Full‐Field‐of‐View Metalens Scanner Optical Module for High‐Speed Imaging Toward Miniaturized Two‐Photon Microscopy

Two‐photon microscopy is a widely used imaging technique in life sciences, offering deep‐tissue penetration and high signal‐to‐noise ratio. However, the performance of miniaturized two‐photon systems is often constrained by the bulky dimensions of conventional objectives, limited aberration correction, and a restricted field of view, which together hinder high‐quality imaging in freely behaving animals. Here, we design and experimentally validate a full‐field‐of‐view metalens scanner optical module based on a gallium nitride metasurface toward high‐speed miniaturized two‐photon microscopy. Guided by generalized Snell's law, the optimized phase profile of the full‐field‐of‐view metalens suppresses off‐axis aberrations and maintains well‐confined focusing over a 100 µm field of view. Transmission and reflection imaging experiments demonstrate that, when integrated with a piezoelectric fiber scanner, the metalens scanner optical module achieves an acquisition rate of 20 fps. The present study does not directly demonstrate two‐photon excitation, fluorescence imaging, or nonlinear optical sectioning, but rather establishes an optical foundation for the future integration of the metalens scanner module into a compact two‐photon fluorescence imaging system.