Optical glass, optical components and preforms

Abstract

An optical glass having high dispersion with an Abbe number of 45 to 68, which maintains the characteristics of high refractive index and anomalous dispersion (Δθg, F), a preform using the optical glass, and an optical element are obtained. The optical glass contains 17.0 to 50.0% of P in terms of cation % (mol %). 5+ 3.0~20.0% Al 3+ , 33.0~60.0% R 2+ , expressed as cation % (mol %), Nb 5+ 、Ti 4+ and W 6+ Total content (Nb 5+ +Ti 4+ +W 6+ ) is 0% to 15.0%, Ln 3+ The total content is 2.0~40.0%, including O 2－ and F － As anionic components, the refractive index (n d ) is 1.50~1.67, and the Abbe number (ν d ) is 45 to 68, and the anomalous dispersion (Δθg, F) ​​is greater than 0.002.

Description

Technical Field

[0001] The present invention relates to an optical glass, an optical element and a preform. Background Art

[0002] Lens systems in optical devices are typically designed by combining multiple glass lenses with different optical properties. In recent years, the characteristics required of lens systems in optical devices have become increasingly diverse. To further enhance design flexibility, optical glasses with previously unattractive optical properties are being developed. Among these, optical glasses with anomalous dispersion (Δθg, F) ​​are attracting significant attention as being particularly effective at correcting chromatic aberration.

[0003] For example, Patent Documents 1 to 3 propose an optical glass having high anomalous dispersion in addition to the high refractive index, low dispersion, and excellent processability required in the past. 5+ 、Al 3+ , alkaline earth metal ions, etc. as cationic components, and contains F － and O 2－ as anionic components.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-55883

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2011-116649

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2011-126782 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] However, the optical glasses disclosed in Patent Documents 1 to 3 have low refractive indices or high Abbe numbers. Therefore, it is desired to develop optical glasses having a refractive index of 1.50 or higher and an Abbe number of 45 to 68 in the high refractive index and low dispersion range.

[0011] The present invention is proposed in view of the above-mentioned technical problems, and its purpose is to provide an optical glass that can maintain the characteristics of high refractive index and anomalous dispersion (Δθg, F) ​​in a fluorophosphate optical glass and has high dispersion with an Abbe number of 45 to 68, an optical element using the optical glass, and a preform.

[0012] Solutions to technical problems

[0013] The present inventors have completed the present invention after intensive research to solve the above technical problems. Specifically, the present invention provides the following products.

[0014] (1) an optical glass,

[0015] Expressed as cation % (mol %), it contains:

[0016] 17.0~50.0% P 5+ ,

[0017] 3.0~20.0% Al 3+ ,

[0018] 33.0~60.0% R 2+ ,

[0019] Expressed as cation % (mol%), Nb 5+ 、Ti 4+ and W 6+ Total content (Nb 5+ +Ti 4+ +W 6+ ) is 0% to 15.0%,

[0020] Ln 3+ The total content is 2.0~40.0%,

[0021] Contains O 2－ and F － As anionic components,

[0022] Refractive index (n d ) is 1.50~1.67, and the Abbe number (ν d ) is 45 to 68,

[0023] Anomalous dispersion (Δθg, F) ​​is 0.002 or more (Ln 3+ Is to choose Y 3+ 、La 3+ 、Gd 3+ 、Yb 3+ and Lu 3+ At least one of the groups R 2+ Is selected from Mg 2+ , Ca 2+ 、Sr 2+ 、Ba 2+ and Zn 2+ At least one of the groups consisting of . ).

[0024] (2) The optical glass according to (1), wherein

[0025] Expressed as cation % (mol %), it contains:

[0026] 0~25.0% Mg 2+ ,

[0027] 0~20.0% Ca 2+ ,

[0028] 10.0%~55.0% Ba 2+

[0029] 0 to less than 20.0% Sr 2+ ,

[0030] 0~25.0% Zn 2+ .

[0031] (3) The optical glass according to (1) or (2), wherein

[0032] Expressed as anion % (mol %), it contains:

[0033] 30.0-75.0% O 2－ ,

[0034] 25.0~65.0% F － .

[0035] (4) An optical element made of the optical glass described in any one of (1) to (3).

[0036] (5) A preform for grinding and / or precision press molding made of the optical glass described in any one of (1) to (3).

[0037] (6) An optical element formed by grinding the preform described in (5).

[0038] (7) An optical element formed by precision pressing the preform described in (5).

[0039] Effects of the Invention

[0040] According to the present invention, it is possible to provide an optical glass having a desired high refractive index and Abbe number and an anomalous dispersion (Δθg, F) ​​of 0.002 or greater, and an optical element and a preform using the optical glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The vertical axis is the partial dispersion ratio (θg, F) ​​and the horizontal axis is the Abbe number (ν d ) is a diagram of the standard line (Normal Line) represented by the rectangular coordinate system. DETAILED DESCRIPTION

[0042] The optical glass of the present invention contains P as a cationic component as an essential component. 5+ 、Al 3+ 、R 2+ , and Nb 5+ 、Ti 4+ , and W 6+ Total content (Nb 5+ +Ti 4+ +W 6+ ) is 0% to 15.0%, Ln 3+ The total content of is 2.0 to 40.0%, and contains O as an anion component 2－ and F － , thus, the refractive index (n d ) is 1.50~1.67, and the Abbe number (ν d ) is 45 to 68 and an anomalous dispersion (Δθg, F) ​​is 0.002 or more.

[0043] The optical glass of the present invention is described below. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the present invention. It should be noted that the description of the overlapping parts may be omitted, which does not limit the purpose of the invention.

[0044] <Glass composition>

[0045] Each component constituting the optical glass of the present invention will be described.

[0046] In this specification, the content of each component is expressed as cation % or anion % based on a molar ratio unless otherwise specified. Here, "cation %" and "anion %" (hereinafter also referred to as "cation % (mol %)" and "anion % (mol %)") refer to the composition of the optical glass of the present invention, dividing the glass composition into cationic components and anionic components, with the total ratio of each component being 100 mol %, and expressing the content of each component contained in the glass.

[0047] It should be noted that the ionic valence of each component is a representative value for convenience and is not used to distinguish it from other ionic valences. The ionic valence of each component in optical glass may also be a value other than the representative value. For example, P usually exists in glass with an ionic valence of 5, so in this specification, "P" is used. 5+ ", but it can also exist in the state of other ionic valences. Thus, although strictly speaking it can exist in the state of other ionic valences, in this specification, it is regarded that each component exists in the glass with the ionic valence of the representative value.

[0048] [About cationic ingredients]

[0049] P 5+ It is a glass forming component and an essential component. In particular, containing 17.0% or more of P can improve the devitrification resistance of glass. 5+ The lower limit of the content is preferably 17.0% or more, more preferably 20.0% or more, still more preferably 21.0% or more, further preferably 22.0% or more, further preferably 23.0% or more, and further preferably 24.0% or more.

[0050] On the other hand, P 5+ The content of 50.0% or less can inhibit P 5+ The decrease in refractive index and Abbe number can be reduced, and the decrease in chemical durability can be suppressed. 5+ The upper limit of the content is preferably 50.0% or less, more preferably 45.0% or less, still more preferably 43.0% or less, further preferably 40.0% or less, further preferably 38.0% or less, and further preferably less than 36.0%.

[0051] P 5+ , Al(PO3)3, Ca(PO3)2, Ba(PO3)2, Zn(PO3)2, BPO4, H3PO4, etc. can be used as raw materials.

[0052] Al 3+ It is an essential component, containing more than 3.0%, which can help form the skeleton of the glass's microstructure, thereby improving the resistance to devitrification and reducing wear. 3+ The lower limit of the content is preferably 3.0% or more, more preferably 4.0% or more, still more preferably 5.0% or more, and further preferably 5.5% or more.

[0053] On the other hand, by making Al 3+ The content of 20.0% or less can inhibit Al 3+ The refractive index and Abbe number are reduced, and the increase of glass transition point and yield point is suppressed. 3+ The upper limit of the content is preferably 20.0% or less, more preferably less than 15.0%, even more preferably 13.0% or less, further preferably less than 12.0%, further preferably less than 10.0%, and further preferably less than 9.0%.

[0054] Al 3+ , Al(PO3)3, AlF3, Al2O3, etc. can be used as raw materials.

[0055] B 3+ It is an optional component. When its content exceeds 0%, it can improve the refractive index and devitrification resistance of the glass.

[0056] On the other hand, by making B 3+ The content of B is 10.0% or less, which can suppress the deterioration of chemical durability. 3+ The content of B is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, further preferably less than 3.0%, further preferably 1.0% or less, and further preferably 0.5% or less. In particular, from the viewpoint of preventing the generation of striae due to volatilization of the glass, it is preferred not to contain B. 3+ .

[0057] B 3+ , H3BO3, Na2B4O7, BPO4, etc. can be used as raw materials.

[0058] Si 4+ It is an optional component. When the content is greater than 0%, it can improve the devitrification resistance of the glass, increase the refractive index, and reduce the abrasion resistance.

[0059] On the other hand, by making Si 4+ The content of 3.0% or less can reduce the 4+ Therefore, Si 4+ The content of is preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, and further preferably 0.5% or less.

[0060] Si 4+ , SiO2, K2SiF6, Na2SiF6, etc. can be used as raw materials.

[0061] Li + It is an optional component. When the content is greater than 0%, it is possible to maintain high devitrification resistance during glass formation and lower the glass transition point.

[0062] On the other hand, by making Li + When the content of Li is less than 10.0%, a stable glass can be obtained, which can reduce the maximum value of the expansion coefficient. In addition, the reduction of the refractive index can be suppressed. + The content of is preferably 10.0% or less, more preferably 5.0% or less, still more preferably less than 1.0%, and further preferably less than 0.5%.

[0063] Li + , Li2CO3, LiNO3, LiF, etc. can be used as raw materials.

[0064] Na +It is an optional component. When the content is greater than 0%, it is possible to maintain high devitrification resistance during glass formation and to lower the glass transition point.

[0065] On the other hand, by making Na + When the content of Na is less than 10.0%, a stable glass can be obtained, which can reduce the maximum value of the expansion coefficient. In addition, the reduction of the refractive index can be suppressed. + The content of is preferably 10.0% or less, more preferably 5.0% or less, still more preferably less than 1.0%, and further preferably less than 0.5%.

[0066] Na + , Na2CO3, NaNO3, NaF, etc. can be used as raw materials.

[0067] K + It is an optional component. When the content is greater than 0%, it is possible to maintain high devitrification resistance during glass formation and to lower the glass transition point.

[0068] On the other hand, by making K + When the content of K is less than 10.0%, a stable glass can be obtained, which can reduce the maximum value of the expansion coefficient. In addition, the reduction of the refractive index can be suppressed. Therefore, K + The content of is preferably 10.0% or less, more preferably 5.0% or less, still more preferably less than 3.0%, and further preferably less than 1.0%.

[0069] K + , K2CO3, KNO3, KF, KHF2, K2SiF6, etc. can be used as raw materials.

[0070] Alkali metals are selected from Li + 、Na + and K + At least one of the group consisting of. + 、Na + and K + At least one of the groups is recorded as Rn + In addition, Rn + The total content refers to the total content of one or more of these three ions (e.g. Li + +Na + +K + ).

[0071] Mg 2+ It is an optional component. When the content is greater than 0%, it can improve the devitrification resistance of the glass, reduce friction and improve workability. 2+The content of is preferably greater than 0%, more preferably 1.0% or more, still more preferably 2.0% or more, and further preferably 3.0% or more.

[0072] On the other hand, by making Mg 2+ The content of Mg is 30.0% or less, which can inhibit the excessive inclusion of Mg 2+ This causes the glass to lose clarity and reduce its refractive index. 2+ The content of is preferably 30.0% or less, more preferably 26.0% or less, still more preferably 24.0% or less, further preferably 20.0% or less, and further preferably 16.0% or less.

[0073] Mg 2+ , MgO, MgF2, etc. can be used as raw materials.

[0074] Ca 2+ It is an optional component. When the content is greater than 0%, the devitrification resistance of the glass can be improved.

[0075] Therefore, Ca 2+ The lower limit of the content is preferably greater than 0%, more preferably 1.0% or more, still more preferably 2.0% or more, further preferably 2.5% or more, and even more preferably 3.0% or more.

[0076] On the other hand, by making Ca 2+ The content of 30.0% or less can inhibit the excessive presence of Ca 2+ This causes the glass to lose clarity and reduce its refractive index. 2+ The content is preferably 30.0% or less, more preferably 26.0% or less, still more preferably 23.0% or less, further preferably 20.0% or less, further preferably 15.0% or less, further preferably less than 14.0%, and further preferably 12.0% or less.

[0077] Ca 2+ , Ca(PO3)2, CaCO3, CaF2, etc. can be used as raw materials.

[0078] Sr 2+ It is an optional component. When the content is greater than 0%, it can improve the devitrification resistance of the glass and suppress the decrease in the refractive index. 2+ The content of is preferably greater than 0%, more preferably 1.0% or more, still more preferably 2.0% or more, and further preferably 3.0% or more.

[0079] On the other hand, by making Sr 2+ The content is less than 20.0%, which can inhibit the excessive presence of Sr 2+This causes the glass to lose clarity and reduce its refractive index. 2+ The content of is preferably less than 20.0%, more preferably 18.0% or less, still more preferably 15.0% or less, further preferably 10.0% or less, and further preferably 5.0% or less.

[0080] Sr 2+ , Sr(NO3)2, SrF2, etc. can be used as raw materials.

[0081] Ba 2+ Ba is an essential component, containing more than 10.0%, which can lower the glass transition point and yield point, improve the resistance to devitrification, increase the Abbe number, and increase the refractive index. 2+ The content of is preferably 10.0% or more, more preferably 15.0% or more, still more preferably 20.0% or more, further preferably 25.0% or more, and further preferably 30.0% or more.

[0082] On the other hand, by making Ba 2+ The content of Ba is 55.0% or less, which can inhibit the excessive inclusion of Ba 2+ Therefore, the glass is subjected to a reduction in the resistance to devitrification. 2+ The content of is preferably 55.0% or less, more preferably 53.0% or less, still more preferably 50.0% or less, and further preferably 48.0% or less.

[0083] Ba 2+ , Ba(PO3)2, BaCO3, Ba(NO3)2, BaF2, etc. can be used as raw materials.

[0084] Zn 2+ It is an optional component. When the content is greater than 0%, the devitrification resistance of the glass can be improved.

[0085] On the other hand, by making Zn 2+ The content of Zn is 25.0% or less, which can suppress the decrease of refractive index. 2+ The content of is preferably 25.0% or less, more preferably 20.0% or less, still more preferably 15.0% or less, and further preferably 13.0% or less.

[0086] Zn 2+ , Zn(PO3)2, ZnO, ZnF2, etc. can be used as raw materials.

[0087] Alkaline earth metals are selected from Sr 2+ 、Ba 2+ Mg 2+ , Ca 2+ and Zn 2+In addition, sometimes R 2+ Indicates selection from Sr 2+ 、Ba 2+ Mg 2+ , Ca 2+ and Zn 2+ One or more types of groups.

[0088] In addition, R 2+ The total content refers to the total content of one or more of these five ions (e.g. Sr 2+ +Ba 2+ +Mg 2+ +Ca 2 + +Zn 2+ ).

[0089] Y 3+ It is an optional component. When the content is greater than 0%, it can maintain a high refractive index and a high Abbe number and improve the resistance to devitrification. 3+ The content of is preferably greater than 0%, more preferably 0.5% or more, still more preferably 1.0% or more, and further preferably 2.0% or more.

[0090] On the other hand, by making Y 3+ The content of Y is below 25.0%, which can reduce the 3+ The devitrification caused by this can reduce the material cost of the glass and reduce the specific gravity. In addition, it can inhibit the increase of the glass transition point and the yield point. 3+ The content of is preferably 25.0% or less, more preferably 20.0% or less, still more preferably 15.0% or less, further preferably 10.0% or less, and still further preferably 8.0% or less.

[0091] Y 3+ , Y2O3, YF3, etc. can be used as raw materials.

[0092] La 3+ It is an optional component. When the content is greater than 0%, it can maintain a high refractive index and a high Abbe number and improve the resistance to devitrification. 3+ The content of is preferably greater than 0%, more preferably greater than 0.1%, still more preferably greater than 0.3%, and further preferably greater than 0.5%.

[0093] On the other hand, by making La 3+ The content of La is less than 15.0%, which can reduce the 3+ The devitrification caused by this can reduce the material cost of the glass and reduce the specific gravity. In addition, it can inhibit the increase of the glass transition point and the yield point.3+ The content of is preferably 15.0% or less, more preferably 10.0% or less, still more preferably 8.0% or less, further preferably 6.0% or less, and still further preferably 3.5% or less.

[0094] La 3+ , La2O3, LaF3, etc. can be used as raw materials.

[0095] Gd 3+ It is an optional component. When the content is greater than 0%, it can maintain a high refractive index and a high Abbe number and improve the resistance to devitrification. 3+ The content of is preferably greater than 0%, more preferably 0.5% or more, and even more preferably 1.0% or more.

[0096] On the other hand, by making Gd 3+ The content of Gd is less than 25.0%, which can reduce the 3+ The devitrification caused by this can reduce the material cost of the glass and reduce the specific gravity. In addition, it can inhibit the increase of the glass transition point and the yield point. 3+ The content of is preferably 25.0% or less, more preferably 20.0% or less, still more preferably 18.0% or less, and further preferably 15.0% or less.

[0097] Gd 3+ , Gd2O3, GdF3, etc. can be used as raw materials.

[0098] Yb 3+ It is an optional component. When the content is greater than 0%, it can maintain a high refractive index and a high Abbe number and improve the resistance to devitrification. 3+ The content of is preferably greater than 0%, more preferably 0.1% or more, and even more preferably 0.5% or more.

[0099] On the other hand, by making Yb 3+ The content of Yb is less than 10.0%, which can reduce the 3+ The devitrification caused by Yb can be reduced, and the material cost of the glass can be reduced and the specific gravity can be reduced. In addition, the increase of the glass transition point and the yield point can be suppressed. 3+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, further preferably 2.5% or less, and still further preferably 1.0% or less.

[0100] Yb 3+ , Yb2O3, YbF3, etc. can be used as raw materials.

[0101] Lu 3+It is an optional component. When the content is greater than 0%, it can maintain a high refractive index and a high Abbe number and improve the resistance to devitrification. 3+ The content of is preferably greater than 0%, more preferably 0.5% or more, and even more preferably 1.0% or more.

[0102] On the other hand, by making Lu 3+ The content of Lu is less than 10.0%, which can reduce the risk of excessive Lu 3+ The devitrification caused by this can reduce the material cost of the glass and reduce the specific gravity. In addition, this can inhibit the increase of the glass transition point and the yield point. 3+ The content of is preferably 10.0% or less, more preferably 8.0% or less, and still more preferably 5.0% or less.

[0103] Lu 3+ , Lu2O3, LuF3, etc. can be used as raw materials.

[0104] Ln 3+ It means, choose from La 3+ 、Gd 3+ 、Y 3+ 、Yb 3+ and Lu 3+ At least one of the groups consisting of 3+ The total content of these five ions (La 3+ +Gd 3+ +Y 3+ +Yb 3+ +Lu 3+ ).

[0105] Ti 4+ It is an optional component. When the content is greater than 0%, it can increase the refractive index of the glass and improve chemical durability. In addition, it can suppress the decrease in the Abbe number and has the property of reducing coloration.

[0106] On the other hand, by making Ti 4+ 8.0% or less can improve the devitrification resistance. 4+ The content of is 8.0% or less, more preferably 7.0% or less, still more preferably 6.0% or less, further preferably 5.0% or less.

[0107] Ti 4+ , for example, TiO2 can be used as a raw material and included in the glass.

[0108] Nb 5+It is an optional component. When the content is greater than 0%, it can increase the refractive index of the glass and improve the chemical durability. In addition, it has the property of suppressing the decrease of the Abbe number and the increase of the melting temperature. 5+ The content of is preferably greater than 0%, more preferably 1.0% or more, and even more preferably 2.0% or more.

[0109] On the other hand, by making Nb 5+ 8.0% or less can improve the devitrification resistance. 5+ The content of is 8.0% or less, more preferably 6.0% or less, still more preferably 4.0% or less, further preferably 3.0% or less.

[0110] Nb 5+ , for example, Nb2O5 can be used as a raw material and included in the glass.

[0111] Zr 4+ It is an optional component. When its content is greater than 0%, it can increase the refractive index of the glass.

[0112] On the other hand, by making Zr 4+ The content of Zr is 10.0% or less, which can reduce the wave streaks in the glass caused by the volatilization of the components in the glass. 4+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and further preferably 3.0% or less.

[0113] Zr 4+ , ZrO2, ZrF4, etc. can be used as raw materials.

[0114] W 6+ It is an optional component. When the content is greater than 0%, it increases the refractive index of the glass and improves chemical durability. It also has the property of suppressing the decrease in the Abbe number and reducing coloration.

[0115] Therefore, W 6+ The content of is preferably greater than 0%, more preferably 0.1% or more, and even more preferably 0.5% or more.

[0116] On the other hand, when W 6+ When the content of W is 8.0% or less, the decrease in refractive index can be suppressed, and the decrease in Abbe number can also be suppressed. 6+ The content of Mg is preferably 8.0% or less, more preferably 6.0% or less, still more preferably 4.0% or less, further preferably 3.0% or less.

[0117] W 6+ , for example, WO3 can be used as a raw material and included in the glass.

[0118] Ge 4+ It is an optional component. When its content is greater than 0%, it can increase the refractive index of the glass and improve the devitrification resistance.

[0119] On the other hand, by making Ge 4+ The content of Ge is less than 10.0%, which can reduce the expensive Ge 4+ Therefore, the material cost of glass can be reduced. 4+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and further preferably 3.0% or less.

[0120] Ge 4+ , GeO2 and the like can be used as raw materials.

[0121] Ta 5+ It is an optional component. When its content is greater than 0%, it can increase the refractive index of the glass.

[0122] On the other hand, by making Ta 5+ The content of Ta is 10.0% or less, which can reduce the devitrification of glass. 5+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and further preferably 3.0% or less.

[0123] Ta 5+ , Ta2O5 and the like can be used as raw materials.

[0124] Bi 3+ It is an optional component. When its content is greater than 0%, it can increase the refractive index of the glass and lower the glass transition point.

[0125] On the other hand, by making Bi 3+ The content of Bi is 10.0% or less, which can suppress the reduction of visible light transmittance caused by devitrification and coloring of the glass. 3+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and further preferably 3.0% or less.

[0126] Bi 3+ , Bi2O3 and the like can be used as raw materials.

[0127] Te 4+ It is an optional component. When its content is greater than 0%, it can increase the refractive index of the glass and reduce coloring.

[0128] On the other hand, by making Te 4+The content of Te is 10.0% or less, which can suppress the reduction of visible light transmittance caused by devitrification and coloring of the glass. 4+ The content of is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and further preferably 3.0% or less.

[0129] Te 4+ , TeO2 and the like can be used as raw materials.

[0130] R 2+ The total content of is preferably 33.0% or more and 60.0% or less.

[0131] In particular, by making R 2+ When the content of R is 33.0% or more, a glass with higher resistance to devitrification can be obtained. 2+ The total content of is preferably 33.0% or more, more preferably 35.0% or more, still more preferably 36.0% or more, further preferably 37.0% or more, and further preferably 38.0% or more.

[0132] On the other hand, by making R 2+ The content of R is below 60.0%, which can reduce the 2+ Therefore, R 2+ The total content of is preferably 60.0% or less, more preferably 55.0% or less, still more preferably 53.0% or less, and further preferably 50.0% or less.

[0133] Rn + When the total content of Rn is greater than 0%, the devitrification resistance of the glass can be maintained at a high level and the glass transition point can be lowered. + The total content of is preferably greater than 0%, more preferably 0.4% or more, and further preferably 0.7% or more.

[0134] On the other hand, by making Rn + The upper limit of Rn is 5.0% or less, which can suppress the decrease of refractive index. + The total content of is preferably 5.0% or less, more preferably 4.0% or less, still more preferably 3.0% or less, and further preferably 2.0% or less.

[0135] By making Ln 3+ The total content of Ln is 2.0% or more, which can maintain a high refractive index and a high Abbe number while improving the resistance to devitrification. 3+ The total content of is preferably 2.0% or more, more preferably 4.0% or more, still more preferably 6.0% or more, and further preferably 8.0% or more.

[0136] On the one hand, by making Ln 3+ The total content of Ln is 40.0% or less, which can reduce the 3+ The devitrification caused by Ln can reduce the material cost and specific gravity of glass. 3+ The total content of is preferably 40.0% or less, more preferably 30.0% or less, still more preferably 25.0% or less, further preferably 23.0% or less, and still further preferably 21.0% or less.

[0137] In the optical glass of the present invention, Nb 5+ 、Ti 4+ 、W 6+ When the total content of Nb is greater than 0%, a high refractive index can be achieved and the chemical durability can be improved. 5+ +Ti 4+ +W 6+ ) is preferably greater than 0%, more preferably greater than 0.5%, and even more preferably greater than 0.9%.

[0138] On the other hand, by making the upper limit 15.0%, it is possible to suppress the decrease in the Abbe number. 5+ +Ti 4+ +W 6+ ) is preferably 15.0% or less, more preferably 12.0% or less, still more preferably 10.0% or less, and further preferably 9.0% or less.

[0139] Al 3+ / P 5+ When Al is contained in an amount of 0.05 or more, uniformity can be improved and chemical durability can be improved. 3+ / P 5+ , preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.15 or more.

[0140] On the other hand, by making Al 3+ / P 5+ The upper limit of Al is 0.35 or less, which can suppress the deterioration of the uniformity of the molten glass during glass production. 3+ / P 5+ , preferably 0.35 or less, more preferably 0.30 or less, still more preferably 0.28 or less.

[0141] Ba 2+ / R 2+ When Ba is contained at 0.40 or more, the glass is stable and devitrification can be reduced. 2+ / R 2+The content of is preferably 0.40 or more, more preferably 0.43 or more, and even more preferably 0.45 or more.

[0142] On the other hand, by making Ba 2+ / R 2+ The upper limit of Ba is 1.00 or less, which can suppress the decrease of refractive index and Abbe number. 2+ / R 2+ The content of is preferably 1.00 or less, more preferably 0.95 or less, and still more preferably 0.90 or less.

[0143] Sr 2+ / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ ), when Sr is contained in an amount greater than 0, the glass is stable and devitrification can be reduced. 2+ / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ ) content is preferably greater than 0, more preferably 0.03 or more, and even more preferably 0.05 or more.

[0144] On the other hand, by making Sr 2+ / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ ) is 0.35 or less, which can suppress the decrease in refractive index. 2+ / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ ) is preferably 0.35 or less, more preferably 0.30 or less, still more preferably 0.20 or less, and further preferably 0.15 or less.

[0145] Sr 2+ / (Li + +Na + +K + ), when Sr is contained in an amount greater than 0, it is possible to maintain high resistance to devitrification during glass formation. 2+ / (Li + +Na + +K + ) content is preferably greater than 0, more preferably 2.00 or more, still more preferably 3.00 or more, and further preferably 4.00 or more.

[0146] On the other hand, by making Sr 2+ / (Li + +Na + +K + ) is 15.00 or less, a high refractive index can be obtained, and ribs are unlikely to be generated. 2+ / (Li + +Na + +K + ) content is preferably 15.00 or less, more preferably 13.00 or less, still more preferably 10.00 or less, and further preferably 8.00 or less.

[0147] F + / P 5+ When the content is 0.70 or more, the glass is stable and devitrification can be reduced. + / P 5+ The content of is preferably 0.70 or more, more preferably 0.80 or more, still more preferably 0.90 or more, and further preferably 1.00 or more.

[0148] On the other hand, F + / P 5+ When the content is 2.50 or less, it can have high anomalous dispersion. + / P 5+ The content of is preferably 2.50 or less, more preferably 2.30 or less, still more preferably 2.00 or less, and further preferably 1.80 or less.

[0149] [About anionic components]

[0150] The optical glass of the present invention contains O 2－ .O 2－ The content of MgO is preferably, for example, 30.0% to 75.0%.

[0151] In particular, by containing 30.0% or more of O 2－ , can suppress the devitrification of glass and suppress the increase of wear resistance. 2－ The content of is preferably 30.0% or more, more preferably 40.0% or more, still more preferably 45.0% or more, and further preferably 52.0% or more.

[0152] On the other hand, by making O 2－ The content of O is 75.0% or less, and the effects of other anionic components can be easily obtained. 2－ The content of is preferably 75.0% or less, more preferably 70.0% or less, still more preferably 66.0% or less, further preferably 63.0% or less, and still further preferably 61.0% or less.

[0153] O2－ As raw materials, oxides of various cationic components such as Al2O3, MgO, and BaO, and phosphates of various cationic components such as Al(PO)3, Mg(PO)2, and Ba(PO)2 can be used.

[0154] The optical glass of the present invention contains F － . F － The content of Mg is preferably, for example, not less than 25.0% and not more than 65.0%.

[0155] In particular, by containing 25.0% or more of F － , can improve the anomalous dispersion and Abbe number of the glass, and can improve the resistance to devitrification of the glass. － The content of is preferably 25.0% or more, more preferably 27.0% or more, still more preferably 30.0% or more, further preferably 35.0% or more, and still further preferably 39.0% or more.

[0156] On the other hand, by setting the F- content to 65.0% or less, the reduction in glass abrasiveness can be suppressed. Therefore, the F- content is preferably 65.0% or less, more preferably 60.0% or less, even more preferably 55.0% or less, further preferably 50.0% or less, and even more preferably 48.0% or less.

[0157] In addition, from the viewpoint of suppressing the devitrification of glass, 2－ The content and F － The upper limit of the total content is preferably 98.0% or more, more preferably 99.0% or more, and still more preferably 100%.

[0158] F － , fluorides of various cationic components such as AlF3, MgF2, BaF2, etc. can be used as raw materials.

[0159] By making F － / (F － +O 2－ ) is 0.35 or more, the anomalous dispersion and Abbe number of the glass can be improved, and the devitrification resistance of the glass can be improved. － / (F － +O 2－ ), preferably 0.35 or more, more preferably 0.36 or more, still more preferably 0.37 or more, further preferably 0.38 or more.

[0160] On the other hand, by making F － / (F － +O 2－ ) is 0.55 or less, which can reduce the wave striae of the glass caused by the volatilization of the components in the glass.－ / (F － +O 2－ ), preferably 0.55 or less, more preferably 0.53 or less, still more preferably 0.50 or less, further preferably 0.49 or less.

[0161] [About other ingredients]

[0162] To the optical glass of the present invention, other components may be added as needed within a range that does not impair the properties of the glass of the present invention.

[0163] [About ingredients that should not be contained]

[0164] Next, components that should not be contained in the optical glass of the present invention and components that are preferably not contained are described.

[0165] Other components not mentioned above may be added as needed within a range that does not impair the properties of the glass of the present invention. However, transition metal components such as Ce, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, even when contained in small amounts alone or in combination, can color the glass and absorb specific wavelengths in the visible region, thereby reducing the visible light transmittance-enhancing effect of the present invention. Therefore, they are preferably substantially absent from optical glasses that transmit wavelengths in the visible region, particularly in optical glasses that transmit wavelengths in the visible region.

[0166] In recent years, there has been a trend to control the use of cations such as Pb, Th, Cd, Tl, Os, Be, and Se as harmful chemical substances. This requires environmental countermeasures not only in the glass manufacturing process but also in the processing and post-product handling. Therefore, given the importance of environmental impact, it is preferable to substantially exclude these cations, except for unavoidable inclusions. Thus, the optical glass is substantially free of environmentally polluting substances. Consequently, the optical glass can be manufactured, processed, and discarded without the need for special environmental countermeasures.

[0167] Although Sb and Ce cations are useful as degassing agents, they are harmful to the environment, and in recent years there has been a trend to exclude them from optical glass. Therefore, based on this point, the optical glass of the present invention preferably does not contain Sb and Ce.

[0168] [Manufacturing method]

[0169] The method for producing the optical glass of the present invention is not particularly limited. For example, the raw materials are uniformly mixed so that the contents of the components are within a specified range. The resulting mixture is initially melted in a quartz crucible, an alumina crucible, or a platinum crucible. The mixture is then melted in a platinum crucible, a platinum alloy crucible, or an iridium crucible at a temperature of 900 to 1200°C for 2 to 10 hours. The mixture is then stirred for homogenization and defoaming. The optical glass is then finally stirred at a temperature below 900 to 750°C to remove ribs. The mixture is then cast into a mold and slowly cooled.

[0170] [physical properties]

[0171] The optical glass of the present invention has a high refractive index in the high refractive index and low dispersion region.

[0172] The refractive index (n d ) is preferably 1.50 or more, more preferably 1.52 or more, even more preferably 1.54 or more, and further preferably 1.56 or more. On the other hand, the upper limit of the refractive index is preferably 1.67 or less, more preferably 1.66 or less, and even more preferably 1.65 or less.

[0173] In addition, the Abbe number (ν d ) is preferably 45 or more, more preferably 47 or more, and even more preferably 50 or more, and the upper limit is preferably 68 or less, more preferably 67 or less, and even more preferably 65 or less.

[0174] Here, the partial dispersion ratio (θg, F) ​​and the anomalous dispersion (Δθg, F) ​​are described, and then the physical properties of the optical glass of the present invention are described in more detail.

[0175] First, the partial dispersion ratio (θg, F) ​​will be described.

[0176] The partial dispersion ratio (θg, F) ​​is represented by the ratio of the difference between the refractive indexes in two wavelength regions in the wavelength dependency of the refractive index, and is expressed by the following formula (1).

[0177] θg, F=(ng-nF) / (nF-nC)······Equation (1)

[0178] Here, ng refers to the refractive index of the g-line (435.83 nm), nF refers to the refractive index of the F-line (486.13 nm), and nC refers to the refractive index of the C-line (656.27 nm).

[0179] Then, the partial dispersion ratio (θg, F) ​​is compared with the Abbe number (ν d) is plotted on an XY graph. In the case of general optical glass, it is generally plotted on a straight line called a standard line. The standard line is a line with the partial dispersion ratio (θg, F) ​​as the vertical axis and the Abbe number (ν d ) is the horizontal axis of the XY graph (on rectangular coordinates), the partial dispersion ratios and Abbe numbers of NSL7 and PBM2 are plotted, and the rightward rising straight line obtained by connecting these two points (refer to Figure 1 The standard glass used as the basis for the standard line varies depending on the optical glass manufacturer, but each company uses roughly the same slope and intercept to define it (NSL7 and PBM2 are optical glasses manufactured by Ohara Co., Ltd., and the Abbe number (ν d ) is 60.5, the partial dispersion ratio (θg, F) ​​is 0.5436, the Abbe number (νd) of PBM2 is 36.3, and the partial dispersion ratio (θg, F) ​​is 0.5828).

[0180] In contrast to the partial dispersion ratio (θg, F), anomalous dispersion (Δθg, F) ​​represents the relationship between the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ) plotted along the vertical axis deviates from the standard line. Optical elements made of glass with high anomalous dispersion (Δθg, F) ​​have the property of correcting chromatic aberration caused by other lenses in the near-blue wavelength range.

[0181] After intensive research, the inventors have successfully developed a glass with an Abbe number (ν d ) is an optical glass with a higher value of anomalous dispersion (Δθg, F).

[0182] For example, in the case of the preferred optical glass described below as an example, it is possible to obtain an optical glass having an Abbe number (ν d ) is about 50 to 68, the partial dispersion ratio (θg, F) ​​is 0.535 or more, and the anomalous dispersion (Δθg, F) ​​is also 0.0020 or more. The values ​​of the partial dispersion ratio (θg, F) ​​and the anomalous dispersion (Δθg, F) ​​are the same as those of the optical glass with the same Abbe number (ν d ) is significantly higher than existing glass.

[0183] The optical glass of the present invention is characterized by the partial dispersion ratio (θg, F). Therefore, it is easy to obtain an optical glass capable of correcting chromatic aberration with high precision.

[0184] The partial dispersion ratio (θg, F) ​​is 0.510 or greater, preferably 0.520 or greater, more preferably 0.530 or greater, and even more preferably 0.535 or greater. It should be noted that the partial dispersion ratio (θg, F) ​​of the optical glass of the present invention is preferably 0.580 or less, more preferably 0.576 or less, and even more preferably 0.573 or less.

[0185] In addition, the partial dispersion ratio described in the present invention refers to the partial dispersion ratio in the short wavelength region.

[0186] The optical glass of the present invention has high anomalous dispersion (Δθg, F), and therefore, can easily provide a lens capable of correcting chromatic aberration with high precision.

[0187] The anomalous dispersion (Δθg, F) ​​is preferably 0.002 or greater, more preferably 0.005 or greater, still more preferably 0.007 or greater, further preferably 0.090 or greater, further more preferably 0.011 or greater, and further more preferably 0.013 or greater.

[0188] On the other hand, the upper limit of the anomalous dispersion (Δθg,F) of the optical glass of the present invention is preferably 0.030 or less, more preferably 0.028 or less, still more preferably 0.026 or less, further preferably 0.024 or less, and even more preferably 0.022 or less.

[0189] [Preform and Optical Element]

[0190] The produced optical glass can be used to produce a glass molded body using a press molding method such as reheating press molding or precision press molding. Specifically, a preform for press molding can be produced from the optical glass, and the preform can be press molded and then ground to produce a glass molded body. Alternatively, a preform produced by grinding or a preform formed by a known float process can be precision press molded to produce a glass molded body. It should be noted that the method for producing a glass molded body is not limited to the above method.

[0191] The glass molded article thus produced can be used in a variety of optical components and optical designs. In particular, the optical glass of the present invention is preferably used to manufacture optical components such as lenses, prisms, and reflectors using methods such as precision press molding. Consequently, when these optical components are used in optical devices that transmit visible light, such as cameras and projectors, they can achieve high-definition and high-precision imaging characteristics, while also reducing the weight of the optical systems of these devices.

[0192] [Example]

[0193] The compositions (expressed as cation % or anion % in mole %), refractive index (n d ), Abbe number (ν d ), partial dispersion ratio (θg, F) ​​and anomalous dispersion (Δθg, F) ​​are shown in Tables 1 to 9. It should be noted that the following embodiments are only for illustration and are not limited to these embodiments.

[0194] The optical glasses of the embodiments and comparative examples are all made of high-purity raw materials such as various corresponding oxides, carbonates, nitrates, fluorides, and metaphosphate compounds used in conventional fluorophosphate glasses. The raw materials are weighed to obtain the proportions of the combinations shown in the table and uniformly mixed. The mixture is then placed in a platinum crucible and melted in an electric furnace at a temperature range of 900 to 1250° C. for 2 to 10 hours depending on the melting difficulty of the glass composition. After stirring for homogenization and defoaming, the temperature is lowered to below 900° C., cast into a mold, and slowly cooled to produce the glass.

[0195] The refractive index (n d ) and the Abbe number (ν d ), expressed using the value measured for the d line (587.56 nm) of a helium lamp. d ), using the refractive index of the d line, the refractive index of the F line (486.13nm) of the hydrogen lamp (nF), and the refractive index of the C line (656.27nm) (nC), the Abbe number (ν d )=[(n d -1) / (nF-nC)] is calculated.

[0196] In addition, the partial dispersion ratio is calculated by measuring the refractive index nC of the C line (wavelength 656.27nm), the refractive index nF of the F line (wavelength 486.13nm), and the refractive index ng of the g line (wavelength 435.83nm) using the formula (θg, F) ​​= (ng-nF) / (nF-nC). Then, the measured Abbe number (ν d ) Figure 1 The anomalous dispersion (Δθg, F) ​​is calculated by taking the difference between the value of the partial dispersion ratio (θg, F) ​​on the standard line and the measured value of the partial dispersion ratio (θg, F).

[0197]

Table 1

[0198]

[0199]

Table 2

[0200]

[0201]

Table 3

[0202]

[0203]

Table 4

[0204]

[0205]

Table 5

[0206]

[0207]

Table 6

[0208]

[0209]

Table 7

[0210]

[0211]

Table 8

[0212]

[0213]

Table 9

[0214]

[0215] As shown in Tables 1 to 9, the refractive index of the optical glasses of the Examples was all above 1.50, more specifically, above 1.52, falling within the required range. On the other hand, the refractive index of the glasses of the Comparative Examples was 1.4982, below 1.50. Therefore, it can be seen that the refractive index of the optical glasses of the Examples of the present invention is higher than that of the glasses of the Comparative Examples.

[0216] Furthermore, the optical glasses of the examples of the present invention all had an Abbe number of 45 or greater, more specifically, 47 or greater, and an Abbe number of 68 or less, more specifically, 67 or less, falling within the required range. On the other hand, the glass of the comparative example had an Abbe number of 79.1, which was 68 or greater. Therefore, it can be seen that the optical glasses of the examples of the present invention had lower Abbe numbers than the glass of the comparative example.

[0217] In addition, the optical glasses of Examples all had partial dispersion ratios (θg, F) ​​of 0.510 or greater, and anomalous dispersion (Δθg, F) ​​of 0.002 or greater.

[0218] Therefore, it can be seen that the optical glass of the example has a desired high refractive index, an Abbe number within a desired range, and high anomalous dispersion (Δθg, F).

[0219] Although the present invention has been described in detail above for the purpose of illustration, the present embodiment is merely illustrative and it should be understood that those skilled in the art can make various modifications without departing from the spirit and scope of the present invention.

Claims

1. An optical glass, Expressed as cation % in mole %, it contains: 17.0% to 50.0% P 5+ , 3.0% or more and less than 10.0% Al 3+ , 33.0% to 60.0% R 2+ ,and Gd below 1.73% 3+ ; Expressed as cation % in mole %, Nb 5+ 、Ti 4+ , and W 6+ Total content (Nb 5+ +Ti 4+ +W 6+ ) is 0% to 15.0%, Ln 3+ The total content is 9.09% to 40.0%, Contains O 2－ and F － As anionic components, Expressed as anion % in mole %, it contains: 30.0% to 58.21% O 2－ ,and 41.79%~65.0% F － ; Refractive index (n d ) is 1.50~1.67, and the Abbe number (ν d ) is 61.69~65.21, and Anomalous dispersion (Δθg, F) ​​is 0.002 or more, in, Ln 3+ Is to choose Y 3+ 、La 3+ 、Gd 3+ 、Yb 3+ and Lu 3+ At least one of the groups R 2+ Is selected from Mg 2 + , Ca 2+ 、Sr 2+ 、Ba 2+ and Zn 2+ At least one of the groups.

2. The optical glass according to claim 1, wherein Expressed as cation % in mole %, it contains: 0~25.0% Mg 2+ , 0~20.0% Ca 2+ , 10.0% to 55.0% Ba 2+ 0 to less than 20.0% Sr 2+ ,and 0 to 25.0% Zn 2+ .

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

4. A preform for grinding and / or precision press forming made of the optical glass according to claim 1 or 2.

5. An optical element formed by grinding the preform according to claim 4.

6. An optical element formed by precision pressing the preform according to claim 4.

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