Tomographie de cohérence optique plein champ pour l'endoscopie : microscopie in situ et in vivo des tissus biologiques

Abstract : The main challenges of biomedical optical imaging methods are absorption and scattering of light by the tissue, which alter the signal and limit the imaging depth. Here we are interested in Optical Coherence Tomography (OCT), a technique that selects ballistic photons using low coherence interferometry in order to virtually slice inside the tissue. The so-called Full-Field approach achieves an isotropic resolution of 1 µm, but cannot image deeper than 1 mm. It is thus impossible to image internal organs in vivo and in situ: an endoscopic system is needed. The adaptation of Full-Field OCT for endoscopy had not yet been realized. We propose a Full-Field OCT system with a flexible endoscope based on the coupling of two interferometers, one external to the probe and the other situated at the tip of the probe in contact with the tissue. This makes the probe entirely passive and insensitive to environment-induced perturbations. The flexible endoscope could access organs such as the colon. However the probe is a bundle made of thousands of optical fibers, so that a parasitic interferometric signal arises from coupling between cores and modes. We have found and tested different solutions to get rid of these stray signals and allow imaging of tissue. Concerning rigid endoscopy we have built two setups, with either one or two interferometers, and compared both methods. The probe is an assembly of graded-index lenses, it can be applied in contact on areas like skin or it can be inserted as a needle inside organs like breast. This system has been demonstrated for in vivo human skin imaging.
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Anne Latrive. Tomographie de cohérence optique plein champ pour l'endoscopie : microscopie in situ et in vivo des tissus biologiques. Optique [physics.optics]. Université Pierre et Marie Curie - Paris VI, 2012. Français. ⟨pastel-00782552⟩

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