TY - CHAP A1 - Maiwald, Frederik A1 - Fries, Fabian A1 - Schulze, Julian A1 - Honnerová, Petra A1 - Hierl, Stefan A1 - Schmidt, Michael T1 - Optical coherence tomography for in situ weld seam monitoring in absorber-free laser transmission welding T2 - Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXX, 25-31 January 2025, San Francisco, California, United States N2 - Optical and medical devices are frequently made of polymers and place high demands on precision, cleanliness, and reliability of the manufacturing processes used. Absorber-free laser transmission welding is well-suited for joining these devices: the energy input is contactless, no adhesives, additives, or absorbers are required, and the fiber lasers used enable precise weld seams. As the weld seam geometry is decisive for the joint strength and thus crucial for the quality of the product, the welding process is monitored in-situ using Optical Coherence Tomography (OCT). Subsequently, the weld seam geometry is identified automatically using the AI model "Segment Anything" (SAM), which performs semantic segmentation of the OCT data without requiring any training from the user. Welding tests using polyamide six indicate that the seam size is measured with an accuracy of a few hundredths of a millimeter, showing excellent agreement with microscopic images of microtome sections. Y1 - 2025 U6 - https://doi.org/10.1117/12.3040607 PB - SPIE ER -