Ptycho-endoscopy on a lensless ultrathin fiber bundle tip

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Microscopy

Background:

• Synthetic aperture radar (SAR) achieves high resolution by synthesizing a large aperture.
• Micro-endoscopic imaging is limited by the diffraction of light and the physical size of the probe.
• Existing endoscopic techniques struggle to achieve both high resolution and extended depth of field.

Purpose of the Study:

• To introduce synthetic aperture ptycho-endoscopy (SAPE) for micro-endoscopic imaging.
• To overcome the diffraction limit in endoscopic imaging.
• To enhance the space-bandwidth product and depth of field for endoscopic applications.

Main Methods:

• SAPE employs a lensless fiber bundle tip to record coherent diffraction patterns.
• Handheld operation induces positional shifts, analogous to SAR's movement, to acquire a ptychogram.
• Low-rank spatiotemporal decomposition corrects for hand motion and fiber bending artifacts.

Main Results:

• SAPE resolves a 548-nm linewidth, surpassing the diffraction limit.
• Achieved a space-bandwidth product of ~1.1 million effective pixels, a 36-fold increase.
• Demonstrated an extended depth of field exceeding 2 cm with refocusing capability.

Conclusions:

• SAPE enables super-resolution micro-endoscopic imaging beyond the diffraction limit.
• The technique significantly enhances imaging resolution and depth of field.
• Opens new avenues for fiber-based and distal-chip endoscopy in medical diagnostics and industrial inspection.