Strain Analysis for Moiré Interferometry Using the Two-dimensional Continuous Wavelet Transform

Keisuke, Kadooka; Kunoo, Kazuo; Uba, Nobuhide; Ono, Ken; Nagayasu, T.

doi:10.1177/0014485103043001088

Cited by 2 publications

(2 citation statements)

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“…Open fringe patterns are comparatively easier to demodulate due to the presence of carrier frequency. The techniques based on Fourier transform [1], windowed Fourier transform [2], and wavelet transform [3,4] are some of the commonly used techniques to demodulate the open fringe patterns. On the other hand, in the case of a closed fringe pattern, phase sign ambiguity exists due to the absence of a carrier frequency.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous estimation of unwrapped phase and phase derivative from a closed fringe pattern

Kulkarni

Rastogi

2016

Optics and Lasers in Engineering

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We propose a new approach for the direct estimation of the unwrapped phase from a single closed fringe pattern. The fringe analysis is performed along a given row/column at a time by approximating the phase with a weighted linear combination of linearly independent basis functions. Gaussian radial basis functions with equally distributed centers and a fixed variance are considered for the phase approximation. A state space model is defined with the weights of the basis functions as the state vector elements. Extended Kalman filter is effectively utilized for the accurate state estimation. A fringe density estimation based criteria is established to select whether the phase estimation is performed in a row by row or column by column manner. In the seed row/column decided based on this criteria, the optimal basis dimension is computed. The proposed method effectively renders itself in the simultaneous estimation of the phase and the phase derivative. The proposed phase modeling approach also allows to successfully demodulate the low density fringe patterns. Simulation and experimental results validate the practical applicability of the proposed method.

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Section: Introductionmentioning

confidence: 99%

Simultaneous estimation of unwrapped phase and phase derivative from a closed fringe pattern

Kulkarni

Rastogi

2016

Optics and Lasers in Engineering

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“…The CWT also gains applications in analyzing moire ´fringe patterns. [32][33][34] However, all these techniques extract the phase in the spatial domain.…”

Section: Introductionmentioning

confidence: 99%

Instantaneous velocity displacement and contour measurement by use of shadow moiré and temporal wavelet analysis

Tay

Quan

et al. 2004

Appl. Opt.

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A temporal wavelet analysis method is proposed for velocity, displacement, and three-dimensional surface-profile measurement of a continuously deforming object by use of the shadow moiré technique. A grating is placed close to a deforming object, and its shadow is observed through the grating. The moiré fringe patterns, generated by the interference of the grating lines and their shadows, are captured by a high-speed CCD camera with a telecentric gauging lens. Instantaneous frequency of gray-value variation is evaluated point by point with the continuous wavelet transform. From the instantaneous frequency of each point on the object, the velocity, displacement, and high-quality surface profile at different instants can be retrieved. In this application, two specimens are tested to demonstrate the validity of the proposed method: One is a small coin with a rigid body motion, and the other is a simply supported beam subjected to a central point load. The results are compared with those obtained from temporal Fourier-transform and mechanical stylus methods.

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Strain Analysis for Moiré Interferometry Using the Two-dimensional Continuous Wavelet Transform

Cited by 2 publications

References 0 publications

Simultaneous estimation of unwrapped phase and phase derivative from a closed fringe pattern

Simultaneous estimation of unwrapped phase and phase derivative from a closed fringe pattern

Instantaneous velocity displacement and contour measurement by use of shadow moiré and temporal wavelet analysis

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