抄録
We have developed a precision fabrication method to realize an X-ray mirror with nearly atomic
smoothness and shape accuracy of close to 1 nm peak to valley. A set of KB (Kirkpatric-Baez) mirrors
for focusing the Japanese XFEL (X-ray free electron laser) named SACLA (SPring-8 angstrom compact
free electron laser) to a micrometer spot size was developed and installed in the experimental hatch of
SACLA to enable XFEL experiments to be carried out by the public. The spot size achieved was
0.9 × 1.1 μm2 which was theoretically predicrted under the diffraction-limited condition. Another set of
focusing mirrors is currently under development to enable the sub-50 nm focusing of SACLA, in which
two-step focusing will be employed to realize nanofocusing with enough working distance such as
several hundreds of millimeters.
