Process and Beam Control

Monitoring systems are needed to promote process understanding and facilitate certification purposes of complex laser-based additive manufacturing and micro- and nanostructuring processes since the industry places such high demands upon their quality and productivity. Fraunhofer ILT develops and implements a wide range of technologies for inline process monitoring and control, in particular for improving product and process quality. Pyrometric and camera-based systems with analysis tools for thermal or plasma radiation as well as laser-based measurement methods are used here and allow efficient inline process monitoring. This way, defective components or processes can be quickly detected and downstream quality controls replaced.

Not only is acquiring process information important, but it is also crucial to record the process flow through intermediate and trend information. In this context, process sensor technology is an important element for optimizing laser machining processes. The efficient and stable use of sensors in industrial environments requires a high level of process understanding; knowledge and experience from the areas of process development and modeling, system technology as well as beam source development flow into the development and integration of systems for process monitoring. In order to promote process-specific advantages of laser material processing, non-contact measurement processes are commonly used, such as spectroscopy, triangulation, pyrometry, thermography and camera-based methods.

Process data are evaluated with new analysis methods in order to meet the high demands of laser material processing in real time. Modern AI-based processes are used here, which, among other things, make it possible to sharpen process classification.

The range of services we offer includes running feasibility studies, developing and implementing technologies for process visualization and process diagnostics, process monitoring and process control, integrating them in industrial manufacturing environments as well as consulting on an individual basis.

Range of services: Process and beam monitoring

• Monitoring, control and regulation of laser manufacturing processes for many applications of laser technology at different processing wavelengths
• Process monitoring with high spatial and temporal resolution camera systems and fast hardware-based real-time image processing
• Feasibility studies on the feasibility of process monitoring and control
• Integration of process monitoring and control in existing production facilities
• Development of application-oriented tailor-made sensors, e.g. for the seam sequence in laser beam welding, distance measurement in laser buildup welding
• Design of networked multi-sensor systems, e.g. for production data acquisition or multi-parameter control

Neuß, J, Linden, S:
Hide and Seek: Using masked vision transformer to detect surface structures on laser polished metals.
25th International Symposium on Laser Precision Microfabrication, June 11-14, 2024, San Sebastian, Spain.
Proceedings of LPM2024, #24-033, (9 S,), (2024)

Knaak, C., von Eßen, J., Kröger, M.., Schulze, F., Abels, P., Gillner, A.:
A Spatio-Temporal Ensemble Deep Learning Architecture for Real-Time Defect Detection during Laser Welding on Low Power Embedded Computing Boards.
Sensors 21(12), 4205- (28 S.), (2021)
https://doi.org/10.3390/s21124205 (Open Access)

Knaak, C., Masseling, L., Duong, E., Abels, P., Gillner, A.:
Improving build quality in laser powder bed fusion using high dynamic range imaging and model-based reinforcement learning.
IEEE Access 9, 55214-55231 (2021)
https://doi.org/10.1109/ACCESS.2021.3067302

Knaak, C., Abels, P.:
KI-basierte Prozessüberwachung von Laserstrahl-Schweißnähten.
QZ 65, 60-62 (2020)

Knaak, C., Kolter, G., Schulze, F., Kröger, M., Abels P.:
Deep learning-based semantic segmentation for in-process monitoring in laser welding applications.
PROCEEDINGS OF SPIE 11139 - (2019)
https://doi.org/10.1117/12.2529160

Knaak, C., Thombansen, U., Ables, P., Kröger, M.:
Machine learning as a comparative tool to determine the relevance of signal
features in laser welding.
CIRP ANNALS 74, 623-627 (2018)
https://doi.org/10.1016/j.procir.2018.08.073

Rodriguez-Araujo, J., Garcia-Diaz, A., Panadeiro, V., Knaak, C.:
Uncooled MWIR PbSe technology outperforms CMOS in RT closed-loop control and monitoring of laser processing.
OSA TECHNICAL DIGEST, 1-3 (2017)
https://doi.org/10.1364/AIO.2017.ATh2A.2

Özmert, A., Neisser-Deiters, P., Drenker, A.:
Detectability of penetration depth based on weld pool geometry and process emission spectrum in laser welding of copper
Proc. SPIE 9135, 91351W (7 S.) (2014)
https://doi.org/10.1117/12.2051662

Thombansen, U., Gatej, A., Pereira, M.:
Tracking the course of the manufacturing process in selective laser melting
Proc. SPIE 8963, 89630O (7 S.) (2014)
https://doi.org/10.1117/12.2040330

Thombansen, U., Hermanns, T.:
In-situ measurement of the focal position in one and ten micron laser cutting
Proceedings 33rd Int. Congress on Applications of Lasers & Electro-Optics (ICALEO), October 19-23, 2014, San Diego, USA, Paper 179, ISBN 9781940168029 (4 S.) (2014)
https://doi.org/10.2351/1.5063049

Thombansen, U., Hermanns, T.: Molitor, T., Pereira, M., Schulz, W.:
Measurement of cut front properties in laser cutting
Physics Procedia 56, 885-891 (2014)
https://doi.org/10.1016/j.phpro.2014.08.107

Thombansen, U., Hermanns, T., Stoyanov, S.:
Setup and maintenance of manufacturing quality in CO2 laser cutting
Procedia CIRP 20, 98 – 102 (2014)
https://doi.org/10.1016/j.procir.2014.05.037

Thombansen, U., Ungers, M.:
Illumination for process observation in laser material processing
Physics Procedia 56, 1286-1296 (2014)
https://doi.org/10.1016/j.phpro.2014.08.053

Thombansen, U., Ungers, M.:
Cognition for robot scanner based remote welding
Proc. SPIE  8963, 89630N (8 S.) (2014)
https://doi.org/10.1117/12.2040275

Oezmert, A., Drenker, A., Nazery, V.:
Detectability of penetration based on weld pool geometry and process emission spectrum in laser welding of copper
Physics Procedia 41, 502-507 (2013)
https://doi.org/10.1016/j.phpro.2013.03.108

Thombansen, U., Purrio, M., Buchholz, G., Hermanns, T., Molitor, T., Willms, K., Schulz, W., Reisgen, U.:
Measurement of process variables in melt based manufacturing processes
In: ISMTII 2013 - The 11th International Symposium on Measurement Technology and Intelligent Instruments,
Aachen /Braunschweig July 1st-5th 2013 (6 S.) (2013)

Thombansen, U., Beckers, M., Buchholz, G., Hermanns, T., Molitor, T. Willms, K., Reisgen, U., Schulz, W.:
Signal processing for self-optimising manufacturing systems in laser-cutting and gas-metal-arc-welding
In: 1st Joint International Symposium on System-Integrated
Intelligence, 114-116, (2012)

Frank, S., Ungers, M., Rolser, R.:
Coaxial control of aluminium and steel laser brazing processes.
Phys. Proced. 12, Part A, 752-760, (2011)
https://doi.org/10.1016/j.phpro.2011.03.094

Franz, C., Abels, P., Rolsner, R., Becker, M.:
Energy input per unit length - high accuracy kinematic metrology in laser material processing.
Phys. Proced. 12, Part B, 411-420, (2011)
https://doi.org/10.1016/j.phpro.2011.03.151

Franz, C., Abels, P., Merz, M., Singpiel, H., Trein, J.:
Real-time process control by machine vision.
CALEO 30. Int. Congr. on Applications of Lasers and Electro-Optics, October 23-27, 2011. Paper 205, 6 S., (2011)
https://doi.org/10.2351/1.5062179

Franz, C., Singpiel, H., Trein, J.:
Tracking the contour.
Laser Technik J. 8, Nr. 5, 41-44, (2011)
https://doi.org/10.1002/latj.201190058

Gatej, A., Thombansen, U., Loosen, P.:
Kombinierte thermo-optische Simulation für optische Systeme.
DGaO-Proc. 112, 2 S., (2011)

Gatej, A., Thombansen, U., Loosen, P.:
Simulation des thermischen Linseneffekts in hochbelasteten Lasersystemen.
Photonik 5, 54-56, (2011)

Thombansen, U., Schüttler, J., Auerbach, T. [u.a.]:
Model-based self-optimization for manufacturing systems.
Proc. of the 2011 Int. Conf. on Concurrent Enterprising (ICE 2011).
Eds.: K.-D. Thoben [u.a.] Piscataway, NJ : IEEE 2011. 9 S.

Thombansen, U., Auerbach, T.:
Der Weg zu Selbstoptimierenden Fertigungstechnologien.
In: Brecher, C. (Hrsg.): Integrative Produktionstechnik für Hochlohnländer, pp. 849-909, (2011)
https://doi.org/10.1007/978-3-642-20693-1_6

Fiedler, W., Drenker, A., Kaierle, S.:
Process monitoring and control during hybrid laser-arc welding of medium section steel sheets
ICALEO 2010. 29th International Congress on Applications of Lasers & Electro Optics, Anaheim/Ca., Paper 205, 7 S., (2010)
https://doi.org/10.2351/1.5062116

Franz, C., Abels, P.:
Measuring welding velocity at tool center point
ICALEO 2010. 29th International Congress on Applications of Lasers & Electro Optics, Anaheim/Ca., Paper 1909, 8 S., (2010)

Kaierle, S., Kowalick, K., Regaard, B.:
Laser process monitoring: The next generation approach in industrial application.
PICALO 2010, March 23-25, 2010, 4th Pacific International Conference on Applications of Lasers and Optics.
Wuhan, Peoples Republic of China, Paper 405, (2010)
https://doi.org/10.2351/1.5057199

Kaierle, S., Ungers, M., Franz, C., Mann, S., Abels, P.:
Understanding the laser process
Laser Technik J. 7, Nr 2, 49-52, (2010)
https://doi.org/10.1002/latj.201090027

Stache, N., Dieckelmann, J., Firnich, R., Gedicke, J., Abels, P., Olowinsky, A., Aach, T.:
High speed video-based melt pool surveillance in laser spot welding
Proc. of the 27th Int. Congress on Applications of Lasers & Electro-Optics 2008, ICALEO, Temecula, CA, USA, October 20-23, (2008)
https://doi.org/10.2351/1.5061371

Kaierle, S., Abels, P., Fiedler, W., Mann, S., Regaard, S.:
Online-Qualitätssicherung für das Laserstrahlschweissen
MB-Revue 132-135, (2008)

Kaierle, S.:
Process monitoring and control of laser beam welding
Laser Technik J. 5, Nr. 3, 41-43, (2008)
https://doi.org/10.1002/latj.200890024

Abels, P., Roesner, A., Kaierle, S., Mann, S., Olowinsky, A., Matsuo, N., Hino, A.:
Various process monitoring approaches of transparent thermoplastics laser beam welding
Proc. of the 27th Int. Congress on Applications of Lasers & Electro-Optics 2008, ICALEO, Temecula, CA, USA, 99-104, (2008)
https://doi.org/10.2351/1.5061367

Gedicke, J., Olowinsky, A., Jansen, U., Schulz, W., Gillner, A.:
Weld depth control in fiber laser welding of thin metal sheets
Proc. of the 27th Int. Congress on Applications of Lasers & Electro-Optics 2008, ICALEO, Temecula, CA, USA, October 20-23, (2008)
https://doi.org/10.2351/1.5061374

Kaierle, S., Dahmen, M., Mann, S., Poprawe, R.:
Autonomous Production Cell for Laser Beam Welding
Proc. Int. Conf. on Competitive Manufacturing "COMA 07", Stellenbosch, Südafrika, 6 S., (2007)

Franz, C., Mann, S., Kaierle, S.:
Comparison of process monitoring strategies for laser transmission welding of plastics
Proc. of ICALEO 2007, Orlando, Fl. 602-606, (2007)
https://doi.org/10.2351/1.5060992

Dahmen, M., Fiedler, W., Regaard, B., Kaierle, S.:
Continuous process control during laser beam welding of small section Aluminium sheet
Proc. of WLT Conf. Lasers in Manufacturing, Munich, 5 S., (2007)

Regaard, B., Fiedler, W., Kaierle, S:
Error detection in lap welding applications using on-line melt pool contour analysis by coaxial process monitoring with external illumination
Proc. of WLT Conf. Lasers in Manufacturing, Munich, 5 S., (2007)

Fiedler, W., Dahmen, M., Kaierle, S.:
Process control of laser beam welded small section aluminum sheets
Proc. of ICALEO 2007, Orlando, Fl., 271-276, (2007)
https://doi.org/10.2351/1.5061212

Gedicke, J., Regaard, B., Klages, K., Olowinsky, A., Kaierle, S.:
Comparison of different process monitoring methods for laser beam micro welding
Proceedings of ICALEO 2006, 8 S., (2006)
https://doi.org/10.2351/1.5060910

Gedicke, J., Regaard, B., Gillner, A., Kaierle, S.:
Kontrolle beim Mikroschweißen - Automatisierte Prozessüberwachung durch koaxiale Prozesskontrolle mit Fremdbeleuchtung
Laser Technik Journal 3, 33-37, (2006)
https://doi.org/10.1002/latj.200790120

Regaard, B., Kaierle, S., Poprawe, R.:
Self guided laser welding
Proceedings of ICALEO 2006, 7 S., (2006)
https://doi.org/10.2351/1.5060847