This work establishes a new class of endoscopic optical imaging catheters, termed nano-optic endoscopes, that uses metalenses with the ability to modify the phase of incident light at sub-wavelength level. We utilize the control of the phase and chromatic dispersion of the output beam to address two persistent limitations of optical imaging system, namely optical aberrations and the trade-off between transverse resolution and depth-of-focus. High-resolution endoscopic imaging at an extended depth-of-focus is demonstrated in resected human lung specimens and the airways of sheep in vivo. The nano-optic endoscope elevates the capabilities of endoscopic imaging in examining pathological changes in luminal tissue.
