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Ion beam sputtering of x-ray multilayer mirrors

: Gawlitza, P.; Braun, S.; Dietrich, G.; Menzel, M.; Schädlich, S.; Leson, A.


Khounsary, A.M. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Advances in X-Ray/EUV Optics and Components III : San Diego, CA, August 10-14, 2008
Bellingham, WA: SPIE, 2008 (SPIE Proceedings Series 7077)
ISBN: 978-0-8194-7297-7
ISSN: 0277-786X
Art. 707703
Conference "Advances in X-Ray/EUV Optics and Components" <3, 2008, San Diego/Calif.>
Conference Paper
Fraunhofer IWS ()

Ion beam sputtering has been applied for polishing, figuring and multilayer coating on silicon and quartz glass Substrates for the fabrication of x-ray mirrors. For high-performance x-ray optics extremely low microroughnesses of the substrates have to be achieved. Particularly for low d-spacing multilayers (d = 1...2 nm) even small improvements of the surface quality result in significant performance gains of the mirrors. By ion beam polishing silicon substrate surfaces could be smoothed from 0.18 nm rms to 0.11 rim rms (AFM scan length = 5 mu m). Furthermore figuring of spherical substrates into elliptical or parabolic surface contours has been developed and applied. Spherical quartz glass substrates with initial rms roughnesses of 0.73 nm and 0.52 nm show reduced roughnesses after figuring and multilayer coating of 0.26 nm and 0.10 nm using AFM scan lengths of 20 pm and 5 pm, respectively. The testing of the ion beam figured mirrors for the application as parallel beam and focussing optics shows very promising results: The comparison of collimating mirrors, produced either by ion beam figuring or bending, shows very similar x-ray intensities. However, the ion beam figured mirrors open the perspective for further reduced figure errors, improved long-term stability and 2-dimensional focusing.