title: Reconstruction of an astigmatic hard X-ray beam and alignment of K-B mirrors from ptychographic coherent diffraction data.
abstract: We have used coherent X-ray diffraction experiments to characterize both the 1-D and 2-D foci produced by nanofocusing Kirkpatrick-Baez (K-B) mirrors, and we find agreement. Algorithms related to ptychography were used to obtain a 3-D reconstruction of a focused hard X-ray beam waist, using data measured when the mirrors were not optimally aligned. Considerable astigmatism was evident in the reconstructed complex wavefield. Comparing the reconstructed wavefield for a single mirror with a geometrical projection of the wavefront errors expected from optical metrology data allowed us to diagnose a 40 μrad misalignment in the incident angle of the first mirror, which had occurred during the experiment. Good agreement between the reconstructed wavefront obtained from the X-ray data and off-line metrology data obtained with visible light demonstrates the usefulness of the technique as a metrology and alignment tool for nanofocusing X-ray optics.
authors.affiliation: Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland. Cameron.Kewish@synchrotron-soleil.fr
authors.forename: Cameron M
authors.initials: CM
authors.lastname: Kewish
authors.forename: Manuel
authors.initials: M
authors.lastname: Guizar-Sicairos
authors.forename: Chian
authors.initials: C
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Qian
authors.forename: Bing
authors.initials: B
authors.lastname: Shi
authors.forename: Christa
authors.initials: C
authors.lastname: Benson
authors.forename: Ali M
authors.initials: AM
authors.lastname: Khounsary
authors.forename: Joan
authors.initials: J
authors.lastname: Vila-Comamala
authors.forename: Oliver
authors.initials: O
authors.lastname: Bunk
authors.forename: James R
authors.initials: JR
authors.lastname: Fienup
authors.forename: Albert T
authors.initials: AT
authors.lastname: Macrander
authors.forename: Lahsen
authors.initials: L
authors.lastname: Assoufid