A method for using noncontact laser-based techniques for the generation and detection of ultrasound in solids is described. The generation technique uses a high power laser modulated at 1-10 MHz to thermoelastically generate a short tone burst of ultrasound in the solid. By arranging to have several laser spots impinge on the material, an array of ultrasonic sources can be generated, and the ultrasonic beam synthesized from the array can be focused and steered over a range of angles. The suitability of using laser-generated thermoelastic sources as array elements is assessed. The detection technique makes use of a Fabry-Perot interferometer to measure surface displacement caused by echoes reflected from flaws within the material. The sensitivity of the detector and the degradation that results when it is scanned over the surface are evaluated.
|Original language||English (US)|
|Title of host publication||Review of Progress in Quantitative Nondestructive Evaluation|
|Number of pages||10|
|State||Published - 1988|
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