Coating stress analysis and compensation for iridium-based x-ray mirrors

Probst, Anne-Catherine; Bégou, Thomas; Döhring, Thorsten; Zeising, Sebastian; Stollenwerk, Manfred; Stadtmüller, Johannes; Emmerich, Florian; Lumeau, Julien

doi:10.1364/ao.57.008775

Cited by 17 publications

(10 citation statements)

References 15 publications

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“…The application of C/Ni/Pt trilayer coatings in a telescope with a higher resolution will require decreasing the internal stress, what can be achieved through the use of stress relaxation methods. 33,34 Thermal stability is one of the more important parameters of a reflective coating. 35 The C/Ni/Pt trilayer sample was annealed in vacuum for 1 h at a temperature of 200°C.…”

Section: Resultsmentioning

confidence: 99%

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

Yang

Huang

Кожевников

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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Effective area is one of the most important parameters of x-ray telescopes. It can be increased by enlarging the entrance aperture or maximizing the reflectivity through the proper designing and optimization of the reflecting coating. A method to increase the reflectivity of grazing incidence x-ray mirrors in the 0.5-to 8-keV energy region is analyzed. The idea consists in the use of a trilayer reflecting coating instead of single-layer one (e.g., C/Ni/Pt mirror instead of Pt one). Deposition of low-absorbing medium-Z and low-Z layers onto the top of strongly absorbing high-Z material results in essential increase in the reflectivity while keeping the same width of the reflectivity plateau. In particular, C/Ni/Pt trilayer mirror demonstrates enhancement of the double reflection coefficient by a factor achieving 1.5 to 3.5 compared to that of Pt-coated mirror. The effective area of a telescope is also considerably increased. The experimental results are in a very good agreement with the theoretical predictions. In addition, the C/Ni/Pt trilayer mirror exhibits a reasonable thermal stability and a relatively low compressive stress of about −550 MPa. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Resultsmentioning

confidence: 99%

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

Yang

Huang

Кожевников

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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“…Silicon plates provided by the company Cosine, representative of the substrates that will be used for the fabrication of ATHENA's optics, have been coated at two facilities; the DC magnetron sputtering chamber at Smithsonian Astrophysical Observatory (SAO) and the DC magnetron sputtering chamber at Aschaffenburg University (THAB). The two facilities differ for the different control of minimal thickness and for the different optimization of the process for these coatings, which are routinely manufactured in both facilities [21][22][23][24][25][26][27][28][29] , which also have developed methods to control stress in this kind of films [24][25] . The SAO facility has a finer control of the deposited thickness and can produce nanometric or subnanometric thickness films made of sputtered metals layers.…”

Section: Coatings and Overcoatings On Silicon Substrates Deposition And Characterization Of Metallic Layersmentioning

confidence: 99%

Development of low-density coatings for soft x-ray reflectivity enhancement for ATHENA and other missions

Cotroneo

Bruni

Döhring

et al. 2021

International Conference on Space Optics — ICSO 2020

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Metallic coatings made of precious metals (e.g. Ir, Pt or Au) with high atomic number Z have been traditionally employed at grazing incidence for X-rays reflection and focalization. These materials offer a range of reflection extended to higher energies, but also present a series of absorption edges, which limit the reflectivity in the 2-4 keV band and below.Therefore the search for alternative coatings, able to improve the reflection in the soft energy range, is particularly relevant for the development of future telescopes, like ATHENA (ESA), Lynx (NASA) and eXTP (CAS).Low-Z overcoatings (e.g. carbon or B4C), applied on top of the high-Z metallic layer, can enhance the reflectivity in the softer band (mainly below 2 keV), but conventional deposition methods for these materials are not easily compatible with some of the mainstream technologies for mirror fabrication (notably, the silicon pore optics that will be used for the ATHENA X-ray mission which is being implemented by ESA).In this work we discuss novel solutions (carbon-like overcoatings realized by dip coating or vapor phase deposition), which can be particularly convenient for the application to ATHENA and to future telescopes.

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“…High-energy astrophysics realized by focusing X-ray telescopes currently ranges from about 0.2 keV to 80 keV. [1][2][3][4][5] The upper range of the energy band is reached by the Nuclear Spectroscopic Telescope Array (NuSTAR). The High-Energy X-ray Probe (HEX-P) is a X-ray mission concept submitted to the 2020 Decadal Survey, that will extend the reach of broadband X-ray observations to 200 keV 6 .…”

Section: Introductionmentioning

confidence: 99%

Optimization of multilayer coatings for future high-energy focusing telescopes

Gellert¹,

Massahi²,

Ferreira³

et al. 2022

Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray

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Nanometer-thin multilayer coatings can enable high performance of focusing X-ray telescopes to energies up to 200 keV and beyond. In this paper we discuss the multilayer parameters and their limitations necessary for the reflection of hard X-ray photons. We present several multilayer coating designs that are optimized with a Differential Evolution algorithm to perform a stochastic global search of the multi-parametric model space. The coating designs are based on the new specifications of the HEX-P mission geometry, optimizing within the energy range 60 keV -200 keV. We compare the simulated reflectivity spectra of Si/Ni, Si/Pt and Si/W, at different incident angles. We find the effective upper limit of bilayers in the multilayer stack, beyond which reflectivity will not be increased. We discuss a hybrid multilayer coating design, consisting of either a Si/Pt or Si/W multilayer with a top Si/Ni multilayer.

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Coating stress analysis and compensation for iridium-based x-ray mirrors

Cited by 17 publications

References 15 publications

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

Development of low-density coatings for soft x-ray reflectivity enhancement for ATHENA and other missions

Optimization of multilayer coatings for future high-energy focusing telescopes

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