Design of a remote and integrated Sagnac interferometer that can generate narrowband guided wave through the use of laser and effective optics to detect defects occurred in plates

Ng, Kim Ming; Tse, Peter W.

doi:10.1016/j.optlastec.2019.105923

Cited by 7 publications

(12 citation statements)

References 15 publications

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“…Since the line spacing of an LAP governs the wavelength of the generated ultrasonic waves, by adjusting the LAP’s line spacing, ultrasonic waves of the desired frequency can be generated. To generate narrowband guided waves, the authors used a newly designed optical system called the integrated Sagnac interferometer-based optical system (SIOS) [ 36 ].…”

Section: Development Of Experimental Dictionarymentioning

confidence: 99%

“…An utterly non-contact laser-based inspection system was used for railhead defect detection and to design the experimental dictionary. The laser-generated ultrasonic waves were made narrowband with the help of the authors’ [ 36 ] newly designed optical system called the Sagnac interferometer-based optical system (SIOS), which produces the irradiation of a pulsed laser as a line array pattern (LAP) by using several optical lenses.…”

Section: Introductionmentioning

confidence: 99%

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Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Ghafoor

Tse

Rostami

et al. 2021

Sensors

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Laser ultrasonic technology can provide a non-contact, reliable and efficient inspection of train rails. However, the laser-generated signals measured at the railhead are usually contaminated with a high level of noise and unwanted wave components that complicate the identification of defect echoes in the signal. This study explores the possibility of combining laser ultrasonic technology (LUT) and an enhanced matching pursuit (MP) to achieve a fully non-contact inspection of the rail track. A completely non-contact laser-based inspection system was used to generate and sense Rayleigh waves to detect artificial surface horizontal, surface edge, subsurface horizontal and subsurface vertical defects created at railheads of different dimensions. MP was enhanced by developing two novel dictionaries, which include a finite element method (FEM) simulation dictionary and an experimental dictionary. The enhanced MP was used to analyze the experimentally obtained laser-generated Rayleigh wave signals. The results show that the enhanced MP is highly effective in detecting defects by suppressing noise, and, further, it could also overcome the deficiency in the low repeatability of the laser-generated signals. The comparative analysis of MP with both the FEM simulation and experimental dictionaries shows that the enhanced MP with the FEM simulation dictionary is highly efficient in both noise removal and defect detection from the experimental signals captured by a laser-generated ultrasonic inspection system. The major novelty contributed by this research work is the enhanced MP method with the developments of, first, an FEM simulation dictionary and, second, an experimental dictionary that is especially suited for Rayleigh wave signals. Third, the enhanced MP dictionaries are created to process the Rayleigh wave signals generated by laser excitation and received using a 3D laser scanner. Fourth, we introduce a pioneer application of such laser-generated Rayleigh waves for inspecting surface and subsurface detects occurring in train rails.

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Section: Development Of Experimental Dictionarymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Ghafoor

Tse

Rostami

et al. 2021

Sensors

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“…Therefore, the frequency of the ultrasonic waves can be controlled by adjusting the element width of the laser pattern. In the present study, the Integrated Sagnac Interferometer-based Optical System (SIOS) optical system [ 31 ] was used to generate a line-array pattern. The governing equation of the line-array pattern is expressed as:

where

is the absorptivity of the specimen,

is the spatial distribution of the laser beam, and

is the interference term which governs the element width of the pattern,

is the element width, and

is the temporal profile of the laser pulse.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…An Nd: YAG laser (SLIII-EX, Continuum Electro-Optics, Inc. Milpitas, CA, USA) with a wavelength of 532 nm was used as the laser source. The integrated Sagnac interferometer optical system [ 31 , 38 , 39 ] was used to spatially modulate the laser beam to generate a narrowband guided wave at the desired frequency range in the specimen. A PZT was attached at one end of the steel strand to act as the receiver.…”

Section: Experiments and Analysis On Three Sensorsmentioning

confidence: 99%

“…From [ 31 ], the wavelength of the generated guided wave is equal to the element width of the laser pattern. The frequency of the laser-generated guided is determined by the following equation:

where λ is the wavelength of the generated wave, ∆s is the element width, f is the frequency of the desired wave mode, and C p is the phase velocity of the desired wave at f .…”

Section: Experiments and Analysis On Three Sensorsmentioning

confidence: 99%

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Experimental Investigation on Choosing a Proper Sensor System for Guided Waves to Check the Integrity of Seven-Wire Steel Strands

Hou

Rostami

et al. 2020

Sensors

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Multiple wire twisted steel strands are commonly used to hoist elevators, concrete structures, etc. Due to frequent and long-time usage, the steel strands are subjected to corrosion, overloads, and aging, making strands may fail unexpectedly. Hence, the health monitoring of steel strands becomes more important to avoid the sudden collapse of hoisting structures. Guided waves (GW) inspection methods have become favorable in recent years due to its long-distance transmission and stability of evaluation in the area of structural health monitoring (SHM) and Non-Destructive Testing (NDT). Many researchers have reported different GW methods to detect different types of defects that occurred in steel strands. However, researchers rarely carry out comparative studies to investigate the effectiveness of each method or system in monitoring the health state of steel strands. This article reports some vital observations revealed from conducting experiments by using contact and noncontact methods, which include three different popular types of GW sensors and methods during their applications in surface-type defect detection. The proper selection of sensors systems has been identified through the present study. The result of the present study is believed to be useful guidance for selecting appropriate GW methods and sensor systems to monitor the integrity of the steel strand and thereby ensure the safety of the hoisted structures.

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Non-contact detection of railhead defects and their classification by using convolutional neural network

Ghafoor

Tse

Munir

et al. 2022

Optik

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Design of a remote and integrated Sagnac interferometer that can generate narrowband guided wave through the use of laser and effective optics to detect defects occurred in plates

Cited by 7 publications

References 15 publications

Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Experimental Investigation on Choosing a Proper Sensor System for Guided Waves to Check the Integrity of Seven-Wire Steel Strands

Non-contact detection of railhead defects and their classification by using convolutional neural network

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