Ptychographic lensless coherent endomicroscopy through a flexible fiber bundle

Area of Science:

• Optics
• Biomedical Engineering
• Microscopy

Background:

• Conventional fiber-bundle endoscopes use lenses for minimally invasive imaging, with each fiber core acting as a pixel.
• Lensless imaging through multi-core fibers (MCFs) corrects pre-measured phase distortions but struggles with dynamic fiber bending.
• Temporally varying wavefront distortions remain a significant challenge for existing MCF imaging techniques.

Purpose of the Study:

• To develop a coherent lensless imaging technique for MCFs that is insensitive to dynamic phase distortions.
• To enable robust minimally invasive imaging in the presence of fiber movement.
• To adapt ptychographic reconstruction for lensless endoscope imaging.

Main Methods:

• Demonstrated a coherent lensless imaging technique using intensity-only measurements.
• Employed a ptychographic reconstruction algorithm to retrieve object phase and amplitude.
• Utilized a scanned illumination across MCF cores to capture diffracted intensity patterns from reflective objects.

Main Results:

• The developed technique successfully retrieves phase and amplitude profiles of reflective objects.
• The method is inherently insensitive to core-to-core phase distortions, including dynamic ones.
• Achieved imaging capabilities analogous to confocal microendoscopy using a camera instead of a single detector.

Conclusions:

• The proposed intensity-based ptychographic method offers a robust solution for lensless imaging through MCFs, overcoming limitations of dynamic distortions.
• This approach enhances the potential for advanced minimally invasive imaging applications by providing stable, high-quality imaging.
• The technique paves the way for more adaptable and resilient fiber-optic imaging systems.