Science requirements and optimization of the silicon pore optics design for the Athena mirror

Willingale, R.; Pareschi, G.; Christensen, Finn Erland; Herder, J. W. den; Ferreira, Desiree Della Monica; Jakobsen, Anders Clemen; Ackermann, Marcelo; Collon, M.; Bavdaz, Marcos

doi:10.1117/12.2055183

Cited by 20 publications

(23 citation statements)

References 6 publications

(6 reference statements)

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“…Another quantity of frequent use to denote the imaging properties is the half-energy width (HEW), that is, twice the median value of the PSF. Achieving optical systems with high angular resolution -for example, lower than 5 arcsec HEW for the ATHENA X-ray observatory (Willingale et al 2014;Bavdaz et al 2014) that is to be launched in 2028 -requires accurate mirror metrology over a wide range of spatial scales, and also methods for predicting the PSF from metrology data at various X-ray energies.…”

Section: Introductionmentioning

confidence: 99%

Mirrors for X-ray telescopes: Fresnel diffraction-based computation of point spread functions from metrology

Raimondi¹,

Spiga

2014

A&A

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Context. The imaging sharpness of an X-ray telescope is chiefly determined by the optical quality of its focusing optics, which in turn mostly depends on the shape accuracy and the surface finishing of the grazing-incidence X-ray mirrors that compose the optical modules. To ensure the imaging performance during the mirror manufacturing, a fundamental step is predicting the mirror point spread function (PSF) from the metrology of its surface. Traditionally, the PSF computation in X-rays is assumed to be different depending on whether the surface defects are classified as figure errors or roughness. This classical approach, however, requires setting a boundary between these two asymptotic regimes, which is not known a priori. Aims. The aim of this work is to overcome this limit by providing analytical formulae that are valid at any light wavelength, for computing the PSF of an X-ray mirror shell from the measured longitudinal profiles and the roughness power spectral density, without distinguishing spectral ranges with different treatments. Methods. The method we adopted is based on the Huygens-Fresnel principle for computing the diffracted intensity from measured or modeled profiles. In particular, we have simplified the computation of the surface integral to only one dimension, owing to the grazing incidence that reduces the influence of the azimuthal errors by orders of magnitude. The method can be extended to optical systems with an arbitrary number of reflections -in particular the Wolter-I, which is frequently used in X-ray astronomy -and can be used in both near-and far-field approximation. Finally, it accounts simultaneously for profile, roughness, and aperture diffraction. Results. We describe the formalism with which one can self-consistently compute the PSF of grazing-incidence mirrors, and we show some PSF simulations including the UV band, where the aperture diffraction dominates the PSF, and hard X-rays where the X-ray scattering has a major impact on the PSF degradation. The results are validated with ray-tracing simulations, or by comparison with the analytical computation of the half-energy width based on the known scattering theory, where these approaches are applicable. Finally, we validate this by comparing the simulated PSF of a real Wolter-I mirror shell with the measured PSF in hard X-rays.

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Section: Introductionmentioning

confidence: 99%

Mirrors for X-ray telescopes: Fresnel diffraction-based computation of point spread functions from metrology

Raimondi¹,

Spiga

2014

A&A

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“…4. A similar design is currently studied for the Athena mission [13]. The modular approach of SPO is another key benefit.…”

Section: Silicon Pore Opticsmentioning

confidence: 95%

European x-ray optics for next generation space observatories

Wille

Bavdaz

2015

Acta Astronautica

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“…In the future, figure quality of the SPO modules will be improved through the use of high-quality polished fused silica mandrels, which have previously been demonstrated by cosine research to produce optics with superior figure. 6 …”

Section: Discussionmentioning

confidence: 99%

“…6 SPOs make use of industry-standard superpolished silicon wafers. These wafers are first diced into mirror plates of the desired rectangular shape.…”

Section: Silicon Pore Opticsmentioning

confidence: 99%

Performance testing of an off-plane reflection grating and silicon pore optic spectrograph at PANTER

Marlowe

McEntaffer

Allured

et al. 2015

J. Astron. Telesc. Instrum. Syst

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Abstract. An x-ray spectrograph consisting of aligned, radially ruled off-plane reflection gratings and silicon pore optics (SPO) was tested at the Max Planck Institute for Extraterrestrial Physics PANTER x-ray test facility. SPO is a test module for the proposed Arcus mission, which will also feature aligned off-plane reflection gratings. This test is the first time two off-plane gratings were actively aligned to each other and with an SPO to produce an overlapped spectrum. We report the performance of the complete spectrograph utilizing the aligned gratings module and plans for future development. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 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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Science requirements and optimization of the silicon pore optics design for the Athena mirror

Cited by 20 publications

References 6 publications

Mirrors for X-ray telescopes: Fresnel diffraction-based computation of point spread functions from metrology

Mirrors for X-ray telescopes: Fresnel diffraction-based computation of point spread functions from metrology

European x-ray optics for next generation space observatories

Performance testing of an off-plane reflection grating and silicon pore optic spectrograph at PANTER

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