title: Characterization of high-resolution diffractive X-ray optics by ptychographic coherent diffractive imaging.
abstract: We have employed ptychographic coherent diffractive imaging to completely characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens. The ptychographic data from a strongly scattering object was acquired using the radiation cone emanating from a coherently illuminated Fresnel zone plate at a photon energy of 6.2 keV. Reconstructed images of the object were retrieved with a spatial resolution of 8 nm by combining the difference-map phase retrieval algorithm with a non-linear optimization refinement. By numerically propagating the reconstructed illumination function, we have obtained the X-ray wavefield profile of the 23 nm round focus of the Fresnel zone plate (outermost zone width, Δr = 20 nm) as well as the X-ray wavefront at the exit pupil of the lens. The measurements of the wavefront aberrations were repeatable to within a root mean square error of 0.006 waves, and we demonstrate that they can be related to manufacturing aspects of the diffractive optical element and to errors on the incident X-ray wavefront introduced by the upstream beamline optics.
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. jvila@aps.anl.gov
authors: Joan
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authors: Vila-Comamala
authors: Ana
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authors: Diaz
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authors: Guizar-Sicairos
authors: Alexandre
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authors: Mantion
authors: Cameron M
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