OPTICAL MEMBER WITH THICK FILM

摘要

PROBLEM TO BE SOLVED: To form a thick film on a substrate without affecting the antireflection effect of the resulting optical member. SOLUTION: An optical member has a substrate having a refractive index Ns and a thick film formed on the substrate and having a refractive index Nh different from the refractive index Ns to light of a wavelength λ in the range of 200 nm to 2 μm and a thickness of >=λ/Nh (200 nm<=λ<=2 μm) and has a middle layer which satisfies the expressions NsNf>Nh (1) and Nf.Df=0.25λ (2) (where Ns is the refractive index of the substrate; Nh is the refractive index of the thick film; Nf is the refractive index of the middle layer; and Df is the thickness of the middle layer) between the substrate and the thick film.