Glass for optical filters, optical filters, and solid-state imaging devices

Abstract

To provide a glass for optical filter and an optical filter in which the transmittance of light in a visible range (particularly, blue region) is maintained to a high level while the transmittance of light in a near-infrared region is suppressed to a low level.SOLUTION: The present invention relates to a glass for optical filter in which the average transmittance of light having the wavelength 450 nm to 500 nm is 88.5% or more and the average transmittance of light having the wavelength 850 nm to 900 nm is 1.5% or less in terms of a thickness 0.3 mm, which contains each component of P, Cu and Mo, and substantially does not contain F.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to glass for optical filters, which are used in color correction filters for solid-state imaging devices such as digital still cameras and color video cameras, and which have excellent light transmittance in the visible region and excellent light absorption in the near-infrared region, and to optical filters. [Background technology]

[0002] Solid-state imaging devices such as CCDs and CMOSs ​​used in digital still cameras and the like have spectral sensitivity ranging from the visible region to the near-infrared region around 1200 nm. Therefore, solid-state imaging devices cannot achieve good color reproducibility as they are, so the luminosity of the solid-state imaging devices is corrected using near-infrared cut filter glass doped with a specific substance that absorbs infrared light. Optical glass has been developed and is used as this near-infrared cut filter glass, in which Cu (copper) is added to phosphate glass so as to selectively absorb light with wavelengths in the near-infrared region. The compositions of these glasses are disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-008908 Summary of the Invention [Problem to be solved by the invention]

[0004] Phosphate glass has a tendency to have low transmittance in the visible region (especially blue light) because the temperature at which the glass raw materials are melted is high, at over 1000°C. The reason for this is thought to be as follows: In phosphate glass containing Cu, the Cu component in the glass absorbs light in the near-infrared region. 2+ (divalent) and Cu, which has absorption characteristics in the wavelength range of 300nm to 600nm +It is known that Cu exists as a monovalent element. When the temperature is high when melting the glass raw materials, some of the Cu component in the glass becomes Cu. + (Cu 2+ This results in a low transmittance of light in the visible region (especially blue light). In addition, if the temperature when melting the glass raw materials is lowered, unmelted foreign matter is generated in the glass, causing a significant decrease in the transmittance of light in the visible region.

[0005] The present invention has been made against this background, and aims to provide glass for optical filters and optical filters that can maintain high transmittance for light in the visible region (especially blue light) while suppressing transmittance for light in the near-infrared region to a low level. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that phosphate glass containing Cu and Mo (molybdenum) can provide glass for optical filters and optical filters that can maintain a high transmittance of light in the visible region while suppressing the transmittance of light in the near-infrared region to a low level compared to conventional optical filters.

[0007] That is, the glass for optical filters of the present invention contains the components P (phosphorus), Cu and Mo, but does not substantially contain F (fluorine).

[0008] In a preferred embodiment of the glass for optical filters of the present invention, the glass for optical filters further contains 0.01% to 10% MoO3 expressed in mass % on an oxide basis.

[0009] In a preferred embodiment of the glass for optical filters of the present invention, the glass for optical filters further contains 40% or more of P2O5 expressed as mass % on an oxide basis.

[0010] In a preferred embodiment of the glass for optical filters of the present invention, the glass for optical filters further contains 5% or more Al2O3 expressed as mass % on an oxide basis.

[0011] In a preferred embodiment of the glass for optical filters of the present invention, the glass for optical filters further contains more than 2.0% CuO, expressed as mass % on an oxide basis.

[0012] In addition, a preferred embodiment of the glass for optical filters of the present invention is a glass for optical filters further comprising, in mass % on an oxide basis, P2O5: 40%~80%, Al2O3: 5% to 20%, ΣR2O: 0.5% to 20% (R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O, and ΣR2O is the total amount of R2O), ΣR′O: 0% to 15% (R′O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR′O is the total amount of R′O), CuO: 2.0% to 20% (but not including 2.0%) MoO3: 0.01%~10%, included.

[0013] In addition, a preferred embodiment of the glass for optical filters of the present invention is a glass for optical filters having a thickness of 0.3 mm equivalent, The average transmittance of light with wavelengths of 450nm to 500nm is 88.5% or more. The average transmittance of light with wavelengths of 850nm to 900nm is 1.5% or less. is.

[0014] In a preferred embodiment of the glass for optical filters of the present invention, the glass for optical filters further has an average transmittance ratio A / B of 1.140 to 2.000, where A is the average transmittance of light with a wavelength of 450 nm to 500 nm and B is the average transmittance of light with a wavelength of 350 nm to 400 nm.

[0015] The optical filter of the present invention comprises the above-described glass for optical filters. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide glass for optical filters and optical filters that can maintain high transmittance of light in the visible region (especially blue light) while suppressing transmittance of light in the near-infrared region to a low level. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a graph showing the transmittance of light having a wavelength of 300 nm to 1200 nm in Example 7 (Example) and Example 1 (Comparative Example). [Figure 2] 1 is a graph showing the transmittance of light having a wavelength of 350 nm to 600 nm in Example 7 (Example) and Example 1 (Comparative Example). DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes in detail the preferred embodiments of the present invention, but the present invention is not limited to the following preferred embodiments. In addition, in the present specification, the range "α to β" means "not less than α and not more than β."

[0019] Each component that may constitute the glass of this embodiment and its preferred content will be described below. In this specification, unless otherwise specified, the content of each component and the total content are expressed in mass% based on the oxide. Furthermore, the transmittance of the glass of this embodiment includes the reflective properties of the glass surface (i.e., it is the external transmittance of the glass, not the internal transmittance of the glass).

[0020] P2O5 is the main component that forms glass and is an essential component for improving near-infrared blocking properties. If the P2O5 content is 40% or more, this effect is sufficiently obtained, and if it is 80% or less, problems such as glass instability and reduced weather resistance are unlikely to occur. Therefore, the P2O5 content is preferably 50% to 80%, more preferably 52% to 78%, even more preferably 54% to 77%, still more preferably 56% to 76%, and most preferably 60% to 75%.

[0021] Al2O3 is a major component that forms glass and is a component that increases the strength of the glass. If the Al2O3 content is 5% or more, the effect is sufficiently obtained, and if it is 20% or less, problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur. Therefore, the content is preferably 5% to 20%, more preferably 6% to 18%, even more preferably 7% to 17%, even more preferably 8% to 17%, and most preferably 9% to 16.5%.

[0022] R2O (where R2O is one or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. If the total amount of R2O (ΣR2O) is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, the glass is less likely to become unstable, which is preferable. Therefore, the content is preferably 0.5% to 20%, more preferably 1% to 20%, even more preferably 2% to 20%, still more preferably 3% to 20%, and most preferably 4% to 20%.

[0023] Li2O is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. The Li2O content is preferably 0% to 15%. A Li2O content of 15% or less is preferable because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The Li2O content is more preferably 0% to 8%, even more preferably 0% to 7%, even more preferably 0% to 6%, and most preferably 0% to 5%.

[0024] Na2O is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, and stabilizes glass. The Na2O content is preferably 0% to 15%. If the Na2O content is 15% or less, the glass is less likely to become unstable, which is preferable. The Na2O content is more preferably 0.5% to 14%, even more preferably 1% to 13%, and even more preferably 2% to 13%.

[0025] K2O is a component that has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The K2O content is preferably 0% to 15%. If the K2O content is 15% or less, the glass is less likely to become unstable, which is preferable. The K2O content is more preferably 0.5% to 14%, even more preferably 1% to 13%, and even more preferably 2% to 13%.

[0026] RbO is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The RbO content is preferably 0% to 15%. If the RbO content is 15% or less, the glass is less likely to become unstable, which is preferable. The RbO content is more preferably 0.5% to 14%, even more preferably 1% to 13%, and even more preferably 2% to 13%.

[0027] Cs2O is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The Cs2O content is preferably 0% to 15%. If the Cs2O content is 15% or less, the glass is less likely to become unstable, which is preferable. The Cs2O content is more preferably 0.5% to 14%, even more preferably 1% to 13%, and even more preferably 2% to 13%.

[0028] In addition, when two or more types of alkali metal components represented by R2O are added simultaneously, a mixed alkali effect occurs in the glass, 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 +This inhibits the hydration reaction caused by ion exchange, improving the weather resistance of the glass. Therefore, the glass of this embodiment preferably contains two or more components selected from Li2O, Na2O, K2O, Rb2O, and Cs2O. In this case, the total amount (ΣR2O) of R2O (where R2O includes Li2O, Na2O, K2O, Rb2O, and Cs2O) is preferably 7% to 18% (but not including 7%). If the total amount of R2O exceeds 7%, its effects are sufficiently obtained, and if it is 18% or less, problems such as glass instability, reduced near-infrared blocking properties, and reduced glass strength are unlikely to occur, which is preferable. Therefore, ΣR2O is preferably more than 7% and 18% or less, more preferably 7.5% to 17%, even more preferably 8% to 16%, even more preferably 8.5% to 15%, and most preferably 9% to 14%.

[0029] 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 glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The total amount of R'O (ΣR'O) is preferably 0% to 15%. If the total amount of R'O is 15% or less, problems such as glass instability, reduced near-infrared cutoff properties, and reduced strength of glass are unlikely to occur, which is preferable. The amount is more preferably 0% to 13%, and even more preferably 0% to 11%. The amount is even more preferably 0% to 9%, and even more preferably 0% to 8%.

[0030] 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 10%. A CaO content of 10% or less is preferred because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The CaO content is more preferably 0% to 8%, even more preferably 0% to 6%, even more preferably 0% to 5%, and most preferably 0% to 4%.

[0031] 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 15%. An MgO content of 15% or less is preferred because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The content is more preferably 0% to 13%, even more preferably 0% to 10%, even more preferably 0% to 9%, and most preferably 0% to 8%.

[0032] BaO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, etc. The BaO content is preferably 0.1% to 10%. A BaO content of 10% or less is preferred because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The BaO content is more preferably 0% to 8%, even more preferably 0% to 6%, even more preferably 0% to 5%, and most preferably 0% to 4%.

[0033] SrO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. The SrO content is preferably 0% to 10%. If the SrO content is 10% or less, problems such as glass instability and reduced near-infrared cutoff properties are less likely to occur, which is preferable. The SrO content is more preferably 0% to 8%, even more preferably 0% to 7%, and most preferably 0% to 6%.

[0034] 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 15%. If the ZnO content is 15% or less, problems such as deterioration of the melting property of the glass and reduction in the near-infrared cutoff property are unlikely to occur, which is preferable. The ZnO content is more preferably 0% to 13%, even more preferably 0% to 10%, even more preferably 0% to 9%, and most preferably 0% to 8%.

[0035] The glass of this embodiment preferably contains substantially no divalent cations of elements other than Cu. The reason for this is as follows. Note that elements other than Cu include the above-mentioned R'. Therefore, ΣR'O is preferably 0%.

[0036] When the glass of this embodiment contains CuO, Cu 2+ Light in the near-infrared region is cut off by the light absorption of ions. 2- Cu split by the electric field of ions 2+ This occurs due to electron transitions between d orbitals of the ions. The splitting of the d orbitals occurs in Cu 2+ O 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 (wavelengths: 750 nm or more, less than 1000 nm) and strengthening the light absorption ability in the short-wavelength infrared region (wavelengths: 1000 nm or more, less than 2500 nm). Since the strength of the electric field of cations increases with the valence of the ions, adding oxides containing divalent cations, especially of elements other than Cu, to glass can reduce the near-infrared blocking ability and the transmittance of short-wavelength infrared light.

[0037] MoO3 is an essential component for increasing the transmittance of glass to light in the visible region. The inventors prepared Cu-containing phosphate glass (but did not contain a fluorine component) and phosphate glass that additionally contained only Mo, and examined their optical properties. As a result, they confirmed that the latter glass exhibited a significantly increased transmittance of light with wavelengths of 400 nm to 540 nm compared to the former glass. This phenomenon is hypothesized to be due to the following. Mo is contained in the glass. 6+ However, when Mo and Cu are co-doped in phosphate glass, the Cu in the glass +releases electrons and Cu 2+ Next (Cu + → Cu 2+ +e - ), Cu + The electrons emitted by Mo 6+ received Mo 5+ (Mo 6+ +e - → Mo 5+ This allows the absorption of Cu, which has absorption characteristics in the wavelength range of 300 nm to 600 nm. + The proportion of (monovalent) ions decreased, and the transmittance of light with wavelengths of 400 nm to 540 nm increased. It is believed that the transmittance of light with wavelengths of around 400 nm did not increase because Mo ions have the property of absorbing light with wavelengths of around 400 nm. Phosphate glass containing Cu and Mo was not previously known, and the inventors believe that the above finding is a new discovery.

[0038] A MoO3 content of 0.01% or more is sufficient to enhance the transmittance of the glass to light in the visible region, and a content of 10% or less is preferable because problems such as a decrease in near-infrared blocking ability and the generation of devitrification inclusions in the glass are unlikely to occur. The MoO3 content is more preferably 0.02% to 9%, even more preferably 0.03% to 8%, even more preferably 0.04% to 7%, and most preferably 0.05% to 6%.

[0039] CuO is an essential component for blocking near-infrared rays. If the CuO content exceeds 2.0%, that effect and the effect of increasing the transmittance of visible light through the glass obtained when co-doped with MoO3 are sufficiently obtained. On the other hand, if the CuO content is 20% or less, problems such as the generation of devitrification inclusions in the glass and a decrease in transmittance of visible light are unlikely to occur, which is preferable. The CuO content is more preferably 4% to 19.5%, even more preferably 5% to 19%, even more preferably 6% to 18.5%, and most preferably 7% to 18% (but excluding 7%).

[0040] In the glass of this embodiment, F is an effective component for improving weather resistance, but is an environmentally hazardous substance and may reduce the near-infrared blocking properties, so F is not substantially contained. In the present invention, "substantially free of a specific component" means that the component is not intentionally added, and does not exclude the component being unavoidably mixed in from raw materials, etc., to the extent that it does not affect the desired properties.

[0041] B2O3 may be contained in a range of 10% or less to stabilize the glass. A B2O3 content of 10% or less is preferable because problems such as a deterioration in the weather resistance of the glass and a decrease in the near-infrared cutoff ability are unlikely to occur. The B2O3 content is preferably 9% or less, more preferably 8% or less, even more preferably 7% or less, even more preferably 6% or less, and most preferably 5% or less.

[0042] The glass of this embodiment may contain SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 in an amount of 5% or less to improve the weather resistance of the glass. A content of these components of 5% or less is preferred because it is less likely to cause problems such as the generation of devitrification inclusions in the glass and a decrease in near-infrared blocking properties. 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.

[0043] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO are all components that, when present in glass, reduce the transmittance of light in the visible region, and therefore it is preferable that these components are substantially not contained in the glass.

[0044] The glass of this embodiment has a thermal expansion coefficient of 60×10 in the range of 30°C to 300°C. -7 / ℃~180×10 -7 / °C is preferred.

[0045] When the glass of this embodiment is used as a color correction filter (near-infrared cut filter glass) for a solid-state imaging device, it may be directly bonded to a packaging material because it also functions as a cover glass for hermetically sealing the solid-state imaging device. In this case, if there is a large difference in thermal expansion coefficient between the near-infrared cut filter glass and the packaging material, peeling or damage may occur at the bonded portion, making it impossible to maintain an airtight state.

[0046] Generally, materials such as glass, crystallized glass, ceramics, and alumina are used as packaging materials in consideration of heat resistance, and it is preferable to reduce the difference in thermal expansion coefficient between these packaging materials and the near-infrared cut filter glass. Therefore, it is preferable that the thermal expansion coefficient of the glass of this embodiment is within the above range in the temperature range of 30°C to 300°C. If the thermal expansion coefficient of the glass of this embodiment is outside the above range, the difference with the thermal expansion coefficient of the packaging material will be large, and there is a risk that the airtight state will not be maintained due to peeling or breakage. A more preferable range for the thermal expansion coefficient is 65×10 -7 / ℃~175×10 -7 / °C, and a more preferable range is 70 × 10 -7 / ℃~170×10 -7 / ℃.

[0047] The glass of this embodiment has an average transmittance of 88.5% or more for wavelengths of 450 nm to 500 nm and an average transmittance of 1.5% or less for wavelengths of 850 nm to 900 nm, calculated at a thickness of 0.3 mm, when measured when light is incident on the main surface from the normal direction. By providing the glass of this embodiment with these optical properties, it is possible to obtain glass that is suitable for use as an optical filter, which can maintain a high transmittance for light in the visible region while suppressing the transmittance for light in the near-infrared region to a low level. The glass of this embodiment has an average transmittance of light with a wavelength of 450 nm to 500 nm, converted into a thickness of 0.3 mm, of preferably 88.6% or more, more preferably 88.7% or more, even more preferably 88.8% or more, still more preferably 88.9% or more, and most preferably 89% or more. Furthermore, the average transmittance of the glass of this embodiment for light with a wavelength of 850 nm to 900 nm, converted into a thickness of 0.3 mm, is preferably 1.4% or less, more preferably 1.3% or less, even more preferably 1.1% or less, still more preferably 0.9% or less, even more preferably 0.7% or less.

[0048] The glass of this embodiment has an average transmittance ratio A / B of 1.140 to 2.000, where A is the average transmittance of light with wavelengths of 450 nm to 500 nm, and B is the average transmittance of light with wavelengths of 350 nm to 400 nm, converted into a thickness of 0.3 mm. Providing such optical properties, the glass of this embodiment is able to cut ultraviolet light while maintaining high transmittance in the visible range, particularly blue light. An average transmittance ratio A / B of less than 1.140 is undesirable, as the above-mentioned effect may not be fully achieved. An average transmittance ratio A / B of more than 2.000 is undesirable, as absorption of ultraviolet light may extend into the visible range, reducing transmittance of light in the visible range. The glass of this embodiment has an average transmittance ratio A / B of preferably 1.145 to 2.000, more preferably 1.150 to 1.900, even more preferably 1.160 to 1.800, still more preferably 1.170 to 1.700, and most preferably 1.180 to 1.600.

[0049] When the glass of this embodiment is used as a color correction filter for a solid-state imaging device, for example, it is often used with a thickness of 2 mm or less. From the viewpoint of reducing the weight of the component, it is preferably used with a thickness of 1 mm or less, more preferably 0.5 mm or less, even more preferably 0.3 mm or less, and even more preferably 0.2 mm or less. Furthermore, from the viewpoint of ensuring the strength of the glass, it is preferably 0.05 mm or more.

[0050] The glass of this embodiment can be produced, for example, as follows. First, the raw materials are weighed and mixed to achieve the above composition range (mixing process). This raw material mixture is placed in a platinum crucible and heated and melted in an electric furnace at temperatures between 950°C and 1300°C (melting process). After thorough stirring and clarification, the mixture is poured into a mold, cut, polished, and formed into a plate of the specified thickness (forming process).

[0051] In the melting step of the above manufacturing method, the highest temperature of the glass during melting is preferably 1300°C or lower. If the highest temperature of the glass during melting exceeds 1300°C, the transmittance characteristics will deteriorate. The temperature is more preferably 1250°C or lower, even more preferably 1200°C or lower, and even more preferably 1150°C or lower.

[0052] Furthermore, if the temperature in the melting step is too low, problems such as devitrification occurring during melting and a long time required for melting through may occur, so the temperature is preferably 1000°C or higher, more preferably 1025°C or higher.

[0053] The glass of this embodiment may be formed into a predetermined shape, and then an optical multilayer film may be provided on at least one surface of the glass to obtain an optical filter comprising the above-described glass for optical filters. Examples of optical multilayer films include IR cut films (films that reflect near-infrared rays), UV / IR cut films (films that reflect ultraviolet rays and near-infrared rays), UV cut films (films that reflect ultraviolet rays), and anti-reflection films. These optical thin films can be formed by known methods such as vapor deposition and sputtering.

[0054] An adhesion-strengthening film may be provided between the glass and the optical multilayer film of this embodiment. The provision of an adhesion-strengthening film improves adhesion between the glass and the optical multilayer film, preventing film peeling. Examples of adhesion-strengthening films include silicon oxide (SiO2), titanium oxide (TiO2), lanthanum titanate (La2Ti2O7), aluminum oxide (Al2O3), a mixture of aluminum oxide and zirconium oxide (ZrO2), magnesium fluoride (MgF2), calcium fluoride (CaF2), strontium fluoride (SrF2), and fluorine-containing silicone. Substances containing fluorine or oxygen have higher adhesion, and magnesium fluoride and titanium oxide are particularly preferred as adhesion-strengthening films because they enhance adhesion to glass and films. The adhesion-strengthening film may be a single layer or two or more layers. In the case of two or more layers, multiple substances may be combined.

[0055] The optical filter of this embodiment includes the glass of this embodiment described above. The optical filter of this embodiment may also include the following configuration in addition to the glass of this embodiment.

[0056] The optical filter of this embodiment may include an absorption layer containing a near-infrared absorbing material having a maximum absorption wavelength in the near-infrared region on at least one main surface of the glass of this embodiment. By adopting such a configuration, an optical filter with a lower transmittance of light in the near-infrared region can be obtained.

[0057] The optical filter of this embodiment is preferably made of a transparent resin selected from acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyimide resin, polyamideimide resin, polyolefin resin, cyclic olefin resin, and polyester resin, and is preferably made of one of these resins alone or a mixture of two or more of these resins, to which a near-infrared absorbing dye has been added and which is contained in the absorption layer. As the near-infrared absorbing dye, it is preferable to use a near-infrared absorbing material made of at least one selected from the group consisting of squarylium dyes, phthalocyanine dyes, cyanine dyes and diimmonium dyes. [Example]

[0058] Examples will be described below, but the present invention is not limited to these examples. Examples and comparative examples of the optical filter glass of the present invention are shown in Tables 1 to 5. Examples 1, 13, and 16 are comparative examples, and Examples 2 to 12, 14, 15, and 17 are examples.

[0059] [Glass production] These glasses were prepared by weighing and mixing raw materials to obtain the compositions shown in Tables 1 to 5 (oxide mass %, none of the glasses contained substantially fluorine). The raw materials were placed in a crucible with an internal volume of approximately 400 cc and melted for 2 hours in an air atmosphere. The melting temperatures of the glass raw materials were 1100°C for Examples 3, 6, and 16, 1050°C for Examples 1, 2, 4, 5, and 7 to 12, 1150°C for Examples 13 to 15, and 1125°C for Example 17. The mixture was then refined and stirred, poured into a rectangular mold preheated to approximately 300°C to 500°C, measuring 100 mm in length, 80 mm in width, and 20 mm in height, and slowly cooled at a rate of approximately 1°C / min to obtain glass samples in the form of plates measuring 40 mm in length, 30 mm in width, and approximately 0.3 mm in thickness, both sides of which were optically polished.

[0060] The raw materials for each glass were, in the case of P2O5, one or more of H3PO4, Al(PO3)3, NaPO3, and KPO3. In the case of Al2O3, Al(PO3)3 was used. In the case of Li2O, one or more of LiPO3, LiNO3, and Li2CO3 were used. In the case of Na2O, one or more of NaPO3, NaNO3, and Na2CO3 were used. In the case of K2O, one or more of KPO3, KNO3, and K2CO3 were used. In the case of CuO, at least one of CuO and Cu(PO3)2 was used. In the case of MoO3, one or more of MoO3 and Na2MoO4 was used. The raw materials for the glass are not limited to those mentioned above, and known materials can be used.

[0061] [evaluation] For the glass samples prepared as described above, the transmittance of light with wavelengths of 350 nm to 1200 nm was measured using a spectrophotometer (JASCO Corporation, V-570) and converted to a value for a thickness of 0.3 mm. From the converted transmittances, the average transmittance B of light with wavelengths of 350 nm to 400 nm, the average transmittance A of light with wavelengths of 450 nm to 500 nm, and the average transmittance of light with wavelengths of 850 nm to 900 nm were obtained. In addition, the average transmittance ratio A / B was calculated from the average transmittances A and B. The results are shown in Tables 3 to 6. The transmittance of light with wavelengths of 300 nm to 1200 nm in Example 1 (Comparative Example) and Example 7 (Example) is shown in FIG. 1, and the transmittance of light with wavelengths of 350 nm to 600 nm in FIG.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] [Table 5]

[0067] [Table 6]

[0068] In the examples (Examples 2 to 12) of the present invention, by including Mo in the glass, all had an average transmittance of 88.5% or more for wavelengths of 450 nm to 500 nm, and an average transmittance of 1.5% or less for wavelengths of 850 nm to 900 nm, and it was possible to keep the transmittance of light in the near-infrared region low while maintaining a high transmittance of light in the visible region. In particular, compared to the glass of the comparative example (Example 1) which did not contain Mo, the glasses of the examples (Examples 2 to 12) which contained Mo all had improved average transmittance of light in the visible region (particularly blue light). These were due to the fact that the inclusion of Mo reduced the Cu content in the glass. + It is believed that this is due to the reduced proportion of the component present. Furthermore, the glasses of the examples (Examples 14 and 15) of the present invention are obtained by adding only Mo to the glass of the comparative example (Example 13) which does not contain Mo. The glass of the example (Example 17) of the present invention is obtained by adding only Mo to the glass of the comparative example (Example 16) which does not contain Mo. Looking at the optical properties of these glasses, the glasses of the examples which contain Mo have improved average transmittance of light in the visible region (especially blue light) compared to the glass of the comparative example which does not contain Mo. This is because the inclusion of Mo increases the Cu content in the glass. + It is believed that this is due to the reduced proportion of the component present. Furthermore, Examples 3 and 6 are examples in which the glass compositions are the same as those of Examples 2 and 5, respectively, and only the temperature at which the glass raw materials were melted was changed (increased by 50°C). The optical properties shown in Table 3 show that the glasses of Examples 3 and 6 can maintain a high average transmittance of light in the visible region (particularly blue light) compared to the comparative example (Example 1) that does not contain Mo, even though the melting temperature of the glass raw materials was increased.

[0069] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These changes also naturally fall within the technical scope of the present invention.

[0070] This application claims priority based on Patent Application No. 2022-074100, filed with the Japan Patent Office on April 28, 2022, and the entire contents of Patent Application No. 2022-074100 are incorporated herein by reference.

Claims

1. When converted to a thickness of 0.3 mm, the average transmittance of light having a wavelength of 450 nm to 500 nm is 88.5% or more, and the average transmittance of light having a wavelength of 850 nm to 900 nm is 1.5% or less, In terms of mass % based on oxides, P2O5: 50% to 80%, Al 2 O 3: 6% to 20%, ΣR 2 O: 4% to 20% (R 2 O is one or more components selected from Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O, and ΣR 2 O is the total amount of R 2 O), ΣR′O: 0% to 15% (R′O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR′O is the total amount of R′O), CuO: 4% to 20%, MoO3: 0.01% to 10%, Including, the total content of SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 is 5% or less in mass% on an oxide basis; A glass for optical filters that is substantially free of F, Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO.

2. When converted to a thickness of 0.3 mm, the average transmittance ratio A / B is 1.140 to 2.000, where A is the average transmittance of light with a wavelength of 450 nm to 500 nm and B is the average transmittance of light with a wavelength of 350 nm to 400 nm, In terms of oxide mass%, P2O5: 50% to 80%, Al 2 O 3: 6% to 20%, ΣR 2 O: 4% to 20% (R 2 O is one or more components selected from Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O, and ΣR 2 O is the total amount of R 2 O), ΣR′O: 0% to 15% (R′O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR′O is the total amount of R′O), CuO: 4% to 20%, MoO3: 0.01% to 10%, Including, the total content of SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 is 5% or less in mass% on an oxide basis; A glass for optical filters that is substantially free of F, Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO.

3. In terms of mass % based on oxides, P ２ O ５ 3. The glass for optical filters according to claim 1, wherein the glass contains 50% to 77% of

4. 3. The glass for optical filters according to claim 1, which contains 6% to 20% CuO in mass % on an oxide basis.

5. In terms of mass % of oxides, MoO ３ 3. The glass for optical filters according to claim 1, wherein the glass contains 0.01% to 1.18% of

6. An optical filter comprising the glass for optical filters according to claim 1 or 2.

7. A solid-state imaging device comprising the optical filter according to claim 6.

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