Nanofocusing at ESRF Using Graded Multilayer Mirrors

Dynamically bent graded multilayer mirrors have been developed at ESRF for their large energy bandwidth acceptance, energy tunability and large numerical aperture for limited mirror size. Kirkpatrick Baez systems with spot sizes below 100 nanometers have been installed on two beamlines. A diffraction limited line width of 41 nanometers FWHM was obtained at 24 keV on ID19. This experiment directly confirms that the penetration depth of the X‐rays in the multilayer coating does not limit the obtainable focal spot size. The resolution limits of such a nanofocusing device are discussed as well as figure accuracy and vibration level issues.