Patent ID: 10073202

Abstract:
A near-infrared cut filter has an optical multilayer provided on at least one main surface of a transparent substrate, in which the optical multilayer is formed of a high-refractive index layer having a refractive index of 2.0 or more, and a low-refractive index layer having a refractive index of 1.6 or less at a wavelength of 500 nm, and the optical multilayer has a repeating structure of (anQH, bnQL, cnQH, dnQL)^n when a QWOT at the wavelength of 500 nm of the high-refractive index layer is set to QH, and a QWOT at the wavelength of 500 nm of the low-refractive index layer is set to QL, in which an average value of the an is not less than 1.5 nor more than 2.5, and a value obtained by averaging average values of the respective bn, cn, and dn is 1.0 or less.