| 主权项 |
1. A method for manufacturing an optical element having an optical surface including a plurality of ring-shaped zones formed concentrically around an optical axis, comprising:
preparing a mold for forming an optical element, wherein the mold comprises a mold base on which a plurality of first grooves are formed concentrically by relatively driving a diamond cutting tool and the mold base for cutting the mold base, the diamond cutting tool comprising a cutting edge with a cutting face and a flank, the mold base being driven to be rotated, each of the first grooves comprising a bottom surface having a predetermined width extending in a radius direction of the first grooves, providing the mold with a material of the optical element, and molding the material into the optical element, wherein the preparing step comprises:
a first step of cutting the mold base while relatively driving the diamond cutting tool or the mold base in a direction of a rotation axis of the mold,a second step of cutting the mold base while relatively driving the diamond cutting tool or the mold base in a direction perpendicular to the rotation axis of the mold, anda third step of cutting the mold base by displacing the diamond cutting tool or the mold base simultaneously in a direction of the rotation axis of the mold and a direction perpendicular to the rotation axis of the mold while relatively driving the diamond cutting tool or the mold base, between the first and the second steps, and wherein each of the ring-shaped zones of the optical element comprises a second groove comprising a top surface having the predetermined width extending in a radius direction of the ring-shaped zones, a side surface, and a curved surface with a curvature radius in a range from 0.5 μm to 2 μm connecting the top surface and the side surface. |
