Univ. Prof. Dr. Ing.

Bergs, Thomas

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  • Publication
    Compensation of structure distortion in nonisothermalhot forming of laser structured thin glass
    ( 2024-06-12)
    Kohse, Martin orcid-logo
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    Meiners, Constantin
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    Plakhotnik, Denys
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    Vogel, Paul-Alexander
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    Day, Robin
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    Grunwald, Tim
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    Bergs, Thomas
    The modern automotive industry employs various complex shaped glass components. Around 50% of these components are currently functionalized using environmentally and economically unfriendly etching or replication processes. We present a new approach of direct laser structuring on glass, which reduces costs and energy by up to 60% and avoids harmful chemicals, offering a more sustainable alternative to conventional processes.
  • Publication
    Precision Glass Molding of Fused Silica Optics
    ( 2024-05-28)
    Karimova, Albina
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    Vu, Anh Tuan orcid-logo
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    Grunwald, Tim
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    Bergs, Thomas
    Fused silica glass products have exceptional properties that make them ideal for optical components in cutting-edge technologies. The traditional manufacturing process has limitations in scalability and cost. Glass molding offers a sustainable solution for series production of optical components. However, the transferability of glass molding to mass production is challenging due to high forming temperatures. This research focuses on enabling a high temperature molding process for fused silica optics through material screening, numerical simulation, and real experiments. The findings contribute to the development of a high temperature molding process for mass production.
  • Publication
    Surrogate Modeling for Multi-Objective Optimization in the High-Precision Production of LiDAR Glass Optics
    ( 2024-04-26)
    Vu, Anh Tuan orcid-logo
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    Paria, Hamidreza
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    Grunwald, Tim
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    Bergs, Thomas
    This study addresses the ever-increasing demands on glass optics for LiDAR systems in autonomous vehicles, highlighting the pivotal role of the recently developed Nonisothermal Glass Molding (NGM) in enabling the mass production of complex and precise glass optics. While NGM promises a significant advancement in cost- and energy-efficient solutions, achieving the requisite shape and form accuracy for high-precision optics remains a persistent challenge. The research focuses on expediting the development phase, presenting a methodology that strategically utilizes a sparse dataset for determining optimized molding parameters with a minimized number of experimental trials. Importantly, our method highlights the exceptional ability of a robust surrogate model to precisely predict the accuracy outputs of glass optics, strongly influenced by numerous input molding parameters of the NGM process. This significance emphasizes the surrogate model, which emerges as a promising alternative to inefficient traditional methods, such as time-consuming experiments or computation-intensive simulations, particularly in the realm of high-precision production for LiDAR glass optics. In contributing to optics manufacturing advancements, this study also aligns with contemporary trends in digitalization and Industry 4.0 within modern optics production, thereby fostering innovation in the automotive industry.
  • Publication
    Surrogate modeling for multi-objective optimization in the high-precision production of LiDAR glass optics
    ( 2024-04-24)
    Vu, Anh Tuan orcid-logo
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    Paria, Hamidreza
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    Grunwald, Tim
    ;
    Bergs, Thomas
    This study addresses the ever-increasing demands on glass optics for LiDAR systems in autonomous vehicles, highlighting the pivotal role of the recently developed Nonisothermal Glass Molding (NGM) in enabling the mass production of complex and precise glass optics. While NGM promises a significant advancement in cost- and energy-efficient solutions, achieving the requisite shape and form accuracy for high-precision optics remains a persistent challenge. The research focuses on expediting the development phase, presenting a methodology that strategically utilizes a sparse dataset for determining optimized molding parameters with a minimized number of experimental trials. Importantly, our method highlights the exceptional ability of a robust surrogate model to precisely predict the accuracy outputs of glass optics, strongly influenced by numerous input molding parameters of the NGM process. This significance emphasizes the surrogate model, which emerges as a promising alternative to inefficient traditional methods, such as time-consuming experiments or computation-intensive simulations, particularly in the realm of high-precision production for LiDAR glass optics. In contributing to optics manufacturing advancements, this study also aligns with contemporary trends in digitalization and Industry 4.0 within modern optics production, thereby fostering innovation in the automotive industry.
  • Publication
    Precision glass molding process enhancing the expanding of chip-on-tip endoscopes
    ( 2023-06-07)
    Jiang, Cheng orcid-logo
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    Friedrichs, Marcel
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    Grunwald, Tim
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    Bergs, Thomas
    A new endoscope structure called chip-on-tip is designed to reach both miniaturization and affordability beyond the conventional rigid endoscope. Hence, the precision glass molding process as a replicative manufacturing method can be integrated into the endoscopes production chain and deliver the optics with not only high quality but also reasonable cost under large production volume.
  • Publication
    Precision glass molding process enhancing the expanding of chip on tip endoscopes
    ( 2023-06-07)
    Jiang, Cheng orcid-logo
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    Friedrichs, Marcel
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    Grunwald, Tim
    ;
    Bergs, Thomas
    A new endoscope structure called chip-on-tip is designed to reach both miniaturization and affordability beyond the conventional rigid endoscope. Hence, the precision glass molding process as a replicative manufacturing method can be integrated into the endoscopes production chain and deliver the optics with not only high quality but also reasonable cost under large production volume.
  • Publication
    Efficient Fiber-Photonic Integrated Circuit Connection via Wafer-Scale Glass Molding
    ( 2022-12-12)
    Michels, Robert
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    Grunwald, Tim
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    Bergs, Thomas
    Increasing demand for higher data rates in data centers is driving efforts to produce single-mode optics, which substantially improves the commonly used infrastructures. However, the fiber cou-pling to photonic integrated circuits (PICs) is currently a bottle neck. The optics needed to link optical fibers to PICs are sub-millimeter in size and call for extreme precision both at the manu-facturing as well as the assembling stage. Using glass instead of plastic optics increases the optical performance and therefore, the transmissible data rates but results in higher production costs. Fraunhofer IPT and partners developed an innovative, efficient glass fiber coupling technology based on the replicative process of glass molding. In a glass molding process, a glass preform is heated until the viscous state and afterwards pressed into the desired shape using two high-precise molds. This process permits the direct and efficient manufacture of high shape accuracy and sur-face quality optics without any mechanical post-processing steps. To fabricate the fiber couplers, two different glass molding technologies were explored and compared: The highly precise, but slow isothermal process of precision glass molding (PGM) and the more efficient, but less precise non-isothermal glass molding (NGM). A scale-up strategy has been developed which is based on a wafer-scale approach. This allowed producing a large number of identical elements in one mold-ing operation out of a single glass wafer, which increased the efficiency both of the manufacturing process and of the subsequent assembly operations. The development covers all aspects of the realization of single-mode fiber coupling - from the optical and electrical design of the connectors and PICs through process technology, machine tool manufacture and assembly technology to ap-plication within the system and the analysis of the coupling efficiency from fiber to PIC.
  • Publication
    Simulation of the Refractive Index Variation and Validation of the Form Deviation in Precisely Molded Chalcogenide Glass Lenses (IRG 26) Considering the Stress and Structure Relaxation
    ( 2022-09-29)
    Jiang, Cheng orcid-logo
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    Marin Tovar, Carlos orcid-logo
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    Staasmeyer, Jan-Helge
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    Friedrichs, Marcel
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    Grunwald, Tim
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    Bergs, Thomas
    Precise infrared (IR) optics are core elements of infrared cameras for thermal imaging and night vision applications and can be manufactured directly or using a replicative process. For instance, precision glass molding (PGM) is a replicative manufacturing method that meets the demand of producing precise and accurate glass optics in a cost-efficient manner. However, several iterations in the PGM process are applied to compensate the induced form deviation and the index drop after molding. The finite element method (FEM) is utilized to simulate the thermomechanical process, predicting the optical properties of molded chalcogenide lenses and thus preventing costly iterations. Prior to FEM modelling, self-developed glass characterization methods for the stress and structure relaxation of chalcogenide glass IRG 26 are implemented. Additionally, a ray-tracing method is developed in this work to calculate the optical path difference (OPD) based on the mesh structure results from the FEM simulation. The developed method is validated and conducted during the production of molded lenses.
  • Publication
    Enabling Sustainability in Glass Optics Manufacturing by Wafer Scale Molding
    ( 2022-07-22)
    Strobl, Christian
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    Vogel, Paul-Alexander
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    Vu, Anh Tuan orcid-logo
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    Mende, Hendrik
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    Grunwald, Tim
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    Schmitt, Robert H.
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    Bergs, Thomas
    Numerous optical applications have rising demands for ever increasing quantities from lighting and projection optics for modern vehicles to home or street lighting using LED technology. Glass is the material of choice for most of those application fields. It has several advantages over polymers, including heat and scratch resistance as well as longevity and recyclability. Non-isothermal glass molding has become a viable hot forming technology for mass production of optics. The major challenge is enabling a scalable replication process allowing the optical glass elements to be manufactured with high form accuracy and at low-cost production with low reject rates. This work introduces recent developments in glass optics manufacturing that allow the fulfilment of seemingly contradicting criteria: the economic growth and the need for less consumption of resources and energy. While single cavity non-isothermal molding is state-of-the-art, a manufacturing innovation through wafer-scale molding enables an exponentially increasing number of optics to be produced per production shift, allowing a significant reduction of unit costs. In parallel, as multiple optics are produced in one manufacturing cycle, the energy consumption and the consequent CO2 emission can be reduced. In contrast, the technological development arises several challenges that will be discussed in this work. Besides the selection of suitable mold concepts and materials, the challenges also include the temperature control of the mold and the blank up to the optimization of flow and shrinking mechanisms of the glass during rapid forming. Another difficulty in the non-isothermal glass molding is to maintain the low form deviation required for precision optics, repeatability, and low failure rates through process optimization. Finally, detail calculations of cost, energy and CO2 consumption, in comparison with conventional fabrication of glass components using grinding and polishing as well as single cavity molding, will be demonstrated. The non-isothermal wafer-level glass molding is a new technological solution for the sustainable manufacturing of optics at large-scaled production.