Instrumentation et méthodes d’analyse appliquées à l’évaluation du développement rétinien chez le souriceau par tomographie par cohérence optique

Ce mémoire par article décrit le développement d’instrumentation optique et d’algorithmes qui ont servi à l’étude du développement rétinien du modèle murin par tomographie par cohérence optique (OCT de l’anglais, Optical Coherence Tomography). Le document est divisé en deux parties importantes. Le Chapitre 1 introduit les bases théoriques nécessaires à la compréhension de la problématique, alors que le Chapitre 2 décrit les outils qui ont été développés ou adaptés durant le projet pour mener à bien les expériences. Spécifiquement, les particularités du système optique développé pour permettre la focalisation d’un faisceau sur la rétine, maximiser le signal et minimiser l’impact des aberrations sphériques et de dispersion sur la qualité de l’image sont détaillées. Les algorithmes de traitement de signal OCT permettant la visualisation une tomographie sont aussi détaillés. La seconde partie est un manuscrit en préparation pour soumission au journal Investigative Ophthalmology & Visual Science pour publication. Le but de ce manuscrit est d’établir des chartes de référence détaillant la croissance et la maturation morphologique des tissus rétiniens de la souris wild-type (129S1/SvImJ) entre 7 et 21 jours de vie (Chapitre 3). L’article détaille l’algorithme de traitement d’images et de segmentation dédié à la quantification de l’épaisseur des tissus rétiniens dans le temps. Enfin, un aperçu des travaux de recherche rendus possibles par les outils développés dans ce projet est présenté. Cette section montre entre autres le potentiel de ces outils pour étudier des maladies développementales de la rétine.This master thesis is including a manuscript submitted for publication and is divided into two sections. In particular, the document describes the development of optical instrumentation and methodological tools to study the retinal development in an animal model through optical coherence tomography (OCT). The first section is divided into two chapters. Chapter 1 describes the theoretical basis and the problem to solve. Chapter 2 describes the tools developed or adapted to enable the performance of the experiments. In particular, this chapter details the optical system designed to allow the optimal focalization of the light beam onto the retina, which maximizes the signal and minimizes the impact of spherical aberrations and light dispersion on image quality. Also, the processing algorithm used to segment retinal tissues from OCT tomography is discussed. The second section is divided into two chapters. Chapter 3 is a manuscript that was submitted for publication to Investigative Ophthalmology & Visual Science. This work describes the growth and maturation of specific retinal layers in the wild type mouse (129S1/SvImJ) between 7 and 21 days of life. The manuscript also describes the image processing and segmentation algorithm that allows the quantification of the thickness of the layers over time. Then, Chapter 4 describes specific research projects where these OCT imaging tools can be applied. Specifically, this chapter shows the potential to study retinal developmental diseases as well as perfusion methods

All-fiber few-mode optical coherence tomography using a modally-specific photonic lantern

ABSTRACT: Optical coherence tomography (OCT) was recently performed using a few-mode (FM) fiber to increase contrast or improve resolution using a sequential time-domain demultiplexing scheme isolating the different interferometric signals of the mode-coupled backscattered light. Here, we present an all-fiber FM-OCT system based on a parallel modal demultiplexing scheme exploiting a novel modally-specific photonic lantern (MSPL). The MSPL allows for maximal fringe visibility for each fiber propagation mode in an all-fiber assembly which provides the robustness required for clinical applications. The custom-built MSPL was designed for OCT at 930 nm and is wavelength-independent over the broad OCT spectrum. We further present a comprehensive coupling model for the interpretation of FM-OCT images using the first two propagation modes of a few-mode fiber, validate its predictions, and demonstrate the technique using in vitro microbead phantoms and ex vivo biological samples

Search for Scalar Diphoton Resonances in the Mass Range 65−60065-600 GeV with the ATLAS Detector in pppp Collision Data at s\sqrt{s} = 8 TeVTeV

A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using $20.3\text{}\text{}{\mathrm{fb}}^{-1}$ of $\sqrt{s}=8\text{}\text{}\mathrm{TeV}$ $pp$ collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches