Optical filter

Abstract

The present invention relates to an optical filter comprising a glass, a barrier film 1 provided between the glass and a dielectric multilayer film 1, a barrier film 2 provided between the glass and a dielectric multilayer film 2, and a light absorption layer provided on the dielectric multilayer film 2, wherein: the glass is a phosphate glass or a fluorophosphate glass; the light absorption layer includes a near-infrared absorption dye; and the optical filter satisfies all of specific spectral characteristics (i-1) to (i-3) and (i-6).

Description

Optical Filters

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

[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 wavelength 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 a reflective filter 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 the filter reflects light to be blocked by utilizing optical interference, an absorptive filter in which glass or a dye that absorbs light in a specific wavelength range is used to absorb light to be blocked, and a filter that combines a reflective type and an absorptive type.

[0004] Phosphate glass and fluorophosphate glass are known as light-absorbing glasses, but they are susceptible to the effects of moisture in the environment. Phosphate glass, in particular, has the risk of phosphoric acid elution, which may decompose other constituent materials of the optical filter. Therefore, technologies to prevent phosphoric acid elution have been investigated. Patent Document 1 describes phosphate glass whose surface is coated with alumina to form a protective film for improved moisture resistance. Patent Document 2 describes an infrared cut filter in which infrared-absorbing glass, such as phosphate glass, is bonded to a cover glass via an adhesive to improve moisture resistance.

[0005] Japanese Unexamined Patent Publication No. 4-139035 Japanese Unexamined Patent Publication No. 2016-18092

[0006] However, with the technology described in Patent Document 1, the phosphate glass surface covered with an alumina protective film is less susceptible to moisture and moisture resistance is improved, but it is not possible to prevent the reaction of moisture with the glass end face that is not covered with the protective film.Furthermore, there is a risk that phosphoric acid eluted from the glass end face will react with the alumina protective film, resulting in a decrease in adhesion and causing film peeling.Also, with the technology described in Patent Document 2, the adhesive is an organic material, so moisture is likely to penetrate from near the end face.As a result, there is a risk that phosphoric acid eluted from the glass will deteriorate the adhesive and reduce adhesion.

[0007] Furthermore, optical filters with dielectric multilayer films have a problem in that the optical thickness of the dielectric multilayer film changes depending on the angle of incidence of light, and therefore the spectral transmittance curve changes depending on the angle of incidence. In particular, with the recent trend toward lower profile camera modules, use under high angle of incidence is expected, and optical filters that are less susceptible to the effects of the angle of incidence are required.

[0008] An object of the present invention is to provide an optical filter that has excellent moisture resistance, and is excellent in transmittance in the visible light region and shielding in the near-infrared light region even at a high incident angle.

[0009] The present invention provides an optical filter or the like having the following configuration: An optical filter comprising glass, a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the glass, a barrier film 1 provided between the glass and the dielectric multilayer film 1, a barrier film 2 provided between the glass and the dielectric multilayer film 2, and a light absorbing layer provided on the dielectric multilayer film 2, wherein the glass is a phosphate glass having near-infrared absorbing properties and containing substantially no fluorine atoms, or a fluorophosphate glass having near-infrared absorbing properties and containing fluorine atoms, the light absorbing layer contains a near-infrared absorbing dye having a maximum absorption wavelength in the range of 680 to 800 nm, and when the glass is the phosphate glass, the barrier film 1 and the barrier film 2 each independently contain TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２When the glass is the fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain one or more selected from TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ An optical filter comprising one or more selected from the group consisting of: (i) an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-6): (i-1) an average transmittance of wavelengths from 440 to 500 nm is 80% or more at an incident angle of 0 degrees and 70% or more at an incident angle of 60 degrees; (i-2) an average transmittance of wavelengths from 750 to 1000 nm is 1% or less at an incident angle of 0 degrees and 1% or less at an incident angle of 60 degrees; and (i-3) a wavelength IR10 at which the transmittance is 10% in the spectral transmittance curve at an incident angle of 0 degrees. （０ｄｅｇ） (i-6) When the dielectric multilayer film 1 side is set as the incident direction, the maximum reflectance of the wavelength of 850 to 1200 nm is 85% or more at an incident angle of 5 degrees.

[0010] According to the present invention, an optical filter can be provided which has excellent moisture resistance, and is excellent in transmittance in the visible light region and shielding in the near-infrared light region even at a high incident angle.

[0011] FIG. 1 is a cross-sectional view schematically showing an example of an optical filter according to an embodiment. FIG. 2 is a cross-sectional view schematically showing another example of an optical filter according to an embodiment. FIG. 3 is a diagram showing the spectral transmittance curves of glasses 1, 3, and 4. FIG. 4 is a diagram showing the spectral transmittance curve of glass 2. FIG. 5 is a diagram showing the spectral transmittance curves of light absorbing layers 1 and 2. FIG. 6 is a diagram showing the spectral transmittance curve and the spectral reflectance curve of the optical filter of Example 2-1. FIG. 7 is a diagram showing the spectral transmittance curve and the spectral reflectance curve of the optical filter of Example 2-3.

[0012] Hereinafter, embodiments of the present invention will be described. In this specification, a near-infrared absorbing dye may be abbreviated as "NIR dye" and an 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.

[0013] In this specification, the transmittance of glass, the light-absorbing layer including those in which a dye is contained in a resin, the transmittance measured by dissolving a dye in a solvent such as dichloromethane, the transmittance of a dielectric multilayer film, and the transmittance spectrum of an optical filter having a dielectric multilayer film are all "external (measured) transmittance" including reflection losses on the front and back surfaces, even when they are described as "transmittance."

[0014] In this specification, a transmittance of, for example, 90% or more in a specific wavelength range means that the transmittance is not below 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 average transmittance in a specific wavelength range is the arithmetic mean of the transmittance per 1 nm in the wavelength range. Spectral characteristics can be measured using a UV-Vis spectrophotometer. In this specification, the term "to" indicating a numerical range includes the upper and lower limits.

[0015] <Optical Filter> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "the present filter") comprises glass that is phosphate glass or fluorophosphate glass, dielectric multilayer film 1 and dielectric multilayer film 2 provided on both sides of the glass, and a light absorbing layer provided on dielectric multilayer film 2. The present filter further comprises barrier film 1 between the glass and dielectric multilayer film 1, and barrier film 2 between the glass and dielectric multilayer film 2. Barrier films 1 and 2 contain specific materials, as described below. Such barrier films prevent the glass from reacting with moisture in the environment, resulting in an optical filter with excellent moisture resistance.

[0016] An example of the configuration of this filter will be described with reference to the drawings. Figures 1 and 2 are cross-sectional views that schematically show an example of an optical filter according to an embodiment.

[0017] The optical filter 1A shown in FIG. 1 is an example including glass 10, a dielectric multilayer film 21 provided on one main surface of the glass 10, a dielectric multilayer film 22 provided on the other main surface of the glass 10, a light absorbing layer 30 provided on the dielectric multilayer film 22, a barrier film 11 provided between the glass 10 and the dielectric multilayer film 21, and a barrier film 12 provided between the glass 10 and the dielectric multilayer film 22.

[0018] The optical filter 1B shown in FIG. 2 is an example further including a dielectric multilayer film 23 laminated on the surface of the light absorbing layer 30.

[0019] The optical filter according to the embodiment of the present invention satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-6): (i-1) The average transmittance for wavelengths from 440 to 500 nm is 80% or more at an incident angle of 0 degrees and 70% or more at an incident angle of 60 degrees; (i-2) The average transmittance for wavelengths from 750 to 1000 nm is 1% or less at an incident angle of 0 degrees and 1% or less at an incident angle of 60 degrees; (i-3) The wavelength IR10 at which the transmittance is 10% in the spectral transmittance curve at an incident angle of 0 degrees （０ｄｅｇ） (i-6) When the dielectric multilayer film 1 side is set as the incident direction, the maximum reflectance of the wavelength of 850 to 1200 nm is 85% or more at an incident angle of 5 degrees.

[0020] This filter, which satisfies all of the spectral characteristics (i-1) to (i-3) and (i-6), is an optical filter that has excellent transmittance for visible light, as shown in characteristic (i-1), and excellent blocking ability for near-infrared light with wavelengths of 750 to 1000 nm, as shown in characteristic (i-2).

[0021] Furthermore, the optical filter according to the embodiment of the present invention preferably satisfies the following spectral characteristics (i-4) and (i-5): (i-4) A wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm in the spectral transmittance curve at an incident angle of 0 degrees （０ｄｅｇ） and the wavelength IR10 where the transmittance is 10% in the range of 600 to 700 nm in the spectral transmittance curve at an incident angle of 60 degrees.（６０ｄｅｇ） (i-5) The transmittance at a wavelength of 1100 nm is 1% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 60 degrees.

[0022] This filter, which satisfies the spectral characteristics (i-4) and (i-5), is an optical filter that has excellent blocking properties for near-infrared light with a wavelength of 1,100 nm, as shown in characteristic (i-5), and is resistant to a shift in transmittance even at high angles of incidence, as shown in characteristic (i-4).

[0023] Satisfying the spectral characteristic (i-1) means that the transmittance in the visible light region of 440 to 500 nm is excellent even at a high incident angle. The average transmittance in the wavelength region of 440 to 500 nm is preferably 81% or more, more preferably 82% or more, at an incident angle of 0 degrees, and preferably 71% or more, more preferably 72% or more, at an incident angle of 60 degrees. In addition, in order to satisfy the spectral characteristic (i-1), for example, a dielectric multilayer film, glass, or near-infrared light absorbing dye having excellent transmittance in the visible light region may be used.

[0024] Satisfying the spectral characteristic (i-2) means that the film has excellent shielding properties for near-infrared light in the 750 to 1000 nm region even at a high incident angle. The average transmittance for wavelengths of 750 to 1000 nm is preferably 0.5% or less, more preferably 0.2% or less, at an incident angle of 0 degrees, and preferably 0.5% or less, more preferably 0.2% or less, at an incident angle of 60 degrees. In addition, in order to satisfy the spectral characteristic (i-2), for example, light shielding can be achieved by using glass or the absorption ability of a near-infrared light-absorbing dye.

[0025] Satisfying the spectral characteristic (i-3) means that the wavelength region of 600 to 700 nm is a region in which the spectral transmittance curve rises from the near-infrared blocking region to the visible light transmitting region. （０ｄｅｇ） is preferably in the range of 620 to 700 nm, more preferably in the range of 650 to 700 nm.

[0026] Satisfying the spectral characteristic (i-4) means that the spectral transmittance curve is unlikely to shift in the wavelength region of 600 to 700 nm even at a high incident angle. （０ｄｅｇ） and wavelength IR10（６０ｄｅｇ） The absolute value of the difference between the wavelengths is preferably 15 nm or less, more preferably 13 nm or less. In addition, in order to satisfy the spectral characteristic (i-4), for example, light in the wavelength region of 600 to 700 nm may be shielded by glass that is not affected by the angle of incidence or by the absorption ability of a near-infrared light absorbing dye.

[0027] Satisfying the spectral characteristic (i-5) means that the glass has excellent shielding properties in the near-infrared region of 1100 nm even at a high incident angle. The transmittance at a wavelength of 1100 nm is preferably 0.5% or less, more preferably 0.2% or less, at an incident angle of 0 degrees, and preferably 2% or less, more preferably 1% or less, at an incident angle of 60 degrees. In addition, in order to satisfy the spectral characteristic (i-5), for example, light blocking can be achieved by the absorption ability of the glass.

[0028] Satisfying the spectral characteristic (i-6) means that the light blocking property in the range of 850 to 1200 nm is ensured by the reflectance characteristics of the dielectric multilayer film 1. The maximum reflectance in the range of 850 to 1200 nm is preferably 90% or more, more preferably 95% or more.

[0029] The optical filter according to this embodiment preferably satisfies the following spectral characteristics (i-7) and (i-8). (i-7) When the light-absorbing layer side is the incident direction, the maximum reflectance for wavelengths of 450 to 750 nm is 20% or less at an incident angle of 60 degrees. (i-8) When the light-absorbing layer side is the incident direction, the maximum reflectance for wavelengths of 750 to 1200 nm is 42% or less at an incident angle of 60 degrees. Satisfying the spectral characteristics (i-7) and (i-8) means that the dielectric multilayer film 2 has low reflectance even at high incident angles in the wavelength range from visible light of 450 to 1200 nm to near-infrared light. Even if the multilayer film 2 has low reflectance for near-infrared light, the light is absorbed by the glass or the near-infrared light-absorbing dye and reflected by the multilayer film 1, so the light-blocking properties of the optical filter as a whole can be sufficiently ensured. The maximum reflectance for wavelengths of 450 to 750 nm is more preferably 19.8% or less, and even more preferably 19.5% or less. The maximum reflectance in the wavelength range of 750 to 1200 nm is more preferably 41.5% or less, and even more preferably 41.0% or less. The spectral characteristics (i-7) and (i-8) can be achieved, for example, by using a dielectric multilayer film 2 and a barrier film 2 in which X, which will be described later, is in a specific range.

[0030] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-9): (i-9) When the light-absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 750 nm is 7.5% or less at an incident angle of 5 degrees. Satisfying the spectral characteristic (i-9) means that the dielectric multilayer film 2 has low reflectance characteristics in the visible light to near-infrared light wavelength range of 450 to 750 nm. The maximum reflectance at wavelengths of 450 to 750 nm is more preferably 7.4% or less, and even more preferably 7.3% or less. The spectral characteristic (i-9) can be achieved, for example, by using a dielectric multilayer film 2 and a barrier film 2 in which X, which will be described later, is in a specific range.

[0031] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-10): (i-10) When the dielectric multilayer film 1 side is the incident direction, the average reflectance for wavelengths of 800 to 1100 nm is 95% or more at an incident angle of 5 degrees. Satisfying the spectral characteristic (i-10) means that the dielectric multilayer film 1 has wide reflection characteristics in the near-infrared light region of wavelengths of 800 to 1100 nm. The average reflectance for wavelengths of 800 to 1100 nm is more preferably 96% or more, and even more preferably 97% or more.

[0032] <Glass> The optical filter according to this embodiment includes phosphate glass or fluorophosphate glass. Phosphate glass or fluorophosphate glass has near-infrared absorbing properties and also functions as a support for the optical filter. Furthermore, because it blocks light by its absorption properties, the light blocking properties are less susceptible to the influence of the angle of incidence, unlike a dielectric multilayer film.

[0033] The glass preferably has a transmittance of 80% or more at a wavelength of 420 nm, a transmittance of 6% or less at a wavelength of 800 nm, and a transmittance of 25% or less at a wavelength of 1200 nm, calculated based on a plate thickness of 0.2 mm. Glass that satisfies these spectral characteristics is preferred because it has sufficient transmittance for visible light and excellent near-infrared light absorption ability.

[0034] In this specification, phosphate glass is a glass containing P in mole percent based on oxides. ２ O ５ The term "substantially free of fluorine atoms" means that, when the content of component elements other than F contained in the glass is taken as 100 mass %, and the content of F contained in the glass is expressed as an exclusive percentage, the content of F is less than 3 mass %. In this specification, fluorophosphates glass refers to glass containing 40% or more of P in mass %. ５＋ Contains 20% or more of F － This refers to glass containing 3% or more of the above.

[0035] Phosphate glass contains substantially no fluorine atoms and contains P in mole percent on an oxide basis. ２ O ５ 40%~75%, Al ２O ３ 10% to 30%, ΣR ２ O 0.1% to 30% (However, R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ and one or more components selected from ΣR ２ O is R ２ It is preferable that the glass contains: ΣR′O 0% to 30% (where R′O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR′O represents the total content of R′O); and CuO 2% to 30%.

[0036] Fluorophosphate glass is expressed as mass % and contains: ５＋ 20-70% Al ３＋ 1-20% Li ＋ 0-30% Na ＋ 0-40% K ＋ 0-40% Rb ＋ 0-20% Cs ＋ 0-20% Mg ２＋ 0-20% Ca ２＋ 0-20% Sr ２＋ 0-30% Ba ２＋ 0-45% ΣR ＋ 1 to 55% (R ＋ Li ＋ , Na ＋ , K. ＋ , Rb ＋ and Cs ＋ one or more components selected from the following: ２＋ 1 to 50% (R' ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ one or more components selected from the group consisting of: ２＋ 1-20% Zn ２＋ The glass contains 0 to 20% of F. － When the component elements other than F are taken as 100 mass%, －It is preferable that the content is 3 to 60 mass % in terms of the outer ratio.

[0037] Each component that can constitute phosphate glass and its suitable content will be described below. In the following description of phosphate glass, unless otherwise specified, the content of each component and the total content will be expressed in mole percent based on the oxide.

[0038] P ２ O ５ is the main component that forms glass and is a component that enhances the near-infrared ray blocking properties. ２ O ５ If the content is 40% or more, the effect is sufficiently obtained, and if it is 75% or less, problems such as glass instability and reduced weather resistance are unlikely to occur. Therefore, the content is preferably 45 to 75%, more preferably 50 to 70%, even more preferably 52 to 65%, still more preferably 54 to 65%, and most preferably 55 to 60%.

[0039] Al ２ O ３ is the main component that forms glass, and is a component that increases the strength and weather resistance of glass. ２ O ３ If the content of Al is 10% or more, the effect is sufficiently obtained, and if it is 30% or less, problems such as glass instability and reduced near-infrared cutoff are unlikely to occur. Therefore, the content is preferably 10 to 30%, more preferably 11 to 27%, even more preferably 12 to 26%, still more preferably 12.5 to 25%, and most preferably 13 to 24%. ２ O ３ If the content is 13% or more, the weather resistance of the glass can be particularly improved.

[0040] R ２ O (However, R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２O) are components for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ２ The total amount of O (ΣR ２ If O) is 0.1% or more, the effect is sufficiently obtained, and if it is 30% or less, the glass is less likely to become unstable, which is preferable. Therefore, it is preferably 1 to 25%, more preferably 2 to 20%, even more preferably 3 to 18%, still more preferably 4 to 17%, and most preferably 5 to 18%.

[0041] Li ２ O is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, etc. ２ The content of O is preferably 0 to 20%. ２ If the O content is 20% or less, problems such as the glass becoming unstable or the near-infrared cutoff property being reduced are unlikely to occur, and therefore it is preferable. It is more preferably 0 to 15%, even more preferably 0 to 10%, still more preferably 0 to 5%, and most preferably Li ２ It should be noted that, in the present invention, "substantially free of O" means that a specific component is not intentionally added, and does not exclude the inclusion of a component that is unavoidably mixed in from raw materials or the like and that does not affect the desired properties.

[0042] Na ２ O is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. ２ The content of O is preferably 0 to 25%. ２ If the O content is 25% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 20%, even more preferably 1 to 15%, and even more preferably 2 to 10%.

[0043] K ２ O is a component that has the effect of lowering the melting temperature of the glass and the liquidus temperature of the glass. ２ The O content is preferably 0 to 25%. ２If the O content is 25% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 20%, even more preferably 1 to 15%, and even more preferably 2 to 13%.

[0044] Rb ２ O is a component that has the effects of lowering the melting temperature of the glass and lowering the liquidus temperature of the glass. ２ The content of O is preferably 0 to 25%. ２ If the O content is 25% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 20%, even more preferably 1 to 15%, and even more preferably 2 to 10%.

[0045] Cs ２ O is a component that has the effect of lowering the melting temperature of the glass and the liquidus temperature of the glass. ２ The content of O is preferably 0 to 25%. ２ If the O content is 25% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 20%, even more preferably 1 to 15%, and even more preferably 2 to 10%.

[0046] In addition, the above R ２ The alkali metal components represented by O produce a mixed alkali effect in the glass by adding two or more of each component at the same time, and R ＋ The mobility of ions is reduced, so that when the glass comes into contact with water, the H ＋ Ions and R in glass ＋ The hydration reaction caused by the ion exchange of ions is inhibited, and the weather resistance of the glass is improved. ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ In this case, it is preferable that the compound contains two or more components selected from R ２ O (However, R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb２ O, and Cs ２ The total amount (ΣR ２ O) is preferably 6 to 18% (but not including 7%). ２ If the total amount of O is 6% or more, the effect can be sufficiently obtained, and if it is 18% or less, problems such as instability of the glass, deterioration of the near-infrared cutoff property, and deterioration of the strength of the glass are unlikely to occur, which is preferable. ２ O is preferably 7 to 18%, more preferably 8 to 18%, even more preferably 9 to 18%, still more preferably 10 to 18%, and most preferably 10.5 to 18%.

[0047] R'O (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and increases the strength of the glass. The total amount of R'O (ΣR'O) is preferably 0 to 30%. A total amount of R'O of 30% or less is preferred because problems such as glass instability, reduced near-infrared blocking ability, reduced short-wavelength infrared transmittance, and reduced glass strength are less likely to occur. The amount is more preferably 0 to 25%, and even more preferably 0 to 20%. The amount is even more preferably 0 to 15%, and even more preferably 0 to 10%.

[0048] The phosphate glass of this embodiment preferably does not substantially contain divalent cations other than Cu. The reason for this is as follows. When the phosphate glass of this embodiment contains CuO, Cu ２＋ Light absorption in the near-infrared region is cut off by ions. ２－ Cu split by the electric field of ions ２＋ This occurs due to electron transitions between the d orbitals of the ions. The splitting of the d orbitals occurs in Cu ２＋ O present around the ion ２－ This is promoted by reducing the symmetry of the ion. For example, O ２－ When positive ions are present around an ion, the electric field of the positive ions causes the ２－ Ions are attracted and O ２－The symmetry of the ions decreases. As a result, the splitting of d orbitals is promoted, and light absorption occurs due to electronic transitions between the split d orbitals, weakening the light absorption ability in the near-infrared region and strengthening the light absorption ability in the short-wavelength infrared region. Since the strength of the electric field of a cation increases with the valence of the ion, adding an oxide containing a divalent cation other than Cu to glass may reduce the near-infrared blocking ability and reduce the transmittance of short-wavelength infrared light.

[0049] CaO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The CaO content is preferably 0 to 20%. A CaO content of 20% or less is preferred because it is less likely to cause problems such as glass instability, reduced near-infrared blocking properties, and reduced transmittance of short-wavelength infrared rays. The CaO content is more preferably 0 to 15%, even more preferably 0 to 10%, and even more preferably 0 to 5%. Most preferably, the glass contains substantially no CaO.

[0050] MgO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The MgO content is preferably 0 to 20%. An MgO content of 20% or less is preferred because it is less likely to cause problems such as glass instability, reduced near-infrared blocking properties, and reduced transmittance of short-wavelength infrared rays. The content is more preferably 0 to 15%, even more preferably 0 to 10%, and even more preferably 0 to 5%. Most preferably, the glass is substantially free of MgO.

[0051] BaO is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and so on. The BaO content is preferably 0 to 20%. A BaO content of 20% or less is preferable because it is less likely to cause problems such as glass instability, reduced near-infrared blocking properties, and reduced transmittance of short-wavelength infrared rays. The BaO content is more preferably 0 to 15%, even more preferably 0 to 10%, and even more preferably 0 to 5%. The BaO content may be 0.1% or more. Most preferably, BaO is substantially not contained.

[0052] SrO is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and so on. The SrO content is preferably 0 to 20%. If the SrO content is 20% or less, problems such as glass instability, reduced near-infrared blocking properties, and reduced transmittance of short-wavelength infrared rays are unlikely to occur, which is preferable. The SrO content is more preferably 0 to 15%, and even more preferably 0 to 10%. Most preferably, the glass is substantially free of SrO.

[0053] ZnO has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The ZnO content is preferably 0 to 20%. A ZnO content of 20% or less is preferable because problems such as deterioration of the melting point of the glass, deterioration of the near-infrared blocking ability, and deterioration of the transmittance of short-wavelength infrared rays are unlikely to occur. The ZnO content is more preferably 0 to 15%, even more preferably 0 to 10%, and even more preferably 0 to 5%. Most preferably, ZnO is substantially not contained.

[0054] CuO is a component for blocking near-infrared rays. The CuO content is preferably 2 to 30%. A CuO content of 2% or more provides sufficient effects, while a CuO content of 30% or less is preferable because problems such as reduced transmittance in the visible light region and reduced transmittance in the short-wavelength infrared region are unlikely to occur. It is more preferably 5 to 25%, even more preferably 8 to 20%, and even more preferably 11 to 18%. Furthermore, it is even more preferably 12% or more. In particular, when the glass is substantially free of divalent cations other than Cu, a CuO content of 12% or more can further enhance the near-infrared blocking properties and the short-wavelength infrared transmittance. It is most preferably 13 to 18%.

[0055] B ２ O ３ may be contained in an amount of 15% or less to stabilize the glass. ２ O ３If the content of B is 15% or less, problems such as deterioration of the weather resistance of the glass, deterioration of the near-infrared cutoff property, and deterioration of the transmittance of short-wavelength infrared rays are unlikely to occur, and therefore it is preferable. It is preferably 13% or less, more preferably 11% or less, even more preferably 9% or less, still more preferably 7% or less, and most preferably B ２ O ３ It is substantially free of

[0056] MoO ３ is a component for increasing the transmittance of light in the visible region of the glass. ３ If the content is 0.1% or more, the effect of increasing the transmittance of light in the visible region of the glass is sufficient, and if it is 5% 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, so this is preferable. The content is more preferably 0.1 to 4.5%, even more preferably 0.1 to 4%, even more preferably 0.1 to 3.5%, and most preferably 0.1 to 3%.

[0057] In the phosphate glass of this embodiment, F (fluorine atoms) is an effective component for improving weather resistance, but is an environmentally hazardous substance and may reduce near-infrared blocking properties, so the glass does not substantially contain F. "Substantially not containing fluorine atoms" means that, when the content of component elements other than F in the glass is taken as 100 mass % and the content of F in the glass is expressed as an exclusive percentage, the content of F is less than 3 mass %.

[0058] In the phosphate glass of this embodiment, SiO ２ , GeO ２ , ZrO ２ , SnO ２ , TiO ２ , CeO ２ , W.O. ３ , Y ２ O ３ , La ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Nb ２ O ５may be contained in a range of 5% or less to improve the weather resistance of the glass. If the content of these components is 5% or less, problems such as a decrease in near-infrared blocking ability and a decrease in transmittance of short-wavelength infrared rays are unlikely to occur, which is preferable. 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.

[0059] Next, each component that can constitute the fluorophosphate glass and a suitable content thereof will be described below. In the following description of the fluorophosphate glass, the content of each component and the total content will be expressed in mass % unless otherwise specified.

[0060] In fluorophosphate glass, P (phosphorus) 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 sharp cutoff property in the near-infrared region. ５＋ The content of P is preferably 20% to 70%. ５＋ If the content of P is 20% or more, the effect is sufficiently obtained, and if it is 70% or less, problems such as glass instability and deterioration of weather resistance are unlikely to occur. Therefore, it is more preferably 25% or more, even more preferably 30% or more, even more preferably 33% or more, most preferably 35% or more, and more preferably 60% or less, even more preferably 55% or less, even more preferably 50% or less, and most preferably 45% or less. 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.

[0061] In fluorophosphate glass, F (fluorine) 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 the above is taken as 100 mass%, the amount of F contained in the glass is － The content of F is expressed as an external percentage. － The content is preferably 3% to 60% by weight.

[0062] F － If the content of F is 3% or more by external proportion, a sufficient weather resistance effect can be obtained, and if the content is 60% or less by external proportion, problems such as a decrease in light transmittance in the visible region, absorption ability of light in the near-infrared region, and sharp cutting properties, a decrease in mechanical properties such as strength, hardness, and elastic modulus, and an increase in ultraviolet light transmittance are unlikely to occur. － is more preferably an external proportion of 4% or more, even more preferably an external proportion of 6% or more, even more preferably an external proportion of 8% or more, and most preferably an external proportion of 10% or more, and more preferably an external proportion of 50% or less, even more preferably an external proportion of 40% or less, even more preferably an external proportion of 30% or less, and most preferably an external proportion of 20% or less.

[0063] In fluorophosphate glass, Cu (copper) 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.

[0064] Cu ２＋ is a component for improving absorption in the near-infrared region. ２＋ Cu has the property of attracting phosphate chains in the glass together to form a cross-linked structure, which strengthens the glass structure and improves the weather resistance and strength of the glass. ２＋ The content of Cu is preferably 1% to 20%. If it is less than 1%, the absorption ability of the glass in the near-infrared region may decrease. ２＋ is preferably 2% or more, more preferably 3% or more, even more preferably 4% or more, and even more preferably 5% or more. If it exceeds 20%, the glass becomes unstable and the risk of devitrification increases. ２＋ is preferably 18% or less, more preferably 14% or less, even more preferably 12% or less, and even more preferably 10% or less.

[0065] The total Cu content is the total amount of Cu expressed in mass %, including monovalent, divalent, and other valences present, and is the content of all components of the fluorophosphate glass (however, F －When the total Cu content (excluding the content of Cu) is taken as 100%, the range of the total Cu content in the glass is preferably 1% to 20%. When the total Cu content is 1% or more, the effect of absorption ability in the near-infrared region can be sufficiently obtained, and when it is 20% or less, the decrease in visible region transmittance can be suppressed. ＋ The content in % is (Cu ＋ The content of Cu can be determined so that the content of Cu (Cu content) × 100 [%] is in the range of 0.01% to 4.0%.

[0066] In fluorophosphate glass, Al (aluminum) is Al ３＋ It is contained as Al. ３＋ is a component that forms glass and is a component that increases the strength of glass, increases the weather resistance of glass, etc. ３＋ If the content of Al is 1% or more, the effect can be sufficiently obtained, and if it is 20% or less, problems such as the glass becoming unstable and a decrease in absorption ability and sharp cut property in the near-infrared region are unlikely to occur. ３＋ The content of Al is preferably 1% to 20%. ３＋ The content is more preferably 2% or more, even more preferably 3% or more, even more preferably 4% or more, and most preferably 5% or more, and is more preferably 19% or less, even more preferably 18% or less, even more preferably 15% or less, and most preferably 13% or less.

[0067] In addition, Al ３＋ As a raw material for ３ , Al ２ O ３ , Al(OH) ３ Among others, the increase in melting temperature, the occurrence of unmelted material, and F － The amount of AlF is reduced, which makes the glass less stable. ３ It is preferable to use

[0068] Li (lithium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, improves the weather resistance of glass, stabilizes glass, and the like. ＋The content of Li is preferably 0% to 30%. ＋ If the content is 30% or less, the glass is less likely to become unstable. Since the inclusion of Li reduces the absorption ability and sharp cut property in the near-infrared region, it is more preferably 28% or less, even more preferably 25% or less, even more preferably 20% or less, and most preferably 10% or less. It is more preferably 0.5% or more, even more preferably 1% or more, and even more preferably 3% or more. When the alkali metal component is Li ＋ If only Li is used, the weather resistance will improve but the absorption ability and sharp cut in the near infrared region will decrease. ＋ It is necessary to further include one or more alkali metal components having a larger ionic radius.

[0069] Na (sodium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. ＋ The content of Na is preferably 0% to 40%. ＋ If the content of Na is 40% or less, the glass is less likely to become unstable. It is more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, and most preferably 10% or less. It is more preferably 0.5% or more, even more preferably 1% or more, and even more preferably 3% or more. When the alkali metal component is Na ＋ If only Na is used, either the weather resistance or the high absorption capacity and sharp cut performance in the near-infrared region can be improved, and the improved properties differ depending on the composition. However, it is difficult to improve both properties at the same time. Therefore, in order to improve weather resistance, Na ＋ In order to improve absorption and sharp cut in the near infrared region, Na ＋ It is necessary to include an alkali metal component having a larger ionic radius.

[0070] In fluorophosphate glass, K (potassium) is K ＋ It is contained as K. ＋is a component that has the effects of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, and improving the absorption ability and sharp cut property in the near-infrared region. ＋ The content of is preferably 0% to 40%. ＋ If the content of K is 40% or less, the glass is less likely to become unstable, which is preferable. It is more preferably 0.5% or more, even more preferably 1% or more, still more preferably 3% or more, and most preferably 5% or more. ＋ If the alkali metal component is K, the weather resistance is reduced, so the content is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, and most preferably 14% or less. ＋ If only K is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0071] Rb (rubidium) is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, and improving the absorption ability and sharp cut property in the near-infrared region. ＋ The content of Rb is preferably 0% to 20%. ＋ If the content of Rb is 20% or less, the glass is less likely to become unstable, which is preferable. ＋ Since the weather resistance is reduced when the alkali metal component is Rb, the content is more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less. More preferably, the content is 0.5% or more, even more preferably 1% or more, and even more preferably 3% or more. ＋ If only Rb is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0072] Cs (cesium) is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, and improving high absorption capacity and sharp cut properties in the near-infrared region. ＋ The content of Cs is preferably 0% to 20%. ＋ If the content of Cs is 20% or less, the glass is less likely to become unstable, which is preferable. ＋ Since the weather resistance is reduced when the alkali metal component is contained, the content is more preferably 15% or less, further preferably 10% or less, and even more preferably 5% or less. More preferably, the content is 0.5% or more, further preferably 1% or more, and further preferably 3% or more. ＋ If only Cs is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0073] R ＋ (R ＋ Li ＋ , Na ＋ , K. ＋ , Rb ＋ and Cs ＋ R) is a component for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ＋ The total amount of Li ＋ , Na ＋ , K. ＋ , Rb ＋ and Cs ＋ The total amount (ΣR ＋ If ΣR ) is 1% or more, the effect is sufficiently obtained, and if it is 55% or less, the glass is less likely to become unstable, which is preferable. ＋ The content is preferably 1% to 55%, more preferably 5% or more, even more preferably 10% or more, even more preferably 12% or more, and most preferably 15% or more, and more preferably 45% or less, even more preferably 40% or less, even more preferably 30% or less, and most preferably 28% or less.

[0074] Mg (magnesium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of glass. ２＋ The content of Mg is preferably 0 to 20%. ２＋ 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 15% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0075] Ca (calcium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of glass. ２＋ The content of Ca is preferably 0% to 20%. ２＋ 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 1% or more, even more preferably 2% or more, and more preferably 18% or less, even more preferably 15% or less, still more preferably 10% or less, and most preferably 7% or less.

[0076] Strontium (Sr) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of 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 cutoff properties are unlikely to occur. It is more preferably 1% or more, even more preferably 2% or more, even more preferably 4% or more, and most preferably 5% or more, and is more preferably 25% or less, even more preferably 20% or less, even more preferably 16% or less, and most preferably 14% or less.

[0077] Ba (barium) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, enhances the absorption ability of light in the near-infrared region, and enhances the sharp cut property in the near-infrared region. ２＋ The content of Ba is preferably 0% to 40%. ２＋ If the content is 40% or less, problems such as glass instability are unlikely to occur. It is more preferably 1% or more, even more preferably 5% or more, still more preferably 10% or more, and more preferably 35% or less, even more preferably 30% or less, and still more preferably 20% or less.

[0078] R ２＋ (R ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ R) is a component for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ２＋ The total amount of Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total amount (ΣR ２＋ If ΣR is 1% or more, the effect is sufficiently obtained, and if it is 50% or less, the glass is unlikely to become unstable. ２＋ The content is preferably 1% to 50%, more preferably 5% or more, even more preferably 10% or more, even more preferably 15% or more, and most preferably 20% or more, and more preferably 45% or less, even more preferably 40% or less, even more preferably 35% or less, and most preferably 32% or less.

[0079] Zn (zinc) 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 20%. ２＋If the content is 20% or less, problems such as glass instability, deterioration in the melting property of the glass, and reduction in the near-infrared cutoff property are unlikely to occur. It is more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0080] P ５＋ Content of / ΣR″ (R″ is Al ３＋ , Mg ２＋ , Li ＋ and ΣR″ is the total amount of R″) is preferably 3.0 to 7.5.

[0081] P ５＋ is a component that enhances the sharp cut performance in the near infrared region, but also has the effect of reducing weather resistance. ３＋ , Li ＋ , Mg ＋ are components that have the effect of improving weather resistance.

[0082] Therefore, P for ΣR ５＋ By making the content ratio of ΣR″ 7.5 or less, the weather resistance of the glass can be improved. ５＋ By setting the content ratio of P to ΣR″ to be 3.0 or more, the sharp cutting properties of the glass in the near-infrared region can be maintained at a high level. ５＋ is more preferably 3.5 or more, even more preferably 4.0 or more, still more preferably 4.5 or more, and is more preferably 7.0 or less, even more preferably 6.5 or less, still more preferably 6.0 or less, and most preferably 5.5 or less.

[0083] B (boron) may be contained in an amount of up to 20% in order to stabilize the glass. ３＋ If the content is 20% or less, problems such as deterioration in the weather resistance of the glass and a decrease in the near-infrared cutoff property are unlikely to occur. It is more preferably 15% or less, even more preferably 10% or less, still more preferably 8% or less, and most preferably 5% or less.

[0084] In fluorophosphate glass, SiO２ , GeO ２ , ZrO ２ , SnO ２ , TiO ２ , CeO ２ , W.O. ３ , Y ２ O ３ , La ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Nb ２ O ５ may be contained in a range 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 inclusions in the glass and a decrease in the near-infrared cutoff 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.

[0085] Fe ２ O ３ , Cr ２ O ３ , Bi ２ O ３ , NiO, V ２ O ５ , MnO ２ and CoO are 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 for 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.

[0086] The thickness of the glass is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less, from the viewpoint of ease of optical design when incorporating it into a camera module, and is preferably 0.05 mm or more, more preferably 0.1 mm or more, from the viewpoint of element strength and the need to obtain desired optical characteristics.

[0087] <Barrier Film> The optical filter according to this embodiment has barrier films 1 and 2 on both main surfaces of the glass. When the glass is phosphate glass, the barrier films 1 and 2 each independently contain TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ When the glass is a fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain one or more selected from TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ The material contains one or more selected from the group consisting of TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ In order to improve moisture resistance, when the glass is phosphate glass, the barrier film is preferably TiO ２ When the glass is a fluorophosphate glass, the barrier film preferably contains TiO ２ and Al ２ O ３ It is preferable that the barrier films 1 and 2 contain at least one of the following: Note that resin materials are not preferable as materials for the barrier films 1 and 2, since they have a lower ability to prevent moisture penetration than inorganic materials.

[0088] When the glass is a phosphate glass, the barrier film is TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２Preferably, the barrier film contains one or more selected from the group consisting of TiO 2 and TiO 3 in a total content of 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and particularly preferably 100 mol %. ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ The composition may contain 80 mol % or more of one or more materials selected from the above, or may contain 80 mol % or more of two or more materials in total.

[0089] When the glass is a fluorophosphate glass, the barrier film is TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ Preferably, the barrier film contains one or more selected from the group consisting of TiO 2 and TiO 3 in a total content of 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and particularly preferably 100 mol %. ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ The composition may contain 80 mol % or more of one or more materials selected from the above, or may contain 80 mol % or more of two or more materials in total.

[0090] The barrier film is preferably made of TiO within a range that does not impair resistance to moisture. ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ For example, from the viewpoint of adjusting the refractive index of the barrier film, SiO ２On the other hand, since a layer containing silicon (Si) may reduce adhesion to a glass substrate, it is preferable to avoid containing silicon as much as possible. ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ In order to improve the water resistance of the optical filter, it is preferable that the optical filter does not contain any materials other than oxides of metals such as aluminum (Al), titanium (Ti), niobium (Nb), tantalum (Ta), and hafnium (Hf).

[0091] Furthermore, it is preferable that the physical thickness of the barrier film 2 and the dielectric multilayer film 2 positioned in the direction of incidence of external light satisfy a specific condition. That is, when a film consisting of the barrier film 2 and the dielectric multilayer film 2 is defined as the laminated film 2, X represented by the following formula (1) is preferably 35% or more.

[0092] X (%) = {A / (B-C)} x 100 (1) In formula (1), when each layer included in the laminate film 2 is evaluated by the QWOT expressed by the following formula (2), A (nm) is the total thickness of the dielectric layers included in the laminate film 2 that have a QWOT of less than 2 and a refractive index of 1.9 or less. B (nm) is the overall thickness (total physical film thickness) of the laminate film 2. C (nm) is the total thickness of the layers in the laminate film 2 that have a QWOT of 2 or more. Here, QWOT (Quarter Wave Optical Thickness) is the optical film thickness at a wavelength of λ / 4, and is calculated by the following formula (2). QWOT = (thickness of target layer (nm) / 550 (nm)) × 4 × (refractive index of target layer at 550 nm) (2) The above X represents the level of barrier performance in the laminated film 2, and by controlling X, the combined reflectance of the barrier film 2 and the dielectric multilayer film 2 can be controlled, and the effect of high barrier performance can be obtained. If X is 35% or more, for example, the maximum reflectance at wavelengths of 450 to 750 nm when the light absorbing layer side is the incident direction, as shown in the spectral characteristics (i-9) of the optical filter, falls within the desired range, which is preferable. As described above, by suppressing the maximum reflectance when the light absorbing layer side is the incident direction, it is possible to suppress the intrusion of unnecessary light into the sensor. In other words, by providing a barrier film 2 and a dielectric multilayer film 2 with X satisfying 35% or more, the reflectance on the light absorbing layer side can be controlled. X is more preferably 50% or more, and even more preferably 70% or more.

[0093] The total thickness B (nm) of the laminate film 2 is determined by adding together the physical film thickness of the barrier film 2 and the physical film thickness of the dielectric multilayer film 2. The total thickness C (nm) of the layers in the laminate film 2 having a QWOT of 2 or more is determined by adding together the physical film thicknesses of the barrier film 2 and the layers in the dielectric multilayer film 2 having a QWOT of 2 or more. The total thickness A (nm) of the layers in the laminate film 2 having a QWOT of less than 2 and a refractive index of 1.9 or less is determined by adding together the physical film thicknesses of the layers in the barrier film 2 and the dielectric multilayer film 2 having a QWOT of less than 2 and a refractive index of 1.9 or less.

[0094] The thickness of the barrier film 1 is preferably 10 nm or more, more preferably 20 nm or more, from the viewpoint of improving the moisture resistance and reliability of the optical filter. The thickness of the barrier film 2 is preferably 10 nm or more, more preferably 20 nm or more, from the viewpoint of improving the moisture resistance and reliability of the optical filter.

[0095] The total physical film thickness of the barrier film 1 and the dielectric multilayer film 1 is preferably 1 μm or more, more preferably 2 μm or more. This range is preferable from the viewpoints of improving the water resistance of the optical filter and preventing film deformation when the glass surface is altered. The total physical film thickness of the barrier film 2 and the dielectric multilayer film 2 is preferably 100 nm or more, more preferably 200 nm or more. This range is preferable from the viewpoints of improving the water resistance of the optical filter and preventing film deformation when the glass surface is altered.

[0096] The barrier film can be formed by, for example, a vacuum film-forming process such as CVD, sputtering, or vacuum deposition, or a wet film-forming process such as spraying or dipping.

[0097] The laminated film 2 is SiO ２ In the case where the laminated film 2 has a layer made of SiO, X' represented by the following formula (3) may be 35% or more. X' (%) is more preferably 50% or more, and even more preferably 70% or more. X' (%) = {A' / (B'-C')} x 100 (3) In formula (3), A' (nm) represents the percentage of SiO in the laminated film 2 having a thickness of 180 nm or less. ２ B' (nm) is the total thickness of the laminated film 2; C' (nm) is the thickness of the SiO 2 layer having a thickness greater than 180 nm in the laminated film 2; ２ is the total thickness of the layer.

[0098] <Dielectric multilayer film> The optical filter according to this embodiment has a dielectric multilayer film 1 on the barrier film 1 side and a dielectric multilayer film 2 on the barrier film 2 side. As will be described in detail later, when a film made up of the barrier film 1 and the dielectric multilayer film 1 is defined as stacked film 1, and when a film made up of the barrier film 2 and the dielectric multilayer film 2 is defined as stacked film 2, at least one of stacked film 1 and stacked film 2 is preferably designed as a reflective film that reflects a portion of near-infrared light (hereinafter also referred to as an "NIR reflective film"), and from the viewpoint of near-infrared light blocking properties, it is more preferable that at least stacked film 1 is an NIR reflective film.

[0099] The NIR reflective film preferably has wavelength selectivity that transmits visible light and primarily reflects near-infrared light, and may also be appropriately designed to reflect light in wavelength ranges other than near-infrared light, such as near-ultraviolet light.

[0100] A dielectric multilayer film is a laminate of dielectric films with 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 two or more of these laminated films. When transmitting or selecting a desired wavelength band, the reflection characteristics can be adjusted by combining several types of dielectric films with different spectral characteristics.

[0101] The high refractive index material preferably has a refractive index of 1.8 or more and 3.0 or less, more preferably 1.8 or more and 2.8 or less, and even more preferably 1.8 or more and 2.5 or less at a wavelength of 500 nm. ２ O ５ , TiO ２ , TiO, Nb ２ O ５ Other commercially available products include OS50 (Ti) manufactured by Canon Optron Co., Ltd. ３ O ５ ), OS10 (Ti ４ O ７ ), OA500 (Ta ２ O ５ and ZrO ２ a mixture of OA600 (Ta ２ O ５ and TiO ２Among these, TiO is preferred in terms of film-forming property, reproducibility in refractive index, stability, etc. ２ is preferred.

[0102] The medium refractive index material is a material having a relatively lower refractive index than the high refractive index material, and the refractive index at a wavelength of 500 nm is preferably 1.5 or more and 2.0 or less, more preferably 1.5 or more and 1.95 or less, and even more preferably 1.5 or more and 1.8 or less. ２ , Nb ２ O ５ , Al ２ O ３ , HfO ２ and OM-4 and OM-6 (Al) sold by Canon Optron. ２ O ３ and ZrO ２ Among these, Al is preferred in terms of film-forming properties, reproducibility in refractive index, stability, etc. ２ O ３ Al-based compounds ２ O ３ and ZrO ２ A mixture of is preferred.

[0103] The low refractive index material is a material having a refractive index relatively lower than that of the medium refractive index material, and the refractive index at a wavelength of 500 nm is preferably 1.3 or more and 1.7 or less, more preferably 1.3 or more and 1.65 or less, and even more preferably 1.4 or more and 1.5 or less. Examples of low refractive index materials include SiO ２ , SiO ｘ N ｙ、 MgF ２ Other commercially available products include S4F and S5F (SiO ２ and AlO ２ Among these, SiO is preferred from the viewpoints of reproducibility, stability, economy, etc. in film formation. ２ is preferred.

[0104] The laminate film 1 consisting of the barrier film 1 and the dielectric multilayer film 1 is preferably designed so that the optical filter satisfies the spectral characteristic (i-6), i.e., when the dielectric multilayer film 1 side is the incident direction, the maximum reflectance for wavelengths of 850 to 1200 nm is 85% or more at an incident angle of 5 degrees. The optical filter is also preferably designed so that the spectral characteristic (i-10), i.e., when the dielectric multilayer film 1 side is the incident direction, the average reflectance for wavelengths of 800 to 1100 nm is 95% or more at an incident angle of 5 degrees. The spectral characteristics (i-6) and (i-10) of the optical filter substantially reflect the reflection characteristics of the laminate film 1. In other words, the laminate film 1 is preferably capable of reflecting a wide range of near-infrared light.

[0105] The laminated film 1 preferably has an average transmittance of 93% or more for wavelengths of 440 to 500 nm at an incident angle of 0 degrees and 84% or more for wavelengths of 60 degrees. Furthermore, the laminated film 1 preferably has a maximum transmittance of 90% or more for wavelengths of 430 to 750 nm at an incident angle of 0 degrees and a maximum transmittance of 70% or more for wavelengths of 400 to 670 nm at an incident angle of 60 degrees.

[0106] The thickness (physical thickness) of the dielectric multilayer film 1 is preferably 1 μm or more, more preferably 1.5 μm or more, from the viewpoint of reducing the incidence angle dependency of the spectral characteristics and also providing a function of protecting the glass, and is preferably 10 μm or less from the viewpoints of productivity and suppressing reflection ripples in the visible light region. When the dielectric multilayer film 1 as a whole is a thick film of 1 μm or more, the reflection characteristics are less likely to vary with the incidence angle. This is because the thicker the film, the less sensitive it is to interference.

[0107] The dielectric multilayer film 1 preferably satisfies the following characteristic (iiA-1): (iiA-1) A high refractive index layer H made of a high refractive index material having a refractive index of 1.8 or more and 3.0 or less at a wavelength of 500 nm. Ａ and a medium refractive index layer M made of a medium refractive index material having a refractive index relatively lower than that of the high refractive index material and having a refractive index of more than 1.5 and less than 2.0 at a wavelength of 500 nm. Ａand a low refractive index layer L made of a low refractive index material having a refractive index relatively lower than that of the medium refractive index material and having a refractive index of 1.3 or more and 1.7 or less at a wavelength of 500 nm. Ａ and (H Ａ / M Ａ / L Ａ / M Ａ ) ｎ (n is a natural number of 2 or more) (wherein the medium refractive index layer M Ａ is the high refractive index layer H Ａ and the low refractive index layer L Ａ If it consists of, it is treated as an equivalent film.)

[0108] When the dielectric multilayer film 1 satisfies the characteristic (iiA-1), it is preferable in that a multilayer film capable of reflecting a wide range of light in the near-infrared region can be easily obtained. Furthermore, n is preferably a natural number of 2 or more, more preferably 3 or more, and even more preferably 4 or more, and the larger the number, the better. When n is within this range, the repeated stacked structure (H Ａ / M Ａ / L Ａ / M Ａ ) are appropriately present, and desired reflection characteristics can be obtained. Ａ / M Ａ / L Ａ / M Ａ ) may be consecutive or separate.

[0109] The total number of layers in the dielectric multilayer film 1 is preferably 20 or more, more preferably 30 or more, and even more preferably 35 or more. However, since a larger total number of layers may cause warping or an increase in film thickness, the total number of layers is preferably 100 or less, more preferably 75 or less, and even more preferably 60 or less.

[0110] The laminated film 2 consisting of the barrier film 2 and the dielectric multilayer film 2 is preferably designed so that the optical filter satisfies the spectral characteristics (i-7) and (i-8), i.e., when the light-absorbing layer side is the incident direction, the maximum reflectance for wavelengths of 450 to 750 nm is 20% or less at an incident angle of 60 degrees, and the maximum reflectance for wavelengths of 750 to 1200 nm is 42% or less at an incident angle of 60 degrees. The spectral characteristics (i-7) and (i-8) of the optical filter are substantially the reflection characteristics of the laminated film 2. In other words, it is preferable that the laminated film 2 has low reflection characteristics in the visible light region and near-infrared region.

[0111] The thickness (physical thickness) of the dielectric multilayer film 2 is preferably 100 nm or more, more preferably 150 nm or more, from the viewpoint of reducing the incidence angle dependency of the spectral characteristics and also providing a function of protecting the glass, and is preferably 10 μm or less from the viewpoints of productivity and suppressing reflection ripples in the visible light region. As described above, the dielectric multilayer film 2 also plays a role in protecting the glass together with the barrier film 2 and the light absorption layer. From these viewpoints, it is preferable that the dielectric multilayer film 2 be resistant to film peeling and be robust as a system.

[0112] The total number of layers in the dielectric multilayer film 2 is preferably 60 or less, more preferably 30 or less, and even more preferably 6 or less.

[0113] The filter may have at least one outermost surface, preferably on the surface of the light absorbing layer, a dielectric multilayer film 3. From the viewpoint of reducing ripples in the visible light region, the dielectric multilayer film 3 is preferably designed as a near-infrared anti-reflection film (NIR anti-reflection film), for example.

[0114] The total number of layers in the dielectric multilayer film 3 is preferably 60 or less, more preferably 30 or less, even more preferably 15 or less, and is preferably 8 or less. In order to suppress reflection in the visible wavelength range even when the angle of incidence changes, a film with low reflectivity over the entire wavelength range is preferred, rather than a film that reflects only specific wavelengths. The overall thickness (physical thickness) of the dielectric multilayer film 3 is preferably 200 to 1000 nm.

[0115] The dielectric multilayer film can be formed by, for example, a vacuum film-forming process such as CVD, sputtering, or vacuum deposition, or a wet film-forming process such as spraying or dipping.

[0116] <Light Absorption Layer> The optical filter according to this embodiment includes a light absorption layer provided on the dielectric multilayer film 2. The light absorption layer contains a near-infrared absorbing dye having a maximum absorption wavelength in the range of 680 to 800 nm, and can compensate for the wavelength range that is not blocked by the reflection characteristics of the dielectric multilayer film through absorption. From the viewpoint of being able to absorb a wide range of light in the near-infrared range and suppressing a decrease in visible light transmittance, it is preferable to combine two or more near-infrared absorbing dyes having different maximum absorption wavelengths in the range of 680 to 800 nm, and it is more preferable to combine one or more near-infrared absorbing dyes having a maximum absorption wavelength in the range of 700 to 740 nm with one or more near-infrared absorbing dyes having a maximum absorption wavelength in the range of 740 to 800 nm.

[0117] The near-infrared absorbing dye is preferably at least one selected from the group consisting of squarylium dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, dithiol metal complex dyes, azo dyes, polymethine dyes, phthalide dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, croconium dyes, tetradehydrocoline dyes, triphenylmethane dyes, aminium dyes, and diimmonium dyes.

[0118] The near-infrared absorbing dye preferably contains at least one dye selected from a squarylium dye, a phthalocyanine dye, and a cyanine dye. Among these dyes, squarylium dyes and cyanine dyes are preferred from the viewpoint of spectral properties, and phthalocyanine dyes are preferred from the viewpoint of durability.

[0119] The light-absorbing layer is preferably a resin film containing the dye and a resin. The content of the near-infrared absorbing dye in the light-absorbing layer is preferably 0.1 to 25 parts by mass, more preferably 0.3 to 15 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.

[0120] The light absorbing layer may contain other dyes in addition to the near-infrared absorbing dye. The other dyes are preferably dyes (UV dyes) that have a maximum absorption wavelength in the resin of 370 to 440 nm. This allows for efficient blocking of the near-ultraviolet light region.

[0121] Examples of UV 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.

[0122] The resin in the light-absorbing layer is not limited as long as it is a transparent resin, and one or more transparent resins selected from polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins are used. These resins may be used alone or in combination of two or more. From the viewpoints of the spectral characteristics, glass transition temperature (Tg), and adhesion of the light-absorbing layer, one or more resins selected from polyimide resins, polycarbonate resins, polyester resins, and acrylic resins are preferred.

[0123] When a plurality of compounds are used as the near-infrared absorbing dye or other dyes, they may be contained in the same light absorbing layer, or may be contained in separate light absorbing layers.

[0124] The light absorbing layer can be formed by preparing a coating liquid by dissolving or dispersing the dye, the resin or raw material components of the resin, and other components that are blended as necessary in a solvent, applying this onto the dielectric multilayer film 2, drying it, and further curing it as necessary. Alternatively, the coating liquid may be applied to a peelable support that is used only when forming the light absorbing layer, and the light absorbing layer may then be laminated on the dielectric multilayer film 2. The solvent may be any dispersion medium that allows stable dispersion or dissolution.

[0125] The coating liquid may also contain a surfactant to prevent voids caused by minute bubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For application of the coating liquid, methods such as dip coating, cast coating, and spin coating can be used. When the coating liquid contains raw materials for a transparent resin, it is further subjected to a curing treatment such as heat curing or photocuring.

[0126] The light absorbing layer can also be manufactured in the form of a film by extrusion molding. The obtained film-shaped absorbing layer can be laminated on the dielectric multilayer film 2 and integrated by thermocompression bonding or the like to manufacture the present filter.

[0127] The optical filter may have one light absorbing layer or two or more light absorbing layers. When two or more light absorbing layers are included, the layers may have the same or different configurations, and may be formed on each of the dielectric multilayer films, or two or more layers may be stacked on one of the dielectric multilayer films.

[0128] The thickness of the light-absorbing layer 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 expressing desired spectral characteristics at an appropriate dye concentration. When the optical filter has two or more light-absorbing layers, it is preferable that the total thickness of the light-absorbing layers is within the above range.

[0129] The optical filter according to this embodiment may also include, as other components, 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, lanthanum boride, and the like. 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.

[0130] <Imaging Device> An imaging device according to an embodiment of the present invention preferably includes the optical filter according to the embodiment of the present invention. The imaging device preferably further includes a solid-state imaging element and an imaging lens. The optical filter according to 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. By including this filter, which has excellent visible light transmittance, specific near-infrared light blocking properties, and is less likely to shift in its spectral curve even at high angles of incidence, an imaging device can be obtained that has excellent color reproducibility even for light at high angles of incidence.

[0131] When mounting an optical filter on an imaging device, it is usually preferable to place the dielectric multilayer film 1 on the lens side (external light incident side) and the dielectric multilayer film 2 on the sensor side.

[0132] As described above, this specification discloses the following optical filters, etc. [1] An optical filter comprising glass, a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the glass, a barrier film 1 provided between the glass and the dielectric multilayer film 1, a barrier film 2 provided between the glass and the dielectric multilayer film 2, and a light absorbing layer provided on the dielectric multilayer film 2, wherein the glass is a phosphate glass having near-infrared absorbing properties and containing substantially no fluorine atoms, or a fluorophosphate glass having near-infrared absorbing properties and containing fluorine atoms, the light absorbing layer contains a near-infrared absorbing dye having a maximum absorption wavelength in the range of 680 to 800 nm, and when the glass is the phosphate glass, the barrier film 1 and the barrier film 2 each independently contain TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ When the glass is the fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain one or more selected from TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ An optical filter comprising one or more selected from the group consisting of: (i) an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-6): (i-1) an average transmittance of wavelengths from 440 to 500 nm is 80% or more at an incident angle of 0 degrees and 70% or more at an incident angle of 60 degrees; (i-2) an average transmittance of wavelengths from 750 to 1000 nm is 1% or less at an incident angle of 0 degrees and 1% or less at an incident angle of 60 degrees; and (i-3) a wavelength IR10 at which the transmittance is 10% in the spectral transmittance curve at an incident angle of 0 degrees. （０ｄｅｇ）(i-6) When the dielectric multilayer film 1 side is the incident direction, the maximum reflectance of wavelengths of 850 to 1200 nm is 85% or more at an incident angle of 5 degrees. [2] The optical filter according to [1], wherein the optical filter satisfies the following spectral characteristics (i-4) and (i-5). (i-4) A wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm in the spectral transmittance curve at an incident angle of 0 degrees. （０ｄｅｇ） and the wavelength IR10 where the transmittance is 10% in the range of 600 to 700 nm in the spectral transmittance curve at an incident angle of 60 degrees. （６０ｄｅｇ）(i-5) The transmittance at a wavelength of 1100 nm is 1% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 60 degrees. [3] The optical filter according to [1] or [2], wherein the optical filter satisfies the following spectral characteristics (i-7) and (i-8): (i-7) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 750 nm is 20% or less at an incident angle of 60 degrees. (i-8) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 750 to 1200 nm is 42% or less at an incident angle of 60 degrees. [4] The optical filter according to any one of [1] to [3], wherein when a film consisting of the barrier film 2 and the dielectric multilayer film 2 is a laminate film 2, X represented by the following formula (1) is 35% or more. X (%) = {A / (B-C)} x 100 (1) Here, when each layer included in the laminate film 2 is evaluated by the QWOT represented by the following formula (2), A (nm) is the total thickness of layers in the laminate film 2 that have a QWOT of less than 2 and a refractive index of 1.9 or less, QWOT = (thickness of target layer (nm) / 550 (nm)) x 4 x (refractive index of target layer at a wavelength of 550 nm) (2) B (nm) is the total thickness of the laminate film 2, and C (nm) is the total thickness of layers in the laminate film 2 that have a QWOT of 2 or more. [5] An optical filter according to any one of [1] to [4], wherein the optical filter satisfies the following spectral characteristic (i-9): (i-9) When the light absorbing layer side is the incident direction, the maximum reflectance for wavelengths of 450 to 750 nm is 7.5% or less at an incident angle of 5 degrees. [6] The optical filter according to any one of [1] to [5], wherein the optical filter satisfies the following spectral characteristic (i-10): (i-10) When the dielectric multilayer film 1 side is the incident direction, the average reflectance for wavelengths of 800 to 1100 nm is 95% or more at an incident angle of 5 degrees. [7] The phosphate glass does not substantially contain fluorine atoms, and has a mol % content of P based on oxides. ２ O ５ 40%~75%, Al ２ O ３ 10% to 30%, ΣR ２ O 0.1% to 30% (However, R ２ O is Li ２ O, Na２ O.K. ２ O, Rb ２ O, and Cs ２ and one or more components selected from ΣR ２ O is R ２ The optical filter according to any one of [1] to [6], wherein the fluorophosphate glass contains, in mass %, P, ΣR'O 0% to 30% (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR'O represents the total content of R'O), and CuO 2% to 30%. [8] The optical filter according to any one of [1] to [6], wherein the fluorophosphate glass contains, in mass %, P ５＋ 20-70% Al ３＋ 1-20% Li ＋ 0-30% Na ＋ 0-40% K ＋ 0-40% Rb ＋ 0-20% Cs ＋ 0-20% Mg ２＋ 0-20% Ca ２＋ 0-20% Sr ２＋ 0-30% Ba ２＋ 0-40% ΣR ＋ 1 to 55% (R ＋ Li ＋ , Na ＋ , K. ＋ , Rb ＋ and Cs ＋ One or more components selected from ΣR ２＋ 1 to 50% (R ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ one or more components selected from the group consisting of: ２＋ 1-20% Zn ２＋ The glass contains 0 to 20% of F. － When the component elements other than F are taken as 100 mass%, －The optical filter according to any one of [1] to [6], wherein the glass has, in terms of a plate thickness of 0.2 mm, a transmittance of 80% or more at a wavelength of 420 nm, a transmittance of 6% or less at a wavelength of 800 nm, and a transmittance of 25% or less at a wavelength of 1200 nm.

[10] The optical filter according to any one of [1] to [9], wherein the dielectric multilayer film 1 satisfies the following characteristic (iiA-1): (iiA-1) A high refractive index layer H made of a high refractive index material having a refractive index of 1.8 or more and 3.0 or less at a wavelength of 500 nm. Ａ and a medium refractive index layer M made of a medium refractive index material having a refractive index relatively lower than that of the high refractive index material and having a refractive index of 1.5 or more and 2.0 or less at a wavelength of 500 nm. Ａ and a low refractive index layer L made of a low refractive index material having a refractive index relatively lower than that of the medium refractive index material and having a refractive index of 1.3 or more and 1.7 or less at a wavelength of 500 nm. Ａ and (H Ａ / M Ａ / L Ａ / M Ａ ) ｎ (n is a natural number of 2 or more) (wherein the medium refractive index layer M Ａ is the high refractive index layer H Ａ and the low refractive index layer L Ａ

[11] When the glass is the phosphate glass, the barrier film 1 and the barrier film 2 are treated as equivalent films. ２ When the glass is the fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain TiO ２ and Al ２ O ３

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

[11] , wherein the light absorbing layer comprises one or more near-infrared absorbing dyes having a maximum absorption wavelength of 700 nm or more and less than 740 nm, and one or more near-infrared absorbing dyes having a maximum absorption wavelength of 740 nm or more and 800 nm or less.

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

[12] .

[0133] Next, the present invention will be described in more detail with reference to examples. Each spectral characteristic was measured using an ultraviolet-visible spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation). Unless otherwise specified, the spectral characteristics are values ​​measured at an incident angle of 0 degrees (perpendicular to the main surface of the optical filter).

[0134] The dyes used in each example are as follows. Compound 1 (cyanine compound): Synthesized based on Dyes and Pigments 73 (2007) 344-352. Compound 2 (merocyanine compound): Synthesized based on German Patent Publication No. 10109243. Compound 3 (squarylium compound): Synthesized based on International Publication No. 2017 / 135359. Compound 4 (squarylium compound): Synthesized based on International Publication Nos. 2014 / 088063 and 2016 / 133099. Compound 5 (merocyanine compound): Synthesized based on German Patent Publication No. 10109243.

[0135]

[0136] Compounds 1, 3, and 4 are near-infrared absorbing dyes (NIR dyes), and compounds 2 and 5 are near-ultraviolet absorbing dyes (UV dyes). The maximum absorption wavelength of each dye is shown in Table 7 below.

[0137] <Spectral Properties of Glass> The following glasses were prepared. Phosphate glass or fluorophosphate glass was prepared by weighing and mixing raw materials to obtain the contents shown in Table 1 or Table 2, expressed in mol% or mass% based on oxides. The mixture was placed in a crucible with an internal volume of approximately 400 mL and melted for 2 hours under a reducing atmosphere. The mixture was then refined and stirred, and poured into a rectangular mold measuring 100 mm in length, 80 mm in width, and 20 mm in height that had been preheated to approximately 300°C to 500°C. The mixture was then slowly cooled at a rate of approximately 1°C / min to obtain a plate-shaped glass sample with both sides optically polished.

[0138] The spectral characteristics of each glass are shown in Tables 1 and 2. The spectral transmittance curves of each glass are shown in Figures 3 and 4, respectively.

[0139]

[0140]

[0141] As shown above, Glass 1, Glass 3, Glass 4 (phosphate glasses) and Glass 2 (fluorophosphate glass) all have excellent visible light transmittance and can absorb a wide range of near-infrared light from 800 to 1200 nm.

[0142] <Glass Reliability Test 1> A test piece measuring 5 mm in length, 5 mm in width, and 0.29 mm in thickness was prepared from the glass 1 manufactured above. A barrier film was formed by depositing the materials shown in Table 3 below by vapor deposition on both main surfaces. A high-temperature, high-humidity test was conducted on the barrier film-coated glass substrate under the following conditions. The barrier film-coated glass substrate was left in an environment of 85°C temperature and 85% relative humidity for the period shown in Table 3. The edge of the barrier film-coated glass substrate was then observed from the main surface side using a metallurgical microscope at 200x magnification to evaluate the degree of deterioration. The distance from the edge to the most deteriorated point was measured and evaluated based on the following criteria. A grade of B or higher was considered acceptable. A: Edge deterioration was less than 150 μm. B: Edge deterioration was 150 μm or more but less than 200 μm. C: Edge deterioration was 200 μm or more. The evaluation results are shown in Table 3 below. Examples 1-1 and 1-2 are reference examples, and Examples 1-3 to 1-5 are reference comparative examples.

[0143]

[0144] The above results show that for Glass 1 (phosphate glass), barrier films made of titania or tantalum are superior in durability, with titania being particularly preferable. On the other hand, the barrier films made of alumina, silica, and zirconia showed degradation of the end faces and did not achieve durability.

[0145] <Glass Reliability Test 2> A test piece of the glass 1 produced above, measuring 5 mm in length, 5 mm in width, and 0.29 mm in thickness, was prepared, and TiO ２ The barrier films were formed by laminating the above by vapor deposition. ２ and TiO ２These were alternately laminated by vapor deposition to form dielectric multilayer films A or B having the configurations shown in Table 5. Film number 1 is the layer in contact with the barrier film. The obtained test specimens were evaluated for the degree of deterioration of the end faces using the same method and criteria as in Glass Reliability Test 1. The evaluation results are shown in Table 4 below. Examples 1-6 to 1-7 are reference examples.

[0146]

[0147]

[0148] The results of Examples 1-6 to 1-7 above confirmed that the barrier film had good durability in all phosphate glasses. Furthermore, it was confirmed that Example 1-6, which had a larger total thickness of the barrier film and the dielectric multilayer film, had higher durability.

[0149] <Glass Reliability Test 3> A test piece of the glass 2 (fluorophosphate glass) manufactured above, measuring 5 mm in length, 5 mm in width, and 0.225 mm in thickness, was prepared, and TiO ２ or Al ２ O ３ The barrier films were formed by laminating the above by vapor deposition. ２ and TiO ２ These were alternately laminated by vapor deposition to form dielectric multilayer films A or B having the configuration shown in Table 6. Film number 1 is the layer in contact with the barrier film. A high-temperature, high-humidity test was performed on the obtained test specimens under the following conditions. The barrier film-coated glass substrates were left in an environment of 85°C temperature and 85% relative humidity for the time shown in Table 3, and then the edge faces were observed from the main surface side using a metallurgical microscope at 200x magnification to evaluate the degree of deterioration. The distance from the edge face to the most deteriorated point was measured and evaluated based on the following criteria. A grade of C or higher was considered acceptable. A: Edge face deterioration was less than 100 μm. B: Edge face deterioration was 100 μm or more but less than 150 μm. C: Edge face deterioration was 150 μm or more but less than 250 μm. D: Edge face deterioration was 250 μm or more. The evaluation results are shown in Table 6 below. Examples 1-8 to 1-9 are reference examples, and Example 1-10 is a reference comparative example.

[0150]

[0151] From the results of Examples 1-8 to 1-9, TiO ２ or Al ２ O ３ The durability of the fluorophosphate glass was confirmed using any of the barrier films. ２ It was found that Example 1-8 using the above was more preferable.

[0152] <Spectral Characteristics of Light-Absorbing Layer> The dyes of Compounds 1 to 5 were dissolved in polyimide resin C-3G30G manufactured by Mitsubishi Gas Chemical Company, Inc., and mixed at the concentrations shown in Table 7 below. The mixture was stirred and dissolved at 50°C for 2 hours to obtain a coating liquid. The obtained coating liquid was applied to alkali glass (D263 glass manufactured by SCHOTT, thickness 0.2 mm) by spin coating to form light-absorbing layers 1 and 2 with a film thickness of 1 μm. The spectral transmittance curves and spectral reflectance curves of the obtained light-absorbing layers 1 and 2 in the wavelength range of 350 to 1200 nm were measured using a UV-visible spectrophotometer. The results are shown in Table 7 below. The spectral transmittance curve of the light-absorbing layer is also shown in FIG. 5.

[0153]

[0154] Example 2-1: Spectral characteristics of optical filter On both main surfaces of Glass 1 (phosphate glass), TiO ２ The barrier film 1 and the barrier film 2 were formed by depositing the SiO ２ and TiO ２ By alternately laminating these layers by vapor deposition, a dielectric multilayer film 1A having the configuration shown in Table 8 was formed. ２ and TiO ２ By alternately laminating these layers by vapor deposition, a dielectric multilayer film 2A having the configuration shown in Table 11 was formed. A resin solution having the same composition as the light absorbing layer 1 was applied to the surface of the barrier film 2, and the solution was heated sufficiently to remove the organic solvent, thereby forming a light absorbing layer 1 having a thickness of 1 μm. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 3A (anti-reflection film) having the configuration shown in Table 13. In this way, an optical filter 2-1 was manufactured.

[0155] <Example 2-2> An optical filter 2-2 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2B having the configuration shown in Table 11 was formed instead of the dielectric multilayer film 2A, and the thickness of the barrier film 2 was changed to the value shown in Table 14.

[0156] Example 2-3: Glass 2 (fluorophosphate glass) was coated on both main surfaces with Al having the same composition as in Example 1-9. ２ O ３ The barrier film 1 and the barrier film 2 were formed by depositing the SiO ２ and TiO ２ By alternately laminating these layers by vapor deposition, a dielectric multilayer film 1B having the structure shown in Table 8 was formed. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 2C having the configuration shown in Table 11. A resin solution having the same composition as the light absorbing layer 1 was applied to the surface of the barrier film 2-2, and the solution was heated sufficiently to remove the organic solvent, thereby forming a light absorbing layer having a thickness of 1 μm. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 3A (anti-reflection film) having the configuration shown in Table 13. In this way, an optical filter 2-3 was manufactured.

[0157] Example 2-4 An optical filter 2-4 was produced in the same manner as in Example 2-1, except that a dielectric multilayer film 1C having the configuration shown in Table 9 was formed instead of the dielectric multilayer film 1A.

[0158] Example 2-5 An optical filter 2-5 was produced in the same manner as in Example 2-3, except that a dielectric multilayer film 1D having the configuration shown in Table 10 was formed instead of the dielectric multilayer film 1B.

[0159] <Example 2-6> An optical filter 2-6 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2D having the configuration shown in Table 11 was formed instead of the dielectric multilayer film 2A, and the thickness of the barrier film 2 was changed to the value shown in Table 15.

[0160] <Example 2-7> An optical filter 2-7 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2E having the configuration shown in Table 12 was formed instead of the dielectric multilayer film 2A, and the thickness of the barrier film 2 was changed to the value shown in Table 15.

[0161] <Example 2-8> An optical filter 2-8 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2F having the configuration shown in Table 12 was formed instead of the dielectric multilayer film 2A, and the thickness of the barrier film 2 was changed to the value shown in Table 15.

[0162] Example 2-9: Both main surfaces of glass 1 (phosphate glass) were coated with Al having the same composition as in Example 1-9. ２ O ３ The barrier film 1 and the barrier film 2 were formed by depositing the SiO ２ and TiO ２ By alternately laminating these layers by vapor deposition, a dielectric multilayer film 1B having the structure shown in Table 8 was formed. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 2G having the configuration shown in Table 12. A resin solution having the same composition as the light absorbing layer 1 was applied to the surface of the barrier film 2, and the solution was heated sufficiently to remove the organic solvent, thereby forming a light absorbing layer having a thickness of 1 μm. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 3A (anti-reflection film) having the configuration shown in Table 13. In this way, an optical filter 2-9 was manufactured.

[0163] Example 2-10: Glass 3 (phosphate glass) was coated on both main surfaces with TiO ２ The barrier film 1 and the barrier film 2 were formed by depositing the SiO ２ and TiO ２ By alternately laminating these layers by vapor deposition, a dielectric multilayer film 1E having the configuration shown in Table 10 was formed. ２ and TiO ２These were alternately laminated by vapor deposition to form a dielectric multilayer film 2H having the configuration shown in Table 12. A resin solution having the composition of the light absorbing layer 2 was applied to the surface of the barrier film 2, and the solution was heated sufficiently to remove the organic solvent, thereby forming a light absorbing layer having a thickness of 1 μm. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 3B (antireflection film) having the configuration shown in Table 13. In this way, an optical filter 2-10 was manufactured.

[0164] Example 2-11 An optical filter 2-11 was produced in the same manner as in Example 2-10, except that Glass 3 was changed to Glass 4 shown in Table 1.

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171] For each of the optical filters obtained above, a UV-visible spectrophotometer was used to measure the spectral transmittance curves at incident angles of 0 degrees and 60 degrees in the wavelength range of 350 to 1200 nm, and the spectral reflectance curves at incident angles of 5 degrees and 60 degrees. Furthermore, for the optical filters of Examples 2-10 and 2-11, the degree of deterioration of the end faces was evaluated using the same method and criteria as in Glass Reliability Test 1. From the obtained data on spectral characteristics, the various characteristics shown in Tables 14 to 16 below were calculated.

[0172] The method of calculating X in the laminated film 2 will be specifically shown by taking the laminated film 2 consisting of the dielectric multilayer film 2A and the barrier film 2 as an example. ２ The refractive index of TiO is 1.9 or less. ２ The total thickness A (nm) of the dielectric layers included in the laminated film 2, which have a QWOT of less than 2 and a refractive index of 1.9 or less, is SiO２ Physical thickness of the film and SiO ２ The total thickness B (nm) of the laminated film 2 can be calculated from the sum of the physical thickness of the entire dielectric multilayer film 2A and the physical thickness of the barrier film 2. The total thickness C (nm) of the layers in the laminated film 2 that have a QWOT of 2 or more can be calculated from the sum of the physical thickness of the SiO ２ The physical thickness of the film corresponds to this. From the above, X was calculated.

[0173] The spectral transmittance curve and the spectral reflectance curve of the optical filter of Example 2-1 are shown in Fig. 6. The spectral transmittance curve and the spectral reflectance curve of the optical filter of Example 2-3 are shown in Fig. 7.

[0174] Examples 2-1 to 2-11 are examples of the present invention.

[0175]

[0176]

[0177]

[0178] The above results demonstrate that the optical filters of Examples 2-1 to 2-11 exhibit excellent transmittance in the visible light region and excellent shielding properties in the near-infrared region, even at high angles of incidence. Furthermore, the optical filters of Examples 2-1 to 2-6 maintain low reflectance on the light absorption layer side, even at high angles of incidence. This is due to the use of a stacked film 2 (dielectric multilayer film 2 + barrier film 2) with an X of 35% or more. Furthermore, the optical filters of Examples 2-4 and 2-5 were able to reflect a wide range of light in the near-infrared region from 800 to 1100 nm. This is due to the use of a dielectric multilayer film 1C or 1D, which has high light-shielding properties in the near-infrared region. Furthermore, the results of reliability tests on the optical filters of Examples 2-10 and 2-11 confirmed durability even when the total thickness of the stacked film 2 (multilayer film 2 + barrier film 2) was 200 nm or less.

[0179] 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. 2023-135695) filed on August 23, 2023, the contents of which are incorporated herein by reference.

[0180] The optical filter of the present invention has excellent visible light transmittance and near-infrared light blocking properties, and is useful for applications in information acquisition devices such as cameras and sensors for transport aircraft, which have become increasingly sophisticated in recent years.

[0181] 1A, 1B Optical filter 10 Glass 11, 12 Barrier film 21, 22, 23 Dielectric multilayer film 30 Light absorption layer

Claims

1. An optical filter comprising glass, a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the glass, a barrier film 1 provided between the glass and the dielectric multilayer film 1, a barrier film 2 provided between the glass and the dielectric multilayer film 2, and a light absorbing layer provided on the dielectric multilayer film 2, wherein the glass is a phosphate glass having near-infrared absorbing properties and containing substantially no fluorine atoms, or a fluorophosphate glass having near-infrared absorbing properties and containing fluorine atoms, the light absorbing layer contains a near-infrared absorbing dye having a maximum absorption wavelength in the range of 680 to 800 nm, and when the glass is the phosphate glass, the barrier film 1 and the barrier film 2 are each independently composed of TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ When the glass is a fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain one or more selected from the group consisting of TiO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ An optical filter comprising one or more selected from the following, which satisfies all of the following spectral characteristics (i-1) to (i-3) and (i-6): (i-1) the average transmittance of wavelengths from 440 to 500 nm is 80% or more at an incident angle of 0 degrees and 70% or more at an incident angle of 60 degrees, (i-2) the average transmittance of wavelengths from 750 to 1000 nm is 1% or less at an incident angle of 0 degrees and 1% or less at an incident angle of 60 degrees, and (i-3) the wavelength IR10 at which the transmittance is 10% in the spectral transmittance curve at an incident angle of 0 degrees. （０ｄｅｇ） is in the range of 600 to 700 nm. (i-6) When the dielectric multilayer film 1 side is the incident direction, the maximum reflectance of the wavelength of 850 to 1200 nm is 85% or more at an incident angle of 5 degrees.

2. The optical filter according to claim 1, wherein the optical filter satisfies the following spectral characteristics (i-4) and (i-5): (i-4) A wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm in a spectral transmittance curve at an incident angle of 0 degrees. （０ｄｅｇ） and the wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm in the spectral transmittance curve at an incident angle of 60 degrees. （６０ｄｅｇ） (i-5) The transmittance at a wavelength of 1100 nm is 1% or less at an incident angle of 0 degrees and 3% or less at an incident angle of 60 degrees.

3. The optical filter according to claim 1, wherein the optical filter satisfies the following spectral characteristics (i-7) and (i-8): (i-7) When the light absorbing layer side is the incident direction, the maximum reflectance of wavelengths from 450 to 750 nm is 20% or less at an incident angle of 60 degrees; (i-8) When the light absorbing layer side is the incident direction, the maximum reflectance of wavelengths from 750 to 1200 nm is 42% or less at an incident angle of 60 degrees.

4. The optical filter according to claim 1, wherein, when a film consisting of the barrier film 2 and the dielectric multilayer film 2 is taken as a laminate film 2, X represented by the following formula (1) is 35% or more: X (%) = {A / (B-C)} x 100 (1) Here, when each layer included in the laminate film 2 is evaluated by the QWOT represented by the following formula (2), A (nm) is the total thickness of layers in the laminate film 2 having a QWOT of less than 2 and a refractive index of 1.9 or less, QWOT = (thickness of the target layer (nm) / 550 (nm)) x 4 x (refractive index of the target layer at a wavelength of 550 nm) (2) B (nm) is the total thickness of the laminate film 2, and C (nm) is the total thickness of layers in the laminate film 2 having a QWOT of 2 or more.

5. The optical filter according to claim 1, which satisfies the following spectral characteristic (i-9): (i-9) When the light absorbing layer side is the incident direction, the maximum reflectance of the wavelength of 450 to 750 nm is 7.5% or less at an incident angle of 5 degrees.

6. The optical filter according to claim 1, which satisfies the following spectral characteristic (i-10): (i-10) When the dielectric multilayer film 1 side is the incident direction, the average reflectance of wavelengths from 800 to 1100 nm is 95% or more at an incident angle of 5 degrees.

7. The phosphate glass is substantially free of fluorine atoms and contains, in mole percent on an oxide basis, P ２ O ５ 40%~75%, Al ２ O ３ 10% to 30%, ΣR ２ O 0.1% to 30% (R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ O, ΣR ２ O is R ２ 2. The optical filter according to claim 1, comprising: ΣR'O 0% to 30% (wherein R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR'O represents the total content of R'O); and CuO 2% to 30%.

8. The fluorophosphate glass contains, in mass %, ５＋ 20-70% Al ３＋ 1-20% Li ＋ 0-30% Na ＋ 0-40% K ＋ 0-40% Rb ＋ 0-20% Cs ＋ 0-20% Mg ２＋ 0-20% Ca ２＋ 0-20% Sr ２＋ 0-30% Ba ２＋ 0-40% ΣR ＋ 1 to 55% (R ＋ Li ＋ , Na ＋ , K ＋ , Rb ＋ and Cs ＋ One or more components selected from the following: ΣR ２＋ 1 to 50% (R ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ one or more components selected from the group consisting of: ２＋ 1-20% Zn ２＋ The glass contains 0 to 20% F. － When the component elements other than F are taken as 100 mass%, － The optical filter according to claim 1, wherein the content is 3 to 60 mass %.

9. An optical filter according to claim 1, wherein the glass has, in terms of a plate thickness of 0.2 mm, a transmittance of 80% or more at a wavelength of 420 nm, a transmittance of 6% or less at a wavelength of 800 nm, and a transmittance of 25% or less at a wavelength of 1200 nm.

10. The optical filter according to claim 1, wherein the dielectric multilayer film 1 satisfies the following characteristic (iiA-1): (iiA-1) A high refractive index layer H made of a high refractive index material having a refractive index of 1.8 to 3.0 at a wavelength of 500 nm. Ａ and a medium refractive index layer M made of a medium refractive index material having a refractive index relatively lower than that of the high refractive index material and a refractive index at a wavelength of 500 nm of 1.5 or more and 2.0 or less. Ａ and a low refractive index layer L made of a low refractive index material having a refractive index relatively lower than that of the medium refractive index material and a refractive index at a wavelength of 500 nm of 1.3 or more and 1.7 or less. Ａ (H Ａ / M Ａ / L Ａ / M Ａ ) ｎ (n is a natural number of 2 or more) (wherein the medium refractive index layer M Ａ is the high refractive index layer H Ａ and a low refractive index layer L Ａ If it consists of, it is treated as an equivalent film.) 11. When the glass is the phosphate glass, the barrier film 1 and the barrier film 2 are TiO ２ When the glass is a fluorophosphate glass, the barrier film 1 and the barrier film 2 each independently contain TiO ２ and Al ２ O ３ The optical filter of claim 1 , comprising at least one of:

12. The optical filter according to claim 1, wherein the light absorbing layer contains one or more near-infrared absorbing dyes having a maximum absorption wavelength in the range of 700 nm or more and less than 740 nm, and one or more near-infrared absorbing dyes having a maximum absorption wavelength in the range of 740 nm or more and 800 nm or less.

13. An imaging device comprising an optical filter according to any one of claims 1 to 12.