Manuel Vázquez-Marrufo (4557298), Rocío Caballero-Díaz (9411397), Rubén Martín-Clemente (9411400) et al. · Figshare · 2020
<p>Upper left corner: average instantaneous frequency (IF) of the evoked responses in session 1 (red) and session 2 (orange). Colored area represents the 95% confidence interval of the IF in session 1, meaning that the true value of the IF is inside these limits with a probability of 95%. It is noteworthy that the orange curve also lies in this confidence interval. The remaining illustrations can be interpreted in a similar way. The figure in the upper right corner shows the 95% confidence interval of the evoked IF in session 2. The figures in the bottom row show the IFs of the induced responses and their respective confidence intervals, all of them calculated by an equivalent procedure and in the same time interval.</p>
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Alexander Mörtl (584329), Tamara Lorenz (584330), Sandra Hirche (584331) · Figshare · 2015
<p>(A) Exemplary evolution of the predicted event over time . (B) Corresponding evolution of the phase obtained from (25). The slope of instantaneously relates the left over phase in period to the left over time span . Black dots denote boundary conditions. Gray graphs depict perfect prediction and the harmonic phase respectively.</p>
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Trumper, Isaac, Heejoo Choi, Kim, Dae Wook · Figshare · 2016
An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone <sup>®</sup> 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.
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R. Smythe, R. Moore · Optical Engineering · 1984
Conventional phase measuring interferometry normally requires one-half to sixty seconds acquisition time, limiting measurement to stationary phenomena such as optical element wavefronts. We have developed an instantaneous phase measuring interferometer (PMI) that measures displacements at one point to a resolution of 0.003 um. We describe this instrument and an interferometer measuring phase to X/2000 with a measurement time aperture of less than 1 As. Also described is an attached system for analyzing and displaying wavefronts at up to 10 Hz.
Cited by 203
Thirunarayanan Rajkumar. · DR-NTU (Nanyang Technological University) · 2008
This dissertation is about proposing a totally non-mechanical phase shifter and vibration resistant interferometer. A novel Brewster angle interferometer cavity with a non-mechanical polarizing phase shifter is designed and fabricated.
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Trumper, Isaac, Heejoo Choi, Kim, Dae Wook · Figshare · 2016
An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone <sup>®</sup> 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.
Cited by 0Open access
James E. Millerd, Neal Brock, John Hayes et al. · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004
We demonstrate a phase-shifting, point diffraction interferometer that achieves high accuracy and is capable of measuring a single pulse of light. The measurement system utilizes a polarizing point diffraction plate to generate a synthetic reference beam that is orthogonally polarized to the transmitted test beam. The plate has very high polarization contrast, works over an extremely broad angular and spectral range, and is only 100 nanometers thick. The unique features of the polarizing element make the system amenable to measuring strongly convergent light from high numerical aperture optics without the need to use a point reference source to calibrate the system. Results of measuring optics with numerical apertures as high as NA 0.8 are presented.
Cited by 29
Isaac Trumper (3985133), Heejoo Choi (3959717), Dae Wook Kim (841861) · Figshare · 2017
Trefoil Mode Case Metrology Originally published in Optics Express on 28 November 2016 (oe-24-24-27993)
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Isaac Trumper (3985133), Heejoo Choi (3959717), Dae Wook Kim (841861) · Figshare · 2017
SIngle Actuator Case Metrology Originally published in Optics Express on 28 November 2016 (oe-24-24-27993)
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Aldo Vesnaver · Geophysics · 2016
ABSTRACT The instantaneous phase of a complex trace is normally computed as an inverse tangent function of the ratio between its imaginary and real parts. This algorithm often produces a discontinuous function in the range [−π, +π], as the principal value of the inverse tangent is assumed. The attempt of removing these discontinuities, called phase unwrapping, introduces uncertainties and some personal bias because it requires user-defined parameters. A new algorithm that does not require any of these parameters is presented with the related software code and some application examples. The results indicate a fair robustness of the estimates with respect to the noise, for the instantaneous phase and frequency. In addition, the median-averaged instantaneous frequency is a useful tool for the seismic stratigraphy analysis.
Cited by 15
James E. Millerd, Stephen J. Martinek, Neal Brock et al. · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004
We demonstrate an instantaneous phase-shift, point diffraction interferometer that achieves high accuracy and is capable of measuring a single pulse of light at NA greater than 0.8.
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Vo, Duc Duy · JAIST Repository · 2022
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Rajasimhan Rajagovindan (376068), Mingzhou Ding (48702) · Figshare · 2015
<p>Spearman's rank correlation coefficient between instantaneous causality and magnitude of phase-lag in the beta band between site pairs for monkeys GE and LU. The results that did not meet significance at p<0.05 are included with their corresponding p-value.</p>*<p>denotes the channel pair that exhibits bidirectional interaction in the beta frequency band. The symbol “-” indicates that a value is not available.</p>
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Lagunas Hernandez, Miguel A. · QRU Quaderns de Recerca en Urbanisme · 1988
Envelope and instantaneous phase of a real signal are two concepts mainly associated with modulation systems. In this paper is shown how envelope and lnstantaneous phase can be applied in coding systems. In particular, the envelope of t he residual provides informatton ahnut pitch ilnd energy of the signal and can be user to properly codify it. A parametric version of the envelope is taken from the residual of a s ignal and this informat ion ls used ln two different coders: an APC corleranda stochastlcally excited coder. In APC coder the residual envelope is used to quantize the prediction error providing step size and dynamlc bU assignment information. In stochastically excitec coders, the input to the synthesls filter is composecl by the product of the parametric envelope of the residual multiplied by an instantaneous phase taken from a codebook of random phases .
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Mengzi Wang, Yong Hu, Zhihan Zhang et al. · Journal of seismic exploration · 2026
Traditional full waveform inversion objective functions typically rely on discrepancies between waveforms, making full waveform inversion highly dependent on the initial model and the low-frequency components in the seismic data. The instantaneous phase of the seismic signal reflects the kinematic information of seismic waves and has a more linear relationship with the subsurface velocity structure, aiding in the retrieval of low-wavenumber components of velocity models. Conversely, waveform information is instrumental in achieving high-resolution inversion results while maintaining algorithmic stability. In addition, automatic differentiation provides an efficient and accurate mechanism for computing gradients by systematically applying the chain rule across the computational graph, yielding reliable derivative information for optimization. To balance the contributions of waveform and phase information in velocity inversion, within the framework of automatic differentiation, we integrate instantaneous phase and waveform information to propose an automatic differentiation-based weighted instantaneous phase inversion method. Numerical tests using the Marmousi model and the Overthrust model demonstrate that the proposed method achieves more accurate velocity inversion results.
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F. Cakrak, Patrick J. Loughlin · 2002
We develop a new multi-window time-frequency method for estimating the instantaneous frequency (IF) of constant amplitude polynomial FM signals in the presence of noise. The method is computationally simple, asymptotically unbiased for noise-free signals, and provides a signal to noise ratio (SNR) threshold improvement of about 3 dB over other estimators, including the cross-polynomial Wigner time-frequency method (X-PWVD), for quadratic and cubic FM signals.
Cited by 7
Satoru Yoneyama, Michinori Mizuhara, Hisao Kikuta et al. · Key engineering materials · 2006
This paper demonstrates instantaneous phase-stepping and subsequent phase analysis methods for interferometry and two-dimensional photoelasticity. The camera that has a pixelated form-birefringent micro-retarder array acquires phase-stepped fringes in a single camera frame. Then, the distributions of Stokes parameters that represent the state of polarization are calculated from a single image. In the case of the polarization interferometer, the phase difference of the two orthogonally polarized light beam can be easily determined from the Stokes parameters. On the other hand, the phase distributions of the isochromatics and the isoclinics are obtained in the case of the photoelasticity. It is emphasized that this method is applicable to real-time inspection of optical elements as well as the study of the mechanics of time-dependent materials because multiple exposures are unnecessary for sufficient data acquisition in the completion of data analysis.
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2022
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B.V. Seleznev, A.A. Blyablin, А. В. Гаврилов et al. · Diamond and Related Materials · 1995
Cited by 3
J.C. Montaño, Patricio Salmerón Revuelta · IEEE Transactions on Power Delivery · 1998
Fundamental results of the generalized instantaneous power theory have been applied for power factor correction in three-phase systems. Instantaneous and full compensation were considered to set the differences between compensation in general conditions (periodic or nonperiodic waveforms) and compensation in steady states (periodic waveforms). An active power filter is simulated as reactive power compensator to confirm the theory.
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