Pulsed Laser Influence on Two-Beam Laser Metal Deposition

While pulsed lasers are generally used to process solid materials, there are other technologies based on interaction between pulsed lasers and liquids. One example is the double-beam laser brazing where material is molten by a cw-laser and spread using a pw-laser. This technology can be transferred to enhance process stability during laser metal deposition by adjusting the force applied on the liquid surface. It is known that the liquid's dynamic is controlled by the pressure caused by vaporization and opposed influences such as surface tension and gravity, but the magnitude of the force applied on the surface by the pw-laser remains unknown. This study tries to quantify the mean value of this force over time by placing a metal ball into the laser beam. The whole system is mounted on a stage, which is gradually tilted during the experiment. When the gravity forces exceed the pulsed laser pressure, the ball rolls down. Thus, laser parameters can be correlated to acting forces.