A backlight module includes a light box, at least one light guide tube, and at least one light source. The light box has a light exit side. The light guide tube has a plurality of microstructures which are spaced apart along a length of the light guide tube. The light guide tube and the microstructures are disposed in the light box in a particular arrangement so that the microstructures are placed substantially in a matrix array within the light box. The light source is disposed adjacent to the light guide tube, and is operable so as to emit a light beam to the light guide tube. The microstructures disperse the light beam from the light guide tube.