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 <i>in vivo</i>.
© 2004 Optical Society of America
(060.2310) Fiber optics and optical communications : Fiber optics
(110.2350) Imaging systems : Fiber optics imaging
(110.2760) Imaging systems : Gradient-index lenses
(180.2520) Microscopy : Fluorescence microscopy
Werner Göbel, Jason N. D. Kerr, Axel Nimmerjahn, and Fritjof Helmchen, "Miniaturized two-photon microscope based on a flexible coherent fiber bundle and a gradient-index lens objective," Opt. Lett. 29, 2521-2523 (2004)