Grazing incidence telescopes for satellite borne UV and x-ray astronomy missions including ROSAT, XMM and Lyman

Grazing incidence telescopes have been in use for quite some time for X-ray applications. High resolution Wolter type 1 telescopes have been flown on board of Skylab, the Einstein and the EXOSAT satellites. ROSAT will be the next space borne observatory, which will perform for the first time a complete sky survey by means of a large high resolution grazing incidence X-ray telescope. The design and fabrication of the mirror assembly are presented including metrology measurements and full aperture X-ray tests. The X-ray image of the fully assembled prototype model shows a measured radius of 2.0 arcsec and 3.2 arcsec for the 50% and 80% encircled energy, respectively. Metrology measurements of the not yet assembled flight mirrors indicate an even better performance including microroughness of 2.6 A rms. A cluster of highly nested Wolter type I telescopes has been proposed for ESA's future X-ray astronomy cornerstone mission XMM. The optical design of the mirror assembly optimized to high throughput but moderate resolution is presented. Although originally proposed for X-rays grazing incidence telescopes start to be preferred for use at longer wavelengths due to the lack of high reflectivity coatings throughout the region from the X-rays to the UV at -- 1000 A. The future UV astronomy mission Lyman selected for an industrial Phase-A study by ESA utilizes a Wolter Schwarzschild type II telescopes which feeds a high resolution (λ/Δ $ = 30.000) spectrograph covering the 900 - 1200 A region. The optical design of the telescope is described and the error budget for the manufacturing of the arcsec telescope is discussed