Polarization-insensitive micro-metalens for high-resolution and miniaturized all-fiber two-photon microendoscopic fluorescence imaging
Abstract
A high transmission efficiency and polarization-insensitive micro-metalens with a 100 μm diameter has been designed for two-photon excited microendoscopic fluorescence imaging. We theoretically calculate the vector field near the focal region of a high NA objective lens to confirm the effectiveness and feasibility of the micro-metalens. The simulation results of the designed micro-metalens are essentially in agreement with that of an objective lens under linearly or radially polarized hollow Gaussian beam (HGB) illumination. A tightly focused spot with an FWHM of 0.56 μm and a beam quality of 72.54% is obtained when the designed micro-metalens is illuminated by radially polarized 5-order HGB at wavelength 915 nm and the corresponding lateral resolution of the two-photon fluorescence signal is 0.39 μm. Moreover, this ultrathin micro-metalens can be fabricated onto a fiber tip and directly penetrate into tissues. This miniaturized imaging system can provide a compact all-fiber two-photon excitation microendoscopic imaging system.
- Publication:
-
Optics Communications
- Pub Date:
- August 2019
- DOI:
- 10.1016/j.optcom.2019.04.027
- Bibcode:
- 2019OptCo.445...76Y
- Keywords:
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- Micro-metalens;
- Polarization-insensitive;
- High-resolution;
- All-fiber;
- Microendoscopic