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Endoscopic imaging systems based upon bundles of optical fibers are commonplace across medical and industrial applications. However, in principle even just one of these optical fibers transports enough spatial modes to transmit an entire image, the problem being that modal dispersion scrambles the output such that any input image becomes unrecognizable. Many groups across the world are trying to tackle this problem with various approaches. Our approach uses the measure transmission-matrix of the fiber to calculate the required sequence of patterned input beams to create a raster scanned spot at the output, to illuminate the scene. The corresponding sequence of backscattered light is recorded, again through a fiber, and the resulting image reconstructed. This approach is limited by the large size of the transmission matrix which potentially needs to be updated whenever the fiber is moved, typically taking 10 minutes to hours. Here we report a measurement and computation approach that produce a scanning spot in the far field of a needle mounted optical fiber in less than one minute. This rapid approach allows us to recalibrate the system for different fiber configurations and switch between them to account for fiber movement, without interrupting the live image feed. We apply this approach to minimally invasive imaging in low photon-number configurations, showing video rate acquisition at ranges of a meter, or more, from the distal end of the fiber.
Mekhail et al. (Wed,) studied this question.