Multimode-fibre calibration guided by fibre mode correlations for imaging through bending fibres

The need for seeing within structures in medical and industrial settings has made endoscopic imaging an invaluable tool. Traditional endoscopes have limited capabilities as the access points and spaces in which imaging is to be performed get smaller. For this reason, research into single-fibre-endoscopy, where hair-width optical fibres can be used in imaging, has gained a sizeable scientific foothold over the last decade. In the case of multimode fibres, the spatial information density is maximised for a given fibre diameter, field of view, and use wavelength. The trade off here is that without physical separation between the modes of fibres, as is the case for fibre bundles, the image scrambles enroute from the fibre tip to the near-side detector and requires prior calibration for imaging to be performed. A major downside of this calibration is that it is specific to the fibre shape and bending the fibre often requires a new calibration. We investigate a way to hop between calibrations in a calibration library which enables live imaging through a handheld dynamically bent fibre live. We also look at the fibre mode coefficients under different bends offering insight into the best way to form such a library.