Patent ID: 7811947

Claim:
A method of manufacturing an optical substrate comprising the steps of: disposing a low refractive index layer over a transparent substrate, the refractive index of the low refractive index layer being lower than that of the transparent substrate; coating a solgel film over the low refractive index layer; and increasing the density of the solgel film by irradiation with ultraviolet rays after drying, whereby the solgel film has in the infrared absorption spectrum an absorption A of 1107±2 cm −1 in wave number attributable to Si—O—C, an absorption B of 1070±2 cm −1 in wave number attributable to Si—O—Si, and an intensity ratio A/B between the absorption A and the absorption B ranging from 0.5 to 1.0; wherein a relationship between a surface roughness of the low refractive index layer, represented by Ra1, and that of the solgel film over the low refractive index layer, represented by Ra2, is defined as Ra1>Ra2.