Lens forming metal mold, lens forming method and pickup device

A metal mold for forming a lens, the lens being made of resin and the lens having a first lens surface and a second lens surface, the second lens surface formed on a reverse side of the first lens surface, the metal mold comprising:

• a first inner metal mold which forms the first lens surface and a first flat surface portion, the first flat surface portion being formed around an outer periphery of the first lens surface, and the first flat surface portion being a ring-shaped surface perpendicular to an optical axis of the lens;
• a first outer metal mold which forms a second flat surface portion, the second flat surface portion being formed around an outer periphery of the first flat surface portion and positioned closer to a side of the second lens surface than the first flat surface portion, and the second flat surface portion being a ring-shaped surface perpendicular to the optical axis of the lens;
• a second inner metal mold which forms the second lens surface and a third flat surface portion, the third flat surface portion being formed around an outer periphery of the second lens surface, and the third flat surface portion being a ring-shaped surface perpendicular to the optical axis of the lens, and
• a second outer metal mold which forms a fourth flat surface portion, the fourth flat surface portion being formed around an outer periphery of the third flat surface portion and positioned closer to a side of the first lens surface than the third flat surface portion, and the fourth flat surface portion being a ring-shaped surface perpendicular to the optical axis of the lens,
• wherein a first protruded portion which forms a first concaved portion on the lens is formed all around an outer periphery of the first inner metal mold, the first concaved portion serving as clearance for a burr which can occur at a boundary of the first outer metal mold and the first inner metal mold when the lens is formed, and
• wherein a second protruded portion which forms a second concaved portion on the lens is formed all around an outer periphery of the second inner metal mold, the second concaved portion serving as clearance for a burr which can occur at a boundary between the second outer metal mold and the second inner metal mold when the lens is formed.