Optical filter and imaging device

Abstract

Provided are: an optical filter which, while having suppressed thickness, has excellent transmissivity with respect to the visible light region and shielding properties with respect to the near-infrared region, and has a small change in spectral characteristics even at a high angle of incidence; and an imaging device provided with the optical filter.　The optical filter comprises a glass substrate, wherein the thickness of the glass substrate is not more than 300 μm, and prescribed spectral characteristics (1-1) to (1-3) and (2-1) are satisfied.

Description

Optical filter and imaging device

[0001] This disclosure relates to optical filters and imaging devices.

[0002] In imaging devices using solid-state image sensors, optical filters are used that transmit visible light (hereinafter also referred to as "visible light") and block infrared light (hereinafter also referred to as "infrared light") in order to reproduce colors well and obtain sharp images.

[0003] Examples of such optical filters include reflective filters that alternately layer dielectric thin films with different refractive indices on one or both sides of a transparent substrate (dielectric multilayer film) and reflect light to be blocked by utilizing light interference; absorbing 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 absorbing types.

[0004] Patent Document 1 discloses an optical filter having a specific phosphate glass, which is an optical filter that has excellent transmittance of visible light, excellent shielding of near-infrared rays, and exhibits little change in spectral characteristics even at high incidence angles.

[0005] International Publication No. 2024 / 048513

[0006] Infrared cut filters reflect infrared and visible light, which can cause flare and ghosting in captured images. Furthermore, attempting to suppress infrared reflection by increasing infrared absorption has drawbacks, such as reducing the visible light transmittance of the glass or increasing the filter's thickness.

[0007] In view of the above issues, this disclosure aims to provide an optical filter that exhibits excellent transmittance in the visible light region and shielding in the near-infrared region while reducing the thickness of the optical filter, and that shows little change in spectral characteristics even at high incidence angles, as well as an imaging device equipped with said optical filter.

[0008] This disclosure provides an optical filter having the following configuration: [1] An optical filter having a glass substrate, wherein the thickness of the glass substrate is 300 μm or less, and satisfies the following spectral characteristics (1-1) to (1-3) when light is irradiated from the first main surface side, and satisfies the following spectral characteristic (2-1) when light is irradiated from the second main surface side: (1-1) Minimum transmittance of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees is 70% or more, (1-2) Average transmittance of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees is 0.5% or less, (1-3) In the range of wavelengths of 550 to 800 nm, the wavelength of light at which the transmittance at an incident angle of 0 degrees is 590 nm or more, (2-1) Average reflectance of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 30% or less.

[0009] This disclosure provides an optical filter that exhibits excellent transmittance in the visible light region and shielding in the near-infrared region while reducing the thickness of the optical filter, and that shows little change in spectral characteristics even at high incidence angles, as well as an imaging device equipped with the optical filter.

[0010] This is a schematic cross-sectional view showing an example of an optical filter. This is a schematic cross-sectional view showing another example of an optical filter. This is a figure showing the spectral transmittance curve of an optical filter. This is a figure showing the spectral transmittance curve of an optical filter. This is a figure showing the spectral reflectance curve of an optical filter. This is a figure showing the spectral reflectance curve of an optical filter. This is a figure showing the spectral reflectance curve of an optical filter.

[0011] The embodiments for carrying out the invention will be described below with reference to the drawings. In each embodiment, identical components are denoted by the same reference numerals, and their descriptions are omitted or simplified. For clarity, the following descriptions and drawings are simplified as appropriate, and the scale of each component may differ significantly. Also for clarity, one direction of the main surface of the object may be defined as the X-axis, one direction of the main surface of the object perpendicular to the X-axis as the Y-axis, and the normal direction of the main surface of the object as the Z-axis. Note that the XY plane may be a curved surface. In this disclosure, near-infrared absorbing dyes may be referred to as "NIR dyes," and ultraviolet absorbing dyes as "UV dyes." A compound represented by formula (I) may be referred to as compound (I). The same applies to compounds represented by other formulas. In this disclosure, "film," "layer," and "substrate" differ only in name and do not distinguish in thickness or physical properties. Unless otherwise specified, the numerical range indicated by "~" includes the values ​​described before and after it as the lower and upper limits.

[0012] 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% across the entire wavelength range, i.e., 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% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. Spectral characteristics can be measured using an ultraviolet-visible spectrophotometer.

[0013] [Optical Filter] The optical filter according to this embodiment is an optical filter having a glass substrate with a thickness of 300 μm or less, which satisfies the following spectral characteristics (1-1) to (1-3) when light is irradiated from the first main surface side, and satisfies the following spectral characteristic (2-1) when light is irradiated from the second main surface side. (1-1) Minimum transmittance T of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees ４５０－５５０（０ｄｅｇ）ＭＩＮ (1-2) The average transmittance of light with a wavelength of 800-1200 nm and an incident angle of 0 degrees is 70% or more. ８００－１２００（０ｄｅｇ）ＡＶＥ (1-3) Wavelength IR at which the transmittance at an incident angle of 0 degrees is 50% or less, (1-3) Wavelength IR at which the transmittance at an incident angle of 0 degrees is 50% in the range of wavelength 550 to 800 nm ５０（０ｄｅｇ）(2-1) The average reflectance R2800-1200 (5deg) AVE of light with a wavelength of 800-1200 nm and an incident angle of 5 degrees is 30% or less.

[0014] The optical filter of this embodiment, satisfying spectral characteristics (1-1) to (1-3) and spectral characteristic (2-1), has high transmittance of visible light as shown in characteristic (1-1) and high shielding of near-infrared light as shown in characteristic (1-2). Furthermore, it has high transmittance up to the long wavelength region of visible light as shown in characteristic (1-3), and furthermore, the reflection of near-infrared light is suppressed as shown in characteristic (2-1). The optical filter of this embodiment achieves these characteristics using a glass substrate with a thickness of 300 μm or less.

[0015] When the optical filter according to this embodiment is mounted on an imaging device or the like, it is preferable that the "first main surface" is positioned on the light source side and the "second main surface" is positioned on the sensor side, but the arrangement is not limited to this. An optical filter having the above characteristics can be realized if, when light is irradiated from at least one main surface side of the optical filter, characteristics (1-1) to (1-3) are satisfied, and when light is irradiated from the other main surface side, spectral characteristics (2-1) are satisfied.

[0016] Satisfying spectral characteristics (1-1) means excellent transmittance in the visible light region with wavelengths of 450-550 nm. ４５０－５５０（０ｄｅｇ）ＭＩＮ The spectral characteristics (1-1) can be achieved, for example, by using an anti-reflective layer with low reflectivity in the visible light region, a resin film containing a near-infrared absorbing dye with high transmittance in the visible light region, or a specific near-infrared absorbing glass.

[0017] Satisfying the spectral characteristics (1-2) indicates excellent light-shielding properties in the near-infrared region with wavelengths of 800-1200 nm. ８００－１２００（０ｄｅｇ）ＡＶＥThe amount is preferably 0.4% or less, more preferably 0.3% or less, even more preferably 0.25% or less, and particularly preferably 0.2% or less. The spectral characteristics (1-2) can be achieved, for example, by using a resin film containing a near-infrared absorbing dye, using a specific near-infrared absorbing glass, or using a near-infrared reflective multilayer film.

[0018] Satisfying spectral characteristics (2-1) indicates that the reflectance in the near-infrared region with wavelengths of 800 to 1200 nm is low in the second principal surface. R2800-1200 (5 deg) AVE is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, and particularly preferably 5% or less. Spectral characteristics (2-1) can be achieved, for example, by using an anti-reflective layer with low reflectivity or by using a specific near-infrared absorbing glass.

[0019] Meeting the spectral characteristics (1-3) indicates high transmittance up to the long wavelength region of visible light. IR ５０（０ｄｅｇ） The wavelength is preferably 595 nm or more, more preferably 600 nm or more, and even more preferably 605 nm or more. The spectral characteristics (1-3) can be achieved, for example, by using an anti-reflective layer with low reflectivity in the visible light region, a resin film containing a near-infrared absorbing dye with high transmittance in the visible light region, or a specific near-infrared absorbing glass.

[0020] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-4). (1-4) When light is irradiated from the first main surface side, the average reflectance R1800-1200(5deg)AVE of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 70% or less. Satisfying spectral characteristics (1-4) indicates that the reflectance in the near-infrared region with a wavelength of 800 to 1200 nm is small on the first main surface. R1800-1200(5deg)AVE is preferably 60% or less, more preferably 30% or less, even more preferably 20% or less, particularly preferably 15% or less, even more preferably 10% or less, and extremely preferably 5% or less.

[0021] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-5). (1-5) When light is irradiated from the first main surface side, the transmittance T of light with a wavelength of 450 nm and an incident angle of 0 degrees ４５０（０ｄｅｇ） is 70% or more. Satisfying the above spectral characteristics (1-5) means that the transmittance of visible light with a wavelength of 450 nm is more excellent. T ４５０（０ｄｅｇ） is preferably 80% or more, more preferably 90% or more, still more preferably 92% or more, particularly preferably 94% or more, and extremely preferably 95% or more. The spectral characteristics (1-5) can be achieved, for example, by using an antireflection layer with a low reflectance in the visible light region, using a resin film containing a near-infrared absorbing dye with a high transmittance in the visible light region, using a specific near-infrared absorbing glass, and the like.

[0022] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-6). (1-6) When light is irradiated from the first main surface side, the average transmittance T of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees ８００－１２００（０ｄｅｇ）ＡＶＥ is 0.2% or less. Satisfying the spectral characteristics (1-6) indicates that the light shielding property in the near-infrared region with a wavelength of 800 to 1200 nm is further excellent. The spectral characteristics (1-6) can be achieved, for example, by using a resin film containing a near-infrared absorbing dye, using a specific near-infrared absorbing glass, and the like.

[0023] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (2-2), and more preferably further satisfies the following spectral characteristics (2-3). (2-2) When light is irradiated from the second main surface side, the average reflectance R2400-600(60deg)AVE of light with a wavelength of 400 to 600 nm and an incident angle of 60 degrees is 10% or less. (2-3) The above R2400-600(60deg)AVE is 5% or less. Satisfying spectral characteristics (2-2) or (2-3) means that the change in spectral characteristics with respect to the incident angle is small in the visible light region with a wavelength of 450 to 550 nm. R2400-600(60deg)AVE is preferably 9% or less, more preferably 5% or less, and even more preferably 3% or less. The spectral characteristics (2-2) and (2-3) can be achieved, for example, by using an anti-reflective layer with low reflectivity in the visible light region or by using a specific near-infrared absorbing glass.

[0024] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-7): (1-7) When light is irradiated from the first main surface side, the maximum transmittance T in the wavelength range of 450 to 500 nm is shown in the spectral transmittance curve at an incident angle of 0 degrees. ｍａｘ And, minimum transmittance T ｍｉｎ The ratio (T ｍｉｎ / T ｍａｘ The value is 0.920 or higher. Satisfying the spectral characteristics (1-7) indicates that the change in transmittance is small in the visible light region at wavelengths of 450-500 nm, and that the change in color is suppressed. ｍｉｎ / T ｍａｘ The coefficient of gravity is preferably 0.940 or higher, more preferably 0.960 or higher, and even more preferably 0.980 or higher. The spectral characteristics (1-7) can be achieved, for example, by using an anti-reflective layer with low reflectivity in the visible light region, a resin film containing a near-infrared absorbing dye with high transmittance in the visible light region, or a specific near-infrared absorbing glass.

[0025] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-8). (1-8) When light is irradiated from the first main surface side, the wavelength of light IR in the range of 550 to 800 nm at an incident angle of 0 degrees has a transmittance of 20%. ２０（０ｄｅｇ） and wavelength IR which is 50% ５０（０ｄｅｇ） The difference (IR ２０（０ｄｅｇ） -IR ５０（０ｄｅｇ） ) is 45 nm or less. Meeting the spectral characteristics (1-8) indicates that the change in transmittance is steep in the wavelength range of 550-800 nm, demonstrating that it is an optical filter that balances transmittance on the longer wavelength side of visible light with shielding of near-infrared light. IR ２０（０ｄｅｇ） -IR ５０（０ｄｅｇ） The wavelength is preferably 43 nm or less, and more preferably 40 nm or less. The spectral characteristics (1-8) can be achieved, for example, by using a resin film containing a near-infrared absorbing dye with high transmittance in the visible light region, or by using a specific near-infrared absorbing glass. IR ２０（０ｄｅｇ） -IR ５０（０ｄｅｇ） The lower limit is not particularly limited, but for example, it may be 1 nm or more, or 30 nm or more.

[0026] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (1-9): (1-9) Maximum transmittance T of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees when light is irradiated from the first main surface side. ４５０－５５０（０ｄｅｇ）ＭＡＸ This is over 90%. Satisfying the spectral characteristics (1-9) means excellent transmittance in the visible light region at wavelengths of 450-550 nm. ４５０－５５０（０ｄｅｇ）ＭＡＸ The reflectivity is preferably 92% or more, more preferably 94% or more, and even more preferably 85% or more. The spectral characteristics (1-9) can be achieved, for example, by using a dielectric multilayer film with low reflectivity in the visible light region, a resin film containing a near-infrared absorbing dye with high transmittance in the visible light region, or a near-infrared absorbing glass.

[0027] <Configuration of the Optical Filter> Next, the configuration of the optical filter will be described. The optical filter according to this embodiment only needs to have a glass substrate with a thickness of at least 300 μm, and various optical functional layers may be independently arranged on the first main surface side and / or the second main surface side of the glass substrate. Figures 1 and 2 are schematic cross-sectional views showing an example of the layer configuration of an optical filter. The optical filter 10a shown in the example of Figure 1 comprises a glass substrate 1, an anti-reflective layer 2 arranged on the first main surface 1a side of the glass substrate 1, and an anti-reflective layer 3 arranged on the second main surface 1b side of the glass substrate 1. The optical filter 10b shown in the example of Figure 2 comprises a resin film 4 and an anti-reflective layer 2 sequentially arranged on the first main surface 1a side of the glass substrate 1, and an anti-reflective layer 3 on the second main surface 1b side. The optical filter according to this embodiment satisfies the above spectral characteristics by a combination of the glass substrate and the optical functional layers. The following describes each layer that can be used in this optical filter.

[0028] (Glass Substrate) The optical filter of this embodiment uses a glass substrate with a thickness of 300 μm or less. This makes it possible to achieve an optical filter that is thin while having excellent transmittance in the visible light region and shielding in the near-infrared region, and that shows little change in spectral characteristics even at high incidence angles. The thickness of the glass substrate is preferably 250 μm or less. The lower limit of the thickness of the glass substrate is not particularly limited, but from the standpoint of easily satisfying the above optical characteristics and the mechanical strength of the optical film, it is preferably 50 μm or more, more preferably 80 μm or more, and even more preferably 100 μm or more.

[0029] The material for the glass substrate is preferably phosphate glass, as it provides both visible light transmittance and infrared absorption. The components constituting phosphate glass are described below. Note that the content percentages of each glass component listed below are expressed in mass % in terms of oxide. Phosphoric acid (P ２ O ５ ) is the main component that forms glass. P is used because it enhances the absorption of near-infrared rays. ２ O ５ The content is preferably 20% or more, and more preferably 30% or more. Also, from the viewpoint of improving the chemical durability of the glass, P ２ O ５The content of is preferably 80% or less. Furthermore, from the viewpoint of increasing near-infrared absorption, it is preferable that the phosphate glass contains CuO. The CuO content is preferably 10% or more, and more preferably 15% or more. If there is too much CuO, the absorption of visible light will increase, so it is preferably 40% or less, and more preferably 30% or less. Here, the CuO content refers to the content where all copper ions are Cu ２＋ This refers to the CuO content assuming it exists in that state.

[0030] Among the glass substrates, those that easily achieve the above optical properties are preferably glass containing the following components in terms of cation percentage and having an atomic ratio of O to P (O / P) of 2.7 to 3.4. P: 55-75%, Al: 0-20%, Cu: 10-30%, Li: 0-15%, Na: 0-15%, K: 0-15%, Cs: 0-15%, Mg: 0-10%, Ca: 0-10%, Sr: 0-10%, Ba: 0-10%, Zn: 0-10%, ΣR': 0-30%, ΣR'': 0-10%, ΣM: 0-10%. However, ΣR' represents the total amount of Li, Na, K, and Cs, ΣR'' represents the total amount of Mg, Ca, Sr, Ba, and Zn, and ΣM represents the total amount of Y, Yb, In, La, Ce, B, Si, Ti, Zr, Ge, Nb, Ta, W, and Mo.

[0031] Glass having the above composition achieves both excellent infrared-cutting performance and visible light transmission, and also exhibits excellent weather resistance.

[0032] The above glass preferably contains 55-75% P. P is mainly P ５＋ It is contained as P. ５＋ P is the main component of phosphate glass and an essential component for enhancing near-infrared ray blocking properties. ５＋If the content of P is 55% or more, the effect can be obtained sufficiently, and if it is 75% or less, problems such as glass instability or reduced weather resistance are less likely to occur. The content of P is preferably 56% or more, more preferably 57% or more, and even more preferably 58% or more. Furthermore, the content of P is preferably 74% or less, more preferably 73% or less, even more preferably 72% or less, and particularly preferably 71% or less. ５＋ From the viewpoint of suppressing crucible erosion and inhibiting the volatilization of components, phosphoric acid, liquid phosphoric acid, or a salt thereof are preferred as raw materials.

[0033] The above glass may contain 0-20% Al. Al is mainly Al ３＋ It is contained as Al ３＋ Al is a component that forms glass and improves the strength and weather resistance of the glass. From the viewpoint of vitrification stability and infrared cut properties, the Al content is 20% or less. The Al content may be 0% or more, and from the viewpoint of glass strength and weather resistance, it is more preferably 0.50% or more, 1.00% or more, 1.50% or more, 2.00% or more, 2.50% or more, 3.00% or more, 3.50% or more, 4.00% or more, 4.50% or more, and particularly preferably 5% or more. Furthermore, from the viewpoint of vitrification stability and infrared cut properties, the Al content is preferably 18% or less, more preferably 17.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, and particularly preferably 10% or less. ３＋ As a raw material, AlF ３ Al ２ O ３ Al(OH) ３ Al(PO ３ ) ３ The following can be used.

[0034] The above glass preferably contains 10-30% Cu. Cu is mainly Cu ＋ or Cu ２＋It is contained in a concentration of 10-30%. A Cu content of 10% or more provides excellent infrared blocking performance. Furthermore, a Cu content of 30% or less provides excellent visible light transmittance. The Cu content is preferably 11% or more, more preferably 12% or more, even more preferably 13% or more, and particularly preferably 14% or more. On the other hand, the Cu content is preferably 29% or less, more preferably 28% or less, even more preferably 27% or less, and particularly preferably 26% or less. Also, from the viewpoint of visible light transmittance and infrared blocking performance, monovalent copper ions Cu relative to total Cu ＋ Percentage (Cu ＋ (Total Cu amount) × 100 [%] is preferably 0.01 to 4.0%. ２＋ or Cu ＋ As raw materials, CuO, Cu ２ SO ４ CuNO ３ Cu(PO ３ ) ２ The following can be used.

[0035] The above glass may contain 0-15% Li. Li is mainly Li ＋ It is contained as Li ＋ These are components that lower the melting temperature of the glass, lower the liquidus temperature of the glass, and stabilize the vitrification process. From the viewpoint of vitrification stability and infrared cut performance, the Li content is preferably 14% or less, more preferably 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, 0.1% or less, and particularly preferably no Li content.

[0036] The above glass may contain 0-15% Na. Na is mainly Na ＋ It is contained as Na. ＋This component is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, and stabilize the vitrification process. From the viewpoint of vitrification stability and infrared-cutting performance, the Na content is preferably 14% or less, more preferably 13% or less, even more preferably 12% or less, and particularly preferably 10% or less.

[0037] The above glass may contain 0-15% K. K is mainly K ＋ It is contained as K. ＋ This component has effects such as lowering the melting temperature of the glass and lowering the liquidus temperature of the glass. The content of K is preferably 14% or less, more preferably 13% or less, even more preferably 12% or less, and particularly preferably 10% or less.

[0038] The above glass may contain 0-15% Cs. Cs is mainly Cs ＋ It is contained as Cs. ＋ This component has effects such as lowering the melting temperature of the glass and lowering the liquidus temperature of the glass. The Cs content is preferably 14% or less, more preferably 13% or less, even more preferably 12% or less, particularly preferably 10% or less, even more preferably 10% or less, particularly preferably 7% or less, and most preferably 3% or less.

[0039] In the above glass, the total amount of Li, Na, K, and Cs (ΣR') is preferably 0 to 30%. From the viewpoint of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, and stabilizing vitrification, ΣR' is preferably 0.1% or more, more preferably 1% or more, even more preferably 3% or more, particularly preferably 5% or more, and most preferably 8% or more. On the other hand, from the viewpoint of vitrification stability, ΣR' is 30% or less, preferably 20% or less, more preferably 25% or less, and even more preferably 10% or less. As raw materials for R', carbonates, nitrates, hydroxides, metaphosphates, orthophosphates, etc., can be used.

[0040] The above glass may contain 0-10% Mg. Mg is mainly Mg ２＋It is contained as Mg ２＋ This component is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, stabilize the vitrification process, and increase the strength of the glass. From the viewpoint of vitrification stability and infrared-cutting performance, the Mg content is preferably 8% or less, more preferably 6% or less, even more preferably 5% or less, and particularly preferably 3% or less.

[0041] The above glass may contain 0-10% Ca. Ca is mainly Ca ２＋ It is contained as Ca ２＋ This component is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, stabilize vitrification, and increase the strength of the glass. From the viewpoint of vitrification stability and infrared cut performance, the Ca content is preferably 9% or less, more preferably 8% or less, even more preferably 7% or less, and particularly preferably 6% or less.

[0042] The above glass may contain 0-10% Sr. Sr is mainly Sr ２＋ It is contained as Sr ２＋ This component is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, and stabilize the vitrification process. From the viewpoint of vitrification stability and infrared cut performance, the Sr content is preferably 9% or less, more preferably 8% or less, even more preferably 7% or less, and particularly preferably 6% or less.

[0043] The above glass may contain 0-10% Ba. Ba is mainly Ba ２＋ It is contained as Ba ２＋ This component is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, and stabilize the vitrification process. From the viewpoint of vitrification stability and infrared-cutting performance, the Ba content is preferably 9% or less, more preferably 8% or less, even more preferably 7% or less, and particularly preferably 6% or less.

[0044] Furthermore, the above glass may contain Zn. Zn is mainly Zn ２＋ It is contained as Zn. ２＋This has effects such as lowering the melting temperature of the glass and lowering the liquidus temperature of the glass. From the viewpoint of vitrification stability and infrared cut performance, the Zn content is preferably 0 to 10%, more preferably 8% or less, even more preferably 7% or less, and particularly preferably 6% or less.

[0045] In the above glass, the total amount of Mg, Ca, Sr, Ba, and Zn (ΣR'') is preferably 0 to 10%. From the viewpoint of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, and stabilizing vitrification, ΣR'' is preferably 0.1% or more, more preferably 0.5% or more, and even more preferably 1% or more. On the other hand, from the viewpoint of vitrification stability, ΣR'' is 10% or less, preferably 9% or less, and more preferably 8% or less. As raw materials for R'', carbonates, nitrates, hydroxides, metaphosphates, orthophosphates, fluorides, etc., can be used.

[0046] The above glass may contain one or more elements selected from Y, Yb, In, La, Ce, B, Si, Ti, Zr, Ge, Nb, Ta, W, and Mo in a total amount (ΣM) of 0 to 10%. The inclusion of these elements improves the weather resistance of the glass. From the viewpoint of weather resistance, ΣM is preferably 0.2% or more, more preferably 0.5% or more, and even more preferably 1% or more. Furthermore, the above glass preferably contains Nb. The cation percentage ratio of Nb to ΣM (Nb / ΣM) is preferably 0.5 to 1.0, and more preferably 0.6 to 1.0. As raw materials for M, oxides, carbonates, nitrates, fluorides, phosphates, etc., can be used.

[0047] In order to improve infrared-cutting performance, the atomic ratio of O to P (O / P) of the above glass is preferably 2.7 to 3.4, more preferably 2.7 to 3.3, and even more preferably 2.7 to 3.2.

[0048] The above glass may contain F. F is mainly F －It is contained as follows. From the viewpoint of infrared cut performance and the mechanical strength of the glass, the content of F is preferably 1% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less, based on 100% by mass of the total amount of glass.

[0049] The glass described above may further contain other elements not mentioned above, if necessary or unavoidable. The total content of other elements is preferably 8% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, based on 100% by mass of the total amount of glass.

[0050] (Anti-reflective layer) The anti-reflective layer is a layer that suppresses the reflection of visible light and near-infrared light, and examples include dielectric multilayer films and uneven layers having a specific uneven shape.

[0051] A dielectric multilayer film is composed of, for example, a film made by stacking dielectric films with different refractive indices. More specifically, a multilayer film can be made by stacking two or more films selected from a low refractive index dielectric film, a medium refractive index dielectric film, and a high refractive index dielectric film.

[0052] In optical filters, visible light ripple is mainly caused by interference resulting from reflected light at the interface of each layer when dielectric multilayer films are stacked as infrared reflective layers. Therefore, by stacking dielectric multilayer films as anti-reflective layers as described above, an optical filter with suppressed visible light ripple can be obtained. The anti-reflective layer may also have reflective properties in the ultraviolet region.

[0053] The high refractive index film preferably has a refractive index of 1.6 or higher at a wavelength of 500 nm, and more preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta ２ O ５ , TiO ２ ,TiO,Nb ２ O ５ Other commercially available products include the OS50 (Ti) manufactured by Canon Optron Corporation. ３ O ５ ), OS10 (Ti ４ O ７), OA500 (Ta ２ O ５ and ZrO ２ mixture), OA600 (Ta ２ O ５ and TiO ２ mixture), etc. Among these, TiO ２ is preferred from the viewpoints of reproducibility, stability, etc. in film formation properties, refractive index, etc.

[0054] 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 the material for the medium refractive index film include ZrO ２ , Nb ２ O ５ , Al ２ O ３ , HfO ２ , or OM-4, OM-6 (Al ２ O ３ and ZrO ２ mixture), OA-100, H4, M2 (aluminum lanthanum oxide) sold by Merck, etc. Among these, from the viewpoints of reproducibility, stability, etc. in film formation properties, refractive index, etc., Al ２ O ３ -based compounds and mixtures of Al ２ O ３ and ZrO ２ are preferred.

[0055] 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 the material for the low refractive index film include SiO ２ , SiO ｘ N ｙ、 MgF ２ , etc. Other commercially available products include S4F, S5F (mixture of SiO ２ and Al ２ O ３ ) manufactured by Canon Optron. Among these, SiO ２ is preferred from the viewpoints of reproducibility, stability, economy, etc. in film formation properties.

[0056] To create a dielectric multilayer film with suppressed reflection characteristics, one approach is to combine several dielectric films with different spectral characteristics when transmitting and selecting the desired wavelength band.

[0057] The total number of dielectric multilayer films may be two or more, preferably four or more, and more preferably five or more, from the viewpoint of further improving anti-reflective properties. On the other hand, the total number of first optical multilayer films may be 40 or less, more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of suppressing the thickness of the optical filter. The thickness of the dielectric multilayer film is preferably 1 μm or less, more preferably 0.9 μm or less, and preferably 0.2 μm or more. The optical filter of this embodiment may have two or more dielectric multilayer films. In this case, it is preferable that each of the two or more dielectric multilayer films independently satisfies the above-mentioned number of films and thickness.

[0058] For the formation of dielectric multilayer films, known film deposition methods can be used, such as vacuum deposition processes including CVD, sputtering, and vacuum evaporation, or wet deposition processes such as spraying and dipping.

[0059] (Uneven layer) The uneven layer is a layer that provides optical functionality by utilizing its shape, and in this embodiment, a moth-eye layer for providing anti-reflective properties is preferred.

[0060] The moth-eye layer has a fine uneven surface shape in which the cross-sectional area continuously decreases from the substrate 1 side toward the air interface, and a structure in which the refractive index continuously decreases, thereby suppressing reflection. Preferably, the moth-eye layer has an average reflectance of 2% or less when visible light with a wavelength of 400 to 600 nm is incident at an incident angle of 0°. Preferably, the fine uneven surface shape of the moth-eye layer has a microstructure in which the pitch between the protrusions is 400 nm or less, more preferably 200 nm or less. The average height of the protrusions is preferably 400 nm or less, more preferably 200 to 350 nm.

[0061] The above-mentioned uneven layer may be formed using, for example, a commercially available moth-eye film, or it may be formed on a filter (optical multilayer film). As for the formation method, for example, a film containing an oxide of Al, Mg, Zn, or an alloy thereof can be formed by a known film deposition method (vacuum deposition method, sol-gel method, etc.), and the film can be treated with steam or hot water to boehmite (hydroxideize) the surface layer and form the uneven layer. The uneven layer formed by this method contains one or more selected from Al, Mg, and Zn, and usually also contains H and O. When an alumina film is formed, the resulting uneven layer contains aluminum hydroxide oxide (AlO(OH)), the effective refractive index on the air interface side is approximately 1, and the refractive index at the interface with other layers is in the range of 1.35 to 1.58.

[0062] <Resin Film> In this embodiment, the resin film is a layer that imparts optical functionality through its material and additives. The resin constituting the resin film is preferably transparent. Examples of such resins include polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin. The resin may be one type or a mixture of two or more types.

[0063] From the viewpoint of the spectral properties (transparency), glass transition temperature (Tg), and adhesion of the resin, polyimide resin, polycarbonate resin, polyester resin, or acrylic resin are preferred as the resin. The glass transition temperature (Tg) of the resin is preferably 200°C or higher from the viewpoint of heat resistance.

[0064] When imparting near-infrared absorption properties to a resin film, it is preferable to use a near-infrared absorbing dye as an additive. Examples of near-infrared absorbing dyes include dyes having a maximum absorption wavelength of 690 to 850 nm, preferably 690 to 800 nm. By using such dyes, near-infrared light around 700 nm can be blocked. Specific examples of near-infrared absorbing dyes include cyanine dyes, phthalocyanine dyes, squarylium dyes, naphthalocyanine dyes, and diimonium dyes, which can be used individually or in combination. Among these, squarylium dyes and cyanine dyes are preferred because they easily satisfy the above-mentioned spectral characteristics.

[0065] The content of the near-infrared absorbing dye is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of resin. When two or more compounds are combined, the above content is the sum of the content of each compound.

[0066] When imparting ultraviolet light absorption properties to a resin film, it is preferable to use an ultraviolet light absorbing dye as an additive. Examples of ultraviolet light absorbing dyes include dyes having a maximum absorption wavelength of 350 to 410 nm. Specific 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 compounds having a maximum absorption wavelength of 370 to 410 nm and zeromethine compounds having a maximum absorption wavelength of 350 to 380 nm are preferred. The ultraviolet light absorbing dye can be used individually or in combination of several types.

[0067] The amount of ultraviolet-absorbing dye is preferably 3 to 15 parts by mass, more preferably 5 to 14 parts by mass, per 100 parts by mass of resin. When two or more compounds are combined, the above amount is the sum of the individual compounds.

[0068] Furthermore, both near-infrared absorbing dyes and ultraviolet absorbing dyes may be added to a single resin film. In addition, various pigments, silane coupling agents to improve adhesion, surfactants, defoamers, antioxidants, etc. may be used as other additives.

[0069] A resin film can be formed by preparing a coating solution by dissolving or dispersing a resin or resin raw material component, along with dyes and other additives as needed, in a solvent; coating this solution onto a support and drying it; and further curing and / or drying it as needed. The support in this case may be a glass substrate used in this filter, or it may be a releaseable support. The solvent may be any dispersion medium or solvent that can stably disperse or dissolve the components.

[0070] Methods for applying the coating solution include immersion coating, cast coating, and spin coating. After applying the coating solution to a support, it is dried as needed to form a dry coating film. If the resin is a curable resin, a curing treatment such as thermosetting or photocuring is performed as needed. The resin film may also be manufactured in film form by extrusion molding. The obtained film-like resin film may be placed on a glass substrate and integrated by thermocompression bonding or the like.

[0071] The resin film may be present as one layer or as two or more layers within the optical filter. If there are two or more layers, each layer may have the same or different configuration. From the viewpoint of achieving the desired spectral characteristics with an appropriate dye concentration, the thickness of the resin film is preferably 0.5 μm or more. On the other hand, from the viewpoint of keeping the thickness of the optical filter down, it is preferably 10 μm or less, more preferably 5 μm or less.

[0072] <Other Optical Functional Layers> This filter may further have other optical functional layers. Other optical functional layers include layers that provide absorption by inorganic fine particles, etc., which 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 high transmittance of visible light and light absorption over a wide range in the infrared wavelength region exceeding 1200 nm, so they can be used when shielding of such infrared rays is required.

[0073] <Layer Configuration of Optical Filter> The following describes a preferred layer configuration for the optical filter of this embodiment. The notation "Layer A / Layer B / Layer C..." indicates that, in the image sensor described later, the layers are stacked in the order of Layer A, Layer B, Layer C, etc., from the side where the optical sensor is mainly located. "Substrate" refers to a glass substrate. (1) Dielectric multilayer film / Substrate / Dielectric multilayer film (2) Dielectric multilayer film / Resin film / Dielectric multilayer film / Substrate / Dielectric multilayer film (3) Uneven layer / Dielectric multilayer film / Substrate / Dielectric multilayer film / Uneven layer (4) Dielectric multilayer film / Resin film / Dielectric multilayer film / Substrate / Dielectric multilayer film / Uneven layer (5) Uneven layer / Dielectric multilayer film / Resin film / Dielectric multilayer film / Substrate / Dielectric multilayer film / Uneven layer

[0074] According to this embodiment, an optical filter can be realized that exhibits excellent transmittance in the visible light region and shielding in the near-infrared region while keeping the thickness low, and that shows little change in spectral characteristics even at high incidence angles. When the optical filter of this embodiment is used in an imaging device such as a digital still camera, for example, it can provide an imaging device with excellent color reproduction.

[0075] [Imaging device] The imaging device according to this embodiment is characterized by comprising the optical filter of this embodiment. The imaging device comprises at least a solid-state image sensor and the optical filter of this embodiment, and may further comprise an imaging lens or the like. The optical filter may be arranged, for example, in the optical path between the imaging lens and the solid-state image sensor, or it may be directly attached to the solid-state image sensor, imaging lens, etc. of the imaging device via an adhesive layer.

[0076] As described above, the Spectrum discloses the following optical filters, etc. [1] An optical filter having a glass substrate, wherein the thickness of the glass substrate is 300 μm or less, and satisfies the following spectral characteristics (1-1) to (1-3) when light is irradiated from the first main surface side, and satisfies the following spectral characteristic (2-1) when light is irradiated from the second main surface side: (1-1) Minimum transmittance of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees is 70% or more, (1-2) Average transmittance of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees is 0.5% or less, (1-3) In the range of wavelengths of 550 to 800 nm, the wavelength of light at which the transmittance at an incident angle of 0 degrees is 50% is 590 nm or more, (2-1) Average reflectance of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 30% or less. [2] The optical filter according to [1], wherein the thickness of the glass substrate is 250 μm or less. [3] An optical filter according to [1] or [2] that further satisfies the following spectral characteristics (1-4) when irradiated with light from the first main surface side. (1-4) The average reflectance of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 70% or less. [4] An optical filter according to any of [1] to [3] that further satisfies the following spectral characteristics (1-5) when irradiated with light from the first main surface side. (1-5) The transmittance of light with a wavelength of 450 nm and an incident angle of 0 degrees is 70% or more. [5] An optical filter according to any of [1] to [4] that further satisfies the following spectral characteristics (1-6) when irradiated with light from the first main surface side. (1-6) The average transmittance of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees is 0.2% or less. [6] An optical filter according to any of [1] to [5] that further satisfies the following spectral characteristics (2-2) when irradiated with light from the second main surface side. (2-2) The average reflectance of light with a wavelength of 400 to 600 nm and an incident angle of 60 degrees is 10% or less. [7] An optical filter according to any one of [1] to [6] that further satisfies the following spectral characteristics (2-3) when light is irradiated from the second main surface side. (2-3) The average reflectance of light with a wavelength of 400 to 600 nm and an incident angle of 60 degrees is 5% or less. [8] An optical filter according to any one of [1] to [7] having an uneven layer on at least one of its outermost surfaces. [9] An optical filter according to any one of [1] to [8], wherein the fluorine content of the glass substrate is 10% by mass or less.

[10] The optical filter according to any one of [1] to [9], wherein the CuO content of the glass substrate is 10% by mass or more.

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

[10] , further satisfying the following spectral characteristics (1-7) when light is irradiated from the first main surface side. (1-7) The maximum transmittance T in the wavelength range of 450 to 500 nm in the spectral transmittance curve at an incident angle of 0 degrees. ｍａｘ And, minimum transmittance T ｍｉｎ The ratio (T ｍｉｎ / T ｍａｘ ) is 0.920 or higher.

[12] An optical filter according to any one of [1] to

[11] , which further satisfies the following spectral characteristics (1-8) when light is irradiated from the first main surface side. (1-8) In the range of wavelengths from 550 to 800 nm, the difference between the wavelength of light at an incident angle of 0 degrees where the transmittance is 20% and the wavelength at which it is 50% is 45 nm or less.

[13] An optical filter according to any one of [1] to

[12] , which further satisfies the following spectral characteristics (1-9) when light is irradiated from the first main surface side. (1-9) The maximum transmittance of light at a wavelength of 450 to 550 nm and an incident angle of 0 degrees is 90% or higher.

[14] An imaging device equipped with an optical filter according to any one of [1] to

[13] .

[0077] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. Examples 1 to 3 are comparative examples, and Examples 4 to 15 are examples.

[0078] A UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, UH-4150 model) was used to measure each spectral characteristic. Unless otherwise specified, the spectral characteristics were measured at an incident angle of 0° (perpendicular to the main surface of the optical filter).

[0079] <Materials> The dyes used in each example are as follows: • Dye (1): Squallium-based dye (with absorption maximum at a wavelength of 722 nm) • Dye (2): Squallium-based dye (with absorption maximum at a wavelength of 752 nm) • Dye (3): Merocyanine-based dye (with absorption maximum at a wavelength of 400 nm)

[0080]

[0081] The glass substrates used in each example are as follows: • Glass substrate (1): Fluorin dioxide glass (thickness 800 μm, fluorine content over 10%) • Glass substrate (2): Fluorin dioxide glass (thickness 300 μm, fluorine content over 10%) • Glass substrate (3): Phosphate glass (thickness 300 μm, CuO content less than 10%, fluorine content less than 10%) • Glass substrate (4): Phosphate glass (thickness 170 μm, CuO content 10% or more, fluorine content less than 10%) • Glass substrate (5): Phosphate glass (thickness 250 μm, CuO content 10% or more, fluorine content less than 10%) • Glass substrate (6): Phosphate glass (thickness 135 μm, CuO content 10% or more, fluorine content less than 10%) • Glass substrate (7): Phosphate glass (thickness 160 μm, CuO content 10% or more, fluorine content less than 10%) - Glass substrate (8): Phosphate glass (thickness 185 μm, CuO content 10% or more, fluorine content less than 10%) - Glass substrate (9): Phosphate glass (thickness 220 μm, CuO content 10% or more, fluorine content less than 10%) - Glass substrate (10): Phosphate glass (thickness 145 μm, CuO content 10% or more, fluorine content less than 10%) The above glass substrates (4) to (10) all have the composition shown in Table 1 below. In Table 1, the numerical values ​​for the elements that become cationized are the percentage values ​​of the cations. O and F are values ​​that are shown as an external division of the content contained in the glass when the total amount of cations is taken as 100%. Each of the above glass substrates was obtained by melting the glass raw materials in a crucible, shaping them to produce a glass block, grinding them to a predetermined thickness, and performing mirror polishing.

[0082]

[0083] The uneven layer was created by applying a hot water treatment to an aluminum oxide film formed by vacuum deposition. This uneven layer has a fine uneven shape with a pitch of 400 nm or less between the protrusions and an average height of 200 to 350 nm between the protrusions.

[0084] <Preparation of coating solution for resin film> A polyimide resin ("C3G30G" (product name), refractive index 1.59) manufactured by Mitsubishi Gas Chemical Company, Inc. was dissolved in γ-butyrolactone (GBL):cyclohexanone = 1:1 (mass ratio) to prepare a polyimide resin solution with a resin concentration of 8.5% by mass. (Preparation of coating solution 1) To the above polyimide resin solution, the above dye (3) was added at a concentration of 4.9 parts by mass per 100 parts by mass of resin, and the mixture was stirred at 50°C for 2 hours to obtain coating solution 1. (Preparation of coating solution 2) To the above polyimide resin solution, the above dyes (1), (2), and (3) were added at concentrations of 1.5 parts by mass, 4.7 parts by mass, and 4.9 parts by mass, respectively, per 100 parts by mass of resin, and the mixture was stirred at 50°C for 2 hours to obtain coating solution 2.

[0085] <Manufacturing of Optical Filters> Optical filters with the layer configurations shown in Tables 2 to 4 were manufactured. Resin film 1 was formed by applying the above coating liquid 1 by spin coating. Resin film 2 was formed by applying the above coating liquid 2 by spin coating. SiO ２ Membrane and TiO ２ The films were layered by vapor deposition. The uneven layer was created by applying hot water treatment to an aluminum oxide film formed by vacuum deposition, as described above.

[0086]

[0087]

[0088]

[0089] For each optical filter, spectral transmittance curves at an incident angle of 0 degrees, and spectral reflectance curves at incident angles of 5 degrees and 60 degrees were measured using a UV-Vis spectrophotometer in the wavelength range of 350 to 1200 nm. The results are shown in Table 5 below. Note that T in the table ４５０－５００（０ｄｅｇ）ＭＡＸ This is the maximum transmittance T in the above spectral characteristics (1-7). ｍａｘ This represents T ４５０－５００（０ｄｅｇ）ＭＩＮ The minimum transmittance T ｍｉｎThis represents the above. Other symbols are as described above. Furthermore, for the optical filters of Examples 2 to 5 and Example 9, Figures 3 and 4 show the spectral transmittance curve on the first main surface side, Figure 5 shows the spectral reflectance curve at an incident angle of 5 degrees on the first main surface side, and Figures 6 to 7 show the spectral reflectance curve at an incident angle of 60 degrees on the second main surface side.

[0090]

[0091] As shown in Example 2, the optical filter using 300 μm thick phthalate glass had insufficient infrared shielding and high reflectivity. To adequately shield infrared rays using this phthalate glass, it was necessary to use phthalate glass with a thickness of 800 μm, as shown in Example 1. As shown in Example 3, even with phosphate glass, if the CuO content is less than 10%, a thickness of 300 μm was insufficient to adequately shield infrared rays. In contrast, the optical filters shown in Examples 4 to 15 use phosphate glass with a CuO content of 10% or more and a fluorine content of less than 10%, achieving high near-infrared shielding even with a substrate thickness of 300 μm or less, and it was found that optical filters achieving the above spectral characteristics (1-1) to (1-3) and spectral characteristic (2-1) can be obtained.

[0092] This application claims priority based on Japanese Patent Application No. 2025-018395 filed on 6 February 2025, Japanese Patent Application No. 2025-153913 filed on 17 September 2025, and Japanese Patent Application No. 2025-281174 filed on 24 December 2025, and incorporates all of their disclosures herein.

[0093] 1. Glass substrate 1a. First main surface 1b. Second main surface 2, 3. Anti-reflective layer 4. Resin film 10a, 10b. Optical filter

Claims

1. An optical filter having a glass substrate, wherein the thickness of the glass substrate is 300 μm or less, and satisfies the following spectral characteristics (1-1) to (1-3) when light is irradiated from the first main surface side, and satisfies the following spectral characteristic (2-1) when light is irradiated from the second main surface side: (1-1) Minimum transmittance of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees is 70% or more, (1-2) Average transmittance of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees is 0.5% or less, (1-3) In the range of wavelengths of 550 to 800 nm, the wavelength of light at which the transmittance at an incident angle of 0 degrees is 590 nm or more, (2-1) Average reflectance of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 30% or less.

2. The optical filter according to claim 1, wherein the thickness of the glass substrate is 250 μm or less.

3. The optical filter according to claim 1, which further satisfies the following spectral characteristics (1-4) when light is irradiated from the first main surface side. (1-4) The average reflectance of light with a wavelength of 800 to 1200 nm and an incident angle of 5 degrees is 70% or less.

4. The optical filter according to claim 1, which further satisfies the following spectral characteristics (1-5) when light is irradiated from the first main surface side. (1-5) The transmittance of light with a wavelength of 450 nm and an incident angle of 0 degrees is 70% or more.

5. The optical filter according to claim 1, which further satisfies the following spectral characteristics (1-6) when light is irradiated from the first main surface side. (1-6) The average transmittance of light with a wavelength of 800 to 1200 nm and an incident angle of 0 degrees is 0.2% or less.

6. The optical filter according to claim 1, which further satisfies the following spectral characteristics (2-2) when light is irradiated from the second main surface side. (2-2) The average reflectance of light with a wavelength of 400 to 600 nm and an incident angle of 60 degrees is 10% or less.

7. The optical filter according to claim 1, which further satisfies the following spectral characteristics (2-3) when light is irradiated from the second main surface side. (2-3) Average reflectance of light with a wavelength of 400 to 600 nm and an incident angle of 60 degrees is 5% or less.

8. The optical filter according to claim 1, wherein at least one of its outermost surfaces has an uneven surface layer.

9. The optical filter according to claim 1, wherein the fluorine content of the glass substrate is 10% by mass or less.

10. The optical filter according to claim 1, wherein the CuO content of the glass substrate is 10% by mass or more.

11. The optical filter according to claim 1, further satisfying the following spectral characteristics (1-7) when light is irradiated from the first main surface side. (1-7) Maximum transmittance T in the wavelength range of 450 to 500 nm in the spectral transmittance curve at an incident angle of 0 degrees ｍａｘ And, minimum transmittance T ｍｉｎ The ratio (T ｍｉｎ / T ｍａｘ ) is 0.920 or higher.

12. The optical filter according to claim 1, which further satisfies the following spectral characteristics (1-8) when light is irradiated from the first main surface side. (1-8) In the wavelength range of 550 to 800 nm, the difference between the wavelength of light at an incident angle of 0 degrees where the transmittance is 20% and the wavelength at which it is 50% is 45 nm or less.

13. The optical filter according to claim 1, which further satisfies the following spectral characteristics (1-9) when light is irradiated from the first main surface side. (1-9) The maximum transmittance of light with a wavelength of 450 to 550 nm and an incident angle of 0 degrees is 90% or more.

14. An imaging device comprising an optical filter according to any one of claims 1 to 13.

Images