Quantitative phase imaging through an ultra-thin lensless fiber endoscope

TL;DR

This paper introduces a computational lensless microendoscope using an ultra-thin multi-core fiber for high-resolution, 3D quantitative phase imaging of biomedical samples, enabling in vivo applications without mechanical movement.

Contribution

It presents a novel lensless imaging method that reconstructs complex light fields from speckle patterns, allowing 3D QPI through ultra-thin fibers without mechanical scanning.

Findings

Achieves 1 μm lateral resolution and nanoscale axial resolution.

Successfully images human cancer cells in 3D.

Validates phase accuracy with hydrogel beads.

Abstract

Quantitative phase imaging (QPI) is a label-free technique providing both morphology and quantitative biophysical information in biomedicine. However, applying such a powerful technique to in vivo pathological diagnosis remains challenging. Multi-core fiber bundles (MCFs) enable ultra-thin probes for in vivo imaging, but current MCF imaging techniques are limited to amplitude imaging modalities. We demonstrate a computational lensless microendoscope that uses an ultra-thin bare MCF to perform quantitative phase imaging of biomedical samples with up to 1 {\mu}m lateral resolution and nanoscale axial resolution. The incident complex light field at the measurement side is precisely reconstructed from a single-shot far-field speckle pattern at the detection side, enabling digital focusing and 3D volumetric reconstruction without any mechanical movement. The accuracy of the quantitative phase reconstruction is validated by imaging the phase target and hydrogel beads through the MCF. With the proposed imaging modality, 3D imaging of human cancer cells is achieved through the ultra-thin fiber endoscope, promising widespread clinical applications.