A light blocking member includes a first surface, a second surface, an outside surface and an inside surface. The first surface includes a first asymmetric opening. The second surface includes a second asymmetric opening corresponding to the first asymmetric opening. The outside surface disposed between the first surface and the second surface includes a cutting portion and an arch portion. The cutting portion connects the first asymmetric opening and the second asymmetric opening. The inside surface is disposed between the first surface and the second surface. A virtual curved surface is formed between two ends of the cutting portion, and a virtual line is formed between a central point of the virtual curved surface and a central axis of the light blocking member. Two shapes of both of the first asymmetric opening and the second asymmetric opening with respect to two sides of the virtual line are asymmetric.