Patent ID: 8916234

Claim:
A method of making a thin film structure comprising alternating high refractive and low refractive index layers, the method comprising: a) depositing a first layer of film on a substrate, the first layer having a high refractive index, wherein the refractive index is greater than 2.0; b) depositing a second layer of film onto the first layer of film, wherein the second layer of film is a material modified to have a different refractive index from the unmodified material, the second layer having a low refractive index, wherein the ratio of the low refractive index to the refractive index of the first layer is no more than 0.46; and c) depositing a third layer of film onto the second layer of film, the third layer having a high refractive index, wherein the refractive index is greater than 2.0, wherein the layers are of the same material.