Characterization of high-resolution diffractive X-ray optics by ptychographic coherent diffractive imaging

Area of Science:

• Optics
• X-ray Imaging
• Diffractive Optics

Background:

• High-resolution X-ray microscopy requires precise characterization of optical elements.
• Diffractive X-ray lenses, like Fresnel zone plates, are crucial for focusing X-rays.
• Understanding wavefront aberrations is key to optimizing imaging performance.

Purpose of the Study:

• To fully characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens.
• To achieve high spatial resolution imaging using ptychographic techniques.
• To identify sources of aberrations in diffractive X-ray optics.

Main Methods:

• Employed ptychographic coherent diffractive imaging.
• Acquired data using a strongly scattering object and a Fresnel zone plate at 6.2 keV.
• Utilized difference-map phase retrieval and non-linear optimization for image reconstruction.

Main Results:

• Achieved 8 nm spatial resolution in reconstructed object images.
• Determined the X-ray wavefield profile of a 23 nm round focus.
• Measured X-ray wavefront aberrations with a root mean square error of 0.006 waves.
• Correlated aberrations with manufacturing aspects and upstream beamline optics.

Conclusions:

• Ptychographic imaging provides a comprehensive method for characterizing diffractive X-ray lenses.
• The study identified specific sources of wavefront aberrations impacting lens performance.
• Results offer insights for improving the design and fabrication of X-ray optical elements.