Fabrication of elliptically figured mirror for focusing hard x rays to size less than 50nm

In this study, we designed, fabricated, and evaluated a hard x-ray focusing mirror having an ideally focused beam with a full width at half maximum in the intensity profile of 36nm at an x-ray energy of 15keV. The designed elliptically curved shape was fabricated by a computer-controlled fabrication system using plasma chemical vaporization machining and elastic emission machining, on the basis of surface profiles accurately measured by combining microstitching interferometry with relative angle determinable stitching interferometry. A platinum-coated surface was employed for hard x-ray focusing with a large numerical aperture. Line-focusing tests on the fabricated elliptical mirror are carried out at the 1-km-long beamline of SPring-8. A full width at half maximum of 40nm was achieved in the focused beam intensity profile under the best focus conditions.