Abstract: A position sensor for sensing the position of an optical fiber with respect to the axis of a bobbin as the fiber is being wound to the bobbin. The apparatus and method illuminate the fiber being fed onto a bobbin with an externally incident energy which is internally reflected within a portion of the fiber. The position of the illuminated portion of the fiber is detected and the winding process may be controlled based on the detected position. In alternate embodiments, multiple radiation sources produce radiation with distinctive radiation characteristics and multiple sensors discriminate between and distinct radiation characteristics.