Spatial phase-shift dual-beam speckle interferometry

Gao, Xinya; Yang, Lianxiang; Wang, Yonghong; Zhang, Boyang; Dan, Xizuo; Li, Junrui; Wu, Sijin

doi:10.1364/ao.57.000414

Cited by 9 publications

(8 citation statements)

References 23 publications

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“…However, simultaneous quantitative phase retrieval for two symmetric sensitivity vectors is still challenging, especially for in-plane strain measurements. To measure dynamic in-plane displacement, several attempts have been made based on spatial-carrier phase shifting [25], different wavelengths [27], polarization [24], different coherence lengths [28], and spatial multiplexing [20]. For in-plane strain measurements, two-step symmetric measurements and temporal phase shifting have been realized [18,21,22,26,29].…”

Section: Introductionmentioning

confidence: 99%

Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements

Dong¹,

Wang²,

Lü³

et al. 2019

Opt. Express

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A real-time, dual-sensitive shearography system using a single-wavelength laser was developed for simultaneous and dynamic in-plane and out-of-plane strain measurements. The shearography system is capable of measuring crack-tip deformation fields quantitatively. A spatial multiplexing technique based on Fourier transform is employed for simultaneous and dynamic multi-component phase retrieval. Two slit spatial filters and a common-path shearing interferometer are used to obtain an improved phase quality for crack-tip deformation measurements. Mode-I fracture experiments under three-point bending were conducted to validate the feasibility and the capability of this method.

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Section: Introductionmentioning

confidence: 99%

Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements

Dong¹,

Wang²,

Lü³

et al. 2019

Opt. Express

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“…The new configuration of the shearography instrument realises measurements of the in-and out-of-plane surface strain components during the impact using the double frame approach and a double imaging Mach-Zehnder interferometer 11,12 . The main criteria for the continuation of the development were derived by maximising the value of the expected results for the validation of numerical models -to measure both in-and out-of-plane surface strain components at impact speeds up to 200 m/s with a temporal resolution up to sub-μs over the field of view of 100×100 mm.…”

Section: Introductionmentioning

confidence: 99%

EXTREME shearography: high-speed shearography instrument for in-plane surface strain measurements during an impact event

Anisimov¹,

Groves

2019

Optical Measurement Systems for Industrial Inspection XI

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This work presents the design and the latest experimental results on the surface strain measurements during an impact event obtained with the EXTREME high-speed shearography instrument. The shearography technique is used in this project to provide a quantitative measurement of the surface strain development at the first moments of the impact event (μs time scale) which may reveal the initiation of the failure mechanisms in composite materials. Experimentally measured surface strain components over the field of view will be used as input and validation data for new numerical and analytical models of the impact response of composites. The new configuration of the shearography instrument realises measurements of the in-and out-of-plane surface strain components to improve coupling with the numerical models. Two viewing directions (shearing interferometers) with a double-frame approach are used to capture the interferograms during the impact. The interferometers realise a double-imaging Mach-Zehnder scheme for the spatial phase-shifting with independent control of the shearing amount and the carrier frequency. The set of technical parameters of the developed shearography instrument makes it one of the most extreme applications of shearography for material characterisation. The framework for this work is the "EXTREME Dynamic Loading -Pushing the Boundaries of Aerospace Composite Material Structures" Horizon 2020 project.

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“…Sci. 2019, 9, 3882 2 of 10 (DSPI) [3,12]. The sensitivity of Moiré interferometry and DSPI is higher than that of DIC, and the set-up of DSPI is simpler than that of Moiré interferometry.…”

mentioning

confidence: 99%

“…Therefore, an interferometer, capable of measuring two in-plane displacements at the same time, is needed.By using two cameras and two orthogonal polarized dual-beam illumination sets, cross-interference between the two pairs of beams can be avoided, allowing the measurement of the two interferograms at the same time [2]. However, the effectiveness of this method depends on the surface not changing the polarization of the incident beams, which is not always the case [16].The spatial coherence of the laser can also be used to avoid cross-interference [12]. If the optical lengths are equal for each pair of beams, and the optical length difference between two pairs is longer than the coherent length, the two pairs of beams can illuminate the surface at the same time without cross-interference [17].…”

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confidence: 99%

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Measurement of In-Plane Displacement in Two Orthogonal Directions by Digital Speckle Pattern Interferometry

et al. 2019

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The measurement of in-plane displacement in two orthogonal directions is of considerable significance for modern industries. This paper reports on a spatial carrier phase-shift digital speckle pattern interferometry (DSPI) for the simultaneous measurement of in-plane displacement in two orthogonal directions. The object is illuminated from a single direction and observed from four symmetrical directions simultaneously. One pair of the four observation directions is sensitive to in-plane displacement in one direction, and the other pair is sensitive to in-plane displacement in the perpendicular direction, resulting in the displacement in two directions being measured independently. The polarization property of light is used to avoid cross-interference between the two pairs of beams. Spatial carrier frequencies are generated by aperture misalignment, and the displacement in two directions is modulated onto the same interferogram. With a spatial carrier phase-shift technique, the displacement can be separated in the frequency domain and the phase can be evaluated from a single interferogram in real time. The capability of DSPI is described by theoretical discussions and experiments. Appl. Sci. 2019, 9, 3882 2 of 10 (DSPI) [3,12]. The sensitivity of Moiré interferometry and DSPI is higher than that of DIC, and the set-up of DSPI is simpler than that of Moiré interferometry. Because of the high sensitivity and flexibility of DSPI, it has been well-accepted in experimental mechanics, displacement and displacement measurements, and strain measurements.In DSPI, in-plane displacement is measured by evaluating the phase difference of two recorded speckle interferograms under load. The surface under the test is illuminated from two symmetrical directions with a single direction of observation [13], or is observed from two symmetrical directions with a single direction of illumination [14]. The measurement of a surface displacement in two orthogonal directions is often required for the complete characterization of displacement. In traditional DSPI, in-plane displacement is measured in the single direction, depending on the illumination or observation direction. For example, if the surface is illuminated from two symmetrical directions, the measured displacement is in the vector direction, which is the subtraction of the vector directions of the two illumination beams. To measure the displacement in the perpendicular direction, the illumination beams must be rotated 90 degrees around the viewing axis. To make a system sensitive to displacement in two orthogonal directions, two pairs of beams, with different directions, should sequentially illuminate the surface. Thus, two separate interferograms can be recorded and combined vectorially [1,3,8,15]. To avoid cross-interference between the two pairs of beams, they should not illuminate the surface at the same time. Sequential measurement takes more time than usual, making the simultaneous measurement of transient or non-repeatable events, that require displacement in two orth...

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Spatial phase-shift dual-beam speckle interferometry

Cited by 9 publications

References 23 publications

Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements

Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements

EXTREME shearography: high-speed shearography instrument for in-plane surface strain measurements during an impact event

Measurement of In-Plane Displacement in Two Orthogonal Directions by Digital Speckle Pattern Interferometry

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