A method for improving the surface quality of replica mirrors is described. The method eliminates the generally used replica finishing or coating processes which may impair the optical precision of replica optics. With the new technique, the final mirror coatings are evaporated onto the master mold and separated with the replica body to which they adhere excellently. Thus no finishing coatings are required after the replicas are separated from the master mold. The method can be applied to plastic and electroformed metal reproductions. Epoxy type resins were found to be especially suitable for making replicas of various optical elements.
GEORG HASS and WILLIAM W. ERBE, "Method for Producing Replica Mirrors with High Quality Surfaces," J. Opt. Soc. Am. 44, 669-669 (1954)