From stars to bugs

Proteus is a multi-disciplinary project that aims to deliver "Optical Molecular Sensing and Imaging in the distal lung for critically-ill ventilated patients". The aim can be achieved through fibre-based multiplexed optical sensing using surface enhanced Raman spectroscopy (SERS), and fluorescent imaging through the same optical-fibre bundle.
Although endoscopy is routinely employed in hospital departments using a multi-mode fibre bundle, we are exploring aperture synthesis imaging for delivering coherent imaging through an optical fibre. Aperture synthesis is astronomy delivers high resolution images of targets that are too small to be resolved by the largest telescope on Earth. The goal is achieved by combining interferometrically the light of separate telescopes as if they were part of a single giant telescope.
An aperture synthesis endoscope would combine separate fibre cores interferometrically. Sensing fibres could be interspersed with imaging fibres without degradation in the image quality. Similar imaging capabilities of a 30,000-cores endoscopic fibre bundle could be achieved with a 180-cores coherent bundle that would be much smaller than a conventional endoscope and allow access to smaller organs out-of-bound to current technology. The ability to manipulate the optical wavefront will also enable multi-plane lens-less imaging and time-resolved 3D localisation of structures within the tissue, particularly when combined with two-photon excited fluorescence. Finally aperture synthesis improves the lateral resolution of a microscope by a factor of two allowing super-resolved images at high frame rate from the endoscope.