Near-infrared cut filter and imaging device
Abstract:
A near-infrared cut filter has an absorption layer and a reflection layer and satisfies following requirements: average transmittance (R) of 620-750 nm is ≤20%, average transmittance (G) of 495-570 nm is ≥90%, and a ratio (R)/(G) is ≤0.20; |T0(600-725)−T30(600-725)| is ≤3%·nm where T0(600-725) is a transmittance integral value of 600-725 nm in a spectral transmittance curve (0°), and T30(600-725) is a transmittance integral value of 600-725 nm in a spectral transmittance curve (30°); wavelengths λIRT(80), λIRT(50), and λIRT(20) where transmittance becomes 80%, 50%, and 20% respectively in 550-750 nm in the spectral transmittance curve (0°) normalized by maximum transmittance in 450-650 nm satisfy following formulae: 0≤λIRT(80)−λT(80)≤30 nm, 0≤λIRT(50)−λT(50)≤35 nm, and 0≤λIRT(20)−λT(20)≤37 nm where λT(80), λT(50), and λT(20) are wavelengths on a long wavelength side where relative visibility of 0.8, 0.5 and 0.2 is exhibited in a relative visibility curve.
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