Optical Filters

Abstract

To provide an optical filter excellent in weatherability, excellent in transparency in a visible light region, excellent in shielding properties in a near-infrared light region, especially, in a large region including even the vicinity of 1200 nm and having small change in spectral characteristics even at a high incident angle.SOLUTION: An optical filter includes: a dielectric multilayer 1; a base material including a near-infrared absorption glass and a resin film; and a dielectric multilayer 2 in this order. The resin film includes a near-infrared absorption dye and a resin; the near-infrared absorption glass is fluorophosphate glass containing P, Cu and F; and the optical filter satisfies all of specific spectral characteristics (i-1) to (i-3) and (i-5) to (i-7).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical filter that transmits visible light and blocks near-infrared light. [Background technology]

[0002] In order to reproduce color tones well and obtain clear images, imaging devices using solid-state imaging elements use optical filters that transmit light in the visible range (hereinafter also referred to as "visible light") and block light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light").

[0003] Examples of such optical filters include various types, such as reflective filters in which dielectric thin films with different refractive indices are alternately stacked on one or both sides of a transparent substrate (dielectric multilayer film) and utilize optical interference to reflect light to be blocked, absorption filters that absorb light to be blocked using glass or dyes that absorb light in a specific wavelength range, and filters that combine reflective and absorption types.

[0004] Patent Document 1 describes an optical filter containing a copper complex that absorbs light in the near-infrared region. Patent Document 2 describes an optical filter containing a dye that absorbs light in the near-infrared region. Patent Document 3 describes an optical filter that includes glass that absorbs light in the near-infrared region and a reflective layer made of a dielectric multilayer film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent No. 6802938 [Patent Document 2] International Publication No. 2019 / 168090 [Patent Document 3] International Publication No. 2019 / 151348 Summary of the Invention [Problem to be solved by the invention]

[0006] The optical filter described in Patent Document 1 is made by coating a copper complex that absorbs light onto phosphate glass, and has poor moisture resistance, leaving room for improvement in terms of weather resistance.

[0007] The optical filter described in Patent Document 2 has room for improvement in that it blocks a wide range of light in the near-infrared region solely by the absorption characteristics of the dye, resulting in a decrease in transmittance in the visible light region.

[0008] Furthermore, optical filters that utilize the reflection of a dielectric multilayer film, such as the optical filter described in Patent Document 3, have concerns about changes in the spectral transmittance curve and spectral reflectance curve depending on the angle of incidence because the optical film thickness of the dielectric multilayer film changes depending on the angle of incidence of light. For example, if the amount of light captured in the visible light range changes at high angles of incidence, this can cause a problem of reduced image reproducibility. In particular, with the recent trend toward lower profile camera modules, use under high angles of incidence is expected, and optical filters that are less susceptible to the effects of the angle of incidence are therefore required.

[0009] The present invention aims to provide an optical filter that has excellent weather resistance, excellent transmittance in the visible light region, excellent shielding properties in the near-infrared light region, particularly a wide range of shielding properties including around 1200 nm, and exhibits little change in spectral characteristics even at high angles of incidence. [Means for solving the problem]

[0010] The present invention provides an optical filter and the like having the following configuration. [1] An optical filter comprising a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2 in this order, the resin film contains a near-infrared absorbing dye and a resin, the near-infrared absorbing glass is a fluorophosphate glass containing P, Cu, and F; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-5) to (i-7). (i-1) Average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 60 degrees. 440-600(60deg)AVE The absolute difference between (i-2) The average transmittance T 440-600(0deg)AVE More than 75% (i-3) Wavelength IR_T at which transmittance is 50% at an incident angle of 0 degrees 50(0deg) is in the wavelength range of 580 to 640 nm (i-5) Average transmittance T at wavelengths of 800 to 1200 nm and an incident angle of 0 degrees 800-1200(0deg)AVE is 5% or less (i-6) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees 440-650(5deg)AVE is 1.5% or less (i-7) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 to 1200 nm and an incident angle of 5 degrees 850-1200(5deg)AVE More than 60% [Effects of the Invention]

[0011] According to the present invention, an optical filter can be provided which has excellent weather resistance, excellent transmittance in the visible light region, excellent shielding properties in the near-infrared light region, particularly in a wide range including around 1200 nm, and which exhibits little change in spectral characteristics even at high angles of incidence. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of an optical filter according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 1. [Figure 3] FIG. 3 is a diagram showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, dielectric multilayer film 1 side) of the optical filter of Example 1. [Figure 4] FIG. 4 is a diagram showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, dielectric multilayer film 2 side) of the optical filter of Example 1. [Figure 5]FIG. 5 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 2. [Figure 6] FIG. 6 is a diagram showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, dielectric multilayer film 1 side) of the optical filter of Example 2. [Figure 7] FIG. 7 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 3. [Figure 8] FIG. 8 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 4. [Figure 9] FIG. 9 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 5. [Figure 10] FIG. 10 is a diagram showing the spectral transmittance curves (0 degree transmittance, 60 degree transmittance) of the optical filter of Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described. In this specification, the near-infrared absorbing dye may be abbreviated as "NIR dye" and the ultraviolet absorbing dye may be abbreviated as "UV dye". In this specification, a compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. A dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. Furthermore, a group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

[0014] In this specification, the internal transmittance is the transmittance obtained by subtracting the influence of interface reflection from the measured transmittance, which is expressed by the formula {measured transmittance (incident angle 0 degrees) / (100-reflectance (incident angle 5 degrees))}×100.

[0015] In this specification, a transmittance of, for example, 90% or more in a specific wavelength range means that the transmittance is not less than 90% across the entire wavelength range, i.e., the minimum transmittance is 90% or more across the wavelength range. Similarly, a transmittance of, for example, 1% or less in a specific wavelength range means that the transmittance is not more than 1% across the entire wavelength range, i.e., the maximum transmittance is 1% or less across the wavelength range. The same applies to internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic means of the transmittance and internal transmittance per 1 nm in the wavelength range. The reflectance when the dielectric multilayer film side is the incident direction refers to the optical characteristics of the light reflected when measurement light is incident on the surface of the dielectric multilayer film provided in the optical filter. The spectral characteristics can be measured using an ultraviolet-visible spectrophotometer. In this specification, the use of "to" to indicate a range of values ​​includes the upper and lower limits.

[0016] <Optical filters> The optical filter according to this embodiment comprises, in this order, a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2. The resin film contains a near-infrared absorbing dye and a resin, and the near-infrared absorbing glass is a fluorophosphate glass containing P, Cu, and F. In the present invention, as will be described later, the light-blocking properties of the optical filter are preferably ensured by the absorption characteristics of the near-infrared absorbing glass and the near-infrared absorbing dye, and the reflection characteristics of the dielectric multilayer film. Since the absorption characteristics are relatively little affected by the angle of incidence of light, an optical filter can be obtained whose spectral characteristics change little even at high angles of incidence.

[0017] An example of the configuration of an optical filter according to this embodiment will be described with reference to the drawings, in which: Figure 1 is a cross-sectional view schematically showing an example of an optical filter according to an embodiment.

[0018] The optical filter 1B shown in FIG. 1 is an example including a dielectric multilayer film 21, a substrate 40 having a near-infrared absorbing glass 10 and a resin film 30, and a dielectric multilayer film 22.

[0019] The optical filter according to this embodiment satisfies all of the following spectral characteristics (i-1) to (i-5). (i-1) Average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 60 degrees. 440-600(60deg)AVE The absolute difference between (i-2) The average transmittance T 440-600(0deg)AVE More than 75% (i-3) Wavelength IR_T at which transmittance is 50% at an incident angle of 0 degrees 50(0deg) is in the wavelength range of 580 to 640 nm (i-4) Average transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees 700-800(0deg)AVE is 1.1% or less (i-5) Average transmittance T at wavelengths of 800 to 1200 nm and an incident angle of 0 degrees 800-1200(0deg)AVE is 5% or less

[0020] The optical filter according to this embodiment, which satisfies all of the spectral characteristics (i-1) to (i-5), has high visible light transmittance as shown in characteristic (i-2), and high near-infrared light blocking properties over a wide range from 800 to 1200 nm as shown in characteristics (i-4) and (i-5). Furthermore, there is a wavelength within a specific wavelength range where the transmittance is 50% at an incident angle of 0 degrees as shown in characteristic (i-3), and further, the change in the spectral characteristics of visible light is small even at high incident angles as shown in characteristic (i-1).

[0021] Satisfying the spectral characteristics (i-1) and (i-2) means that the visible light transmittance does not decrease even at a high incident angle, and the visible light transmittance is excellent. The absolute value of the difference in the spectral characteristic (i-1) is preferably 15% or less, more preferably 10% or less. Average transmittance T 440-600(0deg)AVE is preferably 76% or more, more preferably 77% or more. The spectral characteristics (i-1) and (i-2) can be achieved, for example, by using a dielectric multilayer film with low reflectance in the visible light region, and by using a near-infrared absorbing dye with high transmittance in the visible light region and fluorophosphate glass as the near-infrared absorbing glass.

[0022] Satisfying the spectral characteristic (i-3) means that the near-infrared light region can be blocked and visible transmitted light can be efficiently captured. Wavelength IR_T 50(0deg) is preferably 580 to 630 nm, more preferably 590 to 625 nm. The spectral characteristic (i-3) can be achieved, for example, by using a fluorophosphate glass, which will be described later, as the near-infrared absorbing glass.

[0023] Satisfying the spectral characteristic (i-4) means that the near-infrared light-shielding property is excellent. Average transmittance T 700-800(0deg)AVE is preferably 0.6% or less, more preferably 0.3% or less, and particularly preferably 0.1% or less. The spectral characteristic (i-4) can be achieved, for example, by using a squarylium dye, which will be described later, as the near-infrared absorbing dye, and a fluorophosphate glass, which will be described later, as the near-infrared absorbing glass.

[0024] Satisfying the spectral characteristic (i-5) means that the film has excellent light-blocking properties in the near-infrared light region up to a wide range around 1200 nm. Average transmittance T 800-1200(0deg)AVE is preferably 4% or less, more preferably 3% or less. The spectral characteristic (i-5) can be achieved, for example, by using a fluorophosphate glass, which will be described later, as the near-infrared absorbing glass.

[0025] The optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (i-6) to (i-7). (i-6) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees 440-650(5deg)AVE is 1.5% or less (i-7) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 to 1200 nm and an incident angle of 5 degrees 850-1200(5deg)AVE More than 60% The spectral characteristics (i-6) to (i-7) substantially reflect the reflection characteristics of the dielectric multilayer film 1, which means that the dielectric multilayer film 1 has low visible light reflection characteristics and reflection characteristics in the near-infrared light region. Average reflectance R1 440-650(5deg)AVE is more preferably 1.3% or less, further preferably 1.2% or less, and particularly preferably 1.1% or less. Average reflectance R1 850-1200(5deg)AVE is more preferably 63% or more, even more preferably 65% ​​or more, and particularly preferably 70% or more. In addition, if the reflection characteristics in the near-infrared region are too strong, the visible light transmittance is likely to change at high incident angles. 850-1200(5deg)AVE is preferably 95% or less, more preferably 90% or less.

[0026] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-8). (i-8) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees 440-650(60deg)AVE is less than 10% The spectral characteristic (i-8) substantially reflects the reflection characteristics of the dielectric multilayer film 1, and means that the dielectric multilayer film 1 has small visible light reflection characteristics even at a high incident angle. Average reflectance R1 440-650(60deg)AVE is more preferably 9% or less, and even more preferably 8.5% or less.

[0027] The optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees 440-650(5deg)AVE is less than 2.0% (i-10) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 5 degrees 700-850(5deg)AVE is 1.2% or less The spectral characteristics (i-9) to (i-10) substantially reflect the reflection characteristics of the dielectric multilayer film 2, meaning that the dielectric multilayer film 2 is an anti-reflection film with low reflection characteristics in both the visible light region and the near-infrared light region. Average reflectance R2 440-650(5deg)AVE is more preferably 1.70% or less, and further preferably 1.53% or less. Average reflectance R2 700-850(5deg)AVE is more preferably 1.1% or less, further preferably 1.0% or less, and particularly preferably 0.8% or less.

[0028] The optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (i-11) to (i-12). (i-11) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees 440-650(60deg)AVE Less than 10% (i-12) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 60 degrees 700-850(60deg)AVE is less than 8% The spectral characteristics (i-11) to (i-12) substantially reflect the reflection characteristics of the dielectric multilayer film 2, meaning that the dielectric multilayer film 2 is an anti-reflection film with low reflection characteristics in both the visible light region and the near-infrared light region, even at high incident angles. Average reflectance R2 440-650(60deg)AVE is more preferably 9% or less, and even more preferably 8.5% or less. Average reflectance R2 700-850(60deg)AVE is more preferably 7.5% or less, even more preferably 7.0% or less, and particularly preferably 6% or less.

[0029] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-13). (i-13) When the dielectric multilayer film 1 side is the incident direction, the wavelength IR_R at which the reflectance becomes 50% at an incident angle of 5 degrees in the wavelength range of 750 to 900 nm 50(5deg) and the wavelength IR_T at which the transmittance is 50% at an incident angle of 5 degrees in the wavelength range of 500 to 700 nm. 50(5deg)The absolute value of the difference is 160 nm or more Satisfying the spectral characteristic (i-13) means that the light-shielding region of the reflection characteristic is separated from the light-shielding region of the absorption characteristic. The absolute value of the difference in the spectral characteristic (i-13) is more preferably 165 nm or more, even more preferably 170 nm or more, and particularly preferably 185 nm or more.

[0030] The optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (i-14) to (i-15). When the dielectric multilayer film 1 side is the incident direction, the amount of absorption loss at wavelengths X to Y nm X-Y is defined below. (Absorption loss X-Y ) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees) (i-14) Absorption loss at wavelengths of 700 to 800 nm 700-800 The average value of 25% or more (i-15) Absorption loss at wavelengths of 850 to 1000 nm 850-1000 The average value of 17% or more The greater the absorption loss, the more light in that wavelength range is absorbed. Satisfying the spectral characteristics (i-14) to (i-15) means that a certain percentage of the spectral characteristics is due to absorption loss. The greater this percentage, the less variation in the spectral characteristics between normal and oblique incident light can be expected. Absorption loss 700-800 The average value is more preferably 26.5% or more, and even more preferably 28% or more. Absorption loss 850-1000 The average value is more preferably 18% or more, and even more preferably 20% or more. The spectral properties (i-14) to (i-15) can be achieved, for example, by using a near-infrared absorbing dye having a maximum absorption wavelength in the wavelength range of 700 to 800 nm.

[0031] <Near-infrared absorbing glass (fluorophosphate glass)> The near-infrared absorbing glass in the optical filter according to this embodiment is a fluorophosphate glass containing P, Cu, and F (hereinafter, also referred to as the fluorophosphate glass of this embodiment, or simply as fluorophosphate glass or glass).

[0032] By adding Cu to fluorophosphate glass containing P and F, it is possible to maintain a high transmittance of light in the visible region while suppressing the transmittance of light in the near-infrared region. Furthermore, by adding F to the glass, it is possible to improve weather resistance such as moisture resistance.

[0033] Each component that may constitute the fluorophosphate glass of this embodiment and its preferred content are described below. In this specification, unless otherwise specified, the content of each component and the total content are expressed in mass %. Furthermore, the transmittance of the glass of this embodiment includes the reflective properties of the glass surface (i.e., it is not the internal transmittance of the glass).

[0034] In the fluorophosphate glass of this embodiment, P is P 5+ It is contained as P 5+ is the main component that forms fluorophosphate glass and is an essential component for improving the near-infrared blocking properties. 5+ If the content is 30% or more, the effect is sufficiently obtained, and if it is 70% or less, problems such as the glass becoming unstable or the weather resistance being reduced are unlikely to occur. 5+ The content is preferably 30 to 70%, more preferably 31% or more, even more preferably 32% or more, still more preferably 33% or more, and more preferably 60% or less, even more preferably 50% or less, still more preferably 45% or less, and most preferably 43% or less. In addition, P 5+ As the raw material for (2), phosphoric acid or a salt thereof is preferably used from the viewpoint of suppressing corrosion of the platinum crucible and suppressing volatilization of the components.

[0035] In the fluorophosphate glass of this embodiment, F is F - It is contained as F - is an essential component for stabilizing the glass and improving the weather resistance. - When the total amount of component elements other than F is taken as 100 mass%, the amount of F contained in the glass - The content of F is expressed as an external percentage. - The content of F is preferably 5 to 70% by weight. - If the content is 5% or more in terms of the external proportion, a sufficient weather resistance effect can be obtained, and if the content is 70% or less in terms of the external proportion, problems such as a decrease in transmittance of light in the visible region, a decrease in mechanical properties such as strength, hardness, and elastic modulus, and an increase in ultraviolet transmittance are unlikely to occur. The external proportion is more preferably 6% or more, even more preferably 8% or more, still more preferably 8.5% or more, and most preferably 10% or more, and also more preferably 60% or less, even more preferably 50% or less, still more preferably 40% or less, and most preferably 25% or less.

[0036] In the fluorophosphate glass of this embodiment, Cu is Cu + or Cu 2+ However, in this specification, all of them are contained as Cu. 2+ The content is listed when present as a substance. Cu 2+ Cu is an essential component for blocking near-infrared rays. 2+ The content of Cu is preferably 1 to 20%. 2+ If the content is 1% or more, the effect of this element and the effect of increasing the transmittance of visible light of the glass obtained when co-doped with Mo are sufficiently obtained, and if it is 20% or less, problems such as the generation of devitrification inclusions in the glass and a decrease in transmittance of visible light are unlikely to occur. The content is more preferably 4.5% or more, even more preferably 6% or more, even more preferably 7.5% or more, and most preferably 7.8% or more, and more preferably 18% or less, even more preferably 16% or less, even more preferably 13% or less, and most preferably 12% or less.

[0037] The total Cu content is the total amount of Cu expressed in mass %, including monovalent, divalent, and other valences present, and is the total amount of Cu in the glass of this embodiment (however, F - When the total Cu content (excluding the content of Cu) is taken as 100 mass %, the range of the total Cu content in the glass is preferably 1 to 20 mass %. If the total Cu content is 1 mass % or more, the near-infrared blocking effect can be sufficiently obtained even if the glass plate thickness is thin, and if it is 20 mass % or less, a decrease in visible transmittance can be suppressed. It is more preferably 4.5% or more, even more preferably 6% or more, even more preferably 7.5% or more, and most preferably 9% or more, and more preferably 18% or less, even more preferably 16% or less, even more preferably 13% or less, and most preferably 11.5% or less. Note that Cu + The mass% content of (Cu + The content of Cu can be determined in the range of 0.01 to 4.0% so that the content of Cu (Cu content) × 100 [%] is 0.01 to 4.0%.

[0038] Al 3+ is a component that forms glass and is a component that increases the strength of glass and weather resistance of glass. 3+ If it contains Al 3+ If the content of Al is 2% or more, the effect is sufficiently obtained, and if it is 20% or less, problems such as the glass becoming unstable or the near-infrared blocking ability decreasing are unlikely to occur. 3+ The content is preferably 0 to 20%, more preferably 2% or more, even more preferably 3% or more, even more preferably 3.5% or more, and most preferably 5% or more, and more preferably 18% or less, even more preferably 15% or less, even more preferably 13% or less, and most preferably 10% or less. In addition, Al 3+ As raw materials for AlF3, Al2O3, Al(OH)3, etc. can be used. Among them, the increase in melting temperature, the generation of unmelted material, and F - It is preferable to use AlF3 because problems such as a decrease in the amount of AlF3 charged and the resulting instability of the glass are unlikely to occur.

[0039] Li + Li is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, and stabilizes glass. + The content of Li is preferably 0 to 20%. + If the content is 20% or less, problems such as the glass becoming unstable or the near-infrared blocking ability decreasing are unlikely to occur. It is more preferably 18% or less, even more preferably 15% or less, still more preferably 12% or less, and most preferably 10% or less.

[0040] In the fluorophosphate glass of this embodiment, Na is + It can be contained as: Na + is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, and stabilizes glass. + The inclusion of Cu in fluorophosphate glass is effective in increasing the transmittance of light in the visible region of the glass obtained when co-doped with Mo. The mechanism behind this is explained as follows. + There are oxygen ions around Cu, and these oxygen ions are negatively charged. The electric field generated by the negative charge + and Mo 6+ The electrons (e - ) movement (Cu + →Cu 2+ +e - ) and (Mo 6+ +e - →Mo 5+ ) has the effect of inhibiting the formation of Na in fluorophosphate glass. + The presence of Na + The positive charge of Cu neutralizes the negative charge of the oxygen ions. + and Mo 5+ The electron transfer between the two is promoted, and Cu, which has optical absorption properties in the visible region, is formed. + The proportion of is reduced, and the light transmittance in the visible region is increased.

[0041] Glass is Na + If it contains Na + The content of Na is preferably 0.1 to 25%. + If the content is 25% or less, the glass is less likely to become unstable. It is more preferably 0.5% or more, even more preferably 1% or more, even more preferably 2% or more, and most preferably 3% or more, and is more preferably 20% or less, even more preferably 18% or less, even more preferably 14% or less, and most preferably 10% or less.

[0042] K + is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. + The content of K is preferably 0 to 25%. + If the content is 25% or less, the glass is less likely to become unstable, which is preferable, more preferably 23% or less, even more preferably 20% or less, still more preferably 18% or less, and most preferably 15% or less.

[0043] R + (Li + , Na + , and K + The components R are used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. + The total amount of Li + , Na + , and K + The total amount (ΣR + If ΣR ) is 0.1% or more, the effect is sufficient, and if it is 30% or less, the glass is less likely to become unstable, which is preferable. + The content is preferably 0.1 to 30%, more preferably 1% or more, even more preferably 3% or more, even more preferably 5% or more, and most preferably 8% or more, and more preferably 28% or less, even more preferably 27% or less, even more preferably 26% or less, and most preferably 25% or less.

[0044] Mg 2+ is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. 2+ The content of Mg is preferably 0 to 10%. 2+ If the content is 10% or less, problems such as the glass becoming unstable or the near-infrared blocking ability decreasing are unlikely to occur. It is more preferably 8% or less, even more preferably 6% or less, even more preferably 5% or less, and most preferably 3% or less.

[0045] Ca 2+ Ca is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. 2+ The content of Ca is preferably 0 to 20%. 2+ If the content is 20% or less, problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur. It is more preferably 0.1% or more, even more preferably 1% or more, even more preferably 2% or more, and most preferably 3% or more, and is more preferably 18% or less, even more preferably 15% or less, even more preferably 10% or less, and most preferably 6% or less.

[0046] Sr 2+ is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, and stabilizes glass. 2+ The content of Sr is preferably 0 to 30%. 2+ If the content is 30% or less, problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur. It is more preferably 0.1% or more, even more preferably 1% or more, even more preferably 3% or more, and most preferably 5% or more, and is more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, and most preferably 10% or less.

[0047] Ba 2+ is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, etc. 2+ The content of Ba is preferably 0 to 40%. 2+ If the content is 40% or less, problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur. It is more preferably 0.1% or more, even more preferably 5% or more, even more preferably 10% or more, and most preferably 15% or more, and is more preferably 35% or less, even more preferably 30% or less, even more preferably 25% or less, and most preferably 23% or less.

[0048] R 2+ (Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ R) is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. 2+ The total amount of Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ The total amount (ΣR 2+ If ΣR is 10% or more, the effect is sufficient, and if it is 45% or less, the glass is less likely to become unstable. 2+ The content is preferably 10 to 45%, more preferably 15% or more, even more preferably 20% or more, even more preferably 23% or more, and most preferably 25% or more, and more preferably 40% or less, even more preferably 35% or less, even more preferably 33% or less, and most preferably 30% or less.

[0049] Zn 2+ has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. 2+ The content of Zn is preferably 0 to 30%. 2+If the content is 30% or less, problems such as glass instability, deterioration in the melting property of the glass, reduction in near-infrared cutoff properties, etc. are unlikely to occur. It is more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, and most preferably 5% or less.

[0050] Rb + is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. + The content of Rb is preferably 0 to 10%. + If the content is 10% or less, the glass is less likely to become unstable, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and most preferably 2% or less.

[0051] Cs + is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. + The content of Cs is preferably 0 to 10%. + If the content is 10% or less, the glass is less likely to become unstable, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and most preferably 2% or less.

[0052] B 3+ may be contained in an amount of up to 20% to stabilize the glass. 3+ If the content is 20% or less, problems such as deterioration in the weather resistance of the glass and reduction in near-infrared cutoff properties are unlikely to occur. It is more preferably 15% or less, even more preferably 10% or less, even more preferably 8% or less, and most preferably 5% or less.

[0053] Mo is Mo 5+ or Mo 6+ However, in this specification, all of them are contained as Mo. 6+ The content is listed when present as a substance. Mo 6+is a component for increasing the transmittance of light in the visible region of the glass. Mo is present in the glass. 6+ However, when Mo and Cu are co-doped in phosphate glass, the Cu in the glass + is the electron (e - ) and Cu 2+ Next (Cu + → Cu 2+ +e - ), Cu + The electrons emitted by Mo 6+ received Mo 5+ (5-valent) (Mo 6+ +e - → Mo 5+ This allows the absorption of Cu, which has absorption characteristics in the wavelength range of 300 nm to 600 nm. + The proportion of (monovalent) atoms decreases, and the transmittance of light with a wavelength of 400 nm to 540 nm increases. 5+ is thought to have the property of absorbing light with a wavelength of around 400 nm, and therefore the transmittance of light with a wavelength of around 400 nm is thought not to increase.

[0054] Mo 6+ The content of Mo is preferably 0 to 4%. 6+ When Mo is contained, its content is preferably 0.01 to 4%. 6+ If the content of this element is 0.01% or more, the effect of increasing the transmittance of light in the visible region of the glass is sufficient, and if it is 4% or less, problems such as a decrease in the near-infrared blocking ability and the occurrence of devitrification in the glass are unlikely to occur. The content is more preferably 0.05% or more, even more preferably 0.1% or more, even more preferably 0.2% or more, and most preferably 0.3% or more, and more preferably 3.5% or less, even more preferably 3% or less, even more preferably 2% or less, and most preferably 1% or less.

[0055] Mo 6+ If it contains Mo 6+ and Cu 2+ content ratio (Mo 6+ / Cu 2+) is preferably 0.01 to 0.39 by mass. + It is possible to sufficiently suppress the absorption of light in the visible light range by Cu 2+ In addition, by being 0.39 or less, the absorption of light in the near-infrared wavelength range by Mo can be sufficiently promoted. 5+ The transmittance in the visible region can be suppressed from decreasing due to the above-mentioned phenomenon. The transmittance is more preferably 0.02 or more, even more preferably 0.03 or more, even more preferably 0.05 or more, and most preferably 0.1 or more, and is more preferably 0.35 or less, even more preferably 0.3 or less, even more preferably 0.25 or less, and most preferably 0.2 or less.

[0056] The fluorophosphate glass of this embodiment may contain SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 in an amount of 10% or less to improve the weather resistance of the glass. If the content of these components is 10% or less, problems such as the generation of devitrification particles in the glass and a decrease in near-infrared blocking properties are unlikely to occur. The content is preferably 4% or less, more preferably 3% or less, even more preferably 2% or less, and even more preferably 1% or less.

[0057] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO are all components that, when present in glass, reduce the transmittance of light in the visible region. Therefore, it is preferable that these components are not substantially contained in the glass. Here, "substantially not contained in the glass" means that they are not contained except as unavoidable impurities, and that the components are not actively added. Specifically, this means that the content of each of these components in the glass is approximately 100 ppm by mass or less.

[0058] The fluorophosphate glass of this embodiment has a thermal expansion coefficient of 60×10 in the range of 30°C to 300°C. -7 / ℃~180×10 -7 / °C, preferably 65 x 10-7 / ℃~175×10 -7 / °C is more preferable, 70 × 10 -7 / ℃~170×10 -7 / °C is more preferred.

[0059] The fluorophosphate glass in the optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (ii-1) to (ii-3). (ii-1) Wavelength IR_T at which transmittance is 50% at an incident angle of 0 degrees 50(0deg) is in the wavelength range of 590 to 640 nm (ii-2) Transmittance T at a wavelength of 700 nm and an incident angle of 0 degrees 700(0deg) is 25% or less (ii-3) Average transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees 700-800(0deg)AVE is less than 10%

[0060] As shown in the spectral characteristics (ii-1) to (ii-3), near-infrared absorbing glass transmits visible light, with the region of 590 to 640 nm being the boundary between the transmission band and the absorption band, and the absorption band starting from 700 nm onwards. This allows for the production of an optical filter with excellent visible light transmittance and near-infrared light blocking properties. Wavelength IR_T 50(0deg) More preferably, it is 590 to 630 nm, and even more preferably, it is 590 to 624 nm. Transmittance T 700(0deg) is more preferably 20% or less, further preferably 15% or less, and particularly preferably 10% or less. Average transmittance T 700-800(0deg)AVE is more preferably 9.8% or less, and even more preferably 9.7% or less.

[0061] The fluorophosphate glass in the optical filter according to this embodiment preferably satisfies the following spectral characteristic (ii-4), thereby providing an optical filter with excellent blocking properties for near-infrared light of 800 nm and above. (ii-4) Average transmittance T at wavelengths of 800 to 1200 nm and an incident angle of 0 degrees 800-1200(0deg)AVE is less than 10% Average transmittance T 800-1200(0deg)AVEis more preferably 8% or less, and even more preferably 6% or less.

[0062] The thickness of the fluorophosphate glass in the optical filter according to this embodiment is preferably 0.5 mm or less, more preferably 0.4 mm or less, and from the viewpoint of maintaining the strength of the element, the thickness is preferably 0.1 mm or more, more preferably 0.15 mm or more.

[0063] <Dielectric multilayer film> The optical filter according to this embodiment includes a dielectric multilayer film 1 and a dielectric multilayer film 2. At least one of the dielectric multilayer films is preferably designed as a reflective film that reflects part of near-infrared light (hereinafter also referred to as an "NIR reflective film"). The other dielectric multilayer films may be designed as reflective films having a reflection range other than the near-infrared range, or as anti-reflection films.

[0064] The NIR reflective film preferably has wavelength selectivity such that it transmits visible light, transmits near-infrared light in the transmission region of the absorbing layer, and mainly reflects other near-infrared light.

[0065] As shown in the spectral characteristics (i-5) and (i-7) of the optical filter, it is preferable that at least one of the dielectric multilayer films is a reflective film having reflective properties in the near-infrared light region with wavelengths of 850 to 1200 nm, and that such properties provide light blocking. By combining the reflection characteristics of this specific wavelength region with the near-infrared absorbing dye having a maximum absorption wavelength in the range of 740 to 800 nm and the absorption characteristics of fluorophosphate glass, which mainly absorbs wavelengths of 700 to 1200 nm, it is possible to block a wide range of near-infrared light in the wavelength range of 700 to 1200 nm. On the other hand, as shown in the spectral characteristics (i-6) and (i-8) of the optical filter, it is preferable that the dielectric multilayer film serving as the reflective film has small changes in the reflection characteristics in the visible light region, which makes it possible to obtain an optical filter in which the spectral characteristics in the visible light region are less likely to change depending on the angle of incidence and ripples are reduced. From the above, it is preferable that at least one dielectric multilayer film is designed as a reflective film that does not reflect visible light but reflects near-infrared light (wavelength 800 to 1200 nm) at an incident angle of light of 0 to 60 degrees. The other dielectric multilayer films are preferably designed as anti-reflection layers that have low reflection characteristics in both the visible light region and the near-infrared light region, as shown in the spectral characteristics (i-9) to (i-12) of the optical filter above.

[0066] The dielectric multilayer film is composed of, for example, a dielectric multilayer film formed by laminating 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 the dielectric multilayer film is composed of a dielectric multilayer film formed by laminating two or more of these. The high refractive index film preferably has a refractive index of 1.6 or higher at a wavelength of 500 nm, more preferably 1.8 to 2.5, and particularly preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta2O5, TiO2, TiO, and Nb2O5. Other commercially available products include OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), and OA600 (a mixture of Ta2O5 and TiO2), all manufactured by Canon Optron. Of these, TiO2 is preferred from the standpoints of film formability, reproducibility in terms of refractive index, stability, and the like.

[0067] The medium-refractive index film preferably has a refractive index of 1.6 or more and less than 2.2 at a wavelength of 500 nm. Examples of materials for the medium-refractive index film include ZrO2, Nb2O5, Al2O3, HfO2, OM-4, OM-6 (a mixture of Al2O3 and ZrO2), and OA-100 sold by Canon Optron, and H4 and M2 (alumina lanthania) sold by Merck. Of these, Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred in terms of film-forming properties, reproducibility in refractive index, and stability.

[0068] The low refractive index film preferably has a refractive index of less than 1.6 at a wavelength of 500 nm, more preferably 1.38 to 1.5. Examples of materials for the low refractive index film include SiO2, SiO x N y、 Examples of commercially available products include S4F and S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Inc. Of these, SiO2 is preferred from the standpoint of reproducibility, stability, and economy in film formation.

[0069] The dielectric multilayer film preferably has a ratio of [sum of QWOTs of dielectric films with a relatively high refractive index, T(H)] / [sum of QWOTs of dielectric films with a relatively low refractive index, T(L)] of 1.6 or more. This makes it easy to obtain a dielectric multilayer film that satisfies the above-mentioned spectral characteristics of reflecting near-infrared light with a wavelength of 800 to 1100 nm and suppressing reflection of visible light, and it is also preferable that at least the dielectric multilayer film stacked on the light incident side satisfy this ratio relationship. Here, QWOT (Quater Wave Optical Thickness) is the optical thickness at λ / 4 of the wavelength, and is calculated from the physical thickness using the following formula. QWOT = Physical thickness / Center wavelength (500 nm) × 4 × Refractive index at wavelength 500 nm

[0070] When the dielectric multilayer film is a laminate of low refractive index films and high refractive index films, the sum of QWOTs T(H) is the sum of QWOTs of the high refractive index films, and the sum of QWOTs T(L) is the sum of QWOTs of the low refractive index films. Furthermore, when the dielectric multilayer film is a laminate of a low refractive index film and a medium refractive index film, the sum of QWOTs T(H) is the sum of QWOTs of the medium refractive index films, and the sum of QWOTs T(L) is the sum of QWOTs of the low refractive index films. When the dielectric multilayer film is a laminate of a medium refractive index film and a high refractive index film, the sum of QWOTs T(H) is the sum of QWOTs of the high refractive index films, and the sum of QWOTs T(L) is the sum of QWOTs of the medium refractive index films.

[0071] The dielectric multilayer film is preferably a multilayer film in which 10 or more H2 layers and 10 or more M2 layers defined below are alternately stacked: H2 layer: A single layer with a refractive index of 1.8 to 2.5 and a QWOT of 1.1 to 3.5 M2 layer: A single layer or multiple layers present between two H2 layers and with a total QWOT of 1.2 to 1.8

[0072] The specific laminated structure is a structure in which single layers (H2 layers) with a high refractive index and optical thickness and layers (M2 layers) with a total optical thickness within a predetermined range are alternately laminated in 10 or more layers. This structure makes it easy to obtain a dielectric multilayer film that reflects near-infrared light with a wavelength of 800 to 1200 nm and has low reflectance for visible light. The M2 layer may be a single layer or multiple layers as long as it has a predetermined optical thickness, but it is preferable that it be composed of multiple layers in order to obtain smoother spectral characteristics, and the minimum thickness of a single layer is preferably 5 nm or more, more preferably 10 nm or more. Furthermore, the refractive index of the dielectric film that constitutes the M2 layer is preferably the same as or lower than the refractive index of the H2 layer.

[0073] It is preferable that the dielectric multilayer film having the above-mentioned specific layered structure is at least designed as a reflective film. When a dielectric multilayer film designed as a reflective film has the above-mentioned laminated structure, it is preferable that the layer closest to the near-infrared absorbing glass out of the H2 layer and the M2 layer is the H2 layer. The H2 layer closest to the near-infrared absorbing glass may be laminated directly on the near-infrared absorbing glass, or another layer that does not correspond to either the H2 layer or the M2 layer may be present between the H2 layer closest to the near-infrared absorbing glass and the near-infrared absorbing glass.

[0074] In a dielectric multilayer film designed as a reflective film, the total number of laminated layers in the dielectric multilayer film is preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more. However, since a large total number of laminated layers can cause warping or an increase in film thickness, the total number of laminated layers is preferably 110 or less, more preferably 80 or less, and even more preferably 60 or less. Moreover, the thickness (physical thickness) of the dielectric multilayer film designed as a reflective film is preferably 1 to 6 μm overall.

[0075] When an optical filter is mounted on an imaging device, the dielectric multilayer film on the sensor side is usually preferably designed as an anti-reflection layer. The total number of layers in the dielectric multilayer film designed as an anti-reflection layer is preferably 40 or less, more preferably 30 or less, even more preferably 20 or less, and is preferably 6 or more. Moreover, the thickness (physical thickness) of the dielectric multilayer film designed as an antireflection layer is preferably 0.2 to 1.0 μm overall.

[0076] The dielectric multilayer film can be formed by, for example, a vacuum film-forming process such as a CVD method, a sputtering method, or a vacuum deposition method, or a wet film-forming process such as a spray method or a dipping method.

[0077] When an optical filter is mounted in an imaging device, the dielectric multilayer film laminated on the glass surface is usually placed on the lens side, and the dielectric multilayer film laminated on the resin film surface is placed on the sensor side. Therefore, the optical filter according to this embodiment is preferably mounted so that dielectric multilayer film 1 is placed on the lens side and dielectric multilayer film 2 is placed on the sensor side.

[0078] <Resin film> The resin film in the optical filter according to this embodiment contains a resin and a near-infrared absorbing dye, where the resin refers to the resin that constitutes the resin film.

[0079] The near-infrared absorbing dye is preferably one that has a maximum absorption wavelength in the resin at 740 to 800 nm. By having a maximum absorption wavelength in the 740 to 800 nm range, the near-infrared light absorption region of the fluorophosphate glass containing Cu or the like is on the short wavelength side, so that the spectral characteristics of the dye can be more effectively utilized when combined with glass.

[0080] The near-infrared absorbing dye may be at least one selected from the group consisting of cyanine dyes, phthalocyanine dyes, squarylium dyes, naphthalocyanine dyes, and diimonium dyes, and may be used alone or in combination. Among these, squarylium dyes and cyanine dyes are preferred, as they can sharply absorb light in the 740 to 800 nm region and are likely to exhibit the effects of the present invention.

[0081] The content of the near-infrared absorbing dye in the resin film is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the resin. When two or more compounds are combined, the above content is the total of the respective compounds.

[0082] The resin film may contain other dyes, such as ultraviolet light absorbing dyes, to the extent that the effects of the present invention are not impaired. Examples of ultraviolet light absorbing dyes include oxazole dyes, merocyanine dyes, cyanine dyes, naphthalimide dyes, oxadiazole dyes, oxazine dyes, oxazolidine dyes, naphthalic acid dyes, styryl dyes, anthracene dyes, cyclic carbonyl dyes, and triazole dyes. Among these, merocyanine dyes are particularly preferred. Furthermore, one type may be used alone, or two or more types may be used in combination.

[0083] The resin is not limited as long as it is a transparent resin, and one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, enethiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamideimide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, polystyrene resin, etc. These resins may be used alone or in combination of two or more. From the viewpoint of the spectral characteristics, glass transition temperature (Tg) and adhesiveness of the resin film, one or more resins selected from polyimide resin, polycarbonate resin, polyester resin and acrylic resin are preferred.

[0084] When a plurality of dyes are used, they may be contained in the same resin film, or may be contained in separate resin films.

[0085] The resin film can be formed by dissolving or dispersing the dye, the resin or the raw material components of the resin, and the components that are mixed as needed in a solvent to prepare a coating solution, then coating the coating solution on a support, drying it, and then curing it as needed.The support in this case can be the near-infrared absorbing glass used in this filter, or a peelable support that is used only when forming the resin film.In addition, the solvent can be any dispersion medium that can be stably dispersed or a solvent that can be dissolved.

[0086] The coating liquid may also contain a surfactant to prevent voids caused by microbubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For example, the coating liquid can be applied by dip coating, cast coating, or spin coating. After the coating liquid is applied to a support, a resin film is formed by drying. When the coating liquid contains raw materials for a transparent resin, it is further subjected to a curing treatment such as thermal curing or photocuring.

[0087] The resin film can also be produced in a film form by extrusion molding. The resulting film-like resin film can be laminated on phosphate glass and integrated by thermocompression bonding or the like to produce a substrate.

[0088] The optical filter may have one resin film layer or two or more resin films. When two or more resin films are present, the layers may have the same or different configurations. When two or more resin films are present, they may all be laminated on the same main surface of the near-infrared absorbing glass, or may be laminated on different main surfaces.

[0089] The thickness of the resin film is 10 μm or less, preferably 5 μm or less, from the viewpoint of the in-plane film thickness distribution within the substrate after coating and the appearance quality, and is preferably 0.5 μm or more, from the viewpoint of achieving the desired spectral characteristics at an appropriate dye concentration. When the optical filter has two or more resin film layers, it is preferable that the total thickness of the resin film layers is within the above range.

[0090] The resin film in the optical filter according to this embodiment preferably satisfies all of the following spectral characteristics (iv-1) to (iv-4). (iv-1) Average internal transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees (in)440-600(0deg)AVE Over 90% (iv-2) Wavelength IR_T at which the internal transmittance is 50% at an incident angle of 0 degrees (in)50(0deg) is in the wavelength range of 630 to 645 nm (iv-3) Wavelength IR_T at which the internal transmittance is 70% at an incident angle of 0 degrees in the wavelength range of 500 to 700 nm (in)70(0deg) and the wavelength IR_T at which the transmittance is 20% at an incident angle of 0 degrees (in)20(0deg) The absolute value of the difference is 60 nm or less (iv-4) Average internal transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees (in)700-800(0deg)AVE is 5% or less The resin film has high visible light transmittance as shown in the spectral characteristics (iv-1), a wavelength of 630 to 645 nm is the boundary region between the transmission region and the absorption region as shown in the spectral characteristics (iv-2), a steep absorption characteristic in the boundary region as shown in the spectral characteristics (iv-3), and a high blocking ability for near-infrared light with a wavelength of 700 to 800 nm as shown in the spectral characteristics (iv-4).

[0091] Average internal transmittance T (in)440-600(0deg)AVE is more preferably 90.5% or more, and even more preferably 91% or more. Wavelength IR_T (in)50(0deg) is more preferably 632 to 640 nm, and even more preferably 634 to 640 nm. The absolute value of the difference in (iv-3) is more preferably 57 nm or less, and even more preferably 55 nm or less. Average internal transmittance T (in)700-800(0deg)AVEis more preferably 4% or less, and even more preferably 3% or less.

[0092] Furthermore, the substrate having the near-infrared absorbing glass and the resin film preferably satisfies all of the following spectral properties (iii-1) to (iii-3). (iii-1) Average internal transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees (in)440-600(0deg)AVE More than 75% (iii-2) Average internal transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees (in)700-800(0deg)AVE is 1.2% or less (iii-3) Average internal transmittance T at wavelengths of 800 to 1000 nm and an incident angle of 0 degrees (in)800-1000(0deg)AVE is 5% or less As shown in the spectral characteristics (iii-1) to (iii-3), the substrate made of a combination of glass and a near-infrared absorbing dye has high visible light transmittance and high near-infrared absorption characteristics in the range of 700 to 1000 nm. Average internal transmittance T (in)440-600(0deg)AVE is more preferably 76% or more, and even more preferably 77% or more. Average internal transmittance T (in)700-800(0deg)AVE is more preferably 1.1% or less, and further preferably 1.05% or less. Average internal transmittance T (in)800-1000(0deg)AVE is more preferably 4.5% or less, and further preferably 4.0% or less.

[0093] The optical filter of this embodiment may also include other components, such as a component (layer) that provides absorption by inorganic fine particles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic fine particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, and lanthanum boride. ITO fine particles and cesium tungstate fine particles have high transmittance for visible light and have light absorption properties over a wide range of infrared wavelengths exceeding 1200 nm, and therefore can be used when such infrared light blocking properties are required.

[0094] When the optical filter of this embodiment is used in an imaging device such as a digital still camera, it can provide an imaging device with excellent color reproducibility. Such an imaging device includes a solid-state imaging element, an imaging lens, and the optical filter of this embodiment. The optical filter of this embodiment can be used, for example, by being disposed between the imaging lens and the solid-state imaging element, or by being directly attached to the solid-state imaging element, imaging lens, etc. of the imaging device via an adhesive layer.

[0095] As described above, this specification discloses the following optical filters and the like. [1] An optical filter comprising a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2 in this order, the resin film contains a near-infrared absorbing dye and a resin, the near-infrared absorbing glass is a fluorophosphate glass containing P, Cu, and F; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-5). (i-1) Average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T at wavelengths of 440 to 600 nm and an incident angle of 60 degrees. 440-600(60deg)AVE The absolute difference between (i-2) The average transmittance T 440-600(0deg)AVE More than 75% (i-3) Wavelength IR_T at which transmittance is 50% at an incident angle of 0 degrees 50(0deg) is in the wavelength range of 580 to 640 nm (i-4) Average transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees 700-800(0deg)AVE is 1.1% or less (i-5) Average transmittance T at wavelengths of 800 to 1200 nm and an incident angle of 0 degrees 800-1200(0deg)AVE is 5% or less [2] The optical filter according to [1], which satisfies all of the following spectral characteristics (i-6) to (i-7). (i-6) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees 440-650(5deg)AVE is 1.5% or less (i-7) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 to 1200 nm and an incident angle of 5 degrees 850-1200(5deg)AVE More than 60% [3] The optical filter according to [1] or [2], wherein the optical filter satisfies the following spectral characteristic (i-8): (i-8) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees 440-650(60deg)AVE is less than 10% [4] The optical filter according to any one of [1] to [3], which satisfies all of the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees 440-650(5deg)AVE is less than 2.0% (i-10) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 5 degrees 700-850(5deg)AVE is 1.2% or less [5] The optical filter according to any one of [1] to [4], which satisfies all of the following spectral characteristics (i-11) to (i-12). (i-11) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees 440-650(60deg)AVE Less than 10% (i-12) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 60 degrees 700-850(60deg)AVE is less than 8% [6] The optical filter according to any one of [1] to [5], which satisfies the following spectral characteristic (i-13): (i-13) When the dielectric multilayer film 1 side is the incident direction, the wavelength IR_R at which the reflectance becomes 50% at an incident angle of 5 degrees in the wavelength range of 750 to 900 nm 50(5deg) and the wavelength IR_T at which the transmittance is 50% at an incident angle of 5 degrees in the wavelength range of 580 to 640 nm. 50(5deg) The absolute value of the difference is 160 nm or more [7] The optical filter according to any one of [1] to [6], which satisfies all of the following spectral characteristics (i-14) to (i-15). When the dielectric multilayer film 1 side is the incident direction, the amount of absorption loss at wavelengths X to Y nm X-Y is defined below. (Absorption loss X-Y ) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees) (i-14) Absorption loss at wavelengths of 700 to 800 nm 700-800 The average value of 25% or more (i-15) Absorption loss at wavelengths of 850 to 1000 nm 850-1000 The average value of 17% or more [8] The near-infrared absorbing glass has a thickness of 0.4 mm or less, The optical filter according to any one of [1] to [7], wherein the near-infrared absorbing glass satisfies all of the following spectral properties (ii-1) to (ii-3): (ii-1) Wavelength IR_T at which transmittance is 50% at an incident angle of 0 degrees 50(0deg) is in the wavelength range of 590 to 640 nm (ii-2) Transmittance T at a wavelength of 700 nm and an incident angle of 0 degrees 700(0deg) is 25% or less (ii-3) Average transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees 700-800(0deg)AVE is less than 10% [9] The optical filter according to any one of [1] to [8], wherein the substrate satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) Average internal transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees (in)440-600(0deg)AVE More than 75% (iii-2) Average internal transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees (in)700-800(0deg)AVE is 1.2% or less (iii-3) Average internal transmittance T at wavelengths of 800 to 1000 nm and an incident angle of 0 degrees (in)800-1000(0deg)AVE is 5% or less

[10] The optical filter according to any one of [1] to [9], wherein the near-infrared absorbing dye comprises a squarylium dye having a maximum absorption wavelength in the resin at 740 to 800 nm.

[11] The optical filter according to any one of [1] to

[10] , wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-4): (iv-1) Average internal transmittance T at wavelengths of 440 to 600 nm and an incident angle of 0 degrees (in)440-600(0deg)AVE Over 90% (iv-2) Wavelength IR_T at which the internal transmittance is 50% at an incident angle of 0 degrees (in)50(0deg) is in the wavelength range of 630 to 645 nm (iv-3) Wavelength IR_T at which the internal transmittance is 70% at an incident angle of 0 degrees in the wavelength range of 500 to 700 nm (in)70(0deg) and the wavelength IR_T at which the transmittance is 20% at an incident angle of 0 degrees (in)20(0deg) The absolute value of the difference is 60 nm or less (iv-4) Average internal transmittance T at wavelengths of 700 to 800 nm and an incident angle of 0 degrees (in)700-800(0deg)AVE is 5% or less

[12] The near-infrared absorbing glass is In mass%, P 5+ :30~70% Al 3+ :0~20% Li + :0~20% Na + :0~25% K + :0~25% Mg 2+ :0~10% Ca 2+ :0~20% Sr 2+ :0~30% Ba 2+ :0~40% ΣR + :0.1~30%(R + Li + , Na + , and K + one or more ingredients selected from ΣR 2+ :10~45%(R 2+is Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ one or more ingredients selected from Cu 2+ :1~20% The F contained in the glass - When the component elements other than F are taken as 100 mass%, - The optical filter according to any one of [1] to

[11] , which is a fluorophosphate glass containing 5 to 70 mass % of the above in terms of the outer ratio.

[13] An imaging device equipped with the optical filter according to any one of [1] to

[12] . [Example]

[0096] Next, the present invention will be explained more specifically with reference to examples. Each spectral characteristic was measured using an ultraviolet-visible spectrophotometer (UH-4150 model, manufactured by Hitachi High-Technologies Corporation). Unless the angle of incidence is specifically stated, the spectral characteristics are values ​​measured at an angle of incidence of 0 degrees (perpendicular to the main surface of the optical filter).

[0097] The dyes used in each example are as follows: Compound 1 (cyanine compound): Synthesized according to the method described in Dyes and Pigments, 73, 344-352 (2007). Compound 2 (squarylium compound): Synthesized based on WO 2017 / 135359. Compound 3 (merocyanine compound): Synthesized based on the specification of German Patent Publication No. 10109243. Compound 4 (squarylium compound): Synthesized based on JP 2017-110209 A. Compound 5 (squarylium compound): Synthesized based on WO 2014 / 088063 and WO 2016 / 133099.

[0098] [ka]

[0099] The maximum absorption wavelength of each dye in a polyimide resin is shown in Table 2 below.

[0100] <Spectral properties of glass> Glasses A1, A2, B, C, D1, and D2 shown in Table 1 were prepared as glasses for use in the examples and comparative examples. The above-mentioned glasses A1, A2, B, D1 and D2 are fluorophosphate glasses, and the glass C is phosphate glass.

[0101] The spectral characteristics of each glass are shown in Table 1 below.

[0102] [Table 1]

[0103] As shown above, it is clear that fluorophosphate glass has high transmittance in the visible light region and is excellent in blocking light in the near-infrared region, and is particularly excellent in blocking light with wavelengths of 700 nm to 800 nm.

[0104] <Example 1: Optical filter> A resin film was formed on one main surface of a fluorophosphate glass substrate A1 by the method described below, producing a base material having a glass substrate and a resin film. First, a polyimide resin ("C3G30G" (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc., refractive index 1.59) was dissolved in a 1:1 (mass ratio) mixture of γ-butyrolactone (GBL) and cyclohexanone to prepare a polyimide resin solution with a resin concentration of 8.5 mass %. Each of the dyes described above was added to the resin solution at the concentrations shown in Table 2 below per 100 mass parts of resin, and the mixture was stirred and dissolved at 50°C for 2 hours to obtain a coating solution. The resulting coating solution was applied to a glass substrate by spin coating to form a resin film 1 with a thickness of approximately 3 μm. On the other main surface of the glass substrate, TiO2 and SiO2 were deposited by vapor deposition in the composition shown in Table 3 below to form a dielectric multilayer film 1. Also, on the surface of the resin film, TiO2 and SiO2 were deposited by vapor deposition in the composition shown in Table 4 below to form a dielectric multilayer film 2. In this way, an optical filter having a structure of dielectric multilayer film 1 (Table 3) / fluorophosphate glass A1 / resin film 1 / dielectric multilayer film 2 (Table 4) was produced.

[0105] <Examples 2 to 12: Optical filters> Optical filters were produced in the same manner as in Example 1, except that the glass, resin film, dielectric multilayer film 1, and dielectric multilayer film 2 were changed to the compositions shown below. The compositions of each dielectric multilayer film are shown in Tables 3 to 6. Example 2: Dielectric multilayer 1 (Table 3) / Fluorophosphate glass A2 / Resin film 1 / Dielectric multilayer 2 (Table 4) Example 3: Dielectric multilayer 1 (Table 3) / Fluorophosphate glass B / Resin film 1 / Dielectric multilayer 2 (Table 4) Example 4: Dielectric multilayer 1 (Table 3) / Phosphate glass C / Resin film 1 / Dielectric multilayer 2 (Table 4) Example 5: Dielectric multilayer 1 (Table 5) / Fluorophosphate glass A1 / Resin film 1 / Dielectric multilayer 2 (Table 4) Example 6: Dielectric multilayer 1 (Table 3) / Fluorophosphate glass A1 / Resin film 2 / Dielectric multilayer 2 (Table 4) Example 7: Dielectric multilayer 1 (Table 3) / Fluorophosphate glass D 2 / Resin film 1 / Dielectric multilayer film 2 (Table 4) Example 8: Dielectric multilayer film 1 (Table 3) / Fluorophosphate glass D1 / Resin film 3 / Dielectric multilayer film 2 (Table 4) Example 9: Dielectric multilayer film 1 (Table 6) / Fluorophosphate glass D1 / Resin film 3 / Dielectric multilayer film 2 (Table 4) Example 10: Dielectric multilayer film 1 (Table 6) / Fluorophosphate glass D2 / Resin film 3 / Dielectric multilayer film 2 (Table 4) Example 11: Dielectric multilayer film 1 (Table 6) / Fluorophosphate glass D1 / Resin film 4 / Dielectric multilayer film 2 (Table 4) Example 12: Dielectric multilayer film 1 (Table 6) / Fluorophosphate glass D2 / Resin film 4 / Dielectric multilayer film 2 (Table 4)

[0106] For each resin film, the spectral transmittance curve was measured at an incident angle of 0 degrees in the wavelength range of 300 to 1200 nm using a UV-visible spectrophotometer. The spectral characteristics of each resin film were evaluated using the internal transmittance of the resin film formed on a transparent glass substrate to avoid the influence of reflection at the air interface and the glass interface. The results are shown in Table 2 below.

[0107] For each substrate (resin film and glass substrate), the spectral transmittance curve was measured at an incident angle of 0 degrees in the wavelength range of 300 to 1200 nm using a UV-visible spectrophotometer. The spectral characteristics of each substrate were evaluated using internal transmittance to avoid the influence of reflection at the air interface and glass interface. The results are shown in Table 6 below.

[0108] For each optical filter, a spectral transmittance curve was measured at incident angles of 0 degrees and 60 degrees, and a spectral reflectance curve at an incident angle of 5 degrees in the wavelength range of 300 to 1200 nm using an ultraviolet-visible spectrophotometer. The results are shown in Tables 7 and 8 below.

[0109] The spectral transmittance curve of the optical filter of Example 1 is shown in Fig. 2, the spectral reflectance curve of the incident direction on the dielectric multilayer film 1 side is shown in Fig. 3, and the spectral reflectance curve of the incident direction on the dielectric multilayer film 2 side is shown in Fig. 4. The spectral transmittance curve of the optical filter of Example 2 is shown in Fig. 5, and the spectral reflectance curve of the incident direction on the dielectric multilayer film 1 side is shown in Fig. 6. The spectral transmittance curves of the optical filters of Examples 3 to 6 are shown in Figs. 7 to 10, respectively. Examples 1 to 12 are working examples, and Examples 3 and 5 are comparative examples.

[0110] [Table 2]

[0111] [Table 3]

[0112] [Table 4]

[0113] [Table 5]

[0114] [Table 6]

[0115] [Table 7]

[0116] [Table 8]

[0117] From the above results, the optical filters of Examples 1, 2, 4, and 6 to 12 have an average transmittance T 440-600(0deg)AVE and average transmittance T 440-600(60deg)AVE The absolute value of the difference between the two is 15% or less, and the change in visible light transmittance is small even at a high incident angle of 60 degrees. 440-600(0deg)AVE The wavelength IR_T at which the transmittance is 50% at an incident angle of 0 degrees is 75% or more, maintaining high visible light transmittance. 50(0deg) The transmittance is in the range of 580 to 640 nm, blocking the near-infrared light region and efficiently capturing visible light. 700-800(0deg)AVE is 1.1% or less and the average transmittance T 800-1200(0deg)AVE is 5% or less, and has excellent near-infrared light blocking properties over a wide range. On the other hand, the optical filter in Example 3 has an average transmittance of T 800-1200(0deg)AVE The near-infrared blocking effect is low because the glass substrate does not absorb enough light. The optical filter in Example 5 has an average transmittance of T 440-600(0deg)AVE and average transmittance T 440-600(60deg)AVE The absolute value of the difference between the values ​​exceeds 15%, and the change in visible light transmittance is large at high incident angles. This is because the reflectance of the dielectric multilayer film 1 in the near-infrared region is too high.

[0118] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2022-210260) filed on December 27, 2022, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0119] The optical filter of this embodiment has excellent weather resistance, exhibits little change in spectral characteristics even at high angles of incidence, is excellent in transmittance in the visible light region, and has excellent near-infrared blocking properties, particularly in a wide range including 1200 nm. This makes the filter useful for imaging devices, such as cameras and sensors for transport aircraft, which have become increasingly sophisticated in recent years. [Explanation of symbols]

[0120] 1B...Optical filter 10...Near-infrared absorbing glass 21, 22...Dielectric multilayer film 30...Resin film 40...Base material

Claims

1. An optical filter comprising a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2 in this order, the resin film contains a near-infrared absorbing dye and a resin, the near-infrared absorbing glass is a fluorophosphate glass containing P, Cu, and F; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-5) to (i-7). (i-1) Average transmittance T at a wavelength of 440 to 600 nm and an incident angle of 0 degrees ４４０－６００（０ｄｅｇ）ＡＶＥ and the average transmittance T at a wavelength of 440 to 600 nm and an incident angle of 60 degrees. ４４０－６００（６０ｄｅｇ）ＡＶＥ The absolute value of the difference is 15% or less (i-2) The average transmittance T is previously recorded. ４４０－６００（０ｄｅｇ）ＡＶＥ が75% and above (i-3) Wavelength IR_T at which the transmittance is 50% at an incident angle of 0 degrees ５０（０ｄｅｇ） is in the wavelength range of 580 to 640 nm (i-5) Average transmittance T at wavelengths of 800 to 1200 nm and an incident angle of 0 degrees ８００－１２００（０ｄｅｇ）ＡＶＥ is less than 5% (i-6) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees ４４０－６５０（５ｄｅｇ）ＡＶＥ is 1.5% or less (i-7) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 to 1200 nm and an incident angle of 5 degrees ８５０－１２００（５ｄｅｇ）ＡＶＥ More than 60%

2. 2. The optical filter according to claim 1, wherein the optical filter satisfies the following spectral characteristic (i-4): (i-4) Average transmittance T at a wavelength of 700 to 800 nm and an incident angle of 0 degrees ７００－８００（０ｄｅｇ）ＡＶＥ is 1.1% or less

3. 2. The optical filter according to claim 1, wherein the optical filter satisfies the following spectral characteristic (i-8): (i-8) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees ４４０－６５０（６０ｄｅｇ）ＡＶＥ is less than 10%

4. 2. The optical filter according to claim 1, wherein the optical filter satisfies all of the following spectral characteristics (i-9) to (i-10): (i-9) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 5 degrees ４４０－６５０（５ｄｅｇ）ＡＶＥ is less than 2.0% (i-10) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 5 degrees ７００－８５０（５ｄｅｇ）ＡＶＥ is 1.2% or less

5. 2. The optical filter according to claim 1, wherein the optical filter satisfies all of the following spectral characteristics (i-11) to (i-12): (i-11) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 to 650 nm and an incident angle of 60 degrees ４４０－６５０（６０ｄｅｇ）ＡＶＥ is less than 10% (i-12) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 to 850 nm and an incident angle of 60 degrees ７００－８５０（６０ｄｅｇ）ＡＶＥ is less than 8%

6. 2. The optical filter according to claim 1, wherein the optical filter satisfies all of the following spectral characteristics (i-14) to (i-15): When the dielectric multilayer film 1 side is the incident direction, the amount of absorption loss at wavelengths X to Y nm Ｘ－Ｙ is defined below. (Absorption loss Ｘ－Ｙ ) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees) (i-14) Absorption loss at wavelengths of 700 to 800 nm ７００－８００ The average value of (i-15) Absorption loss at wavelengths of 850 to 1000 nm ８５０－１０００ The average value of 17% or more

7. the near-infrared absorbing glass has a thickness of 0.4 mm or less, 2. The optical filter according to claim 1, wherein the near-infrared absorbing glass satisfies all of the following spectral characteristics (ii-1) to (ii-3): (ii-1) Wavelength IR_T at which the transmittance is 50% at an incident angle of 0 degrees ５０（０ｄｅｇ） is in the wavelength range of 590 to 640 nm (ii-2) Transmittance T at a wavelength of 700 nm and an incident angle of 0 degrees ７００（０ｄｅｇ） (ii-3) Average transmittance T at a wavelength of 700 to 800 nm and an incident angle of 0 degrees ７００－８００（０ｄｅｇ）ＡＶＥ is less than 10%

8. 2. The optical filter according to claim 1, wherein the substrate satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) Average internal transmittance T at a wavelength of 440 to 600 nm and an incident angle of 0 degrees （ｉｎ）４４０－６００（０ｄｅｇ）ＡＶＥ More than 75% (iii-2) Average internal transmittance T at a wavelength of 700 to 800 nm and an incident angle of 0 degrees （ｉｎ）７００－８００（０ｄｅｇ）ＡＶＥ is 1.2% or less (iii-3) Average internal transmittance T at a wavelength of 800 to 1000 nm and an incident angle of 0 degrees （ｉｎ）８００－１０００（０ｄｅｇ）ＡＶＥ is less than 5%

9. 2. The optical filter according to claim 1, wherein the near-infrared absorbing dye comprises a squarylium dye having a maximum absorption wavelength in the resin at 740 to 800 nm.

10. 2. The optical filter according to claim 1, wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-4): (iv-1) Average internal transmittance T at a wavelength of 440 to 600 nm and an incident angle of 0 degrees （ｉｎ）４４０－６００（０ｄｅｇ）ＡＶＥ More than 90% (iv-2) Wavelength IR_T at which the internal transmittance is 50% at an incident angle of 0 degrees （ｉｎ）５０（０ｄｅｇ） is in the wavelength range of 630 to 645 nm (iv-3) Wavelength IR_T at which the internal transmittance is 70% at an incident angle of 0 degrees in the wavelength range of 500 to 700 nm （ｉｎ）７０（０ｄｅｇ） and the wavelength IR_T at which the transmittance is 20% at an incident angle of 0 degrees. （ｉｎ）２０（０ｄｅｇ） The absolute value of the difference is 60 nm or less (iv-4) Average internal transmittance T at a wavelength of 700 to 800 nm and an incident angle of 0 degrees （ｉｎ）７００－８００（０ｄｅｇ）ＡＶＥ is less than 5%

11. The near-infrared absorbing glass is In mass %, P ５＋ :30~70% Al ３＋ :0~20% Li ＋ :0~20% No ＋ :0~25% K ＋ :0~25% Mg ２＋ :0~10% Ca ２＋ :0~20% Sr ２＋ :0~30% No ２＋ :0~40% ΣR ＋ :0.1~30%(R ＋ Li ＋ , Na ＋ , and K ＋ one or more ingredients selected from ΣR ２＋ : 10 to 45% (R ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ one or more components selected from Cổ ２＋ :1~20% and the F contained in the glass － When the component elements other than F are taken as 100 mass%, － 2. The optical filter according to claim 1, wherein the optical filter is a fluorophosphate glass containing, in an outer ratio, 5 to 70 mass % of:

12. An imaging device comprising the optical filter according to any one of claims 1 to 11.

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