Aktive und adaptive Strahlformungssysteme für die Werkstoffbearbeitung mit Laserstrahlung
- Active and adaptive beam shaping systems for material processing with laser radiation
Pütsch, Oliver; Loosen, Peter (Thesis advisor); Schmitt, Robert (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen, 2016
Due to its technology-related advantages the laser has maintained a highly flexible tool in industrial manufacturing. A large number of applications in laser material processing requires the generation of process adapted intensity distributions in the interaction zone, thus a tailored energy coupling for a particular machining process as well as the working geometry is facilitated. This functionality is provided by active or adaptive optical systems that transform the raw laser beam emitted from the laser source using spatially and temporally-varying beam shaping properties. The realization of such beam shaping systems is provided using two system technologies concerning those current drawbacks are identified. Opto-kinematic multibody systems base upon the reorientation of static optical components along defined motion paths. For the wavelength independent homogenization of laser beams mirror-based systems offer insufficient automation ability for the continuous scaling of the intensity distribution. However, the more suitable concepts basing on transmission only have limited use for the utilization of long-wave laser radiation. This drawback of opto-kinematic multibody systems is addressed by the development of a new concept for wavelength-independent, scalable laser beam homogenization. The scanner-based 3D laser material processing is subject to field-variant projection influences that cause a deformation of the intensity distribution in the interaction zone. The deformation emerges due to the non-perpendicular incidence of the laser beam on the working surface. Depending on the sensitivity of the machining process, the currently pursued strategy of the increase of the laser power will not lead to sufficient compensation. This drawback is counteracted in this work with the development of an adaptive beam shaping system. A significant increase in the spatial and temporal modulation capability is achieved by opto-electromechanical manipulation through the use of highly integrated components. Due to the relatively low cost and high efficiency, in particular commercially available, electrostatic membrane mirrors have become more important in the field of active laser beam shaping. The standardized functionality of commercial optical development environments do not take into account the characteristics of opto-electromechanical manipulation. Therefore, during the optical design no holistic optimization and evaluation of beam shaping properties can be carried out. This drawback is counteracted with the development of an integrated development methodology.