Two-Photon Lensless Endoscopes with Multicore Fibers

The lensless endoscope represents the ultimate limit in miniaturization of imaging tools: an image can be transmitted by numerical or physical inversion of the mode scrambling process through a bare optical fiber. Lensless endoscopes featuring multicore fibers and spatial light modulators are well adapted for nonlinear imaging as they minimally distort ultrashort pulses in the time domain as opposed to multimode fibers [1]. And in earlier works, we had addressed the issues of imaging artifacts and bending sensitivity with an helically twisted multicore fiber with a sparse and aperiodic core layout in the transverse plane [2]. However sufficiently irradiating the sample plane remained a major challenge - particularly for the imaging of dim and challenging samples such as neurons in scattering media.