The light guide plate has a flat body. At least one of the light emission plane and the light reflection plane of the light guide plate has a number of linear reflection structures arranged in parallel along the surface. The reflection structures have a V-shaped cross section pointing outward from or inward into the surface. Each reflection structure further has at least one of its end surfaces slanting towards the other end. It is the reflection structures' slant end surfaces that provide additional collimation and enhancement to the light beams traveling through the light guide plate.