Fundamental study of laser generation of narrowband Lamb waves using superimposed line sources technique

Wu, Tai-Hsien; Ume, I. Charles

doi:10.1016/j.ndteint.2011.01.006

Cited by 15 publications

(12 citation statements)

References 39 publications

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“…Owing to its intrinsic noncontact nature, the automated inspection can be more convenient and more pragmatic [4]. Moreover, this technique provides an advantage that various shapes of surface waves can be easily produced by modulating the shape of laser beam that illuminates the surface of the specimen [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Seo¹,

Kim²,

Choi³

et al. 2012

Journal of the Korean Society for Nondestructive Testing

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Using a single-line pulsed laser beam is well known as a useful noncontact method to generate a directional surface acoustic wave. In this method, different laser beam energy profiles produce different waveforms and frequency characteristics. In this paper, we considered two typical kinds of laser beam energy profiles, Gaussian and square-like, to find out a difference in the frequency characteristics. To achieve this, mathematical models were proposed first for Gaussian laser beam profile and square-like respectively, both of which depended on the laser beam width. To verify the theoretical models, experimental setups with a cylindrical lens and a line-slit mask were respectively designed to produce a line laser beam with Gaussian spatial energy profile and square-like. The frequency responses of the theoretical models showed good agreement with experimental results in terms of the existence of harmonic frequency components and the shift of the first peak frequencies to low.

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Section: Introductionmentioning

confidence: 99%

“…However, by using a line laser beam, the directivity of the surface wave can be improved [5]. A line laser beam can be produced by several methods such as the use of a cylindrical lens and a line-slit mask [2,4,7]. In these methods, the spatial laser energy profile can be largely classified into two kinds: Gaussian and non-Gaussian.…”

Section: Introductionmentioning

confidence: 99%

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Seo¹,

Kim²,

Choi³

et al. 2012

Journal of the Korean Society for Nondestructive Testing

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“…The frequency-wavenumber domain analysis has been shown to be very effective in terms of characterization of guided waves [7]. Guided waves, such as Lamb waves, will appear as dispersive curves in frequency-wavenumber representation [8]. Figure 6(b) is the resultant frequency-wavenumber representation of the acquired B-scan signals.…”

Section: Representation Of Acquired Signals In Moviementioning

confidence: 99%

Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

Lei¹,

Gong²,

Ume³

2014

AIP Conference Proceedings

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“…In particular, laser-generated SAWs are beneficial as a noncontact method since they are free from the contact issues such as surface conditions, acoustic impedance mismatch, and angle of incidence [2][3][4][5]. Moreover, by modulating the shape of the laser beam source, laser-generated SAWs can be generated in various waveforms [6,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of laser beam profiles on the frequency bandwidth of laser-generated surface acoustic waves

Seo

Choi

Jhang

2014

2014 IEEE Far East Forum on Nondestructive Evaluation/Testing

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The frequency characteristics of laser-generated surface acoustic waves (SAWs) were investigated depending on laser beam profiles. The laser-generated SAWs were analytically and experimentally compared when using the single-line laser beams of Gaussian and square-like energy profiles. Also, the line-arrayed laser beam in the square-like energy distribution was introduced to generate the SAW that had a narrow frequency bandwidth. The results from both the experiments and the simulations showed the similar distinction of the frequency characteristics in between using Gaussian and square-like laser energy profiles. The SAW by the Gaussian laser beam showed only single peak in the frequency spectrum, whereas the odd harmonic frequency components appeared in the case of using the square-like laser beams. Moreover, the SAW by the line-arrayed laser beam had narrower frequency bandwidth than the SAW by the single-line laser beam. These results were in good agreement with the theoretical predictions, which supports that laser-generated SAWs have the advantage of frequency modulation by modifying the spatial energy profile of a laser beam.

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Fundamental study of laser generation of narrowband Lamb waves using superimposed line sources technique

Cited by 15 publications

References 39 publications

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

Influence of laser beam profiles on the frequency bandwidth of laser-generated surface acoustic waves

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