Dynamic high-power beam-shaping for 3D laser polishing

Laser-based surface processing methods such as polishing either have too low processing speeds or are restricted to flat workpiece surfaces, both of which currently limit their broad industrial application. Application-adapted intensity distributions allow to tailor the temperature profile to the process in order to increase the processing speed but require dynamic adaptation for 3D surface processing. In this work, an optical design and setup for the shaping and dynamic compensation of an application-adapted intensity distribution is presented. The optics allow for a free rotation of the distribution and a compression of the distribution along an arbitrary axis perpendicular to the optical axis. The compression enables the compensation for the distortion of the distribution on tilted or curved work surfaces. For the laser polishing application, the optics also needs to handle at least 2 kW of continuous wave laser power. Due to the complexity of the intensity distribution, a diffractive optical element (DOE) is used for the initial beam shaping. To take into account the influence of the DOE, the optical design required a combination of ray-tracing and beam propagation methods.