Light guide plate having uniform light emission and backlight module

A backlight module, comprising:

• a light guide plate made of transparent material, and comprising:
• a light emitting surface;
• a bottom surface opposite to the light emitting surface;
• a light incident surface;
• and
• a side surface opposite to the light incident surface;
• wherein the bottom surface is imaginarily divided into a plurality of rectangular portions along a direction from the light incident surface to the side surface, the shapes of the rectangular portions are the same as each other, the areas of the rectangular portions are the same as each other, each of the rectangular portions comprises a plurality of microstructures, the rectangular portions are assigned serial numbers along the direction from the light incident surface to the side surface, the microstructure densities of the rectangular portions increase when the serial numbers of the rectangular portions increase, the microstructure density in each of the rectangular portions between the first rectangular portion and the last rectangular portion satisfies the formula:
• ai=(ai−1+ai+ai+1)/3, where i represents the serial number of the rectangular portion, N represents the total number of the rectangular portions, 1<i<N, and i and N are natural numbers, and
• at least one light source facing the light incident surface.