The calculation of acoustic fields in solids for transient normal surface force sources of arbitrary geometry and apodization

McNab, A.; Cochran, A.; Campbell, Michael A.

doi:10.1121/1.399442

Cited by 23 publications

(8 citation statements)

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“…If noise in the original waveforms is uniform then this apodization maximizes the signal to noise ratio (SNR) at each point in image. As a result, the intensity of the image, I(r), is given by [9], [10]:…”

Section: The Full Matrix Capture and The Total Focusing Methodsmentioning

confidence: 99%

Adapting the full matrix capture and the total focusing method to laser ultrasonics for remote non destructive testing

Stratoudaki

Clark

Wilcox

2017

2017 IEEE International Ultrasonics Symposium (IUS)

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Abstract-Laser Induced Phased Arrays (LIPAs) use post processing to focus and steer the laser generated and detected ultrasonic beam, synthesizing a phased array. The technique is broadband, non-contact, and couplant free, making LIPAs suitable for large stand-off distances, inspection of components of complex geometries and hazardous environments. This paper presents LIPAs synthesized by capturing the Full Matrix (FMC), at the nondestructive, thermoelastic regime. The Total Focusing Method (TFM) is used as the imaging algorithm, where the captured signals are summed with the appropriate time delay, in order to synthesize a focus at every point in the imaging area. The FMC and the TFM, are adapted to the needs of LIPAs in order to enable fast imaging and make more efficient use of the information in the data. Experimental results are presented from nondestructive, laser ultrasonic inspection of an aluminum sample with side drilled holes at depths varying between 10 and 20 mm from the surface.

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Section: The Full Matrix Capture and The Total Focusing Methodsmentioning

confidence: 99%

Adapting the full matrix capture and the total focusing method to laser ultrasonics for remote non destructive testing

Stratoudaki

Clark

Wilcox

2017

2017 IEEE International Ultrasonics Symposium (IUS)

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“…While some condensed volumes on the matter in general have been compiled [12,13,14,15,16,17,18], most of the relevant research is mainly scattered in time and throughout literature. One can find, for example, expositions on pressure-induced [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35] as well as thermal-expansion-induced [26,27,28,29,30,31,32,33,35,36,37,38,39,40,41,42,43,44] ultrasound propagation in a half-space [21,22,23,24,25,26,27,...…”

Section: Introductionmentioning

confidence: 99%

Laser-induced ultrasonic waveform derivation and transition from a point to a homogeneous illumination of a plate

et al. 2017

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Ultrasound modeling, being an established practice, is used to study the fundamentals of light-matter interactions. Although much has been published on the matter, pressure and thermal expansion induction mechanisms in laser ultrasonics have rarely been combined, as they should, in a single ultrasonic source while the effects of its size variation have only been shown to a limited extent. In the paper, we unite these light-matter interaction mechanisms, with inclusion of lateral optical forces, into a single laser-stimulated source as it is observed in nature. With a laser pulse as a manipulable source, we simulate the multifaceted workings of light-matter interactions by exposing the distinct transients originating from different source localities as generated by different induction mechanisms. We also present a transition of simulated ultrasonic waveforms in the epicentral point on the surface of a solid plate opposite from the source while it is expanded from a point to a quasi-limitless extent for pressure and thermal expansion generation regimes. The model utilizes geometric probability theory together with Huygens' superposition principle and temporal convolutions to construct the desired waveforms out of individual Green's functions. We show how the ultrasound generation regimes stem out of a single source and how its size together with energy and momentum transfers during the light-matter interactions affect the induced ultrasonic transients.

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“…Above 60°, another maximum appears that is no Ionger centered on the steering angle, and is possibly associated with increased plate wave generation and leakage into the specimen. Previous work (3] has shown that the element directivities can be associated with elastic-wave sources having a Gaussian force profile, which are active on the surface of the specimen. The effective width of these sources is larger than the element itself, due partly to the Gaussian electric field on the bottom surface of the Iithium niobate, and partly to the high divergence ofwaves propagating within the plate from the top and bottom surfaces.…”

Section: Array Performancementioning

confidence: 99%

Ultrasonic Arrays for Flaw Characterization at High Temperature

McNab¹,

Hayward²,

Cochran³

et al. 1997

Review of Progress in Quantitative Nondestructive Evaluation

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The calculation of acoustic fields in solids for transient normal surface force sources of arbitrary geometry and apodization

Cited by 23 publications

References 0 publications

Adapting the full matrix capture and the total focusing method to laser ultrasonics for remote non destructive testing

Adapting the full matrix capture and the total focusing method to laser ultrasonics for remote non destructive testing

Laser-induced ultrasonic waveform derivation and transition from a point to a homogeneous illumination of a plate

Ultrasonic Arrays for Flaw Characterization at High Temperature

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