Hidden damage visualization using laser speckle photometry

Welzen, J. van; Fang, Yuan; Fong, Rey-Yie

doi:10.1016/j.ndteint.2022.102700

Cited by 8 publications

(4 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The root mean square error (RMSE) can be used to evaluate the error between the unwrapped and true phases 23 , 24 . The smaller the value, the smaller the error, and the closer the unwrapped phase is to the true value ERMS=1normaln∑i=1n(φi−φfalse)2.…”

Section: Algorithm Simulation and Experimental Resultsmentioning

confidence: 99%

Discrete cosine transformation unwrapping algorithm based on phase gradient smoothing correction

et al. 2023

View full text Add to dashboard Cite

At present, in the shear speckle interference technique for vehicle tire defect detection, the key is to accurately reflect the real phase of object motion when there are interference factors. Thus, this study proposes a discrete cosine transformation (DCT) unwrapping algorithm based on phase gradient smoothing correction, and analyzes the feasibility of the proposed method through several experiments and numerical simulation calculations. The proposed method replaces abnormal phase gradients caused by noise with calculated weighted moving average phase gradients, bringing phases closer to real values. Finally, the DCT unwrapping method is used to obtain the final solution of phase. A phase recovered using the proposed method is closer to the real value than that recovered using the traditional DCT unwrapping algorithm. Compared to the traditional DCT unwrapping algorithm, the root mean square error accuracy of the proposed method is improved by 10 to 100 times. And after many experiments to record the average running speed, it can be obtained that the time-consumption of the two algorithms only differs by ∼0.1 to 0.3 s.

show abstract

Section: Algorithm Simulation and Experimental Resultsmentioning

confidence: 99%

Discrete cosine transformation unwrapping algorithm based on phase gradient smoothing correction

et al. 2023

View full text Add to dashboard Cite

show abstract

“…The less practical electronic speckle interferometry is the DSPI technique, where an interference pattern is formed on a digital image sensor using the superposition of a reference beam and reflected beam off the illuminated sample. However, DSPI is known to only perform well in a vibration isolated laboratory environment as it is susceptible to vibrations from the surroundings [2]. The more practical form of electronic speckle interferometry technique is the digital speckle shearing pattern interferometry, also known as DSSPI or shearography.…”

Section: Introductionmentioning

confidence: 99%

Wave-based acoustic shearography for defect imaging

Tham

Chen

Tan

et al. 2023

Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XVII

View full text Add to dashboard Cite

Acoustic shearography technique is a wave-based shearography method. In acoustic shearography, acoustic or ultrasonic waves are used to provide stress loading in the testing materials. Due to the deep penetration of acoustic waves and the flexibility of wave focusing control, acoustic shearography technique can detect deep subsurface defects in solid materials at the optical imaging speed. In this paper, the working principles, and the system setup of the acoustic shearography system are to be presented. Various acoustic excitation methods including acoustic excitation with dispersive acoustic transducers, directional and focusing acoustic wave transducers and pulsed laser beams are discussed. The applications of acoustic shearography for imaging of defects in thick metal structures are demonstrated. The acoustic shearography technique provides a feasible and practical solution for fast NDT of thick and large area structures.

show abstract

“…Intensity-based dynamic speckle method (IDSM) is a reliable tool for evaluating speed of processes ongoing in objects of biological or industrial origin [1][2][3][4] . Pointwise implementation of the method by using a 2D optical sensor gives spatiotemporal activity distribution extracted from a set of correlated in time speckle patterns formed on an object illuminated with coherent light 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Intensity-based dynamic speckle method for analysis of variable-rate dynamic events

Stoykova¹,

Nedelchev²,

Blagoeva³

et al. 2023

Optical Measurement Systems for Industrial Inspection XIII

View full text Add to dashboard Cite

We study efficiency of intensity-based dynamic speckle method for characterization of dynamic events which occur at variable rate in time within the temporal averaging interval. We checked the ability of the method to describe the speed of evolution by i) numerical simulation at variable speed, ii) processing of speckle patterns obtained from phase distributions fed to a SLM at controllable change of the temporal correlation radius of speckle intensity fluctuations and iii) conducting experiments with a polymer solution drying by using a hot-stage. The numerical and SLM simulation experiments allowed for modification of the used estimates in order to obtain relevant information.

show abstract

Hidden damage visualization using laser speckle photometry

Cited by 8 publications

References 52 publications

Discrete cosine transformation unwrapping algorithm based on phase gradient smoothing correction

Discrete cosine transformation unwrapping algorithm based on phase gradient smoothing correction

Wave-based acoustic shearography for defect imaging

Intensity-based dynamic speckle method for analysis of variable-rate dynamic events

Contact Info

Product

Resources

About