Lens-less 3D raster-scanning endomicroscopy via multicore fibers (MCFs) enables minimally invasive applications for instance auto fluorescent imaging for cancer diagnostics in the brain. However, it suffers from various issues: (i) periodic core arrangements, which result in higher diffraction orders and a limited field of view, (ii) bend-sensitive transfer functions which require constant on-line calibration, and (iii) inherent (static) differential path length differences of the individual fiber cores. To overcome these limitations, we present an MCF with 1200 aperiodically arranged cores, which is twisted to decrease dynamic bending sensitivity. Furthermore, diffractive optical elements (DOEs) were directly imprinted on the fiber facet using 2-Photon-Polymerization to compensate the inter-core-dispersion.
As a first demonstration, a simple imaging system consisting only of a camera and an MCF with an integrated DOE for phase compensation and focusing is realized for direct imaging. As a result, a flexible phase preserving fiber waveguide is realized, that can easily be included in standard microscopes to extend their field of applications to deep tissue and in vivo imaging.
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