In one embodiment, a photo-darkening resistant optical fiber includes a waveguide having a numerical aperture less than 0. The scanning module of the image scanner includes a base, a reflective mirror stand, a shaft, a reflective mirror member and a gear set. A first, a second, and a third selectively engagable torque-transmitting mechanism are included. A second terminal electrode is electrically connected to the conductive trace of the second substrate, and surface of the second terminal electrode is orthogonal to the longitudinal axis of the conductive trace of the second substrate.