Manufacturing of a toroidal mold for the production of polymeric lenses

The manufacture of optical molds for generating optical components in continuous or batch production has become a great challenge as freeform components are increasingly required. New manufacturing techniques have emerged to meet these technological demands; however, freeform optics present previously unseen manufacturing challenges as traditional optical workshops are designed to produce components with spherical shapes. The mold technique is widely used for batch production, but the main challenge is mold manufacturing. Therefore, the manufacturing process of a toroidal 6061 aluminum optical mold is presented, using a CNC milling machine. To evaluate the finish of the toroidal surface, null screen tests and coordinate measurements were used as these methods allow changes in slopes across the entire surface to be measured in a single evaluation, which is not possible with other tests. The results obtained show that implementation is feasible at a reduced cost, with a Peak to-Valley (PV) error of 0.1806 mm and an Root Mean Square (RMS of 0.0402 mm in the surface finish, which can be further improved by taking the polishing stage as a guide.