近日，美国康涅狄格大学的Guoan Zheng&Pengming Song及其研究团队取得一项新进展。经过不懈努力，他们研制出无透镜超薄纤维束尖端上的层叠内窥镜。相关研究成果已于2024年7月17日在国际知名学术期刊《光：科学与应用》上发表。

受合成孔径内雷达(SAR)的启发，该研究团队研制出用于超衍射极限显微内窥镜成像的合成孔径层叠内窥镜(SAPE)。SAPE通过手持无透镜纤维束尖端来记录样品的相干衍射模式。远端尖端的光纤芯调制狭窄区域内的绕射波场，模拟SAR中“机载天线”的作用。手持操作引入了尖端的位置移动，类似于飞机的运动。这些移位有助于获取心电图，并合成超出束物理极限的大虚拟孔径。研究人员通过对束的调制曲线进行低阶时空分解来减轻手部运动和纤维弯曲的影响。

该测试证明了在分辨率目标上解析548纳米线宽的能力。实现的空间带宽积约为110万有效像素，与原始光纤束相比增加了36倍。此外，SAPE的再聚焦能力使成像的扩展深度超过2厘米。SAPE的孔径合成过程超过了探针最大收集角度设定的衍射极限，为光纤内窥镜和远端芯片内窥镜在医疗诊断和工业检查等应用中开辟了新的机会。

据悉，合成孔径雷达(SAR)利用机载天线发射电磁脉冲并探测回波。当飞机穿过指定区域时，它会合成一个大的虚拟孔径以提高图像分辨率。

附：英文原文

Title: Ptycho-endoscopy on a lensless ultrathin fiber bundle tip

Author: Song, Pengming, Wang, Ruihai, Loetgering, Lars, Liu, Jia, Vouras, Peter, Lee, Yujin, Jiang, Shaowei, Feng, Bin, Maiden, Andrew, Yang, Changhuei, Zheng, Guoan

Issue&Volume: 2024-07-17

Abstract: Synthetic aperture radar (SAR) utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes. As the aircraft travels across a designated area, it synthesizes a large virtual aperture to improve image resolution. Inspired by SAR, we introduce synthetic aperture ptycho-endoscopy (SAPE) for micro-endoscopic imaging beyond the diffraction limit. SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens. The fiber cores at the distal tip modulate the diffracted wavefield within a confined area, emulating the role of the ‘airborne antenna’ in SAR. The handheld operation introduces positional shifts to the tip, analogous to the aircraft’s movement. These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle’s physical limit. We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle’s modulation profile. Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target. The achieved space-bandwidth product is ~1.1 million effective pixels, representing a 36-fold increase compared to that of the original fiber bundle. Furthermore, SAPE’s refocusing capability enables imaging over an extended depth of field exceeding 2cm. The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe’s maximum collection angle, opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.

DOI: 10.1038/s41377-024-01510-5

Source: https://www.nature.com/articles/s41377-024-01510-5