Nano-optic endoscope for high-resolution optical coherence tomography in vivo


Acquisition of high-resolution images from within internal organs using endoscopic optical imaging has numerous clinical applications. However, difficulties associated with optical aberrations and the trade-off between transverse resolution and depth of focus significantly limit the scope of applications. Here, we integrate a metalens, with the ability to modify the phase of incident light at subwavelength level, into the design of an endoscopic optical coherence tomography catheter (termed nano-optic endoscope) to achieve near diffraction-limited imaging through negating non-chromatic aberrations. Remarkably, the tailored chromatic dispersion of the metalens in the context of spectral interferometry is utilized to maintain high-resolution imaging beyond the input field Rayleigh range, easing the trade-off between transverse resolution and depth of focus. We demonstrate endoscopic imaging in resected human lung specimens and in sheep airways in vivo. The combination of the superior resolution and higher imaging depth of focus of the nano-optic endoscope is likely to increase the clinical utility of endoscopic optical imaging.

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Fig. 1: Endoscopic OCT catheter designs.
Fig. 2: Nano-optic endoscope design and fabrication.
Fig. 3: Optical characterization of the nano-optic endoscope and conventional OCT catheters.
Fig. 4: Resolution measurements of the nano-optic endoscope.
Fig. 5: Comparison of OCT images acquired using the nano-optic endoscope and a conventional OCT catheter.
Fig. 6: In vivo and ex vivo endoscopic OCT using the nano-optic endoscope.


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This project was supported by funding from the National Institutes of Health (R01CA167827, R01HL133664 awarded to M.J.S.), Air Force Office of Scientific Research (MURI: FA9550-14-1-0389, FA9550-16-1-0156 awarded to F.C.), and the LUNGevity Foundation/Upstage Lung Cancer. Y.-W.H. and C.-W.Q. are supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Competitive Research Program (CRP award no. NRF-CRP15-2015-03). This work was performed in part at Harvard’s Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), supported by the National Science Foundation (NSF) under NSF award no. 1541959. Y.-W.H. thanks Y.-C. Chen for helpful comments and discussions.

Author information




H.P., M.K. and Y.-W.H. carried out analyses, fabricated endoscopes, and planned and executed the experiments. Z.S. performed computational analysis for metalens design. L.P.H., M.J.S. and H.P. performed the ex vivo and in vivo imaging. M.J.S. and D.C.A. implemented the OCT system. H.P. and D.C.A. processed imaging data. V.D. and A.Z. assisted with experiments and fabrication. H.P. prepared the original manuscript with significant contributions from M.K., Y.-W.H. and C.-W.Q. M.J.S. and F.C. supervised the project and participated in manuscript preparation.

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Correspondence to Federico Capasso or Melissa J. Suter.

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Competing interests

H.P., M.K., Y.-W.H., Z.S., M.J.S. and F.C. are the inventors on a relevant provisional patent application (application number: 62598455) owned by Harvard University and Massachusetts General Hospital.

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Supplementary Information

Supplementary Information

Additional information on the phase profile calculation for the metalens used, computational analysis of the nanopillars, endoscope wave analysis, analytic approach to spectral interferometry with a chromatic lens, endoscope characterization and the OCT imaging system implemented in the work

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Pahlevaninezhad, H., Khorasaninejad, M., Huang, YW. et al. Nano-optic endoscope for high-resolution optical coherence tomography in vivo. Nature Photon 12, 540–547 (2018).

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