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 with microscale lateral resolution and nanoscale axial sensitivity of the optical path length. The incident complex light field at the measurement side is precisely reconstructed from the far-field speckle pattern at the detection side, enabling digital refocusing in a multi-layer sample 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, three-dimensional imaging of human cancer cells is achieved through the ultra-thin fiber endoscope, promising widespread clinical applications.

定量相位成像 (QPI) 是一种无标记技术，可在生物医学中提供形态学和定量生物物理信息。然而，将如此强大的技术应用于体内病理诊断仍然具有挑战性。多芯光纤束 (MCF) 使超薄探针能够用于体内成像，但当前的 MCF 成像技术仅限于振幅成像模式。我们展示了一种计算无透镜显微内窥镜，它使用超薄裸 MCF 进行定量相位成像，具有微尺度横向分辨率和光路长度的纳米尺度轴向灵敏度。测量侧的入射复合光场由检测侧的远场散斑图案精确重建，无需任何机械运动即可在多层样品中进行数字重聚焦。通过 MCF 对相位目标和水凝胶珠进行成像，验证了定量相位重建的准确性。通过提出的成像方式，通过超薄光纤内窥镜实现人体癌细胞的三维成像，有望在临床上得到广泛应用。