Sample records for maximum phase shift

  1. Crichton's phase-shift ambiguity

    Atkinson, D.; Johnson, P.W.; Mehta, N.; Roo, M. de


    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



    The effect of phase-shift error in phase shifting interferometry is investigated. A new algorithm with two sets of 4 samples for eliminating phase-shift error is presented. The computer simulation and experiment result show that the phase-shift offset should be π when the algorithm is used, and this algorithm has gotten better result than the original 4-sample algorithm.

  3. The holographic reconstructing algorithm and its error analysis about phase-shifting phase measurement

    LU Xiaoxu; ZHONG Liyun; ZHANG Yimo


    Phase-shifting measurement and its error estimation method were studied according to the holographic principle.A function of synchronous superposition of object complex amplitude reconstructed from N-step phase-shifting through one integral period (N-step phase-shifting function for short) was proposed.In N-step phase-shifting measurement,the interferograms are seen as a series of in-line holograms and the reference beam is an ideal parallel-plane wave.So the N-step phase-shifting function can be obtained by multiplying the interferogram by the original referencc wave.In ideal conditions.the proposed method is a kind of synchronous superposition algorithm in which the complex amplitude is separated,measured and superposed.When error exists in measurement,the result of the N-step phase-shifting function is the optimal expected value of the least-squares fitting method.In the above method,the N+1-step phase-shifting function can be obtained from the N-step phase-shifting function.It shows that the N-step phase-shifting function can be separated into two parts:the ideal N-step phase-shifting function and its errors.The phase-shifting errors in N-steps phase-shifting phase measurement can be treated the same as the relative errors of amplitude and intensity under the understanding of the N+1-step phase-shifting function.The difficulties of the error estimation in phase-shifting phase measurement were restricted by this error estimation method.Meanwhile,the maximum error estimation method of phase-shifting phase measurement and its formula were proposed.

  4. In-line phase shift tomosynthesis

    Hammonds, Jeffrey C.; Price, Ronald R.; Pickens, David R.; Donnelly, Edwin F. [Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232 (United States)


    Purpose: The purpose of this work is to (1) demonstrate laboratory measurements of phase shift images derived from in-line phase-contrast radiographs using the attenuation-partition based algorithm (APBA) of Yan et al.[Opt. Express 18(15), 16074–16089 (2010)], (2) verify that the APBA reconstructed images obey the linearity principle, and (3) reconstruct tomosynthesis phase shift images from a collection of angularly sampled planar phase shift images.Methods: An unmodified, commercially available cabinet x-ray system (Faxitron LX-60) was used in this experiment. This system contains a tungsten anode x-ray tube with a nominal focal spot size of 10 μm. The digital detector uses CsI/CMOS with a pixel size of 50 × 50 μm. The phantoms used consisted of one acrylic plate, two polystyrene plates, and a habanero pepper. Tomosynthesis images were reconstructed from 51 images acquired over a ±25° arc. All phase shift images were reconstructed using the APBA.Results: Image contrast derived from the planar phase shift image of an acrylic plate of uniform thickness exceeded the contrast of the traditional attenuation image by an approximate factor of two. Comparison of the planar phase shift images from a single, uniform thickness polystyrene plate with two polystyrene plates demonstrated an approximate linearity of the estimated phase shift with plate thickness (−1600 rad vs −2970 rad). Tomographic phase shift images of the habanero pepper exhibited acceptable spatial resolution and contrast comparable to the corresponding attenuation image.Conclusions: This work demonstrated the feasibility of laboratory-based phase shift tomosynthesis and suggests that phase shift imaging could potentially provide a new imaging biomarker. Further investigation will be needed to determine if phase shift contrast will be able to provide new tissue contrast information or improved clinical performance.

  5. Phase shifting in the spatial frequency domain

    Yazdani, Roghayeh; Petsch, Sebastian; Fallah, Hamidreza; Hajimahmoodzadeh, Morteza; Zappe, Hans


    We present a simple mathematical method for phase shifting that overcomes some phase shift errors and limitations of commonly used methods. The method is used to generate a sequence of phase-shifted interferograms from a single interferogram. The generated interferograms are employed to reconstruct the wavefront aberrations, as an application. The approach yields results with only very small deviations compared to both simulated wavefront aberrations, including the first 25 Zernike polynomials (0.05%) and those measured with a Shack-Hartmann sensor (0.5%).

  6. Phase shifting interferometry from two normalized interferograms with random tilt phase-shift.

    Liu, Fengwei; Wu, Yongqian; Wu, Fan


    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.

  7. Metrology on phase-shift masks

    Roeth, Klaus-Dieter; Maurer, Wilhelm; Blaesing-Bangert, Carola


    In the evaluation of new manufacturing processes, metrology is a key function, beginning with the first step of process development through the final step of everyday mass production at the fabrication floor level. RIM-type phase shift masks are expected to be the first application of phase shift masks in high volume production, since they provide improved lithography process capability at the expense of only moderate complexity in their manufacturing. Measurements of critical dimension (CD) and pattern position (overlay) on experimental rim-type and chromeless phase shift masks are reported. Pattern placement (registration) was measured using the Leitz LMS 2000. The overall design and important components were already described. The pattern placement of the RIM type phase shift structures on the photomask described above was determined within a tolerance of 25 nm (3s); nominal accuracy was within 45 nm (3s). On the chromeless phase shift mask the measurement results were easily obtained using a wafer intensity algorithm available with the system. The measurement uncertainties were less than 25 nm and 50 nm for precision and nominal accuracy respectively. The measurement results from the Leitz CD 200 using transmitted light were: a CD- distribution of 135 nm (3s) on a typical 6 micrometers structure all over the mask; the 0.9 micrometers RIM structure had a distribution of 43 nm (3s). Typical long term precision performance values for the CD 200 on both chrome and phase shift structures have been less than 15 nm.

  8. Phase shifts extraction based on time-domain orthogonal character of phase-shifting interferograms

    Shou, Junwei; Zhong, Liyun; Zhou, Yunfei; Tian, Jindong; Lu, Xiaoxu


    Based on the time-domain orthogonal character of different pixel intensity variation of phase-shifting interferograms, a novel non-iterative algorithm is proposed to achieve the phase shifts in random phase-shifting interferometry. Due to there is no requirement for the fringe number of phase-shifting interferograms, the proposed algorithm can work well even in the case that the fringe number of interferogram is less than one, which is a difficult problem in interferometry. Moreover, only two one-dimensional vectors, achieved from the average intensity of several pixels of interferogram, are enough to perform the phase shifts extraction, the proposed algorithm reveals rapid processing speed. Specially, compared with the conventional phase shifts extraction algorithms, the proposed algorithm does not need to perform the pixel-pixel calculation or the iterative calculation, so its processing speed is greatly improved. Both the simulation and the experiment demonstrate the outstanding performance of the proposed algorithm.

  9. Half-quadratic cost function for computing arbitrary phase shifts and phase: Adaptive out of step phase shifting.

    Rivera, Mariano; Bizuet, Rocky; Martinez, Amalia; Rayas, Juan A


    We present a phase shifting robust method for irregular and unknown phase steps. The method is formulated as the minimization of a half-quadratic (robust) regularized cost function for simultaneously computing phase maps and arbitrary phase shifts. The convergence to, at least, a local minimum is guaranteed. The algorithm can be understood as a phase refinement strategy that uses as initial guess a coarsely computed phase and coarsely estimated phase shifts. Such a coarse phase is assumed to be corrupted with artifacts produced by the use of a phase shifting algorithm but with imprecise phase steps. The refinement is achieved by iterating alternated minimization of the cost function for computing the phase map correction, an outliers rejection map and the phase shifts correction, respectively. The method performance is demonstrated by comparison with standard filtering and arbitrary phase steps detecting algorithms.

  10. Phase-Shifting Zernike Interferometer Wavefront Sensor

    Wallace, J. Kent; Rao, Shanti; Jensen-Clemb, Rebecca M.; Serabyn, Gene


    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

  11. Phase extraction based on sinusoidal extreme strip phase shifting method

    Hui, Mei; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin


    Multiple synthetic aperture imaging can enlarge pupil diameter of optical systems, and increase system resolution. Multiple synthetic aperture imaging is a cutting-edge topic and research focus in recent years, which is prospectively widely applied in fields like astronomical observations and aerospace remote sensing. In order to achieve good imaging quality, synthetic aperture imaging system requires phase extraction of each sub-aperture and co-phasing of whole aperture. In the project, an in-depth study about basic principles and methods of segments phase extraction was done. The study includes: application of sinusoidal extreme strip light irradiation phase shift method to extract the central dividing line to get segment phase extraction information, and the use of interference measurement to get the aperture phase extraction calibration coefficients of spherical surface. Study about influence of sinusoidal extreme strip phase shift on phase extraction, and based on sinusoidal stripe phase shift from multiple linear light sources of the illumination reflected image, to carry out the phase shift error for inhibiting the effect in the phase extracted frame.

  12. Discrete ambiguities in phase-shift analysis

    Heemskerk, A.C.; Kok, L.P.; Roo, M. de


    In two practical examples (α-3He and α-α 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.

  13. Shifts in the temperature of maximum density (TMD) of ionic liquid aqueous solutions.

    Tariq, M; Esperança, J M S S; Soromenho, M R C; Rebelo, L P N; Lopes, J N Canongia


    This work investigates for the first time shifts in the temperature of maximum density (TMD) of water caused by ionic liquid solutes. A vast amount of high-precision volumetric data--more than 6000 equilibrated (static) high-precision density determination corresponding to ∼90 distinct ionic liquid aqueous solutions of 28 different types of ionic liquid--allowed us to analyze the TMD shifts for different homologous series or similar sets of ionic solutes and explain the overall effects in terms of hydrophobic, electrostatic and hydrogen-bonding contributions. The differences between the observed TMD shifts in the -2 temperatures are discussed taking into account the different types of possible solute-water interactions that can modify the structure of the aqueous phase. The results also reveal different insights concerning the nature of the ions that constitute typical ionic liquids and are consistent with previous results that established hydrophobic and hydrophilic scales for ionic liquid ions based on their specific interactions with water and other probe molecules.

  14. Michelson interferometer based spatial phase shift shearography.

    Xie, Xin; Yang, Lianxiang; Xu, Nan; Chen, Xu


    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.

  15. Inhomogeneous phase shifting: an algorithm for nonconstant phase displacements

    Tellez-Quinones, Alejandro; Malacara-Doblado, Daniel


    In this work, we have developed a different algorithm than the classical one on phase-shifting interferometry. These algorithms typically use constant or homogeneous phase displacements and they can be quite accurate and insensitive to detuning, taking appropriate weight factors in the formula to recover the wrapped phase. However, these algorithms have not been considered with variable or inhomogeneous displacements. We have generalized these formulas and obtained some expressions for an implementation with variable displacements and ways to get partially insensitive algorithms with respect to these arbitrary error shifts.

  16. Energy phase shift as mechanism for catalysis

    Beke-Somfai, Tamás


    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.

  17. Sampled phase-shift fiber Bragg gratings

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)


    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  18. Influences of phase shift on superresolution performances of annular filters

    Liu Xi-Min; Liu Li-Ren; Bai Li-Hua


    This paper investigates the influences of phase shift on superresolution performances of annular filters.Firstly,it investigates the influence of phase shift on axial superresolution.It proves theoretically that axial superresolution can not be obtained by two-zone phase filter with phase shift π.and it gets the phase shift with which axial superresolution can be brought by two-zone phase filter.Secondly,it studies the influence of phase shift on transverse superresolution.It finds that the three-zone phase filter with arbitrary phase shift has an almost equal optimal transverse gain to that of commonly used three-zone phase filter,but can produce a much higher axial superresolution gain.Thirdly,it investigates the influence of phase shift on three-dimensional superresolution.Three-dimensional superresolution capability and design margin of three-zone complex filter with arbitrary phase shift are obtained,which presents the theoretical basis for three-dimensional superresolution design. Finally,it investigates the influence of phase shift on focal shift.To obtain desired focal shifts,it designs a series of three-zone phase filters with different phase shifts.A spatial light modulator (SLM) is used to implement the designed filters.By regulating the voltage imposed on the SLM,an accurate focal shift control iS obtained.

  19. Quantum fixed-point search algorithm with general phase shifts


    Grover presented the Phase-π/3 search by replacing the selective inversions by selective phase shifts of π/3.In this paper,we review and discuss the fixed-point search with general but equal phase shifts and the fixedpoint search with general but different phase shifts.

  20. Green binary and phase shifting mask

    Shy, S. L.; Hong, Chao-Sin; Wu, Cheng-San; Chen, S. J.; Wu, Hung-Yu; Ting, Yung-Chiang


    SixNy/Ni thin film green mask blanks were developed , and are now going to be used to replace general chromium film used for binary mask as well as to replace molydium silicide embedded material for AttPSM for I-line (365 nm), KrF (248 nm), ArF (193 nm) and Contact/Proximity lithography. A bilayer structure of a 1 nm thick opaque, conductive nickel layer and a SixNy layer is proposed for binary and phase-shifting mask. With the good controlling of plasma CVD of SixNy under silane (50 sccm), ammonia (5 sccm) and nitrogen (100 sccm), the pressure is 250 mTorr. and RF frequency 13.56 MHz and power 50 W. SixNy has enough deposition latitude to meet the requirements as an embedded layer for required phase shift 180 degree, and the T% in 193, 248 and 365 nm can be adjusted between 2% to 20% for binary and phase shifting mask usage. Ni can be deposited by E-gun, its sheet resistance Rs is less than 1.435 kΩ/square. Jeol e-beam system and I-line stepper are used to evaluate these thin film green mask blanks, feature size less than 200 nm half pitch pattern and 0.558 μm pitch contact hole can be printed. Transmission spectrums of various thickness of SixNy film are inspected by using UV spectrometer and FTIR. Optical constants of the SixNy film are measured by n & k meter and surface roughness is inspected by using Atomic Force Microscope (AFM).

  1. Phase shift reflectometry for wafer inspection

    Peng, Kuang; Cao, Yiping; Li, Hongru; Sun, Jianfei; Bourgade, Thomas; Asundi, Anand Krishna


    In 3D measurement, specular surfaces can be reconstructed by phase shift reflectometry and the system configuration is simple. In this paper, a wafer is measured for industrial inspection to make sure the quality of the wafer by calibrating, phase unwrapping, slope calculation and integration. The profile result of the whole wafer can be reconstructed and it is a curve. As the height of the structures on the wafer is the target we are interested in, by fitting and subtracting the curve surface, the structures on the wafer can be observed on the flat surface. To confirm the quality farther, a part of the wafer is captured and zoomed in to be detected so that the difference between two structures can be observed better.

  2. Maximum likelihood estimation of phase-type distributions

    Esparza, Luz Judith R

    This work is concerned with the statistical inference of phase-type distributions and the analysis of distributions with rational Laplace transform, known as matrix-exponential distributions. The thesis is focused on the estimation of the maximum likelihood parameters of phase-type distributions ...

  3. High-speed optical phase-shifting apparatus

    Zortman, William A.


    An optical phase shifter includes an optical waveguide, a plurality of partial phase shifting elements arranged sequentially, and control circuitry electrically coupled to the partial phase shifting elements. The control circuitry is adapted to provide an activating signal to each of the N partial phase shifting elements such that the signal is delayed by a clock cycle between adjacent partial phase shifting elements in the sequence. The transit time for a guided optical pulse train between the input edges of consecutive partial phase shifting elements in the sequence is arranged to be equal to a clock cycle, thereby enabling pipelined processing of the optical pulses.

  4. A novel random phase-shifting digital holographic microscopy method


    This paper proposes a new method that reconstructs the information of specimen by using random phase shift step in digital holographic microscopy (DHM). The principles of the method are described and discussed in detail. In practical experiment, because the phase shifter is neither perfectly linear nor calibrated, digital holograms with inaccurate phase shift step are recorded by the charge-coupled device (CCD). The phase could be accurately reconstructed from the recorded digital holograms by using the random phase-shifting algorithm, which makes up for reconstructed phase error caused by ordinary phase-shifting algorithm. The phase aberration compensation is also discussed. In order to verify the flexibility of the proposed method, numerical simulation of random phase-shifting DHM was carried out. The simulation results illustrated that the presented method is effective when the phase shift step is unknown or random in DHM.

  5. Phase shift estimation in interferograms with unknown phase step

    Dalmau, Oscar; Rivera, Mariano; Gonzalez, Adonai


    We first present two closed formulas for computing the phase shift in interferograms with unknown phase step. These formulas obtain theoretically the exact phase step in fringe pattern without noise and only require the information in two pixels of the image. The previous formulas allows us to define a functional that yields an estimate of the phase step in interferograms corrupted by noise. In the experiment we use the standard Least Square formulation which also yields a closed formula, although the general formulation admits a robust potential. We provide two possible implementations of our approach, one in which the sites can be randomly selected and the other in which we can scan the whole image. The experiments show that the proposed algorithm presents the best results compared with state of the art algorithms.

  6. Phase shift extraction algorithm based on Euclidean matrix norm.

    Deng, Jian; Wang, Hankun; Zhang, Desi; Zhong, Liyun; Fan, Jinping; Lu, Xiaoxu


    In this Letter, the character of Euclidean matrix norm (EMN) of the intensity difference between phase-shifting interferograms, which changes in sinusoidal form with the phase shifts, is presented. Based on this character, an EMN phase shift extraction algorithm is proposed. Both the simulation calculation and experimental research show that the phase shifts with high precision can be determined with the proposed EMN algorithm easily. Importantly, the proposed EMN algorithm will supply a powerful tool for the rapid calibration of the phase shifts.

  7. Model-based phase-shifting interferometer

    Liu, Dong; Zhang, Lei; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian


    A model-based phase-shifting interferometer (MPI) is developed, in which a novel calculation technique is proposed instead of the traditional complicated system structure, to achieve versatile, high precision and quantitative surface tests. In the MPI, the partial null lens (PNL) is employed to implement the non-null test. With some alternative PNLs, similar as the transmission spheres in ZYGO interferometers, the MPI provides a flexible test for general spherical and aspherical surfaces. Based on modern computer modeling technique, a reverse iterative optimizing construction (ROR) method is employed for the retrace error correction of non-null test, as well as figure error reconstruction. A self-compiled ray-tracing program is set up for the accurate system modeling and reverse ray tracing. The surface figure error then can be easily extracted from the wavefront data in forms of Zernike polynomials by the ROR method. Experiments of the spherical and aspherical tests are presented to validate the flexibility and accuracy. The test results are compared with those of Zygo interferometer (null tests), which demonstrates the high accuracy of the MPI. With such accuracy and flexibility, the MPI would possess large potential in modern optical shop testing.

  8. Superresolved phase-shifting Gabor holography by CCD shift

    Micó, V.; Granero, L.; Zalevsky, Z.; García, J.


    Holography in the Gabor regime is restricted to weak diffraction assumptions. Otherwise, diffraction prevents an accurate recovery of the object's complex wavefront. We have recently proposed a modified Gabor-like setup to extend Gabor's concept to any sample provided that it be non-diffusive. However, the resolution of the final image becomes limited as a consequence of the additional elements considered in the proposed setup. In this paper we present an experimental approach to overcome such a limitation in which the former configuration is used while the CCD camera is shifted to different off-axis positions in order to generate a synthetic aperture. Thus, once the whole image set is recorded and digitally processed for each camera position, we merge the resulting band-pass images into one image by assembling a synthetic aperture. Finally, a superresolved image is recovered by Fourier transformation of the information contained in the generated synthetic aperture. Experimental results validate our concepts for a gain in resolution of close to 2.

  9. Enhancement of entanglement transfer in a spin chain by phase shift control

    Maruyama, K; Nori, F


    We study the effect of a phase shift on the amount of transferrable two-spin entanglement in a spin chain. We consider a ferromagnetic Heisenberg/XY spin chain, both numerically and analytically, and two mechanisms to generate a phase shift, the Aharonov-Casher effect and the Dzyaloshinskii-Moriya interaction. In both cases, the maximum attainable entanglement is shown to be significantly enhanced, suggesting its potential usefulness in quantum information processing.

  10. A self-tuning phase-shifting algorithm for interferometry.

    Estrada, Julio C; Servin, Manuel; Quiroga, Juan A


    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.

  11. Quantum Key Distribution Network Based on Differential Phase Shift

    WANG Wan-Ying; WANG Chuan; WEN Kai; LONG Gui-Lu


    Using a series of quantum correlated photon pairs, we propose a theoretical scheme for any-to-any multi-user quantum key distribution network based on differential phase shift. The differential phase shift and the different detection time slots ensure the security of our scheme against eavesdropping. We discuss the security under the intercept-resend attack and the source replacement attack.

  12. Generalized eikonal treatment of the Gouy phase shift.

    Yang, Jun; Winful, Herbert G


    We use a generalized refractive index that includes diffraction effects to show that the Gouy phase shift can be seen as an intensity averaged optical path difference between the generalized eikonal and the geometrical eikonal. This approach generalizes previous treatments to include the effects of phase distortion and confirms the role of transverse spatial confinement in the Gouy shift.

  13. Regime shifts in annual maximum rainfall across Australia - implications for intensity-frequency-duration (IFD) relationships

    Verdon-Kidd, D. C.; Kiem, A. S.


    Rainfall intensity-frequency-duration (IFD) relationships are commonly required for the design and planning of water supply and management systems around the world. Currently, IFD information is based on the "stationary climate assumption" that weather at any point in time will vary randomly and that the underlying climate statistics (including both averages and extremes) will remain constant irrespective of the period of record. However, the validity of this assumption has been questioned over the last 15 years, particularly in Australia, following an improved understanding of the significant impact of climate variability and change occurring on interannual to multidecadal timescales. This paper provides evidence of regime shifts in annual maximum rainfall time series (between 1913-2010) using 96 daily rainfall stations and 66 sub-daily rainfall stations across Australia. Furthermore, the effect of these regime shifts on the resulting IFD estimates are explored for three long-term (1913-2010) sub-daily rainfall records (Brisbane, Sydney, and Melbourne) utilizing insights into multidecadal climate variability. It is demonstrated that IFD relationships may under- or over-estimate the design rainfall depending on the length and time period spanned by the rainfall data used to develop the IFD information. It is recommended that regime shifts in annual maximum rainfall be explicitly considered and appropriately treated in the ongoing revisions of the Engineers Australia guide to estimating and utilizing IFD information, Australian Rainfall and Runoff (ARR), and that clear guidance needs to be provided on how to deal with the issue of regime shifts in extreme events (irrespective of whether this is due to natural or anthropogenic climate change). The findings of our study also have important implications for other regions of the world that exhibit considerable hydroclimatic variability and where IFD information is based on relatively short data sets.

  14. Nondestructive testing by ESPI and quasi phase shift gradient technique

    Pang, Linyong; Wu, Xiaoping


    A new nondestructive testing (NDT) technique, which is based on Electronic Speckle Pattern Interferometry (ESPI) and digital image processing with quasi phase shift and gradient technique, is presented. A simple phase reduction algorithm is developed, which replaced an accurate phase shifter. Compared with other phase shift techniques, this method is insensitive to environmental vibration and air disturbance, has visible procedures and results allows the object to move slowly during the inspection procedure, does not need phase unwrapping, and has a quick image processing speed. As an application, this NDT technique is used to detect defects in composite materials and the resulting deformation phase gradient image shows a better visual effect than normal ESPI.

  15. Phase-shifting interferometric holography of living cells

    Giel, Dominik M.; Fratz, Markus; Brandenburg, Albrecht


    We present a phase-shifting holographic set-up for the microscopic imaging of adherent cells. The superposition of an object wave field and a reference wave is recorded on a digital sensor with three reference wave phases. The reference phases are then recovered by statistical analysis of the recorded intensities. Subsequently, the object wave phase is calculated by the generalized phase shifting algorithm. After phase unwrapping and background subtraction, the phase shift introduced by the adherent cell culture is reconstructed. As the interferograms are recorded in the image plane of the microsope objective, the full lateral resolution is achieved in contrast to off-axis holography where the reconstruction requires numerical propagation for the separation of 0 th and 1 st order. Our approach uses three arbitrary unknown reference phases and poses thus minimum requirements on the mechanical and thermal stability of the set-up. We give preliminary results of images from a Vero cell line and pollen grains.

  16. A New Phase-Shifted Cascade High Voltage Inverter

    Lau Eng Tin


    This paper presents a unique novel design of the phase-shifted cascade high voltage inverter. Thehigh voltage inverter utilizes fewer power switches and supplies a balance load. The usage of phase shifttransformer and phase shifting SPWM ensures that input and output harmonic wave content is low and outputvoltage change (du/dt) has a low rate, meeting all the requirements of the power authorities. The most out-standing feature is the energy saving with very fast cost recovery.

  17. Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy

    Cheema, M Imran; Hayat, Ahmad A; Peter, Yves-Alain; Armani, Andrea M; Kirk, Andrew G


    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...

  18. An Improvement of Spatial Carrier Phase-shifting Method

    QIAN Kemao; WU Xiaoping


    Spatial-carrier phase-shifting method (SCPM) retrieves the phase distribution from carrier interferograms by assuming that the phases of the processed pixel and its adjacent pixels are uniform,which introduces considerable theoretical error. A new method is presented in this paper to improve the SCPM accuracy: (1) A quadric curve is used to describe the phase distribution of the adjacent pixels; (2) The linear and quadric terms of the phase are considered as phase shifter errors; (3)Suitable phase shifting algorithms insensitive to these errors are selected. Two "5-step" algorithms are used and their properties are analyzed. An example ofphase retrieving by SCPM is given and the result shows that SCPM has high theoretical accuracy. With the potential high accuracy, ability of measuring dynamic phase andcomputational simplicity, SCPM will become a much more useful phase measurement method.

  19. Wavelength Phase-shift Dual-diffraction Interferometer

    Geng-An Jiang


    Full Text Available This paper presents a wavelength phase-shift dual-diffraction interferometer for the displacement measurement. The measurement system is divided into two parts. On the part of the optical configuration, the grating displacement is converted into the phase of the light based on Doppler effect. By means of the dual-diffraction design, the phase sensitivity corresponding to the grating shift is enhanced. The second part is the phase analysis system. Because of the unbalance optical path design and the modulated wavelength, the wavelength phase-shift technique is developed for analyzing the phase variation resulted from the grating displacement. The experimental results demonstrate that this system has good stability and repeatability.

  20. Precision phase-shifting applied to fiber Bragg gratings

    Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin


    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...

  1. Precision phase-shifting applied to fiber Bragg gratings

    Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin


    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...

  2. Research on Quantum Searching Algorithms Based on Phase Shifts

    ZHONG Pu-Cha; BAO Wan-Su


    @@ One iterative in Grover's original quantum search algorithm consists of two Hadamard-Walsh transformations, a selective amplitude inversion and a diffusion amplitude inversion. We concentrate on the relation among the probability of success of the algorithm, the phase shifts, the number of target items and the number of iterations via replacing the two amplitude inversions by phase shifts of an arbitrary φ = ψ(0 ≤φ, ψ≤ 2π). Then, according to the relation we find out the optimal phase shifts when the number of iterations is given. We present a new quantum search algorithm based on the optimal phase shifts of 1.018 after 0.5π /√M/N iterations. The new algorithm can obtain either a single target item or multiple target items in the search space with the probability of success at least 93.43%.

  3. KN Phase Shifts in Chiral SU(3) Quark Model

    HUANGFei; ZHANGZong-Ye; YUYou-Wen


    The isospin I = 0 and I = 1 kaon-nucleon S and P partial waves phase shifts have been studied in the chiral SU(3) quark model by solving a resonating group method equation. When the parameters of the chiral fields are taken in a reasonable region, the numerical results of S-wave are in good agreement with the experimental data, and the P-wave phase shifts can also be explained qualitatively by the calculation of only central force considered.


    Kalinin L.P.


    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.

  5. Phase shifting mask modulated laser patterning on graphene

    Gao, Fan; Liu, Fengyuan; Ye, Ziran; Sui, Chenghua; Yan, Bo; Cai, Pinggen; Lv, Bin; Li, Yun; Chen, Naibo; Zheng, Youdou; Shi, Yi


    A one-step graphene patterning method is developed in this paper. A phase shifting mask is used to modulate incident laser beam spatially and generate graphene patterns by laser heating. Periodic graphene nanoribbon and nanomesh structures are fabricated by employing 1D and 2D phase shifting masks, respectively. The noncontact, simple procedure, easy handling and economic properties of this method make it promising towards graphene-based device fabrication.

  6. The Gouy phase shift in nonlinear interactions of waves

    Lastzka, Nico; Schnabel, Roman


    We theoretically analyze the influence of the Gouy phase shift on the nonlinear interaction between waves of different frequencies. We focus on χ(2)interaction of optical fields, e.g. through birefringent crystals, and show that focussing, stronger than suggested by the Boyd-Kleinman factor, can further improve nonlinear processes. An increased value of 3.32 for the optimal focussing parameter for a single pass process is found. The new value builds on the compensation of the Gouy phase shift by a spatially varying, instead constant, wave vector phase mismatch. We analyze the single-ended, singly resonant standing wave nonlinear cavity and show that in this case the Gouy phase shift leads to an additional phase during backreflection. Our numerical simulations may explain ill-understood experimental observations in such devices.

  7. Absolute surface metrology with a phase-shifting interferometer for incommensurate transverse spatial shifts.

    Bloemhof, E E


    We consider the detailed implementation and practical utility of a novel absolute optical metrology scheme recently proposed for use with a phase-shifting interferometer (PSI). This scheme extracts absolute phase differences between points on the surface of the optic under test by differencing phase maps made with slightly different transverse spatial shifts of that optic. These absolute phase (or height) differences, which for single-pixel shifts are automatically obtained in the well-known Hudgin geometry, yield the underlying absolute surface map by standard wavefront reconstruction techniques. The PSI by itself maps surface height only relative to that of a separate reference optic known or assumed to be flat. In practice, even relatively high-quality (and expensive) transmission flats or spheres used to reference a PSI are flat or spherical only to a few dozen nanometers peak to valley (P-V) over typical 4 in. apertures. The new technique for removing the effects of the reference surface is in principle accurate as well as simple, and may represent a significant advance in optical metrology. Here it is shown that transverse shifts need not match the pixel size; somewhat counterintuitively, the single-pixel spatial resolution of the PSI is retained even when transverse shifts are much coarser. Practical considerations for shifts not necessarily commensurate with pixel size, and broader applications, are discussed.

  8. High-speed phase-shifting interferometry using triangular prism for time-resolved temperature measurement.

    Shoji, Eita; Komiya, Atsuki; Okajima, Junnosuke; Kawamura, Hiroshi; Maruyama, Shigenao


    This study proposes a high-speed phase-shifting interferometer with an original optical prism. This phase-shifting interferometer consists of a polarizing Mach-Zehnder interferometer, an original optical prism, a high-speed camera, and an image-processing unit for a three-step phase-shifting technique. The key aspect of the application of the phase-shifting technique to high-speed experiments is an original prism, which is designed and developed specifically for a high-speed phase-shifting technique. The arbaa prism splits an incident beam into four output beams with different information. The interferometer was applied for quantitative visualization of transient heat transfer. In order to test the optical system for measuring high-speed phenomena, the temperature during heat conduction was measured around a heated thin tungsten wire (diameter of 5 μm) in water. The visualization area is approximately 90  μm×210  μm, and the spatial resolution is 3.5 μm at 300,000 fps of the maximum temporal resolution with a high-speed camera. The temperature fields around the heated wire were determined by converting phase-shifted data using the inverse Abel transform. Finally, the measured temperature distribution was compared with numerical calculations to validate the proposed system; a good agreement was obtained.

  9. Hydrological and vegetation shifts in the Wallacean region of central Indonesia since the Last Glacial Maximum

    Wicaksono, Satrio A.; Russell, James M.; Holbourn, Ann; Kuhnt, Wolfgang


    Precipitation is the most important variable of Indonesian climate, yet there are substantial uncertainties about past and future hydroclimate dynamics over the region. This study explores vegetation and rainfall and associated changes in atmospheric circulation during the past 26,000 years in Wallacea, a biogeographical area in central Indonesia, wedged between the Sunda and Sahul shelves and known for its exceptionally high rainforest biodiversity. We use terrestrial plant biomarkers from sediment cores retrieved from Mandar Bay, off west Sulawesi, to reconstruct changes in Wallacean vegetation and climate since the Last Glacial Maximum (LGM). Enriched leaf wax carbon isotope (δ13Cwax) values recorded in Mandar Bay during the LGM, together with other regional vegetation records, document grassland expansion, implying a regionally dry, and possibly more seasonal, glacial climate. Depleted leaf wax deuterium isotope (δDwax) values in Mandar Bay during the LGM, and low reconstructed precipitation isotope compositions from nearby sites, reveal an intensified Austral-Asian summer monsoon circulation and a southward shift of the mean position of the Intertropical Convergence Zone, likely due to strong southern hemisphere summer insolation and the presence of large northern hemisphere ice sheets. Mandar Bay δ13Cwax was anti-correlated with δDwax during the LGM and the last deglaciation, but was positively correlated during most of the Holocene, indicating time-varying controls on the isotopic composition of rainfall in this region. The inundation event of the Sunda Shelf and in particular the opening of the Java Sea and Karimata Strait between 9.4 and 11.1 thousand years ago might have provided new moisture sources for regional convection and/or influenced moisture source trajectories, providing the trigger for shifts in atmospheric circulation and the controls on precipitation isotope compositions from the LGM to the Holocene.

  10. Measurement of Phase Shift by Using a DSP

    Petr KOČÍ


    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.

  11. Linear approximation for measurement errors in phase shifting interferometry

    van Wingerden, Johannes; Frankena, Hans J.; Smorenburg, Cornelis


    This paper shows how measurement errors in phase shifting interferometry (PSI) can be described to a high degree of accuracy in a linear approximation. System error sources considered here are light source instability, imperfect reference phase shifting, mechanical vibrations, nonlinearity of the detector, and quantization of the detector signal. The measurement inaccuracies resulting from these errors are calculated in linear approximation for several formulas commonly used for PSI. The results are presented in tables for easy calculation of the measurement error magnitudes for known system errors. In addition, this paper discusses the measurement error reduction which can be achieved by choosing an appropriate phase calculation formula.

  12. Digital phase-shifting atomic force microscope Moire method

    Liu Chiaming; Chen Lienwen [Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, 70101 (China)


    In this study, the digital atomic force microscope (AFM) Moire method with phase-shifting technology is established to measure the in-plane displacement and strain fields. The Moire pattern is generated by the interference between the specimen grating and the virtual reference grating formed by digital image processes. The overlapped image is filtered by two-dimensional wavelet transformation to obtain the clear interference Moire patterns. The four-step phase-shifting method is realized by translating the phase of the virtual reference grating from 0 to 2{pi}. The principle of the digital AFM Moire method and the phase-shifting technology are described in detail. Experimental results show that this method is convenient to use and efficient in realizing the microscale measurement.

  13. Impact of Nanograting Phase-Shift on Light Absorption Enhancement in Plasmonics-Based Metal-Semiconductor-Metal Photodetectors

    Narottam Das


    Full Text Available The finite difference time-domain (FDTD method is used to simulate the light absorption enhancement in a plasmonic metal-semiconductor-metal photodetector (MSM-PD structure employing a metal nanograting with phase shifts. The metal fingers of the MSM-PDs are etched at appropriate depths to maximize light absorption through plasmonic effects into a subwavelength aperture. We also analyse the nano-grating phase shift and groove profiles obtained typically in our experiments using focused ion beam milling and atomic force microscopy and discuss the dependency of light absorption enhancement on the nano-gratings phase shift and groove profiles inscribed into MSM-PDs. Our simulation results show that the nano-grating phase shift blue-shifts the wavelength at which the light absorption enhancement is maximum, and that the combined effects of the nano-grating groove shape and phase shift degrade the light absorption enhancement by up to 50%.

  14. Characterization of optical quantum circuits using resonant phase shifts

    Poot, Menno


    We demonstrate that important information about linear optical circuits can be obtained through the phase shift induced by integrated optical resonators. As a proof of principle, the phase of an unbalanced Mach-Zehnder interferometer is determined. Then the method is applied to a complex optical circuit designed for linear optical quantum computation. In this controlled-NOT gate with qubit initialization and tomography stages, the relative phases are determined as well as the coupling ratios of its directional couplers.

  15. DSPI system based on spatial carrier phase shifting technique

    Wang, Yonghong; Li, Junrui; Sun, Jianfei; Yang, Lianxiang


    Digital Speckle Pattern Interferometry (DSPI) is an optical method for measuring small displacement and deformation. It allows whole field, non-contacting measurement of micro deformation. Traditional Temporal phase shifting has been used for quantitative analyses in DSPI. The technique requires the recording of at least three phase-shifted interferograms, which must be taken sequentially. This can lead to disturbances by thermal and mechanical fluctuations during the required recording time. In addition, fast object deformations cannot be detected. In this paper a DSPI system using Spatial Carrier Phase Shifting (SCPS) technique is introduced, which is useful for extracting quantitative displacement data from the system with only two interferograms. The sensitive direction of this system refers to the illumination direction and observation direction. The frequencies of the spatial carrier relates to the angle between reference light and observation direction. Fourier transform is adopted in the digital evaluation to filter out the frequencies links to the deformation of testing object. The phase is obtained from the complex matrix formed by inverse Fourier transform, and the phase difference and deformation are calculated subsequently. Comparing with conventional temporal phase shifting, the technique can achieve measuring the vibration and transient deformation of testing object. Experiment set-ups and results are presented in this paper, and the experiment results have shown the effectiveness and advantages of the SCPS technique.

  16. Precise determination of lattice phase shifts and mixing angles

    Lu, Bing-Nan; Lähde, Timo A.; Lee, Dean; Meißner, Ulf-G.


    We introduce a general and accurate method for determining lattice phase shifts and mixing angles, which is applicable to arbitrary, non-cubic lattices. Our method combines angular momentum projection, spherical wall boundaries and an adjustable auxiliary potential. This allows us to construct radial lattice wave functions and to determine phase shifts at arbitrary energies. For coupled partial waves, we use a complex-valued auxiliary potential that breaks time-reversal invariance. We benchmark our method using a system of two spin-1/2 particles interacting through a finite-range potential with a strong tensor component. We are able to extract phase shifts and mixing angles for all angular momenta and energies, with precision greater than that of extant methods. We discuss a wide range of applications from nuclear lattice simulations to optical lattice experiments.

  17. Anomalous phase shift in a twisted quantum loop

    Taira, Hisao [Division of Applied Physics, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan); Shima, Hiroyuki, E-mail: [Department of Applied Mathematics 3, LaCaN, Universitat Politecnica de Catalunya (UPC), Barcelona 08034 (Spain)


    The coherent motion of electrons in a twisted quantum ring is considered to explore the effect of torsion inherent to the ring. Internal torsion of the ring composed of helical atomic configuration yields a non-trivial quantum phase shift in the electrons' eigenstates. This torsion-induced phase shift causes novel kinds of persistent current flow and an Aharonov-Bohm-like conductance oscillation. The two phenomena can occur even when no magnetic flux penetrates inside the twisted ring, thus being in complete contrast with the counterparts observed in untwisted rings.

  18. An in situ method for diagnosing phase shifting interferometry

    Shao, J.; Ma, D.; Zhang, H.; Xie, Y.


    Current diagnosing phase shifting interferometry is a time and funds consuming process. Hence a brief and effective method is necessary to satisfy the real-time testing. In this paper, mathematical solutions for errors were deduced from the difference of intensity patterns. Based on the diversity of error distributions, an effective method for distinguishing and diagnosing the error sources is proposed and verified by an elaborative designed simulation. In the actual comparison experiment, vibration, phase-shift error and intensity fluctuation were imposed to demonstrate this method. The results showed that this method can be applied into the real-time measurement and provide an in situ diagnosing technique.

  19. Single and Multiple Phase Shifts Tilted Fiber Bragg Gratings

    Christophe Caucheteur


    Full Text Available The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a simple wavelength independent spectral tailoring of this class of devices.

  20. Phase shifts of the paired wings of butterfly diagrams

    Ke-Jun Li; Hong-Fei Liang; Wen Feng


    Sunspot groups observed by the Royal Greenwich Observatory/US Air Force/NOAA from 1874 May to 2008 November and the Carte Synoptique solar filaments from 1919 March to 1989 December are used to investigate the relative phase shift of the paired wings of butterfly diagrams of sunspot and filament activities.Latitudinal migration of sunspot groups(or filaments)does asynchronously occur in the northern and southern hemispheres,and there is a relative phase shift between the paired wings of their butterfly diagrams in a cycle,making the paired wings spatially asymmetrical on the solar equator.It is inferred that hemispherical solar activity strength should evolve in a similar way within the paired wings of a butterfly diagram in a cycle,demonstrating the paired wings phenomenon and showing the phase relationship between the northern and southern hemispherical solar activity strengths,as well as a relative phase shift between the paired wings of a butterfly diagram,which should bring about almost the same relative phase shift of hemispheric solar activity strength.

  1. The Phase Shifts of the Paired Wings of Butterfly Diagrams

    Li, Kejun; Feng, Wen


    Sunspot groups observed by Royal Greenwich Observatory/US Air Force/NOAA from May 1874 to November 2008 and the Carte Synoptique solar filaments from March 1919 to December 1989 are used to investigate the relative phase shift of the paired wings of butterfly diagrams of sunspot and filament activities. Latitudinal migration of sunspot groups (or filaments) does asynchronously occur in the northern and southern hemispheres, and there is a relative phase shift between the paired wings of their butterfly diagrams in a cycle, making the paired wings spatially asymmetrical on the solar equator. It is inferred that hemispherical solar activity strength should evolve in a similar way within the paired wings of a butterfly diagram in a cycle, making the paired wings just and only keep the phase relationship between the northern and southern hemispherical solar activity strengths, but a relative phase shift between the paired wings of a butterfly diagram should bring about an almost same relative phase shift of hemis...

  2. Phase extraction from two phase-shifting fringe patterns using spatial-temporal fringes method.

    Zhu, Ronggang; Li, Bo; Zhu, Rihong; He, Yong; Li, Jianxin


    Phase extraction from phase-shifting fringe patterns with unknown phase shift values is a valuable but challenging task, especially when there are only two frames of fringes. In this paper, a phase demodulation method based on the spatial-temporal fringes (STF) method is proposed, where two phase shift fringes with linear carrier are fused into one STF image, and then the measured phase can be extracted from its frequency spectrum. The algorithm is deduced by extending the traditional STF theory with at least three frames of fringes to the two frames case. In the simulations, its performance is compared with the classical Fourier Transform method, and the different carrier and phase step conditions are analyzed where the accuracy can be ensured in most cases. The algorithm is also validated by the experiment, where the reliable result can be given even if the phase shift changes within a wide range.

  3. Upward Altitudinal Shifts in Habitat Suitability of Mountain Vipers since the Last Glacial Maximum

    Yousefi, Masoud; Ahmadi, Mohsen; Nourani, Elham; Behrooz, Roozbeh; Rajabizadeh, Mehdi; Geniez, Philippe; Kaboli, Mohammad


    We determined the effects of past and future climate changes on the distribution of the Montivipera raddei species complex (MRC) that contains rare and endangered viper species limited to Iran, Turkey and Armenia. We also investigated the current distribution of MRC to locate unidentified isolated populations as well as to evaluate the effectiveness of the current network of protected areas for their conservation. Present distribution of MRC was modeled based on ecological variables and model performance was evaluated by field visits. Some individuals at the newly identified populations showed uncommon morphological characteristics. The distribution map of MRC derived through modeling was then compared with the distribution of protected areas in the region. We estimated the effectiveness of the current protected area network to be 10%, which would be sufficient for conserving this group of species, provided adequate management policies and practices are employed. We further modeled the distribution of MRC in the past (21,000 years ago) and under two scenarios in the future (to 2070). These models indicated that climatic changes probably have been responsible for an upward shift in suitable habitats of MRC since the Last Glacial Maximum, leading to isolation of allopatric populations. Distribution will probably become much more restricted in the future as a result of the current rate of global warming. We conclude that climate change most likely played a major role in determining the distribution pattern of MRC, restricting allopatric populations to mountaintops due to habitat alterations. This long-term isolation has facilitated unique local adaptations among MRC populations, which requires further investigation. The suitable habitat patches identified through modeling constitute optimized solutions for inclusion in the network of protected areas in the region. PMID:26367126

  4. AC system stabilization via phase shift transformer with thyristor commutation

    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)


    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.

  5. Singular value demodulation of phase-shifted holograms

    Lopes, Fernando


    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; 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.

  6. Measurement and Calibration of PSD with Phase-shifting Interferometers

    Lehan, J. P.


    We discuss the instrumental aspects affecting the measurement accuracy when determining PSD with phase shifting interferometers. These include the source coherence, optical train effects, and detector effects. The use of a carefully constructed calibration standard will also be discussed. We will end with a recommended measurement and data handling procedure.

  7. Dual-wavelength in-line phase-shifting interferometry based on two dc-term-suppressed intensities with a special phase shift for quantitative phase extraction.

    Xu, Xiaoqing; Wang, Yawei; Xu, Yuanyuan; Jin, Weifeng


    To efficiently promote the phase retrieval in quantitative phase imaging, a new approach of quantitative phase extraction is proposed based on two intensities with dual wavelength after filtering the corresponding dc terms for each wavelength, in which a special phase shift is used. In this approach, only the combination of the phase-shifting technique and subtraction procedures is needed, and no additional algorithms are required. The thickness of the phase object can be achieved from the phase image, which is related to the synthetic beat wavelength. The feasibility of this method is verified by the simulated experiments of the optically transparent objects.

  8. Analytic estimation of subsample spatial shift using the phases of multidimensional analytic signals.

    Basarab, Adrian; Liebgott, Hervé; Delachartre, Philippe


    In this correspondence, a method of analytic subsample spatial shift estimation based on an a priori n-D signal model is proposed. The estimation uses the linear phases of n analytic signals defined with the multidimensional Hilbert transform. This estimation proposes: i) an analytic solution to the n-D shift estimation and ii) an estimation without processing complex cross-correlation function or cross-spectra between signals contrary to most phase shift estimators. The method provides better performance in estimating subsample shifts than two classical estimators, one using the maximum of cross-correlation function and the other seeking the zero of the complex correlation function phase. Two delay estimators using the in-phase and quadrature-phase components of signals are also compared to our estimator. Like most estimators using the complex signal phases, the estimator proposed herein presents the advantage of unaltered accuracy when low sampled signals are used. Moreover, we show that this method can be applied to motion tracking with ultrasound images. Thus, included in a block-based motion estimation method and tested with ultrasound data, this estimator provides an analytical solution to the translation estimation problem.

  9. Cylindrical PVF2 film based fiber optic phase modulator - Phase shift nonlinearity and frequency response

    Sudarshanam, V. S.; Claus, Richard O.


    A new cylindrical coil configuration for polyvinylidene flouride (PVF2) film based fiber optic phase modulator is studied for the frequency response and nonlinearity of phase shift at the resonance frequency. This configuration, hitherto unapproached for PVF2 film modulators, offers resonance at well defined, controllable and higher frequencies than possible for the flat-strip configuration. Two versions of this configuration are presented that differ strongly in both the resonance frequency and the phase shift nonlinearity coefficient.

  10. Auto-compensating differential phase shift quantum key distribution

    Han, X; Zhou, C; Zeng, H; Han, Xiaohong; Wu, Guang; Zhou, Chunyuan; Zeng, Heping


    We propose an auto-compensating differential phase shift scheme for quantum key distribution with a high key-creation efficiency, which skillfully makes use of automatic alignment of the photon polarization states in optical fiber with modified Michelson interferometers composed of unequal arms with Faraday mirrors at the ends. The Faraday-mirrors-based Michelson interferometers not only function as pulse splitters, but also enable inherent compensation of polarization mode dispersion in the optic-fiber paths at both Alice's and Bob's sites. The sequential pulses encoded by differential phase shifts pass through the quantum channel with the same polarization states, resulting in a stable key distribution immune to the polarization mode dispersion in the quantum channel. Such a system features perfect stability and higher key creation efficiency over traditional schemes.

  11. Coating induced phase shift and impact on Euclid imaging performance

    Gaspar Venancio, Luis M.; Carminati, Lionel; Lorenzo Alvarez, Jose; Amiaux, Jérôme; Bonino, Luciana; Salvignol, Jean-Christophe; Vavrek, Roland; Laureijs, René; Short, Alex; Boenke, Tobias; Strada, Paulo


    The challenging constraints imposed on the Euclid telescope imaging performances have driven the design, manufacturing and characterisation of the multi-layers coatings of the dichroic. Indeed it was found that the coatings layers thickness inhomogeneity will introduce a wavelength dependent phase-shift resulting in degradation of the image quality of the telescope. Such changes must be characterized and/or simulated since they could be non-negligible contributors to the scientific performance accuracy. Several papers on this topic can be found in literature, however the results can not be applied directly to Euclid's dichroic coatings. In particular an applicable model of the phase-shift variation with the wavelength could not be found and was developed. The results achieved with the mathematical model are compared to experimental results of tests performed on a development prototype of the Euclid's dichroic.

  12. Linear sinusoidal phase-shifting method resistant to non-sinusoidal phase error

    Haihua Cui; Wenhe Liao; Ning Dai; Xiaosheng Cheng


    Non-sinusoidal phase error is common in structured light three-dimensional (3D) shape measurement system, thus we perform theoretical and experimental analyses of such error. The number of non-sinusoidal waveform errors in a 2tt phase period is the same as the number of steps of the phase-shifting algorithm; no errors occur within the one-phase period. Based on our findings, a new structured light method, the linear sinusoidal phase-shifting method (LSPS), that is resistant to non-sinusoidal phase error is proposed. Experiments show that the non-sinusoidal waveform error is reduced to an almost negligible level (0.001 rad) using the proposed LSPS.%Non-sinusoidal phase error is common in structured light three-dimensional (3D) shape measurement system,thus we perform theoretical and experimental analyses of such error.The number of non-sinusoidal waveform errors in a 2π phase period is the same as the number of steps of the phase-shifting algorithm; no errors occur within the one-phase period.Based on our findings,a new structured light method,the linear sinusoidal phase-shifting method (LSPS),that is resistant to non-sinusoidal phase error is proposed.Experiments show that the non-sinusoidal waveform error is reduced to an almost negligible level (0.001 rad)using the proposed LSPS.

  13. Radar Subsurface Imaging by Phase Shift Migration Algorithm

    Zhang, Hui; Benedix, Wolf-Stefan; Plettemeier, Dirk; Ciarletti, Valérie


    In this paper the phase shift migration based Syn- thetic Aperture Radar (SAR) is described and applied on radar imaging for dual polarized ground penetrating radar system (GPR). Conventional techniques for SAR imaging focusing use the matched filter concept and convolve the measurement data with a filter impulse response (convolution kernel) which is modified by the range. In fact, conventional techniques for SAR imaging technique can be considered as ray-tracing based SAR imaging technique....

  14. I=2 Pion Scattering Phase Shift with Wilson Fermions

    :,; Fukugita, M; Hashimoto, S; Ishikawa, K-I; Ishizuka, N; Iwasaki, Y; Kanaya, K; Kaneko, T; Kuramashi, Y; Lesk, V; Okawa, M; Taniguchi, Y; Ukawa, A; Yoshié, T


    We present results of phase shift for I=2 $S$-wave $\\pi\\pi$ system with the Wilson fermions in the quenched approximation. The finite size method proposed by L\\"uscher is employed, and calculations are carried out at $\\beta=5.9$ ($a^{-1}=1.934(16)$ GeV from $m_\\rho$) on $24^3 \\times 60$, $32^3 \\times 60$, and $48^3 \\times 60$ lattices.

  15. Cavity Attenuated Phase Shift (CAPS) Monitor Instrument Handbook

    Sedlacek, Arthur J [Brookhaven National Lab. (BNL), Upton, NY (United States)


    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.

  16. Vector Modulator for Phase Shifting in Passive Beamforming Wireless Systems



    Full Text Available This paper proposes vector modulator for changing the phase of a signal in passive beamforming system. Vector modulator is used to perform a phase shift function with added benefit of amplitude control. It is used to improve the directivity of RF waves in Wireless systems. Vector modulator is implemented for a center frequency of 902.5 MHz. The simulation is performed for individual blocks of the vector modulator and for vector modulator with JFET and MOSFET as controlling device in the variable attenuator of the vector modulator.

  17. Two-wavelength phase shift interferometry to characterize ballistic features

    Pagano, Glenn W.; Mann, Christopher J.


    We apply two-wavelength phase shifting interferometry to generate 3D surface profile maps of spent bullet cartridge cases. From the captured interferograms, an optimized algorithm was used to calculate a phase profile from which a precise digital surface map of the cartridge casing may be produced. This 3D surface profile is used to enhance a firearms examiner's ability to uniquely identify distinct features or toolmarks imprinted on the casing when the weapon is fired. These features play a key role in the matching process of ballistic forensic examination.

  18. Improved phase-shifting diffraction interferometer for microsphere topography measurements

    Guodong Liu; Binghui Lu; Heyi Sun; Bingguo Liu; Fengdong Chen; Zhitao Zhuang


    In this study,an improved phase-shifting diffraction interferometer for measuring the surface topography of a microsphere is developed.A common diode-pumped solid state laser is used as the light source to facilitate apparatus realization,and a new polarized optical arrangement is designed to filter the bias light for phase-shifting control.A pinhole diffraction self-calibration method is proposed to eliminate systematic errors introduced by optical elements.The system has an adjustable signal contrast and is suitable for testing the surface with low reflectivity.Finally,a spherical ruby probe of a coordinate measuring machine is used as an example tested by the new phase-shifting diffraction interferometer system and the WYKO scanning white light interferometer for experimental comparison.The measured region presents consistent overall topography features,and the resulting peak-to-valley value of 84.43 nm and RMS value of 18.41 nm are achieved.The average roughness coincides with the manufacturer's specification value.

  19. An atomic clockwork using phase dependent energy shifts

    De Munshi, D; Mukherjee, M


    A frequency stabilized laser referenced to an unperturbed atomic two level system acts as the most accurate clock with femtosecond clock ticks. For any meaningful use, a Femtosecond Laser Frequency Comb (FLFC) is used to transfer the atomic clock accuracy to electronically countable nanosecond clock ticks. Here we propose an alternative clockwork based on the phenomenon that when an atomic system is slowly evolved in a cyclic path, the atomic energy levels gather some phase called the geometric phase. This geometric phase dependent energy shift has been used here to couple the two frequency regimes in a phase coherent manner. It has also been shown that such a technique can be implemented experimentally, bypassing the highly involved setup of a FLFC.

  20. Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications

    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)


    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.

  1. A phase retrieval method of interferograms add-subtracting based on two-step phase shifting.

    Xu, Yuanyuan; Wang, Yawei; Ji, Ying; Jin, Weifeng; Bu, Min; Shang, Xuefu


    A phase retrieval method is introduced in quantitative phase imaging (QPI) based on two-step phase-shifting technique. By acquiring two measured interferograms and calculating the addition and subtraction between them, the quantitative phase information can be directly retrieved. This method is illustrated by both theory and simulation experiments of a ball. The results of the simulation and the experiment of the red blood cell show a good agreement, demonstrating its application for studying cells.

  2. Fluctuational shift of nematic-isotropic phase transition temperature

    Kats, E. I.


    In this work we discuss a macroscopic counterpart to the microscopic mechanism of the straightening dimer mesogens conformations, proposed recently by S.M. Saliti, M.G.Tamba, S.N. Sprunt, C.Welch, G.H.Mehl, A. Jakli, J.T. Gleeson (Phys. Rev. Lett. 116, 217801 (2016)) to explain their experimental observation of the unprecedentedly large shift of the nematic-isotropic transition temperature. Our interpretation is based on singular longitudinal fluctuations of the nematic order parameter. Since these fluctuations are governed by the Goldstone director fluctuations they exist only in the nematic state. External magnetic field suppresses the singular longitudinal fluctuations of the order parameter (similarly as it is the case for the transverse director fluctuations, although with a different scaling over the magnetic field). The reduction of the fluctuations changes the equilibrium value of the modulus of the order parameter in the nematic state. Therefore it leads to additional (with respect to the mean field contribution) fluctuational shift of the nematic-isotropic transition temperature. Our mechanism works for any nematic liquid crystals, however the magnitude of the fluctuational shift increases with decrease of the Frank elastic moduli. Since some of these moduli supposed to be anomalously small for so-called bent-core or dimer nematic liquid crystals, just these liquid crystals are promising candidates for the observation of the predicted fluctuational shift of the phase transition temperature.

  3. LASER: A Maximum Likelihood Toolkit for Detecting Temporal Shifts in Diversification Rates From Molecular Phylogenies

    Daniel L. Rabosky


    Full Text Available Rates of species origination and extinction can vary over time during evolutionary radiations, and it is possible to reconstruct the history of diversification using molecular phylogenies of extant taxa only. Maximum likelihood methods provide a useful framework for inferring temporal variation in diversification rates. LASER is a package for the R programming environment that implements maximum likelihood methods based on the birth-death process to test whether diversification rates have changed over time. LASER contrasts the likelihood of phylogenetic data under models where diversification rates have changed over time to alternative models where rates have remained constant over time. Major strengths of the package include the ability to detect temporal increases in diversification rates and the inference of diversification parameters under multiple rate-variable models of diversification. The program and associated documentation are freely available from the R package archive at

  4. Phase shift in atom interferometry due to spacetime curvature

    Asenbaum, Peter; Kovachy, Tim; Brown, Daniel D; Hogan, Jason M; Kasevich, Mark A


    We present a single-source dual atom interferometer and utilize it as a gradiometer for precise gravitational measurements. The macroscopic separation between interfering atomic wave packets (as large as 16 cm) reveals the interplay of recoil effects and gravitational curvature from a nearby Pb source mass. The gradiometer baseline is set by the laser wavelength and pulse timings, which can be measured to high precision. Using a long drift time and large momentum transfer atom optics, the gradiometer reaches a resolution of $3 \\times 10^{-9}$ s$^{-2}$ per shot and measures a 1 rad phase shift induced by the source mass.

  5. Time for a Paradigm Shift? Exploring Maximum Standards in International Intellectual Property Protection

    Henning Grosse Ruse-Khan


    Full Text Available International intellectual property (IP protection is at the heart of controversies over the impact of economic interests on social or environmental concerns. Some see IP rights as unduly encroaching upon human rights and societal interests, others argue for stronger enforcement and additional exclusivity to incentivize new innovations and creations. Underlying these debates is the perception that international IP treaties set out minimum standards of protection - which presumably allow for additional protection with only the sky being the limit. This article challenges this view and explores the idea of maximum standards or ceilings within the existing body of international IP law. It looks at the relation between IP treaties and subsequent agreements or national laws which offer stronger protection. In particular, within the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS, an important qualification may serve as a door opener for ceilings: While additional IP protection may not go beyond mandatory limits within TRIPS, the qualification not to “contravene” TRIPS is unlikely to safeguard TRIPS flexibilities against TRIPS-plus norms. The article further identifies and examines the rationales for maximum standards in international IP protection as: (1 Legal security and predictability about the boundaries of protection; (2 the global protection of users’ rights; and (3 the free movement of goods, services and information. Examples of mandatory limits in the existing IP treaties and in ongoing initiatives can implement these. However, most of the relevant treaty norms are optional. The article concludes with some observations on the need for more comprehensive and precise maximum standards.

  6. Phase classification by mean shift clustering of multispectral materials images.

    Martins, Diego Schmaedech; Josa, Victor M Galván; Castellano, Gustavo; da Costa, José A T Borges


    A mean-shift clustering (MSC) algorithm is introduced as a valuable alternative to perform materials phase classification from multispectral images. As opposed to other multivariate statistical techniques, such as factor analysis or principal component analysis (PCA), clustering techniques directly assign a class label to each pixel, so that their outputs are phase segmented images, i.e., there is no need for an additional segmentation algorithm. On the other hand, as compared to other clustering procedures and classification methods, such as segmentation by thresholding of multiple spectral components, MSC has the advantages of not requiring previous knowledge of the number of data clusters and not assuming any shape for these clusters, i.e., neither the number nor the composition of the phases must be previously known. This makes MSC a particularly useful tool for exploratory research, assisting phase identification of unknown samples. Visualization and interpretation of the results are also simplified, since the information content of the output image does not depend on the particular choice of the content of the color channels.We applied MSC to the analysis of two sets of X-ray maps acquired in scanning electron microscopes equipped with energy-dispersive detection systems. Our results indicate that MSC is capable of detecting additional phases, not clearly identified through PCA or multiple thresholding, with a very low empirical reject rate.

  7. A New High Frequency Injection Method Based on Duty Cycle Shifting without Maximum Voltage Magnitude Loss

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand


    The conventional high frequency signal injection method is to superimpose a high frequency voltage signal to the commanded stator voltage before space vector modulation. Therefore, the magnitude of the voltage used for machine torque production is limited. In this paper, a new high frequency...... injection method, in which high frequency signal is generated by shifting the duty cycle between two neighboring switching periods, is proposed. This method allows injecting a high frequency signal at half of the switching frequency without the necessity to sacrifice the machine fundamental voltage...... amplitude. This may be utilized to develop new position estimation algorithm without involving the inductance in the medium to high speed range. As an application example, a developed inductance independent position estimation algorithm using the proposed high frequency injection method is applied to drive...

  8. Reconstruction of purely absorbing, absorbing and phase-shifting, and strong phase-shifting objects from their single-shot in-line holograms

    Latychevskaia, Tatiana


    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.

  9. Fluid shifts during initial phase of immersion diuresis in man

    Khosla, S.S.; Dubois, A.B.


    The object was to study shifts in man during the 1st hour of immersion diuresis. Control experiments were done on subjects lying down in air for 4 h with and without vasopressin. During immersion up to the neck, seven of nine subjects had significant diuresis and natriuresis. In the first 20 min of sitting in 33 C water, a hemodilution of 2% of blood volume was observed. As diuresis progressed, hemoconcentration began. When vasopressin was given just before immersion to prevent the diuresis, the hemodilution observed was greater and lasted longer. Thus the hematocrit fell by 1.7 U, plasma osmolality by 6.0 mosmol/kg, plasma proteins by 0.33 g/100 ml, and plasma sodium by 5.0 meq/l. It is concluded that a hemodilution of about 4% of blood volume occurs during the early phase of immersion and the degree of hyposmolality observed suggests that the fluid shifted was more hyposmotic than the interstitial fluid alone, possibly because some intracellular water may have shifted into the bloodstream during immersion.

  10. Chromatic Dispersion Monitoring Method Based on Phase Shift Technique

    L(U) Chengang; WU Xing; ZENG Lizhu; QIN Yifan; ZU Peng; HU Zhixiong; GE Chunfeng


    The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1 532. 16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1 549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1 310 nm, a 1 310/1 550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).

  11. Computer-Generated Holograms for Recording Multiple-Phase-Shifte Fiber Bragg Grating Corrugations


    A new method of fabricating multiple-phase-shifte fiber Bragg grating by CGHs is proposed. The authors present an example of such CGH by which a section multiple-phase-shifte fiber Bragg grating with two π/2 phase shifts and grating length L=21.2 μm was produced. The authors describe the production process and finally give an example of a reconstructed fiber grating with two phase-shifts.

  12. Rapid extraction of the phase shift of the cold-atom interferometer via phase demodulation

    程冰; 王兆英; 许翱鹏; 王启宇; 林强


    Generally, the phase of the cold-atom interferometer is extracted from the atomic interference fringe, which can be obtained by scanning the chirp rate of the Raman lasers at a given interrogation time T . If mapping the phase shift for each T with a series of measurements, the extraction time is limited by the protocol of each T measurement, and therefore increases dramatically when doing fine mapping with a small step of T . Here we present a new method for rapid extraction of the phase shift via phase demodulation. By using this method, the systematic shifts can be mapped though the whole interference area. This method enables quick diagnostics of the potential cause of the phase shift in specific time. We demonstrate experimentally that this method is effective for the evaluation of the systematic errors of the cold atomic gravimeter. The systematic phase error induced by the quadratic Zeeman effect in the free-falling region is extracted by this method. The measured results correspond well with the theoretic prediction and also agree with the results obtained by the fringe fitting method for each T .

  13. Improving the resolution in phase-shifting Gabor holography by CCD shift

    Granero, L.; Micó, V.; Zalevsky, Z.; García, J.; Javidi, B.


    Holography dates back to the year when Dennis Gabor reported on a method to avoid spherical aberration and to improve image quality in electron microscopy. Gabor's two-step holographic method was pioneer but suffered from three major drawbacks: the reconstructed image is affected by coherent noise, the twin image problem of holography that also affects the final image quality, and a restricted sample range (weak diffraction assumption) for preserving the holographic behavior of the method. Nowadays, most of those drawbacks have been overcome and new capabilities have been added due to the replacement of the classical recording media (photographic plate) by digital sensors (CCD and CMOS cameras). But in the Gabor' regime, holography is restricted to weak diffraction assumptions because otherwise, diffraction prevents an accurate recovery of the object's complex wavefront. In this contribution, we present an experimental approach to overcome such limitation and improve final image resolution. We use the phase-shifting Gabor configuration while the CCD camera is shifted to different off-axis positions in order to capture a bigger portion of the diffracted wavefront. Thus, once the whole image set is recorded and digitally processed for each camera's position, we merge the resulting band-pass images into one image by assembling a synthetic aperture. Finally, a superresolved image is recovered by Fourier transformation of the information contained in the generated synthetic aperture. Experimental results are provided using a USAF resolution test target and validating our concepts for a gain in resolution of close to 2.

  14. Picosecond phase shift measurements at 358 MHz using synchrotron radiation

    Sabersky, A.P.; Munro, I.H.


    Properties of synchrotron radiation from SPEAR are reviewed. The power--frequency spectrum of source and photomultiplier tube is measured with a spectrum analyzer. The decay time of a single fluorescent species can be deduced by measuring the phase delay between excitation and fluorescence radiation modulated at a single suitable frequency. It is possible to characterize completely the time (impulse) response or the complex frequency response of a linear system with only phase measurements. A number of test experiments were made by using apparatus designed for time-resolved fluorescence emission anisotropy studies of tryptophan in proteins. Phase shifts were produced by insertion of water-filled quartz cells into the beam and by the introduction of a thick glass slab. The total optical path length could also be altered by linear motion of the phototube. The results yielded 4.7 +- 0.5 degrees per cm of motion. It was concluded that this procedure can be used to study short atomic and molecular fluorescence lifetimes. 3 figures. (RWR)

  15. Analysis of a novel phase-shifted soft switch converter

    蒋志宏; 黄立培; 张义


    In this paper, on the basis of the phase-shifted controlled zero-voltage-switch (ZVS) full-bridge converter with pulse width modulation (PWM), a novel zero-voltage and zero-current switch (ZVZCS) PWM converter using a simple auxiliary circuit was designed. The ZVZCS soft switch is achieved by the resonance among the resisting electromagnetic deflection capacitor, the capacitor of the simple auxiliary network and the leakage inductor of transformer. There are no dissipation devices of the saturation inductor and the auxiliary switch in the converter, meantime the capacitor of the auxiliary circuit is also used to clamp the voltage of the rectifier, and there is no additional clamped circuit. There is no big circulating current in the converter, all the active and passive devices work on the condition of the low current and voltage stress, and the proposed converter has wide load range and small duty loss.

  16. Eikonal phase shift analyses of carbon-carbon scattering

    Townsend, L. W.; Wilson, J. W.; Bidasaria, H. B.


    A high-energy double-folding optical potential approximation to the exact nucleus-nucleus multiple-scattering series is used in determining eikonal phase shifts for carbon-carbon scattering at 204.2, 242.7, and 288.6 MeV. The double-folding potentials are derived by folding the energy-dependent free nucleon-nucleon interaction with densities for the projectile and target; these latter are obtained by unfolding the finite nucleon charge density from harmonic-well carbon charge distributions. The charge parameters for these distributions are taken from the results of electron scattering experiments. Predictions are made for total, reaction, and elastic differential cross sections using standard partial wave analysis for the scattering of identical particles and are then compared with recent experimental results. Excellent agreement is obtained despite the absence of arbitrarily adjusted parameters in the theory.

  17. Rapid phase-shift reversal on a Jamaican coral reef

    Idjadi, Joshua A.; Lee, Sarah C.; Bruno, John F.; Precht, William F.; Allen-Requa, Laurie; Edmunds, Peter J.


    Many Caribbean reefs have experienced a phase-shift in community structure, the principle features being a decline in coral cover and an increase in macroalgal biomass. However, one Jamaican reef—Dairy Bull on the north shore near Discovery Bay—is once again dominated by scleractinian corals and several key species have returned. Living coral cover at 6 8 m depth at Dairy Bull has doubled over the past 9 years and is now ~54%. The absolute cover of Acropora cervicornis was <1% in 1995, but increased to ~11% by January 2004. During this time the cover of macroalgae decreased by 90%, from 45 to 6%. We speculate that long-lived colonies of Montastraea annularis may have facilitated the recovery of this reef by providing structural refugia.

  18. Phase shift analysis in Nimtz experiments on tunneling and transmission

    Jakiel, J


    For the wave representing particle traveling through any layer system we calculate appropriate phase shifts comparing two methods. One bases on the standard scattering theory and is well known another uses unimodular but not unitary M-monodromy matrix. Both methods are not equivalent due to different boundary condition - in the one barrier case there exist analytical expressions showing difference. Authors generalize results to many barrier (layer) system. Instead of speaking about superluminarity we introduce into the quantum mechanics so called by us "hurdling problem": can a quantum hurdler in one dimension be faster then a sprinter (without obstacles) at the same distance. Relations between wavefunction arguments and delay or advance are shown for Nimtz systems.

  19. Low energy scattering phase shifts for meson-baryon systems

    Detmold, William


    In this work, we calculate meson-baryon scattering phase shifts in four channels using lattice QCD methods. From a set of calculations at four volumes, corresponding to spatial sizes of 2, 2.5, 3, and 4 fm, and a pion mass of m_pi ~ 390 MeV, we determine the scattering lengths and effective ranges for these systems at the corresponding quark masses. We also perform the calculation at a lighter quark mass, m_pi ~ 230 MeV, on the largest volume. Using these determinations, along with those in previous work, we perform a chiral extrapolation of the scattering lengths to the physical point after correcting for the effective range contributions using the multi-volume calculations performed at m_pi ~ 390 MeV.

  20. Direct unwrapped phase estimation in phase shifting interferometry using Levenberg–Marquardt algorithm

    Kulkarni, Rishikesh; Rastogi, Pramod


    An algorithm for the direct unwrapped phase estimation from the linearly phase shifted interferograms is presented. The temporal fringe intensity along each pixel is represented as a function of fringe amplitude, phase step and the searched phase. These parameters are estimated in the nonlinear least squares sense using the Levenberg–Marquardt algorithm. The proposed method allows the masked interferograms to be handled using a pixel selection approach to provide the appropriate initial conditions at a given pixel utilizing the estimated parameters at one of its neighboring pixels, which results in direct unwrapped phase estimation. Simulation results are provided to evaluate the performance of the proposed method as a function of noise power, spatially varying phase step, number of interferograms and phase step detuning error. The experimental results are also provided in the case of a holographic interferometry setup.

  1. Maximum likelihood estimation of the parameters of nonminimum phase and noncausal ARMA models

    Rasmussen, Klaus Bolding


    The well-known prediction-error-based maximum likelihood (PEML) method can only handle minimum phase ARMA models. This paper presents a new method known as the back-filtering-based maximum likelihood (BFML) method, which can handle nonminimum phase and noncausal ARMA models. The BFML method is id...... is identical to the PEML method in the case of a minimum phase ARMA model, and it turns out that the BFML method incorporates a noncausal ARMA filter with poles outside the unit circle for estimation of the parameters of a causal, nonminimum phase ARMA model...

  2. Review of recent developments of spatial phase-shift digital shearography

    Xie, Xin; Li, Xiaona; Chen, Xu; Yang, Lianxiang


    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.

  3. Use of melatonin in circadian rhythm disorders and following phase shifts

    Skene, DJ; Deacon, S; Arendt, J.


    Following abrupt phase shifts (real or simulated time zone changes, night shift work) there is desynchronisation between the internal circadian rhythms (including melatonin) and the external environment with consequent disturbances in sleep, mood and performance. In humans the pineal hormone melatonin has phase-shifting and resynchronising properties with regard to a number of circadian rhythms. Suitably timed melatonin adrninstration hastened adaptation to phase shift and significantly impro...

  4. Fizeau simultaneous phase-shifting interferometry based on extended source

    Wang, Shanshan; Zhu, Qiudong; Hou, Yinlong; Cao, Zheng


    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.

  5. Real-time microscopic phase-shifting profilometry.

    Van der Jeught, Sam; Soons, Joris A M; Dirckx, Joris J J


    A real-time microscopic profilometry system based on digital fringe projection and parallel programming has been developed and experimentally tested. Structured light patterns are projected onto an object through one pathway of a stereoscopic operation microscope. The patterns are deformed by the shape of the object and are then recorded with a high-speed CCD camera placed in the other pathway of the microscope. As the optical pathways of both arms are separated and reach the same object point at a relative angle, the recorded patterns allow the full-field object height variations to be calculated and the three-dimensional shape to be reconstructed by employing standard triangulation techniques. Applying proper hardware triggering, the projector-camera system is synchronized to capture up to 120 unique deformed line patterns per second. Using standard four-step phase-shifting profilometry techniques and applying graphics processing unit programming for fast phase wrapping, scaling, and visualization, we demonstrate the capability of the proposed system to generate 30 microscopic height maps per second. This allows the qualitative depth perception of the stereomicroscope operator to be enhanced by live quantitative height measurements with depth resolutions in the micrometer range.

  6. Three-Phase Phase-Shifting Transformer with Regulation in Neutral Point

    Kalinin L.P.


    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.

  7. Highly Selective Hg (II Ion Detection Based on Linear Blue-Shift of the Maximum Absorption Wavelength of Silver Nanoparticles

    Li Ping Wu


    Full Text Available A new method of detecting Hg (II ion with silver nanoparticles (AgNPs is developed in this contribution. When Hg (II ions were added into AgNPs solution, the solution displayed rapid color change and blue shift of the maximum absorption wavelength (Δλ, which was in proportion to the Hg (II ion concentration over the range of 2.0 × 10−7–6.0 × 10−6 mol/L, with detection limit (3σ of 6.6 × 10−9 mol/L. Under the same experimental conditions, other metal ions did not interfere. Thus, we propose a rapid, simple and highly selective method for detecting Hg (II ion.

  8. Quadrature phase-shift error analysis using a homodyne laser interferometer.

    Gregorcic, Peter; Pozar, Tomaz; Mozina, Janez


    The influence of quadrature phase shift on the measured displacement error was experimentally investigated using a two-detector polarizing homodyne laser interferometer with a quadrature detection system. Common nonlinearities, including the phase-shift error, were determined and effectively corrected by a robust data-processing algorithm. The measured phase-shift error perfectly agrees with the theoretically determined phase-shift error region. This error is systematic, periodic and severely asymmetrical around the nominal displacement value. The main results presented in this paper can also be used to assess and correct the detector errors of other interferometric and non-interferometric displacement-measuring devices based on phase-quadrature detection.

  9. Generalized phase-shifting algorithms: error analysis and minimization of noise propagation.

    Ayubi, Gastón A; Perciante, César D; Di Martino, J Matías; Flores, Jorge L; Ferrari, José A


    Phase shifting is a technique for phase retrieval that requires a series of intensity measurements with certain phase steps. The purpose of the present work is threefold: first we present a new method for generating general phase-shifting algorithms with arbitrarily spaced phase steps. Second, we study the conditions for which the phase-retrieval error due to phase-shift miscalibration can be minimized. Third, we study the phase extraction from interferograms with additive random noise, and deduce the conditions to be satisfied for minimizing the phase-retrieval error. Algorithms with unevenly spaced phase steps are discussed under linear phase-shift errors and additive Gaussian noise, and simulations are presented.

  10. Atmospheric Turbulence Compensation with Laser Phase Shifting Interferometry

    Rabien, S; Genzel, R; Davies, R I; Ott, T


    Laser guide stars with adaptive optics allow astronomical image correction in the absence of a natural guide star. Single guide star systems with a star created in the earth's sodium layer can be used to correct the wavefront in the near infrared spectral regime for 8-m class telescopes. For possible future telescopes of larger sizes, or for correction at shorter wavelengths, the use of a single guide star is ultimately limited by focal anisoplanatism that arises from the finite height of the guide star. To overcome this limitation we propose to overlap coherently pulsed laser beams that are expanded over the full aperture of the telescope, traveling upwards along the same path which light from the astronomical object travels downwards. Imaging the scattered light from the resultant interference pattern with a camera gated to a certain height above the telescope, and using phase shifting interferometry we have found a method to retrieve the local wavefront gradients. By sensing the backscattered light from tw...

  11. Optimisation of Transmission Systems by use of Phase Shifting Transformers

    Verboomen, J.


    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.

  12. Alternating phase shift mask technology for 65nm logic applications

    Chakravorty, Kishore K.; Henrichs, Sven; Qiu, Wei; Chavez, Joas L.; Liu, Yi-Ping; Ghadiali, Firoz; Yung, Karmen; Wilcox, Nathan; Silva, Mary; Ma, Jian; Qu, Ping; Irvine, Brian; Yun, Henry; Cheng, Wen-Hao; Farnsworth, Jeff


    Alternating Phase Shift Mask (APSM) Technology has been developed and successfully implemented for the poly gate of 65nm node Logic application at Intel. This paper discusses the optimization of the mask design rules and fabrication process in order to enable high volume manufacturability. Intel's APSM technology is based on a dual sided trenched architecture. To meet the stringent OPC requirements associated with patterning of narrow gates required for the 65nm node, Chrome width between the Zero and Pi aperture need to be minimized. Additionally, APSM lithography has an inherently low MEEF that furthermore, drives a narrower Chrome line as compared to the Binary approach. The double sided trenched structure with narrow Chrome lines are mechanically vulnerable and prone to damage when exposed to conventional mask processing steps. Therefore, new processing approaches were developed to minimize the damage to the patterned mask features. For example, cleaning processes were optimized to minimize Chrome & quartz damage while retaining the cleaning effectiveness. In addition, mask design rules were developed which ensured manufacturability. The narrow Chrome regions between the zero and Pi apertures severely restrict the tolerance for the placement of the second level resists edges with respect to the first level. UV Laser Writer based resist patterning capability, capable of providing the required Overlay tolerance, was developed, An AIMS based methodology was used to optimize the undercut and minimize the aerial image CD difference between the Zero and Pi apertures.

  13. Alternating phase-shifted mask for logic gate levels, design, and mask manufacturing

    Liebmann, Lars W.; Graur, Ioana C.; Leipold, William C.; Oberschmidt, James M.; O'Grady, David S.; Regaill, Denis


    While the benefits of alternating phase shifted masks in improving lithographic process windows at increased resolution are well known throughout the lithography community, broad implementation of this potentially powerful technique has been slow due to the inherent complexity of the layout design and mask manufacturing process. This paper will review a project undertaken at IBM's Semiconductor Research and Development Center and Mask Manufacturing and Development facility to understand the technical and logistical issues associated with the application of alternating phase shifted mask technology to the gate level of a full microprocessor chip. The work presented here depicts an important milestone toward integration of alternating phase shifted masks into the manufacturing process by demonstrating an automated design solution and yielding a functional alternating phase shifted mask. The design conversion of the microprocessor gate level to a conjugate twin shifter alternating phase shift layout was accomplished with IBM's internal design system that automatically scaled the design, added required phase regions, and resolved phase conflicts. The subsequent fabrication of a nearly defect free phase shifted mask, as verified by SEM based die to die inspection, highlights the maturity of the alternating phase shifted mask manufacturing process in IBM's internal mask facility. Well defined and recognized challenges in mask inspection and repair remain and the layout of alternating phase shifted masks present a design and data preparation overhead, but the data presented here demonstrate the feasibility of designing and building manufacturing quality alternating phase shifted masks for the gate level of a microprocessor.

  14. Inverse effects of flowing phase-shift nanodroplets and lipid-shelled microbubbles on subsequent cavitation during focused ultrasound exposures.

    Zhang, Siyuan; Cui, Zhiwei; Xu, Tianqi; Liu, Pan; Li, Dapeng; Shang, Shaoqiang; Xu, Ranxiang; Zong, Yujin; Niu, Gang; Wang, Supin; He, Xijing; Wan, Mingxi


    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 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 exposures.

  15. GCR intensity during the sunspot maximum phase and the inversion of the heliospheric magnetic field

    Krainev, M; Kalinin, M; Svirzhevskaya, A; Svirzhevsky, N


    The maximum phase of the solar cycle is characterized by several interesting features in the solar activity, heliospheric characteristics and the galactic cosmic ray (GCR) intensity. Recently the maximum phase of the current solar cycle (SC) 24, in many relations anomalous when compared with solar cycles of the second half of the 20-th century, came to the end. The corresponding phase in the GCR intensity cycle is also in progress. In this paper we study different aspects of the sunspot, heliospheric and GCR behavior around this phase. Our main conclusions are as follows: 1) The maximum phase of the sunspot SC 24 ended in 06.2014, the development of the sunspot cycle being similar to those of SC 14, 15 (the Glaisberg minimum). The maximum phase of SC 24 in the GCR intensity is still in progress. 2) The inversion of the heliospheric magnetic field consists of three stages, characterized by the appearance of the global heliospheric current sheet (HCS), connecting all longitudes. In two transition dipole stages ...

  16. Three-frame generalized phase-shifting interferometry by a Euclidean matrix norm algorithm

    Xu, Yuanyuan; Wang, Yawei; Ji, Ying; Han, Hao; Jin, Weifeng


    Generalized phase-shifting interferometry (GPSI) is one of the most effective techniques in imaging of a phase object, in which phase retrieval is an essential and important procedure. In this paper, a simple and rapid algorithm for retrieval of the unknown phase shifts in three-frame GPSI is proposed. Using this algorithm, the value of phase shift can be calculated by a determinate formula consisting of three different Euclidean matrix norms of the intensity difference between two phase shifted interferograms, and then the phase can be retrieved easily. The algorithm has the advantages of freeing from the background elimination and less computation, since it only needs three phase-shifted interferograms without no extra measurements, the iterative procedure or the integral transformation. The reliability and accuracy of this algorithm were demonstrated by simulation and experimental results.

  17. Vibration-resistant phase retrieval method with contrast compensation for phase-shifting interferometry

    Liu, Qian; He, Huabin; Yuan, Daocheng; He, Jianguo; Ji, Fang


    Vibration hinders the application of phase-shifting interferometry (PSI) to on-machine test and large-aperture mirror measurement. The investigation of PSI fringe disturbed by vibration indicates that, besides tilt-shifting error, inter- and intra-frame contrast variation is significant. The contrast variation is another dominant error source in phase retrieval of PSI. An inter- and intra-frame contrast compensation method is proposed here to retrieve wavefront phase from interferograms subjected to vibration. The method constructs algebraic equations with interferogram data and solves equations using iterative procedures. Experiments validate its effectiveness and manifest its capability to suppress vibration-induced error over a large frequency region. To enhance the calculation efficiency, a spatial subsampling strategy is proposed. Practical testing shows that subsampling reduces calculation time exponentially and preserves retrieval accuracy and spatial resolution. The proposed method, of which the unique ability is compensating the tilt-shifting error and fringe blur caused by vibration, predicates an effective and low-cost solution for PSI applied in vibration.

  18. 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


    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.

  19. Absolute Definition of Phase Shift in the Elastic Scattering of a Particle from Compound Systems

    Temkin, A.


    The projection of the target wave function on the total wave function of a scattered particle interacting with the target system is used to define an absolute phase shift including any multiples of pi. With this definition of the absolute phase shift, one can prove rigorously in the limit of zero energy for s-wave electrons scattered from atomic hydrogen that the triplet phase shift must approach a nonzero multiple of pi. One can further show that at least one pi of this phase shift is not connected with the existence of a bound state of the H- ion.

  20. Parallel-quadrature phase-shifting digital holographic microscopy using polarization beam splitter.

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, Dvgln


    We present a digital holography microscopy technique based on parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography.

  1. Intrachannel cross-phase modulation-induced phase shift in high-speed dispersion-managed optical fiber transmission system

    Syed, Nitu; Faisal, Mohammad


    We investigate the intrachannel cross-phase modulation (IXPM)-induced phase shift in optical return-to-zero pulse propagating in a periodically dispersion-managed long-haul optical fiber transmission line. Necessary dynamical equations for various pulse parameters have been derived using variational analysis to estimate the phase shift. These equations are solved by the Runge-Kutta method. The analytical result is verified by numerical simulation based on split-step Fourier method. We therefore explore the effects of various parameters, such as transmission distance, input power, duty cycle, dispersion map strength, and residual dispersion, on phase shift for a 40 Gb/s single-channel transmission system. We also check the impact of variation of bit rate on phase shift. We find that IXPM-induced phase shift can be mitigated by proper adjustment of dispersion management and different pulse parameters like duty cycle, dispersion map strength, and peak power.

  2. Detection of cerebral hemorrhage in rabbits by time-difference magnetic inductive phase shift spectroscopy.

    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.

  3. Stokesian peristaltic pumping in a three-dimensional tube with a phase-shifted asymmetry

    Aranda, Vivian; Cortez, Ricardo; Fauci, Lisa


    Many physiological flows are driven by waves of muscular contractions passed along a tubular structure. This peristaltic pumping plays a role in ovum transport in the oviduct and in rapid sperm transport through the uterus. As such, flow due to peristalsis has been a central theme in classical biological fluid dynamics. Analytical approaches and numerical methods have been used to study flow in two-dimensional channels and three-dimensional tubes. In two dimensions, the effect of asymmetry due to a phase shift between the channel walls has been examined. However, in three dimensions, peristalsis in a non-axisymmetric tube has received little attention. Here, we present a computational model of peristaltic pumping of a viscous fluid in three dimensions based upon the method of regularized Stokeslets. In particular, we study the flow structure and mean flow in a three-dimensional tube whose asymmetry is governed by a single phase-shift parameter. We view this as a three-dimensional analog of the phase-shifted two-dimensional channel. We find that the maximum mean flow rate is achieved for the parameter that results in an axisymmetric tube. We also validate this approach by comparing our computational results with classical long-wavelength theory for the three-dimensional axisymmetric tube. This computational framework is easily implemented and may be adapted to more comprehensive physiological models where the kinematics of the tube walls are not specified a priori, but emerge due to the coupling of its passive elastic properties, force generating mechanisms, and the surrounding viscous fluid.

  4. Structured Light Based 3d Scanning for Specular Surface by the Combination of Gray Code and Phase Shifting

    Zhang, Yujia; Yilmaz, Alper


    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 advantages of our new

  5. High-order inertial phase shifts for time-domain atom interferometers

    Bongs, K; Kasevich, M A; Bongs, Kai; Launay, Romain; Kasevich, Mark A.


    High-order inertial phase shifts are calculated for time-domain atom interferometers. We obtain closed-form analytic expressions for these shifts in accelerometer, gyroscope, optical clock and photon recoil measurement configurations. Our analysis includes Coriolis, centrifugal, gravitational, and gravity gradient-induced forces. We identify new shifts which arise at levels relevant to current and planned experiments.

  6. Experimental demonstration of 360 tunable RF phase shift using slow and fast light effects

    Xue, Weiqi; Sales, Salvador; Capmany, Jose;


    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....

  7. Nonreciprocal phase shift caused by magnetic-thermal coupling of a polarization maintaining fiber optic gyroscope.

    Zhang, Dengwei; Zhao, Yuxiang; Fu, Wenlan; Zhou, Wenqing; Liu, Cheng; Shu, Xiaowu; Che, Shuangliang


    A theory for nonreciprocal phase shift caused by cross coupling generated in a polarization maintaining (PM) fiber optic gyroscope (FOG) under the combined action of magnetic and temperature fields is proposed. The magnetic-thermal coupling in the FOG originates from the interaction of the magnetic field, fiber twist, birefringence caused by thermal stress, and the intrinsic and bending birefringence of the fiber. The cross coupling changes with temperature. When the PM fiber has a diameter of 250 μm, beat length of 3 mm, length of 500 m, twist rate of 1  rad/m, and optical source wavelength of 1310 nm, the maximum degree of magnetic-thermal coupling generated by a 1 mT radial magnetic field within the temperature range of -20°C  to 60°C is -5.47%.

  8. Phase Noise Investigation of Maximum Likelihood Estimation Method for Airborne Multibaseline SAR Interferometry

    Magnard, C.; Small, D.; Meier, E.


    The phase estimation of cross-track multibaseline synthetic aperture interferometric data is usually thought to be very efficiently achieved using the maximum likelihood (ML) method. The suitability of this method is investigated here as applied to airborne single pass multibaseline data. Experimental interferometric data acquired with a Ka-band sensor were processed using (a) a ML method that fuses the complex data from all receivers and (b) a coarse-to-fine method that only uses the intermediate baselines to unwrap the phase values from the longest baseline. The phase noise was analyzed for both methods: in most cases, a small improvement was found when the ML method was used.

  9. Femtosecond laser fabrication of phase-shifted Bragg grating waveguides in fused silica.

    Grenier, Jason R; Fernandes, Luís A; Aitchison, J Stewart; Marques, Paulo V S; Herman, Peter R


    Phase-shifted Bragg grating waveguides (PSBGWs) were formed in bulk fused silica glass by femtosecond laser direct writing to produce narrowband (22±3)  pm filters at 1550 nm. Tunable π and other phase shifts generated narrow passbands in controlled positions of the Bragg stopband, while the accurate placement of multiple cascaded phase-shift regions yielded a rectangular-shaped bandpass filter. A waveguide birefringence of (7.5±0.3)×10(-5) is inferred from the polarization-induced spectral shifting of the PSBGW narrowband filters.

  10. The gravity-induced phase shift detected by high-Tc Josephson junctions

    HE Jian-e


    We derive from the Kaluza-Klein theory a formula for the gravity-induced phase shift around a circuit loop,which amounts to the order of 10-6 We propose experiments to detect this phase shift by using the high-Tc d-wave Josephson junction,which is included in a cuprate superconductor circuit loop.By rotating the loop around the horizontal axis,the gravity-induced phase shift can be detected as a frequency shift.These settings can also be used in turn to determine the gravitational constant.This method will be sensitive and accurate.

  11. Transmission spectra of coated phase shifted long-period fiber gratings

    GU Zheng-tian; ZHAO Xiao-yun; ZHANG Jiang-tao


    The transmission spectrum of the coated phase-shifted long-period fiber gratings (LPFGs) with single and multiple phase shifts is analyzed by the coupled-mode theory and the transfer matrix method, and the influences of the film parameters on the spectral characteristics are also studied. It is shown that these parameters will affect the LPFG filtering characteristics. The loss peak of transmission spectrum decreases with the increase of film thickness, and the peak position shifts with the film refractive index. Compared with the non-coated phase-shifted LPFG, the coated one has the similar desirable filtering characteristics, and it has a flexile ability to adjust the transmission properties.

  12. Separation of electrostatic and magnetic phase shifts using a modified transport-of-intensity equation

    Humphrey, E. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Phatak, C.; Petford-Long, A.K. [Argonne National Laboratory, Argonne, IL 60439 (United States); De Graef, M. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States)


    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. - Highlights: • We provide a new way to separate electrostatic and magnetic phase shifts in Lorentz microscopy. • We derive two new transport-of-intensity style equations, one for electrostatic phase shifts and the other for magnetic phase shifts. • We provide a new way to determine the longitudinal intensity derivative that automatically includes time reversal symmetry. • This approach allows for the Tikhonov regularization parameter to be selected for each phase shift separately. • We provide two example application on Permalloy and CoFeB patterned islands.

  13. 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 Univer

  14. Phase shift effects for fluid conveying pipes with non-ideal supports

    Dahl, Jonas; Thomsen, Jon Juel


    Vibrations of a fluid-conveying pipe with non-ideal supports are investigated with respect to phase shift effects. A numerical Galerkin approach is developed for this general problem, and the use of it exemplified with a investigation of phase shift effects from rotational damping at supports...

  15. Electromagnetic corrections to the hadronic phase shifts in low energy $\\pi^{+}p$ elastic scattering

    Gashi, A; Oades, G C; Rasche, G; Woolcock, W S


    We calculate the s and p-wave electromagnetic corrections which must be subtracted from the nuclear phase shifts obtained from the analysis of low energy pi+p elastic scattering data, in order to obtain hadronic phase shifts. We compare our results with earlier calculations and estimate the uncertainties in the corrections.

  16. Phase shift effects for fluid conveying pipes with non-ideal supports

    Dahl, Jonas; Thomsen, Jon Juel


    Vibrations of a fluid-conveying pipe with non-ideal supports are investigated with respect to phase shift effects. A numerical Galerkin approach is developed for this general problem, and the use of it exemplified with a investigation of phase shift effects from rotational damping at supports...

  17. Analyses and computations of asymmetric Z-scan for large phase shift from diffraction theory

    Liyong Ren(任立勇); Baoli Yao(姚保利); Xun Hou(侯洵); Liren Liu(刘立人); Changhe Zhou(周常河)


    Based on Fresnel-Kirchhoff diffraction theory, we set up a diffraction model of nonlinear optical media toGaussian beam, which can interpret the Z-scan phenomenon from a new way. This theory is not onlywell consistent with the conventional Z-scan theory in the case of small nonlinear phase shift, but alsocan fit for the lager nonlinear phase shift. Numeric computations indicate the shape of the Z-scan curveis greatly affected by the value of the nonlinear phase shift. The symmetric dispersion-like Z-scan curveis only valid for small nonlinear phase shift (|△φo| <π), but with increasing the nonlinear phase shift, thevalley of the transmittance is severely suppressed and the peak is greatly enhanced. Further calculationsshow some new interesting results.

  18. Coherent Detection of Optical Quadrature Phase-Shift Keying Signals With Carrier Phase Estimation

    Ly-Gagnon, Dany-Sebastien; Tsukamoto, Satoshi; Katoh, Kazuhiro; Kikuchi, Kazuro


    This paper describes a coherent optical receiver for demodulating optical quadrature phase-shift keying (QPSK) signals. At the receiver, a phase-diversity homodyne detection scheme is employed without locking the phase of the local oscillator (LO). To handle the carrier phase drift, the carrier phase is estimated with digital signal processing (DSP) on the homodyne-detected signal. Such a scheme presents the following major advantages over the conventional optical differential detection. First, its bit error rate (BER) performance is better than that of differential detection. This higher sensitivity can extend the reach of unrepeated transmission systems and reduce crosstalk between multiwavelength channels. Second, the optoelectronic conversion process is linear, so that the whole optical signal information can be postprocessed in the electrical domain. Third, this scheme is applicable to multilevel modulation formats such as M-array PSK and quadrature amplitude modulation (QAM). The performance of the receiver is evaluated through various simulations and experiments. As a result, an unrepeated transmission over 210 km with a 20-Gb/s optical QPSK signal is achieved. Moreover, in wavelength-division multiplexing (WDM) environment, coherent detection allows the filtering of a desired wavelength channel to reside entirely in the electrical domain, taking advantage of the sharp cutoff characteristics of electrical filters. The experiments show the feasibility to transmit polarization-multiplexed 40-Gb/s QPSK signals over 200 km with channel spacing of 16 GHz, leading to a spectral efficiency as high as 2.5 b/s/Hz.

  19. An estimation of the influence of force decrease on the mean power spectral frequency shift of the EMG during repetitive maximum dynamic knee extensions.

    Karlsson, J S; Ostlund, N; Larsson, B; Gerdle, B


    Frequency analysis of myoelectric (ME) signals, using the mean power spectral frequency (MNF), has been widely used to characterize peripheral muscle fatigue during isometric contractions assuming constant force. However, during repetitive isokinetic contractions performed with maximum effort, output (force or torque) will decrease markedly during the initial 40-60 contractions, followed by a phase with little or no change. MNF shows a similar pattern. In situations where there exist a significant relationship between MNF and output, part of the decrease in MNF may per se be related to the decrease in force during dynamic contractions. This study estimated force effects on the MNF shifts during repetitive dynamic knee extensions. Twenty healthy volunteers participated in the study and both surface ME signals (from the right vastus lateralis, vastus medialis, and rectus femoris muscles) and the biomechanical signals (force, position, and velocity) of an isokinetic dynamometer were measured. Two tests were performed: (i) 100 repetitive maximum isokinetic contractions of the right knee extensors, and (ii) five gradually increasing static knee extensions before and after (i). The corresponding ME signal time-frequency representations were calculated using the continuous wavelet transform. Compensation of the MNF variables of the repetitive contractions was performed with respect to the individual MNF-force relation based on an average of five gradually increasing contractions. Whether or not compensation was necessary was based on the shape of the MNF-force relationship. A significant compensation of the MNF was found for the repetitive isokinetic contractions. In conclusion, when investigating maximum dynamic contractions, decreases in MNF can be due to mechanisms similar to those found during sustained static contractions (force-independent component of fatigue) and in some subjects due to a direct effect of the change in force (force-dependent component of fatigue

  20. Noise suppression properties of an interferometer-based regenerator for differential phase-shift keying data.

    Elschner, Robert; de Melo, Alessandro Marques; Bunge, Christian-Alexander; Petermann, Klaus


    We studied the amplitude and phase noise suppression properties of an all-optical regenerator for differential phase-shift keying data. A detailed analytical investigation is performed and compared with numerical simulations for different working points. The results show that both amplitude and phase can be regenerated. However, simultaneous amplitude and phase noise suppression is possible only if the phase degradation is stronger than the amplitude degradation, for instance, due to nonlinear phase noise.

  1. Response of some pi-phase-shifted Bragg gratings to elevated pressure

    Bal, Harpreet K.; Dragomir, Nicoleta M.; Sidiroglou, Fotios; Wade, Scott A.; Baxter, Greg W.; Collins, Stephen F.


    The effect of pressures up to 200 kPa on pi-phase-shifted Bragg gratings was investigated in several types of fibers placed in a pressure chamber. Standard and alternative types of pi-phase shifted gratings were studied, and changes in reflection spectra caused by pressure changes were monitored. The alternative pi-phase shifted grating was fabricated using a phase mask with 536-nm pitch exhibiting features at twice the Bragg wavelength near 1552 nm due to the interleaved refractive index modulations along the fiber core with the periodicity of the phase mask. The three gratings studied exhibited quite different variation in Bragg wavelength with increased pressure for the different fiber types, and the alternative pi-phase-shifted grating in Corning HI 1060 FLEX fiber also suffered a significant change in the shape of the peaks.

  2. Linear systems theory for the analysis of phase-shifting algorithms

    Estrada, Julio C.; Servín, Manuel; Quiroga, Juan A.


    Phase-shifting algorithms are methods used for recovering the modulating phase of an interferogram sequence obtained by Phase Stepping Interferometry (PSI) techniques. Typically, the number of interferograms in a PSI sequence is from 3 to around 9 interferograms, although we can find algorithms that works with more than 9 interferograms. In this paper, we are going to show the analysis and design of phase-shifting algorithms from the point of view of the linear systems paradigm from digital signal processing. We will show how this paradigm describes in a general fashion the phase-shifting algorithm systems, and how we can easily design tunable phase-shifting algorithms using this simple scheme.

  3. Optical encryption of binary data information with 2-step phase-shifting digital holography

    Gil, Sang Keun; Byun, Hyun Joong; Lee, Hyun Jin; Jeon, Seok Hee; Jeong, Jong Rae


    We propose an optical encryption/decryption technique based on 2-step phase-shifting digital holography for a cipher system. The technique using 2-step phase-shifting digital holography is more efficient than 4-step phase-shifting digital holography because the 2-step method has less data than 4-step method to restore or transmit the encrypted data. In our system, 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or π/2 in the reference beam path and are recorded on CCD camera. The information data and the key are expressed with random binary amplitude and random phase. Digital hologram in this method is Fourier transform hologram and digitized with 256 gray-level. DC-term removal is essential to reconstruct and decrypt the original binary data information. The simulation shows that the proposed method gives good results for cipher system. The quantization error is also analyzed.

  4. Phase sensitivity in deformed-state superposition considering nonlinear phase shifts

    Berrada, K.


    We study the problem of the phase estimation for the deformation-state superposition (DSS) under perfect and lossy (due to a dissipative interaction of DSS with their environment) regimes. The study is also devoted to the phase enhancement of the quantum states resulting from a generalized non-linearity of the phase shifts, both without and with losses. We find that such a kind of superposition can give the smallest variance in the phase parameter in comparison with usual Schrödinger cat states in different order of non-linearity even if for a larger average number of photons. Due to the significance of how a system is quantum correlated with its environment in the construction of a scalable quantum computer, the entanglement between the DSS and its environment is investigated during the dissipation. We show that partial entanglement trapping occurs during the dynamics depending on the kind of deformation and mean photon number. These features make the DSS with a larger average number of photons a good candidate for implementation of schemes of quantum optics and information with high precision.

  5. Profilometry with Grating Projection Based on One-step Phase Shift


    An optical technique for 3-D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3-D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one-step phase shift algorithm.In comparison with traditional phase-shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.

  6. All-solid-state microscopic interferometer with frequencyvariation and phase-shifting capability

    TIAN Jin-dong; ZHAO Xiao-bo; PENG Xiang


    A novel microscopic interferometry with ability of frequency-variation and phase-shifting is proposed for microstructures testing. By using acousto-optic technique, sequential carriers can be generated with different spatial frequencies so that the temporal phase unwrapping method can be applied for decoding the height information. Combined with phase-shifting technique realized by spatial light modulator, this method is especially suitable for interferometric measurement with high precision and large dynamic range.

  7. Large phase shift of spatial soliton in lead glass by cross-phase modulation in pump-signal geometry

    Shou, Qian; Zhang, Xiang; Hu, Wei; Guo, Qi


    We investigate the large phase shifts of the bi-color spatial soliton pair in a cylindrical lead glass rod. The theoretical study suggests a synchronous propagation of a strong pump beam and a weak signal beam under the required initial condition. We experimentally obtain a $\\pi$ phase shift of the signal beam by changing the power of the pump beam by about 14 mW around the soliton critical power, which agrees qualitatively with our theoretical result. The ratio of the phase shift rate of the signal soliton to that of the pump soliton shows a close match to the theoretical estimation.

  8. Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically turnable phase shifter

    Kim, T.-Y.; Hanawa, M.; Kim, Sun-Jong


    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 was suc...... was successfully demodulated by the proposed demodulator, showing clearly open eye diagrams as well as bit-error-free performance. Moreover, the phase of delayed optical signal can be tuned by the phase shifter that is controlled by a pumping light at around 980nm....

  9. Phase noise investigation of maximum likelihood estimation method for airborne multibaseline SAR interferometry

    Magnard, Christophe; Small, David; Meier, Erich


    The phase estimation of cross-track multibaseline synthetic aperture interferometric data is usually thought to be very efficiently achieved using the maximum likelihood (ML) method. The suitability of this method is investigated here as applied to airborne single pass multibaseline data. Experimental interferometric data acquired with a Ka-band sensor were processed using (a) a ML method that fuses the complex data from all receivers and (b) a coarse-to-fine method that only uses the interme...

  10. Enhanced high dynamic range 3D shape measurement based on generalized phase-shifting algorithm

    Wang, Minmin; Du, Guangliang; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie


    Measuring objects with large reflectivity variations across their surface is one of the open challenges in phase measurement profilometry (PMP). Saturated or dark pixels in the deformed fringe patterns captured by the camera will lead to phase fluctuations and errors. Jiang et al. proposed a high dynamic range real-time three-dimensional (3D) shape measurement method (Jiang et al., 2016) [17] that does not require changing camera exposures. Three inverted phase-shifted fringe patterns are used to complement three regular phase-shifted fringe patterns for phase retrieval whenever any of the regular fringe patterns are saturated. Nonetheless, Jiang's method has some drawbacks: (1) the phases of saturated pixels are estimated by different formulas on a case by case basis; in other words, the method lacks a universal formula; (2) it cannot be extended to the four-step phase-shifting algorithm, because inverted fringe patterns are the repetition of regular fringe patterns; (3) for every pixel in the fringe patterns, only three unsaturated intensity values can be chosen for phase demodulation, leaving the other unsaturated ones idle. We propose a method to enhance high dynamic range 3D shape measurement based on a generalized phase-shifting algorithm, which combines the complementary techniques of inverted and regular fringe patterns with a generalized phase-shifting algorithm. Firstly, two sets of complementary phase-shifted fringe patterns, namely the regular and the inverted fringe patterns, are projected and collected. Then, all unsaturated intensity values at the same camera pixel from two sets of fringe patterns are selected and employed to retrieve the phase using a generalized phase-shifting algorithm. Finally, simulations and experiments are conducted to prove the validity of the proposed method. The results are analyzed and compared with those of Jiang's method, demonstrating that our method not only expands the scope of Jiang's method, but also improves

  11. Numerical estimation of the total phase shift in complex spectral OCT in vivo imaging

    Cyganek, Marta; Wojtkowski, Maciej; Targowski, Piotr; Kowalczyk, Andrzej


    Complex Spectral Optical Tomography (CSOCT) in comparison to ordinary SOCT produces images free of parasitic mirror terms which results in double extension of the measurement range. This technique, however, requires the exact knowledge about the values of the introduced phase shifts in consecutive measurements. Involuntary object movements, which shift the phase from one measurement to another are always present in in vivo experiments. This introduces residual ghosts in cross-sectional images. Here we present a new method of data analysis, which allows determining the real phase shifts introduced during the measurement, and which helps to reduce the ghost effect. Two-dimensional cross-sectional in vivo images of human eye and skin obtained with the aid of this improved complex spectral OCT technique are shown. The method is free of polychromatic phase error originating from the wavelength dependence of the phase shift introduced by the reference mirror translation.

  12. Experimental quantum-enhanced estimation of a lossy phase shift

    Kacprowicz, M; Wasilewski, W; Banaszek, K; Walmsley, I A


    When standard light sources are employed, the precision of the phase determination is limited by the shot noise. Quantum entanglement provides means to exceed this limit with the celebrated example of N00N states that saturate the ultimate Heisenberg limit on precision, but at the same time are extremely fragile to losses. In contrast, we provide experimental evidence that appropriately engineered quantum states outperform both standard and N00N states in the precision of phase estimation when losses are present.

  13. Evolution of shifted cosmological parameter and shifted dust matter in a two-phase tachyonic field universe

    Verma, Murli Manohar


    We propose a model of the evolution of the tachyonic scalar field over two phases in the universe. The field components do not interact in phase I, while in the subsequent phase II, they change flavours due to relative suppression of the radiation contribution. In phase II, we allow them to interact mutually with time-independent perturbation in their equations of state, as Shifted Cosmological Parameter (SCP) and Shifted Dust Matter (SDM). We determine the solutions of their scaling with the cosmic redshift in both phases. We further suggest the normalized Hubble function diagnostic, which, together with the low- and high-redshift $H(z)$ data and the concordance values of the present density parameters from the CMBR, BAO statistics etc., constrains the strength of interaction, by imposing the viable conditions to break degeneracy in 3-parameter $(\\gamma, \\varepsilon, \\dot{\\phi}^2)$ space. The range of redshifts $(z=0.1$ to $z=1.75)$ is chosen to highlight the role of interaction during structure formation, a...

  14. 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


    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.

  15. Subpixel Accuracy Analysis of Phase Correlation Shift Measurement Methods Applied to Satellite Imagery

    S.M. Badwai


    Full Text Available the key point of super resolution process is the accurate measuring of sub-pixel shift. Any tiny error in measuring such shift leads to an incorrect image focusing. In this paper, methodology of measuring sub-pixel shift using Phase correlation (PC are evaluated using different window functions, then modified version of (PC method using high pass filter (HPF is introduced . Comprehensive analysis and assessment of (PC methods shows that different natural features yield different shift measurements. It is concluded that there is no universal window function for measuring shift; it mainly depends on the features in the satellite images. Even the question of which window is optimal of particular feature is generally remains open. This paper presents the design of a method for obtaining high accuracy sub pixel shift phase correlation using (HPF.The proposed method makes the change in the different locations that lack of edges easy.

  16. Phase shift operator and cyclic evolution in finite dimensional Hilbert space

    Johal, R S


    We address the problem of phase shift operator acting as time evolution operator in Pegg-Barnett formalism. It is argued that standard shift operator is inconsistent with the behaviour of the state vector under cyclic evolution. We consider a generally deformed oscillator algebra at q-root of unity, as it yields the same Pegg-Barnett operator and show that shift operator meets our requirement.

  17. EMP-002a Phase Shift through the Ionosphere

    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)


    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].

  18. Recent advances in phase shifted time averaging and stroboscopic interferometry

    Styk, Adam; Józwik, Michał


    Classical Time Averaging and Stroboscopic Interferometry are widely used for MEMS/MOEMS dynamic behavior investigations. Unfortunately both methods require an extensive measurement and data processing strategies in order to evaluate the information on maximum amplitude at a given load of vibrating object. In this paper the modified strategies of data processing in both techniques are introduced. These modifications allow for fast and reliable calculation of searched value, without additional complication of measurement systems. Through the paper the both approaches are discussed and experimentally verified.

  19. Experimental investigation of zero phase shift effects for Coriolis flowmeters due to pipe imperfections

    Enz, Stephanie; Thomsen, Jon Juel; Neumeyer, Stefan


    , 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...

  20. Two-particle scattering on the lattice: Phase shifts, spin-orbit coupling, and mixing angles

    Borasoy, Bugra; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G


    We determine two-particle scattering phase shifts and mixing angles for quantum theories defined with lattice regularization. The method is suitable for any nonrelativistic effective theory of point particles on the lattice. In the center-of-mass frame of the two-particle system we impose a hard spherical wall at some fixed large radius. For channels without partial-wave mixing the partial-wave phase shifts are determined from the energies of the nearly-spherical standing waves. For channels with partial-wave mixing further information is extracted by decomposing the standing wave at the wall boundary into spherical harmonics, and we solve coupled-channels equations to extract the phase shifts and mixing angles. The method is illustrated and tested by computing phase shifts and mixing angles on the lattice for spin-1/2 particles with an attractive Gaussian potential containing both central and tensor force parts.

  1. The vector projection of normalized interferogram differences and its application in phase-shift estimation

    Li, Teng; Hong, Daxiang


    From three interferograms, a novel algorithm for extracting phase shifts based on the vector projection of normalized difference maps is presented. In it, subtraction and vector normalization are operated successively to obtain two normalized interferogram differences without the effect of background component. Then, the phase shift can be estimated based on the analysis and calculation of the vector projection. Without any iteration and complex calculation, this algorithm can be implemented for phase-shift range approximately being well distributed from 0 to 2π, when fringe number of interferograms is more than one. It offers a powerful tool for rapid calibration of phase shifts because of its high efficiency and easy implementation. Numerical simulations and experiments are performed to prove its validity.

  2. On the phase-shift parameterization and ANC extraction from elastic-scattering data

    Suárez, Oscar Leonardo Ramírez


    We develop a method to parameterize elastic-scattering phase-shifts for charged nuclei, based on Pad\\'e expansions of a simplified effective-range function. The method is potential independent and the input is reduced to experimental phase shifts and bound-state energies. It allows a simple calculation of resonance properties and of asymptotic normalization constants (ANCs) of subthreshold bound states. We analyze the $1^-$ and $2^+$ phase shifts of the $^{12}$C$+\\alpha$ system and extract the ANCs of the corresponding bound states. For the $1^-$ state, a factor-3 improvement with respect to the best value available today is obtained, with a factor-10 improvement in reach. For the $2^+$ state, no improvement is obtained due to relatively larger error bars on the experimental phase shifts.

  3. Large microwave phase shift and small distortion in an integrated waveguide device

    Öhman, Filip; Sales, Salvador; Chen, Yaohui;


    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....

  4. Nonlinear Pulse Compression and Reshaping Using Cross-Phase Modulation in a Dispersion-Shifted Fiber

    S.; W.; Chan; K.; K.; Chow; C.; Shu


    Nonlinear pulse compression has been demonstrated by cross-phase modulation in a dispersion-shifted fiber. The output is obtained from filtering of the broadened optical spectrum and a pulse width reduction from 61 to 28 ps is achieved.

  5. Potential dangers when phase shifts are used as a link between experiment and QCD

    Svarc, Alfred


    Luscher has shown that in single channel problem (elastic region below first inelastic threshold) there exists a direct link between the discrete value of the energy in a finite QCD volume and the scattering phase shift at the same energy. However, when the extension of the theorem is made to the baryon resonance sector (multi-channel situation in the inelastic region above first inelastic threshold), eigenphases (diagonal multi-channel quantities) replace phase shifts (single channel quantities). It is necessary to stress that the renowned pi/2 resonance criterion is formulated for eigenphases and not for phase shifts, so the resonance extracting procedure has to be applied with utmost care. The potential instability of extracting eigenphases from experimental data which occurs if insufficient number of channels is used can be reduced if a trace function which explicitly takes multi-channel aspect of the problem into account is used instead of single-channel phase shifts.

  6. The phase-shift of isospin-2 pi-pi scattering from lattice QCD

    Jozef J. Dudek, Robert G. Edwards, Michael J. Peardon, David G. Richards, Christopher E. Thomas


    Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the L\\"uscher technique. In this letter, as a trial of the method, we report on the extraction of the non-resonant phase-shift for $S$ and $D$-wave $\\pi\\pi$ isospin-2 scattering from dynamical lattice QCD computations. We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta. Computations are performed with pion masses between $400$ and $520$ MeV on multiple spatial volumes. We observe no significant quark mass dependence in the phase-shifts extracted which are in reasonable agreement with the available experimental data at low momentum.

  7. Relationships among jumping performances and sprint parameters during maximum speed phase in sprinters.

    Kale, Mehmet; Aşçi, Alper; Bayrak, Coşkun; Açikada, Caner


    The purpose of this study was to investigate the relationships among jumping performances and speed parameters during maximum speed phase in sprinters. Twenty-one men sprinters volunteered to participate at the beginning of the preparation training phase. All tests-including 100-m sprint running, squat jump (SJ), countermovement jump (CMJ), drop jump (DJ), 60-second repetitive jump (RJ), standing long jump (SLJ), standing triple jump (STJ), standing quintuple jump (SQJ), and standing 10-stride jump (STENJ)-were done on switching mats. Flight (FT) and contact times (CT) during the vertical jump tests and 10-m split times during 100-m sprint running were measured by a 2-channel precision timing system (PTS) connected to the mats. The trace marking method was used for measuring the stride length (SL) through 60 m in 100-m sprint running. Stride frequency (SF), maximum velocity (Vmax), jump height for all vertical jumps, and lower-body power in DJ and RJ were calculated. Statistical analysis showed that the highest significant correlation was found between Vmax and DJ height (r = 0.69; p sprint running and SJ (r = 0.39; p sprint running than the other vertical and horizontal jump tests at the beginning of the preparation training phase.

  8. Phase-shift, stimuli-responsive perfluorocarbon nanodroplets for drug delivery to cancer.

    Rapoport, Natalya


    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.

  9. Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

    Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.


    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....

  10. Synthetic circular-harmonic phase-only filter for shift, rotation and scaling-invariant correlation

    Zi-Liang, ping; Dalsgaard, Erik


    A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations......A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations...

  11. Electromagnetic Corrections to the Hadronic Phase Shifts in Low-Energy $\\pi^{+}p$ Elastic Scattering

    Gashi, A; Oades, G C; Rasche, G; Woolcock, W S


    We calculate for the s-, p(1/2)- and p(3/2)-waves the electromagnetic corrections which must be subtracted from the nuclear phase shifts obtained from the analysis of low energy pi+ 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 qualitatively estimate the uncertainties in the corrections.

  12. Experimental Demonstration of Capacity-Achieving Phase-Shifted Superposition Modulation

    Estaran Tolosa, Jose Manuel; Zibar, Darko; Caballero Jambrina, Antonio


    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....

  13. Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

    Xie, Xin; Chen, Xu; Li, Junrui; Wang, Yonghong; Yang, Lianxiang


    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.

  14. Enhanced Phase-Shifted Current Control for Harmonic Cancellation in Three-Phase Multiple Adjustable Speed Drive Systems

    Yang, Yongheng; Davari, Pooya; Zare, Firuz


    A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies on......-shifted current control is a cost-effective solution to multiple ASD systems in terms of harmonic cancellation.......A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies...... 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...

  15. Motion-induced error reduction by combining Fourier transform profilometry with phase-shifting profilometry.

    Li, Beiwen; Liu, Ziping; Zhang, Song


    We propose a hybrid computational framework to reduce motion-induced measurement error by combining the Fourier transform profilometry (FTP) and phase-shifting profilometry (PSP). The proposed method is composed of three major steps: Step 1 is to extract continuous relative phase maps for each isolated object with single-shot FTP method and spatial phase unwrapping; Step 2 is to obtain an absolute phase map of the entire scene using PSP method, albeit motion-induced errors exist on the extracted absolute phase map; and Step 3 is to shift the continuous relative phase maps from Step 1 to generate final absolute phase maps for each isolated object by referring to the absolute phase map with error from Step 2. Experiments demonstrate the success of the proposed computational framework for measuring multiple isolated rapidly moving objects.

  16. Non-photic modulation of phase shifts to long light pulses.

    Antle, Michael C; Sterniczuk, Roxanne; Smith, Victoria M; Hagel, Kimberly


    Circadian rhythms can be reset by both photic and non-photic stimuli. Recent studies have used long light exposure to produce photic phase shifts or to enhance non-photic phase shifts. The presence or absence of light can also influence the expression of locomotor rhythms through masking; light during the night attenuates locomotor activity, while darkness during the day induces locomotor activity in nocturnal animals. Given this dual role of light, the current study was designed to examine the relative contributions of photic and non-photic components present in a long light pulse paradigm. Mice entrained to a light/dark cycle were exposed to light pulses of various durations (0, 3, 6, 9, or 12 h) starting at the time of lights-off. After the light exposure, animals were placed in DD and were either left undisturbed in their home cages or had their wheels locked for the remainder of the subjective night and subsequent subjective day. Light treatments of 6, 9, and 12 h produced large phase delays. These treatments were associated with decreased activity during the nocturnal light and increased activity during the initial hours of darkness following light exposure. When the wheels were locked to prevent high-amplitude activity, the resulting phase delays to the light were significantly attenuated, suggesting that the activity following the light exposure may have contributed to the overall phase shift. In a second experiment, telemetry probes were used to assess what effect permanently locking the wheels had on the phase shift to the long light pulses. These animals had phase shifts fully as large as animals without any form of wheel lock, suggesting that while non-photic events can modulate photic phase shifts, they do not play a role in the full phase-shift response observed in animals exposed to long light pulses. This paradigm will facilitate investigations into non-photic responses of the mouse circadian system.

  17. Redshift controversy in atom interferometry: representation dependence of the origin of phase shift.

    Schleich, Wolfgang P; Greenberger, Daniel M; Rasel, Ernst M


    Motivated by the recent debate on whether the Kasevich-Chu atom interferometer can measure the gravitational redshift, we show that in different representations of quantum mechanics chosen for the calculation, the observed phase shift appears as though it originates from different physical phenomena. In particular, we demonstrate that the decomposition of the total phase shift into three dynamical phases, which emerges in a semiclassical approach and is at the very heart of the redshift controversy, does not appear in an exact treatment based on a representation-free analysis. Here only two phenomena determine the phase shift: the difference of the laser phases and the acceleration of the atom. Hence, the Kasevich-Chu interferometer is an accelerometer or gravimeter.

  18. Isochronic and isodispersive carrier-envelope phase-shift compensators

    Grebing, C.; Görbe, M.; Osvay, K.; Steinmeyer, G.


    The design of mixed wedge pairs for control of the carrier-envelope phase of femtosecond laser pulses is discussed. The wedge pairs can be designed in such a way that they practically only compensate for the difference between group and phase delay, but leave either the group delay or the dispersion of the wedge assembly constant. Such isochronous or isodispersive compensators can be used for intracavity as well as for extracavity applications. Other side effects, such as the residual angular dispersion of the wedge pair are considered, and it is shown, both theoretically and experimentally, that material combinations exist that even enable a good compromise in reducing practically all disturbing side effects. Based on the two commonly available Schott glasses N-BK10 and N-PK51, a compensator assembly is experimentally tested inside a 10-fs Ti:sapphire oscillator. It is found that undesired variations of the laser repetition rate are reduced by a factor 50 compared to a set of identical silica wedges.

  19. Low-cost automated system for phase-shifting and phase retrieval based on the tunability of a laser diode

    Rivera-Ortega, Uriel; Dirckx, Joris


    A low-cost and fully automated process for phase-shifting interferometry by continuously changing and turning on-off the input voltage of a laser diode under the scheme of an unbalanced Twyman-Green interferometer setup is presented. The input signal of a laser diode is controlled by a Data Acquisition (NI-DAQ) device which permits to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. By using Carré algorithm the phase map is obtained. Measurements of visibility and phase-shift to verify the PSI requirements are also shown.

  20. Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors.

    Tu, Z C


    The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency (> 1/2) for a small load distribution factor (< 0.1).

  1. Core stress distribution of phase shifting multimode polymer optical fiber

    Furukawa, Rei, E-mail:; Matsuura, Motoharu [Center for Frontier Science and Engineering, The University of Electro-Communications, Chofugaoka 1-5-1, Chofu, Tokyo 182-8585 (Japan); Nagata, Morio; Mishima, Kenji [Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo 153-8904 (Japan); Inoue, Azusa; Tagaya, Akihiro; Koike, Yasuhiro [Keio Photonics Research Institute, Keio University, Saiwaiku Shinkawasaki 7-1, Kawasaki, Kanagawa 212-0032 (Japan)


    Poly-(methyl methacrylate-co-benzyl methacrylate) polarization-maintaining optical fibers are known for their high response to normal stress. In this report, responses to higher stress levels up to 0.45 MPa were investigated. The stress amplitude and direction in the fiber cross section were calculated and analyzed with a coincident mode-field obtained from the near-field pattern. The stress amplitude varies significantly in the horizontal direction and is considered to create multiple phases, explaining the measurement results. To investigate possible permanent deformation, the core yield point profile was analyzed. Although it largely exceeds the average applied stress, the calculated stress distribution indicates that the core could partially experience stress that exceeds the yield point.

  2. Out-phased decadal precipitation regime shift in China and the United States

    Yang, Lichao; Fu, Zuntao


    In order to understand the changes in precipitation variability associated with the climate shift around mid-1970s, the precipitation regime changes have been analyzed over both China and the USA. Specifically, a new variable is designed based on Benford's Law (BL) to detect precipitation regime shift by using only the first digit information of the datasets. This new variable describes the decadal precipitation regime shift more directly and clearly than the traditional variables, such mean or trend of yearly precipitation amount. It is found that there is an obvious out-phased relation for precipitation regime shift over China and the USA, i.e., a significant shift from the lower to the higher BL's goodness of fit (weaker to stronger precipitation intensity) in the Southern China occurred in 1979, and a significant shift from the higher to the lower BL's goodness of fit (stronger to weaker precipitation intensity) in the USA occurred around 1978.

  3. Direct comparison of phase-sensitive vibrational sum frequency generation with maximum entropy method: case study of water.

    de Beer, Alex G F; Samson, Jean-Sebastièn; Hua, Wei; Huang, Zishuai; Chen, Xiangke; Allen, Heather C; Roke, Sylvie


    We present a direct comparison of phase sensitive sum-frequency generation experiments with phase reconstruction obtained by the maximum entropy method. We show that both methods lead to the same complex spectrum. Furthermore, we discuss the strengths and weaknesses of each of these methods, analyzing possible sources of experimental and analytical errors. A simulation program for maximum entropy phase reconstruction is available at:

  4. Dual-phase-shift schemes for internal-reflection noise reduction in a Fizeau interferometer

    Kumagai, Toshiki; Hibino, Kenichi; Nagaike, Yasunari


    A method to reduce the phase measurement errors generated from internal-reflection light noise in a Fizeau interferometer is proposed. In addition to an ordinary phase-shift by a mechanical translation of the reference surface, the test surface is also mechanically translated between each phase measurement to further modulate the signal phase. For spherical tests, a mechanical phase-shift generally generates a spatial non-uniformity in the phase increment across the observing aperture. It is shown that a minimum of three positional measurements is necessary to cancel out the systematic error caused by this non-uniformity. Linear combinations of the three measured phases can also cancel the additional primary spherical aberrations that occur when the test surface is out of the null position of the confocal configuration.

  5. Tuning the pH-shift protein-isolation method for maximum hemoglobin-removal from blood rich fish muscle.

    Abdollahi, Mehdi; Marmon, Sofia; Chaijan, Manat; Undeland, Ingrid


    A main challenge preventing optimal use of protein isolated from unconventional raw materials (e.g., small pelagic fish and fish by-products) using the pH-shift method is the difficulty to remove enough heme-pigments. Here, the distribution of hemoglobin (Hb) in the different fractions formed during pH-shift processing was studied using Hb-fortified cod mince. Process modifications, additives and prewashing were then investigated to further facilitate Hb-removal. The alkaline pH-shift process version could remove considerably more Hb (77%) compared to the acidic version (37%) when proteins were precipitated at pH 5.5; most Hb was removed during dewatering. Protein precipitation at pH 6.5 improved total Hb removal up to 91% and 74% during alkaline and acid processing, respectively. Adding phytic acid to the first supernatant of the alkaline process version yielded 93% Hb removal. Combining one prewash with phytic acid at pH 5.5 followed by alkaline/acid pH-shift processing increased Hb removal up to 96/92%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Amorphous-Si waveguide on a garnet magneto-optical isolator with a TE mode nonreciprocal phase shift.

    Ishida, Eiichi; Miura, Kengo; Shoji, Yuya; Yokoi, Hideki; Mizumoto, Tetsuya; Nishiyama, Nobuhiko; Arai, Shigehisa


    We fabricated a magneto-optical (MO) isolator with a TE mode nonreciprocal phase shift. The isolator is based on a Mach-Zehnder interferometer composed of 3-dB directional couplers, a reciprocal phase shifter, and a nonreciprocal phase shifter. To realize TE mode operation in the optical isolator, we designed a novel waveguide structure composed of a hydrogenated amorphous silicon waveguide with an asymmetric MO garnet lateral clad on a garnet substrate. The isolator operation is successfully demonstrated in a fabricated device showing the different transmittances between forward and backward directions. The maximum isolation of the fabricated isolator is 17.9 dB at a wavelength of 1561 nm for the TE mode.

  7. On the nucleon–nucleon scattering phase shifts through supersymmetry and factorization

    U Laha; J Bhoi


    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 demonstrate the usefulness of our constructed potentials by means of model calculation.

  8. Experimental and numerical investigations of the phase-shift effect in capacitively coupled discharges

    Gao, Fei; Zhang, Yu-Ru; Zhao, Shu-Xia; Wang, You-Nian, E-mail: [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)


    The phase-shift effect has been investigated by a Langmuir probe and a fluid model in Ar capacitively coupled plasmas at 50 mTorr. In the discharge, two sources with the same frequency, i.e., 27.12 MHz, are applied on the top and bottom electrodes simultaneously, and the phase shift between them varies from 0 to π. It is found that the electron density has an off-axis peak near the radial edge when the phase difference is equal to 0 due to the electrostatic edge effect, and the best radial uniformity is observed at a phase difference equal to π. Furthermore, when the voltage increases, the best radial uniformity is obtained at lower phase shift values. Moreover, the electron energy probability function has a bi-temperature structure at all the selected phase differences at r = 1–15 cm. The evolution of the plasma characteristics with the phase difference implies that the best radial uniformity can be obtained, by balancing the electrostatic edge effect and the phase shift effect.

  9. Phase-locked states and abrupt shifts in Pacific climate indices

    Douglass, David H., E-mail:


    Douglass has shown that ENSO index aNino3.4 contains segments phase locked to subharmonics of the annual solar cycle and also that a set of indices including aNino3.4 shows abrupt shifts between these phase-locked states. Here, four additional Pacific indices are studied. These five indices show that the Pacific climate system alternates between two regimes: (1) Solar cycle (SOL), (2) Teleconnections (TEL). During SOL each index shows two components that are phase locked to the solar cycle. The first is at the annual cycle, while the second is at a subharmonic of the annual cycle. During TEL abrupt climate shifts occur.

  10. Phase shift spectra of a fiber-microsphere system at the single photon level

    Tanaka, Akira; Toubaru, Kiyota; Takashima, Hideaki; Fujiwara, Masazumi; Okamoto, Ryo; Takeuchi, Shigeki; 10.1364/OE.19.002278


    We succeeded in measuring phase shift spectra of a microsphere cavity coupled with a tapered fiber using a weak coherent probe light at the single photon level. We utilized a tapered fiber with almost no depolarization and constructed a very stable phase shift measurement scheme based on polarization analysis using photon counting. Using a very weak probe light (\\bar{n} = 0:41), we succeeded in observing the transition in the phase shift spectrum between undercoupling and overcoupling (at gap distances of 500 and 100 nm, respectively).We also used quantum state tomography to obtain a 'purity spectrum'. Even in the overcoupling regime, the average purity was 0.982 \\pm 0.024 (minimum purity: 0.892), suggesting that the coherence of the fiber-microsphere system was well preserved. Based on these results, we believe this system is applicable to quantum phase gates using single light emitters such as diamond nitrogen vacancy centers.

  11. A self-reference PRF-shift MR thermometry method utilizing the phase gradient.

    Langley, Jason; Potter, William; Phipps, Corey; Huang, Feng; Zhao, Qun


    In magnetic resonance (MR) imaging, the most widely used and accurate method for measuring temperature is based on the shift in proton resonance frequency (PRF). However, inter-scan motion and bulk magnetic field shifts can lead to inaccurate temperature measurements in the PRF-shift MR thermometry method. The self-reference PRF-shift MR thermometry method was introduced to overcome such problems by deriving a reference image from the heated or treated image, and approximates the reference phase map with low-order polynomial functions. In this note, a new approach is presented to calculate the baseline phase map in self-reference PRF-shift MR thermometry. The proposed method utilizes the phase gradient to remove the phase unwrapping step inherent to other self-reference PRF-shift MR thermometry methods. The performance of the proposed method was evaluated using numerical simulations with temperature distributions following a two-dimensional Gaussian function as well as phantom and in vivo experimental data sets. The results from both the numerical simulations and experimental data show that the proposed method is a promising technique for measuring temperature.

  12. Comment on "Dual-wavelength in-line phase-shifting interferometry based on two dc-term-suppressed intensities with a special phase shift for quantitative phase extraction"

    Wang, Minmin; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie


    We comment on the recent Letter by Xu and Wang et al. [Opt. Lett. 41, 2430 (2016)] in which an approach of quantitative phase extraction in dual-wavelength in-line phase-shifting interferometry (DWILPSI) was proposed. It is noted that a special phase shift is used, which more or less embarrasses its practical operation. We wish to show that the same result can also be reached by combining the generalized phase-shifting algorithm and the least-square algorithm, in which the phase shift can be chosen randomly. In addition to maintaining high accuracy and rapid processing speed of the DWILPSI method, the proposed method greatly facilitates its application in actual measurement.

  13. The coating design of phase-shifting reflector array with high reflectance and specified reflection phase shifts for static Michelson interferometer

    Zhang, Xuanni; Zhang, Hui; Wang, Yijun


    The optical Doppler Michelson imaging interferometer is widely used for wind measurements. Four interferograms obtained simultaneously are needed to immune to environmental disturbances. Thus, a static and divided mirror Michelson interferometer is proposed. Its highlight is the phase-shifting reflector array, which divides one mirror into four quadrants coated by different multilayer films with high reflectance, specified phase steps π/2 and little polarization effects. By combining analytical and empirical method, four coatings are designed with software TFCalc. The simulated results showed good agreement with the desired optical properties. Due to the limitation of the optical material and function of the software TFCalc, there are some design errors within tolerance.

  14. White light phase shifting interferometry and color fringe analysis for the detection of contaminants in water

    Dubey, Vishesh; Singh, Veena; Ahmad, Azeem; Singh, Gyanendra; Mehta, Dalip Singh


    We report white light phase shifting interferometry in conjunction with color fringe analysis for the detection of contaminants in water such as Escherichia coli (E.coli), Campylobacter coli and Bacillus cereus. The experimental setup is based on a common path interferometer using Mirau interferometric objective lens. White light interferograms are recorded using a 3-chip color CCD camera based on prism technology. The 3-chip color camera have lesser color cross talk and better spatial resolution in comparison to single chip CCD camera. A piezo-electric transducer (PZT) phase shifter is fixed with the Mirau objective and they are attached with a conventional microscope. Five phase shifted white light interferograms are recorded by the 3-chip color CCD camera and each phase shifted interferogram is decomposed into the red, green and blue constituent colors, thus making three sets of five phase shifted intererograms for three different colors from a single set of white light interferogram. This makes the system less time consuming and have lesser effect due to surrounding environment. Initially 3D phase maps of the bacteria are reconstructed for red, green and blue wavelengths from these interferograms using MATLAB, from these phase maps we determines the refractive index (RI) of the bacteria. Experimental results of 3D shape measurement and RI at multiple wavelengths will be presented. These results might find applications for detection of contaminants in water without using any chemical processing and fluorescent dyes.

  15. Two-frame phase-shifting interferometry for testing optical surfaces.

    Tian, Chao; Liu, Shengchun


    Standard phase-shifting interferometry (PSI) generally requires collecting at least three phase-shifted interferograms to extract the physical quantity being measured. Here, we propose the application of a simple two-frame PSI for the testing of a range of optical surfaces, including flats, spheres, and aspheres. The two-frame PSI extracts modulated phase from two randomly phase-shifted interferograms using a Gram-Schmidt algorithm, and can work in either null testing or non-null testing modes. Since only two interferograms are used for phase demodulation and the phase shift amount can be random, requirements on environmental conditions and phase shifter calibration are greatly relaxed. Experimental results of three different mirrors suggest that the two-frame PSI can achieve comparable measurement precision with conventional multi-frame PSI, but has faster data acquisition speed and less stringent hardware requirements. The proposed two-frame PSI expands the flexibility of PSI and holds great potential in many applications.

  16. Phase-step calibration technique based on a two-run-times-two-frame phase-shift method.

    Zhong, Xianghong


    A novel phase-step calibration technique is presented on the basis of a two-run-times-two-frame phase-shift method. First the symmetry factor M is defined to describe the distribution property of the distorted phase due to phase-shifter miscalibration; then the phase-step calibration technique, in which two sets of two interferograms with a straight fringe pattern are recorded and the phase step is obtained by calculating M of the wrapped phase map, is developed. With this technique, a good mirror is required, but no uniform illumination is needed and no complex mathematical operation is involved. This technique can be carried out in situ and is applicable to any phase shifter, whether linear or nonlinear.

  17. Maximum a posteriori estimation of crystallographic phases in X-ray diffraction tomography

    Gürsoy, Doǧa; Bicer, Tekin; Almer, Jonathan D.; Kettimuthu, Rajkumar; Stock, Stuart; De Carlo, Francesco


    A maximum a posteriori approach is proposed for X-ray diffraction tomography for reconstructing three-dimensional spatial distribution of crystallographic phases and orientations of polycrystalline materials. The approach maximizes the a posteriori density which includes a Poisson log-likelihood and an a priori term that reinforces expected solution properties such as smoothness or local continuity. The reconstruction method is validated with experimental data acquired from a section of the spinous process of a porcine vertebra collected at the 1-ID-C beamline of the Advanced Photon Source, at Argonne National Laboratory. The reconstruction results show significant improvement in the reduction of aliasing and streaking artefacts, and improved robustness to noise and undersampling compared to conventional analytical inversion approaches. The approach has the potential to reduce data acquisition times, and significantly improve beamtime efficiency.

  18. PV Power-Generation System with a Phase-Shift PWM Technique for High Step-Up Voltage Applications

    Cheng-Tao Tsai


    Full Text Available A PV power-generation system with a phase-shift pulse-width modulation (PWM technique for high step-up voltage applications is proposed. The proposed power-generation system consists of two stages. In the input stage, all power switches of the full-bridge converter with phase-shift technique can be operated with zero-current switching (ZCS at turn-on or turn-off transition. Hence, the switching losses of the power switches can be reduced. Then, in the DC output stage, a voltage-doubler circuit is used to boost a high dc-link bus voltage. To supply a utility power, a dc/ac inverter is connected to induce a sinusoidal source. In order to draw a maximum power from PV arrays source, a microcontroller is incorporated with the perturbation and observation method to implement maximum power point tracking (MPPT algorithm and power regulating scheme. In this study, a full load power of 300 W prototype has been built. Experimental results are presented to verify the performance and feasibility of the proposed PV power-generation system.

  19. Compact microfluidic sensing by introducing effective phase shift in fiber Bragg grating

    Tang, Minghui; Wang, Guanghui; Ho, Ho-Pui A.; Zhang, Xuping


    A compact microfluidic refractive index sensor fabricated by drilling hole in the middle section of a fiber Bragg grating (FBG) is reported herein. The laser-drilled hole provides a microfluidic channel for the aqueous sample to pass through while at the same time permits coupling of the interrogating light to detect the target analyte. The reported sensor takes advantage of the fact that a small phase shift in the central region of the grating will result in a very sharp peak in the FBG stop-band. The phase shift can be related to a range of possible perturbations inside the microfluidic channel, including passage of cells, beads and a shift in the concentration of certain fluidic component. The amount of wavelength shift of the peak in the FBG stop-band represents the change in the refractive index inside the microfluidic channel. Simulation results indicate very favorable sensor signal characteristics such as large wavelength shift and sharp reflection dips. The reported microfluidic phase shift FGB sensor could be a good candidate for portable flow cytometry applications.

  20. Predicting phase shift of elastic waves in pipes due to fluid flow and imperfections

    Thomsen, Jon Juel; Dahl, Jonas; Fuglede, Niels


    Flexural vibrations of a fluid-conveying pipe is investigated, with special consideration to the spatial shift in phase caused by fluid flow and various imperfections, e.g., non-ideal supports, non-uniform stiffness or mass, non-proportional damping, weak nonlinearity, and flow pulsation. This is......Flexural vibrations of a fluid-conveying pipe is investigated, with special consideration to the spatial shift in phase caused by fluid flow and various imperfections, e.g., non-ideal supports, non-uniform stiffness or mass, non-proportional damping, weak nonlinearity, and flow pulsation....... 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...

  1. Modeling, error analysis, and compensation in phase-shifting surface profilers

    Hu, Qingying Jim


    Optical metrology techniques have been widely used in geometric dimension and shape measurements due to many features such as non-contact measurement, fast measurement speed, digital data format for computerized analysis and visualization, superior resolution, and high accuracy, etc. Among these techniques, phase-shifting based surface profilers have drawn more and more attention due to its full-field measurement and maturing wrapping/unwrapping analysis characteristics. This paper analyzes the error sources in phase-shifting surface profilers, including phaseshifting generation, non-linearity compensation, phase-shifting algorithms, surface contour extraction, modeling, and calibration, etc. Some methods to improve the measurement accuracy through coordinate error compensation are also proposed including transfer functions and look-up table (LUT) methods.

  2. Duffing revisited: Phase-shift control and internal resonance in self-sustained oscillators

    Arroyo, Sebastián I


    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...

  3. Sagnac experiment with electrons: Reanalysis of a rotationally induced phase shift for charged particles

    Neutze, Richard; Hasselbach, Franz


    Using a path-integral formalism, we present a reanalysis of the Sagnac experiment with electrons of Hasselbach and Nicklaus [Phys. Rev. A 48, 143 (1993)]. Our analysis, from an inertial frame of reference, makes explicit the central role of the electrostatic biprism in generating interference fringes and recovers the Sagnac formula for the phase shift induced when rotating the interferometer. This phase shift, however, is shown to differ significantly in physical origin from the similar experiment with neutrons. In the electron Sagnac experiment, rotation displaces all classical electron paths closer to (or further from, depending upon direction) the electrostatic biprisms, thereby perturbing the electrostatic potential along these paths, and a phase shift of an electrostatic nature arises. Our analysis yields a corrected expression for the projected area of the interferometer and small numerical corrections to previous work are consequently given.

  4. Strain Measurement Using Phase-shifting Digital Holography with Two Cameras

    Morimoto Y.


    Full Text Available Phase-shifting digital holography is a convenient method to measure displacement and strain distributions. Development of compact and conventional strain distribution measurement equipment for practical use is required for inspection of health monitoring and life lengthening of infrastructures such as steel bridges. In this paper, we propose an off-axis reconstruction method for displacement and strain distribution measurement with a phase-shifting digital holography. In the case of off-axis optical setup, the pitch of the fringe appearing on the image sensor becomes smaller than a pixel size. However, the phase-shifting digital hologram can be obtained even if the off-axis setup and effective results can be obtained using a Windowed-PSDHI. The principle and the experimental result of strain distribution measurement was performed with this method using two cameras.

  5. Enhanced high dynamic range 3D shape measurement based on generalized phase-shifting algorithm

    Wang, Minmin; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie


    It is a challenge for Phase Measurement Profilometry (PMP) to measure objects with a large range of reflectivity variation across the surface. Saturated or dark pixels in the deformed fringe patterns captured by the camera will lead to phase fluctuations and errors. Jiang et al. proposed a high dynamic range real-time 3D shape measurement method without changing camera exposures. Three inverted phase-shifted fringe patterns are used to complement three regular phase-shifted fringe patterns for phase retrieval when any of the regular fringe patterns are saturated. But Jiang's method still has some drawbacks: (1) The phases in saturated pixels are respectively estimated by different formulas for different cases. It is shortage of an universal formula; (2) it cannot be extended to four-step phase-shifting algorithm because inverted fringe patterns are the repetition of regular fringe patterns; (3) only three unsaturated intensity values at every pixel of fringe patterns are chosen for phase demodulation, lying i...

  6. Polarisation Control of DFB Fibre Laser Using UV-Induced Birefringent Phase-Shift

    Philipsen, Jacob Lundgreen; Lauridsen, Vibeke Claudia; Berendt, Martin Ole;


    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...

  7. Improvement of spatial resolution in confocal microscope with shifted-focus phase filter

    Huang, Xiangdong; Xiang, Xiaoyan; Wang, Chongyang


    A spatial super-resolution method is proposed based on the multiplicative character of confocal microscope's amplitude point-spread functions. The axial resolution can be greatly improved by introducing a shifted-focus phase filters in illumination part of a confocal microscope. However, this improvement is accompanied by a decrease of transversal resolution. Thus, a super-Gaussian phase filter is optimized to control the focal shift and transversal intensity distribution in a confocal microscope. Numerical simulation results indicate that the proposed method is useful to obtain a significant improvement in the optical sectioning capacity.

  8. Generation of Periodic Sawtooth Optical Intensity by Phase-Shifting Mask

    Ura, Shogo; Kintaka, Kenji; Awazu, Hideyuki; Nishio, Kenzo; Awatsuji, Yasuhiro; Nishii, Junji


    A new simple interference exposure method using a phase-shifting mask was discussed on the basis of Fourier synthesis for fabricating blazed gratings. Phase-shifting mask was designed with 244 nm exposure-light wavelength to launch multiple diffraction beams so that resultant interference pattern fit to required optical intensity profile. Fine surface-relief pattern on SiO2 mask for 3-µm-period sawtooth optical-intensity profile was fabricated by electron-beam direct-writing lithography with 30 nm scanning step and relief height of 65 nm. Sawtooth-like intensity profile was demonstrated with theoretically predicted interference visibility.

  9. Phase-shifting technique applied to circular harmonic-based joint transform correlator


    The phase-shifting technique is applied to the circular harmonic expansion-based joint transform correlator. Computer simulation has shown that the light efficiency and the discrimination capability are greatly enhanced, and the full rotation invariance is preserved after the phase-shifting technique has been used. A rotation-invariant optical pattern recognition with high discrimination capability and high light efficiency is obtained. The influence of the additive noise on the performance of the correlator is also investigated. However, the anti-noise capability of this kind of correlator still needs improving.

  10. 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


    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.

  11. The phase shift induced by a single atom in free space

    Sondermann, Markus


    In this article we theoretically study the phase shift a single atom imprints onto a coherent state light beam in free space. The calculations are performed in a semiclassical framework. The key parameters governing the interaction and thus the measurable phase shift are the solid angle from which the light is focused onto the atom and the overlap of the incident radiation with the atomic dipole radiation pattern. The analysis includes saturation effects and discusses the associated Kerr-type non-linearity of a single atom.

  12. Light pulse duration differentially regulates mouse locomotor suppression and phase shifts.

    Morin, Lawrence P; Studholme, Keith M


    Brief exposure of mice to nocturnal light causes circadian rhythm phase shifts, simultaneously inducing locomotor suppression, a drop in body temperature, and associated sleep. The exact nature of the relationship between these light-induced responses is uncertain, although locomotor suppression and phase shift magnitudes are related to stimulus irradiance. Whether stimulus duration has similar effects is less clear. Here, the relationship between stimulus duration and response magnitude was evaluated further using 100 µW/cm(2) white light-emitting diode pulses administered for 30, 300, 1200, or 3000 sec. The results show that, in general, shorter pulses yielded smaller responses and larger pulses yielded larger responses. However, the 300-sec pulse failed to augment locomotor suppression compared with the effect of a 30-sec pulse (44.7 ± 4.8 vs 40.6 ± 2.0 min) but simultaneously induced much larger phase shifts (1.28 ± 0.20 vs 0.52 ± 0.11 h). The larger phase shifts induced by the 300-sec stimulus did not differ from those induced by either the 1200- or 3000-sec pulses (1.43 ± 0.10 and 1.30 ± 0.17 h, respectively). The results demonstrate differential photic regulation of the two response types. Pulses ranging from 300 to 3000 sec produce equal phase shifts (present data); pulses ranging from 30 to 600 sec produce equal locomotor suppression levels. Greater suppression can occur additively in response to pulses of 1200 sec or more (present data), but this is not true for phase shifts. Nocturnal light appears to trigger a fixed duration event, locomotor suppression, or phase shift, with the latter followed by a light-refractory interval during which locomotor suppression can additively increase. The results also provide further support for the view that temporal integration of photic energy applies, at best, across a limited set of stimulus durations for both light-induced locomotor suppression/sleep and phase shift regulation. © 2014 The Author(s).

  13. Nucleon-alpha particle interactions from inversion of scattering phase shifts

    Alexander, N.; Amos, K.; Apagyi, B.; Lun, D.R.


    Scattering amplitudes have been extracted from (elastic scattering) neutron-alpha (n-{alpha}) differential cross sections below threshold using the constraint that the scattering function is unitary. Real phase shifts have been obtained therefrom. A modification to the Newton iteration method has been used to solve the nonlinear equation that specifies the phase of the scattering amplitude in terms of the complete (0 to 180 deg) cross section since the condition for a unique and convergent solution by an exact iterated fixed point method, the `Martin` condition, is not satisfied. The results compare well with those found using standard optical model search procedures. Those optical model phase shifts, from both n - {alpha} and p - {alpha} (proton-alpha) calculations in which spin-orbit effects were included, were used in the second phase of this study, namely to determine the scattering potentials by inversion of that phase shift data. A modified Newton-Sabatier scheme to solve the inverse scattering problem has been used to obtain inversion potentials (both central and spin-orbit) for nucleon energies in the range 1 to 24 MeV. The inversion interactions differ noticeably from the Woods-Saxon forms used to give the input phase shifts. Not only do those inversion potentials when used in Schroedinger equations reproduce the starting phase shifts but they are also very smooth, decay rapidly, and are as feasible as the optical model potentials of others to be the local form for interactions deduced by folding realistic two-nucleon g matrices with the density matrix elements of the alpha particle. 23 refs., 8 tabs., 9 figs.

  14. Application of thermal wave imaging and phase shifting method for defect detection in Stainless steel

    Shrestha, Ranjit; Park, Jeonghak; Kim, Wontae


    This paper presents an experimental arrangement for detection of artificial subsurface defects in a stainless steel sample by means of thermal wave imaging with lock-in thermography and consequently, the impact of excitation frequency on defect detectability. The experimental analysis was performed at several excitation frequencies to observe the sample beginning from 0.18 Hz all the way down to 0.01 Hz. The phase contrast between the defective and sound regions illustrates the qualitative and quantitative investigation of defects. The two, three, four and five-step phase shifting methods are investigated to obtain the information on defects. A contrast to noise ratio analysis was applied to each phase shifting method allowing the choice of the most appropriate one. Phase contrast with four-step phase shifting at an optimum frequency of 0.01 Hz provides excellent results. The inquiry with the effect of defect size and depth on phase contrast shows that phase contrast decreases with increase in defect depth and increases with the increase in defect size.

  15. Role of proinflammatory cytokines on lipopolysaccharide-induced phase shifts in locomotor activity circadian rhythm.

    Leone, M Juliana; Marpegan, Luciano; Duhart, José M; Golombek, Diego A


    We previously reported that early night peripheral bacterial lipopolysaccharide (LPS) injection produces phase delays in the circadian rhythm of locomotor activity in mice. We now assess the effects of proinflammatory cytokines on circadian physiology, including their role in LPS-induced phase shifts. First, we investigated whether differential systemic induction of classic proinflammatory cytokines could explain the time-specific behavioral effects of peripheral LPS. Induction levels for plasma interleukin (IL)-1α, IL-1β, IL-6, or tumor necrosis factor (TNF)-α did not differ between animals receiving a LPS challenge in the early day or early night. We next tested the in vivo effects of central proinflammatory cytokines on circadian physiology. We found that intracerebroventricular (i.c.v.) delivery of TNF-α or interleukin IL-1β induced phase delays on wheel-running activity rhythms. Furthermore, we analyzed if these cytokines mediate the LPS-induced phase shifts and found that i.c.v. administration of soluble TNF-α receptor (but not an IL-1β antagonistic) prior to LPS stimulation inhibited the phase delays. Our work suggests that the suprachiasmatic nucleus (SCN) responds to central proinflammatory cytokines in vivo, producing phase shifts in locomotor activity rhythms. Moreover, we show that the LPS-induced phase delays are mediated through the action of TNF-α at the central level, and that systemic induction of proinflammatory cytokines might be necessary, but not sufficient, for this behavioral outcome.

  16. Design and experiment of electronic speckle shearing phase-shifting pattern interferometer

    Xu, Tianhua; Jing, Wencai; Zhang, Hongxia; Jia, Dagong; Zhang, Yimo


    An electronic speckle shearing phase-shifting pattern interferometer (ESSPPI) based on Michelson interferometer was based in this paper. A rotatable mirror driven by a step motor in one of its reflective arm is used to generate an adjustable shearing and the mirror driven by piezoelectric transducer (PZT) in the other reflective arm was used to realize phaseshifting. In the experiments, the deformation of an aluminum plate with the same extern-force on different positions and different forces on the same position is measured. Meanwhile, the phase distribution and phase-unwrap image of the aluminum plate with the extern-force on its center position is obtained by the four-step phase-shifting method.

  17. Improvement on peak-to-trough ratio of sampled fiber Bragg gratings with multiple phase shifts

    Bin Xie; Wei Pan; Bin Luo; Xihua Zou


    Via a cascaded structure, the peak-to-trough ratio is considerably improved for sampled fiber Bragg gratings (SFBGs) based on multiple-phase-shift (MPS) technique. This cascaded filter is composed of two identical SFBGs which are inserted with the increasing or decreasing arrangement of phase shifts.With this inverse arrangement of MPS in grating design, the phase fluctuation of individual SFBG can be compensated, and as a result an excellent phase matching condition is realized. In this way, the peak-to-trough ratio in reflection spectra is improved from 6 to 12 dB when multiplication factor m = 4, and from 5 dB to 10 dB when m=8.

  18. Design and experiment of electronic speckle shearing phase-shifting pattern interferometer


    An electronic speckle shearing phase-shifting pattern interferometer (ESSPPI) based on Michelson interferometer was based in this paper. A rotatable mirror driven by a step motor in one of its reflective arm is used to generate an adjustable shearing and the mirror driven by piezoelectric transducer (PZT) in the other reflective arm was used to realize phaseshifting. In the experiments, the deformation of an aluminum plate with the same extern-force on different positions and different forces on the same position is measured. Meanwhile, the phase distribution and phase-unwrap image of the aluminum plate with the extern-force on its center position is obtained by the four-step phase-shifting method.

  19. The role of strong phase shift masks in Intel's DFM infrastructure development

    Schenker, Richard; Singh, Vivek; Borodovsky, Yan


    Intel has reported on three separate styles and applications of strong phase shift masks (PSMs) over the last decade including alt-PSM for gate patterning, alt-PSM with assist features for contact patterning and Pixelated Phase Masks (PPMs) for metal layer patterning. Each had a prominent role in Intel's Design For Manufacturing (DFM) infrastructure development in terms of design rules and DFM tooling. By gradually inserting design rule changes for alt-PSM for gate patterning starting from the 130nm technology node, density and design impact were minimally effected. Alt-PSM for contact layer required development of complex methods of SRAF placement and coloring while also forcing advances in phase shift mask manufacturing infrastructure. Pixelated phase masks for metal patterning when combined with Inverse Lithography Techniques (ILTs) were successful in supporting a high level of flexibility for metal design rules including multiple feature sizes, pitches and two-dimension content.

  20. Improved maximum entropy method for the analysis of fluorescence spectroscopy data: evaluating zero-time shift and assessing its effect on the determination of fluorescence lifetimes.

    Esposito, Rosario; Mensitieri, Giuseppe; de Nicola, Sergio


    A new algorithm based on the Maximum Entropy Method (MEM) is proposed for recovering both the lifetime distribution and the zero-time shift from time-resolved fluorescence decay intensities. The developed algorithm allows the analysis of complex time decays through an iterative scheme based on entropy maximization and the Brent method to determine the minimum of the reduced chi-squared value as a function of the zero-time shift. The accuracy of this algorithm has been assessed through comparisons with simulated fluorescence decays both of multi-exponential and broad lifetime distributions for different values of the zero-time shift. The method is capable of recovering the zero-time shift with an accuracy greater than 0.2% over a time range of 2000 ps. The center and the width of the lifetime distributions are retrieved with relative discrepancies that are lower than 0.1% and 1% for the multi-exponential and continuous lifetime distributions, respectively. The MEM algorithm is experimentally validated by applying the method to fluorescence measurements of the time decays of the flavin adenine dinucleotide (FAD).




    Full Text Available The generalized maximum likelihood method was used to determine binary interaction parameters between carbon dioxide and components of orange essential oil. Vapor-liquid equilibrium was modeled with Peng-Robinson and Soave-Redlich-Kwong equations, using a methodology proposed in 1979 by Asselineau, Bogdanic and Vidal. Experimental vapor-liquid equilibrium data on binary mixtures formed with carbon dioxide and compounds usually found in orange essential oil were used to test the model. These systems were chosen to demonstrate that the maximum likelihood method produces binary interaction parameters for cubic equations of state capable of satisfactorily describing phase equilibrium, even for a binary such as ethanol/CO2. Results corroborate that the Peng-Robinson, as well as the Soave-Redlich-Kwong, equation can be used to describe phase equilibrium for the following systems: components of essential oil of orange/CO2.Foi empregado o método da máxima verossimilhança generalizado para determinação de parâmetros de interação binária entre os componentes do óleo essencial de laranja e dióxido de carbono. Foram usados dados experimentais de equilíbrio líquido-vapor de misturas binárias de dióxido de carbono e componentes do óleo essencial de laranja. O equilíbrio líquido-vapor foi modelado com as equações de Peng-Robinson e de Soave-Redlich-Kwong usando a metodologia proposta em 1979 por Asselineau, Bogdanic e Vidal. A escolha destes sistemas teve como objetivo demonstrar que o método da máxima verosimilhança produz parâmetros de interação binária, para equações cúbicas de estado capazes de descrever satisfatoriamente até mesmo o equilíbrio para o binário etanol/CO2. Os resultados comprovam que tanto a equação de Peng-Robinson quanto a de Soave-Redlich-Kwong podem ser empregadas para descrever o equilíbrio de fases para o sistemas: componentes do óleo essencial de laranja/CO2.

  2. Motion artifact reduction using hybrid Fourier transform with phase-shifting methods

    Li, Beiwen; Liu, Ziping; Zhang, Song


    We propose to combine the Fourier transform profilometry (FTP) and phase-shifting profilometry (PSP) to reduce motion induced artifacts. The proposed method can be divided into three steps: Step 1 is to obtain a temporarily unwrapped absolute phase map of the entire scene using the FTP method, albeit the absolute phase map has motion introduced artifacts; Step 2 is to generate continuous relative phase maps without motion artifacts for each isolated object by spatially unwrapping each isolated phase map retrieved from the FTP method; and Step 3 is to determine the absolute phase map for each isolate region by referring to the temporally unwrapped phase using PSP method. Experimental results demonstrated success of the proposed method for measuring rapidly moving multiple isolated objects.

  3. Accurate Clock Period Comparison for PLL Using Phase-Shift Direction Detector

    Makihara, Yukinobu; Ikebe, Masayuki; Motohisa, Junichi; Sano, Eiichi

    We proposed a new architecture for a phase-locked loop (PLL) obtained by comparing clock periods. We evaluated the use of a clock-period comparator (CPC) for the digitally controlled PLL we propose, where only the frequency should be locked. However, frequency control with the CPC resulted in the phase being locked. Thus, phase-lock operation was also achieved. The theoretical analysis of the phase-lock mechanism was confirmed through system simulations. We discussed about dead-zone problem caused by a time delay of circuits. We evaluated phase-shift direction detector to solve the dead zone problem. We designed the element blocks of the new PLL using a 0.25-μm CMOS process. We confirmed phase-lock operation through SPICE simulations of the MOSFET level. Moreover, we manufactured a trial circuit for the new PLL. We also confirmed phase-lock operation in the proposed PLL through measurements.

  4. Characterization of electromechanical actuator implemented to phase-shift system applied to a Michelson interferometer

    Barcelata-Pinzon, A.; Meneses Fabian, C.; Juarez-Salazar, R.; Durán-Sánchez, M.; Alvarez-Tamayo, R. I.; Robledo-Sánchez, C. I.; Muñoz-Mata, J. L.; Casco-Vázquez, J. F.


    Numerical results are presented to show the characterization of an electromechanical actuator capable to achieve equally spaced phase shifts and fraction linear wavelength displacements aided by an interface and a computational system. Measurements were performed by extracting the phase with consecutive interference patterns obtained in a Michelson arrangement setup. This paper is based in the use of inexpensive resources on stability adverse conditions to achieve similar results to those obtained with high-grade systems.

  5. Why the phase shifts for solitons on a vortex filament are so large?

    Cie'sli'nski, J L


    The phase ``jumps'' for solitons interacting on a vortex filament, observed in experiments, have been unaccounted for since more than twenty years. Using explicit formulas describing the interaction of two solitons on a thin vortex filament in the Localized Induction Approximation we show that an appropriate choice of the parameters of the solitons leads to large phase shifts. This result does not depend on the axial flow along the filament.

  6. Channel Acquisition for Massive MIMO-OFDM With Adjustable Phase Shift Pilots

    You, Li; Gao, Xiqi; Swindlehurst, A. Lee; Zhong, Wen


    We propose adjustable phase shift pilots (APSPs) for channel acquisition in wideband massive multiple-input multiple-output (MIMO) systems employing orthogonal frequency division multiplexing (OFDM) to reduce the pilot overhead. Based on a physically motivated channel model, we first establish a relationship between channel space-frequency correlations and the channel power angle-delay spectrum in the massive antenna array regime, which reveals the channel sparsity in massive MIMO-OFDM. With this channel model, we then investigate channel acquisition, including channel estimation and channel prediction, for massive MIMO-OFDM with APSPs. We show that channel acquisition performance in terms of sum mean square error can be minimized if the user terminals' channel power distributions in the angle-delay domain can be made non-overlapping with proper phase shift scheduling. A simplified pilot phase shift scheduling algorithm is developed based on this optimal channel acquisition condition. The performance of APSPs is investigated for both one symbol and multiple symbol data models. Simulations demonstrate that the proposed APSP approach can provide substantial performance gains in terms of achievable spectral efficiency over the conventional phase shift orthogonal pilot approach in typical mobility scenarios.

  7. 16-level differential phase shift keying (D16PSK) in direct detection optical communication systems

    Sambaraju, R.; Tokle, Torger; Jensen, J.B.;


    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...


    Kalinin L.P.


    Full Text Available Article is devoted to the development of simulation model in Simulink environment of phase shift installation, executed on classical scheme “Marcerau Connection”, test of idle, short-circuit and loading modes on base of this simulation model and determine of energy characteristics of this installation.

  9. Improved emission properties of polymer photonic crystal lasers by introducing a phase-shift

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron


    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....

  10. Comparing DLLs and Shift Registers for Low-Jitter Multi-phase Clock Generation

    Gao, X.; Klumperink, E.A.M.; Nauta, B.


    In this paper we compare a Shift Register (SR) to a Delay Locked Loop (DLL) for Multi Phase Clock Generation (MPCG), and motivate why a SR is often better. For a given power budget, we show that a SR generates less jitter than a DLL when both are realized with Current Mode Logic (CML) circuits and w

  11. Low-Jitter Multi-phase Clock Generation: a Comparison between DLLs and Shift Registers

    Gao, X.; Klumperink, E.A.M.; Nauta, B.


    This paper shows that, for a given power budget, a shift register based multi-phase clock generator (MPCG) generates less jitter than a delay-locked loop (DLL) equivalent when both are realized with current mode logic (CML) circuits and white noise is assumed. This is due to the factor that the shif

  12. Quantum displacement receiver for M-ary phase-shift-keyed coherent states

    Izumi, Shuro [National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795, Japan and Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan); Takeoka, Masahiro; Fujiwara, Mikio; Sasaki, Masahide [National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795 (Japan); Pozza, Nicola Dalla; Assalini, Antonio [Department of Information Engineering, University of Padua, Via Gradenigo 6/B, 35131, Padova (Italy); Ema, Kazuhiro [Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554 (Japan)


    We propose quantum receivers for 3- and 4-ary phase-shift-keyed (PSK) coherent state signals to overcome the standard quantum limit (SQL). Our receiver, consisting of a displacement operation and on-off detectors with or without feedforward, provides an error probability performance beyond the SQL. We show feedforward operations can tolerate the requirement for the detector specifications.

  13. Acute and phase-shifting effects of ocular and extraocular light in human circadian physiology

    Ruger, M; Gordijn, MCM; Beersma, DGM; de Vries, B; Daan, S


    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

  14. Development of a new high transmission phase shift mask technology for 10 nm logic node

    Faure, Thomas; Sakamoto, Yoshifumi; Toda, Yusuke; Badger, Karen; Seki, Kazunori; Lawliss, Mark; Isogawa, Takeshi; Zweber, Amy; Kagawa, Masayuki; Wistrom, Richard; Xu, Yongan; Lobb, Granger; Viswanathan, Ramya; Hu, Lin; Inazuki, Yukio; Nishikawa, Kazuhiro


    In this paper we will describe the development of a new 12% high transmission phase shift mask technology for use with the 10 nm logic node. The primary motivation for this work was to improve the lithographic process window for 10 nm node via hole patterning by reducing the MEEF and improving the depth of focus (DOF). First, the simulated MEEF and DOF data will be compared between the 6% and high T PSM masks with the transmission of high T mask blank varying from 12% to 20%. This resulted in selection of a 12% transmission phase shift mask. As part of this work a new 12% attenuated phase shift mask blank was developed. A detailed description and results of the key performance metrics of the new mask blank including radiation durability, dry etch properties, film thickness, defect repair, and defect inspection will be shared. In addition, typical mask critical dimension uniformity and mask minimum feature size performance for 10 nm logic node via level mask patterns will be shown. Furthermore, the results of work to optimize the chrome hard mask film properties to meet the final mask minimum feature size requirements will be shared. Lastly, the key results of detailed lithographic performance comparisons of the process of record 6% and new 12% phase shift masks on wafer will be described. The 12% High T blank shows significantly better MEEF and larger DOF than those of 6% PSM mask blank, which is consistent with our simulation data.

  15. Phase shifts in I=2 {\\pi}{\\pi}-scattering from two lattice approaches

    Kurth, T; Doi, T; Aoki, S; Hatsuda, T


    We present a lattice QCD study of the phase shift of I=2 {\\pi}{\\pi}-scattering on the basis of two different approaches: the standard finite volume approach by Luscher and the recently introduced HAL QCD potential method. Quenched QCD simulations are performed on a 32^3x128 lattice with lattice spacing a 0.115 fm using a heavy pion mass of m_{\\pi} 940 MeV. Results of the phase shift and the scattering length are shown to agree quite well between these two methods. In case of the potential method, the error is dominated by the systematic uncertainty associated with the violation of rotational symmetry due to finite lattice spacing. In Luscher's approach, such systematic uncertainty is difficult to be evaluated and thus not included in this work. In case of the potential method, the phase shift can be calculated for arbitrary energies below the inelastic threshold. In that context, the phase shift obtained from the nonrest-frame extension of Luscher's method obtained at a particular center-of-mass momentum lies...

  16. Nucleon-Nucleon Phase Shifts in the Extended Quark-Delocalization Colour-Screening Model

    LU Xi-Feng; PING Jia-Lun; WANG Fan


    An alternative method is applied to the study of nucleon-nucleon scattering phase shifts within the framework of the extended quark demoralization colour-screening model, in which the one-pion exchange with short-range cutoff is included.

  17. One step to generate quantum controlled phase-shift gate using a trapped ion

    Zhang Shi-Jun; Ma Chi; Zhang Wen-Hai; Ye Liu


    This paper presents a very simple scheme for generating quantum controlled phase-shift gate with only one step by using the two vibrational modes of a trapped ion as the two qubits.The scheme couples two vibration degrees of freedom coupled with a suitable chosen laser excitation via the ionic states.

  18. Quadrature phase shift keying coherent state discrimination via a hybrid receiver

    Müller, C. R.; Castaneda, Mario A. Usuga; Wittmann, C.;


    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...

  19. Two-step phase shifting interferometry technique for evaluation of fatigue process zone parameters in notched specimens

    Muravsky, Leonid I.; Picart, Pascal; Kmet', Arkady B.; Voronyak, Taras I.; Ostash, Orest P.; Stasyshyn, Ihor V.


    A new two-step phase shifting interferometry technique for evaluation of a fatigue process zone (FPZ) in notched metal and alloy specimens is proposed. In comparison with well-known destructive and nondestructive methods evaluating FPZ, this technique possesses higher accuracy and performance and allows defining the FPZ size for notched specimens made of metals and alloys with low, moderate or high plasticity. The technique is fulfilled by retrieval of a total surface relief of a studied notched specimen, extraction of surface roughness and waviness phase maps from the retrieved surface relief, calculation of a surface roughness parameter Ra spatial distribution and definition of the FPZ size by using an extracted surface roughness phase map. Obtained experimental results have confirmed assumption that the surface roughness of notched specimens after cyclic loading reaches its maximum values at the FPZ boundary. This boundary is produced as the narrow strip containing pixels possessing the maximum values on the spatial distribution of the roughness parameter Ra near a notch root. The basic distances d* defining the FPZ sizes were measured for notched specimens made of a low-carbon steel and aluminum alloys 2024-T6 and 7075-T3. Results of the distances d* measurement are very close to respective results obtained with the help of other methods for the FPZ evaluation.

  20. Predicting the start and maximum amplitude of solar cycle 24 using similar phases and a cycle grouping

    Jia-Long Wang; Wei-Guo Zong; Gui-Ming Le; Hai-Juan Zhao; Yun-Qiu Tang; Yang Zhang


    We find that the solar cycles 9, 11, and 20 are similar to cycle 23 in their respective descending phases. Using this similarity and the observed data of smoothed monthly mean sunspot numbers (SMSNs) available for the descending phase of cycle 23, we make a date calibration for the average time sequence made of the three descending phases of the three cycles, and predict the start of March or April 2008 for cycle 24. For the three cycles, we also find a linear correlation of the length of the descending phase of a cycle with the difference between the maximum epoch of this cycle and that of its next cycle.Using this relationship along with the known relationship between the rise-time and the maximum amplitude of a slowly rising solar cycle, we predict the maximum SMSN of cycle 24 of 100.2±7.5 to appear during the period from May to October 2012.

  1. How muscles define maximum running performance in lizards: an analysis using swing- and stance-phase muscles.

    Higham, Timothy E; Korchari, Paul G; McBrayer, Lance D


    Maximum locomotor performance is crucial for capturing prey, escaping predators and many other behaviors. However, we know little about what defines maximum performance in vertebrates. Muscles drive the movement of the limbs during locomotion, and thus likely play a major role in defining locomotor capacity. For lizards, the iliofibularis, a swing-phase muscle, is often linked to ecology and/or performance. However, stance-phase muscles likely limit performance given that they propel the animal. Using a small semi-arboreal lizard (Sceloporus woodi), we compared how swing- and stance-phase muscles relate to maximum running speed and acceleration. We employed both a level and vertical trackway to elicit ecologically relevant locomotor performance. Six individuals were filmed at 250 frames s⁻¹ in lateral view. Following performance trials, upper and lower hindlimbs were sectioned and assessed using histochemistry. Fast glycolytic, fast oxidative and slow oxidative fibers were detected and counted in the gastrocnemius (GA; stance phase) and iliofibularis (IF; swing phase) muscles. In addition, the mean fiber diameter for each fiber type in each muscle was determined, as was the fiber cross-sectional area. We found that properties of the GA, but not the IF, were positively correlated with performance. Interestingly, certain attributes of the GA were correlated with maximum vertical locomotion whereas others were correlated with maximum level locomotion. We conclude that stance phase, not swing phase, limits maximum performance in this species of lizard. In addition, we highlight the need to include properties of stance-phase muscles and a spectrum of ecologically relevant behaviors when attempting to correlate locomotor physiology with ecology and/or performance.

  2. Observation of microarray DNA hybridization using surface plasmon resonance phase-shift interferometry

    Chen, Shean-Jen; Tsou, C.-Y.; Chen, Y.-K.; Su, Y.-T.


    Surface plasmon resonance phase-shift interferometry (SPR-PSI) is a novel technique which combines SPR and modified Mach-Zehnder phase-shifting interferometry to measure the spatial phase variation caused by biomolecular interactions upon a sensing chip. The SPR-PSI imaging system offers high resolution and high-throughout screening capabilities for microarray DNA hybridization without the need for additional labeling, and provides valuable real-time quantitative information. Current SPR-PSI imaging systems measure the spatial phase variation caused by tiny biomolecular changes on the sensing interface by means of a five-step phase reconstruction algorithm and a novel multichannel least mean squares (MLMS) phase unwrapping algorithm. The SPR-PSI imaging system has an enhanced detection limit of 2.5 × 10-7 refraction index change, a long-term phase stability of π/100 in 30 minutes, and a spatial phase resolution of π/500 with a lateral resolution of 10μm. This study successfully demonstrates the kinetic and label-free observation of 5-mer DNA microarray hybridization.

  3. 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.


    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.

  4. Fuzzy Determination of Target Shifting Time and Torque Control of Shifting Phase for Dry Dual Clutch Transmission

    Zhiguo Zhao


    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.

  5. Full-Quantum chemical calculation of the absorption maximum of bacteriorhodopsin: a comprehensive analysis of the amino acid residues contributing to the opsin shift

    Hayashi, Tomohiko; Matsuura, Azuma; Sato, Hiroyuki; Sakurai, Minoru


    Herein, the absorption maximum of bacteriorhodopsin (bR) is calculated using our recently developed method in which the whole protein can be treated quantum mechanically at the level of INDO/S-CIS//ONIOM (B3LYP/6-31G(d,p): AMBER). The full quantum mechanical calculation is shown to reproduce the so-called opsin shift of bR with an error of less than 0.04 eV. We also apply the same calculation for 226 different bR mutants, each of which was constructed by replacing any one of the amino acid residues of the wild-type bR with Gly. This substitution makes it possible to elucidate the extent to which each amino acid contributes to the opsin shift and to estimate the inter-residue synergistic effect. It was found that one of the most important contributions to the opsin shift is the electron transfer from Tyr185 to the chromophore upon excitation. We also indicate that some aromatic (Trp86, Trp182) and polar (Ser141, Thr142) residues, located in the vicinity of the retinal polyene chain and the β-ionone ring, respectively, play an important role in compensating for the large blue-shift induced by both the counterion residues (Asp85, Asp212) and an internal water molecule (W402) located near the Schiff base linkage. In particular, the effect of Trp86 is comparable to that of Tyr185. In addition, Ser141 and Thr142 were found to contribute to an increase in the dipole moment of bR in the excited state. Finally, we provide a complete energy diagram for the opsin shift together with the contribution of the chromophore-protein steric interaction. PMID:27493528

  6. Twin-image reduction method for in-line digital holography using periphery and random reference phase-shifting techniques

    Oshima, Teppei; Matsudo, Yusuke; Kakue, Takashi; Arai, Daisuke; Shimobaba, Tomoyoshi; Ito, Tomoyoshi


    Digital holography has the twin image problem that unwanted lights (conjugate and direct lights) overlap in the object light in the reconstruction process. As a method for extracting only the object light, phase-shifting digital holography is widely used; however, this method is not applicable for the observation of moving objects, because this method requires the recording of plural holograms. In this study, we propose a twin-image reduction method by combining the "periphery" method with the "random phase-shifting" method. The proposed method succeeded in improving the reconstruction quality, compared to other one-shot recording methods ("parallel phase-shifting digital holography" and "random phase-shifting").

  7. Fully characterization of an active optical filter based on an equivalent-phase-shifted DFB-SOA

    Deng, Ye; Li, Ming; Shi, Nuannuan; Tang, Jian; Sun, Shuqian; Zhang, Lihong; Li, Wei; Zhu, Ninghua


    A fully characterization of an active optical filter based on an equivalent-phase-shifted DFB-SOA has been theoretically analyzed and experimentally demonstrated in this paper. By employing an optical vector network analyzer (OVNA), transmission characteristics of the equivalent-phase-shifted DFB-SOA are obtained. The influences of driven current on transmission characteristics of the equivalent-phase-shifted DFB-SOA are also investigated. In addition to the advantage of integration, the proposed equivalent-phase-shifted DFB-SOA also shows significant application in design of photonic devices for all-optical signal processing and computing.

  8. Shifting of wrapped phase maps in the frequency domain using a rational number

    Gdeisat, Munther A.; Burton, David R.; Lilley, Francis; Arevalillo-Herráez, Miguel; Abushakra, Ahmad; Qaddoura, Maen


    The number of phase wraps in an image can be either reduced, or completely eliminated, by transforming the image into the frequency domain using a Fourier transform, and then shifting the spectrum towards the origin. After this, the spectrum is transformed back to the spatial domain using the inverse Fourier transform and finally the phase is extracted using the arctangent function. However, it is a common concern that the spectrum can be shifted only by an integer number, meaning that the phase wrap reduction is often not optimal. In this paper we propose an algorithm than enables the spectrum to be frequency shifted by a rational number. The principle of the proposed method is confirmed both by using an initial computer simulation and is subsequently validated experimentally on real fringe patterns. The technique may offer in some cases the prospects of removing the necessity for a phase unwrapping process altogether and/or speeding up the phase unwrapping process. This may be beneficial in terms of potential increases in signal recovery robustness and also for use in time-critical applications.

  9. Measurement of mean thickness of transparent samples using simultaneous phase shifting interferometry with four interferograms.

    Flores Muñoz, V H; Arellano, N-I Toto; Serrano García, D I; Martínez García, A; Rodríguez Zurita, G; García Lechuga, L


    In this research a novel interferometric system is reported, which allows the generation of four simultaneous interferograms with phase shifts of π/2. The system consists of three coupled interferometers: a rectangular Sagnac interferometer which generates a primary pattern with crossed circular polarizations, coupled to two Michelson interferometers which operate as a multiplexing system, and generating replicas of the primary pattern. The two coupled Michelson interferometers generate four patterns retaining their polarization properties, which allow independent phase shifts by placing a linear polarizer over each pattern, thereby, four interferograms with relative phase shifts of π/2 are obtained. The optical phase is calculated using the well-known four-step algorithm. With knowledge of the optical phase, different properties of the samples can be calculated or analyzed; in this case, by knowing the mean refractive index, we can calculate the mean thickness of test objects. The results obtained for static transparent samples are presented. The capability of the system to analyze dynamic events is shown when results for the calculation of a temperature field of a heat flow are presented.

  10. A novel modulation and direct detection scheme of optical phase shift keying

    Yongcai Yang(杨永才); Wolfgang Vogel


    This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK)which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.

  11. Wavelet filtered shifted phase-encoded joint transform correlation for face recognition

    Moniruzzaman, Md.; Alam, Mohammad S.


    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.

  12. 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


    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.

  13. The multifaceted Type II-L supernova 2014G from pre-maximum to nebular phase

    Terreran, G.; Jerkstrand, A.; Benetti, S.; Smartt, S. J.; Ochner, P.; Tomasella, L.; Howell, D. A.; Morales-Garoffolo, A.; Harutyunyan, A.; Kankare, E.; Arcavi, I.; Cappellaro, E.; Elias-Rosa, N.; Hosseinzadeh, G.; Kangas, T.; Pastorello, A.; Tartaglia, L.; Turatto, M.; Valenti, S.; Wiggins, P.; Yuan, F.


    We present multiband ultraviolet, optical, and near-infrared photometry, along with visual-wavelength spectroscopy, of supernova (SN) 2014G in the nearby galaxy NGC 3448 (25 Mpc). The early-phase spectra show strong emission lines of the high ionization species He II/N IV/C IV during the first 2-3 d after explosion, traces of a metal-rich circumstellar material (CSM) probably due to pre-explosion mass-loss events. These disappear by day 9 and the spectral evolution then continues matching that of normal Type II SNe. The post-maximum light curve declines at a rate typical of Type II-L class. The extensive photometric coverage tracks the drop from the photospheric stage and constrains the radioactive tail, with a steeper decline rate than that expected from the 56Co decay if γ-rays are fully trapped by the ejecta. We report the appearance of an unusual feature on the blue side of H α after 100 d, which evolves to appear as a flat spectral feature linking H α and the [O I] doublet. This may be due to interaction of the ejecta with a strongly asymmetric, and possibly bipolar CSM. Finally, we report two deep spectra at ˜190 and 340 d after explosion, the latter being arguably one of the latest spectra for a Type II-L SN. By modelling the spectral region around the [Ca II], we find a supersolar Ni/Fe production. The strength of the [O I] λλ6300,6363 doublet, compared with synthetic nebular spectra, suggests a progenitor with a zero-age main-sequence mass between 15 and 19 M⊙.

  14. Interference of the Bloch phase in layered materials with stacking shifts

    Akashi, Ryosuke; Iida, Yo; Yamamoto, Kohei; Yoshizawa, Kanako


    In periodic systems, electronic wave functions of the eigenstates exhibit the periodically modulated Bloch phases and are characterized by their wave numbers k . We theoretically address the effects of the Bloch phase in general layered materials with a stacking shift. When the interlayer shift and the Bloch wave vector k satisfy certain conditions, interlayer transitions of electrons are prohibited by the interference of the Bloch phase. We specify the manifolds in the k space where the hybridization of the Bloch states between the layers is suppressed in accord with the stacking shift. These manifolds, named stacking-adapted interference manifolds (SAIM), are obviously applicable to general layered materials regardless of a detailed atomic configuration within the unit cell. We demonstrate the robustness and usefulness of the SAIM with first-principles calculations for layered boron nitride, transition-metal dichalcogenide, graphite, and black phosphorus. We also apply the SAIM to general three-dimensional crystals to derive special k-point paths for the respective Bravais lattices, along which the Bloch-phase interference strongly suppresses the band dispersion. Our theory provides a general view on the anisotropic electronic motion intrinsic to the periodic-lattice structure.

  15. Altered circadian rhythm and metabolic gene profile in rats subjected to advanced light phase shifts.

    Laura Herrero

    Full Text Available The circadian clock regulates metabolic homeostasis and its disruption predisposes to obesity and other metabolic diseases. However, the effect of phase shifts on metabolism is not completely understood. We examined whether alterations in the circadian rhythm caused by phase shifts induce metabolic changes in crucial genes that would predispose to obesity. Three-month-old rats were maintained on a standard diet under lighting conditions with chronic phase shifts consisting of advances, delays or advances plus delays. Serum leptin, insulin and glucose levels decreased only in rats subjected to advances. The expression of the clock gene Bmal 1 increased in the hypothalamus, white adipose tissue (WAT, brown adipose tissue (BAT and liver of the advanced group compared to control rats. The advanced group showed an increase in hypothalamic AgRP and NPY mRNA, and their lipid metabolism gene profile was altered in liver, WAT and BAT. WAT showed an increase in inflammation and ER stress and brown adipocytes suffered a brown-to-white transformation and decreased UCP-1 expression. Our results indicate that chronic phase advances lead to significant changes in neuropeptides, lipid metabolism, inflammation and ER stress gene profile in metabolically relevant tissues such as the hypothalamus, liver, WAT and BAT. This highlights a link between alteration of the circadian rhythm and metabolism at the transcriptional level.

  16. Optical birefringence and molecular orientation of crazed fibres utilizing the phase shifting interferometric technique

    Sokkar, T. Z. N.; El-Farahaty, K. A.; El-Bakary, M. A.; Omar, E. Z.; Hamza, A. A.


    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.

  17. Carrier-separating demodulation of phase shifting self-mixing interferometry

    Tao, Yufeng; Wang, Ming; Xia, Wei


    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.

  18. Acquiring multi-viewpoint image of 3D object for integral imaging using synthetic aperture phase-shifting digital holography

    Jeong, Min-Ok; Kim, Nam; Park, Jae-Hyeung; Jeon, Seok-Hee; Gil, Sang-Keun


    We propose a method generating elemental images for the auto-stereoscopic three-dimensional display technique, integral imaging, using phase-shifting digital holography. Phase shifting digital holography is a way recording the digital hologram by changing phase of the reference beam and extracting the complex field of the object beam. Since all 3D information is captured by the phase-shifting digital holography, the elemental images for any specifications of the lens array can be generated from single phase-shifting digital holography. We expanded the viewing angle of the generated elemental image by using the synthetic aperture phase-shifting digital hologram. The principle of the proposed method is verified experimentally.

  19. Four-quadrant spatial phase-shifting Fourier transform digital holography for recording of cosine transform coefficients

    Chujun Zheng; Peng Han; Hongsen Chang


    @@ A new one-step four-quadrant spatial phase-shifting Fourier transform digital holography is presented for recording of cosine transform coefficients, because cosine transform is a real-even symmetric Fourier transform. This approach implements four quadrant spatial phase shifting at a time using a special phase mask, which is located in the reference arm, and the phase distributions of its four-quadrants are 0, π/2, π,and 3π/2 respectively. The theoretical analysis and computer simulation results show that cosine transform coefficients of real-valued image can be calculated by capturing single four-quadrant spatial phase-shifting Fourier transform digital hologram.

  20. Application of maximum likelihood to direct methods: the probability density function of the triple-phase sums. XI.

    Rius, Jordi


    The maximum-likelihood method is applied to direct methods to derive a more general probability density function of the triple-phase sums which is capable of predicting negative values. This study also proves that maximization of the origin-free modulus sum function S yields, within the limitations imposed by the assumed approximations, the maximum-likelihood estimates of the phases. It thus represents the formal theoretical justification of the S function that was initially derived from Patterson-function arguments [Rius (1993). Acta Cryst. A49, 406-409].

  1. Security enhancement of the phase-shifting interferometry-based cryptosystem by independent random phase modulation in each exposure

    Liao, Meihua; He, Wenqi; Lu, Dajiang; Wu, Jiachen; Peng, Xiang


    The traditional phase-shifting interferometry (PSI)-based cryptosystem is one of the most classical optical cryptosystems. It employs the Mach-Zahnder interferometer to record the intensity distributions to partly overcome the inconvenience while storing the complex-valued ciphertext in some other optical cryptosystems (e.g., double random phase encoding technique). However, it has been proven to be vulnerable to chosen-plaintext attack and known-plaintext attack. In this manuscript, we propose an alternative method to enhance the security strength of the traditional PSI-based cryptosystem. By substituting the fixed random phase mask (RPM) and the phase retarder in the reference arm with four independent and different RPMs (served as secret keys) in four exposures, we can correspondingly capture four intensity-only patterns (regarded as ciphertexts). Theoretical analysis, especially with respect to security characteristics, as well as the numerical simulations are presented to verify the feasibility and reliability of the proposed cryptosystem.

  2. A portable intra-oral scanner based on sinusoidal pattern of fast phase-shifting

    Jan, Chia-Ming; Lin, Ying-Chieh


    This paper presented our current research about the intra-oral scanner made by MIRDC. Utilizing the sinusoidal pattern for fast phase-shifting technique to deal with 3D digitalization of human dental surface profile, the development of pseudo-phase shifting digital projection can easily achieve one type of full-field scanning instead of the common technique of the laser line scanning. Based on traditional Moiré method, we adopt projecting fringes and retrieve phase reconstruction to forward phase unwrapping. The phase difference between the plane and object can be exactly calculated from the desired fringe images, and the surface profile of object was probably reconstructed by using the phase differences information directly. According to our algorithm of space mapping between projections and capturing orientation exchange of our intra-oral scanning configuration, the system we made certainly can be proved to achieve the required accuracy of +/-10μm to deal with intra-oral scanning on the basis of utilizing active triangulation method. The final purpose aimed to the scanning of object surface profile with its size about 10x10x10mm3.

  3. Low-Energy Kπ Phase Shifts in Chiral SU(3) Quark Model

    HUANG Fei; ZHANG Zong-Ye; YU You-Wen


    The low-energy region kaon-pion S- and P-wave phase shifts with isospin I = 1/2 and I = 3/2 are dynamically studied in the chiral SU(3) quark model by solving a resonating group method equation. The model parameters are taken to be the values fitted by the energies of the baryon ground states and the kaon-nucleon elastic scattering phase shifts of different partial waves. As a preliminary study the s-channel q(-q) annihilation interactions are not included since they only act in the very short range and are subsequently assumed to be unimportant in the low-energy domain. The numerical results are in qualitative agreement with the experimental data.

  4. Scattering phase shift for elastic two pion scattering and the rho resonance in lattice QCD

    Gutzwiller, Simone


    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.

  5. A laterally-coupled distributed feedback laser with equivalent quarter-wave phase shift.

    Li, Jingsi; Cheng, Julian


    We report the first laterally-coupled distributed feedback (LC-DFB) laser with a quarter-wave equivalent phase shift (EPS) realized by interference lithography (IL) and conventional photolithography. A specially designed sampled grating is fabricated on both sidewalls of a ridge waveguide to provide a quarter-wave EPS at the center of the cavity. The resulting laser exhibits stable single-mode lasing operation over a wide range of injection currents, with a side mode suppression ratio (SMSR) of 41.1 dB. This provides a practical, low-cost method to fabricate quarter-wave phase shifted DFB lasers with high performance without any epitaxial regrowth or the use of electron-beam lithography, thereby simplifying the fabrication of DFB lasers with stable and precise wavelengths, as single devices or as arrays in photonic integrated circuits.

  6. Ultrasonic sensor employing two cascaded phase-shifted fiber Bragg gratings suitable for multiplexing.

    Wu, Qi; Okabe, Yoji


    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.

  7. New technique for phase shift analysis multi-energy solution of inverse scattering problem

    Cooper, S G; MacIntosh, R S; Kuznetsova, E V


    We demonstrate a new approach to the analysis of extensive multi-energy data. For the case of d + He-4, we produce a phase shift analysis covering for the energy range 3 to 11 MeV. The key idea is the use of iterative perturbative data-to-potential inversion which can produce potentials which reproduce the data simultaneously over a range of energies. It thus effectively regularizes the extraction of phase shifts from diverse, incomplete and possibly somewhat contradictory data sets. In doing so, it will provide guidance to experimentalists as to what further measurements should be made. This study is limited to vector spin observables and spin-orbit interactions. We discuss alternative ways in which the theory can be implemented and which provide insight into the ambiguity problems. We compare the extrapolation of these solutions to other energies. Majorana terms are presented for each potential component.

  8. Optical image hiding based on dual-channel simultaneous phase-shifting interferometry and compressive sensing

    Li, Jiaosheng; Zhong, Liyun; Zhang, Qinnan; Zhou, Yunfei; Xiong, Jiaxiang; Tian, Jindong; Lu, Xiaoxu


    We propose an optical image hiding method based on dual-channel simultaneous phase-shifting interferometry (DCSPSI) and compressive sensing (CS) in all-optical domain. In the DCSPSI architecture, a secret image is firstly embedded in the host image without destroying the original host's form, and a pair of interferograms with the phase shifts of π/2 is simultaneously generated by the polarization components and captured by two CCDs. Then, the holograms are further compressed sampling to the less data by CS. The proposed strategy will provide a useful solution for the real-time optical image security transmission and largely reducing data volume of interferogram. The experimental result demonstrates the validity and feasibility of the proposed method.

  9. Non-iterative coherent diffractive imaging using a phase-shifting reference frame

    Enders, B; Giewekemeyer, K; Salditt, T [Institut fuer Roentgenphysik, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Kurz, T [III. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Podorov, S [School of Physics, Monash University, Victoria 3800 (Australia)], E-mail:


    Lensless imaging is a high potential and currently intensely targeted research goal, in view of those fields of applications for which aberration-free high-resolution lenses are not available, for example for x-ray imaging. A recently proposed (direct inversion) variant of lensless imaging combines the advantages of two classical routes toward lensless imaging, the high-resolution characteristics of iterative object reconstruction, and the direct and deterministic nature of holographic reconstruction. Here, we use a simple standard optical setup using visible wavelength, a lithographic test object and a phase-shifting reference object to demonstrate the approach. Importantly, we show that a phase-shifting reference object, instead of the absorption mask proposed earlier, is sufficient for object reconstruction. This is relevant in view of the much easier implementation in future x-ray applications.

  10. The I=2 pipi S-wave Scattering Phase Shift from Lattice QCD

    Beane, S. R.; Chang, E.; Detmold, W.; Lin, H. W.; Luu, T. C.; Orginos, K.; Parreno, A.; Savage, M. J.; A. Torok; Walker-Loud, A.


    The pi+pi+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of m_pi~390 MeV with an anisotropic n_f=2+1 clover fermion discretization in four lattice volumes, with spatial extent L~2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of b_s~0.123 fm in the spatial direction and b_t b_s/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of pi+pi+ systems with both zero and n...

  11. The S/sub 11/-P/sub 11/ phase shifts of pion-nucleon scattering

    Barron, R H


    The S/sub 11/ and P/sub 11/ partial amplitude is calculated using the N/D method. The present calculation differs from the previous ones in the handling of the divergent behaviour of the forces due to first- order diagrams, by parametrizing the short-range forces, and in the way of including inelasticity. The nucleon is obtained as a bound state with correct mass and residue and the correct S/sub 11/ and P /sub 11/ scattering lengths. The calculated S-wave and P-wave phase shifts and absorption coefficients are in substantial agreement with those from the CERN theoretical (1970) and Almehed-Lovelace (1972) phase shift analyses. (22 refs).

  12. Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

    王立乔; 李建林; 张仲超


    A novel current-source active power filter(APF)based on multi-modular converter with carrier phase-shifted SPWM(CPS-SPWM)technique is proposed.With this technique,the effect of equivalent high switching frequency converter is obtained with low switching frequency converter.It is very promising in current-source APF that adopt superconducting magnetic energy storage component.

  13. Variable-length balanced codes for quadrature phase shift keyed systems

    Xin Tu


    Full Text Available The authors outline an approach to construct capacity-approaching balanced quadrature phase shift keyed (QPSK codes. These codes ensure an equal number of different symbol values and many symbol transitions in the encoded sequence in order to assist practical demodulators to accurately recover symbol values. Their codes are comprised of instantaneously decodable variable-length codewords that exhibit excellent performance with average code rates higher than previously reported fixed-length balanced QPSK codes.

  14. Phase-Shift Cyclic-Delay Diversity for MIMO OFDM Systems

    Young-Han Nam


    Full Text Available Phase-shift cyclic-delay diversity (PS CDD scheme and space-frequency-block-code (SFBC PS CDD are developed for multiple-input-multiple-output (MIMO orthogonal frequency division multiplexing (OFDM systems. The proposed PS CDD scheme preserves the diversity advantage of traditional CDD in uncorrelated multiantenna channels, and furthermore removes frequency-selective nulling problem of the traditional CDD in correlated multiantenna channels.

  15. Attenuated phase-shift mask (PSM) blanks for flat panel display

    Kageyama, Kagehiro; Mochizuki, Satoru; Yamakawa, Hiroyuki; Uchida, Shigeru


    The fine pattern exposure techniques are required for Flat Panel display applications as smart phone, tablet PC recently. The attenuated phase shift masks (PSM) are being used for ArF and KrF photomask lithography technique for high end pattern Semiconductor applications. We developed CrOx based large size PSM blanks that has good uniformity on optical characteristics for FPD applications. We report the basic optical characteristics and uniformity, stability data of large sized CrOx PSM blanks.

  16. Investigation of carbon dioxide phase shift possibility under extreme Antarctic winter conditions

    Vashchenko, V M


    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.

  17. A quasi-symmetric beam splitter with 90° phase shift for p-polarized light

    Mamaev, Yu. A.


    A beam splitter with a two-layer metal-dielectric structure in a Michelson interferometer is considered. It is shown that introduction of an additional dielectric interference layer makes it possible to reduce significantly (in comparison with a beam splitter with one metal layer) the difference in the reflectance from the side of air, the reflectance from the side of substrate, and the transmittance for p-polarized light, with conservation of a 90° phase shift for two outputs.

  18. Relativistic description of single-particle resonances via phase shift analysis

    ZHANG Zi-Zhen


    Single-particle resonant states in spherical nuclei are studied by the real stabilization method in coordinate space within the framework of self-consistent relativistic mean field theory. Taking 122Zr as an example, the resonant parameters, including the energies and widths are extracted by fitting energy and phase shift. Good agreement with the previous calculations has been found. The details of single-particle resonant states are analysed.

  19. Differential-phase-shift quantum key distribution using heralded narrow-band single photons.

    Liu, Chang; Zhang, Shanchao; Zhao, Luwei; Chen, Peng; Fung, C-H F; Chau, H F; Loy, M M T; Du, Shengwang


    We demonstrate the first proof of principle differential phase shift (DPS) quantum key distribution (QKD) using narrow-band heralded single photons with amplitude-phase modulations. In the 3-pulse case, we obtain a quantum bit error rate (QBER) as low as 3.06% which meets the unconditional security requirement. As we increase the pulse number up to 15, the key creation efficiency approaches 93.4%, but with a cost of increasing the QBER. Our result suggests that narrow-band single photons maybe a promising source for the DPS-QKD protocol.

  20. Double-image encryption based on joint transform correlation and phase-shifting interferometry

    Lina Shen; Jun Li; Hongsen Chang


    An image encryption method combining the joint transform correlator (JTC) architecture with phaseshifting interferometry to realize double random-phase encoding is proposed. The encrypted field and the decrypting key are registered as holograms by phase-shifting interferometry. This method can encrypt two images simultaneously to improve the encryption efficiency of the methods based on JTC architecture, and eliminate the system alignment constraint of the methods based on Mach-Zehnder interferometer (MZI)architecture. Its feasibility and validity are verified by computer simulations. Moreover, image encryption and decryption can be achieved at high speed optically or digitally. The encrypted data are suitable for Internet transmission.

  1. Bandpass transmission filters based on phase shifted fiber Bragg gratings in microstructured polymer optical fibers

    Ortega, Beatriz; Min, Rui; Sáez-Rodri­guez, David


    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......é structures with a single or various π 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...

  2. Phase shifts and the second virial coefficient for a partially ionized hydrogen plasma

    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)


    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.)

  3. Duffing revisited: phase-shift control and internal resonance in self-sustained oscillators

    Arroyo, Sebastián I.; Zanette, Damián H.


    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, have intrinsic significance to the field of nonlinear 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, and provide analytical approximate expressions for the time dependence of the oscillation amplitude and frequency during transients. 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 when the resonance takes place, and present preliminary experimental results that illustrate the phenomenon. This synchronization process has been proposed to counteract the undesirable frequency-amplitude interdependence in nonlinear time-keeping micromechanical devices. Supplementary material in the form of one pdf file and one gif file available from the Journal web page at

  4. The I=2 pipi S-wave Scattering Phase Shift from Lattice QCD

    Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A


    The pi+pi+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of m_pi~390 MeV with an anisotropic n_f=2+1 clover fermion discretization in four lattice volumes, with spatial extent L~2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of b_s~0.123 fm in the spatial direction and b_t b_s/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of pi+pi+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enough to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: m_pi^2 a r = 3+O(m_pi^2/Lambda_chi^2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the phys...

  5. Instantaneous phase shift of annual subsurface temperature cycles derived by the Hilbert-Huang transform

    Sun, Yang-Yi; Chen, Chieh-Hung; Liu, Jann-Yenq; Wang, Chung-Ho; Chen, Deng-Lung


    This study uses the Hilbert-Huang transform to compute the instantaneous (daily) phase shift between temperature signals at the ground surface and at a depth of 5 m. This approach is not restricted to the stationary harmonic surface temperature assumptions invoked by analytical solutions. The annual cycles are extracted from the ground surface temperatures and the shallow subsurface temperatures at 5 m depth recorded at the Hualien (23.98°N, 121.61°E) and Ilan (24.77°N, 121.75°E) meteorology stations of Central Weather Bureau in Taiwan from 1952 to 2008. Significant reductions in the phase shift and increases in the estimated thermal diffusivity from 1980s to 1990s are found and suggest that the recent warming of the Pacific Decadal Oscillation may affect heat transport in the subsurface environment. The marginal spectra of the instantaneous phase shifts and the precipitation intensity records at Hualien and Ilan reveal that precipitation may play a role in the evolution of seasonal variation in shallow subsurface heat transport.

  6. Phase-shift analysis of low-energy $\\pi^{\\pm}p$ elastic-scattering data

    Matsinos, E; Oades, G C; Rasche, G; Woolcock, W S


    Using electromagnetic corrections previously calculated by means of a potential model, we have made a phase-shift analysis of the $\\pi^\\pm p$ 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 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 $\\pi N N$ coupling constant (in the standard form) is $0.0733 \\pm 0.0014$. 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 t...

  7. Study of Power Coefficient and Insertion Phase Shift for Organic Magnetic Slab

    Li Gao-sheng


    Full Text Available In this paper, theories of electromagnetic reflection and transmission as well as transmission line are adopted, a simulation method is designed to calculate power transmission coefficient and insertion phase shift, and also the mathematical formulas are deduced that the electromagnetic parameters of material used in radomes must be satisfied to remove the depolarization phenomenon, a single magnetic slab is used to discuss and verify the formulas. A special A sandwich radome, as a example, is calculated to analysis the effects of the magnetic and dielectric materials on the power transmission coefficient and the insertion phase shift. It is found that the phenomenon of depolarization can be avoided for A sandwich radome structure once when r r ε = μ (the relative complex permittivity of the magnetic material equals its relative complex permeability, and the power of transmission coefficient for magnetic material is better, the insertion phase shift is smoother, and the property of transmission performance is better than those of the electric material. Finally, the commercial software HFSS further verifies the correctness of the conclusions and validity of the method.

  8. A dual-mode phase-shift modulation control scheme for voltage multiplier based X-ray power supply

    Iqbal, S [School of Electrical and Electronics Engineering, University Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Besar, R; Venkataseshaiah, C, E-mail: [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)


    This paper proposes a dual-mode phase-shift modulation control scheme for series resonant inverter fed voltage multiplier (VM) based X-ray power supply. In this control scheme the outputs voltage of two parallel connected series resonant inverters are mixed before supplying to VM circuit. The output voltage of the power supply is controlled by varying the phase-shift between the output voltages of two inverters. In order to achieve quick rise of output voltage, the power supply is started with zero phase-shift and as the output voltage reaches 90% of the target voltage, the phase-shift is increased to a value which corresponds to target output voltage to prevent overshoot. The proposed control scheme has been shown to have good performance. Experimental results based on the scaled-down laboratory prototype are presented to validate the effectiveness of proposed dual-mode phase shift modulation control scheme.

  9. Study on an improved five-interferogram phase-shifting algorithm

    Zhiyong Luo; Jialin Dai


    Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique.Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented.This improved algorithm not only keeps the high accuracy of traditional five-interferogram algorithm, but also does not need absolute equal step to unwrap phase.Instead, this algorithm only needs measuring phase-shifting.With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice.It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer.

  10. Effect of Phase Shifted Frequency Modulation on Two Level Atom-Field Interaction

    K.V. Priyesh; Ramesh Babu Thayyullathil


    We have studied the effect of phase shifted frequency modulation on two level atom with field interaction using Jaynes-Cummings model. Here the frequency of the interacting field is sinusoidally varying with time with a constant phase. Due to the presence of phase in the frequency modulation, the variation of population inversion with time is different from the standard case. There are no exact collapses and revivals in the variation of population inversion but it oscillates sinusoidally with time. In coherent field atom interaction the population inversion behaves as in the case of Fock state atom interaction, when frequency modulation with a non zero phase is applied. The study done with squeezed field has shown the same behavior of the population inversion.

  11. High-speed 3D imaging using two-wavelength parallel-phase-shift interferometry.

    Safrani, Avner; Abdulhalim, Ibrahim


    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.

  12. Measurement of absolute phase Shift on reflection of thin films using white-light spectral interferometry

    Hui Xue; Weidong Shen; Peifu Gu; Zhenyue Luo; Yueguang Zhang; Xu Liu


    A novel method to measure the absolute phase shift on reflection of thin film is presented utilizing a white-light interferometer in spectral domain.By applying Fourier transformation to the recorded spectral interference signal,we retrieve the spectral phase function ф,which is induced by three parts:the path length difference in air L,the effective thickness of slightly dispersive cube beam splitter Teff and the nonlinear phase function due to multi-reflection of the thin film structure.We utilize the fact that the overall optical path difference(OPD)is linearly dependent on the refractive index of the beam splitter to determine both L and Teff.The spectral phase shift on reflection of thin film structure can be obtained by subtracting these two parts from ф.We show theoretically and experimentally that our now method can provide a sinlple and fast solution in calculating the absolute spectral phase function of optical thin films,while still maintaining high accuracy.

  13. 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


    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)

  14. Design of Three-Phase Three-Level CIC T-Source Inverter with Maximum Boost Control

    Shults, Tatiana; Husev, Oleksandr; Roncero-Clemente, Carlos


    This paper presents guidelines for component design of the three-level three-phase T-source inverter with continuous input current under maximum boost control proposed recently. Steady state analysis under low-frequency current and voltage ripples in the dc side was made. Component sizes for both...

  15. Phase-shifting algorithms for a finite number of harmonics: first-order analysis by solving linear systems.

    Téllez-Quiñones, Alejandro; Malacara-Doblado, Daniel; García-Márquez, Jorge


    From generalized phase-shifting equations, we propose a simple linear system analysis for algorithms with equally and nonequally spaced phase shifts. The presence of a finite number of harmonic components in the fringes of the intensity patterns is taken into account to obtain algorithms insensitive to these harmonics. The insensitivity to detuning for the fundamental frequency is also considered as part of the description of this study. Linear systems are employed to recover the desired insensitivity properties that can compensate linear phase shift errors. The analysis of the wrapped phase equation is carried out in the Fourier frequency domain.

  16. Reply to Comment on ‘Roles of interbasin frequency changes in the poleward shifts of maximum intensity location of tropical cyclones’

    Moon, Il-Ju; Kim, Sung-Hun; Klotzbach, Phil; Chan, Johnny C. L.


    Recently a pronounced global poleward shift in the latitude at which the maximum intensities of tropical cyclones (TC) occur has been identified. Moon et al (2015 Environ. Res. Lett. 10 104004) reported that the poleward migration is significantly influenced by changes in interbasin frequency. These frequency changes are a larger contributor to the poleward shift than the intrabasin migration component. The strong role of interbasin frequency changes in the poleward migration also suggest that the poleward trend could be changed to an opposite equatorward trend in the future due to multi-decadal variability that significantly impacts Northern Hemisphere TC frequency. In the accompanying comment, Kossin et al (2016 Environ. Res. Lett. 11 068001) questioned the novelty and robustness of our results by raising issues associated with subsampling, contributions from some basins to poleward migration, and data dependency. Here, we explain the originality and importance of our main findings, which are different from those of Kossin et al (2014 Nature 509 349-52) and reaffirm that our conclusions are maintained regardless of the issues that were raised.

  17. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    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

  18. Simultaneous maximum-likelihood reconstruction for x-ray grating based phase-contrast tomography avoiding intermediate phase retrieval

    Ritter, André; Durst, Jürgen; Gödel, Karl; Haas, Wilhelm; Michel, Thilo; Rieger, Jens; Weber, Thomas; Wucherer, Lukas; Anton, Gisela


    Phase-wrapping artifacts, statistical image noise and the need for a minimum amount of phase steps per projection limit the practicability of x-ray grating based phase-contrast tomography, when using filtered back projection reconstruction. For conventional x-ray computed tomography, the use of statistical iterative reconstruction algorithms has successfully reduced artifacts and statistical issues. In this work, an iterative reconstruction method for grating based phase-contrast tomography is presented. The method avoids the intermediate retrieval of absorption, differential phase and dark field projections. It directly reconstructs tomographic cross sections from phase stepping projections by the use of a forward projecting imaging model and an appropriate likelihood function. The likelihood function is then maximized with an iterative algorithm. The presented method is tested with tomographic data obtained through a wave field simulation of grating based phase-contrast tomography. The reconstruction result...

  19. Phase control of Goos-Hänchen shift via biexciton coherence in a multiple quantum well

    Asadpour, Seyyed Hossein; Nasehi, Rajab; Soleimani, H. Rahimpour; Mahmoudi, M.


    The behavior of the Goos-Hänchen (GH) shifts of the reflected and transmitted probe and signal pulses through a cavity containing four-level GaAs/AlGaAs multiple quantum wells with 15 periods of 17.5 nm GaAs wells and 15-nm Al0.3Ga0.7As barriers is theoretically discussed. The biexciton coherence set up by two coupling fields can induce the destructive interference to control the absorption and gain properties of probe field under appropriate conditions. It is realized that for the specific values of the intensities and the relative phase of applied fields, the simultaneous negative or positive GH shift in the transmitted and reflected light beam can be obtained via amplification in a probe light. It is found that by adjusting the controllable parameters, the GH shifts can be switched between the large positive and negative values in the medium. Moreover, the effect of exciton spin relaxation on the GH shift has also been discussed. We find that the exciton spin relaxation can manipulate the behavior of GH shift in the reflected and transmitted probe beam through the cavity. We show that by controlling the incident angles of probe beam and under certain conditions, the GH shifts in the reflected and transmitted probe beams can become either negative or positive corresponding to the superluminal or subluminal light propagation. Our proposed model may supply a new prospect in technological applications for the light amplification in optical sensors working on quantum coherence impacts in solid-state systems.

  20. Shifting Phases for Patchy Particles - Effect of mutagenesis and chemical modification on the phase diagram of human gamma D crystallin

    McManus, Jennifer J.; James, Susan; McNamara, Ruth; Quinn, Michelle


    Single mutations in human gamma D crystallin (HGD), a protein found in the eye lens are associated with several childhood cataracts. Phase diagrams for several of these protein mutants have been measured and reveal that phase boundaries are shifted compared with the native protein, leading to condensation of protein in a physiologically relevant regime. Using HGD as a model protein, we have constructed phase diagrams for double mutants of the protein, incorporating two single amino acid substitutions for which phase diagrams are already known. In doing so, the characteristics of each of the single mutations are maintained but both are now present in the same protein particle. While these proteins are not of interest physiologically, this strategy allows the controlled synthesis of nano-scale patchy particles in which features associated with a known phase behavior can be included. It can also provide a strategy for the controlled crystallisation of proteins. Phase boundaries also change after the chemical modification of the protein, through the covalent attachment of fluorescent labels, for example, and this will also be discussed. The authors acknowledge Science Foundation Ireland Stokes Lectureship and Grant 11/RFP.1/PHY/3165. The authors also acknowledge the Irish Research Council and the John and Pat Hume Scholarship.

  1. Optimal shifting control strategy in inertia phase of an automatic transmission for automotive applications

    Meng, Fei; Tao, Gang; Zhang, Tao; Hu, Yihuai; Geng, Peng


    Shifting quality is a crucial factor in all parts of the automobile industry. To ensure an optimal gear shifting strategy with best fuel economy for a stepped automatic transmission, the controller should be designed to meet the challenge of lacking of a feedback sensor to measure the relevant variables. This paper focuses on a new kind of automatic transmission using proportional solenoid valve to control the clutch pressure, a speed difference of the clutch based control strategy is designed for the shift control during the inertia phase. First, the mechanical system is shown and the system dynamic model is built. Second, the control strategy is designed based on the characterization analysis of models which are derived from dynamics of the drive line and electro-hydraulic actuator. Then, the controller uses conventional Proportional-Integral-Derivative control theory, and a robust two-degree-of-freedom controller is also carried out to determine the optimal control parameters to further improve the system performance. Finally, the designed control strategy with different controller is implemented on a simulation model. The compared results show that the speed difference of clutch can track the desired trajectory well and improve the shift quality effectively.

  2. 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


    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.

  3. Band-gaps in long Josephson junctions with periodic phase-shifts

    Ahmad, Saeed; Susanto, Hadi; Wattis, Jonathan A. D.


    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.

  4. Phase-shifting Real-time Holographic Microscopy applied in micro-structures surface analysis

    Brito, I V; Gesualdi, M R R [Universidade Federal do ABC, R. Santa Adelia 166, Bangu, Santo Andre, 09210-170, SP (Brazil); Muramatsu, M [Instituto de Fisica, Universidade de Sao Paulo, Rua do Matao, Travessa R 186, Cidade Universitaria, 05508-090, Sao Paulo, SP (Brazil); Ricardo, J, E-mail: [Universidad de Oriente, Ave. Patricio Lumumba s/n, Santiago de Cuba (Cuba)


    The microscopic real-time analysis of micro structured materials is of great importance in various domains of science and technology. For other hand, the holographic interferometry comprises a group of powerful optical methods for non-destructive testing in surface analysis. The holographic microscopy uses the holographic interferometric techniques to obtain quantitative intensity and phase information of the optical waves by microscopic systems. With the development of CCD cameras, computers (hardware and software), and new materials for holographic recording, these techniques can be used to replace the classical form of registration and became promising tools in surface analysis. In this work, we developed a prototype of Photorefractive and Digital Holographic Microscope for real-time analysis of micro-structured systems based on the phase-shifting real-time holographic interferometry techniques. Using this apparatus, we are made analysis of shapes and surfaces to obtain the phase maps and the 3D profiles of some samples.

  5. Period coded phase shifting strategy for real-time 3-D structured light illumination.

    Wang, Yongchang; Liu, Kai; Hao, Qi; Lau, Daniel L; Hassebrook, Laurence G


    Phase shifting structured light illumination for range sensing involves projecting a set of grating patterns where accuracy is determined, in part, by the number of stripes. However, high pattern frequencies introduce ambiguities during phase unwrapping. This paper proposes a process for embedding a period cue into the projected pattern set without reducing the signal-to-noise ratio. As a result, each period of the high frequency signal can be identified. The proposed method can unwrap high frequency phase and achieve high measurement precision without increasing the pattern number. Therefore, the proposed method can significantly benefit real-time applications. The method is verified by theoretical and experimental analysis using prototype system built to achieve 120 fps at 640 × 480 resolution.

  6. Circadian waveform bifurcation, but not phase-shifting, leaves cued fear memory intact.

    Harrison, E M; Carmack, S A; Block, C L; Sun, J; Anagnostaras, S G; Gorman, M R


    In mammals, memory acquisition and retrieval can be affected by time of day, as well as by manipulations of the light/dark cycle. Under bifurcation, a manipulation of circadian waveform, two subjective days and nights are experimentally induced in rodents. We examined the effect of bifurcation on Pavlovian fear conditioning, a prominent model of learning and memory. Here we demonstrate that bifurcation of the circadian waveform produces a small deficit in acquisition, but not on retrieval of fear memory. In contrast, repeated phase-shifting in a simulated jet-lag protocol impairs retrieval of memory for cued fear. The results have implications for those attempting to adjust to shift-work or other challenging schedules.

  7. Simultaneous dual directional strain measurement using spatial phase-shift digital shearography

    Wang, Yonghong; Gao, Xinya; Xie, Xin; Wu, Sijing; Liu, Yingxue; Yang, Lianxiang


    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.

  8. Shifting the phase of a coherent beam with a $^{174}$Yb$^+$ ion: influence of the scattering cross section

    Fischer, Martin; Alber, Lucas; Weber, Markus; Sondermann, Markus; Leuchs, Gerd


    We discuss and measure the phase shift imposed onto a radially polarized light beam when focusing it onto an $^{174}\\text{Yb}^{+}$ ion. In the derivation of the expected phase shifts we include the properties of the involved atomic levels. Furthermore, we emphasize the importance of the scattering cross section and its relation to the efficiency for coupling the focused light to an atom. The phase shifts found in the experiment are compatible with the expected ones when accounting for known deficiencies of the focusing optics and the motion of the trapped ion at the Doppler limit of laser cooling.


    A. V. Volkov


    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

  10. Optical differential phase-shift keyed signal generation, transmission and detection

    Lize, Yannick Keith

    When encoding information on an electromagnetic wave such as infrared light, to be transmitted through an optical fibre in telecommunication networks, any of the physical properties of light can be modulated. Light has a frequency, intensity, polarization and a phase. Until recently, optical communication systems strictly employed conventional intensity (IM) modulation signals in either non return-to-zero (NRZ) or return-to-zero (RZ) format. But a number of advanced optical modulation formats have attracted increasing attention in the last few years. One prime example is the phase-shift-keyed (PSK) family of formats which carry the information on the optical phase. Since absolute phase is not easily detected through coherent demodulation, differential encoding in which the phase of the preceding bit is used as a relative phase reference for demodulation has become a method of choice for phase modulated signals. The result in the differential-phase-shift-keyed (DPSK) formats, which carry the information in the difference in optical phase between successive bits. In this thesis by article, composed of six papers, we investigate the generation, transmission and demodulation of DPSK in optical fibre transmission systems. We propose a novel way to encode optical packets using DPSK in our investigation of the generation. We also investigate transmission effects monitoring using a novel partial-bit delay interferometer-assisted clock tone monitoring method for sensitive optical-signal-to-noise ratio (OSNR), chromatic dispersion and polarization mode dispersion monitoring. Then we look at the demodulation of DPSK, first investigating the reduced tolerances and power penalties of DPSK demodulation when more than one bit delay is used in the interferometer. We also propose an optical error correction method combining DPSK optical logic gates with electronic logic gates to improve receiver sensitivity and transmission impairment tolerances. Finally we redefine the previously

  11. Measurement of Three-Dimensional Deformations by Phase-Shifting Digital Holographic Interferometry

    Percival Almoro


    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.

  12. New measurements and phase shift analysis of p16O elastic scattering at astrophysical energies

    Dubovichenko, Sergey; Burtebayev, Nassurlla; Dzhazairov-Kakhramanov, Albert; Zazulin, Denis; Kerimkulov, Zhambul; Nassurlla, Marzhan; Omarov, Chingis; Tkachenko, Alesya; Shmygaleva, Tatyana; Kliczewski, Stanislaw; Sadykov, Turlan


    The results of new experimental measurements of p16O elastic scattering in the energy range of 0.6-1.0 MeV at angles of 40°-160° are given. Phase shift analysis of p16O elastic scattering was made using these and other experimental data on differential cross sections in excitation functions and angular distributions at energies of up to 2.5 MeV. Supported by the Ministry of Education and Science of the Republic of Kazakhstan (0073/PCF-IS-MES)

  13. Frequency-dependent polarization-angle-phase-shift in the microwave-induced magnetoresistance oscillations

    Liu, Han-Chun; Ye, Tianyu; Mani, R. G. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Wegscheider, W. [Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich (Switzerland)


    Linear polarization angle, θ, dependent measurements of the microwave radiation-induced oscillatory magnetoresistance, R{sub xx}, in high mobility GaAs/AlGaAs 2D electron devices have shown a θ dependence in the oscillatory amplitude along with magnetic field, frequency, and extrema-dependent phase shifts, θ{sub 0}. Here, we suggest a microwave frequency dependence of θ{sub 0}(f) using an analysis that averages over other smaller contributions, when those contributions are smaller than estimates of the experimental uncertainty.

  14. A full-duplex radio-over-fiber system with differential phase-shift keying signals

    He Jing; Yang Dong; Chen Lin, E-mail: [School of Computer and Communication, Hunan University, Changsha 410082 (China)


    We propose a full-duplex radio-over-fiber (ROF) system transmitting 2.5 Gb/s differential phase-shift keying (DPSK) signals with 40GHz optical millimeter-wave as downlink. Meanwhile it can be reused central wavelength as uplink connection for transmitting 2.5 Gb/s on-off keying (OOK) signals. The experimental and simulation results show that the downstream 2.5Gb/s DPSK data and the upstream 2.5Gb/s OOK data can transmit 40km single-mode fiber successfully.

  15. Universal gates based on targeted phase shifts in a 3D neutral atom array

    Kumar, Aishwarya; Wang, Yang; Wu, Tsung-Yao; Weiss, David


    We demonstrate a new approach to making targeted single qubit gates using Cesium atoms in a 5x5x5 3D neutral atom array. It combines targeted AC Zeeman phase shifts with global microwave pulses to produce arbitrary single qubit gates. Non-targeted atoms are left virtually untouched by the gates. We have addressed 48 sites, targeted individually, in a 40% full array. We have also performed Randomized Benchmarking to characterize the fidelity and crosstalk errors of this gate. These gates are highly insensitive to addressing beam imperfections and can be applied to other systems and geometries. Supported by NSF.

  16. Simultaneous all-optical AND and NOR gates for NRZ differential phase-shift-keying signals

    Xu, Jing; Zhang, X.; Dong, J.


    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....

  17. The Sagnac Phase Shift Suggested by the Aharonov-Bohm Effect for Relativistic Matter Beams

    Rizzi, Guido; Ruggiero, Matteo Luca


    The phase shift due to the Sagnac Effect, for relativistic matter beams counter-propagating in a rotating interferometer, is deduced on the bases of a formal analogy with the Aharonov-Bohm effect. A procedure outlined by Sakurai, in which non relativistic quantum mechanics and Newtonian physics appear together with some intrinsically relativistic elements, is generalized to a fully relativistic context, using the Cattaneo's splitting technique. This approach leads to an exact derivation, in a self-consistently relativistic way, of the Sagnac effect. Sakurai's result is recovered in the first order approximation.

  18. The Sagnac Phase Shift suggested by the Aharonov-Bohm effect for relativistic matter beams

    Rizzi, G; Rizzi, Guido; Ruggiero, Matteo Luca


    The phase shift due to the Sagnac Effect, for relativistic matter beams counter-propagating in a rotating interferometer, is deduced on the bases of a a formal analogy with the the Aharonov-Bohm effect. A procedure outlined by Sakurai, in which non relativistic quantum mechanics and newtonian physics appear together with some intrinsically relativistic elements, is generalized to a fully relativistic context, using the Cattaneo's splitting technique. This approach leads to an exact derivation, in a self-consistently relativistic way, of the Sagnac effect. Sakurai's result is recovered in the first order approximation.

  19. Trustworthiness of measurement devices in round-robin differential-phase-shift quantum key distribution

    Cao, Zhu; Yin, Zhen-Qiang; Han, Zheng-Fu


    Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) has been proposed to raise the noise tolerability of the channel. However, in practice, the measurement device in RRDPS QKD may be imperfect. Here, we show that, with these imperfections, the security of RRDPS may be damaged by proposing two attacks for RRDPS systems with uncharacterized measurement devices. One is valid even for a system with unit total efficiency, while the other is valid even when a single-photon state is sent. To prevent these attacks, either security arguments need to be fundamentally revised or further practical assumptions on the measurement device should be put.

  20. Phase shift experiments identifying Kramers doublets in a chaotic superconducting microwave billiard of threefold symmetry

    Dembowski, C.; Dietz, B.; Graef, H.D.; Heine, A.; Leyvraz, F.; Miski-Oglu, M.; Richter, A.; Seligman, T.H.


    The spectral properties of a two-dimensional microwave billiard showing threefold symmetry have been studied with a new experimental technique. This method is based on the behavior of the eigenmodes under variation of a phase shift between two input channels, which strongly depends on the symmetries of the eigenfunctions. Thereby a complete set of 108 Kramers doublets has been identified by a simple and purely experimental method. This set clearly shows Gaussian unitary ensemble statistics, although the system is time-reversal invariant. (orig.)

  1. Null test fourier domain alignment technique for phase-shifting point diffraction interferometer

    Naulleau, Patrick; Goldberg, Kenneth Alan


    Alignment technique for calibrating a phase-shifting point diffraction interferometer involves three independent steps where the first two steps independently align the image points and pinholes in rotation and separation to a fixed reference coordinate system, e.g, CCD. Once the two sub-elements have been properly aligned to the reference in two parameters (separation and orientation), the third step is to align the two sub-element coordinate systems to each other in the two remaining parameters (x,y) using standard methods of locating the pinholes relative to some easy to find reference point.

  2. Anomalies of the Schwinger phase shifts in the static exchange approximation

    Apagyi, B.; Levay, P.; Ladanyi, K.


    The Schwinger variational method is applied to the static exchange approximation of the electron--hydrogen-atom scattering. Spurious singularities are encountered in singlet scattering processes. The position of the poles is investigated by a simple numerical procedure. Anomalous poles appear in narrow regions of the nonlinear scale parameter. Results are presented which illustrate the behavior of the phase shifts around the spurious poles. No Kohn-type anomalies are encountered in the triplet case. As a byproduct, it is discussed that the Schwinger formula may be approximated in a separable form which is relatively simple but not free of anomalies.

  3. Performance Comparison of Phase Shifted PWM and Sorting Method for Modular Multilevel Converters

    Haddioui, Marcos Rejas; Máthé, Lászlo; Burlacu, Paul Dan;


    Modular Multilevel Converters (MMC) are the solution of preference in HVDC applications due to modularity, scalability, low losses and low filtering requirement. Carrier-based (PWM) and carrier-less (nearest level control) modulation can be applied. By using advanced sorting methods focusing...... 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...

  4. High-speed deformation measurement using spatially phase-shifted speckle interferometry

    Beckmann, Tobias; Fratz, Markus; Bertz, Alexander; Carl, Daniel


    Electronic speckle pattern interferometry (ESPI) is a powerful technique for differential shape measurement with submicron resolution. Using spatial phase-shifting (SPS), no moving parts are required, allowing frame acquisition rates limited by camera hardware. We present ESPI images of 1 megapixel resolution at 500 fps. Analysis of SPS data involves complex, time-consuming calculations. The graphics processing units found in state-of-the-art personal computers have exceptional parallel processing capabilities, allowing real-time SPS measurements at video frame rates. Deformation analysis at this frame rate can be used to analyze transient phenomena such as transient temperature effects in integrated circuit chips or during material processing.

  5. A simple coherent attack and practical security of differential phase shift quantum cryptography

    Kronberg, D. A.


    The differential phase shift quantum key distribution protocol reveals good security against such powerful attacks as unambiguous state discrimination and beam splitting attacks. Its complete security analysis is complex due to high dimensions of the supposed spaces and density operators. In this paper, we consider a particular and conceptually simple coherent attack, available in practical implementations. The main condition for this attack is the length of used coherent state tuples of order 8-12. We show that under this condition, no high level of practical distance between legitimate users can be achieved.

  6. Refractometric sensor based on a phase-shifted long-period fiber grating.

    Falate, Rosane; Frazão, Orlando; Rego, Gaspar; Fabris, José Luís; Santos, José Luís


    A refractometric sensor based on a phase-shifted long-period fiber grating written by electric-arc discharges is presented. Transmission and reflective configurations for refractive index measurements are studied. It is observed that the reflective topology permits better performance compared with the transmission one, which is the approach normally utilized in the context of long-period fiber sensing. The resolution achieved in the measurement of refractive index enables the application of this sensing head structure in demanding situations, such as the measurement of the level of salinity of water.

  7. Distributed cavity phase frequency shifts of the caesium fountain PTB-CSF2

    Weyers, S; Nemitz, N; Li, R; Gibble, K


    We evaluate the frequency error from distributed cavity phase in the caesium fountain clock PTB-CSF2 at the Physikalisch-Technische Bundesanstalt with a combination of frequency measurements and ab initio calculations. The associated uncertainty is 1.3E-16, with a frequency bias of 0.4E-16. The agreement between the measurements and calculations explains the previously observed frequency shifts at elevated microwave amplitude. We also evaluate the frequency bias and uncertainty due to the microwave lensing of the atomic wavepackets. We report a total PTB-CSF2 systematic uncertainty of 4.1E-16.

  8. Experimental comparison of phase-shifting fringe projection and statistical pattern projection for active triangulation systems

    Lutzke, Peter; Schaffer, Martin; Kühmstedt, Peter; Kowarschik, Richard; Notni, Gunther


    Active triangulation systems are widely used for precise and fast measurements. Many different coding strategies have been invented to solve the correspondence problem. The quality of the measurement results depends on the accuracy of the pixel assignments. The most established method uses phase shifted-patterns projected on the scene. This is compared to a method using statistical patterns. In both coding strategies, the number and the spatial frequency of the projected patterns is varied. The measurements and calculations for all presented results were done with exactly the same measurement setup in a narrow time window to avoid any changes and to guarantee identical technical preconditions as well as comparability.

  9. Evaluation of fatigue process zone dimensions in notched specimens by two-step phase shifting interferometry technique

    Muravsky, Leonid I.; Picart, Pascal; Kmet', Arkady B.; Voronyak, Taras I.; Ostash, Orest P.; Stasyshyn, Ihor V.


    A method for evaluation of fatigue process zone (FPZ) dimensions near a notch root in metal and alloy specimens by using a two-step phase shifting interferometry (TS PSI) technique is proposed. In comparison with other destructive and nondestructive methods evaluating the FPZ dimensions, it possesses higher accuracy and performance. The method uses a criterion for the FPZ dimensions definition based on an assumption that the surface roughness of notched specimens after cyclic loading reaches its maximum values at the FPZ boundary. To realize this method, first, a phase map (PM) of a total surface relief near a notch root is retrieved; second, roughness and waviness PMs are extracted from the retrieved total surface relief PM by using the TS PSI; and finally, a surface roughness parameter Ra spatial distribution is calculated according to the offered criterion and the FPZ size d* is defined. The FPZ size was measured for specimens made of low-carbon steel and aluminum alloys 2024-T6 and 7075-T3. Obtained experimental results have shown that the proposed criterion allows defining the FPZ size for notched specimens made of metals and alloys possessing high, moderate, and low plasticity.

  10. Improved Reliability of Single-Phase PV Inverters by Limiting the Maximum Feed-in Power

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede


    . The CPG control strategy is activated only when the DC input power from PV panels exceeds a specific power limit. It enables to limit the maximum feed-in power to the electric grids and also to improve the utilization of PV inverters. As a further study, this paper investigates the reliability performance...... of the power devices (e.g. IGBTs) used in PV inverters with the CPG control under different feed-in power limits. A long-term mission profile (i.e. solar irradiance and ambient temperature) based stress analysis approach is extended and applied to obtain the yearly electrical and thermal stresses of the power...

  11. Sensitivity Distribution Properties of a Phase-Shifted Fiber Bragg Grating Sensor to Ultrasonic Waves

    Qi Wu


    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.

  12. Sensitivity distribution properties of a phase-shifted fiber bragg grating sensor to ultrasonic waves.

    Wu, Qi; Okabe, Yoji; Saito, Kazuya; Yu, Fengming


    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.

  13. A novel NOLM structure with nonreciprocal phase shift bias for power fluctuation reduction of pulse trains

    Liwei Guo; Xue Feng; Yue Liu; Xiaoming Liu


    @@ A novel nonlinear optical loop mirror (NOLM) with a nonreciprocal phase shift bias (NPSB), called power equalization NOLM (PE-NOLM), is proposed for reducing the power fluctuation of pulse trains. NPSB provides part of the nonreciprocal phase difference so that the required input power is reduced, and nonsymmetrical coupling ratio of coupler can adjust the transmission curve to improve the equalization range. It has been shown theoretically that compared with earlier PE-NOLM, about 1.6 dB of equalization power reduction and about 2.2 dB of equalization range enhancement could be achieved. Experiments have demonstrated that the output power fluctuation is reduced to less than 0.4 dB, while the required input peak power range is 4.5 dBm (15.6-20.1 dBm).

  14. Phase behavior under a non-centrosymmetric interaction: shifted charge colloids investigated by Monte Carlo simulation

    Sánchez-Díaz, Luis E; Li, Xin; Wu, Bin; Smith, Gregory S; Chen, Wei-Ren


    Using Monte Carlo simulations, we investigate the structural characteristics of an interacting hard sphere system with shifted charge to elucidate the effect of the non-centrosymmetric interaction on its phase behavior. Two different phase transitions are identified for this model system. Upon increasing the volume fraction, an abrupt liquid-to-crystal transition first occurs at a significantly lower volume fraction in comparison to that of the centro-charged system. This is due to the stronger effective inter-particle repulsion caused by the additional charge anisotropy. Moreover, within the crystal state at higher volume fraction, the system further undergoes a continuous disorder-to-order transition with respect to the charge orientation. Detailed analyses in this work disclose the nature of these transitions, and orientation fluctuation may cause non-centrosymmetric unit cells. The dependence of crystal formation and orientational ordering on temperature was also examined. These findings indicate that the...

  15. Visualizing the phenomena of wave interference, phase-shifting and polarization by interactive computer simulations

    Rivera-Ortega, Uriel; Dirckx, Joris


    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.

  16. Observation of SN2011fe with INTEGRAL. I. Pre--maximum phase

    Isern, J; Bravo, E; Diehl, R; Knödlseder, J; Domingo, A; Hirschmann, A; Hoeflich, P; Lebrun, F; Renaud, M; Soldi, S; Elias-Rosa, N; Hernanz, M; Kulebi, B; Zhang, X; Badenes, C; Domínguez, I; Garcia-Senz, D; Jordi, C; Lichti, G; Vedrenne, G; Von Ballmoos, P


    SN2011fe was detected by the Palomar Transient Factory on August 24th 2011 in M101 a few hours after the explosion. From the early optical spectra it was immediately realized that it was a Type Ia supernova thus making this event the brightest one discovered in the last twenty years. The distance of the event offered the rare opportunity to perform a detailed observation with the instruments on board of INTEGRAL to detect the gamma-ray emission expected from the decay chains of $^{56}$Ni. The observations were performed in two runs, one before and around the optical maximum, aimed to detect the early emission from the decay of $^{56}$Ni and another after this maximum aimed to detect the emission of $^{56}$Co. The observations performed with the instruments on board of INTEGRAL (SPI, IBIS/ISGRI, JEMX and OMC) have been analyzed and compared with the existing models of gamma-ray emission from such kind of supernovae. In this paper, the analysis of the gamma-ray emission has been restricted to the first epoch. B...

  17. Laser Trimming for Adjustment of Grating Offset in Phase-Shifted Fiber Grating Coupler for All-Optical Switching Application

    Hirohisa; Yokota; Yutaka; Sasaki


    We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.

  18. Common-mode noise analysis, modeling and filter design for a phase-shifted full-bridge forward converter

    Makda, Ishtiyaq Ahmed; Nymand, Morten


    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....

  19. Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology

    Vasa Radonić


    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.

  20. Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology.

    Radonić, Vasa; Birgermajer, Slobodan; Kitić, Goran


    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.

  1. A method to measure the movement of a rough plane ultrasonically by Doppler - phase shift

    Kortelainen, Juha

    The Doppler effect has been used to measure the horizontal movement of a rough plane. The operational principle is based on the measurement of the phase shift of an ultrasonic wave scattered from the surface. This method has been developed for measuring the length of logs in a forest machine. Equations for the Doppler phase shift have been derived for the situation where the moving object is a single particle. Later this 'one-particle-theory' has been expanded for the situation where the moving object is a rough plane. The theory uses some simplifications and assumptions from the reality, but the results still agree well with measurements. This method has been tested by moving logs with a velocity varying from 0 to 1 m/s. The variability of measurement with different kind of logs was about 0.3 ... 2% when the movement was about one meter. The analysis of the errors and ideas to compensate them are presented in the paper.

  2. Ultrasonic array imaging of multilayer structures using full matrix capture and extended phase shift migration

    Wu, Haiteng; Chen, Jian; Yang, Keji; Hu, Xuxiao


    Multilayer structures have been widely used in industrial fields, and non-destructive evaluation of these structures is of great importance to assure their quality and performance. Recently, ultrasonic array imaging using full matrix capture, e.g. the total focusing method (TFM), has been shown to increase sensitivity to small defects and improve imaging resolution in homogeneous media. However, it cannot be applied to multilayer structures directly, due to the sound velocity variation in different layers and because refraction occurs at layer interfaces, which gives rise to difficulties in determining the propagation path and time. To overcome these problems, an extended phase shift migration (EPSM) is proposed for the full matrix imaging of multilayer structures in this paper. Based on the theory of phase shift migration for monostatic pulse-echo imaging, full matrix imaging using EPSM is derived by extrapolating the wavefields in both transmission and reception, and extended to the multilayer case. The performance of the proposed algorithm is evaluated by full matrix imaging of a two-layer structure with side-drilled holes conducted both in the simulation and the experiment. The results verify that the proposed algorithm is capable of full matrix imaging of a layered structure with a high resolution and signal-to-noise ratio. For comparison, full matrix imaging using the TFM with root-mean-squared velocity is also performed, and the results demonstrate that the proposed algorithm is superior to the TFM in improving both the image quality and resolution.

  3. Phase-Shift Analysis of Low-Energy $\\pi^{+}p$ Data

    Gashi, A; Oades, G C; Rasche, G; Woolcock, W S


    This work presents the results of a revised analysis of the low-energy (pion laboratory kinetic energy T(sub pi) < 100 MeV) pi+ p data using recently obtained electromagnetic corrections. The measurements are analyzed assuming extended threshold expansions for the hadronic K-matrix elements. With a few exceptions, the description of the experimental data is satisfactory. Several minimization functions have been used, yielding consistent results. The phase-shift values, obtained in the s and p(3/2) partial waves, disagree with those of the most recent VPI global-fit solution (SP98); the largest part of this disagreement is removed if we compare our numbers to their single-energy solutions. The s-wave scattering length a(sub 0+), the p-wave scattering volumes a(sub 1+) and a(sub 1-), as well as the hadronic phase shifts themselves, obtained herein, are in agreement with recent work using older electromagnetic corrections; the output of the present work (including meaningful uncertainties) is tabulated in ord...

  4. 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


    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.

  5. Development of an i-line attenuated phase shift process for dual inlay interconnect lithography

    Sturtevant, John L.; Ho, Benjamin C. P.; Geiszler, Vincent C.; Herrick, Matthew T.; King, Charles F.; Carter, Russell L.; Roman, Bernard J.; Litt, Lloyd C.; Smith, Brad; Strozewski, Kirk J.


    The transition from aluminum/oxide to copper/low-k dielectric interconnect technology involves a variety of fundamental changes in the back-end manufacturing process. The most attractive patterning strategy involves the use of a so-called dual inlay approach, which offers lower fabrication costs by the elimination of one inter-level dielectric (ILD) deposition and polish sequence per metal layer. In this paper, the lithographic challenges for dual inlay, including thin-film interference effect, resist bulk effect, and optical proximity effects are reviewed. The use of attenuated phase shift (aPSM) reticles for patterning vias and trenches was investigated, and shown to provide adequate process margin by optimizing the photoresist and exposure tool parameters. Our results indicate that using appropriately sized attenuated phase shift technique increases the photospeed considerably and simultaneously improves the common process window with sufficient sidelobe suppression margin. The cost of ownership tradeoffs between an attenuated PSM I-Line process and a DUV binary process are discussed.

  6. Phase-shifted fiber Bragg grating inscription by fusion splicing technique and femtosecond laser

    Jiang, Yajun; Yuan, Yuan; Xu, Jian; Yang, Dexing; Li, Dong; Wang, Meirong; Zhao, Jianlin


    A new method for phase-shifted fiber Bragg grating (PS-FBG) inscription in single mode fiber by fusion splicing technique and femtosecond laser is presented. The PS-FBG is produced by exposing the fusion spliced fiber with femtosecond laser through a uniform phase mask. The transmission spectrum of the PS-FBG shows a nonlinear red shift during the inscription process, and two or three main dips can be observed due to the formation of one or two FBG-based Fabry-Pérot structures by controlling the exposure intensity and time of the laser. For a peak power density of 4.8×1013 W/cm2, the induced refractive index modulation can reach to 6.3×10-4 in the fiber without sensitization. The PS-FBG's temperature, strain and pressure characteristics are also experimentally studied. These PS-FBGs can be potentially used for multiple wavelength fiber lasers, filters and optical fiber sensors.

  7. Ultrahigh-frequency microwave phase shifts mediated by ultrafast dynamics in quantum-dot semiconductor optical amplifiers

    Chen, Yaohui; Mørk, Jesper


    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....

  8. Analysis of an effective optical filtering technique to enhance microwave phase shifts based on slow and fast light effects

    Chen, Yaohui; Öhman, Filip; Xue, Weiqi


    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....

  9. 3D surface real-time measurement using phase-shifted interference fringe technique for craniofacial identification

    Levin, Gennady G.; Vishnyakov, Gennady N.; Naumov, Alexey V.; Abramov, Sergey


    We offer to use the 3D surface profile real-time measurement using phase-shifted interference fringe projection technique for the cranioficial identification. Our system realizes the profile measurement by projecting interference fringe pattern on the object surface and by observing the deformed fringe pattern at the direction different from the projection. Fringes are formed by a Michelson interferometer with one mirror mounted on a piezoelectric translator. Four steps self- calibration phase-shift method was used.

  10. Liouville's Theorem from the Principle of Maximum Caliber in Phase Space

    González, Diego


    One of the cornerstones in non--equilibrium statistical mechanics (NESM) is Liouville's theorem, a differential equation for the phase space probability $\\rho(q,p; t)$. This is usually derived considering the flow in or out of a given surface for a physical system (composed of atoms), via more or less heuristic arguments. In this work, we derive the Liouville equation as the partial differential equation governing the dynamics of the time-dependent probability $\\rho(q, p; t)$ of finding a "particle" with Lagrangian $L(q, \\dot{q}; t)$ in a specific point $(q, p)$ in phase space at time $t$, with $p=\\partial L/\\partial \\dot{q}$. This derivation depends only on considerations of inference over a space of continuous paths. Because of its generality, our result is valid not only for "physical" systems but for any model depending on constrained information about position and velocity, such as time series.

  11. Optimization of Key Parameters in 622-Mb/s Amplitude Shift Keying Labeled 40-Gb/s Return to Zero Differential Phase Shift Keying Optical Switching Network

    ZHAO Jun-yan; XIN Xiang-jun; YU Chong-xiu; XU Da-xiong


    Optimized are the label extinction ratio and dispersion compensation of an optical label switching transmission system, which employs 40-Gb/s return to zero differential phase shift keying(RZ-DPSK) payload labeled with 622-Mb/s amplitude shift keying(ASK) control data. In our scheme, the receiver sensitivities of payload and label achieves -27.8 dBm and -33.5 dBm, respectively. After transmitted over 40 km, 60 km and 80 km single mode fiber(SMF)(with dispersion compensation) respectively, the payload can be recovered with no power penalty, while the label can be recovered with less than 2 dB penalty.

  12. Is Echinometra viridis facilitating a phase shift on an Acropora cervicornis patch reef in Belize?

    Stefanic, C. M.; Greer, L.; Norvell, D.; Benson, W.; Curran, H.


    Coral reef health is in rapid decline across the Caribbean due to a number of anthropogenic and natural disturbances. A phase shift from coral- to macroalgae-dominant reefs is pervasive and has been well documented. Acropora cervicornis (Staghorn Coral) has been particularly affected by this shift due to mass mortality of this species since the 1980s. In recent years few Caribbean A. cervicornis refugia have been documented. This study characterizes the relationship between coral and grazing urchins on a rare patch reef system dominated by A. cervicornis off the coast of Belize. To assess relative abundance of live A. cervicornis and the urchin Echinometra viridis, photographs and urchin abundance data were collected from 132 meter square quadrats along five transects across the reef. Photographs were digitized and manually segmented using Adobe Illustrator, and percent live coral cover and branch tip densities were calculated using Matlab. Mean percent live coral cover across all transects was 24.4 % with a high of 65% live coral per meter square. Average urchin density was 18.5 per quadrat, with an average density per transect ranging from 22.1 to 0.5 per quadrat. Up to over 400 live A. cervicornis branch tips per quadrat were observed. Data show a positive correlation between E. viridis abundance and live A. cervicornis, suggesting that these urchins are facilitating recovery or persistence of this endangered coral species. These results suggest the relationship between E. viridis and A. cervicornis could be a key element in a future reversal of the coral to macroalgae phase shift on some Caribbean coral reefs.

  13. Lateral shifting sensitivity of a ground glass for holographic encryption and multiplexing using phase conjugate readout algorithm

    Sun, Ching-Cherng; Su, Wei-Chia; Wang, Bor; Chiou, Arthur E. T.


    An encryption-selectable holographic storage algorithm with use of random phase encoding and angular multiplexing is proposed and demonstrated. The pattern for storage can be encrypted and multiplexed with use of a ground glass, which is also used to decrypt the pattern. A phase conjugation of the reference beam is used to generate phase conjugate waves of the stored patterns. The lateral shifting sensitivity of the ground glass used to decrypt the information is theoretically analyzed and is compared with experimental measurement. The shifting tolerance for various ground glasses under imperfection phase reconstruction in the decryption processing is studied.

  14. Relative phase noise induced impairment in M-ary phase-shift-keying coherent optical communication system using distributed fiber Raman amplifier.

    Cheng, Jingchi; Tang, Ming; Fu, Songnian; Shum, Perry Ping; Liu, Deming


    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.

  15. PDF neuron firing phase-shifts key circadian activity neurons in Drosophila.

    Guo, Fang; Cerullo, Isadora; Chen, Xiao; Rosbash, Michael


    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.

  16. PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

    Guo, Fang; Cerullo, Isadora; Chen, Xiao; Rosbash, Michael


    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. DOI: PMID:24939987

  17. Telecentric 3D profilometry based on phase-shifting fringe projection.

    Li, Dong; Liu, Chunyang; Tian, Jindong


    Three dimensional shape measurement in the microscopic range becomes increasingly important with the development of micro manufacturing technology. Microscopic fringe projection techniques offer a fast, robust, and full-field measurement for field sizes from approximately 1 mm2 to several cm2. However, the depth of field is very small due to the imaging of non-telecentric microscope, which is often not sufficient to measure the complete depth of a 3D-object. And the calibration of phase-to-depth conversion is complicated which need a precision translation stage and a reference plane. In this paper, we propose a novel telecentric phase-shifting projected fringe profilometry for small and thick objects. Telecentric imaging extends the depth of field approximately to millimeter order, which is much larger than that of microscopy. To avoid the complicated phase-to-depth conversion in microscopic fringe projection, we develop a new system calibration method of camera and projector based on telecentric imaging model. Based on these, a 3D reconstruction of telecentric imaging is presented with stereovision aided by fringe phase maps. Experiments demonstrated the feasibility and high measurement accuracy of the proposed system for thick object.

  18. Dual-polarization phase shift processing with the Python ARM Radar Toolkit

    Collis, S. M.; Lang, T. J.; Mühlbauer, K.; Helmus, J.; North, K.


    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:[2] Timothy J. Lang, David A. Ahijevych, Stephen W. Nesbitt, Richard E. Carbone, Steven A. Rutledge, and Robert Cifelli, 2007: Radar

  19. A Single Phase Doubly Grounded Semi-Z-Source Inverter for Photovoltaic (PV Systems with Maximum Power Point Tracking (MPPT

    Tofael Ahmed


    Full Text Available In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT is proposed for photovoltaic (PV systems. This proposed system utilizes a single-ended primary inductor (SEPIC converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximum power point (MPP and the semi-Z-source inverter utilizes a nonlinear SPWM to produce sinusoidal voltage at the output. The proposed system is able to track the MPP of PV arrays and produce an AC voltage at its output by utilizing only three switches. Experimental results show that the fast-converging MPPT algorithm has fast tracking response with appreciable MPP efficiency. In addition, the inverter shows the minimization of common mode leakage current with its ground sharing feature and reduction of the THD as well as DC current components at the output during DC-AC conversion.

  20. Small-Signal Analysis of Single-Phase and Three-phase DC/AC and AC/DC PWM Converters with the Frequency-Shift Technique

    Blaabjerg, Frede; Aquila, A. Dell’; Liserre, Marco;


    A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...... of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters...

  1. Borrelia burgdorferi requires glycerol for maximum fitness during the tick phase of the enzootic cycle.

    Christopher J Pappas


    Full Text Available Borrelia burgdorferi, the spirochetal agent of Lyme disease, is a vector-borne pathogen that cycles between a mammalian host and tick vector. This complex life cycle requires that the spirochete modulate its gene expression program to facilitate growth and maintenance in these diverse milieus. B. burgdorferi contains an operon that is predicted to encode proteins that would mediate the uptake and conversion of glycerol to dihydroxyacetone phosphate. Previous studies indicated that expression of the operon is elevated at 23°C and is repressed in the presence of the alternative sigma factor RpoS, suggesting that glycerol utilization may play an important role during the tick phase. This possibility was further explored in the current study by expression analysis and mutagenesis of glpD, a gene predicted to encode glycerol 3-phosphate dehydrogenase. Transcript levels for glpD were significantly lower in mouse joints relative to their levels in ticks. Expression of GlpD protein was repressed in an RpoS-dependent manner during growth of spirochetes within dialysis membrane chambers implanted in rat peritoneal cavities. In medium supplemented with glycerol as the principal carbohydrate, wild-type B. burgdorferi grew to a significantly higher cell density than glpD mutant spirochetes during growth in vitro at 25°C. glpD mutant spirochetes were fully infectious in mice by either needle or tick inoculation. In contrast, glpD mutants grew to significantly lower densities than wild-type B. burgdorferi in nymphal ticks and displayed a replication defect in feeding nymphs. The findings suggest that B. burgdorferi undergoes a switch in carbohydrate utilization during the mammal to tick transition. Further, the results demonstrate that the ability to utilize glycerol as a carbohydrate source for glycolysis during the tick phase of the infectious cycle is critical for maximal B. burgdorferi fitness.

  2. Shifting distributions of adult Atlantic sturgeon amidst post-industrialization and future impacts in the Delaware River: a maximum entropy approach.

    Breece, Matthew W; Oliver, Matthew J; Cimino, Megan A; Fox, Dewayne A


    Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) experienced severe declines due to habitat destruction and overfishing beginning in the late 19(th) century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt) approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19(th) century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960's. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species.

  3. Shifting distributions of adult Atlantic sturgeon amidst post-industrialization and future impacts in the Delaware River: a maximum entropy approach.

    Matthew W Breece

    Full Text Available Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus experienced severe declines due to habitat destruction and overfishing beginning in the late 19(th century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19(th century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960's. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species.

  4. Combined passive acoustic mapping and magnetic resonance thermometry for monitoring phase-shift nanoemulsion enhanced focused ultrasound therapy

    Crake, Calum; Meral, F. Can; Burgess, Mark T.; Papademetriou, Iason T.; McDannold, Nathan J.; Porter, Tyrone M.


    Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure. Here, we employed phase-shift nanoemulsions (PSNE) embedded in tissue phantoms to promote cavitation and hence temperature rise induced by FUS. In addition, we incorporated passive acoustic mapping (PAM) alongside simultaneous MR thermometry in order to visualize both acoustic emissions and temperature rise, within the bore of a full scale clinical MRI scanner. Focal cavitation of PSNE could be resolved using PAM and resulted in accelerated heating and increased the maximum elevated temperature measured via MR thermometry compared to experiments without nanoemulsions. Over time, the simultaneously acquired acoustic and temperature maps show translation of the focus of activity towards the FUS transducer, and the magnitude of the increase in cavitation and focal shift both increased with nanoemulsion concentration. PAM results were well correlated with MRI thermometry and demonstrated greater sensitivity, with the ability to detect cavitation before enhanced heating was observed. The results suggest that PSNE could be beneficial for enhancement of thermal focused ultrasound therapies and that PAM could be a critical tool for monitoring this process.

  5. Comparative analysis of autofocus functions in digital in-line phase-shifting holography.

    Fonseca, Elsa S R; Fiadeiro, Paulo T; Pereira, Manuela; Pinheiro, António


    Numerical reconstruction of digital holograms relies on a precise knowledge of the original object position. However, there are a number of relevant applications where this parameter is not known in advance and an efficient autofocusing method is required. This paper addresses the problem of finding optimal focusing methods for use in reconstruction of digital holograms of macroscopic amplitude and phase objects, using digital in-line phase-shifting holography in transmission mode. Fifteen autofocus measures, including spatial-, spectral-, and sparsity-based methods, were evaluated for both synthetic and experimental holograms. The Fresnel transform and the angular spectrum reconstruction methods were compared. Evaluation criteria included unimodality, accuracy, resolution, and computational cost. Autofocusing under angular spectrum propagation tends to perform better with respect to accuracy and unimodality criteria. Phase objects are, generally, more difficult to focus than amplitude objects. The normalized variance, the standard correlation, and the Tenenbaum gradient are the most reliable spatial-based metrics, combining computational efficiency with good accuracy and resolution. A good trade-off between focus performance and computational cost was found for the Fresnelet sparsity method.

  6. Study on BSTO/MgO Ferroelectric Materials for Phase Shift Doped with Rare Earth Oxides

    Yang Chunxia; Zhou Hongqing; Liu Min; Wu Hongzhong


    Barium strontium titanate/magnesia (BSTO/MgO) ferroelectric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5% on dielectric behaviors of BSTO/MgO composites were studied in terms of permittivity, loss tangent and tunability both at low and high frequencies. The dielectric constant of Y2O3 and Er2O3 doped samples decreases from 160 to 120, and the microwave loss of La2O3 and Er2O3 doped samples decreases from 8.2×10-3 to 6.8×10-3. Only La2O3 increases the tunability of BSTO/MgO system, from 13.6% to 14.8%. For the La2O3 doped sample, the value of tunability is more than 14% with the external DC field 4000 V*mm-1 and the microwave loss at 2.47 GHz is 6.77×10-3 and, hence, it can basically meet the requirements of phase shifters working at microwave frequencies. The influence mechanism was discussed preliminarily.

  7. Analytical predictions for vibration phase shifts along fluid-conveying pipes due to Coriolis forces and imperfections

    Thomsen, Jon Juel; Dahl, Jonas


    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...

  8. Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift.

    Ling, S D; Johnson, C R; Frusher, S D; Ridgway, K R


    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.

  9. Angular phase shift in polarization-angle dependence of microwave-induced magnetoresistance oscillations

    Liu, Han-Chun; Samaraweera, Rasanga L.; Mani, R. G.; Reichl, C.; Wegscheider, W.


    We examine the microwave frequency (f ) variation of the angular phase shift, θ0, observed in the polarization-angle dependence of microwave-induced magnetoresistance oscillations in a high-mobility GaAs/AlGaAs two-dimensional electron system. By fitting the diagonal resistance Rx x versus θ plots to an empirical cosine square law, we extract θ0 and trace its quasicontinuous variation with f . The results suggest that the overall average of θ0 extracted from Hall bar device sections with length-to-width ratios of L /W =1 and 2 is the same. We compare the observations with expectations arising from the "ponderomotive force" theory for microwave radiation-induced transport phenomena.

  10. Monitoring the thinning dynamics of soap films by phase shift interferometry. The case of perfluoropolyether surfactants.

    Gambi, Cecilia M C; Vannoni, Maurizio; Sordini, Andrea; Molesini, Giuseppe


    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.

  11. Comparative study of bi-layer attenuating phase-shifting masks for hyper-NA lithography

    Yoshizawa, Masaki; Philipsen, Vicky; Leunissen, Leonardus H. A.; Hendrickx, Eric; Jonckheere, Rik; Vandenberghe, Geert; Buttgereit, Ute; Becker, Hans; Koepernik, Corinna; Irmscher, Mathias


    Most IC manufacturers are considering MoSi to be the material of conventional 6% attenuating phase-shifting masks (attPSM) in hyper-NA lithography (50 nm half pitch node and smaller). However, simulation results show that Cr-based binary-intensity mask (BIM) outperforms the attPSM at dense lines and spaces (LS) patterns in hyper-NA lithography. A reason lies in the transmitted polarization state through the mask. The attPSM is found to be a transverse-magnetic polarizer for hyper-NA imaging, while the BIM acts as a transverse-electric polarizer, which is beneficial for imaging. Using a metal-based absorber of the attPSM has potential for improving the degree of polarization of transmitted light. In our previous work absorber thickness of bi-layer attPSM, i.e. Ta/SiO II, was optimized through three-dimensional electromagnetic field (3D-EMF) simulations for better imaging performance than the MoSi attPSM. In this study, the thickness-optimized Ta/SiO II attPSM was fabricated to compare the imaging performance with the standard Ta/SiO II and MoSi attPSMs with 6% transmission and 180 ° phase shift. The thickness-optimized Ta/SiO II attPSM has 1% transmission due to 50% thicker Ta than the standard, while the 180 ° phase shift is controlled by SiO II thickness. The exposure latitude of 45 nm LS delineated by using an NA1.20 full-field scanner with xy-polarized cquadrupole was 15.7%, 13.4%, and 10.1% with depth of focus of 200 nm for the optimized Ta/SiO II, the standard Ta/SiO II, and MoSi, respectively. Line width roughness of the Ta/SiO II attPSMs was approximately 5.5 nm for the 45 nm LS, which was comparable to MoSi. Mask-error-enhancement factor (MEEF) of the 45 nm LS was 4.4, 4.9, and 3.8 for the optimized Ta/SiO II, the standard Ta/SiO II, and MoSi, though the simulation expected MEEF values of 4.1, 5.5, and 6.3, respectively. Because the transmission and the phase shift measured by normal incidence are not linked directly with the imaging performance in the

  12. Quality investigation of surface mount technology using phase-shifting digital holography

    Boonsri, Chantira; Buranasiri, Prathan


    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.

  13. Ultra-fast line-field low coherence holographic elastography using spatial phase shifting

    Liu, Chih-Hao; Schill, Alexander; Raghunathan, Raksha; Wu, Chen; Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Larin, Kirill V.


    Optical coherence elastography (OCE) is an emerging technique for quantifying tissue biomechanical properties. Generally, OCE relies on point-by-point scanning. However, long acquisition times make point-by-point scanning unfeasible for clinical use. Here we demonstrate a noncontact single shot line-field low coherence holography system utilizing an automatic Hilbert transform analysis based on a spatial phase shifting technique. Spatio-temporal maps of elastic wave propagation were acquired with only one air-pulse excitation and used to quantify wave velocity and sample mechanical properties at a line rate of 200 kHz. Results obtained on phantoms were correlated with data from mechanical testing. Finally, the stiffness of porcine cornea at different intraocular pressures was also quantified in situ.

  14. Instantaneous high-resolution focus tracking and a vibrometery system using parallel phase shift interferometry

    Ney, Michael; Safrani, Avner; Abdulhlaim, Ibrahim


    High resolution fast focus tracking and vibrometery system based on parallel phase shift polarization interferometry using three detectors is presented. The basic design and algorithm are described, followed by an experimental demonstration showing sub nm resolution of different controlled motion profiles instantaneously monitored at a feedback rate of 100 kHz. The fact that the method does not rely on active optical components, potentially allows extremely high vibration rates to be measured; limited only by the detector bandwidth and sampling rate. In addition, the relatively simple design relies only on standard optical equipment, combined with the simple algorithm, makes the task of setting up a high performance vibrometry system cheap and readily available.

  15. Analysis and synthesis of phase shifting algorithms based on linear systems theory

    Servin, M.; Estrada, J. C.


    We review and update a recently published formalism for the theory of linear Phase Shifting Algorithms (PSAs) based on linear filtering (systems) theory, mainly using the Frequency Transfer Function (FTF). The FTF has been for decades the standard tool in Electrical Engineering to analyze and synthesize their linear systems. Given the well defined FTF approach (matured over the last century), it clarifies, in our view, many not fully understood properties of PSAs. We present easy formulae for the spectra of the PSAs (the FTF magnitude), their Signal to Noise (S/N) power-ratio gain, their detuning robustness, and their harmonic rejection in terms of the FTF. This paper has more practical appeal than previous publications by the same authors, hoping to enrich the understanding of this PSA's theory as applied to the analysis and synthesis of temporal interferometry algorithms in Optical Metrology.

  16. Ultrasonic imaging of seismic physical models using a phase-shifted fiber Bragg grating.

    Guo, Jingjing; Xue, Shigui; Zhao, Qun; Yang, Changxi


    We report what is to our knowledge the first ultrasonic imaging of seismic physical models by using a phase-shifted fiber Bragg grating (PS-FBG). Seismic models, which consist of multiple layer structures, were immersed in water. Piezoelectric (PZT) transducer was used to generate ultrasonic waves and a PS-FBG as a receiver. Two-dimensional (2D) ultrasonic images were reconstructed by scanning the PS-FBG with a high-precision position scanning device. In order to suppress the low-frequency drift of the Bragg wavelength during scanning, a tight wavelength tracking method was employed to lock the laser to the PS-FBG resonance in its reflection bandgap. The ultrasonic images captured by the PS-FBG have been compared with the images obtained by the geophysical imaging system, Sinopec, demonstrating the feasibility of our PS-FBG based imaging system in seismic modeling studies.

  17. High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

    Bauman, B J; Campbell, E W; Olivier, S S; Sweider, D R


    A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system.

  18. 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


    To overcome the signal disturbance from the transmission process, recently, a new type of protocol named round-robin differential-phase-shift(RRDPS) quantum key distribution[Nature 509, 475(2014)] is proposed. It can estimate how much information has leaked to eavesdropper without monitoring bit error rates. In this paper, we compare the performance of RRDPS using different sources without and with decoy-state method, such as weak coherent pulses(WCPs) and heralded single photon source(HSPS). For practical implementations, we propose finite decoy-state method for RRDPS, the performance of which is close to the infinite one. Taking WCPs as an example, the three-intensity decoystate protocol can distribute secret keys over a distance of 128 km when the length of pulses packet is 32, which confirms the great practical interest of our method.

  19. Experimental Passive Round-Robin Differential Phase-Shift Quantum Key Distribution

    Guan, Jian-Yu; Cao, Zhu; Liu, Yang; Shen-Tu, Guo-Liang; Pelc, Jason S.; Fejer, M. M.; Peng, Cheng-Zhi; Ma, Xiongfeng; Zhang, Qiang; Pan, Jian-Wei


    In quantum key distribution (QKD), the bit error rate is used to estimate the information leakage and hence determines the amount of privacy amplification—making the final key private by shortening the key. In general, there exists a threshold of the error rate for each scheme, above which no secure key can be generated. This threshold puts a restriction on the environment noises. For example, a widely used QKD protocol, the Bennett-Brassard protocol, cannot tolerate error rates beyond 25%. A new protocol, round-robin differential phase-shifted (RRDPS) QKD, essentially removes this restriction and can in principle tolerate more environment disturbance. Here, we propose and experimentally demonstrate a passive RRDPS QKD scheme. In particular, our 500 MHz passive RRDPS QKD system is able to generate a secure key over 50 km with a bit error rate as high as 29%. This scheme should find its applications in noisy environment conditions.

  20. Superresolution imaging method using phase-shifting digital lensless Fourier holography.

    Granero, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier


    A method which is useful for obtaining superresolved imaging in a digital lensless Fourier holographic configuration is presented. By placing a diffraction grating between the input object and the CCD recording device, additional high-order spatial-frequency content of the object spectrum is directed towards the CCD. Unlike other similar methods, the recovery of the different band pass images is performed by inserting a reference beam in on-axis mode and using phase-shifting method. This strategy provides advantages concerning the usage of the whole frequency plane as imaging plane. Thus, the method is no longer limited by the zero order term and the twin image. Finally, the whole process results in a synthetic aperture generation that expands up the system cutoff frequency and yields a superresolution effect. Experimental results validate our concepts for a resolution improvement factor of 3.

  1. Phase shifts and the role of herbivory in the resilience of coral reefs

    Ledlie, M. H.; Graham, N. A. J.; Bythell, J. C.; Wilson, S. K.; Jennings, S.; Polunin, N. V. C.; Hardcastle, J.


    Cousin Island marine reserve (Seychelles) has been an effectively protected no-take marine protected area (MPA) since 1968 and was shown in 1994 to support a healthy herbivorous fish assemblage. In 1998 Cousin Island reefs suffered extensive coral mortality following a coral bleaching event, and a phase shift from coral to algal dominance ensued. By 2005 mean coral cover was habits of six abundant and representative herbivorous fish species around Cousin Island in 2006 demonstrated that epilithic algae were the preferred food resource of all species and that macroalgae were avoided. Given the current dominance of macroalgae and the apparent absence of macroalgal consumers, it is suggested that the increasing abundance of macroalgae is reducing the probability of the system reverting to a coral dominated state.

  2. A Comparison of De-noising Methods for Diff erential Phase Shift and Associated Rainfall Estimation

    胡志群; 刘察平; 吴林林; 魏庆


    Measured diff erential phase shift Φ DP is known to be a noisy unstable polarimetric radar variable, such that the quality of Φ DP data has direct impact on specifi c diff erential phase shift KDP estimation, and subsequently, the KDP-based rainfall estimation. Over the past decades, many Φ DP de-noising methods have been developed; however, the de-noising eff ects in these methods and their impact on KDP-based rainfall estimation lack comprehensive comparative analysis. In this study, simulated noisy Φ DP data were generated and de-noised by using several methods such as fi nite-impulse response (FIR), Kalman, wavelet, traditional mean, and median fi lters. The biases were compared between KDP from simulated and observedΦ DP radial profi les after de-noising by these methods. The results suggest that the complicated FIR, Kalman, and wavelet methods have a better de-noising eff ect than the traditional methods. AfterΦ DP was de-noised, the accuracy of the KDP-based rainfall estimation increased signifi cantly based on the analysis of three actual rainfall events. The improvement in estimation was more obvious when KDP was estimated withΦ DP de-noised by Kalman, FIR, and wavelet methods when the average rainfall was heavier than 5 mm h−1. However, the improved estimation was not signifi cant when the precipitation intensity further increased to a rainfall rate beyond 10 mm h−1. The performance of wavelet analysis was found to be the most stable of these fi lters.

  3. Evaluation of quadrature-phase-shift-keying signal characteristics in W-band radio-over-fiber transmission using direct in-phase/quadrature-phase conversion technique

    Suzuki, Meisaku; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki


    The effects of in-phase/quadrature-phase (IQ) imbalances are evaluated with a direct IQ down-converter in the W-band (75-110 GHz). The IQ imbalance of the converter is measured within a range of +/-10 degrees in an intermediate frequency of DC-26.5 GHz. 1-8-G-baud quadrature phase-shift keying (QPSK) signals are transmitted successfully with observed bit error rates within a forward error correction limit of 2×10-3 using radio over fiber (RoF) techniques. The direct down-conversion technique is applicable to next-generation high-speed wireless access communication systems in the millimeter-wave band.

  4. The Silicon and Calcium High-Velocity Features in Type Ia Supernovae from Early to Maximum Phases

    Zhao, Xulin; Maeda, Keiichi; Sai, Hanna; Zhang, Tianmeng; Zhang, Jujia; Huang, Fang; Rui, Liming; Zhou, Qi; Mo, Jun


    The high-velocity features (HVFs) in optical spectra of type Ia supernovae (SNe Ia) are examined with a large sample including very early-time spectra (e.g., t < -7 days). Multiple Gaussian fits are applied to examine the HVFs and their evolutions, using constraints on expansion velocities for the same species (i.e., SiII 5972 and SiII 6355). We find that strong HVFs tend to appear in SNe Ia with smaller decline rates (e.g., dm15(B)<1.4 mag), clarifying that the finding by Childress et al. (2014) for the Ca-HVFs in near-maximum-light spectra applies both to the Si-HVFs and Ca-HVFs in the earlier phase. The Si-HVFs seem to be more common in fast-expanding SNe Ia, which is different from the earlier result that the Ca-HVFs are associated with SNe Ia having slower SiII 6355 velocities at maximum light (i.e., Vsi). This difference can be due to that the HVFs in fast-expanding SNe Ia usually disappear more rapidly and are easily blended with the photospheric components when approaching the maximum light. Mor...

  5. Simultaneous all-optical demultiplexing and regeneration based on self-phase and cross-phase modulation in a dispersion shifted fiber

    Yu, Jianjun; Jeppesen, Palle


    Simultaneous demultiplexing and regeneration of 40-Gb/s optical time division multiplexed (OTDM) signal based on self-phase and cross-phase modulation in a dispersion shifted fiber is numerically and experimentally investigated. The optimal walkoff time between the control pulse and OTDM signal...

  6. Near-field observation of spatial phase shifts associated with Goos-Hänschen and Surface Plasmon Resonance effects.

    Jose, J; Segerink, F B; Korterik, J P; Offerhaus, H L


    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 phase-sensitive Photon Scanning Tunneling Microscope (PSTM) and shows a good agreement with theory.

  7. Unequal-period combination approach of gray code and phase-shifting for 3-D visual measurement

    Yu, Shuang; Zhang, Jing; Yu, Xiaoyang; Sun, Xiaoming; Wu, Haibin


    Combination of Gray code and phase-shifting is the most practical and advanced approach for the structured light 3-D measurement so far, which is able to measure objects with complex and discontinuous surface. However, for the traditional combination of the Gray code and phase-shifting, the captured Gray code images are not always sharp cut-off in the black-white conversion boundaries, which may lead to wrong decoding analog code orders. Moreover, during the actual measurement, there also exists local decoding error for the wrapped analog code obtained with the phase-shifting approach. Therefore, for the traditional approach, the wrong analog code orders and the local decoding errors will consequently introduce the errors which are equivalent to a fringe period when the analog code is unwrapped. In order to avoid one-fringe period errors, we propose an approach which combines Gray code with phase-shifting according to unequal period. With theoretical analysis, we build the measurement model of the proposed approach, determine the applicable condition and optimize the Gray code encoding period and phase-shifting fringe period. The experimental results verify that the proposed approach can offer a reliable unwrapped analog code, which can be used in 3-D shape measurement.

  8. Phase shift from a coral to a corallimorph-dominated reef associated with a shipwreck on Palmyra atoll.

    Work, Thierry M; Aeby, Greta S; Maragos, James E


    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.

  9. Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier

    Cheng-Tao Tsai


    Full Text Available 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.

  10. Retrieval of Gap Fraction and Effective Plant Area Index from Phase-Shift Terrestrial Laser Scans

    Pyare Pueschel


    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.

  11. Phase-shift Laser Rangefinder%并行鉴相测距激光雷达



    介绍了基于相位法的测距方法,即方波与方波相关法。提出了测量方案和算法。并用Matlab的Simulink工具对测距原理进行了仿真,还对测距精度进行了分析。从理论上证明了此种相位法测距的可行性,为实际激光测距系统的研制奠定了基础。%A laser range finder method based on square-square wave measurement is proposed. The architecture of the system and the principle of phase ranging algorithm are discussed with Matlab Simulink simulation results for one-dimensional distance. The imaging precision is also analyzed. The simulation shows that this algorithms and principles are effective and useful for research of phase-shift laser rangefinder.

  12. Experimental round-robin differential phase-shift quantum key distribution

    Li, Yu-Huai; Cao, Yuan; Dai, Hui; Lin, Jin; Zhang, Zhen; Chen, Wei; Xu, Yu; Guan, Jian-Yu; Liao, Sheng-Kai; Yin, Juan; Zhang, Qiang; Ma, Xiongfeng; Peng, Cheng-Zhi; Pan, Jian-Wei


    In conventional quantum key distribution (QKD) protocols, security is guaranteed by estimating the amount of leaked information. Such estimation tends to overrate, leading to a fundamental threshold of the bit error rate, which becomes a bottleneck of practical QKD development. This bottleneck is broken through by the recent work of round-robin differential phase-shift (RRDPS) protocol, which eliminates the fundamental threshold of the bit error rate. The key challenge for the implementation of the RRDPS scheme lies in the realization of a variable-delay Mach-Zehnder interferometer, which requires active and random choice of many delays. By designing an optical system with multiple switches and employing an active phase stabilization technology, we successfully construct a variable-delay interferometer with 127 actively selectable delays. With this measurement, we experimentally demonstrate the RRDPS protocol and obtain a final key rate of 15.54 bps with a total loss of 18 dB and an error rate of 8.9%.

  13. Demodulation of acoustic telemetry binary phase shift keying signal based on high-order Duffing system

    Yan, Bing-Nan; Liu, Chong-Xin; Ni, Jun-Kang; Zhao, Liang


    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).

  14. Decision-directed automatic gain control for MAPSK systems. [M-ary Amplitude and Phase Shift Keying

    Weber, W. J., III


    An automatic gain control (AGC) loop is presented for use with M-ary amplitude and phase shift keying (MAPSK) systems. The gain control amplifier is regulated by an error signal formed by the difference between the estimated amplitude level and the received amplitude level. The AGC performance is thus independent of the short-term average received signal energy. AGC loop analysis and simulation is presented for M-ary amplitude shift keying and quadrature amplitude shift keying. The AGC is shown to have a negligible degradation on the symbol probability of error for most practical cases. A generalized AGC for an arbitrary MAPSK system is presented.

  15. The LCPDI: A Compact and Robust Phase-Shifting Point-Diffraction Interferometer Based on Dye-Doped LC Technology

    Marshall, K.L.; Adelsberger, K.; Myhre, G.; Griffin, D.W.


    Point-diffraction interferometers, by design, are much less sensitive to environmental disturbances than dual-path interferometers, but, until very recently, have not been capable of phase shifting. The liquid crystal point diffraction interferometer (LCPDI) utilizes a dye-doped, liquid crystal (LC), electro-optical device that functions as both the point-diffraction source and the phase-shifting element, yielding a phase-shifting diagnostic device that is significantly more compact and robust while also using fewer optical elements than conventional dual-path interferometers. These attributes make the LCPDI of special interest for diagnostic applications in the scientific, commercial, military, and industrial sectors, where vibration insensitivity, power requirements, size, weight, and cost are critical issues.

  16. Contrast and phase-shift of a trapped atom interferometer using a thermal ensemble with internal state labelling

    Dupont-Nivet, M; Schwartz, S


    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 minimize 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 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.

  17. Phase-shift effect of amplitude spread function on spectrum and image formation in coherent Raman scattering microspectroscopy.

    Fukutake, Naoki


    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.

  18. Drive Signal Frequency-Lock Method Based on 90° Phase Shift for Quartz Angular-Rate Sensor

    LIAO Xing-cai; SUN Yu-nan; TANG Qiong; CUI Fang


    A drive signal frequency-lock method for quartz angular-rate sensor is presented. The calculation result obtained by the equivalent volume force analytic method indicated that when taking the inherent frequency of the drive tines as the drive signal frequency the phase of the reference vibration is 90° behind that of the drive signal, and the square of amplitude is less than that of the maximal amplitude by 1/(4Q2d) merely. The curves derived from the finite element analytic method proved that near the inherent frequency the phase shift of the feedback voltage is identical to that of the reference vibration, and the amplitude is proportional to that of the reference vibration, and the phase shift is linear approximatively with the frequency shift. The frequency shift could be calculated according to the phase shift obtained by quadrature correlation detection, so the drive signal frequency could be locked at the inherent frequency of the drive tines by means of iteration.

  19. Properties and geoeffectiveness of magnetic clouds in the rising, maximum and early declining phases of solar cycle 23

    K. E. J. Huttunen


    Full Text Available The magnetic structure and geomagnetic response of 73 magnetic clouds (MC observed by the WIND and ACE satellites in solar cycle 23 are examined. The results have been compared with the surveys from the previous solar cycles. The preselected candidate MC events were investigated using the minimum variance analysis to determine if they have a flux-rope structure and to obtain the estimation for the axial orientation (θC, φC. Depending on the calculated inclination relative to the ecliptic we divided MCs into "bipolar" (θC<45° and "unipolar" (θC>45°. The number of observed MCs was largest in the early rising phase, although the halo CME rate was still low. It is likely that near solar maximum we did not identify all MCs at 1AU, as they were crossed far from the axis or they had interacted strongly with the ambient solar wind or with other CMEs. The occurrence rate of MCs at 1AU is also modified by the migration of the filament sites on the Sun towards the poles near solar maximum and by the deflection of CMEs towards the equator due to the fast solar wind flow from large polar coronal holes near solar minimum. In the rising phase nearly all bipolar MCs were associated with the rotation of the magnetic field from the south at the leading edge to the north at the trailing edge. The results for solar cycles 21-22 showed that the direction of the magnetic field in the leading portion of the MC starts to reverse at solar maximum. At solar maximum and in the declining phase (2000-2003 we observed several MCs with the rotation from the north to the south. We observed unipolar (i.e. highly inclined MCs frequently during the whole investigated period. For solar cycles 21-22 the majority of MCs identified in the rising phase were bipolar while in the declining phase most MCs were unipolar. The geomagnetic response of a given MC depends greatly on its magnetic structure and the orientation of the sheath

  20. Analytical calculation of the frequency shift in phase oscillators driven by colored noise: implications for electrical engineering and neuroscience.

    Galán, Roberto F


    We provide an analytical expression for the mean frequency shift in phase oscillators as a function of the standard deviation, sigma and the autocorrelation time, tau of small random perturbations. We show that the frequency shift is negative and proportional to sigma;{2} . Its absolute value increases monotonically with tau , approaching an asymptote determined by the L2 -norm of the phase-response curve. We validate our theoretical predictions with computer simulations and discuss their implications for the design of electronic oscillators and for the encoding of information in biological neural networks.

  1. Simple Scheme for Realizing the General Conditional Phase Shift Gate and a Simulation of Quantum Fourier Transform in Circuit QED

    吴春旺; 韩阳; 邓志姣; 李虹轶; 陈平形; 李承祖


    We propose a theoretical scheme for realizing the general conditional phase shift gate of charge qubits situated in a high-Q superconducting transmission line resonator. The phase shifting angle can be tuned from 0 to 27r by simply adjusting the qubit-resonator detuning and the interaction time. Based on this gate proposal, we give a detailed procedure to implement the three-qubit quantum Fourier transform with circuit quantum eleetrodynamics (QED). A careful analysis of the decoherence sources shows that the algorithm can be achieved with a high fidelity using current circuit QED techniques.

  2. Generation of large fifth-order nonlinear phase shifts by use of lossless χ(2) cascaded nonlinear processes

    XU Guang; QIAN Liejia; WANG Tao; FAN Dianyuan; LI Fuming


    It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonlinearities, the loss of fundamental wave in a cascaded process is controllable and suppressible. By introducing difference frequencies generated from the reaction between the fundamental and its second harmonic after the cascaded processes, the fundamental wave can be free of energy loss, while the large cascaded fifth-order nonlinear phase shift is maintained.

  3. Shifting the feeding of mice to the rest phase creates metabolic alterations, which, on their own, shift the peripheral circadian clocks by 12 hours

    Mukherji, Atish; Kobiita, Ahmad; Chambon, Pierre


    The molecular mechanisms underlying the events through which alterations in diurnal activities impinge on peripheral circadian clocks (PCCs), and reciprocally how the PCCs affect metabolism, thereby generating pathologies, are still poorly understood. Here, we deciphered how switching the diurnal feeding from the active to the rest phase, i.e., restricted feeding (RF), immediately creates a hypoinsulinemia during the active phase, which initiates a metabolic reprogramming by increasing FFA and glucagon levels. In turn, peroxisome proliferator-activated receptor alpha (PPARα) activation by free fatty acid (FFA), and cAMP response element-binding protein (CREB) activation by glucagon, lead to further metabolic alterations during the circadian active phase, as well as to aberrant activation of expression of the PCC components nuclear receptor subfamily 1, group D, member 1 (Nr1d1/RevErbα), Period (Per1 and Per2). Moreover, hypoinsulinemia leads to an increase in glycogen synthase kinase 3β (GSK3β) activity that, through phosphorylation, stabilizes and increases the level of the RevErbα protein during the active phase. This increase then leads to an untimely repression of expression of the genes containing a RORE DNA binding sequence (DBS), including the Bmal1 gene, thereby initiating in RF mice a 12-h PCC shift to which the CREB-mediated activation of Per1, Per2 by glucagon modestly contributes. We also show that the reported corticosterone extraproduction during the RF active phase reflects an adrenal aberrant activation of CREB signaling, which selectively delays the activation of the PPARα–RevErbα axis in muscle and heart and accounts for the retarded shift of their PCCs. PMID:26627259

  4. Phase shifts in binaural stimuli provide directional cues for sound localisation in the field cricket Gryllus bimaculatus.

    Seagraves, Kelly M; Hedwig, Berthold


    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.

  5. Finite volume treatment of pi pi scattering and limits to phase shifts extraction from lattice QCD

    Albaladejo, M; Oset, E; Rios, G; Roca, L


    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...

  6. Pattern Corotation Radii from Potential-Density Phase-Shifts for 153 OSUBGS Sample Galaxies

    Buta, Ronald J


    We apply the potential-density phase-shift method to 153 galaxies in the Ohio State University Bright Galaxy Survey (OSUBGS) to study the general relationship between pattern corotation radii and the morphology of spiral galaxies. The analysis is based on deprojected near-infrared H-band images. We find that multiple pattern speeds are common in disk galaxies. By selecting those corotation radii close to or slightly larger than the bar radius as being the bar corotation (CR) radius, we find that the average and standard deviation of the ratio R = r(CR)/r(bar), is 1.20+/-0.52 for 101 galaxies having well-defined bars. There is an indication that this ratio depends weakly on galaxy type in the sense that the average ranges from 1.03+/-0.37 for 65 galaxies of type Sbc and earlier, to 1.50+/-0.63 for 36 galaxies of type Sc and later. Our bar corotation radii are on average smaller than those estimated from single-pattern-speed numerical simulations, most likely because these simulations tend to find the pattern s...

  7. 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.


    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.

  8. Locality of Area Coverage on Digital Acoustic Communication in Air using Differential Phase Shift Keying

    Mizutani, Keiichi; Ebihara, Tadashi; Wakatsuki, Naoto; Mizutani, Koichi


    We experimentally evaluate the locality of digital acoustic communication in air. Digital acoustic communication in air is suitable for a small cell system, because acoustic waves have a short propagation distance in air. In this study, optimal cell size is experimentally evaluated. Each base station (BS) transmits different commands. In our experiment, differential phase shift keying (DPSK), especially binary DPSK (DBPSK), is adopted as a modulation and demodulation scheme. The evaluated system consists of a personal computer (PC), a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), a loud speaker (SP), a microphone (MIC), and transceiver software. All experiments are performed in an anechoic room. The cell size of the transmitter can be limited under low signal-to-noise ratio (SNR) condition. If another transmitter works, cell size is limited by the effect of the interference from that transmitter. The cell size-to-distance ratio of transmitter A to transmitter B is 37.5%, if cell edge bit-error-rate (BER) is taken as 10-3.

  9. Round-robin differential-phase-shift quantum key distribution with heralded pair-coherent sources

    Wang, Le; Zhao, Shengmei


    Round-robin differential-phase-shift (RRDPS) quantum key distribution (QKD) scheme provides an effective way to overcome the signal disturbance from the transmission process. However, most RRDPS-QKD schemes use weak coherent pulses (WCPs) as the replacement of the perfect single-photon source. Considering the heralded pair-coherent source (HPCS) can efficiently remove the shortcomings of WCPs, we propose a RRDPS-QKD scheme with HPCS in this paper. Both infinite-intensity decoy-state method and practical three-intensity decoy-state method are adopted to discuss the tight bound of the key rate of the proposed scheme. The results show that HPCS is a better candidate for the replacement of the perfect single-photon source, and both the key rate and the transmission distance are greatly increased in comparison with those results with WCPs when the length of the pulse trains is small. Simultaneously, the performance of the proposed scheme using three-intensity decoy states is close to that result using infinite-intensity decoy states when the length of pulse trains is small.

  10. Practical round-robin differential-phase-shift quantum key distribution

    Zhang, Zhen; Yuan, Xiao; Cao, Zhu; Ma, Xiongfeng


    The security of quantum key distribution (QKD) relies on the Heisenberg uncertainty principle, with which legitimate users are able to estimate information leakage by monitoring the disturbance of the transmitted quantum signals. Normally, the disturbance is reflected as bit flip errors in the sifted key; thus, privacy amplification, which removes any leaked information from the key, generally depends on the bit error rate. Recently, a round-robin differential-phase-shift QKD protocol for which privacy amplification does not rely on the bit error rate (Sasaki et al 2014 Nature 509 475) was proposed. The amount of leaked information can be bounded by the sender during the state-preparation stage and hence, is independent of the behavior of the unreliable quantum channel. In our work, we apply the tagging technique to the protocol and present a tight bound on the key rate and employ a decoy-state method. The effects of background noise and misalignment are taken into account under practical conditions. Our simulation results show that the protocol can tolerate channel error rates close to 50% within a typical experiment setting. That is, there is a negligible restriction on the error rate in practice.

  11. 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


    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.

  12. Towards a phoenix phase in aeolian research: shifting geophysical perspectives from fluvial dominance

    Whicker, Jeffrey J [Los Alamos National Laboratory; Field, Jason P [UNIV OF ARIZONA; Breshears, David D [UNIV OF ARIZONA


    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.

  13. Differential phase shift quantum key distribution experiment over 105 km fibre

    Takesue, H; Honjo, T; Langrock, C; Fejer, M M; Inoue, K; Yamamoto, Y


    Since several papers appeared in 2000, the quantum key distribution (QKD) community has been well aware that photon number splitting (PNS) attack by Eve severely limits the secure key distribution distance in BB84 QKD systems with Poissonian photon sources. In attempts to solve this problem, entanglement-based QKD, single-photon based QKD, and entanglement swapping-based QKD, have been studied in recent years. However, there are many technological difficulties that must be overcome before these schemes can become practical systems. Here we report a very simple QKD system, in which secure keys were generated over >100 km fibre for the first time. We used an alternative protocol of differential phase shift keying (DPSK) but with a Poissonian source. We analysed the security of the DPSK protocol and showed that it is robust even against hybrid attacks including collective PNS attack over consecutive pulses, intercept-and-resend (I-R) attack and beamsplitting (BS) attack, because of the non-deterministic collapse...

  14. Unconventional Geometric Phase-Shift Gates Based on Superconducting Quantum Interference Devices Coupled to a Single-Mode Cavity

    SONG Ke-Hui; ZHOU Zheng-Wei; GUO Guang-Can


    We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device (SQUID) qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum logic in SQUID-system.

  15. Light-induced phase-shifting of the peripheral circadian oscillator in the hearts of food-deprived mice.

    Sakamoto, Katsuhiko; Kadota, Koji; Oishi, Katsutaka


    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.

  16. Impact of frequency modulation ratio on capacitor cells balancing in phase-shifted PWM based chain-link STATCOM

    Behrouzian, Ehsan; Bongiorno, Massimo; Teodorescu, Remus


    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...... distribution among cells of the same phase leg, thus contributing to the capacitors balancing. Theoretical conclusions are validated through PSCAD simulation results....

  17. Differentiation of osteoporotic and neoplastic vertebral fractures by chemical shift {l_brace}in-phase and out-of phase{r_brace} MR imaging

    Ragab, Yasser [Radiology Department, Faculty of Medicine, Cairo University (Egypt); Radiology Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail:; Emad, Yasser [Rheumatology and Rehabilitation Department, Faculty of Medicine, Cairo University (Egypt); Rheumatology and Rehabilitation Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail:; Gheita, Tamer [Rheumatology and Rehabilitation Department, Faculty of Medicine, Cairo University (Egypt)], E-mail:; Mansour, Maged [Oncology Department, Faculty of Medicine, Cairo University (Egypt); Oncology Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail:; Abou-Zeid, A. [Public Health Department, Faculty of Medicine, Cairo University, Cairo (Egypt)], E-mail:; Ferrari, Serge [Division of Bone Diseases, Department of Rehabilitation and Geriatrics, and WHO, Collaborating Center for Osteoporosis Prevention, Geneva University Hospital (Switzerland)], E-mail:; Rasker, Johannes J. [Rheumatologist University of Twente, Enschede (Netherlands)], E-mail:


    Objective: The objective of this study was to establish the cut-off value of the signal intensity drop on chemical shift magnetic resonance imaging (MRI) with appropriate sensitivity and specificity to differentiate osteoporotic from neoplastic wedging of the spine. Patients and methods: All patients with wedging of vertebral bodies were included consecutively between February 2006 and January 2007. A chemical shift MRI was performed and signal intensity after (in-phase and out-phase) images were obtained. A DXA was performed in all. Results: A total of 40 patients were included, 20 with osteoporotic wedging (group 1) and 20 neoplastic (group 2). They were 21 males and 19 females. Acute vertebral collapse was observed in 15 patients in group 1 and subacute collapse in another 5 patients, while in group 2, 11 patients showed acute collapse and 9 patients (45%) showed subacute vertebral collapse. On the chemical shift MRI a substantial reduction in signal intensity was found in all lesions in both groups. The proportional changes observed in signal intensity of bone marrow lesions on in-phase compared with out-of-phase images showed significant differences in both groups (P < 0.05). At a cut-off value of 35%, the observed sensitivity of out-of-phase images was 95%, specificity was 100%, positive predictive value was 100% and negative predictive value was 95.2%. Conclusion: A chemical shift MRI is useful in order to differentiate patients with vertebral collapse due to underlying osteoporosis or neoplastic process.

  18. The role of competition in the phase shift to dominance of the zoanthid Palythoa cf. variabilis on coral reefs.

    Cruz, Igor Cristino Silva; Meira, Verena Henschen; de Kikuchi, Ruy Kenji Papa; Creed, Joel Christopher


    Phase shift phenomena are becoming increasingly common. However, they are also opportunities to better understand how communities are structured. In Southwest Atlantic coral reefs, a shift to the zoanthid Palythoa cf. variabilis dominance has been described. To test if competition drove this process, we carried out a manipulative experiment with three coral species. To estimate the natural frequency of encounters we assess the relationship between the proportion of encounters and this zoanthids coverage. The contact causes necrosis in 78% of coral colonies (6.47 ± SD 7.92 cm(2)) in 118 days. We found a logarithmic relationship between the proportion of these encounters and the cover of P. cf. variabilis, where 5.5% coverage of this zoanthid is enough to put 50% of coral colonies in contact, increasing their partial mortality. We demonstrate that zoanthid coverage increase followed by coral mortality increase will reduce coral cover and that competition drives the phase shift process.

  19. Beware the two-beam coupling phase shift: Interpreting pump-probe measurements of the nonlinear refractive index

    Wahlstrand, J K; McCole, E T; Cheng, Y -H; Palastro, J P; Levis, R J; Milchberg, H M


    Nonlinear optics experiments measuring phase shifts induced in a weak probe pulse by a strong pump pulse must account for coherent effects that only occur when the pump and probe pulses are temporally overlapped. It is well known that a weak probe beam experiences a greater phase shift from a strong pump beam than the pump beam induces on itself. The physical mechanism behind the enhanced phase shift is diffraction of pump light into the probe direction by a nonlinear refractive index grating produced by interference between the two beams. For an instantaneous third-order response, the effect of the grating is to simply double the probe phase shift, but when delayed nonlinearities are considered, the effect is more complex. A comprehensive treatment is given for both degenerate and nondegenerate pump-probe experiments in noble and diatomic gases. Results of numerical calculations are compared to a recent transient birefringence measurement [Loriot et al., Opt. Express 17, 13429 (2009)] and a recent spectral i...

  20. Design of all-optical high-order temporal integrators based on multiple-phase-shifted Bragg gratings.

    Asghari, Mohammad H; Azaña, José


    In exact analogy with their electronic counterparts, photonic temporal integrators are fundamental building blocks for constructing all-optical circuits for ultrafast information processing and computing. In this work, we introduce a simple and general approach for realizing all-optical arbitrary-order temporal integrators. We demonstrate that the N(th) cumulative time integral of the complex field envelope of an input optical waveform can be obtained by simply propagating this waveform through a single uniform fiber/waveguide Bragg grating (BG) incorporating N pi-phase shifts along its axial profile. We derive here the design specifications of photonic integrators based on multiple-phase-shifted BGs. We show that the phase shifts in the BG structure can be arbitrarily located along the grating length provided that each uniform grating section (sections separated by the phase shifts) is sufficiently long so that its associated peak reflectivity reaches nearly 100%. The resulting designs are demonstrated by numerical simulations assuming all-fiber implementations. Our simulations show that the proposed approach can provide optical operation bandwidths in the tens-of-GHz regime using readily feasible photo-induced fiber BG structures.

  1. A Control Allocation System for Automatic Detection and Compensation of Phase Shift Due to Actuator Rate Limiting

    Yildiz, Yidiray; Kolmanovsky, Ilya V.; Acosta, Diana


    This paper proposes a control allocation system that can detect and compensate the phase shift between the desired and the actual total control effort due to rate limiting of the actuators. Phase shifting is an important problem in control system applications since it effectively introduces a time delay which may destabilize the closed loop dynamics. A relevant example comes from flight control where aggressive pilot commands, high gain of the flight control system or some anomaly in the system may cause actuator rate limiting and effective time delay introduction. This time delay can instigate Pilot Induced Oscillations (PIO), which is an abnormal coupling between the pilot and the aircraft resulting in unintentional and undesired oscillations. The proposed control allocation system reduces the effective time delay by first detecting the phase shift and then minimizing it using constrained optimization techniques. Flight control simulation results for an unstable aircraft with inertial cross coupling are reported, which demonstrate phase shift minimization and recovery from a PIO event.

  2. A VHF Interleaved Self-Oscillating Resonant SEPIC Converter with Phase-Shift Burst-Mode Control

    Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.


    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 in o...

  3. Improvement of Axial Resolution in Confocal Microscopy by an Optical Pupil Filter with Two Zones Phase-Shifted by π

    林列; 王湘晖; 王肇圻; 母国光


    A filter with two zones phase-shifted by π is proposed to improve the axial resolution of confocal microscopes with a finite-sized detector. The optimum axial resolution for a given size of the detector can be achieved by adjusting the zone boundary of the filter. The experimental results are well in agreement with the theoretical predictions.

  4. Phase shift from a coral to a corallimorph-dominated reef associated with a shipwreck on Palmyra atoll.

    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.

  5. Contrast biases the autocorrelation phase shift estimation in Doppler tissue imaging.

    Ressner, Marcus; Jansson, Tomas; Cedefamn, Jonny; Ask, Per; Janerot-Sjoberg, Birgitta


    Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations of the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index

  6. 3D velocity measurement by a single camera using Doppler phase-shifting holography

    Ninomiya, Nao; Kubo, Yamato; Barada, Daisuke; Kiire, Tomohiro


    In order to understand the details of the flow field in micro- and nano-fluidic devices, it is necessary to measure the 3D velocities under a microscopy. Thus, there is a strong need for the development of a new measuring technique for 3D velocity by a single camera. One solution is the use of holography, but it is well known that the accuracy in the depth direction is very poor for the commonly used in-line holography. At present, the Doppler phase-shifting holography is used for the 3D measurement of an object. This method extracts the signal of a fixed frequency caused by the Doppler beat between the object light and the reference light. It can measure the 3D shape precisely. Here, the frequency of the Doppler beat is determined by the velocity difference between the object light and the reference light. This implies that the velocity of an object can be calculated by the Doppler frequency. In this study, a Japanese 5 yen coin was traversed at a constant speed and its holography has been observed by a high-speed camera. By extracting only the first order diffraction signal at the Doppler frequency, a precise measurement of the shape and the position of a 5 yen coin has been achieved. At the same time, the longitudinal velocity of a 5 yen coin can be measured by the Doppler frequency. Furthermore, the lateral velocities are obtained by particle image velocimetry (PIV) method. A 5 yen coin has been traversed at different angles and its shapes and the 3D velocities have been measured accurately. This method can be applied to the particle flows in the micro- or nano-devices, and the 3D velocities will be measured under microscopes.

  7. X-ray Bragg magnifier microscope as a linear shift invariant imaging system: image formation and phase retrieval.

    Vagovič, P; Svéda, L; Cecilia, A; Hamann, E; Pelliccia, D; Gimenez, E N; Korytár, D; Pavlov, K M; Zápražný, Z; Zuber, M; Koenig, T; Olbinado, M; Yashiro, W; Momose, A; Fiederle, M; Baumbach, T


    We present the theoretical description of the image formation with the in-line germanium Bragg Magnifier Microscope (BMM) and the first successful phase retrieval of X-ray holograms recorded with this imaging system. The conditions under which the BMM acts as a linear shift invariant system are theoretically explained and supported by the experiment. Such an approach simplifies the mathematical treatment of the image formation and reconstruction as complicated propagation of the wavefront onto inclined planes can be avoided. Quantitative phase retrieval is demonstrated using a test sample and a proof of concept phase imaging of a spider leg is also presented.

  8. Measurements of the phase shift on reflection for low-order infrared Fabry-Perot interferometer dielectric stack mirrors.

    Mielke, S L; Ryan, R E; Hilgeman, T; Lesyna, L; Madonna, R G; Van Nostrand, W C


    A simple technique based on a Fizeau interferometer to measure the absolute phase shift on reflection for a Fabry-Perot interferometer dielectric stack mirror is described. Excellent agreement between the measured and predicted phase shift on reflection was found. Also described are the salient features of low-order Fabry-Perot interferometers and the demonstration of a near ideal low-order (1-10) Fabry-Perot interferometer through minimizing the phase dispersion on reflection of the dielectric stack. This near ideal performance of a low-order Fabry-Perot interferometer should enable several applications such as compact spectral imagers for solid and gas detection. The large free spectral range of such systems combined with an active control system will also allow simple interactive tuning of wavelength agile laser sources such as CO(2) lasers, external cavity diode lasers, and optical parametric oscillators.

  9. Shift work or food intake during the rest phase promotes metabolic disruption and desynchrony of liver genes in male rats.

    Salgado-Delgado, Roberto C; Saderi, Nadia; Basualdo, María del Carmen; Guerrero-Vargas, Natali N; Escobar, Carolina; Buijs, Ruud M


    In the liver, clock genes are proposed to drive metabolic rhythms. These gene rhythms are driven by the suprachiasmatic nucleus (SCN) mainly by food intake and via autonomic and hormonal pathways. Forced activity during the normal rest phase, induces also food intake, thus neglecting the signals of the SCN, leading to conflicting time signals to target tissues of the SCN. The present study explored in a rodent model of night-work the influence of food during the normal sleep period on the synchrony of gene expression between clock genes and metabolic genes in the liver. Male Wistar rats were exposed to forced activity for 8 h either during the rest phase (day) or during the active phase (night) by using a slow rotating wheel. In this shift work model food intake shifts spontaneously to the forced activity period, therefore the influence of food alone without induced activity was tested in other groups of animals that were fed ad libitum, or fed during their rest or active phase. Rats forced to be active and/or eating during their rest phase, inverted their daily peak of Per1, Bmal1 and Clock and lost the rhythm of Per2 in the liver, moreover NAMPT and metabolic genes such as Pparα lost their rhythm and thus their synchrony with clock genes. We conclude that shift work or food intake in the rest phase leads to desynchronization within the liver, characterized by misaligned temporal patterns of clock genes and metabolic genes. This may be the cause of the development of the metabolic syndrome and obesity in individuals engaged in shift work.

  10. Shift work or food intake during the rest phase promotes metabolic disruption and desynchrony of liver genes in male rats.

    Roberto C Salgado-Delgado

    Full Text Available In the liver, clock genes are proposed to drive metabolic rhythms. These gene rhythms are driven by the suprachiasmatic nucleus (SCN mainly by food intake and via autonomic and hormonal pathways. Forced activity during the normal rest phase, induces also food intake, thus neglecting the signals of the SCN, leading to conflicting time signals to target tissues of the SCN. The present study explored in a rodent model of night-work the influence of food during the normal sleep period on the synchrony of gene expression between clock genes and metabolic genes in the liver. Male Wistar rats were exposed to forced activity for 8 h either during the rest phase (day or during the active phase (night by using a slow rotating wheel. In this shift work model food intake shifts spontaneously to the forced activity period, therefore the influence of food alone without induced activity was tested in other groups of animals that were fed ad libitum, or fed during their rest or active phase. Rats forced to be active and/or eating during their rest phase, inverted their daily peak of Per1, Bmal1 and Clock and lost the rhythm of Per2 in the liver, moreover NAMPT and metabolic genes such as Pparα lost their rhythm and thus their synchrony with clock genes. We conclude that shift work or food intake in the rest phase leads to desynchronization within the liver, characterized by misaligned temporal patterns of clock genes and metabolic genes. This may be the cause of the development of the metabolic syndrome and obesity in individuals engaged in shift work.

  11. Phase-shifting of correlation fringes created by image processing as an alternative to improve digital shearography

    Braga, Roberto A.; González-Peña, Rolando J.; Marcon, Marlon; Magalhães, Ricardo R.; Paiva-Almeida, Thiago; Santos, Igor V. A.; Martins, Moisés


    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.

  12. The Effect of Phase-Shifting between Pumping and Signal Lights on Transmission Performance of Optical Fiber Communication Systems with in-Line PSA


    In this paper, the effect of phase-shifting between pumping light and input signal light in an optical Phase-Sensitive Amplifier (PSA) on dispersion compensation for optical fiber communication systems using PSA as in-line amplifiers is theoretically analyzed by computer simulation. From our simulation, we've got the result that the eye-pattern degradation of the high-speed signal increases rapidly with the accretion of fiber dispersion and also increases with the increasing of phase shift. But if the phase shift is controlled in a certain range, it won't affect the system performance. Otherwise, the system performance will be seriously degraded. At all events, the shifting range of PSA's phase, which shifts at both sides of zero, will be half of that which shifts at only one side.

  13. The multi-faceted Type II-L supernova 2014G from pre-maximum to nebular phase

    Terreran, G; Benetti, S; Smartt, S J; Ochner, P; Tomasella, L; Howell, D A; Morales-Garoffolo, A; Harutyunyan, A; Kankare, E; Arcavi, I; Cappellaro, E; Elias-Rosa, N; Hosseinzadeh, G; Kangas, T; Pastorello, A; Tartaglia, L; Turatto, M; Valenti, S; Wiggins, P; Yuan, F


    We present multi-band ultraviolet, optical, and near-infrared photometry, along with visual-wavelength spectroscopy, of supernova (SN) 2014G in the nearby galaxy NGC 3448 (25 Mpc). The early-phase spectra show strong emission lines of the high ionisation species He II/N IV/C IV during the first 2-3 d after explosion, traces of a metal-rich CSM probably due to pre-explosion mass loss events. These disappear by day 9 and the spectral evolution then continues matching that of normal Type II SNe. The post-maximum light curve declines at a rate typical of Type II-L class. The extensive photometric coverage tracks the drop from the photospheric stage and constrains the radioactive tail, with a steeper decline rate than that expected from the $^{56}$Co decay if $\\gamma$-rays are fully trapped by the ejecta. We report the appearance of an unusual feature on the blue-side of H$\\alpha$ after 100 d, which evolves to appear as a flat spectral feature linking H$\\alpha$ and the O I doublet. This may be due to interaction o...

  14. 相控阵天线全光移相网络%Optical phase-shifting networks for phased array antenna

    苏君; 邱琪; 史双瑾


    采用全光移相网络的光控相控阵天线具有使空间波束实现宽带宽角扫描的优势.传统相控阵天线受电移相网络的自身特性限制,瞬时应用带宽有限.系统分析了典型全光移相网络的技术特点,以及各个技术合适的应用方向和方案.%Optical phased array antenna based on optical phase-shifting networks continues to be an important challenge today, despite the advances made in beam squint-free scan for ultra-wideband signals. The traditional optical phased array antenna, described as characteristics limit of electronic phase-shifting networks, is beginning to provide low instantaneous bandwidth. In this paper, we systematically analyze the technical characteristics of typical optical phase-shifting networks and discuss some of the appropriate application domain of various networks.

  15. Numerical analysis for four-wave mixing based wavelength conversion of differential phase-shift keying signals

    Liang Jia; Fan Zhang; Ming Li; Yuliang Liu; Zhangyuan Chen


    We numerically investigate the main constrains for high efficiency wavelength conversion of differential phase-shift keying (DPSK) signals based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF). Using multi-tone pump phase modulation techniques, high efficiency wavelength conversion of DPSK signals is achieved with the stimulated Brillouin scattering (SBS) effects effectively suppressed. Our analysis shows that there is a compromise between conversion efficiency and converted idler degradation. By optimizing the pump phase modulation configuration, the converted DPSK idler's degradation can be dramatically decreased through balancing SBS suppression and pump phase modulation degradation. Our simulation results also show that these multi-tone pump phase modulation techniques are more appropriate for the future high bit rate systems.


    Yanming Chen; Yuming He; Eryi Hu; Hongmao Zhu


    phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry (PSP) can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.

  17. Phase-shift nano-emulsions induced cavitation and ablation during high intensity focused ultrasound exposure

    Qiao, Yangzi; Yin, Hui; Chang, Nan; Wan, Mingxi


    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

  18. 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


    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.

  19. Resynchronization of circadian sleep-wake and temperature cycles in the squirrel monkey following phase shifts of the environmental light-dark cycle

    Wexler, D.B.; Moore-ede, M.C.


    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. 13 references.

  20. Resynchronization of circadian sleep-wake and temperature cycles in the squirrel monkey following phase shifts of the environmental light-dark cycle

    Wexler, D. B.; Moore-Ede, M. C.


    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.

  1. Efficient face recognition using local derivative pattern and shifted phase-encoded fringe-adjusted joint transform correlation

    Biswas, Bikram K.; Alam, Mohammad S.; Chowdhury, Suparna


    An improved shifted phase-encoded fringe-adjusted joint transform correlation technique is proposed in this paper for face recognition which can accommodate the detrimental effects of noise, illumination, and other 3D distortions such as expression and rotation variations. This technique utilizes a third order local derivative pattern operator (LDP3) followed by a shifted phase-encoded fringe-adjusted joint transform correlation (SPFJTC) operation. The local derivative pattern operator ensures better facial feature extraction in a variable environment while the SPFJTC yields robust correlation output for the desired signals. The performance of the proposed method is determined by using the Yale Face Database, Yale Face Database B, and Georgia Institute of Technology Face Database. This technique has been found to yield better face recognition rate compared to alternate JTC based techniques.

  2. Renormalized. pi. NN coupling constant and the P-italic-wave phase shifts in the cloudy bag model

    Pearce, B.C.; Afnan, I.R.


    Most applications of the cloudy bag model to ..pi..N scattering involve unitarizing the bare diagrams arising from the Lagrangian by iterating in a Lippmann-Schwinger equation. However, analyses of the renormalization of the coupling constant proceed by iterating the Lagrangian to a given order in the bare coupling constant. These two different approaches means there is an inconsistency between the calculation of phase shifts and the calculation of renormalization. A remedy to this problem is presented that has the added advantage of improving the fit to the phase shifts in the P-italic/sub 11/ channel. This is achieved by using physical values of the coupling constant in the crossed diagram which reduces the repulsion rather than adds attraction. This approach can be justified by examining equations for the ..pi pi..N system that incorporate three-body unitarity.

  3. Renormalized πNN coupling constant and the P-wave phase shifts in the cloudy bag model

    Pearce, B. C.; Afnan, I. R.


    Most applications of the cloudy bag model to πN scattering involve unitarizing the bare diagrams arising from the Lagrangian by iterating in a Lippmann-Schwinger equation. However, analyses of the renormalization of the coupling constant proceed by iterating the Lagrangian to a given order in the bare coupling constant. These two different approaches means there is an inconsistency between the calculation of phase shifts and the calculation of renormalization. A remedy to this problem is presented that has the added advantage of improving the fit to the phase shifts in the P11 channel. This is achieved by using physical values of the coupling constant in the crossed diagram which reduces the repulsion rather than adds attraction. This approach can be justified by examining equations for the ππN system that incorporate three-body unitarity.

  4. Predicting phase shift effects for vibrating fluid-conveying pipes due to Coriolis forces and fluid pulsation

    Enz, Stephanie; Thomsen, Jon Juel


    displacement and approximate axial shift in vibration phase. The analytical predictions are tested against pure numerical solution using representative examples, showing good agreement. Fluid pulsations are predicted not to influence CFM accuracy, since proper signal filtering is seen to allow......Knowing the influence of fluid flow perturbations on the dynamic behavior of fluid-conveying pipes is of relevance, e.g., when exploiting flow-induced oscillations of pipes to determine the fluids mass flow or density, as done with Coriolis flow meters (CFM). This could be used in the attempts...... the determination of the correct mean phase shift. Large amplitude motions, which could influence CFM robustness, do not appear to be induced by the investigated fluid pulsation. Pulsating fluid of the combination resonance type could, however, influence CFMs robustness, if induced pipe motions go unnoticed...

  5. Study of a single longitudinal fiber ring laser with a π phase-shifted fiber Bragg grating

    Wang, Weitao; Song, Zhiqiang; Qi, Haifeng; Zhang, Xiaolei; Ni, Jiasheng; Guo, Jian; Wang, Chang; Peng, Gangding


    A single-longitudinal-mode fiber laser is presented, which is composed of a ring cavity laser and a π phase-shifted fiber Bragg grating. The ring cavity structure can reduce the spatial hole burning, but the mode hopping and competition are still existing due to the long fiber ring cavity length. The π phase-shifted fiber Bragg grating has very narrow transmittance spectrum width as a band-pass filter. Combined with a wavelength-matching fiber Bragg grating, it is able to efficiently suppress the mode hopping and competition in the ring cavity. The single longitudinal mode lasing is verified using a scanning F-P interferometer. Its frequency noise is measured by the self-homodyne technology with a 3×3 optical fiber coupler. The calculated linewidth from the frequency noise is about 21 kHz when the measurement time is 0.2 s.

  6. Phase-shifted reflective coherent gradient sensor for measuring Young's modulus and Poisson's ratio of polished alloys

    Ma, Kang; Xie, Huimin; Fan, Bozhao


    In this study, the Young's modulus and Poisson's ratio of Ni-Cr Alloy are measured using phase-shifted reflective coherent gradient sensing (CGS) method. Three-point bending experiment is applied to obtain the Young's modulus by measuring the specimen out-of-plane displacement slopes. Bending experiment of a circular plate with fixed edges loaded by a centric concentrated force is applied to obtain the specimen bending stiffness. The Poisson's ratio is then solved by substituting the bending stiffness into Young's modulus. The results show that the phase-shifted reflective CGS method is valid for measuring Young's modulus and Poisson's ratio of metals and alloys. In addition, the reflective specimen surfaces are obtained with precision finishing operations and the polishing parameters are optimized for CGS measurement. This method is more effective than the reflecting film transfer method, which is widely used in previous studies.

  7. Interleaved Boost-Half-Bridge Dual–Input DC-DC Converter with a PWM plus Phase-Shift Control for Fuel Cell Applications

    Zhang, Zhe; Andersen, Michael A. E.


    This paper presents an isolated dual-input DC-DC converter with a PWM plus phase-shift control for fuel cell hybrid energy systems. The power switches are controlled by phase shifted PWM signals with a variable duty cycle, and thus the two input voltages as well as the output voltage can...

  8. Enhancement of butanol production in Clostridium acetobutylicum SE25 through accelerating phase shift by different phases pH regulation from cassava flour.

    Li, Han-guang; Zhang, Qing-hua; Yu, Xiao-bin; Wei, Luo; Wang, Qiang


    A prominent delay with 12h was encountered in the phase shift from acidogenesis to solventogenesis in butanol production when the substrate-glucose was replaced by cassava flour. To solve this problem, different phase of pH regulation strategies were performed to shorten this delay time. With this effort, the phase shift occurred smoothly and the fermentation time was shortened. Under the optimal conditions, 16.24g/L butanol and 72h fermentation time were achieved, which were 25.3% higher and 14.3% shorter than those in the case of without pH regulation. Additionally, the effect of CaCO3 on "acid crash" and butanol production was also investigated. It was found that organic acids reassimilation would be of benefit to enhance butanol production. These results indicated that the simple but effective approach for acceleration of phase shift is a promising technique for shortening the fermentation time and improvement of butanol production. Copyright © 2015 Elsevier Ltd. All rights reserved.


    KhalidH.Sayhood; WuLenan


    The multilevel modulation techniques of M-Differential Amplitude Phase Shift Keying(DAPSK)have been proposed in combination with Turbo code scheme for digital radio broad-casting bands below 30 MHz radio channel.Comparison of this modulation method with channel coding in an Additive White Gaussian Noise(AWGN)and mulit-path fading channels has been presented.The analysis provides an iterative decoding of the Turbo code.


    Khalid H. Sayhood; Wu Lenan


    The multilevel modulation techniques of M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.

  11. Nonlinear phase shifts of modulated light waves with slow and superluminal group delay in stimulated Brillouin scattering.

    Arditi, Tal; Granot, Er'el; Sternklar, Shmuel


    Brillouin amplification with counterpropagating modulated pump and Stokes light leads to nonlinear modulation-phase shifts of the interacting intensity waves. This is due to a partial transformation of the nonmodulated light component at the input into modulated light at the output as a result of a mixing process with the counterpropagating modulated component of the pump and results in an advance or delay of the input modulation. This occurs for interactions over less than half of a modulation wavelength. Milliwatts of power in a kilometer of standard single-mode fiber give significant tunability of the modulation phase.

  12. Performance of Coded Offset Quadrature Phase-Shift Keying (OQPSK) and MIL-STD Shaped OQPSK (SOQPSK) with Iterative Decoding

    Li, L.; Simon, M. K.


    We show that, similar to the trellis-coded modulation representation of MIL-STD shaped offset quadrature phase-shift keying (SOQPSK), offset quadrature phase-shift keying (OQPSK) can be decomposed into a "degraded" trellis encoder and a memoryless mapper. Based on the representations of OQPSK and MIL-STD SOQPSK as trellis-coded modulations, we investigate the potential coding gains achievable from the application of simple outer codes to form a concatenated coding structure with iterative decoding. For MIL-STD SOQPSK, we describe the optimum receiver corresponding to its trellis-coded modulation form and then propose a simplified receiver. The bit-error-rate (BER) performances of both receivers for uncoded and coded MIL-STD SOQPSK are simulated and compared to those of OQPSK and Feher-patented quadrature phase-shift keying (FQPSK). The asymptotic BER performance of MIL-STD SOQPSK also is analyzed and compared to that of OQPSK and FQPSK. Simulation results show that, compared to their uncoded systems, both OQPSK and MIL-STD SOQPSK obtain significant coding gains by applying iterative decoding to either the parallel concatenated coding scheme or the serial one, even when very simple outer codes are used.

  13. NMR experimental realization of seven-qubit D-J algorithm and controlled phase-shift gates with improved precision


    In this study, we report the experimental reali-zation of seven-qubit Deutsch-Jozsa (D-J) algorithm and controlled phase-shift gates with improved precision using liquid state nuclear magnetic resonance (NMR). The experimental results have shown that transformations Uf in the seven-qubit D-J algorithm have been implemented with different pulse sequences, and whether f is constant or balanced is determined by using only a single function call (Uf). Furthermore, we propose an experimental method to measure and correct the error in the controlled phase-shift gate that is simple and feasible in experiments, and can have precise phase shifts. These may offer the possibility of surmounting the difficulties of low signal-to-noise ratio(SNR) in multi-qubit NMR quantum computers, more complicated experimental techniques, and the increase of gate errors due to using a large number of imperfect selec-tive pulses. These are also applied to more complicated quantum algorithms with more qubits, such as quantum Fourier transformation and Shor's algorithm.

  14. Determination of the misalignment error of a compound zero-order waveplate using the spectroscopic phase shifting method

    Zheng, Quan; Han, Zhigang; Chen, Lei


    The spectroscopic phase shifting method was proposed to determine the misalignment error of a compound zero-order waveplate. The waveplate, which is composed of two separate multi-order quartz waveplates, was measured by a polarizer-waveplate-analyser setup with a spectrometer as the detector. The theoretical relationship between the misalignment error and the azimuth of the polarized light that emerged from the waveplate was studied by comparing two forms of the Jones matrix of the waveplate. Four spectra were obtained to determine the wavelength-dependent azimuth using a phase shifting algorithm when the waveplate was rotated to four detection angles. The misalignment error was ultimately solved from the wavelength-dependent azimuth by the Levenberg-Marquardt method. Experiments were conducted at six misalignment angles. The measured results of the misalignment angle agree well with their nominal values, indicating that the spectroscopic phase shifting method can be a reliable way to measure the misalignment error of a compound zero-order waveplate.

  15. Thermographic laser Doppler velocimetry using the phase-shifted luminescence of BAM:Eu(2+) phosphor particles for thermometry.

    Ojo, Anthony O; Fond, Benoit; Abram, Christopher; Van Wachem, Berend G M; Heyes, Andrew L; Beyrau, Frank


    Simultaneous point measurements of gas velocity and temperature were recently demonstrated using thermographic phosphors as tracer particles. There, continuous wave (CW) excitation was used and the spectral shift of the luminescence was detected with a two-colour intensity ratio method to determine the gas temperature. The conventional laser Doppler velocimetry (LDV) technique was employed for velocimetry. In this paper, an alternative approach to the gas temperature measurements is presented, which is instead based on the temperature-dependence of the luminescence lifetime. The phase-shift between the luminescence signal and time-modulated excitation light is evaluated for single BaMgAl10O17:Eu(2+) phosphor particles as they cross the probe volume. Luminescence lifetimes evaluated in the time domain and frequency domain indicate that in these experiments, interferences from in-phase signals such as stray excitation laser light are negligible. The dependence of the phase-shift on flow temperature is characterised. In the temperature sensitive range above 700 K, precise gas temperature measurements can be obtained (8.6 K at 840 K) with this approach.

  16. Yeast extract promotes phase shift of bio-butanol fermentation by Clostridium acetobutylicum ATCC824 using cassava as substrate.

    Li, Xin; Li, Zhigang; Zheng, Junping; Shi, Zhongping; Li, Le


    When fermenting on cassava (15-25%, w/v) with Clostridium acetobutylicum ATCC824, a severe delay (18-40 h) was observed in the phase shift from acidogenesis to solventogenesis, compared to the cases of fermenting on corn. By adding yeast extract (2.5 g/L-broth) into cassava meal medium when the delay appeared, the phase shift was triggered and fermentation performances were consequently improved. Total butanol concentrations/butanol productivities, compared to those with cassava substrate alone, increased 15%/80% in traditional fermentation while 86%/79% in extractive fermentation using oleyl alcohol as the extractant, and reached the equivalent levels of those using corn substrate. Analysis of genetic transcriptional levels and measurements of free amino acids in the broth demonstrated that timely and adequate addition of yeast extract could promote phase shift by increasing transcriptional level of ctfAB to 16-fold, and indirectly enhance butanol synthesis through accelerating the accumulation of histidine and aspartic acid families. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Optical DC overlay measurement in the 2nd level process of 65 nm alternating phase shift mask

    Ma, Jian; Han, Ke; Lee, Kyung; Korobko, Yulia; Silva, Mary; Chavez, Joas; Irvine, Brian; Henrichs, Sven; Chakravorty, Kishore; Olshausen, Robert; Chandramouli, Mahesh; Mammen, Bobby; Padmanaban, Ramaswamy


    Alternating phase shift mask (APSM) techniques help bridge the significant gap between the lithography wavelength and the patterning of minimum features, specifically, the poly line of 35 nm gate length (1x) in Intel's 65 nm technology. One of key steps in making APSM mask is to pattern to within the design tolerances the 2nd level resist so that the zero-phase apertures will be protected by the resist and the pi-phase apertures will be wide open for quartz etch. The ability to align the 2nd level to the 1st level binary pattern, i.e. the 2nd level overlay capability is very important, so is the capability of measuring the overlay accurately. Poor overlay could cause so-called the encroachment after quartz etch, producing undesired quartz bumps in the pi-apertures or quartz pits in the zero-apertures. In this paper, a simple, low-cost optical setup for the 2nd level DC (develop check) overlay measurements in the high volume manufacturing (HVM) of APSM masks is presented. By removing systematic errors in overlay associated with TIS and MIS (tool-induced shift and Mask-process induced shift), it is shown that this setup is capable of supporting the measurement of DC overlay with a tolerance as small as +/- 25 nm. The outstanding issues, such as DC overlay error component analysis, DC - FC (final check) overlay correlation and the overlay linearity (periphery vs. indie), are discussed.

  18. A dual-frequency online PMP method with phase-shifting parallel to moving direction of measured object

    Peng, Kuang; Cao, Yiping; Wu, Yingchun; Chen, Cheng; Wan, Yingying


    A dual-frequency online phase measurement profilometry (PMP) method with phase-shifting parallel to moving direction of measured object is proposed in this paper. The high-frequency fringe is used for the better modulation patterns in pixel matching and it is not modified by the measured object's surface. Based on the relative positive between the moving measured object and digital light processing (DLP), the high-frequency fringe in each dual-frequency deformed pattern after pixel matching is the same. As a result, the phase can be calculated directly by the improved Stoilov algorithm without filtering out the low-frequency component containing the measured object's height information. As there is no filtering process in phase calculation, the valid information loss can be avoided so that the accuracy of the proposed method can be guaranteed. Simulations and experiments prove the method's feasibility and precision.

  19. Phase retrieval by Euclidean distance in self-calibrating generalized phase-shifting interferometry of three steps.

    Meneses-Fabian, Cruz; Lara-Cortes, Francisco Alejandro


    This paper presents a novel algorithm for phase extraction based on the computation of the Euclidean distance from a point to an ellipse. The idea consists in extracting the intensities from a data row or column in three interferograms to form points of intensity and then fitting them to an ellipse by the method of least squares. The Euclidean distance for each intensity point is computed to find a parametric phase whose value is associated to the object phase. The main advantage of the present method is to avoid the use of tangent function, reducing the error in the desired phase computation.

  20. Interferometric imaging of acoustical phenomena using high-speed polarization camera and 4-step parallel phase-shifting technique

    Ishikawa, K.; Yatabe, K.; Ikeda, Y.; Oikawa, Y.; Onuma, T.; Niwa, H.; Yoshii, M.


    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.

  1. The evolution of photospheric temperature in nova V2676 Oph toward the formation of C2 and CN during its near-maximum phase

    Kawakita, Hideyo; Arai, Akira; Fujii, Mitsugu


    The molecular formation of C2 and CN in the dust-forming classical nova V2676 Oph occurs during its near-maximum phase. We investigated the temporal evolution of the photospheric temperature of the nova as it approached molecular formation during its early phase. The effective temperature of the nova around the maximum decreased from ˜7000 K to ˜5000 K over the course of ˜3 d. The molecules formed at temperatures of conditions favorable to the molecular formation of C2 and CN in V2676 Oph.

  2. Experimental demonstration of a digital maximum likelihood based feedforward carrier recovery scheme for phase-modulated radio-over-fibre links

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin


    Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission.......Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission....

  3. Modified cavity attenuated phase shift (CAPS) method for airborne aerosol light extinction measurement

    Perim de Faria, Julia; Bundke, Ulrich; Freedman, Andrew; Petzold, Andreas


    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; 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

  4. Activation of AMPA receptors in the suprachiasmatic nucleus phase-shifts the mouse circadian clock in vivo and in vitro.

    Yasutaka Mizoro

    Full Text Available The glutamatergic neurotransmission in the suprachiasmatic nucleus (SCN plays a central role in the entrainment of the circadian rhythms to environmental light-dark cycles. Although the glutamatergic effect operating via NMDAR (N-methyl D-aspartate receptor is well elucidated, much less is known about a role of AMPAR (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor in circadian entrainment. Here we show that, in the mouse SCN, GluR2 and GluR4 AMPAR subtypes are abundantly expressed in the retinorecipient area. In vivo microinjection of AMPA in the SCN during the early subjective night phase-delays the behavioral rhythm. In the organotypic SCN slice culture, AMPA application induces phase-dependent phase-shifts of core-clock gene transcription rhythms. These data demonstrate that activation of AMPAR is capable of phase-shifting the circadian clock both in vivo and in vitro, and are consistent with the hypothesis that activation of AMPA receptors is a critical step in the transmission of photic information to the SCN.

  5. X-band phase-shifting dual-output balanced amplifier MMIC

    Bent, van der G.; Boer, de T.S.; Dijk, van R.; Graaf, van der M.W.; Hek, de A.P.; Vliet, van F.E.


    An X-band MMIC containing two 6 bit phase shifters and 1 Watt amplifiers in balanced configuration has been developed. The device has two output ports. The balance between the output powers of the two ports can be controlled via de phase shifter settings. This MMIC could be applied in systems where

  6. Enhanced topological phase and spin Hall shifts in an optical trap

    Roy, Basudev; Gupta, Subhasish Dutta; Roy, Soumyajit; Banerjee, Ayan


    The spin orbit interaction (SOI) of light has been in the focus in recent times because of fundamental consequences and potential applications in diverse systems ranging from inhomogeneous anisotropic media to engineered plasmonics and metamaterial strutures. Here we demonstrate perhaps one of the simplest means to realize SOI and the Spin Hall Shift (SHS) using a standard Gaussian TEM$_{00}$ beam in an optical trap. Our system exploits the versatility and interference generated in a stratified medium to control and manipulate SOI and transfer the resulting angular momentum to optically trapped micro-particles. We show that even such a simple setup can lead to an order of magnitude enhancement in the SHS compared to the sub-wavelength shifts typically obtained. Importantly, this leads to controlled rotation of mesoscopic particles using a fundamental Gaussian beam lacking any intrinsic angular momentum.

  7. Study on self-frequency-shift of femtosecond pulse in nonlinear dispersion medium using time-resolved cross-phase modulation method

    赵应桥; 朱鹤元; 刘建华; 孙迭篪; 李富铭


    A time-resolved cross-phase modulation method combined with a modified nonlinear Schrodinger equation is used to study the effects of nonlinear response time on the propagation of ultrashort pulses in nonlinear dispersion media. Evolution of cross-phase modulation spectrum with the different time delay between the probe pulse and pump pulse is simulated using split-step Fourier method. It is shown that both normal self-frequency-shift-red-shift and abnormal self-frequency-shift-blue-shift can occur in the frequency domain for the probe pulse, and a satisfactory theoretical interpretation is given.

  8. Positional information from oscillatory phase shifts : insights from in silico evolution

    Beaupeux, M.; François, P.


    Complex cellular decisions are based on temporal dynamics of pathways, including genetic oscillators. In development, recent works on vertebrae formation have suggested that relative phase of genetic oscillators encode positional information, including differentiation front defining vertebrae positions. Precise mechanisms for this are still unknown. Here, we use computational evolution to find gene network topologies that can compute the phase difference between oscillators and convert it into a decoder morphogen concentration. Two types of networks are discovered, based on symmetry properties of the decoder gene. So called asymmetric networks are studied, and two submodules are identified converting phase information into an amplitude variable. Those networks naturally display a ’shock’ for a well defined phase difference, that can be used to define a wavefront of differentiation. We show how implementation of these ideas reproduce experimental features of vertebrate segmentation.

  9. Three-dimensional surface imaging by multi-frequency phase shift profilometry with angle and pattern modeling for system calibration

    Wang, Zhenzhou


    In this paper, we present a 3D surface imaging system based on the well-known phase shift profilometry. To yield the analytical solutions, four shifted phases and three high carrier frequencies are used to compute the phase map and reduce the noises that are caused by the inherent optical aberrations and external influences, e.g. different illumination light sources, uneven intensity distribution and automatic image processing algorithms. To reduce the system noise, we propose to model the pattern of the calibration grid in a virtual space. To obtain the modeled pattern, we use a plane to intercept the rays that are modeled by the proposed angle modeling method. In the world coordinate system, the angle and the pattern are computed based on the calibration data. A registration method is used to transform the modeled pattern in the virtual space to the ideal pattern in the world coordinate system by computing the least squared errors between the true points in the modeled pattern and the measured points in the practical pattern. The modeled (true) points are used for re-calibration of the 3D imaging system. Experimental results showed that the measurement accuracy increases considerably and the MSE is reduced from 0.95 mm to 0.65 mm (32% average error decrease) after replacing the measured points with the true points for calibration.

  10. 248-nm DUV MoSiON embedded phase-shifting mask for 0.25 micrometer lithography

    Dao, Giang T.; Liu, Gang; Hainsey, Robert F.; Farnsworth, Jeff N.; Tokoro, Yasuo; Kawada, Susumu; Yamamoto, Tsuneo; Yoshioka, Nobuyuki; Chiba, Akira; Morimoto, Hiroaki


    Over the past five years worldwide efforts have been made to develop new techniques for optical lithography enhancement. These techniques include optical proximity correction, off-axis illumination, pupil filtering and phase-shifting mask (PSM). Among many phase-shifting mask approaches, embedded PSM (EPSM) method has drawn significant interest due to its relatively simple reticle fabrication process and excellent lithographic performance, in particular, for dark field mask layers such as contact and via holes. Perhaps, the most difficult task in materializing the EPSM technology is the creation of a thin film structure that controls both phase and transmission. In addition, this film structure must withstand severe environment of mask making process and yet can be inspected and repaired successfully using currently available tool sets. The newly developed MoSiON material meets these requirements and has demonstrated a feasibility for DUV EPSM pilot production. In this paper, characteristics of the DUV lifetime test results. Details of reticle fabrication process including e-beam writing, dry etching, inspection and repair will be presented along with chemical durability data and process capability. Finally, wafer level lithographic performance for contact holes printed on a step-and-scan and a projection aligner will be shown to demonstrate lithographic performance of 248 nm DUV EPSM for 0.25 micrometer lithography.

  11. Reconstruction of precipitation variability in the Strait of Yucatan associated with latitudinal shifts in the position of the Intertropical Convergence Zone since the Last Glacial Maximum

    Staines-Urías, Francisca; Seidenkrantz, Marit-Solveig; Fischel, Andrea; Kuijpers, Antoon


    . Notably, records of sea-surface temperature from the Caribbean indicate similar variability, with among others, colder than present conditions in the early Holocene indicating a more northerly mean ITCZ position, followed by warmer surface waters and a weaker tradewind associated with a southward displacement of the ITCZ, further illustrating the strong link between precipitation variability and oceanographic conditions in the region. After 5 cal ka BP, Ti and Fe values remain fairly stable at an intermediate level until shortly after 2 cal ka BP, when a sudden increase in Fe content is observed. At this time, a significant increase in precipitation has also been inferred from the δ18O signal of ostracods and gastropods in lake sediments from the Yucatan Peninsula and a stalagmite δ18O monsoon reconstruction from mainland Mexico. The drastic increment in Fe content also marks the beginning of a shift towards rapidly decreasing Ti and Fe values, suggesting an increasingly drier climate. Decrease inland runoff/precipitation during the late Holocene has also been observed in stalagmite and lacustrine δ18O signals from nearby locations, altogether indicating a southward displacement of the ITCZ.

  12. Spatial differentiation of Bloch surface wave beams using an on-chip phase-shifted Bragg grating

    Doskolovich, L. L.; Bezus, E. A.; Bykov, D. A.; Soifer, V. A.


    Bloch surface waves (BSWs) supported by the interfaces between a photonic crystal and a homogeneous medium are considered as a prospective information carrier in integrated photonic circuits. In the present work, we study the application of on-chip phase-shifted Bragg gratings for spatial differentiation of BSW beams. The presented simulation results demonstrate a high accuracy of the performed differentiation. It is shown that upon differentiation of a Gaussian BSW beam, a two-dimensional analogue of the Hermite-Gaussian mode is generated in reflection. The obtained results may find application in the design of new planar devices for analog optical information processing.

  13. Change of interference pattern using fundamental and second-harmonic wavelengths by phase shift of a beam

    Nakata, Yoshiki; Matsuba, Yoshiki; Murakawa, Keiichi; Miyanaga, Noriaki


    Interference pattern of two different wavelengths, forming a four-sided pyramid consisting of eight beams, is discussed. Synchronization between two wavelengths having a multiple relationship, which corresponds to mixing of fundamental and second-harmonic generation wavelengths, forms a stationary interference pattern successfully. Phase shift variation of a beam changes the basic pattern of interference. This technique can be a new scheme for multi-wavelength material processing with periodic structure and will increase the variation of meta-atoms fabricated by interfering femtosecond laser processing.

  14. Performance of Differential-Phase-Shift Keying Protocol Applying 1310 nm Up-Conversion Single-Photon Detector

    FENG Chen-Xu; JIAO Rong-Zhen; ZHANG Wen-Han


    The performance of the differential-phase-shift keying (DPSK) protocol applying a 1310nm up-conversion single-photon detector is analysed. The error rate and the communication rate as a function of distance for three quantum key distribution protocols, the Bennett-Brassard 1984, the Bennett-Brassard-Mermin 1992, and the DPSK, are presented. Then we compare the performance of these three protocols using the 1310 nm up-conversion detector. We draw the conclusion that the DPSK protocol applying the detector has significant advantage over the other two protocols. Longer transmission distance and lower error rate can be achieved.

  15. Application of coupled mode theory and coherent superposition theory to phase-shift measurements on optical microresonators

    Barnes, Jack A.; Loock, Hans-Peter


    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.

  16. Robustness of the round-robin differential-phase-shift quantum-key-distribution protocol against source flaws

    Mizutani, Akihiro; Imoto, Nobuyuki; Tamaki, Kiyoshi


    Recently, a new type of quantum key distribution, called the round-robin differential-phase-shift (RRDPS) protocol [T. Sasaki et al., Nature (London) 509, 475 (2014), 10.1038/nature13303], was proposed, where the security can be guaranteed without monitoring any statistics. In this Rapid Communication, we investigate source imperfections and side-channel attacks on the source of this protocol. We show that only three assumptions are needed for the security, and no detailed characterizations of the source or the side-channel attacks are needed. This high robustness is another striking advantage of the RRDPS protocol over other protocols.

  17. Slurry phase Fischer-Tropsch synthesis: Cobalt plus a water-gas shift catalyst

    Chanenchuk, C.A.; Yates, I.C.; Satterfield, C.N.


    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/ 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.

  18. Displacement damage in bit error ratio performance of on-off keying, pulse position modulation, differential phase shift keying, and homodyne binary phase-shift keying-based optical intersatellite communication system.

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Dong, Chen; Li, Xuan


    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.

  19. Electro-optic prism-pair setup for efficient high bandwidth isochronous CEP phase shift or group delay generation

    Gobert, Olivier; Mennerat, Gabriel; Cornaggia, Christian; Lupinski, Dominique; Perdrix, Michel; Guillaumet, Delphine; Lepetit, Fabien; Oksenhendler, Thomas; Comte, Michel


    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.

  20. 25 Gbit/s differential phase-shift-keying signal generation using directly modulated quantum-dot semiconductor optical amplifiers

    Zeghuzi, A., E-mail:; 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)


    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.

  1. Phase shift analysis of low energy $\\pi^{\\pm}p$ scattering data and a comparison with pionic hydrogen data

    Gashi, A; Oades, G C; Rasche, G; Woolcock, W S


    Using newly calculated electromagnetic corrections, we have made a phase shift analysis of experimental data on pi+/- p elastic scattering up to 100 MeV, assuming the effective hadronic interaction to be isospin invariant. The output consists of parametrised s and p-wave hadronic phases for isospin 1/2 and 3/2. It is not possible to fit the charge exchange data satisfactorily. We give values for the s-wave scattering lengths and effective ranges and for the p-wave scattering volumes. The combinations 2a_1 + a_3 and a_1 - a_3 of s-wave scattering lengths extracted from pionic hydrogen data are compared with those obtained from our analysis.

  2. The Transmission Performance of Non-zero Dispersion Shifted Fiber Communication Systems Using In-line Phase-sensitive Amplifiers


    This paper focuses on the non-zero dispersion shifted fiber optical transmission system which employs cascaded in-line Phase-sensitive Amplifiers (PSAs). By computer simulation, we have revealed that the eye-penalty of high-speed signal pulses increases with the accretion of dispersion and the transmission distance limited by Intersymbol Interference (ISI) of signals varies with the spacing and average output power of amplifiers for positive and negative fiber dispersion. The analysis shows that although PSA can compensate for both positive and negative dispersion, it is only valid for small dispersion coefficient fiber. Owing to the effect of Self-phase-modulation (SPM), the ISI limited transmission distance of positive dispersion fiber is much longer than that of negative dispersion fiber. In addition, for positive fiber dispersion, there is an optimum value of average output signal power from PSA leading to the longest ISI limited transmission distance.

  3. Liquid crystal multi-mode lenses and axicons based on electronic phase shift control.

    Kirby, Andrew K; Hands, Philip J; Love, Gordon D


    We report on the principle of operation, construction and testing of a liquid crystal lens which is controlled by distributing voltages across the control electrodes, which are in turn controlled by adjusting the phase of the applied voltages. As well as (positive and negative) defocus, then lenses can be used to control tip/tilt, astigmatism, and to create variable axicons.

  4. Modulation Instability and Phase-Shifted Fermi-Pasta-Ulam Recurrence

    Kimmoun, O; Branger, H; Li, M S; Chen, Y Y; Kharif, C; Onorato, M; Kelleher, E J R; Kibler, B; Akhmediev, N; Chabchoub, A


    Instabilities are common phenomena frequently observed in nature, sometimes leading to unexpected catastrophes and disasters in seemingly normal conditions. The simplest form of instability in a distributed system is its response to a harmonic modulation. Such instability has special names in various branches of physics and is generally known as modulation instability (MI). The MI is tightly related to Fermi-Pasta-Ulam (FPU) recurrence since breather solutions of the nonlinear Schr\\"odinger equation (NLSE) are known to accurately describe growth and decay of modulationally unstable waves in conservative systems. Here, we report theoretical, numerical and experimental evidence of the effect of dissipation on FPU cycles in a super wave tank, namely their shift in a determined order. In showing that ideal NLSE breather solutions can describe such dissipative nonlinear dynamics, our results may impact the interpretation of a wide range of new physics scenarios.

  5. Modulation Instability and Phase-Shifted Fermi-Pasta-Ulam Recurrence

    Kimmoun, O.; Hsu, H. C.; Branger, H.; Li, M. S.; Chen, Y. Y.; Kharif, C.; Onorato, M.; Kelleher, E. J. R.; Kibler, B.; Akhmediev, N.; Chabchoub, A.


    Instabilities are common phenomena frequently observed in nature, sometimes leading to unexpected catastrophes and disasters in seemingly normal conditions. One prominent form of instability in a distributed system is its response to a harmonic modulation. Such instability has special names in various branches of physics and is generally known as modulation instability (MI). The MI leads to a growth-decay cycle of unstable waves and is therefore related to Fermi-Pasta-Ulam (FPU) recurrence since breather solutions of the nonlinear Schrödinger equation (NLSE) are known to accurately describe growth and decay of modulationally unstable waves in conservative systems. Here, we report theoretical, numerical and experimental evidence of the effect of dissipation on FPU cycles in a super wave tank, namely their shift in a determined order. In showing that ideal NLSE breather solutions can describe such dissipative nonlinear dynamics, our results may impact the interpretation of a wide range of new physics scenarios.

  6. Optical encryption of gray-level image using on-axis and 2-f digital holography with two-step phase-shifting method

    Jeon, Seok Hee; Hwang, Young Gwan; Gil, Sang Keun


    In this paper we propose an encryption/decryption technique of gray-level image information using an on-axis 2-f digital holographic optical encrypting system with two-step phase-shifting method. This technique reduces the number of holograms in phase-shifting digital holography and minimizes the setup of the encryption system more than multistep phase-shifting technique. We are able to get the complete decrypted image by controlling the K-ratio which is defined as the reference beam intensity versus the object beam intensity. We remove the DC-term of the phase-shifting digital hologram to reconstruct and decrypt the original image information. Simulation results show that the proposed method can be used for encryption and decryption of a 256 gray-level image. Also, the result shows some errors of the decrypted image according to K-ratio.

  7. Eliminating the effect of phase shift between injection current and amplitude modulation in DFB-LD WMS for high-precision measurement.

    Wei, Wei; Chang, Jun; Liu, Yuanyuan; Chen, Xi; Liu, Zhaojun; Qin, Zengguang; Wang, Qiang


    Phase shift between the injection current and amplitude modulation due to the characteristics of diode lasers is discussed in this paper. Phase shift has no apparent regularity, but it has an obvious effect on measurement results, especially for high-precision measurement. A new method is proposed to suppress the influence of this phase shift. Water vapor is chosen as the target gas for experiment in this paper. A new detection system with the new method applied is presented and shows much better performance than the traditional wavelength modulation spectroscopy detection system. Phase shift fluctuation between the injection current and amplitude modulation is suppressed from 0.72 deg to 0.07 deg; accuracy is improved from 0.88 ppm to 0.16 ppm.

  8. Galaxy Secular Mass Flow Rate Determination Using the Potential-Density Phase Shift Approach: Application to Six Nearby Spiral Galaxies

    Zhang, Xiaolei


    Using the potential-density phase shift approach developed by the present authors in earlier publications, we estimate the magnitude of radial mass accretion/excretion rates across the disks of six nearby spiral galaxies having a range of Hubble types. Our goal is to examine these rates in the context of bulge building and secular morphological evolution along the Hubble sequence. Stellar surface density maps of the sample galaxies are derived from SINGS 3.6um and SDSS i-band images. Corresponding molecular and atomic gas surface densities are derived from published CO(1-0) and HI interferometric observations of the BIMA SONG, THINGS, and VIVA surveys. The mass flow rate calculations utilize a volume-type torque integral to calculate the angular momentum exchange rate between the basic state disk matter and density wave modes. The potential-density phase shift approach yields angular momentum transport rates several times higher than those estimated using the Lynden-Bell and Kalnajs (1972) approach. The curre...

  9. Catastrophic shifts in ecosystems: spatial early warnings and management procedures (Inspired in the physics of phase transitions)

    Fort, H [Complex Systems Group, Instituto de Fisica, Facultad de Ciencias, Universidad de la Republica, Igua 4225, 11400 Montevideo (Uruguay); Mazzeo, N [Depto. de EcologIa, Facultad de Ciencias, Universidad de la Republica, Igua 4225, 11400 Montevideo (Uruguay); Scheffer, M; Nes, E van, E-mail: [Wageningen Agricultural University, Aquatic Ecology and Water Quality Management Group, PO Box 47, 6700 AA Wageningen (Netherlands)


    Ecosystems are complex systems which can respond to gradual changes of their conditions by a sudden shift to a contrasting regime or alternative stable state (ASS). Predicting such critical points before they are reached is extremely difficult and providing early warnings is fundamental to design management protocols for ecosystems. Here we study different spatial versions of popular ecological models which are known to exhibit ASS. The spatial heterogeneity is introduced by a local parameter varying from cell to cell in a regular lattice. Transport of biomass among cells occurs by simple diffusion. We investigate whether different quantities from statistical mechanics -like the variance, the two-point correlation function and the patchiness-may serve as early warnings of catastrophic phase transitions between the ASS. In particular, we find that the patch-size distribution follows a power law when the system is close to the catastrophic transition. We also provide links between spatial and temporal indicators and analyze how the interplay between diffusion and spatial heterogeneity may affect the earliness of each of the observables. Finally, we comment on similarities and differences between these catastrophic shifts and paradigmatic thermodynamic phase transitions like the liquid-vapor change of state for a fluid like water.

  10. Dependence of gain and phase-shift on crystal parameters and pump intensity in unidirectional photorefractive ring resonators

    M K Maurya; T K Yadav; R A Yadav


    The steady-state amplification of light beam during two-wave mixing in photorefractive materials has been analysed in the strong nonlinear regime. The oscillation conditions for unidirectional ring resonator have been studied. The signal beam can be amplified in the presence of material absorption, provided the gain due to the beam coupling is large enough to overcome the cavity losses. Such amplification is responsible for the oscillations. The gain bandwidth is only a few Hz. In spite of such an extremely narrow bandwidth, unidirectional oscillation can be observed easily at any cavity length in ring resonators by using photorefractive crystals as the medium and this can be explained in terms of the photorefractive phase-shift. The presence of such a phase-shift allows the possibility of the non-reciprocal steady-state transfer of energy between the two light beams. Dependence of gain bandwidth on coupling constant, absorption coefficient of the material's cavity length (crystal length) and modulation ratio have also been studied.

  11. 3D phase-shifting fringe projection system on the basis of a tailored free-form mirror.

    Zwick, Susanne; Heist, Stefan; Steinkopf, Ralf; Huber, Sandra; Krause, Sylvio; Bräuer-Burchardt, Christian; Kühmstedt, Peter; Notni, Gunther


    Phase-shifting fringe projection is an effective method to perform 3D shape measurements. Conventionally, fringe projection systems utilize a digital projector that images fringes into the measurement plane. The performance of such systems is limited to the visible spectral range, as most projectors experience technical limitations in UV or IR spectral ranges. However, for certain applications these spectral ranges are of special interest. We present a wideband fringe projector that has been developed on the basis of a picture generating beamshaping mirror. This mirror generates a sinusoidal fringe pattern in the measurement plane without any additional optical elements. Phase shifting is realized without any mechanical movement by a multichip LED. As the system is based on a single mirror, it is wavelength-independent in a wide spectral range and therefore applicable in UV and IR spectral ranges. We present the design and a realized setup of this fringe projection system and the characterization of the generated intensity distribution. Experimental results of 3D shape measurements are presented.

  12. Battery Internal Temperature Estimation for LiFePO4 Battery Based on Impedance Phase Shift under Operating Conditions

    Jiangong Zhu


    Full Text Available An impedance-based temperature estimation method is investigated considering the electrochemical non-equilibrium with short-term relaxation time for facilitating the vehicular application. Generally, sufficient relaxation time is required for battery electrochemical equilibrium before the impedance measurement. A detailed experiment is performed to investigate the regularity of the battery impedance in short-term relaxation time after switch-off current excitation, which indicates that the impedance can be measured and also has systematical decrement with the relaxation time growth. Based on the discussion of impedance variation in electrochemical perspective, as well as the monotonic relationship between impedance phase shift and battery internal temperature in the electrochemical equilibrium state, an exponential equation that accounts for both measured phase shift and relaxation time is established to correct the measuring deviation caused by electrochemical non-equilibrium. Then, a multivariate linear equation coupled with ambient temperature is derived considering the temperature gradients between the active part and battery surface. Equations stated above are all identified with the embedded thermocouple experimentally. In conclusion, the temperature estimation method can be a valuable alternative for temperature monitoring during cell operating, and serve the functionality as an efficient implementation in battery thermal management system for electric vehicles (EVs and hybrid electric vehicles (HEVs.

  13. Analyzing algorithms for nonlinear and spatially nonuniform phase shifts in the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports

    Jain, N. [Pittsford Sutherland High School, NY (United States)


    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.

  14. Spread F, GPS phase fluctuations, and medium-scale traveling ionospheric disturbances over Wuhan during solar maximum

    Chen, Wei-Sheng; Lee, Chien-Chih; Chu, Fang-Dar; Su, Shin-Yi


    This study employs a digisonde and a GPS receiver at Wuhan (30.5°N, 114.4°E), China to observe spread F, GPS phase fluctuations, and medium-scale traveling ionospheric disturbances (MSTIDs) at nighttime in 2000. The MSTIDs are derived from the perturbations of total electron content (TEC). In this study, we explored the seasonal and nighttime occurrence rates as well as the one-to-one correspondences for these phenomena. The results show that, for the seasonal variations, three phenomena all are highly active in summer, which confirms that irregularities over Wuhan mainly relate to MSTIDs. Moreover, all spread F types have a minor occurrence peak in winter but none for the MSTIDs and the GPS phase fluctuations. Besides, none of large GPS phase fluctuations event had occurred during observation periods, which indicates that the strength of irregularities related to MSTIDs are weaker than that of equatorial plasma bubbles. For the nighttime variations, the frequency spread F occurs earlier than other spread F types which implies that disturbances start at the altitude near the F-region peak. For the one-to-one correspondences, the occurrence rates of each spread F type and GPS phase fluctuations are low during MSTIDs occurred. This implies that smaller scale irregularities which are observed as spread F or GPS phase fluctuations may only appear in some phase of MSTIDs.

  15. A 2x2 W-Band Reference Time-Shifted Phase-Locked Transmitter Array in 65nm CMOS Technology

    Tang, Adrian; Virbila, Gabriel; Hsiao, Frank; Wu, Hao; Murphy, David; Mehdi, Imran; Siegel, P. H.; Chang, M-C. Frank


    This paper presents a complete 2x2 phased array transmitter system operating at W-band (90-95 GHz) which employs a PLL reference time-shifting approach instead of using traditional mm-wave phase shifters. PLL reference shifting enables a phased array to be distributed over multiple chips without the need for coherent mm-wave signal distribution between chips. The proposed phased array transmitter system consumes 248 mW per array element when implemented in a 65 nm CMOS technology.

  16. A simulation study to compare the phase-shift angle radiofrequency ablation mode with bipolar and unipolar modes in creating linear lesions for atrial fibrillation ablation.

    Yan, Shengjie; Wu, Xiaomei; Wang, Weiqi


    Purpose In pulmonary veins (PVs) isolation (PVI), radiofrequency (RF) energy is often used to create a linear lesion for blocking the accessory conduction pathways around PVs. By using transient finite element analysis, this study compared the effectiveness of phase-shift mode (PsM) ablation with bipolar mode (BiM) and unipolar mode (UiM) in creating a continuous lesion and lesion depth in a 5-mm thick atrial wall. Materials and methods Computer models were developed to study the temperature distributions and lesion dimensions in atrial walls created through PsM, BiM, and UiM. Four phase-shift angles - 45°, 90°, 135°, and 180° - were considered in PsM ablation (hereafter, PsM-45°, PsM-90°, PsM-135°, and PsM-180°, respectively). Results At 60 s/30 V peak value of RF voltage, UiM and PsM-45° did not create an effective lesion, whereas BiM created a lesion of maximum depth and width approximately 1.01 and 1.62 mm, respectively. PsM-135° and PsM-180° not only created transmural lesions in 5-mm thick atrial walls but also created continuous lesions between electrodes spaced 4 mm apart; similarly, PsM-90° created a continuous lesion with a maximum depth and width of nearly 4.09 and 6.12 mm. Conclusions Compared with UiM and BiM, PsM-90°, PsM-135° and PsM-180° created continuous and larger lesions in a single ablation procedure and at 60 s/30 V peak value of RF voltage. Therefore, the proposed PsM ablation method is suitable for PVI and linear isolation at the left atrial roof for treating atrial fibrillation.


    Bosneaga V.A.


    Full Text Available The model of power three-phase three legs phase-shifting transformer with connection in delta and two additional windings is realized. Calculations and research of steady state asymmetric modes particularities of given transformer with such windings connection were fulfilled, taking into account the electromagnetic coupling of the windings, located on different legs. Calculations and analysis were made using as an example the distribution transformer with 10 kV high voltages, including the most characteristic steady state asymmetric modes that occur during different short circuits and asymmetric no load modes, associated with the occurrence of zero sequence magnetic flux. For the considered modes vector diagrams for currents and voltages, as well as for the relative values of magnetic fluxes in legs were constructed, which in ensemble give clear idea about their particularities.

  18. Monitoring of freezing dynamics in trees: a simple phase shift causes complexity.

    Charrier, Guillaume; Nolf, Markus; Leitinger, Georg; Charra-Vaskou, Katline; Losso, Adriano; Tappeiner, Ulrike; Ameglio, Thierry; Mayr, Stefan


    During winter, trees have to cope with harsh conditions, including extreme freeze-thaw stress. The present study focused on ice nucleation and propagation, related water shifts and xylem cavitation as well as cell damage, and was based on in situ monitoring of xylem (thermocouples) and surface temperatures (infrared imaging), ultrasonic emissions and dendrometer analysis. Field experiments during late winter on Picea abies growing at the alpine timberline revealed three distinct freezing patterns: (i) from the top of the tree towards the base, (ii) from thin branches towards the main stem's top and base, and (iii) from the base towards the top. Infrared imaging showed freezing within branches from their base towards distal parts. Such complex freezing causes dynamic and heterogeneous patterns in water potential and probably in cavitation. This study highlights the interaction between environmental conditions upon freezing and thawing and demonstrates the enormous complexity of freezing processes in trees. Diameter shrinkage, which indicated water fluxes within the stem, and acoustic emission analysis, which indicated cavitation events near the ice front upon freezing, were both related to minimum temperature, and upon thawing, related to vapor pressure deficit and soil temperature. These complex patterns, emphasizing the common mechanisms between frost and drought stress, shed new lights on understanding winter tree physiology.

  19. On detector linearity and precision of beam shift detection for quantitative differential phase contrast applications.

    Zweck, Josef; Schwarzhuber, Felix; Wild, Johannes; Galioit, Vincent


    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.

  20. Simultaneous extraction of phase and phase shift from two interferograms using Lissajous figure and ellipse fitting technology with Hilbert-Huang prefiltering

    Liu, Fengwei; Wang, Jing; Wu, Yongqian; Wu, Fan; Trusiak, Maciej; Patorski, Krzysztof; Wan, Yongjian; Chen, Qiang; Hou, Xi


    This paper presents a novel method to extract the phase shift and phase distribution from two interferograms simultaneously. By employing Hilbert-Huang transform based prefiltering, the background intensities and modulation amplitudes of the two interferograms are suppressed and normalized respectively. With the addition and subtraction operation of the two prefiltered interferograms, two parametric equations are achieved which can be regarded as the complex harmonic motion of the Lissajous figure. The phase of the Lissajous figure can be directly demodulated by the ellipse fitting algorithm. Apart from the advantages of other well-known two-step phase demodulation algorithms, i.e., high accuracy and efficiency of the Gram-Schmidt orthonormalization (GS) method and the less stringent requirement concerning the fringe number in the extreme value of interference (EVI) method, proposed Lissajous figure and ellipse fitting (LEF) approach has another bonus related to its robustness to the fluctuations of the fringe patterns noise, background intensity and modulation amplitude. Simulations demonstrate the outstanding performance of the proposed method, and experiments further corroborate its effectiveness.