M.Sc.

Rojacher, Cornelia

Filters

5 2
3 2
3 2
Reset filters

Settings
Now showing 1 - 5 of 5
  • Publication
    Development of a data structure for the description of nominal and measurement properties of optical elements
    (Fraunhofer IPT, 2022-03-08)
    Riediger, Max
    ;
    Hachgenei, Enno
    ;
    Rojacher, Cornelia
    ;
    Wortmann, Jannik
    Recent advances in the digitalization of production processes allow a thorough analysis of the different process parameters. Machine learning algorithms help to find the different dependencies of the production parameters by modelling the production processes especially when a large number of parameters is involved. The knowledge gained of the dependencies of the production parameters can be used to greatly improve the production quality. To harness the full potential of this approach, the different production processes along a value chain must be considered as a whole instead of modelling every process independently. Especially in the field of optics production with tight production tolerances, that are often at the edge of todays manufacturability and metrology, the approach of consid ering all production processes as a whole holds great potential. The evaluation of the production parameters of the whole value chain can help predict and improve the quality of the final product, using techniques such as tolerance matching or enabling adaptive changes in the process without compromising the quality of the final product.
  • Publication
    Digitized assembly of complex optical systems
    (Fraunhofer IPT, 2021)
    Tavakolian, Armin
    ;
    Hoeren, Maximilian
    ;
    Rojacher, Cornelia
    With this publication we would like to present the research approaches and results of the EverPro project in the context of precision assembly of optical systems. The digitalization concept for optics assembly should enable researchers at the Fraunhofer IPT and partners of ACOP to implement and integrate new assembly processes as well as prototype tools into a flexible machine platform faster in the future, and to capture all relevant data from pre-processes.
  • 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.
  • Publication
    Molded anti-reflective structures of chalcogenide glasses for infrared optics by precision glass molding
    ( 2019)
    Vu, Anh Tuan orcid-logo
    ;
    Rojacher, Cornelia
    ;
    Grunwald, Tim
    ;
    Bergs, Thomas
    Infrared (IR) optic holds a key element over a broad range of advanced optical systems such as thermal imaging, night visions or laser-based sensing. Most infrared optical materials like chalcogenide glasses, however, suffer great transmission losses due to their high refractive index. Therefore, antireflective (AR) surfaces are necessary to enhance the optical performance of the IR optics by suppressing undesirable reflection at the optical surfaces and thus increasing the transmission. The AR-coatings commonly used for IR lenses in the contemporary optic market are expensive and environmentally critical. Instead, Precision Glass Molding (PGM), a replicative manufacturing method for the production of highly precise glass optics, becomes a promising solution to fabricate the AR-nanostructures on the chalcogenide glasses in a cost-efficient manner. The PGM process development starts out a multiscale modeling of the molding process, by which the form accuracy of the molded glass lenses is predicted at macroscale while the replication of the AR-structure is visualized at nanoscale simulation. This simulation necessitates a newly developed thermal-mechanical constitutive model to represent thermo-viscoelastic behaviors of the chalcogenide glass. Experimental validations of the form accuracy and the replicated AR-structure of the molded lenses demonstrate essential benefits of the simulation model. This paper focuses on the process simulation as well as the subsequent steps of mold manufacturing and glass molding itself. The success of molding AR-structures by precision glass molding promisingly satisfies the increasing demands for the high volume production of inexpensive IR optical elements in today's optics and photonics markets.