New ways to look through multimode optical fibres

Hair-thin strands of multimode optical fibre (MMF) can operate as ultra-low footprint endoscopes - delivering subcellular resolution images from deep inside the body at the tip of a fine needle. However, images transmitted through MMFs are unrecognisably distorted. Here we present two new ways to unscramble this light and recover images. Firstly, we describe a new in-situ calibration technique requiring access to only the input end of the fibre promising a way to image through flexible fibres. Secondly, we describe the design of a new optical element - an 'optical inverter' - that can unscramble all modes in parallel, offering the potential of single-shot and super-resolution imaging through MMFs.