Nesting mirrors

Newton-XMM is an X-ray telescope eqnipped with a set of nested mirrors designed to focns grazing-incidence X rays, a confignration which explains the name X-ray Mnlti-Mirror. It is an ESA project and was lannched by Ariane 5 in December 1999. It opens a window onto the nltrahigh temperatnre Universe with its explosions and stars ripped apart by black holes. Its spectroscopic targets are snpernova remnants and the gases that fill clnsters of galaxies. 

The best surface roughness ever made has been achieved for the ROSAT (Rontgen satellite) mirrors with about two A RMS (root mean square) microroughness. This value has been measured by X-ray scatter measurement at the PANTER test facility of the MPE (Max Planck Institut fiir Extrater-restrische Physik). The contour accuracy of the mirror shells with parabolic shape in the primaries and hyperbolic shape in the secondaries reached an X-ray performance of three arcsec HEW (half energy width) for the complete mirror system of Wolter type I with four concentric nested mirrors [4.39]. 

X-ray performance of three arc seconds HEW (half energy width) for the complete mirror system of Wolter t3rpe I with four concentric nested mirrors [4.39]. 

The mirror assemblies are composed of 30 nested gold coated, confocal double cone approximation to a Woltjer 1 configuration. X-ray tests on the prototype mirrors (Citterio et al. 1990, Conti et al. 1993, 1995) and on the flight unit in Panter have shown a resolution of 40 (HPR), better than... 

ROSAT (an abbreviation of Roentgen satellite ) is a German X-ray telescope having four nested tubular mirrors constructed with Zerodur mirror substrates of 881 mm maximum diameter and 580 mm height. This system should have been sent up with the Space Shuttle in 1987. The loss of the... 

The German X-ray satellite telescope ROSAT was placed in orbit in 1990. It is equipped with a four-mirror system of parabolic and hyperbolic Zerodur cylinders nested into one another (see Fig. 4.66). The inner surfaces of these reflectors were ground and polished by Carl Zeiss, Germany. The residual surface roughness is less than 0.2 nm RMS. An angular resolution of 3.3 arc seconds was achieved for the telescope due to the precise fabrication and mounting of the mirrors. 

For the current ESA X-ray Evolving Universe Spectroscopy (XEUS) mission and for the NASA Constellation-X mission, components made from Zerodur are being tested. The increasing effective areas of the telescopes require nested thin-walled mirrors of large diameters. The requested sizes of the mirror shells and the corresponding manufacturing tools almost exceed the reasonable technical limits of monolithic fabrication and handling. Mirror shells with diameters of more than Im are therefore manufactured... 

FIGURE 1 Focusing geometry of a Wolter type I grazing incidence X-ray telescope constructed by a paraboloid followed by a hyperboloid cylindrical mirror. In X-ray telescopes a number (2,4, or hundreds) of such shells are nested, or placed one inside the other, to improve the X-ray gathering power of the mirror. 

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