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Ultrashort pulse laser machining is subject to increase the processing speeds by scaling average power and pulse repetition rate, accompanied with higher dose rates of X-ray emission generated during laser–matter interaction. In particular, the X-ray energy range below 10 keV is rarely studied in a quantitative approach. We present measurements with a novel calibrated X-ray detector in the detection range of 2–20 keV and show the dependence of X-ray radiation dose rates and the spectral emissions for different laser parameters from frequently used metals, alloys, and ceramics for ultrafast laser machining. Our investigations include the dose rate dependence on various laser parameters available in ultrafast laser laboratories as well as on industrial laser systems. The measured X-ray dose rates for high repetition rate lasers with different materials definitely exceed the legal limitations in the absence of radiation shielding.

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A first proof of concept for a heart valve-shaped scaffold was created by laser bonding. Thus, the laser is an advantageous tool for post-processing fiber mats and produce complex 3D structures for different applications.

Fabrication technologies for the semiconductor industry have enabled ever smaller electronic components but now face a fundamental limit in their assembly. As the components get smaller and smaller, the difficulty of assembly increases. At the same time, the number of components per circuit board area is growing, as is the case with LED displays. This in turn calls for an increasing assembly rate. The conventional pick-and-place method can handle approximately 25–30 thousand dies per hour but has increasing limitations when component dimensions are reduced below 150 μm edge length. Laser-induced forward transfer is used as a potential alternative for an assembly of semiconductor components. This technique allows to transfer semiconductor components with an edge length of less than 150 μm to a target substrate. The current process is contactless, damage-free, and has sufficient placement accuracy. If this process is combined with the property of high-pulse repetition rates, it is possible to significantly increase the assembly rate of semiconductor components compared to the current limitations. The aim of this study is to characterize the flight properties of silicon semiconductor components of various dimensions in a laser-driven transfer process using optical imaging methods. This method allows to analyze velocity, the direction of fall, and acceleration of falling components. The results can be used to analyze the transfer behavior of various component sizes and to make estimates of the stability of the transfer process.

The properties of glass (e.g., transparency, chemical and thermal inertness) are advantageous for optical, microfluidic, and chemical applications. Additive manufacturing allows the creation of complex geometries and novel functionalities. In contrast to metals and polymers, there are limited options for digitally creating transparent glass geometries. Glass becomes viscous when heated above its transition temperature. This allows a bubble-free forming but requires precise thermal management. Previously explored studies established the deposition of multiple types of glasses using fiber and rod feedstocks. A significant challenge is the speed of the process. Phonon modes in all of these glasses directly absorb CO2-laser radiation (λ = 10.6 μm) with an optical penetration depth of <10 μm [J. Bliedtner, H. Müller, and A. Barz, Lasermaterialbearbeitung: Grundlagen–Verfahren–Anwendungen–Beispiele (Carl Hanser Verlag GmbH Co KG, Munich, Germany, 2013), ISBN:3446429298]. The thermal energy must diffuse through the glass with low thermal conductivity to the interface with the workpiece. Faster deposition rates result in the temperature of the process zone exceeding the evaporation temperature for the material and cause material loss. This study quantifies the material loss due to evaporation for the first time and investigates the use of a CO laser (Coherent J-3-5) for the laser glass deposition process. Lower absorption in silica at the 5.5 μm wavelength of this laser permits much deeper optical penetration into the glass. The effects of surface versus volumetric heating resulting from the choice of laser are experimentally investigated by the deposition of glass fibers with different deposition rates with demonstrations of lower vaporization rates under faster deposition conditions.

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