Abstract: A method of producing an optical element, in which a first and a second die are cooperated with each other so as to press-mold a material in order to produce an optical element including a lens portion, the first die has a circular cross-sectional shape, and the second die defines therein an interior space having a polygonal cross-sectional shape with respect to the direction of die-fastening, the first die is adapted to enter into the interior space of the second die in the direction of die-fastening in the interior space so to press-mold the material in order to form the lens surface while the material is bulged out through gaps between the first die and the second die around the lens surface whereby forming protrusions. An optical element and a mold assembly for an optical element are also provided.

Abstract: A lens is manufactured by hardening soft material filled inside a molding tool by cooling. The lens includes a convex lens portion having an optical axis, and a marking portion located outside of an effective diameter of the lens portion. The shape or the position of the marking portion is set to prevent deformation of the marking portion by contact with the molding tool due to shrinkage of the material during cooling.

Abstract: An optical element being high in productivity and capable of ensuring a large bonding area, and a production method of the optical element. At mold opening when a top part (120) provided with a round portion (121) moves upward, a preform is placed in an inner space the interior of which is formed by a rectangular sleeve (110) and the round portion (131) of a bottom part (130). At mold clamping when the top part (120) moves downward, the preform is pressurized. That is, a convex lens portion is transferred by the concave curved surface (122) and the edge surface (123) of the round portion (121) and the concave curved surface (132) and the edge surface (133) of the round portion (131). The four side surfaces of an optical element (1) are transferred by the inner wall surface (110a) of the sleeve (110).

Abstract: A lens is manufactured by hardening soft material filled inside a molding tool by cooling. The lens includes a convex lens portion having an optical axis, and a marking portion located outside of an effective diameter of the lens portion. The shape or the position of the marking portion is set to prevent deformation of the marking portion by contact with the molding tool due to shrinkage of the material during cooling.