| 摘要 |
PROBLEM TO BE SOLVED: To provide a near-infrared cut filter that has incident angle dependency attenuated in a region where transmittance is equal to or less than 20%.SOLUTION: A near-infrared cut filter has: a substrate that is made up of phosphate glass containing copper or phosphate glass containing the copper; and an optical multilayer membrane that is laminated on the substrate. The optical multilayer membrane has an infrared anti-reflection membrane in which a high refractive index membrane and a low refractive index membrane are repeatedly laminated. An optical characteristic composed of both the substrate and the optical multilayer membrane is such that an average wavelength shift ((Σ(λ-λ))/16) obtained by dividing a total (Σ(λ-λ)) by a 1% increment from 5% to 20% of transmittance for a wavelength shift (λ-λ) composed of a difference between a wavelength (λ) at a 30° incidence in a region on a long wavelength side with respect to a transmittance band in spectral transmittance and a wavelength (λ) at a vertical incidence therein with the number of times of totals exceeds -19nm.SELECTED DRAWING: Figure 1 |
