Spectral Low Coherence Interferometry: A Complete Analysis of the Detection System and the Signal Processing

Low coherence interferometry (LCI) is an optical technique in which light is used as an instrument to obtain high resolution optical images in a great diversity of materials. It is possible to find in the literature, a variety of configurations with different names, based on the same principle: low coherence reflectometry (OLCR), optical coherence tomography (OCT), white light interferometry (WLI), are only some examples of this. The main idea of this technique is to measure the echo time delay of backscattered light in the sample through the characterization of the interference intensity obtained when the light coming from the sample and the light reflected in a reference surface overlap. When a low coherence source is used, the interference signal is temporally and spatially localized, so it is possible to use this property to obtain distance values or parameters related to the time of flight of the light, reflected in different sections of a sample.