The eROSITA x-ray baffle

Friedrich, Péter; Rohé, Christian; Gaida, Roland; Hartwig, Johannes; Soller, F.; Bräuninger, H.; Budau, Bernd; Burkert, Wolfgang; Burwitz, V.; Eder, Josef; Hartner, Gisela; Menz, Benedikt; Predehl, P.

doi:10.1117/12.2056335

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…After the acceptance tests the X-ray baffle was mated to the mirror assembly under optical control. For FM1 the impact on the performance of the mirror module was assessed and showed that the optical performance was not impacted and that the single reflections reduction for far off-axis X-ray sources was demonstrated to work as predicted [2]. Figure 3 Here a comparison of the in-focus and 400 µm intra-focal on-axis and survey PSFs for all 8 mirror modules is shown.…”

Section: Acceptance Testsmentioning

confidence: 97%

“…All these missions use nickel electroformed shells replicated from super polished mandrels and mounted under optical control into mirror structures by Media Lario Technologies (MLT). To round off the mirror design each mirror module is equipped with an elaborate X-ray baffle [2] to reduce the stray light from far off axis bright X-ray sources.…”

Section: Introductionmentioning

confidence: 99%

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The calibration and testing of the eROSITA X-ray mirror assemblies

et al. 2014

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In 2016 the X-ray Survey Telescope eROSITA, designed and built at MPE, will be launched on the Russian SpektrRoentgen-Gamma Mission. A compact bundle of 7 co-aligned mirror modules with a focal length of 1600 mm and 54 nested mirror shells each form the X-ray telescope. The sensitivity of the telescope in terms of effective area, field-ofview (61'), and angular resolution (~16" HEW on-axis) will yield a high grasp of about 1000 cm 2 deg 2 around 1 keV with an average angular resolution of ~26" HEW over the field-of-view (30" including optical and spacecraft error contributions). All flight mirror modules including a flight spare have been completed and passed their acceptance tests in December 2013. The mirror modules now have all been mated with their corresponding X-ray baffles to form mirror assemblies and the passed rigorous environmental vibration and thermal cycling tests. Here we report on the results of these measurements and on the calibration measurements planned for the completed flight mirror assemblies.

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Section: Acceptance Testsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

The calibration and testing of the eROSITA X-ray mirror assemblies

et al. 2014

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“…For example, a sieve plate was employed for XMM-Newton 35 and a precollimator was utilized for eROSITA. 36 The x-ray baffle suppresses the stray light but simultaneously produces additional vignetting. By means of ray-tracing, the stray light problem and potential solutions will be analyzed, obtaining a trade-off between effective stray light reduction and vignetting avoidance.…”

Section: Stray Lightmentioning

confidence: 99%

Design of conical Wolter-I geometry with sectioned secondary mirrors for x-ray telescopes

Liao

Shen

Wang

2019

J. Astron. Telesc. Instrum. Syst.

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Conical Wolter-I geometry is employed for many x-ray telescopes to lower their cost and fabrication difficulty at the expense of angular resolution. Owing to the conic error, the angular resolution of conical Wolter-I geometry is much worse than that of Wolter-I geometry, especially for the telescopes with large diameter. We optimized the conical Wolter-I geometry to significantly improve the angular resolution. We designed a conical Wolter-I geometry with sectioned secondary mirrors. Based on the normal conical Wolter-I geometry, we divided the secondary mirror into two equal sections along the optical axis. In this case, the collecting area was reduced by 5% because of the interval between the two sections. Meanwhile, the conic error was reduced by about 50%, indicating a great improvement in angular resolution. Regarding our improvement in the thermal slumping technique, it is feasible to fabricate sectioned mirrors, thus improving the angular resolution by 50% at the cost of a 5%-reduction in collecting area. In addition, a hybrid geometry, comprising the sectioned and nonsectioned geometries, is proposed as an alternative for x-ray telescopes with a large amount of nested shells, to obtain both a large collecting area and decent angular resolution.

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“…Should the EA of stray light seriously limit the sensitivity of an X-ray telescope, a pre-collimator (or baffle) can be adopted as a countermeasure to stop most stray light, without obstructing the focused flux, at it was done, e.g., for eROSITA. 10 For ATHENA, the dense obstruction of ribs will certainly help mitigate this issue, but since ATHENA was designed to be the most sensitive X-ray telescope ever, stray light cannot certainly be neglected a priori.…”

Section: Introductionmentioning

confidence: 99%

A fully-analytical treatment of stray light in silicon pore optics for the Athena x-ray telescope

Spiga¹,

Sironi

Ferreira

et al. 2022

Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray

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Just like in any other X-ray telescope, stray light is expected to be a potential issue for the ATHENA X-ray telescope, with a significant impact on the scientific goals. The most prominent cause of stray light in Wolter-I type optics is represented by rays that did not undergo double reflection and were reflected only singly, on either the parabolic or the hyperbolic segment. A minor contribution may, additionally, arise from the diffuse reflections on the backside of the pore membrane and ribs. Aiming at determining whether the resulting background is tolerable or not, the effective area for stray light has to be calculated. While ray-tracing is a standard and wellassessed tool to perform this task, it usually takes a considerable amount of computation time to trace a number of rays sufficient to reach an appropriate statistical significance, because only a minority of stray rays emerge unobstructed from the mirror assembly. In contrast, approaching the stray light from the analytical viewpoint takes several upsides: it is faster than ray-tracing, does not suffer from any statistical uncertainties, and allows one to better understand the role of the parameters at play. The only approximation involved is the double cone geometry, which however is largely applicable to ATHENA as far as the sole effective area is concerned. In this paper, we show how the analytical approach can be successfully adopted to model the stray light effective area in the ATHENA mirror assembly, as a function of the X-ray energy and of the source off-axis angle.

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The eROSITA x-ray baffle

Cited by 9 publications

References 2 publications

The calibration and testing of the eROSITA X-ray mirror assemblies

The calibration and testing of the eROSITA X-ray mirror assemblies

Design of conical Wolter-I geometry with sectioned secondary mirrors for x-ray telescopes

A fully-analytical treatment of stray light in silicon pore optics for the Athena x-ray telescope

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