Optical filter and imaging device
There is provide an optical filter suppressed in incidence angle dependence and having high visible light transmittance. The optical filter includes: an absorption layer containing a first near-infrared absorbent (DA) having a maximum absorption wavelength λ(DA_T min ) in wavelengths of 685 to 715 nm and a second near-infrared absorbent (DB) having a maximum absorption wavelength λ(DB_T min ) in wavelengths of 705 to 725 nm or wavelengths of more than 725 nm and 900 nm or less on a side of a wavelength longer than the maximum absorption wavelength λ(DA_T min ), and satisfying specific light absorption characteristics; and a reflection layer including a dielectric multilayer film satisfying specific reflection characteristics in wavelengths of 700 to 1150 nm, wherein a transmittance of the reflection layer in a boundary region of visible light and near-infrared light and a transmittance of the absorption layer have a specific relation.
1. An optical filter comprising:
an absorption layer containing a first near-infrared absorbent (DA) having a maximum absorption wavelength λ(DA_T min ) in wavelengths of 685 to 715 nm and a second near-infrared absorbent (DB) having a maximum absorption wavelength λ(DB_T min ) in wavelengths of 705 to 725 nm, and satisfying the following requirements (i-1) to (i-3); and
a reflection layer comprising a dielectric multilayer film satisfying the following requirements (ii-1) to (ii-2),
(i-1) 10 nm≤λ(DB_T min )−λ(DA_T min )<40 nm,
(i-2) a transmittance for light of a wavelength of 600 nm is 80% or more, a transmittance for light of a wavelength of 650 nm is 40% or more, a transmittance for light of a wavelength of 700 nm is 3% or less, and a transmittance for light of a wavelength of 714 nm is 10% or less,
(i-3) {λSh(DAB_T50%)−λSh(DAB_T90%)}≥{λSh(DAB_T5%)−λSh(DAB_T50%)}
where λSh(DAB_T90%), λSh(DAB_T50%) and λSh(DAB_T5%) indicate wavelengths at which transmittances in wavelengths of 580 nm to λ(DA_T min ) become 90%, 50% and 5% respectively,
(ii-1) the reflection layer has a reflection band where a transmittance with respect to light at an incidence angle of 0° in wavelengths of 700 to 1150 nm becomes 5% or less, and
(ii-2) λSh(DAB_T10%)+30 nm<λ R (0°_T50%)<λLo(DAB_T5%)
where λ R (0°_T50%) indicates a wavelength at which a transmittance with respect to the light at the incidence angle of 0° in wavelengths of 680 to 750 nm becomes 50%, λSh(DAB_T10%) indicates a wavelength at which a transmittance of the absorption layer in the wavelengths of 580 nm to λ(DA_T min ) becomes 10%, and λLo(DAB_T5%) indicates a wavelength at which a transmittance thereof in wavelengths λ(DB_T min ) to 800 nm becomes 5%.
2. The optical filter according to claim 1 ,
wherein an absorption wavelength band width Δλ abs (T10%) where the transmittance becomes 10% or less in a vicinity of a wavelength of 700 nm of the absorption layer is 40 nm or more.
3. The optical filter according to claim 1 , satisfying the following requirements (1) and (2) in spectral transmittance curves at incidence angles of 0° to 30°,
(1) an average transmittance in wavelengths of 440 to 600 nm is 80% or more, and
(2) a transmittance in a whole range of wavelengths of 690 to 720 nm is 5% or less.
4. The optical filter according to claim 1 ,
wherein an average transmittance with respect to light of wavelengths of 350 to 390 nm in a spectral transmittance curve at the incidence angle of 0° is 10% or less.
5. The optical filter according to claim 1 ,
wherein a wavelength λLo(30°_Tp15%) where a transmittance for p-polarized light at the incidence angle of 30° of the reflection layer becomes 15% is more than 1150 nm.
6. The optical filter according to claim 1 ,
wherein the absorption layer contains a near-ultraviolet absorbent having a maximum absorption wavelength λ(DU_T min ) in wavelengths of 370 to 405 nm and having a wavelength λLo(DU_T50%) at which a transmittance becomes 50% in wavelengths of 400 to 420 nm.
7. The optical filter according to claim 1 ,
wherein a difference between a transmittance with respect to light at the incidence angle of 0° and a transmittance with respect to light at the incidence angle of 30° of a wavelength at which a transmittance becomes 50% or less in spectral transmittance curves in wavelengths of 600 to 900 nm is 30% or less.
8. The optical filter according to claim 1 , further comprising a transparent substrate.
9. The optical filter according to claim 8 ,
wherein the transparent substrate is an absorption glass.
10. The optical filter according to claim 9 ,
wherein the absorption glass is a fluorophosphate-based glass or a phosphate-based glass containing CuO.
11. The optical filter according to claim 1 ,
wherein the first near-infrared absorbent (DA) contains at least one kind selected from a squarylium-based compound, a cyanine-based compound, a phthalocyanine-based compound, a naphthalocyanine-based compound, a dithiol metal complex-based compound, and a diimonium-based compound.
12. An imaging device comprising the optical filter according to claim 1 .
13. An optical filter comprising:
an absorption layer containing a first near-infrared absorbent (DA) having a maximum absorption wavelength λ(DA_T min ) in wavelengths of 685 to 715 nm and a second near-infrared absorbent (DB) having a maximum absorption wavelength λ(DB_T min ) in wavelengths of more than 725 nm and 900 nm or less, and the satisfying following requirements (i-4) to (i-6); and
a reflection layer comprising a dielectric multilayer film satisfying the following requirements (ii-3) to (ii-5),
(i-4) 40 nm≤λ(DB_T min )−λ(DA_T min )≤215 nm,
(i-5) a transmittance for light of a wavelength of 600 nm is 80% or more, a transmittance for light of a wavelength of 650 nm is 40% or more, a transmittance for light of the wavelength λ(DA_T min ) is 3% or less, and a transmittance for light of the wavelength λ(DB_T min ) is 3% or less,
(i-6) {λSh(DAB_T50%)−λSh(DAB_T90%)}≥{λSh(DAB_T5%)−λSh(DAB_T50%)}
where λSh(DAB_T90%), λSh(DAB_T50%) and λSh(DAB_T5%) indicate wavelengths at which transmittances in wavelengths of 580 nm to λ(DA_T min ) become 90%, 50% and 5% respectively,
(ii-3) the reflection layer has a reflection band where a transmittance with respect to light at an incidence angle of 0° in wavelengths of 700 to 1150 nm becomes 5% or less,
(ii-4) λSh(DAB_T10%)+20 nm<λ R (0°_T50%)<λ C (T max )
where λ R (0°_T50%) indicates a wavelength at which a transmittance with respect to the light at the incidence angle of 0° in wavelengths of 680 to 750 nm becomes 50%, λSh(DAB_T10%) indicates a wavelength at which a transmittance of the absorption layer in the wavelengths of 580 nm to λ(DA_T min ) becomes 10%, and λ C (T max ) indicates a wavelength at which a transmittance of the absorption layer becomes maximum in wavelengths λ(DA_T min ) to λ(DB_T min ), and
(ii-5) 0 nm<δλ R Sh(T50%)≤25 nm
where δλ R Sh(T50%) indicates a difference between λ R (0°_T50%) and λ R (30°_Ts50%), and λ R (30°_Ts50%) indicates a wavelength at which a transmittance with respect to s-polarized light at an incidence angle of 30° in wavelengths of 640 to 750 nm becomes 50%.
14. The optical filter according to claim 13 ,
wherein the absorption layer has a resin layer containing the first near-infrared absorbent (DA) and an absorption glass containing the second near-infrared absorbent (DB).
15. The optical filter according to claim 13 , satisfying the following requirements (1) and (2) in spectral transmittance curves at incidence angles of 0° to 30°,
(1) an average transmittance in wavelengths of 440 to 600 nm is 80% or more, and
(2) a transmittance in a whole range of wavelengths of 690 to 720 nm is 5% or less.
16. The optical filter according to claim 13 ,
wherein an average transmittance with respect to light of wavelengths of 350 to 390 nm in a spectral transmittance curve at the incidence angle of 0° is 10% or less.
17. The optical filter according to claim 13 ,
wherein a wavelength λLo(30°_Tp15%) where a transmittance for p-polarized light at the incidence angle of 30° of the reflection layer becomes 15% is more than 1150 nm.
18. The optical filter according to claim 13 ,
wherein the absorption layer contains a near-ultraviolet absorbent having a maximum absorption wavelength λ(DU_T min ) in wavelengths of 370 to 405 nm and having a wavelength λLo(DU_T50%) at which a transmittance becomes 50% in wavelengths of 400 to 420 nm.
19. The optical filter according to claim 13 ,
wherein a difference between a transmittance with respect to light at the incidence angle of 0° and a transmittance with respect to light at the incidence angle of 30° of a wavelength at which a transmittance becomes 50% or less in spectral transmittance curves in wavelengths of 600 to 900 nm is 30% or less.
20. The optical filter according to claim 13 , further comprising a transparent substrate.
21. The optical filter according to claim 20 ,
wherein the transparent substrate is an absorption glass.
22. The optical filter according to claim 21 ,
wherein the absorption glass is a fluorophosphate-based glass or a phosphate-based glass containing CuO.
23. The optical filter according to claim 13 ,
wherein the first near-infrared absorbent (DA) contains at least one kind selected from a squarylium-based compound, a cyanine-based compound, a phthalocyanine-based compound, a naphthalocyanine-based compound, a dithiol metal complex-based compound, and a diimonium-based compound.
24. An imaging device comprising the optical filter according to claim 13 .