Patent ID: 6846137

Claim:
Apparatus for forming a precision mold for a micro-sized optical article having an optical radius, comprising: a tool holder having an axis of rotation; a substrate; and a forming element disposed in said tool holder for milling said substrate, said forming element having a half-radius rotatable hardened cutting member having a single half-optical-radius continuous cutting edge and arranged for milling a predetermined shaped mold cavity in said substrate, said half-radius cutting member comprising a contoured front cutting face with the single continuous cutting edge for penetrating said substrate and a rear face having a clearance surface sufficiently removed from said predetermined shaped mold cavity during milling to prevent forming drag marks therein, an intersection of said front face, said cutting edge, and said rear face defining an axis of rotation of said half-radius rotatable hardened cutting member, said axes of rating being aligned to within 5 microns of one another.