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In the process of developing a concentrating telescope for the next generation of X-ray satellites various techniques have been employed to deposit thin films of Au, Pt or Ni on a smooth substrate, Among these the following three methods are of particular interest in terms of making a high throughput X-ray telescope. The first method involves vacuum sputtering of the relevant thin film material onto a polished glass mandrel followed by replication onto a carbon fiber shell. In the second a thin film is deposited directly on lacquered Alfoils by vacuum sputtering. In the third a thin Ni shell is generated by electroforming. In all cases the thin film is deposited on thin shells and it is possible to achieve a large effective collection area by nesting them. X-ray scattering measurements made with a triple axis X-ray spectrometer have been used to test the smoothness of testsurfaces. In this spectrometer a perfect, channelcut Sicrystal extracts Fe Karadiation from a conventional X-ray tube. The radiation is incident on the thin film surface and the specularly reflected and scattered radiation from the thin film is analyzed by another perfect, channelcut Sicrystal. An essentially "tailless" probe of the scattered X-rays is obtained when the X-rays are reflected several times in the channelcut crystals. Measurements on surfaces obtained from various substrate materials and deposition techniques are presented and compared with measurements on a high quality Au testflat and a similar Pt testflat, produced by coating highly polished glassubstrates. It is demonstrated that the measurement technique provides an excellent and detailed test of the quality of the mirror surface.
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