Method for fabricating a plastic optic element injection mold

A method for fabricating an injection mold suitable for forming a plastic optical component comprising the steps of:

• fabricating a plurality of duplicate positive masters of the optical component from a first metal;
• polishing each of said plurality of duplicate positive masters to an optical surface finish;
• placing each of said duplicate positive masters in an electroforming bath;
• electroforming a shell of a second metal on each of said duplicate positive masters to a predetermined thickness;
• scribing an axial mold line on each of said electroformed shells;
• cutting each of a set of positive masters along predetermined cutting lines to form a set of negative master segments, wherein each of negative master segments comprises a portion of the electroformed shell about a positive master;
• trimming each of said negative master segments by removing an overlap region comprising a portion of the electroformed shell interposed between one of said predetermined cutting lines and said mold parting line;
• separating each of said positive master segments from each of said negative master segments to form a set of negative master mold segments;
• and
• building up a mold from a set of negative master mold segments, wherein said set of negative master mold segments completely defines the plastic optical component.

A method for fabricating an injection mold for a plastic optical component comprising the steps of:

• forming two exact metal models of the plastic optic component to be produced by the mold;
• forming a metal shell on each of said metal models;
• defining a line through each of said shells, which lines delineate upper and lower portions of said shells, said upper portions being equal and said lower portions being equal;
• cutting one of said shells along a cut line above its delineating line and the other of said shells along a cut line below its delineating line;
• removing the portion of said one shell below its cut line and the portion of said other shell above its cut line;
• removing the part of the metal mold above its cut line from said one shell and the part of the metal mold below its cut line from said other shell;
• trimming away the segments of each shell between its delineating line and its cut line;
• and
• combining the remaining portions of said one and said other shell to form the injection mold.