Beam distortion detection and deflectometry measurements of gigahertz surface acoustic waves

Higuet, J.; Valier‐Brasier, Tony; Dehoux, Thomas; Audoin, Bertrand

doi:10.1063/1.3660193

Cited by 24 publications

(12 citation statements)

References 26 publications

(32 reference statements)

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“…The laser ultrasonic experimental setup used to monitor the ZGV mode frequency is composed of (i) a pulsed Nd∶YAG laser (1064 nm, pulse duration close to 0.75 ns, repetition rate of 1 kHz) focused to a stretched ellipse (small diameter approximately 20 μm and large diameter approximately 500 μm) on the sample surface to generate the first symmetrical ZGV Lamb mode among others, and (ii) a CW laser (532 nm) focused to a circular spot (diameter approximately 20 μm) in the vicinity of the line source to detect the local resonance thanks to the beamdeflection technique [20,47]. Since the beam-deflection technique is sensitive to the radial gradient of the normal displacement (u z ), a small shift of about 40 μm has been used between generation and detection spots, for the detection of the ZGV mode.…”

Section: Fatigue Setup and Laser Ultrasonic Experimental Setupmentioning

confidence: 99%

Characterization of Progressive Fatigue Damage in Solid Plates by Laser Ultrasonic Monitoring of Zero-Group-Velocity Lamb Modes

et al. 2018

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We propose a method for nondestructive characterization of progressive fatigue damage in solid plates, using a zero-group-velocity (ZGV) Lamb mode generated and detected by lasers. Our experimental results depict a nonmonotonous change in the ZGV mode frequency with an increasing number of loading cycles, and more importantly its drastic decrease prior to the specimen failure. We report three experiments on three specimens made of aluminum, which fail after different numbers of loading cycles. Despite this difference, the three nonmonotonous variations of the ZGV mode frequency with an increasing number of loading cycles are superimposed when plotted as a function of the normalized fatigue lifetime. This feature stresses out the potential of the technique to locate fatigue damage, to predict the fatigue lifetime, and to qualitatively, and even quantitatively, assess the different stages of fatigue damage in micrometer-to potentially centimeters-thick solid plates.

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Section: Fatigue Setup and Laser Ultrasonic Experimental Setupmentioning

confidence: 99%

Characterization of Progressive Fatigue Damage in Solid Plates by Laser Ultrasonic Monitoring of Zero-Group-Velocity Lamb Modes

et al. 2018

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“…The GHz frequency content of the SAWs is imposed by the lateral size (≈ 1.5µm) of the focus pump spot on the free surface of the film. The xy in-plane derivative of the normal displacement of the surface film is detected through a deflectometry detection scheme [38][39][40][41]. Figure 5 shows a raw experimental transient reflectivity at the epicenter over the first 10 ns.…”

Section: Opto-acoustic Response Of a Supported Thin Filmmentioning

confidence: 99%

“…The calculated deflectometric signal, i.e. dynamics of the xy in-plane derivatives of the normal displacement of the surface film [38][39][40][41], are plotted in Fig. 9 as dotted red curves for the 14 pump-probe distances experimentally studied.…”

Section: Low Frequency Surface Acoustic Waves -Analysis Of the Saws Dmentioning

confidence: 99%

Picosecond time resolved opto-acoustic imaging with 48 MHz frequency resolution

Abbas¹,

Guillet²,

Rampnoux³

et al. 2014

Opt. Express

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A compact femtosecond dual-oscillator pump-probe setup with 48 MHz-repetition rate, relying on asynchronous optical sampling, is presented. The relative timing jitter between both lasers over the whole pump-probe delay range is of the order of or lower than 500 fs. We demonstrate that both a picosecond temporal resolution and a 48 MHz spectral resolution combined with the fast acquisition rate inherent to the asynchronous optical sampling allow performing broadband opto-acoustic imaging with a spectrum covering more than two decades from 300 MHz to 150 GHz. As an illustration, the opto-acoustic response of a supported thin film is investigated, revealing high frequency acoustic echoes close to the epicenter as well as low GHz surface acoustic waves propagating up to 40μm away from the epicenter. Semi-analytical calculations have been carried out and perfectly reproduce the dispersion of the surface acoustic waves experimentally observed.

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“…[41][42][43][44][45] Although the case of the thermoelastic generation of interface waves at the perfect interface between a perfect fluid half-space and an isotropic solid halfspace has been largely studied, [46][47][48] investigations of two isotropic solid half-spaces in contact remain scarce. 40 In this section, we propose an even more general modeling of the thermoelastic generation at the interface formed by two anisotropic viscoelastic half-spaces.…”

Section: Modeling Of Thermoelastic Processes At a Generalized Impmentioning

confidence: 99%

Scaled behavior of interface waves at an imperfect solid-solid interface

Valier‐Brasier

Dehoux

Audoin

2012

Journal of Applied Physics

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Laser ultrasonic techniques allow the remote analysis of adhesion mechanisms at imperfect interfaces up to GHz frequencies. However, the sensitivity of interface waves to the properties of the contact is not very well known. In the present work, the mechanical boundary conditions are described considering that the contacting solid half-spaces are connected by tangential and normal springs. Such a modeling implies a discontinuity of the displacement field across the interface. To identify the relative amplitudes of the different types of interface waves-skimming, leaky Rayleigh (LR) and Stoneley (St) waves-a semi-analytical time domain model describing the thermoelastic laser generation is derived. The results illustrate the influence of the boundary conditions on the attenuation of the LR wave and on the existence of the St wave. In addition, a single compact and elegant dispersion equation is presented to investigate the behaviour of the interface waves propagating along a generalized imperfect boundary. Such analysis reveals the existence of a cutoff frequency f c close to which the St wave behaves like a skimming transverse wave. A scaled analysis demonstrates that two master curves suffice to describe the dispersion of LR and St waves and that f c is inversely proportional to the tangential interfacial spring constant.

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Beam distortion detection and deflectometry measurements of gigahertz surface acoustic waves

Cited by 24 publications

References 26 publications

Characterization of Progressive Fatigue Damage in Solid Plates by Laser Ultrasonic Monitoring of Zero-Group-Velocity Lamb Modes

Characterization of Progressive Fatigue Damage in Solid Plates by Laser Ultrasonic Monitoring of Zero-Group-Velocity Lamb Modes

Picosecond time resolved opto-acoustic imaging with 48 MHz frequency resolution

Scaled behavior of interface waves at an imperfect solid-solid interface

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