Meta-element-enhanced confocal scanning fiber fluorescence endoscopy optical system

We present a novel endoscopic imaging system integrating a hybrid metasurface-GRIN lens with a double-clad scanning fiber for confocal fluorescence imaging. To address off-axis aberrations inherent to the GRIN micro objective, we designed a phase correcting metaelement, fabricated the metasurface using silicon nitride as the dielectric, incorporated it in a benchtop endoscopy setup, and validated experimentally. This compact and thin metacorrector improves the image quality, maintaining uniform resolution across the field of view. The system uses a scanning double-clad fiber for simultaneous excitation and fluorescence collection, with detection via a double-clad fiber coupler and APD. Performance was validated using resolution targets and imaging of fluorescent beads. Our results highlight the potential of metasurface-enabled optics to enhance image fidelity in compact, portable endoscopy imaging systems.