Profile reconstruction of grazing-incidence x-ray mirrors from intra-focal x-ray full imaging

Spiga, D.; Basso, S.; Bavdaz, Marcos; Burwitz, V.; Civitani, M.; Citterio, O.; Ghigo, M.; Hartner, Gisela; Menz, Benedikt; Pareschi, G.; Proserpio, L.; Salmaso, B.; Tagliaferri, G.; Wille, Eric

doi:10.1117/12.2023418

Cited by 7 publications

(15 citation statements)

References 22 publications

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“…The HEW of PP0 has been estimated 15.5arcsec on the basis of the reconstructed longitudinal profiles of the hyperbolic and parabolic segments [18]. The positions of ribs are over plotted on the images for the different plates pairs.…”

Section: Metrology Vs Intra-focal X-ray Calibrationmentioning

confidence: 99%

Direct hot slumping and accurate integration process to manufacture prototypal x-ray optical units made of glass

et al. 2013

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X-ray telescopes with very large collecting area, like the proposed International X-ray Observatory (IXO, with around 3 m 2 at 1 keV), need to be composed of a large number high quality mirror segments, aiming at achieving an angular resolution better than 5 arcsec HEW (Half-Energy-Width). A possible technology to manufacture the modular elements that will compose the entire optical module, named X-ray Optical Units (XOUs), consists of stacking in Wolter-I configuration several layers of thin foils of borosilicate glass, previously formed by hot slumping. The XOUs are subsequently assembled to form complete multi-shell optics with Wolter-I geometry. The achievable global angular resolution of the optic relies on the required surface shape accuracy of slumped foils, on the smoothness of the mirror surfaces and on the correct integration and co-alignment of the mirror segments. The Brera Astronomical Observatory (INAF-OAB) is leading a study, supported by ESA, concerning the implementation of the IXO telescopes based on thin slumped glass foils. In addition to the opto-mechanical design, the study foresees the development of a direct hot slumping thin glass foils production technology. Moreover, an innovative assembly concept making use of Wolter-I counter-form moulds and glass reinforcing ribs is under development. The ribs connect pairs of consecutive foils in an XOU stack, playing a structural and a functional role. In fact, as the ribs constrain the foil profile to the correct shape during the bonding, they damp the low-frequency profile errors still present on the foil after slumping. A dedicated semirobotic Integration MAchine (IMA) has been realized to this scope and used to build a few integrated prototypes made of several layers of slumped plates. In this paper we provide an overview of the project, we report the results achieved so far, including full illumination intra-focus X-ray tests of the last integrated prototype that are compliant with a HEW of around 17''.

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Section: Metrology Vs Intra-focal X-ray Calibrationmentioning

confidence: 99%

Direct hot slumping and accurate integration process to manufacture prototypal x-ray optical units made of glass

et al. 2013

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“…This is exactly the PSF expression we already derived (Spiga et al, 2013a) via a purely geometric reasoning. This approach, based on curvature detection, has been also extended to the intrafocal configuration for mirror shape reconstruction under X-ray illumination (Spiga et al, 2013b). The monotonic trend of z 0 e clearly implies that z 00 e !…”

Section: Beam-shaping Formulae In the Geometric Optic Limitmentioning

confidence: 99%

X-ray beam-shapingviadeformable mirrors: surface profile and point spread function computation for Gaussian beams using physical optics

Spiga

2018

J Synchrotron Radiat

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X-ray mirrors with high focusing performances are commonly used in different sectors of science, such as X-ray astronomy, medical imaging and synchrotron/ free-electron laser beamlines. While deformations of the mirror profile may cause degradation of the focus sharpness, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators. The resulting profile can be characterized with suitable metrology tools and correlated with the expected optical quality via a wavefront propagation code or, sometimes, predicted using geometric optics. In the latter case and for the special class of profile deformations with monotonically increasing derivative, i.e. concave upwards, the point spread function (PSF) can even be predicted analytically. Moreover, under these assumptions, the relation can also be reversed: from the desired PSF the required profile deformation can be computed analytically, avoiding the use of trial-and-error search codes. However, the computation has been so far limited to geometric optics, which entailed some limitations: for example, mirror diffraction effects and the size of the coherent X-ray source were not considered. In this paper, the beam-shaping formalism in the framework of physical optics is reviewed, in the limit of small light wavelengths and in the case of Gaussian intensity wavefronts. Some examples of shaped profiles are also shown, aiming at turning a Gaussian intensity distribution into a top-hat one, and checks of the shaping performances computing the at-wavelength PSF by means of the WISE code are made.

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“…The 35 m-long XACT facility at INAF/ OAPA is already described in detail elsewhere [12], [13] and the analysis of the intrafocus intensity distribution pattern, which should enable us to reconstruct the mirror profile and to find the optima l voltages to perform the correct ion of the figure errors, is duly exposed in a prev ious paper [11] . In the present case, however, since the mirror had only two small p iezoelectric actuators , to be compared with a total mirror surface of 200 mm  200 mm, the correction capabilities were extremely limited.…”

Section: First Tests At the Xact Facilitymentioning

confidence: 99%

“…A dedicated electronic board supplies the required voltages to the piezoelectric elements. Finally, the feedback to the piezoelectric array should be provided by reconstructing the mirror shape under Xray illu mination in intra -focal setup [11] at the XACT facility [12], [13] at INAF/OAPA, following an algorith m in itially developed to solve beam-shaping problems [14] . The AXYOM p roject naturally inscribes in the experience gained at the participating institutes in hot slump ing, integration of thin glass foils, thin film deposition, photolithography, electronics, and X-ray tests.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing and testing a thin glass mirror shell with piezoelectric active control

Spiga¹,

Barbera²,

Collura³

et al. 2015

SPIE Proceedings

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Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of lightweight materials like glass or silicon in order to keep the total mass within acceptable limits. Optical modules based on thin slumped g lass foils are being developed at various institutes, aiming at improving the angular resolution to a few arcsec HEW. Th in mirrors are prone to deform, so they require a careful integration to avoid deformations and even correct forming errors. On the other hand, this offers the opportunity to actively correct the residual deformat ion: a viable possibility to improve the mirror figure is the application of p iezoelectric actuators onto the non-optical side of the mirrors, and several groups are already at work on this approach. The concept we are developing consists of actively integrating thin glass foils with piezoelectric patches, fed by voltages driven by the feedback provided by X-rays. The actuators are commercial co mponents, while the tension signals are carried by a p rinted circuit obtained by photolithography, and the driving electronic is a mu lti-channel low power consumption voltage supply developed inhouse. Finally, the shape detection and the consequent voltage signal to be provided to the piezo electric array are determined in X-rays, in intra-focal setup at the XACT facility at INAF/OA PA. In this work, we describe the manufacturing steps to obtain a first active mirror prototype and the very first test performed in X-rays.

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Profile reconstruction of grazing-incidence x-ray mirrors from intra-focal x-ray full imaging

Cited by 7 publications

References 22 publications

Direct hot slumping and accurate integration process to manufacture prototypal x-ray optical units made of glass

Direct hot slumping and accurate integration process to manufacture prototypal x-ray optical units made of glass

X-ray beam-shapingviadeformable mirrors: surface profile and point spread function computation for Gaussian beams using physical optics

Manufacturing and testing a thin glass mirror shell with piezoelectric active control

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