TWI795567B - Optical glasses, optical elements and preforms - Google Patents

Abstract

The object of the present invention is to obtain an optical glass which can maintain the characteristics of high refractive index and anomalous dispersion (Δθ _g , F), and has high dispersion with Abbe number of 45 to 68, a preform using the optical glass, and Optical element. The optical glass, represented by cationic % (mole %), contains 17.0% to 50.0% of P ^{5 +} , 3.0% to 20.0% of Al ^{3 +} , 33.0% to 60.0% of R ^{2 +} Ear %) means that the total content of Nb ^{5 +} , Ti ^{4 +} and W ^{6 +} (Nb ^{5 +} +Ti ^{4 +} +W ^{6 +} ) is 0% to 15.0%, and the total content of Ln ^{3 +} is 2.0% to 40.0%, containing O ^{2 -} and F ^- as anion components, the refractive index (nd ) is 1.50 to 1.67, the Abbe number (ν _{d )} is 45 to 68, and the anomalous dispersion (Δθ _g , F) is 0.002 or more .

Description

Optical glasses, optical elements and preforms

The invention relates to an optical glass, an optical element and a preform.

The lens system of an optical device is usually designed by combining multiple glass lenses with different optical properties. In recent years, the properties required for lens systems of optical devices have been diversifying, and in order to further increase the degree of freedom in their design, optical glasses with optical properties that have not received much attention until now are being developed. Among them, optical glass characterized by anomalous dispersion (Δθg, F) has attracted attention as a glass having a remarkable effect on color correction of aberration.

For example, in Patent Document 1 to Patent Document 3, in addition to properties such as high refractive index, low dispersion, and excellent processability required in the past, an optical glass with high anomalous dispersion is proposed, which contains, for example, P ^{5 +} , Al ^{3 +} , alkaline earth metal ions, etc. are used as cation components, and F ⁻ and O ^{2 −} are contained as anion components. [Prior Art Document] [Patent Document]

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-55883. Patent Document 2: Japanese Unexamined Patent Publication No. 2011-116649. Patent Document 3: Japanese Patent Laid-Open No. 2011-126782.

[Problems to be Solved by the Invention]

However, the optical glasses disclosed in Patent Document 1 to Patent Document 3 have a low refractive index or a high Abbe number. Therefore, it is desired to develop an optical glass having a refractive index of 1.50 or more and an Abbe number of 45 to 68 in a high-refractive-index low-dispersion region.

The present invention has been made in view of the above-mentioned technical problems, and its object is to provide a fluorophosphoric acid-based optical glass that maintains a high refractive index and anomalous dispersion (Δθg, F) and has an Abbe number of 45 to 68. High dispersion optical glass, optical element and preform using the optical glass. [Means to solve the problem]

The inventors of the present invention have made intensive studies to solve the above-mentioned technical problems, and have completed the present invention. Specifically, the present invention provides the following products.

(1) An optical glass, represented by cation % (mole %), containing: 17.0% to 50.0% of P ^{5 +} ; 3.0% to 20.0% of Al ^{3 +} ; 33.0% to 60.0% of R ^{2 +} ; Cation % (mole %) indicates that the total content of Nb ^{5 +} , Ti ^{4 +} and W ^{6 +} (Nb ^{5 +} +Ti ^{4 +} +W ^{6 +} ) is 0% to 15.0%; the total of Ln ^{3 +} The content is 2.0% to 40.0%; contains O ^{2 -} and F ^- as anion components; the refractive index (n _d ) is 1.50 to 1.67, the Abbe number (ν _d ) is 45 to 68; anomalous dispersion (Δθg,F) 0.002 or more (Ln ^{3 +} is at least one selected from the group consisting of Y ^{3 +} , La ^{3 +} , Gd ^{3 +} , Yb ^{3 +} and Lu ^{3 +} , R ^{2 +} is selected from the group consisting of Mg ^{2 +} , Ca ^{2 +} , Sr ^{2 +} , Ba ^{2 +} and at least one of the group consisting of Zn ^{2 +} ).

(2) The optical glass as described in (1), which is represented by cation % (molar %), and contains: 0% to 25.0% of Mg ^{2 +} ; 0% to 20.0% of Ca ^{2 +} ; 10.0% to 55.0% % Ba ^{2 +} ; 0% to less than 20.0% Sr ^{2 +} ; 0% to 25.0% Zn ^{2 +} .

(3) The optical glass described in (1) or (2), which is represented by anion % (mole %), contains: 30.0% to 75.0% of O ^{2 -} ; 25.0% to 65.0% of F ^- .

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

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

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

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

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 more, an optical element and a preform using the optical glass.

The optical glass of the present invention contains, as essential components, P ^{5 +} , Al ^{3 +} , and R ^{2 +} , which are cationic components, and the total amount of Nb ^{5 +} , Ti ^{4 +} , and W ^{6 +} contents (Nb ^{5 +} +Ti ^{4 ++} +W ^{6 +} ) is 0% to 15.0%, the total content of Ln ^{3 +} is 2.0% to 40.0%, and O ^{2 -} and F ^- are contained as anion components, so that the refractive index (n _d ) can be obtained as 1.50 to 1.67, Abbe number (ν _d ) of 45 to 68, anomalous dispersion (Δθg, F) of 0.002 or more optical glass.

Hereinafter, the optical glass of this invention is demonstrated. The present invention is not limited to the following embodiments, and can be implemented with appropriate changes within the scope of the objective of the present invention. It should be noted that descriptions are sometimes omitted for overlapping parts, which does not limit the gist of the invention.

>Glass components> Each component which comprises the optical glass of this invention is demonstrated. In this specification, unless otherwise specified, the content of each component is represented by cation % or anion % based on molar ratio. Here, "cation %" and "anion %" (hereinafter also referred to as "cation % (mole %)" and "anion % (mole %)") refer to the glass composition of the optical glass of the present invention It is divided into a cationic component and an anionic component, and the total ratio of each component is 100 mol%, and the composition shows the content of each component contained in the glass. It should be noted that the ion valences of the respective components are merely representative values for the sake of convenience, and are not distinguished from other ion valences. The ion valence of each component present in optical glass may be a value other than the representative value. For example, P usually exists in a glass with an ionic valence of 5, so it is represented by "P ^{5 +} " in this specification, but it can also exist in a state of other ionic valences. Thus, strictly speaking, although it can exist in the state of another ion valence, in this specification, each component is considered to exist in glass with the ion valence of a representative value.

[About Cationic Components] P ^{5 +} is a glass-forming component and is an essential component. In particular, the devitrification resistance of the glass can be improved by including 17.0% or more. Therefore, the lower limit of the P ^{5 +} content is preferably at least 17.0%, more preferably at least 20.0%, even more preferably at least 21.0%, particularly preferably at least 22.0%, especially preferably at least 23.0%, and most preferably at least 24.0% %above. On the other hand, when the content of P ^{5 +} is 50.0% or less, the decrease in the refractive index and the Abbe number due to P ^{5 +} can be suppressed, and the decrease in chemical durability can also be suppressed. Therefore, the upper limit of the P ^{5 +} content is preferably less than 50.0%, more preferably less than 45.0%, more preferably less than 43.0%, particularly preferably less than 40.0%, especially preferably less than 38.0%, and even more preferably less than 36.0%. P ^{5 +} can use Al(PO ₃ ) ₃ , Ca(PO ₃ ) ₂ , Ba(PO ₃ ) ₂ , Zn(PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ , etc. as a raw material.

Al ^{3 +} is an essential component, containing 3.0% or more, and can explain the formation of the skeleton of the fine structure of the glass, so that the devitrification resistance can be improved and the degree of abrasion can be reduced. Therefore, the lower limit of the Al ^{3 +} content is preferably at least 3.0%, more preferably at least 4.0%, still more preferably at least 5.0%, and most preferably at least 5.5%. On the other hand, by making the content of Al ^{3 +} 20.0% or less, it is possible to suppress the decrease in the refractive index and Abbe's number due to Al ^{3 +} and suppress the increase in the glass transition point and the yield point. Therefore, the upper limit of the content of Al ^{3 +} is preferably less than 20.0%, more preferably less than 15.0%, more preferably less than 13.0%, particularly preferably less than 12.0%, especially preferably less than 10.0%, and even more preferably less than 9.0%. Al ^{3 +} can use Al(PO ₃ ) ₃ , AlF ₃ , Al ₂ O ₃ or the like as a raw material.

B ^{3 +} is an optional component, and when the content exceeds 0%, the refractive index and devitrification resistance of the glass can be improved. On the other hand, by making the content of B ^{3 +} 10.0% or less, deterioration of chemical durability can be suppressed. Therefore, the content of B ^{3 +} is preferably less than 10.0%, more preferably less than 8.0%, more preferably less than 5.0%, particularly preferably less than 3.0%, especially preferably less than 1.0%, and even more preferably less than 0.5%. . In particular, from the viewpoint of preventing streaks due to volatilization of glass, it is preferable not to contain B ^{3 +} . B ^{3 +} can use H ₃ BO ₃ , Na ₂ B ₄ O ₇ , BPO ₄ or the like as a raw material.

Si ^{4 +} 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 degree of wear. On the other hand, by making the content of Si ^{4 +} 3.0% or less, devitrification due to excessive Si ^{4 +} content can be reduced. Therefore, the content of Si ^{4 +} is preferably at most 3.0%, more preferably at most 2.0%, even more preferably at most 1.0%, and most preferably at most 0.5%. Si ^{4 +} can use SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like as a raw material.

Li ⁺ is an optional component, and when the content exceeds 0%, the devitrification resistance at the time of glass formation can be maintained high, and the glass transition point can be lowered. On the other hand, by making the Li ⁺ content rate 10.0% or less, a stable glass can be obtained and the maximum value of the expansion coefficient can be reduced. In addition, a decrease in the refractive index can be suppressed. Therefore, the Li ⁺ content is preferably at most 10.0%, more preferably at most 5.0%, still more preferably less than 1.0%, and most preferably less than 0.5%. Li ⁺ can use _Li2CO3 , _LiNO3 , LiF etc. as _a raw material.

Na ⁺ is an optional component, and when the content exceeds 0%, the glass transition point can be lowered while maintaining high resistance to devitrification at the time of glass formation. On the other hand, by making the Na ⁺ content rate 10.0% or less, a stable glass can be obtained and the maximum value of the expansion coefficient can be reduced. In addition, a decrease in the refractive index can be suppressed. Therefore, the Na ⁺ content is preferably at most 10.0%, more preferably at most 5.0%, still more preferably less than 1.0%, and most preferably less than 0.5%. Na ⁺ can use _Na2CO3 , _NaNO3 , NaF etc. as a _raw material.

K ⁺ is an optional component, and when the content exceeds 0%, the devitrification resistance at the time of glass formation can be maintained high, and the glass transition point can be lowered. On the other hand, by making the K ⁺ content rate 10.0% or less, a stable glass can be obtained and the maximum value of the expansion coefficient can be reduced. In addition, a decrease in the refractive index can be suppressed. Therefore, the content of K ⁺ is preferably at most 10.0%, more preferably at most 5.0%, still more preferably less than 3.0%, and most preferably less than 1.0%. K ⁺ can use K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

The alkali metal refers to at least one or more selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ . In addition, at least one kind selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ may also be described as Rn ⁺ . In addition, the total content of Rn ⁺ refers to the total content of one or more of these three types of ions (for example, Li ⁺ +Na ⁺ +K ⁺ ).

Mg ^{2 +} is an optional component, and when the content is greater than 0%, it can improve the devitrification resistance of the glass, reduce the degree of abrasion and improve the workability. Therefore, the content of Mg ^{2 +} is preferably greater than 0%, more preferably at least 1.0%, even more preferably at least 2.0%, and most preferably at least 3.0%. On the other hand, by making the content of Mg ^{2 +} 30.0% or less, devitrification of glass and a decrease in refractive index due to excessive content of Mg ^{2 +} can be suppressed. Therefore, the content of Mg ^{2 +} is preferably at most 30.0%, more preferably at most 26.0%, even more preferably at most 24.0%, particularly preferably at most 20.0%, and most preferably at most 16.0%. Mg ^{2 +} can use MgO, MgF ₂ or the like as a raw material.

Ca ^{2 +} is an optional component, and when the content exceeds 0%, the devitrification resistance of the glass can be improved. Therefore, the lower limit of the Ca ^{2 +} content is preferably greater than 0%, more preferably at least 1.0%, even more preferably at least 2.0%, particularly preferably at least 2.5%, and most preferably at least 3.0%. On the other hand, by making the content of Ca ^{2 +} 30.0% or less, devitrification of the glass and a decrease in the refractive index due to excessive inclusion of Ca ^{2 +} can be suppressed. Therefore, the content of Ca ^{2 +} is preferably less than 30.0%, more preferably less than 26.0%, more preferably less than 23.0%, particularly preferably less than 20.0%, especially preferably less than 15.0%, and most preferably less than 14.0%. , and even better is below 12.0%. Ca ^{2 +} can use Ca(PO ₃ ) ₂ , CaCO ₃ , CaF ₂ , etc. as a raw material.

Sr ^{2 +} is an optional component, and when the content is greater than 0%, the devitrification resistance of the glass can be improved and the decrease in the refractive index can be suppressed. Therefore, the content of Sr ^{2 +} is preferably greater than 0%, more preferably at least 1.0%, even more preferably at least 2.0%, and most preferably at least 3.0%. On the other hand, by making the content of Sr ^{2 +} less than 20.0%, devitrification of the glass and a decrease in the refractive index due to excessive inclusion of Sr ^{2 +} can be suppressed. Therefore, the content of Sr ^{2 +} is preferably less than 20.0%, more preferably less than 18.0%, even more preferably less than 15.0%, particularly preferably less than 10.0%, and especially preferably less than 5.0%. Sr ^{2 +} can use Sr(NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

Ba ^{2 +} is an essential component, containing 10.0% or more, can lower the glass transition point and yield point, improve devitrification resistance, increase the Abbe number, and increase the refractive index. Therefore, the content of Ba ^{2 +} is preferably at least 10.0%, more preferably at least 15.0%, even more preferably at least 20.0%, particularly preferably at least 25.0%, and most preferably at least 30.0%. On the other hand, by making content of ^{Ba2 +} 55.0% or less, the fall of the devitrification resistance of glass by containing ^{Ba2 +} excessively can be suppressed. Therefore, the content of Ba ^{2 +} is preferably at most 55.0%, more preferably at most 53.0%, even more preferably at most 50.0%, and most preferably at most 48.0%. Ba ^{2 +} can use Ba(PO ₃ ) ₂ , BaCO ₃ , Ba(NO ₃ ) ₂ , BaF ₂ , etc. as a raw material.

Zn ^{2 +} is an optional component, and when the content exceeds 0%, the devitrification resistance of the glass can be improved. On the other hand, by setting the content of Zn ^{2 +} to 25.0% or less, it is possible to suppress a decrease in the refractive index. Therefore, the content of Zn ^{2 +} is preferably at most 25.0%, more preferably at most 20.0%, even more preferably at most 15.0%, and most preferably at most 13.0%. Zn ^{2 +} can use Zn(PO ₃ ) ₂ , ZnO, ZnF ₂ or the like as a raw material.

The alkaline earth metal refers to one or more kinds selected from the group consisting of Sr ^{2 +} , Ba ^{2 +} , Mg ^{2 +} , Ca ^{2 +} and Zn ^{2 +} . In addition, R ^{2 +} may represent one or more species selected from the group consisting of Sr ^{2 +} , Ba ^{2 +} , Mg ^{2 +} , Ca ^{2 +} and Zn ^{2 +} . In addition, the total content of R ^{2 +} refers to the total content of one or more of these five types of ions (for example, Sr ^{2 +} +Ba ^{2 +} +Mg ^{2 +} +Ca ^{2 +} +Zn ^{2 +} ).

Y ^{3 +} is an optional component, and when the content exceeds 0%, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the content of Y ^{3 +} is preferably greater than 0%, more preferably at least 0.5%, even more preferably at least 1.0%, and most preferably at least 2.0%. On the other hand, by reducing the content of Y ^{3 +} to 25.0% or less, devitrification due to excessive Y ^{3 +} content can be reduced, and the material cost and specific gravity of the glass can be reduced. In addition, thereby, the glass transition point and the rise of the yield point can be suppressed. Therefore, the content of Y ^{3 +} is preferably at most 25.0%, more preferably at most 20.0%, even more preferably at most 15.0%, particularly preferably at most 10.0%, even more preferably at most 8.0%. Y ^{3 +} can use Y ₂ O ₃ , YF ₃ or the like as a raw material.

La ^{3 +} is an optional component, and when the content exceeds 0%, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the content of La ^{3 +} is preferably greater than 0%, more preferably greater than 0.1%, even more preferably greater than 0.3%, and most preferably greater than 0.5%. On the other hand, by setting the content of La ^{3 +} to 15.0% or less, it is possible to reduce devitrification caused by excessive La ^{3 +} content, and to reduce the material cost and specific gravity of the glass. In addition, thereby, the glass transition point and the rise of the yield point can be suppressed. Therefore, the content of La ^{3 +} is preferably at most 15.0%, more preferably at most 10.0%, even more preferably at most 8.0%, particularly preferably at most 6.0%, and even more preferably at most 3.5%. La ^{3 +} can use La ₂ O ₃ , LaF ₃ or the like as a raw material.

Gd ^{3 +} is an optional component, and when the content exceeds 0%, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the content of Gd ^{3 +} is preferably greater than 0%, more preferably at least 0.5%, and more preferably at least 1.0%. On the other hand, by reducing the content of Gd ^{3 +} to 25.0% or less, devitrification caused by excessive Gd ^{3 +} content can be reduced, and the material cost and specific gravity of the glass can be reduced. In addition, thereby, the glass transition point and the rise of the yield point can be suppressed. Therefore, the content of Gd ^{3 +} is preferably at most 25.0%, more preferably at most 20.0%, even more preferably at most 18.0%, particularly preferably at most 15.0%. Gd ^{3 +} can use Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

Yb ^{3 +} is an optional component, and when the content exceeds 0%, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the content of Yb ^{3 +} is preferably greater than 0%, more preferably at least 0.1%, and more preferably at least 0.5%. On the other hand, by reducing the content of Yb ^{3 +} to 10.0% or less, devitrification due to excessive Yb ^{3 +} content can be reduced, and the material cost and specific gravity of the glass can be reduced. In addition, thereby, the glass transition point and the rise of the yield point can be suppressed. Therefore, the content of Yb ^{3 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, particularly preferably at most 2.5%, even more preferably at most 1.0%. Yb ^{3 +} can use Yb ₂ O ₃ , YbF ₃ or the like as a raw material.

Lu ^{3 +} is an optional component, and when the content exceeds 0%, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the content of Lu ^{3 +} is preferably greater than 0%, more preferably at least 0.5%, and more preferably at least 1.0%. On the other hand, by reducing the content of Lu ^{3 +} to 10.0% or less, devitrification due to excessive content of Lu ^{3 +} can be reduced, and the material cost and specific gravity of the glass can be reduced. In addition, thereby, the glass transition point and the rise of the yield point can be suppressed. Therefore, the content of Lu ^{3 +} is preferably at most 10.0%, more preferably at most 8.0%, and still more preferably at most 5.0%. Lu ^{3 +} can use Lu ₂ O ₃ , LuF ₃ or the like as a raw material.

Ln ^{3 +} means at least one kind selected from the group consisting of La ^{3 +} , Gd ^{3 +} , Y ^{3 +} , Yb ^{3 +} and Lu ^{3 +} . In addition, the total content of Ln ^{3 +} may represent the total content of these five kinds of ions (La ^{3 +} +Gd ^{3 +} +Y ^{3 +} +Yb ^{3 +} +Lu ^{3 +} ).

Ti ^{4 +} is an optional component, and when the content exceeds 0%, the refractive index of the glass can be increased, the chemical durability can be improved, and the reduction of the Abbe number can be suppressed, and it has the property of reducing coloring. On the other hand, by making Ti ^{4 +} 8.0% or less, devitrification resistance can be improved. Therefore, the content of Ti ^{4 +} is 8.0% or less, more preferably 7.0% or less, still more preferably 6.0% or less, most preferably 5.0% or less. Ti ^{4 +} can be contained in glass using, for example, TiO ₂ as a raw material.

Nb ^{5 +} is an optional component, and when the content exceeds 0%, the refractive index of the glass can be increased, the chemical durability can be improved, and it has the property of suppressing the decrease of the Abbe number and the increase of the melting temperature. Therefore, the content of Nb ^{5 +} is preferably greater than 0%, more preferably at least 1.0%, and more preferably at least 2.0%. On the other hand, by making Nb ^{5 +} into 8.0% or less, devitrification resistance can be improved. Therefore, the content of Nb ^{5 +} is 8.0% or less, more preferably 6.0% or less, still more preferably 4.0% or less, most preferably 3.0% or less. Nb ^{5 +} can be contained in glass using, for example, Nb ₂ O ₅ as a raw material.

Zr ^{4 +} is an optional component, and when the content is greater than 0%, the refractive index of the glass can be increased. On the other hand, by setting the content of Zr ^{4 +} to 10.0% or less, it is possible to reduce streaks of the glass caused by volatilization of components in the glass. Therefore, the content of Zr ^{4 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, particularly preferably at most 3.0%. Zr ^{4 +} can use ZrO ₂ , ZrF ₄ or the like as a raw material.

W ^{6 +} is an optional component, and when the content exceeds 0%, it can increase the refractive index of the glass, improve the chemical durability, and has the property of suppressing the decrease of Abbe's number and reducing coloration. Therefore, the content of W ^{6 +} is preferably greater than 0%, more preferably at least 0.1%, and more preferably at least 0.5%. On the other hand, when the content of W ^{6 +} is 8.0% or less, the decrease in the refractive index can be suppressed, and the decrease in Abbe's number can also be suppressed. Therefore, the content of W ^{6 +} is preferably at most 8.0%, more preferably at most 6.0%, even more preferably at most 4.0%, and most preferably at most 3.0%. W ^{6 +} can be contained in glass using, for example, WO ₃ or the like as a raw material.

Ge ^{4 +} is an optional component, and when the content exceeds 0%, it can increase the refractive index of the glass and improve the devitrification resistance. On the other hand, by making the content of Ge ^{4 +} 10.0% or less, the content of expensive Ge ^{4 +} can be reduced, so that the material cost of glass can be reduced. Therefore, the content of Ge ^{4 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, and most preferably at most 3.0%. Ge ^{4 +} can use GeO ₂ etc. as a raw material.

Ta ^{5 +} is an optional component, and when the content is greater than 0%, the refractive index of the glass can be increased. On the other hand, the devitrification of glass can be reduced by making content of ^{Ta5 +} into 10.0% or less. Therefore, the content of Ta ^{5 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, and most preferably at most 3.0%. Ta ^{5 +} can use Ta ₂ O ₅ or the like as a raw material.

Bi ^{3 +} is an optional component, and when the content is greater than 0%, it can increase the refractive index of the glass and lower the glass transition point. On the other hand, by making the content of Bi ^{3 +} 10.0% or less, it is possible to suppress a reduction in visible light transmittance due to devitrification and coloring of the glass. Therefore, the content of Bi ^{3 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, and most preferably at most 3.0%. Bi ^{3 +} can use Bi ₂ O ₃ or the like as a raw material.

Te ^{4 +} is an optional component, and if the content is greater than 0%, it can increase the refractive index of the glass and reduce coloring. On the other hand, by making the content of Te ^{4 +} 10.0% or less, it is possible to suppress devitrification of the glass and reduction in visible light transmittance due to coloring. Therefore, the content of Te ^{4 +} is preferably at most 10.0%, more preferably at most 8.0%, even more preferably at most 5.0%, and most preferably at most 3.0%. Te ^{4 +} can use TeO ₂ etc. as a raw material.

The total content of R ^{2 +} is preferably not less than 33.0% and not more than 60.0%. In particular, glass having higher devitrification resistance can be obtained by making the content of R ^{2 +} 33.0% or more. Therefore, the total content of R ^{2 +} is preferably at least 33.0%, more preferably at least 35.0%, even more preferably at least 36.0%, particularly preferably at least 37.0%, and especially preferably at least 38.0%. On the other hand, by making the content of R ^{2 +} 60.0% or less, devitrification due to excessive content of R ^{2 +} can be reduced. Therefore, the total content of R ^{2 +} is preferably at most 60.0%, more preferably at most 55.0%, even more preferably at most 53.0%, particularly preferably at most 50.0%.

When the total content of Rn ⁺ is greater than 0%, it can maintain high resistance to devitrification during glass formation, and at the same time can reduce the glass transition point. Therefore, the total content of Rn ⁺ is preferably greater than 0%, more preferably at least 0.4%, and most preferably at least 0.7%. On the other hand, by setting the upper limit of Rn ⁺ to 5.0% or less, it is possible to suppress a decrease in the refractive index. Therefore, the total content of Rn ⁺ is preferably at most 5.0%, more preferably at most 4.0%, even more preferably at most 3.0%, and most preferably at most 2.0%.

By making the total content of Ln ^{3 +} 2.0% or more, the devitrification resistance can be improved while maintaining a high refractive index and a high Abbe number. Therefore, the total content of Ln ^{3 +} is preferably at least 2.0%, more preferably at least 4.0%, even more preferably at least 6.0%, and most preferably at least 8.0%. On the one hand, by making the total content of Ln ^{3 +} 40.0% or less, devitrification due to excessive content of Ln ^{3 +} can be reduced, and the material cost and specific gravity of glass can be reduced. Therefore, the total content of Ln ^{3 +} is preferably at most 40.0%, more preferably at most 30.0%, even more preferably at most 25.0%, particularly preferably at most 23.0%, and most preferably at most 21.0%.

In the optical glass of the present invention, when the total content of Nb ^{5 +} , Ti ^{4 +} , and W ^{6 +} is greater than 0%, a high refractive index can be realized and chemical durability can be improved. Therefore, the total content of (Nb ^{5 +} +Ti ^{4 +} +W ^{6 +} ) is preferably greater than 0%, more preferably 0.5% or more, and still more preferably 0.9% or more. On the other hand, by setting the upper limit to 15.0%, it is possible to suppress a decrease in Abbe's number. Therefore, the total content of (Nb ^{5 +} +Ti ^{4 +} +W ^{6 +} ) is preferably at most 15.0%, more preferably at most 12.0%, even more preferably at most 10.0%, and most preferably at most 9.0%.

When Al ^{3 +} /P ^{5 +} is contained at 0.05 or more, the uniformity can be improved, and it also contributes to the improvement of chemical durability. Therefore, Al ^{3 +} /P ^{5 +} is preferably at least 0.05, more preferably at least 0.10, and still more preferably at least 0.15. On the other hand, by setting the upper limit of Al ^{3 +} /P ^{5 +} to be 0.35 or less, deterioration of uniformity of molten glass at the time of glass production can be suppressed. Therefore, Al ^{3 +} /P ^{5 +} is preferably at most 0.35, more preferably at most 0.30, and still more preferably at most 0.28.

When Ba ^{2 +} /R ^{2 +} is contained at 0.40 or more, the glass is stable and devitrification can be reduced. The content of Ba ^{2 +} /R ^{2 +} is preferably at least 0.40, more preferably at least 0.43, and still more preferably at least 0.45. On the other hand, by setting the upper limit of Ba ^{2 +} /R ^{2 +} to 1.00 or less, it is possible to suppress a decrease in the refractive index and Abbe's number. Therefore, the content of Ba ^{2 +} /R ^{2 +} is preferably at most 1.00, more preferably at most 0.95, still more preferably at most 0.90.

When Sr ^{2 +} /(Mg ^{2 +} +Ca ^{2 +} +Sr ^{2 +} +Ba ^{2 +} ) is contained in a ratio greater than 0, the glass is stable and devitrification can be reduced. Therefore, the content of Sr ^{2 +} /(Mg ^{2 +} +Ca ^{2 +} +Sr ^{2 +} +Ba ^{2 +} ) is preferably greater than 0, more preferably 0.03 or more, and still more preferably 0.05 or more. On the other hand, by By setting the upper limit of Sr ^{2 +} /(Mg ^{2 +} +Ca ^{2 +} +Sr ^{2 +} +Ba ^{2 +} ) to 0.35 or less, it is possible to suppress a decrease in the refractive index. Therefore, the content of Sr ^{2 +} /(Mg ^{2 +} +Ca ^{2 +} +Sr ^{2 +} +Ba ^{2 +} ) is preferably at most 0.35, more preferably at most 0.30, still more preferably at most 0.20, most preferably at most 0.15 .

When Sr ^{2 +} /(Li ⁺⁺ +Na ⁺ +K ⁺ ) is contained at a ratio greater than 0, high resistance to devitrification at the time of glass formation can be maintained. Therefore, the content of Sr ^{2 +} /(Li ⁺⁺ +Na ⁺ +K ⁺ ) is preferably greater than 0, more preferably at least 2.00, still more preferably at least 3.00, and most preferably at least 4.00. On the other hand, by setting the upper limit of Sr ^{2 +} /(Li ⁺ +Na ⁺ +K ⁺ ) to 15.00 or less, a high refractive index can be obtained, and streaks and the like are hardly generated. Therefore, the content of Sr ^{2 +} /(Li ⁺⁺ +Na ⁺ +K ⁺ ) is preferably at most 15.00, more preferably at most 13.00, still more preferably at most 10.00, most preferably at most 8.00.

When the content of F ⁺ /P ^{5 +} is 0.70 or more, the glass is stable and devitrification can be reduced. Therefore, the content of F ⁺ /P ^{5 +} is preferably at least 0.70, more preferably at least 0.80, still more preferably at least 0.90, and most preferably at least 1.00. On the other hand, when F ⁺ /P ^{5 +} is contained at 2.50 or less, it is possible to have high anomalous dispersion. Therefore, the content of F ⁺ /P ^{5 +} is preferably at most 2.50, more preferably at most 2.30, still more preferably at most 2.00, most preferably at most 1.80.

[Regarding anion components] The optical glass of the present invention contains O ^{2 −} . The content of O ^{2 -} is, for example, preferably 30.0% to 75.0%. In particular, by containing 30.0% or more of O ^{2 −} , devitrification of the glass can be suppressed, and an increase in the degree of abrasion can be suppressed. Therefore, the O ^{2 -} content is preferably at least 30.0%, more preferably at least 40.0%, even more preferably at least 45.0%, and most preferably at least 52.0%. On the other hand, by setting the content of O ^{2 −} to 75.0% or less, the effects of other anion components can be easily obtained. Therefore, the O ^{2 -} content is preferably at most 75.0%, more preferably at most 70.0%, even more preferably at most 66.0%, particularly preferably at most 63.0%, and most preferably at most 61.0%. For O ^{2 -} , oxides of various cationic components such as Al ₂ O ₃ , MgO, and BaO, and phosphates of various cationic components such as Al(PO) ₃ , Mg(PO) ₂ , and Ba(PO) ₂ can be used as raw materials. .

The optical glass of the present invention contains F ⁻ . The content of F ^- is, for example, preferably not less than 25.0% and not more than 65.0%. In particular, by containing 25.0% or more of F ⁻ , the anomalous dispersion and the Abbe number of the glass can be improved, and the devitrification resistance of the glass can be improved. Therefore, the ^F- content is preferably at least 25.0%, more preferably at least 27.0%, even more preferably at least 30.0%, particularly preferably at least 35.0%, and most preferably at least 39.0%. On the other hand, by making content of ^F- into 65.0 % or less, the fall of the abrasion degree of glass can be suppressed. Therefore, the ^F- content is preferably at most 65.0%, more preferably at most 60.0%, even more preferably at most 55.0%, particularly preferably at most 50.0%, and most preferably at most 48.0%. In addition, from the viewpoint of suppressing devitrification of the glass, the upper limit of the total of the O ^{2 -} content and the F ^- content is preferably 98.0% or more, more preferably 99.0% or more, and still more preferably 100%. For F ⁻ , fluorides of various cationic components, such as AlF ₃ , MgF ₂ , and BaF ₂ , can be used as raw materials.

By making F ⁻ /(F ⁻ +O ^{2 −} ) 0.35 or more, the anomalous dispersion and the Abbe number of the glass can be improved, and the devitrification resistance of the glass can be improved. Therefore, F ⁻ /(F ⁻ +O ^{2 −} ) is preferably at least 0.35, more preferably at least 0.36, still more preferably at least 0.37, and most preferably at least 0.38. On the other hand, by setting F ⁻ /(F ⁻ +O ^{2 −} ) to be 0.55 or less, it is possible to reduce streaks of the glass caused by volatilization of components in the glass. Therefore, F ⁻ /(F ⁻ +O ^{2 −} ) is preferably at most 0.55, more preferably at most 0.53, still more preferably at most 0.50, most preferably at most 0.49.

[about other ingredients] In the optical glass of this invention, other components can be added as needed within the range which does not impair the characteristic of the glass of this invention.

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

Other components not mentioned above can be added as needed within the range that does not impair the characteristics of the glass of the present invention. However, various transition metal components such as Ce, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, even if contained alone or in a small amount in combination, will color the glass, and the specific wavelength in the visible region Absorption occurs, thereby reducing the visible light transmittance-enhancing effect of the present invention, and therefore, it is preferable not to substantially contain it, particularly in optical glass that transmits wavelengths in the visible region.

Pb, Th, Cd, Tl, Os, Be, and Se cations tend to be restricted as harmful chemical substances in recent years, not only in the manufacturing steps of glass, but also in the processing steps and post-production processes. Environmental measures are also required. Therefore, when considering environmental influence as important, it is preferable not to contain these substantially except for unavoidable mixing. Thereby, substances polluting the environment are substantially not contained in the optical glass. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

Although the cations of Sb and Ce are useful as defoaming agents, they are environmentally harmful components, and there is a tendency not to contain them in optical glasses in recent years. Therefore, the optical glass of the present invention preferably does not contain Sb or Ce based on this point.

[Manufacturing method] The manufacturing method of the optical glass of this invention is not specifically limited. For example, uniformly mix the above-mentioned raw materials so that each component is within a predetermined content range, put the prepared mixture into a quartz crucible, alumina crucible, or platinum crucible for preliminary melting, and then put it into a platinum crucible or a platinum alloy crucible. Or melt in an iridium crucible at a temperature ranging from 900°C to 1200°C for 2 hours to 10 hours, stir to homogenize and defoam, etc., then perform final stirring at a temperature below 900°C to 750°C to remove streaks, and cast Poured into a mold and slowly cooled, it can thus be manufactured.

[Physical Properties] The optical glass of the present invention has a high refractive index in a high refractive index low dispersion region. In addition, the optical glass of the present invention preferably has high dispersion. The lower limit of the refractive index ( _nd ) of the optical glass of the present invention is preferably at least 1.50, more preferably at least 1.52, still more preferably at least 1.54, particularly preferably at least 1.56. On the other hand, the upper limit of the refractive index is preferably at most 1.67, more preferably at most 1.66, and still more preferably at most 1.65.

In addition, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 45 or more, more preferably 47 or more, and more preferably 50 or more, and the upper limit is preferably 68 or less, more preferably 67 or less, More preferably, it is 65 or less.

Here, the partial dispersion ratio (θg, F) and the anomalous dispersion (Δθg, F) will be described, and then the physical characteristics of the optical glass of the present invention will be described in more detail. First, the partial dispersion ratio (θg, F) will be described. The partial dispersion ratio (θg, F) is represented by the ratio of the difference in the refractive index in two wavelength regions among the wavelength dependence of the refractive index, and is represented by the following formula (1). θg,F=(ng-nF)/(nF-nC)・・・・・・・Formula (1) where ng is the refractive index of the g-line (435.83nm), and nF is the refractive index of the F-line (486.13nm). Refractive index, nC refers to the refractive index of C line (656.27nm). Then, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is plotted on an XY graph. on a straight line. The standard line refers to plotting the partial dispersion ratios of NSL7 and _PBM2 and The point of Abbe's number, and the straight line rising to the right obtained by connecting these two points (see Figure 1). The standard glass used as a reference for the standard line differs depending on each optical glass manufacturer, but each company uses approximately equal slopes and intercepts to define (NSL7 and PBM2 are optical glasses manufactured by Ohara Co., Ltd., NSL7 The Abbe number (ν _d ) of PBM2 is 60.5, the partial dispersion ratio (θg, F) is 0.5436, the Abbe number (ν _d ) of PBM2 is 36.3, and the partial dispersion ratio (θg, F) is 0.5828).

The anomalous dispersion (Δθg, F) shows how much the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) are plotted in the direction of the vertical axis, as opposed to such a partial dispersion ratio (θg, F). away from the standard line. Optical elements made of glass with large anomalous dispersion (Δθg, F) have the property of correcting chromatic aberrations caused by other lenses in the wavelength range near blue.

The inventors of the present invention succeeded in developing an optical glass having a higher value of anomalous dispersion (Δθg,F) corresponding to Abbe's number (ν _d ) than conventional glasses as a result of intensive studies. For example, in the case of the optical glass of the preferred form shown below as an example, when the Abbe number (ν _d ) is about 50 to 68, the partial dispersion ratio (θg, F) is 0.535 or more, which is abnormal. Dispersion (Δθg, F) is also an optical glass of 0.0020 or more. The values of the partial dispersion ratio (θg, F) and the anomalous dispersion (Δθg, F) are remarkably higher than those of conventional glasses having an equivalent Abbe number (ν _d ).

The optical glass of the present invention is characterized by a partial dispersion ratio (θg, F). Therefore, it is easy to obtain optical glass capable of correcting chromatic aberration with high precision. The partial dispersion ratio (θg, F) is at least 0.510, preferably at least 0.520, more preferably at least 0.530, and still more preferably at least 0.535. 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, still more preferably 0.573 or less. In addition, the partial dispersion ratio described in the present invention refers to the partial dispersion ratio in the short wavelength region.

The optical glass of the present invention has high anomalous dispersion (Δθg, F). Therefore, it is easy to obtain a lens capable of correcting chromatic aberration with high precision. The anomalous dispersion (Δθg, F) is preferably at least 0.002, more preferably at least 0.005, even more preferably at least 0.007, particularly preferably at least 0.090, especially preferably at least 0.011, and very preferably at least 0.013. On the other hand, the upper limit of the anomalous dispersion (Δθg, F) of the optical glass of the present invention is preferably not more than 0.030, more preferably not more than 0.028, more preferably not more than 0.026, particularly preferably not more than 0.024, especially preferably not more than 0.022 the following.

[Preforms and Optical Elements] From the produced optical glass, for example, a glass molded body can be produced by using press molding methods such as reheat press molding and precision press molding. That is, a preform for press molding is produced from optical glass, and the preform is press-molded and then ground to produce a glass molded body, or the preform produced by grinding is formed by a known float method, etc. The molded preform can be precisely press-molded to produce a glass molded body. In addition, the method of manufacturing a glass molded object is not limited to the said method.

The formed glass body produced in this way can function in various optical elements and optical designs. In particular, it is preferable to manufacture optical elements such as lenses, prisms, and reflectors using the optical glass of the present invention using methods such as precision press molding. Accordingly, when optical elements such as cameras and projectors are used in optical devices that transmit visible light, high-definition and high-precision imaging characteristics and the like can be realized, and the weight of the optical systems of these optical devices can be reduced. [Example]

Composition (in mole % expressed by cation % or expressed by anion %) and refractive index ( _nd ), Abbe's 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.

The optical glasses of Examples and Comparative Examples, as raw materials for each component, are high-purity raw materials used in common fluorophosphate glasses, such as various corresponding oxides, carbonates, nitrates, fluorides, and metaphosphoric acid compounds. , Weigh to obtain the ratio of the combination shown in the table and mix it uniformly, put it into a platinum crucible, use an electric furnace to melt it in the temperature range of 900°C to 1250°C for 2 hours to 10 hours according to the melting difficulty of the glass composition, and stir After homogenization and defoaming, etc., the temperature is lowered to below 900°C, cast into a mold, and slowly cooled to make glass.

The refractive index (n _d ) and Abbe's number (ν _d ) of the glasses of Examples and Comparative Examples are represented by values measured at the d-line (587.56 nm) of a helium lamp. In addition, Abbe's number (ν _d ) uses the values of the above-mentioned refractive index of the d-line, the refractive index (nF) of the F-line (486.13nm) of the hydrogen lamp, and the refractive index (nC) of the C-line (656.27nm) , calculated by the formula of Abbe's number (ν _d )=[(n _d -1)/(nF-nC)]. In addition, for the partial dispersion ratio, measure 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), by (θg, F) =(ng-nF)/(nF-nC) formula is calculated. Then, from the difference between the value of the partial dispersion ratio (θg, F) on the standard line in Fig. 1 at the measured Abbe number (ν _d ) and the value of the measured partial dispersion ratio (θg, F), obtain Anomalous dispersion (Δθg, F).

【Table 1】

【Table 2】

【table 3】

【Table 4】

【table 5】

【Table 6】

【Table 7】

【Table 8】

【Table 9】

As shown in Table 1 to Table 9, the optical glasses of the Examples all have a refractive index of 1.50 or more, more specifically, 1.52 or more, which is within a desired range. On the other hand, the glass of the comparative example has a refractive index of 1.4982, which is 1.50 or less. Therefore, it turns out that the refractive index of the optical glass of the Example of this invention is higher than the glass of a comparative example. In addition, the optical glass of the embodiment of the present invention has an Abbe number of 45 or more, more specifically, 47 or more, and the Abbe number is 68 or less, more specifically, 67 or less, which is in the desired range. within range. On the other hand, the glass of the comparative example has an Abbe number of 79.1, which is 68 or more. Therefore, it turns out that the Abbe's number of the optical glass of the Example of this invention is lower than the glass of a comparative example.

In addition, in the optical glasses of the examples, all the partial dispersion ratios (θg, F) were 0.510 or more, and the anomalous dispersion properties (Δθg, F) were all 0.002 or more.

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

Above, although the present invention has been described in detail for the purpose of examples, this embodiment is only for the purpose of examples. It should be understood that those skilled in the art of the present invention can make various changes without departing from the idea and scope of the present invention.

none.

FIG. 1 is a diagram showing a standard line (Normal Line) represented by a Cartesian coordinate system in which the vertical axis is the partial dispersion ratio (θg, F) and the horizontal axis is the Abbe number (ν _d ).

Claims (7)

An optical glass, expressed by cation % in mole %, containing: 17.0% to 50.0% of P ⁵⁺ ; 3.0% to 20.0% of Al ³⁺ ; 33.0% to 60.0% of R ²⁺ ; The cation % in ear% means that the total content of Nb ⁵⁺ , Ti ⁴⁺ , and W ⁶⁺ (Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ ) is 0% to 15.0%; the total content of Ln ³⁺ Content is 2.0% to 40.0%; contains O ^2- and F ^- as anion components; expressed as anion % in mole %, contains: O ^2- below 63.0%; F ^- above 35.0%; refractive index ( n _d ) is 1.50 to 1.67, the Abbe number (ν _d ) is 45 to 65; the anomalous dispersion (△θg, F) is more than 0.002; wherein, Ln ³⁺ is selected from Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and at least one of the group consisting of Lu ³⁺ , R ²⁺ is at least one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ . The optical glass as described in claim 1, wherein it is expressed by cation % in mole %, contains: 0% to 25.0% of Mg ²⁺ ; 0% to 20.0% of Ca ²⁺ ; 10.0% to 55.0% of Ba ²⁺ ; 0% to less than 20.0% Sr ²⁺ ; 0% to 25.0% Zn ²⁺ . The optical glass as described in claim 1 or 2, wherein expressed by anion % in mole %, contains: 30.0% or more of O ^2- ; 65.0% or less of F ^- . An optical element is made of the optical glass as described in claim 1 or 2. A preform, for grinding and/or precision press molding, is made of the optical glass as described in claim 1 or 2. An optical element is formed by grinding the preform as described in Claim 5. An optical element is formed by precision pressing the preform as described in Claim 5.

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