate and gives rise to two interference beams with mutually perpendicular polarization directions by the PBS film. The two beams falls on the right-angle prism before or after passing through the shearing plate. With reflection of the right-angle prism, a cyclic Jamin shearing interferometric light path is formed. Two emitted beams go into the polarization phase shifter to obtain phase-shifting interferograms. In this interferometer, the cyclic interferometric light path can eliminate error of the surface profile of the optical element and the effect of environment. The interferometer has polarization phase shifting function and its fringe visibility is high. Therefore the interferometer can obtain high accuracy with variable shearing amount. In experiments, phase-shifting interferograms are obtained and the usefulness of the interferometer is verified.
Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton G.; Steenbergen, Wiendelt
2007-02-01
We describe path length resolved Doppler measurements of the multiply scattered light in turbid media using phase modulated low coherence Mach-Zehnder interferometer, with separate fibers for illumination and detection. A Doppler broadened phase modulation interference peak observed at the modulation frequency shows an increase in the average Doppler shift with optical path length. The path length dependent Doppler broadening of scattered light due to the detection of multiple scattered light is measured from the Lorentzian linewidth and the results are compared with the predictions of Diffusive Wave Spectroscopy. For particles with small scattering anisotropy, the diffusion approximation shows good agreement with our experimental results. For anisotropic scatterers, the experimental results show deviations from the Diffusion theory. The optical path lengths are determined experimentally from the Zero order moment of the phase modulation peak around the modulation frequency and the results are validated with the Monte Carlo technique.
Imbert-Fedorov shift in Weyl semimetals: Dependence on monopole charge and intervalley scattering
Wang, Luyang; Jian, Shao-Kai
2017-09-01
The Imbert-Fedorov (IF) shift in optics describes the transverse shift of light beams at the reflection interface. Recently, the IF shift of Weyl fermions at the interface between Weyl semimetals (WSMs) with single monopole charge has been studied. Here, we study the IF shift at the interface between two WSMs, each of which is carrying an arbitrary integer monopole charge. We find a general relation between the monopole charges of the two WSMs and the IF shift. In particular, the IF shift is proportional to the monopole charge if both WSMs have the same one. Our results can be used to infer the topology of the materials by experimentally measuring their IF shift. Furthermore, we consider the possibility that the Weyl fermions are scattered to other Weyl cones during the reflection, which results in qualitatively different behavior of the IF shift. While we use a quantum mechanical approach to solve the problem, semiclassical equations of motion and the conservation of total angular momentum can help us intuitively interpret our results in special cases.
Regente, J; de Zeeuw, J; Bes, F; Nowozin, C; Appelhoff, S; Wahnschaffe, A; Münch, M; Kunz, D
2017-05-01
In single night shifts, extending habitual wake episodes leads to sleep deprivation induced decrements of performance during the shift and re-adaptation effects the next day. We investigated whether short-wavelength depleted (=filtered) bright light (FBL) during a simulated night shift would counteract such effects. Twenty-four participants underwent a simulated night shift in dim light (DL) and in FBL. Reaction times, subjective sleepiness and salivary melatonin concentrations were assessed during both nights. Daytime sleep was recorded after both simulated night shifts. During FBL, we found no melatonin suppression compared to DL, but slightly faster reaction times in the second half of the night. Daytime sleep was not statistically different between both lighting conditions (n = 24) and there was no significant phase shift after FBL (n = 11). To conclude, our results showed positive effects from FBL during simulated single night shifts which need to be further tested with larger groups, in more applied studies and compared to standard lighting. Copyright © 2016 Elsevier Ltd. All rights reserved.
New type high-index dielectric nanosensors based on the scattering intensity shift
Yan, Jiahao; Liu, Pu; Lin, Zhaoyong; Yang, Guowei
2016-03-01
Sensing is regarded as one of the most important applications of noble metal-based nanoplasmonics. However, all previous designs have been based on the wavelength-shift of the localized surface plasmon resonance, in which the sensitivity is intrinsically limited by the low quality factors induced by metal losses, and meanwhile the large ohmic loss, high cost and inevitable toxicity and biofouling for detection in vivo greatly hinder their further applications in biosensors. Beyond noble metals, high-refractive index dielectric materials (HRDMs) like silicon with low-loss and strong magnetic response have drawn more attention. Here, for the first time, we proposed a HRDM nanosphere as a new nanosensor for biomolecule detection, and experimentally demonstrated a HRDM sensor working on the intensity-shift but not wavelength-shift of the scattering. The sensing mechanism based on the synergistic effect of the broadening electric mode shift of HRDMs and the Kerker's scattering intensity-shift is beneficial to achieve higher sensitivity. We validated the efficacy of our sensor to detect refractive index changes and trace amounts of streptavidin molecules, and the sensitivity can reach 27 times as high as the highest sensitivity reported to date for nanoplasmonic structures. These findings showed that monitoring the change of the scattering intensity of HRDM nanostructures is superior to monitoring the wavelength-shift of nanoplasmonic structures, as is widely used in nanoplasmonic sensors, for biosensing, meaning HRDM nanosensors could be an important tool in biomolecule detection.Sensing is regarded as one of the most important applications of noble metal-based nanoplasmonics. However, all previous designs have been based on the wavelength-shift of the localized surface plasmon resonance, in which the sensitivity is intrinsically limited by the low quality factors induced by metal losses, and meanwhile the large ohmic loss, high cost and inevitable toxicity and
Singular-value demodulation of phase-shifted holograms.
Lopes, Fernando; Atlan, Michael
2015-06-01
We report on phase-shifted holographic interferogram demodulation by singular-value decomposition. Numerical processing of optically acquired interferograms over several modulation periods was performed in two steps: (1) rendering of off-axis complex-valued holograms by Fresnel transformation of the interferograms; and (2) eigenvalue spectrum assessment of the lag-covariance matrix of hologram pixels. Experimental results in low-light recording conditions were compared with demodulation by Fourier analysis, in the presence of random phase drifts.
AC system stabilization via phase shift transformer with thyristor commutation
Energy Technology Data Exchange (ETDEWEB)
Oliveira, Jose Carlos de; Guimaraes, Geraldo Caixeta; Moraes, Adelio Jose [Uberlandia Univ., MG (Brazil); Abreu, Jose Policarpo G. de [Escola Federal de Engenharia de Itajuba, MG (Brazil); Oliveira, Edimar Jose de [Juiz de Fora Univ., MG (Brazil)
1994-12-31
This article aims to present initially the constructive and operative forms of a phase-shift autotransformer which provides both magnitude and phase angle change through thyristor commutation, including a technic to reduce the number of thyristors. Following, it is proposed a control system to make such equipment an efficient AC system stabilizing tool. It is presented some simulation results to show the operation of this transformer in an electrical system. (author) 3 refs., 11 figs., 3 tabs.
Phase rotation symmetry and the topology of oriented scattering networks
Delplace, Pierre; Fruchart, Michel; Tauber, Clément
2017-05-01
We investigate the topological properties of dynamical states evolving on periodic oriented graphs. This evolution, which encodes the scattering processes occurring at the nodes of the graph, is described by a single-step global operator, in the spirit of the Ho-Chalker model. When the successive scattering events follow a cyclic sequence, the corresponding scattering network can be equivalently described by a discrete time-periodic unitary evolution, in line with Floquet systems. Such systems may present anomalous topological phases where all the first Chern numbers are vanishing, but where protected edge states appear in a finite geometry. To investigate the origin of such anomalous phases, we introduce the phase rotation symmetry, a generalization of usual symmetries which only occurs in unitary systems (as opposed to Hamiltonian systems). Equipped with this new tool, we explore a possible explanation of the pervasiveness of anomalous phases in scattering network models, and we define bulk topological invariants suited to both equivalent descriptions of the network model, which fully capture the topology of the system. We finally show that the two invariants coincide, again through a phase rotation symmetry arising from the particular structure of the network model.
Wave and ray analysis of a type of cloak exhibiting magnified and shifted scattering effect
Luo, Yu; Zhang, Jingjing; Chen, Hongsheng; Wu, Bae-Ian; Ran, Lixin; Kong, Jin Au
2009-01-01
Ray-tracing exercise and full-wave analysis were performed to validate the performance of a new type of cloak composed of isotropic metamaterials. It is shown that objects inside the folded region of this cloak appear invisible to the incoming light from a ray tracing exercise, but exhibit magnified and shifted scattering under a plane wave illumination from a full wave analysis. Gaussian beams are introduced to resolve this interesting paradox resulted from these two methods. We show that at...
Interpretation of sonotubometric data based on phase-shift detection.
Amoako-Tuffour, Yaw; Garland, Philip; Bance, Manohar
2016-06-10
Sonotubometry is a non-invasive means of assessing Eustachian tube (ET) function. Its interpretation remains a complex task with questionable results due to wide variation between trials. A study was conducted to ascertain whether the measurement of phase shift in sonotubometric signals would be a more reliable indicator of ET patency than fluctuating Sound Pressure Level (SPL). The ears of six healthy participants and two participants with patulous ET (PET) were probed with a 100 Hz signal. Five recordings of SPL were performed at the external auditory canal. Cross-correlation was performed among filtered SPL signals and among extracted phase shift waveforms. Peak coefficients were averaged to provide a measure of waveform similarity between trials. Mean peak cross correlation coefficient for SPL signal measured 0.603 ± 0.057 Standard Error of Mean (SEM) whilst that for Phase-Shift signal measured 0.884 ± 0.027 (SEM). All normal participants demonstrated an observable phase change between the ear and nasal signal during swallowing indicating an acoustic impedance change during the event. For the PET patients tested, the phase measurements in ear and nasal signals follow one another reasonably closely, indicating little or no impedance change during swallowing. It is thought that this impedance change is indicative of opening of the ET in normal patients, and the lack impedance change indicates ET either remaining open or remaining closed throughout the swallow. Experimental data suggest that phase-shift detection is a more consistent means of interpreting sonotubometric data than SPL analysis.
A novel phase shift technique in shearography for NDT
Directory of Open Access Journals (Sweden)
Gao J.
2010-06-01
Full Text Available Digital shearography (DS is a whole-field non-contacting optical method for nondestructive testing (NDT of subsurface flaws and strain measurement. In this paper, we describe a novel phaseshifting technique in DS for nondestructive evaluation (NDE and NDT of quasi dynamic behaviour of objects subject to varying loads. A Wollaston lens, a precise wave plate device and a polariser are employed to introduce constant phase differences between two shearing wavefronts. The wave plate device is in front of the polariser, which has a transmissive wavefront distortion of less than 1/8 wavelength. Phase difference can be adjusted by rotating the polariser. The rotation for angle adjusting can be easily carried out according to the requirement of the phase shifting. In this technique, the phase shifting is performed only on the static images of the object before deformation or loading. By setting the angle of the polariser to 0º, -60º and 60º, three speckle patterns with the defined phase differences are captured, and are referred to as initial speckle patterns I1,0, I1,-60 and I1,60. Afterwards, the polariser is reset to 0º before loading. The speckle pattern I0 is treated as a base pattern, and will be subtracted from the subsequent speckle patterns which are captured in the quasi dynamic deformation process. During the quasi dynamic deformation process, the optical path and the entire optical set-up will be kept unchanged, and a series of speckle patterns (Im,0, m=2,3,….. which carry the deformation information will be quickly captured. In the meantime, fast image subtractions will be performed. The speckle fringes (Im,0 -I1,0 will be displayed in real-time. In detailed post-processing, phase of differences method (PDM [1] is used to extract phase information from the speckle images Im,0 -I1,0, I1,0, I1,-60 and I1,60. Specifically, when a three phase step technique is employed, the phase of the fringe pattern (Im,0-I1,0 can be calculated from (Im
A novel phase shift technique in shearography for NDT
Liu, Z.; Gao, J.
2010-06-01
Digital shearography (DS) is a whole-field non-contacting optical method for nondestructive testing (NDT) of subsurface flaws and strain measurement. In this paper, we describe a novel phaseshifting technique in DS for nondestructive evaluation (NDE) and NDT of quasi dynamic behaviour of objects subject to varying loads. A Wollaston lens, a precise wave plate device and a polariser are employed to introduce constant phase differences between two shearing wavefronts. The wave plate device is in front of the polariser, which has a transmissive wavefront distortion of less than 1/8 wavelength. Phase difference can be adjusted by rotating the polariser. The rotation for angle adjusting can be easily carried out according to the requirement of the phase shifting. In this technique, the phase shifting is performed only on the static images of the object before deformation or loading. By setting the angle of the polariser to 0º, -60º and 60º, three speckle patterns with the defined phase differences are captured, and are referred to as initial speckle patterns I1,0, I1,-60 and I1,60. Afterwards, the polariser is reset to 0º before loading. The speckle pattern I0 is treated as a base pattern, and will be subtracted from the subsequent speckle patterns which are captured in the quasi dynamic deformation process. During the quasi dynamic deformation process, the optical path and the entire optical set-up will be kept unchanged, and a series of speckle patterns (Im,0, m=2,3,…..) which carry the deformation information will be quickly captured. In the meantime, fast image subtractions will be performed. The speckle fringes (Im,0 -I1,0) will be displayed in real-time. In detailed post-processing, phase of differences method (PDM) [1] is used to extract phase information from the speckle images Im,0 -I1,0, I1,0, I1,-60 and I1,60. Specifically, when a three phase step technique is employed, the phase of the fringe pattern (Im,0-I1,0) can be calculated from (Im,0 -I1,0)+ I1
Precision phase-shifting applied to fiber Bragg gratings
DEFF Research Database (Denmark)
Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin
2005-01-01
A simple method of displacing a holographic interferogram within a waveguide based on translation along a slightly tilted fringe pattern of the optical interferogram is presented. By way of example, phase-shifted fibre gratings are produced this way. The spatial resolution in fringe shift is sepa...... is separated from the physical spatial displacement of the optical elements and determined primarily by the fringe tilt angle. This relaxes the tolerances in optical components required and can potentially enable spatial displacements as small as 1 nm/@mm to be realised....
Quantum Theory of Reactive Scattering in Phase Space
Goussev, A.; Schubert, R.; Waalkens, H.; Wiggins, S.; Nicolaides, CA; Brandas, E
2010-01-01
We review recent results on quantum reactive scattering from a phase space perspective. The approach uses classical and quantum versions of Poincare-Birkhoff normal form theory and the perspective of dynamical systems theory. Over the past 10 years the classical normal form theory has provided a
Transcriptional regulation in yeast during diauxic shift and stationary phase.
Galdieri, Luciano; Mehrotra, Swati; Yu, Sean; Vancura, Ales
2010-12-01
The preferred source of carbon and energy for yeast cells is glucose. When yeast cells are grown in liquid cultures, they metabolize glucose predominantly by glycolysis, releasing ethanol in the medium. When glucose becomes limiting, the cells enter diauxic shift characterized by decreased growth rate and by switching metabolism from glycolysis to aerobic utilization of ethanol. When ethanol is depleted from the medium, cells enter quiescent or stationary phase G(0). Cells in diauxic shift and stationary phase are stressed by the lack of nutrients and by accumulation of toxic metabolites, primarily from the oxidative metabolism, and are differentiated in ways that allow them to maintain viability for extended periods of time. The transition of yeast cells from exponential phase to quiescence is regulated by protein kinase A, TOR, Snf1p, and Rim15p pathways that signal changes in availability of nutrients, converge on transcriptional factors Msn2p, Msn4p, and Gis1p, and elicit extensive reprogramming of the transcription machinery. However, the events in transcriptional regulation during diauxic shift and quiescence are incompletely understood. Because cells from multicellular eukaryotic organisms spend most of their life in G(0) phase, understanding transcriptional regulation in quiescence will inform other fields, such as cancer, development, and aging.
Optimized polynomial expansions: potentials and phase shift analyses
Energy Technology Data Exchange (ETDEWEB)
Marker, D.; Rijken, T.; Bohannon, G.; Signell, P.
1980-03-18
The Cutkosky-Deo-Ciulli-Chao Optimized Polynomial Expansion as applied to the proton-proton scattering amplitudes was examined. Chao's positive numerical results for intermediate energy scattering data could not be reproduced. Instead, a negative conclusion as to the method's usefulness for that application was reached. Source(s) of the discrepancies with Chao's results could not be located definitely, but there were indications of a problem with a relative phase. The ability of the method to predict the higher angular momentum parts of the amplitudes for three different potentials having realistic parts was also examined. Again, the method was found to have very meager successes. 7 tables.
Phase shift reflectometry for sub-surface defect detection
Asundi, Anand; Lei, Huang; Eden, Teoh Kang Min; Sreemathy, Parthasarathy; May, Watt Sook
2012-11-01
Phase Shift Reflectometry has recently been seen as a novel alternative to interferometry since it can provide warpage measurement over large areas with no need for large optical components. To confirm its capability and to explore the use of this method for sub-surface defect detection, a Chinese magic mirror is used. This bronze mirror which dates back to the Chinese Han Dynasty appears at first sight to be an ordinary convex mirror. However, unlike a normal mirror, when illuminated by a beam of light, an image is formed onto a screen. It has been hypothesized that there are indentations inside the mirror which alter the path of reflected light rays and hence the reflected image. This paper explores various methods to measure these indentations. Of the methods test Phase Shift Reflectometry (PSR) was found suitable to be the most suitable both in terms of the sensitivity and the field of view.
Pulsed photothermal phase-shift spectroscopy for weak absorption measurement.
Li, B; Deng, Y; Cheng, J
1996-04-01
A novel photothermal phase-shift spectroscopy configuration based on the retro-reflected beam interference has been developed and its operational principle is described. The weak absorption measurement ability of this technique is experimentally proven with a water/ethanol solution of standard Pyronine G dye and the limit of detection is found to be 1.8 x 10(-6) absorbance. Potential applications of the technique are discussed.
Effect of local absorption changes on phase-shift measurement using phase modulation spectroscopy
Cui, Weijia; Ostrander, Lee E.
1993-09-01
Recently, researchers have used phase modulation of photons (PMP) at near infrared wavelengths to assess in vivo tissue blood perfusion. The incident light intensity is amplitude modulated in the megahertz to gigahertz range and the phase shift is measured at the detector for the photon waves that have migrated through biological tissue. The obtained phase shift is related to the pathlength for the detected photons. In the past, the models for this process have not considered the effect upon phase produced by inhomogeneities within the in vivo tissue. The phase shift is a function of the distribution of the optical properties within the medium. We used a simple experimental model to investigate the effect upon phase shift of the location for optical changes. A mathematical model has been developed to describe this effect. The results demonstrate that a measured phase shift depends upon the location at which the optical properties are changed, as well as upon the magnitude of change in the optical properties. In vivo tissue is inhomogeneous so that its optical properties are also inhomogeneous. It is therefore important to consider the optical property distribution of the in vivo tissue when assessing blood perfusion using phase modulation measurements.
Phase-shift- and phase-filtering-based surface-wave suppression method
Wang, De-Ying; Ling, Yun
2016-12-01
Aliased surface waves are caused by large-space sampling intervals in threedimensional seismic exploration and most current surface-wave suppression methods fail to account for. Thus, we propose a surface-wave suppression method using phase-shift and phase-filtering, named the PSPF method, in which linear phase-shift is performed to solve the coupled problem of surface and reflected waves in the FKXKY domain and then used phase and FKXKY filtering to attenuate the surface-wave energy. Processing of model and field data suggest that the PSPF method can reduce the surface-wave energy while maintaining the low-frequency information of the reflected waves.
Energy Technology Data Exchange (ETDEWEB)
Montagut, Y. J.; Garcia, J. V.; Jimenez, Y.; Arnau, A. [Grupo de Fenomenos Ondulatorios, Departamento de Ingenieria Electronica, Universitat Politecnica de Valencia (Spain); March, C.; Montoya, A. [Instituto Interuniversitario de Investigacion en Bioingenieria y Tecnologia Orientada al Ser Humano, Universitat Politecnica de Valencia (Spain)
2011-06-15
The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequency/mass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed.
Binary encoded computer generated holograms for temporal phase shifting.
Amphawan, Angela
2011-11-07
The trend towards real-time optical applications predicates the need for real-time interferometry. For real-time interferometric applications, rapid processing of computer generated holograms is crucial as the intractability of rapid phase changes may compromise the input to the system. This paper introduces the design of a set of binary encoded computer generated holograms (CGHs) for real-time five-frame temporal phase shifting interferometry using a binary amplitude spatial light modulator. It is suitable for portable devices with constraints in computational power. The new set of binary encoded CGHs is used for measuring the phase of the generated electric field for a real-time selective launch in multimode fiber. The processing time for the new set of CGHs was reduced by up to 65% relative to the original encoding scheme. The results obtained from the new interferometric technique are in good agreement with the results obtained by phase shifting by means of a piezo-driven flat mirror.
Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Almaiman, Ahmed; Cao, Yinwen; Chitgarha, Mohammad Reza; Paraschis, Loukas; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Touch, Joseph D; Willner, Alan E
2015-11-01
An eight-phase-shift-keying signal is experimentally de-aggregated onto two four-pulse amplitude modulation signals using nonlinear processes in optical elements. Quadrature-phase-shift-keying signals are similarly de-multiplexed into two binary phase shift keying signals by mapping the data points onto the constellation axes. De-multiplexing performance is evaluated as a function of the optical signal-to-noise ratio of the incoming signals. The effect of phase noise is also studied.
Origin of the frequency shift of Raman scattering in chalcogenide glasses
DEFF Research Database (Denmark)
Han, X.C.; Tao, H.Z.; Gong, L.J.
2014-01-01
of the shift is associated with the topological connectivity of global network and/or the local environment of structural units, (e.g., tetrahedral GeSe4). Here we show the compositional evolution of the main Raman scattering frequency in Ge(SxSe1−x)2 glasses, and then clarify its structural origin. We keep...... units such as GeS4 tetrahedra. The ab-initio calculations of normal Raman mode combined with group theory analysis provide insight into the structural evolution of chalcogenide glasses with varying composition....
Exercise elicits phase shifts and acute alterations of melatonin that vary with circadian phase.
Buxton, Orfeu M; Lee, Calvin W; L'Hermite-Baleriaux, Mireille; Turek, Fred W; Van Cauter, Eve
2003-03-01
To examine the immediate phase-shifting effects of high-intensity exercise of a practical duration (1 h) on human circadian phase, five groups of healthy men 20-30 yr of age participated in studies involving no exercise or exposure to morning, afternoon, evening, or nocturnal exercise. Except during scheduled sleep/dark and exercise periods, subjects remained under modified constant routine conditions allowing a sleep period and including constant posture, knowledge of clock time, and exposure to dim light intensities averaging (+/-SD) 42 +/- 19 lx. The nocturnal onset of plasma melatonin secretion was used as a marker of circadian phase. A phase response curve was used to summarize the phase-shifting effects of exercise as a function of the timing of exercise. A significant effect of time of day on circadian phase shifts was observed (P exercise to the first onset after exercise, circadian phase was significantly advanced in the evening exercise group by 30 +/- 15 min (SE) compared with the phase delays observed in the no-exercise group (-25 +/- 14 min, P evening exercise exposure were attenuated on the second day after exercise exposure and no longer significantly different from phase shifts observed in the absence of exercise. Unanticipated transient elevations of melatonin levels were observed in response to nocturnal exercise and in some evening exercise subjects. Taken together with the results from previous studies in humans and diurnal rodents, the current results suggest that 1) a longer duration of exercise exposure and/or repeated daily exposure to exercise may be necessary for reliable phase-shifting of the human circadian system and that 2) early evening exercise of high intensity may induce phase advances relevant for nonphotic entrainment of the human circadian system.
Nondestructive testing and evaluation using phase-shifting electronic shearography
Xie, L.; Chau, Fook S.; Toh, Siew-Lok
1997-03-01
In this paper, a phase shifting electronic shearography technique and its application in non-destructive testing (NDT) is described. Electronic shearography or Digital Speckle Shearing Interferometry (DSSI) has found applications as an NDT tool in industrial environments due to its less stringent vibration isolation requirement and simple optical set-up. Moreover, it relies on changes in displacement gradient and so measurements are not masked by overall movement of the specimen. One of the main problems in DSSI is that it is not easy to obtain high-contrast fringe patterns under certain conditions. To solve the problem, an applicable computer- controlled phase shift technique is developed and is shown to yield good quality phase contours of a deformed object. In addition, it allows the displacement derivative at all points on the object to be quantified. This capability leads to the easy and rapid determination of the location, size, and shape of a defect. Experimental results of detection of internal flaws in pipes based on the above system are presented.
Joint Multilevel Turbo Equalization and Continuous Phase Frequency Shift Keying
Directory of Open Access Journals (Sweden)
Odabasioglu Niyazi
2008-01-01
Full Text Available A novel type of turbo coded modulation scheme, called multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK, is designed to improve the overall bit error rate (BER and bandwidth efficiency. Then, this scheme is combined with a new double decision feedback equalizer (DDFE to remove the interference and to enhance BER performance for the intersymbol interference (ISI channels. The entire communication scheme is called multilevel turbo equalization-continuous phase frequency shift keying (MLTEQ-CPFSK. In these schemes, parallel input data sequences are encoded using the multilevel scheme and mapped to CPFSK signals to obtain a powerful code with phase continuity over the air. The performances of both MLTC-CPFSK and MLTEQ-CPFSK systems were simulated over nonfrequency and frequency-selective channels, respectively. The superiority of the two level turbo codes with 4CPFSK modulation is shown against the trellis-coded 4CPFSK, multilevel convolutional coded 4CPFSK, and TTCM schemes. Finally, the bit error rate curve of MLTEQ-CPFSK system over Proakis B channel is depicted and ISI cancellation performance of DDFE equalizer is shown against linear and decision feedback equalizers
Phase-shifting optical fiber sensing with rectangular-pulse binary phase modulation
Ren, Zhongjie; Li, Jianxin; Zhu, Rihong; Cui, Ke; He, Qing; Wang, Hailin
2018-01-01
We propose and demonstrate a new method of phase-shifting optical fiber sensing, wherein rectangular-pulse binary phase modulation is imposed on the laser source of an interferometric fiber optic sensor to generate three phase-shifting steps of - π / 2 , 0, and π/2 radians at the output, and the phase shifts that carry the vibration signals are demodulated with an orthogonal demodulation algorithm. This approach offers the advantages of high efficiency and low complexity because it is simple in design and implementation. Moreover, this method can be applied to successfully realize the demodulation of multiplexed systems based on different multiplexing techniques. The techniques are theoretically analyzed and experimentally demonstrated with recovering the sinusoid wave applied to the sensor. Also, in this paper, a simple multiplexed system is proposed and discussed.
Phase-shifted real-time laser feedback interferometry
Ovryn, Ben; Andrews, James H.; Eppell, Steven J.; Khaydarov, John D.
1996-07-01
We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio over a broad range of sample reflectance. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Cane or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured and, as with other forms of PSI, there is no sign ambiguity to the displacement measurement. We have also analyzed the behavior ofthe interferometer for both low and high reflectivity samples. Since the change in the laser's intensity is a non-linear function of the reflected amplitude, additional measures are required before applying PSI methods to high reflectivity samples.
Application of Phase Shifted, Laser Feedback Interferometry to Fluid Physics
Ovryn, Ben; Eppell, Steven J.; Andrews, James H.; Khaydarov, John
1996-01-01
We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio even for low reflectivity samples. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Carre or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured. We have combined our interferometer with a commercial microscope and scanning piezoelectric stage and have measured the variation in OPL and visibility for drops of PDMS (silicone oil) on coated single crystal silicon. Our measurement of the static contact angle agrees with the value of 68 deg stated in the literature.
Full Range ZVS Phase Shifted Power Converter with "Poles"
Bordry, Frederick
1998-01-01
The study and development of a quasi-resonant power converter, with Full Bridge - PhaseShifted - Pulse Width Modulation (FB-PS-PWM) topology is presented. The originality of thepaper is the adding of resonant networks (poles) on each leg to get soft commutation (ZeroVoltage Switching ZVS) over the full range of the output current. The design of the polestructure and the component ratings are described. Simulations and a [1000A-15V] converterprototype, using dual-thyristor, validate the theoretical studies.
Temperature dependence of scattering phases and Friedel phase discontinuity in quantum wires
Vargiamidis, Vassilios; Fessatidis, Vassilios
2011-07-01
Two important issues concerning the scattering phases in a quantum wire with an attractive scatterer are investigated. We consider the case of two quasibound states which couple to a scattering channel and give rise to two Fano resonances. First, we examine the effects of temperature on the phase of the transmission amplitude and the Friedel phase. It is shown that temperature effects tend to smear sharp features of the transmission phase; namely, the phase drops become less than π, and acquire finite widths which increase linearly in the low-temperature regime. The influence of temperature on the Friedel phase and density of states becomes stronger as the Fano resonance becomes narrower. Second, we examine the behavior of the Friedel phase when the energy of the incident electron crosses an infinitely narrow Fano resonance, forming bound state in the continuum. It is shown that the Friedel phase exhibits abrupt jump of π at this energy. We discuss this odd behavior in relation to the Friedel sum rule and point out its consequences on the charge in the scattering region.
Scattering phases for meson and baryon resonances on general moving-frame lattices
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Lage, M.; Rusetsky, A. [Bonn Univ. (Germany). Helmholtz-Inst. fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics; Meissner, U.G. [Bonn Univ. (Germany). Helmholtz-Inst. fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics; Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik; Forschungszentrum Juelich (Germany). Juelich Center for Hadron Physics and JARA - High Performance Computing; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ., SA (Australia). CSSM, School of Chemistry and Physics
2012-06-15
A proposal by Luescher enables one to compute the scattering phases of elastic two-body systems from the energy levels of the lattice Hamiltonian in a finite volume. In this work we generalize the formalism to S-, P- and D-wave meson and baryon resonances, and general total momenta. Employing nonvanishing momenta has several advantages, among them making a wider range of energy levels accessible on a single lattice volume and shifting the level crossing to smaller values of m{sub {pi}}L.
A Simulation Study of the Effect of Phase-Shift on Dual Gated Myocardial Perfusion ECT.
Lee, Taek-Soo; Park, Min Jae; Tsui, Benjamin M W
2011-10-01
We evaluated the effect of relative phase-shift of cardiac and respiratory (C&R) motions in myocardial perfusion (MP) ECT. Previously, we generated a set of realistic 3D XCAT (eXtended CArdiac Torso) phantoms that model simultaneous C&R motions for use in the study of new data acquisition methods and corrective image reconstruction techniques for improved gated MP ECT, including PET and SPECT. The respiratory motion (RM) over a respiration cycle was modeled using 24 equally-spaced time frames while the cardiac beating motion (CBM) over a cardiac cycle was divided into 48 equally-spaced time frames for each of the 24 RM phases. Almost noise-free projection datasets were generated separately from the heart, blood pool, lungs, liver, kidneys, stomach, gall bladder and remaining body at each of the 24 × 48 time points using Monte Carlo simulation techniques that include the effect of collimator detector response, photon attenuation and scatter. To demonstrate the effect of relative phase-shift, a typical (99m)Tc Sestamibi MP SPECT projection dataset were generated. They were then scaled and combined to model different degrees of relative C&R phase shifting and grouped into 6 respiratory-gates with 8 cardiac-gates. Each projection was reconstructed using a 3D OS-EM without and with attenuation correction using an averaged and phase-mismatched gated attenuation maps. The image artifacts of the reconstructed images were compared by visual inspection of the MP polar maps. The results showed significant changes of artifactual non-uniformity in the polar maps for off-phase of RM compared to those of CBM. The changes in the polar maps also demonstrated the effect of phase shifting accordingly. We conclude that the 4D XCAT phantom dataset with simultaneous C&R motions provides a powerful tool in the study of the effects of C&R motions with relative phase shifts, and development of C&R gating schemes and motion correction methods for improved ECT/CT imaging.
Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian
2016-10-24
Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence.
A Neutron Scattering Kernel of Solid Methane in phase II
Shin, Yunchang; Snow, William Michael; Liu, Cnen-Yu; Lavelle, Christopher M.; Baxter, David V.
2008-04-01
A neutron scattering cross section model of solid methane was studied for the cold neutron moderator of Low Energy Neutron Source (LENS) at IUCF/Indiana University especially in temperature range of 20.4 4K. The analytical scattering kernel was adapted from Ozaki.et al .[1][2] to describe molecular rotation in this temperature range. This model includes a molecular translation and intra-molecular vibration as well as the rotational degree of freedom in effective ways. For more broad applications into monte carlo simulations, neutron scattering libraries for MCNP were produced from the frequency spectrums using NJOY code. We have tested this newly- developed scattering kernels for phase II solid methane by calculating the neutron spectral intensity expected from the methane moderator at the LENS neutron source using MCNP. The predictions are compared to the measured energy spectra. The simulations agree with the measurement data at both temperatures. The simulation results show good agreement with measurement data in different temperatures. [1] Y. Ozaki, Y. Kataoka, and T. Yamamoto, The Journal of Chemical Physics 73, 3442 (1980). [2] Y. Ozaki, Y. Kataoka, K. Otaka, and T. Yamamoto, Can. J. Physics. 59, 275 (1981).
Latychevskaia, Tatiana
2015-01-01
We address the problem of reconstructing phase-shifting objects from their single shot in-line holograms. We show that a phase-shifting object cannot be reliably recovered from its in-line hologram by conventional reconstruction routines but that an iterative reconstruction should be applied. We demonstrate examples of simulated in-line holograms of objects with the following properties: purely absorbing, both absorbing and phase shifting, and strong phase-shifting. We investigate the effects of noise and interference resolution in holograms on the reconstruction results and discuss details of an optimal iterative procedure to quantitatively recover the correct absorbing and phase-shifting properties of the object. We also review previously published reconstructions of experimental holograms and summarize the optimal parameters for retrieval of phase-shifting objects from their in-line holograms.
Phase measurement of light absorption and scatter in human tissue
Chance, B.; Cope, M.; Gratton, E.; Ramanujam, N.; Tromberg, B.
1998-10-01
Analog and digital technologies are presented for precise measurement of propagation delay of photons from source and detector placed on portions of the human body. The goal of the apparatus design is to quantify absorption (μa) and scattering (μs') induced by biological pigments and biological structures, respectively. Body tissues are highly scattering with a mean distance between scatterers of less than a mm (at 700-850 nm). Significant absorption is mainly due to 5%-10% of the tissue volume occupied by blood. Measurement of μa and μs' is done by both time and frequency domain equipment. This article focuses upon frequency domain equipment because of its simplicity, reduced noise bandwidth, versatility, and the strong analogy to very high frequency/ultrahigh frequency communication devices, particularly those using phase modulation. Comparisons are made of homodyne and heterodyne systems together with evaluation of single and multiple side band systems, with particular emphasis on methods for multiplexed optical and radio frequencies by frequency encoding or time-sharing technologies. The applications of these phase modulation systems to quantitative brain and muscle blood oximetry, functional activity of the forebrain, and other important problems of medical science, are presented.
Takada, Kazumasa; Aoyagi, Hirotaka; Okamoto, Katsunari
2011-04-01
We report that a spectrum can be retrieved with a planar waveguide spatial heterodyne spectrometer (SHS) incorporating an active phase-shift scheme, where the phase shifts are distributed around π/2. This was confirmed experimentally with an SHS that had 32 interleaved Mach-Zehnder interferometers and whose free spectral range was 625 GHz. The phase shifts ranged from 0.71 to 2.2 rad against the target of π/2 rad.
Chromatic-dispersion measurement by modulation phase-shift method using a Kerr phase-interrogator.
Baker, Chams; Lu, Yang; Bao, Xiaoyi
2014-09-22
We present a novel approach for the measurement of chromatic-dispersion in long optical fibers using a modulation phase-shift method based on a Kerr phase-interrogator. This approach utilizes a Kerr phase-interrogator to measure the phase variation of a sinusoidal optical signal induced by traveling in a fiber under test as the laser carrier wavelength and the sinusoidal signal frequency are varied. Chromatic-dispersion measurement for several fibers including a standard single-mode silica fiber and a dispersion-shifted fiber is experimentally demonstrated. The ultrafast response of the Kerr phase-interrogator opens the way for real-time monitoring of chromatic-dispersion in kilometers-long optical fibers.
A three-step least-squares iterative method for tilt phase-shift interferometry.
Liu, Qian; Wang, Yang; Ji, Fang; He, Jianguo
2013-12-02
An iterative method based on least-squares fittings is proposed to retrieve wavefront phase from tilt phase-shift interferograms. In each iteration cycle, proposed method calculates wavefront phase and tilt phase shifts in x- and y-directions in three individual least-squares fitting steps. In tilt phase shifts extracting steps, phase shifts of interferograms columns or rows are calculated with least-squares method, and then tilt phase shifts of interferograms in x- or y-direction are determined by linear regressions. At least three interferograms of three by three pixels are required with proposed method. The performance of proposed method is demonstrated by simulations and experiments. Tilt gradients and translational phase shifts could be extracted with high accuracy and large wavefront tilts could be well handled with proposed method. The method could be applied to temporal phase-shift interferometers with uncalibrated transducers or that in vibrating environment.
RC Oscillators with Two Operational Amplifiers with Precision Phase Shift between Two Outputs
Horsky, P.
1996-01-01
In some instruments oscillator with precision 90Ã‚Â° phase shift of output signals is needed. In this article a new type of RC oscillators with precision 90Ã‚Â° phase shift between two low impedance output signals is described. This phase shift does not depend on tolerances of RC networks used.
Potential energy function information from quantum phase shift using the variable phase method.
Lemes, Nelson H T; Braga, João P; Alves, Márcio O; Costa, Éderson D'M
2014-07-01
The present work discusses quantum phase shift sensitivity analysis with respect to the potential energy function. A set of differential equations for the functional derivative of the quantum phase shift with respect to the potential energy function was established and coupled with the variable phase equation. This set of differential equations provides a simple, exact and straightforward way to establish the sensitivity matrix. The present procedure is easier to use than the finite difference approach, in which several direct problems have to be addressed. Furthermore, integration of the established equations can be used to demonstrate how the sensitivity phase shift is accumulated as a function of the interatomic distance. The potential energy function was refined to produce a better quality function. The average error on the phase shift decreased from 9.8% in the original potential function to 0.13% in the recovered potential. The present procedure is an important initial step for further work towards recovering potential energy functions in upper dimensions or to recovering this function from cross sections.
Energy Technology Data Exchange (ETDEWEB)
Bychkov, IU.I.; Losev, V.F.; Panchenko, IU.N. (Inst. Sil' notochnoi Elektroniki, Tomsk (Russian Federation))
1992-07-01
Phase conjugation of a XeCl laser beam with spectral line widths of 2 and 0.4 nm depending on conditions of the beam focusing in a cell containing heptane is experimentally studied. Data obtained indicate that the phase conjugation efficiency was greater than 90 percent. The scattered beam contained not only the stimulated Brillouin scattering component but also a second component which was not frequency shifted. The ratio of these components depends on the geometry used to couple the pump beam into the nonlinear medium and on the intensity of the beam. Stimulated Brillouin scattering is performed using phase conjugation. 9 refs.
Jing, Chao; Liu, Zhongling; Zhou, Ge; Zhang, Yimo
2011-11-01
The nanometer-level precise phase-shift system is designed to realize the phase-shift interferometry in electronic speckle shearography pattern interferometry. The PZT is used as driving component of phase-shift system and translation component of flexure hinge is developed to realize micro displacement of non-friction and non-clearance. Closed-loop control system is designed for high-precision micro displacement, in which embedded digital control system is developed for completing control algorithm and capacitive sensor is used as feedback part for measuring micro displacement in real time. Dynamic model and control model of the nanometer-level precise phase-shift system is analyzed, and high-precision micro displacement is realized with digital PID control algorithm on this basis. It is proved with experiments that the location precision of the precise phase-shift system to step signal of displacement is less than 2nm and the location precision to continuous signal of displacement is less than 5nm, which is satisfied with the request of the electronic speckle shearography and phase-shift pattern interferometry. The stripe images of four-step phase-shift interferometry and the final phase distributed image correlated with distortion of objects are listed in this paper to prove the validity of nanometer-level precise phase-shift system.
Review of recent developments of spatial phase-shift digital shearography
Xie, Xin; Li, Xiaona; Chen, Xu; Yang, Lianxiang
2015-03-01
In the last decade, due to the fast development of phase-shift technique, the measurement sensitivity of digital shearography (DS) technology has been increased tens of times which brings the technology itself a wide acceptance by the industry as a practical measurement tool for quality inspection and non-destructive testing. In common sense, compare to Temporal Phase-Shift Digital Shearography (TPS-DS), Spatial Phase-Shift Digital Shearograhy (SPS-DS) has the advantage of a broader capability for both static and dynamic measurement applications while keeps the disadvantage of lower phase-map quality. Recently, with new developments, the phase map quality of spatial phase-shift digital shearography has been greatly improved which is now comparable to the temporal phase-shift technique. This article gives a review of recent developments of spatial phase-shift digital shearography. Theory, experimental setup, phase-map results and applications are shown in detail.
Czech Academy of Sciences Publication Activity Database
Artemyeva, Z.; Žigová, Anna; Kirillova, N.; Šťastný, Martin; Holubík, O.; Podrázký, V.
2017-01-01
Roč. 63, č. 13 (2017), s. 1838-1851 ISSN 0365-0340 Institutional support: RVO:67985831 Keywords : land use * aggregate stability * organo- clay complexes * dynamic light scattering * phase analysis light scattering * color coordinates Subject RIV: DF - Soil Science Impact factor: 2.137, year: 2016
Tahara, Tatsuki; Ito, Kenichi; Kakue, Takashi; Fujii, Motofumi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu
2011-03-01
We propose an algorithm for compensating the phase-shift error of polarization-based parallel two-step phase-shifting digital holography, which is a technique for recording a spatial two-step phase-shifted hologram. Although a polarization-based system of the technique has been experimentally demonstrated, there had been the problem that the phase difference of two phase-shifted holograms had been changed by the extinction ratio of the micropolarizer array attached to the image sensor used in the system. To improve the performance of the system, we established and formulated an algorithm for compensating the phase-shift error. Accurate spatial phase-shifting interferometry in the system can be conducted by the algorithm regardless of phase-shift error due to the extinction ratio. By the numerical simulation, the proposed algorithm was capable of reducing the root mean square errors of the reconstructed image by 1/4 and 1/5 in amplitude and phase, respectively. Also, the algorithm was experimentally demonstrated, and the experimental results showed that the system employing the proposed algorithm suppressed the conjugate image, which slightly appeared in the image reconstructed by the system not employing the algorithm, even when the extinction ratio was 10:1. Thus, the effectiveness of the proposed algorithm was numerically and experimentally verified. © 2010 Optical Society of America
Phase regeneration of phase-shift keying signals in highly nonlinear hybrid plasmonic waveguides.
Zhang, JiHua; Zhao, Ping; Cassan, Eric; Zhang, XinLiang
2013-03-15
Phase regeneration of phase-shift keying signals is theoretically proposed, we believe for the first time, based on the efficient optical parametric amplification (OPA) process in a highly nonlinear symmetric hybrid plasmonic waveguide. This optimized stacked waveguide with nonlinear organic materials has a relatively low loss of about 0.005 dB/μm and an effective nonlinear OPA coupling coefficient up to 60 ps/m/W(1/2). The phase-recovery process was achieved in this waveguide within a length as short as 150 μm.
Global effects of moon phase on nocturnal acoustic scattering layers
Prihartato, PK
2016-01-18
© Inter-Research 2016. The impact of moon phase on the global nocturnal vertical distribution of acoustic scattering layers (SLs) in the upper 200 m was studied during the Malaspina expedition that circumnavigated the world. We assessed the nocturnal weighted mean depths and the vertical extension of the SL (the range between the upper 25th percentile and lower 75th percentile of the backscatter) and used a generalized additive model to reveal the relationship between the nocturnal vertical distribution of the SL and moon phase, as well as other environmental factors. Moon phase significantly affected the SL distribution on a global scale, in contrast to other factors such as dissolved oxygen, temperature and fluorescence, which each correlated with nocturnal SL distribution during the large geographic coverage. Full moon caused a deepening effect on the nocturnal SL. Contrary to expectations, the shallowest distribution was not observed during the darkest nights (new moon) and there was no difference in vertical distribution between new moon and intermediate moon phases. We conclude that the trend of deepening SL during approximately full moon (bright nights) is a global phenomenon related to anti-predator behavior.
Three-Phase Phase-Shifting Transformer with Regulation in Neutral Point
Directory of Open Access Journals (Sweden)
Kalinin L.P.
2015-04-01
Full Text Available The paper aimed to research mode characteristics of phase shift installation based on one three-phase transformer having three windings. Usually, such installations are two cores: exciting transformer and regulation transformer. In paper the installation functional scheme description, as well main relations which determine currents and voltages character in scheme elements during regulation process are given. It is shown, that installation is able to provide phase shift angle regulation up to . The installation scheme is designed to place the control module in the neutral connection point of regulation windings. Such solution allowing essential reduction of installation rated capacity compare to traditional one and excluding necessity of special isolation of shell. Proposed solution ensure in such mode compact construction and commodity for transportation, mounting and service.
Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G.; Steenbergen, Wiendelt
2008-02-01
We describe an improved method for coherence domain path length resolved measurements of multiply scattered photons in turbid media. An electro-optic phase modulator sinusoidally modulates the phase in the reference arm of a low coherence fiber optic Mach-Zehnder interferometer, at a high phase modulation angle. For dynamic turbid media this results in Doppler broadened phase modulation interference peaks at the modulation frequency and its multiples. The signal to noise ratio is increased by almost one order or magnitude for large modulation angles and the shape of the spectral peaks resulting from the interference of Doppler shifted sample waves and reference light is not changed. The path length dependent Doppler broadening is compared with the theoretical predictions in the single scattered and diffusive regimes. The experimentally measured optical path lengths are validated with the Monte Carlo technique.
DEFF Research Database (Denmark)
Kim, T.-Y.; Hanawa, M.; Kim, Sun-Jong
2006-01-01
We propose and demonstrate a novel optical differential phase-shift keying (DPSK) demodulator with an optically tunable phase shifter. The proposed DPSK demodulator is implemented by using a pi-phase-shifted fiber Bragg grating and an Yb3+-Al3+ codoped optical fiber. A 10-Gb/s DPSK signal...
Instantaneous phase-shifting Fizeau interferometry with high-speed pixelated phase-mask camera
Yatagai, Toyohiko; Jackin, Boaz Jessie; Ono, Akira; Kiyohara, Kosuke; Noguchi, Masato; Yoshii, Minoru; Kiyohara, Motosuke; Niwa, Hayato; Ikuo, Kazuyuki; Onuma, Takashi
2015-08-01
A Fizeou interferometer with instantaneous phase-shifting ability using a Wollaston prism is designed. to measure dynamic phase change of objects, a high-speed video camera of 10-5s of shutter speed is used with a pixelated phase-mask of 1024 × 1024 elements. The light source used is a laser of wavelength 532 nm which is split into orthogonal polarization states by passing through a Wollaston prism. By adjusting the tilt of the reference surface it is possible to make the reference and object beam with orthogonal polarizations states to coincide and interfere. Then the pixelated phase-mask camera calculate the phase changes and hence the optical path length difference. Vibration of speakers and turbulence of air flow were successfully measured in 7,000 frames/sec.
The shifting zoom: new possibilities for inverse scattering on electrically large domains
Persico, Raffaele; Ludeno, Giovanni; Soldovieri, Francesco; De Coster, Alberic; Lambot, Sebastien
2017-04-01
Inverse scattering is a subject of great interest in diagnostic problems, which are in their turn of interest for many applicative problems as investigation of cultural heritage, characterization of foundations or subservices, identification of unexploded ordnances and so on [1-4]. In particular, GPR data are usually focused by means of migration algorithms, essentially based on a linear approximation of the scattering phenomenon. Migration algorithms are popular because they are computationally efficient and do not require the inversion of a matrix, neither the calculation of the elements of a matrix. In fact, they are essentially based on the adjoint of the linearised scattering operator, which allows in the end to write the inversion formula as a suitably weighted integral of the data [5]. In particular, this makes a migration algorithm more suitable than a linear microwave tomography inversion algorithm for the reconstruction of an electrically large investigation domain. However, this computational challenge can be overcome by making use of investigation domains joined side by side, as proposed e.g. in ref. [3]. This allows to apply a microwave tomography algorithm even to large investigation domains. However, the joining side by side of sequential investigation domains introduces a problem of limited (and asymmetric) maximum view angle with regard to the targets occurring close to the edges between two adjacent domains, or possibly crossing these edges. The shifting zoom is a method that allows to overcome this difficulty by means of overlapped investigation and observation domains [6-7]. It requires more sequential inversion with respect to adjacent investigation domains, but the really required extra-time is minimal because the matrix to be inverted is calculated ones and for all, as well as its singular value decomposition: what is repeated more time is only a fast matrix-vector multiplication. References [1] M. Pieraccini, L. Noferini, D. Mecatti, C
Bragg-Scattering Four-Wave Mixing in Nonlinear Fibers with Intracavity Frequency-Shifted Laser Pumps
Directory of Open Access Journals (Sweden)
Katarzyna Krupa
2012-01-01
Full Text Available We experimentally study four-wave mixing in highly nonlinear fibers using two independent and partially coherent laser pumps and a third coherent signal. We focus our attention on the Bragg-scattering frequency conversion. The two pumps were obtained by amplifying two Intracavity frequency-shifted feedback lasers working in a continuous wave regime.
Optimisation of Transmission Systems by use of Phase Shifting Transformers
Energy Technology Data Exchange (ETDEWEB)
Verboomen, J.
2008-10-13
In this thesis, transmission grids with PSTs (Phase Shifting Transformers) are investigated. In particular, the following goals are put forward: (a) The analysis and quantification of the impact of a PST on a meshed grid. This includes the development of models for the device; (b) The development of methods to obtain optimal coordination of several PSTs in a meshed grid. An objective function should be formulated, and an optimisation method must be adopted to solve the problem; and (c) The investigation of different strategies to use a PST. Chapter 2 gives a short overview of active power flow controlling devices. In chapter 3, a first step towards optimal PST coordination is taken. In chapter 4, metaheuristic optimisation methods are discussed. Chapter 5 introduces DC load flow approximations, leading to analytically closed equations that describe the relation between PST settings and active power flows. In chapter 6, some applications of the methods that are developed in earlier chapters are presented. Chapter 7 contains the conclusions of this thesis, as well as recommendations for future work.
Nonlinear Ultrafast Spin Scattering in the Skyrmion Phase of Cu2OSeO3
Langner, M. C.; Roy, S.; Huang, S. W.; Koralek, J. D.; Chuang, Y.-D.; Dakovski, G. L.; Turner, J. J.; Robinson, J. S.; Coffee, R. N.; Minitti, M. P.; Seki, S.; Tokura, Y.; Schoenlein, R. W.
2017-09-01
Ultrafast x-ray scattering studies of the topological Skyrmion phase in Cu2 OSeO3 show the dynamics to be strongly dependent on the excitation energy and fluence. At high photon energies, where the electron-spin scattering cross section is relatively high, the excitation of the topological Skyrmion phase shows a nonlinear dependence on the excitation fluence, in contrast to the excitation of the conical phase which is linearly dependent on the excitation fluence. The excitation of the Skyrmion order parameter is nonlinear in the magnetic excitation resulting from scattering during electron-hole recombination, indicating different dominant scattering processes in the conical and Skyrmion phases.
Nonlinear Ultrafast Spin Scattering in the Skyrmion Phase of Cu_{2}OSeO_{3}.
Langner, M C; Roy, S; Huang, S W; Koralek, J D; Chuang, Y-D; Dakovski, G L; Turner, J J; Robinson, J S; Coffee, R N; Minitti, M P; Seki, S; Tokura, Y; Schoenlein, R W
2017-09-08
Ultrafast x-ray scattering studies of the topological Skyrmion phase in Cu_{2}OSeO_{3} show the dynamics to be strongly dependent on the excitation energy and fluence. At high photon energies, where the electron-spin scattering cross section is relatively high, the excitation of the topological Skyrmion phase shows a nonlinear dependence on the excitation fluence, in contrast to the excitation of the conical phase which is linearly dependent on the excitation fluence. The excitation of the Skyrmion order parameter is nonlinear in the magnetic excitation resulting from scattering during electron-hole recombination, indicating different dominant scattering processes in the conical and Skyrmion phases.
Qiu, Jinhuan; Huang, Qirong
1992-01-01
The study of the inversion algorithm for the single scatter lidar equation, for quantitative determination of cloud (or aerosol) optical properties, has received much attention over the last thirty years. Some of the difficulties associated with the solution of this equation are not yet solved. One problem is that a single scatter lidar equation has two unknowns. Because of this, the determination of the far-end boundary value, in the case of Klett's algorithm, is a problem if the atmosphere is optically inhomogeneous. Another difficulty concerns multiple scattering. There is a large error in the extinction distribution solution, in many cases, if only the single scattering component is considered, while neglecting the multiple scattering component. However, the use of multiple scattering in the remote sensing of aerosol or cloud optical properties is promising. In our early study, an inversion method for simultaneous determination of the cloud (or aerosol) Extinction Coefficient Distribution (ECD) and its Forward Scattering Phase Function (FSPF) was proposed according to multiply scattered lidar returns with two fields of view for the receiver. The method is based on a parameterized multiple scatter lidar equation. This paper is devoted to further numerical tests and an experimental study of lidar measurements of cloud ECD and FSPF using this method.
Epi-detection of vibrational phase contrast coherent anti-Stokes Raman scattering
Garbacik, E.T.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.
2014-01-01
We demonstrate a system for the phase-resolved epi-detection of coherent anti-Stokes Raman scattering (CARS) signals in highly scattering and/or thick samples. With this setup, we measure the complex vibrational responses of multiple components in a thick, highly-scattering pharmaceutical tablet in
National Research Council Canada - National Science Library
Muxuan Xiao; Qianming Xu; Honglin Ouyang
2017-01-01
.... In this paper, the relationship between phase-shifted pulse width modulation (PWM) and phase disposition PWM is analyzed, and then an improved hybrid modulation strategy is proposed for cascaded H-bridge...
Black reefs: iron-induced phase shifts on coral reefs.
Kelly, Linda Wegley; Barott, Katie L; Dinsdale, Elizabeth; Friedlander, Alan M; Nosrat, Bahador; Obura, David; Sala, Enric; Sandin, Stuart A; Smith, Jennifer E; Vermeij, Mark J A; Williams, Gareth J; Willner, Dana; Rohwer, Forest
2012-03-01
The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to reefs on Millennium, Tabuaeran and Kingman. These three sites are relatively large (>0.75 km(2)). The phase shift occurs rapidly; the Kingman black reef formed within 3 years of the ship grounding. Iron concentrations in algae tissue from the Millennium black reef site were six times higher than in algae collected from reference sites. Metagenomic sequencing of the Millennium Atoll black reef-associated microbial community was enriched in iron-associated virulence genes and known pathogens. Microcosm experiments showed that corals were killed by black reef rubble through microbial activity. Together these results demonstrate that shipwrecks and their associated iron pose significant threats to coral reefs in iron-limited regions.
Johansson, A.; Herschbach, C.; Fedorov, D. V.; Gradhand, M.; Mertig, I.
2014-07-01
Recently, a generalized relativistic phase shift model was proposed (Fedorovet al 2013 Phys. Rev. B 88 085116) for the description of the skew-scattering contribution to the spin Hall effect caused by impurities. Here, we inspect this model by means of a systematic comparison with the results of first-principles calculations performed for several metallic host systems with different substitutional impurities. It is found that for its proper application, the differences between impurity and host phase shifts should be used as input parameters. Generally, the model provides good qualitative agreement with ab initio results for hosts with a free-electron-like Fermi surface and a relatively weak spin-orbit coupling, but fails otherwise.
Dafermos, Mihalis; Shlapentokh-Rothman, Yakov
2017-03-01
In this paper, we provide an elementary, unified treatment of two distinct blue-shift instabilities for the scalar wave equation on a fixed Kerr black hole background: the celebrated blue-shift at the Cauchy horizon (familiar from the strong cosmic censorship conjecture) and the time-reversed red-shift at the event horizon (relevant in classical scattering theory). Our first theorem concerns the latter and constructs solutions to the wave equation on Kerr spacetimes such that the radiation field along the future event horizon vanishes and the radiation field along future null infinity decays at an arbitrarily fast polynomial rate, yet, the local energy of the solution is infinite near any point on the future event horizon. Our second theorem constructs solutions to the wave equation on rotating Kerr spacetimes such that the radiation field along the past event horizon (extended into the black hole) vanishes and the radiation field along past null infinity decays at an arbitrarily fast polynomial rate, yet, the local energy of the solution is infinite near any point on the Cauchy horizon. The results make essential use of the scattering theory developed in Dafermos, Rodnianski and Shlapentokh-Rothman ( A scattering theory for the wave equation on Kerr black hole exteriors (2014). arXiv:1412.8379) and exploit directly the time-translation invariance of the scattering map and the non-triviality of the transmission map.
Effect of phase shift from corals to Zoantharia on reef fish assemblages.
Cruz, Igor C S; Loiola, Miguel; Albuquerque, Tiago; Reis, Rodrigo; Nunes, José de Anchieta C C; Reimer, James D; Mizuyama, Masaru; Kikuchi, Ruy K P; Creed, Joel C
2015-01-01
Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals) to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB), Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species) and phase-shift reefs (38 species), a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated.
Effect of Phase Shift from Corals to Zoantharia on Reef Fish Assemblages
Cruz, Igor C. S.; Loiola, Miguel; Albuquerque, Tiago; Reis, Rodrigo; de Anchieta C. C. Nunes, José; Reimer, James D.; Mizuyama, Masaru; Kikuchi, Ruy K. P.; Creed, Joel C.
2015-01-01
Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals) to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB), Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species) and phase-shift reefs (38 species), a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated. PMID:25629532
Experimental demonstration of 360 tunable RF phase shift using slow and fast light effects
DEFF Research Database (Denmark)
Xue, Weiqi; Sales, Salvador; Capmany, Jose
2009-01-01
A microwave photonic phase shifter realizing 360º phase shift over a RF bandwidth of more than 10 GHz is demonstrated using optical filtering assisted slow and fast light effects in a cascaded structure of semiconductor optical amplifiers.......A microwave photonic phase shifter realizing 360º phase shift over a RF bandwidth of more than 10 GHz is demonstrated using optical filtering assisted slow and fast light effects in a cascaded structure of semiconductor optical amplifiers....
Dual-polarization phase shift processing with the Python ARM Radar Toolkit
Collis, S. M.; Lang, T. J.; Mühlbauer, K.; Helmus, J.; North, K.
2016-12-01
Weather radars that measure backscatter returns at two orthogonal polarizations can give unique insight into storm macro and microphysics. Phase shift between the two polarizations caused by anisotropy in the liquid water path can be used as a constraint in rainfall rate and drop size distribution retrievals, and has the added benefit of being robust to attenuation and radar calibration. The measurement is complicated, however, by the impact of phase shift on backscatter in the presence of large drops and when the pulse volume is not filled uniformly by scatterers (known as partial beam filling). This has led to a signal processing challenge of separating the underlying desired signal from the transient signal, a challenge that has attracted many diverse solutions. To this end, the Python-ARM Radar Toolkit (Py-ART) [1] becomes increasingly important. By providing an open architecture for implementation of retrieval techniques, Py-ART has attracted three very different approaches to the phase processing problem: a fully variational technique, a finite impulse response filter technique [2], and a technique based on a linear programming [3]. These either exist within the toolkit or in another open source package that uses the Py-ART architecture. This presentation will provide an overview of differential phase and specific differential phase observed at C- and S-band frequencies, the signal processing behind the three aforementioned techniques, and some examples of their application. The goal of this presentation is to highlight the importance of open source architectures such as Py-ART for geophysical retrievals. [1] Helmus, J.J. & Collis, S.M., (2016). The Python ARM Radar Toolkit (Py-ART), a Library for Working with Weather Radar Data in the Python Programming Language. JORS. 4(1), p.e25. DOI: http://doi.org/10.5334/jors.119[2] Timothy J. Lang, David A. Ahijevych, Stephen W. Nesbitt, Richard E. Carbone, Steven A. Rutledge, and Robert Cifelli, 2007: Radar
A Randomized Double-Blind Crossover Study of Phase-Shift Sound Therapy for Tinnitus
Heijneman, Karin M.; de Kleine, Emile; van Dijk, Pim
Objective. The purpose of this study was to compare the efficacy of the treatment of tinnitus with a phase-shifting pure tone to that of the same tone treatment without phase shifting. Study Design. A double-blind crossover randomized controlled trial. Setting. This study was conducted at the
Lee, Clara; Smith, Mark R; Eastman, Charmane I
2006-01-01
Night shift work is associated with a myriad of health and safety risks. Phase-shifting the circadian clock such that it is more aligned with night work and day sleep is one way to attenuate these risks. However, workers will not be satisfied with complete adaptation to night work if it leaves them misaligned during days off. Therefore, the goal of this set of studies is to produce a compromise phase position in which individuals working night shifts delay their circadian clocks to a position that is more compatible with nighttime work and daytime sleep yet is not incompatible with late nighttime sleep on days off. This is the first in the set of studies describing the magnitude of circadian phase delays that occurs on progressively later days within a series of night shifts interspersed with days off. The series will be ended on various days in order to take a "snapshot" of circadian phase. In this set of studies, subjects sleep from 23:00 to 7:00 h for three weeks. Following this baseline period, there is a series of night shifts (23:00 to 07:00 h) and days off. Experimental subjects receive five 15 min intermittent bright light pulses (approximately 3500 lux; approximately 1100 microW/cm2) once per hour during the night shifts, wear sunglasses that attenuate all visible wavelengths--especially short wavelengths ("blue-blockers")--while traveling home after the shifts, and sleep in the dark (08:30-15:30 h) after each night shift. Control subjects remain in typical dim room light (light, and sleep whenever they want after the night shifts. Circadian phase is determined from the circadian rhythm of melatonin collected during a dim light phase assessment at the beginning and end of each study. The sleepiest time of day, approximated by the body temperature minimum (Tmin), is estimated by adding 7 h to the dim light melatonin onset. In this first study, circadian phase was measured after two night shifts and day sleep periods. The Tmin of the experimental subjects (n
Coherent anti-Stokes Raman scattering microscopy for pharmaceutics: a shift in the right direction
Fussell, A.L.
2014-01-01
This dissertation demonstrates coherent anti-Stokes Raman scattering (CARS) microscopy as a tool in pharmaceutical solid state development. CARS microscopy is a nonlinear optical imaging technique that uses inelastic scattering of light to provide chemically specific imaging. CARS microscopy is
A randomized double-blind crossover study of phase-shift sound therapy for tinnitus.
Heijneman, Karin M; de Kleine, Emile; van Dijk, Pim
2012-08-01
The purpose of this study was to compare the efficacy of the treatment of tinnitus with a phase-shifting pure tone to that of the same tone treatment without phase shifting. A double-blind crossover randomized controlled trial. This study was conducted at the University Medical Center Groningen. Twenty-two patients with predominantly tonal tinnitus underwent both intervention and control treatments. Each treatment consisted of three 30-minute sessions in 1 week. The control treatment was identical to the intervention treatment, except that the stimulus was a pure tone without phase shifting. Questionnaires, tinnitus loudness match, and annoyance and loudness ratings were used to measure treatment effects. Pure-tone treatment and phase-shift treatment had no significant effect on tinnitus according to questionnaires (Tinnitus Handicap Index, Tinnitus Reaction Questionnaire, Hospital Anxiety and Depression Scale, and Maastricht Questionnaire), audiological matching procedures, and loudness and annoyance ratings of tinnitus. Furthermore, phase-shift treatment showed no additional significant improvement in comparison with pure-tone treatment. Changes in questionnaire scores due to pure-tone and the phase-shift treatment were correlated. On average across the group, both treatments failed to demonstrate a significant effect. Both treatments were beneficial for some patients. However, a positive effect was not demonstrated that could be attributed to the periodic shifting of the phase of the stimulus tone.
Research on transmission characteristics of phase-shifted CFBG in 2 μm band
Zhang, Luna; Yan, Fengping; Bai, Zhuoya; Bai, Yan; Liu, Shuo; Zhou, Hong; Hou, Yafei; Zhang, Ning
2017-07-01
Principles of single- and multi-phase-shifted chirped fiber Bragg grating (CFBG) in 2 μm band are analyzed with transmission matrix method, and transmission characteristics, including transmissivity, wavelength and bandwidth performance, of single- and multi-phase-shifted CFBG in 2 μm band with different grating parameters are discussed by simulation. It is found that phase-shifted position, grating length, chirped coefficient and refractive index modulation amplitude all have impacts on bandwidth of phase-shifted transmission peak. The transmission peak bandwidths of single-, dual- and tri-phase-shifted CFBG can reach to 0.0270, 0.0172 and 0.0112 nm respectively. The experiment of phase-shifted CFBG verifies the correctness of the simulation, and the bandwidths of 0.0901 and 0.0480 nm are acquired for single- and dual-phase-shifted CFBG respectively, which are narrower than previous filters based on fiber Bragg grating in 2 μm band multi-wavelength fiber laser system.
Foschum, Florian; Kienle, Alwin
2013-08-01
We present simulations and measurements with an optimized goniometer for determination of the scattering phase function of suspended particles. We applied the Monte Carlo method, using a radially layered cylindrical geometry and mismatched boundary conditions, in order to investigate the influence of reflections caused by the interfaces of the glass cuvette and the scatterer concentration on the accurate determination of the scattering phase function. Based on these simulations we built an apparatus which allows direct measurement of the phase function from ϑ=7 deg to ϑ=172 deg without any need for correction algorithms. Goniometric measurements on polystyrene and SiO2 spheres proved this concept. Using the validated goniometer, we measured the phase function of yeast cells, demonstrating the improvement of the new system compared to standard goniometers. Furthermore, the scattering phase function of different fat emulsions, like Intralipid, was determined precisely.
Phase-shift anomaly caused by subwavelength-scale metal slit or aperture diffraction.
Lee, Kanghee; Yi, Minwoo; Park, Sang Eon; Ahn, Jaewook
2013-01-15
Terahertz time-domain spectroscopy probes anomalous phase-shift caused by wave diffraction from a subwavelength-scale metal slit or aperture. Carrier frequency phase measurements in the far-field region reveals that nearly 30° phase advance is induced from a subwavelength slit diffraction and that 180° phase-advance from a subwavelength aperture. These results indicate that the conventional 90° phase advance of diffracted waves in the far-field region, known as the Gouy phase shift, is not valid for subwavelength diffraction phenomena. The physical origin of these phase-shift anomalies is attributed to induced electric currents or magnetic dipole radiation, and theoretical analyses based on these factors are in good agreement with the experimental results.
Bergström, Sten Sture; Gustafsson, Karl-Arne
2011-01-01
Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.
Polarisation Control of DFB Fibre Laser Using UV-Induced Birefringent Phase-Shift
DEFF Research Database (Denmark)
Philipsen, Jacob Lundgreen; Lauridsen, Vibeke Claudia; Berendt, Martin Ole
1998-01-01
The polarisation properties of a distributed feedback (DFB) fibre laser are investigated experimentally. A birefringent phase-shift is induced by side illumination of the centre part of the lasing structure with ultraviolet (UV) light and it is experimentally shown that the birefringence of the p......The polarisation properties of a distributed feedback (DFB) fibre laser are investigated experimentally. A birefringent phase-shift is induced by side illumination of the centre part of the lasing structure with ultraviolet (UV) light and it is experimentally shown that the birefringence...... of the phase-shift is the dominating effect controlling the polarisation properties of the laser....
Eu-Doped GaN Films Grown by Phase Shift Epitaxy
Zhong, Mingyu; Steckl, Andrew J.
2010-12-01
Phase shift epitaxy (PSE) is a dynamic thin film growth technique wherein constituent fluxes are pulsed with an adjustable phase shift. PSE enables the introduction of dopants during the optimum segment of the growth cycle. Eu-doped GaN films were grown with Ga and Eu shutters periodically opened and closed (with varying phase shift) while keeping N flux constant, so that the Ga and Eu coverage on surface during each cycle varies in a controlled way. The Eu concentration and photoluminescence (PL) efficiency are strongly influenced by the PSE parameters. Eu ions doped during high Ga coverage exhibit strong PL efficiency.
3D imaging in volumetric scattering media using phase-space measurements.
Liu, Hsiou-Yuan; Jonas, Eric; Tian, Lei; Zhong, Jingshan; Recht, Benjamin; Waller, Laura
2015-06-01
We demonstrate the use of phase-space imaging for 3D localization of multiple point sources inside scattering material. The effect of scattering is to spread angular (spatial frequency) information, which can be measured by phase space imaging. We derive a multi-slice forward model for homogenous volumetric scattering, then develop a reconstruction algorithm that exploits sparsity in order to further constrain the problem. By using 4D measurements for 3D reconstruction, the dimensionality mismatch provides significant robustness to multiple scattering, with either static or dynamic diffusers. Experimentally, our high-resolution 4D phase-space data is collected by a spectrogram setup, with results successfully recovering the 3D positions of multiple LEDs embedded in turbid scattering media.
Equivalent local potentials and phase approach to low-energy scattering parameters
Energy Technology Data Exchange (ETDEWEB)
Jana, A.K.; Nandi, T.K.; Paul, A.K.; Talukdar, B. (Department of Physics, Santiniketan, West Bengal (India))
1994-01-01
It is shown that the use of the McTavish-Kermode-Melhem-type equivalent local potentials linearizes algorithms of the variable-phase approach needed to compute the low-energy scattering parameters. A case study is presented to demonstrate the merit of the linearized equations, with particular emphasis on the relationship between the interpolating scattering length function and potential functions. (Author).
Investigation on Phase Shifting Effect on The Voltage Output of Piezoelectric Cantilever Array
Jing, B. Y.; Leong, K. S.
2017-06-01
This paper analyses the phase shifting of the output waveform produced by piezoelectric cantilevers under a range of vibration frequencies. The phase shift of four piezoelectric cantilevers with different resonant frequency are inspected while it is excited with the vibration from the electrodynamics shaker at a range of frequencies from 100 Hz to 500 Hz with the acceleration level (g-force) fixed at constant magnitude of 1g-level (9.81 m/s2). Time different and Lissajous pattern methods were used in this research to measure the phase shift of the output waveform. Both methods show similar result where the major phase shift happened at the resonant frequency of respective cantilevers. The phase difference remains low around 0 degrees or in other term in phase before the resonant frequency of the cantilever. When the frequency of the vibration source approaches the resonant frequency of respective cantilever, the phase different start to increase rapidly and reach 180 degree which is out of phase after the resonant frequency. This major phase shifting contributes to the significant rise of the gap in between the peaks formed when multiple piezoelectric cantilevers are connected together. As a result, it indirectly improves the output performance of the piezoelectric cantilevers array.
Small angle neutron scattering study of U(VI) third phase formation ...
Indian Academy of Sciences (India)
It was observed that third phase formation takes place due to the formation of. UO2(NO3)2.DHDECMP reverse micelles in the dodecane phase. SANS data obtained were interpreted with particle interaction model using Baxter sticky spheres model. Keywords. Small angle neutron scattering; U(VI); third phase; DHDECMP.
EMP-002a Phase Shift through the Ionosphere
Energy Technology Data Exchange (ETDEWEB)
Soltz, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simons, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fenimore, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wilks, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carey, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-10-20
In this note we review the derivation and use of the Ionospheric Transfer Function (ITF) in the DIO- RAMA model to calculate the propagation of a broad band ElectroMagnetic Pulse (EMP) through the Ionosphere in the limit of geometric optics. This note is intended to resolve a misunderstanding between the NDS VVA and EMP modeling teams regarding the appropriate use of the phase and group velocities in DIORAMA. The di erent approaches are documented in EMP-002 note, \\Phase vs. Group" [1], generated by the LLNL DIORAMA VVA team, and the subsequent response from the DIORAMA EMP modeling team' [2].
Yang, Hui; Deng, Yan
2017-12-01
All-dielectric metasurfaces for wavefront deflecting and optical vortex generating with broadband and high efficiency are demonstrated. The unit cell of the metasurfaces is optimized to function as a half wave-plate with high polarization conversion efficiency (94%) and transmittance (94.5%) at the telecommunication wavelength. Under such a condition, we can get rid of the complicated parameter sweep process for phase shift selecting. Hence, a phase coverage ranges from 0 to 2 π can be easily obtained by introducing the Pancharatnam-Berry phase. Metasurfaces composed of the two pre-designed super cells are demonstrated for optical beam deflecting and vortex beam generating. It is found that the metasurfaces with more phase shift sampling points (small phase shift increment) exhibit better performance. Moreover, optical vortex beams can be generated by the designed metasurfaces within a wavelength range of 200 nm. These results will provide a viable route for designing broadband and high efficiency devices related to phase modulation.
Humphrey, E; Phatak, C; Petford-Long, A K; De Graef, M
2014-04-01
We introduce a new approach for the separation of the electrostatic and magnetic components of the electron wave phase shift, based on the transport-of-intensity equation (TIE) formalism. We derive two separate TIE-like equations, one for each of the phase shift components. We use experimental results on FeCoB and Permalloy patterned islands to illustrate how the magnetic and electrostatic longitudinal derivatives can be computed. The main advantage of this new approach is the fact that the differences in the power spectra of the two phase components (electrostatic phase shifts often have significant power in the higher frequencies) can be accommodated by the selection of two different Tikhonov regularization parameters for the two phase reconstructions. The extra computational demands of the method are more than compensated by the improved phase reconstruction results. Copyright © 2014 Elsevier B.V. All rights reserved.
Asymmetrically pumped Bragg scattering with the effects of nonlinear phase modulation
DEFF Research Database (Denmark)
Andersen, Lasse Mejling; Friis, Søren Michael Mørk; Reddy, Dileep V.
2014-01-01
We derive exact solutions to asymmetrically pumped Bragg scattering with nonlinear phase-modulation (NPM) and show that this setup allows for the frequency conversion of many temporal modes, while reducing the effects due to NPM....
Energy Technology Data Exchange (ETDEWEB)
Birkbak, Mie Elholm; Nielsen, Ida Gjerlevsen; Frølich, Simon; Stock, Stuart R.; Kenesei, Peter; Almer, Jonathan D.; Birkedal, Henrik
2017-02-01
Advanced functional materials often contain multiple phases which are (nano)crystalline and/or amorphous. The spatial distribution of these phases and their properties, including nanocrystallite size and shape, often drives material function yet is difficult to obtain with current experimental techniques. This article describes the use of diffraction scattering computed tomography, which maps wide-angle scattering information onto sample space, to address this challenge. The wide-angle scattering signal contains information on both (nano)crystalline and amorphous phases. Rietveld refinement of reconstructed diffraction patterns is employed to determine anisotropic nanocrystal shapes. The background signal from refinements is used to identify contributing amorphous phases through multivariate curve resolution. Thus it is demonstrated that reciprocal space analysis in combination with diffraction scattering computed tomography is a very powerful tool for the complete analysis of complex multiphase materials such as energy devices.
Cheng, Jinlong; Yuan, Qun; Dou, Yimeng; Yao, Yanxia; Huang, Jialing; Zuo, Chao; Gao, Zhishan
2017-11-01
Dual-wavelength interferometry could extend the measured range of single-wavelength interferometry by combining the two single wavelength phases, particularly for the measurement of step height. When testing the high-reflectivity surfaces with the single wavelength Fizeau interferometer, we have presented the π / 4 phase-shift carrier squeezing interferometry (QCSI) method for phase extraction with multi-beam interference (Appl. Opt. 55, 1920-1928, 2016). In this paper, we propose an integer and decimal portions synthetization (IDS) method for the multi-beam interference in the dual-wavelength Fizeau interferometer. One of the single wavelength wrapped phases is demodulated by the multi-beam interference QCSI algorithm, while the second of the single wavelength wrapped phases is extracted by the conventional two-beam interference phase-shift algorithm, so the equivalent wavelength unwrapped phase is derived from the two single wavelength wrapped phase. The decimal portion of synthesized phase is then obtained directly from the first single wavelength wrapped phase, and the integer portion of synthesized phase is obtained from the fringe order of the first single wavelength wrapped phase determined by the equivalent wavelength unwrapped phase. The proposed non-iterative IDS method avoids the common error magnification effect in the two-wavelength techniques, and only requires no more than 8 frame phase-shift interferograms for each single wavelength. Its robust performance is validated by both simulations and experiments in the presence of multi-beam interference as well as phase-shift error for measuring objects with height discontinuities.
Phase-shift, stimuli-responsive drug carriers for targeted delivery.
O'Neill, Brian E; Rapoport, Natalya
2011-09-01
The intersection of particles and directed energy is a rich source of novel and useful technology that is only recently being realized for medicine. One of the most promising applications is directed drug delivery. This review focuses on phase-shift nanoparticles (that is, particles of submicron size) as well as micron-scale particles whose action depends on an external-energy triggered, first-order phase shift from a liquid to gas state of either the particle itself or of the surrounding medium. These particles have tremendous potential for actively disrupting their environment for altering transport properties and unloading drugs. This review covers in detail ultrasound and laser-activated phase-shift nano- and micro-particles and their use in drug delivery. Phase-shift based drug-delivery mechanisms and competing technologies are discussed.
Tahara, Tatsuki; Otani, Reo; Omae, Kaito; Gotohda, Takuya; Arai, Yasuhiko; Takaki, Yasuhiro
2017-05-15
We propose multiwavelength in-line digital holography with wavelength-multiplexed phase-shifted holograms and arbitrary symmetric phase shifts. We use phase-shifting interferometry selectively extracting wavelength information to reconstruct multiwavelength object waves separately from wavelength-multiplexed monochromatic images. The proposed technique obtains systems of equations for real and imaginary parts of multiwavelength object waves from the holograms by introducing arbitrary symmetric phase shifts. Then, the technique derives each complex amplitude distribution of each object wave selectively and analytically by solving the two systems of equations. We formulate the algorithm in the case of an arbitrary number of wavelengths and confirm its validity numerically and experimentally in the cases where the number of wavelengths is two and three.
Combined Coding And Modulation Employing Multi Phase Shift ...
African Journals Online (AJOL)
In this paper a technique for combining Huffman code, array code and phase modulation is proposed with a view to reduce redundancy, provide error control and simultaneously optimise on channel bandwidth. The combined scheme provides a reduction in overall complexity of the communication system as compared to a ...
Gamma-phase shifting in awake monkey visual cortex
Vinck, M.; Lima, B.; Womelsdorf, T.; Oostenveld, R.; Singer, W.; Neuenschwander, S.; Fries, P.
2010-01-01
Gamma-band synchronization is abundant in nervous systems. Typically, the strength or precision of gamma-band synchronization is studied. However, the precise phase with which individual neurons are synchronized to the gamma-band rhythm might have interesting consequences for their impact on further
Uniqueness of a 3-D coefficient inverse scattering problem without the phase information
Klibanov, Michael V.; Romanov, Vladimir G.
2017-09-01
We use a new method to prove the uniqueness theorem for a coefficient inverse scattering problem without the phase information for the 3-D Helmholtz equation. We consider the case when only the modulus of the scattered wave field is measured and the phase is not measured. The spatially distributed refractive index is the subject of interest in this problem. Applications of this problem are in imaging of nanostructures and biological cells.
Large microwave phase shift and small distortion in an integrated waveguide device
DEFF Research Database (Denmark)
Öhman, Filip; Sales, Salvador; Chen, Yaohui
2007-01-01
We have obtained a tunable phase shift of 150 degrees in an integrated semiconductor waveguide by optimizing the interplay of fast and slow light effects. Furthermore, the distortions imposed by device nonlinearities have been quantified.......We have obtained a tunable phase shift of 150 degrees in an integrated semiconductor waveguide by optimizing the interplay of fast and slow light effects. Furthermore, the distortions imposed by device nonlinearities have been quantified....
Large phase shift of (1+1)-dimensional nonlocal spatial solitons in lead glass
Shou, Qian; Wu, Miao; Guo, Qi
2014-01-01
The large phase shift of strongly nonlocal spatial optical soliton(SNSOS) in the (1+1)-dimensional [(1+1)D] lead glass is investigated using the perturbation method. The fundamental soliton solution of the nonlocal nonlinear Schodinger equation(NNLSE) under the second approximation in strongly nonlocal case is obtained. It is found that the phase shift rate along the propagation direction of such soliton is proportional to the degree of nonlocality, which indicates that one can realize Pi-pha...
Improved emission properties of polymer photonic crystal lasers by introducing a phase-shift
DEFF Research Database (Denmark)
Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron
2010-01-01
Introducing a phase-shift in nanoimprinted polymer dye lasers is shown to increase the probability of single mode lasing from 19% to 99%. Low-index lasers with only one longitudinal mode are thus superior to band-edge lasers.......Introducing a phase-shift in nanoimprinted polymer dye lasers is shown to increase the probability of single mode lasing from 19% to 99%. Low-index lasers with only one longitudinal mode are thus superior to band-edge lasers....
Experimental Demonstration of Capacity-Achieving Phase-Shifted Superposition Modulation
DEFF Research Database (Denmark)
Estaran Tolosa, Jose Manuel; Zibar, Darko; Caballero Jambrina, Antonio
2013-01-01
We report on the first experimental demonstration of phase-shifted superposition modulation (PSM) for optical links. Successful demodulation and decoding is obtained after 240 km transmission for 16-, 32- and 64-PSM.......We report on the first experimental demonstration of phase-shifted superposition modulation (PSM) for optical links. Successful demodulation and decoding is obtained after 240 km transmission for 16-, 32- and 64-PSM....
Phase-shift, stimuli-responsive perfluorocarbon nanodroplets for drug delivery to cancer.
Rapoport, Natalya
2012-01-01
This review focuses on phase-shift perfluorocarbon nanoemulsions whose action depends on an ultrasound-triggered phase shift from a liquid to gas state. For drug-loaded perfluorocarbon nanoemulsions, microbubbles are formed under the action of tumor-directed ultrasound and drug is released locally into tumor volume in this process. This review covers in detail mechanisms involved in the droplet-to-bubble transition as well as mechanisms of ultrasound-mediated drug delivery. Copyright © 2012 Wiley Periodicals, Inc.
Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab
DEFF Research Database (Denmark)
Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.
2015-01-01
An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration.......An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....
Measurement of in-plane strain with dual beam spatial phase-shift digital shearography
Xie, Xin; Chen, Xu; Li, Junrui; Wang, Yonghong; Yang, Lianxiang
2015-11-01
Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential.
Characterization of nonlinear phase shifts by use of the temporal transport-of-intensity equation.
Dorrer, Christophe
2005-12-01
A temporal transport-of-intensity equation is derived to describe the evolution of the instantaneous power of the electric field in a dispersive medium. As its spatial counterpart, which can be used to measure wavefronts using the intensity measured after various amounts of diffraction, the temporal transport-of-intensity equation allows the determination of temporal phase shifts using only intensity measurements in a direct noninterferometric way. The application to the characterization of nonlinear phase shifts induced by self-phase modulation and cross-phase modulation is used to determine the nonlinear coefficient of a highly nonlinear fiber.
Phase-shift between arterial flow and ICP pulse during infusion test.
Kim, Dong-Joo; Czosnyka, Marek; Kim, Hakseung; Balédent, Olivier; Smielewski, Piotr; Garnett, Matthew R; Czosnyka, Zofia
2015-04-01
The dynamic relationship between pulse waveform of intracranial pressure (ICP) and transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) may contain information about cerebrospinal compliance. This study investigated the possibility by focusing on the phase shift between fundamental harmonics of CBFV and ICP. Thirty-seven normal pressure hydrocephalus patients (20 men, mean age 58) underwent the cerebrospinal fluid (CSF) infusion tests. The infusion was performed via pre-implanted Ommaya reservoir. The TCD FV was recorded in the middle cerebral artery. Resulting continuous ICP and pressure-volume (PV) signals were analyzed by ICM+ software. In initial stage of the CSF infusion, the phase shift was negative (median value = -11°, range = +60 to -117). There was significant inverse association of phase shift with brain elasticity (R = -0.51; p = 0.0009). In all tests, phase shift consistently decreased during gradual elevation of ICP (p = 0.00001). Magnitude of decrease in phase shift was inversely related to the peak-to-peak amplitude of ICP pulse waveform at a baseline (R = -0.51; p = 0.001). Phase shift between fundamental harmonics of ICP and TCD waveforms decreases during elevation of ICP. This is caused by an increase of time delay between systolic peak of flow velocity wave and ICP pulse.
Endocrine and cardiovascular rhythms differentially adapt to chronic phase-delay shifts in rats.
Zeman, Michal; Molcan, Lubos; Herichova, Iveta; Okuliarova, Monika
2016-01-01
Disturbances in regular circadian oscillations can have negative effects on cardiovascular function, but epidemiological data are inconclusive and new data from animal experiments elucidating critical biological mechanisms are needed. To evaluate the consequences of chronic phase shifts of the light/dark (LD) cycle on hormonal and cardiovascular rhythms, two experiments were performed. In Experiment 1, male rats were exposed to either a regular 12:12 LD cycle (CONT) or rotating 8-h phase-delay shifts of LD every second day (SHIFT) for 10 weeks. During this period, blood pressure (BP) was monitored weekly, and daily rhythms of melatonin, corticosterone, leptin and testosterone were evaluated at the end of the experiment. In Experiment 2, female rats were exposed to the identical shifted LD schedule for 12 weeks, and daily rhythms of BP, heart rate (HR) and locomotor activity were recorded using telemetry. Preserved melatonin rhythms were found in the pineal gland, plasma, heart and kidney of SHIFT rats with damped amplitude in the plasma and heart, suggesting that the central oscillator can adapt to chronic phase-delay shifts. In contrast, daily rhythms of corticosterone, testosterone and leptin were eliminated in SHIFT rats. Exposure to phase shifts did not lead to increased body weight and elevated BP. However, a shifted LD schedule substantially decreased the amplitude and suppressed the circadian power of the daily rhythms of BP and HR, implying weakened circadian control of physiological and behavioural processes. The results demonstrate that endocrine and cardiovascular rhythms can differentially adapt to chronic phase-delay shifts, promoting internal desynchronization between central and peripheral oscillators, which in combination with other negative environmental stimuli may result in negative health effects.
Large phase shift via polarization-coupling cascading.
Huo, Juan; Chen, Xianfeng
2012-06-04
Herein, we propose a phenomenon of "polarization-coupling (PC) cascading" generated in MgO doped periodically poled lithium niobate crystal (PPMgLN). PC cascading contributes to the effective electro-optical (EO) Kerr effect that is several orders of magnitude stronger than the classical ones. Experiment of Newton's rings demonstrates the large phase accumulation during the PC cascaded processes, and the experimental data is identical with the theoretical simulation.
Phase function measurements on nonspherical scatterers using a two-axis goniometer.
Forster, Florian Klaus; Kienle, Alwin; Michels, Rene; Hibst, Raimund
2006-01-01
We present a two-axis goniometer for measuring the phase function of scattering media with an angular resolution of about 0.2 deg having 12 decades of dynamic range and covering almost the full solid angle. The setup is evaluated with polystyrene spheres and with perpendicularly and obliquely illuminated thin glass cylinders. The scattering pattern and its intensity distribution are in excellent agreement with analytical theory. A multiple scattering configuration composed of two parallel cylinders is also examined. Finally, the phase function of dentin slabs is measured and its dependence on the dental microstructure is discussed.
New apparatus for precise synchronous phase shift measurements in storage rings
Directory of Open Access Journals (Sweden)
Boris Podobedov
1998-11-01
Full Text Available Measuring a synchronous phase shift as a function of beam current is commonly done in accelerator physics to estimate the longitudinal impedance of a storage ring vacuum chamber. This measurement is normally done with RF techniques that do not have enough accuracy to detect small phase shifts typical to the newer storage rings. In this paper we report results from a new method for precise measurement of a synchronous phase shift. Our method involves downmixing from the RF frequency to a kHz range and then using an audio DSP lock-in amplifier for the actual phase detection. This paper describes the idea and the advantages of a new method as well as its practical implementation in the apparatus we build for precise synchronous phase measurements in the Stanford Linear Collider damping rings. The results of those measurements are also presented.
DEFF Research Database (Denmark)
Enz, Stephanie; Thomsen, Jon Juel; Neumeyer, Stefan
2011-01-01
Theoretical investigations of a single, straight, vibrating, fluid-conveying pipe have resulted in simple analytical expressions for the approximate prediction of the spatial shift in vibration phase. The expressions have lead to hypotheses for real Coriolis flowmeters (CFMs). To test these......, the flexural vibrations of two bent, parallel, non-fluid-conveying pipes are studied experimentally, employing an industrial CFM. Special attention has been paid on the phase shift in the case of zero mass flow, i.e. the zero shift, caused by various imperfections to the ‘‘perfect’’ CFM, i.e. non-uniform pipe...
Hsu, Wei-Feng; Chen, Yu-Wen; Su, Yuan-Hong
2011-07-10
We proposed a method to implement spatial phase-shift patterns with subdiffraction limited features through a holographic projection system. The input device of the system displayed phase-only diffractive optical elements that were calculated using the iterative Fourier-transform algorithm with the dummy-area method. By carefully designing the target patterns to the algorithm, the diffractive optical elements generated the Fourier-transformed images containing the phase-shift patterns in which the widths of dark lines were smaller than the diffraction limit. With these demonstrations, we have successfully shown that the near-field phase-shift lithographic technique can be realized through an inexpensive maskless lithographic system and can still achieve subdiffraction limited images. © 2011 Optical Society of America
Electronic Raman scattering in cuprate superconductors and parent insulating phases
Energy Technology Data Exchange (ETDEWEB)
Klein, M.V.; Liu, R.; Salamon, D.; Blumberg, G.; Reznik, D.; Cooper, S.L.; Lee, W.C.; Ginsberg, D.M. [Univ. of Illinois, Urbana, IL (United States); Cheong, S.W. [AT and T Labs., Murray Hill, NJ (United States)
1994-12-31
Raman scattering from charge and spin excitations in cuprates is reviewed. The two-magnon resonance Raman profile is used to determine the most probable energy for photon-assisted charge transfer leading to exchange between two spins. The difference between this energy and that for absorption is attributed to spin relaxation (spin polaron) effects. Two-magnon spectra in superconducting cuprates are presented. It is argued that their presence is evidence that the antiferromagnetic correlation length is equal to or greater than three lattice constants. The recently-discovered Raman-active excitons are described and possible assignments of them are discussed. It is pointed out that in highly correlated metals and insulators, the mechanisms for fight scattering that are familiar for doped semiconductors or conventional metals are not necessarily the only ones that are operative.
Phase shifting-based debris effect detection in USV-assisted AFM nanomachining
Energy Technology Data Exchange (ETDEWEB)
Shi, Jialin [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100049 (China); Liu, Lianqing, E-mail: lianqingliu@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Yu, Peng; Cong, Yang [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Li, Guangyong [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA 15213 (United States)
2017-08-15
Highlights: • The mechanism of the debris effect on machining depth in force control mode operation is analyzed. • The relationship between phase shifting and pile-up of debris is investigated. • The phase shifting-based method is hardly affected by the pile-up of debris. • Debris effect detection by phase shifting-based method is achived. - Abstract: Atomic force microscopy (AFM) mechanical-based lithography attracts much attention in nanomanufacturing due to its advantages of low cost, high precision and high resolution. However, debris effects during mechanical lithography often lead to an unstable machining process and inaccurate results, which limits further applications of AFM-based lithography. There is a lack of a real-time debris detection approach, which is the prerequisite to eventually eliminating the influence of the debris, and of a method that can solve the above problems well. The ultrasonic vibration (USV)-assisted AFM has the ability to sense the machining depth in real time by detecting the phase shifting of cantilever. However, whether the pile-up of debris affect the phase response of cantilever is still lack of investigation. Therefore, we analyzed the mechanism of the debris effect on force control mode and investigated the relationship between phase shifting and pile-up of debris. Theoretical analysis and experimental results reveal that the pile-up of debris have negligible effect on phase shifting of cantilever. Therefore, the phase shifting-based method can detect the debris effect on machining depth in force control mode of AFM machining.
Fermi energy shift in deposited metallic nanotubes: A Raman scattering study
Hatting, Benjamin; Heeg, Sebastian; Ataka, Kenichi; Heberle, Joachim; Hennrich, Frank; Kappes, Manfred M.; Krupke, Ralph; Reich, Stephanie
2013-04-01
The longitudinal optical phonon of metallic nanotubes shifts by 23 cm-1 to higher energies when the nanotubes are deposited onto a substrate. The linewidth narrows by 13 cm-1. The changes are explained in terms of shifts in the Fermi energy that influence the Kohn anomaly in the longitudinal optical phonon branch in metallic nanotubes. Using in situ electrochemical Raman measurements we show that the Fermi energy is 0.16 eV below its intrinsic value in metallic nanotubes in solution. Our results impact the application of Raman spectroscopy to distinguish between metallic and semiconducting tubes by examining the high-energy mode line shape.
Sato, Takao M.; Satoh, T.; Kasaba, Y.
2010-10-01
It is essential to know scattering properties (e.g., scattering phase function) of clouds for determination of vertical cloud structure. However, we cannot derive those from ground-based and Earth-orbit observations because of the limitation of solar phase angle as viewed from the Earth. Then, most previous studies have used the scattering phase function deduced from the Pioneer 10/IPP data (blue: 440 nm, red: 640nm) [Tomasko et al., 1978]. There are two shortcomings in the Pioneer scattering phase function. One is that we have to use this scattering phase function at red as a substitute for analyses of imaging photometry using CH4 bands (center: 727 and 890 nm), although clouds should have wavelength dependency. The other is that the red pass band of IPP was so broad (595-720 nm) that this scattering phase function in red just show wavelength-averaged scattering properties of clouds. To provide a new reference scattering phase function with wavelength dependency, we have analyzed the Cassini/ISS data in BL1 (451 nm), CB1 (619 nm), CB2 (750 nm), and CB3 (938 nm) over wide solar phase angles (3-141 degrees) during its Jovian flyby in 2000-2001. A simple cloud model which consists of a thin stratospheric haze, a semi-infinite cloud, and an intervening Rayleigh gas layers is adopted. Applying Mie theory to scattering by clouds, we deduce the scattering phase function of cloud and effective particle size in the South Tropical Zone. When we use the nominal value of reflective index for ammonia ice (Martonchik et al., 1984), we cannot obtain reasonable fit to the observed limb-darkening profiles. This would imply that we should consider possible effects on the impurity and/or the nonsphericiy of clouds. In this presentation, we will show detail model description and these results. Finally, we discuss scattering properties of clouds through comparison with previous works.
Durst, Adam C.; Ganeshan, Sriram; Kulkarni, Manas
2011-03-01
In the vortex state of a d-wave superconductor, massless Dirac quasiparticles are scattered from magnetic vortices via a combination of two basic mechanisms: effective potential scattering due to the superflow swirling about the vortices and Aharonov-Bohm scattering due to the Berry phase acquired by a quasiparticle upon circling a vortex. First, we consider the superflow contribution by calculating the differential cross section for a quasiparticle scattering from the effective non-central potential of a single vortex. Next, we consider the Berry phase contribution, which results in branch cuts between neighboring vortices across which the quasiparticle wave function changes sign. Here, the simplest problem that captures the physics is that of scattering from a single finite branch cut that stretches between two vortices. Elliptical coordinates are natural for this two-center problem and we proceed by separating the massless Dirac equation in elliptical coordinates. The separated equations take the form of the Whittaker-Hill equations, which we solve to obtain radial and angular eigenfunctions. With these eigenfunctions in hand, we construct the scattering cross section via partial wave analysis. We discuss the scattering effect of each mechanism, superflow and Berry phase, leaving the important issue of interference between the two mechanisms to future work.
Bhaduri, Basanta; Mohan, N K; Kothiyal, M P; Sirohi, R S
2006-11-27
Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are well known optical tools for qualitative as well as quantitative measurements of displacement components and its derivatives of engineering structures subjected either static or dynamic load. Spatial phase shifting (SPS) technique is useful for extracting quantitative displacement data from the system with only two frames. Optical configurations for DSPI and DS with a double aperture mask in front of the imaging lens for spatial phase shifting are proposed in this paper for the measurement of out-of-plane displacement and its first order derivative (slope) respectively. An error compensating four-phase step algorithm is used for quantitative fringe analysis.
Phase-shifted Bragg grating inscription in PMMA microstructured POF using 248 nm UV radiation
DEFF Research Database (Denmark)
Pereira, L.; Pospori, A.; Antunes, Paulo
2017-01-01
for photosensitivity improvement was used. A uniform phase mask customized for 850 nm grating inscription was used to inscribe these Bragg structures. The phase shift defect was created directly during the grating inscription process by placing a narrow blocking aperture in the center of the UV beam. The produced high...... a significant increase in measurement resolution compared to direct interrogation of a single grating. The reflection and transmission spectra when multiple phase shifts are introduced in the FBG structure are also shown. The PS-POFBG's strain, temperature, pressure, and humidity characteristics have been...
Bhaduri, Basanta; Mohan, N. K.; Kothiyal, M. P.; Sirohi, R. S.
2006-11-01
Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are well known optical tools for qualitative as well as quantitative measurements of displacement components and its derivatives of engineering structures subjected either static or dynamic load. Spatial phase shifting (SPS) technique is useful for extracting quantitative displacement data from the system with only two frames. Optical configurations for DSPI and DS with a double aperture mask in front of the imaging lens for spatial phase shifting are proposed in this paper for the measurement of out-of-plane displacement and its first order derivative (slope) respectively. An error compensating four-phase step algorithm is used for quantitative fringe analysis.
Ovryn, B; Andrews, J H
1999-04-01
The operating characteristics of a novel phase-shifting interferometer are presented. Interference arises by reflecting the light from a sample back into the cavity of a cw He-Ne laser. Changes in phase and fringe visibility are calculated from an overdetermined set of phase-shifted intensity measurements with the phase shifts being introduced with an electro-optic modulator. The interferometer is sensitive enough to measure displacements below 1 Hz with a rms error of approximately 1 nm from a sample that reflects only 3% of the 28 microW that is incident on its surface. The interferometer is applied to the determination of cantilever bending of a piezoelectric bimorph.
Scattering Phase Functions of Constituents of Mineral Dust Aerosols ...
African Journals Online (AJOL)
The results show that there is increasing asymmetry and complexity of the phase functions with increasing radial sizes for each of the selected constituents: Illite, Kaolinite, Montmorillonte, Hematite, Calcite and Quartz. The behaviour of these constituents as observed by their phase functions provide information on the ...
Scattering Phase Functions of Constituents of Mineral Dust Aerosols ...
African Journals Online (AJOL)
In this paper, a Mie-based numerical computation and visualization program has been used to compute the phase functions of typical constituents of mineral dust ... The behaviour of these constituents as observed by their phase functions provide information on the optical properties and radiative effects of the mineral dust ...
Neutron scattering study of the incommensurate high-field phase of CuGeO3
DEFF Research Database (Denmark)
Rønnow, H.M.; Enderle, M.; McMorrow, D.F.
2000-01-01
CuGeO3 is a good realization of a spin-Peierls system. Using neutron scattering, we have investigated the transition from the dimerized spin-Peierls phase to an incommensurately modulated high-field phase. The incommensurate period has been measured for fields up to 14.5 T and is found...
Enhanced Measurement of Paper Basis Weight Using Phase Shift in Terahertz Time-Domain Spectroscopy
Directory of Open Access Journals (Sweden)
Mengbao Fan
2017-01-01
Full Text Available THz time-domain spectroscopy has evolved as a noncontact, safe, and efficient technique for paper characterization. Our previous work adopted peak amplitude and delay time as features to determine paper basis weight using terahertz time-domain spectroscopy. However, peak amplitude and delay time tend to suffer from noises, resulting in degradation of accuracy and robustness. This paper proposes a noise-robust phase-shift based method to enhance measurements of paper basis weight. Based on Fresnel Formulae, the physical relationship between phase shift and paper basis weight is formulated theoretically neglecting multiple reflections in the case of normal incidence. The established formulation indicates that phase shift correlates linearly with paper basis weight intrinsically. Subsequently, paper sheets were stacked to fabricate the samples with different basis weights, and experimental results verified the developed mathematical formulation. Moreover, a comparison was made between phase shift, peak amplitude, and delay time with respect to linearity, accuracy, and noise robustness. The results show that phase shift is superior to the others.
International workshop on phase retrieval and coherent scattering. Coherence 2005
Energy Technology Data Exchange (ETDEWEB)
Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B
2005-07-01
The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.
Xiangjie, Zhao; Cangli, Liu; Jiazhu, Duan; Jiancheng, Zeng; Dayong, Zhang; Yongquan, Luo
2014-06-16
Polymer network liquid crystal (PNLC) was one of the most potential liquid crystal for submillisecond response phase modulation, which was possible to be applied in submillisecond response phase only spatial light modulator. But until now the light scattering when liquid crystal director was reoriented by external electric field limited its phase modulation application. Dynamic response of phase change when high voltage was applied was also not elucidated. The mechanism that determines the light scattering was studied by analyzing the polymer network morphology by SEM method. Samples were prepared by varying the polymerization temperature, UV curing intensity and polymerization time. The morphology effect on the dynamic response of phase change was studied, in which high voltage was usually applied and electro-striction effect was often induced. The experimental results indicate that the polymer network morphology was mainly characterized by cross linked single fibrils, cross linked fibril bundles or even both. Although the formation of fibril bundle usually induced large light scattering, such a polymer network could endure higher voltage. In contrast, although the formation of cross linked single fibrils induced small light scattering, such a polymer network cannot endure higher voltage. There is a tradeoff between the light scattering and high voltage endurance. The electro-optical properties such as threshold voltage and response time were taken to verify our conclusion. For future application, the monomer molecular structure, the liquid crystal solvent and the polymerization conditions should be optimized to generate optimal polymer network morphology.
Decreased emotional reactivity of rats exposed to repeated phase shifts of light-dark cycle.
Okuliarova, Monika; Molcan, Lubos; Zeman, Michal
2016-03-15
Disturbed light-dark (LD) cycles are associated with circadian disruption of physiological and behavioural rhythms and in turn with an increased risk of disease development. However, direct causal links and underlying mechanisms leading to negative health consequences still need to be revealed. In the present study, we exposed male Wistar rats to repeated phase shifts of LD cycle and analysed their ability to cope with mild emotional stressors. In experiment 1, rats were submitted to either a regular 12:12 LD cycle (CTRL rats) or 8-h phase delay shifts applied every 2days for 5weeks (SHIFT rats). Subsequently, the behaviour was examined in the open-field, black-white box and elevated plus maze tests. In experiment 2, changes in blood pressure (BP), heart rate (HR) as well as the activity of autonomic nervous system were measured in telemeterised rats in response to open-field and black-white box tests before and after 5-week exposure to shifted LD regime. Locomotor activity was consistently higher in SHIFT than CTRL rats in in the open-field and black-white box tests. Interestingly, in the elevated plus maze, SHIFT rats displayed increased risk assessment and decreased grooming compared to CTRL rats. Anxiety measures were affected only in the black-white box, where SHIFT rats displayed reduced anxiety-like behaviour compared to CTRL rats. Differences in behavioural reactivity between SHIFT and CTRL rats did not correspond with BP and HR changes. However, exposure to phase shifts increased the sympathovagal reactivity in the black-white box. Together, our results demonstrated that disturbed LD conditions decreased emotional reactivity of rats and affected their ability to cope with emotional stressors denoting an additional risk mechanism linking disrupted circadian organisation to adverse health effects. Copyright © 2016 Elsevier Inc. All rights reserved.
Obermann, Anne; Larose, Eric; Margerin, Ludovic; Rossetto, Vincent
2014-05-01
We analyze the statistics of phase fluctuations of seismic signals obtained from a temporary small aperture array deployed on a volcano in the French Auvergne. We demonstrate that the phase field satisfies Circular Gaussian statistics. We then determine the scattering mean free path of Rayleigh waves from the spatial phase decoherence. This phenomenon, observed for diffuse wavefields, is found to yield a good approximation of the scattering mean free path. Contrary to the amplitude, spatial phase decoherence is free from absorption effects and provides direct access to the scattering mean free path. Our method may find applications in various areas of seismology where the effects of scattering are prominent and a knowledge of the scattering properties is necessary to describe the propagation. As an example, an unbiased estimate of the scattering mean free path is crucial for the localization of changes in multiply scattering media, where a sensitivity kernel based on diffusion theory is used (Larose et al. 2010; Obermann et al. 2013a,b). Our experimental approach may also provide independent estimates of the scattering mean free path in volcanic areas where particularly strong scattering has been proposed, based on the fitting of energy envelopes using energy transport approaches (Wegler & Lühr 2001; Yamamoto & Sato 2010). References: Larose, E., Planès, T., Rossetto, V. & Margerin, L., 2010. Locating a small change in a multiple scattering environment, Appl. Phys. Lett., 96(204101), 1-3. Obermann, A., Planès, T., Larose, E. & Campillo, M., 2013a. Imaging pre and co-eruptive structural and mechanical changes on a volcano with ambient seismic noise, J. geophys. Res., 118, 1-10. Obermann, A., Planès, T., Larose, E., Sens-Schönfelder, C. & Campillo,M., 2013b. Depth sensitivity of seismic coda waves to velocity perturbations in an elastic heterogeneous medium, Geophys. J. Int., 194(1), 372-382. Wegler, U. & Lühr, B.G., 2001. Scattering behaviour at Merapi volcano
The phase shift between the hemispheres in the solar activity cycle
Shibalova, A. S.; Obridko, V. N.; Sokoloff, D. D.
2016-10-01
The shift between the solar activity cycles in the northern and southern hemispheres of the Sun is studied using data on sunspot number and area. The data obtained are compared with archival information on episodes of appreciable solar-cycle asymmetry. The small phase shift between recent activity cycles in the northern and southern solar hemispheres differs considerably from the shift for episodes of appreciable deviations from dipolar symmetry in the sunspot distribution detected with various degrees of confidence in archival astronomical data from the 17th-19th centuries. The current time shift between the hemispheres is insignificant, about 6-7 months. This shift has changed its sign twice in recent solar history; this probably corresponds to more or less periodic variations with a timescale close to the duration of the Gleissberg cycle.
Directory of Open Access Journals (Sweden)
Y. Zhang
2016-06-01
Full Text Available Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i A complete setup of the structured light based 3D scanning system; (ii A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the
Phase shift improvement in ArF/KrF haze-free mask cleaning
Liu, Cathy; Zhao, Shirley; Guo, Eric; Hasegawa, Shinichi; Nemoto, Keiichi; Kuwajima, Tsuneaki
2008-10-01
The continuous evolution of LSI design rules has created an increased demand for the use of KrF and ArF phase-shift photomasks (EPSMs). One of the critical issues in the use of those photomasks, especially ArF half-tone photomasks, has been the generation of optical hazes known as (NH4)2SO4. The other critical issue has been a relatively large phase shift of those ArF and KrF photomasks caused by so-called haze-free mask cleaning.. In the present study we used an SPM integrated clean (as a reference) consisting of heated SPM, diluted SC-1 and heated UPW (widely known for rinsing), and a haze-free integrated mask clean consisting of Ozonated-water with a simultaneous 222nm Excimer UV irradiation, diluted SC-1 and heated UPW. We found that both Ozonated-water with a simultaneous 222nm Excimer UV irradiation and the diluted SC-1 (the components of the haze-free integrated clean) caused a sizable phase shift during the mask clean. We also found that the other component of the haze-free integrated clean, the heated UPW developed a relatively large phase shift in those photomasks. We have confirmed that the more we repeat the use of the 172nm Excimer UV light irradiation treatment before the clean, the less (more improved) phase shift has been realized in the haze-free clean. We found that the haze-free integrated clean also developed the CD shifts of the above photomasks and that those CD shifts could be recovered (reduced) drastically by the use of the 172nm Excimer UV light irradiation before the clean.
Derivation of new equations for phase-shift cavity ring-down spectroscopy.
Reid, Graham D; Robertson, Michael D; Tong, Anthony Z
2011-05-19
Current phase-shift cavity ring-down spectroscopy (PS-CRDS) experiments make use of equations originally developed for fluorescence studies. As these equations fail to take the length of the optical cavity and the superposition of reflecting beams into account, they lose validity as the length of the cavity increases. A new set of equations, based solely on the principles of PS-CRDS, is developed for determining the ring-down time from either the phase shift or the intensity of the waveform exiting the cavity. It is shown that the PS-CRDS equations reduce to those developed for fluorescence study for short cavities. The new equations provide a more accurate method in determining the characteristic ring-down time and phase shift for long cavities, especially fiber optic cavities, which is promising in on-site chemical sensing.
A novel method for identifying the order of interference using phase-shifting digital holography.
Sokkar, T Z N; El-Farahaty, K A; Ramadan, W A; Wahba, H H; Raslan, M I; Hamza, A A
2016-04-01
In this paper, we introduced a mathematical method for measuring the optical path length differences (OPDs), which is suitable for large OPD values where the fringes connections are difficult to detect. The proposed method is based on varying the width of the fringes, without changing the wavelength of the used coherent source. Also, in this work, we discussed the need for such method in off-axis phase-shifting digital holography. Low-resolution off-axis holograms failed to detect the correct interference order. In general, off-axis phase-shifting digital holography is limited by the resolution of the captured holograms. The results obtained using our proposed technique were compared to the results obtained using off-axis phase-shifting digital holograms and conventional two-beam interferometry. Holograms were given for illustration. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.
Duffing revisited: Phase-shift control and internal resonance in self-sustained oscillators
Arroyo, Sebastián I
2014-01-01
We address two aspects of the dynamics of the forced Duffing oscillator which are relevant to the technology of micromechanical devices and, at the same time, disclose new effects of nonlinearities on oscillating systems. First, we study the stability of periodic motion when the phase shift between the external force and the oscillation is controlled -contrary to the standard case, where the control parameter is the frequency of the force. Phase-shift control is the operational configuration under which self-sustained oscillators -and, in particular, micromechanical oscillators- provide a frequency reference useful for time keeping. We show that, contrary to the standard forced Duffing oscillator, under phase-shift control oscillations are stable over the whole resonance curve. Second, we analyze a model for the internal resonance between the main Duffing oscillation mode and a higher-harmonic mode of a vibrating solid bar clamped at its two ends. We focus on the stabilization of the oscillation frequency whe...
Sherwin, Stuart; Pistor, Thomas V.; Neureuther, Andrew; Naulleau, Patrick
2017-03-01
Contact-hole layer patterning is expected to be one of the first applications for EUV lithography. Conventional absorber masks, however, are extremely inefficient for these layers, placing even more burden on the already challenging source power demands. To address this concern, a chromeless checker-board phase-shift mask for 25- nm dense contacts has been shown to provide a throughput gain of 8x based on characterization with the SHARP EUV microscope and 7x based on micro field patterning with the Berkeley MET. These promising experimental results warrant both assessment for implementation in practice and rigorous simulations for diagnosing 3D mask effects. In this paper we verify the theoretical benefits of phase-shift masks over traditional absorber masks in idealized Kirchhoff analysis, explore the sensitivity of patterning to deviations from the ideal scattered orders, model the etched multilayer using thin-film characteristic matrix analysis, and finally use rigorous 3D Finite-Time Time Domain (FTTD) simulations of etched multilayer masks to explore mitigation of 3D effects to achieve optimal mask designs for minimum-pitch line-space and contact array patterns.
Energy Technology Data Exchange (ETDEWEB)
Alekseev, A E; Potapov, V T [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino Branch, Fryazino, Moscow region (Russian Federation); Gorshkov, B G [OOO ' Petrofaiber' , Russia, Tula region, Novomoskovsk (Russian Federation)
2015-10-31
Sensitivity of a fibre scattered-light interferometer to external phase perturbations is studied for the first time. An expression is derived for an average power of a useful signal at the interferometer output under external harmonic perturbations in a signal fibre of the interferometer. It is shown that the maximum sensitivity of the scattered-light interferometer depends on the dispersion of the interferogram intensity. An average signal-to-noise ratio is determined theoretically and experimentally at the output of the interferometer at different amplitudes of external perturbations. Using the measured dependences of the signal-to-noise ratio, the threshold sensitivity of the fibre scattered-light interferometer to external phase perturbations is found. The results obtained can be used to optimise characteristics of optical time-domain reflectometers and to design individual phase-sensitive fibre-optic sensors. (laser applications and other topics in quantum electronics)
Zhang, Yu; Tian, Xiaobo; Liang, Rongguang
2017-10-30
To reduce the environmental errors, a snapshot phase-shifting interference microscope (SPSIM) has been developed for surface roughness measurement. However, fringe-print-through (FPT) error widely exists in the phase-shifting interferometry (PSI). To ensure the measurement accuracy, we analyze the sources which introduce the FPT error in the SPSIM. We also develop a FPT error correction algorithm which can be used in the different intensity distribution conditions. The simulation and experiment verify the correctness and feasibility of the FPT error correction algorithm.
Effect of asymmetric actuator and detector position on Coriolis flowmeter and measured phase shift
DEFF Research Database (Denmark)
Enz, Stephanie
2010-01-01
Coriolis flowmeters (CFM) are forced to vibrate by a periodic excitation usually applied midpipe through an electromagnetic actuator. From hands-on experience with industrial CFMs it appears, that the electromagnetic actuator has to be located as symmetric as possible. For CFM design and trouble-shooting...... position, e.g. due to manufacturing variations or improper handling of the CFM, induces a phase shift that leads to changes of the meter’s sensitivity, and could therefore result into erroneous measurements of the mass flow. This phase shift depends on the mass flow and does not contribute to a lacking...
Perim de Faria, Julia; Bundke, Ulrich; Freedman, Andrew; Petzold, Andreas
2015-04-01
Monitoring the direct impact of aerosol particles on climate requires the consideration of at least two major factors: the aerosol single-scattering albedo, defined as the relation between the amount of energy scattered and extinguished by an ensemble of aerosol particles; and the aerosol optical depth, calculated from the integral of the particle extinction coefficient over the thickness of the measured aerosol layer. Remote sensing networks for measuring these aerosol parameters on a regular basis are well in place (e.g., AERONET, ACTRIS), whereas the regular in situ measurement of vertical profiles of atmospheric aerosol optical properties remains still an important challenge in quantifying climate change. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. Recently, a compact and robust family of optical instruments based on the cavity attenuated phase shift (CAPS) technique has become available for measuring aerosol light extinction. In particular, the CAPS PMex particle optical extinction monitor has demonstrated sensitivity of less than 2 Mm-1 in 1 second sampling period; with a 60 s averaging time, a detection limit of less than 0.3 Mm-1 can be achieved. While this technique was successfully deployed for ground-based atmospheric measurements under various conditions, its suitability for operation aboard aircraft in the free and upper free troposphere still has to be demonstrated. Here, we report on the modifications of a CAPS PMex instrument for measuring aerosol light extinction on aircraft, and subsequent laboratory tests for evaluating the modified instrument prototype: (1) In a
DEFF Research Database (Denmark)
Yang, Yongheng; Davari, Pooya; Zare, Firuz
2017-01-01
on the loading condition of each drive unit as well as the number of drives in parallel. In order to enhance the harmonic cancellation by means of the phase-shifted current control, the currents drawn by the rectifiers should be maintained almost at the same level. Thus, this paper firstly analyzes the impact...
Characteristics of the Phase-shifting Transformer Realized According to the "Polygon" Connection
Directory of Open Access Journals (Sweden)
Kalinin L.P.
2017-12-01
Full Text Available The object of the study is a two-transformer phase-shifting device with a span of adjustment of the angle of phase shift . In order to determine the energy characteristics of the investigated device, it has been put the scope to study the regime's parameters, performing adjustment of the angle of phase shift. This was made possible due to the use of the thyristor key for 10 positions and the low of it’s switching. The model was developed for a series of computational experiments for the cases of: idle, short circuit and loaded regime. A comparative analysis of the technical characteristics of the studied device, with the phase-reversing transformers investigated earlier has been carried out. The novelty of the work consists in the development of a scheme of a two-transformer phase regulating device. The additional winding of the magnetizing transformer was connected on an opposite side to the winding of the phase-shifting transformer. It has been achieved a reduction in the value of the magnetic induction in the core, as well as an increase of the stability in the process of adjusting the angle of phase shift. The analysis of the obtained characteristics of the device made it possible, by comparison with the available variants of existing circuits, to conclude that the developed one was of increased technical efficiency. The proposed technical solution decreased the installed capacity of the equipment, which in turn lead to a reduction of the weight and size indices and, as a consequence, of its cost.
Phase shifting-based debris effect detection in USV-assisted AFM nanomachining
Shi, Jialin; Liu, Lianqing; Yu, Peng; Cong, Yang; Li, Guangyong
2017-08-01
Atomic force microscopy (AFM) mechanical-based lithography attracts much attention in nanomanufacturing due to its advantages of low cost, high precision and high resolution. However, debris effects during mechanical lithography often lead to an unstable machining process and inaccurate results, which limits further applications of AFM-based lithography. There is a lack of a real-time debris detection approach, which is the prerequisite to eventually eliminating the influence of the debris, and of a method that can solve the above problems well. The ultrasonic vibration (USV)-assisted AFM has the ability to sense the machining depth in real time by detecting the phase shifting of cantilever. However, whether the pile-up of debris affect the phase response of cantilever is still lack of investigation. Therefore, we analyzed the mechanism of the debris effect on force control mode and investigated the relationship between phase shifting and pile-up of debris. Theoretical analysis and experimental results reveal that the pile-up of debris have negligible effect on phase shifting of cantilever. Therefore, the phase shifting-based method can detect the debris effect on machining depth in force control mode of AFM machining.
Development of Michelson interferometer based spatial phase-shift digital shearography
Xie, Xin
Digital shearography is a non-contact, full field, optical measurement method, which has the capability of directly measuring the gradient of deformation. For high measurement sensitivity, phase evaluation method has to be introduced into digital shearography by phase-shift technique. Catalog by phase-shift method, digital phase-shift shearography can be divided into Temporal Phase-Shift Digital Shearography (TPS-DS) and Spatial Phase-Shift Digital Shearography (SPS-DS). TPS-DS is the most widely used phase-shift shearography system, due to its simple algorithm, easy operation and good phase-map quality. However, the application of TPS-DS is only limited in static/step-by-step loading measurement situation, due to its multi-step shifting process. In order to measure the strain under dynamic/continuous loading situation, a SPS-DS system has to be developed. This dissertation aims to develop a series of Michelson Interferometer based SPS-DS measurement methods to achieve the strain measurement by using only a single pair of speckle pattern images. The Michelson Interferometer based SPS-DS systems utilize special designed optical setup to introduce extra carrier frequency into the laser wavefront. The phase information corresponds to the strain field can be separated on the Fourier domain using a Fourier Transform and can further be evaluated with a Windowed Inverse Fourier Transform. With different optical setups and carrier frequency arrangements, the Michelson Interferometer based SPS-DS method is capable to achieve a variety of measurement tasks using only single pair of speckle pattern images. Catalog by the aimed measurand, these capable measurement tasks can be divided into five categories: 1) measurement of out-of-plane strain field with small shearing amount; 2) measurement of relative out-of-plane deformation field with big shearing amount; 3) simultaneous measurement of relative out-of-plane deformation field and deformation gradient field by using multiple
An inverse-scattering approach to the physics of transition metals ...
African Journals Online (AJOL)
A method is developed for the deduction of a transition metal ion potential from a knowledge of the phase-shift. The method used is based the distorted plane – wave scattering approximation for the deduction of non singular potentials from scattering phase shifts in an inverse scattering approach. The resulting electron ...
Photonic radio frequency phase-shift amplification by radio frequency interferometry.
Ayun, Moshe Ben; Schwarzbaum, Arye; Rosenberg, Seva; Pinchas, Monika; Sternklar, Shmuel
2015-11-01
We present a new technique for radio frequency (RF) phase-shift amplification based on RF interferometry and demonstrate it in an optical system. A striking feature of this amplifier is that the input phase noise is not amplified together with the input phase signal, so the phase sensitivity improves with higher phase amplification. We also predict that in the case of correlated amplitude noise, the sensitivity is not affected by the amplitude noise. With 600 MHz of modulated light and a phase amplification of 100, we demonstrate a phase resolution of 0.2 mrad, giving a distance resolution of 8 μm. We postulate that nanometric distance resolution can be achieved with sub-gigahertz modulation.
Phase retrieval with the reverse projection method in the presence of object's scattering
Wang, Zhili; Gao, Kun; Wang, Dajiang
2017-08-01
X-ray grating interferometry can provide substantially increased contrast over traditional attenuation-based techniques in biomedical applications, and therefore novel and complementary information. Recently, special attention has been paid to quantitative phase retrieval in X-ray grating interferometry, which is mandatory to perform phase tomography, to achieve material identification, etc. An innovative approach, dubbed ;Reverse Projection; (RP), has been developed for quantitative phase retrieval. The RP method abandons grating scanning completely, and is thus advantageous in terms of higher efficiency and reduced radiation damage. Therefore, it is expected that this novel method would find its potential in preclinical and clinical implementations. Strictly speaking, the reverse projection method is applicable for objects exhibiting only absorption and refraction. In this contribution, we discuss the phase retrieval with the reverse projection method for general objects with absorption, refraction and scattering simultaneously. Especially, we investigate the influence of the object's scattering on the retrieved refraction signal. Both theoretical analysis and numerical experiments are performed. The results show that the retrieved refraction signal is the product of object's refraction and scattering signals for small values. In the case of a strong scattering, the reverse projection method cannot provide reliable phase retrieval. Those presented results will guide the use of the reverse projection method for future practical applications, and help to explain some possible artifacts in the retrieved images and/or reconstructed slices.
Phase-shift interference-based wavefront characterization for orbital angular momentum modes.
Huang, Hao; Ren, Yongxiong; Yan, Yan; Ahmed, Nisar; Yue, Yang; Bozovich, Amanda; Erkmen, Baris I; Birnbaum, Kevin; Dolinar, Sam; Tur, Moshe; Willner, Alan E
2013-07-01
Wavefront characterization for orbital angular momentum (OAM) modes is demonstrated using quadrature phase-shift interference. The phase fronts and intensity profiles of OAM(-2), OAM(-4), OAM(-6), and OAM(-8) are measured. Wavefront correlations between the experimental results and the pure Laguerre-Gaussian modes are calculated to evaluate the measurement. The measured results are in reasonable agreement with the anticipated results based on simulations.
Imaging behavior of high-transmission attenuating phase-shift mask films
Hibbs, Michael; Nemoto, Satoru; Komizo, Toru
2006-10-01
The properties of phase shifting attenuator films are quantified in a variety of ways. Transverse dimensions are measured by optical microscopes or scanning electron microscopes. Vertical dimension and profiles are measured by atomic force microscopes or indirectly by optical scatterometry. The complex refractive index of an attenuator film can be characterized by ellipsometry or by spectroscopic analysis of reflected and transmitted light. Transmission and phase measurements can be made with optical interferometric techniques. Data acquired in these ways can be used as inputs to simulation programs to model the image forming characteristics of the films. For simplicity and speed of calculation, the simulation programs typically use a thin-mask approximation, in which the vertical absorber geometry is ignored and the phase shifting attenuator regions are characterized only by their transmission, phase shift, and two-dimensional geometric shapes. Inclusion of the full three-dimensional profile and complex refractive index of the absorber can be done, but at the cost of greatly increased calculation time and a loss of the simplicity of understanding afforded by the thin-mask model. For example, the thin-mask model assumes that every geometrical feature etched into a given attenuator film will have the same phase and transmission properties. Comparison of thin-mask modeling results with the full three dimensional model shows that this assumption is not true. The effective dimensional bias, phase, transmission, and defocus are strong functions of the feature size, pitch, and complex refractive index of the film. Three dimensional simulations were run for several commercial and developmental high-transmission phase-shifting attenuator films. The effective phase and dimensional printing bias were calculated as a function of pitch for each film. Surprising differences were found in the results for the various film types.
Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G; Steenbergen, Wiendelt
2007-01-01
In optical Doppler measurements, the path length of the light is unknown. To facilitate quantitative measurements, we develop a phase-modulated Mach-Zehnder interferometer with separate fibers for illumination and detection. With this setup, path-length-resolved dynamic light scattering measurements of multiple scattered light in static and dynamic turbid media are performed. Optical path length distributions spanning a range from 0 to 11 mm are measured from the area under the phase modulation peak around the modulation frequency in the power spectrum. A Doppler-broadened phase modulation interference peak is observed that shows an increase in the average Doppler shift with optical path length, independent of absorption. Validation of the estimated path length distributions is done by measuring their deformation for increasing absorption and comparing these observations with predictions based on Lambert-Beer's law.
Remark on the phase shift in the Kuzmak-Whitham ansatz
Dobrokhotov, S. Yu.; Minenkov, D. S.
2011-03-01
We consider one-phase ( formal) asymptotic solutions in the Kuzmak-Whitham form for the nonlinear Klein-Gordon equation and for the Korteweg-de Vries equation. In this case, the leading asymptotic expansion term has the form X( S( x, t)/ h+Φ( x, t), I( x, t), x, t) + O( h), where h ≪ 1 is a small parameter and the phase S}( x, t) and slowly changing parameters I( x, t) are to be found from the system of "averaged" Whitham equations. We obtain the equations for the phase shift Φ( x, t) by studying the second-order correction to the leading term. The corresponding procedure for finding the phase shift is then nonuniform with respect to the transition to a linear (and weakly nonlinear) case. Our observation, which essentially follows from papers by Haberman and collaborators, is that if we incorporate the phase shift Φ into the phase and adjust the parameter Ĩ by setting tilde S = S + hΦ+ O( h 2), Ĩ = I + hI 1 + O( h 2), then the functions tilde S ( x, t, h) and Ĩ( x, t, h) become solutions of the Cauchy problem for the same Whitham system but with modified initial conditions. These functions completely determine the leading asymptotic term, which is X( tilde S ( x, t, h)/ h, Ĩ( x, t, h), x, t) + O( h).
Multisoliton phase shifts in the case of a nonzero reflection coefficient
Schuur, P.
1984-01-01
We study multisoliton solutions of the Korteweg-de Vries equation in the case of a nonzero reflection coefficient. An explicit phase shift formula is derived that clearly displays the nature of the interaction of each soliton with the other ones and with the dispersive wavetrain. In particular, this
Performance Comparison of Phase Shifted PWM and Sorting Method for Modular Multilevel Converters
DEFF Research Database (Denmark)
Haddioui, Marcos Rejas; Máthé, Lászlo; Burlacu, Paul Dan
2015-01-01
on keeping the capacitor voltage ripple under some limit, unnecessary switching events are eliminated leading to reduced switching losses. This paper presents a comparison between the steady-state performances in terms of output voltage THD and equivalent switching frequency of the Phase Shifted Carrier PWM...
16-level differential phase shift keying (D16PSK) in direct detection optical communication systems
DEFF Research Database (Denmark)
Sambaraju, R.; Tokle, Torger; Jensen, J.B.
2006-01-01
Optical 16-level differential phase shift keying (D16PSK) carrying four bits for every symbol is proposed for direct detection optical communication systems. Transmitter and receiver schematics are presented, and the receiver sensitivity is discussed. We numerically investigate the impact...
X-ray phase-shifts-based method of volumetric breast density measurement
Wu, Xizeng; Yan, Aimin; Liu, Hong
2012-01-01
Purpose: The high breast density is one of the biggest risk factors for breast cancer. Identifying patient having persistent high breast density is important for breast cancer screening and prevention. In this work the authors propose for the first time an x-ray phase-shifts-based method of breast density measurement.
Predicting phase shift of elastic waves in pipes due to fluid flow and imperfections
DEFF Research Database (Denmark)
Thomsen, Jon Juel; Dahl, Jonas; Fuglede, Niels
2009-01-01
. This is relevant for understanding wave propagation in elastic media in general, and for the design and trouble-shooting of phase-shift measuring devices such as Coriolis mass flowmeters in particular. A multiple time scaling perturbation analysis is employed for a simple model of a fluid-conveying pipe...
Acute and phase-shifting effects of ocular and extraocular light in human circadian physiology
Rüger, Melanie; Gordijn, Marijke C.M.; Beersma, Domien G.M.; de Vries, Bonnie; Daan, Serge
2003-01-01
Light can influence physiology and performance of humans in two distinct ways. It can acutely change the level of physiological and behavioral parameters, and it can induce a phase shift in the circadian oscillators underlying variations in these levels. Until recently, both effects were thought to
Presumption of Phase Shift in Resonant Dynamical Systems using Wigner-Ville Distribution Function
Niimi, Hironobu; Yatsu, Shigeo; Kayukawa, Naoyuki
2002-02-01
The time evolution of the forced and eigen oscillation modes of a basic rotor model induced by an external force with frequencies of linear functions of time was analyzed by means of the Wigner-Ville distribution function. The instantaneous frequency of the forced oscillation was extracted from the spectrum distribution on the time-frequency plane, and the phase shift between the forced oscillation and the external force was calculated for both weak and strong nonstationariness cases. In the latter case, neither forced nor eigen modes could be separated definitely around the resonant point. This resulted in a discrepancy of the asymptotic value of the phase shift from π in cooperation with the finite frequency resolution. It was shown that the phase shift in this “mixed mode region” could be numerically traced and the bifurcation point could be approximately identified on the basis of the finding that the asymptotic value of the phase shift in the present model was π, irrespective of the nonstationariness.
Quadrature phase shift keying coherent state discrimination via a hybrid receiver
DEFF Research Database (Denmark)
Müller, C. R.; Castaneda, Mario A. Usuga; Wittmann, C.
2012-01-01
We propose and experimentally demonstrate a near-optimal discrimination scheme for the quadrature phase shift keying (QPSK) protocol. We show in theory that the performance of our hybrid scheme is superior to the standard scheme—heterodyne detection—for all signal amplitudes and underpin the pred...
Directory of Open Access Journals (Sweden)
Chun-Woo Lee
2017-05-01
Full Text Available Development in mathematical formulations of parameterizing the resonance structures using the phase-shifted multichannel quantum defect theory (MQDT and their use in analyzing the effect of inter-series interactions on the autoionizing Rydberg spectra is reviewed. Reformulation of the short-range scattering matrix into the form analogous to S = SBSR in scattering theory are the crucial step in this development. Formulation adopts different directions and goals depending on whether autoionizing series converge to the same limit (degenerate or to different limits (nondegenerate because of the different nature of the perturbation. For the nondegenerate case, finding the simplest form of profile index functions of the autoionizing spectra with the minimal number of parameters is the main goal and some results are reviewed. For the degenerate case where perturbation acts uniformly throughout the entire series, isolation of the overlapped autoionizing series into the unperturbed autoionizing series is the key objective in research and some results in that direction are reviewed.
Energy Technology Data Exchange (ETDEWEB)
Woodruff, D.P. E-mail: d.p.woodruff@warwick.ac.uk; Brown, D.; Quinn, P.D.; Noakes, T.C.Q.; Bailey, P
2001-07-01
Through a series of investigations of the quantitative structure of monolayer surface alloy phases of Cu(1 0 0)/Au, Cu(1 0 0)/Mn, Cu(1 1 1)/Sb and Ni(1 1 1)/Pb a number of aspects of the methodology of medium energy ion scattering (MEIS) have been investigated. These include the form of reliability-factors (R-factors) used to provide an objective test of the fit of experimental blocking curves and those simulated for different model structures, and the criteria used to define the precision and uniqueness of such models. The role of absolute calibration of the scattered ion yields and the appropriate choice of scattering geometry are also discussed in the context of these specific studies. The quantitative results for these surface alloy structures also cast some light on the effective atomic radii in such structures and highlight the general trend for phases with low surface corrugation or rumpling.
Submillisecond-response and scattering-free infrared liquid crystal phase modulators.
Sun, Jie; Chen, Yuan; Wu, Shin-Tson
2012-08-27
We demonstrate a submillisecond-response and scattering-free infrared phase modulator using a polymer network liquid crystal (PNLC). The required voltage for achieving 2π phase change at λ = 1.06 µm is 70V (or 5.8 V/μm) and the measured response time is ~200 µs at 25°C and 30 µs at 70°C. Opposite to our conventional understanding, a high viscosity LC helps to achieve small domain size during polymerization process, which in turn reduces the response time and light scattering. We use Rayleigh-Gans-Debye scattering model to analyze the voltage-on state transmission spectra. When the domain size is comparable to the wavelength, the model fits with experimental results well. But when the domain size is smaller than the wavelength, the simple Rayleigh model works well.
FREQUENCY SHIFTS OF RESONANT MODES OF THE SUN DUE TO NEAR-SURFACE CONVECTIVE SCATTERING
Energy Technology Data Exchange (ETDEWEB)
Bhattacharya, J.; Hanasoge, S.; Antia, H. M. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai-400005 (India)
2015-06-20
Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modeled frequencies, a phenomenon referred to as the “surface term.” The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modeling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelengths (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun. We show that the full oscillation equations, in the presence of temporally stationary three-dimensional (3D) flows, can be reduced to an effective “quiet-Sun” wave equation with altered sound speed, Brünt–Väisäla frequency, and Lamb frequency. We derive the modified equation and relations for the appropriate averaging of 3D flows and thermal quantities to obtain the properties of this effective medium. Using flows obtained from 3D numerical simulations of near-surface convection, we quantify their effect on solar oscillation frequencies and find that they are shifted systematically and substantially. We argue therefore that consistent interpretations of resonant frequencies must include modifications to the wave equation that effectively capture the impact of vigorous hydrodynamic convection.
Phase stabilized homodyne of infrared scattering type scanning near-field optical microscopy
Energy Technology Data Exchange (ETDEWEB)
Xu, Xiaoji G., E-mail: xgx214@lehigh.edu [Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Gilburd, Leonid; Walker, Gilbert C., E-mail: gwalker@chem.utoronto.ca [Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)
2014-12-29
Scattering type scanning near-field optical microscopy (s-SNOM) allows sub diffraction limited spatial resolution. Interferometric homodyne detection in s-SNOM can amplify the signal and extract vibrational responses based on sample absorption. A stable reference phase is required for a high quality homodyne-detected near-field signal. This work presents the development of a phase stabilization mechanism for s-SNOM to provide stable homodyne conditions. The phase stability is found to be better than 0.05 rad for the mid infrared light source. Phase stabilization results in improved near field images and vibrational spectroscopies. Spatial inhomogeneities of the boron nitride nanotubes are measured and compared.
Quantum scattering in one dimension
Energy Technology Data Exchange (ETDEWEB)
Barlette, Vania E. [Centro Universitario Franciscano, Santa Maria, RS (Brazil); Leite, Marcelo M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil); Adhikari, Sadhan K. [Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, SP (Brazil)
2000-09-01
A self-contained discussion of non-relativistic quantum scattering is presented in the case of central potentials in one space dimension, which will facilitate the understanding of the more complex scattering theory in two and three dimensions. The present discussion illustrates in a simple way the concepts of partial-wave decomposition, phase shift, optical theorem and effective-range expansion. (author)
Coulomb correction to elastic. alpha. -. alpha. scattering
Energy Technology Data Exchange (ETDEWEB)
Bera, P.K.; Jana, A.K.; Haque, N.; Talukdar, B. (Department of Physics, Visva-Bharati University, Santiniketan-731235, West Bengal, India (IN))
1991-02-01
The elastic {alpha}-{alpha} scattering is treated within the framework of a generalized phase-function method (GPFM). This generalization consists in absorbing the effect of Coulomb interaction in the comparison functions for developing the phase equation. Based on values of scattering phase shifts computed by the present method, it is concluded that the GPFM provides an uncomplicated approach to rigorous Coulomb correction in the {alpha}-{alpha} scattering.
Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue
González, C. A.; Lozano, L. M.; Uscanga, M. C.; Silva, J. G.; Polo, S. M.
2013-04-01
Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.
Vibrational Phase Contrast Microscopy by Use of Coherent Anti-Stokes Raman Scattering
Jurna, M.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.
2009-01-01
In biological samples the resonant coherent anti-Stokes Raman scattering signal of less abundant constituents can be overwhelmed by the nonresonant background, preventing detection of those molecules. We demonstrate a method to obtain the phase of the oscillators in the focal volume that allows
DEFF Research Database (Denmark)
Andersen, Lasse Mejling; McKinstrie, C. J.; Rottwitt, Karsten
2013-01-01
Recently, we solved the coupled-mode equations for Bragg scattering (BS) in the low- and high-conversion regimes, but without the effects of nonlinear phase modulation (NPM). We now present solutions and Green functions in the low-conversion regime that include NPM. We find that NPM does not change...
On the role of inelastic scattering in phase-plate transmission electron microscopy.
Hettler, Simon; Wagner, Jochen; Dries, Manuel; Oster, Marco; Wacker, Christian; Schröder, Rasmus R; Gerthsen, Dagmar
2015-08-01
The phase contrast of Au nanoparticles on amorphous-carbon films with different thicknesses is analyzed using an electrostatic Zach phase plate in a Zeiss 912 Ω transmission electron microscope with in-column energy filter. Specifically, unfiltered and plasmon-filtered phase-plate transmission electron microscopy (PP TEM) images are compared to gain insight in the role of coherence after inelastic scattering processes. A considerable phase-contrast contribution resulting from a combined elastic-inelastic scattering process is found in plasmon-filtered PP TEM images. The contrast reduction compared to unfiltered images mainly originates from zero-order beam broadening caused by the inelastic scattering process. The effect of the sequence of the elastic and inelastic scattering processes is studied by varying the position of the nanoparticles, which can be either located on top or at the bottom of the amorphous-carbon film with respect to the incident electron beam direction. Copyright © 2015 Elsevier B.V. All rights reserved.
Vaudelle, Fabrice; L'Huillier, Jean-Pierre; Askoura, Mohamed Lamine
2017-06-01
Red and near-Infrared light is often used as a useful diagnostic and imaging probe for highly scattering media such as biological tissues, fruits and vegetables. Part of diffusively reflected light gives interesting information related to the tissue subsurface, whereas light recorded at further distances may probe deeper into the interrogated turbid tissues. However, modelling diffusive events occurring at short source-detector distances requires to consider both the distribution of the light sources and the scattering phase functions. In this report, a modified Monte Carlo model is used to compute light transport in curved and multi-layered tissue samples which are covered with a thin and highly diffusing tissue layer. Different light source distributions (ballistic, diffuse or Lambertian) are tested with specific scattering phase functions (modified or not modified Henyey-Greenstein, Gegenbauer and Mie) to compute the amount of backscattered and transmitted light in apple and human skin structures. Comparisons between simulation results and experiments carried out with a multispectral imaging setup confirm the soundness of the theoretical strategy and may explain the role of the skin on light transport in whole and half-cut apples. Other computational results show that a Lambertian source distribution combined with a Henyey-Greenstein phase function provides a higher photon density in the stratum corneum than in the upper dermis layer. Furthermore, it is also shown that the scattering phase function may affect the shape and the magnitude of the Bidirectional Reflectance Distribution (BRDF) exhibited at the skin surface.
Phase of Target Scattering for Wetland Characterization using Polarimetric C-Band SAR
Energy Technology Data Exchange (ETDEWEB)
Touzi, R [Argonne National Laboratory (ANL); Deschamps, Mireille C [ORNL; Rother, Gernot [ORNL
2009-09-01
Wetlands continue to be under threat, and there is a major need for mapping and monitoring wetlands for better management and protection of these sensitive areas. Only a few studies have been published on wetland characterization using polarimetric synthetic aperture radars (SARs). The most successful results have been obtained using the phase difference between HH and VV polarizations, phi{sub HH} - phi{sub VV}, which has shown promise for separating flooded wetland classes. Recently, we have introduced a new decomposition, the Touzi decomposition, which describes target scattering type in terms of a complex entity, the symmetric scattering type. Huynen's target helicity is used to assess the symmetric nature of target scattering. In this paper, the new complex-scattering-type parameters, the magnitude alphas and phase Phi{sub alpha} s, are investigated for wetland characterization. The use of the dominant-scattering-type phase Phi{sub alpha} s makes it possible to discriminate shrub bogs from poor (sedge or shrub) fens. These two classes cannot be separated using phi{sub HH} - phi{sub VV}, or the radiometric scattering information provided by alphas, the Cloude alpha, the entropy H, and the multipolarization HH-HV-VV channels. phi{sub alpha} s, which cannot detect deep (45 cm below the peat surface) water flow in a bog, is more sensitive to the shallower (10-20-cm) fen beneath water, and this makes possible the separation of poor fens from shrub bogs. Phi{sub alpha} s also permits the discrimination of conifer-dominated treed bog from upland deciduous forest under leafy conditions. Target helicity information is exploited to introduce a new parameter, the target asymmetry. The latter is shown very promising for detection of forest changes between leafy and no-leaf conditions. The analysis of low-entropy marsh scattering showed that both the scattering-type magnitude and phas- - e alphas and Phi{sub alpha} s, respectively, as well as the maximum polarization
Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G.; Steenbergen, Wiendelt
2006-04-01
We report the development of non-invasive, path length resolved Doppler measurements of the multiply scattered light in turbid media, for different absorptions using phase modulated Mach-Zehnder low coherence interferometer, with separate fibers for illumination and detection. A Doppler broadened phase modulation interference peak is observed that shows an increase in the average Doppler shift with optical path length, independent of absorption. The estimated path length distributions indicate suppression and narrowing for increasing absorption and can be related by Lambert-Beer's law.
Band-gaps in long Josephson junctions with periodic phase-shifts
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Saeed, E-mail: saeedahmad@uom.edu.pk [Department of Mathematics, University of Malakand Chakdara, Dir(L), Pakhtunkhwa (Pakistan); Susanto, Hadi, E-mail: hsusanto@essex.ac.uk [Department of Mathematical Sciences, University of Essex, Colchester CO4 3SQ (United Kingdom); Wattis, Jonathan A.D. [School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)
2017-04-04
We investigate analytically and numerically a long Josephson junction on an infinite domain, having arbitrary periodic phase shift of κ, that is, the so-called 0–κ long Josephson junction. The system is described by a one-dimensional sine-Gordon equation and has relatively recently been proposed as artificial atom lattices. We discuss the existence of periodic solutions of the system and investigate their stability both in the absence and presence of an applied bias current. We find critical values of the phase-discontinuity and the applied bias current beyond which static periodic solutions cease to exist. Due to the periodic discontinuity in the phase, the system admits regions of allowed and forbidden bands. We perturbatively investigate the Arnold tongues that separate the region of allowed and forbidden bands, and discuss the effect of an applied bias current on the band-gap structure. We present numerical simulations to support our analytical results. - Highlights: • A long Josephson junction on an infinite domain having arbitrary periodic phase shift has been proposed as artificial atom lattices recently. • We compute the band-gaps of the system asymptotically. • We show that the phase-shift and applied bias current can be used to control the band structures.
A simple phase-shift ESPI for 3D deformation measurement
Sun, Ping; Wang, Xinghai; Sun, Haibin
2016-11-01
A simple setup for 3-D deformation measurement is offered. In the scheme a novel Cube Beam-Splitter, called Non- Cube Beam-Splitter (NCBS), is used for 3-D phase-shift Electronic Speckle Pattern Interferometry (ESPI). By using the NCBS lights from a tested object and lights from a reference surface, the reference and the object light can be combined and then interfere each other on a CCD camera when a laser beam illuminate the test object and the reference surface simultaneously. When three laser beams illuminate the test object at different incident angles respectively before and after deformation, three interference fringe patterns are formed. Then three phase maps corresponding to three lasers can be calculated by using phase-shift, by which three displacement components are completed. The principle of the method is presented and proved by a typical three-point bending experiment. Experimental results are offered.
Wavelet filtered shifted phase-encoded joint transform correlation for face recognition
Moniruzzaman, Md.; Alam, Mohammad S.
2017-05-01
A new wavelet-filtered-based Shifted- phase-encoded Joint Transform Correlation (WPJTC) technique has been proposed for efficient face recognition. The proposed technique uses discrete wavelet decomposition for preprocessing and can effectively accommodate various 3D facial distortions, effects of noise, and illumination variations. After analyzing different forms of wavelet basis functions, an optimal method has been proposed by considering the discrimination capability and processing speed as performance trade-offs. The proposed technique yields better correlation discrimination compared to alternate pattern recognition techniques such as phase-shifted phase-encoded fringe-adjusted joint transform correlator. The performance of the proposed WPJTC has been tested using the Yale facial database and extended Yale facial database under different environments such as illumination variation, noise, and 3D changes in facial expressions. Test results show that the proposed WPJTC yields better performance compared to alternate JTC based face recognition techniques.
Xie, Xin; Xu, Nan; Sun, Jianfei; Wang, Yonghong; Yang, Lianxiang
2013-01-01
This paper presents a spatial phase-shift digital shearography system based on a modified Michelson Interferometer, which is capable of measuring out-of-plane deformation and its first derivative simultaneously. A reference beam is introduced into the Michelson Interferometer using an optical fiber. Two sheared images from the Michelson Interferometer are combined with the reference beam to generate two holograms and one shearogram. The Fourier Transform method is utilized to calculate the phase difference. To separate the spectrum in the Fourier Domain, the reference beam is tilted a small angle to create a spatial phase shift. An out-of-plane deformation and its first derivative can then be determined simultaneously from a single speckle interferogram by properly selecting filters for the spectrum image. The theory and the experimental results are presented.
Directory of Open Access Journals (Sweden)
Zhiguo Zhao
2014-01-01
Full Text Available Based on the independently developed five-speed dry dual clutch transmission (DDCT, the paper proposes the torque coordinating control strategy between engine and two clutches, which obtains engine speed and clutch transferred torque in the shifting process, adequately reflecting the driver intention and improving the shifting quality. Five-degree-of-freedom (DOF shifting dynamics model of DDCT with single intermediate shaft is firstly established according to its physical characteristics. Then the quantitative control objectives of the shifting process are presented. The fuzzy decision of shifting time and the model-based torque coordinating control strategy are proposed and also verified by simulating under different driving intentions in up-/downshifting processes with the DCT model established on the MATLAB/Simulink. Simulation results validate that the shifting control algorithm proposed in this paper can not only meet the shifting quality requirements, but also adapt to the various shifting intentions, having a strong robustness.
Phase-shift inversion in oscillator systems with periodically switching couplings.
Lee, Sang Hoon; Lee, Sungmin; Son, Seung-Woo; Holme, Petter
2012-02-01
A system's response to external periodic changes can provide crucial information about its dynamical properties. We investigate the synchronization transition, an archetypical example of a dynamic phase transition, in the framework of such a temporal response. The Kuramoto model under periodically switching interactions has the same type of phase transition as the original mean-field model. Furthermore, we see that the signature of the synchronization transition appears in the relative delay of the order parameter with respect to the phase of oscillating interactions as well. Specifically, the phase shift becomes significantly larger as the system gets closer to the phase transition, so that the order parameter at the minimum interaction density can even be larger than that at the maximum interaction density, counterintuitively. We argue that this phase-shift inversion is caused by the diverging relaxation time, in a similar way to the resonance near the critical point in the kinetic Ising model. Our result, based on exhaustive simulations on globally coupled systems as well as scale-free networks, shows that an oscillator system's phase transition can be manifested in the temporal response to the topological dynamics of the underlying connection structure.
A coral-algal phase shift in Mesoamerica not driven by changes in herbivorous fish abundance.
Directory of Open Access Journals (Sweden)
Jesús Ernesto Arias-González
Full Text Available Coral-algal phase shifts in which coral cover declines to low levels and is replaced by algae have often been documented on coral reefs worldwide. This has motivated coral reef management responses that include restriction and regulation of fishing, e.g. herbivorous fish species. However, there is evidence that eutrophication and sedimentation can be at least as important as a reduction in herbivory in causing phase shifts. These threats arise from coastal development leading to increased nutrient and sediment loads, which stimulate algal growth and negatively impact corals respectively. Here, we first present results of a dynamic process-based model demonstrating that in addition to overharvesting of herbivorous fish, bottom-up processes have the potential to precipitate coral-algal phase shifts on Mesoamerican reefs. We then provide an empirical example that exemplifies this on coral reefs off Mahahual in Mexico, where a shift from coral to algal dominance occurred over 14 years, during which there was little change in herbivore biomass but considerable development of tourist infrastructure. Our results indicate that coastal development can compromise the resilience of coral reefs and that watershed and coastal zone management together with the maintenance of functional levels of fish herbivory are critical for the persistence of coral reefs in Mesoamerica.
A coral-algal phase shift in Mesoamerica not driven by changes in herbivorous fish abundance.
Arias-González, Jesús Ernesto; Fung, Tak; Seymour, Robert M; Garza-Pérez, Joaquín Rodrigo; Acosta-González, Gilberto; Bozec, Yves-Marie; Johnson, Craig R
2017-01-01
Coral-algal phase shifts in which coral cover declines to low levels and is replaced by algae have often been documented on coral reefs worldwide. This has motivated coral reef management responses that include restriction and regulation of fishing, e.g. herbivorous fish species. However, there is evidence that eutrophication and sedimentation can be at least as important as a reduction in herbivory in causing phase shifts. These threats arise from coastal development leading to increased nutrient and sediment loads, which stimulate algal growth and negatively impact corals respectively. Here, we first present results of a dynamic process-based model demonstrating that in addition to overharvesting of herbivorous fish, bottom-up processes have the potential to precipitate coral-algal phase shifts on Mesoamerican reefs. We then provide an empirical example that exemplifies this on coral reefs off Mahahual in Mexico, where a shift from coral to algal dominance occurred over 14 years, during which there was little change in herbivore biomass but considerable development of tourist infrastructure. Our results indicate that coastal development can compromise the resilience of coral reefs and that watershed and coastal zone management together with the maintenance of functional levels of fish herbivory are critical for the persistence of coral reefs in Mesoamerica.
Energy Technology Data Exchange (ETDEWEB)
Baba, Justin S [ORNL; John, Dwayne O [ORNL; Koju, Vijay [ORNL
2015-01-01
The propagation of light in turbid media is an active area of research with relevance to numerous investigational fields, e.g., biomedical diagnostics and therapeutics. The statistical random-walk nature of photon propagation through turbid media is ideal for computational based modeling and simulation. Ready access to super computing resources provide a means for attaining brute force solutions to stochastic light-matter interactions entailing scattering by facilitating timely propagation of sufficient (>10million) photons while tracking characteristic parameters based on the incorporated physics of the problem. One such model that works well for isotropic but fails for anisotropic scatter, which is the case for many biomedical sample scattering problems, is the diffusion approximation. In this report, we address this by utilizing Berry phase (BP) evolution as a means for capturing anisotropic scattering characteristics of samples in the preceding depth where the diffusion approximation fails. We extend the polarization sensitive Monte Carlo method of Ramella-Roman, et al.,1 to include the computationally intensive tracking of photon trajectory in addition to polarization state at every scattering event. To speed-up the computations, which entail the appropriate rotations of reference frames, the code was parallelized using OpenMP. The results presented reveal that BP is strongly correlated to the photon penetration depth, thus potentiating the possibility of polarimetric depth resolved characterization of highly scattering samples, e.g., biological tissues.
General framework for multiple scattering of polarized waves including anisotropies and Berry phase.
Rossetto, V
2009-11-01
We develop a framework for the multiple scattering of a polarized wave. We consider particles with spin propagating in a medium filled with scatterers. We write the amplitudes of each spin eigenstate in a local mobile frame. One of the axes is in the direction of propagation of the particle. We use this representation to define a directional Green's operator of the homogeneous medium and also to write the spin-dependent scattering amplitudes. We show that this representation reveals a Berry phase. We establish a generalized Green-Dyson equation for the multiple-scattering problem in this framework. We show that the generalized Green-Dyson equation can be solved by linear algebra if one uses a representation of the rotations based on Wigner D matrices. The properties of light scattering are retrieved if we use spin 1 particles. Our theory allows to take into account several kinds of anisotropies such as circular or linear dichroism and birefringence, Faraday effects, and Mie scattering within the same formalism. Several anisotropies can be present at the same time.
Solodovnyk, Anastasiia; Lipovšek, Benjamin; Forberich, Karen; Stern, Edda; Krč, Janez; Batentschuk, Miroslaw; Topič, Marko; Brabec, Christoph J.
2015-12-01
We studied the optical properties of polymer layers filled with phosphor particles in two aspects. First, we used two different polymer binders with refractive indices n = 1.46 and n = 1.61 (λ = 600 nm) to decrease Δn with the phosphor particles (n = 1.81). Second, we prepared two particle size distributions D50 = 12 μm and D50 = 19 μm. The particles were dispersed in both polymer binders in several volume concentrations and coated onto glass with thicknesses of 150 - 600 μm. We present further a newly developed optical model for simulation and optimization of such luminescent down-shifting (LDS) layers. The model is developed within the ray tracing framework of the existing optical simulator CROWM (Combined Ray Optics / Wave Optics Model), which enables simulation of standalone LDS layers as well as complete solar cells (including thick and thin layers) enhanced by the LDS layers for an improved solar spectrum harvesting. Experimental results and numerical simulations show that the layers of the higher refractive index binder with larger particles result in the highest optical transmittance in the visible light spectrum. Finally we proved that scattering of the phosphor particles in the LDS layers may increase the overall light harvesting in the solar cell. We used numerical simulations to determine optimal layer composition for application in realistic thin-film photovoltaic devices. Surprisingly LDS layers with lower measured optical transmittance are more efficient when applied onto the solar cells due to graded refractive index and efficient light scattering. Therefore, our phosphor-filled LDS layers could possibly complement other light-coupling techniques in photovoltaics.
Neutron Scattering Studies of Pre-Transitional Effects in Solid-Solid Phase Transformations
Energy Technology Data Exchange (ETDEWEB)
Shapiro, S. M.
1999-06-30
Neutron scattering studies have played a fundamental role in understanding solid-solid phase transformations, particularly in studying the lattice dynamical behavior associated with precursor effects. A review of the studies performed on solids exhibiting Martensitic transformations is given below. The mode softening and associated elastic diffuse scattering, previously observed in NiAl alloys, will be discussed as well as more recent work on Ni{sub 2}MnGa, a system exhibiting magnetic order as well as a Martensitic transformation. Also, new results on the precursor effects in ordered and disordered FePt alloys will be presented.
Quasielastic Diffuse Neutron Scattering from Fluorites in the Fast Ion Phase
DEFF Research Database (Denmark)
Clausen, K.; Hayes, W.; Hutchings, M.T
1981-01-01
Quasielastic diffuse coherent neutron scattering arising from the dynamically disordered anions in CaF2 and PbF2 has been investigated as the temperature is increased into the fast ion phase. The characteristic variation with scattering vector Image of the integrated intensity, S(Image ), can...... be accounted for by a model in which the most probable instantaneous configuration of the defective anions is a cluster centered at the mid-point of nearest-neighbour regular anion sites. The observed S(Image ,ω) is Lorentzian in ω and the width has a marked increase with temperature....
Carrier-separating demodulation of phase shifting self-mixing interferometry
Tao, Yufeng; Wang, Ming; Xia, Wei
2017-03-01
A carrier separating method associated with noise-elimination had been introduced into a sinusoidal phase-shifting self-mixing interferometer. The conventional sinusoidal phase shifting self-mixing interferometry was developed into a more competitive instrument with high computing efficiency and nanometer accuracy of λ / 100 in dynamical vibration measurement. The high slew rate electro-optic modulator induced a sinusoidal phase carrier with ultralow insertion loss in this paper. In order to extract phase-shift quickly and precisely, this paper employed the carrier-separating to directly generate quadrature signals without complicated frequency domain transforms. Moreover, most noises were evaluated and suppressed by a noise-elimination technology synthesizing empirical mode decomposition with wavelet transform. The overall laser system was described and inherent advantages such as high computational efficiency and decreased nonlinear errors of the established system were demonstrated. The experiment implemented on a high precision PZT (positioning accuracy was better than 1 nm) and compared with laser Doppler velocity meter. The good agreement of two instruments shown that the short-term resolution had improved from 10 nm to 1.5 nm in dynamic vibration measurement with reduced time expense. This was useful in precision measurement to improve the SMI with same sampling rate. The proposed signal processing was performed in pure time-domain requiring no preprocessing electronic circuits.
Sokkar, T. Z. N.; El-Farahaty, K. A.; El-Bakary, M. A.; Omar, E. Z.; Hamza, A. A.
2017-09-01
In this article, the features of the phase shifting interferometric technique were utilized to investigate the effect of the presence of crazes in both outer and inner layers on optical birefringence and molecular orientation of polypropylene fibres. The Pluta polarizing interference microscope was used as a phase shifting technique. This method includes adding a stepper motor with a control unit to the micrometer screw of the Pluta microscope. This optical system was calibrated to be used as a phase shifting interferometric technique. The advantage of this technique is that it can detect the crazes in both inner and outer layers of the sample under test. Via this method, the relation between the presence of the crazes (in both inner and outer layers) and the optical molecular orientation of polypropylene (PP) fibres was demonstrated. To clarify the role of this method, the spatial carrier frequency technique was used to show the effect of the presence of the crazes only in the outer layers on the phase distribution values and hence the structural properties of PP fibres.
Open-loop phase shifting for fast acquisition of interferograms in low light levels.
McCracken, Tyler M; Jurgenson, Colby A; Haniff, Chris A; Buscher, David F; Young, John S; Creech-Eakman, Michelle
2013-07-10
Phase shifting interferometry relies on sets of interferograms taken at multiple known phase offsets to deduce the instantaneous phase of a quasi-static fringe pattern. The traditional method for introducing these phase shifts has been either to step a mirror, and measure the fringe pattern at each step, or to scan a mirror, integrating the fringe pattern for discrete time intervals while the fringes "move" on the detector. A stepping mirror eliminates this fringe smear but has typically required a closed-loop controller to ensure that the optical path introduced is accurately known. Furthermore, implementing rapid stepping of a moderately sized optic can prove difficult if the fringe phase needs to be measured on a short time scale. We report results demonstrating very fast (>100 Hz) and precise phase shifting using a piezomodulated mirror operated in open-loop without any position feedback. Our method exploits the use of a synthetic driving waveform that is optimized to match the complex frequency response of the modulator and its supported optic. For phase measurements in the near-infrared at 2.15 μm, and with a time between steps as small as 0.2 ms, we report errors below λ/100 in the desired position of our optic, i.e., an effective optical path difference error of ~λ/55. For applications in near-infrared stellar interferometry, this implies an enhancement in the fringe-tracking sensitivity of roughly 20% (in the photon-limited regime) over that which is conventionally realized using a swept mirror.
Accurate submicron edge detection using the phase change of a nano-scale shifting laser spot
Hai, Hoang Hong; Chen, Liang-Chia; Nguyen, Duc Trung; Lin, Shyh-Tsong; Yeh, Sheng Lih; Yao, Ying
2017-07-01
Accurate edge detection with lateral super-resolution has been a critical issue in optical measurement because of the barrier imposed by the optical diffraction limit. In this study, a diffraction model that applies scalar diffraction theory of Fresnel-Kirchhoff is developed to simulate phase variance and distribution along edge location. Edge position is detected based on the phase variation that occurs on the edge with a surface step-height jump. To detect accurate edge positioning beyond the optical diffraction limit, a nanopositioning stage is used to scan the super steep edge of a single-edge and multi-edges submicron grating with nano-scale, and its phase distribution is captured. Model simulation is performed to confirm the phase-shifting phenomenon of the edge. A phase-shifting detection algorithm is developed to spatially detect the edge when a finite step scanning with a pitch of several tenth nanometers is used. A 180 nm deviation can occur during detection when the step height of the detecting edge varies, or the detecting laser spot covers more than one edge. Preliminary experimental results show that for the edge detection of the submicron line width of the grating, the standard deviation of the optical phase difference detection measurement is 38 nm. This technique provides a feasible means to achieve optical super-resolution on micro-grating measurement.
Dai, Xiangjun; Shao, Xinxing; Li, Lijun; Liu, Cong; Dai, Meiling; Yun, Hai; Yang, Fujun
2017-07-20
Three-dimensional shapes of objects were evaluated with modified phase-shift lateral shearing interferometry illumination and radial basis function. A simple optical system was developed to create the fringe pattern based on the Murty interferometer. The phase shift was generated only by moving a plane-parallel plate along an in-plane parallel direction. A novel moving radial basis function method was presented to improve the quality of fringe patterns. And the proper calculation window size was given based on numerical simulation. Three-dimensional shapes of two kinds of objects were determined to verify the feasibility and effectiveness of the proposed method, and the reconstructed height distributions were in good accordance with the referenced data.
Sheeran, Paul S; Yoo, Kimoon; Williams, Ross; Yin, Melissa; Foster, F Stuart; Burns, Peter N
2017-02-01
Phase-shift perfluorocarbon droplets have been investigated for over 20 years as pre-clinical ultrasound contrast agents with distinctive advantages in imaging and therapy. A number of formulation strategies exist, each with inherent advantages and limitations. In this note, we demonstrate a unique opportunity: that phase-shift droplets can be generated directly from commercially available microbubbles. This may facilitate pre-clinical and translational development by reducing the in-house synthesis expertise and resources required to generate high concentration droplet emulsions. Proof-of-principle in vitro and in vivo is given using droplets created from Definity and MicroMarker. The results demonstrate the role of perfluorocarbon choice in the trade-off between thermal stability and vaporization threshold, and suggest that commercial microbubbles with decafluorobutane cores may be ideal for this approach. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Sheeran, Paul S; Matsuura, Naomi; Borden, Mark A; Williams, Ross; Matsunaga, Terry O; Burns, Peter N; Dayton, Paul A
2017-01-01
Continued advances in the field of ultrasound and ultrasound contrast agents have created new approaches to imaging and medical intervention. Phase-shift perfluorocarbon droplets, which can be vaporized by ultrasound energy to transition from the liquid to the vapor state, are one of the most highly researched alternatives to clinical ultrasound contrast agents (i.e., microbubbles). In this paper, part of a special issue on methods in biomedical ultrasonics, we survey current techniques to prepare ultrasound-activated nanoscale phase-shift perfluorocarbon droplets, including sonication, extrusion, homogenization, microfluidics, and microbubble condensation. We provide example protocols and discuss advantages and limitations of each approach. Finally, we discuss best practice in characterization of this class of contrast agents with respect to size distribution and ultrasound activation.
Wu, Qi; Okabe, Yoji
2012-08-15
An ultrasonic sensor based on two cascaded phase-shifted fiber Bragg gratings (PS-FBGs) is proposed and demonstrated. In place of an external cavity laser, a broadband amplified spontaneous emission light source is used to demonstrate multiplexing ability suitable for sensor networks. The system has a high sensitivity to ultrasonic waves generated by a PZT actuator placed 7.5 cm away from the PS-FBG, because of the steep slope in the center of the PS-FBG spectrum. A second advantage of the phase shift is to reduce the effective sensor length, leading to the achievement of broadband characteristics. A pencil lead break test was performed and all results are compared to a traditional PZT sensor.
Measuring the thickness of soap bubbles with phase-shift interferometry.
Vannoni, Maurizio; Sordini, Andrea; Gabrieli, Riccardo; Melozzi, Mauro; Molesini, Giuseppe
2013-08-26
A model for the optical path difference introduced by a soap bubble in transmission is described. The model is then used with interferometric data to solve for the fringe order, and to define a procedure to extract the global film thickness in presence of turbulence flows occurring during the drainage process due to gravity. Experimental results on soap bubbles examined in single-pass phase-shift interferometry are presented.
Investigation of carbon dioxide phase shift possibility under extreme Antarctic winter conditions
Vashchenko, V M
2014-01-01
The Antarctic winter atmosphere minimal temperature and pressure series reveal that $CO_2$ phase shift (deposition) is possible in some extreme cases, even leading to possible $CO_2$ snow phenomenon at Vostok Antarctic station and in other near South Pole regions. A hypothesis has been formulated that stable $CO_2$ snow cover might have formed in Earth past which may influence interpretation of glacial chronology records. This effect may also manifest in other minor gases. Its global climate role is discussed.
Moiré phase-shifted fiber Bragg gratings in polymer optical fibers
DEFF Research Database (Denmark)
Min, Rui; Marques, Carlos; Bang, Ole
2018-01-01
We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...... periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured....
Spatial-phase-shift imaging interferometry using a spectrally modulated white light source.
Epshtein, Shlomi; Harris, Alon; Yaacobovitz, Igor; Locketz, Garrett; Yitzhaky, Yitzhak; Arieli, Yoel
2014-12-15
An extension of the white light spatial-phase-shift (WLSPS) for object surface measurements is described. Using WLSPS, surface measurements can be obtained from any real object image without the need of a reference beam, thus achieving inherent vibration cancellation. The surface topography is obtained by acquiring multiple images of an object illuminated by a spectrally modulated white light source and using an appropriate algorithm. The modulation of the light source obviates the need for the continuous phase delay to obtain the interferograms.
Rigorous intensity and phase-shift manipulation in optical frequency conversion.
Yang, Bo; Yue, Yang-Yang; Lu, Rong-Er; Hong, Xu-Hao; Zhang, Chao; Qin, Yi-Qiang; Zhu, Yong-Yuan
2016-06-07
A simple method is employed to investigate the nonlinear frequency conversion in optical superlattices (OSL) with pump depletion. Four rigorous phase-matching conditions for different purposes are obtained directly from the nonlinear coupled equations, and the resulting OSL domain structures are generally aperiodic rather than periodic. With this method, not only the intensity but also the phase-shift of the harmonic waves can be manipulated at will. The second-harmonic generation of Gaussian beam is further investigated. This work may provide a guidance for the practical applications of designing nonlinear optical devices with high conversion efficiency.
Femtosecond laser inscription of phase-shifted grating by post-processing
Zhou, Xian; Dai, Yutang; Liu, Fufei; Karanja, Joseph Muna; Zou, Meng
2017-04-01
The method of fabricating phase-shifted fiber Bragg grating (PSFBG) that does not need a phase mask by femtosecond laser (fs) post-processing is demonstrated. A central region of standard single mode fiber Bragg grating (FBG) is irradiated by fs laser. A rotating jig is designed to hold and rotate the fiber when the fiber is irradiated by laser. The bandwidth of transmission peak of PSFBG and the transmission loss is growing with increasing of laser energy. PSFBG produced by this method is simple, fast and reproducible.
DEFF Research Database (Denmark)
Ortega, Beatriz; Min, Rui; Sáez-Rodriguez, David
2017-01-01
In this contribution we report on the fabrication of novel bandpass transmission filters based on PS-FBGs in microstructured polymer fibers at telecom wavelengths. The phase mask technique is employed to fabricate several superimposed gratings with slight different periods in order to form Moir......Ã© structures with a single or various Ï€ phase shifts along the device. Simulations and experimental results are included in order to demonstrate very narrowband transmission filters. Experimental characterization under strain and temperature variations is provided in a non-annealed fiber and time stability...... of the fabricated devices has been also measured under different pre-strain conditions....
Control phase shift of spin-wave by spin-polarized current and its application in logic gates
Energy Technology Data Exchange (ETDEWEB)
Chen, Xiangxu; Wang, Qi; Liao, Yulong; Tang, Xiaoli; Zhang, Huaiwu; Zhong, Zhiyong, E-mail: zzy@uestc.edu.cn
2015-11-15
We proposed a new ways to control the phase shift of propagating spin waves by applying a local spin-polarized current on ferromagnetic stripe. Micromagnetic simulation showed that a phase shift of about π can be obtained by designing appropriate width and number of pinned magnetic layers. The ways can be adopted in a Mach-Zehnder-type interferometer structure to fulfill logic NOT gates based on spin waves. - Highlights: • Spin-wave phase shift can be controlled by a local spin-polarized current. • Spin-wave phase shift increased with the increasing of current density. • Spin-wave phase shift can reach about 0.3π at a particular current density. • The ways can be used in a Mach-Zehnder-type interferometer to fulfill logic gates.
High-speed 3D imaging using two-wavelength parallel-phase-shift interferometry.
Safrani, Avner; Abdulhalim, Ibrahim
2015-10-15
High-speed three dimensional imaging based on two-wavelength parallel-phase-shift interferometry is presented. The technique is demonstrated using a high-resolution polarization-based Linnik interferometer operating with three high-speed phase-masked CCD cameras and two quasi-monochromatic modulated light sources. The two light sources allow for phase unwrapping the single source wrapped phase so that relatively high step profiles having heights as large as 3.7 μm can be imaged in video rate with ±2 nm accuracy and repeatability. The technique is validated using a certified very large scale integration (VLSI) step standard followed by a demonstration from the semiconductor industry showing an integrated chip with 2.75 μm height copper micro pillars at different packing densities.
Gobert, O.; Fedorov, N.; Tcherbakoff, O.; Hergott, J. F.; Perdrix, M.; Lepetit, F.; Guillaumet, D.; Comte, M.
2012-02-01
We investigate and analyze in detail an approach to measure Carrier Envelope Phase shifts by using spectral interferometry. The method which uses a broadband laser source is applied to the characterization of an Electro Optic Carrier Envelope Phase shifter and leads to quick and accurate measurements on a large frequency domain. The shifter is inserted in one arm of a Mach-Zehnder interferometer illuminated by a wide frequency spectrum coherent source. By carefully analyzing the observed fringes, we successfully derived, with a very good accuracy, the main useful parameters of the CEP shifter on the whole investigated wavelength spectrum. The laser source which delivers pulses with a Gaussian spatial distribution and a nearly flat spatial phase does not need to be CEP stabilized and no control of the spectral phase of the pulses is necessary. This has specific advantages compared to other methods.
Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces
Alidoust, Mohammad; Hamzehpour, Hossein
2017-10-01
Employing a Keldysh-Eilenberger technique, we theoretically study the generation of a spontaneous supercurrent and the appearance of the φ0 phase shift parallel to uniformly in-plane magnetized superconducting interfaces made of the surface states of a three-dimensional topological insulator. We consider two weakly coupled uniformly magnetized superconducting surfaces where a macroscopic phase difference between the s -wave superconductors can be controlled externally. We find that, depending on the magnetization strength and orientation on each side, a spontaneous supercurrent due to the φ0 states flows parallel to the interface at the nanojunction location. Our calculations demonstrate that nonsinusoidal phase relations of current components with opposite directions result in maximal spontaneous supercurrent at phase differences close to π . We also study the Andreev subgap channels at the interface and show that the spin-momentum locking phenomenon in the surface states can be uncovered through density of states studies. We finally discuss realistic experimental implications of our findings.
Round-robin differential quadrature phase-shift quantum key distribution
Zhou, Chun; Zhang, Ying-Ying; Bao, Wan-Su; Li, Hong-Wei; Wang, Yang; Jiang, Mu-Sheng
2017-02-01
Recently, a round-robin differential phase-shift (RRDPS) protocol was proposed [Nature 509, 475 (2014)], in which the amount of leakage is bounded without monitoring the signal disturbance. Introducing states of the phase-encoded Bennett-Brassard 1984 protocol (PE-BB84) to the RRDPS, this paper presents another quantum key distribution protocol called round-robin differential quadrature phase-shift (RRDQPS) quantum key distribution. Regarding a train of many pulses as a single packet, the sender modulates the phase of each pulse by one of {0, π/2, π, 3π/2}, then the receiver measures each packet with a Mach-Zehnder interferometer having a phase basis of 0 or π/2. The RRDQPS protocol can be implemented with essential similar hardware to the PE-BB84, so it has great compatibility with the current quantum system. Here we analyze the security of the RRDQPS protocol against the intercept-resend attack and the beam-splitting attack. Results show that the proposed protocol inherits the advantages arising from the simplicity of the RRDPS protocol and is more robust against these attacks than the original protocol. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505261 and 11304397) and the National Basic Research Program of China (Grant No. 2013CB338002)
The exergy of a phase shift: Ecosystem functioning loss in seagrass meadows of the Mediterranean Sea
Montefalcone, Monica; Vassallo, Paolo; Gatti, Giulia; Parravicini, Valeriano; Paoli, Chiara; Morri, Carla; Bianchi, Carlo Nike
2015-04-01
Sustained functioning of ecosystems is predicted to depend upon the maintenance of their biodiversity, structure and integrity. The large consensus achieved in this regard, however, faces to the objective difficulty of finding appropriate metrics to measure ecosystem functioning. Here, we aim at evaluating functional consequence of the phase shift occurring in meadows of the Mediterranean seagrass Posidonia oceanica, a priority habitat that is undergoing regression in many coastal areas due to multiple human pressures. Structural degradation of the P. oceanica ecosystem, consequent to increasing coastal exploitation and climate change, may result in the progressive replacement of this seagrass by opportunistic macrophytes, either native or alien. Reviewing published information and our personal records, we measured changes in biological habitat provisioning, species richness and biomass associated to each of the alternative states characterizing the phase shift. Then, ecosystem functioning was assessed by computing the exergy associated to each state, exergy being a state variable that measures the ecosystem capacity to produce work. Phase shift was consistently shown to imply loss in habitat provision, species richness, and biomass; structural and compositional loss was parallelled by a reduction of exergy content, thus providing for the first time an objective and integrative measure of the loss of ecosystem functioning following the degradation of healthy seagrass meadows.
Investigating Structure and Dynamics of Proteins in Amorphous Phases Using Neutron Scattering
Directory of Open Access Journals (Sweden)
Maria Monica Castellanos
2017-01-01
Full Text Available In order to increase shelf life and minimize aggregation during storage, many biotherapeutic drugs are formulated and stored as either frozen solutions or lyophilized powders. However, characterizing amorphous solids can be challenging with the commonly available set of biophysical measurements used for proteins in liquid solutions. Therefore, some questions remain regarding the structure of the active pharmaceutical ingredient during freezing and drying of the drug product and the molecular role of excipients. Neutron scattering is a powerful technique to study structure and dynamics of a variety of systems in both solid and liquid phases. Moreover, neutron scattering experiments can generally be correlated with theory and molecular simulations to analyze experimental data. In this article, we focus on the use of neutron techniques to address problems of biotechnological interest. We describe the use of small-angle neutron scattering to study the solution structure of biological molecules and the packing arrangement in amorphous phases, that is, frozen glasses and freeze-dried protein powders. In addition, we discuss the use of neutron spectroscopy to measure the dynamics of glassy systems at different time and length scales. Overall, we expect that the present article will guide and prompt the use of neutron scattering to provide unique insights on many of the outstanding questions in biotechnology.
Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.
Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A
2016-02-26
Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.
Toda, Sogo; Kato, Yuji; Kudo, Nobuki; Shimizu, Koichi
2017-04-01
For transillumination imaging of an animal body, we have attempted to suppress the scattering effect in a turbid medium. It is possible to restore the optical image before scattering using phase-conjugate light. We examined the effect of intensity information as well as the phase information for the restoration of the original light distribution. In an experimental analysis using animal tissue, the contributions of the phase- and the intensity-information to the image restoration through turbid medium were demonstrated.
Cantrell, Andrew Glenn
We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves
Balancing the electric mode by shifting with time of one-phase electric receiver load graphs
Directory of Open Access Journals (Sweden)
Леонід Борисович Терешкевич
2017-07-01
Full Text Available A method for balancing the electrical mode by shifting the load diagrams of single-phase electric receivers in time has been developed, that does not require additional capital investments for its implementation, does not affect the technological process and, in certain cases, does not reduce the products output. The method is believed, on the basis of the information on the load curves of single-phase electric receivers connected to one node of the electrical network, to evaluate the mode asymmetry in the supplying three-wire line with all possible relative temporal shifts of the graphs. The criterion for choosing the optimal variant is additional losses of active energy in the supply line due to the asymmetry of the mode. To do this, a set of negative sequence current matrices generated by electric receivers is formed, with the number of rows equal to the number of stages of the load curve, and the number of columns is the tripled number of single-phase power receivers. The total number of matrices is equal to the number of variants of shifts of graphs relative to any of the steps of one of them. The realized connection of electric receivers to the network is described in Boolean variables and is represented by a vector with the number of elements equal to three times the number of electric receivers. To estimate the effect of implementing any variant of the shifts, one can multiply the corresponding matrix of negative sequence currents by the connection vector, and to process the obtained result then. All work on the synthesis of matrices, calculations and selection of the optimal variant is algorithmized, which makes it possible to use information technologies for decision making. The effectiveness of the developed method is illustrated by a numerical example
Solookinejad, Gh; Jabbari, M.; Panahi, M.; Ahmadi Sangachin, E.
2017-11-01
In this paper, we discuss the phase management of Goos–Hänchen (GH) shifts of a probe light through a cavity with a single-layer graphene nanostructure under a strong magnetic field. By using the quantum mechanical density matrix formalism we study the GH shifts of reflected and transmitted light beams. It is realized that negative or positive GH shifts can be achieved simultaneously by tuning some controllable parameters such as relative phase and the Rabi frequency of the applied fields. Moreover, the thickness effect of the cavity structure is considered as an effective parameter for adjusting the GH shifts of reflected and transmitted light beams. We find that by choosing suitable parameters, a maximum negative shift of 4.5 mm and positive shift of 5.4 mm are possible for GH shifts in reflected and transmitted light. Our proposed model may be useful for developing all-optical devices in the infrared region.
Yang, Jiamiao; Shen, Yuecheng; Liu, Yan; Hemphill, Ashton S.; Wang, Lihong V.
2017-11-01
Optical scattering prevents light from being focused through thick biological tissue at depths greater than ˜1 mm. To break this optical diffusion limit, digital optical phase conjugation (DOPC) based wavefront shaping techniques are being actively developed. Previous DOPC systems employed spatial light modulators that modulated either the phase or the amplitude of the conjugate light field. Here, we achieve optical focusing through scattering media by using polarization modulation based generalized DOPC. First, we describe an algorithm to extract the polarization map from the measured scattered field. Then, we validate the algorithm through numerical simulations and find that the focusing contrast achieved by polarization modulation is similar to that achieved by phase modulation. Finally, we build a system using an inexpensive twisted nematic liquid crystal based spatial light modulator (SLM) and experimentally demonstrate light focusing through 3-mm thick chicken breast tissue. Since the polarization modulation based SLMs are widely used in displays and are having more and more pixel counts with the prevalence of 4 K displays, these SLMs are inexpensive and valuable devices for wavefront shaping.
Rectangular QPSK for generation of optical eight-ary phase-shift keying.
Lu, Guo-Wei; Sakamoto, Takahide; Kawanishi, Tetsuya
2011-09-12
Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.
Phase-shifting holography using Bragg and non-Bragg orders in photorefractive lithium niobate
Abeywickrema, Ujitha; Banerjee, Partha
2014-09-01
Holographic interferometry is an effective and rich method for measuring very small (order of a wavelength) deformations of an object and is widely used for non-destructive testing. In this work, the use of photorefractive materials for implementing real time phase shifting holographic interferometry is examined in detail. Bragg and non-Bragg orders generated during two- and multi-beam coupling in a photorefractive material can be used to retrieve the deformation of the object, or the phase information of the object. In previous work, it has been shown that object deformation can be determined from monitoring Bragg and non-Bragg orders. Preliminary experiments for determining the depth profile of an object have been reported, along with approximate analytic solutions for the Bragg and non-Bragg orders for the case of interacting plane waves. In this work, the exact solutions of Bragg and non-Bragg orders are found from numerically solving the interaction equations in a photorefractive material. It is shown that if the grating written in the material using two waves is read out by a reference and the object, the resulting Bragg and non-Bragg orders contain the information of the object phase, and is dependent on material parameters and the writing and reading beam intensities. Similarities and differences between this dynamic holographic technique and the traditional phase shifting digital holography are extensively discussed.
Vehicular motion in counter traffic flow through a series of signals controlled by a phase shift
Nagatani, Takashi; Tobita, Kazuhiro
2012-10-01
We study the dynamical behavior of counter traffic flow through a sequence of signals (traffic lights) controlled by a phase shift. There are two lanes for the counter traffic flow: the first lane is for east-bound vehicles and the second lane is for west-bound vehicles. The green-wave strategy is studied in the counter traffic flow where the phase shift of signals in the second lane has opposite sign to that in the first lane. A nonlinear dynamic model of the vehicular motion is presented by nonlinear maps at a low density. There is a distinct difference between the traffic flow in the first lane and that in the second lane. The counter traffic flow exhibits very complex behavior on varying the cycle time, the phase difference, and the split. Also, the fundamental diagram is derived by the use of the cellular automaton (CA) model. The dependence of east-bound and west-bound vehicles on cycle time, phase difference, and density is clarified.
A scheme for a single molecule phase-shift gate in a solid matrix.
Cui, Xiao-Dong; Zheng, Yujun
2015-06-07
We propose a feasible scheme to implement a phase-shift gate ((1 0) (0 eiγ)) based on a two-state single molecule in a solid matrix, where γ is a geometric phase controlled through a fast on-resonant laser field and a slow off-resonant radio-frequency field. In our scheme, a non-Hermitian quantum model is employed to characterize the single molecule in a solid matrix including the spontaneous decay effect. By the coupling between the radio-frequency field and the two-state permanent dipole difference resulting from the solid matrix, the spontaneous decay fatal to the preservation of geometric phase can be effectively suppressed for a considerably long waiting time.
Microbial and sponge loops modify fish production in phase-shifting coral reefs.
Silveira, Cynthia B; Silva-Lima, Arthur W; Francini-Filho, Ronaldo B; Marques, Jomar S M; Almeida, Marcelo G; Thompson, Cristiane C; Rezende, Carlos E; Paranhos, Rodolfo; Moura, Rodrigo L; Salomon, Paulo S; Thompson, Fabiano L
2015-10-01
Shifts from coral to algae dominance of corals reefs have been correlated to fish biomass loss and increased microbial metabolism. Here we investigated reef benthic and planktonic primary production, benthic dissolved organic carbon (DOC) release and bacterial growth efficiency in the Abrolhos Bank, South Atlantic. Benthic DOC release rates are higher while water column bacterial growth efficiency is lower at impacted reefs. A trophic model based on the benthic and planktonic primary production was able to predict the observed relative fish biomass in healthy reefs. In contrast, in impacted reefs, the observed omnivorous fish biomass is higher, while that of the herbivorous/coralivorous fish is lower than predicted by the primary production-based model. Incorporating recycling of benthic-derived carbon in the model through microbial and sponge loops explains the difference and predicts the relative fish biomass in both reef types. Increased benthic carbon release rates and bacterial carbon metabolism, but decreased bacterial growth efficiency could lead to carbon losses through respiration and account for the uncoupling of benthic and fish production in phase-shifting reefs. Carbon recycling by microbial and sponge loops seems to promote an increase of small-bodied fish productivity in phase-shifting coral reefs. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.
Stimulated Brillouin scattering continuous wave phase conjugation in step-index fiber optics.
Massey, Steven M; Spring, Justin B; Russell, Timothy H
2008-07-21
Continuous wave (CW) stimulated Brillouin scattering (SBS) phase conjugation in step-index optical fibers was studied experimentally and modeled as a function of fiber length. A phase conjugate fidelity over 80% was measured from SBS in a 40 m fiber using a pinhole technique. Fidelity decreases with fiber length, and a fiber with a numerical aperture (NA) of 0.06 was found to generate good phase conjugation fidelity over longer lengths than a fiber with 0.13 NA. Modeling and experiment support previous work showing the maximum interaction length which yields a high fidelity phase conjugate beam is inversely proportional to the fiber NA(2), but find that fidelity remains high over much longer fiber lengths than previous models calculated. Conditions for SBS beam cleanup in step-index fibers are discussed.
Takagi, Mutsumi; Tokunaga, Naochika
2015-08-01
Aiming to establish a method for the noninvasive discrimination of cancer cells from normal cells in adherent culture, we investigated to employ all phase shift data for all pixels inside a cell. The bird's-eye views of phase shifts of human prostate epithelial cells (PRECs) and human prostatic carcinoma epithelial cell (PC-3) lines acquired by phase-shifting laser microscopy showed tableland and cone shapes, respectively, while treatment of PRECs with cytochalasin D resulted in the cone shape. So, the profile of phase shift in both sections towards the x- and y-axes of the views through the peaks of the phase shifts in PRECs and PC-3 cells were trapezoid-like and triangle-like, respectively. Typical profiles of phase shifts in a section in PRECs or PC-3 cells were calculated by averaging from 10 cells and smoothing. Cancer index is defined as the deduction of sums of the squared difference between a real cell and the typical profiles for a PREC and a PC-3 cell. The cancer indices for PC-3 and hepatocellular carcinoma cell lines were positive, while those for PRECs and human normal cryopreserved hepatocytes were negative. Cancer indices along the major axis of fibroblast-like cells of normal mesenchymal stem cells and the osteosarcoma cell line were negative and positive, respectively. Consequently, several cancer cells could be noninvasively discriminated from normal cells by calculating the cancer index employing phase shift for all pixels inside the cells.
Sato, T.; Satoh, T.; Kasaba, Y.
2010-12-01
The three distinct cloud layers were predicted by an equilibrium cloud condensation model (ECCM) of Jupiter. An ammonia ice cloud (NH3), an ammonia hydrosulfide cloud (NH4SH), and a water ice (H2O) cloud would be based at altitudes corresponding to pressures of about 0.7, 2.2 and 6 bars, respectively. However, there are significant gaps in our knowledge of the vertical cloud structure, despite the continuing effort by numerous ground-based, space-based, and in-situ observations and theory. Methane (CH4) is considered that its altitude distribution is globally uniform because it does not condense in Jovian atmosphere. Therefore, it is possible to derive the vertical cloud structure and the optical properties of clouds (i.e., optical thickness and single scattering albedo) by observing reflected sunlight in CH4 bands (727, 890 nm) and continuum in visible to near-infrared spectral ranges. Since we need to consider multiple scattering by clouds, it is essential to know scattering properties (e.g., scattering phase function) of clouds for determination of vertical cloud structure. However, we cannot derive those from ground-based and Earth-orbit observations because of the limitation of solar phase angle as viewed from the Earth. Then, most previous studies have used the scattering phase function deduced from the Pioneer 10/IPP data (blue: 440 nm, red: 640nm) [Tomasko et al., 1978]. There are two shortcomings in the Pioneer scattering phase function. One is that we have to use this scattering phase function at red as a substitute for analyses of imaging photometry using CH4 bands (center: 727 and 890 nm), although clouds should have wavelength dependency. The other is that the red pass band of IPP was so broad (595-720 nm) that this scattering phase function in red just show wavelength-averaged scattering properties of clouds. To provide a new reference scattering phase function with wavelength dependency, we have analyzed the Cassini/ISS data in BL1 (451 nm), CB1 (619
Focusing light inside dynamic scattering media with millisecond digital optical phase conjugation.
Liu, Yan; Ma, Cheng; Shen, Yuecheng; Shi, Junhui; Wang, Lihong V
2017-02-01
Wavefront shaping based on digital optical phase conjugation (DOPC) focuses light through or inside scattering media, but the low speed of DOPC prevents it from being applied to thick, living biological tissue. Although a fast DOPC approach was recently developed, the reported single-shot wavefront measurement method does not work when the goal is to focus light inside, instead of through, highly scattering media. Here, using a ferroelectric liquid crystal based spatial light modulator, we develop a simpler but faster DOPC system that focuses light not only through, but also inside scattering media. By controlling 2.6 × 105 optical degrees of freedom, our system focused light through 3 mm thick moving chicken tissue, with a system latency of 3.0 ms. Using ultrasound-guided DOPC, along with a binary wavefront measurement method, our system focused light inside a scattering medium comprising moving tissue with a latency of 6.0 ms, which is one to two orders of magnitude shorter than those of previous digital wavefront shaping systems. Since the demonstrated speed approaches tissue decorrelation rates, this work is an important step toward in vivo deep-tissue non-invasive optical imaging, manipulation, and therapy.
Equivalence principle for quantum systems: dephasing and phase shift of free-falling particles
Anastopoulos, C.; Hu, B. L.
2018-02-01
We ask the question of how the (weak) equivalence principle established in classical gravitational physics should be reformulated and interpreted for massive quantum objects that may also have internal degrees of freedom (dof). This inquiry is necessary because even elementary concepts like a classical trajectory are not well defined in quantum physics—trajectories originating from quantum histories become viable entities only under stringent decoherence conditions. From this investigation we posit two logically and operationally distinct statements of the equivalence principle for quantum systems. Version A: the probability distribution of position for a free-falling particle is the same as the probability distribution of a free particle, modulo a mass-independent shift of its mean. Version B: any two particles with the same velocity wave-function behave identically in free fall, irrespective of their masses. Both statements apply to all quantum states, including those without a classical correspondence, and also for composite particles with quantum internal dof. We also investigate the consequences of the interaction between internal and external dof induced by free fall. For a class of initial states, we find dephasing occurs for the translational dof, namely, the suppression of the off-diagonal terms of the density matrix, in the position basis. We also find a gravitational phase shift in the reduced density matrix of the internal dof that does not depend on the particle’s mass. For classical states, the phase shift has a natural classical interpretation in terms of gravitational red-shift and special relativistic time-dilation.
Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro
2015-06-15
Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.
Directory of Open Access Journals (Sweden)
A. V. Volkov
2015-07-01
Full Text Available Subject of Research. Important feature of homodyne demodulation method based on the arctangent function approach is the phase shift between the reference oscillator signal and the interference signal. This phenomenon is caused by propagation delays of impulses in the optical interferometric sensor scheme and the analog low-pass filter in front of the phase modulator which produces the reference oscillator signal phase delay. There is multiplying of the reference oscillator signal and the interference signal in this homodyne demodulation scheme during its processing, and the phase shift between these signals leads to a distortion of the output signal. This paper deals with the findings of the phase shift influence of the reference oscillator signal by the output signal of the demodulation scheme at various parameters of the interference signal. Estimation of required accuracy is given of the phase shift compensation for the specified level distortion of the output signal. Method. Mathematical model is proposed in MATLAB. In this model, interference signal with changing parameters by a set of rules is passed through the considered demodulation scheme. This gives the possibility to obtain the dependences of the output signal amplitude from the reference oscillator signal phase shift, the operating point of the interferometer, the depth of phase modulation and amplitude of the measured phase signal. Results obtained during the simulation showed the need to compensate the reference oscillator signal phase shift. To assess this shift in the current homodyne demodulation scheme the original method of its determination has been proposed. The method is based on the transmission of the interference signal and the oscillator signal via one and the same band-pass filter that separates the phase modulation carrier frequency. According to the phase delay between the receiving signals, the value of the reference oscillator signal phase shift can be judged on
Two-level image authentication by two-step phase-shifting interferometry and compressive sensing
Zhang, Xue; Meng, Xiangfeng; Yin, Yongkai; Yang, Xiulun; Wang, Yurong; Li, Xianye; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi
2018-01-01
A two-level image authentication method is proposed; the method is based on two-step phase-shifting interferometry, double random phase encoding, and compressive sensing (CS) theory, by which the certification image can be encoded into two interferograms. Through discrete wavelet transform (DWT), sparseness processing, Arnold transform, and data compression, two compressed signals can be generated and delivered to two different participants of the authentication system. Only the participant who possesses the first compressed signal attempts to pass the low-level authentication. The application of Orthogonal Match Pursuit CS algorithm reconstruction, inverse Arnold transform, inverse DWT, two-step phase-shifting wavefront reconstruction, and inverse Fresnel transform can result in the output of a remarkable peak in the central location of the nonlinear correlation coefficient distributions of the recovered image and the standard certification image. Then, the other participant, who possesses the second compressed signal, is authorized to carry out the high-level authentication. Therefore, both compressed signals are collected to reconstruct the original meaningful certification image with a high correlation coefficient. Theoretical analysis and numerical simulations verify the feasibility of the proposed method.
Simultaneous dual directional strain measurement using spatial phase-shift digital shearography
Wang, Yonghong; Gao, Xinya; Xie, Xin; Wu, Sijing; Liu, Yingxue; Yang, Lianxiang
2016-12-01
This paper presents a Dual Directional Sheared Spatial Phase-Shift Digital Shearography (DDS-SPS-DS) system for simultaneous measurement of strains/displacement derivative in two directions. Two Michelson Interferometers are used as the shearing device to create two shearograms, one in the x-shearing direction and one in the y-shearing direction, which are recorded by a single CCD camera. Two lasers with different wavelengths are used for illumination, and corresponding band pass filters are applied in front of each Michelson Interferometer to avoid cross-interference between the two shearing direction channels. Two perpendicular shearing directions in the two measurement channels introduce two different spatial frequency carriers whose spectrums are orientated in different directions after Fourier Transform. Phase maps of the recorded two shearograms can be obtained by applying a windowed inverse Fourier transform, which enables simultaneous measurement of dual directional strains/displacement derivatives. The new system is well suited for nondestructive testing and strain measurement with a continuous or dynamic load. The capability of the dual directional spatial phase-shift digital shearography system is described by theoretical discussions as well as experiments.
Xie, Xin; Yang, Lianxiang; Chen, Xu; Xu, Nan; Wang, Yonghong
2013-10-01
High accuracy full field three dimensional (3D) deformation measurements have always been an essential problem for the manufacturing, instrument, and aerospace industry. 3D deformations, which can be translated further into 3D strain and stress, are the key parameter for design, manufacturing and quality control. Due to the fast development of the manufacturing industry, especially in the automobile and airspace industry, rapid design and optimization concepts have already widely accepted. These concepts all require the support of rapid, high sensitive and accuracy 3D deformation measurement. Advanced optical methods are gaining widely acceptance for deformation and stain measurement by industry due to the advantages of non-contact, full-field and high measurement sensitivity. Of these methods, Electronic Speckle Pattern Interferometry (ESPI) is the most sensitive and accurate method for 3D deformation measurement in micro and sub micro-level. ESPI measures deformation by evaluating the phase difference of two recorded speckle interferograms under different loading conditions. Combined with a phase shift technique, ESPI systems can measure the 3D deformation with dozens of nanometer level sensitivity. Cataloged by phase calculation methods, ESPI systems can be divided into temporal phase shift ESPI systems and spatial phase shift ESPI system. This article provides a review and a comparison of temporal and spatial phase shift speckle pattern interferometry for 3D deformation measurement. After an overview of the fundamentals of ESPI theory, temporal phase-shift and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI which is suited well for static measurement and by the spatial phase-shift ESPI which is particularly useful for dynamic measurement will be discussed in detail. Basic theory, brief derivation and different optical layouts for the two systems will be presented. The potentials and limitations of the both ESPI
Investigation of snow single scattering properties based on first order Legendre phase function
Eppanapelli, Lavan Kumar; Casselgren, Johan; Wåhlin, Johan; Sjödahl, Mikael
2017-04-01
Angularly resolved bidirectional reflectance measurements were modelled by approximating a first order Legendre expanded phase function to retrieve single scattering properties of snow. The measurements from 10 different snow types with known density and specific surface area (SSA) were investigated. A near infrared (NIR) spectrometer was used to measure reflected light above the snow surface over the hemisphere in the wavelength region of 900-1650 nm. A solver based on discrete ordinate radiative transfer (DISORT) model was used to retrieve the estimated Legendre coefficients of the phase function and a correlation between the coefficients and physical properties of different snow types is investigated. Results of this study suggest that the first two coefficients of the first order Legendre phase function provide sufficient information about the physical properties of snow where the latter captures the anisotropic behaviour of snow and the former provides a relative estimate of the single scattering albedo of snow. The coefficients of the first order phase function were compared with the experimental data and observed that both the coefficients are in good agreement with the experimental data. These findings suggest that our approach can be applied as a qualitative tool to investigate physical properties of snow and also to classify different snow types.
Guo, Hao; Wang, Ziming; Du, Quanyin; Li, Pan; Wang, Zhigang; Wang, Aimin
2017-01-01
Bacterial biofilms on the surface of prostheses are becoming a rising concern in managing prosthetic joint infections. The inherent resistant features of biofilms render traditional antimicrobial therapy unproductive and revision surgery outcomes uncertain. This situation has prompted the exploration of novel antimicrobial strategies. The synergy of ultrasound microbubbles and vancomycin has been proposed as an efficient alternative for biofilm eradication. The purpose of this study was to evaluate the anti-biofilm effect of stimulated phase-shift acoustic nanodroplets (NDs) combined with vancomycin. We fabricated lipid phase-shift NDs with a core of liquid perfluoropentane. A new phase change mode for NDs incorporating an initial unfocused low-intensity pulsed ultrasound for 5 minutes and a subsequent incubation at 37°C into a 24-hour duration was developed. Methicillin-resistant Staphylococcus aureus (MRSA) biofilms were incubated with vancomycin and NDs under the hybrid stimulation. Biofilm morphology following treatment was determined using confocal laser scanning microscopy and scanning electron microscopy. Resazurin assay was used to quantify bactericidal efficacy against MRSA biofilm bacteria. NDs treated sequentially with ultrasound and heating at 37°C achieved gradual and substantial ND vaporization and cavitation in a successive process. NDs after stimulation were capable of generating stronger destruction on biofilm structure which was best characterized by residual circular arc margins and more dead bacteria. Furthermore, NDs combined with vancomycin contributed to significantly decreasing the metabolic activity of bacteria in MRSA biofilms (PPhase-shift acoustic NDs could exert a significant bactericidal effect against MRSA biofilms through a new stimulation mode. Acoustic NDs present advantages over microbubbles for biofilm damage. This anti-biofilm strategy could be used either alone or as an enhancer of traditional antibiotics in the control of
Directory of Open Access Journals (Sweden)
Wencai Pan
Full Text Available Cerebral hemorrhage, a difficult issue in clinical practice, is often detected and studied with computed tomography (CT, magnetic resonance imaging (MRI, and positron emission tomography (PET. However, these expensive devices are not readily available in economically underdeveloped regions, and hence are unable to provide bedside and emergency on-site monitoring. The magnetic inductive phase shift (MIPS is an emerging technology that may become a new tool to detect cerebral hemorrhage and to serve as an inexpensive partial substitute to medical imaging. In order to study a wider band of cerebral hemorrhage MIPS and to provide more useful information for measuring cerebral hemorrhage, we established a cerebral hemorrhage magnetic induction phase shift spectroscopy (MIPSS detection system. Thirteen rabbits with five cerebral hemorrhage states were studied using a single coil-coil within a 1 MHz-200 MHz frequency range in linear sweep. A feature band (FB with the highest detection sensitivity and the greatest stability was selected for further analysis and processing. In addition, a maximum conductivity cerebrospinal fluid (CSF MRI was performed to verify and interpret the MIPSS result. The average phase shift change induced by a 3 ml injection of autologous blood under FB was -7.7503° ± 1.4204°, which was considerably larger than our previous work. Data analysis with a non-parametric statistical Friedman M test showed that in the FB, MIPSS could distinguish the five states of cerebral hemorrhage in rabbits, with a statistical significance of p<0.05. A B-F distribution profile was designed according to the MIPSS under FB that can provide instantaneous diagnostic information about the cerebral hemorrhage severity from a single set of measurements. The results illustrate that the MIPSS detection method is able to provide a new possibility for real-time monitoring and diagnosis of the severity of cerebral hemorrhage.
Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt
2008-01-01
We describe an improved method for coherence domain path length resolved measurements of multiply scattered photons in turbid media. An electro-optic phase modulator sinusoidally modulates the phase in the reference arm of a low coherence fiber optic Mach–Zehnder interferometer, at a high phase
Structural characterization of Pt/C multilayer phase-shift reflectors
Pradhan, P. C.; Bhartiya, S.; Nayak, M.; Lodha, G. S.
2017-05-01
A Pt/C multilayer based phase-shift reflector (MPR) with grating period ˜800 nm and multilayer period ˜4.8 nm with the number of layer pairs 10 was characterized by hard x-ray reflectivity (XRR), rocking scan and atomic force microscopy (AFM). XRR results show the Bragg peaks up to 5th orders indicate good quality of MPR. Well defined grating truncation rods (GTRs) are observed in the rocking scan performed along the grating dispersive direction. AFM image shows that the depth of the MPR is˜35 nm, which can be used to suppress the wavelength region centered at λ = ˜140 nm.
Application of charge-dissipation material in MEBES phase-shift mask fabrication
Tan, Zoilo C. H.; Sauer, Charles A.
1994-12-01
Several charge dissipation materials were evaluated for their ability to improve the overlay accuracy during phase shift mask (PSM) registered writing on a MEBES system. These included an organic conductive polymer and a number of thin inorganic films, which were applied above or below the resist on a coated mask. When used with the resists, all conductive materials evaluated were capable of providing adequate charge dissipation during registered writing. Overlay accuracy of mean + 3 sigma
p-type GaN grown by phase shift epitaxy
Zhong, M.; Roberts, J.; Kong, W.; Brown, A. S.; Steckl, A. J.
2014-01-01
Phase shift epitaxy (PSE) is a periodic growth scheme, which desynchronizes host material growth process from dopant incorporation, allowing independent optimization. p-type doping of GaN with Mg by PSE is accomplished with molecular beam epitaxy by periodic shutter action (in order to iterate between Ga- and N-rich surface conditions) and by adjusting time delays between dopant and Ga shutters. Optimum PSE growth was obtained by turning on the Mg flux in the N-rich condition. This suppresses Mg self-compensation at high Mg concentration and produces fairly high hole concentrations (2.4 × 1018 cm-3).
Measurement of Three-Dimensional Deformations by Phase-Shifting Digital Holographic Interferometry
Directory of Open Access Journals (Sweden)
Percival Almoro
2003-06-01
Full Text Available Out-of-plane deformations of a cantilever were measured using phase-shifting digital holographicinterferometry (PSDHI and the Fourier transform method (FTM. The cantilever was recorded in twodifferent states, and holograms were stored electronically with a charge-coupled device (CCD camera.When the holograms are superimposed and reconstructed jointly, a holographic interferogram results.The three-dimensional (3D surface deformations were successfully visualized by applying FTM toholographic interferogram analysis. The minimum surface displacement measured was 0.317 µm. Theprocessing time for the digital reconstruction and visualization of 3D deformation took about 1 minute.The technique was calibrated using Michelson interferometry setup.
Superfast multifrequency phase-shifting technique with optimal pulse width modulation.
Wang, Yajun; Zhang, Song
2011-03-14
The technique of generating sinusoidal fringe patterns by defocusing squared binary structured ones has numerous merits for high-speed three-dimensional (3D) shape measurement. However, it is challenging for this method to realize a multifrequency phase-shifting (MFPS) algorithm because it is difficult to simultaneously generate high-quality sinusoidal fringe patterns with different periods. This paper proposes to realize an MFPS algorithm utilizing an optimal pulse width modulation (OPWM) technique that can selectively eliminate high-order harmonics of squared binary patterns. We successfully develop a 556 Hz system utilizing a three-frequency algorithm for simultaneously measuring multiple objects.
Simultaneous all-optical AND and NOR gates for NRZ differential phase-shift-keying signals
DEFF Research Database (Denmark)
Xu, Jing; Zhang, X.; Dong, J.
2008-01-01
A scheme for realizing all-optical logic AND and NOR gates simultaneously for nonreturn-to-zero differential phase-shift-keying signals is proposed and demonstrated based on a delayed interferometer and two semiconductor optical amplifiers. Experimental demonstration at 20 Gb/s verifies the logic...... integrity of this scheme. The final results are derived in the ON–OFF keying format with clear open eyes and extinction ratios over 10 dB. The proposed scheme can be expanded to realize arbitrary logic gate....
Wang, Jia; Guo, Zhenyan; Song, Yang; Han, Jun
2018-01-01
To realize volume moiré tomography (VMT) for the real three-dimensional (3D) diagnosis of combustion fields, according to 3D filtered back projection (FBP) reconstruction algorithm, the radial derivatives of the projected phase should be measured firstly. In this paper, a simple spatial phase-shifting moiré deflectometry with double cross gratings is presented to measure the radial first-order derivative of the projected phase. Based on scalar diffraction theory, the explicit analytical intensity distributions of moiré patterns on different diffracted orders are derived, and the spatial shifting characteristics are analyzed. The results indicate that the first-order derivatives of the projected phase in two mutually perpendicular directions are involved in moiré patterns, which can be combined to compute the radial first-order derivative. And multiple spatial phase-shifted moiré patterns can be simultaneously obtained; the phase-shifted values are determined by the parameters of the system. A four-step phase-shifting algorithm is proposed for phase extraction, and its accuracy is proved by numerical simulations. Finally, the moiré deflectometry is used to measure the radial first-order derivative of projected phase of a propane flame with plane incident wave, and the 3D temperature distribution is reconstructed.
A theoretical study on phase-contrast mammography with Thomson-scattering x-ray sources
Energy Technology Data Exchange (ETDEWEB)
De Caro, Liberato; Giannini, Cinzia; Bellotti, Roberto; Tangaro, Sabina [Istituto di Cristallografia-Consiglio Nazionale delle Ricerche (IC-CNR), via Amendola 122/O, I-70125 Bari, Italy and Istituto Nazionale Fisica Nucleare, Sezione di Bari, via Amendola 173, 70126 Bari (Italy); Istituto Nazionale Fisica Nucleare, Sezione di Bari, via Amendola 173, 70126 Bari, Italy and Dipartimento Interateneo di Fisica-M. Merlin, Universita degli Studi di Bari, via Amendola 173, 70126 Bari (Italy); Istituto Nazionale Fisica Nucleare, Sezione di Bari, via Amendola 173, 70126 Bari (Italy)
2009-10-15
Purpose: The x-ray transmitted beam from any material/tissue depends on the complex refractive index (n=1-{delta}+i{beta}), where {delta} is responsible for the phase shift and {beta} is for the beam attenuation. Although for human tissues, the {delta} cross section is about 1000 times greater than the {beta} ones in the x-ray energy range from 10 to 150 keV, the gain in breast tumor visualization of phase-contrast mammography (PCM) with respect to absorption contact imaging (AI) is limited by the maximum dose that can be delivered to the patient. Moreover, in-line PC imaging (PCI) is the simplest experimental mode among all available x-ray PCI techniques since no optics are needed. The latter is a fundamental requirement in order to transfer the results of laboratory research into hospitals. Alternative to synchrotron radiation sources, the implementation of relativistic Thomson-scattering (TS) x-ray sources is particularly suitable for hospital use because of their high peak brightness within a relatively compact and affordable system. In this work, the possibility to realize PCM using a TS source in a hospital environment is studied, accounting for the effect of a finite deliverable dose on the PC visibility enhancement with respect to AI. Methods: The contrast-to-noise ratio of tumor-tissue lesions in PCM has been studied on the bases of a recent theoretical model, describing image contrast formation by means of both wave-optical theory and the mutual coherence formalism. The latter is used to describe the evolution, during wave propagation, of the coherence of the wave field emitted by a TS source. The contrast-to-noise ratio for both PCI and AI has been analyzed in terms of tumor size, beam energy, detector, and source distances, studying optimal conditions for performing PCM. Regarding other relevant factors which could influence ''tumor'' visibility, the authors have assumed simplified conditions such as a spherical shape description of
Moreno, Camilo; Alda, Javier; Kinzel, Edward; Boreman, Glenn
2017-02-01
When considering the pseudo-heterodyne mode for detection of the modulus and phase of the near field from scattering scanning near-field optical microscopy (s-SNOM) measurements, processing only the modulus of the signal may produce an undesired constraint in the accessible values of the phase of the near field. A two-dimensional analysis of the signal provided by the data acquisition system makes it possible to obtain phase maps over the whole [0, 2π) range. This requires post-processing of the data to select the best coordinate system in which to represent the data along the direction of maximum variance. The analysis also provides a quantitative parameter describing how much of the total variance is included within the component selected for calculation of the modulus and phase of the near field. The dependence of the pseudo-heterodyne phase on the mean position of the reference mirror is analyzed, and the evolution of the global phase is extracted from the s-SNOM data. The results obtained from this technique compared well with the expected maps of the near-field phase obtained from simulations.
Effects of nonlinear phase modulation on Bragg scattering in the low-conversion regime
DEFF Research Database (Denmark)
Andersen, Lasse Mejling; Cargill, D. S.; McKinstrie, C. J.
2012-01-01
In this paper, we consider the effects of nonlinear phase modulation on frequency conversion by four-wave mixing (Bragg scattering) in the low-conversion regime. We derive the Green functions for this process using the time-domain collision method, for partial collisions, in which the four fields...... interact at the beginning or the end of the fiber, and complete collisions, in which the four fields interact at the midpoint of the fiber. If the Green function is separable, there is only one output Schmidt mode, which is free from temporal entanglement. We find that nonlinear phase modulation always...... chirps the input and output Schmidt modes and renders the Green function formally nonseparable. However, by pre-chirping the pumps, one can reduce the chirps of the Schmidt modes and enable approximate separability. Thus, even in the presence of nonlinear phase modulation, frequency conversion...
Probing interactions and phase separations of proteins, colloids, and polymers with light scattering
Parmar, Avanish Singh
The broad objective of my research is to investigate the physical characteristics and interactions of macromolecules and nanoparticles, and the corresponding effects on their phase separation behavior using static and dynamic light scattering (SLS & DLS). Light scattering provides a non-invasive technique for monitoring the in-situ behavior of solutes in solution, including solute interactions, sizes, shapes, aggregation kinetics and even rheological properties of condensed phases. Initially, we investigated lysozyme solutions for the presence of preformed aggregates and clusters that can distort the kinetics of protein crystal nucleation studies in this important model system for protein crystallization. We found that both undersaturated and supersaturated lysozyme solutions contained population of large, pre-existing protein aggregate. Separating these clusters and analyzing their composition with gel chromatography indicated that these clusters represented pre-formed lysozyme aggregates, and not extrinsic protein contamination. We investigated the effect of chaotropic versus kosmotropic ions (water structure breakers vs. structure makers) on the hydration layer and hydrodynamic interactions of hen egg white lysozyme. Surprisingly, neither chaotropic nor kosmotropic ions affected the protein hydration layer. Salt-effects on direct and hydrodynamic protein interactions were determined as function of the solutions ionic strength and temperature. Using both static and dynamic light scattering, we investigated the nucleation of gold nanoparticles forming from supersaturated gold sols. We observed that two well separated populations of nuclei formed essentially simultaneously, with sizes of 3nm vs. several tens of nanometer, respectively. We explore the use of lysozyme as tracer particle for diffusion-base measurements of electrolyte solutions. We showed that the unusual stability of lysozyme and its enhanced colloidal stability enable viscosity measurement of salts
Purcell, Michael James
Existing methods for focusing and imaging through strongly scattering materials are often limited by speed, the need for invasive feedback, and the shallow depth of penetration of photons into the material. These limitations have motivated the present research into the development of a new iterative phase optimization method for improving transmission of light through a sample of strongly scattering material. A new method, based on the detection of back-scattered light combined with active (phase-only) wavefront control was found to be partially successful, decreasing the power of backscattered incident light at 488 nm wavelength by approximately 35% in a 626 mum thick sample of Yttria (Y2O3) nanopowder (mean particle size 26 nm) in clear epoxy with transport mean free path length ˜116 mum. However, the observed transmitted power did not show simultaneous improvement. The conclusion was reached that scattering to the sides of the sample and polarization scrambling were responsible for the lack of improved transmission with this method. Some ideas for improvement are discussed in the thesis. This research subsequently led to the development of a lensless holographic imaging method based on a rotating diffuser for statistical averaging of the optical signal for overcoming speckle caused by reflection from a rough surface. This method made it possible to reduce background variations of intensity due to speckle and improve images reflected from rough, immobile surfaces with no direct path for photons between the object and camera. Improvements in the images obtained with this technique were evaluated quantitatively by comparing SSIM indices and were found to offer practical advances for transmissive and reflective geometries alike.
DEFF Research Database (Denmark)
Ekhtiari, Marzieh; Zsurzsan, Tiberiu-Gabriel; Andersen, Michael A. E.
2017-01-01
A new method is implemented in designing of self-oscillating loop for driving piezoelectric transformers. The implemented method is based on combining both analog and digital control systems. Digitally controlled time delay through the self-oscillating loop results in very precise frequency control...... and ensures optimum operation of the piezoelectric transformer in terms of gain and efficiency. Time delay is implemented digitally for the first time through a 16 bit digital-to-analog converter in the self-oscillating loop. The new design of the delay circuit provides 45 ps time resolution, enabling fine......-grained control of phase in the self-oscillating loop. This allows the control loop to dynamically follow frequency changes of the transformer in each resonant cycle. Ultimately, by selecting the optimum phase shift, maximum efficiency under the load and temperature condition is achievable....
Directory of Open Access Journals (Sweden)
Qi Wu
2014-01-01
Full Text Available In this research, the sensitivity distribution properties of a phase-shifted fiber Bragg grating (PS-FBG to ultrasonic waves were investigated employing the surface attachment method. A careful consideration was taken and examined by experimental results to explain that the distances and angles between the sensor and ultrasonic source influence not only the amplitudes, but also the initial phases, waveforms, and spectra of detected signals. Furthermore, factors, including the attachment method and the material’s geometric dimensions, were also discussed. Although these results were obtained based on PS-FBG, they are also applicable to a normal FBG sensor or even an optical fiber sensor, due to the identical physical changes induced by ultrasonic waves in all three. Thus, these results are useful for applications of optical fiber sensors in non-destructive testing and structural health monitoring.
Wu, Qi; Okabe, Yoji; Saito, Kazuya; Yu, Fengming
2014-01-09
In this research, the sensitivity distribution properties of a phase-shifted fiber Bragg grating (PS-FBG) to ultrasonic waves were investigated employing the surface attachment method. A careful consideration was taken and examined by experimental results to explain that the distances and angles between the sensor and ultrasonic source influence not only the amplitudes, but also the initial phases, waveforms, and spectra of detected signals. Furthermore, factors, including the attachment method and the material's geometric dimensions, were also discussed. Although these results were obtained based on PS-FBG, they are also applicable to a normal FBG sensor or even an optical fiber sensor, due to the identical physical changes induced by ultrasonic waves in all three. Thus, these results are useful for applications of optical fiber sensors in non-destructive testing and structural health monitoring.
Rivera-Ortega, Uriel; Dirckx, Joris
2015-09-01
In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.
Qin, Wan; Peng, Xiang; Meng, Xiangfeng; Gao, Bruce Z
2011-06-13
The optical cryptosystem based on phase-shifting interferometry (PSI) is one of the most interesting optical cryptographic schemes in recent years. However, we find that the PSI technique provides an attractive method to record the ciphertext, but contributes little to the security level of the cryptosystem. From the cryptanalysis point of view, in a certain simplified case, an attacker is only required to crack two equivalent decryption keys instead of the original random phase keys and geometric key. Moreover, a chosen-plaintext attack method is proposed, in which an impulse function is chosen as a known plaintext. By using this attack, the attacker can effectively recover any plaintext from the corresponding ciphertext. The validity of the attack is verified by computer simulations.
Cheng, Jingchi; Tang, Ming; Fu, Songnian; Shum, Perry Ping; Liu, Deming
2013-04-01
We show for the first time, to the best of our knowledge, that, in a coherent communication system that employs a phase-shift-keying signal and Raman amplification, besides the pump relative intensity noise (RIN) transfer to the amplitude, the signal's phase will also be affected by pump RIN through the pump-signal cross-phase modulation. Although the average pump power induced linear phase change can be compensated for by the phase-correction algorithm, a relative phase noise (RPN) parameter has been found to characterize pump RIN induced stochastic phase noise. This extra phase noise brings non-negligible system impairments in terms of the Q-factor penalty. The calculation shows that copumping leads to much more stringent requirements to pump RIN, and relatively larger fiber dispersion helps to suppress the RPN induced impairment. A higher-order phase-shift keying (PSK) signal is less tolerant to noise than a lower-order PSK.
DEFF Research Database (Denmark)
Chen, Yaohui; Mørk, Jesper
2010-01-01
We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers.......We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers....
DEFF Research Database (Denmark)
Chen, Yaohui; Öhman, Filip; Xue, Weiqi
2008-01-01
We theoretically analyze and interpret an effective mechanism, which employs optical filtering to enhance the microwave phase shift that can be achieved in semiconductor optical amplifiers based on slow and fast light effects.......We theoretically analyze and interpret an effective mechanism, which employs optical filtering to enhance the microwave phase shift that can be achieved in semiconductor optical amplifiers based on slow and fast light effects....
Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology.
Radonić, Vasa; Birgermajer, Slobodan; Kitić, Goran
2017-04-18
In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG) sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor's operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG) structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM) 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene-methanol mixture where various concentrations of toluene were analysed.
Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology
Directory of Open Access Journals (Sweden)
Vasa Radonić
2017-04-01
Full Text Available In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor’s operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene–methanol mixture where various concentrations of toluene were analysed.
Fibre optic gyroscope with single-mode fibre and loop-back phase shift compensation
Skalský, Michal; Havránek, Zdeněk.; Fialka, Jiří
2017-12-01
An all-fibre optical sensor of an angular velocity (fibre-optic gyroscope) based on the Sagnac interferometer and using a loop-back phase shift compensation is presented. The sensing loop consists of 760 metres of an ordinary single-mode fibre, which makes this setup cost-effective. To ensure principles of beams reciprocity, randomly induced changes of polarization in the fibre are reduced by using an unpolarized light. This is achieved by a fibre Lyot depolarizer and a super fluorescent fibre source consisting of an erbium-doped fibre pumped by a laser diode. Unlike common approaches to the unpolarized fibre-optic gyroscope with a single-mode fibre, whose output is naturally nonlinear, we use a loop-back compensation of a rotation-induced phase shift to achieve a linear response. In most cases, this technique requires fast electro-optical modulator, which is compatible only with an expensive polarization-maintaining fibre. We use a novel loop-back modulation scheme utilizing only harmonic signals and thus compatible with a piezoelectric fibre stretcher, which can be used with any kind of optical fibre. As result of the closed-loop operation, the range of the gyroscope's linearity is greatly increased and a sensitivity to source power changes is suppressed. We describe the gyroscope setup with proposed modulation method and provide a comparison to the common open-loop setup.
Phase shifts, herbivory, and the resilience of coral reefs to climate change.
Hughes, Terence P; Rodrigues, Maria J; Bellwood, David R; Ceccarelli, Daniela; Hoegh-Guldberg, Ove; McCook, Laurence; Moltschaniwskyj, Natalie; Pratchett, Morgan S; Steneck, Robert S; Willis, Bette
2007-02-20
Many coral reefs worldwide have undergone phase shifts to alternate, degraded assemblages because of the combined effects of over-fishing, declining water quality, and the direct and indirect impacts of climate change. Here, we experimentally manipulated the density of large herbivorous fishes to test their influence on the resilience of coral assemblages in the aftermath of regional-scale bleaching in 1998, the largest coral mortality event recorded to date. The experiment was undertaken on the Great Barrier Reef, within a no-fishing reserve where coral abundances and diversity had been sharply reduced by bleaching. In control areas, where fishes were abundant, algal abundance remained low, whereas coral cover almost doubled (to 20%) over a 3 year period, primarily because of recruitment of species that had been locally extirpated by bleaching. In contrast, exclusion of large herbivorous fishes caused a dramatic explosion of macroalgae, which suppressed the fecundity, recruitment, and survival of corals. Consequently, management of fish stocks is a key component in preventing phase shifts and managing reef resilience. Importantly, local stewardship of fishing effort is a tractable goal for conservation of reefs, and this local action can also provide some insurance against larger-scale disturbances such as mass bleaching, which are impractical to manage directly.
Phase-shift-controlled logic gates in Y-shaped nonlinearly coupled chains.
Assunção, T F; Nascimento, E M; Sombra, A S B; Lyra, M L
2016-02-01
We introduce a model system composed of two input discrete chains nonlinearly coupled to a single output chain which mimics the geometry of Y-shaped carbon nanotubes, photonic crystal wave guides, and DNA junctions. We explore the capability of the proposed system to perform logic gate operations based on the transmission of phase-shifted harmonic incoming waves. Within a tight-binding approach, we determine the exact transmission spectrum which exhibits a nonlinear induced bistability. Using a digitalization scheme of the output signal based on amplitude modulation, we show that AND, OR, and XOR logic operations can be achieved. Nonlinearity strongly favors the realization of logic operations in the regime of large wavelengths, while phase shifting is required for the OR logic gate to be realizable. A detailed analysis of the contrast ratio shows that optimal operation of the AND and OR logic gates takes place when the nonlinear response is the predominant physical property distinguishing the coupling and regular sites. These results point towards the possibility of Y-branched junctions to perform logic operations based on the transmission of traveling waves.
Jeon, Seok-Hee; Gil, Sang-Keun
2016-12-01
We propose an optical design of cipher block chaining (CBC) encryption mode using digital holography, which is implemented by the two-step quadrature phase-shifting digital holographic encryption technique using orthogonal polarization. A block of plain text is encrypted with the encryption key by applying the two-step phase-shifting digital holographic method; then, it is changed into cipher text blocks which are digital holograms. Optically, these digital holograms with the encrypted information are Fourier transform holograms and are recorded onto charge-coupled devices with 256 quantization gray levels. This means that the proposed optical CBC encryption is a scheme that has an analog-type of pseudorandom pattern information in the cipher text, while the conventional electronic CBC encryption is a kind of bitwise block message encryption processed by digital bits. Also, the proposed method enables the cryptosystem to have higher security strength and faster processing than the conventional electronic method because of the large two-dimensional (2-D) array key space and parallel processing. The results of computer simulations verify that the proposed optical CBC encryption design is very effective in CBC mode due to fast and secure optical encryption of 2-D data and shows the feasibility for the CBC encryption mode.
Liu, Yan; Ma, Cheng; Shen, Yuecheng; Wang, Lihong V.
2017-02-01
Optical phase conjugation based wavefront shaping techniques are being actively developed to focus light through or inside scattering media such as biological tissue, and they promise to revolutionize optical imaging, manipulation, and therapy. The speed of digital optical phase conjugation (DOPC) has been limited by the low speeds of cameras and spatial light modulators (SLMs), preventing DOPC from being applied to thick living tissue. Recently, a fast DOPC system was developed based on a single-shot wavefront measurement method, a field programmable gate array (FPGA) for data processing, and a digital micromirror device (DMD) for fast modulation. However, this system has the following limitations. First, the reported single-shot wavefront measurement method does not work when our goal is to focus light inside, instead of through, scattering media. Second, the DMD performed binary amplitude modulation, which resulted in a lower focusing contrast compared with that of phase modulations. Third, the optical fluence threshold causing DMDs to malfunction under pulsed laser illumination is lower than that of liquid crystal based SLMs, and the system alignment is significantly complicated by the oblique reflection angle of the DMD. Here, we developed a simple but high-speed DOPC system using a ferroelectric liquid crystal based SLM (512 × 512 pixels), and focused light through three diffusers within 4.7 ms. Using focused-ultrasound-guided DOPC along with a double exposure scheme, we focused light inside a scattering medium containing two diffusers within 7.7 ms, thus achieving the fastest digital time-reversed ultrasonically encoded (TRUE) optical focusing to date.
Arahman, Nasrul; Maimun, Teuku; Mukramah, Syawaliah
2017-01-01
The composition of polymer solution and the methods of membrane preparation determine the solidification process of membrane. The formation of membrane structure prepared via non-solvent induced phase separation (NIPS) method is mostly determined by phase separation process between polymer, solvent, and non-solvent. This paper discusses the phase separation process of polymer solution containing Polyethersulfone (PES), N-methylpirrolidone (NMP), and surfactant Tetronic 1307 (Tet). Cloud point experiment is conducted to determine the amount of non-solvent needed on induced phase separation. Amount of water required as a non-solvent decreases by the addition of surfactant Tet. Kinetics of phase separation for such system is studied by the light scattering measurement. With the addition of Tet., the delayed phase separation is observed and the structure growth rate decreases. Moreover, the morphology of fabricated membrane from those polymer systems is analyzed by scanning electron microscopy (SEM). The images of both systems show the formation of finger-like macrovoids through the cross-section.
PDF neuron firing phase-shifts key circadian activity neurons in Drosophila.
Guo, Fang; Cerullo, Isadora; Chen, Xiao; Rosbash, Michael
2014-06-17
Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.
Directory of Open Access Journals (Sweden)
Jos H T Rohling
Full Text Available The circadian pacemaker of the suprachiasmatic nuclei (SCN contains a major pacemaker for 24 h rhythms that is synchronized to the external light-dark cycle. In response to a shift in the external cycle, neurons of the SCN resynchronize with different pace. We performed electrical activity recordings of the SCN of rats in vitro following a 6 hour delay of the light-dark cycle and observed a bimodal electrical activity pattern with a shifted and an unshifted component. The shifted component was relatively narrow as compared to the unshifted component (2.2 h and 5.7 h, respectively. Curve fitting and simulations predicted that less than 30% of the neurons contribute to the shifted component and that their phase distribution is small. This prediction was confirmed by electrophysiological recordings of neuronal subpopulations. Only 25% of the neurons exhibited an immediate shift in the phase of the electrical activity rhythms, and the phases of the shifted subpopulations appeared significantly more synchronized as compared to the phases of the unshifted subpopulations (p<0.05. We also performed electrical activity recordings of the SCN following a 9 hour advance of the light-dark cycle. The phase advances induced a large desynchrony among the neurons, but consistent with the delays, only 19% of the neurons peaked at the mid of the new light phase. The data suggest that resetting of the central circadian pacemaker to both delays and advances is brought about by an initial shift of a relatively small group of neurons that becomes highly synchronized following a shift in the external cycle. The high degree of synchronization of the shifted neurons may add to the ability of this group to reset the pacemaker. The large desynchronization observed following advances may contribute to the relative difficulty of the circadian system to respond to advanced light cycles.
Energy Technology Data Exchange (ETDEWEB)
Wang, Boyun; Wang, Tao, E-mail: wangtao@hust.edu.cn; Tang, Jian; Li, Xiaoming; Dong, Chuanbo [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)
2014-01-14
We propose phase shift multiplication effect of all-optical analog to electromagnetically induced transparency in two photonic crystal micro-cavities side coupled to a waveguide system through external optical pump beams. With dynamically tuning the propagation phase of the line waveguide, the phase shift of the transmission spectrum in two micro-cavities side coupled to a waveguide system is doubled along with the phase shift of the line waveguide. π-phase shift and 2π-phase shift of the transmission spectrum are obtained when the propagation phase of the line waveguide is tuned to 0.5π-phase shift and π-phase shift, respectively. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and the coupled-mode formalism. These results show a new direction to the miniaturization and the low power consumption of microstructure integration photonic devices in optical communication and quantum information processing.
Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei
2016-05-26
Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.
Mansurova, S; Zarate, P Moreno; Rodriguez, P; Stepanov, S; Köber, S; Meerholz, K
2012-02-01
Non-steady-state photoelectromotive force effect in the presence of periodical and linear phase shift was investigated both theoretically and experimentally. It was shown that superposition of oscillating and linear movements of the interference pattern leads to the appearance of the sharp peak in the frequency dependence of the photoelectromotive force output current when the frequency of periodical modulation matches the frequency of the linear phase shift. We demonstrated experimentally that this effect can be used for determination of a Doppler frequency shift between signal and reference beam.
Mom, T; Montalban, A; Bascoul, A; Gilain, L; Avan, P
2012-02-01
Still today, Menière's disease (MD) can be definitively diagnosed only on post-mortem findings of endolymphatic hydrops. Otoacoustic emission (OAE) phase has been shown to be highly sensitive to intracranial pressure. Preliminary analysis of OAEs in MD patients indicated high sensitivity to slight variations in intracranial pressure. The principal objective of the present study was to confirm this specific sensitivity of OAEs in MD. In a prospective study of 32 consecutive cases of acute MD seen in consultation or hospital, 20 patients (23 ears) underwent acoustic phase-shift test: i.e., seated vs. supine OAE phase centered around 1kHz, with results compared to controls. The acoustic phase-shift test was performed in 62.5% of acute patients (58.9% of affected ears). In the control group, the 95% confidence interval for phase shift was between -30° and +45°. Phase shift was significantly elevated, beyond the normal interval, in 18 of the MD patients: range, -80° to +145°. Sensitivity was 90%. Overall, in patients in whom transient evoked OAEs (TEOAEs) were present, positive predictive value was 100% and negative predictive value 92.3%. The acoustic phase-shift test proved useful and powerful in demonstrating pressure imbalance in acute Menière's disease. Copyright © 2011. Published by Elsevier Masson SAS.
Jose, J.; Segerink, Franciscus B.; Korterik, Jeroen P.; Offerhaus, Herman L.
2008-01-01
We report the near-field observation of the phase shifts associated with total internal reflection on a glass-air interface and surface plasmon resonance on a glass-gold-air system. The phase of the evanescent waves on glass and gold surfaces, as a function of incident angle, is measured using a
DEFF Research Database (Denmark)
Thomsen, Jon Juel; Dahl, Jonas
2010-01-01
Resonant vibrations of a fluid-conveying pipe are investigated, with special consideration to axial shifts in vibration phase accompanying fluid flow and various imperfections. This is relevant for understanding elastic wave propagation in general, and for the design and trouble-shooting of phase...
Jurna, M.; Garbacik, E.T.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Otto, Cornelis; Offerhaus, Herman L.
2010-01-01
In coherent anti-Stokes Raman scattering (CARS), the emitted signal carries both amplitude and phase information of the molecules in the focal volume. Most CARS experiments ignore the phase component, but its detection allows for two advantages over intensity-only CARS. First, the pure resonant
Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift.
Ling, S D; Johnson, C R; Frusher, S D; Ridgway, K R
2009-12-29
A key consideration in assessing impacts of climate change is the possibility of synergistic effects with other human-induced stressors. In the ocean realm, climate change and overfishing pose two of the greatest challenges to the structure and functioning of marine ecosystems. In eastern Tasmania, temperate coastal waters are warming at approximately four times the global ocean warming average, representing the fastest rate of warming in the Southern Hemisphere. This has driven range extension of the ecologically important long-spined sea urchin (Centrostephanus rodgersii), which has now commenced catastrophic overgrazing of productive Tasmanian kelp beds leading to loss of biodiversity and important rocky reef ecosystem services. Coincident with the overgrazing is heavy fishing of reef-based predators including the spiny lobster Jasus edwardsii. By conducting experiments inside and outside Marine Protected Areas we show that fishing, by removing large predatory lobsters, has reduced the resilience of kelp beds against the climate-driven threat of the sea urchin and thus increased risk of catastrophic shift to widespread sea urchin barrens. This shows that interactions between multiple human-induced stressors can exacerbate nonlinear responses of ecosystems to climate change and limit the adaptive capacity of these systems. Management actions focused on reducing the risk of catastrophic phase shift in ecosystems are particularly urgent in the face of ongoing warming and unprecedented levels of predator removal from the world's oceans.
Wave-mixing-induced transparency with zero phase shift in atomic vapors
Zhou, F.; Zhu, C. J.; Li, Y.
2017-12-01
We present a wave-mixing induced transparency that can lead to a hyper-Raman gain-clamping effect. This new type of transparency is originated from a dynamic gain cancellation effect in a multiphoton process where a highly efficient light field of new frequency is generated and amplified. We further show that this novel dynamic gain cancellation effect not only makes the medium transparent to a probe light field at appropriate frequency but also eliminates the probe field propagation phase shift. This gain-cancellation-based induced transparency holds for many potential applications on optical communication and may lead to effective suppression of parasitic Raman/hyper-Raman noise field generated in high intensity optical fiber transmissions.
Surface measurements by white light spatial-phase-shift imaging interferometry.
Arieli, Yoel; Epshtein, Shlomi; Yakubov, Igor; Weitzman, Yosi; Locketz, Garrett; Harris, Alon
2014-06-30
A novel method of common-path imaging interferometry, the White Light Spatial-Phase-Shift (WLSPS) for object surface measurements, is discussed here. Compared to standard White Light Interferometry (WLI), which uses a reference mirror, the interferometry of WLSPS is obtained by creating manipulations to the light wavefront reflected from an object's surface. Using this approach, surface measurements can be obtained from any real object image, and do not need to be taken directly from the object itself. This creates the ability for a surface measurement tool to be attached to any optical system that generates a real image of an object. Further, as this method does not require a reference beam, the surface measurement system contains inherent vibration cancelation.
Practical round-robin differential phase-shift quantum key distribution.
Zhang, Ying-Ying; Bao, Wan-Su; Zhou, Chun; Li, Hong-Wei; Wang, Yang; Jiang, Mu-Sheng
2016-09-05
Recently, a novel protocol named round-robin differential phase-shift (RRDPS) quantum key distribution [Nature 509, 475(2014)] has been proposed. It can estimate information leakage without monitoring bit error rate. In this paper, we study the performance of RRDPS using heralded single photon source (HSPS) without and with decoy-state method, then compare it with the performance of weak coherent pulses (WCPs). From numerical simulation, we can see that HSPS performs better especially for shorter packet and higher bit error rate. Moreover, we propose a general theory of decoy-state method for RRDPS protocol based on only three decoy states and one signal state. Taking WCPs as an example, the three-intensity decoy-state protocol can distribute secret keys over a distance of 128 km when the length of pulses packet is 32, which confirms great practical interest of our method.
Rapid yet accurate measurement of mass diffusion coefficients by phase shifting interferometer
Guo Zhi Xiong; Komiya, A
1999-01-01
The technique of using a phase-shifting interferometer is applied to the study of diffusion in transparent liquid mixtures. A quick method is proposed for determining the diffusion coefficient from the measurements of the location of fringes on a grey level picture. The measurement time is very short (within 100 s) and a very small transient diffusion field can be observed and recorded accurately with a rate of 30 frames per second. The measurement can be completed using less than 0.12 cc of solutions. The influence of gravity on the measurement of the diffusion coefficient is eliminated in the present method. Results on NaCl-water diffusion systems are presented and compared with the reference data. (author)
Gambi, Cecilia M C; Vannoni, Maurizio; Sordini, Andrea; Molesini, Giuseppe
2014-02-01
An interferometric method to monitor the thinning process of vertical soap films from a water solution of surfactant materials is reported. Raw data maps of optical path difference introduced by the film are obtained by conventional phase shift interferometry. Off-line re-processing of such raw data taking into account the layered structure of soap films leads to an accurate measurement of the geometrical thickness. As an example of data acquisition and processing, the measuring chain is demonstrated on perfluoropolyether surfactants; the section profile of vertical films is monitored from drawing to black film state, and quantitative data on the dynamics of the thinning process are presented. The interferometric method proves effective to the task, and lends itself to further investigate the physical properties of soap films.
Application of Ultrasound Phase-Shift Analysis to Authenticate Wooden Panel Paintings
Directory of Open Access Journals (Sweden)
José M. Bravo
2014-05-01
Full Text Available Artworks are a valuable part of the World’s cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated encoding system that enables authentication of the authorship of wooden panel paintings. The method has been evaluated in comparison with optical analysis and shows promising results. The proposed method provides an integrated fingerprint of the artwork, and could be used to enrich the cataloging and protection of artworks. Other advantages that make particularly attractive the proposed technique are its robustness and the use of low-cost sensors.
Application of ultrasound phase-shift analysis to authenticate wooden panel paintings.
Bravo, José M; Sánchez-Pérez, Juan V; Ferri, Marcelino; Redondo, Javier; Picó, Rubén
2014-05-05
Artworks are a valuable part of the World's cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated encoding system that enables authentication of the authorship of wooden panel paintings. The method has been evaluated in comparison with optical analysis and shows promising results. The proposed method provides an integrated fingerprint of the artwork, and could be used to enrich the cataloging and protection of artworks. Other advantages that make particularly attractive the proposed technique are its robustness and the use of low-cost sensors.
p-type GaN grown by phase shift epitaxy
Energy Technology Data Exchange (ETDEWEB)
Zhong, M.; Steckl, A. J., E-mail: a.steckl@uc.edu [Department of Electrical Engineering and Computing Systems, University of Cincinnati, Cincinnati, Ohio 45221-0030 (United States); Roberts, J. [Nitronex Corporation, Raleigh, North Carolina 27606 (United States); Kong, W.; Brown, A. S. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)
2014-01-06
Phase shift epitaxy (PSE) is a periodic growth scheme, which desynchronizes host material growth process from dopant incorporation, allowing independent optimization. p-type doping of GaN with Mg by PSE is accomplished with molecular beam epitaxy by periodic shutter action (in order to iterate between Ga- and N-rich surface conditions) and by adjusting time delays between dopant and Ga shutters. Optimum PSE growth was obtained by turning on the Mg flux in the N-rich condition. This suppresses Mg self-compensation at high Mg concentration and produces fairly high hole concentrations (2.4 × 10{sup 18} cm{sup −3})
Quality investigation of surface mount technology using phase-shifting digital holography
Boonsri, Chantira; Buranasiri, Prathan
2016-09-01
Applying of a phase-shifting digital holography combined with compressive sensing to inspect the soldering quality of surface mount technology (SMT) which is a method for producing electronic circuits. In SMT, the components are mounted and connected with each other directly onto the surface of printed circuit boards (PCBs). By reconstructing the multidimensional images from a few samples of SMT, the results are solved by an optimization problem. In this paper, two problems have been concerned. The first one is to examine the devices and the soldering quality of connections between them, which are in micro-scaled. The second is to observe the effect of heat treatment of soldering material and devices on the surface mount board.
Li, Bingpeng
2017-02-01
Realizing long-distance quantum key distribution (QKD) in fiber channel where classical optical communications and quantum signals are multiplexed by their different wavelengths has attracted considerable attentions. The achievable secure distance of commonly-used Bennet-Brassard 1984 (BB84) protocol is lowered severely due to inevitable crosstalk from classical optical pulses. Unlike conventional quantum key distribution (QKD) protocols, round-robin differential-phase-shift (RRDPS) QKD protocol has a high tolerance for noise, since the potential information leakage in this protocol can be bounded without monitoring signal disturbance. Thus, it may be a promising protocol under noisy channel. In this work, we investigate the performance, e.g., achievable secure distance of RRPDS protocol, when crosstalk from classical communication is considered. Surprisingly, we find that RRPDS only has quite limited advantage over BB84 protocol when optical misalignment of QKD system is serious. If misalignment is trivial, BB84 can even outperform RRDPS protocol.
LMS IPRO: enabling accurate registration metrology on SiN-based phase-shift masks
Steigerwald, Hendrik; Han, Runyuan; Buettner, Alexander; Roeth, Klaus-Dieter
2017-07-01
SiN-based absorber materials are considered to be the new work horse for cutting-edge patterning using 193-nm immersion lithography. The high robustness against cleaning procedures and the low susceptibility for haze makes SiN an ideal material for phase-shift masks. Reliable metrology with high precision, on target as well as on feature, is enabled by the LMS IPROTM metrology tool. This is achieved by taking into account the optical properties of the novel materials and utilisation of the high-accuracy die-to-database algorithm. Simulation as well as actual measurement results are presented. Cost effectiveness of the LMS IPRO is demonstrated by comparison of high-performance mode results versus high-throughput results, confirming suitable metrology performance for high-volume manufacturing.
Hénault, François
2011-07-20
We describe the principle of a multiaperture interferometer that uses a phase-shifting technique and is suitable for quick snapshot imaging of astrophysical objects at extreme angular resolution through Fourier inversion. A few advantages of the proposed design are highlighted, among which are radiometric efficiency, field of view equivalent to those of Fizeau interferometers, and a preliminary calibration procedure allowing characterization of instrumental errors. For large telescope numbers, the proposed design also results in considerable simplification of the optical and mechanical design. Numerical simulations suggest that it should be possible to couple hundreds of telescopes on a single 4K × 4K detector array, using only conventional optical components or emerging technologies. © 2011 Optical Society of America
Zhu, Meng; Zhang, Hao; Li, Xiangyu; Huang, Zhanhua
2013-09-01
A modified Michelson interferometer for spatial phase shifting speckle shearography is presented. The interferometer consists of one slit aperture, one beam splitter, and two spherical mirrors. Spatial carrier frequency and shear are both generated by one translated spherical mirror. The slit aperture controls the speckle size. These arrangements make the system simple and easy to align. The shear is proportional to the translation of the spherical mirror. Shear distortion due to the rotated mirror in a traditional Michelson interferometer is avoided as well. The carrier frequency is proven to be constant in image plane and can be conveniently adjusted by translating the spherical mirror without changing imaging setup. Fourier analysis method is applied to accurately calibrate carrier frequency. Finally, experimental dynamic deformation results of a center loaded metal plate using the proposed method are provided.
Davies, J.A.; Navaratnam, V.; Redfern, P.H.
1974-01-01
1 In rats trained to a 12 h light-12 h dark cycle, advancing the phase by 6 h produced a resynchronization of the 24 h variation in passive avoidance response (PAR) which was completed after 10 days. 2 The attainment of the new steady state was preceded by a period of disruption which was greatest 5 days after phase-shift. 3 The presence of chlordiazepoxide (62.5-500 μg/ml) in the drinking water during the days after phase-shift produced a dose-dependent lessening of the disruptive effect of phase-shift, and a more rapid adaptation to the new light-dark cycle. PMID:4451757
Kwak, Moon Kyu; Ok, Jong G; Lee, Jae Yong; Guo, L Jay
2012-08-31
We report the development of a near-field optical nanolithography method using a roll-type phase-shift mask. Sub-wavelength resolution is achieved using near-field exposure of photoresist through a cylindrical phase mask, allowing dynamic and high throughput continuous patterning. As an application, we present the fabrication of a transparent electrode in the form of a metallic wire grid by using the roller-based optical lithography method. To fabricate a mesh-type metal pattern, a specific phase-shift mask was designed and critical experimental parameters were also studied. As a result, a transparent conductor with suitable properties was achieved with a recently built cylindrical phase-shift lithography prototype designed to pattern on 100 mm(2) of substrate area.
Lin, Guoxing
2015-10-01
Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, K(β)(t)D rad(β)/s(α), where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γ(β)g(β)δ(β)Df1t(α)), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γ(β)g(β)δ(β)Df2t(α)), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α=1, and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1∫0(τ) K(β)(t)dt(α)]. The results obtained in this study are in good agreement with the results in literature. Several expressions that
Lin, Guoxing
2015-10-01
Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, Kβ(t)D radβ/sα, where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γβgβδβDf1 tα), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γβgβδβDf2 tα), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α = 1 , and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1 ∫0τ Kβ (t)dtα ] . The results obtained in this study are in good agreement with the results in literature. Several expressions that describe signal
Petzold, A.; Perim de Faria, J.; Berg, M.; Bundke, U.; Freedman, A.
2015-12-01
Monitoring the direct impact of aerosol particles on climate requires the continuous measurement of aerosol optical parameters like the aerosol extinction coefficient on a regular basis. Remote sensing and ground-based networks are well in place (e.g., AERONET, ACTRIS), whereas the regular in situ measurement of vertical profiles of atmospheric aerosol optical properties remains still an important challenge in quantifying climate change. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. Recently, a compact and robust family of optical instruments based on the cavity attenuated phase shift (CAPS) technique has become available for measuring aerosol light extinction. While this technique was successfully deployed for ground-based atmospheric measurements under various conditions, its suitability for operation aboard aircraft in the free and upper free troposphere still has to be demonstrated. In this work, the modifications of a CAPS PMex instrument for measuring aerosol light extinction on aircraft, the results from subsequent laboratory tests for evaluating the modified instrument prototype, and first results from a field deployment aboard a research aircraft will be covered. In laboratory studies, the instrument showed excellent agreement (deviation < 5%) with theoretical values calculated from Rayleigh scattering cross-sections, when operated on pressurized air and CO2 at ambient and low pressure (~200 hPa). For monodisperse and polydisperse aerosols, reference aerosol extinction coefficients were calculated from measured size distributions and agreed with the CAPS PMex instrument
Varghese, B; Rajan, V; van Leeuwen, T G; Steenbergen, W
2007-07-23
We show experimental validation of a novel technique to measure optical path length distributions and path length resolved Doppler broadening in turbid media for different reduced scattering coefficients and anisotropies. The technique involves a phase modulated low coherence Mach-Zehnder interferometer, with separate fibers for illumination and detection. Water suspensions of Polystyrene microspheres with high scattering and low absorption levels are used as calibrated scattering phantoms. The path length dependent diffusion broadening or Doppler broadening of scattered light is shown to agree with Diffusive Wave Spectroscopy within 5%. The optical path lengths are determined experimentally from the zero order moment of the phase modulation peak around the modulation frequency in the power spectrum and the results are validated with Monte Carlo simulations.
Varghese, B.; Rajan, V.; van Leeuwen, T. G.; Steenbergen, W.
2007-07-01
We show experimental validation of a novel technique to measure optical path length distributions and path length resolved Doppler broadening in turbid media for different reduced scattering coefficients and anisotropies. The technique involves a phase modulated low coherence Mach-Zehnder interferometer, with separate fibers for illumination and detection. Water suspensions of Polystyrene microspheres with high scattering and low absorption levels are used as calibrated scattering phantoms. The path length dependent diffusion broadening or Doppler broadening of scattered light is shown to agree with Diffusive Wave Spectroscopy within 5%. The optical path lengths are determined experimentally from the zero order moment of the phase modulation peak around the modulation frequency in the power spectrum and the results are validated with Monte Carlo simulations.
Energy Technology Data Exchange (ETDEWEB)
Aoun, Bachir; Pellegrini, Eric; Trapp, Marcus; Natali, Francesca; Cantù, Laura; Brocca, Paola; Gerelli, Yuri; Demé, Bruno; Marek Koza, Michael; Johnson, Mark; Peters, Judith
2016-04-01
Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural and dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.
DEFF Research Database (Denmark)
Makda, Ishtiyaq Ahmed; Nymand, Morten
2015-01-01
This paper presents the common-mode noise analysis and modeling of a phase-shifted full-bridge forward converter. The common-mode noise source due to a transformer inter-winding capacitance is considered for the case of study. The generated common-mode noise voltage-source in a converter is analy......This paper presents the common-mode noise analysis and modeling of a phase-shifted full-bridge forward converter. The common-mode noise source due to a transformer inter-winding capacitance is considered for the case of study. The generated common-mode noise voltage-source in a converter...... is analytically determined, which then leads to a common-mode noise modeling of a phase-shifted converter. Using a proposed model, common-mode noise-current harmonics are calculated and a fully analytical filter design procedure is presented to comply with the CISPR-11 standard. Finally, a prototype phase-shifted...... forward converter is built to verify the theoretical analysis. This study shows that the primary-to-secondary transformer winding capacitance creates a very significant amount of common-mode noise current in a phase-shifted forward converter....
Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu
2013-01-01
This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications.
Work, Thierry M; Aeby, Greta S; Maragos, James E
2008-08-20
Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra) in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral reef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives.
Work, Thierry M.; Aeby, Greta S.; Maragos, James E.
2008-01-01
Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra) in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral reef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives. PMID:18714355
Energy Technology Data Exchange (ETDEWEB)
Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Kim, Tae Hyun [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Jankowska-Sumara, Irena [Institute of Physics, Pedagogical University, ul. Podchorążych 2, 30-084 Kraków (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Kojima, Seiji [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)
2015-02-15
Highlights: • Phase transition mechanisms were studied in antiferroelectric PbHf{sub 0.975}Sn{sub 0.025}O{sub 3.} • Acoustic phonons showed anomalies at 472 and 426 K due to phase transitions. • Brillouin data showed evidence for presence of polar clusters in paraelectric phase. • An order-disorder mechanism of the PE to AFE2 transition was proved. - Abstract: Specific heat, dielectric, powder X-ray diffraction and Brillouin scattering studies of phase transitions in antiferroelectric PbHf{sub 0.975}Sn{sub 0.025}O{sub 3} crystal were performed. The specific heat data revealed clear anomalies at T{sub 1} = 473.5 and T{sub 2} = 426.3 K on cooling, which could be attributed to onset of first order phase transitions from the paraelectric (PE) phase to an intermediate antiferroelectric phase (AFE2) and the AFE2 phase to another antiferroelectric phase (AFE1), respectively. The estimated entropy changes at T{sub 1} and T{sub 2} pointed to mainly an order-disorder and displacive character of these transitions, respectively. X-ray diffraction data showed a complex superstructure of the intermediate phase with a = 11.895(6) Å, b = 11.936(4) Å, c = 8.223(3) Å at 453 K. Brillouin studies revealed pronounced softening of longitudinal acoustic (LA) mode in the PE phase associated with its broadening. The broadening and softening exhibited maximum values at T{sub 1}. Additional acoustic anomalies, that is, abrupt frequency shifts for LA and transverse acoustic (TA) modes were also observed at T{sub 2}. Brillouin scattering data also showed presence of a broad central peak (CP) that exhibited highest intensity at T{sub 1}. The observed temperature dependences of acoustic modes and CP indicate order-disorder character of the FE to AFE2 phase transition and importance of polar precursor clusters in the PE phase. The obtained data also suggest that the intermediate antiferroelectric phases in Sn{sup 4+} doped PbHfO{sub 3} and PbZrO{sub 3} may have very similar structures
Plug-and-play round-robin differential phase-shift quantum key distribution.
Mao, Qian-Ping; Wang, Le; Zhao, Sheng-Mei
2017-11-13
The round-robin differential-phase-shift quantum key distribution (RRDPS-QKD) protocol could provide an effective way to estimate the leakage information without monitoring the signal disturbance. Moreover, the self-compensating property of plug-and-play (P&P) setup can eliminate the variations of phase or polarization in QKD procedure. In the paper, we introduce the P&P concept into RRDPS-QKD, and propose a QKD protocol, named P&P RRDPS-QKD protocol, to make the RRDPS-QKD scheme more practical. We analyze the security, and discuss the key generation rate with infinite-intensity decoy state method. The results show that the proposed protocol is a good solution to RRDPS-QKD protocol with untrusted sources. It has a high security and its key generation rate could be as good as the protocol with trusted sources when the average input photon number N is greater than 10(6). In addition, the proposed protocol has a high noise tolerance in comparison with P&P BB84-QKD protocol.
Retrieval of Gap Fraction and Effective Plant Area Index from Phase-Shift Terrestrial Laser Scans
Directory of Open Access Journals (Sweden)
Pyare Pueschel
2014-03-01
Full Text Available The characterization of canopy structure is crucial for modeling eco-physiological processes. Two commonly used metrics for characterizing canopy structure are the gap fraction and the effective Plant Area Index (PAIe. Both have been successfully retrieved with terrestrial laser scanning. However, a systematic assessment of the influence of the laser scan properties on the retrieval of these metrics is still lacking. This study investigated the effects of resolution, measurement speed, and noise compression on the retrieval of gap fraction and PAIe from phase-shift FARO Photon 120 laser scans. We demonstrate that FARO’s noise compression yields gap fractions and PAIe that deviate significantly from those based on scans without noise compression and strongly overestimate Leaf Area Index (LAI estimates based on litter trap measurements. Scan resolution and measurement speed were also shown to impact gap fraction and PAIe, but this depended on leaf development phase, stand structure, and LAI calculation method. Nevertheless, PAIe estimates based on various scan parameter combinations without noise compression proved to be quite stable.
Liu, Qian; Yuan, Daocheng; He, Huabin
2017-11-01
The sensitivity of phase-shifting interferometers (PSIs) to vibration impairs their application in unsteady environment. Iterative algorithms were developed to desensitise the effect of vibration on PSIs, but their desensitising capability is restricted by the estimated initial value. In this paper, a spatial carrier-assisted method is proposed, in which a wavefront phase retrieved from an additional spatial-carrier interferogram is used as the initial value. Because of the benefits of spatial carrier, vibration immunity and sign determination, iteration could converge to accurate value even when interferometers are under severe vibration. To reduce the possibility of transverse movement of the measured surface, subsampling strategy is further proposed to decrease the required tilt angle, with the additional benefit of decreasing the calculation time of iteration. Computer simulations and experiments are performed to verify the effectiveness of the proposed method. Results indicate that the vibration desensitising capability of an iterative algorithm is significantly enhanced by the proposed method. The proposed method improves the vibration desensitising capability with low cost and is thus highly compatible.
Yan, Bing-Nan; Liu, Chong-Xin; Ni, Jun-Kang; Zhao, Liang
2016-10-01
In order to grasp the downhole situation immediately, logging while drilling (LWD) technology is adopted. One of the LWD technologies, called acoustic telemetry, can be successfully applied to modern drilling. It is critical for acoustic telemetry technology that the signal is successfully transmitted to the ground. In this paper, binary phase shift keying (BPSK) is used to modulate carrier waves for the transmission and a new BPSK demodulation scheme based on Duffing chaos is investigated. Firstly, a high-order system is given in order to enhance the signal detection capability and it is realized through building a virtual circuit using an electronic workbench (EWB). Secondly, a new BPSK demodulation scheme is proposed based on the intermittent chaos phenomena of the new Duffing system. Finally, a system variable crossing zero-point equidistance method is proposed to obtain the phase difference between the system and the BPSK signal. Then it is determined that the digital signal transmitted from the bottom of the well is ‘0’ or ‘1’. The simulation results show that the demodulation method is feasible. Project supported by the National Natural Science Foundation of China (Grant No. 51177117) and the National Key Science & Technology Special Projects, China (Grant No. 2011ZX05021-005).
The Interplay of Symmetry and Scattering Phase in Second Harmonic Generation from Gold Nanoantennas.
Gennaro, Sylvain D; Rahmani, Mohsen; Giannini, Vincenzo; Aouani, Heykel; Sidiropoulos, Themistoklis P H; Navarro-Cía, Miguel; Maier, Stefan A; Oulton, Rupert F
2016-08-10
Nonlinear phenomena are central to modern photonics but, being inherently weak, typically require gradual accumulation over several millimeters. For example, second harmonic generation (SHG) is typically achieved in thick transparent nonlinear crystals by phase-matching energy exchange between light at initial, ω, and final, 2ω, frequencies. Recently, metamaterials imbued with artificial nonlinearity from their constituent nanoantennas have generated excitement by opening the possibility of wavelength-scale nonlinear optics. However, the selection rules of SHG typically prevent dipole emission from simple nanoantennas, which has led to much discussion concerning the best geometries, for example, those breaking centro-symmetry or incorporating resonances at multiple harmonics. In this work, we explore the use of both nanoantenna symmetry and multiple harmonics to control the strength, polarization and radiation pattern of SHG from a variety of antenna configurations incorporating simple resonant elements tuned to light at both ω and 2ω. We use a microscopic description of the scattering strength and phases of these constituent particles, determined by their relative positions, to accurately predict the SHG radiation observed in our experiments. We find that the 2ω particles radiate dipolar SHG by near-field coupling to the ω particle, which radiates SHG as a quadrupole. Consequently, strong linearly polarized dipolar SHG is only possible for noncentro-symmetric antennas that also minimize interference between their dipolar and quadrupolar responses. Metamaterials with such intra-antenna phase and polarization control could enable compact nonlinear photonic nanotechnologies.
Liu, Han-Chun; Samaraweera, Rasanga L.; Reichl, C.; Wegscheider, W.; Mani, R. G.
2017-06-01
We report the evolution of the phase shift, θ 0, extracted from traces of the diagonal resistance, Rxx , vs. the linear polarization angle, θ, at oscillatory extrema of the microwave radiation induced magnetoresistance oscillations over the 36 ≤ f ≤ 40 GHz band in GaAs/AlGaAs system. A reference phase shift for the linear polarization angle in the vicinity of the specimen is obtained with the help of a sensitive carbon resistor. We fit an empirical cosine square law to the sinusoidal responses of Rxx vs. θ to extract the phase shift θ 0. The quasi-continuous variation θ 0 vs. f trace suggests a preferable polarization orientation for the specimen, and the f- and B- independence of overall average of θ 0.
Dupont-Nivet, M.; Westbrook, C. I.; Schwartz, S.
2016-11-01
We report a theoretical study of a double-well Ramsey interferometer using internal state labelling. We consider the use of a thermal ensemble of cold atoms rather than a Bose-Einstein condensate to minimise the effects of atomic interactions. To maintain a satisfactory level of coherence in this case, a high degree of symmetry is required between the two arms of the interferometer. Assuming that the splitting and recombination processes are adiabatic, we theoretically derive the phase-shift and the contrast of such an interferometer in the presence of a gravity or an acceleration field. We also consider using a ‘shortcut to adiabaticity’ protocol to speed up the splitting process and discuss how such a procedure affects the phase shift and contrast. We find that the two procedures lead to phase-shifts of the same form.
Directory of Open Access Journals (Sweden)
M. S. Lehtinen
2004-04-01
Full Text Available This paper presents binary phase codes and corresponding decoding filters which are optimal in the sense that they produce no sidelobes and they maximise the signal-to-noise ratio (SNR henceforth. The search is made by investigating all possible binary phase codes with a given length. After selecting the code, the first step is to find a filter which produces no sidelobes. This is possible for all codes with no zeros in the frequency domain, and it turns out that most codes satisfy this requirement. An example of a code which cannot be decoded in this way is a code with a single phase, i.e. a long pulse. The second step is to investigate the SNR performance of the codes. Then the optimal code of a given length is the one with the highest SNR at the filter output. All codes with lengths of 3–25 bits were studied, which means investigating 33554428 binary phase codes. It turns out that all Barker codes except the 11-bit code are optimal in the above sense. It is well known that the performance of matched-filter decoding of Barker codes is better than decoding without sidelobes. In the case of the 7-bit Barker code, it is shown here that the SNR given by sidelobe-free decoding is nearly 30% worse than that of standard decoding, but for the 13-bit code sidelobe-free decoding is only about 5% worse. The deterioration of SNR should be evaluated against the benefits gained in disposing of the sidelobes, which, even for the 13-bit code, contribute by 7.1% to the total signal power from a homogeneous target. Thus, regions of weak scattering can be contaminated by the sidelobes from neighbouring layers of strong scattering, causing broadening of thin spatial structures and giving a lower spatial resolution than implied by the bit length. A practical example is shown where sidelobes mask a weak signal when the standard matched filter is used in the analysis. An improvement is achieved when sidelobe-free filtering is carried out.
Key words. Radio
Srinivasan, K; Senthilkumar, D V; Raja Mohamed, I; Murali, K; Lakshmanan, M; Kurths, J
2012-06-01
We construct a new RC phase shift network based Chua's circuit, which exhibits a period-doubling bifurcation route to chaos. Using coupled versions of such a phase-shift network based Chua's oscillators, we describe a new method for achieving complete synchronization (CS), approximate lag synchronization (LS), and approximate anticipating synchronization (AS) without delay or parameter mismatch. Employing the Pecora and Carroll approach, chaos synchronization is achieved in coupled chaotic oscillators, where the drive system variables control the response system. As a result, AS or LS or CS is demonstrated without using a variable delay line both experimentally and numerically.
A Double Phase-Shift Control Strategy for A Full-Bridge Three-Level DC/DC Converter
DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Gong, Zheng
2016-01-01
In this paper, a double phase-shift control strategy is proposed for the full-bridge three-level (FBTL) DC/DC converter applied into DC distribution systems with the medium DC bus voltage. By utilizing the proposed control strategy, the voltage change rate dv/dt and voltage stress of the transfor......In this paper, a double phase-shift control strategy is proposed for the full-bridge three-level (FBTL) DC/DC converter applied into DC distribution systems with the medium DC bus voltage. By utilizing the proposed control strategy, the voltage change rate dv/dt and voltage stress...
Zhang, Siyuan; Cui, Zhiwei; Xu, Tianqi; Liu, Pan; Li, Dapeng; Shang, Shaoqiang; Xu, Ranxiang; Zong, Yujin; Niu, Gang; Wang, Supin; He, Xijing; Wan, Mingxi
2017-01-01
This paper compared the effects of flowing phase-shift nanodroplets (NDs) and lipid-shelled microbubbles (MBs) on subsequent cavitation during focused ultrasound (FUS) exposures. The cavitation activity was monitored using a passive cavitation detection method as solutions of either phase-shift NDs or lipid-shelled MBs flowed at varying velocities through a 5-mm diameter wall-less vessel in a transparent tissue-mimicking phantom when exposed to FUS. The intensity of cavitation for the phase-shift NDs showed an upward trend with time and cavitation for the lipid-shelled MBs grew to a maximum at the outset of the FUS exposure followed by a trend of decreases when they were static in the vessel. Meanwhile, the increase of cavitation for the phase-shift NDs and decrease of cavitation for the lipid-shelled MBs had slowed down when they flowed through the vessel. During two discrete identical FUS exposures, while the normalized inertial cavitation dose (ICD) value for the lipid-shelled MB solution was higher than that for the saline in the first exposure (p-value phase-shift NDs, the normalized ICD was 0.71 in the first exposure and increased to 0.97 in the second exposure. At a low acoustic power, the normalized ICD values for the lipid-shelled MBs tended to increase with increasing velocities from 5 to 30cm/s (r>0.95). Meanwhile, the normalized ICD value for the phase-shift NDs was 0.182 at a flow velocity of 5cm/s and increased to 0.188 at a flow velocity of 15cm/s. As the flow velocity increased to 20cm/s, the normalized ICD was 0.185 and decreased to 0.178 at a flow velocity of 30cm/s. At high acoustic power, the normalized ICD values for both the lipid-shelled MBs and the phase-shift NDs increased with increasing flow velocities from 5 to 30cm/s (r>0.95). The effects of the flowing phase-shift NDs vaporized into gas bubbles as cavitation nuclei on the subsequent cavitation were inverse to those of the flowing lipid-shelled MBs destroyed after focused ultrasound
Rivera-Ortega, Uriel; Pico-Gonzalez, Beatriz
2016-01-01
In this manuscript an algorithm based on a graphic user interface (GUI) designed in MATLAB for an automatic phase-shifting estimation between two digitalized interferograms is presented. The proposed algorithm finds the midpoint locus of the dark and bright interference fringes in two skeletonized fringe patterns and relates their displacements with the corresponding phase-shift. In order to demonstrate the usefulness of the proposed GUI, its application to simulated and experimental interference patterns will be shown. The viability of this GUI makes it a helpful and easy-to-use computational tool for educational or research purposes in optical phenomena for undergraduate or graduate studies in the field of physics.
Seagraves, Kelly M; Hedwig, Berthold
2014-07-01
The cricket's auditory system is a highly directional pressure difference receiver whose function is hypothesised to depend on phase relationships between the sound waves propagating through the auditory trachea that connects the left and right hearing organs. We tested this hypothesis by measuring the effect of experimentally constructed phase shifts in acoustic stimuli on phonotactic behavior of Gryllus bimaculatus, the oscillatory response patterns of the tympanic membrane, and the activity of the auditory afferents. The same artificial calling song was played simultaneously at the left and right sides of the cricket, but one sound pattern was shifted in phase by 90 deg (carrier frequencies between 3.6 and 5.4 kHz). All three levels of auditory processing are sensitive to experimentally induced acoustic phase shifts, and the response characteristics are dependent on the carrier frequency of the sound stimulus. At lower frequencies, crickets steered away from the sound leading in phase, while tympanic membrane vibrations and auditory afferent responses were smaller when the ipsilateral sound was leading. In contrast, opposite responses were observed at higher frequencies in all three levels of auditory processing. Minimal responses occurred near the carrier frequency of the cricket's calling song, suggesting a stability at this frequency. Our results indicate that crickets may use directional cues arising from phase shifts in acoustic signals for sound localisation, and that the response properties of pressure difference receivers may be analysed with phase-shifted sound stimuli to further our understanding of how insect auditory systems are adapted for directional processing. © 2014. Published by The Company of Biologists Ltd.
S-matrix formulation of thermodynamics with N-body scatterings
Lo, Pok Man
2017-08-01
We apply a phase space expansion scheme to incorporate the N-body scattering processes in the S-matrix formulation of statistical mechanics. A generalized phase shift function suitable for studying the thermal contribution of N → N processes is motivated and examined in various models. Using the expansion scheme, we revisit how the hadron resonance gas model emerges from the S-matrix framework, and consider an example of structureless scattering in which the phase shift function can be exactly worked out. Finally we analyze the influence of dynamics on the phase shift function in a simple example of 3- and 4-body scattering.
S-matrix formulation of thermodynamics with N-body scatterings
Energy Technology Data Exchange (ETDEWEB)
Lo, Pok Man [University of Wroclaw, Institute of Theoretical Physics, Wroclaw (Poland); Extreme Matter Institute EMMI, GSI, Darmstadt (Germany)
2017-08-15
We apply a phase space expansion scheme to incorporate the N-body scattering processes in the S-matrix formulation of statistical mechanics. A generalized phase shift function suitable for studying the thermal contribution of N → N processes is motivated and examined in various models. Using the expansion scheme, we revisit how the hadron resonance gas model emerges from the S-matrix framework, and consider an example of structureless scattering in which the phase shift function can be exactly worked out. Finally we analyze the influence of dynamics on the phase shift function in a simple example of 3- and 4-body scattering. (orig.)
Sakamoto, Katsuhiko; Kadota, Koji; Oishi, Katsutaka
2004-10-01
In the present study, we investigated the effect of fasting on photoentrainment of the peripheral circadian oscillator in the mammalian heart. Northern blotting showed that a single light pulse applied at an appropriate time in constant darkness, caused obvious phase-shifting in the circadian expression rhythm of the mammalian clock gene Period2 (mPer2) even in the hearts of food-deprived mice. Fasting did not significantly affect either the phase or the light-induced phase-shifts of the mPer2 rhythm. Although several studies of temporal feeding restriction have indicated that feeding is the dominant timing cue for mammalian peripheral oscillators, our findings suggest that feeding is not essential for mammals to induce phase resetting of the circadian oscillator in the heart.
Leonard, Heidi; Halachmi, Sarel; Ben-Dov, Nadav; Nativ, Ofer; Segal, Ester
2017-06-27
With global antimicrobial resistance becoming increasingly detrimental to society, improving current clinical antimicrobial susceptibility testing (AST) is crucial to allow physicians to initiate appropriate antibiotic treatment as early as possible, reducing not only mortality rates but also the emergence of resistant pathogens. In this work, we tackle the main bottlenecks in clinical AST by designing biofunctionalized silicon micropillar arrays to provide both a preferable solid-liquid interface for bacteria networking and a simultaneous transducing element that monitors the response of bacteria when exposed to chosen antibiotics in real time. We harness the intrinsic ability of the micropillar architectures to relay optical phase-shift reflectometric interference spectroscopic measurements (referred to as PRISM) and employ it as a platform for culture-free, label-free phenotypic AST. The responses of E. coli to various concentrations of five clinically relevant antibiotics are optically tracked by PRISM, allowing for the minimum inhibitory concentration (MIC) values to be determined and compared to both standard broth microdilution testing and clinic-based automated AST system readouts. Capture of bacteria within these microtopologies, followed by incubation of the cells with the appropriate antibiotic solution, yields rapid determinations of antibiotic susceptibility. This platform not only provides accurate MIC determinations in a rapid manner (total assay time of 2-3 h versus 8 h with automated AST systems) but can also be employed as an advantageous method to differentiate bacteriostatic and bactericidal antibiotics.
Dimario, Matthew; Becerra, Francisco; Jackson, Richard; Carrasco, Zeke
2017-04-01
Non-Gaussian receivers that achieve discrimination errors below the Quantum Noise Limit (QNL) are an important tool in communication and quantum information. Discrimination of coherent states of light with zero probability of error is fundamentally impossible due to their intrinsic overlap. Therefore, the goal is to design and demonstrate strategies that minimize the probability of error and outperform a perfect heterodyne measurement working at the QNL, while being compatible with current communication technologies. We experimentally implement a strategy proposed in to discriminate between quaternary phase-shift keyed (QPSK) coherent states below the QNL that is based on simultaneously testing multiple hypotheses within a single-shot measurement. The receiver uses displacement operations and single photon counting without the need for any feedback operations and thus it is compatible with current high-bandwidth communications. In our demonstration we use optimized displacement operations to minimize the probability of error in a polarization based set-up. Our investigations allow us to identify how the critical parameters, such as visibility of the displacements and detection efficiency, influence the error probability as well as what is required to out-perform a heterodyne measurement under realistic noise and loss.
Liotard, Arnaud; Muratet, Sylvaine; Zamkotsian, Fr‰d.‰ric; Fourniols, Jean-Yves
2005-01-01
Since micro deformable mirrors based on Micro-Opto-Electronico-Mechanical Systems (MOEMS) technology would be essential in next generation adaptive optics system, we are designing, realizing, characterizing and modeling this key-component. Actuators and a continuous-membrane micro deformable mirror (3*3 actuators, 600*600 μm2) have been designed in-house and processed by surface micromachining in the Cronos foundry. A dedicated characterization bench has been developed for the complete analysis. This Twyman-Green interferometer allows high in-plane resolution (4 μm) or large field of view (40mm). Out-of-plane measurements are performed with phase-shifting interferometry showing highly repeatable results (standard deviation<5nm). Features such as optical quality or electro-mechanical behavior are extracted from these high precision three-dimensional component maps and FEM can be fitted. Dynamic analysis like vibration mode and cut-off frequency is realized with time-averaged interferometer. The deformable mirror exhibit a 350nm stroke for 35 volts on the central actuator. This limited stroke could be overcome by changing the components material and promising actuators are made with polymers.
Modeling effects of climate change and phase shifts on detrital production of a kelp bed.
Krumhansl, Kira A; Lauzon-Guay, Jean-Sébastien; Scheibling, Robert E
2014-03-01
The exchange of energy and nutrients between ecosystems (i.e., resource subsidies) plays a central role in ecological dynamics over a range of spatial and temporal scales. Little attention has been paid to the role of anthropogenic impacts on natural systems in altering the magnitude, timing, and quality of resource subsidies. Kelp ecosystems are highly productive on a local scale and export over 80% of kelp primary production as detritus, subsidizing consumers across broad spatial scales. Here, we generate a model of detrital production from a kelp bed in Nova Scotia to hindcast trends in detrital production based on temperature and wave height recorded in the study region from 1976 to 2009, and to project changes in detrital production that may result from future climate change. Historical and projected increases in temperature and wave height led to higher rates of detrital production through increased blade breakage and kelp dislodgment from the substratum, but this reduced kelp biomass and led to a decline in detrital production in the long-term. We also used the model to demonstrate that the phase shift from a highly productive kelp bed to a low-productivity barrens, driven by the grazing activity of sea urchins, reduces kelp detrital production by several orders of magnitude, an effect that would be exacerbated by projected increases in temperature and wave action. These results indicate that climate-mediated changes in ecological dynamics operating on local scales may alter the magnitude of resource subsidies to adjacent ecosystems, affecting ecological dynamics on regional scales.
Round-robin differential-phase-shift quantum key distribution with a passive decoy state method.
Liu, Li; Guo, Fen-Zhuo; Qin, Su-Juan; Wen, Qiao-Yan
2017-02-13
Recently, a new type of protocol named Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) was proposed, where the security can be guaranteed without monitoring conventional signal disturbances. The active decoy state method can be used in this protocol to overcome the imperfections of the source. But, it may lead to side channel attacks and break the security of QKD systems. In this paper, we apply the passive decoy state method to the RRDPS QKD protocol. Not only can the more environment disturbance be tolerated, but in addition it can overcome side channel attacks on the sources. Importantly, we derive a new key generation rate formula for our RRDPS protocol using passive decoy states and enhance the key generation rate. We also compare the performance of our RRDPS QKD to that using the active decoy state method and the original RRDPS QKD without any decoy states. From numerical simulations, the performance improvement of the RRDPS QKD by our new method can be seen.
Primary processes in e-beam and laser lithographies for phase-shift mask manufacturing II
Kurihara, Masa-aki; Arai, Masumi; Fujita, Hiroshi; Moro-oka, Hisashi; Takahashi, Yoichi; Sano, Hisatake
1993-03-01
Two lithographic processes for phase-shift mask (PSM) manufacturing have been investigated. In particular, processes in E-beam (electron beam) lithography by use of a charge-dissipating layer of a conductive polymer are studied. Two commercial conductive polymers, TQV and ESPACER100, are found to work well for charge-dissipation. Three new resists along with CMS and EBR9 are evaluated regarding their properties necessary for patterning a shifter layer. Among them two new resists are demonstrated to be excellent. The effect of the number of data-blocks on the alignment accuracy is examined in delineation with a Hitachi HL-600, where each data-block has four fine-alignment marks. The examination suggests that the use of one or two data-blocks is practical. As to combination of writers for the Cr level and the shifter level, HL-600 - HL-600 gave better alignment accuracy than the other combinations, WW6000 - HL-600 and MEBES III - HL-600, did. The comparison between the E-beam and the laser writers is summarized.
Nonlinear detection for a high rate extended binary phase shift keying system.
Chen, Xian-Qing; Wu, Le-Nan
2013-03-28
The algorithm and the results of a nonlinear detector using a machine learning technique called support vector machine (SVM) on an efficient modulation system with high data rate and low energy consumption is presented in this paper. Simulation results showed that the performance achieved by the SVM detector is comparable to that of a conventional threshold decision (TD) detector. The two detectors detect the received signals together with the special impacting filter (SIF) that can improve the energy utilization efficiency. However, unlike the TD detector, the SVM detector concentrates not only on reducing the BER of the detector, but also on providing accurate posterior probability estimates (PPEs), which can be used as soft-inputs of the LDPC decoder. The complexity of this detector is considered in this paper by using four features and simplifying the decision function. In addition, a bandwidth efficient transmission is analyzed with both SVM and TD detector. The SVM detector is more robust to sampling rate than TD detector. We find that the SVM is suitable for extended binary phase shift keying (EBPSK) signal detection and can provide accurate posterior probability for LDPC decoding.
Nonlinear Detection for a High Rate Extended Binary Phase Shift Keying System
Directory of Open Access Journals (Sweden)
Le-Nan Wu
2013-03-01
Full Text Available The algorithm and the results of a nonlinear detector using a machine learning technique called support vector machine (SVM on an efficient modulation system with high data rate and low energy consumption is presented in this paper. Simulation results showed that the performance achieved by the SVM detector is comparable to that of a conventional threshold decision (TD detector. The two detectors detect the received signals together with the special impacting filter (SIF that can improve the energy utilization efficiency. However, unlike the TD detector, the SVM detector concentrates not only on reducing the BER of the detector, but also on providing accurate posterior probability estimates (PPEs, which can be used as soft-inputs of the LDPC decoder. The complexity of this detector is considered in this paper by using four features and simplifying the decision function. In addition, a bandwidth efficient transmission is analyzed with both SVM and TD detector. The SVM detector is more robust to sampling rate than TD detector. We find that the SVM is suitable for extended binary phase shift keying (EBPSK signal detection and can provide accurate posterior probability for LDPC decoding.
Energy Technology Data Exchange (ETDEWEB)
Whicker, Jeffrey J [Los Alamos National Laboratory; Field, Jason P [UNIV OF ARIZONA; Breshears, David D [UNIV OF ARIZONA
2008-01-01
Aeolian processes are a fundamental driver of earth surface dynamics, yet the importance of aeolian processes in a broader geosciences context may be overshadowed by an unbalanced emphasis on fluvial processes. Here we wish to highlight that aeolian and fluvial processes need to be considered in concert relative to total erosion and to potential interactions, that relative dominance and sensitivity to disturbance vary with mean annual precipitation, and that there are important scale-dependencies associated with aeolian-fluvial interactions. We build on previous literature to present relevant conceptual syntheses highlighting these issues. We then highlight the relative investments that have been made in aeolian research on dust emission and management relative to that in fluvial research on sediment production. Literature searches highlight that aeolian processes are greatly understudied relative to fluvial processes when considering total erosion in different environmental settings. Notably, within the USA, aeolian research was triggered by the Dust Bowl catastrophe of the 1930s, but the resultant research agencies have shifted to almost completely focusing on fluvial processes, based on number of remaining research stations and on monetary investments in control measures. However, numerous research issues associated with intensification of land use and climate change impacts require a rapid ramping up in aeolian research that improves information about aeolian processes relative to fluvial processes, which could herald a post-Dust Bowl Phoenix phase in which aeolian processes are recognized as broadly critical to geo- and environmental sciences.
Wood, Ezra C; Charest, John R
2014-10-21
We describe a new instrument for the quantification of atmospheric peroxy radicals (HO2, CH3O2, C2H5O2, etc.) using the chemical amplification method. Peroxy radicals are mixed with high concentrations of NO and CO, causing a chain reaction that produces a measurable increase in NO2 which is quantified by cavity attenuated phase shift (CAPS) spectroscopy, a highly sensitive spectroscopic detection technique. The instrument utilizes two identical reaction chambers, each with a dedicated CAPS NO2 sensor. Similar to all dual-channel chemical amplifiers, one reaction chamber operates in amplification or "ROx" mode and the other in background or "Ox" mode. The peroxy radical mixing ratio is determined by the difference between the two channels' NO2 readings divided by a laboratory-determined chain length. Each reaction chamber alternates between ROx and Ox mode on an anti-synchronized schedule, eliminating the effect of CAPS baseline offsets on the calculated peroxy radical concentrations. The chain length is determined by a new calibration method: peroxyacetyl and methyl peroxy radicals are produced by the photolysis of acetone and quantified as NO2 following reaction with excess NO. We demonstrate the performance of the instrument with results from ambient sampling in Amherst and several diagnostics of its precision. The detection limit while sampling ambient air at a relative humidity (RH) of 40% is 0.6 ppt (1 min average, signal-to-noise ratio =2), with an estimated accuracy of 25% (2σ).
A binary phase-shift keying receiver for the detection of attention to human speech.
Lopez-Gordo, M A; Pelayo, F
2013-08-01
Synthetic sounds, tone-beeps, vowels or syllables are typically used in the assessment of attention to auditory stimuli because they evoke a set of well-known event-related potentials, whose characteristics can be statistically contrasted. Such approach rules out the use of stimuli with non-predictable response, such as human speech. In this study we present a procedure based on the robust binary phase-shift keying (BPSK) receiver that permits the real-time detection of selective attention to human speeches in dichotic listening tasks. The goal was achieved by tagging the speeches with two barely-audible tags whose joined EEG response constitutes a reliable BPSK constellation, which can be detected by means of a BPSK receiver. The results confirmed the expected generation of the BPSK constellation by the human auditory system. Also, the bit-error rate and the information transmission rate achieved in the detection of attention fairly followed the expected curves and equations of the standard BPSK receiver. Actually, it was possible to detect attention as well as the estimation a priori of its accuracy based on the signal-to-noise ratio of the BPSK signals. This procedure, which permits the detection of the attention to human speeches, can be of interest for new potential applications, such as brain-computer interfaces, clinical assessment of the attention in real time or for entertainment.
Analysis of a shearography device using a Wollaston prism and polarization phase shifting
Sanchez, E.; Benedet, M. E.; Willemann, D. P.; Fantin, A. V.; Albertazzi, A. G.
2016-08-01
Speckle shear interferometry, or shearography, has been more and more frequently used in the industry for in-field nondestructive inspections of flaws in composite materials used in the aerospace and oil and gas industry. Nowadays new applications has emerged demanding the ability to operate in harsher environments. Bringing interferometric systems to harsh environments is not an easy task since they are very sensitive to many harsh environmental factors. Due to the quasi-equal-path property, shearography is an intrinsically robust interferometric technique that has been successfully used in the field, but there are still limits to overcome. Mechanical vibrations are probably the most challenging factor to cope in the field measurements. This work presents a potentially robust shear interferometer configuration. It uses a Wollaston prism as the shearing element rather than a traditional Michelson interferometer and polarizers to achieve the phase shift. The use of the Wollaston prism makes the optical setup more compact and robust, given that a rotating polarizer is the only movable part of the interferometer.
Scattering cross section for various potential systems
Directory of Open Access Journals (Sweden)
Myagmarjav Odsuren
2017-08-01
Full Text Available We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.
Scattering cross section for various potential systems
Energy Technology Data Exchange (ETDEWEB)
Odsuren, Myagmarjav; Khuukhenkhuu, Gonchigdorj; Davaa, Suren [Nuclear Research Center, School of Engineering and Applied Sciences, National University of Mongolia, Ulaanbaatar (Mongolia); Kato, Kiyoshi [Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University, Sapporo (Japan)
2017-08-15
We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.
Modified Two-core Phase-shifting Transformer Based on the Classical «Delta Connection» Scheme
Directory of Open Access Journals (Sweden)
Golub I.V.
2016-04-01
Full Text Available Nowadays, in joined power systems increases the role and significance of phase-shifting devices, which are used in the quality of FACTS-controllers (Flexible Alternative Current Transmission System, allowing solving various problems of modes management in a complex-closed inhomogeneous network. A modified version of the two-transformer circuit phase-adjusting device, built based on the classical single-transformer scheme «Delta Connection» has been studied in the paper. The proposed device’s topology differs from the classical of single-transformer one so that the control coil is supplied by a lower voltage than phase level, which in turn makes it possible to use it in high rated voltage networks. A mathematical model of the device, which describes the change of parameters of operation mode of phase-shifting transformer under the adjusting of the phase-shifting angle, has been provided. The achieved results can be used for comparative analysis when determining the technical and economic efficiency in the deal of further development of phase rotating devices of transformer type.
Venkatasubba Rao, Chethan P; Bershad, Eric M; Calvillo, Eusebia; Maldonado, Nelson; Damani, Rahul; Mandayam, Sreedhar; Suarez, Jose I
2017-05-25
Cerebral edema, which is associated with increased intracranial fluid, is often a complication of many acute neurological conditions. There is currently no accepted method for real-time monitoring of intracranial fluid volume at the bedside. We evaluated a novel noninvasive technique called "Volumetric Integral Phase-shift Spectroscopy (VIPS)" for detecting intracranial fluid shifts during hemodialysis. Subjects receiving scheduled hemodialysis for end-stage renal disease and without a history of major neurological conditions were enrolled. VIPS monitoring was performed during hemodialysis. Serum osmolarity, electrolytes, and cognitive function with mini-mental state examination (MMSE) were assessed. Twenty-one monitoring sessions from 14 subjects (4 women), mean group age 50 (SD 12.6), were analyzed. The serum osmolarity decreased by a mean of 6.4 mOsm/L (SD 6.6) from pre- to post-dialysis and correlated with an increase in the VIPS edema index (E-Dex) of 9.7% (SD 12.9) (Pearson's correlation r = 0.46, p = 0.037). Of the individual determinants of serum osmolarity, changes in serum sodium level correlated best with the VIPS edema index (Pearson's correlation, r = 0.46, p = 0.034). MMSE scores did not change from pre- to post-dialysis. We detected an increase in the VIPS edema index during hemodialysis that correlated with decreased serum osmolarity, mainly reflected by changes in serum sodium suggesting shifts in intracranial fluids.
Jabbari, M.
2017-06-01
In this article we proposed a new model based on carbon-nanotube quantum dot (CNT QD) nanostructure for controlling the Goos-Hänchen (GH) shifts in reflected and transmitted light beams. In our calculation we introduce the spin-orbit coupling parameter in the CNT QD nanostructure. Our results show that owing to the presence of spin-orbit coupling, Rabi frequency of magnetic field, coupling laser field and relative phase between applied fields, the enhanced GH shifts in reflected and transmitted light beams can be achieved. Moreover, we demonstrate that such enhanced GH shifts are simultaneously obtained for both reflected and transmitted light beams. At the end, we discuss the impact of intracavity thickness on the GH shift properties of reflected and transmitted light beams. We hope that our proposed model may be used for future developments based on CNT QD nanostructures.
DEFF Research Database (Denmark)
Behrouzian, Ehsan; Bongiorno, Massimo; Teodorescu, Remus
2014-01-01
The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power that flows in the cells of a chain-link based STATCOM when using Phase-Shifted PWM. Two different cases are investigated for the converter cells: low, and high switching frequency. It is shown...
ASML; Delft University of Technology
2002-01-01
A reflector for EUV has additional multi-layers on the front surface of a base multilayer stack provided selectively to compensate for figure errors in the base multilayer stack or the substrate on which the multilayer stack is provided. A phase shift mask for EUV uses two multilayer stacks, one
DEFF Research Database (Denmark)
Yang, Yongheng; Davari, Pooya; Zare, Firuz
2016-01-01
of a new DC link modulation scheme with a phase-shifted current control enabled by the SCR. The DC-link current modulation scheme is implemented by adding and subtracting specific modulation levels, which makes the total currents drawn from the grid “multi-level”, resulting in an improved current quality...
A VHF Interleaved Self-Oscillating Resonant SEPIC Converter with Phase-Shift Burst-Mode Control
DEFF Research Database (Denmark)
Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.
2014-01-01
This paper presents design and implementation of the phase-shift burst-mode control method for interleaved selfoscillating resonant SEPIC converters for LED lighting applications. The proposed control method utilizes delays in the turn-on and turn-off of the power stage and control circuitry...
DEFF Research Database (Denmark)
Zare, Firuz; Davari, Pooya; Blaabjerg, Frede
2017-01-01
In this paper, an electronic phase-shifting strategy has been optimized for a multi-parallel configuration of line-commutated rectifiers with a common dc-bus voltage used in motor drive application. This feature makes the performance of the system independent of the load profile and maximizes its...
Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt
2007-01-01
We show experimental validation of a novel technique to measure optical path length distributions and path length resolved Doppler broadening in turbid media for different reduced scattering coefficients and anisotropies. The technique involves a phase modulated low coherence Mach-Zehnder
DEFF Research Database (Denmark)
Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel
2009-01-01
An increased gain in a fibre-optical parametric amplifier through suppression of stimulated Brillouin scattering is demonstrated by applying a temperature distribution along the fibre for a fixed phase modulation of the pump. The temperature distribution slightly impacts the gain spectrum....
Mégret, P.; Dekker, R.; Wuilpart, M.; Klein, E.J.; Niehusmann, J.; Bette, S.; Staquet, N.; Först, M.; Ondracek, F.; Ctyroky, J.; Usechak, N.; Driessen, A.
2005-01-01
Self Phase Modulation (SPM) and Stimulated Raman Scattering (SRS) in silicon waveguides have been observed and will be discussed theoretically using a modified Nonlinear Schrödinger Equation. The high optical peak powers needed for the experiments were obtained by coupling sub-picosecond (200fs)
Directory of Open Access Journals (Sweden)
Thierry M Work
Full Text Available Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral reef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives.
Hishiki, Keisuke; Li, Hongpu
2013-05-20
A novel approach to calibrate a phase-shift formed in a long-period fiber grating (LPG) is firstly proposed and numerically demonstrated, which is based on the use of either intensity- or wavelength-interrogation technique to the main loss-peak of the phase-shift LPG in the spectrum. Moreover, by using a CO2 laser with high-repetition-rate pulses emission, an equivalent phase-shift is successfully created at middle of the LPG. As an application of the proposed calibration scheme, measurement for the temperature and the refractive index of the ambient solution has been proposed and successfully demonstrated by using a phase-shifted LPG.
Pfurtscheller, Gert; Klobassa, Daniela S; Altstätter, Christof; Bauernfeind, Günther; Neuper, Christa
2011-07-01
One important feature of the baroreflex loop is its strong preference for oscillations around 0.1 Hz. In this study, we investigated heart rate intervals, arterial blood pressure (BP), and prefrontal oxyhemoglobin changes during 5 min rest and during brisk finger movements in 19 healthy subjects. We analyzed the phase coupling around 0.1 Hz between cardiovascular and (de)oxyhemoglobin oscillations, using the cross-spectral method. The analyses revealed phase shifts for slow oscillations in BP and heart rate intervals between -10° and -118° (BP always leading). These phase shifts increased significantly (poxyhemoglobin oscillations was less clear. Only 12 subjects demonstrated a phase coupling (COH(2) ≥ 0.5) between oxyhemoglobin and BP oscillations. This may be explained by an overwhelming proportion of nonlinearity in cardiovascular and hemodynamic systems. The phase shifts between slow cardiovascular and hemodynamic oscillations are relatively stable subject-specific biometric features and could be of interest for person identification in addition to other biometric data. Slow BP-coupled oscillations in prefrontal oxyhemoglobin changes can seriously impair the detection of mentally induced hemodynamic changes in an optical brain-computer interface, a novel nonmuscular communication system. © 2011 IEEE
Burgess, Mark T.; Porter, Tyrone M.
2015-01-01
Localized, targeted delivery of small interfering ribonucleic acid (siRNA) has been the foremost hurdle in the use of siRNA for the treatment of various diseases. Major advances have been achieved in the synthesis of siRNA, which has led to greater target messenger RNA (mRNA) silencing and stability in physiological conditions. Although numerous delivery strategies have shown promise, there are still limited options for targeted delivery and release of siRNA administered systemically. In this in vitro study, phase-shift nanoemulsions (PSNE) were explored as cavitation nuclei to facilitate free siRNA delivery to cancer cells via sonoporation. A cell suspension containing varying amounts of PSNE and siRNA was exposed to 5 MHz pulsed ultrasound at fixed settings (6.2 MPa peak negative pressure, 5 cycle pulses, 250 Hz pulse repetition frequency, and total exposure duration of 100 seconds). Inertial cavitation emissions were detected throughout the exposure using a passive cavitation detector. Successful siRNA delivery was achieved (i.e. > 50% cell uptake) with high viability (> 80% viability). The percentage of cells with siRNA uptake was correlated with the amount of inertial cavitation activity generated from vaporized PSNE. The siRNA remained functional after delivery, significantly reducing expression of green fluorescent protein (GFP) in a stably transfected cell line. These results show that vaporized PSNE can facilitate siRNA entry into the cytosol of a majority of sonicated cells and may provide a non-endosomal route for siRNA delivery. PMID:25979417
Volumetric electromagnetic phase-shift spectroscopy of brain edema and hematoma.
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Cesar A Gonzalez
Full Text Available Motivated by the need of poor and rural Mexico, where the population has limited access to advanced medical technology and services, we have developed a new paradigm for medical diagnostic based on the technology of "Volumetric Electromagnetic Phase Shift Spectroscopy" (VEPS, as an inexpensive partial substitute to medical imaging. VEPS, can detect changes in tissue properties inside the body through non-contact, multi-frequency electromagnetic measurements from the exterior of the body, and thereby provide rapid and inexpensive diagnostics in a way that is amenable for use in economically disadvantaged parts of the world. We describe the technology and report results from a limited pilot study with 46 healthy volunteers and eight patients with CT radiology confirmed brain edema and brain hematoma. Data analysis with a non-parametric statistical Mann-Whitney U test, shows that in the frequency range of from 26 MHz to 39 MHz, VEPS can distinguish non-invasively and without contact, with a statistical significance of p<0.05, between healthy subjects and those with a medical conditions in the brain. In the frequency range of between 153 MHz to 166 MHz it can distinguish with a statistical significance of p<0.05 between subjects with brain edema and those with a hematoma in the brain. A classifier build from measurements in these two frequency ranges can provide instantaneous diagnostic of the medical condition of the brain of a patient, from a single set of measurements. While this is a small-scale pilot study, it illustrates the potential of VEPS to change the paradigm of medical diagnostic of brain injury through a VEPS classifier-based technology. Obviously substantially larger-scale studies are needed to verify and expand on the findings in this small pilot study.
Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma
Gonzalez, Cesar A.; Valencia, Jose A.; Mora, Alfredo; Gonzalez, Fernando; Velasco, Beatriz; Porras, Martin A.; Salgado, Javier; Polo, Salvador M.; Hevia-Montiel, Nidiyare; Cordero, Sergio; Rubinsky, Boris
2013-01-01
Motivated by the need of poor and rural Mexico, where the population has limited access to advanced medical technology and services, we have developed a new paradigm for medical diagnostic based on the technology of “Volumetric Electromagnetic Phase Shift Spectroscopy” (VEPS), as an inexpensive partial substitute to medical imaging. VEPS, can detect changes in tissue properties inside the body through non-contact, multi-frequency electromagnetic measurements from the exterior of the body, and thereby provide rapid and inexpensive diagnostics in a way that is amenable for use in economically disadvantaged parts of the world. We describe the technology and report results from a limited pilot study with 46 healthy volunteers and eight patients with CT radiology confirmed brain edema and brain hematoma. Data analysis with a non-parametric statistical Mann-Whitney U test, shows that in the frequency range of from 26 MHz to 39 MHz, VEPS can distinguish non-invasively and without contact, with a statistical significance of p<0.05, between healthy subjects and those with a medical conditions in the brain. In the frequency range of between 153 MHz to 166 MHz it can distinguish with a statistical significance of p<0.05 between subjects with brain edema and those with a hematoma in the brain. A classifier build from measurements in these two frequency ranges can provide instantaneous diagnostic of the medical condition of the brain of a patient, from a single set of measurements. While this is a small-scale pilot study, it illustrates the potential of VEPS to change the paradigm of medical diagnostic of brain injury through a VEPS classifier-based technology. Obviously substantially larger-scale studies are needed to verify and expand on the findings in this small pilot study. PMID:23691001
Larocque, Hugo; Lu, Ping; Bao, Xiaoyi
2016-04-01
Phase-shift detection in a fast-Fourier-transform (FFT)-based spectrum analysis technique for temperature sensing using a tapered fiber microknot resonator is proposed and demonstrated. Multiple transmission peaks in the FFT spectrum of the device were identified as optical modes having completed different amounts of round trips within the ring structure. Temperature variation induced phase shifts for each set of peaks were characterized, and experimental results show that different peaks have distinct temperature sensitivities reaching values up to -0.542 rad/°C, which is about 10 times greater than that of a regular adiabatic taper Mach-Zehnder interferometer when using similar phase-tracking schemes.
Pal, Mandira; Banerjee, Chitram; Chandel, Shubham; Bag, Ankan; Majumder, Shovan K.; Ghosh, Nirmalya
2016-01-01
Spin orbit interaction and the resulting Spin Hall effect of light are under recent intensive investigations because of their fundamental nature and potential applications. Here, we report an interesting manifestation of spin Hall effect of light and demonstrate its tunability in an inhomogeneous anisotropic medium exhibiting spatially varying retardance level. In our system, the beam shift occurs only for one circular polarization mode keeping the other orthogonal mode unaffected, which is shown to arise due to the combined spatial gradients of the geometric phase and the dynamical phase of light. The constituent two orthogonal circular polarization modes of an input linearly polarized light evolve in different trajectories, eventually manifesting as a large and tunable spin separation. The spin dependent beam shift and the demonstrated principle of simultaneously tailoring space-varying geometric and dynamical phase of light for achieving its tunability (of both magnitude and direction), may provide an attractive route towards development of spin-optical devices. PMID:28004825
Braga, Roberto A.; González-Peña, Rolando J.; Marcon, Marlon; Magalhães, Ricardo R.; Paiva-Almeida, Thiago; Santos, Igor V. A.; Martins, Moisés
2016-12-01
The adoption of digital speckle pattern shearing interferometry, or speckle shearography, is well known in many areas when one needs to measure micro-displacements in-plane and out of the plane in biological and non-biological objects; it is based on the Michelson's Interferometer with the use of a piezoelectric transducer (PZT) in order to provide the phase-shift of the fringes and then to improve the quality of the final image. The creation of the shifting images using a PZT, despite its widespread use, has some drawbacks or limitations, such as the cost of the apparatus, the difficulties in applying the same displacement in the mirror repeated times, and when the phase-shift cannot be used in dynamic object measurement. The aim of this work was to create digitally phase-shift images avoiding the mechanical adjustments of the PZT, testing them with the digital shearography method. The methodology was tested using a well-known object, a cantilever beam of aluminium under deformation. The results documented the ability to create the deformation map and curves with reliability and sensitivity, reducing the cost, and improving the robustness and also the accessibility of digital speckle pattern shearing interferometry.
A small-angle X-ray scattering study of the lyotropic nematic phase of vanadium pentoxide gels
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Davidson, P. [Universite de Paris-Sud, Orsay (France). Lab. de Phys. des Solides; Bourgaux, C.; Sergot, P.; Livage, J.
1997-10-01
Aqueous suspensions of vanadium pentoxide (V{sub 2}O{sub 5}) ribbons, also called Zocher phases, are known to display a lyotropic nematic phase. In this paper, it is shown how the small-angle X-ray scattering (SAXS) technique can provide useful information on the building blocks and their organization in this phase. SAXS experiments were performed either on unoriented samples or on samples aligned by a magnetic field or by shear flow. The scattering is comparable to that of the other classic lyotropic nematic phases displayed by stiff organic rod-like particles such as the tobacco mosaic virus. Scattering studies show that the building blocks have a ribbon shape, that their thickness is 9(1) A and indirectly that their width is several 100 A. Their length is known to be around a few thousand A and therefore could not be measured by SAXS. By following the average distance between the ribbons as a function of concentration, it is shown that the swelling of the phase is one-dimensional at large concentrations and two-dimensional at low concentrations. Finally, estimates of the nematic order parameter of a single domain sample and of samples sheared in a Couette cell have been obtained. (orig.). 24 refs.
Energy Technology Data Exchange (ETDEWEB)
Hamilton, W A; Porcar, L, E-mail: Hamilton.WA@gmail.com
2010-11-01
We report on a small angle neutron scattering (SANS) study of a temperature driven first order phase transition in a 25wt% solution of the surfactant AOT (Sodium Di-2-ethylhexyl Sulfosuccinate) in 1.5wt% heavy brine between an isotropic L{sub 3} 'sponge' state at 27 deg. C and a stacked lamellar L{sub {alpha}} monophase 55 deg. C. The prominent scattering features of these phases are correlation peaks due to the mean passage size of the L{sub 3} sponge and the L{sub {alpha}} stacking separation. This ratio of the monophase peak positions Q{sub {alpha}}/Q{sub 3}{approx}1.3, is consistent with previous observations in this and similar systems. In the present study we tracked this system through the intermediate L{sub 3} +L{sub {alpha}} biphasic miscibility gap. There the initial appearance of the L{sub {alpha}} peak at 33.25 deg. C was at a scattering vector some 23% higher than the final high temperature monophase value. During coexistence both L{sub 3} and L{sub {alpha}} phase peak positions decreased linearly with increasing temperature maintaining a roughly constant ratio Q{sub {alpha}}/Q{sub 3} {approx}1.6-1.7. Two phase fits to the scattering data and application of scaling law predictions allow us to obtain local L{sub 3} phase volume fractions in the biphasic region and make preliminary determinations of the structural accomodations necessitated by phase coexistence in this system's miscibility gap.
Highly anisotropic etching of phase-shift masks using ICP of CF4-SF6-CHF3 gas mixtures
Choi, Se-Jong; Cha, Han-Sun; Yoon, Si-Yeul; Kim, Yong-Dae; Lee, Dong-Hyuk; Kim, Jin-Min; Kim, Jin-Su; Min, Dong-Soo; Jang, Pil-Jin; Chang, Byung-Soo; Kwon, Hyuk-Joo; Choi, Boo-Yeon; Choi, Sang-Soo; Jeong, Soo Hong
2002-07-01
There is considerable interest in phase shift masks as a route to extending the resolution, contrast, and depth of focus of lithographic tools beyond what is achievable with the normal chrome mask technology. A problem that has so far hindered the introduction of phase shift masks has been the difficulty of phase and transmittance control when a phase shift mask is applied to practical use. Also, to apply phase shift layer (MoSiON), it remains that effects several critical mask parameters including sidewall slope, surface roughness, and critical dimension. For these reasons, this process requires a high degree of control of the etch process of shift layer. So in this paper, we described a technique for the fabrication of phase shift masks by etch rate of a MoSiON layer. Etching experiments of MoSiON were performed using different fluorinated gas mixtures. Four of them, CF4/O2/He, SF6/O2/He, CHF3/O2/He and Cl2/CF4/O2/He were chosen for high etch rate, sidewall slope, and surface morphology. Each added gases had a unique property on the etch rate, anisotropy, surface roughness and sidewall morphology. Result indicates that vertical slope and smooth surface are obtained using the Cl2/ CF4/O2/He and SF6/O2/He mixture. With increasing O2 flow rate to the SF6/O2/He Plasma and added Cl2 gas to the CF4/O2/He Plasma, the MoSiON etching profile becomes anisotropic without undercutting and trench profile. It is probably due to both increasing etch rate and sidewall passivation of Cl2 ion flux. When Cl2 gas was added to the CF4/O2/He Plasma, the small addition of chlorine was enough to protect the exposed sidewall of the undercutting, therefore, higher flow rate of chlorine had to be added to protect the sidewall of the undercutting by forming a sidewall passivation layer. These results show that both increasing O2 flow rate to the SF6/O2/He Plasma and the addition of Cl2 to the CF4/O2/He plasma are necessary in order to achieve a vertical profile and a smooth surface
Stanley, David A; Talathi, Sachin S; Parekh, Mansi B; Cordiner, Daniel J; Zhou, Junli; Mareci, Thomas H; Ditto, William L; Carney, Paul R
2013-09-01
For over a century epileptic seizures have been known to cluster at specific times of the day. Recent studies have suggested that the circadian regulatory system may become permanently altered in epilepsy, but little is known about how this affects neural activity and the daily pattern of seizures. To investigate, we tracked long-term changes in the rate of spontaneous hippocampal EEG spikes (SPKs) in a rat model of temporal lobe epilepsy. In healthy animals, SPKs oscillated with near 24-h period; however, after injury by status epilepticus, a persistent phase shift of ∼12 h emerged in animals that later went on to develop chronic spontaneous seizures. Additional measurements showed that global 24-h rhythms, including core body temperature and theta state transitions, did not phase shift. Instead, we hypothesized that locally impaired circadian input to the hippocampus might be responsible for the SPK phase shift. This was investigated with a biophysical computer model in which we showed that subtle changes in the relative strengths of circadian input could produce a phase shift in hippocampal neural activity. MRI provided evidence that the medial septum, a putative circadian relay center for the hippocampus, exhibits signs of damage and therefore could contribute to local circadian impairment. Our results suggest that balanced circadian input is critical to maintaining natural circadian phase in the hippocampus and that damage to circadian relay centers, such as the medial septum, may disrupt this balance. We conclude by discussing how abnormal circadian regulation may contribute to the daily rhythms of epileptic seizures and related cognitive dysfunction.
Analytical description of photon beam phase spaces in inverse Compton scattering sources
Curatolo, C.; Drebot, I.; Petrillo, V.; Serafini, L.
2017-08-01
We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc.) and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a quite accurate first
Analytical description of photon beam phase spaces in inverse Compton scattering sources
Directory of Open Access Journals (Sweden)
C. Curatolo
2017-08-01
Full Text Available We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc. and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a
Studies in A-scan echoencephalography: evaluation of a proposed two phase shift
Directory of Open Access Journals (Sweden)
Helio Lemmi
1969-09-01
Full Text Available A series of 440 patients studied by echoencephalography is reported. Rather than dividing the patients in the classic two groups of less than 3 mm and more than 3 mm deviation of the midline, the patients in this study were divided into three groups, correlating the degree of midline shift to the presence of intracranial pathology. Group I, showing 0 to 2.5 mm shift proves to be normal with a "miss" rate of only 10%. Group II, showing 2.5 to 3.5 mm shift is regarded as a borderline group with an incidence of significant intracranial pathology of 46%, clearly indicating the need for further evaluation. Group III, demonstrating greater than 3.5 mm shift from the midline, is designated with confidence as abnormal, with a yield of significant intracranial pathology of 100% in this study.
Geometric phase and o-mode blue shift in a chiral anisotropic medium inside a Fabry-P\\'erot cavity
Timofeev, I V; Sutormin, V S; Myslivets, S A; Arkhipkin, V G; Vetrov, S Ya; Lee, W; Zyryanov, V Ya
2015-01-01
Anomalous spectral shift of transmission peaks is observed in a Fabry--P\\'erot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method and geometrically using the generalized Mauguin--Poincar\\'e rolling cone method. The $o$-mode blue shift is measured for a 4-methoxybenzylidene-4'-$n$-butylaniline twisted--nematic layer inside the Fabry--P\\'erot cavity. The twist is electrically induced due to the homeoplanar--twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model.
Qiao, Yangzi; Yin, Hui; Chang, Nan; Wan, Mingxi
2017-03-01
Phase-shift Nano-emulsions (PSNEs) with a small initial diameter in nanoscale have the potential to leak out of the blood vessels and to accumulate at target point of tissue. At desired location, PSNEs can undergo acoustic droplet vaporization (ADV) process, change into gas bubbles and enhance focused ultrasound efficiency. The aim of this work was to provide spatial and temporal information on PSNE induced cavitation and ablation effects during pulsed high intensity focused ultrasound (HIFU) exposure. The PSNEs were composed of perfluorohaxane (PFH) and bovine serum albumin (BSA), and then uniformly distributed in a transparent polyacrylamide phantom. The Sonoluminescence (SL) method was employed to visualize the cavitation distribution and formation process of PSNEs induced cavitation. For the phantom which was used for ablation observation, heat sensitive BSA was added. When the temperature generated by ultrasound exposure was high enough to denature BSA, the transparent phantom would turn out white lesions. The shape of the lesion and the formation process were compared with those of cavitation. Each of the pulse contained 12 cycles for a duration of 10 µs. And the duty cycle changed from 1:10 to 1:40. The total "on" time of HIFU was 2s. PSNE can evidently accelerate cavitation emitting bright SL in pre-focal region. The cavitation was generated layer by layer towards the transducer. The formed bubble wall can block acoustic waves transmitting to the distal end. And the lesion appeared to be separated into two parts. One in pre-focal region stemmed from one point and grew quickly toward the transducer. The other in focal region was formed by merging some small white dots, and grew much slower. The influence of duty cycle has also been examined. The lower duty cycle with longer pulse-off time would generate more intense cavitation, however, smaller lesion. Bubble cloud gradually developed within phantom would greatly influence the cavitation and ablation
The Nonrelativistic Scattering States of the Deng-Fan Potential
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Bentol Hoda Yazarloo
2013-01-01
Full Text Available The approximately analytical scattering state solution of the Schrodinger equation is obtained for the Deng-Fan potential by using an approximation scheme to the centrifugal term. Energy eigenvalues, normalized wave functions, and scattering phase shifts are calculated. We consider and verify two special cases: the l=0 and the s-wave Hulthén potential.
Wexler, D. B.; Moore-Ede, M. C.
1986-01-01
Circadian rhythms in physiological and behavioral functions gradually resynchronize after phase shifts in environmental time cues. In order to characterize the rate of circadian resynchronization in a diurnal primate model, the temperature, locomotor activity, and polygraphically determined sleep-wake states were monitored in squirrel monkeys before and after 8-h phase shifts of an environmental light-dark cycle of 12 h light and 12 h dark (LD 12:12). For the temperature rhythm, resynchronization took 4 d after phase delay shift and 5 d after phase advance shift; for the rest-activity cycle, resynchronization times were 3 d and 6 d, respectively. The activity acrophase shifted more rapidly than the temperature acrophase early in the post-delay shift interval, but this internal desynchronization between rhythms disappeared during the course of resynchronization. Further study of the early resynchronization process requires emphasis on identifying evoked effects and measuring circadian pacemaker function.
Energy Technology Data Exchange (ETDEWEB)
Hedman, Matthew M. [Physics Department, University of Idaho, 875 Perimeter Drive, MS 0903, Moscow, ID 83844-0903 (United States); Stark, Christopher C., E-mail: mhedman@uidaho.edu, E-mail: cstark@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2015-09-20
The appearance of debris disks around distant stars depends upon the scattering/phase function (SPF) of the material in the disk. However, characterizing the SPFs of these extrasolar debris disks is challenging because only a limited range of scattering angles are visible to Earth-based observers. By contrast, Saturn’s tenuous rings can be observed over a much broader range of geometries, so their SPFs can be much better constrained. Since these rings are composed of small particles released from the surfaces of larger bodies, they are reasonable analogs to debris disks and so their SPFs can provide insights into the plausible scattering properties of debris disks. This work examines two of Saturn’s dusty rings: the G ring (at 167,500 km from Saturn’s center) and the D68 ringlet (at 67,600 km). Using data from the cameras on board the Cassini spacecraft, we are able to estimate the rings’ brightnesses at scattering angles ranging from 170° to 0.°5. We find that both of the rings exhibit extremely strong forward-scattering peaks, but for scattering angles above 60° their brightnesses are nearly constant. These SPFs can be well approximated by a linear combination of three Henyey–Greenstein functions, and are roughly consistent with the SPFs of irregular particles from laboratory measurements. Comparing these data to Fraunhofer and Mie models highlights several challenges involved in extracting information about particle compositions and size distributions from SPFs alone. The SPFs of these rings also indicate that the degree of forward scattering in debris disks may be greatly underestimated.
Zhu, Cunguang; Chang, Jun; Wang, Pengpeng; Wei, Wei; Zhang, Sasa; Liu, Zhi; Peng, Gangding
2013-12-16
A novel method based on distributed-feedback laser diode (DFB-LD) continuous wavelength-scanning for acquiring precise spectra of phase-shift fiber gratings is presented. Compared to the traditional method, the spectral resolution retrieved by this method is only limited by the optical line-width of the light source, which can reach up to the order of femtometer and is much higher than that of high-resolution optical spectrum analyzer (generally on the order of picometer). In addition, a Signal-to-Noise Ratio (SNR) advantage can be provided owing to a much higher spectral density of DFB-LD than amplified spontaneous emission (ASE) source. Precise spectra of three phase-shift fiber grating samples have been obtained at a resolution of 23.5 femtometer.
Thornton, Douglas E.; Spencer, Mark F.; Perram, Glen P.
2017-09-01
The effects of deep turbulence in long-range imaging applications presents unique challenges to properly measure and correct for aberrations incurred along the atmospheric path. In practice, digital holography can detect the path-integrated wavefront distortions caused by deep turbulence, and di erent recording geometries offer different benefits depending on the application of interest. Previous studies have evaluated the performance of the off-axis image and pupil plane recording geometries for deep-turbulence sensing. This study models digital holography in the on-axis phase shifting recording geometry using wave optics simulations. In particular, the analysis models spherical-wave propagation through varying deep-turbulence conditions to estimate the complex optical field, and performance is evaluated by calculating the field-estimated Strehl ratio and RMS wavefront error. Altogether, the results show that digital holography in the on-axis phase shifting recording geometry is an effective wavefront-sensing method in the presence of deep turbulence.
Prabhathan, P; Murukeshan, V M; Jing, Zhang; Ramana, Pamidighantam V
2009-10-10
We propose the silicon-on-insulator (SOI) based, phase shifted vertical side wall grating as a resonant transmission filter suitable for dense wavelength division multiplexing (DWDM) communication channels with 100 GHz channel spacing. The gratings are designed and numerically simulated to obtain a minimum loss in the resonant cavity by adjusting the grating parameters so that a high transmittivity can be achieved for the resonant transmission. The resonant grating, which is designed to operate in the DWDM International Telecommunication Union (ITU) grid C band of optical communication, has a high free spectral range of 51.7 nm and a narrow band resonant transmission. The wavelength selectivity of the filter is improved through a coupled cavity configuration by applying two phase shifts to the gratings. The observed channel band width and channel isolation of the resonant transmission filter are good and in agreement with the ITU specifications.
DEFF Research Database (Denmark)
Marques, C. A. F.; Pospori, A.; Pereira, L.
2017-01-01
We present the first phase-shifted polymer optical fiber Bragg grating sensor inscribed with only one KrF laser pulse. The phase shift defect was created directly during the grating inscription process by placing a very narrow blocking aperture, in the center of the UV beam. One laser pulse...... with a duration of 15 ns and energy 6.3 mJ is adequate to introduce a refractive index change of 0.69×10−4 in the fiber core. The high-quality produced Bragg grating structure rejects 16.3 dB transmitted power, thus providing 97.6% reflectivity, which is well suited for photonic applications. The transmission...
Experimental study of entanglement evolution in the presence of bit-flip and phase-shift noises
Liu, Xia; Cao, Lian-Zhen; Zhao, Jia-Qiang; Yang, Yang; Lu, Huai-Xin
2017-10-01
Because of its important role both in fundamental theory and applications in quantum information, evolution of entanglement in a quantum system under decoherence has attracted wide attention in recent years. In this paper, we experimentally generate a high-fidelity maximum entangled two-qubit state and present an experimental study of the decoherence properties of entangled pair of qubits at collective (non-collective) bit-flip and phase-shift noises. The results shown that entanglement decreasing depends on the type of the noises (collective or non-collective and bit-flip or phase-shift) and the number of qubits which are subject to the noise. When two qubits are depolarized passing through non-collective noisy channel, the decay rate is larger than that depicted for the collective noise. When two qubits passing through depolarized noisy channel, the decay rate is larger than that depicted for one qubit.
Iida, Atsuo; Nishiyama, Isa; Takanishi, Yoichi
2014-03-01
The electric-field-induced phase transition of a chiral liquid crystal containing Br revealed a transition phase between the three-layer periodicity ferrielectric phase and the synclinic ferroelectric phase in the electric field versus temperature phase diagram. Resonant x-ray scattering from the transition phase showed a diffuse streak or spotty weak reflections, which were composed of strong m/3-order (where m = 1 and 2) reflections and other weak peaks. The spotty reflections were found to be related to a 12-layer periodicity phase with a weak contribution from the 15-layer periodicity. An x-ray intensity analysis based on the Ising model suggested that the 12-layer periodicity phase was composed of two three-layer ferrielectric blocks and six synclinic layers. This model indicated that, in the transition phase, the three-layer ferrielectric molecular configuration gradually changed to the synclinic configuration. The diffuse streak appearing around m/3-order reflections near the field-induced transition from the four-layer periodicity phase to the synclinic ferroelectric phase is also discussed.
Dong, Po; Gui, Chengcheng
2016-06-15
In coherent optical transmission, traveling-wave Mach-Zehnder modulators are commonly used to generate various advanced formats where the modulators are biased at the minimum transmission point. Here, we report that an optical isolation effect with lower backward transmission occurs under this condition. This concept is successfully demonstrated to achieve ∼7 dB isolation over a 90-nm wavelength span under binary phase-shift keying modulation using a commercial lithium niobate modulator.
Chow, C W; Talli, G; Ellis, A D; Townsend, P D
2008-02-04
We demonstrate a novel Rayleigh interferometric noise mitigation scheme for applications in carrier-distributed dense wavelength division multiplexed (DWDM) passive optical networks at 10 Gbit/s using carrier suppressed subcarrier-amplitude modulated phase shift keying modulation. The required optical signal to Rayleigh noise ratio is reduced by 12 dB, while achieving excellent tolerance to dispersion, subcarrier frequency and drive amplitude variations.
Electrical system using phase-shifted carrier signals and related operating methods
Welchko, Brian A; Campbell, Jeremy B
2012-09-18
An automotive drive system and methods for making the same are provided. The system includes a three-phase motor and an inverter module. The three-phase motor includes a first set of windings each having a first magnetic polarity; and a second set of windings each having a second magnetic polarity that is opposite the first magnetic polarity. The first set of windings being electrically isolated from the second set of windings. The inverter module includes a first set of phase legs and a second set of phase legs. Each one of the first set of phase legs is coupled to a corresponding phase of the first set of windings, and each one of the second set of phase legs is coupled to a corresponding phase of the second set of windings.
DEFF Research Database (Denmark)
Behrouzian, Ehsan; Bongiorno, Massimo; Teodorescu, Remus
2017-01-01
The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation. The case of high- and low-switching frequency for the converter cells...... control loops. It is also shown that the selected frequency modulation ratio affects the active power distribution among the cells. In particular, the selection of a noninteger frequency modulation ratio helps in providing a more uniform power distribution among cells of the same phase leg, thus...
Ishikawa, K.; Yatabe, K.; Ikeda, Y.; Oikawa, Y.; Onuma, T.; Niwa, H.; Yoshii, M.
2017-02-01
Imaging of sound aids the understanding of the acoustical phenomena such as propagation, reflection, and diffraction, which is strongly required for various acoustical applications. The imaging of sound is commonly done by using a microphone array, whereas optical methods have recently been interested due to its contactless nature. The optical measurement of sound utilizes the phase modulation of light caused by sound. Since light propagated through a sound field changes its phase as proportional to the sound pressure, optical phase measurement technique can be used for the sound measurement. Several methods including laser Doppler vibrometry and Schlieren method have been proposed for that purpose. However, the sensitivities of the methods become lower as a frequency of sound decreases. In contrast, since the sensitivities of the phase-shifting technique do not depend on the frequencies of sounds, that technique is suitable for the imaging of sounds in the low-frequency range. The principle of imaging of sound using parallel phase-shifting interferometry was reported by the authors (K. Ishikawa et al., Optics Express, 2016). The measurement system consists of a high-speed polarization camera made by Photron Ltd., and a polarization interferometer. This paper reviews the principle briefly and demonstrates the high-speed imaging of acoustical phenomena. The results suggest that the proposed system can be applied to various industrial problems in acoustical engineering.
Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, J. Bernard; Wygant, J. R.; Kletzing, C. A.
2017-02-01
We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ˜450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (˜50 to 150 keV) across the estimated resonant energy (˜104 keV) is ˜360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift-resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave-particle interaction in the magnetosphere.
Thermal-induced phase-shift error of a fiber-optic gyroscope due to fiber tail length asymmetry.
Zhang, Yunhao; Zhang, Yonggang; Gao, Zhongxing
2017-01-10
As a high-precision angular sensor, the fiber-optic gyroscope (FOG) usually shows high sensitivity to disturbances of the environmental temperature. Research on thermal-induced error of the FOG is meaningful to improve its robust performance and reliability in practical applications. In this paper, thermal-induced nonreciprocal phase-shift error of the FOG due to asymmetric fiber tail length is discussed in detail, based on temperature diffusion theory. Theoretical analysis shows that the increase of thermal-induced nonreciprocal phase shift of the FOG is proportional to the asymmetric tail length. Moreover, experiments with temperature ranging from -40°C to 60°C are performed to confirm the analysis. The analysis and experiment results indicate that we may compensate the asymmetry of fiber coil due to imperfect winding and the assembly process by adjusting the fiber tail length, which can reduce the thermal-induced phase-shift error and further improve the adaptability of the FOG in a changing ambient temperature.
Iida, Atsuo; Takanishi, Yoichi; Fukuda, Atsuo; Vij, Jagdish K
2016-11-01
Resonant x-ray scattering experiments revealed transitional subphases near the electric-field-induced phase transition of a Se-containing chiral liquid crystal in a planar aligned cell geometry. In the lower-temperature range (Sm-C_{A}^{*} and three-layer periodicity Sm-C_{γ}^{*} phases), the six-layer periodicity subphase appeared with increasing electric field during the field-induced transition from Sm-C_{γ}^{*} to Sm-C^{*}. In the higher-temperature range [four-layer periodicity antiferroelectric (AF) phase], the peak positions of the three-layer satellites shifted to those of the four-layer satellites and then the satellites corresponding to the five- through seven-layer periodicity appeared in sequence. Near the AF to Sm-C_{α}^{*} phase transition temperature, the layer periodicity increased with applied field. The molecular configurations of the subphases near the field-induced transition are discussed based on the Ising, distorted clock, and perfect clock models.
Directory of Open Access Journals (Sweden)
Seonhyeop Shin
2015-06-01
Full Text Available The elastic properties of KF-substituted perovskite lead titanate (PbTiO3 were investigated by dielectric measurements and Brillouin light scattering. The ferroelectric phase transition occurred at substantially lower temperature due to KF substitution, which was attributed to the modification of the covalency in Pb–O and Ti–O bonds. The longitudinal acoustic (LA mode of KF-substituted PbTiO3 showed a frequency softening in the paraelectric phase, which was accompanied by increasing acoustic damping. This indicated that polarization fluctuations responsible for the acoustic anomalies were enhanced by KF substitution.
Electron Elastic-Scattering Cross-Section Database
SRD 64 NIST Electron Elastic-Scattering Cross-Section Database (PC database, no charge) This database provides values of differential elastic-scattering cross sections, corresponding total elastic-scattering cross sections, phase shifts, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 20,000 eV (in steps of 1 eV).
Quax, Silvan; Jensen, Ole; Tiesinga, Paul
2017-05-01
Selective routing of information between cortical areas is required in order to combine different sources of information according to cognitive demand. Recent experiments have suggested that alpha band activity originating from the pulvinar coordinates this inter-areal cortical communication. Using a computer model we investigated whether top-down induced shifts in the relative alpha phase between two cortical areas could modulate cortical communication, quantified in terms of changes in gamma band coherence between them. The network model was comprised of two uni-directionally connected neuronal populations of spiking neurons, each representing a cortical area. We find that the phase difference of the alpha oscillations modulating the two neuronal populations strongly affected the interregional gamma-band neuronal coherence. We confirmed that a higher gamma band coherence also resulted in more efficient transmission of spiking information between cortical areas, thereby confirming the value of gamma coherence as a proxy for cortical information transmission. In a model where both neuronal populations were connected bi-directionally, the relative alpha phase determined the directionality of communication between the populations. Our results show the feasibility of a physiological realistic mechanism for routing information in the brain based on coupled oscillations. Our model results in a set of testable predictions regarding phase shifts in alpha oscillations under different task demands requiring experimental quantification of neuronal oscillations in different regions in e.g. attention paradigms.
Directory of Open Access Journals (Sweden)
Silvan Quax
2017-05-01
Full Text Available Selective routing of information between cortical areas is required in order to combine different sources of information according to cognitive demand. Recent experiments have suggested that alpha band activity originating from the pulvinar coordinates this inter-areal cortical communication. Using a computer model we investigated whether top-down induced shifts in the relative alpha phase between two cortical areas could modulate cortical communication, quantified in terms of changes in gamma band coherence between them. The network model was comprised of two uni-directionally connected neuronal populations of spiking neurons, each representing a cortical area. We find that the phase difference of the alpha oscillations modulating the two neuronal populations strongly affected the interregional gamma-band neuronal coherence. We confirmed that a higher gamma band coherence also resulted in more efficient transmission of spiking information between cortical areas, thereby confirming the value of gamma coherence as a proxy for cortical information transmission. In a model where both neuronal populations were connected bi-directionally, the relative alpha phase determined the directionality of communication between the populations. Our results show the feasibility of a physiological realistic mechanism for routing information in the brain based on coupled oscillations. Our model results in a set of testable predictions regarding phase shifts in alpha oscillations under different task demands requiring experimental quantification of neuronal oscillations in different regions in e.g. attention paradigms.
Energy Technology Data Exchange (ETDEWEB)
Baimbetov, F B; Kudyshev, Z A [Department of Physics, Al-Farabi Kazakh National University, 050012 Almaty (Kazakhstan)], E-mail: Fazylhan.Baimbetov@kaznu.kz, E-mail: Z.Kudyshev@mail.ru
2009-05-29
In the present work an electron impact ionization cross section is considered. The electron impact ionization cross section is calculated with the help of a variable phase approach to potential scattering. The Calogero equation is numerically solved, based on a pseudopotential model of interaction between partially ionized plasma particles, which accounts for correlation effects. As a result, scattering phase shifts are obtained. On the basis of the scattering phase shifts, the ionization cross section is calculated.
DEFF Research Database (Denmark)
Lico, Pasqualino; Marinelli, Mattia; Knezovic, Katarina
2015-01-01
In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise....... This may results in heavy imbalances. This paper uses a real Danish distribution system with household consumers, photovoltaic installation and electrical vehicles (EV). In this paper the possibility to use EVs’ charging spots in order to reduce grid’s imbalances will be investigated. Usually, charging...
Bozhenkov, S. A.; Beurskens, M.; Dal Molin, A.; Fuchert, G.; Pasch, E.; Stoneking, M. R.; Hirsch, M.; Höfel, U.; Knauer, J.; Svensson, J.; Trimino Mora, H.; Wolf, R. C.
2017-10-01
The optimized stellarator Wendelstein 7-X started operation in December 2015 with a 10 week limiter campaign. Divertor experiments will begin in the second half of 2017. The W7-X Thomson scattering system is an essential diagnostic for electron density and temperature profiles. In this paper the Thomson scattering diagnostic is described in detail, including its design, calibration, data evaluation and first experimental results. Plans for further development are also presented. The W7-X Thomson system is a Nd:YAG setup with up to five lasers, two sets of light collection lenses viewing the entire plasma cross-section, fiber bundles and filter based polychromators. To reduce hardware costs, two or three scattering volumes are measured with a single polychromator. The relative spectral calibration is carried out with the aid of a broadband supercontinuum light source. The absolute calibration is performed by observing Raman scattering in nitrogen. The electron temperatures and densities are recovered by Bayesian modelling. In the first campaign, the diagnostic was equipped for 10 scattering volumes. It provided temperature profiles comparable to those measured using an electron cyclotron emission diagnostic and line integrated densities within 10% of those from a dispersion interferometer.
Resonance and phase shift in an open Aharonov-Bohm ring with an embedded quantum dot.
Hedin, Eric R; Joe, Yong S; Satanin, Arkady M
2009-01-07
The transmission and phase properties of electron transport through a quantum dot (QD) with variable coupling to a third-terminal probe are investigated analytically for the case of the QD connected directly to source and drain reservoirs and when the QD is embedded in one arm of an Aharonov-Bohm (AB) ring. Using the tight-binding model, explicit analytical expressions of the transmission through the QD for each case are given. Expressions for the conductance with coupling to the third terminal, which breaks unitarity and phase-locking, are also given. It is shown that in a three-terminal interferometer the zero of the Fano resonance in the transmission moves off the real energy axis for finite values of the coupling parameter. The zero orbits around the pole in the complex energy plane as a function of magnetic flux through the ring, and can be returned to the real energy axis unless the coupling parameter exceeds a critical value. With the QD embedded in one arm of the AB ring, the electron transmission and the transmission phase, and the phase of the AB oscillations, are described in relation to the degree of coupling to the third-terminal probe which opens the interferometer. By tuning the degree of coupling to the probe, it is shown that the phase of the AB oscillations can be made to match the intrinsic phase of the QD, facilitating experimental characterization of the phase response of the QD.
Schaub, Scott A.; Naqwi, Amir A.; Harding, Foster L.
1998-01-01
We present fundamental studies examining the design of a phase /Doppler laser light-scattering system applicable to on-line measurements of small-diameter ( fiberglass manufacturing. We first discuss off-line diameter measurement techniques currently used in the fiberglass industry and outline the limitations and problems associated with these methods. For the phase /Doppler design study we have developed a theoretical computer model for the response of the measurement system to cylindrical fibers, which is based on electromagnetic scattering theory. The model, valid for arbitrary fiber diameters and hardware configurations, generates simulated detector output as a function of time for a finite absorbing, cylindrical fiber oriented perpendicular to the two incident laser beams. Results of experimental measurements are presented, confirming predictions of the theoretical model. Parametric studies have also been conducted using the computer model to identify experimental arrangements that provide linear phase -diameter relationships for small-diameter fibers, within the measurement constraints imposed by the fiberglass production environment. The effect of variations in optical properties of the glass as well as fiber orientation effects are discussed. Through this research we have identified phase /Doppler arrangements that we expect to have future applications in the fiberglass industry for on-line diameter monitoring and process control.
Energy Technology Data Exchange (ETDEWEB)
Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics
1996-12-31
We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.
Scattering state solutions of the Duffin-Kemmer-Petiau equation with the Varshni potential model
Energy Technology Data Exchange (ETDEWEB)
Oluwadare, O.J. [Federal University Oye-Ekiti, Department of Physics, Oye-Ekiti, Ekiti State (Nigeria); Oyewumi, K.J. [Federal University of Technology, Department of Physics, Minna, Niger State (Nigeria)
2017-02-15
The scattering state of the Duffin-Kemmer-Petiau equation with the Varshni potential was studied. The asymptotic wave function, the scattering phase shift and normalization constant were obtained for any J states by dealing with the centrifugal term using a suitable approximation. The analytical properties of the scattering amplitude and the bound state energy were obtained and discussed. Our numerical and graphical results indicate that the scattering phase shift depends largely on total angular momentum J, screening parameter β and potential strengths a and b. (orig.)
Polymer boosting effect in the droplet phase studied by small-angle neutron scattering
Frielinghaus, H; Allgaier, J; Richter, D; Jakobs, B; Sottmann, T; Strey, R
2002-01-01
Small-angle neutron-scattering experiments were performed in order to obtain the six partial scattering functions of a droplet microemulsion containing water, decane, C sub 1 sub 0 E sub 4 surfactant and PEP sub 5 -PEO sub 8 sub 0. We systematically varied the contrast around the polymer contrast, where only the polymer becomes visible, and we also measured bulk and film contrasts. With the singular value decomposition method we could extract the desired six partial scattering functions from the 15 measured spectra. We find a sphere-shell-shell structure of the droplets, where the innermost sphere consists of oil, the middle shell of surfactant and the outer shell is a depletion zone where the polymer is almost not present. (orig.)
Kopechek, Jonathan A.; Zhang, Peng; Burgess, Mark T.; Porter, Tyrone M.
2012-01-01
High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments. PMID:23007836
Waldo, Nicholas B; Vecitis, Chad D
2018-03-01
In an effort to increase the efficiency of sonochemical reactors, this study investigates a single-source, dual-high-frequency ultrasound reactor. Experiments were conducted with a variety of piezoelectric crystals and reactor components, and for each reactor design a range of power distributions and phase shifts between the two frequencies were evaluated. Certain dual-frequency configurations produced up to a threefold increase in sonochemical efficiency, while others yeilded no improvement over a single frequency. These results led to two significant findings. First, phase-shift had a strong effect on sonochemical efficiency for both harmonic and non-harmonic frequency combinations. Second, the most efficient dual-harmonic-frequency waveforms had a single peak per half-cycle, rather than two unique peaks. If dual-frequency, single-source ultrasound reactors are to become more efficient they must be able to consistently control the phase angle of and power distribution between harmonic waves to create an optimal waveform. Copyright © 2017 Elsevier B.V. All rights reserved.
Kanick, S. C.; Krishnaswamy, V.; Gamm, U. A.; Sterenborg, H. J. C. M.; Robinson, D. J.; Amelink, A.; Pogue, B. W.
2012-01-01
Reflectance spectra measured in Intralipid (IL) close to the source are sensitive to wavelength-dependent changes in reduced scattering coefficient (μ′s) and scattering phase function (PF). Experiments and simulations were performed using device designs with either single or separate optical fibers for delivery and collection of light in varying concentrations of IL. Spectral reflectance is not consistently linear with varying IL concentration, with PF-dependent effects observed for single fiber devices with diameters smaller than ten transport lengths and for separate source-detector devices that collected light at less than half of a transport length from the source. Similar effects are thought to be seen in tissue, limiting the ability to quantitatively compare spectra from different devices without compensation. PMID:22567598
Li, Dian-Jeng; Tseng, Ping-Tao; Chen, Yen-Wen; Wu, Ching-Kuan; Lin, Pao-Yen
2016-01-01
Abstract Bupropion is widely used for treating bipolar disorder (BD), and especially those with depressive mood, based on its good treatment effect, safety profile, and lower risk of phase shifting. However, increasing evidence indicates that the safety of bupropion in BD patients may not be as good as previously thought. The aim of this study was to summarize data on the treatment effect and safety profile of bupropion in the treatment of BD via a meta-analysis. Electronic search through PubMed and ClinicalTrials.gov was performed. The inclusion criteria were: (i) studies comparing changes in disease severity before and after bupropion treatment or articles comparing the treatment effect of bupropion in BD patients with those receiving other standard treatments; (ii) articles on clinical trials in humans. The exclusion criteria were (i) case reports/series, and (ii) nonclinical trials. All effect sizes from 10 clinical trials were pooled using a random effects model. We examined the possible confounding variables using meta-regression and subgroup analysis. Bupropion significantly improved the severity of disease in BD patients (P bupropion and those who received other antidepressants. We could not perform a detailed meta-analysis of every category of antidepressant, nor could we rule out the possible confounding effect of concurrent psychotropics or include all drug side effects. Furthermore, the number of studies recruited in the meta-analysis was relatively small. Our findings reconfirm the benefits of bupropion for the treatment of bipolar depression, which are similar to those of other antidepressants. However, the rate of phase shifting with bupropion usage was not as low compared to other antidepressants as previously thought, which should serve to remind clinicians of the risk of phase shifting when prescribing bupropion to BD patients regardless of the suggestions of current clinical practice guidelines. PMID:27043678
Quark model for kaon nucleon scattering
Indian Academy of Sciences (India)
Abstract. Kaon nucleon elastic scattering is studied using chiral SU(3) quark model including antiquarks. Parameters of the present model are essentially based on nucleon–nucleon and nucleon– hyperon interactions. The mass of the scalar meson σ is taken as 635 MeV. Using this model, the phase shifts of the S and P ...
Simple Z$\\_{0}\\^{*}$ model (Isoscalar KN scattering)
Johnson, R C
1974-01-01
A model for isoscalar KN scattering near the K*N threshold is constructed, and solved analytically in the approximation of retaining only pion exchange terms. Basic features of phenomenological phase shifts are reproduced, including a wide J/sup P/=1/2/sup +/ exotic resonance, Z/sub 0/* (1800). (19 refs).
Amiranoff, F.; Riconda, C.; Chiaramello, M.; Lancia, L.; Marquès, J. R.; Weber, S.
2018-01-01
The role of the global phase in the spatio-temporal evolution of the 3-wave coupled equations for backscattering is analyzed in the strong-coupling regime of Brillouin scattering. This is of particular interest for controlled backscattering in the case of plasma-based amplification to produce short and intense laser pulses. It is shown that the analysis of the envelope equations of the three waves involved, pump, seed, and ion wave, in terms of phase and amplitude fully describes the coupling dynamics. In particular, it helps understanding the role of the chirp of the laser beams and of the plasma density profile. The results can be used to optimize or quench the coupling mechanism. It is found that the directionality of the energy transfer is imposed by the phase relation at the leading edge of the pulse. This actually ensures continued energy transfer even if the intensity of the seed pulse is already higher than the pump pulse intensity.
Barnes, Jack A; Loock, Hans-Peter
2016-09-19
Several mathematical models exist in the literature to describe the properties of optical resonators. Here, coupled mode theory and coherent superposition theory are compared and their consistency is demonstrated as they are applied to phase-shift cavity ring-down measurements in optical (micro-)cavities. In the particular case of a whispering gallery mode in a microsphere cavity these models are applied to transmission measurements and backscattering measurements through the fiber taper that couples light into the microresonator. It is shown that both models produce identical relations when applied to these traveling wave cavities.
A tractable above-threshold model for the design of DFB and phase-shifted DFB lasers
Orfanos, I.; Sphicopoulos, Thomas; Tsigopoulos, A.; Caroubalos, C.
1991-04-01
A model, based on the transfer matrix method and extended to above-threshold conditions in order to be used in the analysis and design of distributed feedback (DFB) structures, is presented. It provides the oscillation parameters as lasing frequency and net material gain, the linewidth estimation and output power, the photon density, carrier density, and effective refractive index profiles. This model can be used with or without facet reflectivities and with a number of symmetric or asymmetric phase shifts. It takes into account nonuniform envelope material gain and nonuniform index saturation. It is easily adaptable to any structure modifications.
Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Dong, Chen; Li, Xuan
2016-04-10
Displacement damage (DD) effect induced bit error ratio (BER) performance degradations in on-off keying (OOK), pulse position modulation (PPM), differential phase-shift keying (DPSK), and homodyne binary phase shift keying (BPSK) based systems were simulated and discussed under 1 MeV neutron irradiation to a total fluence of 1×1012 n/cm2 in this paper. Degradation of main optoelectronic devices included in communication systems were analyzed on the basis of existing experimental data. The system BER degradation was subsequently simulated and the variations of BER with different neutron irradiation location were also achieved. The result shows that DD on an Er-doped fiber amplifier (EDFA) is the dominant cause of system degradation, and a BPSK-based system performs better than the other three systems against DD. In order to improve radiation hardness of communication systems against DD, protection and enhancement of EDFA are required, and the use of a homodyne BPSK modulation scheme is a considered choice.
Slurry phase Fischer-Tropsch synthesis: Cobalt plus a water-gas shift catalyst
Energy Technology Data Exchange (ETDEWEB)
Chanenchuk, C.A.; Yates, I.C.; Satterfield, C.N.
1990-01-01
A Co/MgO/SiO[sub 2] Fischer-Tropsch catalyst was operated simultaneously with a Cu/ZnO/Al[sub 2]O[sub 3] water-gas-shift catalyst in a slurry reactor for over 400 hours. The process conditions were held constant at a temperature of 240[degrees]C, a pressure of 0.79 MPa, and a 1.1 H[sub 2]/CO feed of 0.065 Nl/min-g.cat. The Fischer-Tropsch activity remained constant at the level predicted by the operation of the Co/MgO/SiO[sub 2] catalyst alone. The water-gas-shift reaction was near equilibrium. The hydrocarbon product distribution of the combined catalyst system was stable and matched that of the CO/MgO/SiO[sub 2] operating alone under similar conditions. The combined catalyst system exhibited a high selectivity to n-alkanes. Neither catalysts's operation appeared to have a detrimental effect on that of the other, showing promise for future option.
Energy Technology Data Exchange (ETDEWEB)
Zeghuzi, A., E-mail: zeghuzi@mailbox.tu-berlin.de; Schmeckebier, H.; Stubenrauch, M.; Bimberg, D. [Department of Solid-State Physics, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Meuer, C.; Schubert, C. [Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Einsteinufer 37, 10587 Berlin (Germany); Bunge, C.-A. [Hochschule fuer Telekommunikation Leipzig (HfTL), Gustav-Freytag-Str. 43-45, 04277 Leipzig (Germany)
2015-05-25
Error-free generation of 25-Gbit/s differential phase-shift keying (DPSK) signals via direct modulation of InAs quantum-dot (QD) based semiconductor optical amplifiers (SOAs) is experimentally demonstrated with an input power level of −5 dBm. The QD SOAs emit in the 1.3-μm wavelength range and provide a small-signal fiber-to-fiber gain of 8 dB. Furthermore, error-free DPSK modulation is achieved for constant optical input power levels from 3 dBm down to only −11 dBm for a bit rate of 20 Gbit/s. Direct phase modulation of QD SOAs via current changes is thus demonstrated to be much faster than direct gain modulation.
Smirnov, L S; Savenko, B N
2002-01-01
The x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I is studied using samples with the ammonium concentration 0.01
Gobert, Olivier; Mennerat, Gabriel; Cornaggia, Christian; Lupinski, Dominique; Perdrix, Michel; Guillaumet, Delphine; Lepetit, Fabien; Oksenhendler, Thomas; Comte, Michel
2016-05-01
We report the experimental demonstration of an electro-optic prism pair pure carrier-envelope phase (CEP) shifter at low voltage (shift of 1 rad for a voltage of 90 V, applied to a crystal of 5 mm aperture). Validating our mathematical model, the experiments prove that this set-up which uses two rubidium titanyl phosphate (RTP) crystals, can be used either as an efficient high bandwidth CEP shifter without modifying the group delay of an ultrashort pulse (isochronous CEP shifter) or alternatively as a group delay generator with quasi-constant CEP (Pure Group Delay generator). These two configurations which correspond to specific geometries are characterized by spectral interferometry with a 800 nm mode-locked Ti:sapphire laser. The results are in very good agreement with the model. In the pure group delay mode, a group delay of 2.3 fs is obtained at 1000 V/cm without significant CEP shift. In the isochronous mode, a shift of 5.5 rad at 1000 V/cm is generated without significant delay. The applied voltage is also lowered by a factor of nearly three in this configuration, compared to the case of an RTP rectangular slab of the same total length.
Energy Technology Data Exchange (ETDEWEB)
Zweck, Josef, E-mail: josef.zweck@ur.de; Schwarzhuber, Felix; Wild, Johannes; Galioit, Vincent
2016-09-15
Differential phase contrast is a STEM imaging mode where minute sideways deflections of the electron probe are monitored, usually by using a position sensitive device (Chapman, 1984 [1]; Lohr et al., 2012 [2]) or, alternatively in some cases, a fast camera (Müller et al., 2012 [3,4]; Yang et al., 2015 [5]; Pennycook et al., 2015 [6]) as a pixelated detector. While traditionally differential phase contrast electron microscopy was mainly focused on investigations of micro-magnetic domain structures and their specific features, such as domain wall widths, etc. (Chapman, 1984 [1]; Chapman et al., 1978, 1981, 1985 [7–9]; Sannomiya et al., 2004 [10]), its usage has recently been extended to mesoscopic (Lohr et al., 2012, 2016 [2,12]; Bauer et al., 2014 [11]; Shibata et al., 2015 [13]) and nano-scale electric fields (Shibata et al., 2012 [14]; Mueller et al., 2014 [15]). In this paper, the various interactions which can cause a beam deflection are reviewed and expanded by two so far undiscussed mechanisms which may be important for biological applications. As differential phase contrast microscopy strongly depends on the ability to detect minute beam deflections we first treat the linearity problem for an annular four quadrant detector and then determine the factors which limit the minimum measurable deflection angle, such as S/N ratio, current density, dwell time and detector geometry. Knowing these factors enables the experimenter to optimize the set-up for optimum performance of the microscope and to get a clear figure for the achievable field resolution error margins. - Highlights: • Detector linearity range determined. • Quantitative treatment of measurement precision for differential phase contrast. • Optimization strategy for detector geometry. • Possible application of differential phase contrast in biology.
Energy Technology Data Exchange (ETDEWEB)
Jain, N. [Pittsford Sutherland High School, NY (United States)
1999-03-01
Phase-shifting interferometry has many advantages, and the phase shifting nature of the Liquid Crystal Point Diffraction Interferometer (LCPDI) promises to provide significant improvement over other current OMEGA wavefront sensors. However, while phase-shifting capabilities improve its accuracy as an interferometer, phase-shifting itself introduces errors. Phase-shifting algorithms are designed to eliminate certain types of phase-shift errors, and it is important to chose an algorithm that is best suited for use with the LCPDI. Using polarization microscopy, the authors have observed a correlation between LC alignment around the microsphere and fringe behavior. After designing a procedure to compare phase-shifting algorithms, they were able to predict the accuracy of two particular algorithms through computer modeling of device-specific phase shift-errors.
Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs.
Kriegisch, Nina; Reeves, Simon; Johnson, Craig R; Ling, Scott D
2016-01-01
Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) was manipulated over 12 months to estimate (1) the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2) the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia. In parallel, the role of one of the 'bottom-up' drivers of ecosystem structure was examined by (3) manipulating local nutrient levels and thus attempting to alter primary production on the experimental reefs. It was found that densities of 8 or more urchins m-2 (≥ 427 g m-2 biomass) lead to complete overgrazing of kelp beds while kelp bed recovery occurred when densities were reduced to ≤ 4 urchins m-2 (≤ 213 g m-2 biomass). This experiment provided further insight into the dynamics of transition between urchin barrens and kelp beds by exploring possible tipping-points which in this system can be found between 4 and 8 urchins m-2 (213 and 427 g m-2 respectively). Local enhancement of nutrient loading did not change the urchin density required for overgrazing or kelp bed recovery, as algal growth was not affected by nutrient enhancement.
Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs.
Directory of Open Access Journals (Sweden)
Nina Kriegisch
Full Text Available Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems was manipulated over 12 months to estimate (1 the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2 the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia. In parallel, the role of one of the 'bottom-up' drivers of ecosystem structure was examined by (3 manipulating local nutrient levels and thus attempting to alter primary production on the experimental reefs. It was found that densities of 8 or more urchins m-2 (≥ 427 g m-2 biomass lead to complete overgrazing of kelp beds while kelp bed recovery occurred when densities were reduced to ≤ 4 urchins m-2 (≤ 213 g m-2 biomass. This experiment provided further insight into the dynamics of transition between urchin barrens and kelp beds by exploring possible tipping-points which in this system can be found between 4 and 8 urchins m-2 (213 and 427 g m-2 respectively. Local enhancement of nutrient loading did not change the urchin density required for overgrazing or kelp bed recovery, as algal growth was not affected by nutrient enhancement.
Magnani, N; Caciuffo, R; Lander, G H; Hiess, A; Regnault, L-P
2010-03-24
The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.
Kidun, O; Berakdar, J
2002-01-01
Following the framework of the variable-phase approach, we derive an equation for determining the scattering amplitude of a non-relativistic quantum particle in a non-local potential. Its solution implies the integration of the Volterra integro-differential equation of the first kind and allows determination of bound-state energies and wavefunctions. A fast numerical scheme for the solution of these equations is suggested and it is demonstrated that the proposed method requires the numerical efforts of the same order as in the local potential case.
Huang, Kuo-Ting; Chen, Hsi-Chao; Lin, Ssu-Fan; Lin, Ke-Ming; Syue, Hong-Ye
2012-09-01
While tin-doped indium oxide (ITO) has been extensively applied in flexible electronics, the problem of the residual stress has many obstacles to overcome. This study investigated the residual stress of flexible electronics by the double beam shadow moiré interferometer, and focused on the precision improvement with phase shifting interferometry (PSI). According to the out-of-plane displacement equation, the theoretical error depends on the grating pitch and the angle between incident light and CCD. The angle error could be reduced to 0.03% by the angle shift of 10° as a result of the double beam interferometer was a symmetrical system. But the experimental error of the double beam moiré interferometer still reached to 2.2% by the noise of the vibration and interferograms. In order to improve the measurement precision, PSI was introduced to the double shadow moiré interferometer. Wavefront phase was reconstructed by the five interferograms with the Hariharan algorithm. The measurement results of standard cylinder indicating the error could be reduced from 2.2% to less than 1% with PSI. The deformation of flexible electronic could be reconstructed fast and calculated the residual stress with the Stoney correction formula. This shadow moiré interferometer with PSI could improve the precision of residual stress for flexible electronics.