The present disclosure provides an optical coherence tomography (OCT) system for characterising first and second areas of interest of a material. The OCT system comprises first and second optical elements in use positioned at the first and second areas of interest of the material. The first and second optical elements are at least partially transmissive for electromagnetic radiation. The system further comprises first and second scanning heads in use positioned at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material at the first and second areas of interest. In addition, the system comprises at least one detector optically coupled to the first and second scanning heads. The first and second optical elements are arranged such that respective reference radiation associated with the first and second optical elements is generated by reflection at interfaces of or at the first and second optical elements, respectively, and the first and second optical elements are arranged or positioned such that an optical path length difference between the reference radiation associated with the first optical element reference radiation and electromagnetic radiation that interacted with the material associated with the first optical element differs from an optical path length difference between the reference radiation associated with the second optical element and electromagnetic radiation that interacted with the material associated with the second optical element.
