Near perfect focusing through multimode fibres

Holographic, multimode fibre (MMF) based endoscopes envision high-quality in-vivo imaging inside previously inaccessible structures of living organisms, amongst other perspective applications. Within these instruments, a digital micro-mirror device (DMD) is deployed in order to holographically synthesise light fields which, after traversing the multimode fibre, form foci at desired positions behind the distal fibre facet. When applied in various imaging modalities, the purity and sharpness of the achieved foci are determinant for the imaging performance. Here we present diffraction-limited foci, which contain in excess of 96% of optical power delivered by the fibre which, to the best of our knowledge, represents the highest value reported to date. Further, we quantitatively study the impact of various conditions of the experimental procedure including input polarisation settings, influence of ghost diffraction orders, light modulation regimes, bias of the calibration camera and the influence of noise. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Holographic, multimode fibre-based endoscopes offer high-quality in-vivo imaging and have promising applications. Researchers have achieved diffraction-limited foci with high purity and sharpness, representing the highest reported optical power delivery. The study also examines the impact of various experimental conditions on imaging performance.