Reference : Laser Ultrasound for NDT: investigation of the generation beam shape
Scientific congresses and symposiums : Poster
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/2268/207254
Laser Ultrasound for NDT: investigation of the generation beam shape
English
Languy, Fabian mailto [Université de Liège > > CSL (Centre Spatial de Liège) >]
Perrard, Aurélie mailto []
Vandenrijt, Jean-François mailto [Université de Liège > > CSL (Centre Spatial de Liège) >]
Georges, Marc mailto [Université de Liège > > CSL (Centre Spatial de Liège) >]
Jul-2016
No
No
International
5th International Symposium on Laser-Ultrasonics and Advanced Sensing
from 04-07-2016 to 08-07-2016
RECENDT
Linz
Austria
[en] laser ultrasonics ; ultrasounds ; non-destructive testing
[en] Usually laser ultrasonic systems use an infrared laser operating at 10 µm to generate the ultrasound in CFRP objects. However this system suffer from an important drawback: optical fiber cannot be used to transport the high energy beam from the laser output to the target which limits the flexibility of the system to investigated complex shaped objects.
To overcome this issue, visible light can be used to generate ultrasound. In our case we use a fiber-coupled laser operating at 532 nm. The output end of the optical fiber is placed on an industrial robot arm. The investigated object remains stationary while the optical fiber mounted on the robot arm scan the object. This system offers large flexibility but laser generation at 532 nm is known to be less efficient than CO 2 system emitting at 10 µm. Increasing the visible pulse power is one of the options but optics and CRFF object will be damaged before the same echo level as CO2 generation can be obtained.
An alternative solution consists in the investigation of the generation beam size and shape. We recently developed an optical design composed of an axicon lens able to generate annular beam. The diameter of the beam can be adapted. If the axicon lens is removed the optical system provides a disk whose diameter can also be adapted onto the investigated object.
Ray-traycing simulations performed with ASAP and experimental beam profile investigated with a
beam profiler show good agreement between theoretical and experimental optical design. An experimental comparison between ring and disk shapes will be presented. The comparisons take into account the beam diameter and the beam intensity but also the effect of the angle of incidence will be presented.
Centre Spatial de Liège - CSL
Service public de Wallonie : Direction générale opérationnelle de l'économie, de l'emploi et de la recherche - DG06
TECCOMA
Researchers
http://hdl.handle.net/2268/207254

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