New developments in two photon endoscopy

We designed and constructed a two-fiber-optic two-photon endoscope with compact two axes piezo scanner system and a miniature high 0.65 NA Grin lens objective. The high NA GRIN lens objective coupled to the fibers with a beam splitter cube represent a rigid miniaturized optical system block which is scanned as a whole by a piezo scanner allowing always an on-axes beam irradiation of the optical system. We have demonstrated the ability of our system to perform good images in the micrometer field. Fluorescence detection was able at different wavelengths between 790 and 840 nm which could allow SHG detection. The endoscope is high flexible and controllable in terms of time acquisition, resolution and magnification. Fluorescence images were acquired over a maximal 420 µm x 420 µm field-of-view.