Fabrication of optical mirrors by epoxy replication

The master, which contains the desired optical surface, is epoxied to the substrate. When the pieces are separated, the epoxy resin layer is transferred to the substrate producing a replicated mirror. Epoxy replication is an efficient and low-cost way to fabricate optical mirrors. The surface figure accuracy will decrease with the increase in mirror size due to the characteristic of the epoxy resin, and there is no effective way to correct the surface figure aberrations after replication. Finite element analysis was used to simulate the replication process and optimize the thickness of the master for better surface figure accuracy. A multilayer film compatible with Magneto-Rheological Finishing was also developed. A parabolic replicated mirror with a diameter of Φ180 mm and a plane replicated mirror with a diameter of Φ500 mm were fabricated within 5 and 10 days, respectively. The precision shape (RMS < 20 nm) and low surface roughness (Rq=0.6 nm) were both achieved.