X-ray focusing using elliptically bent multilayers
- European Synchrotron Radiation Facility, Grenoble (France)
The authors present the x-ray performance on an ESRF synchrotron beamline of a focusing device based on the dynamical bending of a flat silicon plate coated with a 2.5 nm d-spacing W/Si multilayer. The mirror was shaped by trial and error to a cylindrical ellipse using an optical profilometer. In a first experiment the device was bent to a 71-m radius to account for the demagnification factor and the energy of operation. With a monochromatic incident beam set at 9 keV a vertical spot size of 4.5 {micro}m was obtained at 41 m from the source and 1 m from the multilayer, which agreed closely with theoretical expectations. Such good agreement was due to the small residual slope error with respect to the ellipse: around 2 {micro}rad over a 150-mm length for radii greater than 50 m. Moreover, as the divergence of the incident beam was larger than the rocking curve width, less than 25% of the mirror could contribute, reducing the distortion to an even lower figure. With the same geometrical parameters the device exposed to the white beam (monochromator removed) lead to a vertical spot size of about 7 {micro}m. Here the whole mirror surface could reflect, which caused more distortion to the incoming beam but also gave rise to a much higher intensity. The gain in flux obtained with a gradient of d-spacing along the mirror surface is discussed. Finally, results with a Kirkpatrick-Baez arrangement let one expect in the near future a flux gain greater than 10{sup 4} with a 10 {micro}m by 10 {micro}m focal spot.
- OSTI ID:
- 531518
- Report Number(s):
- CONF-960848--; ISBN 0-8194-2244-4
- Country of Publication:
- United States
- Language:
- English
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