Near-field ptychography: phase retrieval for inline holography using a structured illumination.

Area of Science:

• Phase-contrast imaging
• X-ray microscopy
• Diffraction imaging

Background:

• Inline holography encodes phase information using free-space propagation.
• Quantitative imaging in inline holography is challenging due to sample or propagation distance constraints.

Purpose of the Study:

• To present a novel method for simultaneously retrieving a sample's complex-valued transmission function and incident illumination function.
• To improve the robustness and reduce artifacts in propagation-based X-ray phase tomography.

Main Methods:

• Utilizing near-field diffraction patterns from laterally translated samples under structured illumination.
• Applying a reconstruction approach analogous to ptychography.
• Validating the method with hard X-ray synchrotron measurements and simulations.

Main Results:

• Successful simultaneous retrieval of sample transmission function and illumination function.
• Demonstrated reduction of reconstruction artifacts compared to traditional inline holography.
• Relaxation of constraints on sample scattering properties.

Conclusions:

• Near-field ptychography offers a more robust approach to X-ray phase tomography.
• The method effectively factors out wavefront imperfections, enhancing quantitative imaging.
• This technique is expected to improve the accuracy and applicability of phase-contrast X-ray imaging.