This work presents time-resolved images of femtosecond-laser-induced melt dynamics in 60 nm gold films on glass substrates. Melt dynamics induced by laser radiation with focus diameters of 6 μm and 8 μm (FWHM) at constant laser fluence is investigated with a temporal resolution of 10 ns. In both cases, the formation of the microbumps and gold jets takes at least 250 ns. It is shown that the formation process can be compared to jetting behavior induced by cavitation bubbles near a free liquid surface. This is confirmed by SEM illustrating a re-entrant spike through a hole in the microbump.

We developed an all-fiber component with a signal feedthrough capable of combining up to 6 fiber-coupled multi-mode pump sources to a maximum pump power of 400 W at efficiencies in the range of 89 to 95%, providing the possibility of transmitting a high power signal in forward and in reverse direction. Hence, the fiber combiner can be implemented in almost any fiber laser or amplifier architecture. The complete optical design of the combiner was developed based on ray tracing simulations and confirmed by experimental results.

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Qualitative uncertainties are a key challenge for the further industrialization of additive manufacturing. To solve this challenge, methods for measuring the process states and properties of parts during additive manufacturing are essential. The subject of this review is in-situ process monitoring for material extrusion additive manufacturing. The objectives are, first, to quantify the research activity on this topic, second, to analyze the utilized technologies, and finally, to identify research gaps. Various databases were systematically searched for relevant publications and a total of 221 publications were analyzed in detail. The study demonstrated that the research activity in this field has been gaining importance. Numerous sensor technologies and analysis algorithms have been identified. Nonetheless, research gaps exist in topics such as optimized monitoring systems for industrial material extrusion facilities, inspection capabilities for additional quality characteristics, and standardization aspects. This literature review is the first to address process monitoring for material extrusion using a systematic and comprehensive approach.

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