Optical filter

Abstract

To provide an optical filter which is excellent in a shielding property relative to specific near-infrared light and near-ultraviolet light other than visible light and specific near-infrared light to be transmission regions even at a high incident angle.SOLUTION: An optical filter includes a dielectric multilayer film 1, a glass substrate, a dielectric multilayer film 2, a light absorption layer, and a dielectric multilayer film 3 in this order. The light adsorption layer contains a near-infrared absorption pigment. The optical filter satisfies all specific spectral characteristics (i-1) to (i-6).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical filter.

Background Art

[0002] An imaging device using a solid-state imaging device has been extended in its applications to devices that image regardless of day or night, such as surveillance cameras and in-vehicle cameras. In such a device, it is necessary to acquire a (color) image based on visible light and a (black-and-white) image based on infrared light, respectively.

[0003] For this reason, in addition to a near-infrared cut filter function for transmitting visible light and faithfully reproducing an image based on the visible light, the use of an optical filter having a function of selectively transmitting specific near-infrared light, so-called a dual-bandpass filter, has been studied.

[0004] Patent Document 1 describes an optical filter that combines a dielectric multilayer film and a resin substrate containing a near-infrared absorbing dye, and transmits visible light and near-infrared light near 850 nm, and blocks other light. Patent Document 2 describes an optical filter that combines a dielectric multilayer film and a resin substrate containing a near-infrared absorbing dye, and transmits visible light and near-infrared light near 940 nm, and blocks other light.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, with the diversification of the sensing region in the imaging field, laser light including a part of the near-infrared light region after 1000 nm, which has a different wavelength region from those of Patent Documents 1 and 2 above, is used. Therefore, an optical filter that can transmit the near-infrared light in such a sensing region and block other near-infrared light and near-ultraviolet light that become noise is required.

[0007] In addition, in an optical filter having a dielectric multilayer film, since the optical film thickness of the dielectric multilayer film changes depending on the incident angle of light, the change in the spectral transmittance curve depending on the incident angle is a problem. For example, when the incident angle of light increases, the reflection characteristic shifts to the short-wavelength side, and as a result, the reflection characteristic may decrease in the region that is originally desired to be shielded. Such a phenomenon is more likely to occur as the incident angle is larger. When such a filter is used, the spectral sensitivity of the solid-state imaging device may be affected by the incident angle. In recent years, with the reduction in the height of camera modules, use under high incident angle conditions is assumed, and thus an optical filter that is less affected by the incident angle is required.

[0008] An object of the present invention is to provide an optical filter having excellent shielding properties for specific near-infrared light and near-ultraviolet light other than visible light and specific near-infrared light that are in the transmission region even at a high incident angle.

Means for Solving the Problems

[0009] The present invention relates to an optical filter and the like having the following configuration. An optical filter having a dielectric multilayer film 1, a glass substrate, a dielectric multilayer film 2, a light absorption layer, and a dielectric multilayer film 3 in this order, The light absorption layer contains a near-infrared absorbing dye, The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-6). (i-1) When one main surface is the incident direction, the average reflectance of light with a wavelength of 1300 to 1500 nm is 90% or more at an incident angle of 5 degrees and 90% or more at an incident angle of 40 degrees (i-2) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 1300 to 1500 nm is 95% or more at an incident angle of 5 degrees and 95% or more at an incident angle of 40 degrees (i-3) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 750 to 900 nm is 30% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 40 degrees (i-4) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 750 to 900 nm is 80% or more at an incident angle of 5 degrees and 70% or more at an incident angle of 40 degrees (i-5) The average transmittance of light with a wavelength of 350 to 400 nm is 1% or less at an incident angle of 0 degrees and 2% or less at an incident angle of 40 degrees (i-6) The maximum transmittance of light with a wavelength of 350 to 400 nm is 2% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 40 degrees [Effect of the Invention]

[0010] According to the present invention, an optical filter excellent in shielding specific near-infrared light and near-ultraviolet light other than visible light and specific near-infrared light that become transmission regions can be provided even at a high incident angle. The optical filter of the present invention is particularly an optical filter excellent in the reflection characteristics of light with a wavelength of 1300 to 1500 nm and light with a wavelength of 750 to 900 nm that become noise and the shielding property of near-ultraviolet light, and is hardly affected by the incident angle. [Brief Description of the Drawings]

[0011]

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[0012] Hereinafter, embodiments of the present invention will be described. In this specification, near-infrared absorbing dyes may be abbreviated as "NIR dyes" and ultraviolet absorbing dyes may be abbreviated as "UV dyes". In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. The dye composed of compound (I) is also referred to as dye (I), and the same applies to other dyes. Further, the group represented by formula (I) is also denoted as group (I), and the same applies to groups represented by other formulas.

[0013] In this specification, the transmittance of glass, the light absorption layer including the case where the dye is contained in the resin, the transmittance measured by dissolving the dye in a solvent such as dichloromethane, the transmittance of the dielectric multilayer film, and the spectral transmittance of the optical filter having the dielectric multilayer film are all "external (measured) transmittance" including the reflection loss on the front and back surfaces when described as "transmittance".

[0014] In this specification, the optical density indicates a value converted from the transmittance by the following formula. Optical density at wavelength λ nm = -log10(iT λ / 100) iT λ : Transmittance at an incident angle of 0 degrees at wavelength λ nm

[0015] In this specification, for a specific wavelength range, a transmittance of, for example, 90% or more means that the transmittance does not fall below 90% in the entire wavelength range, that is, the minimum transmittance in that wavelength range is 90% or more. Similarly, for a specific wavelength range, a transmittance of, for example, 1% or less means that the transmittance does not exceed 1% in the entire wavelength range, that is, the maximum transmittance in that wavelength range is 1% or less. The average transmittance in a specific wavelength range is the arithmetic mean of the transmittances every 1 nm in that wavelength range. The spectral characteristics can be measured using an ultraviolet-visible spectrophotometer. In this specification, for the symbol "~" representing a numerical range, the upper and lower limits are included.

[0016] <Optical filter> An optical filter according to an embodiment of the present invention (hereinafter, also referred to as "this filter") is an optical filter having a dielectric multilayer film 1, a glass substrate, a dielectric multilayer film 2, a light absorption layer, and a dielectric multilayer film 3 in this order, wherein the light absorption layer contains a near-infrared absorbing dye. Due to the reflection characteristics of the dielectric multilayer film and the absorption characteristics of the light absorption layer, excellent transmittance in the visible light region and a specific near-infrared light region and excellent shielding properties from other near-infrared light regions and the near-ultraviolet light region can be realized for the entire optical filter.

[0017] The configuration example of this filter will be described with reference to the drawings. FIGS. 1 to 2 are cross-sectional views schematically showing an example of an optical filter according to an embodiment.

[0018] The optical filter 10 shown in FIG. 2 is an example having a dielectric multilayer film 1, a glass substrate 4, a dielectric multilayer film 2, a light absorption layer 5, and a dielectric multilayer film 3 in this order.

[0019] This filter satisfies all of the following spectral characteristics (i-1) to (i-6). (i-1) When one main surface is the incident direction, the average reflectance of light with a wavelength of 1300 to 1500 nm is 90% or more at an incident angle of 5 degrees and 90% or more at an incident angle of 40 degrees (i-2) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 1300 to 1500 nm is 95% or more at an incident angle of 5 degrees and 95% or more at an incident angle of 40 degrees. (i-3) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 750 to 900 nm is 30% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 40 degrees. (i-4) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 750 to 900 nm is 80% or more at an incident angle of 5 degrees and 70% or more at an incident angle of 40 degrees. (i-5) The average transmittance of light with a wavelength of 350 to 400 nm is 1% or less at an incident angle of 0 degrees and 2% or less at an incident angle of 40 degrees. (i-6) The maximum transmittance of light with a wavelength of 350 to 400 nm is 2% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 40 degrees.

[0020] This filter that satisfies all of the spectral characteristics (i-1) to (i-6) is an optical filter that is excellent in the reflection characteristics of light with wavelengths of 1300 to 1500 nm and 750 to 900 nm, which become noise, and in the shielding property of near-ultraviolet light, and is hardly affected by the incident angle even at a high incident angle.

[0021] In the spectral characteristic (i-1), the average reflectance of light with a wavelength of 1300 to 1500 nm is preferably 94% or more at an incident angle of 5 degrees and preferably 95% or more at an incident angle of 40 degrees. In the spectral characteristic (i-2), the maximum reflectance of light with a wavelength of 1300 to 1500 nm is preferably 98% or more at an incident angle of 5 degrees and preferably 98% or more at an incident angle of 40 degrees. Also, the spectral characteristics (i-1) and the spectral characteristic (i-2) are preferably satisfied on the dielectric multilayer film 1 side (substrate side). To satisfy the spectral characteristics (i-1) and the spectral characteristic (i-2), for example, a dielectric multilayer film excellent in the reflection characteristics of light with a wavelength of 1300 to 1500 nm can be used. Preferably, any one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiA-1) to (iiA-3).

[0022] In the spectral characteristic (i-3), the average reflectance of light with a wavelength of 750 to 900 nm is preferably 35% or more at an incident angle of 5 degrees and preferably 35% or more at an incident angle of 40 degrees. In the spectral characteristic (i-4), the maximum reflectance of light with a wavelength of 750 to 900 nm is preferably 83% or more at an incident angle of 5 degrees and preferably 76% or more at an incident angle of 40 degrees. Further, the spectral characteristic (i-3) and the spectral characteristic (i-4) are preferably satisfied on the side of the dielectric multilayer film 3 (light absorption layer side). To satisfy the spectral characteristic (i-3) and the spectral characteristic (i-4), for example, a dielectric multilayer film having excellent reflection characteristics for light with a wavelength of 750 to 900 nm can be used. Preferably, any one of the dielectric multilayer films 1 to 3 satisfies all of the characteristics (iiC-1) to (iiC-3) described later.

[0023] In the spectral characteristic (i-5), the average transmittance of light with a wavelength of 350 to 400 nm is preferably 0.1% or less at an incident angle of 0 degrees and preferably 0.5% or less at an incident angle of 40 degrees. In the spectral characteristic (i-6), the maximum transmittance of light with a wavelength of 350 to 400 nm is preferably 0.5% or less at an incident angle of 0 degrees and preferably 2.0% or less at an incident angle of 40 degrees. To satisfy the spectral characteristic (i-5) and the spectral characteristic (i-6), for example, a dielectric multilayer film having excellent reflection characteristics for light with a wavelength of 350 to 400 nm can be used. Preferably, any one of the dielectric multilayer films 1 to 3 satisfies all of the characteristics (iiB-1) to (iiB-3) described later.

[0024] This filter preferably satisfies the following spectral characteristic (i-7). When any one of the main surfaces is the incident direction, the absorption loss amount at a wavelength of X nm X is defined as follows. (Absorption loss amount X ) [%] = 100 - (transmittance at an incident angle of 0 degrees) - (reflectance at an incident angle of 5 degrees) The absorption loss amount at wavelengths of 430 to 1100 nm 430-1100 has an integrated value of 10,000 or more The absorption loss amount X is an index indicating the degree of light shielding due to the absorption characteristics at wavelength X nm. The larger the value, the more the light of wavelength X is shielded by absorption. The integrated value in the spectral characteristic (i-7) is more preferably 12,000 or more. In order to satisfy the spectral characteristic (i-7), for example, using a near-infrared absorbing dye having a maximum absorption wavelength between 430 and 1100 nm can be mentioned.

[0025] This filter preferably satisfies all of the following spectral characteristics (i-8) to (i-11). (i-8) When one main surface is the incident direction, the average reflectance of light with wavelengths of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees (i-9) When one main surface is the incident direction, the maximum reflectance of light with wavelengths of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees (i-10) When one main surface is the incident direction, the average reflectance of light with wavelengths of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees (i-11) When one main surface is the incident direction, the maximum reflectance of light with wavelengths of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees

[0026] Satisfying all of the spectral characteristics (i-8) to (i-11) means that the reflection characteristics of light in the visible light region and the target wavelength region are small. In the spectral characteristic (i-8), the average reflectance of light with wavelengths of 420 to 650 nm is more preferably 4.5% or less at an incident angle of 5 degrees and more preferably 4.5% or less at an incident angle of 40 degrees. In the spectral characteristic (i-9), the maximum reflectance of light with a wavelength of 420 to 650 nm is preferably 7.5% or less at an incident angle of 5 degrees, and more preferably 13.9% or less at an incident angle of 40 degrees. In the spectral characteristic (i-10), the average reflectance of light with a wavelength of 1030 to 1150 nm is preferably 6.0% or less at an incident angle of 5 degrees, and more preferably 6.0% or less at an incident angle of 40 degrees. In the spectral characteristic (i-11), the maximum reflectance of light with a wavelength of 1030 to 1150 nm is preferably 7.0% or less at an incident angle of 5 degrees, and more preferably 11.0% or less at an incident angle of 40 degrees. Further, the spectral characteristics (i-8) to (i-11) are preferably satisfied on the side of the dielectric multilayer film 1 (substrate side). In order to satisfy the spectral characteristics (i-8) to (i-11), preferably, any one of the dielectric multilayer films 1 to 3 satisfies all of the characteristics (iiA-1) to (iiA-3) described below.

[0027] This filter preferably satisfies all of the following spectral characteristics (i-12) to (i-15). (i-12) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees (i-13) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees (i-14) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees (i-15) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees

[0028] Satisfying all of the spectral characteristics (i-12) to (i-15) means that the reflection characteristics of light in the visible light region and the target wavelength region are small. In the spectral characteristic (i-12), the average reflectance of light with a wavelength of 420 to 650 nm is preferably 4.0% or less at an incident angle of 5 degrees and more preferably 4.0% or less at an incident angle of 40 degrees. In the spectral characteristic (i-13), the maximum reflectance of light with a wavelength of 420 to 650 nm is preferably 8.0% or less at an incident angle of 5 degrees and more preferably 14.5% or less at an incident angle of 40 degrees. In the spectral characteristic (i-14), the average reflectance of light with a wavelength of 1030 to 1150 nm is preferably 6.0% or less at an incident angle of 5 degrees and more preferably 6.0% or less at an incident angle of 40 degrees. In the spectral characteristic (i-15), the maximum reflectance of light with a wavelength of 1030 to 1150 nm is preferably 8.0% or less at an incident angle of 5 degrees and more preferably 11.0% or less at an incident angle of 40 degrees. Also, the spectral characteristics (i-12) to (i-15) are preferably satisfied on the side of the dielectric multilayer film 3 (the light absorption layer side). To satisfy the spectral characteristics (i-12) to (i-15), preferably, any one of the dielectric multilayer films 1 to 3 satisfies all of the characteristics (iiC-1) to (iiC-3) described below.

[0029] <Glass substrate> This filter includes a glass substrate. Since this filter includes at least three dielectric multilayer films, a material with high rigidity such as glass is preferred as the base material rather than a resin film. This can reduce warping during film formation.

[0030] As the glass substrate, a transparent glass substrate or a light absorption glass substrate may be used, but a light absorption glass substrate is preferred. Since the absorption characteristics of the light absorption glass substrate do not cause the light shielding region to shift depending on the incident angle of light like the reflection characteristics of the dielectric multilayer film, high light shielding performance can be exhibited even at a high incident angle.

[0031] As the light-absorbing glass, glass containing ytterbium is preferable. The glass containing ytterbium has the property of absorbing near-infrared light in the wavelength range of 900 to 1000 nm. Further, since the waveform of the absorption band is steep, it has excellent transmittance in regions other than the maximum absorption wavelength region. Therefore, it has excellent transmittance in the visible light region and in the near-infrared light region from visible light to about 800 nm.

[0032] Hereinafter, each component that can constitute the glass and its preferred content (expressed in mol% based on oxides) will be described. In this specification, unless otherwise specified, the content of each component and the total content are expressed in mol% based on oxides.

[0033] Yb2O3 is a component for efficiently absorbing light in the vicinity of 900 to 1000 nm in wavelength, particularly light with a wavelength of 940 nm, and reducing the transmittance. In the glass of this embodiment, if the content of Yb2O3 is 20% or more, the effect can be sufficiently obtained. If it is 60% or less, problems such as deterioration of the devitrification resistance of the glass, deterioration of the meltability, and generation of stray light due to fluorescence are less likely to occur. Therefore, the content of Yb2O3 is preferably 20 to 60%, more preferably 25 to 60%, still more preferably 30 to 60%, even more preferably 35 to 60%, particularly preferably more than 40% and 60% or less, and most preferably 45% to 60%.

[0034] SiO2 is the main component for forming the glass and is a component for increasing the devitrification resistance of the glass and the viscosity with respect to the liquidus temperature. In the glass of this embodiment, if the content of SiO2 is 0.1% or more, problems such as the glass becoming unstable, the weather resistance decreasing, and veins occurring in the glass are less likely to occur. If the content of SiO2 is 50% or less, problems such as deterioration of the meltability of the glass are less likely to occur. Therefore, the content of SiO2 is preferably 0.1 to 50%, more preferably 0.1 to 40%, still more preferably 0.1 to 30%, even more preferably 0.1 to 20%, particularly preferably 0.1 to 10%, and most preferably 0.1% to 9%.

[0035] B2O3 is the main component forming the glass and is a component for increasing the devitrification resistance of the glass and the viscosity with respect to the liquidus temperature. If the content of B2O3 in the glass of the present embodiment is 15% or more, problems such as the glass becoming unstable are less likely to occur. If the content of B2O3 is 40% or less, problems such as the weather resistance of the glass decreasing and veins occurring in the glass are less likely to occur. Therefore, the content of B2O3 is preferably 15 to 40%, more preferably 15 to 38%, still more preferably 15 to 36%, even more preferably 15 to 34%, particularly preferably 15 to 32%, and most preferably 15 to 30%.

[0036] From the viewpoint of obtaining a stable glass, the light-absorbing glass preferably contains at least one of SiO2 and B2O3. The total content of the above components is preferably more than 65% from the viewpoint that problems such as the glass becoming unstable are less likely to occur, and is preferably 80% or less from the viewpoint that problems such as the deterioration of the meltability of the glass are less likely to occur. Therefore, it is more preferably more than 65% and 79% or less, still more preferably more than 65% and 78% or less, even more preferably more than 65% and 77% or less, particularly preferably more than 65% and 76% or less, and most preferably more than 65% and 75% or less.

[0037] P2O5 is a component for improving the meltability and stability of the glass. In the glass of the present embodiment, the content of P2O5 is preferably 0 to 15%. If the content of P2O5 is 15% or less, problems such as the weather resistance of the glass deteriorating, the glass phase-separating, and veins occurring in the glass are less likely to occur. The content of P2O5 is more preferably 1 to 13%, still more preferably 2 to 12%, even more preferably 3 to 11%, and most preferably 4 to 10%.

[0038] GeO2 is a component for increasing the devitrification resistance of the glass and the viscosity with respect to the liquidus temperature. In the glass of this embodiment, the content of GeO2 is preferably 0 to 15%. If the content of GeO2 is 15% or less, problems such as deterioration of the meltability of the glass are less likely to occur. The content of GeO2 is more preferably 0 to 13%, still more preferably 0 to 11%, even more preferably 0 to 9%, and most preferably 0 to 7%.

[0039] Ga2O3 is a component for increasing the Young's modulus of the glass and improving the meltability and stability. In the glass of this embodiment, the content of Ga2O3 is preferably 0 to 30%. If the content of Ga2O3 is 30% or less, problems such as deterioration of the devitrification of the glass and an increase in reflectivity and generation of stray light due to the reflected light are less likely to occur. The content of Ga2O3 is more preferably 0.5 to 28%, still more preferably 1 to 26%, even more preferably 2 to 24%, and most preferably 3 to 22%.

[0040] ZrO2 is a component for increasing the Young's modulus of the glass and increasing the viscosity with respect to the liquidus temperature of the glass. In the glass of this embodiment, the content of ZrO2 is preferably 0 to 7%. If the content of ZrO2 is 7% or less, problems such as deterioration of the devitrification of the glass and deterioration of the meltability are less likely to occur. The content of ZrO2 is more preferably 0 to 6%, still more preferably 0 to 5%, even more preferably 0 to 4%, and most preferably 0 to 3%.

[0041] La2O3 is a component for increasing the Young's modulus of the glass and improving the meltability. In the glass of this embodiment, the content of La2O3 is preferably 0.1 to 20%. If the content of La2O3 is 0.1% or more, the effect can be sufficiently obtained, and if it is 20% or less, problems such as deterioration of the devitrification of the glass, an increase in reflectivity, and generation of stray light due to the reflected light are less likely to occur. The content of La2O3 is more preferably 0.5 to 19%, still more preferably 1 to 18%, even more preferably 2 to 17%, and most preferably 2 to 16%.

[0042] Al2O3 is a component for increasing the Young's modulus of the glass and lowering the refractive index of the glass. In the glass of the present embodiment, the content of Al2O3 is preferably 0.1 to 20%. If the content of Al2O3 is 0.1% or more, the effect can be sufficiently obtained. If it is 20% or less, problems such as deterioration of the devitrification property of the glass, an increase in the reflectance, and generation of stray light due to the reflected light are less likely to occur. More preferably, it is 0.1 to 18%, still more preferably 0.1 to 15%, even more preferably 0.1 to 13%, and most preferably 0.1 to 11%.

[0043] The ratio of the total amount of the Al2O3, GeO2, Ga2O3, and P2O5 components to the total content of the SiO2 and B2O3 components, that is, (total content of Al2O3, GeO2, Ga2O3 and P2O5) / (total content of SiO2 and B2O3), is preferably less than 0.1 from the viewpoint of vitrifying the glass without devitrifying the glass containing the Yb component.

[0044] As the light-absorbing glass, within a range not impairing the object of the present invention, it may contain alkali metal oxides, alkaline earth metal oxides, Sb2O3, Cl, F, and other components.

[0045] As the glass substrate in this filter, when used in an optical filter, in order to prevent stray light generated due to reflected light on the glass surface, it is desirable to lower the reflectance of the glass. The reflectance of the glass is determined by the refractive index, and typically, the refractive index at a wavelength of 588 nm is preferably 1.700 to 1.900.

[0046] When used as a glass substrate in a so-called dual-band pass filter having a function of selectively transmitting visible light and specific near-infrared light, the thickness is usually used at 3 mm or less, and is often preferably 2 mm or less, more preferably 1 mm or less, still more preferably 0.5 mm or less, and even more preferably 0.3 mm or less from the viewpoint of reducing the weight of the component. Also, from the viewpoint of ensuring the strength of the glass, 0.05 mm or more is preferable.

[0047] The glass substrate in this filter can be produced, for example, as follows. First, raw materials are weighed and mixed so as to fall within the above composition range (mixing step). This raw material mixture is placed in a platinum crucible and heated and melted at a temperature of 1200 to 1650 °C in an electric furnace (melting step). After sufficiently stirring and clarifying, it is poured into a mold and cut and polished to form a flat plate of a predetermined thickness (forming step).

[0048] In the melting step of the above manufacturing method, it is preferable that the highest temperature of the glass during glass melting is 1650 °C or lower. If the highest temperature of the glass during glass melting is below the above temperature, problems such as crystallization of the glass and generation of unmelted foreign substances in the glass are less likely to occur. The above temperature is more preferably 1625 °C or lower, and still more preferably 1600 °C or lower.

[0049] Also, if the temperature in the above melting step is too low, problems such as devitrification occurring during melting and taking a long time to melt off may occur, so it is preferably 1300 °C or higher, more preferably 1350 °C or higher.

[0050] <Light absorption layer> This filter includes a light absorption layer containing a near-infrared absorbing dye (NIR dye). Thereby, the region not shielded by the reflection characteristics of the dielectric multilayer film can be compensated by the absorption characteristics not affected by the incident angle.

[0051] The light absorption layer preferably satisfies all of the following spectral characteristics (iii-1) to (iii-2). (iii-1) In the spectral transmittance curve with a wavelength of 650 to 720 nm, let the shortest wavelength at which the internal transmittance becomes 30% be λ A_VIS(30%) and, in the spectral transmittance curve with a wavelength of 720 to 1000 nm, let the shortest wavelength at which the internal transmittance becomes 30% be λ A_IR(30%) When this is the case, the following relational expression is satisfied |λ A_IR(30%) −λ A_VIS(30%) |≥100 nm (iii-2) When the optical density at a wavelength of 720 nm is OD _720 When this is the case, the following relational expression is satisfied OD _720 ≥2.0

[0052] |λ A_IR(30%) −λ A_VIS(30%) | in characteristic (iii-1) is an index of the near-infrared light absorption band centered at 720 nm, and being 100 nm or more means that it is a light absorption layer that widely absorbs in the said region. |λ A_IR(30%) −λ A_VIS(30%) | is more preferably 120 nm or more. Also, from the point that it becomes difficult to keep the transmittance in the visible light region high as the maximum absorption wavelength of the dye is in the long wavelength region, it is preferably 150 nm or less. In order to satisfy characteristic (iii-1), for example, as the near-infrared absorbing dye, it is possible to combine two kinds of dyes having different maximum absorption wavelengths and in the region of 680 to 800 nm, preferably combine a dye having a maximum absorption wavelength in the range of 680 to 740 nm and a dye having a maximum absorption wavelength in the range of 740 to 800 nm. Also, from the viewpoint that wide absorption can be realized with a small addition amount, it is possible to use squarylium dyes.

[0053] Characteristic (iii-2) means that it is a light absorption layer having high near-infrared light shielding property at 720 nm. OD _720 is preferably 2.1 or more, more preferably 2.2 or more. In order to satisfy characteristic (iii-2), for example, as the near-infrared absorbing dye, a symmetric squarylium dye can be used from the viewpoint of strongly absorbing near 720 nm and maintaining a high transmittance in the visible light region.

[0054] The near-infrared absorbing dye (NIR dye) is preferably a dye having a maximum absorption wavelength in the wavelength range of 680 to 800 nm in dichloromethane (hereinafter, also referred to as "NIR dye"). By including such a dye, the light absorption layer can widely absorb the near-infrared light absorption band centered around 720 nm as shown in the above characteristics (iii-1) and (iii-2), and it is easy to achieve both visible light transmittance at 450 nm and near-infrared light shielding property at 720 nm. As the near-infrared absorbing dye, from the viewpoint of being able to widely absorb the near-infrared region while maintaining the transmittance in the visible light region, preferably two or more dyes having different maximum absorption wavelengths and in the region of 680 to 800 nm, more preferably three dyes are combined. In particular, it is preferable to include a dye having a maximum absorption wavelength of 700 nm or more and less than 730 nm, a dye having a maximum absorption wavelength of 730 nm or more and less than 760 nm, and a dye having a maximum absorption wavelength of 761 nm or more and less than 800 nm as the near-infrared absorbing dye.

[0055] As the NIR dye, at least one selected from the group consisting of squarylium dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, dithiol metal complex dyes, azo dyes, polymethine dyes, phthalide dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, croconium dyes, tetradehydroocorin dyes, triphenylmethane dyes, aminium dyes and diimonium dyes is preferable.

[0056] As the NIR dye, it is particularly preferable to contain at least one dye selected from squarylium dyes, phthalocyanine dyes, and cyanine dyes. Among these NIR dyes, it is more preferable to contain either squarylium dyes, cyanine dyes, or both from the spectroscopic viewpoint, and it is preferable to contain phthalocyanine dyes from the viewpoint of durability.

[0057] The content of the NIR dye in the light absorption layer is preferably 10% by mass or more, more preferably 20% by mass or less, and still more preferably 15% by mass or less. When combining two or more compounds, the above content is the sum of each compound.

[0058] The light absorption layer preferably contains a near-infrared absorbing dye and a resin. As the resin, there is no limitation as long as it is a transparent resin, and one or more transparent resins selected from polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins are used. These resins may be used alone or in combination of two or more. From the viewpoints of the spectroscopic characteristics, glass transition point (Tg), and adhesion of the light absorption layer, one or more resins selected from polyimide resins, polycarbonate resins, polyester resins, and acrylic resins are preferable.

[0059] When using a plurality of compounds as NIR dyes and other dyes, these may be contained in the same light absorption layer or may be contained in separate light absorption layers, respectively.

[0060] The light absorption layer can be formed by dissolving or dispersing a dye, a resin or a raw material component of the resin, and each component blended as required in a solvent to prepare a coating solution, coating this on a support, drying it, and further curing it as required. The support may be a light-absorbing glass substrate or a peelable support used only when forming the light absorption layer. Also, the solvent may be a dispersion medium that can be stably dispersed or a solvent that can be dissolved.

[0061] Further, the coating solution may contain a surfactant to improve voids due to minute bubbles, dents due to adhesion of foreign substances, etc., and repelling in the drying process. Further, for coating the coating solution, for example, a dipping coating method, a cast coating method, a spin coating method, etc. can be used. Also, when the coating solution contains a raw material component of a transparent resin, a curing treatment such as heat curing or photocuring is further performed.

[0062] Also, the light absorption layer can be manufactured in film form by extrusion molding. This filter can be manufactured by laminating the obtained film-shaped absorption layer on a light-absorbing glass substrate and integrating them by thermocompression bonding or the like.

[0063] The light absorption layer may have one layer or two or more layers in the optical filter. When having two or more layers, each layer may have the same configuration or different configurations.

[0064] The thickness of the light absorption layer is preferably 5 μm or less from the viewpoint of the in-plane film thickness distribution in the substrate after coating and the appearance quality, more preferably 2 μm or less from the viewpoint of reducing the thermal expansion amount of the resin, and preferably 0.5 μm or more from the viewpoint of expressing desired spectral characteristics at an appropriate dye concentration. When the optical filter has two or more light absorption layers, it is preferable that the total thickness of each light absorption layer is within the above range.

[0065] <Dielectric multilayer film> This filter includes three dielectric multilayer films on one main surface side of a glass substrate, the other main surface side, and the surface of the light absorption layer. The larger the thickness of the dielectric multilayer film, the easier it is to control the spectral characteristics. On the other hand, if it is too thick, stress is likely to occur and it becomes a cause of deformation. By providing the dielectric multilayer films at three locations, it is possible to disperse the role in the control of spectral characteristics and avoid concentrating the thickness on one multilayer film. It is preferable to design the dielectric multilayer films 1 to 3 as a reflection film that reflects a part of near-infrared light or a reflection film that reflects near-ultraviolet light.

[0066] It is preferable that at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiA-1) to (iiA-3). (iiA-1) The total number of stacked layers is 1 to 80 (iiA-2) It includes a high refractive index layer HA with a refractive index of 1.8 or more and 2.5 or less, and a low refractive index layer LA with a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HA to the total physical film thickness of the low refractive index layer LA is 0.3 to 0.8 (iiA-3) Among the high refractive index layers, QWOT is 1.0 or more and the layer closest to the nth position to the glass substrate is the HA n layer, and among the low refractive index layers, QWOT is 1.0 or more and the layer closest to the glass substrate next to the layer HA n is the LA n layer, when the layer between the HA n layer and the LA n layer is a MA layer composed of a single layer or a plurality of layers and the total QWOT is 1 or less 2n-1 layer, and the layer between the LA n layer and the HA layer with QWOT of 1.0 or more and closest to the (n + 1)th position to the glass substrate n+1 is a MA layer composed of a single layer or a plurality of layers and the total QWOT is 1 or less 2n layer, and has a repeating structure shown in the following formula (n is a natural number of 2 or more) (HA1 layer / MA1 layer / LA1 layer / MA2 layer)···(HA n layer / MA 2n-1 layer / LAn Layer / MA 2n layer)

[0067] By satisfying the characteristics (iiA-1) to (iiA-3), a dielectric multilayer film excellent in visible light transmittance and transmittance of near-infrared light in the short wavelength region, preferably near-infrared light of 1000 nm or less, and excellent in sharp cut-off property of near-infrared light in the long wavelength region, preferably near-infrared light of 1100 nm or more, can be obtained. The total number of stacked layers in (iiA-1) is more preferably 1 to 70. The ratio of the total physical film thickness in (iiA-2) is more preferably 0.4 to 0.6. n in (iiA-3) is more preferably 2 to 8. Also, the repeating structures may be continuous or separated from each other, but it is preferably continuous from the viewpoint of obtaining desired spectral characteristics.

[0068] Note that the refractive index means the refractive index at a wavelength of 500 nm. The same applies to the subsequent characteristics. Also, QWOT means an optical film thickness of 1 / 4 wavelength.

[0069] At least one of the dielectric multilayer films 1 to 3 preferably satisfies all of the following characteristics (iiB-1) to (iiB-3). (iiB-1) The total number of stacked layers is 1 to 60 (iiB-2) It includes a high refractive index layer HB having a refractive index of 1.8 or more and 2.5 or less and a low refractive index layer LB having a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HB to the total physical film thickness of the low refractive index layer LB is 0.2 to 0.8 (iiB-3) When the high refractive index layer with QWOT of 1.0 or more is defined as HB1 layer and the low refractive index layer with QWOT of 1.0 or more is defined as LB1 layer, The layer between the HB1 layer and the LB1 layer is composed of a single layer or a plurality of layers, and is an MB1 layer with QWOT of 1.0 or less per layer of all these layers, It has one or more of the stacked structures shown by the following formula (HB1 layer / MB1 layer / LB1 layer)

[0070] By satisfying the characteristics (iiB-1) to (iiB-3), a dielectric multilayer film excellent in visible light transmittance, near-infrared light transmittance, and near-ultraviolet light sharp cut-off property can be obtained. The total number of stacked layers in (iiB-1) is more preferably 1 to 20. The ratio of the total physical film thickness in (iiB-2) is more preferably 0.25 to 0.75. The number of stacked structures in (iiB-3) is more preferably 1. Further, when having two or more stacked structures, the stacked structures may be continuous or separated from each other, but are preferably continuous from the viewpoint of obtaining desired spectral characteristics.

[0071] It is preferable that at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiC-1) to (iiC-3). (iiC-1) The total number of stacked layers is 1 to 60 (iiC-2) It includes a high refractive index layer HC having a refractive index of 1.8 or more and 2.5 or less, and a low refractive index layer LC having a refractive index of 1.4 or more and 1.6 or less. The ratio of the total physical film thickness of the high refractive index layer HC to the total physical film thickness of the low refractive index layer LC is 0.5 to 0.9, and the ratio of the total QWOT of the high refractive index layer HC to the total QWOT of the low refractive index layer LC is 1.1 to 1.5. (iiC-3) It has a stacked structure represented by the following formula (HC2 layer / LC2 layer / HC2 layer) / MC1 layer / (LC1 layer / HC1 layer / LC1 layer) / MC1 layer / (HC2 layer / LC2 layer / HC2 layer) HC1 layer, HC2 layer: Each independently, a high refractive index layer having a QWOT of 1.0 or more LC1 layer, LC2 layer: Each independently, a low refractive index layer having a QWOT of 1.0 or more MC1 layer: Each independently, a layer composed of a single layer or a plurality of layers having a total QWOT of 1 or less

[0072] By satisfying characteristics (iiC-1) to (iiC-3), a dielectric multilayer film excellent in visible light transmittance and in the transmittance of near-infrared light in the long-wavelength region, preferably near-infrared light of 1100 nm or more, and excellent in the sharp cut-off property of near-infrared light in the short-wavelength region, preferably near-infrared light of 1000 nm or less, can be obtained. The total number of stacked layers in (iiC-1) is more preferably 1 to 45. The ratio of the total physical film thickness in (iiC-2) is more preferably 0.6 to 0.8. The ratio of the total QWOT in (iiC-2) is more preferably 1.1 to 1.35. As the stacked structure in (iiC-3), the following stacked structure is more preferable. (HC3 layer / MC3 layer / HC3 layer) / (MC2 layer / LC3 layer / MC2 layer) / (HC2 layer / LC2 layer / HC2 layer) / MC1 layer / (LC1 layer / HC1 layer / LC1 layer) / MC1 layer / (HC2 layer / LC2 layer / HC2 layer) / (MC2 layer / LC3 layer / MC2 layer) / (HC3 layer / MC3 layer / HC3 layer) HC1 layer, HC2 layer, LC1 layer, LC2 layer, MC1 layer: synonymous with the above definition HC3 layer: Each independently, a high refractive index layer with a QWOT of 0.8 or more LC3 layer: Each independently, a low refractive index layer with a QWOT of 1.0 or more MC2 layer: Each independently, a layer composed of a single layer or a plurality of layers with a total QWOT of 1 or less MC3 layer: Each independently, a layer composed of a single layer or a plurality of layers with a total QWOT of 2 or less

[0073] It is more preferable that each of the dielectric multilayer films 1 to 3 satisfies the above characteristics (iiA-1) to (iiA-3), characteristics (iiB-1) to (iiB-3), and characteristics (iiC-1) to (iiC-3), respectively. Thereby, due to the reflection characteristics of the three dielectric multilayer films, a sharp cut-off property for near-ultraviolet light, a high transmittance for visible light, and sharp cut-off properties on the short-wavelength side and the long-wavelength side of the target wavelength can be imparted to the optical filter. Particularly preferably, the dielectric multilayer film 1 satisfies the characteristics (iiA-1) to (iiA-3), the dielectric multilayer film 2 satisfies the characteristics (iiB-1) to (iiB-3), and the dielectric multilayer film 3 satisfies the characteristics (iiC-1) to (iiC-3).

[0074] A dielectric multilayer film is a laminate of dielectric films having different refractive indices. More specifically, examples include a low-refractive-index dielectric film (low-refractive-index film), a medium-refractive-index dielectric film (medium-refractive-index film), and a high-refractive-index dielectric film (high-refractive-index film), and it is composed of a dielectric multilayer film in which two or more of these are laminated. By combining several dielectric films having different spectral characteristics when transmitting and selecting a desired wavelength band, the reflection characteristics can be adjusted.

[0075] The high-refractive-index material preferably has a refractive index at a wavelength of 500 nm of 1.8 or more and 2.5 or less, and more preferably 1.9 or more and 2.5 or less. Examples of the high-refractive-index material include Ta2O5, TiO2, TiO, and Nb2O5. Other commercially available products include OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), OA600 (a mixture of Ta2O5 and TiO2), etc. manufactured by Canon Optron Co., Ltd. Among these, TiO2 is preferable in terms of film-forming properties, reproducibility in refractive index, stability, etc.

[0076] The medium refractive index material preferably has a refractive index at a wavelength of 500 nm greater than 1.5 and less than 1.8, more preferably 1.55 or more and less than 1.8. Examples of the medium refractive index material include ZrO2, Nb2O5, Al2O3, HfO2, OM-4, OM-6 (a mixture of Al2O3 and ZrO2), OA-100 sold by Canon Optron Co., Ltd., H4, M2 (aluminum lanthanum oxide) sold by Merck Co., Ltd., and the like. Among these, from the viewpoints of film formation properties, reproducibility in refractive index, stability, etc., Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred. Note that the medium refractive index film may be replaced with an equivalent film composed of a high refractive index film and a low refractive index film without using the aforementioned medium refractive index material.

[0077] The low refractive index material preferably has a refractive index at a wavelength of 500 nm of 1.4 or more and 1.6 or less, more preferably 1.45 or more and 1.5 or less. Examples of the low refractive index material include, for example, SiO2, SiO x N y、 MgF2 and the like. Other commercially available products include S4F and S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Co., Ltd. Among these, SiO2 is preferred from the viewpoints of reproducibility in film formation properties, stability, economy, etc.

[0078] The film thickness (physical film thickness) of the dielectric multilayer film 1 is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of easily controlling the spectral characteristics, and is preferably 6 μm or less from the viewpoints of productivity and suppressing reflection ripple in the visible light region.

[0079] The film thickness (physical film thickness) of the dielectric multilayer film 2 is preferably 0.2 μm or more, more preferably 0.5 μm or more, from the viewpoint of easily controlling the spectral characteristics, and is preferably 6 μm or less from the viewpoints of productivity and suppressing reflection ripple in the visible light region.

[0080] The film thickness (physical film thickness) of the dielectric multilayer film 3 is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of easily controlling the spectral characteristics, and is preferably 6 μm or less from the viewpoints of productivity and suppressing reflection ripple in the visible light region.

[0081] For forming the dielectric multilayer film, for example, vacuum film forming processes such as CVD method, sputtering method, vacuum evaporation method, etc., and wet film forming processes such as spray method, dip method, etc. can be used.

[0082] As other components, this filter may include, for example, components (layers) that provide absorption by inorganic fine particles or the like that control the transmission and absorption of light in a specific wavelength range. Specific examples of the inorganic fine particles include ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, lanthanum boride, etc. ITO fine particles and cesium tungstate fine particles have a high transmittance of visible light and light absorbency in a wide range of infrared wavelength regions exceeding 1200 nm, and thus can be used when such infrared light shielding properties are required.

[0083] <Imaging device> The imaging device according to an embodiment of the present invention preferably includes the optical filter according to the above embodiment of the present invention. The imaging device preferably further includes a solid-state imaging device and an imaging lens. The optical filter according to the present embodiment can be used, for example, by being disposed between the imaging lens and the solid-state imaging device, or by being directly adhered to the solid-state imaging device, imaging lens, etc. of the imaging device via an adhesive layer. By providing this filter that is excellent in the transmittance of visible light and specific near-infrared light, has the shielding property of specific near-infrared light, and has a spectral curve that is difficult to shift even at a high incident angle, an imaging device excellent in color reproducibility for light at a high incident angle can be obtained.

[0084] When mounting the optical filter on the imaging device, it is usually preferable, but not limited to, to have the dielectric multilayer film 1 on the lens side and the dielectric multilayer film 3 on the sensor side.

[0085] As described above, the following optical filters and the like are disclosed in this specification. 〔1〕An optical filter having a dielectric multilayer film 1, a glass substrate, a dielectric multilayer film 2, a light absorption layer, and a dielectric multilayer film 3 in this order, The light absorption layer contains a near-infrared absorbing dye, The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-6). (i-1) When one main surface is the incident direction, the average reflectance of light with a wavelength of 1300 to 1500 nm is 90% or more at an incident angle of 5 degrees and 90% or more at an incident angle of 40 degrees (i-2) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 1300 to 1500 nm is 95% or more at an incident angle of 5 degrees and 95% or more at an incident angle of 40 degrees (i-3) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 750 to 900 nm is 30% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 40 degrees (i-4) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 750 to 900 nm is 80% or more at an incident angle of 5 degrees and 70% or more at an incident angle of 40 degrees (i-5) The average transmittance of light with a wavelength of 350 to 400 nm is 1% or less at an incident angle of 0 degrees and 2% or less at an incident angle of 40 degrees (i-6) The maximum transmittance of light with a wavelength of 350 to 400 nm is 2% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 40 degrees 〔2〕The optical filter according to 〔1〕, wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiB-1) to (iiB-3). (iiB-1) The total number of stacked layers is 1 to 60 (iiB-2) It includes a high refractive index layer HB having a refractive index of 1.8 or more and 2.5 or less and a low refractive index layer LB having a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HB to the total physical film thickness of the low refractive index layer LB is 0.2 to 0.8 (iiB-3) When the high refractive index layer with QWOT of 1.0 or more is HB1 layer and the low refractive index layer with QWOT of 1.0 or more is LB1 layer, The layer between the HB1 layer and the LB1 layer is composed of a single layer or a plurality of layers, and is a MB1 layer in which QWOT per layer of all these layers is 1.0 or less, It has one or more of the stacked structures shown in the following formula (HB1 layer / MB1 layer / LB1 layer) [3] The optical filter according to [1] or [2], wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiA-1) to (iiA-3). (iiA-1) The total number of stacked layers is 1 to 80 (iiA-2) It includes a high refractive index layer HA with a refractive index of 1.8 or more and 2.5 or less, and a low refractive index layer LA with a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HA to the total physical film thickness of the low refractive index layer LA is 0.3 to 0.8 (iiA-3) Among the high refractive index layers, the layer with QWOT of 1.0 or more and closest to the glass substrate in the n-th position is the HA n layer, and among the low refractive index layers, the layer with QWOT of 1.0 or more and closest to the glass substrate next to the HA n layer is the LA n layer, when the HA n layer and the LA n layer, the layer between them is a MA layer composed of a single layer or multiple layers and having a total QWOT of 1 or less 2n-1 layer, and the LA n layer and the HA layer with QWOT of 1.0 or more and closest to the glass substrate in the (n + 1)-th position n+1 layer, the layer between them is a MA layer composed of a single layer or multiple layers and having a total QWOT of 1 or less 2n layer, and It has a repeating structure shown by the following formula (n is a natural number of 2 or more) (HA1 layer / MA1 layer / LA1 layer / MA2 layer) ··· (HA n layer / MA 2n-1 layer / LA n layer / MA 2n layer) [4] The optical filter according to any one of [1] to [3], wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiC-1) to (iiC-3). (iiC-1) The total number of stacked layers is 1 to 60 (iiC-2) It includes a high refractive index layer HC with a refractive index of 1.8 or more and 2.5 or less, and a low refractive index layer LC with a refractive index of 1.4 or more and 1.6 or less. The ratio of the total physical film thickness of the high refractive index layer HC to the total physical film thickness of the low refractive index layer LC is 0.5 to 0.9, and the ratio of the total QWOT of the high refractive index layer HC to the total QWOT of the low refractive index layer LC is 1.1 to 1.5. (iiC-3) It has a laminated structure shown by the following formula. (HC2 layer / LC2 layer / HC2 layer) / MC1 layer / (LC1 layer / HC1 layer / LC1 layer) / MC1 layer / (HC2 layer / LC2 layer / HC2 layer) HC1 layer, HC2 layer: Each independently, a high refractive index layer with a QWOT of 1.0 or more. LC1 layer, LC2 layer: Each independently, a low refractive index layer with a QWOT of 1.0 or more. MC1 layer: Each independently, a layer composed of a single layer or multiple layers with a total QWOT of 1 or less. 〔5〕The optical filter according to any one of 〔1〕~〔4〕, wherein the glass substrate contains ytterbium. 〔6〕The optical filter according to any one of 〔1〕~〔5〕, wherein the optical filter satisfies the following spectral characteristic (i-7). When any main surface is the incident direction, the absorption loss amount at a wavelength of X nm X is defined as follows. (Absorption loss amount X ) [%] = 100 - (transmittance at an incident angle of 0 degrees) - (reflectance at an incident angle of 5 degrees) (i-7) The integrated value of the absorption loss amount at wavelengths of 430 to 1100 nm 430-1100 is 10000 or more 〔7〕The glass substrate is expressed in mol% based on oxides, SiO2 is 0.1 to 50 mol%, B2O3 is 15 to 40 mol%, P2O5 is 0 to 15 mol%, and Yb2O3 is 20 to 60 mol%. The optical filter according to any one of 〔1〕~〔6〕. 〔8〕The near-infrared absorbing dye contains a dye having a maximum absorption wavelength in the wavelength range of 680 to 800 nm, The optical filter according to any one of [1] to [7], wherein the light absorption layer satisfies all of the following spectral characteristics (iii-1) to (iii-2). (iii-1) In the spectral transmittance curve with wavelengths of 650 to 720 nm, the shortest wavelength at which the internal transmittance becomes 30% is λ A_VIS(30%) and in the spectral transmittance curve with wavelengths of 720 to 1000 nm, the shortest wavelength at which the internal transmittance becomes 30% is λ A_IR(30%) When this is the case, the following relational expression is satisfied |λ A_IR(30%) - λ A_VIS(30%) |≥ 100 nm (iii-2) When the optical density at a wavelength of 720 nm is OD _720 the following relational expression is satisfied OD _720 ≥ 2.0 [9] The optical filter according to any one of [1] to [8], wherein the optical filter satisfies all of the following spectral characteristics (i-8) to (i-11). (i-8) When one main surface is the incident direction, the average reflectance of light with wavelengths of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees (i-9) When one main surface is the incident direction, the maximum reflectance of light with wavelengths of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees (i-10) When one main surface is the incident direction, the average reflectance of light with wavelengths of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees (i-11) When one main surface is the incident direction, the maximum reflectance of light with wavelengths of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees

[10] The optical filter according to any one of [1] to [9], which satisfies all of the following spectral characteristics (i-12) to (i-15). (i-12) When the other main surface is the incident direction, the average reflectance of light with wavelengths of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees When the principal surface of the other side is taken as the incident direction, the maximum reflectance of light with a wavelength of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees. When the principal surface of the other side is taken as the incident direction, the average reflectance of light with a wavelength of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees. When the principal surface of the other side is taken as the incident direction, the maximum reflectance of light with a wavelength of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees. An imaging device including the optical filter according to any one of

[11] [1] to

[10] .

Example

[0086] Next, the present invention will be described more specifically by way of examples. For the measurement of each spectral characteristic, an ultraviolet-visible spectrophotometer (UH-4150 type, manufactured by Hitachi High-Technologies Corporation) was used. Note that the spectral characteristics when the incident angle is not particularly specified are the values measured at an incident angle of 0 degrees (perpendicular to the principal surface of the optical filter). The dyes used in each example are as follows. Compound 1 (cyanine compound): Synthesized based on Dyes and pigments 73 (2007) 344-352. Compound 2 (merocyanine compound): Synthesized based on the specification of German Patent Publication No. 10109243. Compound 3 (squarylium compound): Synthesized based on the specification of US Patent No. 5543086. Note that Compound 1 and Compound 3 are near-infrared absorbing dyes (NIR dyes), and Compound 2 is a near-ultraviolet absorbing dye (UV dye).

[0087]

Chemical formula

[0088] <Spectral characteristics of dyes> The maximum absorption wavelengths in the absorption spectra measured by dissolving the above pigments (Compounds 1 to 3) in dichloromethane are shown in Table 1 described later.

[0089] <Glass substrate> As the glass substrates, Glass A which is a light-absorbing glass and non-absorbing Glass B were prepared. For Glass A, raw materials were weighed and mixed so that in terms of mol% of oxides, it would be SiO2 7.5%, B2O3 23.6%, P2O5 7.5%, Yb2O3 47.2%, Ga2O3 11.8%, and La2O3 2.4%. They were put into a crucible with an internal volume of about 400 cc and melted at 1400 to 1650 °C for 2 hours in an air atmosphere. Then, they were clarified, stirred, and cast into a rectangular mold with a length of 100 mm × width of 50 mm × height of 20 mm preheated to approximately 300 °C to 500 °C, and slowly cooled to room temperature at about -1 °C / min. They were cut to a predetermined thickness in the range of length 40 mm × width 30 mm × thickness 0.3 to 1.5 mm, and both sides were optically polished to obtain a plate-shaped glass. Also, Glass B is a non-absorbing glass, and D263 glass (manufactured by Schott, borosilicate glass, commercially available product) was used.

[0090] Note that the following raw materials were used for each glass. SiO2: Oxide B2O3: One or more selected from oxide, PBO4, and H3BO3 P2O5: Either one or more of H3PO4 and PBO4 GeO2: Oxide ZrO2: Oxide Ga2O3: Oxide Yb2O3: Oxide La2O3: Oxide Al2O3: Either one or more of oxide and Al(OH)3 Note that the raw materials for the glass are not limited to the above, and known ones can be used.

[0091] The transmittance curves of light with wavelengths of 350 to 1200 nm for Glass A and Glass B (both Glass A and Glass B have a plate thickness of 0.4 mm and internal transmittance) are shown in Figure 2.

[0092] <Light absorption layer> One of the dyes of Compounds 1 to 3 was dissolved in a polyimide resin (manufactured by Mitsubishi Gas Chemical Company, C-3G30G), mixed at the concentrations described in the following table, and stirred and dissolved at 50 °C for 2 hours to obtain a coating solution. The obtained coating solution was applied to an alkaline glass (manufactured by SCHOTT, D263 glass, thickness 0.2 mm) by spin coating to form a light absorption layer having the film thickness and spectral characteristics shown in Table 1 below. In addition, the transmittance curve of light with wavelengths from 350 to 1200 nm of the light absorption layer is shown in Fig. 3.

[0093]

Table 1

[0094] <Example 1: Optical filter> On one main surface of a glass substrate (Glass A), a dielectric multilayer film A1 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the other main surface of the glass substrate, a dielectric multilayer film B1 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the surface of the dielectric multilayer film B1, a resin solution was applied with the same composition as the light absorption layer 1, and heated sufficiently to remove the organic solvent to form a light absorption layer. On the surface of the light absorption layer, a dielectric multilayer film C1 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. From the above, the optical filter of Example 1 was manufactured.

[0095] <Example 2> On one main surface of a glass substrate (Glass A), a dielectric multilayer film A2 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the other main surface of the glass substrate, a dielectric multilayer film C2 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the surface of the dielectric multilayer film C2, a resin solution was applied with the same composition as the light absorption layer 1, and heated sufficiently to remove the organic solvent to form a light absorption layer. On the surface of the light absorption layer, a dielectric multilayer film B2 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. From the above, the optical filter of Example 2 was manufactured.

[0096] <Example 3> On one main surface of a glass substrate (Glass A), a dielectric multilayer film C3 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the other main surface of the glass substrate, a dielectric multilayer film A3 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the surface of the dielectric multilayer film A3, a resin solution was coated with the same composition as the light absorption layer 1, and heated sufficiently to remove the organic solvent, thereby forming a light absorption layer. On the surface of the light absorption layer, a dielectric multilayer film B3 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. From the above, the optical filter of Example 3 was manufactured.

[0097] <Example 4> An optical filter of Example 4 was manufactured in the same manner as in Example 1, except that Glass B was used instead of Glass A as the glass substrate.

[0098] <Example 5: Optical Filter> On one main surface of a glass substrate (Glass A), a dielectric multilayer film X1 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the other main surface of the glass substrate, a dielectric multilayer film X2 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the surface of the dielectric multilayer film X2, a resin solution was coated with the same composition as the light absorption layer 1, and heated sufficiently to remove the organic solvent, thereby forming a light absorption layer. On the surface of the light absorption layer, a dielectric multilayer film X3 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. From the above, the optical filter of Example 5 was manufactured.

[0099] <Example 6: Optical Filter> On one main surface of a glass substrate (Glass A), a dielectric multilayer film Y1 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. On the other main surface of the glass substrate, a resin solution was coated with the same composition as the light absorption layer 1 and heated sufficiently to remove the organic solvent, thereby forming a light absorption layer. On the surface of the light absorption layer, a dielectric multilayer film Y3 was formed by alternately depositing SiO2 and TiO2 by vapor deposition. From the above, the optical filter of Example 6 was manufactured.

[0100] The configurations of the dielectric multilayer films A1 to A3, the dielectric multilayer films B1 to B3, and the dielectric multilayer films C1 to C3 are shown in Tables 2 to 10 below. Note that the order of the numbers (No.) corresponds to the stacking order.

[0101] [Table 2]

[0102] [Table 3]

[0103] [Table 4]

[0104] [Table 5]

[0105] [Table 6]

[0106] [Table 7]

[0107] [Table 8]

[0108]

Table 9

[0109]

Table 10

[0110] For each of the optical filters obtained as described above, the spectral transmittance curve at an incident angle of 0 degrees and the spectral reflectance curves at incident angles of 5 degrees and 40 degrees in the wavelength range of 350 to 1200 nm were measured using an ultraviolet-visible spectrophotometer. From the data of the obtained spectral characteristics, each characteristic shown in Table 12 below was calculated. In addition, the spectral transmittance and reflectance curves of the optical filters of Example 1 and Example 5 are shown in FIGS. 4 to 9, respectively.

[0111] Note that Examples 1 to 4 are examples, and Examples 5 to 6 are comparative examples.

[0112]

Table 11

[0113]

Table 12

[0114] From the above results, it can be seen that the optical filters of Examples 1 to 4 provided with the dielectric multilayer films 1 to 3 all have excellent reflection characteristics for light with wavelengths of 1300 to 1500 nm and 750 to 900 nm even at a high incident angle, and excellent shielding properties for light with wavelengths of 350 to 400 nm. On the other hand, the optical filter of Example 5 that does not include the dielectric multilayer films 1 and 3 satisfying the predetermined requirements had small reflection characteristics for light with wavelengths of 1300 to 1500 nm and insufficient shielding properties for light with wavelengths of 350 to 400 nm. In addition, the optical filter of Example 6 that does not include the dielectric multilayer film 2 was insufficient in both the reflection characteristics of light with wavelengths of 1300 to 1500 nm and 750 to 900 nm and the light shielding property of light with wavelengths of 350 to 400 nm.

Industrial Applicability

[0115] The optical filter according to this embodiment is excellent in the transmittance of visible light and specific near-infrared light even at a high incident angle, and excellent in the light shielding property of other near-infrared light. In recent years, with the progress of high performance, it is useful for applications such as imaging devices such as cameras and sensors for transportation machines.

Explanation of Reference Numerals

[0116] 1 Dielectric multilayer film 2 Dielectric multilayer film 3 Dielectric multilayer film 4 Light absorption layer 5 Glass substrate 10 Optical filter

Claims

1. An optical filter having a dielectric multilayer film 1, a glass substrate, a dielectric multilayer film 2, a light absorption layer, and a dielectric multilayer film 3 in this order, wherein the light absorption layer contains a near-infrared absorbing dye, and the optical filter satisfies all of the following spectral characteristics (i-1) to (i-6). (i-1) When one main surface is the incident direction, the average reflectance of light with a wavelength of 1300 to 1500 nm is 90% or more at an incident angle of 5 degrees and 90% or more at an incident angle of 40 degrees (i-2) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 1300 to 1500 nm is 95% or more at an incident angle of 5 degrees and 95% or more at an incident angle of 40 degrees (i-3) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 750 to 900 nm is 30% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 40 degrees (i-4) When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 750 to 900 nm is 80% or more at an incident angle of 5 degrees and 70% or more at an incident angle of 40 degrees (i-5) The average transmittance of light with a wavelength of 350 to 400 nm is 1% or less at an incident angle of 0 degrees and 2% or less at an incident angle of 40 degrees (i-6) The maximum transmittance of light with a wavelength of 350 to 400 nm is 2% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 40 degrees

2. The optical filter according to claim 1, wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiB-1) to (iiB-3). (iiB-1) The total number of stacked layers is 1 to 60 (iiB-2) It includes a high refractive index layer HB having a refractive index of 1.8 or more and 2.5 or less and a low refractive index layer LB having a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HB to the total physical film thickness of the low refractive index layer LB is 0.2 to 0.8 The high refractive index layer in which QWOT is 1.0 or more is defined as the HB layer in (iiB-3). １ When the low refractive index layer in which QWOT is 1.0 or more is defined as the LB layer １ then the HB １ layer and the LB １ layer is a layer composed of a single layer or a plurality of layers, and the QWOT per layer of all these layers is 1.0 or less, which is the MB １ layer, and It has one or more of the stacked structures shown in the following formula (HB １ layer / MB １ layer / LB １ layer)

3. The optical filter according to claim 1, wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiA-1) to (iiA-3). (iiA-1) The total number of stacked layers is 1 to 80 (iiA-2) It includes a high refractive index layer HA having a refractive index of 1.8 or more and 2.5 or less and a low refractive index layer LA having a refractive index of 1.4 or more and 1.6 or less, and the ratio of the total physical film thickness of the high refractive index layer HA to the total physical film thickness of the low refractive index layer LA is 0.3 to 0.8 Among the high refractive index layers, the layer where QWOT is 1.0 or more and which is the n-th closest to the glass substrate is defined as HA layer. ｎ Among the low refractive index layers, the layer where QWOT is 1.0 or more and which is the next closest to the glass substrate after the layer HA ｎ is defined as LA layer. ｎ When this is done, The HA ｎ layer and the LA ｎ layer, the layer therebetween is a MA layer composed of a single layer or a plurality of layers and having a total QWOT of 1 or less, ２ｎ－１ and The LA mentioned above ｎ layer and the HA ｎ＋１ layer, which is the layer closest to the (n + 1)-th layer on the glass substrate with QWOT being 1.0 or more, consists of a single layer or multiple layers and has a total QWOT of 1 or less, is the MA ２ｎ layer, and It has the repeating structure shown in the following formula (n is a natural number of 2 or more) (HA １ layer / MA １ layer / LA １ layer / MA ２ layer) ... (HA ｎ layer / MA ２ｎ－１ layer / LA ｎ layer / MA ２ｎ layer)

4. The optical filter according to claim 1, wherein at least one of the dielectric multilayer films 1 to 3 satisfies all of the following characteristics (iiC-1) to (iiC-3). (iiC-1) The total number of stacked layers is 1 to 60 (iiC-2) It includes a high refractive index layer HC having a refractive index of 1.8 or more and 2.5 or less, and a low refractive index layer LC having a refractive index of 1.4 or more and 1.6 or less. The ratio of the total physical film thickness of the high refractive index layer HC to the total physical film thickness of the low refractive index layer LC is 0.5 to 0.9, and the ratio of the total QWOT of the high refractive index layer HC to the total QWOT of the low refractive index layer LC is 1.1 to 1.5 (iiC-3) It has a stacked structure represented by the following formula (HC ２ layer / LC ２ layer / HC ２ layer) / MC １ layer / (LC １ layer / HC １ layer / LC １ layer) / MC １ layer / (HC ２ layer / LC ２ layer / HC ２ layer) HC １ layer, HC ２ layer: Each independently, a high refractive index layer with QWOT of 1.0 or more LC １ layer, LC ２ layers: each independently, a low refractive index layer having a QWOT of 1.0 or more MC １ Layer: A layer composed of a single layer or multiple layers, each independently having a total QWOT of 1 or less

5. The optical filter according to claim 1, wherein the glass substrate contains ytterbium.

6. The optical filter according to claim 1, wherein the optical filter satisfies the following spectral characteristic (i-7). When any main surface is taken as the incident direction, the absorption loss amount at a wavelength of X nm is defined as follows. Ｘ is defined as follows. (Absorption loss Ｘ ) [%] = 100 - (Transmittance at an incident angle of 0 degrees) - (Reflectance at an incident angle of 5 degrees) The integrated value of the absorption loss amount at a wavelength of 430 to 1100 nm is 10000 or more ４３０－１１００ ​

7. The glass substrate is expressed in mol% based on oxides SiO ２ in an amount of 0.1 to 50 mol%, B ２ O ３ is 15 to 40 mol%, P ２ O ５ is 0 to 15 mol%, and Yb ２ O ３ The optical filter according to claim 1, containing 20 to 60 mol% of

8. The near-infrared absorbing dye includes a dye having a maximum absorption wavelength in the wavelength range of 680 to 800 nm The optical filter according to claim 1, wherein the light absorption layer satisfies all of the following spectral characteristics (iii-1) to (iii-2). (iii-1) In the spectral transmittance curve with a wavelength of 650 to 720 nm, the shortest wavelength at which the internal transmittance becomes 30% is λ Ａ＿ＶＩＳ（３０％） is defined as, and in the spectral transmittance curve with a wavelength of 720 to 1000 nm, the shortest wavelength at which the internal transmittance becomes 30% is λ Ａ＿ＩＲ（３０％） is defined as, and the following relational expression is satisfied |λ Ａ＿ＩＲ（３０％） -λ Ａ＿ＶＩＳ（３０％） |≥100 nm (iii-2) When the optical density at a wavelength of 720 nm is OD ＿７２０ the following relational expression is satisfied OD ＿７２０ ≥2.0

9. The optical filter according to claim 1, wherein the optical filter satisfies all of the following spectral characteristics (i-8) to (i-11). (i-8) When one main surface is the incident direction, the average reflectance of light with a wavelength of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees (i-9) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees (i-10) When one main surface is the incident direction, the average reflectance of light with a wavelength of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees (i-11) When one main surface is the incident direction, the maximum reflectance of light with a wavelength of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees

10. The optical filter according to claim 1, which satisfies all of the following spectral characteristics (i-12) to (i-15). (i-12) When the other main surface is the incident direction, the average reflectance of light with a wavelength of 420 to 650 nm is 5% or less at an incident angle of 5 degrees and 5% or less at an incident angle of 40 degrees When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 420 to 650 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees When the other main surface is the incident direction, the average reflectance of light with a wavelength of 1030 to 1150 nm is 9% or less at an incident angle of 5 degrees and 10% or less at an incident angle of 40 degrees When the other main surface is the incident direction, the maximum reflectance of light with a wavelength of 1030 to 1150 nm is 10% or less at an incident angle of 5 degrees and 15% or less at an incident angle of 40 degrees **Claim 11** An imaging device including the optical filter according to any one of Claims 1 to 10

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