Method for preparing a mold part useful for transfering a coating onto an optical substrate

A method for preparing at least one mold part of a two-part mold comprising the steps of : (a) providing a two-part mold having opposed optical surfaces intended to define therebetween a molding cavity; (b) forming on at least one of the optical surfaces of the mold a hydrophobic top coat ; (c) forming an antireflecting coating onto the hydrophobic top coat; wherein, - the antireflecting coating comprises a stack of dielectric material layers of alternate high and low refractive indices, and - the first dielectric material layer deposited on the hydrophobic top coat is deposited using a two stage process in which, in a first stage, a first sub-layer of dielectric material is deposited by vacuum deposition and, thereafter, in a second stage, a second sub-layer is deposited by ion assisted vacuum deposition.