Phase estimation via riesz transform in laser speckle interferometry for large-area damage imaging

Fong, Rey-Yie; Fang, Yuan

doi:10.1016/j.ndteint.2022.102711

Cited by 10 publications

(3 citation statements)

References 53 publications

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“…2. Limited resolution: the resolution of LSI technology is limited by the size and propagation path of the laser spot, which is relatively low compared to other high-resolution imaging techniques, such as electron microscopy [51].…”

Section: Experimental Discussion Of Improved Angular Spectrum Methods...mentioning

confidence: 99%

Investigation of an Improved Angular Spectrum Method Based on Holography

Wu,

Yang,

Wang

et al. 2023

Photonics

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Digital holography (DH) is a novel, real-time, non-destructive, and quantitative phase-contrast imaging method that is particularly suitable for label-free live biological cell imaging and real-time dynamic monitoring. It is currently a research hotspot in the interdisciplinary field of optics and biomedical sciences, both domestically and internationally. This article proposes an improved angle spectrum algorithm based on holographic technology, which reconstructs a cellular hologram based on phase information. Optical images and chromosome cell images, reconstructed using holographic technology at different diffraction distances under the improved angle spectrum algorithm, were analyzed and compared. The optimal diffraction distance for reconstructing chromosome cell images was selected, and chromosome cell images reproduced using traditional angle spectrum algorithms, angle spectrum algorithms combined with GS, and improved angle spectrum algorithms were compared. Comparative experiments with the different models show that the proposed algorithm is superior to traditional angle spectrum algorithms in reconstructing cell images based on phase information. Furthermore, experiments have shown that images reconstructed using the improved algorithm can resolve high signal-to-noise ratio information. This algorithmic improvement provides new applications for cellular detection in clinical diagnostics and is more suitable for cell phase reconstruction in practical applications.

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Section: Experimental Discussion Of Improved Angular Spectrum Methods...mentioning

confidence: 99%

Investigation of an Improved Angular Spectrum Method Based on Holography

Wu,

Yang,

Wang

et al. 2023

Photonics

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“…Optical laser-based sensing methods, such as interferometric techniques like Moire´interferometry, holographic interferometry, speckle pattern interferometry, and sherography, enable remote full-field measurement of surface deformations and deformation gradients. 22 However, they generally require a coherent light source and very carefully controlled laboratory conditions, which limits their practicality for NDI/ SHM.…”

Section: Introductionmentioning

confidence: 99%

Subsurface impact damage imaging for composite structures using 3D digital image correlation

Abbott

Fang

2023

Structural Health Monitoring

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An integrated system is proposed to visualize subsurface barely visible impact damage (BVID) in composite structures using three-dimensional (3D) digital image correlation (3D DIC). This system uses a pair of digital cameras to record video frames in the field-of-view (FOV) of the structure’s surface, capturing the wavefield generated via chirp excitation in the near-ultrasonic frequency range. Significant pitfalls of previous efforts of damage imaging using two-dimensional DIC have been largely mitigated. First, 3D DIC enables capturing out-of-plane displacements, which are much larger in amplitude versus in-plane displacements that a single camera would be limited to sensing, thus increasing the signal-to-noise ratio. This enhancement in turn increases the sensitivity of the stereo-camera system. Second, a total wave energy (TWE) damage imaging condition is proposed to visualize the local damage region. The monogenic signal obtained via Reisz transform (RT) is employed to compute the instantaneous amplitude, with which the local wave energy can be calculated spatially over time. Since a high displacement amplitude and thus high wave energy will occur in the damage region due to the local resonance, the proposed TWE imaging condition can relax the Nyquist sampling requirement, unlike guided-wave-based structural health monitoring techniques which require fully reconstructing the wavefield and wave modes through sampling that satisfies the Nyquist criterion. As such, a much lower camera frame rate is adequate for the proposed system. Consequently, the maximum spatial resolution of the camera for a given FOV can be achieved at the expense of a reduced frame rate. With the maximized pixel resolution and reduced frame rate for employing the TWE imaging condition, composite structures can be inspected or monitored with a larger FOV. As a result, there is no longer any need to apply signal enhancement techniques, such as sample interleaving, image stitching, or averaging, to increase the effective performance of the camera. Rather than needing thousands of repeated videos for minimizing the incoherent noise, only a single stereo-video with a few seconds of sampling duration is necessary for damage imaging. The use of a powerful piezo-shaker also increases the wave signal amplitude and further enhances sensitivity without permanent adhesion. To demonstrate this stereo-camera concept with the TWE imaging condition, the system was used to image damage in two carbon fiber reinforced polymer composite honeycomb panels, which had been subjected to low-velocity impacts (2 J). For each panel, two excitation configurations were used to verify the robustness of the system. Initial damage maps produced for a 100 × 100-mm FOV using a three-second stereo-video show accurate damage imaging ability that is independent of excitation location and comparable to benchmark damage images computed from laser Doppler vibrometer data and those gathered from ultrasonic and X-ray computerized tomography scans. This efficient and reliable integrated system demonstrated high potential for in-time damage inspection on composite aircraft and other critical structures.

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“…Optical methods offer a solution to these limitations since digital cameras can instantaneously image a surface with an array of sensors (pixels). Optical laser-based sensing methods such as interferometric techniques like Moire' interferometry, holographic interferometry, speckle pattern interferometry, and sherography enable remote full-field measurement of surface deformations and deformation gradients [9]. However, they generally require a coherent light source and very carefully controlled laboratory conditions, which limits their practicality for NDI/SHM.…”

Section: Introductionmentioning

confidence: 99%

Impact damage imaging for composite structures using guided wave techniques with 3D digital image correlation

Abbott

Yuan

2023

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2023

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This paper presents an integrated system capable of damage imaging of barely visible impact damage (BVID) in composite structures. This system applies guided-wave-based structural health monitoring using 3D digital image correlation, or GWSHM-3D DIC to produce a map of subsurface damage using a short video from a stereo pair of synchronized digital cameras. The proposed system overcomes many limitations of previous efforts of GWSHM that used 2D digital image correlation (DIC). First, 3D DIC can capture the higher-amplitude out-of-plane displacements associated with the antisymmetric wave mode, lowering the spatial resolution requirements of the cameras. Second, a total wave energy (TWE) imaging condition is employed that uses the monogenic signal via a Reisz transform to obtain the local instantaneous amplitude as a contribution to wave energy. This condition can highlight local resonance in the damage region without the need for high frame rates to fully reconstruct the wavefield. With significantly lowered spatial and temporal resolution requirements of the cameras, high-stiffness materials like composites can be inspected or monitored with a larger field-ofview (FOV). Additionally, signal enhancement techniques intended to increase the effective resolution of the camera are no longer necessary, which reduces the data acquisition time from many hours to a few seconds. To demonstrate this integrated dual-camera concept with the TWE imaging condition, the system was used to image damage in a CFRP composite sandwich panel that had been subjected to a low-velocity impact. Initial damage maps produced for a 100-mm ´ 100-mm FOV using a three-second video pair show precise damage imaging ability that is comparable to benchmark ultrasonic and x-ray scans. This efficient and reliable integrated system demonstrated high potential for in-time damage inspection on composite aircraft and other critical structures.

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Phase estimation via riesz transform in laser speckle interferometry for large-area damage imaging

Cited by 10 publications

References 53 publications

Investigation of an Improved Angular Spectrum Method Based on Holography

Investigation of an Improved Angular Spectrum Method Based on Holography

Subsurface impact damage imaging for composite structures using 3D digital image correlation

Impact damage imaging for composite structures using guided wave techniques with 3D digital image correlation

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