| Autor: |
Huber, R. D., Candy, J. V., Chambers, D. H. |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2000, Vol. 509 Issue 1, p859, 6p, 5 Diagrams |
| Abstrakt: |
In this paper we describe the results of controlled laser-based ultrasonic experiments for NDE applications, which are aimed at detecting and imaging a well-defined flaw in an aluminum component. A pulsed laser is used to generate ultrasonic signals which are then received by an interferometer so as to synthesize an array for displacement measurements. We demonstrate how these measurements can be coupled to an algorithm to detect, localize, and image the flaw. The technique, called matched-field imaging (MFI), evolves from research in ocean acoustics. It is shown that MFI is a generalization of the well-known (ad hoc) synthetic aperture focusing technique (SAFT). In terms of investigating components for flaws during NDE, the matched-field approach also offers a reasonable technique of imaging the component itself. Because of the low signal-to-noise ratio inherent in laser-based ultrasound, preprocessing is required and accomplished by a correlation canceling technique designed to separate a correlated (reference) from uncorrelated (flaw) measurements. The canceler then provides the optimal separation removing the wash, primary arrivals, etc. and extracting just information about the flaw. We compare the performance of the MFI and SAFT processors on both simulated and experimental data. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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