Abstract: A system for locating a strand including fibers of a first woven preform material, the preform including, at the surface, strands of fibers of a second material and the strand including fibers of the first material forming a tracer. The system further includes a camera; a light source emitting a non-polarized incident beam configured to be directed towards the preform; a polarizer configured to polarize the non-polarized incident beam before interacting with the preform in order to obtain a polarized incident beam; and a crossed analyzer; the first material being chosen from among glass, aramid and aluminum oxide; the second material being chosen from among carbon and silicon carbide; the camera being configured to film a reflected beam originating from the interaction of the polarized incident beam with the preform, the reflected beam having previously crossed the crossed analyzer, so as to locate the tracer of the preform.