Shape sensing using two outer cores of multicore fiber and optical frequency domain reflectometer

A method, i.e., vector projections, using two outer cores of multicore fiber without calibration and OFDR was proposed to realize three-dimensional (3D) shape sensing. A complement for apparent curvature vector method using three outer cores of multicore fiber was also proposed to determine the viable fiber cores arrangement for shape sensing. Compared with apparent curvature vector method, the vector projections method based on two outer cores of multicore fiber, decreased the number of fiber cores, which eliminating the requirement for fiber cores arrangement. Based on these methods, a reconstructed shape with a higher accuracy was obtained based on integrating all fiber shape from all cores combinations. The maximum root-mean-square errors (RMSEs) of end position for the vector projections and apparent curvature vector method were 13.1 and 12.4 mm, while a higher accuracy, i.e., maximum RMSEs of 11.9 and 12.1 mm, was obtained based on the integrated fiber shapes.