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Optical Coherence Tomography for 3D Weld Seam Localization in Absorber-Free Laser Transmission Welding

  • Quality and reliability are of the utmost importance for manufacturing in the optical and medical industries. Absorber-free laser transmission welding enables the precise joining of identical polymers without additives or adhesives and is well-suited to meet the demands of the aforementioned industries. To attain sufficient absorption of laser energy without absorbent additives, thulium fiber lasers, which emit in the polymers’ intrinsic absorption spectrum, are used. Focusing the laser beam with a high numerical aperture provides significant intensity gradients inside the workpiece and enables selective fusing of the internal joining zone without affecting the surface of the device. Because seam size and position are crucial, the high-quality requirements demand internal weld seam monitoring. In this work, we propose a novel method to determine weld seam location and size using optical coherence tomography. Changes in optical material properties because of melting and re-solidification during welding allow for weld seam differentiation from the injection-molded base material. Automatic processing of the optical coherence tomography data enables the identification and measurement of the weld seam geometry. The results from our technique are consistent with microscopic images of microtome sections and demonstrate that weld seam localization in polyamide 6 is possible with an accuracy better than a tenth of a millimeter.

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Metadaten
Author:Frederik MaiwaldORCiD, Clemens Roider, Michael Schmidt, Stefan HierlGND
DOI:https://doi.org/10.3390/app12052718
Parent Title (English):Applied Sciences
Publisher:MPDI
Place of publication:Basel
Document Type:Article
Language:English
Year of first Publication:2022
Release Date:2022/03/31
Tag:image processing; laser transmission welding; optical coherence tomography; process monitoring; transparent polymers
Volume:12
Issue:5
Article Number:2718
First Page:1
Last Page:11
Note:
Corresponding author: Frederik Maiwald
Institutes:Fakultät Maschinenbau
Fakultät Maschinenbau / Labor Laser-Materialbearbeitung (LMP)
Begutachtungsstatus:peer-reviewed
research focus:Produktion und Systeme
OpenAccess Publikationsweg:Corresponding author der OTH Regensburg
Licence (German):Creative Commons - CC BY - Namensnennung 4.0 International