Fig. 1. Examples illustrating properties of coherent fibre bundles that limit the imaging capabilities of fibred endoscopy.

(a) Scanning Electron Microscopy (SEM) image of commercial coherent fibre bundle (FIGH-30-650S, Fujikura), along with (b) a uniform, flood illumination (520 nm) image of the same fibre bundle, using widefield endomicroscopy. The variable size and shape, as well as irregular distribution of the cores is apparent in both (a) and (b). (c) Binary masque and associated Delaunay triangulation of cores, identified within a uniformly illuminated image, similar to (b). (d) Intensity profile across the five cores highlighted in (c) illustrating the variations of coupling efficiency amongst different neighbouring cores. (e) Example inter-core coupling spread at 520 nm, as measured by Perperidis et al. (2017b). (f) Example raw widefield endomicroscopy image of auto-fluorescent alveoli structures from an ex-vivo, human lung. The imaged structured is heavily corrupted by the intrinsic characteristics of the imaging fibre bundle, highlighting the need for effective image reconstruction approaches. Images (a-b), (c) and (e) have been reproduced (cropped) from Figures 6, 7 and 8 respectively of the “Characterization and modelling of inter-core coupling in coherent fibre bundles" by Perperidis et al. (2017b) under the Creative Commons Attribution (CC BY) 4.0 International License (https://creativecommons.org/licenses/by/4.0).