Visualization of weld defects in water by laser-ultrasonics

We present a new method of visualized weld defects in water by laser-ultrasonics. To detect and visualize a surface of weld metal with welding bead, the authors have developed a new detection method by leaky wave induced by interaction with surface acoustic waves and defects. Furthermore, developing Synthetic Aperture Focus Technique (SAFT) for visualized inspection surface 2-dementionally, we achieve the inspection result alike Penetrant Testing (PT) despite underwater environment. The proposed method can visualize weld defect of pit with around φ0.16mm and weld cracks with opening of a few μm and around 0.24mm in length.