Miniaturized two-photon microscope based on a flexible coherent fiber bundle and a gradient-index lens objective

TLDR

The authors introduce a miniature, flexible two‑photon microscope that couples a 30,000‑core coherent fiber bundle to a gradient‑index lens objective. The system scans a two‑photon laser focus across the fiber bundle entrance, sequentially coupling light into individual cores, and detects the resulting fluorescence through the bundle. The microscope resolves micrometer‑scale fluorescent beads and pollen grains and successfully images fluorescently labeled blood vessels in the rat brain in vivo.

Abstract

We present a miniature, flexible two-photon microscope consisting of a fused coherent optical fiber bundle with 30,000 cores and a gradient-index lens objective. The laser focus of a standard two-photon laser-scanning microscope was scanned over the entrance surface of the fiber bundle, resulting in sequential coupling into individual cores. Fluorescent light was detected through the fiber bundle. Micrometer-sized fluorescent beads and pollen grains were readily resolved. In addition, fluorescently labeled blood vessels were imaged through the fiber bundle in rat brain in vivo.