Near-infrared cut filter

A near-infrared cut filter comprising a transparent substrate and an optical multilayer provided on at least one of principal surfaces of the transparent substrate,

• wherein the optical multilayer comprises a repeated layered structure having:
• a high-refractive index layer having a refractive index at a wavelength of 500 nm of 2.0 or higher;
• a middle-refractive index layer having a refractive index at the wavelength of 500 nm of 1.6 or higher and lower than the refractive index of the high-refractive index layer;
• and
• a low-refractive index layer having a refractive index at the wavelength of 500 nm of lower than 1.6,
• the repeated layered structure being expressed by a repeat of (LMHML)̂n (n is a natural number of 1 or more) where the high-refractive index layer is H, the middle-refractive index layer is M, and the low-refractive index layer is L,
• wherein the optical multilayer comprises
• a transmission band where a mean transmittance is 85% or higher in a wavelength range from 400 nm to 700 nm, and
• a stopband having a width of 100 nm to 280 nm where a mean transmittance is 10% or lower in a wavelength range from 750 nm to 1100 nm, and
• wherein the high-refractive index layer, the middle-refractive index layer, and the low-refractive index layer are stacked so that,
• where a QWOT (Quarter-wave Optical Thickness) of the high-refractive index layer of the optical multilayer is TH, a QWOT of the middle-refractive index layer is TM, and a QWOT of the low-refractive index layer is TL,
• in a case where the refractive index of the middle-refractive index layer is equal to or higher than an intermediate value between the refractive index of the high-refractive index layer and the refractive index of the low-refractive index layer,
• 2TL/(TH+2TM) falls within a range from 100% to 70% when a maximum value of 2TL/(TH+2TM) in which there is no part where a transmittance locally decreases by 5% or more in the wavelength range of 400 nm to 700 nm in spectral characteristics under a vertical incident condition is set to 100% and a minimum value thereof is set to 0%, and
• in a case where the refractive index of the middle-refractive index layer is lower than the intermediate value between the refractive index of the high-refractive index layer and the refractive index of the low-refractive index layer,
• (2TL+2TM)/TH falls within a range from 100% to 70% when a maximum value of (2TL+2TM)/TH in which there is no part where the transmittance locally decreases by 5% or more in the wavelength range of 400 nm to 700 nm in the spectral characteristics under the vertical incident condition is set to 100% and a minimum value thereof is set to 0%.