Advances in imaging through a single optical fibre (Invited Paper)

Traditional endoscopes relay images through a bundle of optical fibres, one fibre for each pixel in the image. However, in principle even one of these fibres carries enough spatial modes to relay an entire image, but modal dispersion means the resulting image is scrambled. As a solution to this, various groups world-wide are using aberration correction techniques to create a scanning spot at the exit of the fibre to raster-scan an object, the backscattered light from this spot is measured to give an image. The current limitation is that the aberration correction depends upon the bend of the fibre, meaning that once imaging is achieved, the fibre cannot be moved. We will present our latest work on high-speed aberration correction and choice of fibre, demonstrating that bends of several 10s of degrees can be achieved without degradation in image quality. Our work opens the route to fibre-based imaging systems being deployed in dynamic situations for various inspection and healthcare applications.