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Klocke F.,Fraunhofer Institute for Production Technology | Klocke F.,Fraunhofer Project Center for Coatings in Manufacturing | Dambon O.,Fraunhofer Institute for Production Technology | Georgiadis K.,Fraunhofer Institute for Production Technology | Georgiadis K.,Fraunhofer Project Center for Coatings in Manufacturing
Key Engineering Materials | Year: 2010

The complexity of optical components increases steadily in recent years, while their dimension decrease. This situation makes the production of state of the art optical components by grinding and polishing very difficult and expensive. However, the technology of precision glass molding can be used to replace these traditional manufacturing methods by a single step replicative process. To achieve economies of scale with precision glass molding, a long molding tool lifetime is necessary. This can only be realized by applying protective PVD coatings on the molding tool surfaces. Well known thin hard coatings like TiAlN or CrN, as well as noble metal coatings are possible candidates. However, practical testing of carious coating-glass combinations in precision glass molding machines is not feasible due to long process times that make such testing very expensive and time consuming. In this work, these coatings are compared with each other and in combination with various glass types by performing oxidation and contact angle tests. The results of these tests are compared to the results of practical tests, in order to determine to which extent such model tests can replace practical testing. © (2010) Trans Tech Publications. Source


Georgiadis K.,Fraunhofer Institute for Production Technology | Georgiadis K.,Fraunhofer Project Center for Coatings in Manufacturing | Bulla B.,Fraunhofer Institute for Production Technology | Hollstegge D.,Fraunhofer Institute for Production Technology | And 3 more authors.
Proceedings of the 11th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2011 | Year: 2011

The demand for complex-shaped optical components is rising rapidly, driven by their significant advantages over traditional optics. A great example are lenses that combine aspherical surfaces and diffraction gratings. These can eliminate spherical as well as chromatic aberrations in imaging optics and can therefore replace multi-lens optical systems. Although glass aspheric lenses or lenses with diffraction gratings can be manufactured by various production technologies, the production of glass lenses that combine both was not possible until now. In this paper, the development of a production method of such lenses using precision glass moulding is presented. Source


Klocke F.,Fraunhofer Institute for Production Technology | Klocke F.,Fraunhofer Project Center for Coatings in Manufacturing | Georgiadis K.,Fraunhofer Institute for Production Technology | Georgiadis K.,Fraunhofer Project Center for Coatings in Manufacturing | And 7 more authors.
Optical Engineering | Year: 2012

Precision glass molding is the technology of choice for the production of complex-shaped optical components. Protective coatings can significantly extend the lifetime of the molding tools, but the coating properties have to be exactly customized for individual application conditions. The current biggest challenge is to ensure the reliability of newly developed coatings without resorting to extensive and expensive practical testing. However, the usual coating qualification methods either cannot be used or don't provide meaningful results. In this work a new three-tier, application-specific methodology for the qualification such coatings is presented. First, the basic characterization of coating properties is discussed, taking into account the specific characteristics of the coatings used for precision glass molding tools. In the second step, application-specific testing methods are devised, based on the analysis of the loads during glass molding. Finally, a new machine for testing the lifetime of the coated molding tools is proposed. Three case studies are presented where nanoscratch, nanoimpact and glass contact tests are performed with Pt-Ir, TiAlN, and CrAlN-coated samples in combination with various glass types, showcasing the usefulness of the proposed three-tier methodology. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Klocke F.,Fraunhofer Institute for Production Technology | Klocke F.,Fraunhofer Project Center for Coatings in Manufacturing | Georgiadis K.,Fraunhofer Institute for Production Technology | Georgiadis K.,Fraunhofer Project Center for Coatings in Manufacturing | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Precision glass molding is the technology of choice for the production of complex-shaped optical components. Protective coatings can significantly extend the lifetime of the molding tools, but the coating properties have to be exactly customized for the individual application conditions, or else an improvement in the tool performance cannot be guaranteed. The currently biggest challenge is to ensure the reliability of newly developed coatings without resorting to extensive and expensive practical testing. However, the usual coating qualification methods either cannot be used or don't provide meaningful results. In this work a new three-tier, application-specific methodology for the qualification such coatings is presented. © 2011 SPIE. Source

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