Mr. Alexander Gatej Profile

Alexander Gatej

Corporate Innovation Expert at Vanturious FZC-LLC

SPIE Involvement:

Author

Area of Expertise:

Corporate Innovation , Forschungszulage , Public Funding , Laser Technology , Optical Industry

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Alexander Gatej graduated with a Diploma in Industrial Engineering from the University of Erlangen-Nuremberg, Germany in 2009. In 2012, he assumed the role of the head of the 'Optical Systems' group. Subsequently, he earned his PhD in Engineering in 2014 for his dissertation on thermal lensing in optical systems from RWTH Aachen University, in collaboration with the Fraunhofer-Institute for Laser Technology.
With a decade of experience in corporate innovation in diverse management roles within the industry, Alexander established Vanturious - a company exclusively dedicated to facilitating research and development (R&D) activities through participation in Forschungszulage, a specialized German R&D funding program.

SPIE Journal Paper | 8 October 2014 Open Access

Process observation in fiber laser–based selective laser melting

Ulrich Thombansen, Alexander Gatej, Milton Pereira

OE, Vol. 54, Issue 01, 011008, (October 2014) https://doi.org/10.1117/12.10.1117/1.OE.54.1.011008

KEYWORDS: Fiber lasers, Signal processing, Spatial light modulators, Manufacturing, Lenses, Sensors, Data acquisition, Laser processing, Cameras, Pyrometry

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The process observation in selective laser melting (SLM) focuses on observing the interaction point where the powder is processed. To provide process relevant information, signals have to be acquired that are resolved in both time and space. Especially in high-power SLM, where more than 1 kW of laser power is used, processing speeds of several meters per second are required for a high-quality processing results. Therefore, an implementation of a suitable process observation system has to acquire a large amount of spatially resolved data at low sampling speeds or it has to restrict the acquisition to a predefined area at a high sampling speed. In any case, it is vitally important to synchronously record the laser beam position and the acquired signal. This is a prerequisite that allows the recorded data become information. Today, most SLM systems employ f-theta lenses to focus the processing laser beam onto the powder bed. This report describes the drawbacks that result for process observation and suggests a variable retro-focus system which solves these issues. The beam quality of fiber lasers delivers the processing laser beam to the powder bed at relevant focus diameters, which is a key prerequisite for this solution to be viable. The optical train we present here couples the processing laser beam and the process observation coaxially, ensuring consistent alignment of interaction zone and observed area. With respect to signal processing, we have developed a solution that synchronously acquires signals from a pyrometer and the position of the laser beam by sampling the data with a field programmable gate array. The relevance of the acquired signals has been validated by the scanning of a sample filament. Experiments with grooved samples show a correlation between different powder thicknesses and the acquired signals at relevant processing parameters. This basic work takes a first step toward self-optimization of the manufacturing process in SLM. It enables the addition of cognitive functions to the manufacturing system to the extent that the system could track its own process. The results are based on analyzing and redesigning the optical train, in combination with a real-time signal acquisition system which provides a solution to certain technological barriers.

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Proceedings Article | 1 May 2014 Paper

Methods for compensation of thermal lensing based on thermo-optical (TOP) analysis

Alexander Gatej, Peter Loosen

Proceedings Volume 9131, 91310F (2014) https://doi.org/10.1117/12.2052203

KEYWORDS: Silica, Absorption, Cameras, Thermal effects, Metrology, Coating, Data modeling, Thermography, Charge-coupled devices, Collimation

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Proceedings Article | 20 February 2014 Paper

Tracking the course of the manufacturing process in selective laser melting

U. Thombansen, Alexander Gatej, M. Pereira

Proceedings Volume 8963, 89630O (2014) https://doi.org/10.1117/12.2040330

KEYWORDS: Manufacturing, Laser processing, Spatial light modulators, Cameras, Lenses, Scanners, Sensors, Signal processing, Optics manufacturing, Laser applications

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Proceedings Article | 17 October 2012 Paper

Thermo-Optical (TOP) analysis of transmissive elements for laser systems

Alexander Gatej, Annika Richmann, Oliver Pütsch, Peter Loosen

Proceedings Volume 8490, 84900C (2012) https://doi.org/10.1117/12.929213

KEYWORDS: Ray tracing, Optical simulations, Finite element methods, Absorption, Computer simulations, Polishing, Glasses, Optical design, Carbon dioxide lasers, Laser systems engineering

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Proceedings Article | 5 May 2012 Paper

Thermo-optical (TOP) analysis by coupling FEM and ray tracing

Alexander Gatej, Johannes Wasselowski, Peter Loosen

Proceedings Volume 8429, 84290E (2012) https://doi.org/10.1117/12.921533

KEYWORDS: Finite element methods, Ray tracing, Absorption, Optical simulations, Optical design, Optical components, Coating, Laser applications, Interfaces, Geometrical optics

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