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

Spiga, D.; Raimondi, Lorenzo; Furuzawa, Akihiro; Basso, S.; Binda, Riccardo; Borghi, G.; Cotroneo, Vincenzo; Grisoni, Gabriele; Kunieda, H.; Marioni, Fabio; Matsumoto, Hironori; Mori, Hajime; Miyazawa, Tatsuo; Negri, B.; Orlandi, A.; Pareschi, G.; Salmaso, B.; Tagliaferri, G.; Uesugi, Kentaro; Valsecchi, Giuseppe; Vernani, Dervis

doi:10.1117/12.894488

Cited by 7 publications

(13 citation statements)

References 22 publications

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“…The SPring-8 measurement results are reported in detail in another paper of this volume [19] . A dedicated jig to test the NHXM prototypes in the pencil beam configuration has been recently completed and will be used in the near future in order to test the entire mirror surface in pencil beam setup also at the PANTER [20] facility.…”

Section: Tdm2mentioning

confidence: 96%

“…Figure 12. Comparison of the HEW measurement results obtained at PANTER and Spring-8 [19] on the W/Si coated mirror shell 297. The trends obtained from the two campaigns are mutually consistent in the overlapping energy region (15-40 keV).…”

Section: Tdm2mentioning

confidence: 99%

“…has been tested. (right) Reconstruction of the mirror shell focal spot at 30 keV [19] . The image size is 4 cm.…”

Section: Tdm2mentioning

confidence: 99%

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

et al. 2011

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The New Hard X-ray Mission (NHXM) is a space X-ray telescope project focused on the 0.2 to 80 keV energy band, coupled to good imaging, spectroscopic and polarimetry detectors. The mission is currently undergoing the Phase B study and it has been proposed to ESA as a small-size mission to be further studied in the context of the M3 call; even if the mission was not downselected for this call, its study is being continued by ASI. The required performance is reached with a focal length of 10 m and with four mirror modules, each of them composed of 70 NiCo electroformed mirror shells. The reflecting coating is a broadband graded multilayer film, and the focal plane is mounted onto an extensible bench. Three of the four modules are equipped with a camera made of two detectors positioned in series, a Silicon low energy detector covering the range 0.2 to 15 keV and a high energy detector based on CdTe sensitive from 10 keV up to 120 keV. The fourth module is dedicated to the polarimetry to be performed with enhanced imaging capabilities. In this paper the latest development in the design and manufacturing of the optics is presented. The design has been optimized in order to increase as much as possible the effective area in the high-energy band. The manufacturing of the mirror shells benefits from the latest development in the mandrel production (figuring and polishing), in the multilayer deposition and in the integration improvements.

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Section: Tdm2mentioning

confidence: 96%

Section: Tdm2mentioning

confidence: 99%

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

et al. 2011

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“…1 compares the advantages of either method to compute the PSF. 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.…”

Section: Theoretical and Experimental Validation Of Resultsmentioning

confidence: 95%

“…Finally, the application of the Fresnel diffraction to the real data out of profile and roughness metrology of a Wolter-I mirror shell for the NHXM optics 18 is in very good agreement with the PSFs measured at the SPring-8 radiation facility. 17 The applications of this method to the development of X-ray optics for astronomy or terrestrial sources are potentially numerous.…”

Section: Discussionmentioning

confidence: 99%

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

Cited by 7 publications

References 22 publications

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

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

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

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

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