Fluorophosphate-based optical glass, optical elements, and lenses

Abstract

Provided are: a fluorophosphate-based optical glass having a larger partial dispersion ratio relative to an Abbe's number (νd) and having excellent press moldability; an optical element; and a lens.　The fluorophosphate-based optical glass is characterized in that the content of an F- component is 50.0% to 90.0% inclusive when expressed in anion % (mol%), the total content of an Rn+ component is 2.0% or less when expressed in cation % (mol%) (in which the Rn+ component comprises at least one component selected from the group consisting of Li+, Na+ and K+), a Ti4+ component or a Bi3+ component is contained, and the formula: (θg,F) > -0.0005νd+0.575 which shows the relationship between a partial dispersion ratio (θg,F) and an Abbe's number (νd) is satisfied.

Description

[Technical Field]

[0001] This invention relates to phthalate-based optical glass, optical elements, and lenses. [Background technology]

[0002] Fluorophosphate-based optical glass has a high fluorine content, resulting in lower dispersion and a higher partial dispersion ratio compared to glasses with other compositions.

[0003] In photographic lenses, lenses with different partial dispersion ratios and dispersions are used in combination to correct chromatic aberration. Therefore, for lenses with similar Abbe numbers, a lens with a larger partial dispersion ratio is more suitable for correcting chromatic aberration. Patent documents 1 and 2 describe inventions aimed at obtaining glass with excellent chromatic aberration correction. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-226594 [Patent Document 2] Japanese Patent Publication No. 2018-145028 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the glass described in Patent Document 1 is Gd 3+ Ya Y 3+ It contains a large amount of Gd. 3+ Ya Y 3+ Because rare earth oxides such as these have a high specific gravity, the weight reduction of the glass is not sufficient relative to the Abbe number.

[0006] Furthermore, the glass described in Patent Document 2 is Rn + Component (Rn + The main ingredient is Li+ , Na + and K + one or more selected from the group consisting of) in a large amount. Rn + When press molding such as mold press molding is performed during lens production, this component is a component that tends to cause devitrification like clouding on the surface of the lens.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a fluorophosphate-based optical glass, an optical element, and a lens, which have a large partial dispersion ratio with respect to the Abbe number (ν d ) and are excellent in press moldability. [Means for Solving the Problem]

[0008] The inventors of the present invention have conducted intensive tests and studies to solve the above problems, and as a result, as a cation component, P 5+ , Ti 4+ component or Bi 3+ component is contained, and as an anion component, F - is contained in the glass, and by adjusting the content of each component, it has been found that a fluorophosphate-based optical glass having a large partial dispersion ratio with respect to the Abbe number (ν d ) and excellent in press moldability can be obtained, and the present invention has been completed. Specifically, the present invention provides the following.

[0009] (1) in terms of anion % (mol%), F - the content of the component is 50.0% or more and 90.0% or less, in terms of cation % (mol%), Rn + the total content of components is 2.0% or less (Rn + component is Li + , Na + and K + one or more selected from the group consisting of), Ti 4+ component or Bi 3+ component is contained, partial dispersion ratio (θg,F), Abbe number (νd The formula showing the relationship with ) (θg,F)>-0.0005ν d +0.575, A feature that satisfies the following conditions: Fluorophosphate-based optical glass.

[0010] (2)Ln 3+ The total content of the ingredients is 3.0% or less (Ln 3+ The ingredients are La 3+ , Gd 3+ , Y 3+ and Yb 3+ The optical glass described in (1), which is one or more selected from the group consisting of the following.

[0011] (3) Cation ratio Gd 3+ / (La 3+ +Y 3+ +Yb 3+ The optical glass described in (1) or (2), wherein the ratio is 1.60 or less.

[0012] (4) An optical element made of optical glass as described in any of (1) to (3). [Effects of the Invention]

[0013] According to the present invention, the Abbe number (ν d ) allows for the production of phthalate-based optical glass, optical elements, and lenses with a high partial dispersion ratio and excellent press-formability. Furthermore, it is possible to obtain phthalate-based optical glass, optical elements, and lenses that are also lightweight. [Modes for carrying out the invention]

[0014] The embodiments of the optical glass of the present invention will be described in detail below. The present invention is not limited in any way to the embodiments described below, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, explanations may be omitted where necessary to avoid repetition, but this does not limit the spirit of the invention.

[0015] <Glass components> The components constituting the optical glass of the present invention will be described. In this specification, unless otherwise specified, the content of each component shall be expressed in cation% or anion% based on the molar ratio. Here, "cation%" and "anion%" (hereinafter sometimes referred to as "cation% (mol%)" and "anion% (mol%)") represent the content of each component contained in the glass, obtained by separating the glass components of the optical glass of the present invention into cation components and anion components, and setting the total proportion of each to 100 mol%. Note that the ionic values ​​used for each component are merely representative values ​​for convenience and do not distinguish them from those with other ionic values. The ionic values ​​of each component present in optical glass may be other than the representative values. For example, since phosphorus (P) usually exists in glass with an ionic value of 5, in this specification, "P 5+ Although it is expressed as "[...], it may exist in other ionic states. Thus, even if strictly speaking other ionic states exist, in this specification, each component is treated as existing in the glass at its representative ionic state.

[0016] The optical glass of this invention is a phthalate-based optical glass, and refers to glass containing phosphoric acid and fluorine. In this invention, phthalate-based optical glass may be referred to simply as optical glass.

[0017] [About cation components] P 5+ It is a glass-forming component and has the property of reducing devitrification of glass and increasing the refractive index. Therefore, P 5+ The content of is preferably 10.0% or more, more preferably 11.0% or more, even more preferably 12.0% or more, even more preferably 13.0% or more, and most preferably 14.0% or more as the lower limit. On the other hand, P 5+ The content of is preferably 30.0% or less, more preferably 29.0% or less, and even more preferably 28.0% or less.

[0018] Al 3+It has the property of reducing devitrification of glass and increasing the stability of glass. Therefore, Al 3+ The content of is preferably 10.0% or more, more preferably 12.0% or more, even more preferably 14.0% or more, even more preferably 16.0% or more, even more preferably 117.0% or more, even more preferably 18.0% or more, and even more preferably 19.0% or more as the lower limit. On the other hand, Al 3+ From the viewpoint of suppressing devitrification due to excessive content, the content of is preferably 35.0% or less, more preferably 34.0% or less, even more preferably 33.0% or less, and even more preferably 32.0% or less.

[0019] Ti 4+ This component increases the partial dispersion ratio while increasing the refractive index and dispersion of the glass. In particular, Ti 4+ Compared to other high refractive index components, it has a lower specific gravity and is a component with high dispersive properties. Therefore, 4+ The content of is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.15% or more, and even more preferably 0.25% or more as the lower limit. On the other hand, Ti 4+ From the viewpoint of improving resistance to devitrification, the upper limit is preferably 5.0% or less, more preferably 4.0% or less, and even more preferably 3.5% or less.

[0020] Bi 3+ , Ti 4+ Similarly, this component increases the partial dispersion ratio while also increasing the refractive index and dispersion of the glass. Therefore, Bi 3+ The content of is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.3% or more, and even more preferably 0.5% or more as the lower limit. On the other hand, Bi 3+ From the viewpoint of reducing the specific gravity of the glass, the content of is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, and even more preferably 2.0% or less.

[0021] Mg2+ Ca 2+ Sr 2+ Ba 2+ It has the property of reducing devitrification of glass and improving its meltability. On the other hand, a high content leads to a decrease in resistance to devitrification.

[0022] Mg 2+ The lower limit of the content is preferably greater than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, even more preferably 2.0% or more, and even more preferably 3.0% or more. On the other hand, Mg 2+ The content of is preferably 15.0% or less, more preferably 13.0% or less, even more preferably 10.0% or less, even more preferably 9.0% or less, and even more preferably 8.0% or less.

[0023] Ca 2+ The lower limit of the content is preferably greater than 0%, more preferably 3.0% or more, even more preferably 5.0% or more, even more preferably 8.0% or more, even more preferably 10.0% or more, even more preferably 13.0% or more, and even more preferably 15.0% or more. On the other hand, Ca 2+ The content of is preferably 30.0% or less, more preferably 28.0% or less, even more preferably 27.0% or less, even more preferably 26.0% or less, and even more preferably 25.0% or less.

[0024] Sr 2+ The lower limit of the content is preferably greater than 0%, more preferably 3.0% or more, even more preferably 6.0% or more, even more preferably 8.0% or more, and even more preferably 10.0% or more. On the other hand, Sr 2+ The content of is preferably limited to 35.0% or less, more preferably 30.0% or less, even more preferably 25.0% or less, even more preferably 22.0% or less, and even more preferably 20.0% or less.

[0025] Ba 2+The lower limit of the content is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, and even more preferably 2.0% or more. On the other hand, Ba 2+ The content of is preferably 15.0% or less, more preferably 13.0% or less, even more preferably 10.0% or less, even more preferably 9.0% or less, and even more preferably 8.0% or less.

[0026] La 3+ , Gd 3+ , Y 3+ Yb 3+ It is a component that maintains low dispersibility (high Abbe number), increases refractive index, and further enhances devitrification resistance. Therefore, La 3+ , Gd 3+ , Y 3+ Yb 3+ The content of each is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.5% or less, even more preferably 1.0% or less, even more preferably 0.8% or less, even more preferably 0.5% or less, even more preferably 0.25% or less, and even more preferably 0.1% or less. 3+ , Gd 3+ , Y 3+ Yb 3+ Since it is a component with high specific gravity, La is used from the perspective of obtaining low specific gravity optical glass. 3+ , Gd 3+ , Y 3+ Yb 3+ The content may be 0%.

[0027] Zn 2+ It has the property of lowering the glass transition temperature and improving the meltability and devitrification resistance of glass. Therefore, Zn 2+ The content of is preferably more than 0%, more preferably 0.2% or more, and even more preferably 0.5% or more. On the other hand, Zn 2+The content rate is preferably at most 15.0%, more preferably at most 12.0%, still more preferably at most 10.0%, further preferably at most 8.0%, still further preferably at most 5.0%, yet further preferably at most 2.0%, and still further preferably at most 1.0% as the upper limit, but the content rate may be 0%.

[0028] Li + , Na + and K + are components that improve the meltability and viscosity of glass, and have the property of lowering the glass transition temperature (Tg). In particular, Li + is more prone to + inducing devitrification during press molding than Na and K + .

[0029] Li + The content rate is preferably at most 2.0%, more preferably at most 1.5%, still more preferably less than 1.0%, further preferably at most 0.9%, still further preferably at most 0.8%, yet further preferably at most 0.7%, still further preferably at most 0.3%, yet further preferably at most 0.2%, and still further preferably at most 0.1% as the upper limit, but the glass does not necessarily have to contain it.

[0030] Na + The content rate is preferably at most 2.0%, more preferably at most 1.0%, still more preferably less than 0.5%, further preferably at most 0.4%, still further preferably at most 0.3%, yet further preferably at most 0.2%, and still further preferably at most 0.1% as the upper limit, but the glass does not necessarily have to contain it.

[0031] K + The content rate is preferably at most 2.0%, more preferably at most 1.0%, still more preferably at most 0.5%, further preferably at most 0.2%, and still further preferably at most 0.1% as the upper limit, but the glass does not necessarily have to contain it.

[0032] Si 4+ is a glass-forming component, and is a component that improves the devitrification resistance of glass. Therefore, Si 4+The content rate is preferably at most 10.0%, more preferably at most 5.0%, still more preferably at most 3.0%, even more preferably at most 1.0%, and most preferably 0% (not contained).

[0033] B 3+ is a glass-forming component and a component that improves the devitrification resistance of glass. Therefore, the content rate of B 3+ is preferably at most 10.0%, more preferably at most 5.0%, still more preferably at most 3.0%, even more preferably at most 1.0%, and most preferably 0% (not contained).

[0034] Nb 5+ is a component having the property of increasing the refractive index of glass. Therefore, the content rate of Nb 5+ is preferably at most 5.0%, more preferably at most 3.0%, still more preferably at most 1.0%, and even more preferably at most 0.5%. Since Nb 5+ is a component with high specific gravity, from the viewpoint of obtaining optical glass with low specific gravity, the content of Nb 5+ may be 0%.

[0035] W 6+ is a component having the property of increasing the refractive index of glass. Therefore, the content rate of W 6+ is preferably at most 3.0%, more preferably at most 2.0%, still more preferably at most 1.0%, and even more preferably at most 0.5%. Since W 6+ is a component with high specific gravity, from the viewpoint of obtaining optical glass with low specific gravity, the content of W 6+ may be 0%.

[0036] Zr 4+ is a component having the property of increasing the refractive index of glass. Therefore, the content rate of Zr 4+ is preferably at most 5.0%, more preferably at most 3.0%, still more preferably at most 1.0%, even more preferably at most 0.5%, and even still more preferably at most 0.3%.

[0037] Ta 5+ It is a component that has the property of increasing the refractive index of glass. Therefore, Ta 5+ The content of is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and even more preferably 0.5% or less.

[0038] Ge 4+ The content of is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably not contained.

[0039] Te 4+ The content of is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably not contained.

[0040] Sn 4+ The content of is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably not contained.

[0041] W 3+ Mo 6+ , Tb 3+ ,EU 3+ The content of is preferably 1.0% or less, more preferably 0.5% or less, even more preferably 0.1% or less, and most preferably not present at all.

[0042] [About anionic components] F - It has the property of increasing the Abbe number and the partial variance ratio. Therefore, F - The content of is preferably 50.0% or more, more preferably 53.0% or more, and even more preferably 55.0% or more as the lower limit. On the other hand, F - It has the property that when the content is high, the amount of volatilization increases and further lowers the refractive index. Therefore, F -The content of is preferably 90.0% or less, more preferably 85.0% or less, even more preferably 83.0% or less, and even more preferably 80.0% or less.

[0043] O 2- It has the property of suppressing devitrification of glass. Therefore, O 2- The content of is preferably 10.0% or more, more preferably 15.0% or more, even more preferably 18.0% or more, and even more preferably 20.0% or more as the lower limit. At the airport, 2- This makes it easier to obtain the effects of other anionic components, but it reduces the partial dispersion ratio, so O 2- The content of is preferably 50.0% or less, more preferably 48.0% or less, and even more preferably 45.0% or less.

[0044] Furthermore, from the viewpoint of suppressing glass devitrification, O 2- The content and F - The total content of is preferably 98.0% or more, more preferably 99.0% or more, and even more preferably 100%. 2- and F - Other anionic components, for example, Cl - YaBr - , I - The total content of one or more substances selected from the group consisting of the above is preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, even more preferably 0.10% or less, and most preferably 0%.

[0045] R 2+ Total content (R 2+ Mg 2+ Ca 2+ Sr 2+ and Ba 2+ By selecting one or more elements from the group consisting of the above, and setting the concentration within the range of 30.0-63.0%, it is possible to obtain glass with higher resistance to devitrification. Therefore, R 2+The total content of is preferably 30.0% or more, more preferably 33.0% or more, even more preferably 35.0% or more, even more preferably 38.0% or more, even more preferably 40.0% or more, and even more preferably 42.0% or more as the lower limit. Also, R 2+ The total content is preferably 63.0% or less, more preferably 60.0% or less, even more preferably 57.0% or less, and even more preferably 54.0% or less.

[0046] Ln 3+ Total content (Ln 3+ is, La 3+ , Gd 3+ , Y 3+ Yb 3+ By reducing the amount of one or more substances selected from the group consisting of the above to 3.0% or less, the fusion properties can be increased and the specific gravity can be reduced. Therefore, Ln 3+ The total content is preferably 3.0% or less, more preferably less than 3.0%, more preferably 2.0% or less, more preferably 1.0% or less, more preferably 0.8% or less, and more preferably 0.5% or less.

[0047] Rn + Total content (Rn + Li + na + and K + By keeping the amount of one or more elements selected from the group consisting of 2.0% or less, it is possible to suppress devitrification during press molding, improve moldability, and prevent a decrease in refractive index. Therefore, Rn + The total content is preferably 2.0% or less, more preferably 1.5% or less, even more preferably less than 1.0%, even more preferably 0.7% or less, and even more preferably 0.3% or less.

[0048] The optical glass of the present invention is F - Bi 3+ and Ti 4+ The ratio of the total amount multiplied by 100 (Bi 3+ +Ti 4+ ) × 100 / F- By setting the value to a range of greater than 0 to 3.60, it is possible to increase the partial variance ratio while suppressing low variance. Therefore, (Bi 3+ +Ti 4+ ) × 100 / F - The lower limit is preferably greater than 0, more preferably 0.10 or more, even more preferably 0.20 or more, even more preferably 0.30 or more, even more preferably 0.40 or more, and even more preferably 0.50 or more. On the other hand, (Bi 3+ +Ti 4+ ) × 100 / F - Preferably, the upper limit is 3.60 or less, more preferably 3.50 or less, and even more preferably 3.30 or less.

[0049] The optical glass of the present invention is La 3+ , Y 3+ Yb 3+ Gd for the total amount 3+ The ratio Gd 3+ / (La 3+ +Y 3+ +Yb 3+ By keeping the specific gravity below 1.60, the weight of the glass can be reduced. Therefore Gd 3+ / (La 3+ +Y 3+ +Yb 3+ The upper limit of the value is preferably 1.60 or less, more preferably 1.50 or less, even more preferably 1.30 or less, even more preferably 1.15 or less, even more preferably 1.00 or less, even more preferably 0.80 or less, and even more preferably 0.50 or less.

[0050] [Regarding other ingredients] Other components may be added to the optical glass of the present invention as needed, provided that they do not impair the properties of the glass of the present invention.

[0051] [Regarding ingredients that should not be included] Next, we will describe the components that should not be included in the optical glass of the present invention, and components that are undesirable to include.

[0052] Cations of transition metals such as Cu, Nd, V, Cr, Mn, Fe, Co, Ni, Ag, and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, can cause glass to color and absorb at specific wavelengths in the visible range, even when present in small amounts individually or in combination. Therefore, it is preferable that optical glass used in the visible range is substantially free of these cations.

[0053] The cations of Pb, As, Th, Cd, Tl, Os, Be, and Se have recently been increasingly discouraged from use as hazardous chemicals, and environmental measures are required not only in the glass manufacturing process but also in the processing and disposal of the finished product. Furthermore, the cation of S (sulfur) is also a hazardous chemical (SO4). x These can generate (etc.). Therefore, if environmental impact is a concern, the content of one or more of these should preferably be less than 1.0%, more preferably less than 0.5%, and most preferably, one or more of these should not be substantially present.

[0054] In this specification, "substantially absent" preferably means having a content of less than 0.1%, and more preferably means absent except for those present as unavoidable impurities.

[0055] While Sb and Ce cations are useful as defoaming agents, they are considered environmentally harmful components, and in recent years there has been a trend to avoid including them in optical glass. Therefore, for this reason, it is preferable that the optical glass of the present invention substantially does not contain Sb or Ce.

[0056] [Manufacturing method for optical glass] The method for manufacturing optical glass according to the present invention is not particularly limited. For example, the above raw materials are uniformly mixed so that each component is within a predetermined content range, the resulting mixture is placed in a quartz crucible, alumina crucible, or platinum crucible and roughly melted, then placed in a platinum crucible, a platinum alloy crucible, or an iridium crucible and melted at a temperature range of 800 to 1200°C for 2 to 10 hours, stirred and homogenized, and bubbles are removed, and then the temperature is lowered to 850°C or lower before being cast into a mold and slowly cooled.

[0057] [Physical properties] The optical glass of the present invention has a refractive index (n d Preferably, the refractive index (n) is 1.46000 or more and 1.54000 or less. More specifically, the lower limit of the refractive index of the optical glass of the present invention is preferably 1.46000 or more, more preferably 1.47000 or more, and even more preferably 1.48000 or more. On the other hand, the refractive index (n) of the optical glass of the present invention is preferably 1.46000 or more and 1.47000 or more. d The upper limit of ) is preferably 1.54000 or less, more preferably 1.53000 or less, and even more preferably 1.52000 or less.

[0058] The optical glass of the present invention has an Abbe number (ν d Preferably, the Abbe number (ν) is 65.00 or more and 88.00 or less. More specifically, the optical glass of the present invention has an Abbe number (ν) d The lower limit of the Abbe number (ν) is preferably 65.00 or higher, more preferably 66.00 or higher, even more preferably 67.00 or higher, even more preferably 68.00 or higher, even more preferably 69.00 or higher, and even more preferably 70.00 or higher. On the other hand, the optical glass of the present invention has an Abbe number (ν) d The upper limit of ) is preferably 95.00 or less, more preferably 93.00 or less, even more preferably 92.00 or less, even more preferably 91.00 or less, even more preferably 90.00 or less, even more preferably 88.00 or less, even more preferably 87.00 or less, even more preferably 86.00 or less, and even more preferably 85.00 or less.

[0059] The optical glass of the present invention has a high partial dispersion ratio (θg,F). More specifically, the partial dispersion ratio (θg,F) of the optical glass of the present invention is not particularly limited to an upper limit, but is preferably 0.5800 or less, and more preferably 0.5700 or less. On the other hand, the partial dispersion ratio (θg,F) of the optical glass of the present invention is preferably 0.5300 or more, more preferably 0.5350 or more, and even more preferably 0.5380 or more as the lower limit. Thus, the optical glass of the present invention has a higher partial dispersion ratio (θg,F) than conventionally known phthalic acid glass. Therefore, optical elements formed from this optical glass can be preferably used for correcting chromatic aberration.

[0060] Here, the Abbe number (ν) of the optical glass of the present invention d The partial variance ratio (θg,F) in relation to (θg,F=-0.0005ν) is preferably (θg,F=-0.0005ν d (+0.575) and more, more (θg, F = -0.0005ν) d (+0.577) or more, more preferably (θg, F = -0.0005ν d (+0.579) or more, more preferably (θg, F = -0.0005ν d (+0.581) or more, more preferably (θg, F = -0.0005ν d (+0.583) or higher. On the other hand, the Abbe number (ν) of the optical glass of the present invention d The upper limit of the partial variance ratio (θg,F) in relation to (θg,F = -0.0005ν) is not particularly limited, but preferably (θg,F = -0.0005ν). d (+0.605) or less, more preferably (θg, F = -0.0005ν) d It may also be set to +0.603 or less.

[0061] The specific gravity of the optical glass of the present invention is preferably 4.00 or less, more preferably 3.95 or less, more preferably 3.90 or less, more preferably 3.85 or less, and still more preferably 3.80 or less. As a highly dispersed component, La 3+ , Gd 3+ , Y 3+ Yb 3+ Rare earth oxides such as Ti4+ , Bi 3+ Nb 5+ , W 6+ One example is the high dispersion component, which tends to increase the specific gravity and cause devitrification compared to other components. Therefore, it is difficult to obtain glass with a lower specific gravity while having the same Abbe number, but the present invention has the characteristic of being more dispersed than conventional glass while having a lower specific gravity.

[0062] [Optical glass and optical elements] From the produced glass, a glass molded body can be manufactured using, for example, polishing, or mold press molding such as reheat press molding or precision press molding. However, the means for manufacturing the glass molded body are not limited to these methods.

[0063] The glass of the present invention can be used as optical glass and is useful for various optical elements and optical designs. Glass molded articles made from the glass of the present invention can be used for optical elements such as lenses, prisms, and mirrors. [Examples]

[0064] The composition of the optical glass of Examples 1 to 58 and Comparative Example 1 of the present invention (expressed in mol% in cation% or anion%), refractive index (n d ), Abbe number (ν d The results for the partial dispersion ratio (θg,F) and specific gravity are shown in Tables 1 and 2. Note that the following examples are for illustrative purposes only and the model is not limited to these examples.

[0065] In each example and comparative example, high-purity raw materials commonly used in fluorine phosphate glass, such as oxides, carbonates, nitrates, fluorides, and metaphosphate compounds, were selected as raw materials for each component. These were weighed to achieve the composition shown in the table for each example, and then uniformly mixed. The mixture was then placed in a platinum crucible, the crucible was covered, and heated in an electric furnace at 950-1100°C for 2 hours to melt the raw materials, stir and homogenize them, and remove bubbles. After that, the temperature was lowered to below 850°C, the mixture was cast into a mold, and slowly cooled to produce glass.

[0066] Refractive index (n) of the glass in the examples and comparative examples. d ), Abbe number (ν d The refractive index (n) was measured in accordance with the V-block method specified in JIS B 7071-2:2018. d The values ​​shown are measured values ​​for the d-line (587.56 nm) of a helium lamp. Also, the Abbe number (ν) d ) is the refractive index (n) of a helium lamp with respect to the d line. d ) and the refractive index (n) of the hydrogen lamp relative to the F line (486.13 nm). F ), refractive index (n) for the C line (656.27 nm) C Using the value of ), the Abbe number (ν d )=[(n d -1) / (n F -n C These refractive indices (n d ), Abbe number (ν d The temperature was determined by measuring the temperature of glass obtained by slow cooling at a rate of -25°C / hr. Furthermore, the partial dispersion ratio (θg,F) is the refractive index (n) of the Hg lamp with respect to the g line. g ) and the refractive index (n) of the hydrogen lamp relative to the F line (486.13 nm). F ), refractive index (n) for the C line (656.27 nm) C Using the value of ), the partial variance ratio (θg,F) = (n g -n F ) / (n F -n C These refractive indices (n) were calculated from the formula. d ), Abbe number (ν dThe partial dispersion ratio (θg,F) was determined by measuring the glass obtained by slow cooling at a rate of -25°C / hr.

[0067] Then, the Abbe number (ν) obtained by measurement d From the values ​​of (θg,F) and the partial variance ratio (θg,F), the relationship (θg,F) = -a × ν d We found the y-intercept b2 when the slope a is -0.0005 at +b.

[0068] The specific gravity of the glass in the examples was determined based on the method for measuring density and specific gravity using the liquid weighing method as specified in JIS Z 8807:2012.

[0069] [Table 1]

[0070] [Table 2]

[0071] The optical glass of the embodiment of the present invention has an Abbe number (ν d Because it has a large partial dispersion ratio (θg,F) relative to ) and a low specific gravity, it was suitable for correcting chromatic aberration.

[0072] Although the present invention has been described in detail above for illustrative purposes, it will be understood that these embodiments are for illustrative purposes only, and that many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. Expressed in anion % (mol %), F - The ingredient content is between 50.0% and 90.0%. The content of O2-component is between 10.0% and 50.0%. And, Expressed in cation percentage (mol%), Rn + The total content of the components is 2.0% or less (Rn + The ingredients are Li + Na + and K + (One or more species selected from the group consisting of) The P5+ component content is between 10.0% and 30.0%. The Al3+ component content is between 10.0% and 35.0%. The Mg2+ content is more than 0% and less than or equal to 15.0%. The Ca2+ component content is greater than 0% and less than or equal to 30.0%. The Sr2+ component content is greater than 0% and less than or equal to 35.0%. The Ba 2+ component content is greater than 0% and less than or equal to 15.0%. Gd3+ component content is 1.5% or less And, Ti 4+ The component is greater than 0% and less than or equal to 5.0% or Bi 3+ Contains ingredients in amounts greater than 0% but less than or equal to 5.0%. Partial dispersion ratio (θg, F), Abbe number (ν ｄ ) Expression showing the relationship with (θG, F)>-000005ν ｄ +0.575, A feature that satisfies the following conditions: Fluorophosphate-based optical glass.

2. Ln 3+ The total content of the components is 3.0% or less (Ln 3+ The ingredients are La 3+ , Gd 3+ , Y 3+ and Yb 3+ The optical glass according to claim 1, which is one or more selected from the group consisting of the following.

3. Cation ratio Gd 3+ / (La 3+ +Y 3+ +Yb 3+ The optical glass according to claim 1 or 2, wherein the coefficient of the optical glass is 1.60 or less.

4. An optical element made of optical glass according to claim 1 or 2.

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