TY - CHAP A1 - Probst, Anne-Catherine A1 - Döhring, Thorsten A1 - Zeising, Sebastian A1 - Salmaso, Bianca A1 - Stollenwerk, Manfred A1 - Proserpio, Laura T1 - Challenges in metrology of mirror segments for X-ray telescopes T2 - Proceedings of the 8th High Level Expert Meeting Asphere Metrology N2 - High angular resolution, large collecting area and reduced weight per unit area are required for astronomical X-ray telescopes of the next generation observatories. New technologies for processing X-ray mirrors are under development to fulfill these needs. One option is to realize a Wolter I type telescope constituted of several hundred nested thin and light-weight X-ray mirror segments. The individual mirror segments need to be coated with an about 100 nm thick film of a high-reflective material to enhance the reflectivity for X-rays. Thereby an accurate shape metrology of the segments is necessary to predict the angular resolution of the astronomical telescope as well as to control the development process of X-ray mirrors. We present the challenges in shape measurements of thin glasses used to control the coating process and first experimental results about the repeatability of the measurements. KW - metrology KW - mirror KW - telescope KW - Spiegelteleskop Y1 - 2017 UR - http://www.upob.de/index.php?option=com_phocadownload&view=category&download=198:8th-high-level-expert-meeting-2017-detailed-programme&id=21:upob-high-level-expert-meetings&Itemid=70 VL - 2017 IS - 8 PB - UTOB e.V. CY - Braunschweig ER - TY - CHAP A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Schmitt, Paul A1 - Szeghalmi, Andrea T1 - Umweltbeständige Spiegelbeschichtungen aus Iridium für den infraroten Spektralbereich T2 - DGaO Proceedings N2 - Das Edelmetall Iridium ist hart; extrem dicht; thermisch, mechanisch und chemisch stabil; weist eine hohe Reflektivität im mittleren und fernen Infrarot auf und hat eine hohe Beständigkeit gegenüber Umwelteinflüssen - auch ohne weitere Schutzschichten. Es wurden die komplexen Brechungsindizes für Iridium-Spiegelbeschichtungen bestimmt, welche vorhandene Literaturwerte ergänzen. KW - Iridium KW - Spiegel KW - Reflektivität KW - Brechungsindex KW - ALD KW - Iridium KW - Beschichtung Y1 - 2022 UR - https://www.dgao-proceedings.de/download/123/123_p13.pdf SN - 1614-8436 VL - 2022 IS - 123 SP - 1 EP - 2 PB - DGaO ER - TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI,AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - Sputter KW - ALD KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.1364/OME.447306 VL - 2022 IS - 12 / 2 SP - 545 EP - 559 ER - TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirrorcoatings for infrared applications: supplement JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - ALD KW - Sputter KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.6084/m9.figshare.17121509 VL - 2022 IS - 12/2 SP - 545 EP - 559 ER - TY - GEN A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Schmitt, Paul A1 - Szeghalmi, Adriana T1 - Umweltbeständige Spiegelbeschichtungen aus Iridium für den infraroten Spektralbereich N2 - Hochreflektierende Metallbeschichtungen sind essenziell für zahlreiche optische Elemente. Bewährte Spiegelbeschichtungen aus Silber und Gold bieten eine hohe und breitbandige Eigenreflexion im infraroten Spektralbereich, sind ohne geeignete Schutzschichten jedoch anfällig gegenüber Umwelteinflüssen und mechanischer Beanspruchung. Insbesondere im langwelligen Spektralbereich verringern die Absorptionsbanden dieser Schutzschichten teilweise die hohe Spiegelreflektivität wieder. Das Edelmetall Iridium (Ir) ist hart; extrem dicht; thermisch, mechanisch und chemisch stabil; weist eine ähnlich hohe Reflektivität im mittleren und fernen Infrarot, wie Silber und Gold, auf und hat zusätzlich eine hohe Beständigkeit gegenüber Umwelteinflüssen - auch ohne Schutzschichten. In diesem Beitrag werden die optischen und strukturellen Eigenschaften von Iridium-Spiegelbeschichtungen, welche mittels Atomlagenabscheidung (ALD) und DC-Magnetron-Sputtern hergestellt wurden, vorgestellt und miteinander verglichen. Die komplexen Brechungsindizes für ALD-erzeugte und gesputterte Iridium-Spiegelbeschichtungen wurden für Wellenlängen von 200 nm bis 20 μm bestimmt, welche nun bereits vorhandene Literaturwerte ergänzen. N2 - Poster KW - Iridium KW - Brechungsindex KW - infrarot KW - Spiegel KW - Beschichtung KW - Iridium KW - Beschichtung Y1 - 2022 SP - 1 EP - 1 PB - DGaO ER - TY - GEN A1 - Döhring, Thorsten A1 - Rödling, Claudius A1 - Kimmel, Kevin A1 - Zeising, Sebastian A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred A1 - Verma, Shruti A1 - Rees, Paul T1 - Optical characterization of reflective coatings for astronomical telescope mirrors T2 - DGaO Jahrestagung N2 - With ground based optical telescopes astronomers observe celestial objects over a wide spectral range. As usually three or even more reflections at telescope mirrors are involved, good reflection properties of the mirror coatings are important. The aluminum evaporation technique has been - and is still - the standard solution for the reflective coatings of large astronomical mirrors. Such coatings have excellent reflectivity in the ultraviolet and in the visible, but perform poorly in the infrared. Silver is the metal having highest reflectivity for wavelengths longward of 400 nm, but isn´t the best choice for reflectivity in the ultraviolet and for blue light. To avoid degradation by oxidation, durable silver coatings need to be protected by transmitting overcoating layers. In the presented study, different metallic coatings – including unusual ones like sputtered iridium - are characterized to identify a coating that is most suitable for the spectral range from ultraviolet to infrared. Experimental results are compared to simulations based on the complex refractive indices of these materials. Thereby dependence of incidence angle and polarization is also considered. N2 - Poster KW - mirror KW - coating KW - iridium KW - astronomy KW - telescope KW - Spiegelteleskop Y1 - 2021 UR - https://dgao.de/jahrestagung/ VL - 2021 SP - 1 EP - 1 ER - TY - CHAP A1 - Döhring, Thorsten A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred A1 - Cotroneo, Vincenzo A1 - Pareschi, Giovanni A1 - Gibertini, Eugenio A1 - Magagnin, Luca T1 - Low-density coatings for enhanced X-ray reflectivity of astronomical telescope mirrors T2 - DGaO Proceedings N2 - High reflectivity grazing incidence mirrors of astronomical X-ray telescopes are usually coated with thin layers of iridium, gold, or platinum. Due to a series of absorption edges, these noble metals have low reflectivity in the 2 - 4 keV band. We present the development of innovative material combinations using chromium and an additional layer of polydopamine for enhanced reflectivity X-ray coatings. KW - Dopamin KW - Iridium KW - mirror KW - coating KW - X-ray KW - Röntgenteleskop Y1 - 2021 UR - https://www.dgao-proceedings.de/download/122/122_p3.pdf SN - 1614-8436 VL - 2021 IS - 122 SP - 1 EP - 2 PB - DGaO ER - TY - CHAP A1 - Döhring, Thorsten A1 - Rödling, Claudius A1 - Kimmel, Kevin A1 - Zeising, Sebastian A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred A1 - Verma, Shruti A1 - Rees, Paul T1 - Optical characterization of reflective coatings for astronomical telescope mirrors T2 - DGaO Proceedings N2 - Aluminium evaporation is still the standard solution for reflective coatings of large astronomical mirrors. Silver and gold are also used in specific cases depending on the targeted wavelength. This study characterized different metallic coatings - including unusual ones like sputtered iridium - to identify the most suitable mirror coating for the spectral range from ultraviolet to infrared wavelengths. KW - Iridium KW - mirror KW - coating KW - reflectivity KW - telescope KW - Spiegelteleskop Y1 - 2021 UR - https://www.dgao-proceedings.de/download/122/122_p4.pdf SN - 1614-8436 VL - 2021 IS - 122 SP - 1 EP - 1 PB - DGaO ER - TY - GEN A1 - Döhring, Thorsten A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred A1 - Cotroneo, Vincenzo A1 - Pareschi, Giovanni A1 - Gibertini, Eugenio A1 - Magagnin, Luca T1 - Low-density coatings for enhanced X-ray reflectivity of astronomical telescope mirrors T2 - DGaO Jahrestagung N2 - X-ray telescopes usually operate in space and are quite different from astronomical telescopes for visible light. For normal angles of incidence, optical light is reflected on the mirror surface, whereas X-rays are either transmitted or absorbed. However, also high reflectivity X-rays mirrors are possible, when the incident rays direction is almost parallel to the mirror surface. Such grazing incidence mirrors are usually coated with thin layers of precious metals like iridium, gold or platinum, as this result in high X-ray reflectivity. These noble metals offer a wide range of reflection up to high photon energies, but, due to a series of absorption edges, have low reflectivity in the 2 - 4 keV band and below. This contribution presents the development of innovative material combinations based on thin layers of iridium and chromium, followed by an additional layer of carbon-based materials. We also discuss corresponding production methods (like dip coating) for enhanced reflectivity mirror coatings of future X-ray telescopes. N2 - Poster KW - X-ray KW - mirror KW - coating KW - iridium KW - satellite KW - Röntgenstrahlung KW - Spiegelteleskop Y1 - 2021 UR - https://dgao.de/jahrestagung/ VL - 2021 SP - 1 EP - 1 ER - TY - GEN A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Stadtmüller, Johannes A1 - Freudenmann, Dominic A1 - Röcke, Nicole T1 - Nanostructured iridium catalysts for effective hydrogen peroxide decomposition T2 - EuroNanoForum N2 - The EU intends to restrict the use of critical fuels in space propulsion systems. These propellants like hydrazine are chemically aggressive, toxic and carcinogenic. Space propulsion of the future should be environmentally friendly, inexpensive, and easy to handle. Aschaffenburg University and DLR are currently developing environmentally friendly technologies for future satellite engines. Thereby rocket-grade hydrogen peroxide, which is foreseen as a substitute, is converted to uncritical water vapour and oxygen by an exothermic catalytic reaction on nanostructured iridium layers. The resulting hot gases provide the required amount of thrust. The iridium catalyst layers are coated onto ceramic pellets, using RF magnetron sputtering technology. The catalytic functionality was tested afterwards at the chemical laboratories of DLR. First experimental results show a significantly higher catalytic activity for nanostructured iridium surfaces than for smoother crystalline layers. N2 - Poster KW - satellite KW - propulsion KW - catalyst KW - iridium KW - hydrogen peroxide KW - Iridium KW - Katalysator KW - Satellitentechnik Y1 - 2021 VL - 2021 ER -