阅读说明：本技术 光学玻璃、光学元件以及预成形体 (Optical glass, optical element and preform ) 是由 荻野道子 于 2018-04-10 设计创作，主要内容包括：本发明提供一种光学玻璃、光学元件以及预成形体,能通过异常色散性较高的特性来高精确地校正玻璃透镜的色像差,此外,与以往的玻璃相比,更轻且磨耗度更低,更容易进行研磨加工。本发明的光学玻璃含有P<Sup>5+</Sup>、Al<Sup>3+</Sup>及Zn<Sup>2+</Sup>作为阳离子成分,并含有O<Sup>2-</Sup>及F<Sup>-</Sup>作为阴离子成分；以阳离子％计,含有P<Sup>5+</Sup>为25％至40％,Al<Sup>3+</Sup>为5％至20％,Zn<Sup>2+</Sup>为1％至15％,Ba<Sup>2+</Sup>为0％至28％；以阴离子％计,含有O<Sup>2-</Sup>为40％至70％,F<Sup>-</Sup>为30％至60％；且折射率(nd)为1.53至1.60,阿贝数(νd)为65至75,部分色散比θg,F值的范围为0.520至0.560,磨耗度范围在420以下。(The invention provides an optical glass, an optical element and a preform, which can correct chromatic aberration of a glass lens with high precision by the characteristic of high anomalous dispersion, and is lighter and lower in abrasion degree compared with the prior glass, and is easier to polish. The optical glass of the present invention contains P 5+ 、Al 3+ And Zn 2+ As a cationic component and containing O 2‑ And F ‑ As an anionic component; contains P in cationic% 5+ 25 to 40% of Al 3+ 5 to 20 percent of Zn 2+ 1% to 15% of Ba 2+ From 0% to 28%; contains O in terms of anion% 2‑ Is 40% to 70%％，F ‑ From 30% to 60%; and has a refractive index (nd) of 1.53 to 1.60, an Abbe's number (. nu.d) of 65 to 75, a partial dispersion ratio [ theta ] g, an F value in the range of 0.520 to 0.560, and an abrasion degree in the range of 420 or less.)

1. An optical glass, wherein,

containing P⁵⁺、Al³⁺And Zn²⁺As a cationic component and containing O^2-And F^-As an anionic component;

contains, in cation%:

P⁵⁺is 25 to 40 percent of the total weight of the composition,

Al³⁺is 5 to 20 percent of the total weight of the composition,

Zn²⁺is1 to 15 percent of the total weight of the composition,

Ba²⁺from 0% to 28%;

contains, in% of anions:

O^2-is 40 to 70 percent of the total weight of the composition,

F^-from 30% to 60%;

the optical glass has a refractive index (nd) of 1.53 to 1.60, an Abbe number (nd) of 65 to 75, and a degree of abrasion of 420 or less.

2. The optical glass as claimed in claim 1, wherein the temperature coefficient of the relative refractive index at 589.3nm at 40 ℃ to 60 ℃ is + 2.0X 10^-6℃^-1to-5.5X 10^-6℃^-1The range of (1).

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

Technical Field

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

Background

The lens system of an optical device is typically designed by combining a plurality of glass lenses having different optical properties. In recent years, characteristics required for a lens system of an optical device have been diversified, and in order to further widen the degree of freedom of design, an optical glass having optical characteristics that have not been noticed in the past has been developed. Among them, optical glasses characterized by anomalous dispersion properties (Δ θ g, F) have attracted attention because they exhibit remarkable effects in color correction of aberrations.

For example, patent document 1 proposes an optical glass having high anomalous dispersion properties, such as P-containing property, in addition to the properties of high refractive index, low dispersion properties, and excellent processability, which have been conventionally considered necessary⁵⁺、Al³⁺An alkaline earth metal ion or the like as a cationic component and F^-And O^2-As the anionic component.

Disclosure of Invention

Technical problem to be solved by the invention

However, the conventional optical glass described in patent document 1 has a low degree of abrasion and is poor in workability. That is, it is desired to develop an optical glass having workability while maintaining a high anomalous dispersion property.

The conventional optical glass described in patent document 2 is improved in abrasion but has a large specific gravity because it contains a large amount of Ba component, and is not suitable for use in a lens unit which is required to be light-weighted.

The object of the present invention is to solve the technical problem.

That is, an object of the present invention is to provide optical glass, an optical element, and a preform, which can correct chromatic aberration of a glass lens with high accuracy by virtue of characteristics of high anomalous dispersion, are lighter in weight than conventional products, have low abrasion, and can be polished more easily.

It is another object of the present invention to provide an optical glass that can be used in an optical system that hardly affects image forming characteristics even when temperature changes, for example, as an optical element incorporated in an optical device for a vehicle such as a drive recorder or an optical element incorporated in an optical device that generates a large amount of heat such as a projector, a copier, a laser printer, and a broadcasting device.

Means for solving the problems

The present inventors have made extensive studies to solve the above-mentioned problems, and as a result, the present invention has been completed.

The present invention is the following (1) to (3).

(1) An optical glass contains P⁵⁺、Al³⁺And Zn²⁺As a cationic component and containing O^2-And F^-As an anionic component;

contains, in cation%:

P⁵⁺is 25 to 40 percent of the total weight of the composition,

Al³⁺is 5 to 20 percent of the total weight of the composition,

Zn²⁺is1 to 15 percent of the total weight of the composition,

Ba²⁺from 0% to 28%;

contains, in% of anions:

O^2-is 40 to 70 percent of the total weight of the composition,

F^-from 30% to 60%;

and has a refractive index (nd) of 1.53 to 1.60, an Abbe's number (. nu.d) of 65 to 75, and an abrasion degree of 420 or less.

(2) The optical glass according to (1), wherein the temperature coefficient (40 ℃ C. to 60 ℃ C.) of the relative refractive index (546.07nm) is + 2.0X 10^-6(℃^-1) to-5.5X 10^-6(℃^-1) Example (A) ofInside the enclosure.

(3) An optical element comprising the optical glass according to (1) or (2).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide an optical glass which can correct chromatic aberration of a glass lens with high accuracy by the characteristic of high anomalous dispersion, is lighter in weight than conventional products, has low abrasion, and can be easily polished. Further, it is possible to provide an optical glass which can be used in an optical system which is difficult to affect the imaging characteristics and the like even if the temperature fluctuates.

Detailed Description

The present invention will be explained.

The present invention provides an optical glass containing P⁵⁺、Al³⁺And Zn²⁺As a cationic component and containing O^2-And F^-As an anionic component;

contains, in cation%:

P⁵⁺is 25 to 40 percent of the total weight of the composition,

Al³⁺is 5 to 20 percent of the total weight of the composition,

Zn²⁺is1 to 15 percent of the total weight of the composition,

Ba²⁺from 0% to 28%;

contains, in% of anions:

O^2-is 40 to 70 percent of the total weight of the composition,

F^-from 30% to 60%;

and has a refractive index (nd) of 1.53 to 1.60, an Abbe's number (. nu.d) of 65 to 75, and an abrasion degree in the range of 420 or less.

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

< glass composition >

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

In the present specification, the content of each component is expressed as cation% or anion% based on the molar ratio, unless otherwise specified. The "cation%" and "anion%" mean that the glass constituent components of the optical glass of the present invention are divided into a cation component and an anion component, and the total ratio is 100 mol%, respectively, to represent the composition of each component contained in the glass.

For the sake of simplicity, the ion valences of the respective components are representative values, and are not distinguished from other ion valences. The ion valence of each component present in the optical glass may be an ion valence other than the representative value. For example, since P is usually present in the glass in a state of ionic valence of 5, P is "P" in the present specification⁵⁺"but it still has the possibility of existing in other ionic valency states. Even if the element exists in another ion valence state in such a strict sense, the ion valence of each component is represented in the optical glass in the present specification.

[ regarding the cationic component ]

<P⁵⁺>

The optical glass of the present invention contains P⁵⁺。P⁵⁺Is a glass forming component, and has the properties of inhibiting glass from devitrifying and improving the refractive index.

Due to such enhanced properties, P⁵⁺The content of (b) is preferably 25.0% to 40.0%. Further, it is more preferably 26.0% or more, and still more preferably 28.0% or more. Further, it is more preferably 40.0% or less, still more preferably 38.0% or less, and further preferably 37.0% or less.

For example, Al (PO) can be used₃)₃、Ca(PO₃)₂、Ba(PO₃)₂、Zn(PO₃)₂、BPO₄、H₃PO₄Etc. as raw materials to contain P in the glass⁵⁺。

<Al³⁺>

The optical glass of the present invention contains Al³⁺。Al³⁺Has the properties of improving the devitrification resistance of the glass and reducing the abrasion degree.

Due to such enhanced properties, Al³⁺The content of (b) is preferably 5.0% to 20.0%. Further, it is more preferably 7.0% or more, and still more preferablyThe content is preferably 8.0% or more, more preferably 10.0% or more. Further, it is more preferably 19.0% or less, and still more preferably 17.0% or less.

For example, Al (PO) can be used₃)₃、AlF₃、Al₂O₃Etc. as raw materials to contain Al in the glass³⁺。

<Zn²⁺>

Has the properties of keeping the abrasion degree of the glass at the required value of the invention and improving the devitrification resistance. However, if the content is too large, the abrasion of the glass is deteriorated and the refractive index is lowered.

Zn²⁺The content of (b) is preferably 1.0% to 18.0%. Further, it is more preferably 2.0% or more, still more preferably 3.0% or more, and further preferably 16.0% or less. Further, it is more preferably 15.0% or less.

< alkaline earth metals >

In the optical glass of the present invention, the alkaline earth metal means Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺. In addition, R may be used^{2 +}To represent a group selected from Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺At least 1 of the group.

Furthermore, R²⁺The total content of (A) means the total content of the 4 kinds of ions (Mg)²⁺+Ca²⁺+Sr²⁺+Ba²⁺)。

R²⁺The total content of (A) is preferably 20.0% to 55.0%. This is because if the content is within this range, a more stable glass can be obtained.

R²⁺The total content of (a) is more preferably 27.0% or more, and still more preferably 29.0% or more. Further, it is more preferably 55.0% or less, still more preferably 53.0% or less, and further preferably 50.0% or less.

<Mg²⁺>

The optical glass of the present invention contains Mg²⁺。Mg²⁺Has the properties of improving the devitrification resistance of the glass and reducing the abrasion degree.

Because of such enhanced properties, Mg²⁺The content of (b) is preferably 0.0% to 20.0%. Further, it is more preferably 1.0% or more, and still more preferably 2.0% or more. Further, it is more preferably 18.0% or less, and still more preferably 15.0% or less.

MgO, MgF, for example, can be used₂Etc. as raw materials to contain Mg in the glass²⁺。

<Ca²⁺>

The optical glass of the present invention preferably contains Ca²⁺。Ca²⁺Has the properties of improving resistance to devitrification, suppressing lowering of refractive index, and reducing glass abrasion.

Due to such enhanced properties, Ca²⁺The content of (b) is preferably 0.0% to 25.0%. Further, it is more preferably 2.0% or more, and still more preferably 3.0% or more. Further, it is more preferably 23.0% or less, and still more preferably 20.0% or less.

For example, Ca (PO) can be used₃)₂、CaCO₃、CaF₂Etc. as raw materials to contain Ca in the glass²⁺。

<Sr²⁺>

The optical glass of the present invention contains Sr²⁺To be used as a kind of R²⁺(alkaline earth metals). Sr²⁺Has the properties of improving the devitrification resistance of the glass and suppressing the lowering of the refractive index.

Due to such enhanced properties, Sr²⁺The content of (b) is preferably 0% to 20.0%. Further, it is more preferably 1.0% or more, and still more preferably 2.0% or more. Further, it is more preferably 18.0% or less, and still more preferably 16.0% or less.

Use may be made of, for example, Sr (NO)₃)₂、SrF₂Etc. as raw materials to contain Sr in the glass²⁺。

<Ba²⁺>

The optical glass of the present invention has a Ba content²⁺To be used as a kind of R²⁺(alkaline earth metals). When contained in a predetermined amount, Ba²⁺Has the advantages of improvementResistance to devitrification of the glass. In addition, the composition has the properties of maintaining low dispersion and improving refractive index. However, if the content is too large, the specific gravity may become too large, and thus it may be difficult to use the lens unit as a component.

Ba is enhanced by such properties²⁺The content of (b) is preferably 0% to 30.0%. Further, it is preferably 1.0% or more, and more preferably 3.0% or more. More preferably 28.0% or less, and still more preferably 23.0% or less.

For example, Ba (PO) can be used₃)₂、BaCO₃、Ba(NO₃)₂、BaF₂Etc. as raw materials to contain Ba in the glass²⁺。

<Ln³⁺>

In the present invention, Ln³⁺Represents a group selected from Y³⁺、La³⁺、Gd³⁺、Yb³⁺And Lu³⁺At least 1 of the group. Furthermore, Ln³⁺The total content of (C) means the total content (Y) of the 5 ions³⁺+La³⁺+Gd³⁺+Yb³⁺+Lu³⁺)。

The optical glass of the present invention preferably contains Ln in a state that the total content is 10.0% or less³⁺. This is because the content in such a range tends to increase the refractive index of the glass and lower the dispersion. Further, it is preferably 9.0% or less, more preferably 8.0% or less, and further preferably 7.0% or less. Furthermore, due to Ln³⁺The optical glass of the present invention may contain no Ln because of its optional components³⁺。

<Y³⁺>

The optical glass of the present invention may contain Y³⁺As Ln³⁺1 kind of (1). Y is³⁺Has the properties of maintaining low dispersion, improving refractive index and improving devitrification resistance. However, since stability is easily deteriorated when the content is excessive, the content is preferably 10.0% or less, more preferably 8.0% or less, and still more preferably 7.0% or less. Furthermore, even if Y is not contained³⁺Still, the glass of the present invention can be obtainedGlass, so that Y may not be contained in this viewpoint³⁺。

Use may be made of, for example, Y₂O₃、YF₃Etc. as raw materials to contain Y in the glass³⁺。

<La³⁺>

The optical glass of the present invention may contain La³⁺As Ln³⁺1 kind of (1). La³⁺Has the properties of maintaining low dispersion and improving refractive index.

Due to such enhanced properties, La³⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 7.0% or less.

For example, La can be used₂O₃、LaF₃Etc. as raw materials to make the glass contain La³⁺。

<Gd³⁺>

The optical glass of the present invention may contain Gd³⁺As Ln³⁺1 kind of (1). Gd (Gd)³⁺Has the properties of maintaining low dispersion, increasing refractive index, and further improving resistance to devitrification.

Because of this enhanced property, Gd³⁺The content of (b) is more preferably 10.0% or less, still more preferably 8.0% or less, and still more preferably 7.0% or less.

For example Gd may be used₂O₃、GdF₃Etc. as raw materials to contain Gd in the glass³⁺。

<Yb³⁺>

The optical glass of the present invention may contain Yb³⁺As Ln³⁺1 kind of (1). Yb of³⁺Has the properties of maintaining low dispersion, increasing refractive index, and further improving resistance to devitrification.

Yb due to such enhanced properties³⁺The content of (b) is more preferably 10.0% or less, still more preferably 8.0% or less, and still more preferably 7.0% or less.

For example Yb can be used₂O₃Etc. as raw materials to contain Yb in the glass³⁺。

<Lu³⁺>

The optical glass of the present invention may contain Lu³⁺As Ln³⁺1 kind of (1). Lu (Lu)³⁺Has the properties of maintaining low dispersion, increasing refractive index, and further improving resistance to devitrification.

Due to such enhanced properties, Lu³⁺The content of (b) is more preferably 9.0% or less, still more preferably 8.0% or less, and still more preferably 7.0% or less.

For example, Lu can be used₂O₃Etc. as raw materials to make the glass contain Lu³⁺。

<Si⁴⁺>

The optical glass of the present invention may contain Si⁴⁺As an arbitrary component. When contained in a predetermined amount, Si⁴⁺Has the properties of improving the devitrification resistance of the glass, improving the refractive index and reducing the abrasion degree.

Due to such enhanced properties, Si⁴⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, SiO₂、K₂SiF₆、Na₂SiF₆Etc. as raw materials to contain Si in the glass⁴⁺。

<B³⁺>

The optical glass of the present invention may contain B³⁺As an arbitrary component. When it contains a predetermined amount, B³⁺The glass has properties of improving devitrification resistance, lowering abrasion resistance while increasing the refractive index, and further making it difficult to deteriorate chemical durability.

Due to such enhanced properties, B³⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

May be used, for example, as H₃BO₃、Na₂B₄O₇、BPO₄Etc. as raw materials to make the glass contain B³⁺。

<Li⁺>

Hair brushThe clear optical glass may also contain Li⁺As an arbitrary component. Li⁺Has a property of lowering the glass transition point (Tg) while maintaining resistance to devitrification at the time of glass formation.

Due to such enhanced properties, Li⁺The content of (b) is preferably 10.0% or less, more preferably 5.0% or less, and still more preferably 1.0% or less.

It is possible to use, for example, Li₂CO₃、LiNO₃Or LiF, etc., as raw materials to contain Li in the glass⁺。

<Na⁺>

The optical glass of the present invention may contain Na⁺As an arbitrary component. Na (Na)⁺Has a property of lowering the glass transition point (Tg) while maintaining resistance to devitrification at the time of glass formation.

Due to such enhanced properties, Na⁺The content of (b) is preferably 10.0% or less, more preferably 9.5% or less, and further preferably 5.0% or less.

For example, Na can be used₂CO₃、NaNO₃、NaF、Na₂SiF₆Etc. as raw materials to contain Na in the glass⁺。

<K⁺>

The optical glass of the present invention may also contain K⁺As an arbitrary component. K⁺Has a property of lowering the glass transition point (Tg) while maintaining resistance to devitrification at the time of glass formation.

Due to such enhanced properties, K⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

May use, for example, K₂CO₃、KNO₃、KF、KHF₂、K₂SiF₆Etc. as raw materials to make the glass contain K⁺。

<Rn⁺>

In the optical glass of the present invention, Rn⁺(Rn⁺Is selected from Li⁺、Na⁺And K⁺At least 1 of the group) The total content of (a) is preferably 20.0% or less, more preferably 15.0% or less, and still more preferably 10.0% or less.

<Nb⁵⁺>

The optical glass of the present invention may contain Nb⁵⁺As an arbitrary component. Nb⁵⁺Has the properties of increasing the refractive index of the glass, improving chemical durability, and further suppressing the lowering of the Abbe number.

Due to such enhanced properties, Nb⁵⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, Nb₂O₅Etc. as raw materials to contain Nb in the glass⁵⁺。

<Ti⁴⁺>

The optical glass of the present invention may also contain Ti⁴⁺As an arbitrary component. Ti⁴⁺Has the property of improving the refractive index of the glass.

Due to such enhanced properties, Ti⁴⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, TiO₂Etc. as raw materials to contain Ti in the glass⁴⁺。

<Zr⁴⁺>

The optical glass of the present invention may contain Zr⁴⁺As an arbitrary component. Zr⁴⁺Has the property of improving the refractive index of the glass.

Due to such enhanced properties, Zr⁴⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, ZrO₂、ZrF₄Etc. as raw materials to contain Zr in the glass⁴⁺。

<Ta⁵⁺>

The optical glass of the present invention may contain Ta⁵⁺As an arbitrary component. Ta⁵⁺Has the property of improving the refractive index of the glass.

Since this is the caseThe properties of the sample are enhanced, thus Ta⁵⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, Ta₂O₅Etc. as raw materials to contain Ta in the glass⁵⁺。

<W⁶⁺>

The optical glass of the present invention may contain W⁶⁺As an arbitrary component. W⁶⁺Has the properties of improving the refractive index of the glass and reducing the transfer point of the glass.

Due to such enhanced properties, W⁶⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, WO₃Etc. as raw materials to make W contained in the glass⁶⁺。

<Ge⁴⁺>

The optical glass of the present invention may contain Ge⁴⁺As an arbitrary component. Ge (germanium) oxide⁴⁺Has the properties of improving the refractive index of the glass and improving the devitrification resistance of the glass.

Since such properties become apparent, Ge⁴⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, GeO₂Etc. as raw materials to contain Ge in the glass⁴⁺。

<Bi³⁺>

The optical glass of the present invention may contain Bi³⁺As an arbitrary component. Bi³⁺Has the properties of improving the refractive index of the glass and reducing the transfer point of the glass.

Due to such enhanced properties, Bi³⁺The content of (b) is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 5.0% or less.

It is possible to use, for example, Bi₂O₃Etc. as raw materials to contain Bi in the glass³⁺。

<Te⁴⁺>

The inventionThe optical glass may contain Te⁴⁺As an arbitrary component. Te (Te)⁴⁺Has the properties of improving the refractive index of the glass, reducing the transfer point of the glass and inhibiting coloring.

Due to such enhanced properties, Te⁴⁺The content of (b) is preferably 15.0% or less, more preferably 10.0% or less, still more preferably 8.0% or less, and further preferably 5.0% or less.

For example TeO can be used₂Etc. as raw materials to contain Te in the glass⁴⁺。

[ regarding the anionic component ]

<F^->

The optical glass of the present invention contains F^-。F^-Has the properties of improving the abnormal dispersibility and Abbe number of the glass and further making the glass difficult to devitrify.

Due to such enhanced properties, F^-The content of (b) is preferably 30.0% to 60.0%, as represented by anion% (mol%). Further, it is more preferably 30.0% or more, still more preferably 33.0% or more, and further preferably 36.0% or more.

Further, it is more preferably 60.0% or less, still more preferably 55.0% or less, and still more preferably 50.0% or less.

For example, AlF can be used₃、MgF₂、BaF₂Etc. of various cationic components as a raw material to contain F in the glass^-。

<O^2->

The optical glass of the present invention contains O^2-。O^2-Has the property of inhibiting the increase of the abrasion degree of the glass.

Due to such enhanced properties, O^2-The content of (b) is preferably 40.0% to 70.0%, as represented by anion% (mol%). Further, it is more preferably 40.0% or more, still more preferably 45.0% or more, and further preferably 50.0% or more.

Further, it is more preferably 70.0% or less, still more preferably 66.0% or less, and still more preferably 64.0% or less.

Furthermore, O^2-Content ratio of (A) and (F)^-The total content of (b) is preferably 98.0% or more, more preferably 99.0% or more, and further preferably 100%, in terms of anion%. This is because a stable glass can be obtained by the total amount.

For example, Al can be used₂O₃Oxides of various cationic components such as MgO and BaO, or Al (PO)₃)₃、Mg(PO₃)₂、Ba(PO₃)₂Phosphate of various cationic components, etc. as a raw material to contain O in the glass^2-。

The optical glass of the present invention may contain other components as required within a range not impairing the characteristics of the glass of the present invention.

[ regarding components 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 suitable to be contained therein will be described.

In addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, which are contained alone or in a composite form, are preferably not substantially contained in optical glass using a wavelength in the visible region because the glass is colored even if contained in a small amount and has a property of absorbing light having a specific wavelength in the visible region.

Further, cations of Pb, Th, Cd, Tl, Os, Be, and Se are considered as harmful chemical substances in recent years and tend to Be avoided, and measures against the environment are required not only in the glass production step but also in the processing step and in the disposal after the product formation. Therefore, when importance is attached to the influence on the environment, it is preferable that these components are not substantially contained except for unavoidable mixing. Thus, the optical glass can be substantially free of substances contaminating the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special measures for environmental countermeasures.

In addition, Sb functions as an antifoaming agent, but in recent years, Sb is considered to be a component that is harmful to the environment, and therefore tends not to be contained in the optical glass, and from this viewpoint, it is preferable not to contain Sb.

[ production method ]

The method for producing the optical glass of the present invention is not particularly limited. The optical glass of the present invention can be produced, for example, in the following manner: the raw materials are uniformly mixed to ensure that the content of each component is within the range of the specified content, the prepared mixture is put into a quartz crucible, an alumina crucible or a platinum crucible for primary melting, then the mixture is put into a platinum crucible, a platinum alloy crucible or an iridium crucible for melting for 2 to 10 hours at the temperature of 900 to 1200 ℃, the mixture is stirred for homogenization and defoaming, and the temperature is reduced to below 850 ℃, then the mixture is stirred for removing textures at the final stage, and the mixture is cast into a casting mold and slowly cooled.

[ Properties ]

The optical glass of the present invention is characterized by a partial dispersion ratio (θ g, F). Therefore, an optical glass that can correct chromatic aberration with high accuracy can be obtained.

The partial dispersion ratio (θ g, F) is preferably 0.520 or more, more preferably 0.522 or more, and still more preferably 0.524 or more.

Further, it is preferably 0.560 or less, more preferably 0.558 or less, and further preferably 0.556 or less.

Further, the partial dispersion ratio (θ g, F) is a value obtained by measurement according to the Japanese society for optical glass Standard JOGIS 01-2003.

Hereinafter, the partial dispersion ratio (θ g, F) and the anomalous dispersion property (Δ θ g, F) will be described, and 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 (θ g, F) will be described.

The partial dispersion ratio (θ g, F) is a ratio of differences in refractive index in a certain 2 wavelength region among the wavelength dependency of the refractive index, and is represented by the following formula (1).

θg,F＝(n_g-n_F)/(n_F-n_C) ..

Here, n is_gDenotes the refractive index of g line (435.83nm), n_FDenotes the refractive index of F line (486.13nm), n_CThe refractive index of the C line (656.27nm) is shown.

Then, the relationship between the partial dispersion ratio (θ g, F) and the abbe number (ν d) is plotted on an XY coordinate graph, and in the case of a general optical glass, it is basically plotted on a straight line called a standard line. The standard line is a straight line extending upward and rightward (on a rectangular coordinate) on an XY coordinate diagram (on an XY coordinate) having a vertical axis of the partial dispersion ratio (θ g, F) and a horizontal axis of the abbe number (ν d), the straight line connecting 2 points of the partial dispersion ratio and the abbe number of the NSL7 and the PBM2 (see fig. 1). Although standard glasses serving as a reference of the standard line vary from optical glass manufacturer to optical glass manufacturer, almost all the manufacturers define the standard glass with the same slope and intercept (NSL7 and PBM2 are optical glasses manufactured by mini-original gmbh, the abbe number (vd) of NSL7 is 60.5, the partial dispersion ratio (θ g, F) is 0.5436, the abbe number (vd) of PBM2 is 36.3, and the partial dispersion ratio (θ g, F) is 0.5828).

With respect to such a partial dispersion ratio, the anomalous dispersion property (Δ θ g, F) is expressed as: the degree of the drawing point of the partial dispersion ratio (θ g, F) and the abbe number (vd) from the standard line in the vertical axis direction. An optical element made of glass having a large anomalous dispersion (Δ θ g, F) has a property of being capable of correcting chromatic aberration generated by other lenses in a wavelength range near blue.

In the middle-low dispersion region (region having an abbe number of about 55 or more), the anomalous dispersion (Δ θ g, F) tends to become larger as the abbe number (ν d) becomes larger in the past. Furthermore, it is difficult to keep the degree of abrasion 420 or less and the abnormal dispersibility tends to be maintained at a high value.

As a result of intensive studies by the present inventors, an optical glass having a high value of anomalous dispersion (Δ θ g, F) with respect to abbe's number (ν d) and good processability was successfully developed.

The optical glass of the present invention has a low dispersion property (high Abbe number) in addition to a high refractive index (nd).

In the optical glass of the present invention, the refractive index (nd) is preferably 1.50 to 1.60. The refractive index (nd) is preferably 1.50 or more, more preferably 1.51 or more. Further, it is preferably 1.59 or less, more preferably 1.58 or less.

In the optical glass of the present invention, the abbe number (ν d) is preferably 60 to 80.

The abbe number is preferably 62 or more, more preferably 64 or more, and still more preferably 80 or more. Further, it is preferably 78 or less, and more preferably 76 or less.

The refractive index and Abbe number are values measured according to the Japanese society for optical glass Standard JOGIS 01-2003.

The degree of abrasion is particularly preferably low, and is preferably 420 or less. Therefore, unnecessary abrasion or damage of the optical glass can be reduced, and the optical glass can be easily polished and processed.

The degree of wear is more preferably 415 or less, and still more preferably 410 or less.

On the other hand, if the degree of wear is too low, polishing tends to be difficult. Therefore, the degree of wear is preferably 200 or more, more preferably 210 or more, and further preferably 220 or more.

Further, the abrasion degree means a value obtained by measurement according to "abrasion degree measuring method of optical glass by JOGIS 10-1994".

The optical glass of the present invention has a low temperature coefficient of relative refractive index (dn/dT).

More specifically, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably + 3.0X 10 as the upper limit value^-6℃^-1More preferably, + 2.0X 10^-6℃^-1Still more preferably, + 1.0X 10^-6℃^-1More preferably 0X 10^-6℃^-1And the temperature coefficient of the relative refractive index may be the upper limit value or a value lower (decrease side) than the upper limit value.

On the other hand, the lower limit of the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably-5.5X 10^-6℃^-1More preferably-4.5X 10^-6℃^-1Still more preferably-4.0X 10^-6℃^-1Further preferred is-3.7X 10^-6℃^-1Most preferably-3.0X 10^-6℃^-1The temperature coefficient of the relative refractive index may be the lower limit value or a value higher (increase side) than the lower limit value.

Among them, glasses in which the temperature coefficient of the relative refractive index becomes negative are hardly known, and selection of correction of conditions such as image defocus due to temperature change is increased. Further, a glass having a small absolute value of the temperature coefficient of the relative refractive index can more easily correct the imaging defocus and the like caused by the temperature change. Therefore, by setting the temperature coefficient of the relative refractive index in such a range, it is possible to contribute to correction of imaging defocus and the like due to temperature change.

The temperature coefficient of relative refractive index of the optical glass of the present invention is a temperature coefficient of refractive index (589.3nm) of the optical glass relative to air at the same temperature, and when the temperature is changed from 40 ℃ to 60 ℃, the change amount (DEG C) per 1 ℃ corresponds to^-1) To indicate.

[ preform and optical element ]

The optical glass of the present invention can function in various optical elements and optical designs, but among them, it is particularly preferable to form a preform from the optical glass of the present invention and produce optical elements such as lenses, prisms, mirrors, etc. by polishing or precision press molding the preform. Thus, when the optical element is used in an optical device such as a camera or a projector which transmits visible light through the optical element, high-definition and high-precision imaging characteristics can be realized. Here, the method for producing the preform is not particularly limited, and for example, a method for forming a glass gob described in japanese patent application laid-open No. 8-319124, a method for directly producing a preform from molten glass as described in the method and apparatus for producing optical glass of japanese patent application laid-open No. 8-73229, or a method for cold working by grinding or the like a strip formed of optical glass can be used.

Further, if the optical glass of the present invention can obtain desired optical characteristics such as image forming characteristics in a wider temperature range, it is preferable to use the optical glass of the present invention because a more desirable preform and optical element can be obtained.