Patent ID: 7811684

Claim:
An optical member having antireflection performance comprising: a base, a layer containing silicon oxide in a molar content of 40% or more which is the largest content among contents of all components, with the layer containing silicon oxide being formed directly on the base; an amorphous oxide layer containing aluminum oxide in a molar content of 50% or more, with the amorphous oxide layer being formed directly on the layer containing silicon oxide; and a plate crystal layer formed on the surface of the amorphous oxide layer from plate crystals containing aluminum oxide in a molar content of 50% or more, wherein the surface of the plate crystal layer has a shape of irregularities, and wherein a refractive index n b of the base, a refractive index n s of the layer containing silicon oxide, and a refractive index n a of the amorphous oxide layer containing aluminum oxide meet a relation of n b ≧n s ≧n a .