Improved Two-Step Replication Process for Producing Precision Optical Mirrors

Production of precision optical mirrors by replication requires molds or mandrels of the complementary shape. For example, replicating a concave mirror requires a convex mandrel. Convex shapes are difficult to fabricate and test since they do not focus light. Convex mandrels are therefore costly when they are available. Their sizes are limited to 1-2 meters. Two-step or double replication is well known in the art. In the traditional method, a specific polymer resin system with fillers is used to replicate an existing concave mirror (designated as “mother”) to produce a convex intermediate designated as “daughter.” The same material is then used to replicate the daughter, creating a third-generation concave that is designated as “granddaughter.”