A shutter includes a plurality of light-guiding devices each of which includes a light collector and a beam expander. The light collector includes a light-guiding plate that has a first end portion and a second end portion opposite to the first end portion in a first direction, and a plurality of light-collecting members that are disposed on the first end portion and that are arranged in the first direction. Each of the light-collecting members has a curved surface that is adapted for reflecting light beams that travel into the light-collecting member so that the light beams travel into the light-guiding plate. The beam expander is disposed on the second end portion of the light-guiding plate. When the light beams travel into the light-guiding plate, the light-guiding plate is adapted for the light beams to reflect therein, and to travel through the second end portion into the beam expander.