Optical filter and imaging device
An optical filter, including a first absorption layer containing a near-infrared absorbing dye and a transparent resin. The optical filter also includes a reflection layer. The first absorption layer has a thickness of 0.3 μm to 10 μm. The optical filter satisfies conditions described in the disclosure. An imaging apparatus including the optical filter.
1. An optical filter, comprising: a first absorption layer comprising a near-infrared absorbing dye and a transparent resin; and a reflection layer,
wherein the first absorption layer has a thickness of 0.3 μm to 10 μm, and
wherein the optical filter satisfies the following (ii-2) to (ii-6):
(ii-2) an average transmittance T 435-480ave0° of light in a wavelength range of 435 to 480 nm is 70% or more at an incident angle of 0 degrees,
(ii-3) an average transmittance T 490-580ave0° of light in a wavelength range of 490 to 580 nm is 84% or more at an incident angle of 0 degrees,
(ii-4) an average transmittance T 800-900ave60° of light in a wavelength range of 800 to 900 nm is 0.1% or less at an incident angle of 60 degrees,
(ii-5) a maximum transmittance T 800-900max60° of light in a wavelength range of 800 to 900 nm is 2.1% or less at an incident angle of 60 degrees, and
(ii-6) a wavelength λ SHT20-0° that is a shorter wavelength of wavelengths showing a transmittance of 20% at an incident angle of 0 degrees is in a wavelength range of 640 to 690 nm, and a difference between a wavelength λ SHT20-30° that is a shorter wavelength of wavelengths showing a transmittance of 20% at an incident angle 30 degrees and the wavelength λ SHT20-0° is 10 nm or less.
2. An imaging apparatus comprising the optical filter as described in claim 1 .
3. The optical filter according to claim 1 , wherein the maximum transmittance T 800-900max60° of light in the wavelength range of 800 to 900 nm is 1.9% or less at an incident angle of 60 degrees.
4. The optical filter according to claim 3 , wherein the maximum transmittance T 800-900max60° of light in the wavelength range of 800 to 900 nm is 0.4% or less at an incident angle of 60 degrees.
5. The optical filter according to claim 1 , wherein the first absorption layer comprises two or more of the near-infrared absorbing dyes.
6. The optical filter according to claim 1 , further comprising a second absorption layer comprising a transparent resin.
7. The optical filter according to claim 1 , wherein the first absorption layer further comprises a UV dye.
8. The optical filter according to claim 1 , further comprising a transparent substrate made of phosphate glass, borosilicate glass, alkali-free glass, or a transparent resin.
9. The optical filter according to claim 1 , wherein the reflection layer has a thickness of 2 μm to 10 μm.
10. The optical filter according to claim 1 , further comprising an antireflection layer.
11. The optical filter according to claim 1 , wherein the near-infrared absorbing dye has a maximum absorption wavelength in a wavelength range of 680 to 750 nm.
12. The optical filter according to claim 1 , wherein the near-infrared absorbing dye has a maximum absorption wavelength in a wavelength range of 760 to 900 nm.
13. The optical filter according to claim 1 , further satisfying the following:
an average transmittance T 435-480ave50° of light in a wavelength range of 435 to 480 nm is 60.6% or more at an incident angle of 50 degrees.
14. The optical filter according to claim 1 , further satisfying the following:
an average transmittance T 490-580ave50° of light in a wavelength range of 490 to 580 nm is 77.6% or more at an incident angle of 50 degrees.
15. The optical filter according to claim 1 , wherein the near-infrared absorbing dye comprises a cyanine-based dye represented by the following Formula (A1) or Formula (A2):
wherein, symbols in the Formulae (A1) and (A2) are as follows:
R 101 to R 109 and R 121 to R 131 are each independently a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms, which may have a substituent, or an aryl group having 5 to 20 carbon atoms;
R 110 to R 114 and R 132 to R 136 are each independently a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 15 carbon atoms;
a plurality of R 101 's to R 109 's and R 121 's to R 131 's included in each formula may be the same as or different from each other;
X − represents a monovalent anion;
n1 and n2 are 0 or 1; and
a hydrogen atom bonding to a carbon ring containing —(CH 2 ) n1 — or a carbon ring containing —(CH 2 ) n2 — may be substituted with a halogen atom, or an alkyl group having 1 to 15 carbon atoms or aryl group having 5 to 20 carbon atoms which may have a substituent.