@inproceedings{ProbstDoehringStollenwerketal.2017, author = {Probst, Anne-Catherine and D{\"o}hring, Thorsten and Stollenwerk, Manfred and Mingwu, Wen and Proserpio, Laura}, title = {Iridium coatings for space based x-ray optics}, series = {Proceedings of SPIE}, volume = {2017}, booktitle = {Proceedings of SPIE}, number = {10562}, editor = {Cugny, Bruno and Karafolas, Nikos and Sodnik, Zoran}, doi = {10.1117/12.2296167}, pages = {105621E-01 -- 105621E-09}, year = {2017}, abstract = {Future investigations of astronomical X-ray sources require light weight telescope systems with large collecting areas and good angular resolution. The Wolter I type telescope design offers a suitable possibility for obtaining performant X-ray mirrors with high collecting areas. The technology based on replicated slumped glass optics using thin glasses thereby provides the opportunity to fulfil the light weight and mass production requirements. In NASA's telescope NuSTAR this technology has been proven as advantageous compared to previous systems. Coating thin glasses with iridium, gold or platinum enhances the reflectivity of X-ray mirrors.}, subject = {Iridium}, language = {en} } @inproceedings{DoehringProbstStollenwerketal.2017, author = {D{\"o}hring, Thorsten and Probst, Anne-Catherine and Stollenwerk, Manfred and Emmerich, Florian and Stehl{\´i}kov{\´a}, Veronika and Inneman, Adolf}, title = {Prototyping iridium coated mirrors for X-ray astronomy}, series = {Proceedings of the International Society for Optics and Photonics}, volume = {2017}, booktitle = {Proceedings of the International Society for Optics and Photonics}, number = {10235}, editor = {Hudec, Ren{\´e} and Pina, Ladislav}, publisher = {SPIE International Society for Optics and Photonics}, address = {Bellingham WA}, organization = {Hochschule Aschaffenburg}, doi = {10.1117/12.2265931}, pages = {1023504-1 -- 1023504-8}, year = {2017}, abstract = {X-ray astronomy uses space-based telescopes to overcome the disturbing absorption of the Earth´s atmosphere. The telescope mirrors are operating at grazing incidence angles and are coated with thin metal films of high-Z materials to get sufficient reflectivity for the high-energy radiation to be observed. In addition the optical payload needs to be light-weighted for launcher mass constrains. Within the project JEUMICO, an acronym for "Joint European Mirror Competence", the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague started a collaboration to develop mirrors for X-ray telescopes. The X-ray telescopes currently developed within this Bavarian- Czech project are of Lobster eye type optical design. Corresponding mirror segments use substrates of flat silicon wafers which are coated with thin iridium films, as this material is promising high reflectivity in the X-ray range of interest. The deposition of the iridium films is based on a magnetron sputtering process. Sputtering with different parameters, especially by variation of the argon gas pressure, leads to iridium films with different properties. In addition to investigations of the uncoated mirror substrates the achieved surface roughness has been studied. Occasional delamination of the iridium films due to high stress levels is prevented by chromium sublayers. Thereby the sputtering parameters are optimized in the context of the expected reflectivity of the coated X-ray mirrors. In near future measurements of the assembled mirror modules optical performances are planned at an X-ray test facility.}, subject = {Iridium}, language = {en} } @inproceedings{StehlikovaUrbanNentvichetal.2017, author = {Stehlikova, Veronika and Urban, Martin and Nentvich, Ondrej and Inneman, Adolf and D{\"o}hring, Thorsten and Probst, Anne-Catherine}, title = {Study of lobster eye optics with iridium coated X-ray mirrors for a rocket experiment}, series = {Proceedings of the International Society for Optics and Photonics (SPIE)}, volume = {2017}, booktitle = {Proceedings of the International Society for Optics and Photonics (SPIE)}, number = {10235}, editor = {Hudec, Rene}, publisher = {SPIE International Society for Optics and Photonics}, address = {Bellingham WA}, organization = {Czech Technical University in Prague}, doi = {10.1117/12.2265769}, pages = {1023505-1 -- 1023505-7}, year = {2017}, abstract = {In the field of astronomical X-ray telescopes, different types of optics based on grazing incidence mirrors can be used. This contribution describes the special design of a lobster-eye optics in Schmidt's arrangement, which uses dual reflection to increase the collecting area. The individual mirrors of this wide-field telescope are made of at silicon wafers coated with reflecting iridium layers. This iridium coatings have some advantages compared to more common gold layers as is shown in corresponding simulations. The iridium coating process for the X-ray mirrors was developed within a cooperation of the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague. Different mirror parameters essential for a proper function of the X-ray optics, like the surface microroughness and the problematic of a good adhesion quality of the coatings were studied. After integration of the individual mirrors into the final lobster-eye optics and the corresponding space qualification testing it is planned to fly the telescope in a recently proposed NASA rocket experiment.}, subject = {Iridium}, language = {en} } @inproceedings{ProbstDoehringZeisingetal.2017, author = {Probst, Anne-Catherine and D{\"o}hring, Thorsten and Zeising, Sebastian and Salmaso, Bianca and Stollenwerk, Manfred and Proserpio, Laura}, title = {Challenges in metrology of mirror segments for X-ray telescopes}, series = {Proceedings of the 8th High Level Expert Meeting Asphere Metrology}, volume = {2017}, booktitle = {Proceedings of the 8th High Level Expert Meeting Asphere Metrology}, number = {8}, publisher = {UTOB e.V.}, address = {Braunschweig}, organization = {Hochschule Aschaffenburg}, pages = {4}, year = {2017}, abstract = {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.}, subject = {Spiegelteleskop}, language = {en} } @inproceedings{DoehringProbstStehlikovaetal.2017, author = {D{\"o}hring, Thorsten and Probst, Anne-Catherine and Stehlikova, Veronika and Skala, Petr and Inneman, Adolf and Hudec, Rene}, title = {JEUMICO - Bayerisch-tschechische Kooperation zur Entwicklung von R{\"o}ntgenteleskopen}, series = {DGaO-Proceedings}, volume = {2017}, booktitle = {DGaO-Proceedings}, number = {2017}, publisher = {DGaO}, organization = {Hochschule Aschaffenburg}, issn = {1614-8436}, pages = {2}, year = {2017}, abstract = {Das Projekt JEUMICO wird vom Projekttr{\"a}ger BAYHOST im Rahmen eines Programms f{\"u}r bilaterale wissenschaftliche Projekte zwischen Tschechien und Bayern gef{\"o}rdert. Inhaltlich werden von der Hochschule Aschaffenburg und der Technischen Universit{\"a}t Prag hier gemeinsam R{\"o}ntgenoptiken f{\"u}r ein geplantes astronomisches Experiment an Bord einer NASA-H{\"o}henrakete entwickelt.}, subject = {R{\"o}ntgenstrahlung}, language = {de} } @article{ProbstBegouDoehringetal.2018, author = {Probst, Anne-Catherine and Begou, Thomas and D{\"o}hring, Thorsten and Zeising, Sebastian and Stollenwerk, Manfred and Stadtm{\"u}ller, Johannes and Emmerich, Florian and Lumeau, Julien}, title = {Coating stress analysis and compensation for iridium-based x-ray mirrors}, series = {Applied Optics}, volume = {2018}, journal = {Applied Optics}, number = {57 (29)}, editor = {Publishing OSA,}, pages = {8775 -- 8779}, year = {2018}, abstract = {Iridium-based coatings for mirrors of x-ray telescopes are studied. In particular, stress-induced deformation is characterized and shown to be compressive and equal to -1786  MPa. Two methods for stress compensation are then studied. One relies on the deposition of silica on the back surface of the substrate and a second one relies on the deposition of a chromium sublayer. Advantages and drawbacks of each of these techniques are presented.}, subject = {R{\"o}ntgenteleskop}, language = {en} }