BEaTriX, the Beam Expander Testing X-ray facility for testing ATHENA's SPO modules: the collimating mirror
Date Issued
2019
Abstract
The BEaTriX (Beam Expander Testing X-ray) facility is now under construction at INAF-Brera Astronomical
Observatory with the support of ESA. We aim to use it as a pathfinder to demonstrate the feasibility of the acceptance
tests of the ATHENA’s Silicon pore optics Mirror Modules (MM), i.e., point spread function and effective area
measurements at two energies for all MMs. A microfocus X-ray source placed in the focus of a paraboloid mirror will
provide a collimated X-ray beam to the next stages featuring the facility, i.e., the monochromator and the beam
expansion units, which will finally enable the full illumination of the mirror modules under test. The collimating mirror
has to satisfy severe surface specifications to allow the divergence of the X-ray beam reaching the requirements.
Simulations, based on physical optics, have shown that the optical quality of the mirror surface has to reach 0.5 arcsec
Half-Energy Width (HEW) at 4.51 keV. We procured a ground and lapped mirror substrate in HOQ 310 fused quartz
material. The first step of the process is based on the bonnet polishing technology with our CNC IRP1200 Zeeko
machine, and it is guided by the analysis of the metrological data obtained by the optical profilometer present at Media
Lario S.r.l. laboratories. The spatial frequency errors not correctable by bonnet polishing can be then removed by
smoothing and superpolishing processes, followed by ion beam figuring to correct the remaining errors in the low
frequency range. In this paper, we report on the analysis performed to correlate the requirement on beam divergence to
the manufacturing tolerances on the surface. We present the manufacturing process and the results so far achieved.
Coverage
Optics for EUV, X-Ray, and Gamma-Ray Astronomy IX
All editors
O'Dell, Stephen; Pareschi, Giovanni
Series
Volume
11119
Start page
111191J-1
Conferenece
Optics for EUV, X-Ray, and Gamma-Ray Astronomy IX
Conferenece place
San Diego, California, United States
Conferenece date
11-15 August, 2019
Issn Identifier
0277-786X
Ads BibCode
2019SPIE11119E..1JV
Rights
open.access
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