Method for producing mold for zonal optical element

Abstract

A method for producing a mold for a zonal optical element having a circular portion having a circular shape taking an optical axis as a center viewed from a plane surface; at least one zonal surface formed around the circular portion in a ring form; and boundary wall surfaces connecting the circular portion with the zonal surface or connecting the zonal surfaces with each other is produced by a stage for forming a circular portion where while rotating a work around a rotation axis corresponding to the optical axis as a center, a tip is relatively moved relative to the work to form the circular portion at the mold side corresponding to the circular portion on the processing surface of the work perpendicular to the rotation axis; a stage for forming a zonal surface where the tip is relatively moved relative to the work to form a zonal surface at the mold side corresponding to the zonal surface; and a stage for forming a corner portion between the boundary portion at the mold side and the zonal surface at the mold side wherein a raked surface of the tip is in contact with a portion corresponding to the boundary wall surface.

1 . A zonal optical element produced by using a mold, having a circular portion having a circular shape taking an optical axis as a center viewed from a plane surface; at least one zonal surface formed around the circular portion in a ring form; and boundary wall surfaces connecting said circular portion with the zonal surface or connecting the zonal surfaces with each other;
 said mold comprising:   a circular portion at the mold side corresponding to the circular portion possessed by the zonal optical element;   at least one zonal surface at the mold side corresponding to the zonal surface possessed by the zonal optical element; and   at least one corner portion between said boundary portion at the mold side and said zonal surface at the mold side wherein said corner portion is in a sharpened state formed by bringing a raked surface of a tip into contact with a portion a portion corresponding to said boundary wall surface.