The X-ray telescope of eROSITA will consist of 7 identical and co-aligned mirror modules, each with 54 nested Wolter-1 mirror shells. The mirror shells are glued onto a spider wheel which is screwed to the mirror interface structure making a rigid mechanical unit. The assembly of 7 modules forms a compact hexagonal configuration with 1300 mm diameter (see Fig. 1) and will be attached to the telescope structure which connects to the 7 separate CCD cameras in the focal planes. The co-alignment of the mirror module enables eROSITA to perform also pointed observations.
The replication process described in chapter III allows the manufacturing in one single piece and at the same time of both the parabola and hyperbola parts of the Wolter 1 mirror.
The X-ray telescope of eROSITA will consist of 7 identical and co-aligned mirror modules, each with 54 nested Wolter-1 mirror shells. The mirror shells are glued onto a spider wheel which is screwed to the mirror interface structure making a rigid mechanical unit. The assembly of 7 modules forms a compact hexagonal configuration with 1300 mm diameter (see Fig. 1) and will be attached to the telescope structure which connects to the 7 separate CCD cameras in the focal planes. The co-alignment of the mirror module enables eROSITA to perform also pointed observations.
The replication process described in chapter III allows the manufacturing in one single piece and at the same time of both the parabola and hyperbola parts of the Wolter 1 mirror.
This paper provides the theoretic description of such a Fresnel zone plate especially considering resolution and efficiency. Based on the theoretic results the collimator setup performance is analyzed and requirements for fabrication and alignment are calculated.
An open question in the measurement of X-ray optics for telescopes in space is what the point spread function (PSF) looks like in orbit and what is the focal length for an infinite source distance. In order to measure such a PSF, a parallel X-ray beam with a diameter of several centimeters to meters is needed.
For this purpose it is studied of how to collimate the X-rays using a zone plate. Furthermore, a configuration study is presented to characterize X-ray optics with such a collimated beam at the PANTER X-ray test facility. In particular, estimations for segmented optics for future X-ray missions such as ATHENA+ with a focal length of 10m to 20m are presented.
MPE will provide the X-ray Survey Telescope eROSITA for the Russian Spektrum-Roentgen-Gamma Mission. The mirror system consists of a compact bundle of seven co-aligned mirror modules with a focal length of 1600 mm and 54 nested mirror shells each. The 61 arcmin field-of-view (FoV) will yield a high grasp of about 1000 cm2deg2 around 1 keV. An angular resolution of 15 arcsec HEW on-axis (resulting in an average angular resolution of ~26 arcsec HEW over the field-of-view and ~30 arcsec including all optical and spacecraft error contributions) will help distinguish point sources from extended emission of galaxy clusters which are relevant for cosmological studies. During a four year allsky survey eROSITA will generate a new rich database of X-ray sources. In a second phase of the mission eROSITA will also perform pointed observations.
After a mirror development program the integration of flight mirror modules started in early 2011. Currently, the manufacturing of flight modules is ongoing and some of the partially integrated ones have already been X-ray tested. Calibration of completed mirror modules will start end of 2012. Parallel to the X-ray mirrors we have developed an X-ray baffle to suppress stray light from single reflections. It consists of precisely shaped and welded concentric Invar foils which will be mounted on top of each mirror module and aligned by optical means.
We report on the design and the mirror development program including the X-ray baffle and present the latest results from X-ray measurements.
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