Fluorophosphate glass, near-infrared cut filter, and optical device

Abstract

The present invention is a fluorophosphate glass containing each of P, Al, K, Cu, F and R (R is one or more items selected from Li, Na, Rb, and Cs) as essential components, in which the content of Al3+ in mass% is 2%-20%, and the expected value of the ionic radius of an alkali metal component comprising K and R is 80 pm or more and less than 133 pm.

Description

Fluorophosphate glass, near-infrared cut filter, optical device

[0001] The present invention relates to fluorophosphate glass, which is used in color correction filters for digital still cameras, color video cameras, and the like, and which has excellent transmittance in the visible range, excellent absorption of light in the near-infrared range, and good weather resistance, as well as to a near-infrared cut filter and an optical device incorporating said glass.

[0002] Solid-state imaging devices such as CCDs and CMOSs ​​used in PCs, digital still cameras, etc. have spectral sensitivity ranging from the visible range to the near-infrared range around 1200 nm. Because solid-state imaging devices cannot achieve good color reproducibility as they are, the luminosity is corrected using near-infrared cut filter glass to which a specific substance that absorbs infrared light has been added.

[0003] For near-infrared cut filter glass, two important properties are optical properties and weather resistance.

[0004] The optical properties required for near-infrared cut filter glass include strong absorption in the near-infrared region (800 nm to 1200 nm) and high transmittance in the visible to red region (400 nm to 600 nm). In particular, a sharper absorption curve (hereinafter also referred to as sharp cut property) is required in the transmittance curve from the red transmission region to the near-infrared blocking region.

[0005] Furthermore, in order to obtain the above-mentioned optical properties, optical glasses have been developed for near-infrared cut filter glasses, in which Cu components have been added to fluorine-free phosphate glass (hereinafter also referred to as copper phosphate glass). However, copper phosphate glass has problems with weather resistance. Therefore, optical glasses have been developed in which Cu components have been added to fluorophosphate glass (phosphate glass containing fluorine) (hereinafter also referred to as copper fluorophosphate glass or Cu-containing fluorophosphate glass, or fluorophosphate glass) to have high weather resistance. The compositions of these glasses are disclosed in Patent Documents 1 to 4.

[0006] JP 2016-60671 A JP 2004-83290 A WO2022 / 009558CN-A-114455836

[0007] In the near-infrared cut filter glasses described in the patent documents, it was difficult to achieve both high levels of optical properties and weather resistance.

[0008] That is, as mentioned above, copper phosphate glass has high absorption power in the near-infrared region and excellent sharp-cutting ability in the near-infrared region, but has issues with weather resistance, whereas copper fluorophosphate glass has high weather resistance but has issues with absorption power in the near-infrared region and sharp-cutting ability in the near-infrared region.

[0009] For example, as described in Patent Document 4, in copper fluorophosphate glass, increasing the P content in the glass is effective for improving the absorption ability in the near-infrared region and the sharp cutting ability in the near-infrared region, but may result in a decrease in weather resistance.

[0010] The present invention aims to provide a fluorophosphate glass that combines optical properties such as high transmittance from the visible region to the red region, high absorption power in the near-infrared region, and high sharp-cutting power in the near-infrared region with high weather resistance, and to provide a near-infrared cut filter, an optical filter, and an optical device that include the glass.

[0011] As a result of extensive research, the present inventors have found that, in Cu-containing fluorophosphate glass, by setting the content of Al component and the content ratio of alkali metal component within respective predetermined ranges, glass having good weather resistance and desired optical properties can be obtained.

[0012] That is, the present invention is as follows.

[0013] It contains the components P, Al, K, Cu, F and R (R is one or more selected from Li, Na, Rb and Cs), and contains, in mass %, Al ３＋ The content of K is 2% to 20%, and the expected value of the ionic radius of the alkali metal component consisting of K and R is 80 pm to less than 133 pm.

[0014] According to the present invention, it is possible to provide a fluorophosphate glass that combines excellent optical properties with high weather resistance, and a near-infrared cut filter, an optical filter, and an optical device that include the glass.

[0015] FIG. 1 is a graph showing the transmittance of light having wavelengths of 300 nm to 1200 nm in the fluorophosphate glasses of Example 5 (Example) and Example 10 (Comparative Example).

[0016] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention should not be construed as being limited to the embodiments and mechanisms of action described below.

[0017] In this specification, unless otherwise specified, the content of each component and the total content are expressed in "mass %." Here, "mass %" used in this specification refers to the percentage of the mass of each ion when the total mass of the cationic components is 100. In this specification, the range "α to β" means "not less than α and not more than β." "Not less than α to β" means "not less than α and not more than β." Furthermore, the transmittance of the glass of this embodiment includes the reflection characteristics of the glass surface (i.e., it is not the internal transmittance of the glass).

[0018] <Fluorophosphates Glass> The fluorophosphates glass according to an embodiment of the present invention (hereinafter also referred to as the fluorophosphates glass of the present embodiment, or simply as fluorophosphates glass or glass) essentially contains P, Al, K, Cu, F, and R (R is one or more selected from Li, Na, Rb, and Cs), and ３＋ The content of is 2% to 20%, and the expected value of the ionic radius of the alkali metal components consisting of K and R is 80 pm (picometers) to less than 133 pm (picometers).

[0019] A glass according to an embodiment of the present invention is a copper fluorophosphate glass containing, as essential components, P, Al, K, Cu, F, and R (wherein R is one or more selected from Li, Na, Rb, and Cs). Glass containing P as the main component has the effect of enhancing absorption in the near-infrared region and sharp cutting properties in the near-infrared region. Furthermore, the inclusion of F and Al in the glass can improve weather resistance. Furthermore, the absorption in the near-infrared region and sharp cutting properties can be improved by adjusting the expected value of the ionic radius of the alkali metal components consisting of K and R to 80 pm to less than 133 pm, and the inclusion of K and R can improve weather resistance.

[0020] The alkali metal component is K. ＋, Li ＋ , Na ＋ , Rb ＋ and Cs ＋ The expected values ​​of the ionic radii of these components are defined as follows:

[0021] The ionic radii of the alkali metal components are as follows: Li ＋ Ionic radius r Ｌｉ 60 pm, Na ＋ Ionic radius r Ｎａ is 95 pm, K ＋ Ionic radius r Ｋ is 133 pm, Rb ＋ Ionic radius r Ｒｂ is 148 pm, Cs ＋ Ionic radius r Ｃｓ is 169 pm. These ionic radii are based on the literature of L. Pauling (1931-1933), THE NATURE OF THE CHEMICAL BOND (1963, translated by Masao Koizumi, "Chemical Bond Theory", Kyoritsu Shuppan). "Cation %" is a unit that expresses the content of each cationic component as a molar percentage when the total content of all cationic components contained in glass is taken as 100 mol %.

[0022] The expected value of the ionic radius of the alkali metal component is calculated by the following formula:

[0023] Expected value of ionic radius=[ionic radius of each alkali metal component×total amount of cations of each component] / [total amount of cations of all alkali metal components], More specifically, it is as follows.

[0024] [Ionic radius of each alkali metal component × total amount of cations of each component] = ionic radius r Ｌｉ × Amount of Li cations + Ionic radius r Ｎａ × Amount of Na cations + Ionic radius r Ｋ × Amount of cations of K + Ionic radius r Ｒｂ × Amount of Rb cations + Ionic radius r Ｃｓ × amount of Cs cations, [total amount of cations of all alkali metal components] = amount of Li cations + amount of Na cations + amount of K cations + amount of Rb cations + amount of Cs cations

[0025] The glass of the present embodiment contains an alkali metal component (Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ By setting the expected value of the ionic radius of 80 pm or more, it is possible to maintain a high transmittance in the red region while maintaining a sharp absorption profile with enhanced absorption in the near-infrared region. The reason for this is presumed to be as follows.

[0026] Cu in glass ２＋ The non-bridging oxygen atoms are coordinated to form a regular octahedron. ２＋ If the symmetry of the non-bridging oxygen atoms coordinated to Cu is high, a sharp absorption peak will be observed in the near-infrared region. However, if the symmetry of these non-bridging oxygen atoms decreases for reasons described later, Cu ２＋ The absorption peak shifts, and the shape of the glass transmittance curve changes from a sharp absorption peak to a broad absorption peak. It has been reported in "Optical Properties of Glass II." by Kohei Kadono (2009), NEW GLASS Vol. 24 No. 2, that the absorption spectrum of transition metals including Cu is easily changed by changes in the coordination environment in the glass.

[0027] Cu in glass ２＋ The non-bridging oxygen atoms coordinated to the atom are attracted to the surrounding electronegative elements, reducing their symmetry. Electronegativity is a property that indicates the strength of the force with which the nucleus of an atom attracts surrounding electrons. Ionic radius is a value that indicates the distance from the nucleus to the outermost electron shell of an atom. In atoms of the same group, the greater the distance between the nucleus and the bonding electron pair, the lower the electronegativity. Therefore, it can be said that elements with a large ionic radius have low electronegativity.

[0028] Therefore, by including a component with a large ionic radius among alkali metal components in the glass, Cu ２＋ The symmetry of the non-bridging oxygen atoms coordinated to the bridging group is not reduced, and high absorption power in the near-infrared region and high sharp cutoff performance in the near-infrared region can be achieved.

[0029] On the other hand, the alkali metal component (Li ＋ , Na ＋ , K.＋ , Rb ＋ , Cs ＋ ) is 133 pm or more, there is a concern that the weather resistance may be reduced. The reason for this is presumed as follows.

[0030] Weather resistance is evaluated by the degree of deterioration of the glass surface caused when the glass is left standing under high temperature and humidity for a long period of time. ＋ penetrates into the glass, attacks the -O-P-O- structure, and causes hydrolysis. As a result, H desorbed from the glass surface ３ P.O. ４ When the glass is left standing for a long time under high temperature and humidity, the strength of the glass structure weakens due to the inclusion of a large amount of alkali metal components with a large ionic radius, which weakens the ability to attract non-bridging oxygen in the glass. ＋ In other words, the hydrolysis reaction is accelerated, and the weather resistance of the glass is reduced.

[0031] For these reasons, the expected value of the ionic radius of the alkali metal component is desirably 80 pm to less than 133 pm. If it is 80 pm or more, the effects of high absorption in the near-infrared region and improved sharp cut performance can be sufficiently obtained, and if it is less than 133 pm, problems such as reduced weather resistance are unlikely to occur. Therefore, it is more preferably 85 pm or more, even more preferably 90 pm or more, even more preferably 95 pm or more, and most preferably 100 pm or more, and more preferably 130 pm or less, even more preferably 128 pm or less, even more preferably 125 pm or less, and most preferably 120 pm or less.

[0032] The glass according to an embodiment of the present invention essentially contains alkali metal components consisting of K and R. By containing two or more types of alkali metal components in the glass, weather resistance can be improved. The reason for this is presumed to be as follows.

[0033] Glass with poor weather resistance deteriorates under high temperature and high pressure, and precipitates and liquids are seen to be eluted. The cause of this is the alkali metal components and H ＋ If glass is left standing for a long time under high temperature and humidity, the H on the glass surface ＋ An ion exchange reaction occurs between the alkali metal ions on the surface of the glass and the alkali metal ions on the surface of the glass. Specifically, the alkali metal ions are dissolved on the surface of the glass by the ion exchange reaction, and H ＋ The H that has penetrated into the glass ＋ The influence of alkali metals on glass has been described above. The ion diffusion coefficient of alkali metals is larger than that of other components, so the ion mobility is high and H ＋ This easily causes an ion exchange reaction with the glass, which reduces the weather resistance of the glass.

[0034] It is known that when two or more alkali metal components are contained in glass in combination, the mixed alkali effect reduces the ion mobility of each alkali metal component. ＋ This can suppress the ion exchange reaction between the alkali metal component and the aluminum oxide, thereby preventing a decrease in weather resistance.

[0035] Each component that can constitute the glass of the embodiment of the present invention and a suitable content thereof will be described below.

[0036] In the glass of the present invention, P (phosphorus) is P ５＋ It is contained as P ５＋ is the main component that forms fluorophosphate glass, and is an essential component for improving the sharp cutoff property in the near-infrared region. ５＋ The content of P is preferably 20% to 70%. ５＋ If the content of P is 20% or more, the effect is sufficiently obtained, and if it is 70% or less, problems such as glass instability and deterioration of weather resistance are unlikely to occur. Therefore, it is more preferably 25% or more, even more preferably 30% or more, even more preferably 33% or more, and more preferably 60% or less, even more preferably 55% or less, even more preferably 50% or less, and most preferably 45% or less.５＋ As the raw material for (2), phosphoric acid or a salt thereof is preferably used from the viewpoint of suppressing corrosion of the platinum crucible and suppressing volatilization of the components.

[0037] In the glass of the present invention, F (fluorine) is F － It is contained as F. － is an essential component for stabilizing the glass and improving weather resistance. In this specification, when the total amount of all cationic component elements contained in the glass is taken as 100 mass %, F contained in the glass is － The content of F is expressed as an external percentage. － The content is preferably 3% to 60% by weight.

[0038] F － If the content is 3% or more in terms of the external proportion, a sufficient weather resistance effect can be obtained, and if the content is 60% or less in terms of the external proportion, problems such as a decrease in the transmittance of light in the visible region, the absorption ability of light in the near-infrared region, and sharp cutting ability, a decrease in mechanical properties such as strength, hardness, and elastic modulus, and an increase in ultraviolet transmittance are unlikely to occur. The external proportion is more preferably 4% or more, even more preferably 6% or more, still more preferably 8% or more, and most preferably 10% or more, and also more preferably 50% or less, even more preferably 40% or less, still more preferably 30% or less, and most preferably 20% or less.

[0039] In the glass of the present invention, Cu (copper) is Cu ＋ or Cu ２＋ However, in this specification, all of them are contained as Cu. ２＋ The content is listed when present as a substance.

[0040] Cu ２＋ is an essential component for improving absorption in the near-infrared region. ２＋ Cu has the property of attracting phosphate chains in the glass together to form a cross-linked structure, which strengthens the glass structure and improves the weather resistance and strength of the glass. ２＋The content of is preferably 1% to 20%. If it is less than 1%, the glass's absorption ability in the near-infrared region may decrease. It is preferably 2% or more, more preferably 3% or more, even more preferably 4% or more, and even more preferably 5% or more. If it exceeds 20%, the glass becomes unstable and the risk of devitrification increases. It is preferably 18% or less, more preferably 16% or less, even more preferably 15.2% or less, and even more preferably 14% or less.

[0041] The total Cu content is the total amount of Cu expressed in mass %, including monovalent, divalent, and other valences present, and is the content of all components of the glass of this embodiment (excluding F － When the total Cu content (excluding the content of Cu) is taken as 100%, the range of the total Cu content in the glass is preferably 1% to 20%. When the total Cu content is 1% or more, the effect of absorption ability in the near-infrared region can be sufficiently obtained, and when it is 20% or less, the decrease in visible region transmittance can be suppressed. ＋ The content in % is (Cu ＋ The content of Cu can be determined so that the content of Cu (Cu content) × 100 [%] is in the range of 0.01% to 4.0%.

[0042] In the glass of the present invention, Al (aluminum) is Al ３＋ It is contained as Al. ３＋ is a component that forms glass and is an essential component for increasing the strength and weather resistance of glass. ３＋ If the content of Al is 2% or more, the effect can be sufficiently obtained, and if it is 20% or less, problems such as the glass becoming unstable and a decrease in absorption ability and sharp cut property in the near-infrared region are unlikely to occur. ３＋ The content of is preferably 2% to 20%, more preferably 3.5% or more, even more preferably 4% or more, even more preferably 4.5% or more, and most preferably 5% or more, and more preferably 19% or less, even more preferably 18% or less, even more preferably 15% or less, and most preferably 13% or less.

[0043] In addition, Al ３＋ As a raw material for ３ , Al２ O ３ , Al(OH) ３ Among others, the increase in melting temperature, the occurrence of unmelted material, and F － The amount of AlF is reduced, which makes the glass less stable. ３ It is preferable to use

[0044] Li (lithium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, improves the weather resistance of glass, stabilizes glass, and the like. ＋ The content of Li is preferably 0% to 30%. ＋ If the content of Li is 30% or less, the glass is less likely to become unstable. Since the absorption ability and sharp cut property in the near-infrared region are reduced when Li is contained, the content is more preferably 28% or less, even more preferably 25% or less, still more preferably 20% or less, and most preferably 10% or less. ＋ If only Li is used, the weather resistance will improve but the absorption ability and sharp cut in the near infrared region will decrease. ＋ It is necessary to further include one or more alkali metal components having a larger ionic radius.

[0045] Na (sodium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. ＋ The content of Na is preferably 0% to 40%. ＋ If the content of Na is 40% or less, the glass is less likely to become unstable. It is more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, and most preferably 10% or less. ＋ If only Na is used, either the weather resistance or the high absorption capacity and sharp cut performance in the near infrared region can be improved, and the improved properties differ depending on the composition. However, it is difficult to improve both properties at the same time. Therefore, in order to improve weather resistance, Na ＋ In order to improve absorption and sharp cut in the near infrared region, Na ＋It is necessary to include an alkali metal component having a larger ionic radius.

[0046] In the glass of the present invention, K (potassium) is K ＋ It is contained as K. ＋ is an essential component that has the effects of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, and improving the absorption ability and sharp cut property in the near-infrared region. ＋ The content of is preferably 1% to 40%. ＋ If the content of K is 40% or less, the glass is less likely to become unstable, which is preferable. It is more preferably 2% or more, even more preferably 5% or more, even more preferably 8% or more, and most preferably 10% or more. ＋ If the alkali metal component is K, the weather resistance is reduced, so the content is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, and most preferably 14% or less. ＋ If only K is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0047] Rb (rubidium) is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, and improving the absorption ability and sharp cut property in the near-infrared region. ＋ The content of Rb is preferably 0% to 20%. ＋ If the content of Rb is 20% or less, the glass is less likely to become unstable, which is preferable. ＋ Since the weather resistance is reduced when the alkali metal component is Rb, the content is more preferably 15% or less, further preferably 10% or less, and even more preferably 5% or less. ＋ If only Rb is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0048] Cs (cesium) is a component that has the effects of lowering the melting temperature of glass, lowering the liquidus temperature of glass, and improving high absorption capacity and sharp cut properties in the near-infrared region. ＋ The content of Cs is preferably 0% to 20%. ＋ If the content of Cs is 20% or less, the glass is less likely to become unstable, which is preferable. ＋ Since the weather resistance is reduced when the alkali metal component is contained, the content is more preferably 15% or less, further preferably 10% or less, and further more preferably 5% or less. ＋ If only Cs is used, the absorption ability and sharp cut in the near infrared region will improve, but the weather resistance will decrease. ＋ It is necessary to contain one or more alkali metal components other than the above.

[0049] K ＋ and R ＋ (R ＋ Li ＋ , Na ＋ , Rb ＋ and Cs ＋ R) is an essential component for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ＋ and K. ＋ The total amount of Li ＋ , Na ＋ , K. ＋ , Rb ＋ and Cs ＋ The total amount (ΣR ＋ +K ＋ If ΣR ) is 14% or more, the effect can be obtained sufficiently, and if it is 42% or less, the glass is less likely to become unstable, which is preferable. ＋ +K ＋ The content of ΣR is preferably 14% to 42%. ＋ +K ＋ The content of ΣR is more preferably 14.5% or more, even more preferably 15% or more, even more preferably 17% or more, and most preferably 18% or more. ＋ +K ＋The content is more preferably 35% or less, even more preferably 30% or less, even more preferably 28% or less, and most preferably 25% or less.

[0050] Mg (magnesium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of glass. ２＋ The content of Mg is preferably 0 to 20%. ２＋ If the content is 20% or less, problems such as the glass becoming unstable or the near-infrared blocking ability decreasing are unlikely to occur. It is more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0051] Ca (calcium) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of glass. ２＋ The content of Ca is preferably 0% to 20%. ２＋ If the content is 20% or less, problems such as the glass becoming unstable or the near-infrared blocking ability decreasing are unlikely to occur. It is more preferably 1% or more, even more preferably 2% or more, and more preferably 18% or less, even more preferably 15% or less, still more preferably 10% or less, and most preferably 7% or less.

[0052] Strontium (Sr) is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, increases the strength of glass, and increases the weather resistance of glass. ２＋ The content of Sr is preferably 0% to 30%. ２＋If the content is 30% or less, problems such as glass instability and reduced near-infrared cutoff properties are unlikely to occur. It is more preferably 1% or more, even more preferably 2% or more, even more preferably 4% or more, and most preferably 5% or more, and is more preferably 25% or less, even more preferably 20% or less, even more preferably 16% or less, and most preferably 14% or less.

[0053] Ba (barium) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, enhances the absorption ability of light in the near-infrared region, and enhances the sharp cut property in the near-infrared region. ２＋ The content of Ba is preferably 0% to 40%. ２＋ If the content is 40% or less, problems such as glass instability are unlikely to occur. It is more preferably 1% or more, even more preferably 5% or more, even more preferably 10% or more, and most preferably 13% or more, and is more preferably 35% or less, even more preferably 30% or less, even more preferably 22% or less, and most preferably 19% or less.

[0054] R" ２＋ (R" ２＋ is Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ R" is a component for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ２＋ The total amount of Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total amount (ΣR" ２＋ If ΣR" is 14.5% or more, the effect is sufficiently obtained, and if it is 35% or less, the glass is less likely to become unstable. ２＋The content is preferably 14.5% to 35%, more preferably 16.5% or more, even more preferably 18% or more, even more preferably 20% or more, and most preferably 22% or more, and more preferably 34% or less, even more preferably 32.5% or less, even more preferably 30% or less, and most preferably 28% or less.

[0055] Zn (zinc) has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. ２＋ The content of Zn is preferably 0% to 20%. ２＋ If the content is 20% or less, problems such as glass instability, deterioration in the melting property of the glass, and reduction in near-infrared cutoff properties are unlikely to occur. Zn (zinc) is more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less. Most preferably, Zn (zinc) is not contained.

[0056] P ５＋ Content of / ΣR' (R' is Al ３＋ , Mg ２＋ , Li ＋ and ΣR′ is the total amount of R′) is preferably 3.0 to 7.7.

[0057] P ５＋ is a component that enhances the sharp cut performance in the near infrared region, but also has the effect of reducing weather resistance. ３＋ , Li ＋ , Mg ＋ are components that have the effect of improving weather resistance.

[0058] Therefore, P for ΣR' ５＋ By making the content ratio of P to ΣR′ 7.7 or less, the weather resistance of the glass can be improved. ５＋ By setting the content ratio of P to ΣR′ to be 3.0 or more, the sharp cutting properties of the glass in the near-infrared region can be maintained at a high level. ５＋The ratio of the content of P to ΣR′ is more preferably 3.2 or more, even more preferably 3.5 or more, even more preferably 4.0 or more, and most preferably 4.5 or more. ５＋ The content ratio is more preferably 7.5 or less, even more preferably 7.0 or less, even more preferably 6.3 or less, and most preferably 5.5 or less.

[0059] B (boron) may be contained in an amount of up to 20% in order to stabilize the glass. ３＋ If the content is 20% or less, problems such as deterioration in the weather resistance of the glass and a decrease in the near-infrared cutoff property are unlikely to occur. It is more preferably 15% or less, even more preferably 10% or less, still more preferably 8% or less, and most preferably 5% or less.

[0060] In the glass of the present embodiment, SiO ２ , GeO ２ , ZrO ２ , SnO ２ , TiO ２ , CeO ２ , W.O. ３ , Y ２ O ３ , La ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Nb ２ O ５ may be contained in a range of 10% or less to improve the weather resistance of the glass. If the content of these components is 10% or less, problems such as the generation of devitrification inclusions in the glass and a decrease in the near-infrared cutoff properties are unlikely to occur. The content is preferably 4% or less, more preferably 3% or less, even more preferably 2% or less, and even more preferably 1% or less.

[0061] Fe ２ O ３ , Cr ２ O ３ , Bi ２ O ３ , NiO, V ２ O ５ , MnO２ and CoO are components that, when present in glass, reduce the transmittance of light in the visible region. Therefore, it is preferable that these components are not substantially contained in the glass. Here, "substantially not contained in the glass" means that they are not contained except for unavoidable impurities, and that the components are not actively added. Specifically, this means that the content of each of these components in the glass is approximately 100 ppm by mass or less.

[0062] From the viewpoint of ensuring the strength of the glass, the glass of the embodiment of the present invention preferably has a Young's modulus of 48 GPa or more, more preferably 50 GPa or more, even more preferably 55 GPa or more, and still more preferably 60 GPa or more.

[0063] The glass of the present invention has an average thermal expansion coefficient of 60×10 in the range of 30° C. to 300° C. －７ / ℃~180×10 －７ / °C, and 65 x 10 －７ / ℃~165×10 －７ / °C is more preferable, and 70 × 10 －７ / ℃~157×10 －７ / °C is more preferable, and 70 × 10 －７ / ℃~150×10 －７ / °C is more preferable, and 70 × 10 －７ / ℃~143×10 －７ / °C is most preferred.

[0064] When the glass of the embodiment of the present invention is used as a color correction filter (near-infrared cut filter glass) for a solid-state imaging device, it also functions as a cover glass for hermetically sealing the solid-state imaging device, and therefore may be directly bonded to the packaging material. In this case, if there is a large difference in the thermal expansion coefficient between the near-infrared cut filter glass and the packaging material, peeling or breakage may occur at the bonded portion, and the airtight state may not be maintained.

[0065] 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 glass of this embodiment has an average thermal expansion coefficient in the temperature range of 30°C to 300°C within the above range.

[0066] In the glass of the embodiment of the present invention, when the glass thickness is converted so that the wavelength at which the transmittance in the near-infrared region is 50% (hereinafter referred to as the IR half-value) is 630 nm, the spectral transmittance at a wavelength of 1200 nm is preferably 22% or less. By doing so, a glass having low transmittance in the near-infrared region can be obtained. The spectral transmittance is more preferably 21% or less, even more preferably 20% or less, and even more preferably 19% or less. The spectral transmittance can be measured by the method described in the examples.

[0067] The glass of the present invention preferably has a spectral transmittance of 60% or more at a wavelength of 600 nm when converted into a sheet thickness such that the IR half-value is 630 nm. This provides a glass with high sharp-cutting properties in the near-infrared region. The spectral transmittance is more preferably 62% or more, even more preferably 64% or more, and even more preferably 66% or more. The spectral transmittance can be measured by the method described in the examples.

[0068] The glass of the present invention preferably has a spectral transmittance of 4.0% or less at a wavelength of 800 nm when converted into a sheet thickness such that the IR half-value is 630 nm. This provides a glass with low transmittance of light in the near-infrared region. The spectral transmittance is more preferably 3.8% or less, even more preferably 3.6% or less, and even more preferably 3.4% or less. The spectral transmittance can be measured by the method described in the examples.

[0069] The glass of the present invention preferably has a spectral transmittance of 75% or more at a wavelength of 420 nm when converted into a sheet thickness such that the IR half-value is 630 nm. This provides a glass with high transmittance in the visible range. The spectral transmittance is more preferably 78% or more, even more preferably 80% or more, and particularly preferably 82% or more. The spectral transmittance can be measured by the method described in the examples.

[0070] In the glass of the present invention, when converted into a plate thickness such that the IR half-value is 630 nm, the ratio of the spectral transmittance at a wavelength of 600 nm to the spectral transmittance at a wavelength of 800 nm (spectral transmittance at a wavelength of 600 nm / spectral transmittance at a wavelength of 800 nm) is preferably 20 or more. By doing so, a glass with high sharp-cutting properties in the near-infrared region can be obtained. The spectral transmittance ratio is more preferably 21 or more, even more preferably 21.5 or more, and particularly preferably 22 or more. The spectral transmittance can be measured by the method described in the examples.

[0071] The conversion of the plate thickness at which the IR half value of the glass of the embodiment of the present invention becomes 630 nm is carried out by the formula (T ｉ２ =T ｉ１ （ｔ２／ｔ１） ) was used. ｉ１ is the internal transmittance of the target glass at a wavelength of 630 nm (data excluding reflection loss on the front and back surfaces), t1 is the plate thickness of the target glass, T ｉ２ is the converted transmittance, and t2 is the converted plate thickness (plate thickness at which the IR half-value is 630 nm). The conversion from transmittance to internal transmittance was performed using the following formula, assuming that the reflection losses Ref on the front and back surfaces of the glass were each 0.0454.

[0072] Internal transmittance=transmittance / {100×(1-Ref) ２}

[0073] When used as a color correction filter for a solid-state imaging device, for example, the glass of the present invention is often used in a thickness of 0.4 mm or less. When converted to a thickness such that the IR half value is 630 nm, the thickness is preferably 0.4 mm or less, more preferably 0.3 mm or less, even more preferably 0.25 mm or less, and even more preferably 0.23 mm or less. Furthermore, from the viewpoint of ensuring the strength of the glass, a thickness of 0.05 mm or more is preferred.

[0074] The glass according to the embodiment of the present invention can be produced, for example, as follows.

[0075] First, the raw materials are weighed and mixed to achieve the above composition range (mixing step). This raw material mixture is placed in a platinum crucible and heated and melted in an electric furnace at a temperature of 750°C to 1000°C (melting step). After thorough stirring and clarification, the mixture is poured into a mold, cut, polished, and formed into a plate of the specified thickness (forming step).

[0076] In the melting step of the above manufacturing method, the highest temperature of the glass during melting is preferably 1000°C or lower. If the highest temperature of the glass during melting exceeds this temperature, the transmittance characteristics may deteriorate. The temperature is more preferably 950°C or lower, even more preferably 930°C or lower, and even more preferably 900°C or lower.

[0077] 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 800°C or higher, more preferably 820°C or higher.

[0078] After being formed into a predetermined shape, the glass of the present invention may have an optical multilayer film provided on at least one surface of the glass. Examples of optical multilayer films include an IR cut film (a film that reflects near-infrared rays), a UV / IR cut film (a film that reflects ultraviolet rays and near-infrared rays), a UV cut film (a film that reflects ultraviolet rays), and an anti-reflection film. These optical thin films can be formed by known methods such as vapor deposition and sputtering.

[0079] An adhesion-strengthening film may be provided between the glass of the embodiment of the present invention and the optical multilayer film. By providing the adhesion-strengthening film, the adhesion between the glass and the optical multilayer film can be improved, and film peeling can be suppressed. Examples of the adhesion-strengthening film include silicon oxide (SiO ２ ), titanium oxide (TiO ２ ), lanthanum titanate (La ２ Ti ２ O ７ ), aluminum oxide (Al ２ O ３ ), aluminum oxide and zirconium oxide (ZrO ２ ), a mixture with magnesium fluoride (MgF ２ ), calcium fluoride (CaF ２ ), strontium fluoride (SrF ２ ), fluorine silicone, etc. Substances containing fluorine or oxygen have higher adhesion, and magnesium fluoride and / or titanium oxide are particularly preferred as adhesion-strengthening films because they have high adhesion to glass or films. The adhesion-strengthening film may be a single layer or two or more layers. In the case of two or more layers, a combination of multiple substances may be used.

[0080] <Near-infrared cut filter> A near-infrared cut filter according to an embodiment of the present invention comprises the glass according to the embodiment of the present invention described above. This makes it possible to obtain a near-infrared cut filter that can keep the transmittance of light in the near-infrared region low while maintaining a high transmittance of light in the visible region (particularly blue light). The near-infrared cut filter according to an embodiment of the present invention may comprise the following configuration in addition to the glass according to an embodiment of the present invention.

[0081] The near-infrared cut filter of an embodiment of the present invention may include, on at least one main surface of the glass of an embodiment of the present invention, an absorption layer containing a near-infrared absorbing material having a maximum absorption wavelength in the near-infrared region. By adopting such a configuration, it is possible to obtain a near-infrared cut filter having a lower transmittance of light in the near-infrared region.

[0082] The near-infrared cut filter of an embodiment of the present invention is preferably made of a transparent resin selected from acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, and polyester resins, and the near-infrared absorbing dye is added to the transparent resin, which is made of one type of resin alone or a mixture of two or more types, and the resulting resin is contained in the absorption layer.

[0083] 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.

[0084] <Optical Devices> The glass according to the embodiments of the present invention can be applied to optical devices. An optical device is a device that uses light to record or transmit information. Examples of optical devices include the imaging device of a digital still camera and an optical sensor that detects light and converts it into an electrical signal. Applying the glass according to the embodiments of the present invention to optical devices has the advantage of contributing to the miniaturization and low profile of optical devices, since the glass has excellent absorption characteristics, particularly in the near-infrared region.

[0085] When applied to an optical device, the glass of the present invention can be used in combination with an optical filter having light absorption characteristics different from those of the glass of the present invention. Examples of light absorption characteristics of an optical filter include an absorption ability in a wavelength range different from that of the glass of the present invention, or an absorption ability in the same near-infrared wavelength range as the glass of the present invention. By using the glass of the present invention in combination with an optical filter having different light absorption characteristics in an optical device, optical characteristics that are difficult to obtain with a single glass can be achieved. Examples of optical filters include an infrared cut filter provided near the image sensor of an imaging device, a cover glass covering an opening on the subject side of an optical device, and a lens provided inside an optical device. The glass of the present invention and an optical filter may also be used in a laminated configuration.

[0086] As explained above, the present specification discloses the following: [1] An alloy containing, indispensably, P, Al, K, Cu, F, and R (R is one or more selected from Li, Na, Rb, and Cs), and containing, in mass %, Al ３＋ The content of K is 2% to 20%, and the expected value of the ionic radius of the alkali metal components consisting of K and R is 80 pm to less than 133 pm. [2] Fluorophosphate glass, in which, expressed in mass %, ＋ (R ＋ Li ＋ , Na ＋ , Rb ＋ , Cs ＋ One or more components selected from ΣR ＋ is R ＋ the total amount of) and K ＋ The total amount of ΣR" is 14% to 42%. ２＋ (R" ２＋ Is, Ba ２＋ , Sr ２＋ , Ca ２＋ , Mg ２＋ one or more components selected from ΣR″ ２＋ is R" ２＋ [3] The fluorophosphate glass according to [1], wherein the total amount of K is 14.5% to 35%. ＋[4] The fluorophosphate glass according to [1] or [2], wherein the content of Al is 1% to 40% by mass. ３＋ [5] The fluorophosphate glass according to any one of [1] to [3], wherein the content of P is 3.5% to 20% by mass. ５＋ :20%~70% Al ３＋ :3.5%~20%K ＋ : 1% to 40% Li ＋ : 0% to 30% Na ＋ : 0% to 40% Rb ＋ : 0% to 20% Cs ＋ : 0% to 20% Mg ２＋ : 0% to 20% Ca ２＋ : 0% to 20% Sr ２＋ : 0% to 30% Ba ２＋ : 0% to 40% Cu ２＋ : 1% to 20% Zn ２＋ : Contains 0% to 20% of F － [6] The fluorophosphate glass according to any one of [1] to [4], containing 3% to 60% of P. ５＋ Content of / ΣR' (R' is Al ３＋ , Mg ２＋ , Li ＋and ΣR' is the total amount of R') is 3.0 to 7.7. [7] The fluorophosphate glass according to any one of [1] to [4], wherein, when converted into a plate thickness so that the wavelength at which the transmittance in the near-infrared region becomes 50% (IR half value) is 630 nm, the plate thickness is 0.4 mm or less, the spectral transmittance at a wavelength of 1,200 nm is 22% or less, and the spectral transmittance at a wavelength of 600 nm is 60% or more. [8] The fluorophosphate glass according to any one of [1] to [7], wherein, when converted into a plate thickness so that the wavelength at which the transmittance in the near-infrared region becomes 50% (IR half value) is 630 nm, the plate thickness is 0.4 mm or less, the spectral transmittance at a wavelength of 800 nm is 4% or less, and the spectral transmittance at a wavelength of 420 nm is 75% or more. [9] Fluorophosphate glass according to any one of [1] to [8], having a plate thickness of 0.4 mm or less when converted into a plate thickness so that the wavelength at which the transmittance in the near-infrared region becomes 50% (IR half-value) is 630 nm, and having a spectral transmittance ratio (A / B) of 20 or more, where A is the spectral transmittance at a wavelength of 600 nm and B is the spectral transmittance at a wavelength of 800 nm.

[10] A near-infrared cut filter comprising the fluorophosphate glass according to any one of [1] to [9].

[11] An optical device comprising the fluorophosphate glass according to any one of [1] to

[10] .

[12] An optical device comprising the fluorophosphate glass according to any one of [1] to

[11] and an optical filter having light absorption characteristics different from those of the fluorophosphate glass.

[0087] Examples will be described below, but the present invention is not limited to these examples.

[0088] Examples and comparative examples of the fluorophosphate glass of the present invention are shown in Tables 1 to 4. Examples 1 to 7 and 19 to 32 are examples, and Examples 8 to 18 are comparative examples.

[0089] Example 10 shows the results of preparing and evaluating a glass having a glass composition corresponding to that of Example 9 described in Patent Document 1.

[0090] [Preparation of Glass] The glasses of Examples 1 to 32 had the compositions (mass %, F) shown in Tables 1 to 4 after melting. －The raw materials were weighed and mixed so that the content was the same as the original content (% indicates the total content, and % indicates the cation content for alkali metal components only). The raw materials were placed in a platinum crucible with an internal volume of 1 L and heated and melted in an electric furnace at the melting temperature shown in each table for 1 to 100 hours. The mixture was then clarified, stirred, and poured into a rectangular mold measuring 100 mm in length, 65 mm in width, and 20 mm in height that had been preheated to 50°C to 500°C. The mixture was then held at 300°C to 500°C for at least 2 hours, and then slowly cooled at a rate of approximately 1°C / min to obtain a plate-shaped glass sample measuring 40 mm in length, 40 mm in width, and 0.1 to 0.5 mm thick, both sides of which were optically polished.

[0091] F － Since F is highly volatile, the difference between before and after dissolution is － The content of F contained in the raw materials before melting of the glasses of Examples 1 to 32 varies. － The value converted into the content of raw material before dissolution F － The F contained in the glasses of Examples 1 to 7, 11 to 13, 19, 21 to 27, and 30 after melting is shown in Table 1. － The content of the fluorine-containing compound was analyzed by XRF (Rigaku, ZSX Primus II) and the value was referred to as "analysis value after dissolution F － " is shown.

[0092] The F of the glasses of Examples 1 to 7, 11 to 13, 19, 21 to 27, and 30 before and after melting － Content ratio of "analysis value after dissolution F － " / "Pre-melting raw material equivalent value F － The average value of " was calculated for Examples 8 to 10, 14 to 18, 20, 28, 29, 31, and 32, converted into the raw material before melting. － From the content of F after dissolution, － The calculated value was referred to as the "estimated value after dissolution F － " is shown.

[0093] The following raw materials were used for each glass.

[0094] P ５＋ In the case of H ３ P.O. ４ was used.

[0095] Al ３＋ In the case of ３ was used.

[0096] Li ＋ In the case of LiF, LiNO ３ was used.

[0097] Na ＋ In this case, NaF was used.

[0098] K ＋ In this case, KF was used.

[0099] Mg ２＋ In this case, MgO was used.

[0100] Ca ２＋ In the case of CaF ２ was used.

[0101] Sr ２＋ In the case of SrF ２ was used.

[0102] Ba ２＋ In the case of BaF ２ was used.

[0103] Cu ２＋ In the case of , CuO was used.

[0104] Zn ２＋ In the case of F using ZnO － In the case of , the fluoride raw material of the above component was used.

[0105] In addition to the components described in the Examples and Comparative Examples, O was added to the glass as an anion. ２－ Includes. ２－ The content of F is highly volatile － Although the glass in the examples and comparative examples has a different O content, ２－ Contains:

[0106] The raw materials for the glass are not limited to those mentioned above, and known materials can be used.

[0107] [Evaluation - Transmittance] The transmittance was evaluated by the following procedure. The transmittance of the prepared optically polished glass was measured in 1 nm increments for light with wavelengths of 300 nm to 1200 nm using a spectrophotometer (V-570, manufactured by JASCO Corporation), and the plate thickness was converted so that the IR half-value (the wavelength at which the transmittance in the near-infrared region, including reflection losses on the front and back surfaces, is 50%) was 630 nm. The conversion was performed by first converting the obtained transmittance to internal transmittance and using the following formula.

[0108] T ｉ２ =T ｉ１ （ｔ２／ｔ１） ・T ｉ１ : Internal transmittance of actual sample (before conversion) t1: Plate thickness of actual sample T ｉ２ : Internal transmittance after conversion t2: Plate thickness to be converted Internal transmittance after conversion (T ｉ２ From the transmittance including reflection losses on the front and back surfaces, the spectral transmittance at a wavelength of 1200 nm, the spectral transmittance B at a wavelength of 800 nm, the spectral transmittance A at a wavelength of 600 nm, and the spectral transmittance at a wavelength of 420 nm were calculated, and also from the transmittance A and transmittance B, the transmittance ratio A / B was calculated. Note that the transmittance was converted to internal transmittance using the following formula, assuming that the reflection losses Ref on the front and back surfaces of the glass were each 0.0454. Internal transmittance = Transmittance / {100 × (1 - Ref) ２}

[0109] [Evaluation - Weather Resistance] Weather resistance was evaluated according to the following procedure. After leaving the glass for 100 hours in an atmosphere at a temperature of 85°C and a humidity of 85%, the glass was visually observed under a high-intensity light source. If no foreign matter was deposited on the glass surface, no liquid was eluted, and no deterioration was observed, the glass was evaluated as "Good." If only foreign matter was deposited on the glass surface or only liquid was eluted, the glass was evaluated as "Good." If both foreign matter was deposited on the glass surface or liquid was eluted, the glass was evaluated as "Poor."

[0110] [Evaluation - Meltability] Meltability was evaluated according to the following procedure. After melting the glass at 750°C to 1000°C, the glass was maintained under the aforementioned conditions, and cooled. The presence or absence of devitrification particles in the resulting glass was visually inspected, with observation of devitrification particles indicated as "X" and absence of devitrification particles indicated as "O". [Evaluation - Young's Modulus] Young's modulus was evaluated according to the following procedure. The glass was processed into a size of 30 x 30 x 10 mm, and the value measured using the ultrasonic pulse method (JIS R 1602: Test method for elastic modulus of fine ceramics) was expressed in units of [GPa]. [Evaluation - Average Thermal Expansion Coefficient] The average thermal expansion coefficient was evaluated according to the following procedure. The glass was processed into a rod-shaped piece, and the average thermal expansion coefficient was measured from 30 to 300°C at a heating rate of 5°C / min using a thermal analyzer (manufactured by Rigaku Corporation, product name: TMA8310) by the thermal expansion method.

[0111] The results are shown in Tables 1 to 4.

[0112]

[0113]

[0114]

[0115]

[0116] FIG. 1 also shows the transmittances of Example 5 (Example) and Example 10 (Comparative Example) converted into thicknesses so that the IR half value was 630 nm.

[0117] In each example of the present invention, glass was obtained that had high absorption power and sharp cut properties in the near-infrared region, did not devitrify (good solubility), and had good weather resistance.

[0118] In contrast, the glasses of Examples 8 to 18, which are comparative examples, had the following properties.

[0119] In Example 8, the expected value of the ionic radius of the alkali metal component was less than 80 pm, and therefore the glass had good weather resistance but poor absorption ability in the near-infrared region and poor sharp-cutting properties.

[0120] Example 9 contains only one alkali metal component, P ５＋ Content of / ΣR' (R' is Al ３＋ , Mg２＋ , Li ＋ where ΣR′ is the total amount of R′) is greater than 7.5, the glass has high absorption ability and sharp cut in the near-infrared region but has poor weather resistance.

[0121] Example 10 is P ５＋ Content of / ΣR' (R' is Al ３＋ , Mg ２＋ , Li ＋ where ΣR′ is the total amount of R′) is less than 3.0, the glass has good weather resistance but poor absorption ability in the near-infrared region and poor sharp-cutting ability.

[0122] Examples 11 to 14 contained only one type of alkali metal component, and the expected value of the ionic radius of the alkali metal component was 133 pm or more, so the glasses had high absorption ability and sharp cut properties in the near-infrared region but low weather resistance.

[0123] Examples 15 and 16 contain two types of alkali metal components, but the expected values ​​of the ionic radii of the alkali metal components are 133 pm or more. Therefore, the glasses have high absorption ability and sharp cut properties in the near-infrared region but have reduced weather resistance.

[0124] Example 17 is ΣR ＋ Since the content was less than 14%, devitrification occurred, resulting in a glass with low melting point.

[0125] From Example 17, ΣR ＋ It was suggested that the solubility can be improved by setting the content within a certain range.

[0126] Example 18 is ΣR ＋ is less than 14% and ΣR" ＋ Since the content of SiO 2 exceeded 40%, devitrification occurred, resulting in a glass with low melting point.

[0127] From Example 18, ΣR ＋ and ΣR" ＋ It was suggested that the solubility can be improved by setting the content within a certain range.

[0128] This application claims priority based on Japanese Patent Application No. 2023-109751, filed on July 4, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. Contains P, Al, K, Cu, F and R (R is one or more selected from Li, Na, Rb and Cs) as essential components, and is expressed as Al in mass%. ３＋ The content of is 2% to 20%, and the expected value of the ion radius of the alkali metal components consisting of K and R is 80 pm to less than 133 pm.

2. Mass % display, ΣR ＋ (R ＋ Li ＋ , Na ＋ , Rb ＋ , Cs ＋ One or more components selected from ΣR ＋ is R ＋ (total amount of) and K ＋ The total amount of ΣR" is 14% to 42%. ２＋ (R" ２＋ Is Ba ２＋ , Sr ２＋ , Ca ２＋ , Mg ２＋ One or more components selected from ΣR″ ２＋ " ２＋ The fluorophosphates glass according to claim 1, wherein the total amount of (a) is 14.5% to 35%.

3. In mass percent, K ＋ The fluorophosphates glass according to claim 1, wherein the content of is 1% to 40%.

4. Mass % of Al ３＋ The fluorophosphates glass according to claim 1, wherein the content of is 3.5% to 20%.

5. In mass %, P ５＋ :20%~70% Al ３＋ :3.5%~20%K ＋ : 1% to 40% Li ＋ : 0% to 30% Na ＋ : 0% to 40% Rb ＋ : 0% to 20% Cs ＋ : 0% to 20% Mg ２＋ : 0% to 20% Ca ２＋ : 0% to 20% Sr ２＋ : 0% to 30% Ba ２＋ : 0% to 40% Cu ２＋ : 1% to 20% Zn ２＋ : Contains 0% to 20% F － The fluorophosphates glass according to claim 1, containing 3% to 60% of 6. P ５＋ Content of Al / ΣR' (R' is Al ３＋ , Mg ２＋ , Li ＋ 2. The fluorophosphates glass according to claim 1, wherein ΣR′ is the total amount of R′) is 3.0 to 7.

7.

7. The fluorophosphate glass according to claim 1, wherein, when converted into a plate thickness such that the wavelength at which the transmittance in the near infrared region is 50% (IR half value) is 630 nm, the plate thickness is 0.4 mm or less, the spectral transmittance at a wavelength of 1,200 nm is 22% or less, and the spectral transmittance at a wavelength of 600 nm is 60% or more.

8. The fluorophosphate glass according to claim 1, wherein, when converted into a plate thickness such that the wavelength at which the transmittance in the near infrared region is 50% (IR half value) is 630 nm, the plate thickness is 0.4 mm or less, the spectral transmittance at a wavelength of 800 nm is 4% or less, and the spectral transmittance at a wavelength of 420 nm is 75% or more.

9. The fluorophosphate glass according to claim 1, wherein, when converted into a plate thickness so that the wavelength at which the transmittance in the near-infrared region is 50% (IR half value) is 630 nm, the plate thickness is 0.4 mm or less, and the spectral transmittance ratio (A / B) is 20 or more, where A is the spectral transmittance at a wavelength of 600 nm and B is the spectral transmittance at a wavelength of 800 nm.

10. A near-infrared cut filter comprising the fluorophosphates glass according to claim 1.

11. An optical device comprising the fluorophosphate glass of claim 1.

12. An optical device comprising the fluorophosphate glass of claim 1 and an optical filter having light absorption characteristics different from those of the fluorophosphate glass.

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