Science.gov

Sample records for additional phase shift

  1. Additive-Subtractive Two-Wavelength ESPI Contouring by Using a Synthetic Wavelength Phase Shift.

    PubMed

    Hack, E; Frei, B; Kästle, R; Sennhauser, U

    1998-05-01

    The addition correlation of two speckle fields by simultaneousillumination at different wavelengths is used for object contouring ina Twyman-Green-type interferometer. Fringe visibility is enhancedwhen the stochastic speckle background intensity obtained from areference plane modulation is subtracted. We calculate the contourphase map by using a phase-shift algorithm in the syntheticwavelength. A comparison with a sequential illumination, phasedifference method based on a laser wavelength phase shift isgiven. The test setup does not need to be stable on aninterferometric scale, and therefore a method is provided that lendsitself to applications in noisy environments.

  2. Phase-shifting interferometry corrupted by white and non-white additive noise.

    PubMed

    Servin, M; Quiroga, J A; Estrada, J C

    2011-05-09

    The standard tool to estimate the phase of a sequence of phase-shifted interferograms is the Phase Shifting Algorithm (PSA). The performance of PSAs to a sequence of interferograms corrupted by non-white additive noise has not been reported before. In this paper we use the Frequency Transfer Function (FTF) of a PSA to generalize previous white additive noise analysis to non-white additive noisy interferograms. That is, we find the ensemble average and the variance of the estimated phase in a general PSA when interferograms corrupted by non-white additive noise are available. Moreover, for the special case of additive white-noise, and using the Parseval's theorem, we show (for the first time in the PSA literature) a useful relationship of the PSA's noise robustness; in terms of its FTF spectrum, and in terms of its coefficients. In other words, we find the PSA's estimated phase variance, in the spectral space as well as in the PSA's coefficients space.

  3. Instantaneous phase shifting deflectometry.

    PubMed

    Trumper, Isaac; Choi, Heejoo; Kim, Dae Wook

    2016-11-28

    An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone ® 6. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using Fourier techniques. Along with experimental data showing the capabilities of the instantaneous deflectometry system, a quantitative comparison with the Fourier transform profilometry method, which is a distinct phase measuring method from the phase shifting approach, is presented. Sources of error, nonlinear color-multiplexing induced error correction, and hardware limitations are discussed.

  4. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

  5. Phase shifting interferometer

    DOEpatents

    Sommargren, Gary E.

    1999-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  6. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  7. Phase shifting interferometer

    DOEpatents

    Sommargren, G.E.

    1999-08-03

    An interferometer is disclosed which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 11 figs.

  8. Upward shift of the vortex solid phase in high-temperature-superconducting wires through high density nanoparticle addition

    DOE PAGES

    Miura, Masashi; Maiorov, Boris; Balakirev, Fedor F.; ...

    2016-02-08

    Here, we show a simple and effective way to improve the vortex irreversibility line up to very high magnetic fields (60T) by increasing the density of second phase BaZrO3 nanoparticles. (Y0.77,Gd0.23)Ba2Cu3Oy films were grown on metal substrates with different concentration of BaZrO3 nanoparticles by the metal organic deposition method. We find that upon increase of the BaZrO3 concentration, the nanoparticle size remains constant but the twin-boundary density increases. Up to the highest nanoparticle concentration (n ~ 1.3 × 1022/m3), the irreversibility field (Hirr) continues to increase with no sign of saturation up to 60 T, although the vortices vastly outnumbermore » pinning centers. We find extremely high Hirr, namely Hirr = 30 T (H||45°) and 24 T (H||c) at 65 K and 58 T (H||45°) and 45 T (H||c) at 50K. The difference in pinning landscape shifts the vortex solid-liquid transition upwards, increasing the vortex region useful for power applications, while keeping the upper critical field, critical temperature and electronic mass anisotropy unchanged.« less

  9. Upward shift of the vortex solid phase in high-temperature-superconducting wires through high density nanoparticle addition

    SciTech Connect

    Miura, Masashi; Maiorov, Boris; Balakirev, Fedor F.; Kato, Takeharu; Sato, Michio; Takagi, Yuji; Izumi, Teruo; Civale, Leonardo

    2016-02-08

    Here, we show a simple and effective way to improve the vortex irreversibility line up to very high magnetic fields (60T) by increasing the density of second phase BaZrO3 nanoparticles. (Y0.77,Gd0.23)Ba2Cu3Oy films were grown on metal substrates with different concentration of BaZrO3 nanoparticles by the metal organic deposition method. We find that upon increase of the BaZrO3 concentration, the nanoparticle size remains constant but the twin-boundary density increases. Up to the highest nanoparticle concentration (n ~ 1.3 × 1022/m3), the irreversibility field (Hirr) continues to increase with no sign of saturation up to 60 T, although the vortices vastly outnumber pinning centers. We find extremely high Hirr, namely Hirr = 30 T (H||45°) and 24 T (H||c) at 65 K and 58 T (H||45°) and 45 T (H||c) at 50K. The difference in pinning landscape shifts the vortex solid-liquid transition upwards, increasing the vortex region useful for power applications, while keeping the upper critical field, critical temperature and electronic mass anisotropy unchanged.

  10. Upward shift of the vortex solid phase in high-temperature-superconducting wires through high density nanoparticle addition

    NASA Astrophysics Data System (ADS)

    Miura, Masashi; Maiorov, Boris; Balakirev, Fedor F.; Kato, Takeharu; Sato, Michio; Takagi, Yuji; Izumi, Teruo; Civale, Leonardo

    2016-02-01

    We show a simple and effective way to improve the vortex irreversibility line up to very high magnetic fields (60T) by increasing the density of second phase BaZrO3 nanoparticles. (Y0.77,Gd0.23)Ba2Cu3Oy films were grown on metal substrates with different concentration of BaZrO3 nanoparticles by the metal organic deposition method. We find that upon increase of the BaZrO3 concentration, the nanoparticle size remains constant but the twin-boundary density increases. Up to the highest nanoparticle concentration (n ~ 1.3 × 1022/m3), the irreversibility field (Hirr) continues to increase with no sign of saturation up to 60 T, although the vortices vastly outnumber pinning centers. We find extremely high Hirr, namely Hirr = 30 T (H||45°) and 24 T (H||c) at 65 K and 58 T (H||45°) and 45 T (H||c) at 50K. The difference in pinning landscape shifts the vortex solid-liquid transition upwards, increasing the vortex region useful for power applications, while keeping the upper critical field, critical temperature and electronic mass anisotropy unchanged.

  11. Upward shift of the vortex solid phase in high-temperature-superconducting wires through high density nanoparticle addition

    PubMed Central

    Miura, Masashi; Maiorov, Boris; Balakirev, Fedor F.; Kato, Takeharu; Sato, Michio; Takagi, Yuji; Izumi, Teruo; Civale, Leonardo

    2016-01-01

    We show a simple and effective way to improve the vortex irreversibility line up to very high magnetic fields (60T) by increasing the density of second phase BaZrO3 nanoparticles. (Y0.77,Gd0.23)Ba2Cu3Oy films were grown on metal substrates with different concentration of BaZrO3 nanoparticles by the metal organic deposition method. We find that upon increase of the BaZrO3 concentration, the nanoparticle size remains constant but the twin-boundary density increases. Up to the highest nanoparticle concentration (n ~ 1.3 × 1022/m3), the irreversibility field (Hirr) continues to increase with no sign of saturation up to 60 T, although the vortices vastly outnumber pinning centers. We find extremely high Hirr, namely Hirr = 30 T (H||45°) and 24 T (H||c) at 65 K and 58 T (H||45°) and 45 T (H||c) at 50K. The difference in pinning landscape shifts the vortex solid-liquid transition upwards, increasing the vortex region useful for power applications, while keeping the upper critical field, critical temperature and electronic mass anisotropy unchanged. PMID:26853703

  12. Phase-shift coherence holography.

    PubMed

    Naik, Dinesh N; Ezawa, Takahiro; Miyamoto, Yoko; Takeda, Mitsuo

    2010-05-15

    We propose and experimentally demonstrate a new reconstruction scheme for coherence holography using computer-generated phase-shift coherence holograms. A 3D object encoded into the spatial coherence function is reconstructed directly from a set of incoherently illuminated computer-generated holograms with numerically introduced phase shifts. Although a rotating ground glass is used to introduce spatially incoherent illumination, the phase-shifting portion of the system is simple and free from mechanically moving components.

  13. Phase-shifting Gabor holography.

    PubMed

    Micó, Vicente; García, Javier; Zalevsky, Zeev; Javidi, Bahram

    2009-05-15

    We present a modified Gabor-like setup able to recover the complex amplitude distribution of the object wavefront from a set of inline recorded holograms. The proposed configuration is characterized by the insertion of a condenser lens and a spatial light modulator (SLM) into the classical Gabor configuration. The phase shift is introduced by the SLM that modulates the central spot (dc term) in an intermediate plane, without an additional reference beam. Experimental results validate the proposed method and produce superior results to the Gabor method.

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

    PubMed

    Liu, Fengwei; Wu, Yongqian; Wu, Fan

    2015-07-27

    We propose a novel phase shifting interferometry from two normalized interferograms with random tilt phase-shift. The determination of tilt phase-shift is performed by extracting the tilted phase-shift plane from the phase difference of two normalized interferograms, and with the calculated tilt phase-shift value the phase distribution can be retrieved from the two normalized frames. By analyzing the distribution of phase difference and utilizing special points fitting method, the tilted phase-shift plane is extracted in three different cases, which relate to different magnitudes of tilts. Proposed method has been applied to simulations and experiments successfully and the satisfactory results manifest that proposed method is of high accuracy and high speed compared with the three step iterative method. Additionally, both open and closed fringe can be analyzed with proposed method. What's more, it cannot only eliminate the small tilt-shift error caused by slight vibration in phase-shifting interferometry, but also detect the large tilt phase-shift in phase-tilting interferometry. Thus, it will relaxes the requirements on the accuracy of phase shifter, and the costly phase shifter may even be useless by applying proposed method in high amplitude vibrated circumstance to achieve high-precision analysis.

  15. Geometric phase shifting digital holography.

    PubMed

    Jackin, Boaz Jessie; Narayanamurthy, C S; Yatagai, Toyohiko

    2016-06-01

    A new phase shifting digital holographic technique using a purely geometric phase in Michelson interferometric geometry is proposed. The geometric phase in the system does not depend upon either optical path length or wavelength, unlike dynamic phase. The amount of geometric phase generated is controllable through a rotating wave plate. The new approach has unique features and major advantages in holographic measurement of transparent and reflecting three-dimensional (3D) objects. Experimental results on surface shape measurement and imaging of 3D objects are presented using the proposed method.

  16. Nonphotic phase shifting in hamster clock mutants.

    PubMed

    Mrosovsky, N; Salmon, P A; Menaker, M; Ralph, M R

    1992-01-01

    Golden hamsters with the tau mutation were kept in the dark and induced to become active through confinement to a novel running wheel for 3 hr. The response of the mutants to this nonphotic phase-shifting stimulus differed from that of wild-type hamsters. The mutants showed larger phase shifts, and their phase response curves differed in shape, with an advance portion at about circadian time 24, a phase at which wild types show delays. The results establish that the tau mutation, in addition to its already known effects, alters the response of the circadian system to nonphotic events.

  17. Doppler phase shifting using dual, switched phase shifting devices

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor)

    2002-01-01

    A system of inducing a phase shift using moving reflector elements. The moving reflectors can be moving mirrors or an acousto-optical filter. The moving reflectors oscillate i.e. the move first in a first direction and then in a second direction. Two different reflectors are used so that the light can be switched between the reflectors. During a first portion of the cycle the light is coupled to the first modulator which moves the reflector in the first direction. The second modulator is out of phase with the first modulator, and the light is switched to that second modulator during a second portion of the cycle. The second modulator is also moving in the first direction when the light is applied thereto. In this way, the light obtains a constant direction Doppler shift.

  18. Statistical properties of phase-shift algorithms

    NASA Astrophysics Data System (ADS)

    Rathjen, C.

    1995-09-01

    Statistical properties of phase-shift algorithms are investigated for the case of additive Gaussian intensity noise. Based on a bivariate normal distribution, a generally valid probability-density function for the random phase error is derived. This new description of the random phase error shows properties that cannot be obtained through Gaussian error propagation. The assumption of a normally distributed phase error is compared with the derived probability-density function. For small signal-to-noise ratios the assumption of a normally distributed phase error is not valid. Additionally, it is shown that some advanced systematic-error-compensating algorithms have a disadvantageous effect on the random phase error. error, systematic error, additive Gaussian noise, phase-measuring interferometry.

  19. Generalized phase-shifting color digital holography

    NASA Astrophysics Data System (ADS)

    Nomura, Takanori; Kawakami, Takaaki; Shinomura, Kazuma

    2016-06-01

    Two methods to apply the generalized phase-shifting digital holography to color digital holography are proposed. One is wave-splitting generalized phase-shifting color digital holography. This is realized by using a color Bayer camera. Another is multiple exposure generalized phase-shifting color digital holography. This is realized by the wavelength-dependent phase-shifting devices. Experimental results for both generalized phase-shifting color digital holography are presented to confirm the proposed methods.

  20. Multicolor Holography With Phase Shifting

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1996-01-01

    Prototype apparatus constructed to test feasibility of two-color holographic interferometric scheme in which data for reconstructing holographic wavefront obtained with help of phase-shifting technique. Provides two sets of data needed to solve equations for effects of temperature and concentration. Concept extended to holography at three or more wavelengths to measure three or more phenomena associated with significant variations in index of refraction

  1. EUVL alternating phase shift mask

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Yang; Myers, Alan; Shroff, Yashesh; Chandhok, Manish; Zhang, Guojing; Gullikson, Eric; Salmassi, Farhad

    2011-04-01

    Extreme ultra-violet Lithography (EUVL) alternating phase shift mask (APSM) or other optical enhancement techniques are likely needed for 16nm (half pitch) technology generation and beyond. One possible option is the combination of EUVL and APSM. The fabrication of EUVL APSM is more difficult than either the fabrication of an EUVL binary mask or a conventional optical APSM mask. In the case of EUVL APSM, the phase difference in the two regions (0 and 180-degree phase regions) is created by a phase step in the substrate prior to the multilayer (ML) coating. The step height that induces 180-degree phase mismatch in the ML is determined by [λ/(4cosθ)](2m+1), where m are integers (0, 1, 2,...). In this experiment, we targeted for a step height with m=1. The same mask design also contains the standard binary structures so that the comparison between the EUVL APSM and the EUVL binary mask can be performed under the same illumination and wafer process conditions. The EUVL APSM mask was exposed using Nikon's EUV1 scanner in Kumagaya Japan. The wafer level results showed higher dense line resolution for EUVL APSM as compared to that of EUVL binary mask. APSM also showed improved line width roughness (LWR) and depth of focus (DoF) as compared to the best EUVL binary results obtained with C-dipole off-axis illumination (OAI). The wafer CD resolution improvement obtained by APSM in this experiment is partially limited by the resist resolution and the mask phase edge spread during ML deposition. We believe that wafer CD resolution and can further be improved with imaging imbalance compensation mask design and improvements in resist resolution and the phase generation portion of the mask fabrication process. In this paper, we will discuss in detail the mask fabrication process, wafer level data analysis, and our understanding of EUVL APSM related issues.

  2. Rapid phase shifts extraction and phase retrieval by performing 1-norm operation for phase-shifting interferograms

    NASA Astrophysics Data System (ADS)

    Zhou, Yunfei; Shou, Junwei; Zhong, Liyun; Li, Jiaosheng; Liu, Shengde; Tian, Jindong; Lu, Xiaoxu

    2017-01-01

    By performing 1-norm operation for phase-shifting interferograms, a rapid phase shift extraction and phase retrieval algorithm is proposed in random phase-shifting interferometry (PSI). First, by performing the 1-norm operation for a sequence of phase-shifting interferograms, we can construct a group of new interference patterns, possessing less data information but the same phase shifts relative to the original interferograms. Second, based on the least-square iteration (LSI) algorithm, accurate phase shifts can be extracted from these construct interference patterns. Finally, the measured phase can be achieved from the above extracted phase-shifts using the LSI algorithm. The obtained results show that as long as the pixel number of the constructed interference pattern through performing 1-norm operation is about 0.4% pixel number of the original interferogram, the proposed algorithm can achieve accurate phase shifts and be measured. Compared with other iteration algorithms of PSI, in addition to maintaining the advantage of high accuracy, the proposed algorithm reveals outstanding performance in processing speed.

  3. In-line phase shift tomosynthesis

    SciTech Connect

    Hammonds, Jeffrey C.; Price, Ronald R.; Pickens, David R.; Donnelly, Edwin F.

    2013-08-15

    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.

  4. Zero difference algorithm for phase shift extraction in blind phase-shifting holography.

    PubMed

    Guo, Cheng-Shan; Sha, Bei; Xie, Yi-Yan; Zhang, Xiu-Jiang

    2014-02-15

    A simple noniterative algorithm for retrieval of the unknown phase shifts in phase-shifting holography is proposed. In this algorithm, the phase shift value between two phase-shifting holograms can be calculated through a simple analytical formula that is derived according to the fact that there exist some points whose intensity difference between two phase-shifting holograms is equal to zero. Both the simulated and experimental results demonstrated the feasibility of this so-called zero difference algorithm over a wide range of phase shifts.

  5. Phase-shift interferometry with a digital photocamera

    NASA Astrophysics Data System (ADS)

    Vannoni, Maurizio; Trivi, Marcelo; Molesini, Giuseppe

    2007-01-01

    A phase-shift interferometry experiment is proposed, working on a Twyman-Green optical configuration with additional polarization components. A guideline is provided to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses.

  6. Quantum walks with random phase shifts

    SciTech Connect

    Kosik, Jozef; Buzek, Vladimir; Hillery, Mark

    2006-08-15

    We investigate quantum walks in multiple dimensions with different quantum coins. We augment the model by assuming that at each step the amplitudes of the coin state are multiplied by random phases. This model enables us to study in detail the role of decoherence in quantum walks and to investigate the quantum-to-classical transition. We also provide classical analog of the quantum random walks studied. Interestingly enough, it turns out that the classical counterparts of some quantum random walks are classical random walks with a memory and biased coin. In addition random phase shifts 'simplify' the dynamics (the cross-interference terms of different paths vanish on average) and enable us to give a compact formula for the dispersion of such walks.

  7. Optical vortex phase-shifting digital holography.

    PubMed

    Guo, Cheng-Shan; Cheng, Xin; Ren, Xiu-Yun; Ding, Jian-Ping; Wang, Hui-Tian

    2004-10-18

    We report a new optical vortex phase-shifting method for digital holography, in which an optical vortex mode is taken as the reference beam for holographic recording, and the required phase shifts are directly generated by rotating the vortex mode. In digital reconstruction, the complex amplitude of the object wave can be retrieved by use of the conventional phase shifting algorithm on condition that the digital illumination beam is replaced by an vortex beam with the same topological charge as the reference used. Both the theoretical analysis and experimental results demonstrate the feasibility of this approach.

  8. An advanced phase retrieval algorithm in N-step phase-shifting interferometry with unknown phase shifts

    PubMed Central

    Li, Jiaosheng; Zhong, Liyun; Liu, Shengde; Zhou, Yunfei; Xu, Jie; Tian, Jindong; Lu, Xiaoxu

    2017-01-01

    In phase-shifting interferometry with unknown phase shifts, a normalization and orthogonalization phase-shifting algorithm (NOPSA) is proposed to achieve phase retrieval. The background of interferogram is eliminated through using the orthogonality of complex sinusoidal function; and the influence of phase shifts deviation on accuracy of phase retrieval is avoided through both normalization and orthogonalization processing. Compared with the current algorithms with unknown phase shifts, the proposed algorithm reveals significantly faster computation speed, higher accuracy, better stability and non-sensitivity of phase shifts deviation. PMID:28290494

  9. An advanced phase retrieval algorithm in N-step phase-shifting interferometry with unknown phase shifts

    NASA Astrophysics Data System (ADS)

    Li, Jiaosheng; Zhong, Liyun; Liu, Shengde; Zhou, Yunfei; Xu, Jie; Tian, Jindong; Lu, Xiaoxu

    2017-03-01

    In phase-shifting interferometry with unknown phase shifts, a normalization and orthogonalization phase-shifting algorithm (NOPSA) is proposed to achieve phase retrieval. The background of interferogram is eliminated through using the orthogonality of complex sinusoidal function; and the influence of phase shifts deviation on accuracy of phase retrieval is avoided through both normalization and orthogonalization processing. Compared with the current algorithms with unknown phase shifts, the proposed algorithm reveals significantly faster computation speed, higher accuracy, better stability and non-sensitivity of phase shifts deviation.

  10. Digital holography with a quadrature phase-shifting interferometer.

    PubMed

    Kiire, Tomohiro; Nakadate, Suezou; Shibuya, Masato

    2009-03-01

    An alternative method for digital holography using a quadrature phase-shifting interferometer for high-speed measurement is presented. We show that it has image quality equal to the four-bucket method. In addition, it requires fewer imaging devices. Two quadrature phase-shifting fringe patterns are acquired in each state of an object changed temporally. The phase calculation method with these four fringe patterns gives the phase distribution of the hologram. This digital phase hologram is reconstructed to yield an object image by the Fresnel transform using digital convolutions with the fast Fourier transform algorithm. Verification results of simulations and experiments are given.

  11. Data for phase angle shift with frequency

    PubMed Central

    Paul, T.; Banerjee, D.; Kargupta, K.

    2016-01-01

    Phase angle shift between the current and voltage with frequency has been reported for a single phosphoric acid fuel cell in the cell temperature from 100 °C to 160 °C and the humidifier temperature from 40 °C to 90 °C. An electrochemical workbench is employed to find the shift. The figure of phase angle shift shows a peak in high humidifier temperatures. The peak in phase angle shift directs to lower frequency side with decreasing humidifier temperature. The estimation of electrochemical reaction time is also evaluated in the humidifier temperature zone from 50 °C to 90 °C. PMID:27158655

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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.

  13. Differential phase shift of partially reflected radio waves.

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.

    1971-01-01

    The addition of phase difference measurements to differential absorption experiments is shown to be both feasible and desirable. The phase information can provide a more sensitive measurement of electron density above about 75 km. The differential phase shift is only weakly dependent on collision frequency in this range, and so an accurate collision frequency profile is not a prerequisite. The differential phase shift and differential absorption measurements taken together can provide both electron density and collision frequency data from about 70 to 90 km.

  14. Liquid crystal display for phase shifting

    NASA Astrophysics Data System (ADS)

    Villalobos-Mendoza, B.; Granados-Agustín, F. S.; Aguirre-Aguirre, D.; Cornejo-Rodríguez, A.

    2013-11-01

    This work arises based on the idea proposed by Millered et al. in 2004, where they show how to get in one shot interferograms with phase shift using a mask with micro-polarizers, in this work we pretend to obtain phase shift in localized areas of an interferogram using the properties of polarization and the pixelated configuration of a liquid crystal display (LCD) for testing optical surfaces. In this work we describes the process of characterization of a liquid crystal display CRL Opto and XGA2P01 model, which is introduced in one arm of a Twyman Green interferometer. Finally we show the experimental interferograms with phase shifts which are caused by different gray levels displayed in the LCD.

  15. Robust phase-shift estimation method for statistical generalized phase-shifting digital holography.

    PubMed

    Yoshikawa, Nobukazu; Shiratori, Takaaki; Kajihara, Kazuki

    2014-06-16

    We propose a robust phase-shift estimation method for statistical generalized phase-shifting digital holography using a slightly off-axis optical configuration. The phase randomness condition in the Fresnel diffraction field of an object can be sufficiently established by the linear phase factor of the oblique incident reference wave. Signed phase-shift values can be estimated with a statistical approach regardless of the statistical properties of the Fresnel diffraction field of the object. We present computer simulations and optical experiments to verify the proposed method.

  16. Phase-shifting structures for isolated features

    NASA Astrophysics Data System (ADS)

    Garofalo, Joseph G.; Kostelak, Robert L.; Yang, Tungsheng

    1991-07-01

    The technique for improving optical projection-system resolution by phase-shifting alternate apertures of a periodic grating was introduced in 1982. This halves the frequency content of the image passing through the optics and should therefore double the effective resolution of such patterns. Unfortunately, as feature separation increases, the efficacy of this method diminishes. Previous work applying a similar approach to isolated features involves introducing minute, non-printable, phase-shifted assist slots around the desired feature. The diffraction side-lobes of these slots constructively interfere with the center lobe of the primary aperture. The resolution enhancement afforded be this technique is limited by the printability of the assist slots. This restraint also dictates 1X-size reticle feature dimensions and the employment of high contrast imaging resists. A new approach entails significantly oversizing the desired feature and introducing a phase-shifting region around the periphery. This type of structure affords substantial focus-exposure improvements and may either be fabricated in a single-level, self-aligned scheme or by a two-level exposure with conventional e-beam tools since the phase-shifting regions are on the order of 1 micrometers (reticle dimensions). Extensive modeling of this structure for isolated contact holes and spaces explores the myriad of trade- offs involved in an optimum design. Mask-fabrication tolerances, such as phase-shift uniformity, are also investigated. It is shown that the focus-exposure window enlarges as the overall structure dimensions increase. The degree of enhancement must therefore by weighed against packing density restrictions. Also, the structure suffers, to some degree, from the effect of side-lobes. However, for a given side-lobe intensity, this technique yields enhancements superior to the assist-slot approach. As is typical of phase-shifted systems, performance is improved as the partial coherence ((sigma

  17. Higher-order phase shift reconstruction approach

    SciTech Connect

    Cong Wenxiang; Wang Ge

    2010-10-15

    Purpose: Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x-ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x-ray phase-contrast provides a new mechanism for soft tissue imaging. The x-ray phase shift of soft tissues is about a thousand times greater than the x-ray absorption over the diagnostic x-ray energy range, yielding a higher signal-to-noise ratio than the attenuation contrast counterpart. Thus, phase-contrast imaging is a promising technique to reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x-ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues. Methods: A novel phase retrieval approach is proposed to reconstruct an x-ray phase image of an object based on the paraxial Fresnel-Kirchhoff diffraction theory. A primary advantage of the authors' approach is higher-order accuracy over that with the conventional linear approximation models, relaxing the current restriction of slow phase variation. The nonlinear terms in the autocorrelation equation of the Fresnel diffraction pattern are eliminated using intensity images measured at different distances in the Fresnel diffraction region, simplifying the phase reconstruction to a linear inverse problem. Numerical experiments are performed

  18. Phase-Shifting Zernike Interferometer Wavefront Sensor

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The canonical Zernike phase-contrast technique1,2,3,4 transforms a phase object in one plane into an intensity object in the conjugate plane. This is done by applying a static pi/2 phase shift to the central core (approx. lambda/D) of the PSF which is intermediate between the input and output planes. Here we present a new architecture for this sensor. First, the optical system is simple and all reflective. Second, the phase shift in the central core of the PSF is dynamic and or arbitrary size. This common-path, all-reflective design makes it minimally sensitive to vibration, polarization and wavelength. We review the theory of operation, describe the optical system, summarize numerical simulations and sensitivities and review results from a laboratory demonstration of this novel instrument

  19. Phase-Shifting Zernike Interferometer Wavefront Sensor

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Rao, Shanti; Jensen-Clem, Rebecca M.

    2011-01-01

    The canonical Zernike phase-contrast technique 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/diameter) of the PSF which is intermediate between the input and output plane. Here we present a new architecture for this sensor. First, the optical system is simple and all reflective, and second the phase shift in the central core of the PSF is dynamic and can be made arbitrarily large. 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.

  20. The Phase Shift in the Jumping Ring

    ERIC Educational Resources Information Center

    Jeffery, Rondo N.; Amiri, Farhang

    2008-01-01

    The popular physics demonstration experiment known as Thomson's Jumping Ring (JR) has been variously explained as a simple example of Lenz's law, or as the result of a phase shift of the ring current relative to the induced emf. The failure of the first-quadrant Lenz's law explanation is shown by the time the ring takes to jump and by levitation.…

  1. Spectral phase-shift detection of surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Duliakova, M.; Hlubina, P.; Ciprian, D.

    2016-12-01

    A two-step spectral interferometric technique to detect the spectral phase shift of surface plasmon resonance (SPR) in the Kretschmann configuration is proposed and demonstrated. The technique utilizes a polarimetry setup to record two channeled spectra, one including reflection of p- and s-polarized waves from an SPR structure for air when the SPR phenomenon does not occur, and the other one for an analyte when the SPR phenomenon occurs. The channeled spectra are used to detect the SPR spectral phase shift and first, an SF10 glass prism and a gold coated SF10 slide with a chromium adhesion layer is used to measure the SPR phase shift for aqueous solutions of ethanol. In addition, the position of a sharp maximum in the spectral derivative of the SPR phase shift is measured as a function of the analyte parameter. Second, the setup with a gold coated SF10 glass prism is used to measure the SPR phase shift for the same analyte. It is revealed that the detection accuracy of the measurement of the spectral derivative of the SPR phase shift in the second setup is lower than that in the first setup. For the first case, the measurements are accompanied by theoretical modeling of the SPR responses using the material dispersion characteristics.

  2. Two-step phase-shifting SPIDER

    PubMed Central

    Zheng, Shuiqin; Cai, Yi; Pan, Xinjian; Zeng, Xuanke; Li, Jingzhen; Li, Ying; Zhu, Tianlong; Lin, Qinggang; Xu, Shixiang

    2016-01-01

    Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths. PMID:27666528

  3. Two-step phase-shifting SPIDER

    NASA Astrophysics Data System (ADS)

    Zheng, Shuiqin; Cai, Yi; Pan, Xinjian; Zeng, Xuanke; Li, Jingzhen; Li, Ying; Zhu, Tianlong; Lin, Qinggang; Xu, Shixiang

    2016-09-01

    Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths.

  4. Quadrature-Quadrature Phase Shift Keying.

    DTIC Science & Technology

    1986-09-01

    Q 2PSK for the data stream a (t) in Figure 3.1 ................................................ 27 3.3. Spectral densities of OQPSK , MSK and Q’PSK...Offset Quadrature Phase Shift Keying ( OQPSK ). Minimum Shift Keying ( vISK ), Quadrature Overlapped taised Cosine ( QOW signalling scheme, Tamed Frequency...orthogonal; hence the name %liniliur ’t Keving (AfSK) . The baseband power spectral densities S~.f) a1nd( o’,,, r QPSlK (or OQPSk . and NLSK are given by

  5. Parallel phase-shifting color digital holography using two phase shifts.

    PubMed

    Kakue, Takashi; Tahara, Tatsuki; Ito, Kenichi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2009-12-01

    We propose parallel phase-shifting color digital holography using two phase shifts. This technique enables the instantaneous acquisition of three-dimensional information of a moving color object. The interference fringe image that contains six holograms with two phase shifts for three wavelengths is recorded by a single shot exposure. Decreasing the degree of space-division multiplexing of these holograms makes it possible to suppress the degradation of the image quality owing to the aliasing caused by the multiplexing. Numerical simulation and preliminary experiments demonstrate the validity of the proposed technique; the reconstructed images of the proposed technique are clearer than those of the previously reported single-shot phase-shifting color digital holography that uses four phase steps.

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

    PubMed

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

    2016-06-01

    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.

  7. Michelson interferometer based spatial phase shift shearography.

    PubMed

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

    2013-06-10

    This paper presents a simple spatial phase shift shearography based on the Michelson interferometer. The Michelson interferometer based shearographic system has been widely utilized in industry as a practical nondestructive test tool. In the system, the Michelson interferometer is used as a shearing device to generate a shearing distance by tilting a small angle in one of the two mirrors. In fact, tilting the mirror in the Michelson interferometer also generates spatial frequency shift. Based on this feature, we introduce a simple Michelson interferometer based spatial phase shift shearography. The Fourier transform (FT) method is applied to separate the spectrum on the spatial frequency domain. The phase change due to the loading can be evaluated using a properly selected windowed inverse-FT. This system can generate a phase map of shearography by using only a single image. The effects of shearing angle, spatial resolution of couple charge device camera, and filter methods are discussed in detail. The theory and the experimental results are presented.

  8. Microstrip Antennas with Broadband Integrated Phase Shifting

    NASA Technical Reports Server (NTRS)

    Bernhard, Jennifer T.; Romanofsky, Robert R. (Technical Monitor)

    2001-01-01

    The goal of this research was to investigate the feasibility of using a spiral microstrip antenna that incorporates a thin ferroelectric layer to achieve both radiation and phase shifting. This material is placed between the conductive spiral antenna structure and the grounded substrate. Application of a DC bias between the two arms of the spiral antenna will change the effective permittivity of the radiating structure and the degree of coupling between contiguous spiral arms, therefore changing the phase of the RF signal transmitted or received by the antenna. This could eliminate the need for a separate phase shifter apart from the antenna structure. The potential benefits of such an antenna element compared to traditional phased array elements include: continuous, broadband phase shifting at the antenna, lower overall system losses, lighter, more efficient, and more compact phased arrays, and simpler control algorithms. Professor Jennifer Bernhard, graduate student Gregory Huff, and undergraduate student Brian Huang participated in this effort from March 1, 2000 to February 28, 2001. No inventions resulted from the research undertaken in this cooperative agreement.

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

    SciTech Connect

    Tellez-Quinones, Alejandro; Malacara-Doblado, Daniel

    2010-11-10

    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.

  10. Phase-shifting color digital holography.

    PubMed

    Yamaguchi, Ichirou; Matsumura, Tatsuki; Kato, Jun-Ichi

    2002-07-01

    Digital holography with a three-wavelength laser and a color CCD has been demonstrated. With the phase shifting of the reference beam, in-line holograms for three wavelengths are recorded simultaneously for derivation of the complex amplitude at each wavelength, and then the three monochromatic images are reconstructed and combined into full-color images in the computer. Laser power variation for wavelengths can be compensated for in the reconstruction process. We have compared the images reconstructed by two algorithms using a single Fourier transformation and a convolution with each other by both experiments and numerical simulations. Phase-shifting errors arising at two of the three wavelengths have proved not to cause serious deterioration of the reconstructed images.

  11. Digital phase-shifting point diffraction interferometer.

    PubMed

    Akondi, Vyas; Jewel, A R; Vohnsen, Brian

    2014-03-15

    A digital phase-shifting (PS) point diffraction interferometer is demonstrated with a transmitting liquid crystal spatial light modulator. This novel wavefront sensor allows tunability in the choice of pinhole size and eliminates the need for mechanically moving parts to achieve PS. It is shown that this wavefront sensor is capable of sensing Zernike aberrations introduced with a deformable mirror. The results obtained are compared with those of a commercial Hartmann-Shack wavefront sensor.

  12. Simple phase-shifting lateral shearing interferometer.

    PubMed

    Mihaylova, Emilia; Whelan, Maurice; Toal, Vincent

    2004-06-01

    A phase-shifting electronic speckle pattern shearing interferometer with a very simple shearing device is proposed. Two partially reflective glass plates are used to introduce the shear in this new interferometer. The reflection coefficients of the coatings on the two plates are 0.3 and 0.7. The distance between the two glass plates controls the size of the shear. The proposed new interferometric system is simple, flexible, and low cost.

  13. Phase-shifting error and its elimination in phase-shifting digital holography.

    PubMed

    Guo, Cheng-Shan; Zhang, Li; Wang, Hui-Tian; Liao, Jun; Zhu, Y Y

    2002-10-01

    We investigate the influence of phase-shifting error on the quality of the reconstructed image in digital holography and propose a method of error elimination for a perfect image. In this method the summation of the intensity bit errors of the reconstructed image is taken as an evaluation function for an iterative algorithm to find the exact phase-shifting value. The feasibility of this method is demonstrated by computer simulation.

  14. High precision phase-shifting electron holography

    PubMed

    Yamamoto; Kawajiri; Tanji; Hibino; Hirayama

    2000-01-01

    Today's information-oriented society requires high density and high quality magnetic recording media. The quantitative observation of fine magnetic structures by electron holography is greatly anticipated in the development of such new recording materials. However, the magnetic fields around particles <50 nm have not been observed, because the fields are too weak to observe in the usual way. Here we present a highly precise phase measurement technique: improved phase-shifting electron holography. Using this method, the electric field around a charged polystyrene latex particle (100 nm in diameter) and the magnetic field around iron particles (30 nm in diameter) are observed precisely. A precision of the reconstructed phase image of 2pi/300 rad is achieved in the image of the latex particle.

  15. Phase-shifting point diffraction interferometer phase grating designs

    DOEpatents

    Naulleau, Patrick

    2001-01-01

    Diffraction phase gratings are employed in phase-shifting point diffraction interferometers to improve the interferometric fringe contrast. The diffraction phase grating diffracts a zeroth-order diffraction of light at a first power level to the test-beam window of a mask that is positioned at the image plane and a first-order diffraction at a second power to the reference-beam pinhole. The diffraction phase grating is preferably selected to yield a desired ratio of the first power level to second power level.

  16. Green binary and phase shifting mask

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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).

  17. Differential-phase-shift quantum secret sharing.

    PubMed

    Inoue, K; Ohashi, T; Kukita, T; Watanebe, K; Hayashi, S; Honjo, T; Takesue, H

    2008-09-29

    A quantum secret sharing (QSS) protocol based on a differential-phase-shift scheme is proposed, which quantum mechanically provides a full secret key to one party and partial keys to two other parties. A weak coherent pulse train is utilized instead of individual photons as in conventional schemes. Compared with previous QSS protocols, the present one features a simple setup, is suitable for fiber transmission, and offers the possibility for a high key creation rate. An experiment is also carried out to demonstrate the operation.

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

    PubMed

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

    2014-01-01

    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.

  19. High-speed optical phase-shifting apparatus

    SciTech Connect

    Zortman, William A.

    2016-11-08

    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.

  20. Achromatic phase shifting focal plane masks

    NASA Astrophysics Data System (ADS)

    Newman, Kevin

    The search for life on other worlds is an exciting scientific endeavor that could change the way we perceive our place in the universe. Thousands of extrasolar planets have been discovered using indirect detection techniques. One of the most promising methods for discovering new exoplanets and searching for life is direct imaging with a coronagraph. Exoplanet coronagraphy of Earth-like planets is a challenging task, but we have developed many of the tools necessary to make it feasible. The Phase-Induced Amplitude Apodization (PIAA) Coronagraph is one of the highest-performing architectures for direct exoplanet imaging. With a complex phase-shifting focal plane mask, the PIAA Complex Mask Coronagraph (PIAACMC) can approach the theoretical performance limit for any direct detection technique. The architecture design is flexible enough to be applied to any arbitrary aperture shape, including segmented and obscured apertures. This is an important feature for compatibility with next-generation ground and space-based telescopes. PIAA and PIAACMC focal plane masks have been demonstrated in monochromatic light. An important next step for high-performance coronagraphy is the development of broadband phase-shifting focal plane masks. In this dissertation, we present an algorithm for designing the PIAA and PIAACMC focal plane masks to operate in broadband. We also demonstrate manufacturing of the focal plane masks, and show laboratory results. We use simulations to show the potential performance of the coronagraph system, and the use of wavefront control to correct for mask manufacturing errors. Given the laboratory results and simulations, we show new areas of exoplanet science that can potentially be explored using coronagraph technology. The main conclusion of this dissertation is that we now have the tools required to design and manufacture PIAA and PIAACMC achromatic focal plane masks. These tools can be applied to current and future telescope systems to enable new

  1. NMR characterization of cellulose acetate: chemical shift assignments, substituent effects, and chemical shift additivity.

    PubMed

    Kono, Hiroyuki; Hashimoto, Hisaho; Shimizu, Yuuichi

    2015-03-15

    A series of cellulose acetates (CA) with degrees of substitution (DS) ranging from 2.92-0.92 dissolved in dimethylsulfoxide (DMSO)-d6 and cellulose dissolved in tetrabutylammonium fluoride (TBAF)/DMSO-d6 were investigated by two-dimensional NMR spectroscopy. The NMR spectroscopic analysis allowed the determination of the (1)H and (13)C NMR chemical shifts of the eight anhydroglucose units (AGUs) that contain CA: 2,3,6-tri-, 2,3-di-, 2,6-di-, 3,6-di-, 2-mono-, 3-mono-, 6-mono-, and unacetylated AGUs. A comparative analysis of the chemical shift data revealed the substituent effect of acetyl groups at the 2-, 3-, and 6-positions on the (1)H and (13)C nuclei in the same AGU. In addition, chemical shift additivity could be applied to the (1)H and (13)C chemical shifts of CA because the chemical shifts of the diacetylated and triacetylated AGUs could be almost completely explained by the acetyl substituent effects at the 2-, 3-, and 6-positions.

  2. Parallel three-step phase-shifting digital holography.

    PubMed

    Awatsuji, Yasuhiro; Fujii, Atsushi; Kubota, Toshihiro; Matoba, Osamu

    2006-05-01

    We propose parallel three-step phase-shifting digital holography as a technique capable of noiseless instantaneous measurement of three-dimensional objects based on phase-shifting interferometry. The proposed digital holography carries out three-step phase shifting at the same time by using a phase-shifting array device located in the reference beam. The array device has a periodic three-step phase distribution, and its configuration is simplified compared with that required for conventional parallel phase-shifting digital holography. Therefore the optical system of the proposed parallel phase-shifting digital holography is more suitable for the realization of the proposed holography. We conduct both a numerical simulation and a preliminary experiment. The results of the simulation and experiment agree well with those of the conventional phase-shifting method and are superior to the results obtained by conventional digital holography by using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified.

  3. Phase-shifting point diffraction interferometer

    DOEpatents

    Medecki, Hector

    1998-01-01

    Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams.

  4. Phase-shifting point diffraction interferometer

    DOEpatents

    Medecki, H.

    1998-11-10

    Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams. 8 figs.

  5. Phase shift estimation in interferograms with unknown phase step

    NASA Astrophysics Data System (ADS)

    Dalmau, Oscar; Rivera, Mariano; Gonzalez, Adonai

    2016-08-01

    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-shifting behaviour revisited: An alternative measure

    NASA Astrophysics Data System (ADS)

    Kang, Bo Soo; Ryu, Doojin; Ryu, Doowon

    2014-05-01

    This study re-examines the recently documented phase-shifting behaviour of financial markets using an alternative measure, an intraday return-based measure. While most previous studies on phase-shifting behaviour adopt the volume-imbalance measure proposed by Plerou et al. (2003), we find that our return-based measure successfully captures phase-shifting behaviour, and moreover exhibits a unique pattern of phase-shifting that is not detected when the classical volume imbalance measure is used. By analysing a high-frequency dataset of KOSPI200 futures, we also find that large trades reveal phase-shifting behaviour more clearly and significantly than smaller trades.

  7. Phase-shifting point diffraction interferometer grating designs

    DOEpatents

    Naulleau, Patrick; Goldberg, Kenneth Alan; Tejnil, Edita

    2001-01-01

    In a phase-shifting point diffraction interferometer, by sending the zeroth-order diffraction to the reference pinhole of the mask and the first-order diffraction to the test beam window of the mask, the test and reference beam intensities can be balanced and the fringe contrast improved. Additionally, using a duty cycle of the diffraction grating other than 50%, the fringe contrast can also be improved.

  8. Spatial phase-shifting characteristic of double grating interferometer.

    PubMed

    Song, Yang; Chen, Yunyun; He, Anzhi; Zhao, Zhimin

    2009-10-26

    Double grating interferometer is usually used to achieve phase information from distorted wave front by its temporal phase-shifting characteristic. In this paper, the spatial phase-shifting characteristic of double grating interferometer is presented. The explicit intensity distributions of interferograms produced by double gratings are derived with the scalar diffraction theory, and the stable phase shift is found between plus-first, zero and minus-first order interferograms. Results indicate that the phase shift only depends on the grating period and the distance between two gratings if no phase object exists. If phase object exists, it varies on the interferograms. But the phase shifts are equal at any special point of interferograms. In particular, the triple grating interferometer is presented to generate at least four phase shift interferograms simultaneously with the similar method.

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

    PubMed

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

    2016-02-20

    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. Investigation of the Effect of Various Oxide and Fluoride Additives on the Microstructure, Electronic Properties, and Phase Shifting Ability of Ba(1-x) Sr(x)TiO3

    DTIC Science & Technology

    1993-09-01

    and Phase Shifting Ability of Bai-xSrxTiO3 L.C. Sengupta, E. Ngo, S. Stowell, R. Lancto, W.C. Drach , T.E. Koscica, and R.W. Babbitt ARL-TR-217...Bal_xSrxTi03 S. AUTHOR(S) L. C. Sengupta, E. Ngo, S. Stowell, and R. Lancto W. C. Drach , T. E. Koscica, and R. W. Babbitt 7. PERFORMING ORGANIZATION NAME...and DRACH . W. E. Microwavc Journal. % 35. 1992. p. 63. 2. ARLT. G., HENNINGS. D.. and deWITH. G. J. Appl. Phys.. v. 58. 1985, p. 1619. 19

  11. Model-based phase-shifting interferometer

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  12. Uncertainty-managed phase-shifting digital holography.

    PubMed

    Hahn, Joonku; Kim, Hwi

    2012-11-01

    Phase-shifting digital holography is a digital measurement technology of a complex optical field profile that uses focal plane array detectors without the loss of bandwidth. It has been known that the accuracy of phase-shifting digital holography is limited mainly by the phase tolerance of reference. In this Letter, it is revealed that the uncertainty in an expected signal is highly dependent on the phase of the signal itself, as well as the phase tolerance of the reference. Based on the uncertainty analysis, we propose a novel scheme of phase-shifting digital holography that exploits an uncertainty property to enhance the measurement accuracy even under significant reference phase tolerance.

  13. Generalized phase-shifting digital holography for single-exposure

    NASA Astrophysics Data System (ADS)

    Nomura, Takanori; Imbe, Masatoshi

    2015-07-01

    Single exposure phase-shifting digital holography is mandatory for recording/analyzing dynamic phenomena. As one of the candidate for the single exposure phase-shifting digital holography is the wave-splitting phase-shifting digital holography. We have proposed generalized phase-shifting digital holography as one of the wave-splitting phase-shifting digital holography. In the digital holography, the phase-shift quantity, which corresponds to the difference between the phase quantities of the reference wave on the adjacent pixels is generalized different from ordinal wave-splitting methods. Owing to the generalized phase-shifting, we can use a random-phase wave as the reference wave. The proposed phase-shifting digital holography enables us to record a fully-complex field of a dynamic phenomena without dc and conjugate terms using a commercially available optical devices. The relation between the property of the reference wave and the quality of the reconstructed images are discussed. Experimental results are given to confirm the proposed phase-shifting digital holography.

  14. Etched-multilayer phase shifting masks for EUV lithography

    DOEpatents

    Chapman, Henry N.; Taylor, John S.

    2005-04-05

    A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.

  15. Phase-shifting interferometry by wave amplitude modulation.

    PubMed

    Meneses-Fabian, Cruz; Rivera-Ortega, Uriel

    2011-07-01

    A new method for phase-shifting interferometry based on wave amplitude modulation is proposed and discussed. This proposal is based on the interference of three waves, where two waves attend as two reference waves and the other wave attends as a probe wave. Thereby, three interference terms are obtained, but because a phase difference of π/2 between the two references is kept constant, one of the three terms will be dropped, while the two remaining will be put in quadrature. Under these conditions, the resulting pattern is mathematically modeled by an interferogram of two waves, where an additional phase is given by the amplitude variations of the reference waves. In this Letter, both a theoretical model and some numerical simulations are presented.

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

    PubMed

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

    2010-02-01

    In Phase Stepping Interferometry (PSI) an interferogram sequence having a known, and constant phase shift between the interferograms is required. Here we take the case where this constant phase shift is unknown and the only assumption is that the interferograms do have a temporal carrier. To recover the modulating phase from the interferograms, we propose a self-tuning phase-shifting algorithm. Our algorithm estimates the temporal frequency first, and then this knowledge is used to estimate the interesting modulating phase. There are several well known iterative schemes published before, but our approach has the unique advantage of being very fast. Our new temporal carrier, and phase estimator is capable of obtaining a very good approximation of their temporal carrier in a single iteration. Numerical experiments are given to show the performance of this simple yet powerful self-tuning phase shifting algorithm.

  17. Fluctuational shift of nematic-isotropic phase transition temperature

    NASA Astrophysics Data System (ADS)

    Kats, E. I.

    2017-02-01

    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.

  18. Polarization Phase-Shift Interferometry: A Simple Laboratory Setup

    NASA Astrophysics Data System (ADS)

    Vannoni, Maurizio; Trivi, Marcelo; Molesini, Giuseppe

    2008-04-01

    An interferometry experiment is proposed, working on a Twyman-Green optical configuration. The interferogram is acquired with a digital camera and processed. Using polarization components the interferogram is phase-shifted and four different interferograms are acquired. The experiment is proposed as an introduction to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses.

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

    PubMed

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

    2013-10-01

    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.

  20. Pixel-by-pixel absolute phase retrieval using three phase-shifted fringe patterns without markers

    NASA Astrophysics Data System (ADS)

    Jiang, Chufan; Li, Beiwen; Zhang, Song

    2017-04-01

    This paper presents a method that can recover absolute phase pixel by pixel without embedding markers on three phase-shifted fringe patterns, acquiring additional images, or introducing additional hardware component(s). The proposed three-dimensional (3D) absolute shape measurement technique includes the following major steps: (1) segment the measured object into different regions using rough priori knowledge of surface geometry; (2) artificially create phase maps at different z planes using geometric constraints of structured light system; (3) unwrap the phase pixel by pixel for each region by properly referring to the artificially created phase map; and (4) merge unwrapped phases from all regions into a complete absolute phase map for 3D reconstruction. We demonstrate that conventional three-step phase-shifted fringe patterns can be used to create absolute phase map pixel by pixel even for large depth range objects. We have successfully implemented our proposed computational framework to achieve absolute 3D shape measurement at 40 Hz.

  1. Moon Phase & Libration 2013: Additional Graphics

    NASA Video Gallery

    This visualization shows the phase and libration of the Moon throughout the year 2013, at hourly intervals. Each frame represents one hour. In addition, this version of the visualization shows addi...

  2. Polarization phase shifting interferometric technique for phase calibration of a reflective phase spatial light modulator

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Somparna; Sarkar, Sanjukta; Bhattacharya, Kallol; Hazra, Lakshminarayan

    2013-03-01

    Calibration of phase in spatial light modulators is a prerequisite for applications where a prespecified phase distribution needs to be implemented over the surface of the modulator. The present work proposes a full-field polarization phase shifting interferometric technique, based on the Twyman-Green interferometer, for the purpose.

  3. Gravitationally induced phase shift on a single photon

    NASA Astrophysics Data System (ADS)

    Hilweg, Christopher; Massa, Francesco; Martynov, Denis; Mavalvala, Nergis; Chruściel, Piotr T.; Walther, Philip

    2017-03-01

    The effect of the Earth’s gravitational potential on a quantum wave function has only been observed for massive particles. In this paper we present a scheme to measure a gravitationally induced phase shift on a single photon traveling in a coherent superposition along different paths of an optical fiber interferometer. To create a measurable signal for the interaction between the static gravitational potential and the wave function of the photon, we propose a variant of a conventional Mach–Zehnder interferometer. We show that the predicted relative phase difference of 10‑5 rad is measurable even in the presence of fiber noise, provided additional stabilization techniques are implemented for each arm of a large-scale fiber interferometer. Effects arising from the rotation of the Earth and the material properties of the fibers are analysed. We conclude that optical fiber interferometry is a feasible way to measure the gravitationally induced phase shift on a single-photon wave function, and thus provides a means to corroborate the equivalence of the energy of the photon and its effective gravitational mass.

  4. Parallel two-step phase-shifting digital holography.

    PubMed

    Awatsuji, Yasuhiro; Tahara, Tatsuki; Kaneko, Atsushi; Koyama, Takamasa; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2008-07-01

    We propose a parallel two-step phase-shifting digital holography technique capable of instantaneous measurement of three-dimensional objects, with a view toward measurement of dynamically moving objects. The technique is based on phase-shifting interferometry. The proposed technique carries out the two-step phase-shifting method at one time and can be optically implemented by using a phase-shifting array device located in the reference beam. The array device has a periodic two-step phase distribution, and its configuration is simplified compared with that required for three-step and four-step parallel phase-shifting digital holographies. Therefore the optical system of the proposed technique is more suitable for the realization of a parallel phase-shifting digital holography system. We conduct both a numerical simulation and a preliminary experiment in the proposed technique. The results of the simulation and the experiment agree well with those of sequential phase-shifting digital holography, and results are superior to those obtained by conventional digital holography using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified.

  5. Phase-shifting interferometric holography of living cells

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

    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.

  6. Phase determination method in statistical generalized phase-shifting digital holography.

    PubMed

    Yoshikawa, Nobukazu

    2013-03-20

    A simple estimation method of the relative phase shift for generalized phase-shifting digital holography based on a statistical method is proposed. This method consists of a selection procedure of an optimum cost function and a simple root-finding procedure. The value and sign of the relative phase shift are determined using the coefficient and the solution of the optimum cost function. The complex field of an object wave is obtained using the estimated relative phase shift. The proposed method lifts the typical restriction on the range of the phase shift due to the phase ambiguity problem. Computer simulations and optical experiments are performed to verify the proposed method.

  7. Phase shifting mask modulated laser patterning on graphene

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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.

  8. Antiresonance phase shift in strongly coupled cavity QED.

    PubMed

    Sames, C; Chibani, H; Hamsen, C; Altin, P A; Wilk, T; Rempe, G

    2014-01-31

    We investigate phase shifts in the strong coupling regime of single-atom cavity quantum electrodynamics. On the light transmitted through the system, we observe a phase shift associated with an antiresonance and show that both its frequency and width depend solely on the atom, despite the strong coupling to the cavity. This shift is optically controllable and reaches 140°--the largest ever reported for a single emitter. Our result offers a new technique for the characterization of complex integrated quantum circuits.

  9. Binary phase-shift keying by coupling modulation of microrings.

    PubMed

    Sacher, Wesley D; Green, William M J; Gill, Douglas M; Assefa, Solomon; Barwicz, Tymon; Khater, Marwan; Kiewra, Edward; Reinholm, Carol; Shank, Steven M; Vlasov, Yurii A; Poon, Joyce K S

    2014-08-25

    We propose a coupling-modulated microring in an add-drop configuration for binary phase-shift keying (BPSK), where data is encoded as 0 and π radian phase-shifts on the optical carrier. The device uses the π radian phase-flip across the zero coupling point in a 2 × 2 Mach-Zehnder interferometer coupler to produce the modulation. The coupling-modulated microring combines the drive power reduction of resonant modulators with the digital phase response of Mach-Zehnder BPSK modulators. A proof-of-concept device was demonstrated in silicon-on-insulator, showing differential binary phase-shift keying operation at 5 and 10 Gb/s.

  10. Displacement measurement using a wavelength-phase-shifting grating interferometer.

    PubMed

    Lee, Ju-Yi; Jiang, Geng-An

    2013-10-21

    A grating interferometer based on the wavelength-modulated phase-shifting method for displacement measurements is proposed. A laser beam with sequential phase shifting can be accomplished using a wavelength-modulated light passing through an unequal-path-length optical configuration. The optical phase of the moving grating is measured by the wavelength-modulated phase-shifting technique and the proposed time-domain quadrature detection method. The displacement of the grating is determined by the grating interferometry theorem with the measured phase variation. Experimental results reveal that the proposed method can detect a displacement up to a large distance of 1 mm and displacement variation down to the nanometer range.

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

    PubMed

    Bloemhof, E E

    2014-02-10

    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.

  12. Phase shifts in the Fourier spectra of phase gratings and phase grids: an application for one-shot phase-shifting interferometry.

    PubMed

    Toto-Arellano, Noel-Ivan; Rodriguez-Zurita, Gustavo; Meneses-Fabian, Cruz; Vazquez-Castillo, Jose F

    2008-11-10

    Among several techniques, phase shifting interferometry can be implemented with a grating used as a beam divider to attain several interference patterns around each diffraction order. Because each pattern has to show a different phase-shift, a suitable shifting technique must be employed. Phase gratings are attractive to perform the former task due to their higher diffraction efficiencies. But as is very well known, the Fourier coefficients of only-phase gratings are integer order Bessel functions of the first kind. The values of these real-valued functions oscillate around zero, so they can adopt negative values, thereby introducing phase shifts of pi at certain diffraction orders. Because this almost trivial fact seems to have been overlooked in the literature regarding its practical implications, in this communication such phase shifts are stressed in the description of interference patterns obtained with grating interferometers. These patterns are obtained by placing two windows in the object plane of a 4f system with a sinusoidal grating/grid in the Fourier plane. It is shown that the corresponding experimental observations of the fringe modulation, as well as the corresponding phase measurements, are all in agreement with the proposed description. A one-shot phase shifting interferometer is finally proposed taking into account these properties after proper incorporation of modulation of polarization.

  13. Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator.

    PubMed

    Lin, Miao; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2012-05-10

    Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.

  14. Two-step-only quadrature phase-shifting digital holography.

    PubMed

    Liu, Jung-Ping; Poon, Ting-Chung

    2009-02-01

    Conventional methods of quadrature phase-shifting holography require two holograms and either intensity distribution of the reference wave or that of the object wave to reconstruct an original object without the zero order and the twin-image noise in an on-axis holographic recording setup. We present a technique called two-step-only quadrature phase-shifting holography in which solely two quadrature-phase holograms are required. Neither reference-wave intensity nor an object-wave intensity measurement is needed in the technique.

  15. Resampling masks for phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Zhang, Wenhui; Cao, Liangcai; Zhang, Hao; Zong, Song; Jin, Guofan

    2016-10-01

    Holographic imaging is degraded severely by the speckle or incoherent noise. In this work, resampling mask method based on phase-shifting digital holography is proposed to reduce the reconstruction noise. The zero-order and the conjugate term of the hologram can be eliminated with four-step phase-shifting digital holography (PSDH). The complex amplitude of the object after propagation can be calculated by the phase-shifting algorithm. A phase-only spatial light modulator is used to realize PSDH in the experiment. The complex amplitude is encoded into several parts by resampling masks. A high quality reconstruction image with low noise is achieved through the superposition of the individually reconstruction of coded complex amplitudes. The experiment data go well with the asymptotic function. This method can be used for digital holographic imaging of the biological samples and microstructures. Experimental results prove the feasibility of this proposed method.

  16. Crosstalk Cancellation for a Simultaneous Phase Shifting Interferometer

    NASA Technical Reports Server (NTRS)

    Olczak, Eugene (Inventor)

    2014-01-01

    A method of minimizing fringe print-through in a phase-shifting interferometer, includes the steps of: (a) determining multiple transfer functions of pixels in the phase-shifting interferometer; (b) computing a crosstalk term for each transfer function; and (c) displaying, to a user, a phase-difference map using the crosstalk terms computed in step (b). Determining a transfer function in step (a) includes measuring intensities of a reference beam and a test beam at the pixels, and measuring an optical path difference between the reference beam and the test beam at the pixels. Computing crosstalk terms in step (b) includes computing an N-dimensional vector, where N corresponds to the number of transfer functions, and the N-dimensional vector is obtained by minimizing a variance of a modulation function in phase shifted images.

  17. Concatenated shift registers generating maximally spaced phase shifts of PN-sequences

    NASA Technical Reports Server (NTRS)

    Hurd, W. J.; Welch, L. R.

    1977-01-01

    A large class of linearly concatenated shift registers is shown to generate approximately maximally spaced phase shifts of pn-sequences, for use in pseudorandom number generation. A constructive method is presented for finding members of this class, for almost all degrees for which primitive trinomials exist. The sequences which result are not normally characterized by trinomial recursions, which is desirable since trinomial sequences can have some undesirable randomness properties.

  18. Spin-electric Berry phase shift in triangular molecular magnets

    NASA Astrophysics Data System (ADS)

    Azimi Mousolou, Vahid; Canali, C. M.; Sjöqvist, Erik

    2016-12-01

    We propose a Berry phase effect on the chiral degrees of freedom of a triangular magnetic molecule. The phase is induced by adiabatically varying an external electric field in the plane of the molecule via a spin-electric coupling mechanism present in these frustrated magnetic molecules. The Berry phase effect depends on spin-orbit interaction splitting and on the electric dipole moment. By varying the amplitude of the applied electric field, the Berry phase difference between the two spin states can take any arbitrary value between zero and π , which can be measured as a phase shift between the two chiral states by using spin-echo techniques. Our result can be used to realize an electric-field-induced geometric phase-shift gate acting on a chiral qubit encoded in the ground-state manifold of the triangular magnetic molecule.

  19. Can small shifts in circadian phase affect performance?

    PubMed Central

    Burgess, Helen J.; Legasto, Carlo S.; Fogg, Louis F.; Smith, Mark R.

    2012-01-01

    Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1 hour shift away from a proposed optimal circadian phase angle (6 hours between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p<0.05). These results add to previous reports that suggest that humans may be sensitive to commonly occurring small shifts in circadian timing. PMID:22695081

  20. Can small shifts in circadian phase affect performance?

    PubMed

    Burgess, Helen J; Legasto, Carlo S; Fogg, Louis F; Smith, Mark R

    2013-01-01

    Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1 h shift away from a proposed optimal circadian phase angle (6 h between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p < 0.05). These results add to previous reports that suggest that humans may be sensitive to commonly occurring small shifts in circadian timing.

  1. Phase shifts in the collision of massive particles

    SciTech Connect

    Sidharth, B.G.

    1989-03-01

    In this paper phase shifts for inverse power potentials and their superpositions are considered. These potentials govern a large number of collision processes involving massive particles. But they are problematic as they do not conform to the norms obeyed by standard potentials: The usual rules for estimating the error of the phase shifts break down and an abnormally large number of phase shifts have to be computed, even if they are small. A sufficiency condition is deduced for the applicability of the Born approximation which shows that, for a given potential strength and l, surprisingly, the Born approximation is good at low energies and bad at high energies. The magnitude and direction of the error committed are also estimated. These conclusions are then verified in a number of special cases, for instance, the inverse fourth power potential used in the scattering of electrons by atoms and the Lennard--Jones potential used in the scattering of beams of molecular hydrogen with mercury atoms.

  2. Threshold secret sharing scheme based on phase-shifting interferometry.

    PubMed

    Deng, Xiaopeng; Shi, Zhengang; Wen, Wei

    2016-11-01

    We propose a new method for secret image sharing with the (3,N) threshold scheme based on phase-shifting interferometry. The secret image, which is multiplied with an encryption key in advance, is first encrypted by using Fourier transformation. Then, the encoded image is shared into N shadow images based on the recording principle of phase-shifting interferometry. Based on the reconstruction principle of phase-shifting interferometry, any three or more shadow images can retrieve the secret image, while any two or fewer shadow images cannot obtain any information of the secret image. Thus, a (3,N) threshold secret sharing scheme can be implemented. Compared with our previously reported method, the algorithm of this paper is suited for not only a binary image but also a gray-scale image. Moreover, the proposed algorithm can obtain a larger threshold value t. Simulation results are presented to demonstrate the feasibility of the proposed method.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Coaxial Fizeau simultaneous phase-shifting interferometer plays an important role in many fields for its characteristics of long optical path, miniaturization, and elimination of reference surface high-frequency error. Based on the matching of coherence between extended source and interferometer, orthogonal polarization reference wave and measurement wave can be obtained by Fizeau interferometry with Michelson interferometer preposed. Through matching spatial coherence length between preposed interferometer and primary interferometer, high contrast interference fringes can be obtained and additional interference fringes can be eliminated. Thus, the problem of separation of measurement and reference surface in the common optical path Fizeau interferometer is solved. Numerical simulation and principle experiment is conducted to verify the feasibility of extended source interferometer. Simulation platform is established by using the communication technique of DDE (dynamic data exchange) to connect Zemax and Matlab. The modeling of the extended source interferometer is realized by using Zemax. Matlab codes are programmed to automatically rectify the field parameters of the optical system and conveniently calculate the visibility of interference fringes. Combined with the simulation, the experimental platform of the extended source interferometer is established. After experimental research on the influence law of scattering screen granularity to interference fringes, the granularity of scattering screen is determined. Based on the simulation platform and experimental platform, the impacts on phase measurement accuracy of the imaging system aberration and collimation system aberration of the interferometer are analyzed. Compared the visibility relation curves between experimental measurement and simulation result, the experimental result is in line with the theoretical result.

  4. Simple phase-shifting method in a wedge-plate lateral-shearing interferometer.

    PubMed

    Song, Jae Bong; Lee, Yun Woo; Lee, In Won; Lee, Yong-Hee

    2004-07-10

    A simple phase-shifting method in a wedge-plate lateral shearing interferometer is described. Simply moving the wedge plate in an in-plane parallel direction gives the amount of phase shift required for phase-shifting interferometry because the thickness of a wedge plate is not constant and varies along the wedge direction. This method requires only one additional linear translator to move the wedge plate. The required moving distance for a phase shift of the wave front with this method is of the order of a millimeter, whereas the typical moving distance for another method that uses a piezoelectric transducer is of the order of a wavelength. This method yields better precision in controlling the moving distance than do the other methods.

  5. Phase-Shifting Liquid Crystal Interferometers for Microgravity Fluid Physics

    NASA Technical Reports Server (NTRS)

    Griffin, DeVon W.; Marshall, Keneth L.

    2002-01-01

    tends to become more transparent, thus introducing a rather large amount of error into the phase-shifting measurement. While that error can be greatly reduced by normalization, we prefer eliminating the source of the error. To that end, we have pursued development of a 'blend' of custom dyes that will not exhibit these properties. That goal has not yet been fully achieved. Guardalben, et al, presented a similar set of interferograms in a paper partially funded by this grant. Shearing interferometers are a second class of common path interferometers. Typically they consist of a thick glass plate optimized for equal reflection from the front and back surface. While not part of the original thrust of the project, through the course of laboratory work, we demonstrated a prototype of a shearing interferometer capable of phase shifting using a commercial liquid crystal retardation plate. A schematic of this liquid crystal shearing interferometer (LCSI) and a sample set of interferograms are in the reference. This work was also supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article. Additional information is included in the original extended abstract.

  6. Parallel phase-shifting digital holography using spectral estimation technique.

    PubMed

    Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu

    2014-09-20

    We propose a parallel phase-shifting digital holography using a spectral estimation technique, which enables the instantaneous acquisition of spectral information and three-dimensional (3D) information of a moving object. In this technique, an interference fringe image that contains six holograms with two phase shifts for three laser lines, such as red, green, and blue, is recorded by a space-division multiplexing method with single-shot exposure. The 3D monochrome images of these three laser lines are numerically reconstructed by a computer and used to estimate the spectral reflectance distribution of object using a spectral estimation technique. Preliminary experiments demonstrate the validity of the proposed technique.

  7. An in situ method for diagnosing phase shifting interferometry

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  8. Quantum phase shift in Chern-Simons modified gravity

    SciTech Connect

    Nandi, K. K.; Kizirgulov, I. R.; Mikolaychuk, O. V.; Mikolaychuk, N. P.; Potapov, A. A.

    2009-04-15

    Using a unified approach of optical-mechanical analogy in a semiclassical formula, we evaluate the effect of Chern-Simons modified gravity on the quantum phase shift of de Broglie waves in neutron interferometry. The phase shift calculated here reveals, in a single equation, a combination of effects coming from Newtonian gravity, inertial forces, Schwarzschild and Chern-Simons modified gravity. However the last two effects, though new, turn out to be too tiny to be observed, and hence only of academic interest at present. The approximations, wherever used, as well as the drawbacks of the nondynamical approach are clearly indicated.

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

    PubMed

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

    2016-04-04

    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.

  10. High-speed phase imaging by parallel phase-shifting digital holography.

    PubMed

    Kakue, Takashi; Yonesaka, Ryosuke; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-11-01

    Parallel phase-shifting digital holography can obtain three-dimensional information of a dynamically moving object with high accuracy by using space-division multiplexing of multiple holograms required for phase-shifting interferometry. We demonstrated high-speed parallel phase-shifting digital holography and obtained images of the phase variation of air caused by a compressed gas flow sprayed from a nozzle. In particular, we found the interesting phenomenon of periodic phase distributions. Reconstructed images were obtained at frame rates of 20,000 and 180,000 frames per second.

  11. Robust phase-shift-keying silicon photonic modulator.

    PubMed

    Adams, Donald; Aboketaf, Abdelsalam; Preble, Stefan

    2012-07-30

    Here we propose a robust silicon modulator that seamlessly generates phase shift keyed data. The modulator has very low insertion loss and is robust against electrical amplitude variations in the modulating signal; specifically a 50%-200% variation in modulating amplitude leads to only a π/9 variation in output optical phase, corresponding to only ± 10% variation in the differentially detected signal. This yields a ~2.5dB enhancement in SNR over OOK (on-off-keying) formats.

  12. Group-theoretical derivation of Aharonov-Bohm phase shifts

    SciTech Connect

    Hagen, C. R.

    2013-02-15

    The phase shifts of the Aharonov-Bohm effect are generally determined by means of the partial wave decomposition of the underlying Schroedinger equation. It is shown here that they readily emerge from an o(2,1) calculation of the energy levels employing an added harmonic oscillator potential which discretizes the spectrum.

  13. Equal-Path, Phase-Shifting, Sample-Point Interferometer

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K.

    1991-01-01

    Proposed interferometer combination of sample-point interferometer and equal-path interferometer. Used to monitor optical figures of arrays of mirrors or of segmented mirrors. Incorporation of phase shifting with part of equal-path interferometer renders new interferometer insensitive to vibration and air turbulence. Instrument used over large distances, on ground, or on vibrating structures.

  14. A Simple Ultrasonic Experiment Using a Phase Shift Detection Technique.

    ERIC Educational Resources Information Center

    Yunus, W. Mahmood Mat; Ahmad, Maulana

    1996-01-01

    Describes a simple ultrasonic experiment that can be used to measure the purity of liquid samples by detecting variations in the velocity of sound. Uses a phase shift detection technique that incorporates the use of logic gates and a piezoelectric transducer. (JRH)

  15. Phase extracting and unwrapping algorithm of electrical speckle shearing phase-shifting pattern interferometry

    NASA Astrophysics Data System (ADS)

    Jing, Chao; Zhou, Ping; Zhang, Yimo

    2016-10-01

    Electrical Speckle Shearing Phase-shifting Pattern Interferometry (ESSPPI) has been used in the fields of nondestructive testing (NDT) and stress field analysis as a precise deformation measuring method. The general fixed-step phase extracting algorithms of ESSPPI, such as three-step algorithms, four-step algorithms, five-step algorithms, and their corresponding errors are analyzed. It is proved that the phase accuracy of ESSPPI with different algorithms are mainly affected by linear error of phase-shifting. Therefore the modified four-step phase-shifting extracting algorithm that isn't sensitive to linear error of phase-shifting is adopted in the paper. The filtering algorithm should be employed to reduce the influences of speckle noise and wrong data caused by errors during measurement. Then the least-squares phase-unwrapping algorithm based on fast discrete cosine transform (LPABFDCT) is adopted to search the least-squares solutions between phase difference value of adjacent pixels and unwrapped phase difference value of the pixels and the real phase distribution caused by object deformation is obtained. The Electrical Speckle Shearing Phase-shifting Pattern Interferometric images are captured with four-step phase-shifting method and the real phase distributing image is achieved with modified four-step phase-shifting extracting algorithm, denoising filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform. It is proved with experiment results that the real phase distributing images are effective achieved by mean of combination of average filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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.

  17. Effects of quantization in phase-shifting digital holography.

    PubMed

    Mills, Godfrey A; Yamaguchi, Ichirou

    2005-03-01

    We discuss quantization effects of hologram recording on the quality of reconstructed images in phase-shifting digital holography. We vary bit depths of phase-shifted holograms in both numerical simulation and experiments and then derived the complex amplitude, which is subjected to Fresnel transformation for the image reconstruction. The influence of bit-depth limitation in quantization has been demonstrated in a numerical simulation for spot-array patterns with linearly varying intensities and a continuous intensity object. The objects are provided with uniform and random phase modulation. In experiments, digital holograms are originally recorded at 8 bits and the bit depths are changed to deliver holograms at bit depths of 1 to 8 bits for the image reconstruction. The quality of the reconstructed images has been evaluated for the different quantization levels.

  18. Family of detuning-insensitive phase-shifting algorithms.

    PubMed

    Malacara-Doblado, D; Dorrío, B V

    2000-10-01

    The design of phase-shifting algorithms (PSA's) has been carried out with diverse strategies by different authors. A generalized algebraic approach is employed to obtain a family of detuning-insensitive PSA's; their behavior against a linear phase error is analyzed from a geometric point of view. The obtained results are compared with the conditions provided by the Fourier representation of the corresponding sampling reference functions. In our case, new equations as criteria for determining whether a PSA is detuning insensitive, new analytic expressions for the phase error, and new algorithms with interesting properties are achieved.

  19. Phase-shift migration with wave-packet algorithms

    NASA Astrophysics Data System (ADS)

    Mosher, Charles C.; Foster, Douglas J.; Wu, Ru-Shan

    1996-10-01

    Wavelet transforms have a simple representation in the frequency domain (Daubchies, 1992; Veterlli and Herley, 1992; Mosher and Foster, 1995). Since wave propagation also has a simple representation in the frequency domain, frequency domain wavelet transforms provide a useful framework for studying the nature of wave propagation in the wavelet domain. In this paper, we study phase shift extrapolators for 2-dimensional wavefields that have been Fourier transformed over time and wavelet transformed over space. The wavelet transform over the space axis is implemented in the wavenumber-frequency domain by complex multiplication of low and high pass wavenumber filter functions to form wave packet trees. To differentiate this operation from time-frequency wavelet transforms, we refer to the space-wavenumber-frequency transform as the 'beamlet transform.' The interaction of beamlet transform filter banks and phase shift wavefield extrapolators are simple complex multiplications. Wavefield propagation in the beamlet domain is complicated, however, by the digital implementation of decimation and upsampling operators used in orthogonal wavelet transforms. Unlike the filter functions, which can be viewed as diagonal matrix operators, the decimation and upsampling operators have significant off-diagonal terms. Since these operators do not commute with the filter and phase shift operators, the effects of the non-diagonal operators must be accounted for in the application of wave propagation operators. A simple (but unsatisfying) solution would be to apply forward-inverse transforms at each extrapolation step. Beamlet transforms with compact support in the wavenumber domain (Mosher and Foster, 1995) provide an alternate solution. Analysis of phase shift migration in the beamlet domain yields a simple matrix representation defining the interaction of filters, phase operators, and decimation/upsampling. The effects of decimation/upsampling are represented by simple folding

  20. Phase-shifting digital holography with a phase difference between orthogonal polarizations.

    PubMed

    Nomura, Takanori; Murata, Shinji; Nitanai, Eiji; Numata, Takuhisa

    2006-07-10

    Phase-shifting digital holography with a phase difference between orthogonal polarizations is proposed. The use of orthogonal polarizations can make it possible to record two phase-shifted holograms simultaneously. By combining the holograms with the distributions of a reference wave and an object wave, the complex field of the object's wavefront can be obtained. Preliminary experimental results are shown to confirm the proposed method.

  1. Detection of the phase shift from a single Abrikosov vortex.

    PubMed

    Golod, T; Rydh, A; Krasnov, V M

    2010-06-04

    We probe a quantum mechanical phase rotation induced by a single Abrikosov vortex in a superconducting lead, using a Josephson junction, made at the edge of the lead, as a phase-sensitive detector. We observe that the vortex induces a Josephson phase shift equal to the polar angle of the vortex within the junction length. When the vortex is close to the junction it induces a π step in the Josephson phase difference, leading to a controllable and reversible switching of the junction into the 0-π state. This in turn results in an unusual Φ(0)/2 quantization of the flux in the junction. The vortex may hence act as a tunable "phase battery" for quantum electronics.

  2. Surface shape measurement by phase-shifting digital holography with a wavelength shift.

    PubMed

    Yamaguchi, Ichirou; Ida, Takashi; Yokota, Masayuki; Yamashita, Kouji

    2006-10-10

    Surface contouring by phase-shifting digital holography is proposed and verified by experiments and numerical simulations. Digital holograms are recorded before and after mode hopping of a laser diode subject to current tuning, and the difference of the reconstructed phases at each wavelength is computed to deliver surface contours of a diffusely reflecting surface. Since normal incidence on the object is employed, the method does not need the removal of the tilt component and is free from the shadowing effect as advantages over the dual-incidence method proposed before by the first author.

  3. Phase Shift of the Asymmetric Friedel-Anderson Impurity

    NASA Astrophysics Data System (ADS)

    Bergmann, Gerd

    2013-04-01

    The ground state of the asymmetric Friedel-Anderson (aFA) impurity is calculated within the FAIR (Friedel artificially inserted resonance) theory. Its properties are investigated by means of the fidelity with different Friedel impurities and by its Friedel oscillations. Friedel impurities with a specific phase shift δ at the Fermi level possess a finite fidelity with the aFA impurity. This phase shift δ determines other properties of the aFA impurity such as the amplitude and displacement of its Friedel oscillations. One can find the parameters of a Friedel impurity which coincides in its Friedel oscillations almost perfectly with the aFA impurity, thereby avoiding an Anderson orthogonality catastrophe.

  4. Terahertz single-shot quadrature phase-shifting interferometry.

    PubMed

    Földesy, Péter

    2012-10-01

    A single-shot quadrature phase-shifting interferometry architecture is presented that is applicable to antenna coupled detector technologies. The method is based on orthogonally polarized object and reference beams and on linear and circular polarization sensitive antennas in space-division multiplexing. The technique can be adapted to two-, three-, and four-step and Gabor holography recordings. It is also demonstrated that the space-division multiplexing does not necessarily cause sparse sampling. A sub-THz detector array is presented containing multiple on-chip antennas and FET plasma wave detectors implemented in a 90 nm complementary metal-oxide semiconductor technology. As an example, two-step phase-shifting reconstruction results are given at 360 GHz.

  5. Phase-shifting electron holography for atomic image reconstruction.

    PubMed

    Yamamoto, Kazuo; Sugawara, Yoshihiro; McCartney, Martha R; Smith, David J

    2010-08-01

    Phase-shifting electron holography was used to reconstruct the object-wave function of high-spatial-frequency specimens of HgCdTe, and the requirements for precise measurements were investigated. Fresnel fringes due to the electrostatic biprism caused serious calculation errors during the phase-shifting reconstruction. Uniform interference fringes, obtained by adjusting the biprism voltage to cancel out the Fresnel fringes, were needed to minimize these errors. High-resolution holograms of a HgCdTe single crystal were recorded with coarse interference fringes and a high visibility of 65% and then used to reconstruct the atomic-scale object wave. Although the spatial resolution (0.25 nm) of the transmission electron microscope was worse than the separation (0.16 nm) between Hg (or Cd) and Te columns, the crystal polarity was determined from the aberration-corrected object wave.

  6. Use of Fresnelets for phase-shifting digital hologram compression.

    PubMed

    Darakis, Emmanouil; Soraghan, John J

    2006-12-01

    Fresnelets are wavelet-like base functions specially tailored for digital holography applications. We introduce their use in phase-shifting interferometry (PSI) digital holography for the compression of such holographic data. Two compression methods are investigated. One uses uniform quantization of the Fresnelet coefficients followed by lossless coding, and the other uses set portioning in hierarchical trees (SPIHT) coding. Quantization and lossless coding of the original data is used to compare the performance of the proposed algorithms. The comparison reveals that the Fresnelet transform of phase-shifting holograms in combination with SPIHT or uniform quantization can be used very effectively for the compression of holographic data. The performance of the new compression schemes is demonstrated on real PSI digital holographic data.

  7. Phase-shifting point diffraction interferometer mask designs

    DOEpatents

    Goldberg, Kenneth Alan

    2001-01-01

    In a phase-shifting point diffraction interferometer, different image-plane mask designs can improve the operation of the interferometer. By keeping the test beam window of the mask small compared to the separation distance between the beams, the problem of energy from the reference beam leaking through the test beam window is reduced. By rotating the grating and mask 45.degree., only a single one-dimensional translation stage is required for phase-shifting. By keeping two reference pinholes in the same orientation about the test beam window, only a single grating orientation, and thus a single one-dimensional translation stage, is required. The use of a two-dimensional grating allows for a multiplicity of pinholes to be used about the pattern of diffracted orders of the grating at the mask. Orientation marks on the mask can be used to orient the device and indicate the position of the reference pinholes.

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

    NASA Astrophysics Data System (ADS)

    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

    2016-07-01

    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.

  9. Phase-shifting interferometry based on the lateral displacement of the light source.

    PubMed

    Robledo-Sanchez, Carlos; Juarez-Salazar, Rigoberto; Meneses-Fabian, Cruz; Guerrero-Sánchez, Fermin; Arévalo Aguilar, L M; Rodriguez-Zurita, Gustavo; Ixba-Santos, Viridiana

    2013-07-15

    A simple and inexpensive optical setup to phase-shifting interferometry is proposed. This optical setup is based on the Twyman-Green Interferometer where the phase shift is induced by the lateral displacement of the point laser source. A theoretical explanation of the induced phase by this alternative method is given. The experimental results are consistent with the theoretical expectations. Both, the phase shift and the wrapped phase are recovered by a generalized phase-shifting algorithm from two or more interferograms with arbitrary and unknown phase shift. The experimental and theoretical results show the feasibility of this unused phase-shifting technique.

  10. Nonlocal nonlinear refraction in Hibiscus sabdariffa with large phase shifts.

    PubMed

    Ramírez-Martínez, D; Alvarado-Méndez, E; Trejo-Durán, M; Vázquez-Guevara, M A

    2014-10-20

    In this work we present a study of nonlinear optical properties in organic materials (hibiscus sabdariffa). Our results demonstrate that the medium exhibits a highly nonlocal nonlinear response. We show preliminary numerical results of the transmittance as nonlocal response by considering, simultaneously, the nonlinear absorption and refraction in media. Numerical results are accord to measurement obtained by Z- scan technique where we observe large phase shifts. We also analyze the far field diffraction ring patterns of the sample.

  11. Simultaneous two-wavelength Doppler phase-shifting digital holography.

    PubMed

    Barada, Daisuke; Kiire, Tomohiro; Sugisaka, Jun-ichiro; Kawata, Shigeo; Yatagai, Toyohiko

    2011-12-01

    This paper presents a method based on the use of an image sensor for obtaining the complex amplitudes of beams diffracted from an object at two different wavelengths. The complex amplitude for each wavelength is extracted by the Doppler phase-shifting method. The principle underlying the proposed method is experimentally verified by using the method with two lasers having different wavelengths to measure the surface shape of a concave mirror.

  12. Multiwavelength parallel phase-shifting digital holography using angular multiplexing.

    PubMed

    Tahara, Tatsuki; Ito, Yasunori; Lee, Yonghee; Xia, Peng; Inoue, Junichi; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2013-08-01

    We propose a single-shot digital holography for recording multiwavelength and complex amplitude information by using a single monochromatic image sensor. The zeroth-order wave and conjugate image in each wavelength are removed from a recorded single hologram by applying parallel phase-shifting interferometry. Angular multiplexing is utilized to record the complex amplitude of an object wave in each wavelength separately, and no color filter is required. The effectiveness of the proposed technique was experimentally verified.

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

    NASA Astrophysics Data System (ADS)

    Pagano, Glenn W.; Mann, Christopher J.

    2014-05-01

    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.

  14. Common-path phase-shifting lensless holographic microscopy.

    PubMed

    Micó, Vicente; García, Javier

    2010-12-01

    We present an approach capable of high-NA imaging in a lensless digital in-line holographic microscopy layout even outside the Gabor's regime. The method is based on spatial multiplexing at the sample plane, allowing a common-path interferometric architecture, where two interferometric beams are generated by a spatial light modulator (SLM) prior to illuminating the sample. The SLM allows phase-shifting interferometry by phase modulation of the SLM diffracted beam. After proper digital processing, the complex amplitude distribution of the diffracted object wavefront is recovered and numerically propagated to image the sample. Experimental results are reported that validate the proposed method.

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

    SciTech Connect

    Montagut, Y. J.; Garcia, J. V.; Jimenez, Y.; Arnau, A.; March, C.; Montoya, A.

    2011-06-15

    The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequency/mass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed.

  16. Phase shift facilitation following cyclone disturbance on coral reefs.

    PubMed

    Roff, George; Doropoulos, Christopher; Zupan, Mirta; Rogers, Alice; Steneck, Robert S; Golbuu, Yimnang; Mumby, Peter J

    2015-08-01

    While positive interactions have been observed to influence patterns of recruitment and succession in marine and terrestrial plant communities, the role of facilitation in macroalgal phase shifts is relatively unknown. In December 2012, typhoon Bopha caused catastrophic losses of corals on the eastern reefs of Palau. Within weeks of the typhoon, an ephemeral bloom of monospecific macroalgae (Liagora sp.) was observed, reaching a peak of 38.6% cover in February 2013. At this peak, we observed a proliferation of a second macroalgal species, Lobophora variegata. Lobophora was distributed non-randomly, with higher abundances occurring within the shelter of Liagora canopies than on exposed substrates. Bite rates of two common herbivorous fish (Chlorurus sordidus and Ctenochaetus striatus) were significantly higher outside canopies (2.5- and sixfold, respectively), and cage exclusion resulted in a significant increase in Lobophora cover. Experimental removal of Liagora canopies resulted in a 53.1% decline in the surface area of Lobophora after 12 days, compared to a 51.7% increase within canopies. Collectively, these results indicate that Liagora canopies act as ecological facilitators, providing a 'nursery' exclusion zone from the impact of herbivorous fish, allowing for the establishment of understory Lobophora. While the ephemeral Liagora bloom had disappeared entirely 9 months post-typhoon, the facilitated shift to Lobophora has persisted for over 18 months, dominating ~40% of the reef substrate. While acute disturbance events such as typhoons have been suggested as a mechanism to reverse algal phase shifts, our results suggest that typhoons may also trigger, rather than just reverse, phase shifts.

  17. A new approach to NMR chemical shift additivity parameters using simultaneous linear equation method.

    PubMed

    Shahab, Yosif A; Khalil, Rabah A

    2006-10-01

    A new approach to NMR chemical shift additivity parameters using simultaneous linear equation method has been introduced. Three general nitrogen-15 NMR chemical shift additivity parameters with physical significance for aliphatic amines in methanol and cyclohexane and their hydrochlorides in methanol have been derived. A characteristic feature of these additivity parameters is the individual equation can be applied to both open-chain and rigid systems. The factors that influence the (15)N chemical shift of these substances have been determined. A new method for evaluating conformational equilibria at nitrogen in these compounds using the derived additivity parameters has been developed. Conformational analyses of these substances have been worked out. In general, the results indicate that there are four factors affecting the (15)N chemical shift of aliphatic amines; paramagnetic term (p-character), lone pair-proton interactions, proton-proton interactions, symmetry of alkyl substituents and molecular association.

  18. Phase-Shifting Liquid Crystal Point-Diffraction Interferometry

    NASA Technical Reports Server (NTRS)

    Griffin, DeVon W.; Marshall, Kenneth L.; Mercer, Carolyn R.

    2000-01-01

    , the limited spatial resolution and the methods required for data reduction suggest that a more useful instrument needs to be developed. The category of interferometers known as common path interferometers can eliminate much of the vibration sensitivity associated with traditional interferometry as described above. In these devices, division of the amplitude of the wavefront following the test section produces the reference beam. Examples of these instruments include shearing and point diffraction interferometers. In the latter case, shown schematically, a lens focuses light passing through the test section onto a small diffracting object. Such objects are typically either a circle of material on a high quality glass plate or a small sphere in a glass cell. The size of the focused spot is several times larger than the object so that the light not intercepted by the diffracting object forms the test beam while the diffracted light generates a spherical reference beam. While this configuration is mechanically stable, phase shifting one beam with respect to the other is difficult due to the common path. Phase shifting enables extremely accurate measurements of the phase of the interferogram using only gray scale intensity measurements and is the de facto standard of industry. Mercer and Creath 2 demonstrated phase shifting in a point diffraction interferometer using a spherical spacer in a liquid crystal cell as the diffracting object. By changing the voltage across the cell, they were able to shift the phase of the undiffracted beam relative to the reference beam generated by diffraction from the sphere. While they applied this technology to fluid measurements, the device shifted phase so slowly that it was not useful for studying transient phenomena. We have identified several technical problems that precluded operation of the device at video frame rates and intend to solve them to produce a phase-shifting liquid crystal point-diffraction interferometer operating at

  19. Phase shifting two coupled circadian pacemakers - Implications for jet lag

    NASA Technical Reports Server (NTRS)

    Gander, P. H.; Kronauer, R. E.; Graeber, R. C.

    1985-01-01

    Two Van der Pol oscillators with reciprocal linear velocity coupling are utilized to model the response of the human circadian timing system to abrupt displacements of the environmental time cues (zeitgebers). The core temperature rhythm and sleep-wake cycle simulated by the model are examined. The relationship between the masking of circadian rhythms by environmental variables and behavioral and physiological events and the rates of resynchronization is studied. The effects of zeitgeber phase shifts and zeitgeber strength on the resynchronization rates are analyzed. The influence of intrinsic pacemakers periods and coupling strength on resynchronization are investigated. The simulated data reveal that: resynchronization after a time zone shift depends on the magnitude of the shift; the time of day of the shift has little influence on resynchronization; the strength of zeitgebers affects the rate and direction of the resynchronization; the intrinsic pacemaker periods have a significant effect on resynchronization; and increasing the coupling between the oscillators results in an increase in the rate of resynchronization. The model data are compared to transmeridian flight studies data and similar resynchronization patterns are observed.

  20. Compressive holography reconstruction using phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Shen, Chuan; Cheng, Hong; Zhang, Fen; Liu, Kaifeng; Zhang, Quanbing; Wei, Sui

    2015-05-01

    In classical compressive holography (CH), which based on the Gabor holography setup, two nonlinear terms are inherent in the intensity recorded by a 2D detector arrays, the DC term and the squared field term. The DC term (the term at the origin) can be eliminated by filtering the Fourier transform of the interference irradiance measurements using appropriate high-pass filter near the zero frequency. The nonlinearity caused by the squared field term can be neglected and modeled as a error term in the measurement. However, the above assumptions are significantly limited, which yields the degradation of reconstruction quality. In this paper, an novel scheme using phase-shifting method is presented. To accurately recover the complex optical field caused by the propagation of the object, without the influence of the DC term and the squared field term, a very effective method for removing these two terms is introduced. The complex optical field of the 3D object and the complex optical field at the detector plane can be precisely represented by a linear mapping model. The complex optical field at the recorder plane is obtained by phase-shifting interferometry with multiple shots. Then, the corresponded complex optical field at the detector plane can be successfully extracted from multiple captured holograms using conventional four phase-shifting interferometry. From such complex optical field at the record plane, including the amplitude and phase information, the complex optical field of the 3D object can be reconstructed via an optimization procedure. Numerical results demonstrate the effectiveness of our proposed method.

  1. Phase shifting technique for extended inline holographic microscopy with a pinhole array.

    PubMed

    Graulig, Christian; Kanka, Mario; Riesenberg, Rainer

    2012-09-24

    Digital inline holographic microscopy using a pinhole for sample illumination allows lensless imaging. To overcome restrictions of the sample size and density in the setup additional reference waves are generated by extending the single pinhole to a regular 2D pinhole array illumination. A technique is presented that uses phase shifting between the pinhole waves. Multiple foci with stable phase differences and a phase error (rms) of 0.027 rad generate pinhole waves which illuminate an undiluted, dense blood smear sample. Amplitude and phase images of the blood sample were successfully reconstructed.

  2. Optical channel de-aggregation of quadrature-phase-shift-keying and eight-phase-shift-keying data using mapping onto constellation axes.

    PubMed

    Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Almaiman, Ahmed; Cao, Yinwen; Chitgarha, Mohammad Reza; Paraschis, Loukas; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Touch, Joseph D; Willner, Alan E

    2015-11-01

    An eight-phase-shift-keying signal is experimentally de-aggregated onto two four-pulse amplitude modulation signals using nonlinear processes in optical elements. Quadrature-phase-shift-keying signals are similarly de-multiplexed into two binary phase shift keying signals by mapping the data points onto the constellation axes. De-multiplexing performance is evaluated as a function of the optical signal-to-noise ratio of the incoming signals. The effect of phase noise is also studied.

  3. Application of ANFIS to Phase Estimation for Multiple Phase Shift Keying

    NASA Technical Reports Server (NTRS)

    Drake, Jeffrey T.; Prasad, Nadipuram R.

    2000-01-01

    The paper discusses a novel use of Adaptive Neuro-Fuzzy Inference Systems (ANFIS) for estimating phase in Multiple Phase Shift Keying (M-PSK) modulation. A brief overview of communications phase estimation is provided. The modeling of both general open-loop, and closed-loop phase estimation schemes for M-PSK symbols with unknown structure are discussed. Preliminary performance results from simulation of the above schemes are presented.

  4. Implementation of phase-shift focus monitor with modified illumination

    NASA Astrophysics Data System (ADS)

    Nakao, Shuji; Maejima, Shinroku; Ueno, Atsushi; Yamashita, Shigenori; Miyazaki, Junji; Tokui, Akira; Tsujita, Kouichirou; Arimoto, Ichiriou

    2002-07-01

    For the convenience of practical use of phase shift focus monitor (PSFM), which has been developed by T. Brunner, imaging characteristics of PSFM are investigated under modified illumination by optical image calculations and printing experiments. Although the mechanism of pattern shift with focus offset under modified illumination is different from that for conventional high coherent illumination, sufficient sensitivity for precise focus monitoring is predicted by optical image calculations. Also, it is revealed that reduction of NA, i.e., localizing illumination at the peripheral part of pupil is effective to obtain higher sensitivity. By experiments, predicted characteristics are observed and similar sensitivity to that in conventional high coherent illumination is confirmed both for annular and quadrupole illuminations.

  5. Carrier Synchronization of Offset Quadrature Phase-Shift Keying

    NASA Astrophysics Data System (ADS)

    Simon, M. K.

    1998-01-01

    This article contains analyses of the performance of various carrier synchronization loops for offset quadrature phase-shift-keying (OQPSK) modulation, all motivated in one form or another by the maximum a posteriori (MAP) estimation of carrier phase. When they are implemented as either high or low signal-to-noise ratio (SNR) approximations to the generic implementation suggested by the MAP estimation of carrier phase for an OQPSK signal, it is shown that the loops behave more like biphase than quadriphase loops in that they only exhibit a 180-deg phase ambiguity rather than the 90-deg phase ambiguity typical of the latter. This phase ambiguity advantage coupled with the mean-square tracking-error performance advantage that results and its ultimate effect on average error probability performance offer a potentially significant justification for using OQPSK rather than QPSK even on a linear transmission channel, where it often is reasoned (based on the assumption of an ideal environment) that the two modulation schemes perform identically.

  6. The phase shift method for studying nonlinear acoustics in a soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper, a phase shift method for studying nonlinear acoustic behaviors of a soil is described. The method uses a phase-lock-in technique to measure the phase shift caused by increments in the amplitude of an excitation. The measured phase shift as a function of dynamic strain amplitude is use...

  7. Application of Phase Shifted, Laser Feedback Interferometry to Fluid Physics

    NASA Technical Reports Server (NTRS)

    Ovryn, Ben; Eppell, Steven J.; Andrews, James H.; Khaydarov, John

    1996-01-01

    We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio even for low reflectivity samples. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Carre or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured. We have combined our interferometer with a commercial microscope and scanning piezoelectric stage and have measured the variation in OPL and visibility for drops of PDMS (silicone oil) on coated single crystal silicon. Our measurement of the static contact angle agrees with the value of 68 deg stated in the literature.

  8. Phase-Shifting Liquid Crystal Point-Diffraction Interferometry

    NASA Technical Reports Server (NTRS)

    Griffin, DeVon W.; Marshall, Kenneth L.; Mercer, Carolyn R.

    2000-01-01

    , the limited spatial resolution and the methods required for data reduction suggest that a more useful instrument needs to be developed. The category of interferometers known as common path interferometers can eliminate much of the vibration sensitivity associated with traditional interferometry as described above. In these devices, division of the amplitude of the wavefront following the test section produces the reference beam. Examples of these instruments include shearing and point diffraction interferometers. In the latter case, shown schematically, a lens focuses light passing through the test section onto a small diffracting object. Such objects are typically either a circle of material on a high quality glass plate or a small sphere in a glass cell. The size of the focused spot is several times larger than the object so that the light not intercepted by the diffracting object forms the test beam while the diffracted light generates a spherical reference beam. While this configuration is mechanically stable, phase shifting one beam with respect to the other is difficult due to the common path. Phase shifting enables extremely accurate measurements of the phase of the interferogram using only gray scale intensity measurements and is the de facto standard of industry. Mercer and Creath 2 demonstrated phase shifting in a point diffraction interferometer using a spherical spacer in a liquid crystal cell as the diffracting object. By changing the voltage across the cell, they were able to shift the phase of the undiffracted beam relative to the reference beam generated by diffraction from the sphere. While they applied this technology to fluid measurements, the device shifted phase so slowly that it was not useful for studying transient phenomena. We have identified several technical problems that precluded operation of the device at video frame rates and intend to solve them to produce a phase-shifting liquid crystal point-diffraction interferometer operating at

  9. Reflection/transmission phase shift interferometer and viewing optics

    SciTech Connect

    Monjes, J.A.; Weinstein, B.W.; Willenborg, D.L.

    1981-06-15

    The interferometer and viewing optics that are the main optical components of an Automated Surface Mapping system (ASM) used to characterize the surface topography and the wall thickness uniformity of opaque and transparent spherical shells is described. To characterize surface finish or wall thickness of spherical shells with an accuracy of 10 nm and a resolution of 1 ..mu..m the differential phase shift between two beams of orthogonal polarizations is measured, before and after the probe beam has interacted with the test object.

  10. Two-step phase-shifting fluorescence incoherent holographic microscopy.

    PubMed

    Qin, Wan; Yang, Xiaoqi; Li, Yingying; Peng, Xiang; Yao, Hai; Qu, Xinghua; Gao, Bruce Z

    2014-06-01

    Fluorescence holographic microscope (FINCHSCOPE) is a motionless fluorescence holographic imaging technique based on Fresnel incoherent correlation holography (FINCH) that shows promise in reconstructing three-dimensional fluorescence images of biological specimens with three holograms. We report a developing two-step phase-shifting method that reduces the required number of holograms from three to two. Using this method, we resolved microscopic fluorescent beads that were three-dimensionally distributed at different depths with two interferograms captured by a CCD camera. The method enables the FINCHSCOPE to work in conjunction with the frame-straddling technique and significantly enhance imaging speed.

  11. Two-step phase-shifting fluorescence incoherent holographic microscopy

    PubMed Central

    Qin, Wan; Yang, Xiaoqi; Li, Yingying; Peng, Xiang; Yao, Hai; Qu, Xinghua; Gao, Bruce Z.

    2014-01-01

    Abstract. Fluorescence holographic microscope (FINCHSCOPE) is a motionless fluorescence holographic imaging technique based on Fresnel incoherent correlation holography (FINCH) that shows promise in reconstructing three-dimensional fluorescence images of biological specimens with three holograms. We report a developing two-step phase-shifting method that reduces the required number of holograms from three to two. Using this method, we resolved microscopic fluorescent beads that were three-dimensionally distributed at different depths with two interferograms captured by a CCD camera. The method enables the FINCHSCOPE to work in conjunction with the frame-straddling technique and significantly enhance imaging speed. PMID:24972355

  12. Hand held phase-shifting diffraction Moire interferometer

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1994-09-20

    An interferometer is described in which a coherent beam of light is generated within a remote case and transmitted to a hand held unit tethered to said remote case, said hand held unit having optical elements for directing a pair of mutually coherent collimated laser beams at a diffraction grating. Data from the secondary or diffracted beams are then transmitted to a separate video and data acquisition system for recording and analysis for load induced deformation or for identification purposes. Means are also provided for shifting the phase of one incident beam relative to the other incident beam and being controlled from within said remote case. 4 figs.

  13. Hand held phase-shifting diffraction moire interferometer

    DOEpatents

    Deason, Vance A.; Ward, Michael B.

    1994-01-01

    An interferometer in which a coherent beam of light is generated within a remote case and transmitted to a hand held unit tethered to said remote case, said hand held unit having optical elements for directing a pair of mutually coherent collimated laser beams at a diffraction grating. Data from the secondary or diffracted beams are then transmitted to a separate video and data acquisition system for recording and analysis for load induced deformation or for identification purposes. Means are also provided for shifting the phase of one incident beam relative to the other incident beam and being controlled from within said remote case.

  14. Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses

    SciTech Connect

    Alekseev, A E; Vdovenko, V S; Sergachev, I A; Simikin, D E; Gorshkov, B G; Potapov, V T

    2014-10-31

    We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)

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

    PubMed

    Morin, Lawrence P; Studholme, Keith M

    2014-10-01

    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.

  16. Motion compensation and noise tolerance in phase-shifting digital in-line holography.

    PubMed

    Stenner, Michael D; Neifeld, Mark A

    2006-05-15

    We present a technique for phase-shifting digital in-line holography which compensates for lateral object motion. By collecting two frames of interference between object and reference fields with identical reference phase, one can estimate the lateral motion that occurred between frames using the cross-correlation. We also describe a very general linear framework for phase-shifting holographic reconstruction which minimizes additive white Gaussian noise (AWGN) for an arbitrary set of reference field amplitudes and phases. We analyze the technique's sensitivity to noise (AWGN, quantization, and shot), errors in the reference fields, errors in motion estimation, resolution, and depth of field. We also present experimental motion-compensated images achieving the expected resolution.

  17. Amplitude-weighted quadrature phase shift keying using SAW technology

    NASA Astrophysics Data System (ADS)

    Belkerdid, M. A.; Malocha, D. C.

    1985-09-01

    Surface acoustic wave (SAW) convolvers are capable of performing programmable matched filtering with the desirable properties of large processing gain, good dynamic range, broad bandwidth, small size and weight, and low power requirements. Equally powerful are the SAW-based modulators, which produce the desired pseudo-random code sequence for secure transmission in a spread-spectrum system. The SAW filter provides precise reproducible pulse shaping of the coded waveform with the same advantages of the convolver. It is very important as spectrum space becomes more crowded to optimize the spectral efficiency of transmitted information. Quadrature phase (QPSK) and minimum phase shift keying (MSK) are the two more popular quadrature modulation schemes. A new modulation technique that is composed of several amplitude-weighted QPSK signals (AWQPSK) and exhibits better bandwidth efficiency than OPSK or MSK is introduced. System analysis and performance parameters are presented for evaluation. A SAW modulator implementation is discussed and proposed.

  18. Hilbert reconstruction of phase-shifted second-harmonic holographic images.

    PubMed

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

    2012-06-01

    New techniques are presented that make phase-shifting holography viable for second-harmonic generation (SHG) holography with weak object fields. We developed an intrinsic phase shift calibration of SHG holograms, an algorithm that extracts the reference and object intensity directly from a set of phase-shifted holographic data, and a more robust phase-shifting holography reconstruction algorithm based on π-shifted hologram pairs that permits self-calibration of the phase shift and recovery of the complex field through a Hilbert transform.

  19. Improvement of the accuracy of phase observation by modification of phase-shifting electron holography.

    PubMed

    Suzuki, Takahiro; Aizawa, Shinji; Tanigaki, Toshiaki; Ota, Keishin; Matsuda, Tsuyoshi; Tonomura, Akira

    2012-07-01

    We found that the accuracy of the phase observation in phase-shifting electron holography is strongly restricted by time variations of mean intensity and contrast of the holograms. A modified method was developed for correcting these variations. Experimental results demonstrated that the modification enabled us to acquire a large number of holograms, and as a result, the accuracy of the phase observation has been improved by a factor of 5.

  20. Food-deprivation-induced phase shifts in Sminthopsis macroura froggatti.

    PubMed

    Coleman, G J; O'Reilly, H M; Armstrong, S M

    1989-01-01

    Past research has shown that there is a circadian oscillator in laboratory rats that is entrained by restricted feeding schedules. However, in laboratory rats at least, the light-dark (LD) cycle is the dominant zeitgeber in the entrainment of wheel-running activity rhythms. Given that dasyurid marsupials are predominantly carnivorous, the episodic intake of food in the wild and the high nutritive content of that food suggest that food may be an important zeitgeber in these species. Twelve Sminthopsis macroura froggatti were presented with a daily meal at 0900 hr under an LD 12:12 cycle with lights-on at 0600 hr for 37 days. Activity in anticipation of the meal was observed in most animals. Following this, all animals were exposed to periods of 12-18 days ad lib. food interspersed with 3-day periods of deprivation--a technique used previously to demonstrate persistent meal-associated rhythms. The meal-associated activity rhythms previously observed in rats during the 3-day deprivation period were not seen, but the 3-day deprivation period produced large phase-shifts in the activity rhythms of several S.m. froggatti. It is concluded that meal feeding does not dominate the LD cycle in entraining dasyurid marsupials, but that the frequent observation of phase shifts suggests a different and, perhaps, stronger role for food intake in biological rhythmicity than has been observed previously in laboratory rats.

  1. Controllable optical phase shift over one radian from a single isolated atom.

    PubMed

    Jechow, A; Norton, B G; Händel, S; Blūms, V; Streed, E W; Kielpinski, D

    2013-03-15

    Fundamental optics such as lenses and prisms work by applying phase shifts of several radians to incoming light, and rapid control of such phase shifts is crucial to telecommunications. However, large, controllable optical phase shifts have remained elusive for isolated quantum systems. We have used a single trapped atomic ion to induce and measure a large optical phase shift of 1.3±0.1 radians in light scattered by the atom. Spatial interferometry between the scattered light and unscattered illumination light enables us to isolate the phase shift in the scattered component. The phase shift achieves the maximum value allowed by atomic theory over the accessible range of laser frequencies, pointing out new opportunities in microscopy and nanophotonics. Single-atom phase shifts of this magnitude open up new quantum information protocols, in particular long-range quantum phase-shift-keying cryptography.

  2. High-resolution parallel phase-shifting digital holography using a low-resolution phase-shifting array device based on image inpainting.

    PubMed

    Jiao, Shuming; Zou, Wenbin

    2017-02-01

    Parallel phase-shifting digital holography can record high-quality holograms efficiently from fast-moving objects in a dynamic scene. However, a phase-shifting array device with a cell size identical to image sensors is required, which imposes difficulty in practice. This Letter proposes a novel scheme to employ a low-resolution phase-shifting array device to achieve high-resolution parallel phase-shifting digital holography, based on image inpainting performed on incomplete holograms. The experimental results validate the effectiveness of the proposed scheme.

  3. Single-exposure phase-shifting digital holography using a random-phase reference wave.

    PubMed

    Nomura, Takanori; Imbe, Masatoshi

    2010-07-01

    We propose a single-exposure phase-shifting digital holography based on a wave-splitting method using a random-phase reference wave. A random-phase reference wave gives random-phase distribution on the digital hologram. Using the amplitude and the phase distributions of the reference wave, the fully complex amplitude of the object wave is obtained. The proposed method requires not devised optical systems but ordinary imaging devices, such as CCD cameras. A preliminary experimental result is given to confirm the proposed method.

  4. Studies on Phase Shifting Mechanism in Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Padmanabhan; Gurudath, C. S.; Srikanth, Thota; Ambirajan, A.; Basavaraj, SA; Dinesh, Kumar; Venkatarathnam, G.

    2017-02-01

    Pulse Tube cryocoolers (PTC) are being used extensively in spacecraft for applications such as sensor cooling due to their simple construction and long life owing to a fully passive cold head. Efforts at ISRO to develop a PTC for space use have resulted in a unit with a cooling capacity of 1W at 80K with an input of 45watts. This paper presents the results of a study with this PTC on the phase shifting characteristics of an Inertance tube in conjunction with a reservoir. The aim was to obtain an optimum phase angle between the mass flow (ṁ) and dynamic pressure (\\tilde p) at the PT cold end that results in the largest possible heat lift from this unit. Theoretical model was developed using Phasor Analysis and Transmission Line Model (TLM) for different mass flow and values of optimum frequency and phase angles were predicted. They were compared with experimental data from the PTC for different configurations of the Inertance tube/reservoir at various frequencies and charge pressures. These studies were carried out to characterise an existing cryocooler and design an optimised phase shifter with the aim of improving the performance with respect to specific power input.

  5. Two-step phase-shifting interferometry and its application in image encryption

    NASA Astrophysics Data System (ADS)

    Meng, X. F.; Cai, L. Z.; Xu, X. F.; Yang, X. L.; Shen, X. X.; Dong, G. Y.; Wang, Y. R.

    2006-05-01

    Conventional phase-shifting interferometry (PSI) needs at least three interferograms. A novel algorithm of two-step PSI, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. This algorithm is then applied to an information security system based on double random-phase encoding in the Fresnel domain. The feasibility of this method and its robustness against occlusion and additional noise attacks are verified by computer simulations. This approach can considerably improve the efficiency of data transmission and is very suitable for Internet use.

  6. Measurement of longitudinal displacement using lateral shearing cyclic path optical configuration setup and phase shifting interferometry.

    PubMed

    Kumar, Y Pavan; Chatterjee, Sanjib

    2011-04-01

    We present a technique for the measurement of longitudinal displacement using a lateral shearing cyclic path optical configuration (CPOC) setup and phase shifting interferometry. In the technique, a plane mirror mounted on a linear translation stage, placed slightly away from the focal plane of a lens, introduces a longitudinal focal shift to the incident focusing beam. The resulting spherical wavefront emerging from the lens is sheared into two orthogonally polarized beams using the CPOC setup. By applying polarization phase shifting interferometry (PPSI), the longitudinal focal shift of the beam focus is calculated by determining the slope of the optical path difference variation between the sheared beams. Similarly, the additional focal shift introduced due to longitudinal translation of the mirror, by an unknown amount, is determined using PPSI. Half of the difference between the two longitudinal focal shifts measured gives the longitudinal displacement of the mirror. The technique can be used for an extended range of distance measurement. The novelty of the technique is the introduction of CPOC for the distance measurement. The advantages of the technique compared to other related methods are discussed.

  7. Measurement of longitudinal displacement using lateral shearing cyclic path optical configuration setup and phase shifting interferometry

    SciTech Connect

    Kumar, Y. Pavan; Chatterjee, Sanjib

    2011-04-01

    We present a technique for the measurement of longitudinal displacement using a lateral shearing cyclic path optical configuration (CPOC) setup and phase shifting interferometry. In the technique, a plane mirror mounted on a linear translation stage, placed slightly away from the focal plane of a lens, introduces a longitudinal focal shift to the incident focusing beam. The resulting spherical wavefront emerging from the lens is sheared into two orthogonally polarized beams using the CPOC setup. By applying polarization phase shifting interferometry (PPSI), the longitudinal focal shift of the beam focus is calculated by determining the slope of the optical path difference variation between the sheared beams. Similarly, the additional focal shift introduced due to longitudinal translation of the mirror, by an unknown amount, is determined using PPSI. Half of the difference between the two longitudinal focal shifts measured gives the longitudinal displacement of the mirror. The technique can be used for an extended range of distance measurement. The novelty of the technique is the introduction of CPOC for the distance measurement. The advantages of the technique compared to other related methods are discussed.

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

    NASA Astrophysics Data System (ADS)

    Cheng, Bing; Wang, Zhao-Ying; Xu, Ao-Peng; Wang, Qi-Yu; Lin, Qiang

    2015-11-01

    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. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174249 and 61475139), the Ministry of Science and Technology of China (Grant No. 2011AA060504), the National Basic Research Program of China (Grant No. 2013CB329501), and the Fundamental Research Funds for the Central Universities, China (Grant No. 2015FZA3002).

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  10. Digital phase-shifting interferometer with an electrically addressed liquid-crystal spatial light modulator.

    PubMed

    Bitou, Youichi

    2003-09-01

    A digital phase-shifting interferometer with a liquid-crystal-display coupled, parallel aligned, nematic liquid-crystal spatial light modulator is developed. The optical phase shift in the Michelson-type polarization interferometer is achieved by a digital phase shift of a grating displayed on the spatial light modulator. Accurate experimental results of using the heterodyne system for pi/2 phase steps were demonstrated. A phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shift was achieved.

  11. Chromatic-dispersion measurement by modulation phase-shift method using a Kerr phase-interrogator.

    PubMed

    Baker, Chams; Lu, Yang; Bao, Xiaoyi

    2014-09-22

    We present a novel approach for the measurement of chromatic-dispersion in long optical fibers using a modulation phase-shift method based on a Kerr phase-interrogator. This approach utilizes a Kerr phase-interrogator to measure the phase variation of a sinusoidal optical signal induced by traveling in a fiber under test as the laser carrier wavelength and the sinusoidal signal frequency are varied. Chromatic-dispersion measurement for several fibers including a standard single-mode silica fiber and a dispersion-shifted fiber is experimentally demonstrated. The ultrafast response of the Kerr phase-interrogator opens the way for real-time monitoring of chromatic-dispersion in kilometers-long optical fibers.

  12. Simple, flexible, and accurate phase retrieval method for generalized phase-shifting interferometry.

    PubMed

    Yatabe, Kohei; Ishikawa, Kenji; Oikawa, Yasuhiro

    2017-01-01

    This paper presents a non-iterative phase retrieval method from randomly phase-shifted fringe images. By combining the hyperaccurate least squares ellipse fitting method with the subspace method (usually called the principal component analysis), a fast and accurate phase retrieval algorithm is realized. The proposed method is simple, flexible, and accurate. It can be easily coded without iteration, initial guess, or tuning parameter. Its flexibility comes from the fact that totally random phase-shifting steps and any number of fringe images greater than two are acceptable without any specific treatment. Finally, it is accurate because the hyperaccurate least squares method and the modified subspace method enable phase retrieval with a small error as shown by the simulations. A MATLAB code, which is used in the experimental section, is provided within the paper to demonstrate its simplicity and easiness.

  13. Determination of displacement with a piezoelectric transducer using phase-shift algorithms

    NASA Astrophysics Data System (ADS)

    Jaing, Cheng-Chung; Shie, Yi-Lin; Tang, Chien-Jen; Liou, Yeuh-Yeong; Chang, Chun-Ming; Yang, Chii-Rong

    2009-03-01

    This investigation accurately measures the relationship between applied voltage and the displacement of a piezoelectric transducer device both by analyzing phase shifting interferometry algorithms and using a Twyman-Green interferometer. Simulations are performed to calculate unknown phase shifts, especially around π/2 and 3 π/2. It is indicated that the Hariharan algorithm is indeed an effective phase shifting interferometry algorithm.

  14. Phase-shifting by means of an electronically tunable lens: quantitative phase imaging of biological specimens with digital holographic microscopy.

    PubMed

    Trujillo, Carlos; Doblas, Ana; Saavedra, Genaro; Martínez-Corral, Manuel; García-Sucerquia, Jorge

    2016-04-01

    The use of an electronically tunable lens (ETL) to produce controlled phase shifts in interferometric arrangements is shown. The performance of the ETL as a phase-shifting device is experimentally validated in phase-shifting digital holographic microscopy. Quantitative phase maps of a section of the thorax of a Drosophila melanogaster fly and of human red blood cells have been obtained using our proposal. The experimental results validate the possibility of using the ETL as a reliable phase-shifter device.

  15. Phase-shifting point-diffraction interferometry at EUV wavelengths

    SciTech Connect

    Goldberg, K.A.; Tejnil, E.; Sang Lee

    1997-04-01

    A novel phase-shifting point-diffraction interferometer (PS/PDI) operating at the Advanced Light Source (ALS) is being used to perform wavefront-measuring metrology at 13.4-nm wavelength to characterize aberrations in a multilayer-coated 10x Schwarzschild objective designed for extreme ultraviolet (EUV) projection lithography experiments. To achieve 0.1-micron critical dimension pattern transfer with EUV projection lithography at 13.4-nm wavelength, nearly diffraction-limited all-reflective multilayer-coated optical systems with 0.1 numerical aperture are required. The EUV wavefront, determined by the mirror surfaces and the reflective multilayer coatings, is measurable only at the operational wavelength of the system. The authors goal is to measure the EUV wavefront to an accuracy of 0.01 waves rms (0.13 nm). The PS/PDI is a type of point-diffraction interferometer, modified for significantly improved throughput and phase-shifting capability. The interferometer design utilizes a grating beamsplitter and pinhole spatial filters in the object and image planes of the optical system under test. The 10x-reduction Schwarzschild objective, with image-side numerical aperture of 0.08, is illuminated by a sub-micron pinhole in the object plane. A coarse, 20-micron pitch grating placed between the illumination pinhole and the Schwarzschild system serves a dual role as a small-angle beam-splitter and a phase-shifting element. The first-order diffracted beam from the grating is spatially filtered in the image plane of the Schwarzschild with a sub-100-nm pinhole and becomes the `D reference` wave in the interferometer. The zero-order beam is the `test` wave, and it passes unobstructed through a 4.5-{mu}m window in the image plane. The test and reference beams are separated by several microns in the image plane to minimize beam overlap. The interference fringes are recorded with a CCD detector placed about 12 cm from the Schwarzschild image plane.

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

    NASA Astrophysics Data System (ADS)

    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

    2016-05-01

    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.

  17. Gouy phase shift for annular beam profiles in attosecond experiments.

    PubMed

    Schlaepfer, F; Ludwig, A; Lucchini, M; Kasmi, L; Volkov, M; Gallmann, L; Keller, U

    2017-02-20

    Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-harmonic generation (HHG). Furthermore, the strong absorption of materials at the extreme ultraviolet (XUV) wavelengths of the attosecond pulses typically prevents the use of transmissive optics. As a result, pump and probe beams are typically recombined geometrically with a center-hole mirror that reflects the larger IR beam and transmits the smaller XUV, which leads to an annular beam profile of the IR. This modification of the IR beam can affect the pump-probe measurements because the propagation that follows the reflection on the center-hole mirror can strongly deviate from that of an ideal Gaussian beam. Here we present a detailed experimental study of the Gouy phase of an annular IR beam across the focus using a two-foci attosecond beamline and the RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) technique. Our measurements show a Gouy phase shift of the truncated beam as large as 2π and a corresponding rate of 50 as/mm time delay change across the focus in a RABBITT measurement. These results are essential for attosecond pump-probe experiments that compare measurements of spatially separated targets.

  18. Potential energy function information from quantum phase shift using the variable phase method.

    PubMed

    Lemes, Nelson H T; Braga, João P; Alves, Márcio O; Costa, Éderson D'M

    2014-07-01

    The present work discusses quantum phase shift sensitivity analysis with respect to the potential energy function. A set of differential equations for the functional derivative of the quantum phase shift with respect to the potential energy function was established and coupled with the variable phase equation. This set of differential equations provides a simple, exact and straightforward way to establish the sensitivity matrix. The present procedure is easier to use than the finite difference approach, in which several direct problems have to be addressed. Furthermore, integration of the established equations can be used to demonstrate how the sensitivity phase shift is accumulated as a function of the interatomic distance. The potential energy function was refined to produce a better quality function. The average error on the phase shift decreased from 9.8% in the original potential function to 0.13% in the recovered potential. The present procedure is an important initial step for further work towards recovering potential energy functions in upper dimensions or to recovering this function from cross sections.

  19. Stochastic characterization of phase detection algorithms in phase-shifting interferometry

    SciTech Connect

    Munteanu, Florin

    2016-11-01

    Phase-shifting interferometry (PSI) is the preferred non-contact method for profiling sub-nanometer surfaces. Based on monochromatic light interference, the method computes the surface profile from a set of interferograms collected at separate stepping positions. Errors in the estimated profile are introduced when these positions are not located correctly. In order to cope with this problem, various algorithms that minimize the effects of certain types of stepping errors (linear, sinusoidal, etc.) have been developed. Despite the relatively large number of algorithms suggested in the literature, there is no unified way of characterizing their performance when additional unaccounted random errors are present. Here, we suggest a procedure for quantifying the expected behavior of each algorithm in the presence of independent and identically distributed (i.i.d.) random stepping errors, which can occur in addition to the systematic errors for which the algorithm has been designed. As a result, the usefulness of this method derives from the fact that it can guide the selection of the best algorithm for specific measurement situations.

  20. Stochastic characterization of phase detection algorithms in phase-shifting interferometry

    DOE PAGES

    Munteanu, Florin

    2016-11-01

    Phase-shifting interferometry (PSI) is the preferred non-contact method for profiling sub-nanometer surfaces. Based on monochromatic light interference, the method computes the surface profile from a set of interferograms collected at separate stepping positions. Errors in the estimated profile are introduced when these positions are not located correctly. In order to cope with this problem, various algorithms that minimize the effects of certain types of stepping errors (linear, sinusoidal, etc.) have been developed. Despite the relatively large number of algorithms suggested in the literature, there is no unified way of characterizing their performance when additional unaccounted random errors are present. Here,more » we suggest a procedure for quantifying the expected behavior of each algorithm in the presence of independent and identically distributed (i.i.d.) random stepping errors, which can occur in addition to the systematic errors for which the algorithm has been designed. As a result, the usefulness of this method derives from the fact that it can guide the selection of the best algorithm for specific measurement situations.« less

  1. Common path point diffraction interferometer using liquid crystal phase shifting

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R. (Inventor)

    1997-01-01

    A common path point diffraction interferometer uses dyed, parallel nematic liquid crystals which surround an optically transparent microsphere. Coherent, collimated and polarized light is focused on the microsphere at a diameter larger than that of the microsphere. A portion of the focused light passes through the microsphere to form a spherical wavefront reference beam and the rest of the light is attenuated by the dyed liquid crystals to form an object beam. The two beams form an interferogram which is imaged by a lens onto an electronic array sensor and into a computer which determines the wavefront of the object beam. The computer phase shifts the interferogram by stepping up an AC voltage applied across the liquid crystals without affecting the reference beam.

  2. Phase shifting and phase retrieval with a fully automated laser diode system.

    PubMed

    Rivera-Ortega, Uriel; Dirckx, Joris; Meneses-Fabian, Cruz

    2015-11-20

    A low-cost and fully automated process for phase-shifting interferometry (PSI) by continuously changing the input voltage of a laser diode (LD) under the scheme of an unbalanced Twyman-Green interferometer (TGI) setup is presented. The input signal of a LD is controlled by a data acquisition (NI-DAQ) device that allows it to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. The phase map is obtained using the Carré algorithm. Measurements of visibility and phase shift to verify the PSI requirements are shown. It is demonstrated with experimental results and statistical analysis that the phase retrieval can be successfully achieved without calibration and using minimal optical devices.

  3. Bone resorption is affected by follicular phase length in female rotating shift workers.

    PubMed Central

    Lohstroh, Pete N; Chen, Jiangang; Ba, Jianming; Ryan, Louise M; Xu, Xiping; Overstreet, James W; Lasley, Bill L

    2003-01-01

    Stressors as subtle as night work or shift work can lead to irregular menstrual cycles, and changes in reproductive hormone profiles can adversely affect bone health. This study was conducted to determine if stresses associated with the disruption of regular work schedule can induce alterations in ovarian function which, in turn, are associated with transient bone resorption. Urine samples from 12 rotating shift workers from a textile mill in Anqing, China, were collected in 1996-1998 during pairs of sequential menstrual cycles, of which one was longer than the other (28.4 vs. 37.4 days). Longer cycles were characterized by a prolonged follicular phase. Work schedules during the luteal-follicular phase transition (LFPT) preceding each of the two cycles were evaluated. All but one of the shorter cycles were associated with regular, forward phase work shift progression during the preceding LFPT. In contrast, five longer cycles were preceded by a work shift interrupted either by an irregular shift or a number of "off days." Urinary follicle-stimulating hormone levels were reduced in the LFPT preceding longer cycles compared with those in the LFPT preceding shorter cycles. There was greater bone resorption in the follicular phase of longer cycles than in that of shorter cycles, as measured by urinary deoxypyridinoline. These data confirm reports that changes in work shift can lead to irregularity in menstrual cycle length. In addition, these data indicate that there may be an association between accelerated bone resorption in menstrual cycles and changes of regularity in work schedule during the preceding LFPT. PMID:12676625

  4. Direct unwrapped phase estimation in phase shifting interferometry using Levenberg-Marquardt algorithm

    NASA Astrophysics Data System (ADS)

    Kulkarni, Rishikesh; Rastogi, Pramod

    2017-01-01

    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.

  5. Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis

    NASA Astrophysics Data System (ADS)

    Singh Mehta, Dalip; Srivastava, Vishal

    2012-11-01

    We report quantitative phase imaging of human red blood cells (RBCs) using phase-shifting interference microscopy. Five phase-shifted white light interferograms are recorded using colour charge coupled device camera. White light interferograms were decomposed into red, green, and blue colour components. The phase-shifted interferograms of each colour were then processed by phase-shifting analysis and phase maps for red, green, and blue colours were reconstructed. Wavelength dependent refractive index profiles of RBCs were computed from the single set of white light interferogram. The present technique has great potential for non-invasive determination of refractive index variation and morphological features of cells and tissues.

  6. Alleviation of additional phase noise in fiber optical parametric amplifier based signal regenerator.

    PubMed

    Jin, Lei; Xu, Bo; Yamashita, Shinji

    2012-11-19

    We theoretically and numerically explain the power saturation and the additional phase noise brought by the fiber optical parametric amplifier (FOPA). An equation to calculate an approximation to the saturated signal output power is presented. We also propose a scheme for alleviating the phase noise brought by the FOPA at the saturated state. In simulation, by controlling the decisive factor dispersion difference term Δk of the FOPA, amplitude-noise and additional phase noise reduction of quadrature phase shift keying (QPSK) based on the saturated FOPA is studied, which can provide promising performance to deal with PSK signals.

  7. Fast Reference Phase Extraction and Wave-front Reconstruction for Generalized Phase-shifting Interferometry

    NASA Astrophysics Data System (ADS)

    Xu, Xian-Feng; Cai, Lu-Zhong; Wang, Yu-Rong; Li, Dai-Lin; Yan, Ru-Sen

    2010-04-01

    An important approach of complex wave reconstruction in generalized phase-shifting interferometry (GPSI) with arbitrary unknown phase shifts is the combination of two (a conventional and an inverse) least square methods (LSMs), where the conventional LSM requires the calculation of solving a set of least square equations for each pixel in each iteration, giving rise to a heavy computation burden. Here a much-simplified algorithm is suggested to extract reference phase and then reconstruct object wave-front by replacing the conventional LSM in above process with our specially derived wave reconstruction formulae for GPSI. In this method, only one least-square equation is needed in each iteration to retrieve the reference phase, and the object phase can be calculated analytically and simultaneously. The feasibility and effectiveness of this algorithm have been verified by computer simulations with both the smooth and diffusing objects. The results show that this innovation can save computing time by about 20 times compared with previous two-LSM algorithm while still ensures its high precision. This approach can be used for GPSI with three or more frames in the wide range of unknown positive or negative phase shifts. Optical experiments have also made with satisfactory results.

  8. Compensation algorithm for the phase-shift error of polarization-based parallel two-step phase-shifting digital holography.

    PubMed

    Tahara, Tatsuki; Ito, Kenichi; Kakue, Takashi; Fujii, Motofumi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-03-01

    We propose an algorithm for compensating the phase-shift error of polarization-based parallel two-step phase-shifting digital holography, which is a technique for recording a spatial two-step phase-shifted hologram. Although a polarization-based system of the technique has been experimentally demonstrated, there had been the problem that the phase difference of two phase-shifted holograms had been changed by the extinction ratio of the micropolarizer array attached to the image sensor used in the system. To improve the performance of the system, we established and formulated an algorithm for compensating the phase-shift error. Accurate spatial phase-shifting interferometry in the system can be conducted by the algorithm regardless of phase-shift error due to the extinction ratio. By the numerical simulation, the proposed algorithm was capable of reducing the root mean square errors of the reconstructed image by 1/4 and 1/5 in amplitude and phase, respectively. Also, the algorithm was experimentally demonstrated, and the experimental results showed that the system employing the proposed algorithm suppressed the conjugate image, which slightly appeared in the image reconstructed by the system not employing the algorithm, even when the extinction ratio was 10:1. Thus, the effectiveness of the proposed algorithm was numerically and experimentally verified.

  9. Simultaneous multi-wavelength phase-shifting interferometry based on principal component analysis with a color CMOS

    NASA Astrophysics Data System (ADS)

    Fan, Jingping; Lu, Xiaoxu; Xu, Xiaofei; Zhong, Liyun

    2016-05-01

    From a sequence of simultaneous multi-wavelength phase-shifting interferograms (SMWPSIs) recorded by a color CMOS, a principal component analysis (PCA) based multi-wavelength interferometry (MWI) is proposed. First, a sequence of SMWPSIs with unknown phase shifts are recorded with a single-chip color CMOS camera. Subsequently, the wrapped phases of single-wavelength are retrieved with the PCA algorithm. Finally, the unambiguous phase of the extended synthetic wavelength is achieved by the subtraction between the wrapped phases of single-wavelength. In addition, to eliminate the additional phase introduced by the microscope and intensity crosstalk among three-color channels, a two-step phase compensation method with and without the measured object in the experimental system is employed. Compared with conventional single-wavelength phase-shifting interferometry, due to no requirements for phase shifts calibration and the phase unwrapping operation, the actual unambiguous phase of the measured object can be achieved with the proposed PCA-based MWI method conveniently. Both numerical simulations and experimental results demonstrate that the proposed PCA-based MWI method can enlarge not only the measuring range, but also no amplification of noise level.

  10. Monitoring and evaluation of drying of paint by using phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Yokota, Masayuki

    2010-01-01

    We propose a novel method for monitoring the drying process of a painted surface by using phase-shifting digital holography. In comparison with previous methods using speckle patterns, the proposed method can afford an intensity image for directly monitoring and local variations of drying without an imaging lens. It can also be used for surfaces of complex shapes. In addition, quantitative analysis utilizing a cross-correlation function and phase change derived from the reconstructed complex amplitude is performed and the drying time of paint for different areas and temperature is evaluated. The technique is also applied to monitoring the drying process of a complex surface of a lightbulb.

  11. Image reconstruction only by phase data in phase-shifting digital holography.

    PubMed

    Yamaguchi, Ichirou; Yamamoto, Kazuhiro; Mills, Godfrey A; Yokota, Masayuki

    2006-02-10

    We describe data compression in phase-shifting digital holography. We demonstrate by experimentation that an image of a diffusely reflecting object can be reconstructed only by phase data of the derived complex amplitude. It is shown that reduction of the bit depth of the phase data does not seriously damage the image even down to 1 bit. We observe enhancement of halo in the image with low bit depths. This tendency is verified quantitatively by a one-dimensional simulation. Our procedure for smoothing the images that result from the data-compression methods is shown to be effective.

  12. Statistical study of generalized nonlinear phase step estimation methods in phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Langoju, Rajesh; Patil, Abhijit; Rastogi, Pramod

    2007-11-01

    Signal processing methods based on maximum-likelihood theory, discrete chirp Fourier transform, and spectral estimation methods have enabled accurate measurement of phase in phase-shifting interferometry in the presence of nonlinear response of the piezoelectric transducer to the applied voltage. We present the statistical study of these generalized nonlinear phase step estimation methods to identify the best method by deriving the Cramér-Rao bound. We also address important aspects of these methods for implementation in practical applications and compare the performance of the best-identified method with other bench marking algorithms in the presence of harmonics and noise.

  13. Statistical study of generalized nonlinear phase step estimation methods in phase-shifting interferometry

    SciTech Connect

    Langoju, Rajesh; Patil, Abhijit; Rastogi, Pramod

    2007-11-20

    Signal processing methods based on maximum-likelihood theory, discrete chirp Fourier transform, and spectral estimation methods have enabled accurate measurement of phase in phase-shifting interferometry in the presence of nonlinear response of the piezoelectric transducer to the applied voltage. We present the statistical study of these generalized nonlinear phase step estimation methods to identify the best method by deriving the Cramer-Rao bound. We also address important aspects of these methods for implementation in practical applications and compare the performance of the best-identified method with other bench marking algorithms in the presence of harmonics and noise.

  14. Investigation of phase error correction for digital sinusoidal phase-shifting fringe projection profilometry

    NASA Astrophysics Data System (ADS)

    Ma, S.; Quan, C.; Zhu, R.; Tay, C. J.

    2012-08-01

    Digital sinusoidal phase-shifting fringe projection profilometry (DSPFPP) is a powerful tool to reconstruct three-dimensional (3D) surface of diffuse objects. However, a highly accurate profile is often hindered by nonlinear response, color crosstalk and imbalance of a pair of digital projector and CCD/CMOS camera. In this paper, several phase error correction methods, such as Look-Up-Table (LUT) compensation, intensity correction, gamma correction, LUT-based hybrid method and blind phase error suppression for gray and color-encoded DSPFPP are described. Experimental results are also demonstrated to evaluate the effectiveness of each method.

  15. An OADM based on phase-shifted fiber grating and Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Huang, Yonglin; Xiao, Qichen

    2017-01-01

    In order to study the properties of phase-shifted fiber Bragg grating, The reflection spectrum characteristic of phase-shifted fiber grating with different fiber grating length, different refractive index modulation depth and different shift angle are analyzed using transmission matrix method. A new scheme of optical add-drop multiplexer based on phase-shifted fiber Bragg grating and Mach-Zehnder interferometer is proposed and simulated. The reflection spectrum of phase-shifted fiber grating is optimized using Gauss apodization function. Two channel signals can be dropped simultaneously. This study may provide theory instruction for the application of the OADM.

  16. Electron Phase Shift at the Zero-Bias Anomaly of Quantum Point Contacts.

    PubMed

    Brun, B; Martins, F; Faniel, S; Hackens, B; Cavanna, A; Ulysse, C; Ouerghi, A; Gennser, U; Mailly, D; Simon, P; Huant, S; Bayot, V; Sanquer, M; Sellier, H

    2016-04-01

    The Kondo effect is the many-body screening of a local spin by a cloud of electrons at very low temperature. It has been proposed as an explanation of the zero-bias anomaly in quantum point contacts where interactions drive a spontaneous charge localization. However, the Kondo origin of this anomaly remains under debate, and additional experimental evidence is necessary. Here we report on the first phase-sensitive measurement of the zero-bias anomaly in quantum point contacts using a scanning gate microscope to create an electronic interferometer. We observe an abrupt shift of the interference fringes by half a period in the bias range of the zero-bias anomaly, a behavior which cannot be reproduced by single-particle models. We instead relate it to the phase shift experienced by electrons scattering off a Kondo system. Our experiment therefore provides new evidence of this many-body effect in quantum point contacts.

  17. Phase shift between respiratory oscillations in cerebral blood flow velocity and arterial blood pressure.

    PubMed

    Uryga, Agnieszka; Placek, Michał M; Wachel, Paweł; Szczepański, Tomasz; Czosnyka, Marek; Kasprowicz, Magdalena

    2017-02-01

    We aim to investigate whether phase shift between respiratory oscillations in cerebral blood flow velocity (CBFV) and arterial blood pressure (ABP) is associated with changes in cerebral autoregulation (CA) or reflects the mechano-elastic properties of the cerebrovascular bed. The relationships between respiratory phase shift and slow wave phase shift versus cerebrovascular time constant (the product of cerebrovascular resistance and compliance) and the index of CA (Mx) were analyzed during breathing at 6, 10, and 15 breaths min(-1) in 39 volunteers. With increasing respiratory rate the time constant, Mx, and respiratory phase shift decreased, whereas slow wave phase shift increased. The time constant correlated moderately strongly with the respiratory phase shift (R  =  0.49, p [Formula: see text] 0.001) and did not correlate with the slow wave phase shift. The slow wave phase shift was significantly associated with Mx (R  =  -0.46, p [Formula: see text] 0.001). The respiratory phase shift more accurately reflects the mechano-elastic properties of the cerebrovascular bed, whereas CA is better described by the slow wave phase shift.

  18. Statistical generalized phase-shifting digital holography with a continuous fringe-scanning scheme.

    PubMed

    Yoshikawa, Nobukazu; Kajihara, Kazuki

    2015-07-01

    We propose a novel statistical generalized phase-shifting digital holography using a continuous fringe-scanning scheme. In this method, the continuous fringe-scanning scheme is implemented using a PC-based measurement system without any synchronous circuit between the digital camera and the phase shifter. Thus, nonuniformly phase-shifted interference fringes are captured sequentially because of the fluctuation of the image-capturing interval. To cope with the nonuniform phase shifts, we employ a statistical generalized phase-shifting approach. Since the algorithm is designed to use an arbitrary phase shift, the nonuniform phase shifts do not obstruct object wave retrieval. Simulations and experiments demonstrate that the proposed method can be used to implement a practical and accurate digital holography system.

  19. A method of hard X-ray phase-shifting digital holography.

    PubMed

    Park, So Yeong; Hong, Chung Ki; Lim, Jun

    2016-07-01

    A new method of phase-shifting digital holography is demonstrated in the hard X-ray region. An in-line-type phase-shifting holography setup was installed in a 6.80 keV hard X-ray synchrotron beamline. By placing a phase plate consisting of a hole and a band at the focusing point of a Fresnel lens, the relative phase of the reference and objective beams could be successfully shifted for use with a three-step phase-shift algorithm. The system was verified by measuring the shape of a gold test pattern and a silica sphere.

  20. Measuring atmospheric visibility cavity attenuated phase shift spectroscopy

    NASA Astrophysics Data System (ADS)

    Jie, Guo; Ye, Shan-Shan; Yang, Xiao; Han, Ye-Xing; Tang, Huai-Wu; Yu, Zhi-Wei

    2016-10-01

    In the paper, an accurate and sensitive cavity attenuated phase shift spectroscopy (CAPS) system was used to monitor the atmospheric visibility coefficient in urban areas. The CAPS system, which detects the atmospheric visibility within a 10 nm bandpass centered at 532 nm, comprises a green LED with center wavelength in 532nm, a resonant optical cavity (36 cm length), a Photo Multiplier Tube detector and a lock in amplifier. The performance of the CAPS system was evaluated by measuring of the stability and response of the system. The minima ( 0.06 Mm-1) in the Allan plots show the optimum average time( 80s) for optimum detection performance of the CAPS system. The 2L/min flow rate, the CAPS system rise and fall response time is about 15 s, so as to realize the fast measurement of visibility. By comparing the forward scatter visibility meter measurement results, the CAPS system measurement results are verified reliably, and have high precision measurement. These figures indicate that this method has the potential to become one of the most sensitive on-line analytical techniques for atmospheric visibility detection.

  1. Design optimization of phase-shifting point diffraction interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Li, Yanqiu

    2008-12-01

    The phase-shifting point diffraction interferometer (PS/PDI) is so far the most accurate measurement tool in atwavelength interferometry of projection optics for extreme ultraviolet lithography (EUVL). The complicate interrelationships between configuration parameters of PS/PDI call for an optimization to achieve high accuracy of PS/PDI. In this paper, a novel system-level modeling approach is proposed to optimize the parameters of PS/PDI designed for visible light (λ=632.8nm) concept proof experiment. The optimal reference pinhole size selection is performed by modeling pinhole spatial filtering effect using Diffraction-Based Beam Propagation (BPR) module of CODE V and in house software. The result shows that various pinhole diameters ranging from 1.6um to 2.2um should be used in our PS/PDI experiment. The test window size and grating duty cycle optimization, which is based on the spatial frequency domain analysis of PS/PDI, is conducted by modeling the entire PS/PDI system using Physical Optics Propagation (POP) module of Zemax and in house software. The optimal window size is approximately 62um for a given window-pinhole separation of 63.3um. The optimal duty cycle of grating is calculated to be 83% to obtain the maximum fringe contrast of 0.879.

  2. Two-shot common-path phase-shifting interferometer with a four-step algorithm and an unknown phase shift.

    PubMed

    Zhong, Zhi; Hao, Bengong; Shan, Mingguang; Wang, Ying; Diao, Ming; Zhang, Yabin

    2014-04-01

    This paper presents a two-shot common-path phase-shifting interferometer that consists of a 4f optical system with two windows in the input plane and a Ronchi grating in the Fourier plane, and generates two adjacent interferograms using only diffraction orders 0 and +1 and 0 and -1. Four phase-shifted interferograms can be obtained in two shots by modulating two linear polarizers with angle difference of π/4 and translating the grating with only an unknown phase shift. An algorithm similar to the standard four-step algorithm is used to retrieve the phase of a specimen, and it requires no knowledge of the phase shift introduced by translation of the grating. The validity and repeatability of the proposed method is proved through simulations and experiments.

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

    NASA Astrophysics Data System (ADS)

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

    1999-07-01

    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.

  4. Multi-spatial-frequency and phase-shifting profilometry using a liquid crystal phase modulator.

    PubMed

    Joo, Kyung-Il; Park, Chang-Sub; Park, Min-Kyu; Park, Kyung-Woo; Park, Ji-Sub; Seo, Youngmin; Hahn, Joonku; Kim, Hak-Rin

    2012-05-10

    Optical profilometry is widely applied for measuring the morphology of objects by projecting predetermined patterns on them. In this technique, the compact size is one of the interesting issues for practical applications. The generation of pattern by the interference of coherent light sources has a potential to reduce the dimension of the illumination part. Moreover, this method can make fine patterns without projection optics, and the illumination part is free of restriction from the numerical aperture of the projection optics. In this paper, a phase-shifting profilometry is implemented by using a single liquid crystal (LC) cell. The LC phase modulator is designed to generate the interference patterns with several different spatial frequencies by changing selection of the spacing between the micro-pinholes. We manufactured the LC phase modulator and calibrated it by measuring the phase modulation amount depending on an applied voltage. Our optical profilometry using the single LC cell can generate multi-spatial frequency patterns as well as four steps of the phase-shifted patterns. This method can be implemented compactly, and the reconstructed depth profile is obtained without a phase-unwrapping algorithm.

  5. Spatial-carrier phase-shifting digital holography utilizing spatial frequency analysis for the correction of the phase-shift error.

    PubMed

    Tahara, Tatsuki; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu; Kubota, Toshihiro

    2012-01-15

    We propose a single-shot digital holography in which the complex amplitude distribution is obtained by spatial-carrier phase-shifting (SCPS) interferometry and the correction of the inherent phase-shift error occurred in this interferometry. The 0th order diffraction wave and the conjugate image are removed by phase-shifting interferometry and Fourier transform technique, respectively. The inherent error is corrected in the spatial frequency domain. The proposed technique does not require an iteration process to remove the unwanted images and has an advantage in the field of view in comparison to a conventional SCPS technique.

  6. Adduct Formation in ESI/MS by Mobile Phase Additives

    NASA Astrophysics Data System (ADS)

    Kruve, Anneli; Kaupmees, Karl

    2017-03-01

    Adduct formation is a common ionization method in electrospray ionization mass spectrometry (ESI/MS). However, this process is poorly understood and complicated to control. We demonstrate possibilities to control adduct formation via mobile phase additives in ESI positive mode for 17 oxygen and nitrogen bases. Mobile phase additives were found to be a very effective measure for manipulating the formation efficiencies of adducts. An appropriate choice of additive may increase sensitivity by up to three orders of magnitude. In general, sodium adduct [M + Na]+ and protonated molecule [M + H]+ formation efficiencies were found to be in good correlation; however, the former were significantly more influenced by mobile phase properties. Although the highest formation efficiencies for both species were observed in water/acetonitrile mixtures not containing additives, the repeatability of the formation efficiencies was found to be improved by additives. It is concluded that mobile phase additives are powerful, yet not limiting factors, for altering adduct formation.

  7. Scheme to improve the reconstructed image in parallel quasi-phase-shifting digital holography.

    PubMed

    Awatsuji, Yasuhiro; Sasada, Masaki; Fujii, Atsushi; Kubota, Toshihiro

    2006-02-10

    We propose a scheme to improve the reconstructed image in parallel quasi-phase-shifting digital holography. Parallel quasi-phase-shifting digital holography is a technique capable of noiseless instantaneous measurement of three-dimensional objects, and it implements four kinds of phase shifting at a time with an array of 2 x 2 phase-shifting devices located in the reference wave. In the phase-shifting calculation in the reconstruction process of the technique, the scheme assigns the 2 x 2 cell configuration for each pixel in the vertical direction and for each 1-pixel interval in the horizontal direction of the hologram recorded by the image sensor. We conduct both a numerical simulation and a preliminary experiment. The results show that the proposed scheme can improve the quality of the reconstructed image calculated by the conventional scheme of parallel quasi-phase-shifting digital holography we previously proposed, and then the effectiveness of the proposed scheme is verified.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    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.

  9. Selecting efficient phase estimation with constant-precision phase shift operators

    NASA Astrophysics Data System (ADS)

    Chiang, Chen-Fu

    2013-10-01

    We investigate the cost of three phase estimation procedures that require only constant-precision phase shift operators. The cost is in terms of the number of elementary gates, not just the number of measurements. Faster phase estimation requires the minimal number of measurements with a logarithmic factor of reduction when the required precision n is large. The arbitrary constant-precision approach (ACPA) requires the minimal number of elementary gates with a minimal factor of 14 of reduction in comparison with Kitaev's approach. The reduction factor increases as the precision gets higher in ACPA. Kitaev's approach is with a reduction factor of 14 in comparison with the faster phase estimation in terms of elementary gate counts.

  10. Complete presentation of the Gouy phase shift with the THz digital holography.

    PubMed

    Wang, Xinke; Sun, Wenfeng; Cui, Ye; Ye, Jiasheng; Feng, Shengfei; Zhang, Yan

    2013-01-28

    Three dimensional information of the Gouy phase shift in a converging spherical terahertz (THz) beam is directly observed by using a THz balanced electro-optic holographic imaging system. The major properties of the Gouy phase shift are presented, including the longitudinal and transverse distributions, relationships with the frequency and the f-number, influence on the THz polarization. The imaging technique supplies an accurate and comprehensive measurement method for observing and understanding the Gouy phase shift.

  11. Simultaneous phase-shifting interferometry based on high-speed CCD

    NASA Astrophysics Data System (ADS)

    Zuo, Fen; Chen, Lei; Xu, Chunsheng

    2007-01-01

    A new simultaneous phase-shifting measuring method based on Twyman-Green polarization phase- shifting technique is presented. In the corresponding set-up, a 2-dimentional grating is applied. By the grating, 4 diffracted beams of (+/-1, +/-1) orders are formed for the same diffracting efficiency. Each is let to pass one of four polarizing plates respectively, polarization directions of which differ in turn by 45°. So four interferograms with 90°phase-shifting interval are frozen simultaneously by a high-speed CCD, which has short exposure of 1/10000 s. Moreover, by the use of 4-bucket algorithm, a profile of the test surface is thus derived. Meantime, the system is deposited on a vibration-isolate flat, and the structure of an ordinary piezoelectric transducer (PZT), with a time response above 1000 Hz at amplitude of λ/2, is used to simulate an epicenter, the frequency of which varying from 10 Hz to 200 Hz. In addition, the experimental results reveal that the advanced system has a high testing precision and testing repeatability in the vibrational environment whose amplitude- frequency product is less than 100 Wave-Hertz. Therefore, the proposed system has enough endurance to the vibration during on-line optical testing.

  12. Black reefs: iron-induced phase shifts on coral reefs.

    PubMed

    Kelly, Linda Wegley; Barott, Katie L; Dinsdale, Elizabeth; Friedlander, Alan M; Nosrat, Bahador; Obura, David; Sala, Enric; Sandin, Stuart A; Smith, Jennifer E; Vermeij, Mark J A; Williams, Gareth J; Willner, Dana; Rohwer, Forest

    2012-03-01

    The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to <10% on black 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.

  13. Hybrid shearing and phase-shifting point diffraction interferometer

    DOEpatents

    Goldberg, Kenneth Alan; Naulleau, Patrick P.

    2003-06-03

    A new interferometry configuration combines the strengths of two existing interferometry methods, improving the quality and extending the dynamic range of both. On the same patterned mask, placed near the image-plane of an optical system under test, patterns for phase-shifting point diffraction interferometry and lateral shearing interferometry coexist. The former giving verifiable high accuracy for the measurement of nearly diffraction-limited optical systems. The latter enabling the measurement of optical systems with more than one wave of aberration in the system wavefront. The interferometry configuration is a hybrid shearing and point diffraction interferometer system for testing an optical element that is positioned along an optical path including: a source of electromagnetic energy in the optical path; a first beam splitter that is secured to a device that includes means for maneuvering the first beam splitter in a first position wherein the first beam splitter is in the optical path dividing light from the source into a reference beam and a test beam and in a second position wherein the first beam splitter is outside the optical path: a hybrid mask which includes a first section that defines a test window and at least one reference pinhole and a second section that defines a second beam splitter wherein the hybrid mask is secured to a device that includes means for maneuvering either the first section or the second section into the optical path positioned in an image plane that is created by the optical element, with the proviso that the first section of the hybrid mask is positioned in the optical path when first beam splitter is positioned in the optical path; and a detector positioned after the hybrid mask along the optical path.

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

    NASA Technical Reports Server (NTRS)

    Temkin, A.

    1961-01-01

    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.

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

    PubMed

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

    2012-11-01

    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.

  16. Phase shifting interferometry using a spatial light modulator to measure optical thin films.

    PubMed

    Villalobos-Mendoza, Brenda; Granados-Agustín, Fermín S; Aguirre-Aguirre, Daniel; Cornejo-Rodríguez, Alejandro

    2015-09-10

    This work describes a process for measuring thin film steps, using phase shifting interferometry (PSI). The phase shifts are applied only in the region where the thin film steps are located. The phase shift is achieved by displaying different gray levels on a spatial light modulator (SLM Holoeye LC2012) placed in one arm of a Twyman-Green (T-G) interferometer. Before measuring the thin film steps, it was necessary to quantify the phase shifts achieved with this SLM by measuring the fringe shifts in experimental interferograms. The phase shifts observed in the interference patterns were produced by displaying the different gray levels on the SLM one by one, from 0 to 255. The experimental interferograms and the thicknesses of the thin film steps were successfully quantified, proving that this method can be used to measure thin films by applying the PSI method only on the region occupied by them.

  17. Analysis of edge effects in attenuating phase-shift masks using quantitative phase imaging

    NASA Astrophysics Data System (ADS)

    Shanker, Aamod; Sczyrba, Martin; Connolly, Brid; Neureuther, Andy; Waller, Laura

    2013-09-01

    Thick mask electromagnetic edge effects in attenuating phase-shift masks (ATT-PSM) are analyzed by extracting optical phase at the wafer plane from a series of through focus aerial images with 193nm light. The thick edges of an ATT-PSM can lead to phase distortions, creating asymmetric intensity contrast on either side of focus. Here we use through focus intensity images from an AIMS tool to quantitatively recover phase via the Transport of Intensity Equation (TIE). The TIE can recover the effective phase across the mask due to edge effects by analyzing the through focus image stack. We verify a previously proposed model for edge effects by adding quadrature phase boundary layers at the edges during simulation and compare the simulated through focus images with experimental data. After tuning the real and imaginary part of the boundary layer and the angle of the substrate, the simulated through focus behavior agrees with experiment, giving a measure of the edge effects. This leads to comparable quantitative phase profiles recovered at the wafer plane for simulation and experiment with the ATT-PSM. We expect that the method is applicable for the approximation of topographical effects in other types of thick masks as well.

  18. Effect of Phase Shift from Corals to Zoantharia on Reef Fish Assemblages

    PubMed Central

    Cruz, Igor C. S.; Loiola, Miguel; Albuquerque, Tiago; Reis, Rodrigo; de Anchieta C. C. Nunes, José; Reimer, James D.; Mizuyama, Masaru; Kikuchi, Ruy K. P.; Creed, Joel C.

    2015-01-01

    Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals) to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB), Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species) and phase-shift reefs (38 species), a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated. PMID:25629532

  19. Single-shot dual-wavelength phase unwrapping in parallel phase-shifting digital holography.

    PubMed

    Lee, Yonghee; Ito, Yasunori; Tahara, Tatsuki; Inoue, Junichi; Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu

    2014-04-15

    We propose a single-shot phase-unwrapping method using two wavelengths in parallel phase-shifting digital holography (PPSDH). The proposed method enables one to solve the phase ambiguity problem in PPSDH. We conducted an experiment of the proposed method using two lasers whose wavelengths are 473 and 532 nm. An object having about 1.9 μm step, which is 7.1 times larger than the half wavelength of one of the lasers (266 nm), was fabricated by using vapor deposition of aluminum. Single-shot measurement of the height of the object was successfully demonstrated, and the validity of the proposed method was verified.

  20. Two-wavelength phase-shifting interferometry with a superimposed grating displayed on an electrically addressed spatial light modulator.

    PubMed

    Bitou, Youichi

    2005-03-20

    A two-wavelength moire phase-shifting interferometer that uses a superimposed grating has been developed. The optical phase shifts for the two wavelengths are given by digital phase shifts of a superimposed grating displayed on a liquid-crystal spatial light modulator. A phase shift of the moire fringe is achieved by equal phase shifts with opposite signs in the two gratings. A moire phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shifts was obtained. Our experimental result shows measurements of the profile of a step object with a 2.65-microm synthetic wavelength.

  1. Single-shot and phase-shifting digital holographic microscopy using a 2-D grating.

    PubMed

    Yang, Taeseok Daniel; Kim, Hyung-Jin; Lee, Kyoung J; Kim, Beop-Min; Choi, Youngwoon

    2016-05-02

    We demonstrate digital holographic microscopy that, while being based on phase-shifting interferometry, is capable of single-shot measurements. A two-dimensional (2-D) diffraction grating placed in a Fourier plane of a standard in-line holographic phase microscope generates multiple copies of a sample image on a camera sensor. The identical image copies are spatially separated with different overall phase shifts according to the diffraction orders. The overall phase shifts are adjusted by controlling the lateral position of the grating. These phase shifts are then set to be multiples of π/2. Interferograms composed of four image copies combined with a parallel reference beam are acquired in a single shot. The interferograms are processed through a phase-shifting algorithm to produce a single complex image. By taking advantage of the higher sampling capacity of the in-line holography, we can increase the imaging information density by a factor of 3 without compromising the imaging acquisition speed.

  2. Critical phase shifts slow down circadian clock recovery: implications for jet lag.

    PubMed

    Leloup, Jean-Christophe; Goldbeter, Albert

    2013-09-21

    Advancing or delaying the light-dark (LD) cycle perturbs the circadian clock, which eventually recovers its original phase with respect to the new LD cycle. Readjustment of the clock occurs by shifting its phase in the same (orthodromic re-entrainment) or opposite direction (antidromic re-entrainment) as the shift in the LD cycle. To investigate circadian clock recovery after phase shifts of the LD cycle we use a detailed computational model previously proposed for the cellular regulatory network underlying the mammalian circadian clock. The model predicts the existence of a sharp threshold separating orthodromic from antidromic re-entrainment. In the vicinity of this threshold, resynchronization of the clock after a phase shift markedly slows down. The type of re-entrainment, the position of the threshold and the time required for resynchronization depend on multiple factors such as the autonomous period of the clock, the direction and magnitude of the phase shift, the clock biochemical kinetic parameters, and light intensity. Partitioning the phase shift into a series of smaller phases shifts decreases the impact on the recovery of the circadian clock. We use the phase response curve to predict the location of the threshold separating orthodromic and antidromic re-entrainment after advanced or delayed phase shifts of the LD cycle. The marked increase in recovery times predicted near the threshold could be responsible for the most severe disturbances of the human circadian clock associated with jet lag.

  3. Demonstration of an optical isolator by use of a nonreciprocal phase shift.

    PubMed

    Yokoi, H; Mizumoto, T; Takano, T; Shinjo, N

    1999-12-20

    The experimental study of an optical isolator by use of a nonreciprocal phase shift is demonstrated. The isolator has an optical interferometer composed of tapered couplers, nonreciprocal phase shifters, and a reciprocal phase shifter. The isolator, designed for a 1.55-microm wavelength, was fabricated to investigate the characteristics of each component. The branching and coupling characteristics of the tapered coupler were measured. The nonreciprocal and reciprocal phase shifts were also evaluated. By applying an external magnetic field to the interferometer, we confirmed the nonreciprocal phase shift in the interferometric isolator.

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

    PubMed

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

    2012-06-15

    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.

  5. The effects and inhibition of frequency offset on differential phase-shift keying detection

    NASA Astrophysics Data System (ADS)

    Guo, Hao; Zhou, Jing; Su, Shaojing; Pan, Zhongming

    2015-10-01

    Differential phase-shift keying (DPSK) has been widely implemented and developed in high-speed optical communication systems. The low error rate detection at high access rate is one of the considerable issues in practical engineering application. Balanced detection based on fiber Mach-Zehnder delay interferometer (MZDI) is the typical optical DPSK signal detecting method. It requires that the free spectrum range (FSR) of the MZDI equals the reciprocal of symbol period of the DPSK signal. For the reasons of ambient temperature variation and nonlinear phase noise, a dynamic frequency offset always exists between the FSR and the reciprocal of symbol period. That may introduce some optical signal-to-noise ratio (OSNR) costs and fault detections. Therefore, it is significant to inhibit the frequency offset on DPSK detection. In this paper, firstly, we discuss the effects of frequency offset on DPSK detection, and realize the conclusion that frequency offset is virtually equivalent to an additional phase difference between adjacent symbols. Secondly, through simulation, we analyze the feasibility of DPSK detection in the presence of a definite range of frequency offset, and present the quantitative computation of effective coverage, duty cycle, and optimal sampling time of symbol interference. Some issues which should be considered in practical implementation are also discussed. Finally, according to the relationship among phase difference, temperature and voltage, we propose a phase difference compensation scheme which can automatically adjust the voltage for optimal detections, and dynamically track the changing of ambient temperature and nonlinear phase noise. Furthermore, we ascertain the performance of the voltage requested for implementing the scheme. The scheme can be also developed to quadrature phase-shift keying (QPSK) and differential QPSK (DQPSK) modulation situations.

  6. Phase shift on reflection from polystyrene colloidal photonic crystal film on hydrogel surface

    NASA Astrophysics Data System (ADS)

    Rutirawut, T.; Sinsarp, A.; Tivakornsasithorn, K.; Srikhirin, T.; Osotchan, T.

    2015-07-01

    The phase shift on reflection from the colloidal photonic crystal film was measured by the Fabry-Pérot resonant cavity along the cross-section of the photonic crystal film without additional optical parts. The wet colloidal photonic crystal film was fabricated by dip-coating an agarose-gel-coated glass substrate into a suspension containing monodisperse polystyrene nanospheres with the diameter about 188 nm. The ordered structure of monodisperse spheres in the wet film on hydrogel contributed the reflection stopband of photonic crystals together with Fabry-Pérot interference fringes of this uniform wet film over the entire visible region. The spectrum of reflectance was observed under the reflected microscope with the optical fiber spectrometer. The analyzed experimental results show the thickness of film about 20 μm and the photonic stopband peak at ~470 nm. The variation of phase shift values between both edges of the peak varies from 0.07π to 0.88π which is in range of 0 to π as reported by other works. Moreover, these extracted optical properties are slightly changed due to the gradual water evaporation of the wet film. This stopband peak of photonic crystal is shifted to a shorter wavelength due to the more packing of nanospheres after drying.

  7. Phase correction method for least-squares wavefront calculation in statistical generalized phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Nobukazu; Kajihara, Kazuki

    2015-09-01

    When phase-shifting digital holography with a continuous fringe-scanning scheme is implemented using a PC-based measurement system without any synchronous circuit, nonuniform phase-shifted interference fringes are captured because of the fluctuation in the image-capturing interval. To cope with the nonuniform phase shifts, a statistical generalized phase-shifting approach is employed. Because the algorithm is designed to use an arbitrary phase shift, the nonuniform phase shifts do not obstruct object-wave retrieval. Moreover, multiple interference fringes can be obtained in a short time owing to the continuous fringe-scanning scheme. However, the wavefront calculation method is not designed for sequentially recorded interference fringes. To use multiple interference fringes appropriately, we develop a least-squares wavefront calculation method combined with corrections for the initial phase and the direction of phase rotation. We verify the proposed method by numerical simulations and optical experiments. The results show that the object wave with the same initial phase can be correctly reconstructed by using both phase correction methods simultaneously.

  8. One-shot phase-shifting phase-grating interferometry with modulation of polarization: case of four interferograms.

    PubMed

    Rodriguez-Zurita, Gustavo; Meneses-Fabian, Cruz; Toto-Arellano, Noel-Ivan; Vázquez-Castillo, José F; Robledo-Sánchez, Carlos

    2008-05-26

    An experimental setup for optical phase extraction from 2-D interferograms using a one-shot phase-shifting technique able to achieve four interferograms with 90 degrees phase shifts in between is presented. The system uses a common-path interferometer consisting of two windows in the input plane and a phase grating in Fourier plane as its pupil. Each window has a birefringent wave plate attached in order to achieve nearly circular polarization of opposite rotations one respect to the other after being illuminated with a 45 degrees linear polarized beam. In the output, interference of the fields associated with replicated windows (diffraction orders) is achieved by a proper choice of the windows spacing with respect to the grating period. The phase shifts to achieve four interferograms simultaneously to perform phase-shifting interferometry can be obtained by placing linear polarizers on each diffraction orders before detection at an appropriate angle. Some experimental results are shown.

  9. Intensity and phase fields behind Phase Shifting Masks studied with High Resolution Interference Microscopy

    NASA Astrophysics Data System (ADS)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Herzig, Hans Peter; Weichelt, Tina; Zeitner, Uwe; Vogler, Uwe; Voelkel, Reinhard

    2015-03-01

    The proximity printing industry is in real need of high resolution results and it can be done using Phase Shift Mask (PSM) or by applying Optical Proximity Correction (OPC). In our research we are trying to find out details of how light fields behind the structures of photo masks develop in order to determine the best conditions and designs for proximity printing. We focus here on parameters that are used in real situation with gaps up to 50 μm and structure sizes down to 2 μm. The light field evolution behind the structures is studied and delivers insight in to precisions and tolerances that need to be respected. It is the first time that an experimental analysis of light propagation through mask is presented in detail, which includes information on intensity and phase. The instrument we use is known as High Resolution Interference Microscopy (HRIM). HRIM is a Mach-Zehnder interferometer which is capable of recording three dimensional distributions of intensity and phase with diffraction limited resolution. Our characterization technique allows plotting the evolution of the desired light field and therefore printable structure till the desired proximity gap. In this paper we discuss in detail the evolution of intensity and phase fields of elbow or corner structure at different position behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the resolution in printed structures.

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

    NASA Astrophysics Data System (ADS)

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

    2006-01-01

    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.

  11. Alternative stable states and phase shifts in coral reefs under anthropogenic stress.

    PubMed

    Fung, Tak; Seymour, Robert M; Johnson, Craig R

    2011-04-01

    Ecosystems with alternative stable states (ASS) may shift discontinuously from one stable state to another as environmental parameters cross a threshold. Reversal can then be difficult due to hysteresis effects. This contrasts with continuous state changes in response to changing environmental parameters, which are less difficult to reverse. Worldwide degradation of coral reefs, involving "phase shifts" from coral to algal dominance, highlights the pressing need to determine the likelihood of discontinuous phase shifts in coral reefs, in contrast to continuous shifts with no ASS. However, there is little evidence either for or against the existence of ASS for coral reefs. We use dynamic models to investigate the likelihood of continuous and discontinuous phase shifts in coral reefs subject to sustained environmental perturbation by fishing, nutrification, and sedimentation. Our modeling results suggest that coral reefs with or without anthropogenic stress can exhibit ASS, such that discontinuous phase shifts can occur. We also find evidence to support the view that high macroalgal growth rates and low grazing rates on macroalgae favor ASS in coral reefs. Further, our results suggest that the three stressors studied, either alone or in combination, can increase the likelihood of both continuous and discontinuous phase shifts by altering the competitive balance between corals and algae. However, in contrast to continuous phase shifts, we find that discontinuous shifts occur only in model coral reefs with parameter values near the extremes of their empirically determined ranges. This suggests that continuous shifts are more likely than discontinuous shifts in coral reefs. Our results also suggest that, for ecosystems in general, tackling multiple human stressors simultaneously maximizes resilience to phase shifts, ASS, and hysteresis, leading to improvements in ecosystem health and functioning.

  12. Optical tomography of transparent objects with phase-shifting interferometry and stepwise-shifted Ronchi ruling.

    PubMed

    Meneses-Fabian, Cruz; Rodriguez-Zurita, Gustavo; Arrizón, Víctor

    2006-02-01

    An experimental setup for tomographic inspection of phase objects is presented. The system uses a common-path interferometer consisting of two windows in the input plane and a translating grating as its pupil. In the output, interference of the fields associated with replicated windows is achieved by a proper choice of the windows' spacing with respect to the grating period. With a rotating object in one window and a plane wave in the second one, the phase distribution of each projection is encoded as a corresponding digital image row, which, in turn, constructs a composite interferogram over the plane of a traditional sinogram. Phase stepping of composite interferograms can be achieved by a proper translation of the grating in order to obtain the unwrapped phase distribution as the corresponding sinogram. This sinogram allows tomographic reconstruction of phase slices by standard procedures. Composite interferograms and reconstructions for some transparent samples are shown.

  13. Nitrogen addition shifts the microbial community in the rhizosphere of Pinus tabuliformis in Northwestern China

    PubMed Central

    Lv, Fenglian; Xue, Sha; Wang, Guoliang; Zhang, Chao

    2017-01-01

    Atmospheric nitrogen (N) deposition profoundly alters the soil microbial communities and will thus affect nutrient cycles. The effects of N availability on microbial community, however, are not clear. We used PLFA analysis to evaluate the effects of a gradient of N addition (0, 2.8, 5.6, 11.2, and 22.4 g N m-2 y-1) for three years on the rhizospheric microbial community of Pinus tabuliformis seedlings. The main factors influencing the community were quantified using structural equation modelling and redundancy analysis. At the microbial-community level, N addition increased the total phospholipid fatty acids content by increasing the dissolved organic carbon (DOC) and root biomass. Increases in soil microbial biomass carbon and N, however, was attributed to the increased DOC, N content and decreased pH. At the microbial-groups level, Fungal, arbuscular mycorrhizal fungal (AMF), gram-positive bacterial (GP) abundances and the GP:GN ratio first increased and then decreased with N addition. Nitrogen addition increased the abundances of bacteria, fungi, and actinomycetes mainly by increasing the DOC content and decreasing root biomass. Additionally, the decrease of pH and ammonium N caused by N addition increased the fungal abundances and reduced actinomycete abundances, respectively. Nitrogen addition shifted the rhizospheric microbial community mainly by altering the DOC content and root biomass. The current rate of N deposition (2.5 g N m-2 y-1) benefits plant growth and increases the abundances of fungi, arbuscular mycorrhizal fungi, GP, actinomycetes and the GP:GN ratio. PMID:28234932

  14. Additive Diversity Partitioning of Fish in a Caribbean Coral Reef Undergoing Shift Transition

    PubMed Central

    Acosta-González, Gilberto; Rodríguez-Zaragoza, Fabián A.; Hernández-Landa, Roberto C.; Arias-González, Jesús E.

    2013-01-01

    Shift transitions in dominance on coral reefs from hard coral cover to fleshy macroalgae are having negative effects on Caribbean coral reef communities. Data on spatiotemporal changes in biodiversity during these modifications are important for decision support for coral reef biodiversity protection. The main objective of this study is to detect the spatiotemporal patterns of coral reef fish diversity during this transition using additive diversity-partitioning analysis. We examined α, β and γ fish diversity from 2000 to 2010, during which time a shift transition occurred at Mahahual Reef, located in Quintana Roo, Mexico. Data on coral reef fish and benthic communities were obtained from 12 transects per geomorphological unit (GU) in two GUs (reef slope and terrace) over six years (2000, 2005, 2006, 2007, 2008, 2010). Spatial analysis within and between the GUs indicated that the γ-diversity was primarily related to higher β-diversity. Throughout the six study years, there were losses of α, β and γ-diversity associated spatially with the shallow (reef slope) and deeper (reef terrace) GUs and temporally with the transition in cover from mound corals to fleshy macroalgae and boulder corals. Despite a drastic reduction in the number of species over time, β-diversity continues to be the highest component of γ-diversity. The shift transition had a negative effect on α, β and γ-diversity, primarily by impacting rare species, leading a group of small and less vulnerable fish species to become common and an important group of rare species to become locally extinct. The maintenance of fish heterogeneity (β-diversity) over time may imply the abetment of vulnerability in the face of local and global changes. PMID:23776521

  15. Additive diversity partitioning of fish in a Caribbean coral reef undergoing shift transition.

    PubMed

    Acosta-González, Gilberto; Rodríguez-Zaragoza, Fabián A; Hernández-Landa, Roberto C; Arias-González, Jesús E

    2013-01-01

    Shift transitions in dominance on coral reefs from hard coral cover to fleshy macroalgae are having negative effects on Caribbean coral reef communities. Data on spatiotemporal changes in biodiversity during these modifications are important for decision support for coral reef biodiversity protection. The main objective of this study is to detect the spatiotemporal patterns of coral reef fish diversity during this transition using additive diversity-partitioning analysis. We examined α, β and γ fish diversity from 2000 to 2010, during which time a shift transition occurred at Mahahual Reef, located in Quintana Roo, Mexico. Data on coral reef fish and benthic communities were obtained from 12 transects per geomorphological unit (GU) in two GUs (reef slope and terrace) over six years (2000, 2005, 2006, 2007, 2008, 2010). Spatial analysis within and between the GUs indicated that the γ-diversity was primarily related to higher β-diversity. Throughout the six study years, there were losses of α, β and γ-diversity associated spatially with the shallow (reef slope) and deeper (reef terrace) GUs and temporally with the transition in cover from mound corals to fleshy macroalgae and boulder corals. Despite a drastic reduction in the number of species over time, β-diversity continues to be the highest component of γ-diversity. The shift transition had a negative effect on α, β and γ-diversity, primarily by impacting rare species, leading a group of small and less vulnerable fish species to become common and an important group of rare species to become locally extinct. The maintenance of fish heterogeneity (β-diversity) over time may imply the abetment of vulnerability in the face of local and global changes.

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

    PubMed

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

    2007-01-15

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    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.

  18. Quantitative reflection phase mesoscopy by remote coherence tuning of phase-shift interference patterns

    PubMed Central

    Arbel, Elad; Bilenca, Alberto

    2015-01-01

    Conventional low-magnification phase-contrast microscopy is an invaluable, yet a qualitative, imaging tool for the interrogation of transparent objects over a mesoscopic millimeter-scale field-of-view in physical and biological settings. Here, we demonstrate that introducing a compact, unbalanced phase-shifting Michelson interferometer into a standard reflected brightfield microscope equipped with low-power infinity-corrected objectives and white light illumination forms a phase mesoscope that retrieves remotely and quantitatively the reflection phase distribution of thin, transparent, and weakly scattering samples with high temporal (1.38 nm) and spatial (0.87 nm) axial-displacement sensitivity and micrometer lateral resolution (2.3 μm) across a mesoscopic field-of-view (2.25 × 1.19 mm2). Using the system, we evaluate the etch-depth uniformity of a large-area nanometer-thick glass grating and show quantitative mesoscopic maps of the optical thickness of human cancer cells without any area scanning. Furthermore, we provide proof-of-principle of the utility of the system for the quantitative monitoring of fluid dynamics within a wide region. PMID:26216719

  19. Calculation method for a quadrature phase-shifting interferometer and its applications.

    PubMed

    Nakadate, Suezou; Sawada, Shinya; Kiire, Tomohiro; Shibuya, Masato; Yatagai, Toyohiko

    2013-01-01

    A calculation method for a quadrature phase-shifting interferometer is presented, and its applications to specular and speckle interferometers and digital holography are described. Two sets of quadrature phase-shifted interferograms are acquired, and the calculation method proposed gives the phase distribution of the interferograms. The principle of the calculation method with error analysis and experimental results for specular and speckle interferometers and digital holography are also given.

  20. Phase-shift-locked interferometer with a wavelength-modulated laser diode.

    PubMed

    Onodera, Ribun; Ishii, Yukihiro

    2003-01-01

    A phase-shift-locked interferometer has been constructed for distance measurement. A phase shift produced by sawtooth-current modulation of a laser diode is locked to a phase difference preset by polarization optics that consists of a quarter-wave plate and polarizers through an electrical feedback technique. An optical path difference can be measured from the locked sawtooth-wave current amplitude in real time. The sensitivity of the interferometer is discussed.

  1. Achromatic-phase-shifting low-coherence digital holography: theoretical analyses of zero-phase-shifting error condition and linear and nonlinear calibrations

    NASA Astrophysics Data System (ADS)

    Hayasaki, Yoshio

    2015-10-01

    Some methods for decreasing a measurement error derived from a phase-shifting error for broadband light in phase-shifting low-coherence digital holography are proposed based on theoretical analysis and numerical calculations. It is well-known that an achromatic-phase shifter based on a rotating polarizer drastically decreases the error, but it is found that a small error remains according to the imperfection of the achromatic-phase shifter. It is also found that an ideal achromatic-phase shifter perfectly eliminates the error only when the light source has a symmetrical spectrum. Furthermore, it is demonstrated that a simple linear calibration method decreases the error in a narrow range of optical path differences if a light source with an asymmetrical spectrum is used. Finally, a nonlinear calibration method that can further decrease the error in a wide range of optical path differences is discussed.

  2. Slope measurement of a phase object using a polarizing phase-shifting high-frequency Ronchi grating interferometer.

    PubMed

    Toto-Arellano, Noel-Ivan; Martínez-García, Amalia; Rodríguez-Zurita, Gustavo; Rayas-Álvarez, Juan Antonio; Montes-Perez, Areli

    2010-11-20

    An interferometric method to measure the slope of phase objects is presented. The analysis was performed by implementing a polarizing phase-shifting cyclic shear interferometer coupled to a 4-f Fourier imaging system with crossed high-frequency Ronchi gratings. This system can obtain nine interference patterns with adjustable phase shifts and variable lateral shear. In order to extract the slope of a phase object, it is only analyzed using four patterns obtained in a single shot, and applying the classical method of phase extraction.

  3. Mechanisms for Phase Shifting in Cortical Networks and their Role in Communication through Coherence

    PubMed Central

    Tiesinga, Paul H.; Sejnowski, Terrence J.

    2010-01-01

    In the primate visual cortex, the phase of spikes relative to oscillations in the local field potential (LFP) in the gamma frequency range (30–80 Hz) can be shifted by stimulus features such as orientation and thus the phase may carry information about stimulus identity. According to the principle of communication through coherence (CTC), the relative LFP phase between the LFPs in the sending and receiving circuits affects the effectiveness of the transmission. CTC predicts that phase shifting can be used for stimulus selection. We review and investigate phase shifting in models of periodically driven single neurons and compare it with phase shifting in models of cortical networks. In a single neuron, as the driving current is increased, the spike phase varies systematically while the firing rate remains constant. In a network model of reciprocally connected excitatory (E) and inhibitory (I) cells phase shifting occurs in response to both injection of constant depolarizing currents and to brief pulses to I cells. These simple models provide an account for phase-shifting observed experimentally and suggest a mechanism for implementing CTC. We discuss how this hypothesis can be tested experimentally using optogenetic techniques. PMID:21103013

  4. Image quality improvement of parallel four-step phase-shifting digital holography by using the algorithm of parallel two-step phase-shifting digital holography.

    PubMed

    Kakue, Takashi; Moritani, Yuri; Ito, Kenichi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2010-04-26

    We propose an algorithm that can improve the quality of the reconstructed image from the single hologram recorded by the optical system of the parallel four-step phase-shifting digital holography. The proposed algorithm applies the image-reconstruction algorithm of parallel two-step phase-shifting digital holography to the hologram so as to reduce errors in the reconstructed image and eliminate ghosts. We numerically and experimentally confirmed that the proposed algorithm decreased 25% in terms of root mean square error in amplitude, and eliminated the ghosts, respectively.

  5. Detection of Cerebral Hemorrhage in Rabbits by Time-Difference Magnetic Inductive Phase Shift Spectroscopy

    PubMed Central

    Pan, Wencai; Yan, Qingguang; Qin, Mingxin; Jin, Gui; Sun, Jian; Ning, Xu; Zhuang, Wei; Peng, Bin; Li, Gen

    2015-01-01

    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. PMID:26001112

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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

  7. Invariance of waveguide grating mirrors to lateral displacement phase shifts.

    PubMed

    Brown, Daniel; Friedrich, Daniel; Brückner, Frank; Carbone, Ludovico; Schnabel, Roman; Freise, Andreas

    2013-06-01

    We present a method to analyze the coupling of lateral displacements in nanoscale structures, in particular waveguide grating mirrors (WGMs), into the phase of a reflected Gaussian beam using a finite-difference time-domain simulation. Such phase noise is of interest for using WGMs in high-precision interferometry. We show that, to the precision of our simulations (10(-7) rad), waveguide mirrors do not couple lateral displacement into phase noise of a reflected beam and that WGMs are therefore not subject to the same stringent alignment requirements as previously proposed layouts using diffraction gratings.

  8. UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-aryl shift cascade reactions.

    PubMed

    Zheng, Lewei; Huang, Hongli; Yang, Chao; Xia, Wujiong

    2015-02-20

    UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    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.

  10. Parallel phase-shifting self-interference digital holography with faithful reconstruction using compressive sensing

    NASA Astrophysics Data System (ADS)

    Wan, Yuhong; Man, Tianlong; Wu, Fan; Kim, Myung K.; Wang, Dayong

    2016-11-01

    We present a new self-interference digital holographic approach that allows single-shot capturing three-dimensional intensity distribution of the spatially incoherent objects. The Fresnel incoherent correlation holographic microscopy is combined with parallel phase-shifting technique to instantaneously obtain spatially multiplexed phase-shifting holograms. The compressive-sensing-based reconstruction algorithm is implemented to reconstruct the original object from the under sampled demultiplexed holograms. The scheme is verified with simulations. The validity of the proposed method is experimentally demonstrated in an indirectly way by simulating the use of specific parallel phase-shifting recording device.

  11. Superresolution of interference fringes in parallel four-step phase-shifting digital holography.

    PubMed

    Tahara, Tatsuki; Lee, Yonghee; Ito, Yasunori; Xia, Peng; Shimozato, Yuki; Takahashi, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2014-03-15

    A superresolution method for interference fringes obtained by parallel four-step phase-shifting digital holography is proposed. A complex amplitude distribution of an object wave is derived from a recorded hologram by parallel phase-shifting interferometry using two pixels without any interpolation procedures. Multiple distributions are derived by changing one of the two pixels when conducting phase-shifting interferometry. The angular spectrum distribution of the object wave is obtained by both the Fourier transforms and synthesis of the spectrum distribution from the Fourier-transformed images in the spatial frequency domain. Available space bandwidth is extended to half of that of an image sensor.

  12. Statistical method for detecting phase shifts in alpha rhythm from human electroencephalogram data

    NASA Astrophysics Data System (ADS)

    Naruse, Yasushi; Takiyama, Ken; Okada, Masato; Umehara, Hiroaki

    2013-04-01

    We developed a statistical method for detecting discontinuous phase changes (phase shifts) in fluctuating alpha rhythms in the human brain from electroencephalogram (EEG) data obtained in a single trial. This method uses the state space models and the line process technique, which is a Bayesian method for detecting discontinuity in an image. By applying this method to simulated data, we were able to detect the phase and amplitude shifts in a single simulated trial. Further, we demonstrated that this method can detect phase shifts caused by a visual stimulus in the alpha rhythm from experimental EEG data even in a single trial. The results for the experimental data showed that the timings of the phase shifts in the early latency period were similar between many of the trials, and that those in the late latency period were different between the trials. The conventional averaging method can only detect phase shifts that occur at similar timings between many of the trials, and therefore, the phase shifts that occur at differing timings cannot be detected using the conventional method. Consequently, our obtained results indicate the practicality of our method. Thus, we believe that our method will contribute to studies examining the phase dynamics of nonlinear alpha rhythm oscillators.

  13. Simulation study on simultaneous phase-shifting lateral-shearing interferometer

    NASA Astrophysics Data System (ADS)

    Wu, XuHua

    2016-09-01

    Phase-shifting interferometry (PSI) is widely used in optical testing because of its advantages of high accuracy, high sensitivity and untouched test characteristics. However, the environment vibration introduces a random error in the temporal phase shift, which should be presise enough to ensure the test accuracy. In this paper, an novel simultaneous phase-shifting interferometry (SPSI) device is presented. In this device, using two identical transmission gratings and double shear-plates as the beam splitter and double shear-plates as the phase shifter, the optical path difference between the original wavefront and the sheared wavefront can be achieved by adjusting the spacing and wedge angle between the double shear-plates. Then three interferograms with 90° phase shift interval are captured simultaneously and instantaneously by the same CCD. The processing of the interferograms is performed using conventional methods of phase extraction with the algorithm of three phase shifts. Overcoming the disadvantages of traditional mechanical phaseshifting mode, therefore, influence caused by the environment vibration is eliminated. The arithmetic model of this SPSI system is deduced, sheared interferograms of optical system with different wavefront heights can be obtained, which can be used to test the high precision optical surface on-line. Compared with the conventional temporal PSI, this SPSI device is easy to be realized, but some phase shift errors appears such as the spatial mismatch between phase shifted interferograms and the inaccurate light split ratio generated by the difference diffraction efficiency between the +/-1th order and the 0th order transmittance lights of the gratings. Better precision can be achieved by error correction techniques such as phase shifting calibration or multiplying the right correction factor in the interferograms processing algorithm.

  14. A Comparison of the Performances of Coherent Binary-Phase-Shift Keying (BPSK) and Offset Quadrature-Phase-Shift Keying (OQPSK) in the Presence of Interference

    NASA Astrophysics Data System (ADS)

    Simon, M. K.; Darden, S.

    1999-10-01

    The performance of offset quadrature-phase-shift keying (OQPSK) in the presence of narrowband and wideband interference signals is considered, assuming perfect carrier synchronization. Narrowband interference is modeled as an unmodulated tone at a given frequency offset and random phase with respect to the desired OQPSK signal. Wideband interference is modeled as another OQPSK signal at a given frequency offset, random phase, and random timing with respect to the desired OQPSK signal, but having the identical data rate. This model is more typical of co-channel interference than that considered in other studies of this subject, where a wideband Gaussian noise was assumed. The results obtained here for OQPSK are compared with analogous results obtained previously by one of the authors for binary-phase-shift-keyed (BPSK) modulation.

  15. Development and characterization of advanced phase-shift mask blanks for 14nm node and beyond

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Jun; Jang, Kyu-Jin; Choi, Min-Ki; Yang, Chul-Kyu; Lee, Jae-Chul; Lee, Jong-Keun; Kang, Byung-Sun; Lee, Jong-Hwa; Shin, Cheol; Nam, Kee-Soo

    2014-10-01

    Recently, the development of semiconductor process for 14nm node and beyond is in progress. The mask-making process demands higher resolution and CD accuracy to meet requirements. Current conventional ArF PSM has several problems such as higher 3D effect and higher loading effect due to the thicker film. These problems cause the CD performance degradation. This study is about the manufacturing of advance ArF PSM, which has thinner phase shift layer and higher etch rate Cr absorber film. The thickness of phase shift film is less than 60nm and the total etch-time for the Cr absorber film is reduced more than 30%. The mask CD performance of this new blank was evaluated in terms of CD uniformity, CD linearity, pattern resolution, and loading effect and so on. Adapting to this new blank, we can achieve better CD performance by reducing the loading effect. In addition, the chemical durability and ArF exposure durability were also improved. In conclusion, the mask-making process margin was extended by using this new blank, and it is expected that we can achieve the required specifications for 14nm node and beyond.

  16. EMP-002a Phase Shift through the Ionosphere

    SciTech Connect

    Soltz, R.; Simons, D.; Fenimore, E.; Wilks, S.; Carey, T.

    2015-10-20

    In this note we review the derivation and use of the Ionospheric Transfer Function (ITF) in the DIO- RAMA model to calculate the propagation of a broad band ElectroMagnetic Pulse (EMP) through the Ionosphere in the limit of geometric optics. This note is intended to resolve a misunderstanding between the NDS VVA and EMP modeling teams regarding the appropriate use of the phase and group velocities in DIORAMA. The di erent approaches are documented in EMP-002 note, \\Phase vs. Group" [1], generated by the LLNL DIORAMA VVA team, and the subsequent response from the DIORAMA EMP modeling team' [2].

  17. Direct phase-shift measurement with transmitted deep-UV illumination

    NASA Astrophysics Data System (ADS)

    Kusunose, Haruhiko; Awamura, Naoki; Takizawa, Hideo; Miyazaki, Kouji; Ode, Takahiro; Awamura, Daikichi

    1996-07-01

    This paper describes a direct phase-shift measurement system with transmitted deep-UV illumination for phase shifting mask (PSM) using a lateral shearing interferometer system. This interferometer has new structure developed for this purpose. The mirror mount of the interferometer is made of SiC ceramics that promote stability against vibration and ambient temperature drift. The illumination employs a xenon mercury arc lamp that has a spectrum close to the wavelength of KrF excimer laser. The repeatability of measurements is 0.5 degree in 3 sigma. The system can measure a small pattern down to 1 μm with an alternating type PSM with the objective of N.A.=0.4. Influence of incident angle of illumination on phase-shift measurement is investigated by experiment. The results show similar effects with simulation for circular illumination. The phase-shift measurement results on quartz step meet well with a calculation from step height and known refractive index including the effect of incident angle of illumination. The deep-UV measurement results also have good correlation with calculations from the results with another direct phase-shift measurement system that wavelength is 365nm. The simulation for focus latitude of alternating type PSMs agree with the experimental results of wafer exposure and the phase measurement. The accuracy of this system is sufficient for application to development of phase shift mask process.

  18. Surface characterization based on optical phase shifting interferometry

    DOEpatents

    Mello, Michael , Rosakis; Ares J.

    2011-08-02

    Apparatus, techniques and systems for implementing an optical interferometer to measure surfaces, including mapping of instantaneous curvature or in-plane and out-of-plane displacement field gradients of a sample surface based on obtaining and processing four optical interferograms from a common optical reflected beam from the sample surface that are relatively separated in phase by .pi./2.

  19. Optical π phase shift created with a single-photon pulse.

    PubMed

    Tiarks, Daniel; Schmidt, Steffen; Rempe, Gerhard; Dürr, Stephan

    2016-04-01

    A deterministic photon-photon quantum logic gate is a long-standing goal. Building such a gate becomes possible if a light pulse containing only one photon imprints a phase shift of π onto another light field. We experimentally demonstrate the generation of such a π phase shift with a single-photon pulse. A first light pulse containing less than one photon on average is stored in an atomic gas. Rydberg blockade combined with electromagnetically induced transparency creates a phase shift for a second light pulse, which propagates through the medium. We measure the π phase shift of the second pulse when we postselect the data upon the detection of a retrieved photon from the first pulse. This demonstrates a crucial step toward a photon-photon gate and offers a variety of applications in the field of quantum information processing.

  20. Experimental demonstration of parallel two-step phase-shifting digital holography.

    PubMed

    Tahara, Tatsuki; Ito, Kenichi; Fujii, Motofumi; Kakue, Takashi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2010-08-30

    Parallel two-step phase-shifting digital holography is a technique for single-shot implementation of phase-shifting interferometry and requires only the intensity distribution of the reference wave and spatial two phase-shifted holograms. We constructed a system of parallel two-step phase-shifting digital holography and experimentally demonstrated the technique, for the first time. The system uses an originally fabricated image sensor having an array of 2 × 1 micro polarizers. Each micro polarizer was attached on pixel by pixel. In the experiment, the unwanted images, the zero-order diffraction wave and the conjugate image, are removed from the reconstructed image of objects by the system, while the images superimpose on the image of objects reconstructed by Fresnel transform alone. Also the capability of single-shot and three-dimensional imaging is demonstrated by the system.

  1. Analysis of wavelength error in spectral phase shifting of digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Zhang, Xiangchao; Zhang, Xiaolei; Xiao, Hong; Xu, Min

    2016-10-01

    Digital holographic microscopy is an attractive technology of precision measurement. Phase shifting is required to correctly reconstruct the measured surfaces from interferograms. Spectral phase shifting scheme, as an alternative approach of phase shifting, has drawn intensive attention in recent years. However, the wavelength modulated by the acousto-optic tunable filter (AOTF) is not sufficiently precise. As a consequence, severe measurement errors will be caused. In this paper, an iterative calibration algorithm is proposed. It estimates the unknown wavelength errors in the 3-step spectral phase shifting interferometry and then reconstructs the complex object wave. The actual wavelength is obtained by minimizing the difference between the measured and calculated intensities. Numerical examples have demonstrated that this algorithm can achieve very high accuracy over a wide range of wavelengths.

  2. High-speed 3D imaging by parallel phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Awatsuji, Yasuhiro; Xia, Peng; Matoba, Osamu

    2015-07-01

    As a high-speed three-dimensional (3D) imaging technique, parallel phase-shifting digital holography is presented. This technique records a single hologram of an object with an image sensor having a phase-shift array device and reconstructs the instantaneous 3D image of the object with a computer. In this technique, a single hologram in which the multiple holograms required for phase-shifting digital holography are multiplexed by using space-division multiplexing technique pixel by pixel. Also, we present a high-speed parallel phase-shifting digital holography system. The system consists of an interferometer, a continuous-wave laser, and a high-speed polarization imaging camera. Motion pictures of dynamic phenomena at the rate of up to 1,000,000 frames per second have been achieved by the high-speed system.

  3. Quantum correlation transfer through two parallel XXZ spin chains with phase shift control

    SciTech Connect

    Zhang Jian; Shao Bin; Liu Benqiong; Zou Jian; Li Qianshu; Wu Lianao

    2011-07-15

    Transmitting quantum states and entanglement through quantum channels is one of the key requirements for the development of quantum computation. Quantum discord has received much attention in quantum computation. We transfer quantum discord through two parallel XXZ spin chains with phase shift. The maximum discord can be enhanced by the phase shift. It will take more time to obtain an enhanced maximum discord in some cases, but for other cases, both the maximum and speed are enhanced by the phase shift. In the thermodynamic limit, the effect of the phase shift disappears and the maximum discord exponentially decays with increasing of the receiving position. Our results on spin chains are generalized to a family of linear Hamiltonians.

  4. Phase-shift, stimuli-responsive drug carriers for targeted delivery

    PubMed Central

    O’Neill, Brian E; Rapoport, Natalya

    2011-01-01

    The intersection of particles and directed energy is a rich source of novel and useful technology that is only recently being realized for medicine. One of the most promising applications is directed drug delivery. This review focuses on phase-shift nanoparticles (that is, particles of submicron size) as well as micron-scale particles whose action depends on an external-energy triggered, first-order phase shift from a liquid to gas state of either the particle itself or of the surrounding medium. These particles have tremendous potential for actively disrupting their environment for altering transport properties and unloading drugs. This review covers in detail ultrasound and laser-activated phase-shift nano- and micro-particles and their use in drug delivery. Phase-shift based drug-delivery mechanisms and competing technologies are discussed. PMID:22059114

  5. A staggered differential phase-shift keying modulation format for 100Gbit/s applications.

    PubMed

    Shao, Yufeng; Wen, Shuangchun; Chen, Lin; Li, Ying; Xu, Huiwen

    2008-08-18

    We propose and demonstrate by numerical simulation a new phase modulation format, the staggered differential phase-shift keying (SDPSK), for 100 Gbit/s applications. Non-return-to-zero (NRZ) SDPSK signals was generated by using two phase modulators, and return-to-zero (RZ) SDPSK signals with 50% duty cycle was generated by cascading a dual-arm Mach-Zehnder modulator. The demodulation of 2 bit/symbol can be simply achieved on 1 bit rate through only one Mach-Zehnder delay interferometer and a balanced receiver. By comparing the transmission characteristics of the two staggered phase modulation formats with those of NRZ-DPSK, RZ-DPSK, NRZ-DQPSK, and RZ-DQPSK, respectively, we show that, the SDPSK signal has similar chromatic dispersion and polarization-mode-dispersion tolerance to the DPSK signal with same NRZ or RZ shape, while the SDPSK signal has stronger nonlinear tolerance than the DPSK or DQPSK signal. In addition, the SDPSK signal has the best transmission performance when each signal was transmitted over 106km optical SMF+DCF, and then launched into a third-order Gaussian optical bandpass filter placed with beyond 125GHz bandwidth.

  6. Design and calibration of zero-additional-phase SPIDER

    SciTech Connect

    Baum, Peter; Riedle, Eberhard

    2005-09-01

    Zero-additional-phase spectral phase interferometry for direct electric field reconstruction (ZAP-SPIDER) is a novel technique for measuring the temporal shape and phase of ultrashort optical pulses directly at the interaction point of a spectroscopic experiment. The scheme is suitable for an extremely wide wavelength region from the ultraviolet to the near infrared. We present a comprehensive description of the experimental setup and design guidelines to effectively apply the technique to various wavelengths and pulse durations. The calibration of the setup and procedures to check the consistency of the measurement are discussed in detail. We show experimental data for various center wavelengths and pulse durations down to 7 fs to verify the applicability to a wide range of pulse parameters.

  7. Disturbance-free phase-shifting laser diode interferometer using adaptive feedback control

    SciTech Connect

    Suzuki, Takamasa; Takahashi, Tsutomu; Sasaki, Osami

    2009-10-10

    A feedback-control-equipped phase-shifting laser diode interferometer that eliminates external disturbance is proposed. The feedback loop is stabilized by adaptive control of the polarity of the interference signal. Conventional phase-shifting interferometry can be used with the feedback control, resulting in simplified signal processing and accurate measurement. Several experiments confirm the stability of the feedback control with a measurement repeatability of 1.8 nm.

  8. Phase shifting digital holography implemented with a twisted-nematic liquid-crystal display.

    PubMed

    Cruz, Maria-Luisa; Castro, Albertina; Arrizón, Victor

    2009-12-20

    We describe and experimentally demonstrate a phase shifting method based on the lateral displacement of a grating implemented with a twisted-nematic liquid-crystal spatial light modulator. This method allows an accurate implementation of the phase shift without requiring moving parts. The technique is implemented in a Mach-Zehnder digital holography setup in which the field transmitted by the sample object freely propagates to the hologram plane.

  9. Method for the manufacture of phase shifting masks for EUV lithography

    DOEpatents

    Stearns, Daniel G.; Sweeney, Donald W.; Mirkarimi, Paul B.; Barty, Anton

    2006-04-04

    A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

  10. ( t, n) Threshold quantum secret sharing using the phase shift operation

    NASA Astrophysics Data System (ADS)

    Qin, Huawang; Zhu, Xiaohua; Dai, Yuewei

    2015-08-01

    A ( t, n) threshold quantum secret sharing scheme is proposed, in which the secret is a quantum state, and the dealer encodes the secret through the phase shift operation. The participants perform the phase shift operations on the quantum state according to their private keys, and any t out of the n participants can use the Lagrange interpolation to recover the original quantum state. Compared to the existing schemes, the proposed scheme is simpler and more efficient.

  11. Rapid Solidification and Phase Transformations in Additive Manufactured Materials

    DOE PAGES

    Asle Zaeem, Mohsen; Clarke, Amy Jean

    2016-01-14

    Within the past few years, additive manufacturing (AM) has emerged as a promising manufacturing technique to enable the production of complex engineering structures with high efficiency and accuracy. Among the important factors establishing AM as a sustainable manufacturing process is the ability to control the microstructures and properties of AM products. In most AM processes, such as laser sintering (LS), laser melting (LM), and laser metal deposition (LMD), rapid solidification and high-temperature phase transformations play primary roles in determining nano- and microstructures, and consequently the mechanical and other properties of AM products. This topic of JOM is dedicated to summarizingmore » the current research efforts in the area of rapid solidification and phase transformations in additively manufactured materials. Finally, a brief summary follows below of 10 journal articles in this topic.« less

  12. Rapid Solidification and Phase Transformations in Additive Manufactured Materials

    SciTech Connect

    Asle Zaeem, Mohsen; Clarke, Amy Jean

    2016-01-14

    Within the past few years, additive manufacturing (AM) has emerged as a promising manufacturing technique to enable the production of complex engineering structures with high efficiency and accuracy. Among the important factors establishing AM as a sustainable manufacturing process is the ability to control the microstructures and properties of AM products. In most AM processes, such as laser sintering (LS), laser melting (LM), and laser metal deposition (LMD), rapid solidification and high-temperature phase transformations play primary roles in determining nano- and microstructures, and consequently the mechanical and other properties of AM products. This topic of JOM is dedicated to summarizing the current research efforts in the area of rapid solidification and phase transformations in additively manufactured materials. Finally, a brief summary follows below of 10 journal articles in this topic.

  13. Differential encoding for multiple amplitude and phase shift keying systems

    NASA Technical Reports Server (NTRS)

    Weber, W. J., III

    1978-01-01

    Because of the symmetry in most two-dimensional signal constellations, ambiguities exist at the receiver as to the exact phase orientation of the received signal set. In PSK systems, this ambiguity is resolved by the use of differential encoding. This paper presents differential encoding techniques which can be used with a variety of symmetric signal sets to remove their phase ambiguity. While not proven to be optimum, the techniques do have low performance penalties relative to the uncoded performance. The key to reducing the performance penalty is to use the minimum amount of differential encoding necessary to resolve the ambiguity. Examples of encoding techniques for several common signal constellations are given, including their performance penalties.

  14. Large phase shift via polarization-coupling cascading.

    PubMed

    Huo, Juan; Chen, Xianfeng

    2012-06-04

    Herein, we propose a phenomenon of "polarization-coupling (PC) cascading" generated in MgO doped periodically poled lithium niobate crystal (PPMgLN). PC cascading contributes to the effective electro-optical (EO) Kerr effect that is several orders of magnitude stronger than the classical ones. Experiment of Newton's rings demonstrates the large phase accumulation during the PC cascaded processes, and the experimental data is identical with the theoretical simulation.

  15. A Novel Sample Based Quadrature Phase Shift Keying Demodulator

    PubMed Central

    Ali, Sawal Hamid Md

    2014-01-01

    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10−6, whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator. PMID:25197687

  16. A novel sample based quadrature phase shift keying demodulator.

    PubMed

    Mohamed Moubark, Asraf; Ali, Sawal Hamid Md

    2014-01-01

    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10(-6), whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.

  17. Single-shot femtosecond-pulsed phase-shifting digital holography.

    PubMed

    Kakue, Takashi; Itoh, Seiya; Xia, Peng; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2012-08-27

    Parallel phase-shifting digital holography is capable of three-dimensional measurement of a dynamically moving object with a single-shot recording. In this letter, we demonstrated a parallel phase-shifting digital holography using a single femtosecond light pulse whose central wavelength and temporal duration were 800 nm and 96 fs, respectively. As an object, we set spark discharge in atmospheric pressure air induced by applying a high voltage to between two electrodes. The instantaneous change in phase caused by the spark discharge was clearly reconstructed. The reconstructed phase image shows the change of refractive index of air was -3.7 × 10(-4).

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

    PubMed

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

    2015-07-10

    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.

  19. Dynamic Phase Shifts in Nanoscale Distance Measurements by Double Electron Electron Resonance (DEER)†

    SciTech Connect

    Bowman, Michael K.; Maryasov, Alexander G.

    2007-04-01

    The off-resonant pump pulse used in double electron electron resonance (DEER) measurements produces dynamic phase shifts that are explained here by simple analytic and vector descriptions of the full range of signal behaviors observed during DEER measurements, including: large phase shifts in the signal; changes in the position and shape of the detected echo; and changes in the signal intensity. The dynamic phase shifts depend on the width, amplitude and offset frequency of the pump pulse. Isolated radicals as well as pairs or clusters of dipolar-coupled radicals have the same dynamic phase shift that is independent of pump pulse delay in a typical measurement. A method of calibrating both the pump pulse offset frequency and the pump pulse field strength is outlined. A vector model is presented that explains the dynamic phase shifts in terms of precessing magnetization that is either spin locked or precessing about the effective pump field during the pump pulse. Implications of the dynamic phase shifts are discussed as they relate to setting up, calibrating and interpreting the results of DEER measurements.

  20. Dynamic phase shifts in nanoscale distance measurements by double electron electron resonance (DEER)

    NASA Astrophysics Data System (ADS)

    Bowman, Michael K.; Maryasov, Alexander G.

    2007-04-01

    The off-resonant pump pulse used in double electron electron resonance (DEER) measurements produces dynamic phase shifts that are explained here by simple analytic and vector descriptions of the full range of signal behaviors observed during DEER measurements, including: large phase shifts in the signal; changes in the position and shape of the detected echo; and changes in the signal intensity. The dynamic phase shifts depend on the width, amplitude and offset frequency of the pump pulse. Isolated radicals as well as pairs or clusters of dipolar-coupled radicals have the same dynamic phase shift that is independent of pump pulse delay in a typical measurement. A method of calibrating both the pump pulse offset frequency and the pump pulse field strength is outlined. A vector model is presented that explains the dynamic phase shifts in terms of precessing magnetization that is either spin locked or precessing about the effective pump field during the pump pulse. Implications of the dynamic phase shifts are discussed as they relate to setting up, calibrating and interpreting the results of DEER measurements.

  1. Phase Shifting Capacity of the Circadian Pacemaker Determined by the SCN Neuronal Network Organization

    PubMed Central

    vanderLeest, Henk Tjebbe; Rohling, Jos H. T.; Michel, Stephan; Meijer, Johanna H.

    2009-01-01

    Background In mammals, a major circadian pacemaker that drives daily rhythms is located in the suprachiasmatic nuclei (SCN), at the base of the hypothalamus. The SCN receive direct light input via the retino-hypothalamic tract. Light during the early night induces phase delays of circadian rhythms while during the late night it leads to phase advances. The effects of light on the circadian system are strongly dependent on the photoperiod to which animals are exposed. An explanation for this phenomenon is currently lacking. Methodology and Principal Findings We recorded running wheel activity in C57 mice and observed large amplitude phase shifts in short photoperiods and small shifts in long photoperiods. We investigated whether these different light responses under short and long days are expressed within the SCN by electrophysiological recordings of electrical impulse frequency in SCN slices. Application of N-methyl-D-aspartate (NMDA) induced sustained increments in electrical activity that were not significantly different in the slices from long and short photoperiods. These responses led to large phase shifts in slices from short days and small phase shifts in slices from long days. An analysis of neuronal subpopulation activity revealed that in short days the amplitude of the rhythm was larger than in long days. Conclusions The data indicate that the photoperiodic dependent phase responses are intrinsic to the SCN. In contrast to earlier predictions from limit cycle theory, we observed large phase shifting responses in high amplitude rhythms in slices from short days, and small shifts in low amplitude rhythms in slices from long days. We conclude that the photoperiodic dependent phase responses are determined by the SCN and propose that synchronization among SCN neurons enhances the phase shifting capacity of the circadian system. PMID:19305510

  2. The addition of granulocyte-colony stimulating factor shifts the dose limiting toxicity and markedly increases the maximum tolerated dose and activity of the kinesin spindle protein inhibitor SB-743921 in patients with relapsed or refractory lymphoma: results of an international, multicenter phase I/II study.

    PubMed

    O'Connor, Owen A; Gerecitano, John; Van Deventer, Henrik; Hainsworth, John; Zullo, Kelly M; Saikali, Khalil; Seroogy, Joseph; Wolff, Andrew; Escandón, Rafael

    2015-01-01

    This was a phase I study of SB-743921 (SB-921) in patients with relapsed/refractory lymphoma. Previous studies established that neutropenia was the only dose limiting toxicity (DLT). The primary objective was to determine the DLT, maximum tolerated dose (MTD) and efficacy of SB-921 with and without granulocyte-colony stimulating factor (G-CSF). Sixty-eight patients were enrolled, 42 without G-CSF, 26 with G-CSF. In the cohort without G-CSF, SB-921 doses ranged from 2 to 7 mg/m(2), with 6 mg/m(2) being the MTD. In the cohort with G-CSF support, doses of 6-10 mg/m(2) were administered, with 9 mg/m(2) being the MTD, representing a 50% increase in dose density. Fifty-six patients were evaluable for efficacy. Four of 55 patients experienced a partial response (three in Hodgkin lymphoma and one in non-Hodgkin lymphoma, all at doses ≥ 6 mg/m(2)); 19 patients experienced stable disease, 33 patients developed progression of disease. G-CSF shifted the DLT from neutropenia to thrombocytopenia, allowing for a 50% increase in dose density. Responses were seen at higher doses with G-CSF support.

  3. Superresolution imaging method using phase-shifting digital lensless Fourier holography.

    PubMed

    Granero, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier

    2009-08-17

    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.

  4. Dynamic BOTDA measurements based on Brillouin phase-shift and RF demodulation.

    PubMed

    Urricelqui, Javier; Zornoza, Ander; Sagues, Mikel; Loayssa, Alayn

    2012-11-19

    We demonstrate a novel dynamic BOTDA sensor based, for the first time to our knowledge, on the use of the Brillouin phase-shift in addition to the conventional Brillouin gain. This provides the advantage of measurements that are largely immune to variations in fiber attenuation or changes in pump pulse power. Furthermore, the optical detection deployed leads to an enhanced precision or measurement time and to the broadening of the measurement range. Proof-of-concept experiments demonstrate 1.66-kHz measurement rate with 1-m resolution over a 160 m sensing fiber length. Moreover, a measurement range of 2560 µε with a precision of 20 µε is successfully proved.

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

    NASA Astrophysics Data System (ADS)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2016-09-01

    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.

  6. Functional Contributions of Strong and Weak Cellular Oscillators to Synchrony and Light-shifted Phase Dynamics.

    PubMed

    Roberts, Logan; Leise, Tanya L; Welsh, David K; Holmes, Todd C

    2016-08-01

    Light is the primary signal that calibrates circadian neural circuits and thus coordinates daily physiological and behavioral rhythms with solar entrainment cues. Drosophila and mammalian circadian circuits consist of diverse populations of cellular oscillators that exhibit a wide range of dynamic light responses, periods, phases, and degrees of synchrony. How heterogeneous circadian circuits can generate robust physiological rhythms while remaining flexible enough to respond to synchronizing stimuli has long remained enigmatic. Cryptochrome is a short-wavelength photoreceptor that is endogenously expressed in approximately half of Drosophila circadian neurons. In a previous study, physiological light response was measured using real-time bioluminescence recordings in Drosophila whole-brain explants, which remain intrinsically light-sensitive. Here we apply analysis of real-time bioluminescence experimental data to show detailed dynamic ensemble representations of whole circadian circuit light entrainment at single neuron resolution. Organotypic whole-brain explants were either maintained in constant darkness (DD) for 6 days or exposed to a phase-advancing light pulse on the second day. We find that stronger circadian oscillators support robust overall circuit rhythmicity in DD, whereas weaker oscillators can be pushed toward transient desynchrony and damped amplitude to facilitate a new state of phase-shifted network synchrony. Additionally, we use mathematical modeling to examine how a network composed of distinct oscillator types can give rise to complex dynamic signatures in DD conditions and in response to simulated light pulses. Simulations suggest that complementary coupling mechanisms and a combination of strong and weak oscillators may enable a robust yet flexible circadian network that promotes both synchrony and entrainment. A more complete understanding of how the properties of oscillators and their signaling mechanisms facilitate their distinct roles

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

    NASA Astrophysics Data System (ADS)

    Yang, Lichao; Fu, Zuntao

    2016-08-01

    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.

  8. RF CALIBRATION OF CEBAF LINAC CAVITIES THROUGH PHASE SHIFTS

    SciTech Connect

    Carpenter, Adam P.; Benesch, Jay F.; Slominski, Christopher J.

    2016-10-01

    This paper describes a new beam-based method of cavity energy gain calibration based on varying the cavity phase. This method can be fully automated and allows a larger range of momentum excursions during measurement than previous calibration approaches. Monte Carlo simulations suggest that a calibration precision of 2-3% could be realistically achieved using this method. During the commissioning of the Continuous Electron Beam Accelerator Facility's (CEBAF) energy upgrade to 12 GeV, 876 measurements were performed on 375 of the 400 linac cavities in Fall 2015 and applied December 2015. Linac optics appears to be closer to design as a result. The resulting ensemble proved to be 2% over the value needed to get the desired energy in the arcs. Continued offline analysis of the data has allowed for error analysis and better understanding of the process.

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

    SciTech Connect

    Furukawa, Rei Matsuura, Motoharu; Nagata, Morio; Mishima, Kenji; Inoue, Azusa; Tagaya, Akihiro; Koike, Yasuhiro

    2013-11-18

    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.

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

    NASA Astrophysics Data System (ADS)

    Styk, Adam; Józwik, Michał

    2016-08-01

    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.

  11. Chronic Ethanol Intake Alters Circadian Phase Shifting and Free-Running Period in Mice

    PubMed Central

    Seggio, Joseph A.; Fixaris, Michael C.; Reed, Jeffrey D.; Logan, Ryan W.; Rosenwasser, Alan M.

    2011-01-01

    Chronic alcohol intake is associated with widespread disruptions in sleep and circadian rhythms in both human alcoholics and in experimental animals. Recent studies have demonstrated that chronic and acute ethanol treatments alter fundamental properties of the circadian pacemaker—including free-running period and responsiveness to photic and nonphotic phase-shifting stimuli—in rats and hamsters. In the present work, the authors extend these observations to the C57BL/6J mouse, an inbred strain characterized by very high levels of voluntary ethanol intake and by reliable and stable free-running circadian activity rhythms. Mice were housed individually in running-wheel cages under conditions of either voluntary or forced ethanol intake, whereas controls were maintained on plain water. Forced ethanol intake significantly attenuated photic phase delays (but not phase advances) and shortened free-running period in constant darkness, but voluntary ethanol intake failed to affect either of these parameters. Thus, high levels of chronic ethanol intake, beyond those normally achieved under voluntary drinking conditions, are required to alter fundamental circadian pacemaker properties in C57BL/6J mice. These observations may be related to the relative ethanol insensitivity displayed by this strain in several other phenotypic domains, including ethanol-induced sedation, ataxia, and withdrawal. Additional experiments will investigate chronobiological sensitivity to ethanol in a range of inbred strains showing diverse ethanol-related phenotypes. PMID:19625732

  12. Detection and correction of wavefront errors caused by slight reference tilt in two-step phase-shifting digital holography.

    PubMed

    Xu, Xianfeng; Cai, Luzhong; Gao, Fei; Jia, Yulei; Zhang, Hui

    2015-11-10

    A simple and convenient method, without the need for any additional optical devices and measurements, is suggested to improve the quality of the reconstructed object wavefront in two-step phase-shifting digital holography by decreasing the errors caused by reference beam tilt, which often occurs in practice and subsequently introduces phase distortion in the reconstructed wave. The effects of reference beam tilt in two-step generalized interferometry is analyzed theoretically, showing that this tilt incurs no error either on the extracted phase shift or on the retrieved real object wave amplitude on the recording plane, but causes great deformation of the recovered object wavefront. A corresponding error detection and correction approach is proposed, and the formulas to calculate the tilt angle and correct the wavefront are deduced. A series of computer simulations to find and remove the wavefront errors caused by reference beam tilt demonstrate the effectiveness of this method.

  13. Quantum Process Tomography of a Room Temperature Optically-Controlled Phase Shift

    NASA Astrophysics Data System (ADS)

    Kupchak, Connor; Rind, Samuel; Figueroa, Eden; Stony Brook University Team

    2015-05-01

    We have developed a room temperature setup capable of optically controlled phase shifts on a weak probe field. Our system is realized in a vapor of 87Rb atoms under the conditions of electromagnetically induced transparency utilizing a N-type energy level scheme coupled by three optical fields. By varying the power of the signal field, we can control the size of an optical phase shift experienced by weak coherent state pulses of < n > ~ 1 , propagating through the vapor. We quantify the optical phase shift by measuring the process output via balanced homodyne tomography which provides us with the complete quadrature and phase information of the output states. Furthermore, we measure the output for a set of states over a subspace of the coherent state basis and gain the information to completely reconstruct our phase shift procedure by coherent state quantum process tomography. The reconstruction yields a rank-4 process superoperator which grants the ability to predict how our phase shift process will behave on an arbitrary quantum optical state in the mode of the reconstruction. Our results demonstrate progress towards room temperature systems for possible quantum gates; a key component of a future quantum processor designed to operate at room temperature. US-Navy Office of Naval Research N00141410801, National Science Foundation PHY-1404398, Natural Sciences and Engineering Research Council of Canada.

  14. One-shot phase-shifting interferometry: five, seven, and nine interferograms.

    PubMed

    Rodriguez-Zurita, Gustavo; Toto-Arellano, Noel-Ivan; Meneses-Fabian, Cruz; Vázquez-Castillo, José F

    2008-12-01

    To extract phase distributions, which evolve in time using phase-shifting interferometry, the simultaneous capture of several interferograms with a prescribed shift has to be done. Previous interferometric systems aimed to fulfill such a task were reported to get only four interferograms. It is pointed out that more than four suitable interferograms can be obtained with an interferometer that uses two windows in the object plane, a phase grid as a pupil, and modulation of polarization for each diffraction orders in the image plane. Experimental results for five, seven, and nine interferograms are given.

  15. Digital phase-shifting atomic force microscope Moiré method

    NASA Astrophysics Data System (ADS)

    Liu, Chia-Ming; Chen, Lien-Wen

    2005-04-01

    In this study, the digital atomic force microscope (AFM) Moiré method with phase-shifting technology is established to measure the in-plane displacement and strain fields. The Moiré 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 Moiré patterns. The four-step phase-shifting method is realized by translating the phase of the virtual reference grating from 0 to 2π. The principle of the digital AFM Moiré 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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Xuanni; Zhang, Hui; Wang, Yijun

    2016-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

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

    PubMed

    Tian, Chao; Liu, Shengchun

    2016-08-08

    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.

  19. Self-referenced rectangular path cyclic interferometer with polarization phase shifting.

    PubMed

    Sarkar, S; Ghosh, N; Chakraborty, S; Bhattacharya, K

    2012-01-01

    A polarization phase shifting interferometer using a cyclic path configuration for measurement of phase nonuniformities in transparent samples is presented. A cube beam splitter masked by two linear polarizers is used to split the source wavefront into two counter propagating linearly polarized beams that pass through the sample. At the output of the interferometer, the two orthogonally polarized beams are rendered circularly polarized in the opposite sense through the use of a quarter wave plate. Finally, phase shifting is achieved by rotating a linear polarizer before the recording plane. In a rectangular path interferometer, although the two counter propagating wavefronts are laterally folded with respect to each other in the interferometer arms, the beams finally emerge mutually unfolded at the output of the interferometer. This phenomenon is utilized to create a reference if the sample is introduced in one lateral half of the beam in any one of the interferometer arms. The polarization phase shifting technique is used to generate four phase-shifted interferograms, which are utilized to evaluate the phase profile of the phase sample. Experimental results presented validate the proposed technique.

  20. The detection of brain oedema with frequency-dependent phase shift electromagnetic induction.

    PubMed

    González, César A; Rubinsky, Boris

    2006-06-01

    The spectroscopic distribution of inductive phase shift in the brain as a function of the relative volume of oedema was evaluated with theoretical and experimental methods in the frequency range 1 to 8 MHz. The theoretical study employed a simple mathematical model of electromagnetic induction in tissue and brain tissue data available from the literature to calculate the phase shift as a function of oedema in the bulk of the brain. Experimental data were generated from bulk measurements of ex vivo homogenized pig brain tissue mixed with various volumes of physiological saline in a volume sample typical of the human brain. There is good agreement between the analytical and the experimental results. Detectable changes in phase shift begin from a frequency of about 3 MHz to 4 MHz in the tested compositions and volume. The phase shift increases with frequency and fluid content. The results suggest that measuring phase shift in the bulk of the brain has the potential for becoming a robust means for non-contact detection of oedema in the brain.

  1. Second-order Born approximation for the scattering phase shifts: Application to the Friedel sum rule

    NASA Astrophysics Data System (ADS)

    Nersisyan, Hrachya B.; Fernández-Varea, José M.

    2013-09-01

    Screening effects are important to understand various aspects of ion-solid interactions and, in particular, play a crucial role in the stopping of ions in solids. In this paper the phase shifts and scattering amplitudes for the quantum-mechanical elastic scattering within up to the second-order Born (B2) approximation are revisited for an arbitrary spherically-symmetric electron-ion interaction potential. The B2 phase shifts and scattering amplitudes are then used to derive the Friedel sum rule (FSR) involving the second-order Born corrections. This results in a simple equation for the B2 perturbative screening parameter of an impurity ion immersed in a fully degenerate electron gas which, as expected, turns out to depend on the ion atomic number Z1 unlike the first-order Born (B1) screening parameter reported earlier by some authors. Furthermore, our analytical results for the Yukawa, hydrogenic, Hulthén, and Mensing potentials are compared, for both positive and negative ions and a wide range of one-electron radii, to the exact screening parameters calculated self-consistently by imposing the FSR requirement. It is shown that the B2 screening parameters agree excellently with the exact values at large and moderate densities of the degenerate electron gas, while at lower densities they progressively deviate from the exact numerical solutions but are nevertheless more accurate than the prediction of the B1 approximation. In addition, a simple Padé approximant to the Born series has been developed that improves the performance of the perturbative FSR for any negative ion as well as for Z1=+1.

  2. The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts

    PubMed Central

    Vergés, Adriana; Steinberg, Peter D.; Hay, Mark E.; Poore, Alistair G. B.; Campbell, Alexandra H.; Ballesteros, Enric; Heck, Kenneth L.; Booth, David J.; Coleman, Melinda A.; Feary, David A.; Figueira, Will; Langlois, Tim; Marzinelli, Ezequiel M.; Mizerek, Toni; Mumby, Peter J.; Nakamura, Yohei; Roughan, Moninya; van Sebille, Erik; Gupta, Alex Sen; Smale, Dan A.; Tomas, Fiona; Wernberg, Thomas; Wilson, Shaun K.

    2014-01-01

    Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to ‘barrens’ when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs. PMID:25009065

  3. A novel method for identifying the order of interference using phase-shifting digital holography.

    PubMed

    Sokkar, T Z N; El-Farahaty, K A; Ramadan, W A; Wahba, H H; Raslan, M I; Hamza, A A

    2016-04-01

    In this paper, we introduced a mathematical method for measuring the optical path length differences (OPDs), which is suitable for large OPD values where the fringes connections are difficult to detect. The proposed method is based on varying the width of the fringes, without changing the wavelength of the used coherent source. Also, in this work, we discussed the need for such method in off-axis phase-shifting digital holography. Low-resolution off-axis holograms failed to detect the correct interference order. In general, off-axis phase-shifting digital holography is limited by the resolution of the captured holograms. The results obtained using our proposed technique were compared to the results obtained using off-axis phase-shifting digital holograms and conventional two-beam interferometry. Holograms were given for illustration.

  4. Superresolved common-path phase-shifting digital inline holographic microscopy using a spatial light modulator.

    PubMed

    Micó, Vicente; Zalevsky, Zeev; Garcia, Javier

    2012-12-01

    Common-path phase-shifting lensless holographic microscopy has been recently proposed as a novel approach capable of high numerical aperture imaging in a lensless digital inline holographic microscopy layout [Opt. Lett.35, 3919 (2010)]. Here we present proof-of-concept validation for improving the resolution limit imposed by diffraction in such a setup. This is accomplished by shifting the phase lens displayed at the spatial light modulator, which moves the illumination point source to different off-axis positions. For each off-axis position, a set of inline phase-shifted holograms are recorded by the digital sensor and stored at the computer's memory for later digital postprocessing. As a consequence, each recording allows the recovery of different spatial frequency content of the object's diffracted wavefront meaning a superresolved image of the input object. Experimental results are reported validating the proposed method.

  5. Phase-Shift Master-Slave Mechanisms for High Angular-Speed Wedge-Prism Systems

    NASA Astrophysics Data System (ADS)

    Chappuis, Olivier; Clavel, Reymond

    2013-02-01

    Laser micro-machining requires high dynamic laser spot trajectory and accuracy to control the laser beam scanning. A well-known technique to scan a laser beam over a specimen is to use a pair of wedge-prisms. However, it is difficult to master-slave the phase-shift between two rotating prisms at high angular-speed. We present here two drive mechanisms that decouple the phase-shift control and the angular-speed control. These mechanisms simplify the required control architecture and are suitable to achieve a high-dynamic trajectory. These concepts are based on differential timing belts and gears mechanisms that modify the phase-shift between the prisms without interrupting the rotation. This article focuses on the kinematic and mechanical design aspects of such mechanisms.

  6. A new route for length measurement by phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Luo, ZhiYong; Li, ZhangHong

    2012-04-01

    By the mathematic models of flexible hinge, the accurate relationship between the phase-shifting and pressure acting on the hinge is deduced and verified by experimental results. Through the optimization of the geometric parameter of flexible hinge, a phase-shifting generator is developed to determine the length of an object precisely by interferometry. The experiments show that the triple phase-shifting produced using this generator is up to 1 μm. With this generator, an example for the application in length measurement is introduced. The result shows the length uncertainty is 0.5 nm when the temperature uncertainty is limited in 2 mK. This paper provides a novel technique to measure the dimension of an object, especially to the diameter of a silicon sphere for Avogadro constant project.

  7. The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts.

    PubMed

    Vergés, Adriana; Steinberg, Peter D; Hay, Mark E; Poore, Alistair G B; Campbell, Alexandra H; Ballesteros, Enric; Heck, Kenneth L; Booth, David J; Coleman, Melinda A; Feary, David A; Figueira, Will; Langlois, Tim; Marzinelli, Ezequiel M; Mizerek, Toni; Mumby, Peter J; Nakamura, Yohei; Roughan, Moninya; van Sebille, Erik; Gupta, Alex Sen; Smale, Dan A; Tomas, Fiona; Wernberg, Thomas; Wilson, Shaun K

    2014-08-22

    Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to 'barrens' when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs.

  8. Coherent noise reduction in digital holographic phase contrast microscopy by slightly shifting object.

    PubMed

    Pan, Feng; Xiao, Wen; Liu, Shuo; Wang, FanJing; Rong, Lu; Li, Rui

    2011-02-28

    A method to reduce coherent noise in digital holographic phase contrast microscopy is proposed. By slightly shifting the specimen, a series of digital holograms with different coherent noise patterns is recorded. Each hologram is reconstructed individually, while the different phase tilts of the reconstructed complex amplitudes due to the specimen shifts are corrected in the hologram plane by using numerical parametric lens method. Afterward, the lateral displacements of the phase maps from different holograms are compensated in the image plane by using digital image registration method. Thus, all phase images have same distribution, but uncorrelated coherent noise patterns. By a proper averaging procedure, the coherent noise of phase contrast image is reduced significantly. The experimental results are given to confirm the proposed method.

  9. An effective phase shift diffusion equation method for analysis of PFG normal and fractional diffusions.

    PubMed

    Lin, Guoxing

    2015-10-01

    Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, K(β)(t)D rad(β)/s(α), where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γ(β)g(β)δ(β)Df1t(α)), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γ(β)g(β)δ(β)Df2t(α)), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α=1, and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1∫0(τ) K(β)(t)dt(α)]. The results obtained in this study are in good agreement with the results in literature. Several expressions that

  10. Wideband design of nonreciprocal phase shift magneto-optical isolators using phase adjustment in Mach-Zehnder interferometers.

    PubMed

    Shoji, Yuya; Mizumoto, Tetsuya

    2006-09-20

    A wideband design is proposed for nonreciprocal phase shift magneto-optical isolators based on Mach-Zehnder interferometers. The wavelength dependence of nonreciprocal phase difference between the backward waves propagating in two interferometer arms is compensated for by that of reciprocal phase difference. This is realized by introducing an appropriate phase bias in one of interferometer arms. Two design examples are presented with a backward loss of >30 dB in the wavelength range of 1.40-1.63 microm for a magnetic garnet waveguide isolator and of 1.485-1.630 microm for a Si-wire waveguide isolator.

  11. Thermo-mechanical phase-shift determination in Coriolis mass-flowmeters with added masses

    NASA Astrophysics Data System (ADS)

    Ghayesh, Mergen H.; Amabili, Marco; Païdoussis, Michael P.

    2012-10-01

    The aim of this paper is to develop an approximate analytical solution for phase-shift (and thus mass flow) prediction along the length of the measuring tube of a Coriolis mass-flowmeter. A single, straight measuring tube is considered; added masses at the sensor and excitation locations are included in the model, and thus in the equation of motion. The measuring tube is excited harmonically by an electromagnetic driver. Taking into account thermal effects, the equation of motion is derived through use of the extended Hamilton's principle and constitutive relations. The equation of motion is discretized into a set of ordinary differential equations via Galerkin's technique. The method of multiple timescales is applied to the set of resultant equations, and the equations of order one and epsilon are obtained analytically for the system at primary resonance. The solution of the equation of motion is obtained by satisfying the solvability condition (making the solution of order epsilon free of secular terms). The flow-related phase-shift in the driver-induced tube vibration is measured at two symmetrically located points on either side of the mid-length of the tube. The analytical results for the phase-shift are compared to those obtained numerically. The effect of system parameters on the measured phase-shift is discussed. It is shown that the measured phase-shift depends on the mass flow rate, of course, but it is also affected by the magnitude of the added sensor mass and location, and the temperature change; nevertheless, the factors investigated do not induce a zero phase-shift.

  12. Self-calibrating generalized phase-shifting interferometry of three phase-steps based on geometric concept of volume enclosed by a surface

    NASA Astrophysics Data System (ADS)

    Meneses-Fabian, Cruz

    2016-12-01

    This paper presents a non-iterative, fast, and simple algorithm for phase retrieval, in phase-shifting interferometry of three unknown and unequal phase-steps, based on the geometric concept of the volume enclosed by a surface. This approach can be divided in three stages; first the background is eliminated by the subtraction of two interferograms, for obtaining a secondary pattern; second, a surface is built by the product of two secondary patterns and the volume enclosed by this surface is computed; and third, the ratio between two enclosed volumes is approximated to a constant that depends on the phase-steps, with which a system of equations is established, and its solution allows the measurement of the phase-steps to be obtained. Additional advantages of this approach are its immunity to noise, and its capacity to support high spatial variations in the illumination. This approach is theoretically described and is numerically and experimentally verified.

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    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.

  14. Single-shot polarization-imaging digital holography based on simultaneous phase-shifting interferometry.

    PubMed

    Tahara, Tatsuki; Awatsuji, Yasuhiro; Shimozato, Yuki; Kakue, Takashi; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-08-15

    We propose single-shot digital holography which is capable of simultaneously capturing both the information of multiple phase-shifted holograms and the distribution of the polarization. In this technique, a single image sensor records both the information required for phase-shifting interferometry and that of the polarization states of objects using an array of polarizers. The essence of the technique is the capability of imaging the distribution of the polarization of three-dimensional objects with a single-shot exposure by using the space-division multiplexing of holograms. The validity of the proposed technique was confirmed by the preliminary experiments.

  15. Enhanced depth resolution in terahertz imaging using phase-shift interferometry

    NASA Astrophysics Data System (ADS)

    Johnson, Jon L.; Dorney, Timothy D.; Mittleman, Daniel M.

    2001-02-01

    We describe an imaging technique for few-cycle optical pulses. An object to be imaged is placed at the focus of a lens in one arm of a Michaelson interferometer. This introduces a phase shift of approximately π between the two arms of the interferometer, via the Gouy phase shift. The resulting destructive interference provides a nearly background-free measurement, and a dramatic enhancement in depth resolution. We demonstrate this using single-cycle pulses of terahertz radiation, and show that it is possible to resolve features thinner than 2% of the coherence length of the radiation. This technique could have important applications in low-coherence optical tomographic measurements.

  16. Digital microscopy using phase-shifting digital holography with two reference waves.

    PubMed

    Guo, Pengyi; Devaney, Anthony J

    2004-04-15

    A lensless, coherent optical microscope is described that uses a version of phase-shifting digital holography (PSDH) in conjunction with a field backpropagation algorithm to form coherent images of transmission-type objects. The PSDH is implemented by use of only two reference waves, in contrast with the usual implementation that requires four quadrature phase-shifting reference waves. Therefore only two digital holograms need to be recorded, and the complexity of the microscopic system is reduced. Experimental results are presented that compare images generated from conventional Gabor digital holography, two-reference-wave PSDH, and conventional white-light microscopy.

  17. A Phase-Shifting Zernike Wavefront Sensor for the Palomar P3K Adaptive Optics System

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Crawford, Sam; Loya, Frank; Moore, James

    2012-01-01

    A phase-shifting Zernike wavefront sensor has distinct advantages over other types of wavefront sensors. Chief among them are: 1) improved sensitivity to low-order aberrations and 2) efficient use of photons (hence reduced sensitivity to photon noise). We are in the process of deploying a phase-shifting Zernike wavefront sensor to be used with the realtime adaptive optics system for Palomar. Here we present the current state of the Zernike wavefront sensor to be integrated into the high-order adaptive optics system at Mount Palomar's Hale Telescope.

  18. Envelope solitary waves exist and collide head-on without phase shift in a dusty plasma

    PubMed Central

    Zhang, Heng; Qi, Xin; Duan, Wen-Shan; Yang, Lei

    2015-01-01

    The rarefactive KdV solitary waves in a dusty plasma have been extensively studied analytically and found experimentally in the previous works. Though the envelope solitary wave described by a nonlinear Schrödinger equation (NLSE) has been proposed by using the reductive perturbation method, it is first verified by using the particle-in-cell (PIC) numerical method in this paper. Surprisingly, there is no phase shift after the head on collision between two envelope solitary waves, while it is sure that there are phase shifts of two colliding KdV solitary waves after head on collision. PMID:26383642

  19. Extracting scattering phase shifts in higher partial waves from lattice QCD calculations

    SciTech Connect

    Luu, Thomas; Savage, Martin J.

    2011-06-01

    Lüscher’s method is routinely used to determine meson-meson, meson-baryon, and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from lattice QCD calculations—presently at unphysical light-quark masses. In this work we review the formalism and develop the requisite expressions to extract phase shifts describing meson-meson scattering in partial waves with angular momentum l≤6 and l=9. The implications of the underlying cubic symmetry, and strategies for extracting the phase shifts from lattice QCD calculations, are presented, along with a discussion of the signal-to-noise problem that afflicts the higher partial waves.

  20. Simulation of high precision pulsed laser fuze based on phase shifting

    NASA Astrophysics Data System (ADS)

    Chen, Huimin; Li, Ping; Peng, Zhoufeng; Wang, Xiaobo; Zhang, Yingwen

    2009-07-01

    With the development of semiconductor laser technology, laser proximity fuzes have been widely used in various kinds of guided missiles and routine ammunitions. And its precision of ranging has a direct influence on the overall performance of the system. This work employed Spartan III series FPGA chip from Xilinx company. Through phase shifting the primary reference clock and ranging with four doubled-frequency clocks with each phase shiftings of 90 degree, the ranging precision can be improved obviously. The theoretical ranging error is 0.1875m and the result has been proven by simulation with Modelsim. Valuable conclusions were drawn for improving the ranging precision of laser fuze.

  1. Phase-shift based BOTDA measurements tolerant to non-local effects

    NASA Astrophysics Data System (ADS)

    Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2013-05-01

    We demonstrate a BOTDA sensor based on the use of the Brillouin phase-shift that performs measurements tolerant to non-local effects. This technique raises opportunities to increase the distance covered by these sensors and the maximum optical power of the probe wave injected to the fiber. As a result, the system has the potential to increase the SNR achieved at the last meters of the fiber. Proof-of-concept experiments demonstrate unaltered measurements of the phase-shift spectrum in a 20Km long fiber for large frequency-dependent distortions of the pump pulse.

  2. A method to design tunable quadrature filters in phase shifting interferometry.

    PubMed

    Mosiño, J F; Doblado, D Malacara; Hernández, D Malacara

    2009-08-31

    The main purpose of this paper is to present a method to design tunable quadrature filters in phase shifting interferometry. The algorithm is obtained from a generalized Fourier transform of a symmetrical quadrature filter. This formalism allows us to represent the detuning phase shift error and bias modulation as geometrical conditions. Therefore, the design of the filter becomes a set of solvable linear equations. Hence, to prove our method, several general tunable filters, like three and four frame algorithms, are obtained. Finally, from our results we reproduce particular symmetrical four frame algorithms reported in literature.

  3. Phase-shifted reflective coherent gradient sensor for measuring Young's modulus and Poisson's ratio of polished alloys

    NASA Astrophysics Data System (ADS)

    Ma, Kang; Xie, Huimin; Fan, Bozhao

    2017-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Shrestha, Ranjit; Park, Jeonghak; Kim, Wontae

    2016-05-01

    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.

  5. Coral-algal phase shifts on coral reefs: Ecological and environmental aspects [review article

    NASA Astrophysics Data System (ADS)

    McManus, John W.; Polsenberg, Johanna F.

    2004-02-01

    This paper briefly reviews coral-algal phase shifts on coral reefs, with particular regard to summarizing the exogenous and endogenous factors in support of a proposed conceptual model, and to identifying critical information gaps. A phase shift occurs on a coral reef when the cover of a substrate by scleractinian corals is reduced in favor of macroalgal dominance, and resilience of the former condition is retarded because of ecological processes and/or environmental conditions. The change is often, but not always, associated with a perturbation such as coral bleaching, outbreaks of a coral-eating species, or storm damage. The new state is generally associated with some combination of reduced herbivory (from disease and/or fishing) and nutrient enrichment, although the relative importance of these factors is under debate and may vary among locations and even across single reefs. Disturbances that result in a state of generally low biotic three-dimensional structural complexity often precede a phase shift. Following such a disturbance, the system will pass to a state of higher biotic structural complexity, with either macroalgae or coral dominating. As the community progresses towards larger and more three-dimensionally complex corals or macroalgae, it exhibits greater resistance to shifting dominance from one state to the other. Studies of the phase-shift phenomena have been generally conducted at scales that are small relative to the sizes and inherent variability of whole coral reefs and systems of reefs. There is an urgent need for studies aimed at quantifying and simulating cause and effect aspects of the phase shift, including human-environment coupling, particularly in support of coral reef decision-making.

  6. Phase shift in the 24-hour rhythm of hippocampal EEG spiking activity in a rat model of temporal lobe epilepsy

    PubMed Central

    Stanley, David A.; Talathi, Sachin S.; Parekh, Mansi B.; Cordiner, Daniel J.; Zhou, Junli; Mareci, Thomas H.; Ditto, William L.

    2013-01-01

    For over a century epileptic seizures have been known to cluster at specific times of the day. Recent studies have suggested that the circadian regulatory system may become permanently altered in epilepsy, but little is known about how this affects neural activity and the daily pattern of seizures. To investigate, we tracked long-term changes in the rate of spontaneous hippocampal EEG spikes (SPKs) in a rat model of temporal lobe epilepsy. In healthy animals, SPKs oscillated with near 24-h period; however, after injury by status epilepticus, a persistent phase shift of ∼12 h emerged in animals that later went on to develop chronic spontaneous seizures. Additional measurements showed that global 24-h rhythms, including core body temperature and theta state transitions, did not phase shift. Instead, we hypothesized that locally impaired circadian input to the hippocampus might be responsible for the SPK phase shift. This was investigated with a biophysical computer model in which we showed that subtle changes in the relative strengths of circadian input could produce a phase shift in hippocampal neural activity. MRI provided evidence that the medial septum, a putative circadian relay center for the hippocampus, exhibits signs of damage and therefore could contribute to local circadian impairment. Our results suggest that balanced circadian input is critical to maintaining natural circadian phase in the hippocampus and that damage to circadian relay centers, such as the medial septum, may disrupt this balance. We conclude by discussing how abnormal circadian regulation may contribute to the daily rhythms of epileptic seizures and related cognitive dysfunction. PMID:23678009

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Li, Beiwen; Liu, Ziping; Zhang, Song

    2016-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2016-05-01

    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.

  10. An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy

    SciTech Connect

    Lian, S.; Yang, H.; Kudo, H.; Momose, A.; Yashiro, W.

    2015-02-15

    The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called “Talbot effect” by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

  11. Anomalous Phase Shift of Quantum Oscillations in 3D Topological Semimetals.

    PubMed

    Wang, C M; Lu, Hai-Zhou; Shen, Shun-Qing

    2016-08-12

    Berry phase physics is closely related to a number of topological states of matter. Recently discovered topological semimetals are believed to host a nontrivial π Berry phase to induce a phase shift of ±1/8 in the quantum oscillation (+ for hole and - for electron carriers). We theoretically study the Shubnikov-de Haas oscillation of Weyl and Dirac semimetals, taking into account their topological nature and inter-Landau band scattering. For a Weyl semimetal with broken time-reversal symmetry, the phase shift is found to change nonmonotonically and go beyond known values of ±1/8 and ±5/8, as a function of the Fermi energy. For a Dirac semimetal or paramagnetic Weyl semimetal, time-reversal symmetry leads to a discrete phase shift of ±1/8 or ±5/8. Different from the previous works, we find that the topological band inversion can lead to beating patterns in the absence of Zeeman splitting. We also find the resistivity peaks should be assigned integers in the Landau index plot. Our findings may account for recent experiments in Cd_{2}As_{3} and should be helpful for exploring the Berry phase in various 3D systems.

  12. Anomalous Phase Shift of Quantum Oscillations in 3D Topological Semimetals

    NASA Astrophysics Data System (ADS)

    Wang, C. M.; Lu, Hai-Zhou; Shen, Shun-Qing

    2016-08-01

    Berry phase physics is closely related to a number of topological states of matter. Recently discovered topological semimetals are believed to host a nontrivial π Berry phase to induce a phase shift of ±1 /8 in the quantum oscillation (+ for hole and - for electron carriers). We theoretically study the Shubnikov-de Haas oscillation of Weyl and Dirac semimetals, taking into account their topological nature and inter-Landau band scattering. For a Weyl semimetal with broken time-reversal symmetry, the phase shift is found to change nonmonotonically and go beyond known values of ±1 /8 and ±5 /8 , as a function of the Fermi energy. For a Dirac semimetal or paramagnetic Weyl semimetal, time-reversal symmetry leads to a discrete phase shift of ±1 /8 or ±5 /8 . Different from the previous works, we find that the topological band inversion can lead to beating patterns in the absence of Zeeman splitting. We also find the resistivity peaks should be assigned integers in the Landau index plot. Our findings may account for recent experiments in Cd2 As3 and should be helpful for exploring the Berry phase in various 3D systems.

  13. Estimation of vibration frequency of loudspeaker diaphragm by parallel phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Kakue, T.; Endo, Y.; Shimobaba, T.; Ito, T.

    2014-11-01

    We report frequency estimation of loudspeaker diaphragm vibrating at high speed by parallel phase-shifting digital holography which is a technique of single-shot phase-shifting interferometry. This technique records multiple phaseshifted holograms required for phase-shifting interferometry by using space-division multiplexing. We constructed a parallel phase-shifting digital holography system consisting of a high-speed polarization-imaging camera. This camera has a micro-polarizer array which selects four linear polarization axes for 2 × 2 pixels. We set a loudspeaker as an object, and recorded vibration of diaphragm of the loudspeaker by the constructed system. By the constructed system, we demonstrated observation of vibration displacement of loudspeaker diaphragm. In this paper, we aim to estimate vibration frequency of the loudspeaker diaphragm by applying the experimental results to frequency analysis. Holograms consisting of 128 × 128 pixels were recorded at a frame rate of 262,500 frames per second by the camera. A sinusoidal wave was input to the loudspeaker via a phone connector. We observed displacement of the loudspeaker diaphragm vibrating by the system. We also succeeded in estimating vibration frequency of the loudspeaker diaphragm by applying frequency analysis to the experimental results.

  14. Supersymmetry-generated jost functions and nucleon–nucleon scattering phase shifts

    SciTech Connect

    Bhoi, J. Laha, U.

    2015-10-15

    By exploiting the supersymmetry-inspired factorization method higher partial wave Jost solutions and functions for nuclear Hulthen potential are constructed from the knowledge of the ground state wave function. As a case study the nucleon–nucleon scattering phase shifts are computed for partial waves ℓ = 0, 1, and 2.

  15. Noise and aliases in off-axis and phase-shifting holography.

    PubMed

    Gross, M; Atlan, M; Absil, E

    2008-04-10

    We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of a USAF target backlit with laser illumination, recorded with a charge-coupled device camera. We show that it is essential to remove the local oscillator beam noise, especially at low illumination levels.

  16. On the phase shift between electric potential and plasma density fluctuations in the edge turbulence

    SciTech Connect

    Shchepetov, S. V. Kholnov, Yu. V.; Vasil'kov, D. G.

    2013-02-15

    In some cases, the phase shift between fluctuations of the electric potential and plasma density helps to identify the instability that governs the turbulent state. In this paper, the basic experimental and theoretical results that denote the possibility (or impossibility) of such identification are briefly discussed. The experimental data based on measurements of the phase shift between the floating potential and ion saturation current fluctuations in the L-2M stellarator-a system with externally imposed magnetic surfaces-are presented (Shchepetov, Kholnov, Fedyanin, et al., Plasma Phys. Controlled Fusion 50, 045001 (2008)). It is shown that the observed phase shift {Omega} varies in a wide range from {pi} to 0, gradually decreasing with deepening inside the plasma. A number of arguments are presented suggesting that {Omega} Almost-Equal-To {pi} can indicate that the process is nonlocal, i.e., oscillations at a given spatial point are driven and mainly determined by the processes localized outside of the observation point. We note that, within the framework of the magnetohydrodynamic theory, plasma was definitely unstable with respect to resistive interchange modes in all cases under study. It is demonstrated experimentally that the widespread notion that the phase shift {Omega} Almost-Equal-To {pi}/2 is characteristic of only resistive interchange modes is hardly universal. The experimental results are analyzed on the basis of analytical estimates.

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

    SciTech Connect

    Izumi, Shuro; Takeoka, Masahiro; Fujiwara, Mikio; Sasaki, Masahide; Pozza, Nicola Dalla; Assalini, Antonio

    2014-12-04

    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.

  18. Characterization of phase-shifted Brillouin dynamic gratings in a polarization maintaining fiber

    NASA Astrophysics Data System (ADS)

    Zhou, Dengwang; Dong, Yongkang; Xu, Pengbai; Teng, Lei; Zhang, Hongying; Lu, Zhiwei

    2016-11-01

    We numerically calculate and experimentally investigate the characterization of phase-shifted Brillouin dynamic gratings (PS-BDGs) in a polarization maintaining fiber (PMF). A phase-shifted point is induced into the middle of a conventional BDG through phase-modulating one of the two pump pulse, generating a PS-BDG thanks to the stimulated Brillouin scattering (SBS). When the frequency difference between a high frequency pump1 pulse with 1ns and π-1ns and a low frequency pump2 pulse with 100ps is equal to the Brillouin frequency shift of the PMF, a transient PS-BDG with a 3dBbandwidth of 354MHz of the notch spectrum is simulated based on the coupled-wave equations of BDG. By increasing the repetition rate up to 250MHz, an enhanced PS-BDG with a deep notch depth is obtained since the residual acoustic wave of the former SBS process is enhanced by the optical waves of the latter SBS process. Then a proof-of-concept experiment is built to verify the transient PS-BDG and the results show that the notch feature is consistent with the simulation results and the notch frequency of the PS-BDG can be changed by tuning the phase shift Δϕ . The proposed PS-BDGs have important potential applications in optical fiber sensing, microwave photonics, all-optical signal processing and RoF (radio-over-fiber) networks.

  19. Exact analysis of a balanced receiver for differential phase-shift keying signals.

    PubMed

    Ho, Keang-Po

    2007-03-01

    The performance of differential phase-shift keying signals with a balanced receiver is exactly analyzed by using a closed-form expression without approximation. The numerical results are well matched with previous results based on the saddle-point approximation. The error probability is calculated exactly using the well-known Marcum Q function.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  1. The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD

    DOE PAGES

    Beane, S. R.; Chang, E.; Detmold, W.; ...

    2012-02-16

    The π+π+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of mπ ≈ 390 MeV with an anisotropic nf = 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 bs ≈ 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of π+π+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enoughmore » 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: mπ2 a r = 3+O(mπ2/Λχ2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.« less

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

    NASA Astrophysics Data System (ADS)

    Izumi, Shuro; Takeoka, Masahiro; Fujiwara, Mikio; Pozza, Nicola Dalla; Assalini, Antonio; Ema, Kazuhiro; Sasaki, Masahide

    2014-12-01

    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.

  3. Assessment of a Single-Shot Pixelated Phase-Shifting Interferometer Utilizing a Liquid Crystal Spatial Light Modulator

    SciTech Connect

    Baker, K L; Stappaerts, E A

    2005-10-01

    This article introduces a novel phase shifting pixelated interferometer based on a liquid crystal spatial light modulator and simulates the expected performance. The phase shifted frames are captured simultaneously which reduces the problems arising from vibrations and air turbulence. The liquid crystal spatial light modulator is very flexible and can be configured to provide a large number of phase shift levels and geometries to reduce the measurement error.

  4. Different adaptation of the motor activity rhythm to chronic phase shifts between adolescent and adult rats.

    PubMed

    Albert, Nerea; da Silva, Crhistiane; Díez-Noguera, Antoni; Cambras, Trinitat

    2013-09-01

    Chronic phase shifts is a common feature in modern societies, which may induce sleep alterations and other health problems. The effects of phase shift on the circadian rhythms have been described to be more pronounced in old than in young animals. However, few works address the effects of chronic phase shifts during adolescence. Here we tested the development of the motor activity circadian rhythm of young rats under chronic phase shifts, which consisted on 6-h advances (A), 6h delays (D) or 6h advances and delays alternated every 5 days (AD) during the first 60 days after weaning. Moreover, the rhythmic pattern was compared to that of adult rats under the same lighting conditions. Results indicate that adolescent rats, independently on the lighting environment, developed a clear circadian rhythm, whose amplitude increased the first 50 days after weaning and showed a more stable circadian rhythm than adults under the same lighting conditions. In the case of A and AD groups, circadian disruption was observed only in adult rats. In all groups, the offset of activity correlated with light pattern better than the onset, and this correlation was always higher in the case of the rhythm of the pubertal rats. When AD groups were transferred to constant darkness, the group submitted to this condition during adolescence showed shorter period than that submitted in their adulthood. In conclusion, differently from adult rats, adolescent rats submitted to chronic phase shifts did not show circadian disruption and developed a single circadian rhythm, suggesting permanent changes in the circadian system.

  5. Measurement of elastic 12C+alpha scattering: details of the experiment, analysis, and discussion of phase shifts

    SciTech Connect

    Couture, Aaron Joseph; Detwiler, Rebecca; Gorres, Joachim; Stech, Edward J; Ugalde, Claudio; Wiescher, Michael C F; Heil, Michael; Kappeler, Franz; Azuma, Richard E; Buchmann, Lothar

    2009-01-01

    Recent global analyses of {sup 12}C({alpha},{gamma}){sup 16}O have incorporated both elastic-scallering and {beta}-decay data in addition to direct measurements. In that context, it has been shown that an improvement in the available elastic-scallering data could help determine the contribution of the two subthreshold states, 6.92(2{sup +}) and 7.12(1{sup -}) MeV, and with excellent statistics could restrict resonance parameters above the threshold. To this end angular distributions of {sup 12}C({alpha}, {alpha}){sup 12}C in the {alpha}-energy range of 2.6-8.2 MeV, at angles from 24 to 166 have been measured at the University of Notre Dame using an array of 32 silicon detectors. Details of the experiment are reported. In the present analysis, the phase shifts have been determined from our previously reported R-matrix fit to these data. The uncertainties in the R-matrix phase shifts ({ell} = 0...6) are derived by a new Monte Carlo analysis technique as described in the article. We provide these phase shifts here for general use, in particular for the improved analysis and extrapolation of the {alpha} radiative capture to low energies.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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. Space-bandwidth extension in parallel phase-shifting digital holography using a four-channel polarization-imaging camera.

    PubMed

    Tahara, Tatsuki; Ito, Yasunori; Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2013-07-15

    We propose a method for extending the space bandwidth (SBW) available for recording an object wave in parallel phase-shifting digital holography using a four-channel polarization-imaging camera. A linear spatial carrier of the reference wave is introduced to an optical setup of parallel four-step phase-shifting interferometry using a commercially available polarization-imaging camera that has four polarization-detection channels. Then a hologram required for parallel two-step phase shifting, which is a technique capable of recording the widest SBW in parallel phase shifting, can be obtained. The effectiveness of the proposed method was numerically and experimentally verified.

  8. RACE and Calculations of Three-dimensional Distributed Cavity Phase Shifts

    NASA Technical Reports Server (NTRS)

    Li, Ruoxin; Gibble, Kurt

    2003-01-01

    The design for RACE, a Rb-clock flight experiment for the ISS, is described. The cold collision shift and multiple launching (juggling) have important implications for the design and the resulting clock accuracy and stability. We present and discuss the double clock design for RACE. This design reduces the noise contributions of the local oscillator and simplifies and enhances an accuracy evaluation of the clock. As we try to push beyond the current accuracies of clocks, new systematic errors become important. The best fountain clocks are using cylindrical TE(sub 011) microwave cavities. We recently pointed out that many atoms pass through a node of the standing wave microwave field in these cavities. Previous studies have shown potentially large frequency shifts for atoms passing through nodes in a TE(sub 013) cavity. The shift occurs because there is a small traveling wave component due to the absorption of the copper cavity walls. The small traveling wave component leads to position dependent phase shifts. To study these effects, we perform Finite Element calculations. Three-dimensional Finite Element calculations require significant computer resources. Here we show that the cylindrical boundary condition can be Fourier decomposed to a short series of two-dimensional problems. This dramatically reduces the time and memory required and we obtain (3D) phase distributions for a variety of cavities. With these results, we will be able to analyze this frequency shift in fountain and future space clocks.

  9. Compression of computer generated phase-shifting hologram sequence using AVC and HEVC

    NASA Astrophysics Data System (ADS)

    Xing, Yafei; Pesquet-Popescu, Béatrice; Dufaux, Frederic

    2013-09-01

    With the capability of achieving twice the compression ratio of Advanced Video Coding (AVC) with similar reconstruction quality, High Efficiency Video Coding (HEVC) is expected to become the newleading technique of video coding. In order to reduce the storage and transmission burden of digital holograms, in this paper we propose to use HEVC for compressing the phase-shifting digital hologram sequences (PSDHS). By simulating phase-shifting digital holography (PSDH) interferometry, interference patterns between illuminated three dimensional( 3D) virtual objects and the stepwise phase changed reference wave are generated as digital holograms. The hologram sequences are obtained by the movement of the virtual objects and compressed by AVC and HEVC. The experimental results show that AVC and HEVC are efficient to compress PSDHS, with HEVC giving better performance. Good compression rate and reconstruction quality can be obtained with bitrate above 15000kbps.

  10. Interferometric optical isolator employing a nonreciprocal phase shift operated in a unidirectional magnetic field.

    PubMed

    Yokoi, Hideki; Shoji, Yuya; Shin, Etsu; Mizumoto, Tetsuya

    2004-08-20

    An interferometric optical isolator that employs a nonreciprocal phase shift was studied. The optical isolator consisted of an interferometer with distinct layer structures. A traveling light wave underwent distinct nonreciprocal phase shifts such that the optical isolator could be operated in a unidirectional magnetic field. The optical isolator, in which the waveguide had a HfO2 cladding layer in one of the arms, was designed at a wavelength of 1.55 microm. The propagation distance of the nonreciprocal phase shifter required for the isolator's operation was less than 1.5 mm. The device's total length was less than 2 mm. An optical isolator with distinct layer structures was fabricated and evaluated. An isolation ratio of approximately 9.9 dB was obtained in the unidirectional magnetic field.

  11. Object recognition by use of polarimetric phase-shifting digital holography.

    PubMed

    Nomura, Takanori; Javidi, Bahram

    2007-08-01

    Pattern recognition by use of polarimetric phase-shifting digital holography is presented. Using holography, the amplitude distribution and phase difference distribution between two orthogonal polarizations of three-dimensional (3D) or two-dimensional phase objects are obtained. This information contains both complex amplitude and polarimetric characteristics of the object, and it can be used for improving the discrimination capability of object recognition. Experimental results are presented to demonstrate the idea. To the best of our knowledge, this is the first report on 3D polarimetric recognition of objects using digital holography.

  12. Spectral shifts and switches in random fields upon interaction with negative-phase materials

    SciTech Connect

    Tong Zhisong; Korotkova, Olga

    2010-07-15

    Spectral shifts in stochastic beam-like fields on interaction with layers of positive- and negative-phase materials are examined on the basis of the ABCD-matrix approach and generalized Huygens-Fresnel principle. It is found that boundaries between such materials may cause spectral switches. Effect of absorption of negative-phase materials on the beam spectrum is discussed. Our results may find applications in connection with spectrum-selection optical interconnects, spectrally encoded information transfer, image formation in systems involving negative-phase materials, and geometrically tunable metamaterials.

  13. Nonlinear Detection for a High Rate Extended Binary Phase Shift Keying System

    PubMed Central

    Chen, Xian-Qing; Wu, Le-Nan

    2013-01-01

    The algorithm and the results of a nonlinear detector using a machine learning technique called support vector machine (SVM) on an efficient modulation system with high data rate and low energy consumption is presented in this paper. Simulation results showed that the performance achieved by the SVM detector is comparable to that of a conventional threshold decision (TD) detector. The two detectors detect the received signals together with the special impacting filter (SIF) that can improve the energy utilization efficiency. However, unlike the TD detector, the SVM detector concentrates not only on reducing the BER of the detector, but also on providing accurate posterior probability estimates (PPEs), which can be used as soft-inputs of the LDPC decoder. The complexity of this detector is considered in this paper by using four features and simplifying the decision function. In addition, a bandwidth efficient transmission is analyzed with both SVM and TD detector. The SVM detector is more robust to sampling rate than TD detector. We find that the SVM is suitable for extended binary phase shift keying (EBPSK) signal detection and can provide accurate posterior probability for LDPC decoding. PMID:23539034

  14. Round-robin differential-phase-shift quantum key distribution with a passive decoy state method

    NASA Astrophysics Data System (ADS)

    Liu, Li; Guo, Fen-Zhuo; Qin, Su-Juan; Wen, Qiao-Yan

    2017-02-01

    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.

  15. Round-robin differential-phase-shift quantum key distribution with a passive decoy state method.

    PubMed

    Liu, Li; Guo, Fen-Zhuo; Qin, Su-Juan; Wen, Qiao-Yan

    2017-02-13

    Recently, a new type of protocol named Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) was proposed, where the security can be guaranteed without monitoring conventional signal disturbances. The active decoy state method can be used in this protocol to overcome the imperfections of the source. But, it may lead to side channel attacks and break the security of QKD systems. In this paper, we apply the passive decoy state method to the RRDPS QKD protocol. Not only can the more environment disturbance be tolerated, but in addition it can overcome side channel attacks on the sources. Importantly, we derive a new key generation rate formula for our RRDPS protocol using passive decoy states and enhance the key generation rate. We also compare the performance of our RRDPS QKD to that using the active decoy state method and the original RRDPS QKD without any decoy states. From numerical simulations, the performance improvement of the RRDPS QKD by our new method can be seen.

  16. Round-robin differential-phase-shift quantum key distribution with a passive decoy state method

    PubMed Central

    Liu, Li; Guo, Fen-Zhuo; Qin, Su-Juan; Wen, Qiao-Yan

    2017-01-01

    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. PMID:28198808

  17. Synthetic phase-shifting for optical testing: Point-diffraction interferometry without null optics or phase shifters

    PubMed Central

    Park, Ryeojin; Kim, Dae Wook; Barrett, Harrison H.

    2013-01-01

    An innovative iterative search method called the synthetic phase-shifting (SPS) algorithm is proposed. This search algorithm is used for maximum-likelihood (ML) estimation of a wavefront that is described by a finite set of Zernike Fringe polynomials. In this paper, we estimate the coefficient, or parameter, values of the wavefront using a single interferogram obtained from a point-diffraction interferometer (PDI). In order to find the estimates, we first calculate the squared-difference between the measured and simulated interferograms. Under certain assumptions, this squared-difference image can be treated as an interferogram showing the phase difference between the true wavefront deviation and simulated wavefront deviation. The wavefront deviation is the difference between the reference and the test wavefronts. We calculate the phase difference using a traditional phase-shifting technique without physical phase-shifters. We present a detailed forward model for the PDI interferogram, including the effect of the finite size of a detector pixel. The algorithm was validated with computational studies and its performance and constraints are discussed. A prototype PDI was built and the algorithm was also experimentally validated. A large wavefront deviation was successfully estimated without using null optics or physical phase-shifters. The experimental result shows that the proposed algorithm has great potential to provide an accurate tool for non-null testing. PMID:24216862

  18. Phase-shift inversion in oscillator systems with periodically switching couplings.

    PubMed

    Lee, Sang Hoon; Lee, Sungmin; Son, Seung-Woo; Holme, Petter

    2012-02-01

    A system's response to external periodic changes can provide crucial information about its dynamical properties. We investigate the synchronization transition, an archetypical example of a dynamic phase transition, in the framework of such a temporal response. The Kuramoto model under periodically switching interactions has the same type of phase transition as the original mean-field model. Furthermore, we see that the signature of the synchronization transition appears in the relative delay of the order parameter with respect to the phase of oscillating interactions as well. Specifically, the phase shift becomes significantly larger as the system gets closer to the phase transition, so that the order parameter at the minimum interaction density can even be larger than that at the maximum interaction density, counterintuitively. We argue that this phase-shift inversion is caused by the diverging relaxation time, in a similar way to the resonance near the critical point in the kinetic Ising model. Our result, based on exhaustive simulations on globally coupled systems as well as scale-free networks, shows that an oscillator system's phase transition can be manifested in the temporal response to the topological dynamics of the underlying connection structure.

  19. Serotonin and the mammalian circadian system: II. Phase-shifting rat behavioral rhythms with serotonergic agonists.

    PubMed

    Edgar, D M; Miller, J D; Prosser, R A; Dean, R R; Dement, W C

    1993-01-01

    The suprachiasmatic nuclei (SCN) receive primary afferents from the median and dorsal raphe, but the role of these projections in circadian timekeeping is poorly understood. Studies of the SCN in vitro suggest that quipazine, a general serotonin (5-HT) receptor agonist, can produce circadian time-dependent phase advances and phase delays in circadian rhythms of neuronal activity. The present study addresses whether quipazine and the selective 5-HT1A receptor agonist 8-OH-DPAT are similarly effective in vivo. Drinking and wheel-running patterns of male Wistar rats individually housed in constant darkness were monitored before and after subcutaneous administration of quipazine (5-10 mg/kg) at either circadian time (CT) 6 or CT 18, with and without running wheels available. Dose-dependent phase advances (20-180 min) were produced at CT 6. Significant phase shifts were not observed at CT 18. CT 6 quipazine-treated animals also showed a sustained and significant shortening of rhythm period (tau) following treatment (-0.28 hr; p < 0.002). tau shortening was inconsistently observed in CT 18 quipazine-treated rats. Neither quipazine-induced phase shifts nor tau effects were dependent on wheel-running activity per se. 8-OH-DPAT delivered via intracerebral ventricular treatment into the third ventricle (5 microliters at 100 microM in saline) produced slightly smaller phase advances (20-90 min) at CT 6, but did not produce phase delays at CT 18 or changes in tau. These findings support in vitro evidence that 5-HT-ergic agonists can phase-shift the circadian pacemaker.

  20. Temperature effect on entrainment, phase shifting, and amplitude of circadian clocks and its molecular bases.

    PubMed

    Rensing, Ludger; Ruoff, Peter

    2002-09-01

    Effects of temperature and temperature changes on circadian clocks in cyanobacteria, unicellular algae, and plants, as well as fungi, arthropods, and vertebrates are reviewed. Periodic temperature with periods around 24 h even in the low range of 1-2 degrees C (strong Zeitgeber effect) can entrain all ectothermic (poikilothermic) organisms. This is also reflected by the phase shifts-recorded by phase response curves (PRCs)-that are elicited by step- or pulsewise changes in the temperature. The amount of phase shift (weak or strong type of PRC) depends on the amplitude of the temperature change and on its duration when applied as a pulse. Form and position of the PRC to temperature pulses are similar to those of the PRC to light pulses. A combined high/low temperature and light/dark cycle leads to a stabile phase and maximal amplitude of the circadian rhythm-when applied in phase (i.e., warm/light and cold/dark). When the two Zeitgeber cycles are phase-shifted against each other the phase of the circadian rhythm is determined by either Zeitgeber or by both, depending on the relative strength (amplitude) of both Zeitgeber signals and the sensitivity of the species/individual toward them. A phase jump of the circadian rhythm has been observed in several organisms at a certain phase relationship of the two Zeitgeber cycles. Ectothermic organisms show inter- and intraspecies plus seasonal variations in the temperature limits for the expression of the clock, either of the basic molecular mechanism, and/or the dependent variables. A step-down from higher temperatures or a step-up from lower temperatures to moderate temperatures often results in initiation of oscillations from phase positions that are about 180 degrees different. This may be explained by holding the clock at different phase positions (maximum or minimum of a clock component) or by significantly different levels of clock components at the higher or lower temperatures. Different permissive temperatures

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

    NASA Astrophysics Data System (ADS)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2017-03-01

    A carrier separating method associated with noise-elimination had been introduced into a sinusoidal phase-shifting self-mixing interferometer. The conventional sinusoidal phase shifting self-mixing interferometry was developed into a more competitive instrument with high computing efficiency and nanometer accuracy of λ / 100 in dynamical vibration measurement. The high slew rate electro-optic modulator induced a sinusoidal phase carrier with ultralow insertion loss in this paper. In order to extract phase-shift quickly and precisely, this paper employed the carrier-separating to directly generate quadrature signals without complicated frequency domain transforms. Moreover, most noises were evaluated and suppressed by a noise-elimination technology synthesizing empirical mode decomposition with wavelet transform. The overall laser system was described and inherent advantages such as high computational efficiency and decreased nonlinear errors of the established system were demonstrated. The experiment implemented on a high precision PZT (positioning accuracy was better than 1 nm) and compared with laser Doppler velocity meter. The good agreement of two instruments shown that the short-term resolution had improved from 10 nm to 1.5 nm in dynamic vibration measurement with reduced time expense. This was useful in precision measurement to improve the SMI with same sampling rate. The proposed signal processing was performed in pure time-domain requiring no preprocessing electronic circuits.

  2. Effects of birefringence on Fizeau interferometry that uses a polarization phase-shifting technique.

    PubMed

    Zhao, Chunyu; Kang, Dongyel; Burge, James H

    2005-12-10

    Interferometers that use different states of polarization for the reference and the test beams can modulate the relative phase shift by using polarization optics in the imaging system. Thus the interferometer can capture simultaneous images that have a fixed phase shift, which can be used for phase-shifting interferometry. As all measurements are made simultaneously, the interferometer is not sensitive to vibration. Fizeau interferometers of this type have an advantage compared with Twyman-Green-type systems because they are common-path interferometers. However, a polarization Fizeau interferometer is not strictly common path when both wavefronts are transmitted by an optic that suffers from birefringence. The two polarized beams see different phases owing to birefringence; as a result, an error can be introduced in the measurement. We study the effect of birefringence on measurement accuracy when different polarization techniques are used in Fizeau interferometers. We demonstrate that measurement error is reduced dramatically and can be eliminated if the reference and test beams are circularly polarized rather than linearly polarized.

  3. Altered Circadian Rhythm and Metabolic Gene Profile in Rats Subjected to Advanced Light Phase Shifts

    PubMed Central

    Herrero, Laura; Valcarcel, Lorea; da Silva, Crhistiane Andressa; Albert, Nerea; Diez-Noguera, Antoni; Cambras, Trinitat; Serra, Dolors

    2015-01-01

    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. PMID:25837425

  4. Approaches for Achieving Broadband Achromatic Phase Shifts for Visible Nulling Coronagraphy

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Lyon, Richard G.

    2012-01-01

    Visible nulling coronagraphy is one of the few approaches to the direct detection and characterization of Jovian and Terrestrial exoplanets that works with segmented aperture telescopes. Jovian and Terrestrial planets require at least 10(exp -9) and 10(exp -10) image plane contrasts, respectively, within the spectral bandpass and thus require a nearly achromatic pi-phase difference between the arms of the interferometer. An achromatic pi-phase shift can be achieved by several techniques, including sequential angled thick glass plates of varying dispersive materials, distributed thin-film multilayer coatings, and techniques that leverage the polarization-dependent phase shift of total-internal reflections. Herein we describe two such techniques: sequential thick glass plates and Fresnel rhomb prisms. A viable technique must achieve the achromatic phase shift while simultaneously minimizing the intensity difference, chromatic beam spread and polarization variation between each arm. In this paper we describe the above techniques and report on efforts to design, model, fabricate, align the trades associated with each technique that will lead to an implementations of the most promising one in Goddard's Visible Nulling Coronagraph (VNC).

  5. Imaging performance of attenuated phase-shift mask using coherent scattering microscope

    NASA Astrophysics Data System (ADS)

    Lee, Jae Uk; Jeong, SeeJun; Hong, Seong Chul; Lee, Seung Min; Ahn, Jinho

    2014-03-01

    The half-tone phase shift mask (PSM) has been suggested for better imaging performances like image contrast, NILS and H-V bias compared to the binary mask (BIM) in EUV lithography. In this paper, we measured imaging performance of a fabricated half-tone attenuated PSM with Coherent Scattering Microscopy (CSM) and the results were compared with simulation data obtained by EM-suite tool. We prepared a half-tone attenuated PSM which has 12.7% reflectivity and 180° phase shift with absorber stack of 16.5mn-thick TaN absorber and 24nm-thick Mo phase shifter. With CSM, an actinic inspection tool, we measured the imaging properties of PSM. The diffraction efficiencies of BIM were measured as 31%, 36%, and 44% for 88 nm, 100 nm, and 128 nm mask CD, respectively, while those of PSM were measured as 45%, 62%, and 81%. Also the aerial image at wafer level obtained by CSM with high volume manufacturing tool's (HVM) illumination condition (NA=0.33, σ=0.9) showed higher image contrast and NILS with phase shift effect. And the measured data were consistent with the simulation data.

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    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.

  7. Experimental demonstration of phase-sensitive regeneration of a binary phase-shift keying channel without a phase-locked loop using Brillouin amplification.

    PubMed

    Almaiman, Ahmed; Cao, Yinwen; Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Liao, Peicheng; Bao, Changjing; Alishahi, Fatemeh; Fallahpour, Ahmad; Shamee, Bishara; Ahmed, Nisar; Willner, Asher J; Akasaka, Youichi; Ikeuchi, Tadashi; Takasaka, Shigehiro; Sugizaki, Ryuichi; Wilkinson, Steven; Touch, Joseph D; Tur, Moshe; Willner, Alan E

    2016-12-01

    All-optical phase regeneration of a binary phase-shift keying signal is demonstrated at 10-30 Gb/s without a phase-locked loop in a phase-sensitive amplification-based system using Brillouin amplification of the idler. The system achieves phase noise reduction of up to 56% and up to 11 dB OSNR gain at 10-5 bit error rate for the 10 Gb/s signal. The system's sensitivity to different parameters and stability is also evaluated.

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

    NASA Astrophysics Data System (ADS)

    Jan, Chia-Ming; Lin, Ying-Chieh

    2016-03-01

    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.

  9. Attenuated phase-shift mask for mitigation of photon shot noise effect in contact hole pattern for extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Kim, Jung Sik; Hong, Seongchul; Lee, Jae Uk; Lee, Seung Min; Ahn, Jinho

    2014-09-01

    In extreme ultraviolet lithography (EUVL), insufficient light source power is the biggest concern for high-volume manufacturing. Additionally, the photon shot noise (PSN) effect is believed to be the main source of degradation in various aspects of imaging performance. In this study, we propose an attenuated phase-shift mask (PSM) as a solution to both of these issues, yielding improved mask performance for the printing of small contact hole (C/H) patterns. Our PSM shows superior imaging performance over that of a binary intensity mask. We speculate that the stochastic imaging characteristics are improved by the enhanced diffraction efficiency of the PSM.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

  11. Shift in membrane miscibility transition temperature upon addition of short-chain alcohols

    NASA Astrophysics Data System (ADS)

    Schick, M.

    2016-12-01

    I consider the effect of a small concentration of a molecule, such as a short-chain alcohol, on the miscibility transition temperature of a giant plasma membrane vesicle. For concentrations sufficiently small such that the system can be treated as a dilute solution, the change in transition temperature is known to depend upon the extent of the molecule's partition into the coexisting liquid-disordered and liquid-ordered phases. Preferential partitioning into the former decreases the miscibility temperature, while preferential partitioning into the latter causes an increase. The analysis, combined with calculated values of the partition coefficient of saturated chains, illuminates the results of recent experiments on the change in miscibility transition temperatures with changing alcohol chain length, and makes several testable predictions.

  12. No indication of f0(1370) in ππ phase shift analyses

    NASA Astrophysics Data System (ADS)

    Ochs, Wolfgang

    2010-08-01

    The scalar meson f0(1370)—indicated in particular in the low energy pp¯→3 body reactions—is a crucial element in certain schemes of the scalar meson spectroscopy including glueballs. The most definitive results can be obtained from elastic and inelastic ππ phase shift analyses using the constraints from unitarity where the discrete ambiguities can be identified and resolved. We reconsider the phase shift analyses for π+π-→π+π-, π0π0, KK¯, ηη. While a clear resonance signal for f0(1500) in the resp. Argand diagrams is seen in all channels above a large "background" from f0(600) there is no clear signal of a second resonance "f0(1370)" in this mass range in any reaction, at the level of ˜10% branching ratio into ππ.

  13. Compression of interference patterns with application to phase-shifting digital holography.

    PubMed

    Darakis, Emmanouil; Soraghan, John J

    2006-04-10

    A compression method of phase-shifting digital holographic data is presented. Three interference patterns are recorded, and holographic information is extracted from them by phase-shifting interferometry. The scheme uses standard baseline Joint Photographic Experts Group (JPEG) or standard JPEG-2000 image compression techniques on the recorded interference patterns to reduce the amount of data to be stored. High compression rates are achieved for good reconstructed object image quality. The utility of the proposed method is experimentally verified with real holographic data. Results for compression rates using JPEG-2000 and JPEG of approximately 27 and 20, respectively, for a normalized root-mean-square error of approximately 0.7 are demonstrated.

  14. Image authentication via sparsity-based phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Chen, Xudong

    2015-03-01

    Digital holography has been widely studied in recent years, and a number of applications have been demonstrated. In this paper, we demonstrate that sparsity-based phase-shifting digital holography can be applied for image authentication. In phase-shifting digital holography, the holograms are sequentially recorded. Only small parts of each hologram are available for numerical reconstruction. It is found that nonlinear correlation algorithm can be applied to simply authenticate the reconstructed object. The results illustrate that the recovered image can be correctly verified. In the developed system, the recorded holograms are highly compressed which can facilitate data storage or transmission, and one simple authentication strategy has been established instead of applying relatively complex algorithms (such as compressive sensing) to recover the object.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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.

  16. A silicon photonic biosensor using phase-shifted Bragg gratings in slot waveguide.

    PubMed

    Wang, Xu; Flueckiger, Jonas; Schmidt, Shon; Grist, Samantha; Fard, Sahba T; Kirk, James; Doerfler, Matt; Cheung, Karen C; Ratner, Daniel M; Chrostowski, Lukas

    2013-10-01

    We present a novel silicon photonic biosensor using phase-shifted Bragg gratings in a slot waveguide. The optical field is concentrated inside the slot region, leading to efficient light-matter interaction. The Bragg gratings are formed with sidewall corrugations on the outside of the waveguide, and a phase shift is introduced to create a sharp resonant peak within the stop band. We experimentally demonstrate a high sensitivity of 340 nm/RIU measured in salt solutions and a high quality factor of 1.5 × 10⁴, enabling a low intrinsic limit of detection of 3 × 10⁻⁴ RIU. Furthermore, the silicon device was fabricated by a CMOS foundry, facilitating high-volume and low-cost production. Finally, we demonstrate the device's ability to interrogate specific biomolecular interactions, resulting in the first of its kind label-free biosensor.

  17. Ultrahigh efficiency EUV contact-hole printing with chromeless phase shift mask

    NASA Astrophysics Data System (ADS)

    Naulleau, Patrick; Anderson, Christopher N.; Chao, Weilun; Goldberg, Kenneth A.; Gullikson, Eric; Salmassi, Farhad; Wojdyla, Antoine

    2016-05-01

    Contact-hole layer patterning is expected to be one of the first applications for EUV lithography. Conventional darkfield absorber masks, however, are extremely inefficient for these layers, placing even more burden on the already challenging source power demands. To address this concern, a checkerboard phase shift mask configuration has been proposed yielding theoretical throughput gains of 5x assuming a thin-mask modeling. In this manuscript we describe the fabrication of such a mask and demonstrate its imaging performance using the SHARP EUV microscope and MET exposure tool at Lawrence Berkeley National Laboratory. For 25-nm dense features, the phase shift mask was shown to provide a throughput gain of 8x based on SHARP and 7x based on the Berkeley MET. The higher then predicted gain is expected to be due to the fact that the thin mask modeling used in the initial prediction misses shadowing effects.

  18. A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

    DOE PAGES

    Colak, Kerim; Asa, Erdem; Bojarski, Mariusz; ...

    2015-05-12

    We investigated a novel phase-shift control of a semibridgeless active rectifier (S-BAR) in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Moreover, theoretical and simulation results showthat with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. In order to confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm xmore » 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.« less

  19. A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

    SciTech Connect

    Colak, Kerim; Asa, Erdem; Bojarski, Mariusz; Czarkowski, Dariusz; Onar, Omer C.

    2015-05-12

    We investigated a novel phase-shift control of a semibridgeless active rectifier (S-BAR) in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Moreover, theoretical and simulation results showthat with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. In order to confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm x 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.

  20. Cooperative Lamb shift and the cooperative decay rate for an initially detuned phased state

    SciTech Connect

    Friedberg, Richard; Manassah, Jamal T.

    2010-04-15

    The cooperative Lamb shift (CLS) is hard to measure because in samples much larger than a resonant wavelength it is much smaller, for an initially prepared resonantly phased state, than the cooperative decay rate (CDR). We show, however, that if the phasing of the initial state is detuned so that the spatial wave vector is k{sub 1} congruent with k{sub 0{+-}}O((1/R)) (where k{sub 0}={omega}{sub 0}/c is the resonant frequency), the CLS grows to 'giant' magnitudes making it comparable to the CDR. Moreover, for certain controlled values of detuning, the initial CDR becomes small so that the dynamical Lamb shift (DLS) can be measured over a considerable period of time.

  1. An automatic system for measurement of retardation of wave plates based on phase-shifted method

    NASA Astrophysics Data System (ADS)

    Gao, Zhishan; Yan, Ming

    2005-02-01

    A practical system is described to measure the retardation of wave plates with phase-shifted method. The tested wave plate is put in and the original angle between the axis of it and the analyzer is random, not 45 degree. For the measurement is made rapidly and automatically, a standard wave plate act as a compensator, the stepping motor is used to drive the analyzer to realize phase shifting and a grating encoder is used to measure its rotating angle. At the same time, while the beam comes out from the analyzer, the photoelectric detector gets its intensity, and then the signals is magnified, filtered and sent to computer through its serial port. The results show the system has the advantages of costing little time and high accuracy.

  2. Threshold multi-secret sharing scheme based on phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Deng, Xiaopeng; Wen, Wei; Shi, Zhengang

    2017-03-01

    A threshold multi-secret sharing scheme is proposed based on phase-shifting interferometry. The K secret images to be shared are firstly encoded by using Fourier transformation, respectively. Then, these encoded images are shared into many shadow images based on recording principle of the phase-shifting interferometry. In the recovering stage, the secret images can be restored by combining any 2 K + 1 or more shadow images, while any 2 K or fewer shadow images cannot obtain any information about the secret images. As a result, a (2 K + 1 , N) threshold multi-secret sharing scheme can be implemented. Simulation results are presented to demonstrate the feasibility of the proposed method.

  3. High-speed parallel phase-shifting digital holography system using special-purpose computer for image reconstruction

    NASA Astrophysics Data System (ADS)

    Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2015-05-01

    We report a high-speed parallel phase-shifting digital holography system using a special-purpose computer for image reconstruction. Parallel phase-shifting digital holography is a technique capable of single-shot phase-shifting interferometry. This technique records information of multiple phase-shifted holograms required for calculation of phase-shifting interferometry with a single shot by using space-division multiplexing. This technique needs image-reconstruction process for a huge amount of recorded holograms. In particular, it takes a long time to calculate light propagation based on fast Fourier transform in the process and to obtain a motion picture of a dynamically and fast moving object. Then we designed a special-purpose computer for accelerating the image-reconstruction process of parallel phase-shifting digital holography. We developed a special-purpose computer consisting of VC707 evaluation kit (Xilinx Inc.) which is a field programmable gate array board. We also recorded holograms consisting of 128 × 128 pixels at a frame rate of 180,000 frames per second by the constructed parallel phase-shifting digital holography system. By applying the developed computer to the recorded holograms, we confirmed that the designed computer can accelerate the calculation of image-reconstruction process of parallel phase-shifting digital holography ~50 times faster than a CPU.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  5. Multiple bit differential detection of offset quadrature phase-shift-keying

    NASA Technical Reports Server (NTRS)

    Simon, M.

    2003-01-01

    Analogous to multiple symbol differential detectionof quadrature phase-shift-keying (QPSK), a multiple bit differential detection scheme is described for offset QPSK that also exhibits continuous improvement in performance with increasing observation interval. Being derived from maximum-likelihood (ML) considerations, the proposed scheme is purported to be the most power efficient scheme for such a modulation and detection method. Extension of the results to shaped offset QPSK is also possible.

  6. Note: Rapid offset reduction of impedance bridges taking into account instrumental damping and phase shifting.

    PubMed

    van der Wel, C M; Kortschot, R J; Bakelaar, I A; Erné, B H; Kuipers, B W M

    2013-03-01

    The sensitivity of an imperfectly balanced impedance bridge is limited by the remaining offset voltage. Here, we present a procedure for offset reduction in impedance measurements using a lock-in amplifier, by applying a complex compensating voltage external to the bridge. This procedure takes into account instrumental damping and phase shifting, which generally occur at the high end of the operational frequency range. Measurements demonstrate that the output of the circuit rapidly converges to the instrumentally limited noise at any frequency.

  7. The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD

    SciTech Connect

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

    2012-02-16

    The π+π+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of mπ ≈ 390 MeV with an anisotropic nf = 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 bs ≈ 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of π+π+ 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: mπ2 a r = 3+O(mπ2χ2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.

  8. Atomic multiple-wave interferometer phase-shifted by the scalar Aharonov-Bohm effect

    SciTech Connect

    Aoki, Takatoshi; Yasuhara, Makoto; Morinaga, Atsuo

    2003-05-01

    A time-domain atomic multiple-wave interferometer using laser-cooled and trapped sodium atoms has been developed under pulsed magnetic fields. Each atomic phase was shifted due to the scalar Aharonov-Bohm effect by applying spatially homogeneous pulsed magnetic fields between numerous Raman excitation laser pulses. Interference fringes with a finesse of 11 were demonstrated for 11 successive Raman pulses and ten magnetic-field pulses.

  9. Using phase shift Granger causality to measure directed connectivity in EEG recordings.

    PubMed

    Marshall, William J; Lackner, Christine L; Marriott, Paul; Santesso, Diane L; Segalowitz, Sidney J

    2014-12-01

    Cortical activity is maintained by neural networks working in tandem. Electroencephalographic (EEG) signals across two sites are said to be coherent with one another when they show consistent phase relations. However, periods of desynchrony beginning with a shift in phase relations are a necessary aspect of information processing. Traditional measures of EEG coherence lack the temporal resolution required to divide the relationship between two signals into periods of synchrony and desynchrony and are unable to specify the direction of information transmission (i.e., which site is leading and which is lagging), a goal referred to as directed connectivity. In this article, the authors introduce a novel method of measuring directed connectivity by applying the framework of Granger causality to phase shift events which are estimated with high temporal resolution. A simulation study is used to verify that the proposed method is able to identify connectivity patterns in situations similar to EEG recordings, such as high levels of noise and linear source mixing. Their method is able to correctly identify both the existence and direction of information transfer, and that the existence of spatiotemporal noise serves to reduce the spread of shift identification due to volume conduction. To demonstrate the method on real data, it is applied to EEG recordings from 18 adolescents during a resting period and auditory and visual vigilance tasks. Their new measure, Phase Shift Granger Causality (PSGC), is able to clearly distinguish between the resting task and the active tasks. The latter have higher rates of connectivity overall and specifically more long-range connections. As expected, the resting task appears to activate more localized neural circuitry, whereas the active tasks appear to increase communication across several neural regions involved in vigilance tasks. The vigilance tasks also showed significantly higher clustering coefficients than the resting task, a property

  10. Simple BOTDA temperature sensor based on distributed Brillouin phase-shift measurements within a Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    López-Gil, Alexia; Angulo-Vinuesa, Xabier; Dominguez-López, Alejandro; Martín-López, Sonia; González-Herráez, Miguel

    2015-09-01

    In this work we demonstrate an extremely simple BOTDA scheme capable of delivering distributed Brillouin Phase Shift measurements along an optical fiber. It is based on exploiting the non-reciprocity of the Stimulated Brillouin Scattering effect. This non-reciprocity is easily characterized by means of a suitably tuned Sagnac Interferometer. The technique is advantageous as, in comparison with previous methods, no complex modulation, no sharp filtering and no highbandwidth detection is needed. Theoretical and experimental proofs of the concept are given.

  11. Cloud-Based Automated Design and Additive Manufacturing: A Usage Data-Enabled Paradigm Shift

    PubMed Central

    Lehmhus, Dirk; Wuest, Thorsten; Wellsandt, Stefan; Bosse, Stefan; Kaihara, Toshiya; Thoben, Klaus-Dieter; Busse, Matthias

    2015-01-01

    Integration of sensors into various kinds of products and machines provides access to in-depth usage information as basis for product optimization. Presently, this large potential for more user-friendly and efficient products is not being realized because (a) sensor integration and thus usage information is not available on a large scale and (b) product optimization requires considerable efforts in terms of manpower and adaptation of production equipment. However, with the advent of cloud-based services and highly flexible additive manufacturing techniques, these obstacles are currently crumbling away at rapid pace. The present study explores the state of the art in gathering and evaluating product usage and life cycle data, additive manufacturing and sensor integration, automated design and cloud-based services in manufacturing. By joining and extrapolating development trends in these areas, it delimits the foundations of a manufacturing concept that will allow continuous and economically viable product optimization on a general, user group or individual user level. This projection is checked against three different application scenarios, each of which stresses different aspects of the underlying holistic concept. The following discussion identifies critical issues and research needs by adopting the relevant stakeholder perspectives. PMID:26703606

  12. Cloud-Based Automated Design and Additive Manufacturing: A Usage Data-Enabled Paradigm Shift.

    PubMed

    Lehmhus, Dirk; Wuest, Thorsten; Wellsandt, Stefan; Bosse, Stefan; Kaihara, Toshiya; Thoben, Klaus-Dieter; Busse, Matthias

    2015-12-19

    Integration of sensors into various kinds of products and machines provides access to in-depth usage information as basis for product optimization. Presently, this large potential for more user-friendly and efficient products is not being realized because (a) sensor integration and thus usage information is not available on a large scale and (b) product optimization requires considerable efforts in terms of manpower and adaptation of production equipment. However, with the advent of cloud-based services and highly flexible additive manufacturing techniques, these obstacles are currently crumbling away at rapid pace. The present study explores the state of the art in gathering and evaluating product usage and life cycle data, additive manufacturing and sensor integration, automated design and cloud-based services in manufacturing. By joining and extrapolating development trends in these areas, it delimits the foundations of a manufacturing concept that will allow continuous and economically viable product optimization on a general, user group or individual user level. This projection is checked against three different application scenarios, each of which stresses different aspects of the underlying holistic concept. The following discussion identifies critical issues and research needs by adopting the relevant stakeholder perspectives.

  13. Study of key technology of ghost imaging via compressive sensing for a phase object based on phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Leihong, Zhang; Dong, Liang; Bei, Li; Zilan, Pan; Dawei, Zhang; Xiuhua, Ma

    2015-07-01

    In this article, the algorithm of compressing sensing is used to improve the imaging resolution and realize ghost imaging via compressive sensing for a phase object based on the theoretical analysis of the lensless Fourier imaging of the algorithm of ghost imaging based on phase-shifting digital holography. The algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography uses the bucket detector to measure the total light intensity of the interference and the four-step phase-shifting method is used to obtain the total light intensity of differential interference light. The experimental platform is built based on the software simulation, and the experimental results show that the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography can obtain the high-resolution phase distribution figure of the phase object. With the same sampling times, the phase clarity of the phase distribution figure obtained by the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography is higher than that obtained by the algorithm of ghost imaging based on phase-shift digital holography. In this article, this study further extends the application range of ghost imaging and obtains the phase distribution of the phase object.

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

    PubMed

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

    2013-04-22

    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.

  15. M-ary-state phase-shift-keying discrimination below the homodyne limit

    SciTech Connect

    Becerra, F. E.; Fan, J.; Polyakov, S. V.; Migdall, A.; Baumgartner, G.; Goldhar, J.; Kosloski, J. T.

    2011-12-15

    We investigate a strategy for M-ary discrimination of nonorthogonal phase states with error rates below the homodyne limit. This strategy uses feed forward to update a reference field and signal nulling for the state discrimination. We experimentally analyze the receiver performance using postprocessing and a Bayesian strategy to emulate the feed-forward process. This analysis shows that for a moderate system detection efficiency, it is possible to surpass the homodyne error limit for quadrature phase-shift keying signals using feed forward.

  16. Acoustic radiation force expansions in terms of partial wave phase shifts for scattering: Applications

    NASA Astrophysics Data System (ADS)

    Marston, Philip L.; Zhang, Likun

    2016-11-01

    When evaluating radiation forces on spheres in soundfields (with or without orbital-angular momentum) the interpretation of analytical results is greatly simplified by retaining the use of s-function notation for partial-wave coefficients imported into acoustics from quantum scattering theory in the 1970s. This facilitates easy interpretation of various efficiency factors. For situations in which dissipation is negligible, each partial-wave s-function becomes characterized by a single parameter: a phase shift allowing for all possible situations. These phase shifts are associated with scattering by plane traveling waves and the incident wavefield of interest is separately parameterized. (When considering outcomes, the method of fabricating symmetric objects having a desirable set of phase shifts becomes a separate issue.) The existence of negative radiation force "islands" for beams reported in 2006 by Marston is manifested. This approach and consideration of conservation theorems illustrate the unphysical nature of various claims made by other researchers. This approach is also directly relevant to objects in standing waves. Supported by ONR.

  17. Error Analysis in a Device to Test Optical Systems by Using Ronchi Test and Phase Shifting

    SciTech Connect

    Cabrera-Perez, Brasilia; Castro-Ramos, Jorge; Gordiano-Alvarado, Gabriel; Vazquez y Montiel, Sergio

    2008-04-15

    In optical workshops, Ronchi test is used to determine the optical quality of any concave surface, while it is in the polishing process its quality is verified. The Ronchi test is one of the simplest and most effective methods used for evaluating and measuring aberrations. In this work, we describe a device to test converging mirrors and lenses either with small F/numbers or large F/numbers, using LED (Light-Emitting Diode) that has been adapted in the Ronchi testing as source of illumination. With LED used the radiation angle is bigger than common LED. It uses external power supplies to have well stability intensity to avoid error during the phase shift. The setup also has the advantage to receive automatic input and output data, this is possible because phase shifting interferometry and a square Ronchi ruling with a variable intensity LED were used. Error analysis of the different parameters involved in the test of Ronchi was made. For example, we analyze the error in the shifting of phase, the error introduced by the movement of the motor, misalignments of x-axis, y-axis and z-axis of the surface under test, error in the period of the grid used.

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

    NASA Astrophysics Data System (ADS)

    Arroyo, Sebastián I.; Zanette, Damián H.

    2016-01-01

    We address two aspects of the dynamics of the forced Duffing oscillator which are relevant to the technology of micromechanical devices and, at the same time, 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 http://dx.doi.org/10.1140/epjb/e2015-60517-3

  19. I=2{pi}{pi} scattering phase shift with two flavors of Oa improved dynamical quarks

    SciTech Connect

    Yamazaki, T.; Aoki, S.; Kanaya, K.; Fukugita, M.; Ishikawa, K-I.; Okawa, M.; Ishizuka, N.; Iwasaki, Y.; Ukawa, A.; Yoshie, T.; Kaneko, T.; Kuramashi, Y.

    2004-10-01

    We present a lattice QCD calculation of phase shift including the chiral and continuum extrapolations in two-flavor QCD. The calculation is carried out for I=2 S-wave {pi}{pi} scattering. The phase shift is evaluated for two momentum systems, the center of mass and laboratory systems, by using the finite-volume method proposed by Luescher in the center of mass system and its extension to general systems by Rummukainen and Gottlieb. The measurements are made at three different bare couplings {beta}=1.80, 1.95 and 2.10 using a renormalization group improved gauge and a tadpole improved clover fermion action, and employing a set of configurations generated for hadron spectroscopy in our previous work. The illustrative values we obtain for the phase shift in the continuum limit are {delta}(deg.)=-3.50(64), -9.5(30) and -16.9(64) for {radical}(s)(GeV)=0.4, 0.6 and 0.8, which are consistent with experiments.

  20. Phase shift due to atom-atom interactions in a light-pulse atom interferometer

    NASA Astrophysics Data System (ADS)

    Jannin, Raphaël; Cladé, Pierre; Guellati-Khélifa, Saïda

    2015-07-01

    We present a theoretical model allowing precise calculation of the phase shift induced by atom-atom interactions in a light-pulse atom interferometer based on two-photon Raman atom optics. This model is in good agreement with numerical simulations based on solving the Gross-Pitaevskii equation. The atom interferometer exhibits an atom-atom-interaction-induced phase shift when there is asymmetry between the two arms of the interferometer. In the case of a Ramsey-Bordé atom interferometer ({π /2 -π /2 }-{π /2 -π /2 } pulse configuration), the asymmetry comes from the fact that the number of atoms in each arm of the interferometer is not constant. In the case of a Mach-Zehnder ({π /2 -π -π /2 } pulse sequence), if the pulses are perfect, the number of atoms is constant in the interferometer. We study the effect due to imperfections of the light pulses as well as the effect due to the expansion of the cloud. Our model leads to precise and simple formulas of the mean-field phase shift as a function of the experimental parameters.

  1. Four-step phase-shifting digital holography simultaneously sensing dual-wavelength information using a monochromatic image sensor

    NASA Astrophysics Data System (ADS)

    Tahara, Tatsuki; Mori, Ryota; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-12-01

    Four-step phase-shifting digital holography simultaneously sensing dual-wavelength information from wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves at multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Two-step phase-shifting interferometry is merged into the procedures to decrease the number of the recorded holograms. The proposed technique is numerically investigated and experimentally demonstrated. The applicability to the case where the number of wavelengths is more than two and possible noise when using two-step phase-shifting interferometry are discussed.

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

    NASA Astrophysics Data System (ADS)

    Iqbal, S.; Besar, R.; Venkataseshaiah, C.

    2010-05-01

    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.

  3. Circadian rhythm of catecholamine excretion in rats after phase shift of light-dark cycle.

    PubMed

    Sudo, A; Miki, K

    1995-01-01

    To clarify the time course of circadian rhythm adaptation to a phase shift of the light-dark (LD) cycle, urinary excretion of catecholamines was measured in rats before and after a 12-hour or 6-hour phase delay of a 12-hour light and 12-hour dark schedule. In rats under a basal condition, distinct circadian rhythms in catecholamine excretion were observed, especially in adrenaline excretion. During the 1st and 2nd days after a 12-hour phase delay, the acrophase and amplitude of adrenaline rhythm remained almost unchanged, but thereafter the acrophase was retarded and the amplitude was reduced. The acrophase once again became constant after 5 or 6 days, but the ratio of amplitude to mesor in the circadian rhythm of adrenaline excretion and the ratio of light-period to 24-hour noradrenaline excretion were readjusted to the new LD schedule on 11th or 12th day. IN the 6-hour phase delay of the LD cycle, similar findings were observed, and the results suggested adaptation on the 5-6th day. It is considered that the circadian rhythms of the sympathetic adrenomedullary function are restored, at the latest, 12 days after a 12-hour delay of the LD cycle, and 6 days after a 6-hour delay, suggesting that rats need approximately 1 day to adapt to a 1-hour phase shift.

  4. Round-robin differential quadrature phase-shift quantum key distribution

    NASA Astrophysics Data System (ADS)

    Zhou, Chun; Zhang, Ying-Ying; Bao, Wan-Su; Li, Hong-Wei; Wang, Yang; Jiang, Mu-Sheng

    2017-02-01

    Recently, a round-robin differential phase-shift (RRDPS) protocol was proposed [Nature 509, 475 (2014)], in which the amount of leakage is bounded without monitoring the signal disturbance. Introducing states of the phase-encoded Bennett–Brassard 1984 protocol (PE-BB84) to the RRDPS, this paper presents another quantum key distribution protocol called round-robin differential quadrature phase-shift (RRDQPS) quantum key distribution. Regarding a train of many pulses as a single packet, the sender modulates the phase of each pulse by one of {0, π/2, π, 3π/2}, then the receiver measures each packet with a Mach–Zehnder interferometer having a phase basis of 0 or π/2. The RRDQPS protocol can be implemented with essential similar hardware to the PE-BB84, so it has great compatibility with the current quantum system. Here we analyze the security of the RRDQPS protocol against the intercept-resend attack and the beam-splitting attack. Results show that the proposed protocol inherits the advantages arising from the simplicity of the RRDPS protocol and is more robust against these attacks than the original protocol. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505261 and 11304397) and the National Basic Research Program of China (Grant No. 2013CB338002)

  5. Two-step phase-shift interferometry with known but arbitrary reference waves: a graphical interpretation.

    PubMed

    Sabitov, Nail; Meinecke, Thomas; Kelly, Damien P; Sinzinger, Stefan

    2012-10-01

    There are many applications in biology and metrology where it is important to be able to measure both the amplitude and phase of an optical wave field. There are several different techniques for making this type of measurement, including digital holography and phase retrieval methods. In this paper we propose an analytical generalization of this two-step phase-shifting algorithm. We investigate how to reconstruct the object signal if both reference waves are different in phase and amplitude. The resulting equations produce two different solutions and hence an ambiguity remains as to the correct solution. Because of the complexity of the generalized analytical expressions we propose a graphical-vectorial method for solution of this ambiguity problem. Combining our graphical method with a constraint on the amplitude of the object field we can unambiguously determine the correct result. The results of the simulation are presented and discussed.

  6. Shift in metabolism towards ethanol production in Saccharomyces cerevisiae by addition of metabolic inhibitors

    SciTech Connect

    Hahn-Haegerdal, B.; Mattiasson, B.

    1982-01-01

    The future exploitation of fermentation processes for the production of bulk chemicals will very much depend on whether product yield and product concentration can be improved. At the present time the cost for the raw material and the product upgrading limits the competitiveness of fermentation processes in relation to petrochemical processes. Much effort is put into selecting microbial strains with higher product yields as well as improved tolerance towards increased product concentrations. This approach is rather laborious and time-consuming and the overall goal will be beneficial if it is complemented with other techniques. This investigation will describe how productivity migh be improved by addition of a specific metabolic inhibitor, sodium azide, which inhibits the cytochrome oxidase of the respiratory chain. As a model for these studies Saccaromyces cerevisiae fermenting glucose to ethanol was chosen.

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

    PubMed

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

    2012-04-01

    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.

  8. All-optical phase and amplitude regeneration of return-to-zero differential phase shift keying data.

    PubMed

    Awad, Ehab S; Cho, Pak S; Goldhar, Julius

    2007-02-15

    We report a novel implementation of an all-optical rephasing, reshaping, and reamplification differential phase shift keying (DPSK) regenerator. The rephasing is based on converting phase noise into amplitude noise by using an interferometric configuration and then eliminating the amplitude noise by using a semiconductor optical amplifier (SOA). The reshaping is performed using gain competition and gain compression in a saturated SOA. The scheme was tested using 10Gbit/s, 2(23)-1 pseudorandom bit sequence return-to-zero DPSK data. The measurement shows removal of the degraded data error floor with a 6 order-of-magnitude improvement in bit-error rate. The measured negative power penalty is about 4dB. Mathematical analysis shows a reduction in DPSK phase-noise power by half.

  9. Sub-70-nm pattern fabrication using an alternating phase-shifting mask in 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Irie, Shigeo; Kanda, Noriyoshi; Watanabe, Kunio; Suganaga, Toshifumi; Itani, Toshiro

    2002-07-01

    In Selete, we have developed various resolution-enhancement technologies (RETs) such as the alternating phase shifting mask (alt-PSM), attenuated-PSM (att-PSM), and off-axis illumination (OAI). The alt-PSM, for example, reduces the k1 factor and extends the lithographic performance. A problem concerning the alt-PSM is the difference in the transmitted light intensities of the non-phase-shifting region and the phase-shifting region which can cause critical-dimension (CD) placement error. The transmitted light intensities of the two regions can be made equal by side-etching, in which the quartz (Qz) is undercut by wet-etching at the side of the transmitting region. We sought to optimize the mask structure in terms of a high numerical aperture (NA) through a simulation using two kinds of structures with a 157 nm exposure wavelength. The structures were a single-trench structure and a dual-trench structure, with each trench dug in the transmitting region. To attain a high NA (NA equals 0.85), we tried to optimize the parameters of the Cr film thickness, the amount of the undercut (side-etching), and the phase shift. The evaluated line pattern sizes were 70 nm (line/space size equals 70/70 nm, 70/140 nm, 70/210 nm, and 70/350 nm) and 50 nm (line/space size equals 50/50 nm, 50/100 nm, 50/150 nm, and 50/250 nm) at the wafer. Further, using the optimized mask, we calculated the lithographic margin of a sub 70 nm pattern through a simulation. For the 70 nm line patterns, we found that it will be difficult to fabricate precisely a 70 nm line patten using a mask with a single- trench structure. And we also found that the most suitable conditions for the dual-trench structure mask were a 90 nm undercut, a 100 nm Cr film thickness, and a 180 degree(s) phase shift. The exposure latitude at a depth of focus (DOF) of 0.3 micrometers , simulated using the optimized mask, was 5.3% for the 70/70 nm pattern, 3.6% for 70/140 nm 16.0% for 70/210 nm, and 29.3% for 70/350 nm. As the pitch

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

    NASA Astrophysics Data System (ADS)

    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

  11. Phase noise optimization in temporal phase-shifting digital holography with partial coherence light sources and its application in quantitative cell imaging.

    PubMed

    Remmersmann, Christian; Stürwald, Stephan; Kemper, Björn; Langehanenberg, Patrik; von Bally, Gert

    2009-03-10

    In temporal phase-shifting-based digital holographic microscopy, high-resolution phase contrast imaging requires optimized conditions for hologram recording and phase retrieval. To optimize the phase resolution, for the example of a variable three-step algorithm, a theoretical analysis on statistical errors, digitalization errors, uncorrelated errors, and errors due to a misaligned temporal phase shift is carried out. In a second step the theoretically predicted results are compared to the measured phase noise obtained from comparative experimental investigations with several coherent and partially coherent light sources. Finally, the applicability for noise reduction is demonstrated by quantitative phase contrast imaging of pancreas tumor cells.

  12. Phase shift method to estimate solids circulation rate in circulating fluidized beds

    SciTech Connect

    Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

    2013-01-01

    While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in the return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.

  13. Atmospheric Peroxy Radical Measurements by Chemical Amplification - Cavity Attenuated Phase Shift Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wood, E. C.; Charest, J. R.

    2013-12-01

    We present a new chemical amplifier for the detection of peroxy radicals using Cavity Attenuated Phase Shift spectroscopy (CAPS) detection of NO2. The amplification scheme is similar to other chemical amplifiers and involves addition of CO (8%) and NO (3 ppm) to air sampled in a PFA tube. The chain length is quantified by amplification of a known concentration of methyl peroxy radicals (CH3O2) and peroxyacetyl radicals (CH3COO2) sampled by the instrument's reactor. The CH3O2 and CH3COO2 radicals are produced by photolysis of acetone at 254 nm and quantified by conversion to NO2 by reaction with excess NO. The chain length (CL) in dry air is over 200 and constant at RO2 concentrations under 500 ppt. The CL decreases by 55% at a relative humidity of 50%. A 0.95 cm (3/8') ID PFA tube, a 0.32 cm (1/8' ID) PFA tube, and a 0.48 cm ID quartz reactor give near-identical chain lengths and RH dependence, demonstrating the small importance of wall reactions (for clean tubing) as radical termination steps. The instrument comprises two independent inlets and CAPS detectors, allowing for simultaneous measurements in ROx mode (= NO2 + O3 + RO2 + HO2) and Ox mode (= NO2 + O3) thereby greatly reducing the effect of variations in background [Ox]. The 1σ precision of the instrument at constant background [Ox] and 0% relative humidity is 0.2 ppt ROx with 100 second averaging and increases to 0.3 ppt at an RH of 50%. The absolute uncertainty of the measurements is estimated as 20% and is affected by the accuracy of the NO2 calibration, the precision of the CAPS when calibrating at low RO2 concentrations, and the uncertainty in the photolysis quantum yield for the CH3CO + CH3 channel of acetone photolysis.

  14. Restricted feeding phase shifts clock gene and sodium glucose cotransporter 1 (SGLT1) expression in rats.

    PubMed

    Balakrishnan, Anita; Stearns, Adam T; Ashley, Stanley W; Tavakkolizadeh, Ali; Rhoads, David B

    2010-05-01

    The intestine exhibits striking diurnal rhythmicity in glucose uptake, mediated by the sodium glucose cotransporter (SGLT1); however, regulatory pathways for these rhythms remain incompletely characterized. We hypothesized that SGLT1 rhythmicity is linked to the circadian clock. To investigate this, we examined rhythmicity of Sglt1 and individual clock genes in rats that consumed food ad libitum (AL). We further compared phase shifts of Sglt1 and clock genes in a second group of rats following restricted feeding to either the dark (DF) or light (LF) phase. Rats fed during the DF were pair-fed to rats fed during the LF. Jejunal mucosa was harvested across the diurnal period to generate expression profiles of Sglt1 and clock genes Clock, Bmal1 (brain-muscle Arnt-like 1), ReverbA/B, Per(Period) 1/2, and Cry (Cryptochrome) 1/2. All clock genes were rhythmic in AL rats (P < 0.05). Sglt1 also exhibited diurnal rhythmicity, with peak expression preceding nutrient arrival (P < 0.05). Light-restricted feeding shifted the expression rhythms of Sglt1 and most clock genes (Bmal1, ReverbA and B, Per1, Per2, and Cry1) compared with dark-restricted feeding (P < 0.05). The Sglt1 rhythm shifted in parallel with rhythms of Per1 and ReverbB. These effects of restricted feeding highlight luminal nutrients as a key Zeitgeber in the intestine, capable of simultaneously shifting the phases of transporter and clock gene expression, and suggest a role for clock genes in regulating Sglt1 and therefore glucose uptake. Understanding the regulatory cues governing rhythms in intestinal function may allow new therapeutic options for conditions of dysregulated absorption such as diabetes and obesity.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  16. Characterization and Suppression of the Electromagnetic Interference Induced Phase Shift in the JLab FEL Photo - Injector Advanced Drive Laser System

    SciTech Connect

    F. G. Wilson, D. Sexton, S. Zhang

    2011-09-01

    The drive laser for the photo-cathode gun used in the JLab Free Electron Laser (FEL) facility had been experiencing various phase shifts on the order of tens of degrees (>20{sup o} at 1497 MHz or >40ps) when changing the Advanced Drive Laser (ADL) [2][3][4] micro-pulse frequencies. These phase shifts introduced multiple complications when trying to setup the accelerator for operation, ultimately inhibiting the robustness and overall performance of the FEL. Through rigorous phase measurements and systematic characterizations, we determined that the phase shifts could be attributed to electromagnetic interference (EMI) coupling into the ADL phase control loop, and subsequently resolved the issue of phase shift to within tenths of a degree (<0.5{sup o} at 1497 MHz or <1ps). The diagnostic method developed and the knowledge gained through the entire process will prove to be invaluable for future designs of similar systems.

  17. Fiber nonlinear tolerance comparison between 112 Gb/s coherent transmission systems using quadrature-phase-shift-keying, offset quadrature-phase-shift-keying, and minimum-shift-keying formats

    NASA Astrophysics Data System (ADS)

    Zhang, Fangzheng; Wu, Jian; Li, Yan; Lin, Jintong

    2012-10-01

    We numerically investigate the nonlinear transmission performance of 112 Gb/s coherent transmission systems using polarization multiplexed quadrature-phase-shift-keying (QPSK), offset QPSK (OQPSK) and minimum-shift-keying (MSK) formats, and compare the fiber nonlinear tolerances of the three modulation formats. Simulation results show that in both single channel and wavelength-division-multiplexed (WDM) systems, OQPSK is slightly more resistant to fiber nonlinearities than QPSK, and MSK has the best fiber nonlinear tolerance. The advantage of MSK format over QPSK and OQPSK is particularly notable in WDM systems. When digital back propagation (DBP) is used in the digital coherent receiver for intra-channel fiber nonlinearity compensation, system performance is improved with better Q-factor, enlarged input optical power range and extended transmission distance. It is found that the use of DBP brings the largest performance improvement in QPSK system and the least performance improvement in MSK system although MSK system has better fiber nonlinear tolerance.

  18. Rectangular QPSK for generation of optical eight-ary phase-shift keying.

    PubMed

    Lu, Guo-Wei; Sakamoto, Takahide; Kawanishi, Tetsuya

    2011-09-12

    Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.

  19. Alternative phase-shifting technique for measuring full-field refractive index

    NASA Astrophysics Data System (ADS)

    Chen, Kun-Huang; Chen, Jing-Heng; Lin, Jiun-You; Chu, Yen-Chang

    2015-09-01

    This study proposes an alternative and simple method for measuring full-field refractive index. This method is based on the phase-shifting technique with a modulated electro-optical (EO) modulator and the phenomenon of total internal reflection. To this purpose, a linear polarized light is expanded and incident on the interface between the prism and the tested specimen, and the reflected light passes through an analyzer for interference. The phase difference between the s- and p-polarized light is sensitive to the refractive index of the tested specimen when the total internal reflection appears on this interface. Based on this effect, the resulting phase differences make it possible to analyze the refractive index of the tested specimen through a phase-shifting technique with a modulated EO modulator. The feasibility of this method was verified by experiment, and the measurement resolution can reach a value of refractive index unit of at least 3.552×10-4. This method has advantages of simple installation, ease of operation, and fast measurement.

  20. Measurement of displacement using phase shifted wedge plate lateral shearing interferometry

    NASA Astrophysics Data System (ADS)

    Disawal, Reena; Prakash, Shashi

    2016-03-01

    In present communication, a simple technique for measurement of displacement using phase shifted wedge plate lateral shearing interferometry is described. The light beam from laser is expanded and illuminates a wedge plate of relatively large angle. Light transmitted through the wedge plate is converged onto a reflecting specimen using a focusing lens. Back-reflected wavefront from the specimen is incident on the wedge plate. Because of the tilt and shear of the wavefront reflected from the wedge plate, typical straight line fringes appear. These fringes are superimposed onto a sinusoidal grating forming a moiré pattern. The orientation of the moiré fringes is a function of specimen displacement. Four step phase shifting test procedure has been incorporated by translating the grating in phase steps of π/2. Necessary mathematical formulation to establish correlation between the 'difference phase' and the displacement of the specimen surface is undertaken. The technique is automatic and provides resolution and expanded uncertainty of 1 μm and 0.246 μm, respectively. Detailed uncertainty analysis is also reported.

  1. Vehicular motion in counter traffic flow through a series of signals controlled by a phase shift

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi; Tobita, Kazuhiro

    2012-10-01

    We study the dynamical behavior of counter traffic flow through a sequence of signals (traffic lights) controlled by a phase shift. There are two lanes for the counter traffic flow: the first lane is for east-bound vehicles and the second lane is for west-bound vehicles. The green-wave strategy is studied in the counter traffic flow where the phase shift of signals in the second lane has opposite sign to that in the first lane. A nonlinear dynamic model of the vehicular motion is presented by nonlinear maps at a low density. There is a distinct difference between the traffic flow in the first lane and that in the second lane. The counter traffic flow exhibits very complex behavior on varying the cycle time, the phase difference, and the split. Also, the fundamental diagram is derived by the use of the cellular automaton (CA) model. The dependence of east-bound and west-bound vehicles on cycle time, phase difference, and density is clarified.

  2. Security of the differential-quadrature-phase-shift quantum key distribution

    NASA Astrophysics Data System (ADS)

    Kawakami, Shun; Sasaki, Toshihiko; Koashi, Masato

    2016-08-01

    One of the simplest methods for implementing quantum key distribution over fiber-optic communication is the Bennett-Brassard 1984 protocol with phase encoding (PE-BB84 protocol), in which the sender uses phase modulation over double pulses from a laser and the receiver uses a passive delayed interferometer. Using essentially the same setup and by regarding a train of many pulses as a single block, one can carry out the so-called differential-quadrature-phase-shift (DQPS) protocol, which is a variant of differential-phase-shift (DPS) protocols. Here we prove the security of the DQPS protocol based on an adaptation of proof techniques for the BB84 protocol, which inherits the advantages arising from the simplicity of the protocol, such as accommodating the use of threshold detectors and simple off-line calibration methods for the light source. We show that the secure key rate of the DQPS protocol in the proof is eight-thirds as high as the rate of the PE-BB84 protocol.

  3. The Effect of Phase and Amplitude Imbalance on the Performance of Offset Quadrature Phase-Shift-Keyed (OQPSK) Communication Systems

    NASA Astrophysics Data System (ADS)

    Tsou, H.

    1998-07-01

    The balanced modulator, which comprises two amplitude-modulation modules, is widely used in phase-modulated communication systems. In practice, the balance between these amplitude-modulation modules is difficult to maintain, and the amplitude and phase imbalances can cause distortion in the signal constellation and introduce undesired interfering tone signal components when such an imperfect modulator is used to modulate the data directly onto the RF carrier. The rendered imperfection inevitably degrades the receiver performance and, in a quadrature phase-shift-keyed (QPSK) system, causes cross talk between the in-phase and quadrature-phase channels. This article summarizes an analysis of the impact of these modulator imbalances on an offset QPSK (OQPSK) communication system in which an OQPSK signal is coherently demodulated by using a carrier reference extracted from a modified QPSK carrier tracking loop. Both carrier-suppression level and bit-error performance are analyzed in this article. The results show that the current Consultative Committee for Space Data Systems (CCSDS) recommendations of 2-deg maximum permissible phase imbalance and 0.2-dB amplitude imbalance are sufficient to provide a 25-dB or more carrier suppression and a system degradation of 1 dB or less at the bit-error probability of 10±4 when the OQPSK system is operated in a reasonable loop SNR region.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  5. Phase behavior and hydrated solid structure in lysophospholipid/long-chain alcohol/water system and effect of cholesterol addition.

    PubMed

    Konno, Yoshikazu; Naito, Noboru; Yoshimura, Akio; Aramaki, Kenji

    2010-01-01

    Phase behavior in lysophospholipid/long-chain alcohol/water system at 80°C was investigated using hexanol and oleyl alcohol as the long-chain alcohol. Similarly to hydrophilic surfactant, a micellar phase in a lysophospholipid/water system transitioned to a lamellar liquid-crystalline phase by the addition of long-chain alcohol. In the oleyl alcohol system the lamellar liquid-crystalline phase was observed in wider region compared to the hexanol system. The effect of cholesterol addition on the phase behavior was also studied. The region of liquid-crystalline phase and (reverse micellar + liquid-crystalline + water) phase shifted towards higher lysophospholipid concentrations. The structure of hydrated solid as well as the transition between lamellar liquid-crystalline phase and hydrated solid was analyzed by X-ray scattering measurement and differential scanning calorimetry measurement. It was revealed that the hydrated solid was α-type crystals with lamellar structure. The hydrated solid (gel)-liquid crystal transition temperature gradually decreased with increasing oleyl alcohol concentration and the decrement was enhanced by the addition of cholesterol.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  7. Microbial and sponge loops modify fish production in phase-shifting coral reefs.

    PubMed

    Silveira, Cynthia B; Silva-Lima, Arthur W; Francini-Filho, Ronaldo B; Marques, Jomar S M; Almeida, Marcelo G; Thompson, Cristiane C; Rezende, Carlos E; Paranhos, Rodolfo; Moura, Rodrigo L; Salomon, Paulo S; Thompson, Fabiano L

    2015-10-01

    Shifts from coral to algae dominance of corals reefs have been correlated to fish biomass loss and increased microbial metabolism. Here we investigated reef benthic and planktonic primary production, benthic dissolved organic carbon (DOC) release and bacterial growth efficiency in the Abrolhos Bank, South Atlantic. Benthic DOC release rates are higher while water column bacterial growth efficiency is lower at impacted reefs. A trophic model based on the benthic and planktonic primary production was able to predict the observed relative fish biomass in healthy reefs. In contrast, in impacted reefs, the observed omnivorous fish biomass is higher, while that of the herbivorous/coralivorous fish is lower than predicted by the primary production-based model. Incorporating recycling of benthic-derived carbon in the model through microbial and sponge loops explains the difference and predicts the relative fish biomass in both reef types. Increased benthic carbon release rates and bacterial carbon metabolism, but decreased bacterial growth efficiency could lead to carbon losses through respiration and account for the uncoupling of benthic and fish production in phase-shifting reefs. Carbon recycling by microbial and sponge loops seems to promote an increase of small-bodied fish productivity in phase-shifting coral reefs.

  8. Entrainment and phase-shifting by centrifugation abolished in mice lacking functional vestibular input

    NASA Astrophysics Data System (ADS)

    Fuller, Charles; Ringgold, Kristyn

    The circadian pacemaker can be phase shifted and entrained by appropriately timed locomotor activity, however the mechanism(s) involved remain poorly understood. Recent work in our lab has suggested the involvement of the vestibular otolith organs in activity-induced changes within the circadian timing system (CTS). For example, we have shown that changes in circa-dian period and phase in response to locomotion (wheel running) require functional macular gravity receptors. We believe the neurovestibular system is responsible for the transduction of gravitoinertial input associated with the types of locomotor activity that are known to af-fect the pacemaker. This study investigated the hypothesis that daily, timed gravitoinertial stimuli, as applied by centrifugation. would induce entrainment of circadian rhythms in only those animals with functional afferent vestibular input. To test this hypothesis, , chemically labyrinthectomized (Labx) mice, mice lacking macular vestibular input (head tilt or hets) and wildtype (WT) littermates were implanted i.p. with biotelemetry and individually housed in a 4-meter diameter centrifuge in constant darkness (DD). After 2 weeks in DD, the mice were exposed daily to 2G via centrifugation from 1000-1200 for 9 weeks. Only WT mice showed entrainment to the daily 2G pulse. The 2G pulse was then re-set to occur at 1200-1400 for 4 weeks. Only WT mice demonstrated a phase shift in response to the re-setting of the 2G pulse and subsequent re-entrainment to the new centrifugation schedule. These results provide further evidence that gravitoinertial stimuli require a functional vestibular system to both en-train and phase shift the CTS. Entrainment among only WT mice supports the role of macular gravity receptive cells in modulation of the CTS while also providing a functional mechanism by which gravitoinertial stimuli, including locomotor activity, may affect the pacemaker.

  9. Simultaneous measurement of thickness and refractive index using phase shifted Coherent Gradient Sensor

    NASA Astrophysics Data System (ADS)

    Disawal, Reena; Suzuki, Takamasa; Prakash, Shashi

    2016-12-01

    We report simultaneous measurement of thickness and refractive index (RI) using Coherent Gradient Sensing (CGS) based interferometric setup. The collimated light beam transmitted through the specimen is analyzed using two gratings in tandem and a spatial filtering arrangement. At the imaging plane, the desired orders superpose yielding interference fringes. Phase shifting interferometric (PSI) technique has been used to obtain the phase information directly. For decoding the information of thickness and RI, the specimen is rotated and the variation in interferometric phase before and after the specimen rotation determined. Simultaneous measurement on a glass plate of thickness 6.019 mm and refractive index of 1.4570 has been demonstrated. Detailed uncertainty analysis is also reported. The expanded uncertainty for thickness and RI in the measurement process was determined to be ±0.005 mm and ±0.00008 respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    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.

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

    PubMed

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

    2017-02-01

    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.

  12. Non-reciprocal phase shift induced by an effective magnetic flux for light

    NASA Astrophysics Data System (ADS)

    Tzuang, Lawrence D.; Fang, Kejie; Nussenzveig, Paulo; Fan, Shanhui; Lipson, Michal

    2014-09-01

    Photons are neutral particles that do not interact directly with a magnetic field. However, recent theoretical work has shown that an effective magnetic field for photons can exist if the phase of light changes with its direction of propagation. This direction-dependent phase indicates the presence of an effective magnetic field, as shown experimentally for electrons in the Aharonov-Bohm experiment. Here, we replicate this experiment using photons. To create this effective magnetic field we construct an on-chip silicon-based Ramsey-type interferometer. This interferometer has been traditionally used to probe the phase of atomic states and here we apply it to probe the phase of photonic states. We experimentally observe an effective magnetic flux between 0 and 2π corresponding to a non-reciprocal 2π phase shift with an interferometer length of 8.35 mm and an interference-fringe extinction ratio of 2.4 dB. This non-reciprocal phase is comparable to those of common monolithically integrated magneto-optical materials.

  13. On the phase shift of reflection high energy electron diffraction intensity oscillations during Ge(001) homoepitaxy by molecular beam epitaxy

    SciTech Connect

    Shin Byungha; Leonard, John P.; McCamy, James W.; Aziz, Michael J.

    2007-03-15

    The authors have conducted a systematic investigation of the phase shift of the reflection high energy electron diffraction (RHEED) intensity oscillations during homoepitaxy of Ge(001) by molecular beam epitaxy for a wide range of diffraction conditions. Their results show that for small incidence angles with a beam azimuth several degrees away from the <110> crystallographic symmetry direction, the phase is independent of incidence angle; however, it starts to shift once the incidence angle is high enough that the (004) Kikuchi line appears in the RHEED pattern. Moreover, under some conditions they observe the oscillations from only the Kikuchi feature and not from the specular spot, and the oscillatory behavior of the Kikuchi feature is almost out of phase with that of the specular spot. They conclude that the phase shift is caused by the overlap of the specular spot and the Kikuchi features, in contrast to models involving dynamical scattering theory for the phase shift. They discuss necessary conditions for avoiding interference.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    This paper presents a Dual Directional Sheared Spatial Phase-Shift Digital Shearography (DDS-SPS-DS) system for simultaneous measurement of strains/displacement derivative in two directions. Two Michelson Interferometers are used as the shearing device to create two shearograms, one in the x-shearing direction and one in the y-shearing direction, which are recorded by a single CCD camera. Two lasers with different wavelengths are used for illumination, and corresponding band pass filters are applied in front of each Michelson Interferometer to avoid cross-interference between the two shearing direction channels. Two perpendicular shearing directions in the two measurement channels introduce two different spatial frequency carriers whose spectrums are orientated in different directions after Fourier Transform. Phase maps of the recorded two shearograms can be obtained by applying a windowed inverse Fourier transform, which enables simultaneous measurement of dual directional strains/displacement derivatives. The new system is well suited for nondestructive testing and strain measurement with a continuous or dynamic load. The capability of the dual directional spatial phase-shift digital shearography system is described by theoretical discussions as well as experiments.

  15. Task-based assessment of phase-shifting interferometer/ellipsometer

    NASA Astrophysics Data System (ADS)

    Rogala, Eric W.

    2002-06-01

    In this presentation, I present a novel phase-shifting interferometer/ellipsometer. The uniqueness arises from the fact that this study is the consolidation of four distinct ideas drawn from the field of optics and the field of statistics. A conventional four-step phase-shifting interferometer is modified to allow for both TE and TM polarized measurements. Maximum-likelihood estimation theory is then used to extract the three parameters of interest, namely the real and imaginary components of the complex index of refraction and the surface profile. Finally, Cramer-Rao lower bounds serve as a quantitative means of assessing the particular system design at the task of estimating the three parameters in question. I will demonstrate the feasibility of the proposed technique with a Mach-Zehnder prototype, and show how three system parameters, namely the incident amplitude and the relationship between the TE and TM polarized light in terms of amplitude and phase, affect the performance. I also show how quantization of the measured irradiance affects the performance.

  16. Theoretical analysis for temporal phase-shifting of volume moiré tomography via double cross gratings

    NASA Astrophysics Data System (ADS)

    Sun, Nan; Yan, Keding; Xue, Liang; Wang, Shouyu

    2014-11-01

    Volume Moiré Tomography (VMT) is an important technique to diagnose the flow field. In this Letter, the characteristic of temporal phase-shifting is analyzed for VMT. When the distance between two cross gratings is not on the Talbot distance, the phase-shifting factors are existed between moiré patterns of different orders. Especially, when the distance conforms to the sub-Talbot distance, the phase-shifting factors are maximum. This characteristic of temporal phaseshifting could be used for real 3-D flow fields reconstruction in the future.

  17. Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

    PubMed

    Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-06-15

    Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    We discuss and measure the phase shift imposed onto a radially polarized light beam when focusing it onto an ^{174} {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 (Hänsch and Schawlow in Opt Commun 13:68-69, 1975).

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

    NASA Astrophysics Data System (ADS)

    Aranda, Vivian; Cortez, Ricardo; Fauci, Lisa

    2011-08-01

    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.

  20. Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

    NASA Technical Reports Server (NTRS)

    Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

    1996-01-01

    1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

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

    NASA Astrophysics Data System (ADS)

    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

  2. Multiparty quantum secret sharing scheme based on the phase shift operations

    NASA Astrophysics Data System (ADS)

    Du, Yu-tao; Bao, Wan-su

    2013-11-01

    Based on a kind of multiparty quantum secret sharing schemes with Bell states, we propose a novel collective attack strategy in this paper. In our strategy, the group of in-attackers can obtain the entire secret information without introducing any error. More interestingly, a new multiparty quantum secret sharing scheme is proposed based on the 3-element phase shift operations. The scheme can resist not only the existing attacks, but also the cheating attack from the dishonest agent. Meanwhile, the scheme improves the efficiency of scheme by reducing the number of the eavesdropping detections and the computation complexity.

  3. Basic Fourier properties for generalized phase shifting and some interesting detuning insensitive algorithms

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    In this manuscript, some interesting properties for generalized or nonuniform phase-shifting algorithms are shown in the Fourier frequency space. A procedure to find algorithms with equal amplitudes for their sampling function transforms is described. We also consider in this procedure the finding of algorithms that are orthogonal for all possible values in the frequency space. This last kind of algorithms should closely satisfy the first order detuning insensitive condition. The procedure consists of the minimization of functionals associated with the desired insensitivity conditions.

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

    DOEpatents

    Naulleau, Patrick; Goldberg, Kenneth Alan

    2000-01-01

    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.

  5. Study of reference waves in single-exposure generalized phase-shifting digital holography.

    PubMed

    Imbe, Masatoshi; Nomura, Takanori

    2013-06-20

    The appropriate reference wave in single-exposure phase-shifting digital holography using a random-complex-amplitude encoded reference wave is experimentally investigated. Although the reference wave is generalized, the quality of reconstructed images depends on it. Furthermore, when the reference wave satisfies a certain condition, reconstructed images cannot be obtained in this method. After the certain condition is presented, the appropriate condition is studied using a speckle property. Experimental results are given to investigate the relations between the quality of reconstructed images and the sizes of speckles of the reference waves. The results prove that the appropriate reference wave exists in this method.

  6. Analysis of all-optical temporal integrator employing phased-shifted DFB-SOA.

    PubMed

    Jia, Xin-Hong; Ji, Xiao-Ling; Xu, Cong; Wang, Zi-Nan; Zhang, Wei-Li

    2014-11-17

    All-optical temporal integrator using phase-shifted distributed-feedback semiconductor optical amplifier (DFB-SOA) is investigated. The influences of system parameters on its energy transmittance and integration error are explored in detail. The numerical analysis shows that, enhanced energy transmittance and integration time window can be simultaneously achieved by increased injected current in the vicinity of lasing threshold. We find that the range of input pulse-width with lower integration error is highly sensitive to the injected optical power, due to gain saturation and induced detuning deviation mechanism. The initial frequency detuning should also be carefully chosen to suppress the integration deviation with ideal waveform output.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  9. Basic Fourier properties for generalized phase shifting and some interesting detuning insensitive algorithms.

    PubMed

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

    2011-07-20

    In this manuscript, some interesting properties for generalized or nonuniform phase-shifting algorithms are shown in the Fourier frequency space. A procedure to find algorithms with equal amplitudes for their sampling function transforms is described. We also consider in this procedure the finding of algorithms that are orthogonal for all possible values in the frequency space. This last kind of algorithms should closely satisfy the first order detuning insensitive condition. The procedure consists of the minimization of functionals associated with the desired insensitivity conditions.

  10. In Situ alignment system for phase-shifting point-diffraction interferometry

    DOEpatents

    Goldberg, Kenneth Alan; Naulleau, Patrick P.

    2000-01-01

    A device and method to facilitate the gross alignment of patterned object- and image-plane masks in optical systems such as the phase-shifting point diffraction interferometer are provided. When an array of similar pinholes or discreet mask fields is used, confusion can occur over the alignment of the focused beams within the field. Adding to the mask pattern a circumscribed or inscribed set of symbols that are identifiable in situ facilitates the unambiguous gross alignment of the object- and/or image-plane masks. Alternatively, a system of markings can be encoded directly into the window shape to accomplish this same task.

  11. Highly sensitive compact refractive index sensor based on phase-shifted sidewall Bragg gratings in slot waveguide.

    PubMed

    Wang, Xin; Madsen, Christi K

    2014-01-01

    The geometrical and physical parameters of phase-shifted sidewall Bragg gratings in a silicon slot waveguide are optimized to possess performance characteristics desirable for integrated optical sensors. By tailoring the spectral response of such phase-shifted sidewall gratings, highly sensitive compact refractive index sensors detecting the resonance wavelength shift or the variation of light intensity are designed with the transfer matrix method. Both refractive index sensors have a minimum detection limit on the order of 10(-6), and a linear response and a compact structure dimension as small as 11.7 μm, offering the capabilities for sensor array and lab-on-a-chip integration. The resonance-shift sensor has a much wider detection range of 1.32 refractive index units than the intensity-measurement sensor. The performance parameters are compared with other refractive index sensors, including Mach-Zehnder interferometers, ring resonators, surface gratings, and phase-shifted gratings in silicon nanowire.

  12. Shifts of Gamma Phase across Primary Visual Cortical Sites Reflect Dynamic Stimulus-Modulated Information Transfer

    PubMed Central

    Besserve, Michel; Lowe, Scott C.; Logothetis, Nikos K.; Schölkopf, Bernhard; Panzeri, Stefano

    2015-01-01

    Distributed neural processing likely entails the capability of networks to reconfigure dynamically the directionality and strength of their functional connections. Yet, the neural mechanisms that may allow such dynamic routing of the information flow are not yet fully understood. We investigated the role of gamma band (50–80 Hz) oscillations in transient modulations of communication among neural populations by using measures of direction-specific causal information transfer. We found that the local phase of gamma-band rhythmic activity exerted a stimulus-modulated and spatially-asymmetric directed effect on the firing rate of spatially separated populations within the primary visual cortex. The relationships between gamma phases at different sites (phase shifts) could be described as a stimulus-modulated gamma-band wave propagating along the spatial directions with the largest information transfer. We observed transient stimulus-related changes in the spatial configuration of phases (compatible with changes in direction of gamma wave propagation) accompanied by a relative increase of the amount of information flowing along the instantaneous direction of the gamma wave. These effects were specific to the gamma-band and suggest that the time-varying relationships between gamma phases at different locations mark, and possibly causally mediate, the dynamic reconfiguration of functional connections. PMID:26394205

  13. 3D phase-shifting fringe projection system on the basis of a tailored free-form mirror.

    PubMed

    Zwick, Susanne; Heist, Stefan; Steinkopf, Ralf; Huber, Sandra; Krause, Sylvio; Bräuer-Burchardt, Christian; Kühmstedt, Peter; Notni, Gunther

    2013-05-10

    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.

  14. High-speed broadband slight-off digital holography based on simultaneous two-step Gouy phase shifting interferometry

    NASA Astrophysics Data System (ADS)

    Lu, Xiaowei; Xu, Shixiang; Li, Jingzhen; Cai, Yi; Fan, Yupeng

    2016-02-01

    It is well known that phase shift is depended on wavelength of light source by traditional optical path difference (OPD) in free space or wave plate methods. In this paper, we demonstrated a slight-off two-step Gouy phase shifting interferometry which is suitable for broadband digital holography. This technique uses Gouy phase shift to introduce π phase differences between two reference arms. A dual-channel interferometer was employed to monitor the Gouy phase-shifting between two orthogonal polarized references and snap imaging with single shot enabling potential real-time and high-speed imaging capabilities. Theoretical analysis and numerical simulation comparisons between the proposed method and some traditional phase shifting approaches for broadband digital holography were given. Accurate recovers can be obtained in ideal conditions by Gouy, OPD in free space and λ/2 wave plate methods. However, when considering of environment influence, the accuracy of the traditional methods declined rapidly, the recover errors are more than 70 and 20 times higher than our proposed method. The results also show that Gouy method can get consistent phase shift for broadband light source with little influence with wavelength.

  15. Measurement of displacement and distance with a polarization phase shifting folded Twyman Green interferometer.

    PubMed

    Chatterjee, Sanjib; Kumar, Y Pavan

    2015-11-20

    A Sagnac interferometer (SI), consisting of a polarization beam splitter (PBS), along with two equally spaced plane mirrors that are inclined at 45° to each other, is transformed into a folded Twyman Green interferometer (TGI) by placing a mirrored parallel plate (MPP) into the hypotenuse arm of the SI. The converging input beam produced by a telescope objective (TO) is split into reflected (s-polarized) and transmitted (p-polarized) components by the PBS. The p- and s-polarized focal spots are made to fall on the mirrored end surfaces of the parallel plate (PP). The retroreflected p- and s-polarized beams become collimated after passing through the TO. A linear shift of the PP in either (longitudinal) direction alters the positions of the p- and s-polarized focal spots and results in a set of converging and diverging spherical wavefronts that interfere to form concentric circular fringes. We applied polarization phase-shifting interferometry to obtain the optical path difference (OPD) variation of the interference field. The displacement is calculated from the OPD variation. A validation experiment has been carried out by introducing known shifts to the PP. The setup can be used for displacement as well as distance measurement.

  16. Mussel bed boundaries as dynamic equilibria: thresholds, phase shifts, and alternative states.

    PubMed

    Donahue, Megan J; Desharnais, Robert A; Robles, Carlos D; Arriola, Patricia

    2011-11-01

    Ecological thresholds are manifested as a sudden shift in state of community composition. Recent reviews emphasize the distinction between thresholds due to phase shifts-a shift in the location of an equilibrium-and those due to alternative states-a switch between two equilibria. Here, we consider the boundary of intertidal mussel beds as an ecological threshold and demonstrate that both types of thresholds may exist simultaneously and in close proximity on the landscape. The discrete lower boundary of intertidal mussel beds was long considered a fixed spatial refuge from sea star predators; that is, the upper limit of sea star predation, determined by desiccation tolerance, fixed the lower boundary of the mussel bed. However, recent field experiments have revealed the operation of equilibrium processes that maintain the vertical position of these boundaries. Here, we cast analytical and simulation models in a landscape framework to show how the discrete lower boundary of the mussel bed is a dynamic predator-prey equilibrium, how the character of that boundary depends on its location in the landscape, and how boundary formation is robust to the scale of local interactions.

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

    NASA Astrophysics Data System (ADS)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2015-09-01

    In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.

  18. Measurement of wavefront structure from large aperture optical components by phase shifting interferometry

    SciTech Connect

    Wolfe, C.R.; Lawson, J.K.; Kellam, M.; Maney, R.T.; Demiris, A.

    1995-05-12

    This paper discusses the results of high spatial resolution measurement of the transmitted or reflected wavefront of optical components using phase shifting interferometry with a wavelength of 6328 {angstrom}. The optical components studied range in size from approximately 50 mm {times} 100 mm to 400 mm {times} 750 mm. Wavefront data, in the form of 3-D phase maps, have been obtained for three regimes of scale length: ``micro roughness``, ``mid-spatial scale``, and ``optical figure/curvature.`` Repetitive wavefront structure has been observed with scale lengths from 10 mm to 100 mm. The amplitude of this structure is typically {lambda}/100 to {lambda}/20. Previously unobserved structure has been detected in optical materials and on the surfaces of components. We are using this data to assist in optimizing laser system design, to qualify optical components and fabrication processes under study in our component development program.

  19. Reduction of translation rate stabilizes circadian rhythm and reduces the magnitude of phase shift.

    PubMed

    Nakajima, Masato; Koinuma, Satoshi; Shigeyoshi, Yasufumi

    2015-08-14

    In the intracellular environment, the circadian oscillator is exposed to molecular noise. Nevertheless, cellular rhythms are robust and show almost constant period length for several weeks. To find which molecular processes modulate the stability, we examined the effects of a sublethal dose of inhibitors for processes in the molecular clock. Inhibition of PER1/2 phosphorylation by CKIε/δ led to reduced amplitude and enhancement of damping, suggesting that inhibition of this process destabilized oscillation. In contrast, moderate inhibition of translation led to stabilization of the circadian oscillation. Moreover, inhibition of translation also reduced magnitude of phase shift. These results suggest that some specific molecular processes are crucial for stabilizing the circadian rhythm, and that the molecular clock may be stabilized by optimizing parameters of some crucial processes in the primary negative feedback loop. Moreover, our findings also suggested that rhythm stability is closely associated with phase stability against stimuli.

  20. XPSK - A new cross-correlated phase-shift keying modulation technique

    NASA Astrophysics Data System (ADS)

    Feher, K.; Kato, S.

    1983-05-01

    A new modulation technique, cross-correlated phase-shift keying (XPSK), has been developed for the bandwidth and power efficient digital transmission. The modulation scheme proposed here, in which a controlled amount of cross correlation is introduced between the in-phase and quadrature channels, has improved the envelope fluctuation of the IJF-OQPSK (QORC) modulation scheme from 3 dB to approximately O dB. Therefore, in nonlinear channels, the power spectrum characteristics of XPSK are better than those of IJF-OQPSK. The Pe performance degradation of the XPSK scheme is within 1.15 dB of the theoretical linear channel performance of QPSK systems. The power spectra of XPSK signal can be controlled by adjusting the amplitude parameter according to the nonlinearity of a specific system to get minimum Pe degradation.

  1. Detection of lack of fusion using opaque additives, phase 1

    NASA Technical Reports Server (NTRS)

    Cook, J. L.

    1972-01-01

    Two major problems in welded aluminum spacecraft structure, reliable nondestructive inspection for incomplete weldment penetration and the rapid oxidation of aluminum surfaces left exposed to the atmosphere are investigated. The approach employed to solve both problems was to employ copper as a coating to prevent oxidation of the aluminum and as an opaque additive in the weldment to enhance X-ray detection in the event of incomplete penetration. Both plasma spray and vacuum vapor deposition techniques were evaluated for depositing the copper. A series of welded panels was made using three thicknesses of vacuum-vapor-deposited copper. All weldments were nondestructively inspected by X-ray, then excised into tensile and bend specimens. Mechanical tests were conducted and all data evaluated. It was determined that the vacuum-vapor-deposited coating was superior to a plasma sprayed coating of the same thickness. The vacuum-vapor-deposited coating was more uniform in thickness, provided complete coverage of the aluminum, and was free of cracks and porosity.

  2. Phase shift of TE and TM modes in an optical fiber due to axial strain (exact solution)

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1992-01-01

    Axial strain may be determined by monitoring the phase shift of modes of a variety of optical fiber sensors. In this paper, the exact solution of a circular optical fiber is used to calculate the phase shift of the TE and TM modes. Whenever an optical fiber is stressed, the optical path length, the index of refraction, and the propagation constants of each fiber mode change. In consequence, the modal phase term, beta(ln)z, of the fields is shifted by an amount Delta phi. In certain cases, it is desirable to control the phase shift term in order to make the fiber either more or less sensitive to certain kinds of strain. It is shown that it can be accomplished by choosing appropriate fiber parameters.

  3. Algorithm for reconstructing wide space-bandwidth information in parallel two-step phase-shifting digital holography.

    PubMed

    Tahara, Tatsuki; Shimozato, Yuki; Xia, Peng; Ito, Yasunori; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu; Kubota, Toshihiro

    2012-08-27

    We propose an image-reconstruction algorithm of parallel phase-shifting digital holography (PPSDH) which is a technique of single-shot phase-shifting interferometry. In the conventional algorithms in PPSDH, the residual 0th-order diffraction wave and the conjugate images cannot be removed completely and a part of space-bandwidth information is discarded. The proposed algorithm can remove these residual images by modifying the calculation of phase-shifting interferometry and by using Fourier transform technique, respectively. Then, several types of complex amplitudes are derived from a recorded hologram according to the directions in which the neighboring pixels used for carrying out the spatial phase-shifting interferometry are aligned. Several distributions are Fourier-transformed and wide space-bandwidth information of the object wave is obtained by selecting the spectrum among the Fourier-transformed images in each region of the spatial frequency domain and synthesizing a Fourier-transformed image from the spectrum.

  4. A practical alternative to chemiluminescence-based detection of nitrogen dioxide: cavity attenuated phase shift spectroscopy.

    PubMed

    Kebabian, Paul L; Wood, Ezra C; Herndon, Scott C; Freedman, Andrew

    2008-08-15

    We present results obtained from a greatly improved version of a previously reported nitrogen dioxide monitor (Anal Chem. 2005, 77, 724-728) that utilizes cavity attenuated phase shift spectroscopy (CAPS). The sensor, which detects the optical absorption of nitrogen dioxide within a 20 nm bandpass centered at 440 nm, comprises a blue light emitting diode, an enclosed stainless steel measurement cell (26 cm length) incorporating a resonant optical cavity of near-confocal design and a vacuum photodiode detector. An analog heterodyne detection scheme is used to measure the phase shift in the waveform of the modulated light transmitted through the cell induced by the presence of nitrogen dioxide within the cell. The sensor, which operates at atmospheric pressure, fits into a 19 in.-rack-mounted instrumentation box, weighs 10 kg, and utilizes 70 W of electrical power with pump included. The sensor response to nitrogen dioxide (calculated as the cotangent of the phase shift) is demonstrated to be linear (r2 > 0.9999) within +/- 1 ppb over a range of 0-320 ppb (by volume). The device exhibits a detection limit (3sigma precision) of less than 60 parts per trillion (0.060 ppb) with 10 s integration, a value derived from measurements at NO2 concentration levels of both 0 and 20 ppb; the detection limit improves as the integration time is increased to several hundred seconds. The observed baseline drift is less than +/- 0.5 ppb overthe course of a month. An intercomparison of measurements of ambient NO2 concentrations over several days using this sensor with a quantum cascade laser-based infrared absorption spectrometer and a standard chemiluminescence-based NOx analyzer is presented. The data from the CAPS sensor are highly correlated (r2 > 0.99) with the other two instruments. The absolute agreement between the CAPS and each of the two other instruments is within the expected statistical noise associated with the infrared laser-based absorption spectrometer (+/- 0.3 ppb

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  6. Coral–algal phase shifts alter fish communities and reduce fisheries production

    PubMed Central

    Ainsworth, Cameron H; Mumby, Peter J

    2015-01-01

    Anthropogenic stress has been shown to reduce coral coverage in ecosystems all over the world. A phase shift towards an algae-dominated system may accompany coral loss. In this case, the composition of the reef-associated fish assemblage will change and human communities relying on reef fisheries for income and food security may be negatively impacted. We present a case study based on the Raja Ampat Archipelago in Eastern Indonesia. Using a dynamic food web model, we simulate the loss of coral reefs with accompanied transition towards an algae-dominated state and quantify the likely change in fish populations and fisheries productivity. One set of simulations represents extreme scenarios, including 100% loss of coral. In this experiment, ecosystem changes are driven by coral loss itself and a degree of habitat dependency by reef fish is assumed. An alternative simulation is presented without assumed habitat dependency, where changes to the ecosystem are driven by historical observations of reef fish communities when coral is lost. The coral–algal phase shift results in reduced biodiversity and ecosystem maturity. Relative increases in the biomass of small-bodied fish species mean higher productivity on reefs overall, but much reduced landings of traditionally targeted species. PMID:24953835

  7. Experimental analysis of time-phase-shift flow sensing based on a piezoelectric peristaltic micropump

    NASA Astrophysics Data System (ADS)

    Huang, Pao-Cheng; Wang, Min-Haw; Chen, Ming-Kun; Jang, Ling-Sheng

    2016-05-01

    Flow rate sensing is a critical issue for piezoelectric-based micropump systems. This paper describes experimental analysis of flow rate sensing in a peristaltic micropump system. Sensing can be integrated with such a pump using piezoelectric actuators based on the time-phase-shift (TPS) method. To do this, an evaluation-window is added on the falling edge of the driving pulse to help detect the flow velocity without affecting the flow rate. We fabricate a prototype piezoelectric peristaltic micropump with three chambers and three piezoelectric actuators. The middle actuator works not only as an actuator for driving fluid but also as a transducer for sensing flow rate. An evaluation-window is performed to ascertain the relationship between the flow rate and the phase shift of output-signal responses from the transducer. The experimental results show that the evaluation-window response of flow rates in a piezoelectric peristaltic micropump has rates of from 5.56‒33.36 μl s-1. The results are extended to propose a practical flow rate sensor, the design of which can be realized easily in the piezoelectric peristaltic micropump system for sensorless responses that can detect flow rate without any sensors or circuits. The proposed TPS method is real-time, integrated, fast, efficient, and suitable for flow rate detection in piezoelectric peristaltic micropumps.

  8. Phase-shift/transmittance measurements in a micro pattern using MPM193EX

    NASA Astrophysics Data System (ADS)

    Nozawa, Hiroto; Ishida, Takayuki; Kato, Satoru; Sato, Osamu; Miyazaki, Koji; Takehisa, Kiwamu; Awamura, Naoki; Takizawa, Hideo; Kusunose, Hal

    2009-04-01

    A new direct Phase-shift/Transmittance measurement tool "MPM193EX" has been developed to respond to the growing demand for higher precision measurements of finer patterns in ArF Lithography. Specifications of MPM193EX are listed below along with corresponding specifications of the conventional tool MPM193. 1) Phase-shift [3 Sigma]: 0.5 deg. (MPM193) => 0.2 deg. (MPM193EX) 2) Transmittance [3 Sigma]: 0.20 % (MPM193) => 0.04 % (MPM193EX) 3) Minimum measurement pattern width: 7.5 μm (MPM193) => 1.0 μm (MPM193EX) Furthermore, new design optics using an ArF Laser and an objective lens with long working distance allows measurements of masks with pellicles. The new method for improving the measurement repeatability is based on elimination of influence from instantaneous fluctuation in interferometer fringes by scanning two adjacent areas simultaneously. Also, MPM193EX is equipped with high-resolution and stable optics. The newly employed auto-focus system in MPM193EX accurately adjusts, by a new image processing method using high-resolution optics, the focus height that is one of the most important factors for measurements in a micro pattern.

  9. Phase shifts, herbivory, and the resilience of coral reefs to climate change.

    PubMed

    Hughes, Terence P; Rodrigues, Maria J; Bellwood, David R; Ceccarelli, Daniela; Hoegh-Guldberg, Ove; McCook, Laurence; Moltschaniwskyj, Natalie; Pratchett, Morgan S; Steneck, Robert S; Willis, Bette

    2007-02-20

    Many coral reefs worldwide have undergone phase shifts to alternate, degraded assemblages because of the combined effects of over-fishing, declining water quality, and the direct and indirect impacts of climate change. Here, we experimentally manipulated the density of large herbivorous fishes to test their influence on the resilience of coral assemblages in the aftermath of regional-scale bleaching in 1998, the largest coral mortality event recorded to date. The experiment was undertaken on the Great Barrier Reef, within a no-fishing reserve where coral abundances and diversity had been sharply reduced by bleaching. In control areas, where fishes were abundant, algal abundance remained low, whereas coral cover almost doubled (to 20%) over a 3 year period, primarily because of recruitment of species that had been locally extirpated by bleaching. In contrast, exclusion of large herbivorous fishes caused a dramatic explosion of macroalgae, which suppressed the fecundity, recruitment, and survival of corals. Consequently, management of fish stocks is a key component in preventing phase shifts and managing reef resilience. Importantly, local stewardship of fishing effort is a tractable goal for conservation of reefs, and this local action can also provide some insurance against larger-scale disturbances such as mass bleaching, which are impractical to manage directly.

  10. Tunable optoelectronic oscillator incorporating a carrier phase-shifted double sideband modulation system

    NASA Astrophysics Data System (ADS)

    Li, Chengxin; Chen, Fushen; Zhang, Jiahong

    2016-01-01

    A tunable optoelectronic oscillator (OEO) implemented by using a carrier phase-shifted double sideband modulation (CPS-DSB) system consisting of an optical coupler (OC), a Mach-Zehnder modulator (MZM) biased at the minimum transmission point, a polarization beam splitter (PBS), and a tunable optical delay line (TODL) is proposed and experimentally demonstrated. The key device in the system is the CPS-DSB system, which functions in conjunction with a chirped fiber Bragg grating (CFBG) in the loop form a high-Q microwave photonic filter (MPF). Through simply adjusting the TODL, the central frequency of the MPF is shifted and the frequency tunability of the OEO can be realized. A detailed theoretical analysis is provided and the results are confirmed by an experiment. A microwave signal with a frequency-tuning range from 7.24 to 14.05 GHz is generated. The phase noise, the long-term stability and the side-mode suppression performance of the generated microwave signal are also investigated.

  11. Optical implementation of cipher block chaining mode algorithm using phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Jeon, Seok-Hee; Gil, Sang-Keun

    2016-12-01

    We propose an optical design of cipher block chaining (CBC) encryption mode using digital holography, which is implemented by the two-step quadrature phase-shifting digital holographic encryption technique using orthogonal polarization. A block of plain text is encrypted with the encryption key by applying the two-step phase-shifting digital holographic method; then, it is changed into cipher text blocks which are digital holograms. Optically, these digital holograms with the encrypted information are Fourier transform holograms and are recorded onto charge-coupled devices with 256 quantization gray levels. This means that the proposed optical CBC encryption is a scheme that has an analog-type of pseudorandom pattern information in the cipher text, while the conventional electronic CBC encryption is a kind of bitwise block message encryption processed by digital bits. Also, the proposed method enables the cryptosystem to have higher security strength and faster processing than the conventional electronic method because of the large two-dimensional (2-D) array key space and parallel processing. The results of computer simulations verify that the proposed optical CBC encryption design is very effective in CBC mode due to fast and secure optical encryption of 2-D data and shows the feasibility for the CBC encryption mode.

  12. Static and dynamic micro deformable mirror characterization by phase-shifting and time-averaged interferometry

    NASA Astrophysics Data System (ADS)

    Liotard, Arnaud; Zamkotsian, Frederic

    2004-09-01

    Since micro deformable mirrors based on Micro-Opto-Electronico-Mechanical Systems (MOEMS) technology would be essential in next generation adaptive optics system, we are designing, realizing and characterizing blocks of this key-component. An in-house designed tiltable mirror (170*100 μm2) has been processed by surface micromachining in the Cronos foundry, and a dedicated characterization bench has been developed for the complete analysis of building blocks as well as operational deformable mirrors. This modular Twyman-Green interferometer allows high in-plane resolution (4μm) or large field of view (40mm). Out-of-plane measurements are performed with phase-shifting interferometry showing highly repeatable results (standard deviation<5nm). Features such as optical quality or electro-mechanical behavior are extracted from these high precision three-dimensional component maps. Range is increased without loosing accuracy by using two-wavelength phase-shifting interferometry authorizing large steps measurements such as 590 nm print-through steps caused by the Cronos process. Dynamic analysis like vibration mode and cut-off frequency is realized with time-averaged interferometry. Rotation mode frequency of 31-3kHz of the micro tiltable mirror, and a resonance with a tuned damping at 1.1kHz of the commercial OKO deformable mirror are revealed.

  13. Acute exposure to 2G phase shifts the rat circadian timing system

    NASA Technical Reports Server (NTRS)

    Hoban-Higgins, T. M.; Murakami, D. M.; Tandon, T.; Fuller, C. A.

    1995-01-01

    The circadian timing system (CTS) provides internal and external temporal coordination of an animal's physiology and behavior. In mammals, the generation and coordination of these circadian rhythms is controlled by a neural pacemaker, the suprachiasmatic nucleus (SCN), located within the hypothalamus. The pacemaker is synchronized to the 24 hour day by time cures (zeitgebers) such as the light/dark cycle. When an animal is exposed to an environment without time cues, the circadian rhythms maintain internal temporal coordination, but exhibit a 'free-running' condition in which the period length is determined by the internal pacemaker. Maintenance of internal and external temporal coordination are critical for normal physiological and psychological function in human and non-human primates. Exposure to altered gravitational environments has been shown to affect the amplitude, mean, and timing of circadian rhythms in species ranging from unicellular organisms to man. However, it has not been determined whether altered gravitational fields have a direct effect on the neural pacemaker, or affect peripheral parameters. In previous studies, the ability of a stimulus to phase shift circadian rhythms was used to determine whether a stimulus has a direct effect on the neural pacemaker. The present experiment was performed in order to determine whether acute exposure to a hyperdynamic field could phase shift circadian rhythms.

  14. Cost-effective overlay and CD metrology on phase-shifting masks

    NASA Astrophysics Data System (ADS)

    McCallum, Martin; Smith, Stewart; Hourd, Andrew; Walton, Anthony J.; Stevenson, J. Tom M.

    2004-12-01

    This paper presents the use of specially designed electrically testable structures to measure characteristics of alternating aperture phase-shifting masks (altPSM). The linewidths of chrome features on the mask are measured using modified cross-bridge structures, the technique behind this is explained together with the specific designs used to characterise both dense and isolated features. A practical, manufacturable solution to overcoming the problem of the non-conductive anti-reflective chromium oxy-nitride is given and results shown to prove its success. Correlation to more conventional CD measurements reinforce this result. A new technique, to measure the overlay of the second laye, used in the mask manufacture as the mask for the quartz etch establishing the phase shifted areas, is discussed. This entails using capacitive test structures in a progressional offset array to establish the minimum capacitance, indicating the overlay achieved. This technique has the added advantage of removing the errors created by mask sag in overlay metrology tools where the mask is held only at the edge. Results are presented indicating the success of this technique.

  15. Coral-algal phase shifts alter fish communities and reduce fisheries production.

    PubMed

    Ainsworth, Cameron H; Mumby, Peter J

    2015-01-01

    Anthropogenic stress has been shown to reduce coral coverage in ecosystems all over the world. A phase shift towards an algae-dominated system may accompany coral loss. In this case, the composition of the reef-associated fish assemblage will change and human communities relying on reef fisheries for income and food security may be negatively impacted. We present a case study based on the Raja Ampat Archipelago in Eastern Indonesia. Using a dynamic food web model, we simulate the loss of coral reefs with accompanied transition towards an algae-dominated state and quantify the likely change in fish populations and fisheries productivity. One set of simulations represents extreme scenarios, including 100% loss of coral. In this experiment, ecosystem changes are driven by coral loss itself and a degree of habitat dependency by reef fish is assumed. An alternative simulation is presented without assumed habitat dependency, where changes to the ecosystem are driven by historical observations of reef fish communities when coral is lost. The coral-algal phase shift results in reduced biodiversity and ecosystem maturity. Relative increases in the biomass of small-bodied fish species mean higher productivity on reefs overall, but much reduced landings of traditionally targeted species.

  16. 3D surface real-time measurement using phase-shifted interference fringe technique for craniofacial identification

    NASA Astrophysics Data System (ADS)

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

    1998-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  18. Transitional liquid crystalline phases between the hexagonal and lamellar phases in ternary cesium N-tetradecanoate-water-additive mixtures

    SciTech Connect

    Blackburn, J.C.; Kilpatrick, P.K. )

    1993-04-01

    The effects of added salt (CsOH, CsCl), long-chain carboxylic acid, and long-chain alcohol on the lyotropic liquid crystalline phase behavior in the cesium n-tetradecanoate (CsTD)-water system is reported. The transitional region between the hexagonal (H) and lamellar (L) phases was the compositional range of focus. Three transitional phases were observed: (i) the ribbon (R) phase, a biaxial phase consisting of cylinders of ellipsoidal cross section; (ii) the viscous isotropic (VI) phase, an isotropic phase thought to consist of interconnected rods on an Ia3d lattice; and (iii) the intermediate (Int) phase, a uniaxial anisotropic phase thought to consist of interconnected rods on a planar lattice. The effect of the additives was to decrease the interfacial curvature of the surfactant head group layer by varying head group repulsion and by varying the surfactant tail volume relative to the surfactant head group area. These changes resulted in formation of transitional phases seeming to possess curvature between that of the cylindrical H phase and the planar L phase. The ionic repulsion between carboxylate head groups was reduced by the addition of CsOH or CsCl, and resulted in destabilization of the VI phase and the formation of the anisotropic Int phase. With the addition of cosurfactants, n-tetradecanoic acid (TDA) and 1-tetradecanol (TDOH), no Int phase was observed. With 7 wt% added TDA the R phase was stabilized up to temperatures of 336 K, above the 330 K temperature limit in the binary CsTD-D[sub 2]O system. In all four systems, sufficient additive (5-10 wt%) resulted in a transition to the L phase, which was stable over a large portion of the compositional range. In order of apparently decreasing mean curvature, the phase sequence is: hexagonal, ribbon, viscous isotropic, intermediate, and lamellar.

  19. High Temperature Chemistry of Chlorinated Acenaphthylene. 3C Bay Acetylene Additions and Annealing by Five-Membered Ring Shifts.

    PubMed

    McIntosh, Grant J; Russell, Douglas K

    2015-12-24

    Experimental and theoretical results concerning the growth and isomerization of chlorinated acenaphthylene, C12H8, during the pyrolysis of chlorohydrocarbons are presented here. A fullerene subunit, C12H8, is a useful system to investigate regarding C60 formation. However, direct experimental observation of isomerization and annealing processes in particular are difficult to confirm due to the high symmetry of the parent molecule. Chlorination lowers the symmetry, essentially labeling carbon atoms, allowing growth and isomerization to be followed directly. Pyrolysis of dichloro- and trichloroethylene, and their copyrolyses with trichlorobenzenes, provides an efficient and general source of chlorinated acenaphthylenes in a range of degrees of chlorination and over a number of unique congeners. Analysis of congener yields as a function of reagents employed, guided by DFT/B3LYP/6-311G(d,p) level calculations, strongly suggests that C2 addition across three-carbon bays in naphthalene is a major driver of growth. Additionally, extremely facile five-membered ring shifts are operative, with chlorine promoting isomerization. Theoretical study of C16H10- and C18H10-based congeners indicate that this is a general phenomenon, and with chlorine also favoring internal cyclopentafused rings in addition to increased isomerization rates, this suggests halogen moieties may be an important feature for efficient fullerene growth.

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

    PubMed

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

    2014-06-17

    Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.

  1. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

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

    PubMed

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

    2013-04-01

    We show for the first time, to the best of our knowledge, that, in a coherent communication system that employs a phase-shift-keying signal and Raman amplification, besides the pump relative intensity noise (RIN) transfer to the amplitude, the signal's phase will also be affected by pump RIN through the pump-signal cross-phase modulation. Although the average pump power induced linear phase change can be compensated for by the phase-correction algorithm, a relative phase noise (RPN) parameter has been found to characterize pump RIN induced stochastic phase noise. This extra phase noise brings non-negligible system impairments in terms of the Q-factor penalty. The calculation shows that copumping leads to much more stringent requirements to pump RIN, and relatively larger fiber dispersion helps to suppress the RPN induced impairment. A higher-order phase-shift keying (PSK) signal is less tolerant to noise than a lower-order PSK.

  3. Phase shift multiplication effect of all-optical analog to electromagnetically induced transparency in two micro-cavities side coupled to a waveguide system

    SciTech Connect

    Wang, Boyun; Wang, Tao Tang, Jian; Li, Xiaoming; Dong, Chuanbo

    2014-01-14

    We propose phase shift multiplication effect of all-optical analog to electromagnetically induced transparency in two photonic crystal micro-cavities side coupled to a waveguide system through external optical pump beams. With dynamically tuning the propagation phase of the line waveguide, the phase shift of the transmission spectrum in two micro-cavities side coupled to a waveguide system is doubled along with the phase shift of the line waveguide. π-phase shift and 2π-phase shift of the transmission spectrum are obtained when the propagation phase of the line waveguide is tuned to 0.5π-phase shift and π-phase shift, respectively. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and the coupled-mode formalism. These results show a new direction to the miniaturization and the low power consumption of microstructure integration photonic devices in optical communication and quantum information processing.

  4. Phase shifts in binaural stimuli provide directional cues for sound localisation in the field cricket Gryllus bimaculatus.

    PubMed

    Seagraves, Kelly M; Hedwig, Berthold

    2014-07-01

    The cricket's auditory system is a highly directional pressure difference receiver whose function is hypothesised to depend on phase relationships between the sound waves propagating through the auditory trachea that connects the left and right hearing organs. We tested this hypothesis by measuring the effect of experimentally constructed phase shifts in acoustic stimuli on phonotactic behavior of Gryllus bimaculatus, the oscillatory response patterns of the tympanic membrane, and the activity of the auditory afferents. The same artificial calling song was played simultaneously at the left and right sides of the cricket, but one sound pattern was shifted in phase by 90 deg (carrier frequencies between 3.6 and 5.4 kHz). All three levels of auditory processing are sensitive to experimentally induced acoustic phase shifts, and the response characteristics are dependent on the carrier frequency of the sound stimulus. At lower frequencies, crickets steered away from the sound leading in phase, while tympanic membrane vibrations and auditory afferent responses were smaller when the ipsilateral sound was leading. In contrast, opposite responses were observed at higher frequencies in all three levels of auditory processing. Minimal responses occurred near the carrier frequency of the cricket's calling song, suggesting a stability at this frequency. Our results indicate that crickets may use directional cues arising from phase shifts in acoustic signals for sound localisation, and that the response properties of pressure difference receivers may be analysed with phase-shifted sound stimuli to further our understanding of how insect auditory systems are adapted for directional processing.

  5. Stereoselective synthesis of cyclohexanones via phase transfer catalyzed double addition of nucleophiles to divinyl ketones.

    PubMed

    Silvanus, Andrew C; Groombridge, Benjamin J; Andrews, Benjamin I; Kociok-Köhn, Gabriele; Carbery, David R

    2010-11-05

    Functionalized cyclohexanones are formed in excellent yield and diastereoselectivity from a phase transfer catalyzed double addition of active methylene pronucleophiles to nonsymmetrical divinyl ketones.

  6. Equal path, phase shifting, sample point interferometer for monitoring the configuration of surfaces

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K. (Inventor)

    1992-01-01

    A system for monitoring the configuration of a surface (e.g., a segmented parabolic surface) using orthogonally placed retroreflectors at sets of points 1, 2, and 3 dispersed throughout the surface with a stationary halfwave plate (HWP) in the front of the one retroreflector at a corner point 3 and a rotating halfwave plate (RHWP) over a source of linearly polarized coherent light, thereby causing the direction of linear polarization to continuously rotate through 360 deg and causing light returned by the retroreflector at point 3 to be continuously phase shifted through 360 deg relative to light returned by retroreflectors at points 1 and 2. The returned light from each set of points 1, 2, and 3 is focused onto a bed-of-nails (BON) phase grating diagonally oriented with respect to the orthogonal orientation of the incident beams from retroreflectors 1, 2, and 3, thereby causing overlap in the light from points 1 and 3 to produce interferometric signals 1,3 and 2,3. Any change in phase of the interferometric signals 1,3 and 2,3 indicates both the magnitude and direction of any change in the position of the retroreflector at point 3 relative to retroreflectors at points 1 and 2.

  7. Comparative analysis of autofocus functions in digital in-line phase-shifting holography.

    PubMed

    Fonseca, Elsa S R; Fiadeiro, Paulo T; Pereira, Manuela; Pinheiro, António

    2016-09-20

    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.

  8. Compressive optical image encryption with two-step-only quadrature phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Hongbing; Li, Jiaosheng; Pan, Yangyang; Li, Rong

    2015-06-01

    An image encryption method which combines two-step-only quadrature phase-shifting digital holography with compressive sensing (CS) has been proposed in the fully optical domain. An object image is firstly encrypted to two on-axis quadrature-phase holograms using the two random phase masks in the Mach-Zehnder interferometer. Then, the two encrypted images are highly compressed to a one-dimensional signal using the single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the two compressive encrypted holograms are exactly reconstructed from much less than the Nyquist sampling number of observations by solving an optimization problem, and the original image can be decrypted with only two reconstructed holograms and the correct keys. This method largely decreases holograms data volume for the current optical image encryption system, and it is also suitable for some special optical imaging cases such as different wavelengths imaging and weak light imaging. Numerical simulation is performed to demonstrate the feasibility and validity of this novel image encryption method.

  9. Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift.

    PubMed

    Ling, S D; Johnson, C R; Frusher, S D; Ridgway, K R

    2009-12-29

    A key consideration in assessing impacts of climate change is the possibility of synergistic effects with other human-induced stressors. In the ocean realm, climate change and overfishing pose two of the greatest challenges to the structure and functioning of marine ecosystems. In eastern Tasmania, temperate coastal waters are warming at approximately four times the global ocean warming average, representing the fastest rate of warming in the Southern Hemisphere. This has driven range extension of the ecologically important long-spined sea urchin (Centrostephanus rodgersii), which has now commenced catastrophic overgrazing of productive Tasmanian kelp beds leading to loss of biodiversity and important rocky reef ecosystem services. Coincident with the overgrazing is heavy fishing of reef-based predators including the spiny lobster Jasus edwardsii. By conducting experiments inside and outside Marine Protected Areas we show that fishing, by removing large predatory lobsters, has reduced the resilience of kelp beds against the climate-driven threat of the sea urchin and thus increased risk of catastrophic shift to widespread sea urchin barrens. This shows that interactions between multiple human-induced stressors can exacerbate nonlinear responses of ecosystems to climate change and limit the adaptive capacity of these systems. Management actions focused on reducing the risk of catastrophic phase shift in ecosystems are particularly urgent in the face of ongoing warming and unprecedented levels of predator removal from the world's oceans.

  10. Temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals.

    PubMed

    Liao, Po-Yu; Liu, Wen-Chung; Cheng, Chih-Hao; Chiu, Yi-Hua; Kung, Ying-Yu; Chang, Shih-Lin

    2015-07-01

    This paper reports temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals, involving forbidden (002) and weak (222) reflections. Phase determination based on multiple-beam diffraction is employed to estimate phase shifts from (002)-based {(002)(375)(373̅)} four-beam cases and (222)-based { (222)(5̅33̅)} three-beam cases in the vicinity of the Ge K edge for temperatures from 20 K up to 300 K. The forbidden/weak reflections enhance the sensitivity of measuring phases at resonance. At room temperature, the resonance triplet phases reach a maximum of 8° for the four-beam cases and -19° for the three-beam cases. It is found that the peak intensities and triplet phases obtained from the (002) four-beam diffraction are related to thermal motion induced anisotropy and anomalous dispersion, while the (222) three-beam diffraction depends on the aspherical covalent electron distribution and anomalous dispersion. However, the electron-phonon interaction usually affects the forbidden reflections with increasing temperatures and seems to have less effect on the resonance triplet phase shifts measured from the (002) four-beam diffraction. The resonance triplet phase shifts of the (222) three-beam diffraction versus temperature are also small.

  11. Error detection and correction for a multiple frequency quaternary phase shift keyed signal

    NASA Astrophysics Data System (ADS)

    Hopkins, Kevin S.

    1989-06-01

    A multiple frequency quaternary phased shift (MFQPSK) signaling system was developed and experimentally tested in a controlled environment. In order to insure that the quality of the received signal is such that information recovery is possible, error detection/correction (EDC) must be used. Various EDC coding schemes available are reviewed and their application to the MFQPSK signal system is analyzed. Hamming, Golay, Bose-Chaudhuri-Hocquenghem (BCH), Reed-Solomon (R-S) block codes as well as convolutional codes are presented and analyzed in the context of specific MFQPSK system parameters. A computer program was developed in order to compute bit error probabilities as a function of signal to noise ratio. Results demonstrate that various EDC schemes are suitable for the MFQPSK signal structure, and that significant performance improvements are possible with the use of certain error correction codes.

  12. Phase-shifting point diffraction interferometer focus-aid enhanced mask

    DOEpatents

    Naulleau, Patrick

    2000-01-01

    A phase-shifting point diffraction interferometer system (PS/PDI) employing a PS/PDI mask that includes a PDI focus aid is provided. The PDI focus aid mask includes a large or secondary reference pinhole that is slightly displaced from the true or primary reference pinhole. The secondary pinhole provides a larger capture tolerance for interferometrically performing fine focus. With the focus-aid enhanced mask, conventional methods such as the knife-edge test can be used to perform an initial (or rough) focus and the secondary (large) pinhole is used to perform interferometric fine focus. Once the system is well focused, high accuracy interferometry can be performed using the primary (small) pinhole.

  13. Application of Ultrasound Phase-Shift Analysis to Authenticate Wooden Panel Paintings

    PubMed Central

    Bravo, José M.; Sánchez-Pérez, Juan V.; Ferri, Marcelino; Redondo, Javier; Picó, Rubén

    2014-01-01

    Artworks are a valuable part of the World's cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated encoding system that enables authentication of the authorship of wooden panel paintings. The method has been evaluated in comparison with optical analysis and shows promising results. The proposed method provides an integrated fingerprint of the artwork, and could be used to enrich the cataloging and protection of artworks. Other advantages that make particularly attractive the proposed technique are its robustness and the use of low-cost sensors. PMID:24803191

  14. Quality investigation of surface mount technology using phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Boonsri, Chantira; Buranasiri, Prathan

    2016-09-01

    Applying of a phase-shifting digital holography combined with compressive sensing to inspect the soldering quality of surface mount technology (SMT) which is a method for producing electronic circuits. In SMT, the components are mounted and connected with each other directly onto the surface of printed circuit boards (PCBs). By reconstructing the multidimensional images from a few samples of SMT, the results are solved by an optimization problem. In this paper, two problems have been concerned. The first one is to examine the devices and the soldering quality of connections between them, which are in micro-scaled. The second is to observe the effect of heat treatment of soldering material and devices on the surface mount board.

  15. Assessment of weak light condition in parallel four-step phase-shifting digital holography.

    PubMed

    Miao, Lin; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2013-01-01

    Minimum optical energy required for four-step parallel phase-shifting digital holography (PPSDH) is evaluated numerically by using photon-counting analysis. PPSDH enables us to develop instantaneous three-dimensional (3D) measurement by single-shot measurement. In fast measurement of dynamic 3D events, detected optical power at an image sensor will be decreased. For biomedical sensing, maximum light intensity exists for preventing the damage of the tissue. In the numerical evaluation, a photon-counting approach is used for the evaluation of minimum detected energy by comparing the reconstructed images. Numerical results indicate that hundreds of photons at each pixel in the image sensor are enough for the reconstruction and total detected energy in a multiplexed hologram is about 1 pJ.

  16. Image formation in phase-shifting digital holography and applications to microscopy.

    PubMed

    Yamaguchi, I; Kato, J; Ohta, S; Mizuno, J

    2001-12-01

    We discuss image formation in phase-shifting digital holography by developing an analytical formulation based on the Fresnel-Kirchhoff diffraction theory. Image-plane position and imaging magnification are derived for general configurations in which a spherical reference is employed. The influences of discrete sampling of the resulting interference patterns by a CCD and numerical reconstruction on qualities of point images are investigated. Dependence of the point images on the ratio of the minimum fringe spacing to pixel pitch of the CCD is numerically analyzed. Two-point resolution and magnification are also investigated as a function of pixel numbers by a simulation using a one-dimensional model. In experiments magnified images of biological objects and a resolution target were reconstructed with the same quality as by conventional microscopy.

  17. Free-viewpoint images captured using phase-shifting synthetic aperture digital holography.

    PubMed

    Nakatsuji, Tatsuya; Matsushima, Kyoji

    2008-07-01

    Free-viewpoint images obtained from phase-shifting synthetic aperture digital holography are given for scenes that include multiple objects and a concave object. The synthetic aperture technique is used to enlarge the effective sensor size and to make it possible to widen the range of changing perspective in the numerical reconstruction. The lensless Fourier setup and its aliasing-free zone are used to avoid aliasing errors arising at the sensor edge and to overcome a common problem in digital holography, namely, a narrow field of view. A change of viewpoint is realized by a double numerical propagation and by clipping the wave field by a given pupil. The computational complexity for calculating an image in the given perspective from the base complex-valued image is estimated at a double fast Fourier transform. The experimental results illustrate the natural change of appearance in cases of both multiple objects and a concave object.

  18. Ultra-fast line-field low coherence holographic elastography using spatial phase shifting.

    PubMed

    Liu, Chih-Hao; Schill, Alexander; Raghunathan, Raksha; Wu, Chen; Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Larin, Kirill V

    2017-02-01

    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.

  19. Ultra-fast line-field low coherence holographic elastography using spatial phase shifting

    PubMed Central

    Liu, Chih-Hao; Schill, Alexander; Raghunathan, Raksha; Wu, Chen; Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Larin, Kirill V.

    2017-01-01

    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. PMID:28270998

  20. Regenerated phase-shifted sinusoids assisted EMD for adaptive analysis of fringe patterns

    NASA Astrophysics Data System (ADS)

    Wang, Chenxing; Kemao, Qian; Da, Feipeng

    2016-12-01

    Fringe patterns are often produced from optical metrology. It is important yet challenging to reduce noise and remove a complicated background in a fringe pattern, for which empirical mode decomposition based methods have been proven useful. However, the mode-mixing problem and the difficulty in automatic mode classification limit the application of these methods. In this paper, a newly developed method named regenerated phase-shifted sinusoids assisted empirical mode decomposition is introduced to decompose a fringe pattern, and subsequently, a new noise-signal-background classification strategy is proposed. The former avoids the mode-mixing problem appearing during the decomposition, while the latter adaptively classifies the decomposition results to remove the noise and background. The proposed method is testified by both simulation and real experiments, which shows effective and robust for fringe pattern analysis under different noise, fringe modulation, and defects.