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TY - THES AU - Hofmann, Jörg TI - Kompensation thermischer Linseneffekte in optischen Systemen für die Lasermaterialbearbeitung PB - Rheinisch-Westfälische Technische Hochschule Aachen VL - Dissertation CY - Aachen M1 - RWTH-2025-04723 SP - 1 Online-Ressource : Illustrationen PY - 2025 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2025 AB - In laser material processing, optical systems are used e.g. for beam guidance and shaping. Particularly with laser powers in the multi-kilowatt range, the absorbed laser light leads to heating of the optical elements. One consequence is the so-called thermal lens effect. The thermal lens effect leads to a change in the focal length of the optical system and thus to a shift in the focal position relative to the workpiece. This can lead to reduced machining quality or even to an abortion of the machining process. This thesis therefore investigates various concepts for active and passive compensation of thermal effects. A passive approach for the compensating of thermal effects is investigated using the example of plastic optics for a laser power of 15 W. Compared to glass optics, plastic optics exhibit thermal effects that are about 100 times greater at the same laser power, which is why their range of application has so far been limited to optical systems with laser powers <<1 W. On the other side, they offer considerable cost-saving potential due to their injection molding production. Passive compensation of thermal effects through a different combination of thermoplastics is not possible due to their similar material parameters. This work therefore pursues a passive approach in which the geometry of an existing plastic lens is adapted for a specific operating condition. This approach extends the power range that has been effectively usable to date. To this end, the laser and material parameters relevant to the thermo-optical design are first identified using a sensitivity analysis and measured using various measurement methods. The lens geometry is then optimized for the operating condition based on the laser and material parameters. The adapted lens geometry is produced by injection moulding and then characterized with regard to its optical properties. The compensated lens geometry has a Gaussian intensity distribution in the focal plane but deviates from the target value by 27 LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2025-04723 UR - https://publications.rwth-aachen.de/record/1011781 ER -