Optical filter

Abstract

The present invention pertains to an optical filter provided with: a phosphate glass; a dielectric multilayer film 1 and a dielectric multilayer film 2 which are provided on the opposing surfaces of the phosphate glass; a barrier film 1 provided between the phosphate glass and the dielectric multilayer film 1; a barrier film 2 provided between the phosphate glass and the dielectric multilayer film 2; and a light absorption layer provided on the dielectric multilayer film 2. The barrier film 1 and the barrier film 2 each independently contain at least one selected from TiO2, Nb2O5, Ta2O5, and HfO2. The optical filter satisfies all of specific spectral characteristics (i-1) to (i-5).

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 is known as a type of glass that absorbs light, but it is susceptible to the effects of moisture in the environment, and phosphoric acid may leach out and decompose other constituent materials of the optical filter. Therefore, technologies to prevent the leaching of phosphoric acid 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, as camera modules have become thinner in recent years, they are expected to be used under conditions of high angles of incidence, and therefore optical filters that are less susceptible to the effects of angles 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 phosphate glass, a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the phosphate glass, a barrier film 1 provided between the phosphate glass and the dielectric multilayer film 1, a barrier film 2 provided between the phosphate glass and the dielectric multilayer film 2, and a light absorbing layer provided on the dielectric multilayer film 2, wherein the light absorbing layer contains a near-infrared absorbing dye, and the barrier films 1 and 2 each independently contain TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２An 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-5): (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 0.5% or less at an incident angle of 0 degrees and 0.5% 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-4) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm （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) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 950 nm is 24% or less at an incident angle of 5 degrees and 35% or less at an incident angle of 60 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 illustrating an example of an optical filter according to an embodiment. FIG. 2 is a cross-sectional view schematically illustrating another example of an optical filter according to an embodiment. FIG. 3 is a diagram illustrating the spectral transmittance curves of glasses 1 to 5. FIG. 4 is a diagram illustrating the spectral transmittance curve of a light absorbing layer. FIG. 5 is a diagram illustrating the spectral reflectance curve of a laminate film 1 including a dielectric multilayer film 1A and a barrier film 1. FIG. 6 is a diagram illustrating the spectral reflectance curve of a laminate film 1 including a dielectric multilayer film 1C and a barrier film 1. FIG. 7 is a diagram illustrating the spectral transmittance curve of an optical filter according to Example 2-1. FIG. 8 is a diagram illustrating the spectral reflectance curve of the dielectric multilayer film 1 side of the optical filter according to Example 2-1. FIG. 9 is a diagram illustrating the spectral reflectance curve of the light absorbing layer side of the optical filter according to Example 2-1. FIG. 10 is a diagram illustrating the spectral transmittance curve of an optical filter according to Example 2-7. FIG. 11 is a diagram illustrating the spectral reflectance curve of the dielectric multilayer film 1 side of the optical filter according to Example 2-7. FIG. 12 is a diagram illustrating the spectral reflectance curve of the light absorbing layer side of the optical filter according to Example 2-7.

[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 transmittance of a light-absorbing layer including a case where 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 of an optical filter having a dielectric multilayer film are actually measured transmittances.

[0014] In this specification, a transmittance of, for example, 90% or more in a specific wavelength range means that the transmittance does not fall below 90% across the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, a transmittance of, for example, 1% or less in a specific wavelength range means that the transmittance does not exceed 1% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The average transmittance in a specific wavelength range is the arithmetic mean of the transmittance per 1 nm in that wavelength range. Spectral characteristics can be measured using a UV-visible 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 "this filter") comprises phosphate glass, dielectric multilayer film 1 and dielectric multilayer film 2 provided on both sides of the phosphate glass, and a light absorbing layer provided on dielectric multilayer film 2. This filter further comprises barrier film 1 between the phosphate glass and dielectric multilayer film 1, and barrier film 2 between the phosphate glass and dielectric multilayer film 2. Barrier films 1 and 2 contain specific materials, as described below. Such barrier films prevent the phosphate 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 Figure 1 is an example that includes phosphate glass 10, a dielectric multilayer film 21 provided on one main surface of the phosphate glass 10, a dielectric multilayer film 22 provided on the other main surface of the phosphate glass 10, a light absorbing layer 30 provided on the dielectric multilayer film 22, a barrier film 11 provided between the phosphate glass 10 and the dielectric multilayer film 21, and a barrier film 12 provided between the phosphate 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 light absorption 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-5): (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 0.5% or less at an incident angle of 0 degrees and 0.5% 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-4) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm （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) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 950 nm is 24% or less at an incident angle of 5 degrees and 35% or less at an incident angle of 60 degrees.

[0020] This filter, which satisfies all of the spectral characteristics (i-1) to (i-5), is an optical filter that has excellent visible light transmittance as shown in characteristic (i-1) and excellent near-infrared light blocking as shown in characteristic (i-2), is resistant to transmittance shift even at high angles of incidence as shown in characteristic (i-4), and has reduced reflectance in the wavelength range of 450 to 950 nm as shown in characteristic (i-5).

[0021] 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 82% or more, more preferably 85% or more, at an incident angle of 0 degrees, and preferably 72% or more, more preferably 75% 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, phosphate glass, or near-infrared light absorbing dye, which has excellent transmittance in the visible light region, may be used.

[0022] 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 high angles of incidence. The average transmittance for wavelengths of 750 to 1000 nm is preferably 0.4% or less, more preferably 0.2% or less, at an angle of incidence of 0 degrees, and preferably 0.4% or less, more preferably 0.2% or less, at an angle of incidence of 60 degrees. In addition, in order to satisfy the spectral characteristic (i-2), for example, light shielding can be achieved by the absorption ability of phosphate glass or a near-infrared light-absorbing dye.

[0023] 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 630 to 700 nm, more preferably in the range of 650 to 700 nm.

[0024] 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 13 nm or less, and more preferably 12 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 can be shielded by phosphate glass or the absorption ability of a near-infrared light absorbing dye, which is not affected by the angle of incidence.

[0025] Satisfying the spectral characteristic (i-5) means that the reflection characteristic at wavelengths of 450 to 950 nm is suppressed in the incident direction on the light absorbing layer side. This is preferable because, for example, when reflected light from the sensor side is incident on the optical filter, reflection can be suppressed on the optical filter side, thereby preventing unnecessary light from entering the sensor. The maximum reflectance at wavelengths of 450 to 950 nm is preferably 20% or less, more preferably 10% or less, at an incident angle of 5 degrees, and preferably 30% or less, more preferably 25% or less, at an incident angle of 60 degrees. To satisfy the spectral characteristic (i-5), for example, an anti-reflection film may be laminated on the light absorbing layer side.

[0026] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-6). (i-6) When the dielectric multilayer film 1 side is the incident direction, the maximum reflectance at wavelengths of 750 to 950 nm is 20% or more at an incident angle of 5 degrees, and 30% or more at an incident angle of 60 degrees. Satisfying the spectral characteristic (i-6) means that the reflectance of near-infrared light at wavelengths of 750 to 950 nm is high. The maximum reflectance at wavelengths of 750 to 950 nm is more preferably 50% or more, more preferably 70% or more at an incident angle of 5 degrees, and more preferably 50% or more, more preferably 70% or more at an incident angle of 60 degrees. In order to satisfy the spectral characteristic (i-6), for example, a dielectric multilayer film 1 having a high reflectance at wavelengths of 750 to 950 nm can be used.

[0027] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-7): (i-7) The absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 60 degrees, for wavelengths of 440 to 500 nm, is 15% or less. Satisfying the spectral characteristic (i-7) means that the change in transmittance (ripple) of visible light is small even at high incident angles. The above absolute value is more preferably 12% or less. In order to satisfy the spectral characteristic (i-7), it is possible to use a dielectric multilayer film that has a small change in transmittance (ripple) of visible light even at high incident angles.

[0028] The optical filter according to this embodiment preferably satisfies the following spectral characteristic (i-8). (i-8) Average transmittance for wavelengths of 900 to 1000 nm is 1% or less at an incident angle of 0 degrees. Satisfying the spectral characteristic (i-8) means that the filter has excellent shielding properties for near-infrared light with wavelengths of 900 to 1000 nm. The average transmittance for wavelengths of 900 to 1000 nm is more preferably 0.1% or less, and even more preferably 0.01% or less, at an incident angle of 0 degrees. In order to satisfy the spectral characteristic (i-8), for example, the absorption ability of the phosphate glass and the reflection characteristics of the dielectric multilayer film can be combined to shield the relevant region.

[0029] <Phosphate Glass> The optical filter according to this embodiment includes phosphate glass. In this specification, phosphate glass is defined as a glass containing phosphate in mole percent (mol%) based on oxides. ２ O ５ The term "glass containing 40% or more of fluorine atoms" refers to glass that is substantially free of fluorine atoms. Here, "substantially free of fluorine atoms" means that, when the content of component elements other than fluorine atoms contained in the glass is taken as 100% by mass and the content of fluorine atoms contained in the glass is expressed as an exclusive percentage, the content of fluorine atoms is less than 3% by mass. Phosphate glass absorbs near-infrared light and also functions as a support for optical filters. Furthermore, because it blocks light due to its absorption properties, its light-blocking properties are less susceptible to the influence of the angle of incidence, unlike dielectric multilayer films.

[0030] The phosphate glass preferably has an average transmittance of 70% or more at wavelengths of 440 to 500 nm, 20% or less at wavelengths of 1200 nm, 7% or less at wavelengths of 1000 nm, and 7% or less at wavelengths of 800 nm, calculated based on a plate thickness of 0.29 mm. Phosphate glass that satisfies these spectral characteristics is preferable because it has sufficient transmittance for visible light and excellent near-infrared light absorption. The average transmittance for wavelengths of 440 to 500 nm is more preferably 75% or more, and even more preferably 80% or more. The transmittance for a wavelength of 1200 nm is more preferably 17% or less, even more preferably 15% or less, and even more preferably 10% or less. The transmittance for a wavelength of 1000 nm is more preferably 6% or less, even more preferably 5% or less, and even more preferably 3% or less. The transmittance for a wavelength of 800 nm is more preferably 6% or less, and even more preferably 4% or less.

[0031] The phosphate glass contains substantially no fluorine atoms and contains, in mole percent on an oxide basis, 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, 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 and 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%.

[0032] The components that can constitute phosphate glass and their suitable contents are described below. In this specification, unless otherwise specified, the content of each component and the total content are expressed in mole percent based on the oxide.

[0033] 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 40 to 75%, more preferably 45 to 73%, even more preferably 47 to 71%, still more preferably 50 to 69%, and most preferably 55 to 67%.

[0034] Al ２ O ３ is the main component that forms glass and is a component that increases the strength of the 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 29%, even more preferably 12 to 28%, still more preferably 13 to 27%, and most preferably 14 to 26%. ２ O ３ If the content is 14% or more, the weather resistance of the glass can be improved.

[0035] R ２ O (However, R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ O) 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 ２If 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, the O content is preferably 0.1 to 30%, more preferably 0.4 to 27%, even more preferably 0.7 to 24%, still more preferably 1.0 to 21%, and most preferably 1.3 to 18%.

[0036] 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 glass instability and a decrease in near-infrared blocking properties are unlikely to occur, which is preferable. The O content 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.

[0037] 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 20%. ２ If the O content is 20% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 17%, even more preferably 1 to 14%, and even more preferably 1.5 to 11%.

[0038] 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 20%. ２ If the O content is 20% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 1 to 18%, even more preferably 2 to 15%, and even more preferably 3 to 13%.

[0039] 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 20%. ２ If the O content is 20% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 18%, even more preferably 1 to 16%, and even more preferably 2 to 14%.

[0040] 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 20%. ２ If the O content is 20% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 18%, even more preferably 1 to 16%, and even more preferably 2 to 14%.

[0041] 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, Rb ２ O, and Cs ２ The total amount (ΣR ２ O) is preferably 12 to 25%. ２If the total amount of O is 12% or more, the effect can be sufficiently obtained, and if it is 25% 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 12 to 25%, more preferably 13 to 24%, even more preferably 14 to 25%, even more preferably 15 to 26%, and most preferably 16 to 24%.

[0042] 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%.

[0043] The glass of this embodiment preferably does not substantially contain divalent cations other than Cu. The reason for this is as follows. When the 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 range and reduced transmittance in the short-wavelength infrared range are unlikely to occur. It is more preferably 4 to 25%, even more preferably 5 to 19%, and even more preferably 6 to 20%. Furthermore, it is even more preferably 8% or more. In particular, when the glass contains substantially no divalent cations other than Cu, a CuO content of 8% or more can further enhance the near-infrared blocking properties and the short-wavelength infrared transmittance. It is more preferably 10 to 18%, and most preferably 11 to 18%.

[0050] Fe ２ O ３ is a component for blocking near-infrared rays. ２ O ３ The content of Fe is preferably 0.1% or more and 35% or less. ２ O ３ If the content is 0.1% or more, the near-infrared blocking effect can be obtained sufficiently, and２ O ３ When the content of Fe is 35% or less, the transmittance of light in the visible region is less likely to decrease, which is preferable. ２ O ３ The content is more preferably 1 to 35%, even more preferably 2% to 35%, even more preferably 3% to 35%, particularly preferably 4% to 35%, particularly more preferably 5% to 35%, and most preferably 6% to 35%.

[0051] B ２ O ３ may be contained in an amount of 15% or less to stabilize the glass. ２ O ３ If 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 more preferably 13% or less, even more preferably 11% or less, still more preferably 9% or less, particularly preferably 7% or less, and most preferably B ２ O ３ It is substantially free of

[0052] In the glass of this embodiment, F (fluorine atom) 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. Here, "substantially not containing F" 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 %.

[0053] In the 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 ２O ５ may 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.

[0054] The thickness of the phosphate 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 0.1 mm or more from the viewpoint of element strength and the need to obtain desired optical characteristics.

[0055] <Barrier Film> The optical filter according to this embodiment has barrier films 1 and 2 on both main surfaces of the phosphate glass. These barrier films are each independently made of TiO ２ , 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 , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ Both of these have high resistance to moisture, and the presence of a barrier film having such a configuration between the phosphate glass and the dielectric multilayer film can prevent the phosphate glass from being eluted due to the influence of moisture. Also, from the viewpoint of excellent adhesion to the phosphate glass, it is preferable that the barrier film satisfy such a configuration.

[0056] For example, resin materials are not preferable as materials for the first barrier layer 120 and the second barrier layer 130 because they have a lower ability to prevent moisture penetration than inorganic materials.

[0057] 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 barrier film may contain 80 mol % or more of one or more materials selected from the group consisting of TiO and TiO 2 , or may contain 80 mol % or more of two or more materials in total, as long as the resistance to moisture is not impaired. ２ , 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 ２ and Al ２ O ３ It may contain TiO ２ , Nb ２ O ５ , Ta ２ O ５ , and HfO ２ When materials other than these are contained, the total content is preferably 20 mol% or less. On the other hand, materials containing Si may reduce adhesion to the glass substrate, so from this viewpoint, it is preferable not to contain them. Furthermore, from the viewpoint of improving the water resistance of the optical filter, it is preferable not to contain materials other than oxides of metals such as aluminum (Al), titanium (Ti), niobium (Nb), tantalum (Ta), and hafnium (Hf).

[0058] Furthermore, the barrier film 2 and the dielectric multilayer film 2 positioned in the direction of incidence of external light satisfy a specific condition for their physical thickness. That is, when a film consisting of the barrier film 2 and the dielectric multilayer film 2 is defined as a laminate film 2, it is preferable that X, defined by the following formula, is 35% or more. When the film (laminated film 2) consisting of the dielectric multilayer film 2 and the barrier film 2 present between the phosphate glass and the light absorbing layer satisfies the specific condition for the physical thickness, this is preferable because it further enhances the moisture resistance of the optical filter and avoids the effects of interface reflection caused by the provision of the barrier film 2.

[0059]

[0060] Here, QWOT (Quarter Wave Optical Thickness) is the optical thickness at a wavelength of λ / 4, and is calculated by the following formula: QWOT=(physical thickness nm / 550 nm)×4×(refractive index at 550 nm).

[0061] Controlling X can suppress the reflection behavior caused by the provision of a barrier film, making it possible to obtain an optical filter with better spectral characteristics. If X is 35% or more, for example, the maximum reflectance for wavelengths of 450 to 950 nm when the incident direction is the light-absorbing layer side, as shown in the spectral characteristics (i-5) of the optical filter, tends to fall within the desired range, which is preferable. As described above, suppressing the maximum reflectance when the incident direction is the light-absorbing layer side can 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.

[0062] The total physical film thickness of the laminated 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 physical film thickness of the laminated film 2 having a thickness of QWOT2 or more is determined by adding together the physical film thicknesses of the barrier film 2 and the films having a thickness of QWOT2 or more contained in the dielectric multilayer film 2. The total physical film thickness of the laminated film 2 having a thickness of less than QWOT2 and a refractive index of 1.9 or less is determined by adding together the physical film thicknesses of the barrier film 2 and the films having a refractive index of less than QWOT2 and a refractive index of 1.9 or less contained in the dielectric multilayer film 2.

[0063] In addition, the laminated film 2 is SiO ２ In the case where the laminated film 2 has a layer made of the above, X' defined by the following formula is preferably 35% or more, more preferably 50% or more, and even more preferably 70% or more, from the viewpoint of suppressing the reflectance on the light absorbing layer side. X' (%) = {SiO ２ Total thickness of layers / (total physical thickness of stacked film 2−SiO 2 having a thickness greater than 180 nm ２ (total thickness of layers) × 100

[0064] 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.

[0065] The total physical film thickness of the barrier film 1 and the dielectric multilayer film 1 is preferably 1.5 μm or more, more preferably 2.0 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 1.5 μm or more, more preferably 2.0 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.

[0066] 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.

[0067] <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. Although details will be described later, when a film made up of the barrier film 1 and the dielectric multilayer film 1 is used as a laminated film 1, the laminated film 1 is preferably designed as a reflective film that reflects part of near-infrared light (hereinafter also referred to as an "NIR reflective film").

[0068] The NIR reflective film preferably has wavelength selectivity that transmits visible light and primarily reflects near-infrared light. Specifically, it is preferably configured to have a wavelength band with a width of 100 nm or more in which the reflectance at an incident angle of 5 degrees is 80% or more for light with a wavelength between 750 nm and 1200 nm. The NIR reflective film may also be appropriately designed to reflect light in wavelength ranges other than near-infrared light, for example, near-ultraviolet light.

[0069] 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.

[0070] The high refractive index material preferably has a refractive index of 1.9 or more and 3.0 or less, more preferably 1.9 or more and 2.8 or less, and even more preferably 1.9 or more and 2.6 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 ２ Among these, TiO is preferred in terms of film-forming property, reproducibility in refractive index, stability, etc. ２ is preferred.

[0071] 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 1.9 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.

[0072] The low refractive index material is a material that has a relatively lower refractive index than 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 1.3 or more and 1.6 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.

[0073] When the dielectric multilayer film 1 is formed into a laminate film 1 consisting of a barrier film 1 and a dielectric multilayer film 1, the laminate film 1 is preferably designed as a reflective film that reflects a portion of near-infrared light, and more preferably as a reflective film that gently blocks light in the near-infrared region. Designing a dielectric multilayer film to enhance the reflectivity in the near-infrared region makes it more likely that ripples will occur in the visible light region when light is incident at a high angle of incidence, resulting in a decrease in visible light transmittance. Designing the laminate film 1 so that it does not strongly block light in the near-infrared region results in an optical filter that is less susceptible to the effects of the angle of incidence. The light blocking properties in the near-infrared region that cannot be completely blocked by the reflectivity properties of the laminate film 1 are complemented by the absorption properties of the phosphate glass described above and the near-infrared absorbing dye described below, thereby providing excellent near-infrared light blocking properties as a whole for the optical filter of the present invention. Specifically, the average reflectivity in the wavelength range from 800 nm to 1200 nm at an incident angle of 5° is preferably 50% to 90%.

[0074] The thickness (physical thickness) of the dielectric multilayer film 1 is preferably 1 μm or more, more preferably 1.5 μm or more, and even more preferably 2.0 μm or more, from the viewpoint of suppressing deterioration of the material. Also, from the viewpoint of productivity, it is preferably 10 μm or less.

[0075] 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.

[0076] The thickness (physical thickness) of the dielectric multilayer film 2 is preferably 100 nm or more, more preferably 300 nm or more, from the viewpoint of improving the water resistance of the optical filter, and is preferably 10 μm or less from the viewpoint of productivity.

[0077] 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.

[0078] The filter may have a dielectric multilayer film 3 on at least one outermost surface, preferably on the light absorbing layer. 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.

[0079] The total number of laminated layers in the dielectric multilayer film 3 is preferably 60 or less, more preferably 30 or less, even more preferably 15 or less, and preferably 8 or more. 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. Furthermore, the overall thickness (physical thickness) of the dielectric multilayer film 3 is preferably 200 to 1000 nm.

[0080] 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.

[0081] <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, and can compensate for the wavelength region that is not blocked by the reflection characteristics of the dielectric multilayer film by absorbing light. The near-infrared absorbing dye preferably has a maximum absorption wavelength in the range of 680 to 800 nm. From the viewpoint of being able to absorb light over a wide range in the near-infrared region and suppressing a decrease in visible light transmittance, it is preferable to combine two or more near-infrared absorbing dyes that have 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 that have a maximum absorption wavelength of 700 nm or more but less than 740 nm with one or more near-infrared absorbing dyes that have a maximum absorption wavelength of 740 to 800 nm.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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 to the surface of 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.

[0090] 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.

[0091] 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.

[0092] The optical filter may have one light absorbing layer or two or more light absorbing layers. When two or more light absorbing layers are present, the layers may have the same or different configurations, and may be formed on the surfaces of the dielectric multilayer films, or two or more layers may be superimposed on the surface of one of the dielectric multilayer films.

[0093] 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.

[0094] 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.

[0095] <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.

[0096] 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.

[0097] As described above, this specification discloses the following optical filters, etc. [1] An optical filter comprising phosphate glass, a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the phosphate glass, a barrier film 1 provided between the phosphate glass and the dielectric multilayer film 1, a barrier film 2 provided between the phosphate glass and the dielectric multilayer film 2, and a light absorbing layer provided on the dielectric multilayer film 2, wherein the light absorbing layer contains a near-infrared absorbing dye, and 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 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-5): (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 0.5% or less at an incident angle of 0 degrees and 0.5% 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-4) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm （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) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 950 nm is 24% or less at an incident angle of 5 degrees and 35% or less at an incident angle of 60 degrees. [2] The optical filter according to [1], wherein when a film consisting of the barrier film 2 and the dielectric multilayer film 2 is defined as a laminated film 2, X defined by the following formula is 35% or more.

[0098]

[0099] (QWOT = (physical film thickness nm / 550 nm) × 4 × refractive index at 550 nm) [3] The optical filter according to [1] or [2], wherein the optical filter satisfies the following spectral characteristic (i-6): (i-6) When the dielectric multilayer film 1 side is the incident direction, the maximum reflectance at wavelengths of 750 to 950 nm is 20% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 60 degrees. [4] The optical filter according to any one of [1] to [3], wherein the optical filter satisfies the following spectral characteristic (i-7): (i-7) The absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 60 degrees for wavelengths of 440 to 500 nm is 15% or less. [5] The optical filter according to any one of [1] to [4], wherein the optical filter satisfies the following spectral characteristic (i-8): (i-8) The average transmittance of the wavelength of 900 to 1000 nm is 1% or less at an incident angle of 0 degrees. [6] The barrier film 1 and the barrier film 2 are TiO ２ [7] The optical filter according to any one of [1] to [5], comprising:

[0022] a total thickness of the barrier film 2 and the dielectric multilayer film 2 is 1.5 μm or more; [8] The optical filter according to any one of [1] to [7], wherein the total thickness of the barrier film 1 and the dielectric multilayer film 1 is 1.5 μm or more; [9] The phosphate glass is substantially free of fluorine atoms, and contains P in mole % on an oxide basis. 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, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ and one or more components selected from ΣR ２ O is R ２ΣR'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), CuO 2 to 30%.

[10] The optical filter according to any one of [1] to [9], wherein the phosphate glass has, converted into a plate thickness of 0.29 mm, an average transmittance at wavelengths of 440 to 500 nm of 70% or more, a transmittance at a wavelength of 1200 nm of 20% or less, a transmittance at a wavelength of 1000 nm of 7% or less, and a transmittance at a wavelength of 800 nm of 7% or less.

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

[10] , 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 to less than 740 nm, and one or more near-infrared absorbing dyes having a maximum absorption wavelength in the range of 740 to 800 nm.

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

[11] .

[0100] 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).

[0101] 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.

[0102]

[0103] 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 5 below.

[0104] <Spectral Properties of Glass> The following glasses were prepared. For phosphate glass or fluorophosphate glass, raw materials were weighed and mixed to have the contents shown in Table 1, expressed in mol% 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.

[0105] The spectral characteristics of each glass are shown in Table 1. The spectral transmittance curves of each glass are shown in FIG.

[0106]

[0107] <Glass Reliability Test 1> A test piece measuring 5 mm in length and 5 mm in width was prepared from the glass 1 manufactured above. A barrier film was formed on both main surfaces by vapor deposition of the materials shown in Table 2 below. 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 2. 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 point with the most advanced deterioration was measured and evaluated based on the following criteria. A grade of C or higher was considered acceptable. A: Edge deterioration was less than 50 μm. B: Edge deterioration was 50 μm or more but less than 100 μm. C: Edge deterioration was 100 μm or more but less than 200 μm. D: Edge deterioration was 200 μm or more. The evaluation results are shown in Table 2 below. Examples 1-1 and 1-2 are reference examples, and Examples 1-3 to 1-5 are reference comparative examples.

[0108]

[0109] The above results show that the barrier films made of titania or tantalum have excellent durability. On the other hand, the barrier films made of alumina, silica, and zirconia showed degradation of the end faces and did not achieve durability.

[0110] <Glass Reliability Test 2> A test piece of the glass 1 manufactured above, measuring 5 mm in length and 5 mm in width, was prepared, and a barrier film was formed on both main surfaces by depositing the materials shown in Table 4 below by vapor deposition. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film having the configuration shown in Table 3. Film number 1 is the layer in contact with the barrier film. The degree of deterioration of the end faces of the obtained test pieces was evaluated 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.

[0111]

[0112]

[0113] The above results confirmed the durability of the barrier film in both cases where the dielectric multilayer film A or B was laminated. Furthermore, durability was further improved in Example 1-6, in which the total thickness of the dielectric multilayer film and the barrier film was 1.5 μm or more.

[0114] <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 5 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 layer 1 and light-absorbing layer 2 with a film thickness of 1 μm. The spectral transmittance curve and spectral reflectance curve of the obtained light-absorbing layer in the wavelength range of 350 to 1200 nm were measured using a UV-visible spectrophotometer. The results are shown in Table 5 below. The spectral transmittance curve of the light-absorbing layer is also shown in FIG. 4.

[0115]

[0116] <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 structure shown in Table 6 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 7 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 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 structure shown in Table 8. In this way, an optical filter 2-1 was manufactured.

[0117] <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 7 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 9.

[0118] <Example 2-3> An optical filter 2-3 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 1B having the configuration shown in Table 6 was formed instead of the dielectric multilayer film 1A, and the thickness of the barrier film 1 was changed to the value shown in Table 9.

[0119] <Example 2-4> An optical filter 2-4 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2C having the configuration shown in Table 7 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 9.

[0120] <Example 2-5> An optical filter 2-5 was manufactured in the same manner as in Example 2-1, except that a dielectric multilayer film 2D having the configuration shown in Table 7 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 9.

[0121] <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 2E having the configuration shown in Table 7 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 9.

[0122] Example 2-7 An optical filter 2-7 was manufactured in the same manner as in Example 2-1, except that a 2000 nm silica film 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 9.

[0123] <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 1C having the configuration shown in Table 6 was formed instead of the dielectric multilayer film 1A, and the thickness of the barrier film 1 was changed to the value shown in Table 9.

[0124] Example 2-9 Optical filter 2-9 was produced in the same manner as in Example 2-1, except that glass 2 (phosphate glass) was used instead of glass 1 (phosphate glass).

[0125] Example 2-10 An optical filter 2-10 was produced in the same manner as in Example 2-1, except that Glass 3 (phosphate glass) was used instead of Glass 1 (phosphate glass).

[0126] Example 2-11 Optical filter 2-11 was produced in the same manner as in Example 2-1, except that glass 4 (fluorophosphate glass) was used instead of glass 1 (phosphate glass).

[0127] Example 2-12: On both main surfaces of Glass 5 (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 1D having the structure shown in Table 6 was formed. ２ and TiO ２ These were alternately laminated by vapor deposition to form a dielectric multilayer film 2B having the configuration shown in Table 7. A resin solution having the same composition as 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 8. In this way, an optical filter 2-12 was manufactured.

[0128]

[0129]

[0130]

[0131] For each optical filter obtained above, a UV-visible spectrophotometer was used to measure the spectral transmittance curves at incident angles of 0 degrees and 60 degrees, and the spectral reflectance curves at incident angles of 5 degrees and 60 degrees in the wavelength range of 350 to 1200 nm. In addition, the degree of deterioration of the end face 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 9 and 10 below were calculated. The method for calculating X in the laminate film 2 will be specifically shown using the laminate film 2 consisting of the dielectric multilayer film 2A and the barrier film 2 as an example. Here, SiO ２ The refractive index of TiO is 1.9 or less. ２ The total physical thickness of the laminated film 2 having a QWOT of less than 2 and a refractive index of 1.9 or less is 1.9 or less. ２ Physical thickness of the film and SiO ２ The total physical thickness 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 physical thickness of the laminated film 2 having 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.

[0132] 5 shows the spectral reflectance curve of the laminate film 1 consisting of the dielectric multilayer film 1A and the barrier film 1. FIG. 6 shows the spectral reflectance curve of the laminate film 1 consisting of the dielectric multilayer film 1C and the barrier film 1. FIG. 7 shows the spectral transmittance curve of the optical filter of Example 2-1, FIG. 8 shows the spectral reflectance curve of the dielectric multilayer film 1 side, and FIG. 9 shows the spectral reflectance curve of the light absorbing layer side. FIG. 10 shows the spectral transmittance curve of the optical filter of Example 2-7, FIG. 11 shows the spectral reflectance curve of the dielectric multilayer film 1 side, and FIG. 12 shows the spectral reflectance curve of the light absorbing layer side.

[0133] Examples 2-1 to 2-4, 2-9 to 2-10, and 2-12 are working examples, and Examples 2-5 to 2-8 and 2-11 are comparative examples.

[0134]

[0135]

[0136] From the above results, it can be seen that the optical filters of Examples 2-1 to 2-4, 2-9 to 2-10, and 2-12 have excellent visible light transmittance even at high incident angles, excellent near-infrared light blocking properties in the 750 to 1000 nm range, small reflectance characteristics for light with wavelengths of 450 to 950 nm, and small shifts in the spectral curves even at high incident angles. The optical filters of Examples 2-5 to 2-7 had high reflectance characteristics in the 450 to 950 nm range. Furthermore, X calculated from the stacked film 2 consisting of the barrier film 2 and the dielectric multilayer film 2C was less than 35%. The optical filter of Example 2-8 had low visible light transmittance and low near-infrared light blocking properties in the 750 to 1000 nm range at high incident angles. Furthermore, the spectral curve shifted significantly at high incident angles. This is thought to be due to the high reflectance characteristics of the multilayer film 1C used as the dielectric multilayer film 1. The optical filter of Example 2-11 had poor blocking ability for near-infrared light in the range of 750 to 1000 nm at high angles of incidence, which is thought to be due to the low absorption characteristics in this range due to the use of fluorophosphate glass.

[0137] 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. 2023-135693) filed on August 23, 2023, the contents of which are incorporated herein by reference.

[0138] 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.

[0139] 1A, 1B Optical filter 10 Phosphate glass 11, 12 Barrier film 21, 22, 23 Dielectric multilayer film 30 Light absorption layer

Claims

1. An optical filter comprising: phosphate glass; a dielectric multilayer film 1 and a dielectric multilayer film 2 provided on both sides of the phosphate glass; a barrier film 1 provided between the phosphate glass and the dielectric multilayer film 1; a barrier film 2 provided between the phosphate glass and the dielectric multilayer film 2; and a light absorbing layer provided on the dielectric multilayer film 2, wherein the light absorbing layer contains a near infrared absorbing dye, and 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 An optical filter comprising one or more selected from the group consisting of: (i-1) an average transmittance of 80% or more at wavelengths of 440 to 500 nm at an incident angle of 0 degrees and 70% or more at an incident angle of 60 degrees; (i-2) an average transmittance of 0.5% or less at wavelengths of 750 to 1000 nm at an incident angle of 0 degrees and 0.5% or less at an incident angle of 60 degrees; (i-3) an average transmittance of 10% at a wavelength IR10 at which the transmittance is 10% in the spectral transmittance curve at an incident angle of 0 degrees; （０ｄｅｇ） (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR10 at which the transmittance is 10% in the range of 600 to 700 nm is （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) When the light absorbing layer side is the incident direction, the maximum reflectance at wavelengths of 450 to 950 nm is 24% or less at an incident angle of 5 degrees and 35% or less at an incident angle of 60 degrees.

2. The optical filter according to claim 1, wherein when a film consisting of said barrier film 2 and said dielectric multilayer film 2 is defined as a laminate film 2, X defined by the following formula is 35% or more. (QWOT = (physical film thickness nm / 550 nm) x 4 x refractive index at 550 nm) 3. The optical filter according to claim 1, which satisfies the following spectral characteristic (i-6): (i-6) When the dielectric multilayer film 1 side is the incident direction, the maximum reflectance of a wavelength of 750 to 950 nm is 20% or more at an incident angle of 5 degrees and 30% or more at an incident angle of 60 degrees.

4. The optical filter according to claim 1, which satisfies the following spectral characteristic (i-7): (i-7) the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 60 degrees, for wavelengths of 440 to 500 nm, is 15% or less.

5. The optical filter according to claim 1, which satisfies the following spectral characteristic (i-8): (i-8) the average transmittance of wavelengths from 900 to 1000 nm is 1% or less at an incident angle of 0 degrees.

6. The barrier film 1 and the barrier film 2 are TiO ２ The optical filter of claim 1 , comprising:

7. The optical filter according to claim 1, wherein the total thickness of said barrier film 2 and said dielectric multilayer film 2 is 1.5 μm or more.

8. The optical filter according to claim 1, wherein the total thickness of said barrier film 1 and said dielectric multilayer film 1 is 1.5 μm or more.

9. 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%.

10. The optical filter according to claim 1, wherein the phosphate glass has, converted into a plate thickness of 0.29 mm, an average transmittance of 70% or more at wavelengths of 440 to 500 nm, a transmittance of 20% or less at a wavelength of 1200 nm, a transmittance of 7% or less at a wavelength of 1000 nm, and a transmittance of 7% or less at a wavelength of 800 nm.

11. 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 to 800 nm.

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

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