Laser-ultrasonics three-dimensional imaging of advanced composite materials

We present a laser-ultrasonic system that can scan large areas of parts made from composite materials. Since, with laser-ultrasonics, there is no need for normal incidence of the laser beams on the part to be inspected, this system can inspect samples of curved or awkward surfaces using a two rotation-axis scanning mirror. A ranging system accurately measures the distance of the part from the system. The angular position of the scanning mirror and the range information provide a spherical reconstruction model that allows us to generate (without prior knowledge) the geometry of the surface of the inspected part. Since the laser generated ultrasonic pulses propagate in a direction normal to the surface, the reconstruction model includes the generation of a mesh of the surface to determine the normal direction. With traditional tools for three dimensional representation, such as voxelization and isosurfaces, we obtain a powerful method for visualizing the inspection of composite materials of complex shapes