Univ. Prof. Dr. Ing.

Bergs, Thomas

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  • Publication
    Precision Glass Molding of infrared optics with anti-reflective microstructures
    ( 2020)
    Rojacher, Cornelia
    ;
    Vu, Anh Tuan orcid-logo
    ;
    Grunwald, Tim
    ;
    Bergs, Thomas
    Highly precise infrared lenses are used in a broad range of optical systems such as night visions, thermal imaging or gas sensing. As most infrared materials (e.g. Germanium, Chalcogenide glass) suffer from high Fresnel reflection losses, the use of anti-reflective coatings is state of the art to overcome this issue. An alternative approach is the implementation of anti-reflective microstructures into molded infrared lenses. This shortens the process chain and enables many advantages for example regarding the monolithic optics design. Precision Glass Molding (PGM), a replicative manufacturing technology, allows the macroscopic lens molding and the replication of surface microstructures to be carried out simultaneously. While PGM is an established process for manufacturing glass optics in general, there is a lack of knowledge regarding the replication of microstructures. This leads to the necessity to further investigate the PGM process chain for molding microstructures. The current paper addresses the process chain of manufacturing anti-reflective optics by precision glass molding. Process simulations are presented by a multiscale approach. In order to prevent wear, a suitable anti-adhesive coating system for molding tools with regard to the special requirements of microstructured surfaces is introduced. The results of the molding experiments highlight the importance of a multiscale simulation approach and demonstrate the stability of the anti-reflective microstructure.
  • Publication
    Replicative manufacturing of glass optics with functional microstructures
    ( 2019)
    Rojacher, Cornelia
    ;
    Grunwald, Tim
    ;
    Bergs, Thomas
    Microstructuring of glass optics enables a large variety of benefits for miscellaneous fields of application. From an enhancement of the performance of optical systems to the haptic improvement of coverglasses the advantages of structured glass are obvious. Especially in the field of high-precision optics, microstructured optical surfaces can carry out important functions, such as beam shaping in laser systems or the correction of dispersive color alterations. Besides enhancements regarding optics of the visible light spectrum, microstructures can compensate disadvantages of infrared(IR)-transmissive lenses such as chalcogenide glasses. As these optics suffer high transmission losses due to their high refractive index the integration of an anti-reflective (AR) function is necessary. Moth-eye-structures are a promising way to avoid the currently used AR-coatings. So far, microstructures are brought into the lens surface by lithography mainly. The therefore additional processing step follows the previous shaping. An efficient production of the structured components is the key to success for applications aside science and research. The technology precision glass molding (PGM) is able to combine the contradicting aspects of high precision and high volume production. PGM is a replicative manufacturing method that allows the macroscopic molding and the manufacturing of microscopic structures to be carried out simultaneously. Based on a representative PGM process chain, the paper at hand describes differences, challenges and current research results regarding molding microstructures.