Reconstructing mode mixtures in the optical near-field

Area of Science:

• X-ray imaging
• Coherent optics
• Phase contrast microscopy

Background:

• Current full-field phase contrast imaging requires high spatial coherence.
• Partial spatial coherence presents challenges for advanced imaging techniques.
• Hard x-ray imaging benefits from improved coherence control.

Purpose of the Study:

• To develop a reconstruction scheme for hard x-ray inline holography compatible with partial spatial coherence.
• To extend phase contrast imaging capabilities beyond full coherence requirements.
• To enable relaxed coherence filtering in experimental settings.

Main Methods:

• A mixed-state approach combined with multi-plane detection of extended wavefields.
• Utilizing measurements at different detector defocus positions to generate reconstruction diversity.
• Reconstructing coherent modes and occupancy numbers of the illumination probe.

Main Results:

• Demonstrated successful reconstruction of coherent modes for a partially coherent probe.
• Showed the ability to recover occupancy numbers of these modes.
• Enabled straightforward computation of practical quantities like transversal coherence length.

Conclusions:

• The proposed scheme effectively reconstructs probe modes under partial coherence.
• This method relaxes the stringent coherence requirements for x-ray imaging.
• Facilitates advanced imaging techniques in experimentally relevant, less coherent conditions.