A high resolution large x-ray mission based on thin glass: optomechanical design

Abstract

The technology of X-ray optics based on very thin glass sheets curved on mandrels figured to an optical quality have been quickly developed in these last years, as the on flight NUSTAR or the glass solutions for the IXO mission have demonstrated. Different possibilities to freeze the correct shape can be chosen and the constrains to the glass can widely affect the response in term of strength and quality. This study shows the opto-mechanical performances of the design based on the hot slumped glass sheets stiffed with reinforcing ribs. With this concept a glass stack can be integrated into a mechanical structure in order to form a module that can be assembled in a large structure. The considered input data and requirements are those specified for the proposed Athena mission. Different types of materials are considered following the latest progress in the slumping and the availability of alternative tougher glass. Static and dynamic FE analyses coupled with ray-tracing are performed in order to reach a high resolution (less than 5 arcsec). Also an optimization of the ribs distribution is implemented in function of the radius of curvature.

X-ray optical units made of glass: achievements and perspectives

“…Finally we presented a possible layout for the Athena mirror module based on the slumped glass as a back-up solution. The requirement in terms of effective area can be met and with good margin if a different layout of the mirror modules is implemented [16]. The same set-up used to build the 20 m focal length prototype can be used to build mirror modules with shorter focal length (12 m).…”

“…These glasses have been slumped on the new K20 mold and are characterized by a lower micro-roughness with respect to the previous ones (10nm in the WYKO region). More details on the slumping with this kind of glass can be found in [16]. The same approach used for the PoC#2 layer has been used to determine the best focus position, then different images have been acquired with PIXI at the same energies.…”

“…The new proposed ATHENA mission has a focal length of 12m. In order to keep the glass technology as a back-up solution, it is necessary to develop a new optical design for the system and to perform the analysis of the XOUs structures from the thermo mechanical point of view [16]. Two different mounting schemes are under consideration.…”

Active shape correction of a thin glass/plastic x-ray mirror

“…The latter can be improved by a proper optimization of the parameters used in the thermal process [3] , adopting precisely figured slumping and integration moulds, and along with a dedicated integration process [5] , aimed at suppressing most of the long-period errors remaining in the glass foil profiles after the slumping process. Other deformations may arise post integration as a result from mechanical stresses caused by the accelerations experienced at launch, or as a result of a thermal load applied to a small, but nonzero, CTE mismatch between the materials composing the XOU [6] .…”

Direct hot slumping of thin glass foils for future generation x-ray telescopes: current state of the art and future outlooks

“…Finite Element Analysis was performed with the ANSYS software [6] to evaluate the capability of the process to correct the initial errors at different spatial wavelengths: the basic result is that long-period errors are corrected almost entirely, whereas errors over a few cm scale remain almost unchanged after the integration. An opto-mechanical study for different types of materials and different XOU design was recently performed fulfilling the requirements specified by the ATHENA mission [7]. The study, already performed for the IXO [6] X-ray telescope with a 20 m focal length and an effective area of 3 m 2 at 1 keV, was reviewed for a 12 m focal length telescope, with 2 m 2 effective area at 1 keV, the characteristics of ATHENA.…”