X‐ray single‐grating interferometry for wavefront measurement and correction of hard x‐ray nanofocusing mirrors

Abstract

X‐ray single‐grating interferometry was applied to conduct accurate wavefront corrections for hard X‐ray nanofocusing mirrors. Systematic errors in the interferometer, originating from a grating, a detector, and alignment errors of the components, were carefully examined. Based on the measured wavefront errors, the mirror shapes were directly corrected using a differential deposition technique. The corrected X‐ray focusing mirrors with a numerical aperture of 0.01 attained two‐dimensionally diffraction‐limited performance. The results of the correction indicate that the uncertainty of the wavefront measurement was less than λ/72 in root‐mean‐square value.