| 摘要 |
PROBLEM TO BE SOLVED: To improve the film strength and durability of a low-refractive index layer and to obtain high anti-reflection efficiency by strictly regulating the film thicknesses and refractive indices of respectively layers. SOLUTION: A middle-refractive index layer, high-refractive index layer and low-refractive index layer are successively formed from a base material side toward an air surface on the front surface of a transparent base material. The middle-refractive index layer contains the metal oxide selected from aluminum, etc., and the high-refractive index layer contains titanium oxide. The low-refractive index layer contains particulates consisting of a polymer of a fluorine-contained monomer and microvoids which do not scatter light. The refractive indices and film thicknesses of the respective layers are in ranges of the middle-refractive index layer: n3=1.60×1.70, hλ/4×0.8<n3d3<hλ/4λ1.2, the high-refractive index layer: n2=1.90 to 2.20, hλ/4×0.8<n2d2<hλ/4×1.2, the low-refractive index layer: n1=1.37 to 1.46, hλ/4×0.8<n1d1<hλ/4×1.2, where (h) and (k) respectively denote 1, 2 or 3 and (n) and (d) respectively denote the refractive indices and layer thicknesses (nm) of the respectively refractive index layers. |
