Characterizing Sub-Nanometre Fluctuations in Biological and Bio-inspired Materials Using Optical Coherence Tomography

Abstract

Optical coherence tomography (OCT) is a non-invasive imaging technique that generates high-resolution cross-sectional tissue images[1]. OCT is very common in ophthalmology and it is part of a group of techniques that are based on depth scans with low temporal coherence interferometry (LCI)[2]. However, the OCT technique can be widely used for different purposes. In this thesis with OCT we will be able to measure the thermal expansion of the polystyrene beads. Through the use of a laser and a broadband light source, we will target polystyrene microspheres (diameter 10 μm) doped with fluorophores. The laser hitting the microspheres will excite the fluorophores, which will release energy through heat and fluorescence. The heat will cause the microsphere to expand and by using broadband light we will measure the difference in the optical path of light between the top and bottom surface of the microsphere to get thermal expansion. The heat expansion will be analyzed for different laser powers in order to understand and verify the dilatation at different temperatures. In addition, a theoretical model will be developed to give explanations for the behaviour of the microspheres in relation to different laser powers used in the thesis