JP2013163632A - Optical glass, optical element, and preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide optical glass having higher abnormal dispersibility, so that the optical glass can compensate chromatic aberration of a glass lens with high precision, having a high index of refraction, a low dispersibility (high abbe number), an abrasiveness lower than the glass of the prior art, and thus the optical glass being easy to be ground for processing; an optical element; and a preform.SOLUTION: Optical glass includes P, Al, and Mgas cationic ingredients, and contains Oand Fas anionic ingredients, wherein the ratio ((Mg+Ca)/R) between the sum of the Mgcontent (cation%) and the Cacontent (cation%) and the total content of alkaline earth metals (R: cation%) is 0.25 or more, and the abrasiveness is 440 or less.

Description

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

  A lens system of an optical apparatus is usually designed by combining a plurality of glass lenses having different optical properties. In recent years, characteristics required for lens systems of optical devices have been diversified, and optical glasses having optical characteristics that have not been noticed in the past have been developed in order to further increase the degree of freedom of design. Among them, optical glass characterized by anomalous dispersion (Δθg, F) has been attracting attention as having a remarkable effect on aberration color correction.

For example, in Patent Documents 1 to 4, in addition to the conventionally required properties of high refractive index, low dispersibility, and excellent workability, optical glasses having high anomalous dispersion, for example, P ⁵⁺ , Al ³ as cation components are used. There has been proposed an optical glass containing ⁺ , alkaline earth metal ions and the like, and containing F ⁻ and O ²⁻ as anionic components.

JP 2007-55883 A JP 2008-137877 A International Publication No. 2008/111439 Pamphlet JP 2009-256169 A

  However, the conventional optical glasses as described in Patent Documents 1 to 4 have poor workability. That is, it is desired to develop an optical glass having processability while maintaining high anomalous dispersion.

The present invention aims to solve such problems.
That is, an object of the present invention is to provide an optical glass and an optical element that can correct chromatic aberration of a glass lens with high accuracy due to high anomalous dispersibility, and have a lower degree of wear and are easier to polish than conventional ones. And to provide a preform.

The present inventors have intensively studied to solve the above problems, and have completed the present invention.
The present invention includes the following (1) to (8).
(1) containing P ⁵⁺ , Al ³⁺ and Mg ²⁺ as the cation component, and containing O ²⁻ and F ⁻ as the anion component,
Ratio of total Mg ²⁺ content (cation%) and Ca ²⁺ content (cation%) to total alkaline earth metal content (R ²⁺ : cation%) ((Mg ²⁺ + Ca ²⁺ ) / R ²⁺ ) is 0.25 or more,
An optical glass having an abrasion degree of 440 or less.
(2) The ratio (Mg ²⁺ / R ²⁺ ) of Mg ²⁺ content (cation%) to the total alkaline earth metal content (R ²⁺ : cation%) is 0.30 or more, The optical glass according to (1).
(3) Optical glass as described in said (1) or (2) whose refractive index (nd) is 1.50-1.60 and whose Abbe number ((nu) d) is 60-80.
(4) The optical glass according to any one of (1) to (3), wherein the partial dispersion ratio (θg, F) is 0.530 or more.
(5) In terms of cation% (mol%),
The content of P ⁵⁺ is 20 to 55%,
Al ³⁺ content is 5-20%,
Mg ²⁺ content is 0.1-30%,
Ca ²⁺ content is 0.1-30%,
Sr ²⁺ content is 0-20%,
Ba ²⁺ content is 0.1-25%,
The content of R ²⁺ is 30 to 70%,
Zn ²⁺ content is 0-15%,
Anion% (mol%) display,
The optical glass according to any one of (1) to (4), wherein the content of F ⁻ is 20 to 70%.
(6) An optical element made of the optical glass according to any one of (1) to (5) above.
(7) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (5) above.
(8) An optical element obtained by precision pressing the preform described in (7).

  According to the present invention, the chromatic aberration of the glass lens can be corrected with high accuracy due to the high anomalous dispersion, and furthermore, the optical glass, the optical element, and the plug having a lower degree of wear and easier to polish than the conventional one. Renovation can be provided.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft, and Abbe number ((nu) d) on a horizontal axis.

The present invention will be described.
The present invention contains P ⁵⁺ , Al ³⁺ and Mg ²⁺ as the cation component, O ²⁻ and F ⁻ as the anion component, and the total content of alkaline earth metals (R ²⁺ : The total ratio of Mg ²⁺ content (cation%) and Ca ²⁺ content (cation%) to (cation%) ((Mg ²⁺ + Ca ²⁺ ) / R ²⁺ ) is 0.25 or more, It is an optical glass having an abrasion degree of 440 or less.
Hereinafter, such an optical glass is also referred to as “optical glass of the present invention”.

<Glass component>
Each component which comprises the optical glass of this invention is demonstrated.
In the present specification, unless otherwise specified, the content of each component is expressed in terms of cation% or anion% based on the molar ratio. Here, “cation%” and “anion%” are contained in the glass by separating the glass component of the optical glass of the present invention into a cation component and an anion component, and the total ratio is 100 mol% in each. It is the composition which described each component.
In addition, the ionic value of each component uses the representative value for convenience, and does not distinguish it from other ionic values. The ionic valence of each component present in the optical glass may be other than the representative value. For example, since P is usually present in the glass with an ionic value of 5, it is expressed as “P ⁵⁺ ” in the present specification, but may exist in other ionic values. Strictly speaking, even if it exists in a state of another ionic valence, in this specification, each component is treated as being present in the optical glass with a representative ionic valence.

[Cation component]
<P ⁵⁺ >
The optical glass of the present invention contains P ⁵⁺ . P ⁵⁺ is a glass-forming component and has properties of suppressing devitrification of the glass and increasing the refractive index.
Since such properties are strengthened, the content of P ⁵⁺ is preferably 20.0 to 55.0%. Further, it is more preferably 25.0% or more, and further preferably 30.0% or more. Further, it is more preferably 50.0% or less, more preferably 45.0% or less, more preferably 43.0% or less, and further preferably 41.0% or less.
P ⁵⁺ is contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , Zn (PO ₃ ) ₂ , BPO ₄ , H ₃ PO _4, etc. as raw materials. It can be included.

<Al ³⁺ >
The optical glass of the present invention contains Al ³⁺ . Al ³⁺ has the property of increasing the devitrification resistance of the glass and lowering the degree of wear.
Since such properties are strengthened, the content of Al ³⁺ is preferably 5 to 20.0%. Moreover, it is more preferably 7.0% or more, more preferably 10.0% or more, and further preferably 12.0 or more. Moreover, it is more preferable that it is 18.0% or less, and it is further more preferable that it is 16.0% or less.
Al ³⁺ can be contained in the glass using, for example, Al (PO ₃ ) ₃ , AlF ₃ , Al ₂ O ₃ or the like as a raw material.

<Alkaline earth metal>
In the optical glass of the present invention, the alkaline earth metal means Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ . In addition, at least one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ may be represented as R ²⁺ .
The total content of R ²⁺ means the total content of these four ions (Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ ).
The total content of R ²⁺ is preferably 30.0 to 70.0%. This is because a more stable glass can be obtained when the content is in such a range.
The total content of R ²⁺ is more preferably 35.0% or more, more preferably 40.0% or more, and further preferably 44.0% or more. Further, it is more preferably 65.0% or less, more preferably 60.0% or less, more preferably 55.0% or less, and further preferably 53.0% or less.

<Mg ²⁺ >
The optical glass of the present invention contains Mg ²⁺ . Mg ²⁺ has the property of increasing the devitrification resistance of the glass and lowering the degree of wear.
Since such properties are strengthened, the Mg ²⁺ content is preferably 0.1 to 30.0%. Further, it is more preferably 2.0% or more, more preferably 5.0% or more, and further preferably 10.0% or more. Moreover, it is more preferable that it is 25.0% or less, and it is further more preferable that it is 20.0% or less.
Mg ²⁺ can be contained in the glass using, for example, MgO, MgF ₂ or the like as a raw material.

<Ca ²⁺ >
The optical glass of the present invention preferably contains Ca ²⁺ . Ca ²⁺ has the properties of enhancing devitrification resistance, suppressing a decrease in refractive index, and lowering the degree of wear of glass.
Since such properties increase, the Ca ²⁺ content is more preferably 0.1% to 30.0%. Further, it is more preferably 5.0% or more, more preferably 10.0% or more, more preferably 12.0% or more, and further preferably 13.0% or more. Further, it is more preferably 20.0% or less, and further preferably 16.0% or less.
Ca ²⁺ can be contained in the glass using, for example, Ca (PO ₃ ) ₂ , CaCO ₃ , CaF ₂ or the like as a raw material.

The optical glass of the present invention preferably contains Mg ²⁺ as an essential component and further contains Ca ²⁺ . The coexistence of these two components enhances the devitrification resistance of the glass, suppresses the lowering of the refractive index, and lowers the degree of wear, and in particular enhances the devitrification resistance of the glass. The optical glass of the present invention preferably further contains other alkaline earth metal Sr ²⁺ and / or Ba ²⁺ .

In the optical glass of the present invention, the total ratio of the Mg ²⁺ content (cation%) and the Ca ²⁺ content (cation%) to the total alkaline earth metal content (R ²⁺ : cation%) (( Mg ²⁺ + Ca ²⁺ ) / R ²⁺ ) is 0.25 or more. The lower limit of (Mg ²⁺ + Ca ²⁺ ) / R ²⁺ is preferably 0.28, more preferably 0.31, more preferably 0.34, and 0.36. Is more preferred and 0.38 is even more preferred. The upper limit of (Mg ²⁺ + Ca ²⁺ ) / R ²⁺ is preferably 0.80, more preferably 0.75, more preferably 0.70, and 0.68 More preferably it is.
The present inventor is an optical glass containing P ⁵⁺ , Al ³⁺ , Mg ²⁺ and Ca ²⁺ as a cation component and O ²⁻ and F ⁻ as an anion component, ^{If 2+} + Ca ²⁺ ) / R ²⁺ is 0.25 or more, the chromatic aberration of the glass lens can be corrected with high accuracy due to its high anomalous dispersion, and the degree of wear is higher than that of the conventional one. It has been found that an optical glass that is low and easy to polish can be obtained.

In the optical glass of the present invention, the Mg ²⁺ content (cation%) ratio (Mg ²⁺ / R ²⁺ ) is preferably 0.30 or more. The lower limit of Mg ²⁺ / R ²⁺ is preferably 0.32, more preferably 0.34, even more preferably 0.36, and even more preferably 0.37. The upper limit of Mg ²⁺ / R ²⁺ is preferably 0.75, more preferably 0.70, more preferably 0.65, and further preferably 0.63. .
The inventor of the present invention is an optical glass containing P ⁵⁺ , Al ³⁺ and Mg ²⁺ as cation components and O ²⁻ and F ⁻ as anion components, wherein (Mg ²⁺ + Ca ²⁺ ) / R ²⁺ is 0.25 or more, and further Mg ²⁺ / R ²⁺ is 0.30 or more, the chromatic aberration of the glass lens can be corrected with high accuracy due to higher anomalous dispersion. In addition, it has been found that an optical glass having a lower degree of wear and easier polishing can be obtained than the conventional one.

<Sr ²⁺ >
The optical glass of the present invention may contain Sr ²⁺ as one of R ²⁺ (alkaline earth metal). Sr ²⁺ has the property of increasing the devitrification resistance of the glass and suppressing the decrease in the refractive index.
Since such properties are strengthened, the Sr ²⁺ content is preferably 0% to 20.0%. Further, it is more preferably 1.0% or more, and further preferably 2.0% or more. Moreover, it is more preferable that it is 17.0% or less, and it is further more preferable that it is 14.0% or less.
Sr ²⁺ can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

<Ba ²⁺ >
The optical glass of the present invention may contain Ba ²⁺ as one of R ²⁺ (alkaline earth metal). Ba ²⁺ has a property of increasing the devitrification resistance of the glass when contained in a predetermined amount. Moreover, it has the property of maintaining low dispersibility and increasing the refractive index.
Since such properties are strengthened, the Ba ²⁺ content is preferably 0.1 to 25.0%. Further, it is more preferably 20.0% or less, more preferably 19.0% or less, and further preferably 17.0% or less. Further, it is preferably 1.0% or more, preferably 5.0% or more, more preferably 10.0% or more, and even more preferably 12.0% or more, and 13. It is more preferably 0% or more, and further preferably 14.0% or more.
Ba ²⁺ can be contained in the glass by using, for example, Ba (PO ₃ ) ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like as a raw material.

<Zn ²⁺ >
The optical glass of the present invention may contain Zn ²⁺ as an optional component. Zn ²⁺ has the property of improving the degree of wear and increasing the refractive index.
Since such properties are enhanced, the Zn ²⁺ content is preferably 0% to 15.0%. Further, it is more preferably 1.0% or more, and further preferably 1.5% or more. Moreover, it is more preferable that it is 12.0% or less, it is more preferable that it is 8.0% or less, it is more preferable that it is 4.0% or less, and it is further more preferable that it is 2.0% or less.
Zn ²⁺ can be contained in the glass by using, for example, Zn (PO ₃ ) ₂ , ZnO, ZnF ₂ or the like as a raw material.

<Ln ³⁺ >
In the present invention, Ln ³⁺ means at least one selected from the group consisting of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and Lu ³⁺ . The total content of Ln ³⁺ means the total content of these five ions (Y ³⁺ + La ³⁺ + Gd ³⁺ + Yb ³⁺ + Lu ³⁺ ).
The optical glass of the present invention preferably contains Ln ³⁺ at a total content of 10.0% or less. This is because when the content is in such a range, the refractive index of the glass tends to increase and the dispersion tends to be low. Further, it is preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. Since Ln ³⁺ is an optional component, the optical glass of the present invention may not contain Ln ³⁺ .

<Y ³⁺ >
The optical glass of the present invention may contain Y ³⁺ as one of Ln ³⁺ . Y ³⁺ has the properties of maintaining low dispersibility, increasing the refractive index, and improving devitrification resistance. However, since the stability tends to deteriorate when contained in excess, the content is more preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. . Further, it is possible to obtain a glass of the present invention be free of Y ^3+, from such a point may not include a Y ^3+.
Y ³⁺ can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ or the like as a raw material.

<La ³⁺ >
The optical glass of the present invention may contain La ³⁺ as one of Ln ³⁺ . La ³⁺ has the property of maintaining low dispersibility and increasing the refractive index.
Since such properties are strengthened, the La ³⁺ content is more preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. .
La ³⁺ can be contained in the glass using, for example, La ₂ O ₃ , LaF ₃ or the like as a raw material.

<Gd ³⁺ >
The optical glass of the present invention may contain Gd ³⁺ as one of Ln ³⁺ . Gd ³⁺ has the properties of maintaining low dispersibility, increasing the refractive index, and further improving devitrification resistance.
Since such properties are strengthened, the content of Gd ³⁺ is more preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. .
Gd ³⁺ can be contained in the glass using, for example, Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

<Yb ³⁺ >
The optical glass of the present invention may contain Yb ³⁺ as one of Ln ³⁺ . Yb ³⁺ has the properties of maintaining low dispersibility, increasing the refractive index, and further improving devitrification resistance.
Since such properties are strengthened, the content of Yb ³⁺ is more preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. .
Yb ³⁺ can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

<Lu ³⁺ >
The optical glass of the present invention may contain Lu ³⁺ as one of Ln ³⁺ . Lu ³⁺ has the properties of maintaining low dispersibility, increasing the refractive index, and further improving devitrification resistance.
Since such properties are strengthened, the Lu ³⁺ content is more preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. .
Lu ³⁺ can be contained in the glass using, for example, Lu ₂ O ₃ as a raw material.

<Si ⁴⁺ >
The optical glass of the present invention may contain Si ⁴⁺ as an optional component. Si ⁴⁺ has the property of increasing the devitrification resistance of the glass when it is contained in a predetermined amount and lowering the degree of wear while increasing the refractive index.
Since such properties are strengthened, the Si ⁴⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Si ⁴⁺ can be contained in the glass by using, for example, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like as a raw material.

<B ³⁺ >
The optical glass of the present invention may contain B ³⁺ as an optional component. B ³⁺ has the property of increasing the devitrification resistance of the glass when contained in a predetermined amount, increasing the refractive index, lowering the degree of wear, and further making it difficult to deteriorate the chemical durability.
Since such properties increase, the content of B ³⁺ is preferably 15.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less. More preferably, it is 3.0% or less. Further, it is preferably 0.1% or more, more preferably 0.5% or more, and further preferably 1.0% or more.
B ³⁺ can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , BPO ₄ or the like as a raw material.

<Li ⁺ >
The optical glass of the present invention may contain Li ⁺ as an optional component. Li ⁺ has the property of lowering the glass transition point (Tg) while maintaining devitrification resistance during glass formation.
Since such properties are strengthened, the Li ⁺ content is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 10.0% or less.
Li ⁺ can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

<Na ⁺ >
The optical glass of the present invention may contain Na ⁺ as an optional component. Na ⁺ has the property of lowering the glass transition point (Tg) while maintaining devitrification resistance during glass formation.
Since such properties are strengthened, the Na ⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Na ⁺ can be contained in the glass by using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

<K ⁺ >
The optical glass of the present invention may contain K ⁺ as an optional component. K ⁺ has the property of lowering the glass transition point (Tg) while maintaining devitrification resistance during glass formation.
Since such properties are strengthened, the K ⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
K ⁺ can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

<Rn ⁺ >
In the optical glass of the present invention, the total content of Rn ⁺ (Rn ⁺ is at least one selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ ) is preferably 20.0% or less, It is more preferably 0% or less, and further preferably 10.0% or less.

<Nb ⁵⁺ >
The optical glass of the present invention may contain Nb ⁵⁺ as an optional component. Nb ⁵⁺ has the properties of increasing the refractive index of the glass, increasing the chemical durability, and further suppressing the decrease in the Abbe number.
Since such properties are strengthened, the content of Nb ⁵⁺ is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Nb ⁵⁺ can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

<Ti ⁴⁺ >
The optical glass of the present invention may contain Ti ⁴⁺ as an optional component. Ti ⁴⁺ has the property of increasing the refractive index of glass.
Since such properties are strengthened, the Ti ⁴⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Ti ⁴⁺ can be contained in the glass using, for example, TiO ₂ as a raw material.

<Zr ⁴⁺ >
The optical glass of the present invention may contain Zr ⁴⁺ as an optional component. Zr ⁴⁺ has the property of increasing the refractive index of glass.
Since such properties are strengthened, the Zr ⁴⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Zr ⁴⁺ can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

<Ta ⁵⁺ >
The optical glass of the present invention may contain Ta ⁵⁺ as an optional component. Ta ⁵⁺ has the property of increasing the refractive index of glass.
Since such properties are strengthened, the Ta ⁵⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Ta ⁵⁺ can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

<W ⁶⁺ >
The optical glass of the present invention may contain W ⁶⁺ as an optional component. W ⁶⁺ has the property of increasing the refractive index of the glass and lowering the glass transition point.
Since such properties are strengthened, the W ⁶⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
W ⁶⁺ can be contained in the glass using, for example, WO ₃ as a raw material.

<Ge ⁴⁺ >
The optical glass of the present invention may contain Ge ⁴⁺ as an optional component. Ge ⁴⁺ has the property of increasing the refractive index of glass and increasing the devitrification resistance of glass.
Since such properties become remarkable, the content of Ge ⁴⁺ is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less. preferable.
Ge ⁴⁺ can be contained in the glass using, for example, GeO ₂ as a raw material.

<Bi ³⁺ >
The optical glass of the present invention may contain Bi ³⁺ as an optional component. Bi ³⁺ has the property of increasing the refractive index of the glass and lowering the glass transition point.
Since such properties are strengthened, the Bi ³⁺ content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less.
Bi ³⁺ can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

<Te ⁴⁺ >
The optical glass of the present invention may contain Te ⁴⁺ as an optional component. Te ⁴⁺ has the properties of increasing the refractive index of the glass, lowering the glass transition point, and suppressing coloration.
Since such properties are strengthened, the Te ⁴⁺ content is preferably 15.0% or less, more preferably 10.0% or less, and even more preferably 8.0% or less. More preferably, it is 5.0% or less.
Te ⁴⁺ can be contained in the glass using, for example, TeO ₂ as a raw material.

[About anion components]
<F ^->
The optical glass of the present invention contains F ⁻ . F ⁻ has the properties of increasing the anomalous dispersion and Abbe number of the glass and making the glass difficult to devitrify.
Since such properties are strengthened, the content of F ⁻ is preferably 20.0 to 70.0% in terms of anion% (mol%). Further, it is more preferably 30.0% or more, more preferably 35.0% or more, and further preferably 38.0% or more. Further, it is more preferably 60.0% or less, more preferably 50.0% or less, and further preferably 48.0% or less.
F ⁻ can be contained in the glass by using fluorides of various cationic components such as AlF ₃ , MgF ₂ , and BaF ₂ as a raw material.

< ^O2- >
The optical glass of the present invention contains O ²⁻ . O ²⁻ has a property of suppressing an increase in the wear degree of the glass.
Since such properties are strengthened, it is preferable that the content of O ²⁻ is 30.0 to 80.0% in terms of% anion (mol%). Further, it is more preferably 40.0% or more, more preferably 45.0% or more, and further preferably 50.0% or more. Further, it is more preferably 70.0% or less, more preferably 66.0% or less, and further preferably 62.0% or less.
Further, the total of the content of O ^{2− and} the content of F ⁻ is preferably 98.0% or more in terms of anion%, more preferably 99.0% or more, and 100%. More preferably. This is because stable glass can be obtained.
O ²⁻ is a raw material such as oxides of various cation components such as Al ₂ O ₃ , MgO and BaO, and various cations such as Al (PO ₃ ) ₃ , Mg (PO ₃ ) ₂ and Ba (PO ₃ ) _2. It can be made to contain in the glass using the phosphate of a component.

  If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass of the present invention are not impaired.

[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 not preferably contained will be described.

  Cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, are each singly or in combination. Even if it is contained in a small amount, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. Therefore, it is preferable that the glass is not substantially contained particularly in optical glass using a wavelength in the visible range.

  In addition, cations of Pb, Th, Cd, Tl, Os, Be, and Se have tended to be refrained from being used as harmful chemical substances in recent years. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

  Moreover, although it is useful as a defoaming agent, in recent years, Sb tends to be excluded from the optical glass as a component that adversely affects the environment, and from this point, it is preferable not to contain Sb.

The above is put together and the preferable aspect of the optical glass of this invention is shown.
The optical glass of the present invention is
As a cation component, cation% (mol%) display,
The content of P ⁵⁺ is 20 to 55%,
Al ³⁺ content is 5-20%,
Mg ²⁺ content is 0.1-30%,
Ca ²⁺ content is 0.1-30%,
Sr ²⁺ content is 0-20%,
Ba ²⁺ content is 0.1-25%,
The content of R ²⁺ is 30 to 70%,
Zn ²⁺ content is 0-15%,
Anion% (mol%) display,
The content of F ⁻ is 20 to 70%,
The content of O ²⁻ is 30-80%,
An optical glass having a refractive index (nd) of 1.50 to 1.60, an Abbe number (νd) of 60 to 80, and an abrasion degree of 440 or less is preferable.
Furthermore, an optical glass having a partial dispersion ratio (θg, F) of 0.530 or more is preferable.

[Production method]
The method for producing the optical glass of the present invention is not particularly limited. For example, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is poured into a quartz crucible, an alumina crucible or a platinum crucible, and then roughly melted, and then a platinum crucible, a platinum alloy Stir in a crucible or iridium crucible for 2-10 hours at 900-1200 ° C, stir to homogenize, blow out bubbles, etc., then lower the temperature to 850 ° C or lower, then stir to finish and stir It is possible to manufacture by removing the above, casting into a mold and slow cooling.

[Physical properties]
The optical glass of the present invention is characterized by a partial dispersion ratio (θg, F). Therefore, an optical glass that corrects chromatic aberration with high accuracy can be obtained.
The partial dispersion ratio (θg, F) is preferably 0.530 or more, more preferably 0.534 or more, and further preferably 0.538 or more.
The partial dispersion ratio (θg, F) means a value obtained by measurement based on Japan Optical Glass Industry Association Standard JOGIS01-2003.

The optical glass of the present invention has high anomalous dispersion (Δθg, F). Therefore, it is easy to obtain a lens that can correct chromatic aberration with high accuracy.
The anomalous dispersibility (Δθg, F) is preferably 0.010 or more, more preferably 0.012 or more, more preferably 0.014 or more, and more preferably 0.016 or more. Preferably, it is more preferably 0.018 or more.

Here, the partial dispersion ratio (θg, F) and the anomalous dispersion (Δθg, F) will be described, and then the characteristics of the physical properties 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) indicates the ratio of the difference in refractive index between two wavelength ranges in the wavelength dependence of the refractive index, and is expressed by the following formula (1).
θg, F = ( _ng− n _F ) / (n _F −n _C ) (1)
Here, _ng means the g-line (435.83 nm), n _F means the F-line (486.13 nm), and n _C means the refractive index of the C-line (656.27 nm).
When the relationship between the partial dispersion ratio (θg, F) and the Abbe number (νd) is plotted on an XY graph, in the case of general optical glass, it is plotted on a straight line called a normal line. Become. The normal line is the XY graph (on the Cartesian coordinates) where the partial dispersion ratio (θg, F) is taken on the vertical axis and the Abbe number (νd) is taken on the horizontal axis, and the partial dispersion ratio and Abbe number of NSL7 and PBM2 It means a straight line going up to the right connecting the two plotted points (see FIG. 1). Normal glass, which is the standard for the normal line, differs depending on the optical glass manufacturer, but each company defines it with almost the same inclination and intercept. The number (νd) is 60.5, the partial dispersion ratio (θg, F) is 0.5436, and the Abbe number (νd) of PBM2 is 36.3, and the partial dispersion ratio (θg, F) is 0.5828. ).

  For such a partial dispersion ratio (θg, F), anomalous dispersion (Δθg, F) means that the plot of partial dispersion ratio (θg, F) and Abbe number (νd) is in the vertical axis direction from the normal line. It shows how far away. An optical element made of glass having a large anomalous dispersion (Δθg, F) has a property capable of correcting chromatic aberration caused by other lenses in a wavelength range near blue.

  Further, conventionally, in the medium to low dispersion region (region where the Abbe number is about 55 or more), the anomalous dispersion (Δθg, F) tends to increase as the Abbe number (νd) increases. Furthermore, there is a tendency that it is difficult to maintain the anomalous dispersibility at a high level while setting the wear degree to 440 or less.

The inventor has intensively studied and succeeded in developing an optical glass having a high value of anomalous dispersion (Δθg, F) with respect to the Abbe number (νd) and good workability.
For example, in the case of the optical glass of a preferred embodiment shown as an example later, when the degree of wear is 405 or less and the Abbe number (νd) is about 73 to 77, the partial dispersion ratio (θg, F) is An optical glass having an anomalous dispersibility (Δθg, F) of 0.018 or more can be obtained.

The optical glass of the present invention has a high refractive index (nd) and low dispersibility (high Abbe number).
In the optical glass of the present invention, the refractive index (nd) is preferably 1.50 to 1.60, and more preferably 1.50 to 1.58. The refractive index (nd) is preferably 1.51 or more, and more preferably 1.52 or more. Moreover, it is preferable that it is 1.57 or less, and it is more preferable that it is 1.55 or less.
In the optical glass of the present invention, the Abbe number (νd) is preferably 60 to 80. The Abbe number is preferably 65 or more, more preferably 70 or more, and further preferably 73 or more. Moreover, it is preferable that it is 78 or less, and it is more preferable that it is 77 or less.
The refractive index (nd) and Abbe number (νd) mean values obtained by measurement based on the Japan Optical Glass Industry Association Standard JOGIS01-2003.

The optical glass of the present invention has a particularly low degree of wear and is preferably 440 or less. Therefore, unnecessary wear and scratches of the optical glass are reduced, the optical glass can be easily handled in the polishing process, and the polishing process can be easily performed.
The degree of wear is more preferably 430 or less, more preferably 420 or less, more preferably 410 or less, and even more preferably 405 or less.
On the other hand, if the degree of wear is too low, the polishing process tends to be difficult. Therefore, the degree of wear is preferably 80 or more, more preferably 100 or more, and further preferably 120 or more.
In addition, a wear degree shall mean the value obtained by measuring according to "The measuring method of the wear degree of JOGIS10-1994 optical glass".

Moreover, it is preferable that the optical glass of the present invention can obtain desired optical characteristics such as imaging characteristics in a wider temperature range.
In recent years, optical elements incorporated in optical devices such as projectors, copiers, laser printers, and broadcasting equipment have been increasingly used in more severe temperature environments. For example, in a projector, it is necessary to use a high-intensity light source and a highly precise optical system in order to meet the demand for miniaturization and high resolution. In particular, when a high-luminance light source is used, the temperature at the time of use of the optical element constituting the optical system is likely to fluctuate greatly due to the influence of heat generated by the light source, and the temperature often reaches 100 ° C. or higher. At this time, if a highly precise optical system is used, the influence of the temperature variation on the imaging characteristics of the optical system becomes so large that it cannot be ignored. Is required.
Further, even in an optical system that requires extremely high accuracy in refractive index, such as an optical system of an optical device having high resolution, the influence on the imaging characteristics and the like due to the operating temperature may not be negligible.
The optical glass of the present invention is preferably an optical glass capable of obtaining desired optical characteristics such as imaging characteristics in a wider temperature range.

In the optical glass of the present invention, the temperature coefficient (dn / dT) of the relative refractive index is preferably close to zero. Specifically, the lower limit of the temperature coefficient (20 to 40 ° C.) of the relative refractive index (589.29 nm) is preferably −6.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably −5.5 × 10 ^−6. It is preferable that it is (degreeC- ¹⁾ , More preferably, it is -5.0 * ^10-6 degreeC- ¹ . As a result, even in an environment where the temperature of the optical element fluctuates greatly, the refractive index fluctuation is small, and thus desired optical characteristics can be exhibited with high accuracy in a wider temperature range.
On the other hand, if the temperature coefficient of the relative refractive index is too large in the positive direction, the change in the refractive index due to the temperature change of the optical element is increased. Therefore, the optical glass of the present invention, the upper limit of the temperature coefficient of the relative refractive index, and more preferably 6.0 × 10 ^-6 ℃ ^-1, more preferably 5.5 × 10 ^-6 ℃ ^-1, more preferably It may be 5.0 × 10 ⁻⁶ ° C. ⁻¹ . The temperature coefficient of the relative refractive index of the optical glass of the present invention is more preferably a small absolute value, and most preferably 0.
The temperature coefficient of the relative refractive index is the change in the refractive index per 1 ° C. when the temperature of the optical glass is changed while irradiating light with a wavelength of 589.29 nm in air at the same temperature as the optical glass. It is expressed in quantity (× 10 ⁻⁶ ° C. ⁻¹ ).

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. Among them, a preform is formed from the optical glass of the present invention, and polishing, precision press molding, etc. are performed on the preform. It is preferable to produce an optical element such as a lens, a prism, or a mirror using the means. As a result, when used in an optical device that transmits visible light to an optical element such as a camera or a projector, high-definition and high-precision imaging characteristics can be realized. Here, the method for producing the preform material is not particularly limited. For example, a glass gob forming method described in JP-A-8-319124 and an optical glass manufacturing method and manufacturing apparatus described in JP-A-8-73229 are used. Thus, a method of manufacturing a preform material directly from molten glass can also be used, and a method of manufacturing by performing cold processing such as grinding and polishing on a strip material formed from optical glass can also be used.

  Further, the optical glass of the present invention that can obtain desired optical characteristics such as imaging characteristics in a wider temperature range is preferable because a more preferable preform and optical element using the optical glass can be obtained.

  Composition of glass of Examples 1 to 16 and Comparative Example 1 which are optical glasses of the present invention (indicated by mol% in terms of cation% or anion%), refractive index (nd), Abbe number (νd), partial dispersion ratio Table 1 shows (θg, F), anomalous dispersion (Δθg, F), and the degree of wear (Aa).

  The optical glasses of Examples 1 to 16 and Comparative Example 1 of the present invention are all ordinary fluorophosphate glasses such as oxides, carbonates, nitrates, fluorides, and metaphosphate compounds corresponding to the raw materials of the respective components. Select the high-purity raw material to be used, weigh it so that it has the composition ratio of each example shown in Table 1, and mix it uniformly, then put it in a platinum crucible, depending on the melting difficulty of the glass composition After melting in an electric furnace at a temperature range of 900 to 1200 ° C. for 2 to 10 hours, stirring and homogenizing to remove bubbles, the temperature is lowered to 850 ° C. or lower, cast into a mold, and gradually cooled to glass. Was made.

  Here, the refractive index (nd), Abbe number (νd), and partial dispersion ratio (θg, F) of the optical glasses of Examples 1 to 16 and Comparative Example 1 are based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Measured. The glass used in this measurement was annealed under a slow cooling furnace with a slow cooling rate of −25 ° C./hr. From the difference between the value of the partial dispersion ratio (θg, F) on the normal line in FIG. 1 and the value of the measured partial dispersion ratio (θg, F) in the measured Abbe number (νd), Dispersibility (Δθg, F) was determined.

Further, the degree of abrasion was measured according to “Measurement method of degree of abrasion of JOGIS 10-1994 optical glass”. That is, a sample of a glass square plate having a size of 30 × 30 × 10 mm is placed on a fixed position of 80 mm from the center of a flat plate made of cast iron (250 mmφ) horizontally rotating 60 times per minute, and a load of 9.8 N (1 kgf) is applied. While applying vertically, a polishing solution obtained by adding 10 g of lapping material (alumina A abrasive grains) of # 800 (average particle size 20 μm) to 20 mL of water is uniformly fed for 5 minutes to cause friction, and the sample mass before and after the lapping is measured. Then, the wear mass was obtained. Similarly, the wear mass of the standard sample specified by the Japan Optical Glass Industry Association is obtained,
Abrasion degree = {(wear mass / specific gravity of sample) / (wear mass / specific gravity of standard sample)} × 100
Calculated by

  Further, the temperature coefficient (dn / dT) of the relative refractive index of the optical glass is an interference method among the methods described in Japanese Optical Glass Industry Association Standard JOGIS18-1994 “Method for Measuring the Temperature Coefficient of the Refractive Index of Optical Glass”. Measured with

  As shown in Table 1, all of the optical glasses of Examples 1 to 16 of the present invention have a refractive index (nd) of 1.50 to 1.60 and an Abbe number (νd) of 60 to 80. Met.

  Specifically, in any of the examples, the refractive index (nd) was 1.52 to 1.55, and the Abbe number (νd) was 73 to 77. Also, in all the examples, the degree of wear was 405 or less. The partial dispersion ratio (θg, F) was 0.541 or more, and the anomalous dispersion (Δθg, F) was 0.018 or more.

  On the other hand, the optical glass of Comparative Example 1 outside the scope of the present invention has a high degree of wear.

As shown in Table 1, the optical glasses of Examples 1, 2, ^6, 10, 11, 13, and 16 have a temperature coefficient of relative refractive index (20 to 40 ° C.) of −6.0 × 10 ^−6. ° C. ^-1 or more, which was within the desired range.

  Furthermore, using the optical glass of the example of the present invention, after forming a preform for polishing, grinding and polishing were performed to form lenses and prisms. In addition, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded into a lens and a prism. In either case, it could be processed into various lens and prism shapes.

Claims (8)

Containing P ⁵⁺ , Al ³⁺ and Mg ²⁺ as the cation component, O ²⁻ and F ⁻ as the anion component,
Ratio of total Mg ²⁺ content (cation%) and Ca ²⁺ content (cation%) to total alkaline earth metal content (R ²⁺ : cation%) ((Mg ²⁺ + Ca ²⁺ ) / R ²⁺ ) is 0.25 or more,
An optical glass having an abrasion degree of 440 or less. The ratio (Mg ²⁺ / R ²⁺ ) of the Mg ²⁺ content (cation%) to the total alkaline earth metal content (R ²⁺ : cation%) is 0.30 or more. The optical glass described.   The optical glass according to claim 1 or 2, wherein the refractive index (nd) is 1.50 to 1.60, and the Abbe number (νd) is 60 to 80.   The optical glass according to claim 1, wherein the partial dispersion ratio (θg, F) is 0.530 or more. In cation% (mol%) display,
The content of P ⁵⁺ is 20 to 55%,
Al ³⁺ content is 5-20%,
Mg ²⁺ content is 0.1-30%,
Ca ²⁺ content is 0.1-30%,
Sr ²⁺ content is 0-20%,
Ba ²⁺ content is 0.1-25%,
The content of R ²⁺ is 30 to 70%,
Zn ²⁺ content is 0-15%,
Anion% (mol%) display,
The optical glass according to claim 1, wherein the content of F ⁻ is 20 to 70%.   An optical element made of the optical glass according to claim 1.   A preform for polishing and / or precision press molding comprising the optical glass according to claim 1. An optical element obtained by precision pressing the preform according to claim 7.

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