Phys. Rev. Lett. 109, 203901 (2012)

Today's endoscopes collect high-resolution images via hundreds or thousands of individual optical fibres, which results in a bulky design with limited accessibility. The use of multimode fibre, although able to support numerous independent spatial modes, is hampered by wave distortions induced by the fibre. Youngwoon Choi and colleagues from Korea and the USA have now demonstrated endoscopic imaging using a single multimode optical fibre. They reconstructed a real image from the scrambled image transmitted by the multiple modes of light propagating down a single, 1-m-long multimode optical fibre with a 200-μm-diameter core, 15-μm-thick cladding and a 0.48 numerical aperture. Their trick was to characterize the input–output response of the fibre by recording its transmission matrix. To overcome wave distortions, the researchers employed methods of speckle imaging and turbid lens imaging. The resulting multimode fibre functioned as a self-contained, flexible three-dimensional imaging device that did not require a scanner or a lens. The researchers obtained a high spatial resolution of 1.8 μm and a field-of-view of around 200 μm.