TWI546270B - Optical glass, optical elements and preforms - Google Patents

Description

Optical glass, optical components and preforms

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

Lens systems for optical machines are typically designed by combining a plurality of glass lenses having different optical properties. In recent years, the characteristics required for the lens system of an optical device have been diversified, and in order to further expand the degree of freedom in design, optical glass having optical characteristics not previously focused on has been developed. Among them, the optical glass which is characterized by abnormal dispersibility (Δθg, F) has been attracting attention as a significant effect on color correction of aberrations.

For example, in Patent Literatures 1 to 3, an optical glass having a high degree of dispersibility and high workability, which is considered to have high refractive index and low dispersibility and high workability, is proposed to contain, for example, P ⁵⁺ and Al ^{3 . +} , an alkaline earth metal ion or the like as a cationic component, and an optical glass containing F ^- and O ^{2 -} as an anion component.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-55883

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-137877

[Patent Document 3] International Publication No. 2008/111439

However, the prior optical glass described in Patent Documents 1 to 3 has poor workability. That is, it is desirable to develop a kind in addition to maintaining a high degree of abnormal dispersion, It also has processable optical glass.

The object of the present invention is to solve the above problems.

In other words, it is an object of the present invention to provide an optical glass which is capable of correcting chromatic aberration of a glass lens with high precision by which the abnormal dispersibility is high, and which is easier to perform polishing than the former. And preforms.

The present inventors have made intensive studies to solve the above problems, and have completed the present invention.

The present invention is the following (1) to (8).

(1) An optical glass containing at least one of P, Al, and Zn and further containing an alkaline earth metal as a cationic component, and containing O and F as an anion component, and having an abrasion degree of 440 or less.

(2) The optical glass according to (1) above, wherein the refractive index (nd) is 1.40 to 1.60, and the Abbe number (vd) is 70 to 90.

(3) The optical glass according to (1) or (2) above, wherein the content of P ⁵⁺ is 20 to 50%, and the content of Al ³⁺ is 8 to 30%, expressed as % of cation (% by mole). The content of Mg ²⁺ is 2 to 25%, the content of Ca ²⁺ is 5 to 30%, the content of Sr ²⁺ is 5 to 30%, and the content of Ba ²⁺ is 0 to 20%. The content of ²⁺ is 0.5 to 15%.

(4) The optical glass according to any one of (1) to (3) above, wherein the content of F ^- is represented by an anion % (% by mole) of 41 to 80%.

(5) An optical element comprising the optical glass according to any one of (1) to (4) above.

(6) A preform comprising the optical glass for polishing processing and/or precision press molding according to any one of the above (1) to (4).

(7) An optical element obtained by grinding a preform of the above (6).

(8) An optical element obtained by precisely pressing a preform as in the above (6).

According to the present invention, it is possible to provide an optical glass, an optical element, and an optical glass which can be corrected by a high precision by which the chromatic aberration of the glass lens can be corrected with high accuracy, and the abrasion degree is lower than that of the former. Shaped body.

Hereinafter, the present invention will be described.

The present invention relates to an optical glass containing at least one of P, Al, and Zn and further containing an alkaline earth metal as a cationic component, and containing O and F as an anion component, and having an abrasion degree of 440 or less.

Hereinafter, such an optical glass is also referred to as "the optical glass of the present invention".

<Glass composition>

The components constituting the optical glass of the present invention will be described.

In the present specification, the content ratio of each component is expressed by the percentage of the cation or the percentage of the anion based on the molar ratio, unless otherwise specified. Here, the "cation %" and the "anion %" mean that the glass constituent component of the optical glass of the present invention is separated into a cationic component and an anionic component, and the total ratio thereof is set to 100 mol%, which means that the glass is contained in the glass. The composition of each component.

Further, for the sake of convenience, the ion valence of each component is a representative value, and is not distinguished from other ion valences. The ion valence of each component present in the optical glass may be a value other than the representative value. For example, P is usually present in the glass in a state where the ion valence is 5, and therefore, it is expressed as "P ⁵⁺ " in the present specification, but it may exist in the state of other ion valence. Even if it is strictly in the state of other ion valence, in the present specification, each component is treated as an ion value of the representative value in the optical glass.

[About cationic ingredients] <P ⁵⁺ >

The optical glass of the present invention contains P ⁵⁺ . P ⁵⁺ is a glass forming component and has a property of suppressing devitrification of glass and increasing refractive index.

In order to enhance this property, the content of P ⁵⁺ is preferably 20.0 to 50.0%. Further, it is more preferably 24.0% or more, further preferably 26.0% or more. Further, it is more preferably 40.0% or less, more preferably 35.0% or less, still more preferably 32.0% or less, still more preferably 30.0% or less.

The P ⁵⁺ system may be 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 or the like as a raw material. .

<Al ³⁺ >

The optical glass of the present invention contains Al ³⁺ . Al ³⁺ has the property of improving the resistance to devitrification of the glass and reducing the abrasion.

In order to enhance this property, the content of Al ³⁺ is preferably 8.0 to 30.0%. Further, it is more preferably 15.0% or more, still more preferably 18.0% or more. Further, it is more preferably 25.0% or less, further preferably 22.0% or less.

The Al ³⁺ system 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>

The optical glass of the present invention contains at least one of alkaline earth metals. That is, in the present invention, the alkaline earth metal refers to Mg ²⁺ , Ca ²⁺ , Sr ^{2+ ,} and Ba ²⁺ , and thus the optical glass of the present invention contains one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ^{2+ ,} and Ba ^{2 . +} At least one of the groups consisting of ⁺ . Further, Mg ²⁺ , Ca ²⁺ , Sr ^{2+ ,} and Ba ^{2+ may be} represented as R ²⁺ . In addition, the total content ratio of R ²⁺ refers to the total content ratio of these four kinds of ions (Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ ).

The total content of R ²⁺ is preferably from 30.0 to 70.0%. If the content ratio is such a range, a more stable glass solid can be obtained.

The total content of R ²⁺ is more preferably 35.0% or more, still more preferably 40.0% or more. Further, it is more preferably 65.0% or less, still more preferably 60.0% or less, still more preferably 55.0% or less.

<Mg ²⁺ >

The optical glass of the present invention sometimes contains Mg ²⁺ as one of R ²⁺ (alkaline earth metal). Mg ²⁺ has the property of improving the resistance to devitrification of glass and reducing the degree of wear.

In order to enhance this property, the content of Mg ²⁺ is preferably 2.0 to 25.0%. Further, it is more preferably 3.0% or more, further preferably 5.0% or more. Further, it is more preferably 20.0% or less, further preferably 15.0% or less.

The Mg ²⁺ system 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 may contain Ca ²⁺ as one of R ²⁺ (alkaline earth metal). Ca ²⁺ has the property of improving resistance to devitrification, suppressing a decrease in refractive index, and reducing the abrasion of glass.

In order to enhance this property, the content of Ca ²⁺ is preferably from 5.0% to 30.0%. Further, it is more preferably 10.0% or more, further preferably 15.0% or more. Further, it is more preferably 25.0% or less, further preferably 20.0% or less.

Further, if Ca ²⁺ is present in the glass along with other alkaline earth metals, that is, at least one selected from the group consisting of Mg ²⁺ , Sr ^{2+ ,} and Ba ²⁺ , the devitrification resistance and suppression of the glass are improved. The property of reducing the refractive index and reducing the degree of wear, in particular, enhancing the resistance of the glass to devitrification. Thus, the optical glass of the present invention is preferably selected from the group comprising Ca ²⁺ and Mg ^2+, the group consisting of Sr ²⁺ and Ba ²⁺ is at least one kind.

The Ca ²⁺ system can be contained in the glass using, for example, Ca(PO ₃ ) ₂ , CaCO ₃ , CaF ₂ or the like as a raw material.

Further, in order to particularly improve the resistance to devitrification of the optical glass of the present invention, the molar ratio of the content of Ca ²⁺ (% by mole) to the total amount of total alkaline earth metals (total content (% by mole)) The lower limit of Ca ²⁺ /R ²⁺ ) is preferably 0.001, more preferably 0.005, most preferably 0.01. Further, the upper limit thereof is preferably 0.90, more preferably 0.70, most preferably 0.50.

<Sr ²⁺ >

The optical glass of the present invention sometimes contains Sr ²⁺ as one of R ²⁺ (alkaline earth metal). Sr ²⁺ has the property of improving the resistance to devitrification of the glass and suppressing the decrease in the refractive index.

In order to enhance this property, the content of Sr ²⁺ is preferably from 5.0% to 30.0%. Further, it is more preferably 10.0% or more, and still more preferably 12.0% or more. Further, it is more preferably 25.0% or less, further preferably 20.0% or less.

The Sr ²⁺ system 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 sometimes contains Ba ^{2+ which} is one of R ²⁺ (alkaline earth metal). Ba ²⁺ has the property of increasing the resistance to devitrification of the glass when it contains a specific amount. Further, it has a property of maintaining low dispersibility and increasing the refractive index.

In order to enhance this property, the content of Ba ²⁺ is preferably 0 to 20.0%. Further, it is more preferably 15.0% or less, still more preferably 10.0% or less, still more preferably 7.0% or less. Further, it is preferably 0.05% or more, preferably 0.1% or more, more preferably 0.5% or more, still more preferably 1.0% or more, still more preferably 1.5% or more, still more preferably 2.0% or more, and still more preferably 2.5%. the above.

The Ba ²⁺ system can be contained in the glass 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 contains Zn ²⁺ . Zn ²⁺ has the property of improving the degree of wear and increasing the refractive index.

In order to enhance this property, the content of Zn ²⁺ is preferably from 0.5% to 15.0%. Further, it is more preferably 1.0% or more, further preferably 2.0% or more. Further, it is more preferably 12.0% or less, further preferably 10.0% or less.

The Zn ²⁺ system can be contained in glass, for example, using 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⁺ . In addition, the total content ratio of Ln ³⁺ is a total content ratio of these five kinds of 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. The reason for this is that if the content ratio is 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, still more preferably 7.0% or less. Further, 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 can also contain, as one kind of the ^{3 +} Ln Y ^3+. Y ³⁺ has the property of maintaining low dispersibility, increasing refractive index, and improving resistance to devitrification. However, if the content is excessive, the stability is likely to be deteriorated, so that it is more preferably 9.0% or less, more preferably 8.0% or less, still more preferably 7.0% or less. Further, the glass of the present invention can be obtained even if Y ^{3+ is} not contained, and therefore Y ³⁺ may not be contained in this respect.

The Y ³⁺ system can be contained in the glass using, for example, Y ₂ O ₃ or YF ₃ as a raw material.

<La ³⁺ >

The optical glass of the present invention can also contain, as one kind of the ^{3 +} Ln La ^3+. La ³⁺ has the property of maintaining low dispersibility and increasing refractive index.

In order to enhance such a property, the content of La ³⁺ is more preferably 9.0% or less, still more preferably 8.0% or less, still more preferably 7.0% or less.

The La ³⁺ system 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 can also contain, as one kind of the ^{3 +} Ln Gd ^3+. Gd ³⁺ has the property of maintaining low dispersibility, increasing the refractive index, and further improving the resistance to devitrification.

In order to enhance such a property, the content of Gd ³⁺ is more preferably 9.0% or less, more preferably 8.0% or less, still more preferably 7.0% or less.

The Gd ³⁺ system 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 can also contain, as one kind of the ^{3 +} Ln Yb ^3+. Yb ³⁺ has the property of maintaining low dispersibility, increasing the refractive index, and further improving the resistance to devitrification.

In order to enhance such a property, the content of Yb ³⁺ is more preferably 9.0% or less, more preferably 8.0% or less, still more preferably 7.0% or less.

The Yb ³⁺ system can be contained in the glass using, for example, Yb ₂ O ₃ or the like as a raw material.

<Lu ³⁺ >

The optical glass of the present invention can also contain, as one kind of the ^{3 +} Ln Lu ^3+. Lu ³⁺ has the property of maintaining low dispersibility, increasing the refractive index, and further improving the resistance to devitrification.

In order to enhance such a property, the content of Lu ³⁺ is more preferably 9.0% or less, more preferably 8.0% or less, still more preferably 7.0% or less.

The Lu ³⁺ system can be contained in the glass using, for example, Lu ₂ O ₃ or the like as a raw material.

<Si ⁴⁺ >

The optical glass of the present invention may also contain Si ⁴⁺ as an optional component. Si ⁴⁺ has a property of improving the devitrification resistance of the glass and increasing the refractive index while reducing the degree of wear while containing a specific amount.

In order to enhance such a property, the content of Si ⁴⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Si ⁴⁺ system can be contained in the glass 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 also contain B ³⁺ as an optional component. B ³⁺ has a property of improving the devitrification resistance of the glass and increasing the refractive index when the content is contained, and the degree of wear is lowered, and the chemical durability is hard to be deteriorated.

In order to enhance such a property, the content of B ³⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The B ³⁺ system 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 reducing the glass transition point (Tg) while maintaining the resistance to devitrification when the glass is formed.

In order to enhance such a property, the content of Li ⁺ is preferably 20.0% or less, more preferably 15.0% or less, still more preferably 10.0% or less.

The Li ⁺ system 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 also contain Na ⁺ as an optional component. Na ⁺ has a property of reducing the glass transition point (Tg) while maintaining the resistance to devitrification when the glass is formed.

In order to enhance such a property, the content of Na ⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Na ⁺ system can be contained in the glass 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 also contain K ⁺ as an optional component. K ⁺ has the property of reducing the glass transition point (Tg) while maintaining the resistance to devitrification when the glass is formed.

In order to enhance such a property, the content of K ⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The K ⁺ system 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, more preferably 15.0%. Hereinafter, it is more preferably 10.0% or less.

<Nb ⁵⁺ >

The optical glass of the present invention may also contain Nb ⁵⁺ as an optional component. Nb ⁵⁺ has the property of increasing the refractive index of the glass, improving the chemical durability, and further suppressing the decrease in the Abbe number.

In order to enhance such a property, the content of Nb ⁵⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Nb ⁵⁺ system can be contained in the glass using, for example, Nb ₂ O ₅ or the like as a raw material.

<Ti ⁴⁺ >

The optical glass of the present invention may also contain Ti ⁴⁺ as an optional component. Ti ⁴⁺ has the property of increasing the refractive index of the glass.

In order to enhance such a property, the content of Ti ⁴⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Ti ⁴⁺ system can be contained in the glass using, for example, TiO ₂ or the like as a raw material.

<Zr ⁴⁺ >

The optical glass of the present invention may also contain Zr ⁴⁺ as an optional component. Zr ⁴⁺ has the property of increasing the refractive index of the glass.

In order to enhance such a property, the content of Zr ⁴⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Zr ⁴⁺ system 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 also contain Ta ⁵⁺ as an optional component. Ta ⁵⁺ has the property of increasing the refractive index of the glass.

In order to enhance such a property, the content of Ta ⁵⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Ta ⁵⁺ system can be contained in the glass using, for example, Ta ₂ O ₅ or the like as a raw material.

<W ⁶⁺ >

The optical glass of the present invention may also contain W ⁶⁺ as an optional component. W ⁶⁺ has the property of increasing the refractive index of the glass and lowering the transfer point of the glass.

In order to enhance such a property, the content of W ⁶⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The W ⁶⁺ system can be contained in the glass using, for example, WO ₃ or the like as a raw material.

<Ge ⁴⁺ >

The optical glass of the present invention may also contain Ge ⁴⁺ as an optional component. Ge ⁴⁺ has the property of increasing the refractive index of glass and improving the resistance to devitrification of glass.

In order to make such a property remarkable, the content of Ge ⁴⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Ge ⁴⁺ system can be contained in the glass using, for example, GeO ₂ or the like 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 transfer point of the glass.

In order to enhance such a property, the content of Bi ³⁺ is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less.

The Bi ³⁺ system can be contained in the glass using, for example, Bi ₂ O ₃ or the like as a raw material.

<Te ⁴⁺ >

The optical glass of the present invention may also contain Te ⁴⁺ as an optional component. Te ⁴⁺ has the property of increasing the refractive index of the glass, lowering the glass transition point, and suppressing coloration.

In order to enhance such a property, the content of Te ⁴⁺ is preferably 15.0% or less, more preferably 10.0% or less, still more preferably 8.0% or less, still more preferably 5.0% or less.

Te ⁴⁺ can be contained in the glass using, for example, TeO ₂ or the like as a raw material.

[About anionic ingredients] <F ^- >

The optical glass of the present invention contains F ^- . F ^- has the property of improving the abnormal dispersibility of the glass and the Abbe number, and further making the glass difficult to devitrify.

In order to enhance such a property, the content of F ^- is preferably 41.0 to 80.0% in terms of anion % (% by mole). Further, it is more preferably 45.0% or more, further preferably 50.0% or more. Further, it is more preferably 75.0% or less, further preferably 70.0% or less.

The F ^- series can be contained in the glass using, for example, a fluoride of various cationic components such as AlF ₃ , MgF ₂ or BaF ₂ as a raw material.

<O ^2- >

The optical glass of the present invention contains O ^2- . O ^2- has a property of suppressing an increase in the abrasion of the glass.

In order to enhance such a property, the content of O ^2- is preferably from 20.0 to 60.0% in terms of anion % (% by mole). Further, it is more preferably 25.0% or more, and still more preferably 30.0% or more. Further, it is more preferably 55.0% or less, further preferably 50.0% or less.

Further, the total content of O ^{2- and} the content ratio of F ^- is preferably 98.0% or more, more preferably 99.0% or more, and still more preferably 100%, in terms of anion %. The reason for this is that a stable glass can be obtained.

As the O ² -series, an oxide of various cationic components such as Al ₂ O ₃ , MgO or BaO, or a phosphoric acid of various cationic components such as Al(PO ₃ ) ₃ , Mg(PO ₃ ) ₂ or Ba(PO ₃ ) ₂ can be used. Salt or the like is contained in the glass as a raw material.

In the optical glass of the present invention, other components may be added as needed within a range not impairing the characteristics of the glass of the invention of the present application.

[About ingredients that should not be included]

Next, the components which should not be contained in the optical glass of the present invention and the components which are not preferable in the case of description will be described.

The cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo other than Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu have a small amount even if they are alone or in combination. In the case of the case, the glass is also colored, and the specific wavelength of the visible light region is absorbed. Therefore, in particular, in the optical glass using the wavelength of the visible light region, it is preferable that the optical glass is substantially not contained.

Further, cations of Pb, Th, Cd, Tl, Os, Be, and Se tend to be restricted as harmful chemical substances in recent years, and are not only used in the manufacturing steps of glass, but also in processing steps and post-product processing. All measures must be taken in the context of environmental measures. Therefore, when it is important to pay attention to the influence of the environment, it is preferable that it does not substantially contain the in addition to the inevitable mixing. Thereby, the optical glass does not substantially contain a substance that pollutes the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special measures for environmental measures.

Further, although Sb is used as an antifoaming agent, in recent years, it tends to be contained in an optical glass as a component which adversely affects the environment. In this respect, Sb is preferably not contained.

The above shows a preferred aspect of the optical glass of the present invention.

The optical glass of the present invention preferably has a cationic component (% by mole) as a cationic component, a P ⁵⁺ content of 20 to 50%, and an Al ³⁺ content of 8 to 30%, Mg. The content of ²⁺ is 2 to 25%, the content of Ca ²⁺ is 5 to 30%, the content of Sr ²⁺ is 5 to 30%, and the content of Ba ²⁺ is 0 to 20%. Zn ²⁺ The content is 0.5 to 15%, and the anion component is represented by an anion % (% by mole), the content of F ^- is 41 to 80%, and the refractive index (nd) is 1.40 to 1.60, and the Abbe number (vd) ) is 70 to 90, and the wear rate is 440 or less.

[Production method]

The method for producing the optical glass of the present invention is not particularly limited. For example, it can be produced by uniformly mixing the raw materials in such a manner that the respective components are within a specific content ratio, and after the prepared mixture is introduced into quartz crucible or alumina crucible or platinum crucible for coarse melting, It is placed in a platinum crucible, a platinum alloy crucible or a crucible and melted in a temperature range of 900 to 1200 ° C for 2 to 10 hours, stirred and homogenized, defoamed, etc., and then lowered to a temperature of 850 ° C or less, and then completed. The veins are removed by agitation, cast into a mold and slowly cooled.

[physical property]

The optical glass of the present invention is characterized by a partial dispersion ratio (θg, F). Therefore, an optical glass in which chromatic aberration is corrected with high precision can be obtained.

The partial dispersion ratio (θg, F) is preferably 0.493 or more, more preferably 0.494 or more, still more preferably 0.595 or more, still more preferably 0.596 or more.

In addition, the partial dispersion ratio (θg, F) is a value obtained by measurement based on the Japan Optical Glass Industry Association specification JOGIS01-2003.

The optical glass of the present invention has a high degree of dispersibility (Δθg, F). Therefore, it is easier to obtain a lens that can correct chromatic aberration with high precision.

The abnormal dispersibility (Δθg, F) is preferably 0.005 or more, more preferably 0.006 or more, still more preferably 0.007 or more, still more preferably 0.008 or more.

Here, the partial dispersion ratio (θg, F) and the abnormal dispersibility (Δθg, F) will be described, and then 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) is a ratio of the refractive index difference of a certain two wavelength regions in the wavelength dependence of the refractive index, and is expressed by the following formula (1).

Θg, F=(n _g -n _F )/(n _F -n _C )...(1)

Here, n _g represents the refractive index of the g-ray (435.83 nm), n _F represents the refractive index of the F-ray (486.13 nm), and n _C represents the refractive index of the C-ray (656.27 nm).

Further, when the relationship between the partial dispersion ratio (θg, F) and the Abbe number (vd) is plotted on the XY chart, in the case of a general optical glass, it is roughly drawn on a straight line called a regular line. The so-called regular line The dispersion ratio (θg, F) is the vertical axis and the Abbe number (vd) is the horizontal axis on the XY graph (on the orthogonal coordinates), and the connection is made by dividing the partial dispersion ratio of NSL7 and PBM2 and the Abbe number. The rising line (see Figure 1). The standard glass that becomes the basis for the regular line varies according to the optical glass manufacturer, but each company is defined by roughly the same inclination and intercept (NSL7 and PBM2 are optical glass manufactured by OHARA Co., Ltd., NSL7). The number of shells (vd) was 60.5, the partial dispersion ratio (θg, F) was 0.5436, the Abbe number (vd) of PBM2 was 36.3, and the partial dispersion ratio (θg, F) was 0.5828).

With respect to the partial dispersion ratio (θg, F), the abnormal dispersibility (Δθg, F) is a graph showing the partial dispersion ratio (θg, F) and the Abbe number (vd) plotted from the regular line to the vertical. How far the axis direction deviates. An optical element comprising a glass having a large anomalous dispersion (Δθg, F) has a property of correcting chromatic aberration generated by other lenses in a wavelength range near blue.

Further, in the middle-low dispersion region (the region having an Abbe number of 55 or more), the higher the Abbe number (vd), the larger the abnormal dispersibility (Δθg, F). Further, it is difficult to maintain the abnormal dispersibility at a high level while the abrasion degree is 440 or less.

The inventors of the present invention have intensively studied to develop an optical glass having an abnormal dispersibility (Δθg, F) with a high value of Abbe number (vd) and good workability.

For example, in the case of the optical glass which is a preferred embodiment shown in the following examples, a partial dispersion ratio (θg) can be obtained when the abrasion degree is 400 or less and the Abbe number (vd) is about 78 to 81. F) is an optical glass having a degree of dispersibility of 0.530 or more and an abnormal dispersibility (Δθg, F) of 0.008 or more.

The optical glass of the invention has a higher refractive index (nd) and has a higher Low dispersion (higher Abbe number).

In the optical glass of the present invention, the refractive index (nd) is preferably from 1.40 to 1.60. The refractive index (nd) is preferably 1.45 or more, more preferably 1.48 or more. Further, it is preferably 1.55 or less, more preferably 1.52 or less.

In the optical glass of the present invention, the Abbe number (vd) is preferably from 70 to 90. The Abbe number is preferably 75 or more, more preferably 77 or more, and still more preferably 78 or more. Further, it is preferably 85 or less, more preferably 82 or less.

In addition, the refractive index (nd) and the Abbe number (vd) are values obtained by measurement based on the Japanese Optical Glass Industrial Standards JOGIS01-2003.

The optical glass of the present invention preferably has a particularly low abrasion rate of 440 or less. Therefore, it is possible to reduce the abrasion or damage necessary for the optical glass, and it is easy to handle the polishing process of the optical glass, thereby facilitating the polishing process.

The abrasion degree is more preferably 430 or less, more preferably 420 or less, still more preferably 410 or less, and still more preferably 400 or less.

On the other hand, if the abrasion degree is too low, it tends to be difficult to perform the polishing process. Therefore, the degree of abrasion is preferably 80 or more, more preferably 100 or more, still more preferably 120 or more.

In addition, the abrasion degree is a value obtained by measuring according to the "method of measuring the abrasion degree of optical glass of JOGIS10-1994".

Further, the optical glass of the present invention preferably has optical characteristics such as desired imaging characteristics in a wider temperature range.

In recent years, optical components such as projectors, photocopiers, laser printers, and broadcast equipment have been incorporated into more severe temperature environments. The situation of use increases. For example, in a projector, in order to meet the requirements of miniaturization and high resolution, it is necessary to use a high-intensity light source or a high-precision optical system. In particular, when a high-intensity light source is used, the temperature at which the optical element constituting the optical system is used is likely to vary greatly due to the influence of the heat generated by the light source, and the temperature is often higher than 100 °C. In this case, when a high-precision optical system is used, the influence of temperature fluctuation on the imaging characteristics of the optical system and the like becomes large, and it is required to constitute an optical which does not undergo fluctuations in optical characteristics due to temperature fluctuation. system.

Further, in an optical system which requires extremely high refractive index like an optical system of an optical apparatus having high resolution, there is a case where the influence of the use temperature on the imaging characteristics or the like cannot be ignored.

The optical glass of the present invention is preferably one which can obtain optical characteristics such as desired imaging characteristics over a wider temperature range.

The optical glass of the present invention preferably has a temperature coefficient of relative refractive index (dn/dT) close to zero. Specifically, the optical glass of the present invention preferably has a lower temperature coefficient (20 to 40 ° C) of a relative refractive index (589.29 nm), preferably -6.0 × 10 ^-6 ° C ^-1 , more preferably -5.5 × 10 ^-6 ° C ^-1 , further preferably -5.0 × 10 ^-6 ° C ^-1 . Thereby, even if the fluctuation of the refractive index is small in an environment in which the temperature of the optical element greatly changes, the desired optical characteristics can be exhibited with high precision in a wider temperature range.

On the other hand, if the temperature coefficient of the relative refractive index is excessively large in the positive direction, the change in the refractive index due to the temperature change of the optical element becomes large. Therefore, the optical glass of the present invention may have an upper limit of the temperature coefficient of the relative refractive index of more preferably 6.0 × 10 ^-6 ° C ^-1 , more preferably 5.5 × 10 ^-6 ° C ^-1 , still more preferably 5.0 × 10 ^-6 °C ^-1 . The optical glass of the present invention preferably has a temperature coefficient of relative refractive index of less than an absolute value, and is preferably 0.

Further, the temperature coefficient of the relative refractive index is the amount of change in the refractive index per 1 ° C when the temperature of the optical glass is changed while irradiating the light at a wavelength of 589.29 nm in the same temperature as the optical glass (×10 ^{-6 ).} °C ^-1 ) indicates.

[Preforms and optical components]

The optical glass of the present invention can be used in various optical elements and optical designs. Among them, it is particularly preferable to form a preform from the optical glass of the present invention, and to form a lens or a crucible by using a method such as grinding or precision press molding on the preform. Optical components such as mirrors. Thereby, when used in an optical machine such as a camera or a projector that allows visible light to penetrate the optical element, high-definition and high-precision imaging characteristics can be realized. Here, the method of producing the preformed body material is not particularly limited, and for example, a method of forming a glass gob as described in Japanese Patent Laid-Open No. Hei 8-319124, or a method described in Japanese Patent Laid-Open No. Hei 8-73229 A method of directly producing a preform material from molten glass like a method for producing an optical glass and a manufacturing apparatus, and a method of producing a preform material by cold working such as grinding and polishing of a strip formed of optical glass.

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

[Examples]

The composition of the glass of Examples 1 to 6 and Comparative Example 1 of the optical glass of the present invention (indicated by cation % or % of anion %), refractive index (nd), Abbe number (vd), The partial dispersion ratio (θg, F), the abnormal dispersion (Δθg, F), and the degree of wear are shown in Table 1.

The optical glasses of Examples 1 to 6 and Comparative Example 1 of the present invention are each produced by selecting, as a raw material of each component, oxides, carbonates, nitrates, fluorides, metaphosphoric compounds, and the like which are usually equivalent. The high-purity raw material used for the fluorophosphate glass is weighed and uniformly mixed so as to become the composition ratio of each of the examples and the comparative example 1 shown in Table 1, and then put into a platinum crucible, and melted according to the glass composition. The easiness is melted in an electric furnace at a temperature of 900 to 1200 ° C for 2 to 10 hours, and the mixture is homogenized and defoamed, and then the temperature is lowered to 850 ° C or less, and then cast into a mold to perform slow cooling to produce glass. .

Here, the refractive index (nd), the Abbe's number (vd), and the partial dispersion ratio (θg, F) of the optical glasses of Examples 1 to 6 and Comparative Example 1 were measured based on the Japanese Optical Glass Industry Association specification JOGIS01-2003. . In addition, as the glass used for the measurement, the annealing condition was used to set the slow cooling rate to -25 ° C / hr and to treat it in a slow cooling furnace. Then, the difference between the value of the partial dispersion ratio (θg, F) on the normal line of FIG. 1 and the value of the measured partial dispersion ratio (θg, F) under the measured Abbe number (vd) is obtained. Abnormal dispersion (Δθg, F).

Further, the degree of wear was measured in accordance with "JOGIS10-1994 Method for Measuring the Abrasion of Optical Glass". That is, a sample of a glass slab of 30 × 30 × 10 mm size is placed in a cast iron flatware (250 mm) rotated 60 times per minute in the horizontal direction. ) The starting position of 80 mm from the center is applied with a load of 9.8 N (1 kgf) vertically, and a uniform addition of #800 (average particle size of 20 μm) to 20 mL of water is supplied uniformly over 5 minutes. The polishing liquid obtained by 10 g of the material (alumina A abrasive grains) was rubbed, and the mass of the sample before and after the polishing was measured to determine the abrasion quality. Similarly, the wear quality of the standard sample specified by the Japan Optical Glass Industry Association was determined.

The degree of wear was calculated by the degree of wear = {(wear mass/specific gravity of the sample) / (wear mass/specific gravity of the standard sample)} × 100}.

In addition, the temperature coefficient (dn/dT) of the relative refractive index of the optical glass is measured by the interference method in the method described in the Japanese Optical Glass Industrial Standards JOGIS18-1994 "Method for Measuring the Temperature Coefficient of Refractive Index of Optical Glass". .

As shown in Table 1, the refractive indices (nd) of the optical glasses of Examples 1 to 6 of the present invention were all 1.40 to 1.60, and the Abbe number (vd) was 70 to 90.

Further, specifically, in any of the embodiments, the refractive index (nd) is 1.49 to 1.51, and the Abbe number (vd) is 78 to 81. Further, in any of the examples, the degree of wear was 400 or less. Further, the partial dispersion ratio (θg, F) is 0.520 or more, and the abnormal dispersion property (Δθg, F) is 0.013 or more.

On the other hand, the optical glass abrasion degree of the comparative example 1 outside the range of this invention becomes high.

As shown in the first table, the temperature coefficient (20 to 40 ° C) of the relative refractive index of the optical glasses of Examples 1 to 4 was -6.0 × 10 ^-6 ° C ^-1 or more, which was within the desired range.

Further, the optical glass of the embodiment of the present invention is used to form a preform for polishing, and then ground and polished to form a lens and a crucible. In addition, the preform for precision press molding is formed using the optical glass of the embodiment of the present invention, and the preform for precision press molding is subjected to precision press forming to be processed into a shape of a lens and a crucible. In either case, it can be processed into various lenses and shapes.

Fig. 1 is a view showing a regular line indicated by orthogonal coordinates in which a partial dispersion ratio (θg, F) is a vertical axis and an Abbe number (vd) is a horizontal axis.

Claims (9)

An optical glass containing at least one of P, Al, and Zn and further containing an alkaline earth metal as a cationic component, expressed as a cationic % (% by mole), and a Ba ²⁺ content of 0 to 15% (excluding 15%) And the optical glass contains O and F as an anion component, and the abrasion degree is 440 or less. The optical glass of claim 1 has a refractive index (nd) of 1.40 to 1.60 and an Abbe number (νd) of 70 to 90. The optical glass of claim 1 or 2, wherein the content of P ⁵⁺ is 20 to 50%, the content of Al ³⁺ is 8 to 30%, and the content of Mg ²⁺ is represented by % of cation (% by mole). The rate is 2 to 25%, the content of Ca ²⁺ is 5 to 30%, the content of Sr ²⁺ is 5 to 30%, and the content of Zn ²⁺ is 0.5 to 15%. The optical glass of claim 1 or 2, wherein the content of F ^- is represented by an anion % (% by mole) of 41 to 80%. The optical glass of claim 3, wherein the content of F ^- is represented by an anion % (% by mole) of 41 to 80%. An optical element comprising the optical glass of any one of claims 1 to 5. A preform comprising the optical glass of any one of claims 1 to 5 A preform for polishing and/or precision press forming of a glass. An optical component obtained by grinding a preform of claim 7. An optical element obtained by precisely pressing a preform as claimed in claim 7.