Compression molding of glass freeform optics using diamond machined silicon mold

In precision glass molding of freeform optics, mold material selection and mold fabrication are two major challenges. In this letter, we propose a method to fabricate silicon molds for micro freeform optics using ultraprecision diamond machining. Specifically, two microlens arrays and a kinoform lens molds were created on a 5.0mm thick silicon wafer using ultraprecision diamond machining. The fabricated silicon molds were coated with a graphene-like carbon coating using chemical vapor deposition to prevent glass to silicon adhesion. To demonstrate the functionality of the single point diamond machined silicon molds, glass micro components were fabricated using precision compression molding. Compared with conventional grinding process required for tungsten carbide, the method investigated in this research provides a more flexible, faster and affordable alternative to fabricate molds for complex precision glass freeform optics.