Patent ID: 6924037

Claim:
A manufactured article, comprising: a transparent substrate; an antireflection coating on at least one face of the transparent substrate, said antireflection coating made of a stack of thin layers of dielectric material having alternately high and low refractive indices, wherein the stack comprises, in succession: a high-index first layer, having a refractive index n 1 of between 1.8 and 2.2 and a geometrical thickness e 1 of between 5 and 50 nm; a low-index second layer, having a refractive index n 2 of between 1.35 and 1.65 and a geometrical thickness e 2 of between 5 and 50 nm; a high-index third layer, having a refractive index n 3 of between 1.8 and 2.2 and a geometrical thickness e 3 of between 70 and 120 nm; a low-index fourth layer, having a refractive index n 4 of between 1.35 and 1.65 and a geometrical thickness e 4 of at least 80 μm, wherein the antireflection stack uses, at least for its high-index third layer, silicon nitride or aluminium nitride to undergo a heat treatment of bending, toughening, or annealing.