Method for producing mold for zontal optical element

Abstract

A mold for a zonal optical element. The mold includes 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.

1 . 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 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.   
   
   
       2 . The mold according to  claim 1 , which is produced by a process comprising the steps of:
 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 said work to form the circular portion at the mold side corresponding to said circular portion on the processing surface of said work perpendicular to said rotation axis;   forming a zonal surface where said tip is relatively moved relative to said work to form a zonal surface at the mold side corresponding to said zonal surface; and   forming a corner portion between said boundary portion at the mold side and said zonal surface at the mold side wherein a raked surface of said tip is in contact with a portion corresponding to said boundary wall surface.