Application of Root-MUSIC Algorithm for Enhancing Spatial Resolution of Optical Coherence Tomography Images of Optical Fibers

Properties of optical fibers are strongly related to their geometric dimensions and the properties of the materials they are made of. Therefore, for precise inspection and prediction of optical fibers properties it is desirable to perform non-destructive measurement of their internal structure. Optical concrete tomography is one of the commonly used imaging technologies that produces two- and three-dimensional images of transparent objects with high spatial resolution. However, with traditional signal processing techniques, axial spatial resolution is inversely proportional to the spectral width over which the measurement is made. Improvement in resolution by simply increasing the bandwidth is limited due to the practical properties of available optical sources and the influence of material dispersion. In this paper, we propose to apply the root-MUSIC method to optical coherence tomography interference signal processing and demonstrate that, under certain conditions, several-fold improvement in axial spatial resolution can be achieved. Experimental verification of the effectiveness of the proposed approach was carried out by measuring the geometric parameters of cross-sections of multimode and single-mode optical fibers.