Fundamental studies are performed concerning the development of joining, surface modification and removal processing with a laser beam. In particular, the mechanisms of joining and imperfection formation are clarified by the high-speed observation and measurement of laser and/or arc welding phenomena with optical sensors or X-ray transmission imaging techniques. Further studies of monitoring, adaptive control and simulation of processing are undertaken on metallic, ceramic or plastic materials to obtain a basic knowledge in producing high quality welds at all times. Moreover, researches are made of laser brazing, laser-arc hybrid welding, underwater laser welding or repairing, and laser joining of dissimilar materials such as different metals or metal and plastic.

1. Laser weldability of various materials.
2. Development of high-quality, high-performance, highprecision and high-efficiency laser welding process.
3. Elucidation of laser welding phenomena and imperfection formation mechanisms, and development of remedies.
4. Laser joining of dissimilar materials (Laser-assisted metal-plastic joining)
5. Development of monitoring and adaptive control in laser welding.
6. Fundamental studies of materials processing utilizing laser.