Optical filter and imaging device

Patent metadata

Field	Value
Publication number	US-10746908-B2
Application number	US-201715819670-A
Country	US
Kind code	B2
Filing date	Nov 21, 2017
Priority date	Sep 25, 2015
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

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_Tmin) in wavelengths of 685 to 715 nm and a second near-infrared absorbent (DB) having a maximum absorption wavelength λ(DB_Tmin) 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_Tmin), 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.

First claim

What is claimed is:

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

Assignees

• Agc Inc

Inventors

• Ooi Yoshiharu
• Kumai Hiroshi
• Shiono Kazuhiko
• Hotaka Hiroki

Classifications

• G02B1/04

  made of organic materials, e.g. plastics (G02B1/08 takes precedence) · CPC title

• G02B5/282

  reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection · CPC title

• G02B5/208 Primary

  for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation · CPC title

• C09B57/007

  Squaraine dyes · CPC title

• G02B5/28

  Interference filters · CPC title