The optics system of the New Hard X-ray Mission: status report

Basso, S.; Pareschi, G.; Citterio, O.; Spiga, D.; Tagliaferri, G.; Raimondi, Lorenzo; Sironi, G.; Cotroneo, Vincenzo; Salmaso, B.; Negri, B.; Attinà, Primo; Borghi, G.; Orlandi, A.; Vernani, Dervis; Valsecchi, Giuseppe; Binda, Riccardo; Marioni, Fabio; Moretti, Stefano; Castelnuovo, Moreno; Burkert, Wolfgang; Freyberg, M. J.; Burwitz, V.

doi:10.1117/12.895324

Cited by 8 publications

(16 citation statements)

References 19 publications

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“…An experimental proof in favor of the proposed methods (including the linear sum of figure and XRS) is provided in another paper of this volume, 17 where we report the hard X-ray tests we performed at the SPring-8 synchrotron facility (JASRI, Japan) on an electroformed Wolter-I mirror for the NHXM project. 18 Not only the measured HEW trend is found to be in agreement with the analytically computed one from the figure and roughness measurement, but also the PSF measured in hard X-rays is very well reproduced by the application of the Fresnel diffraction to the measured mirror profiles and roughness. This proves not only the accuracy of X-ray measurements and metrological characterizations, but also the correctness of the Fresnel diffraction method as a predictive approach to the PSF computation from mirror metrology.…”

Section: Theoretical and Experimental Validation Of Resultssupporting

confidence: 69%

Point spread function of real Wolter-I X-ray mirrors: computation by means of the Huygens-Fresnel principle

Raimondi

Spiga

2011

SPIE Proceedings

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The Point Spread Function (PSF) of an imaging X-ray telescope is mostly determined by the defects of its grazing reflection optics. In terms of Fourier components of the mirrors' profile, figure errors comprise long spatial wavelengths, whilst short spatial wavelengths are identified as microroughness. The former contribution is in general treated by means of geometrical optics, while the contribution of the latter -strongly dependent on the X-ray energy -is usually derived from the first order scattering theory. This approach, however, requires setting a sudden transition between these two treatments, whereas in the general case the change is expectedly more gradual. In order to compute the PSF expected from a mirror profile, we need a general method that does not need to classify surface defects as roughness or profile errors. In this work we show how to compute the PSF of real X-ray mirror shells in a typical Wolter-I configuration, at any X-ray energy. The suggested method is an application of the Huygens-Fresnel principle to grazing incidence Wolter-I profiles, and is an extension of the single-reflection formalism we presented in a previous paper. A few integral equations, applied from UV to hard X-rays, return the expected PSFs from measured or simulated profiles, accounting for the surface roughness along with its PSD (Power Spectral Density). The results are consistent with the ray-tracing results whenever geometric optic can be applied, and they merge with the results of the first order X-ray scattering theory when the roughness is within the smooth-surface limit. Finally, the PSF computed from the profile and the roughness of a real mirror is in very good agreement with the one experimentally measured in hard X-rays.

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Section: Theoretical and Experimental Validation Of Resultssupporting

confidence: 69%

Point spread function of real Wolter-I X-ray mirrors: computation by means of the Huygens-Fresnel principle

Raimondi

Spiga

2011

SPIE Proceedings

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“…The diameters of the shells range from 507 to 267 mm. To meet the different requirements for the angular resolution, and to optimize the mass constrains, two different thickness-to-diameter ratio sequences for the Nickel mirror walls of the shells are considered [17,18].…”

Section: -5mentioning

confidence: 99%

The enhanced X-ray Timing and Polarimetry mission—eXTP

Zhang

Santangelo

Feroci

et al. 2018

Sci. China Phys. Mech. Astron.

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256

116

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In this paper we present the enhanced X-ray Timing and Polarimetry mission. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources. The paper provides a detailed description of: 1) The technological and technical aspects, and the expected performance of the instruments of the scientific payload; 2) The elements and functions of the mission, from the spacecraft to the ground segment.X-ray instrumentation, X-ray Polarimetry, X-ray Timing, Space mission: eXTP PACS number(s): 95.55. Ka, 95.85.Nv, 95.75.Hi, 97.60.Jd, 97.60.Lf

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“…Even if an adoption of the pencil beam at PANTER [14] is foreseen to calibrate the NHXM optics after completion of an appropriate manipulator [9] , we envisaged conducting parallel measurements with synchrotron light at the beamline BL20B2 of the SPring-8 radiation facility (JASRI, Hyogo prefecture, Japan). The reason is that SPring-8 is a powerful source with a copious emission flux extended to more than 110 keV, thereby minimizing the exposure time per tested sector.…”

Section: Introductionmentioning

confidence: 99%

Angular resolution measurements at SPring-8 of a hard x-ray optic for the New Hard X-ray Mission

et al. 2011

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The realization of X-ray telescopes with imaging capabilities in the hard (> 10 keV) X-ray band requires the adoption of optics with shallow (< 0.25 deg) grazing angles to enhance the reflectivity of reflective coatings. On the other hand, to obtain large collecting area, large mirror diameters (< 350 mm) are necessary. This implies that mirrors with focal lengths ≥10 m shall be produced and tested. Full-illumination tests of such mirrors are usually performed with onground X-ray facilities, aimed at measuring their effective area and the angular resolution; however, they in general suffer from effects of the finite distance of the X-ray source, e.g. a loss of effective area for double reflection. These effects increase with the focal length of the mirror under test; hence a "partial" full-illumination measurement might not be fully representative of the in-flight performances. Indeed, a pencil beam test can be adopted to overcome this shortcoming, because a sector at a time is exposed to the X-ray flux, and the compensation of the beam divergence is achieved by tilting the optic. In this work we present the result of a hard X-ray test campaign performed at the BL20B2 beamline of the SPring-8 synchrotron radiation facility, aimed at characterizing the Point Spread Function (PSF) of a multilayer-coated Wolter-I mirror shell manufactured by Nickel electroforming. The mirror shell is a demonstrator for the NHXM hard X-ray imaging telescope (0.3 -80 keV), with a predicted HEW (Half Energy Width) close to 20 arcsec. We show some reconstructed PSFs at monochromatic X-ray energies of 15 to 63 keV, and compare them with the PSFs computed from post-campaign metrology data, self-consistently treating profile and roughness data by means of a method based on the Fresnel diffraction theory. The modeling matches the measured PSFs accurately.

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The optics system of the New Hard X-ray Mission: status report

Cited by 8 publications

References 19 publications

Point spread function of real Wolter-I X-ray mirrors: computation by means of the Huygens-Fresnel principle

Point spread function of real Wolter-I X-ray mirrors: computation by means of the Huygens-Fresnel principle

The enhanced X-ray Timing and Polarimetry mission—eXTP

Angular resolution measurements at SPring-8 of a hard x-ray optic for the New Hard X-ray Mission

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