ROSAT Calendar Title Page 2003

View on the entrance opening of one of three X-ray telescopes of XMM-Newton. The largest of the 58 paraboloid mirros measures 70 cm in diameter. The mirror shells are made up of thin nickel in contrary to those of ROSAT and Chandra which are composed of glas ceramics. As reflection layer 0.2 µm gold is evaporated. The benchmark data of the largest X-ray telescopes can be taken from the table.

gzipped PostScript version

	ROSAT	XMM-Newton	Chandra	XEUS (planned)
number of telescopes	1	3	1	1
mirror pairs per telescope	4	58	4	333
material	ZERODUR	nickel	ZERODUR	?
mirror thickness / mm	20	0.5 - 1.21	20 - 40	0.5 - 1
mirror length / cm	100	60	84	100
mass / kg	890	450	1.484	1^st stage 8900 2^nd stage 17400
maximum diameter / m	0,82	0,70	1,20	10
mirror coating	Gold	Gold	Iridium	Gold ?
mirror surface* / cm²	500	1250 pro Teleskop	800	28
spacial resolution / arcsec	3	12	0.5	5
microroughness / nm	0.3	0.5	0.3	0.5
focal length / m	2.4	7.5	10	50

* Telescope Collection Surface at 1 keV