NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH TeisnachBeitrag (Sammelband oder Tagungsband)
Sebastian Sitzberger, Johannes Liebl, Jakob Reitberger, Rolf Rascher
Zero-point clamping systems in optical production
Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA
2019
DOI: 10.1117/12.2528774
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Zero point clamping systems are an integral part of the manufacturing industry. They have only yet to find their way into the optical industry. This article compares the hydraulic expansion holder, a clamping system currently used in the optical industry with a zero-point clamping system. The achievable accuracies of both systems are compared over several measurement series. In addition, the process capability evaluation is used for the comparison. Finally, the results are summarized to provide every researcher and practitioner with a foundation for assessing whether zero point clamping systems meet the requirements for the use in optical manufacturing.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH TeisnachBeitrag (Sammelband oder Tagungsband)
Jessica Stelzl, Christine Wünsche, S. Höfer
Processing of a new nonlinear optical crystal for continuous wave UV-laser applications
Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA
2019
DOI: 10.1117/12.2528140
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Lasers have been known for a long time and are used in a wide variety of fields such as industrial and material processing or measuring and control technology. A new application is being tested which aims to use continuous wave UV-lasers in metrology. For this application a nonlinear optical crystal is needed. Its processing is developed in a two-year project at the Institute for Precision Manufacturing and High-Frequency Technology of Deggendorf Institute of Technology. The crucial factor for the full optical performance in the UV range is the low roughness of the crystal surface, as it is installed between two prisms and the contactability between them should be ensured. In China, a nonlinear crystal that meets the requirements has already been designed and a production process for the raw crystal has been established. However, since the production of optically homogenous crystals has proven to be difficult, the availability of such is very limited. For this reason, a reference material with similar hardness and material behaviour is used in the process development in order not to be limited in the number of trials. It is important to be able to transfer the results from the reference material in an analogous way to the original crystal. One challenge of the project lies in the crystal thickness, since only a maximum thickness of three millimetres can be achieved for the purest form of the crystal required in the application. Therefore, it is important to handle the material sparingly during the process. In addition, the small dimensions of about ten to five millimetres and the brittleness of the material pose a problem. The goal of the project will be to develop a process that can circumvent all these problems so that small roughness of the crystal can be achieved by precision polishing.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH TeisnachBeitrag (Sammelband oder Tagungsband)
Emilio Zambrano, Christine Wünsche, S. Mechold, S. Herr
Cleaning effects in optical layers: error characteristics and analysis methods
Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA
2019
DOI: 10.1117/12.2527974
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In the course of the ever-increasing demand of high-performance optical components, dielectric coating processes are the key technology for the refinement of optics, ensuring their functionality. These optics are based on optical interference coatings, which are formed by a layer stack of alternating transparent single layers of high and low refractive index material. Assuming that turbidity as well as defects embedded in coatings are considered as a primary factor limiting the quality of optical coatings, the level of cleaning the substrates before coating has to be extremely high. Particular importance is attached to the interface between the layer stack and the substrate, especially to the interaction during the transition from the glass surface to the coating during the manufacturing process. This interaction is assumed to be caused by polishing, by corrosion during storage time or by effects during cleaning of the substrate before coating. Thus, it is necessary to characterize each type of defect and to define which technique is adequate to analyze each one of them efficiently. The project aims to raise the awareness and knowledge in terms of what happens during the coating process and, in particular, to understand the physical processes at the substrate during the manufacturing process. After analyzing the material flow, first focus was set on the cleaning procedure. It is assumed that one of the main influences on defects in the interface is the chemical cleaning. Chemical reactions on the surface of the glass substrate may occur due to additional effects of external components and elevated temperature in the washing basins.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH TeisnachBeitrag (Sammelband oder Tagungsband)
Simon Killinger, Johannes Liebl, Rolf Rascher
Mid-spatial frequency errors in feed direction occurring in ADAPT polishing
Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA
2019
DOI: 10.1117/12.2528114
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Previous work shows the effectiveness of computer controlled polishing (CCP) with the ADAPT tool by Satisloh for correcting form errors in optics manufacturing. This method however has a risk of producing residual errors in the range of mid spatial frequency errors (MSFE). In order to prevent these errors the residual in feed direction is investigated as well as the behavior at different parameters.
DigitalNachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH TeisnachBeitrag (Sammelband oder Tagungsband)
Johannes Jakob, R. Sammer, Franz Xaver Röhrl, Stefan Zorn, Werner Bogner
WR12 to planar transmission line transition on organic substrate
Proceedings of the 49th European Microwave Conference (EuMC)/European Microwave Week (EuMW) 2019 (September 29-October 4, 2019; Paris, France)
2019
DOI: 10.23919/EuMC.2019.8910843
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Transitions for planar transmission lines on printed circuit boards to rectangular waveguide are challenging to design and manufacture. This paper introduces two transitions, the first one is a broadband transition from WR12 (60-90 GHz) waveguide to a stripline (SL) and the second is a narrowband transition to a grounded coplanar waveguide (GCPW). The focus at the first transition is based on the fact that signals can be transmitted in the complete E-Band. In the process, many manufacturing possibilities were exploited. For the second transition, the focus was on manufacturability in order to achieve the most cost effective transition possible. Design, simulated and measured results will be presented.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ SpiegelauZeitschriftenartikel
M. König, Günther Ruhl, A. Gahoi, S. Wittman, T. Preis, J.-M. Batke, I. Costina, M. Lemme
Accurate Graphene-Metal Junction Characterization
IEEE Journal of the Electron Devices Society (J-EDS), vol. 7, pp. 219-226
2019
DOI: 10.1109/JEDS.2019.2891516
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A reliable method is proposed for measuring specific contact resistivity (p C ) for graphenemetal contacts, which is based on a contact end resistance measurement. We investigate the proposed method with simulations and confirm that the sheet resistance under the metal contact (R SK ) plays an important role, as it influences the potential barrier at the graphene-metal junction. Two different complementary metal-oxide-semiconductor-compatible aluminum-based contacts are investigated to demonstrate the importance of the sheet resistance under the metal contact: the difference in R SK arises from the formation of insulating aluminum oxide (Al 2 O 3 ) and aluminum carbide (Al 4 C 3 ) interfacial layers, which depends on the graphene pretreatment and process conditions. Auger electron spectroscopy and X-ray photoelectron spectroscopy support electrical data. The method allows direct measurements of contact parameters with one contact pair and enables small test structures. It is further more reliable than the conventional transfer length method when the sheet resistance of the material under the contact is large. The proposed method is thus ideal for geometrically small contacts where it minimizes measurement errors and it can be applied in particular to study emerging devices and materials.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenZeitschriftenartikel
Thomas Stirner, Ali Hamid, Jizhong Sun, Hongyu Zhang, Arvind Jadon
Molecular dynamics simulations of helium clustering and bubble growth under tungsten surfaces
Computational Materials Science, vol. 163, no. June, pp. 141-147
2019
DOI: 10.1016/j.commatsci.2019.03.008
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We study the surface response of W to helium bombardment using molecular dynamics simulations. Simulations have been performed for incident helium of energy 80 eV and surface temperature 2100 K. The saturation of He retention has been observed to be high, a result of the bubbles trapping helium atoms and preventing them from diffusing to the surface and further back into the plasma. On the other hand, we have observe near-surface “cluster rupture” leading to the expulsion of helium atoms towards the vacuum. We have found that bubbles typically grow in a relatively narrow band of He/V ratios (1–3). Besides, it was observed that tungsten atoms migrated from the top surface into the bulk. The coalescence of helium bubbles has also been observed.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenZeitschriftenartikel
David Scholz, Thomas Stirner
Convergence of surface energy calculations for various methods: (0 0 1) hematite as benchmark
Journal of Physics: Condensed Matter, vol. 31, no. 19
2019
DOI: 10.1088/1361-648X/ab069d
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Different methods for calculating the surface energy from ab initio simulations are applied to the relaxed (0 0 1) surface of the metal oxide hematite (α-Fe2O3). The simulations are carried out with a rather moderate k-point grid with shrinking factors of (6 6 6) for all bulk and (6 6) for all slab simulations. Very good convergence is obtained if a linear fit of the slab energies with respect to the number of layers in the slab is performed. In comparison to the other methods employed, this procedure is ultimately the most accurate and reliable method for extracting convergent surface energies from (0 0 1) hematite slabs. Additionally, we propose a way to determine the least possible starting point for calculating the surface energy by the linear-fit method. Furthermore, we find the Boettger method to perform nearly equally well, if the bulk energy is extracted from the energy difference per layer between the slabs with 12 and 18 layers thickness. Both methods give a surface energy of 2.43 J m-2 with a deviation of less than ±0.005 J m-2. The standard approach, which uses a separate bulk simulation, instead shows a significant linear divergence with increasing number of layers in the slab. We also carried out bulk simulations with a surface-oriented bulk unit cell, but found it in our case not to improve the convergence of the standard approach.
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