| Autor: |
G. Brassard, J.-L. Lesne, D. Hauden, O. Cassier, R. De Mol, Mathias Fink, B. Cretin, Daniel Royer |
| Rok vydání: |
1991 |
| Předmět: |
|
| DOI: |
10.1016/b978-0-7506-0389-8.50066-4 |
| Popis: |
In the field of laser-generated ultrasonic waves, we are concerned with the thermoelastic regime as it is non destructive. The drawback of this regime is the low intensity of ultrasound waves making optical detection difficult. Among practical methods to improve the acoustic efficiency of the ultrasonic waves generated by laser impact, we are testing two techniques: - the first one uses a moving thermoelastic source at velocities greater than the speed of ultrasonic waves in the material - the second one uses a set of elementary photoacoustic sources that are spatially and temporally dispersed on the material surface. With an appropriate mathematical model, we demonstrate the net gain in directivity. Experimental evidences are obtained with the moving acoustic source. Some conclusions are presented in view of the specifications needed in some industrial applications with a laser based ultrasonic system connected with an optical interferometric detection. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
