Non-destructive imaging, characterization or measurement of thin items using laser-generated lamb waves
US7798000B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 2006 |
| Grant date | Sep 21, 2010 |
| Priority date | — |
| Expiry date | Jul 15, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0427
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser-based ultrasonic technique for the inspection of thin plates and membranes employs an amplitude-modulated laser source to excite narrow bandwidth Lamb waves. The dominant feature in the acoustic spectrum is a sharp resonance peak that occurs at the minimum frequency of the first-order symmetric Lamb mode, where the group velocity of the Lamb wave goes to zero while the phase velocity remains finite. Experimental results with the laser source and receiver on epicenter demonstrate that the zero group velocity resonance generated with a low power modulated excitation source can be detected using an optical probe such as a Michelson interferometer coupled to a lock-in amplifier. This resonance peak is sensitive to the thickness and mechanical properties of plates and may be suitable, for example, for the measurement and mapping of nanoscale thickness variations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.