JP6937540B2 - Optical glass, preforms and optics - Google Patents

Description

The present invention relates to optical glass, preforms and optical elements.

Optical systems such as digital cameras and video cameras, although they are large and small, contain bleeding called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration, and in particular, chromatic aberration strongly depends on the material properties of the lens used in the optical system.

Generally, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens, but this combination can only correct aberrations in the red region and the green region, and aberrations in the blue region remain. This aberration in the blue region that cannot be completely removed is called a quadratic spectrum. In order to correct the secondary spectrum, it is necessary to carry out an optical design that takes into account the trend of the g-line (435.835 nm) in the blue region. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics attracting attention in the optical design. In the optical system combining the above-mentioned low-dispersion lens and high-dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low-dispersion side lens, and a partial dispersion ratio (partial dispersion ratio) is used for the high-dispersion side lens. By using an optical material having a small θg, F), the secondary spectrum is satisfactorily corrected.

The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = ( _ng −n _F ) / (n _F −n _C ) ・ ・ ・ ・ ・ ・ ・ ・ (1)

In optical glass, there is a substantially linear relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _{d), which represent the partial dispersibility in the short wavelength region.} The straight line representing this relationship is a plot of the partial dispersion ratio and Abbe number of NSL7 and PBM2 on Cartesian coordinates with the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _{d) on the horizontal axis.} It is represented by a straight line connecting two points and is called a normal line (see FIG. 1). The normal glass, which is the standard of the normal line, differs depending on the optical glass manufacturer, but each company defines it with almost the same inclination and intercept. (NSL7 and PBM2 are optical glasses manufactured by O'Hara Co., Ltd., the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7. Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

_{In recent years, due to the needs in optical design, glass having an Abbe number (ν d} ) of 30 or more and 47 or less is often used as an optical material having a small partial dispersion ratio (θg, F). _{Here, as a conventional glass having an Abbe number (ν d} ) of 30 or more and 47 or less,, for example, optical glass as shown in Patent Documents 1 and 2 is known.

JP-A-2002-209777 Japanese Unexamined Patent Publication No. 2008-239478

However, the glass disclosed in Patent Document 1 does not have a small partial dispersion ratio, and is not sufficient for use as a lens for correcting the secondary spectrum. Further, although the glass disclosed in Patent Document 2 has a relatively small partial dispersion ratio, it has a large Abbe number, so that a glass having a smaller Abbe number has been required. Further, there is a problem that the stability of the glass is poor and the productivity is significantly lowered.

The present invention has been made in view of the above problems, and an object of the present invention is to have a partial dispersion ratio ( _{n d} ) and an Abbe number (ν _{d) within desired ranges.} The purpose is to obtain an optical glass having a small θg, F).

As a result of intensive test research to solve the above problems, the present inventors have found _{that a glass containing a SiO 2} component and an Nb ₂ O ₅ component has a high refractive index and a low Abbe number (high) within a desired range. Dispersion) and found that a glass having a low partial dispersion ratio can be obtained, and have completed the present invention.

(1) By mass% of oxide equivalent composition,
SiO ₂ component 20.0 to 60.0%,
It _{contains 20.0 to 45.0% of Nb 2} O ₅ component and 1.0 to 20.0% of ZrO ₂ component.
_{Refractive index (nd} ) of 1.60 or more and 1.75 or less,
_{It has an Abbe number (ν d} ) of 30 or more and 47 or less,
The partial dispersion ratio (θg, F) is _{between the Abbe number (ν d} ) and (-0.00256 x ν _d +0.637) ≤ (θg, F) ≤ (-0.00256 x ν _d +0.684). ) Satisfying the relationship.

(2) By mass% of oxide equivalent composition,
ZnO component 0 to 25.0%,
Na ₂ O component 0 to 20.0%,
Li ₂ O component 0 to 20.0%,
K ₂ O component 0 to 10.0%,
The optical glass according to (1).

(3) By mass% of oxide equivalent composition,
B ₂ O ₃ component 0 to 20.0%,
TiO ₂ component 0 to 15.0%,
MgO component 0-10.0%,
CaO component 0-10.0%,
SrO component 0-10.0%,
BaO component 0-10.0%,
La ₂ O ₃ component 0 to 10.0%,
Gd ₂ O ₃ component 0 to 10.0%,
Y ₂ O ₃ component 0 to 10.0%,
Yb ₂ O ₃ component 0 to 10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
WO ₃ component 0-10.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0-10.0%,
Al ₂ O ₃ component 0 to 10.0%,
Ga ₂ O ₃ component 0 to 10.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ component 0-5.0%,
SnO ₂ component 0-1.0%,
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) and (2).

(4) The optical glass according to any one of (1) to (3), wherein the mass ratio (Li ₂ O + K ₂ O) / (ZrO ₂ + Li _{2 O) is more than 0 and less than 2.5.}

(5) By mass% based on oxide
The mass sum of the Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 0 to 15.0%.
The mass sum of the Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is 0 to 30.0%.
The mass sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 0 to 20.0%.
The optical glass according to any one of (1) to (4).

(6) Any of (1) to (5) in which the _{wavelength (λ 80} ) showing a spectral transmittance of 80% is 420 nm or less and the wavelength (λ _{5) showing a spectral transmittance of 5% is 365 nm or less.} The optical glass described.

(7) A preform for polishing and / or precision press molding made of the optical glass according to any one of (1) to (6).

(8) An optical element made of the optical glass according to any one of (1) to (6).

According to the present invention, it is possible to obtain an optical glass having reduced glass opalescence and devitrification in the reheat pressing process at a lower cost while _{the refractive index (nd} ) and Abbe number (ν _{d) are within desired ranges.} can.

It is a figure which shows the normal line where the partial dispersion ratio (θg, F) is represented by the vertical axis, and the Abbe number (ν _d ) is represented by the Cartesian coordinates of the horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _{d) for the Example of this application.}

In the optical glass of the present invention, the SiO ₂ component is 20.0 to 60.0%, the Nb ₂ O ₅ component is 20.0 to 45.0%, and the ZrO ₂ component is 1. contains 0 to 20.0%, a 1.60 or 1.75 or less of the refractive index _{(n d),} 30 or more 47 or less in Abbe number ([nu _d), the partial dispersion ratio ([theta] g, F) Satisfies the relationship of (−0.00256 × ν _d +0.637) ≦ (θg, F) ≦ (−0.00256 × ν _d +0.684) with the Abbe number (ν _d).
In _{a glass containing a SiO 2} component, an Nb ₂ O ₅ component, and a ZrO ₂ component, a glass having a high refractive index within a desired range, a low Abbe number (high dispersion), and a low partial dispersion ratio can be obtained.
Therefore, it is possible to obtain desired while having a high refractive index (n _d) and low Abbe number ([nu _d), the partial dispersion ratio ([theta] g, F) useful optical glass in reducing chromatic aberration is small optical system ..

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention. .. It should be noted that the description may be omitted as appropriate for the parts where the explanations are duplicated, but the gist of the invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise specified in the present specification, the content of each component shall be expressed as a mass% of the total mass of the glass in the oxide conversion composition. Here, the "oxide-equivalent composition" is based on the assumption that the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed at the time of melting and changed to oxides. It is a composition which describes each component contained in a glass, assuming that the total mass of the produced oxide is 100 mass%.

<About essential ingredients and optional ingredients>
The SiO ₂ component is an essential component for reducing devitrification (generation of crystals), which is unfavorable for optical glass, because it can promote stable glass formation and lower the liquidus temperature.
In particular, by _{setting the content of the SiO 2} component to 20.0% or more, a glass having excellent devitrification resistance can be obtained without significantly increasing the partial dispersion ratio. Further, this can reduce devitrification and coloring at the time of reheating. Therefore, the _{lower limit of the content of the SiO 2} component is preferably 20.0%, more preferably 25.0%, still more preferably 30.0%, still more preferably 32.0%.
On the other hand, by _{setting the content of the SiO 2} component to 60.0% or less, the refractive index is less likely to decrease, so that a desired high refractive index can be easily obtained and an increase in the partial dispersion ratio can be suppressed. Further, this can suppress a decrease in the meltability of the glass raw material. Therefore, _{the content of the SiO 2} component is preferably 60.0%, more preferably 55.0%, still more preferably 50.0%, still more preferably 47.0%, still more preferably 44.0%. And.
As the SiO _{2 component, SiO 2} , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

The Nb ₂ O ₅ component is an essential component capable of increasing the refractive index, reducing the Abbe number and the partial dispersion ratio, and enhancing the devitrification resistance.
In particular, _{by increasing the content of the Nb 2} O ₅ component to 20.0% or more, the refractive index is increased to the target optical constant and adjusted within the range of the present invention to reduce the anomalous dispersibility. can do. Therefore, the _{lower limit of the content of the Nb 2} O ₅ component is preferably 20.0%, more preferably 22.0%, and even more preferably 23.0%.
On the other hand, _{by reducing the content of the Nb 2} O ₅ component to 45.0% or less, the material cost of the glass can be reduced. In addition, it is possible to suppress an increase in the melting temperature during glass production and reduce devitrification due to excessive inclusion of the _{Nb 2} O _{5 component.} Therefore, _{the content of the Nb 2} O ₅ component is preferably 45.0%, more preferably 40.0%, still more preferably 35.0%, still more preferably 30.0%.
As the Nb ₂ O _{5 component, Nb 2} O ₅ or the like can be used as a raw material.

ZrO ₂ component increases the refractive index of the glass and the Abbe number, low partial dispersion ratio, which is an essential component capable of and enhance resistance to devitrification. Further, this can reduce devitrification and coloring at the time of reheating. Therefore, the content of the ZrO ₂ component is preferably 1.0% or more, more preferably 3.0% greater, more preferably 5.0 percent.
On the other hand, by the content of the ZrO ₂ component below 20.0%, it is possible to reduce the devitrification and can be easy to obtain a more homogeneous glass. Therefore, the content of the ZrO ₂ component is preferably 20.0% is more preferably 18.0%, more preferably 15.0%, more preferably 13.0%, more preferably up to 10.0% And.
As the ZrO _{2 component, ZrO 2} , ZrF _4, or the like can be used as a raw material.

The ZnO component is an optional component that is inexpensive, can improve devitrification resistance, and can lower the glass transition point when it contains more than 0%. Therefore, the content of the ZnO component may be preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.
On the other hand, by reducing the content of the ZnO component to 25.0% or less, it is possible to improve the chemical durability while reducing devitrification and coloring when the glass is reheated. Therefore, the content of the ZnO component is preferably 25.0% or less, more preferably 20.0% or less, still more preferably less than 18.0%, still more preferably less than 14.0%, still more preferably 10.0. It shall be less than%.

When the Na ₂ O component is contained in excess of 0%, the partial dispersion ratio can be lowered, the liquidus temperature can be lowered, and the meltability of the glass raw material can be improved. Therefore, _{the content of the Na 2} O component may be preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably more than 5.0%.
On the other hand, by _{setting the content of the Na 2} O component to 20.0% or less, it is possible to suppress a decrease in the refractive index, make it difficult for the chemical durability to deteriorate, and reduce devitrification due to an excessive content.
Therefore, _{the content of the Na 2} O component is preferably 20.0% or less, more preferably 15.0% or less, still more preferably less than 10.0%, still more preferably less than 8.0%.
As the Na ₂ O component, Na ₂ CO ₃ , _{Na NO 3} , NaF, Na ₂ SiF _6, or the like can be used as a raw material.

When the Li ₂ O component is contained in excess of 0%, the partial dispersion ratio can be lowered, the transmittance can be improved, the liquidus temperature can be lowered, and the meltability of the glass raw material can be enhanced. Therefore, _{the content of the Li 2} O component may be preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably more than 5.0%.
On the other hand, by _{setting the content of the Li 2} O component to 20.0% or less, it is possible to suppress a decrease in the refractive index, make it difficult for the chemical durability to deteriorate, and reduce devitrification due to an excessive content.
Therefore, _{the content of the Li 2} O component is preferably 20.0% or less, more preferably 15.0% or less, still more preferably less than 10.0%, still more preferably less than 8.0%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF or the like can be used as a raw material.

K 2 _O component, when ultra containing 0%, increased meltability of the glass raw material, which is an optional component that and can lower the liquidus temperature. Therefore, the content of _{K 2} O component is preferably 0 percent, more preferably 0.5 percent, more preferably be 1.0 percent.
On the other hand, by the content of K 2 _O ingredient 10.0% or less, suppressed the increase in the partial dispersion ratio can reduce the devitrification, and can hardly deteriorates chemical durability. Therefore, the content of _{K 2} O component is preferably 10.0% or less, more preferably less than 8.0%, more preferably less than 5.0%.
As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _{6, and the} like can be used as raw materials.

When the B ₂ O ₃ component is contained in excess of 0%, stable glass formation can be promoted and the liquidus temperature can be lowered, so that the devitrification resistance can be enhanced and the meltability of the glass raw material can be enhanced. It is an optional ingredient. Therefore, _{the content of the B 2} O ₃ component may be preferably more than 0%, more preferably more than 0.1%, and even more preferably more than 1.0%. In particular, from the viewpoint of forming the molten glass at a low temperature to improve the devitrification resistance and reduce the veins, it is desirable and more preferably 5 to contain 3.0% or more _{of the B 2} O _{3 component.} It may be 0.0% or more, more preferably 7.0% or more.
On the other hand, by _{setting the content of the B 2} O ₃ component to 20.0% or less, the decrease in the refractive index can be suppressed and the increase in the partial dispersion ratio can be suppressed. Therefore, _{the content of the B 2} O ₃ component is preferably 20.0%, more preferably 18.0%, still more preferably 15.0%, still more preferably 12.0%.
B ₂ O ₃ component can be used _H 3 _BO 3 as a starting _{material, Na 2 B 4 O 7,} Na 2 B 4 O 7 · 10H 2 O, the BPO ₄ and the like.

The TiO ₂ component is an optional component that increases the refractive index, lowers the Abbe number, and enhances the devitrification resistance when it contains more than 0%.
On the other hand, _{by reducing the content of the TiO 2} component to 15.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. Further, since this makes it difficult for the partial dispersion ratio to increase, it is possible to easily obtain a desired low partial dispersion ratio close to the normal line. Therefore, _{the content of the TiO 2} component is preferably 15.0% or less, more preferably 10.0% or less, still more preferably less than 5.0%, still more preferably 2.0% or less. In particular, from the viewpoint of reducing the anomalous dispersibility of the glass, it is desirable that the glass is not substantially contained.
As the TiO _{2 component, TiO 2} or the like can be used as a raw material.

The MgO component is an optional component that can lower the melting temperature of the glass when it contains more than 0%.
On the other hand, by setting the content of the MgO component to 10.0% or less, devitrification can be reduced while suppressing a decrease in the refractive index. Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the MgO component, MgO, MgCO ₃ , MgF _2, or the like can be used as a raw material.

When the CaO component is contained in excess of 0%, it is an optional component that can reduce the Abbe number, reduce devitrification, and enhance the meltability of the glass raw material while reducing the material cost of the glass. Therefore, the content of the CaO component may be preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 2.0%.
On the other hand, by setting the content of the CaO component to 10.0% or less, it is possible to suppress a decrease in the refractive index, an increase in the Abbe number, an increase in the partial dispersion ratio, and a reduction in devitrification. Therefore, the content of the CaO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the CaO component, CaCO ₃ , CaF _2, or the like can be used as a raw material.

The SrO component is an optional component that can increase the refractive index and the devitrification resistance when it is contained in excess of 0%.
In particular, by reducing the content of the SrO component to 10.0% or less, deterioration of chemical durability can be suppressed. Therefore, the content of the SrO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably 3.0% or less, still more preferably less than 3.0%, still more preferably 1.0. It shall be less than%.
As the SrO component, Sr (NO ₃ ) ₂ , SrF _2, or the like can be used as a raw material.

When the BaO component is contained in excess of 0%, the refractive index can be increased, the partial dispersion ratio can be lowered, the devitrification resistance can be improved, the meltability of the glass raw material can be improved, and other alkaline earth components can be obtained. It is an optional component that can reduce the material cost of glass as compared with the above.
In particular, by setting the content of the BaO component to 10.0% or less, it is possible to suppress a decrease in the refractive index, an increase in the Abbe number, an increase in the partial dispersion ratio, and a reduction in devitrification. Therefore, the content of the BaO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) _2, or the like can be used as a raw material.

La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component can be arbitrarily increased in refractive index and reduced partial dispersion ratio by containing at least any one of them in excess of 0%. It is an ingredient.
In particular, _{by reducing the content of each of the La 2} O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component to 10.0% or less, the increase in the Abbe number can be suppressed and lost. The transparency can be reduced and the material cost can be reduced. Therefore, _{the content of each of the La 2} O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably 5.0%, and further preferably. Is up to 3.0%, more preferably less than 1.0%.
La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are used as raw materials for La ₂ O ₃ , La (NO ₃ ) ₃ , XH ₂ O (X is an arbitrary integer), Y ₂ O ₃ , YF ₃ , Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3, and the} like can be used.

The Ta ₂ O ₅ component is an optional component capable of increasing the refractive index, lowering the Abbe number and the partial dispersion ratio, and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, _{by reducing the content of the Ta 2} O ₅ component to 10.0% or less, the amount of the Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is easily melted at a lower temperature. The production cost of glass can be reduced. Further, this can reduce the devitrification of the glass due to the excessive content _{of the Ta 2} O _{5 component.} Therefore, _{the content of the Ta 2} O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%. In particular, from the viewpoint of reducing the material cost of glass, it is not necessary to contain the _{Ta 2} O _{5 component.}
As the Ta ₂ O _{5 component, Ta 2} O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component capable of increasing the refractive index, lowering the Abbe number, increasing the devitrification resistance, and enhancing the meltability of the glass raw material when the content exceeds 0%.
On the other hand, by _{setting the content of the WO 3} component to 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio of the glass, and it is possible to reduce the coloring of the glass and increase the internal transmittance. Therefore, _{the content of the WO 3} component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the WO _{3 component, WO 3} or the like can be used as a raw material.

The P ₂ O ₅ component is an optional component that can enhance the stability of the glass when it is contained in excess of 0%.
On the other _hand, when the content of P 2 _{O 5} component to 10.0% or _less, can be reduced devitrification due to excessive content of P 2 _{O 5} component. Therefore, _{the content of the P 2} O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO _{4, and the} like can be used as raw materials.

The GeO ₂ component is an optional component capable of increasing the refractive index and reducing devitrification when the content exceeds 0%.
On the other hand, _{by reducing the content of the GeO 2} component to 10.0% or less, the amount of the expensive GeO ₂ component used can be reduced, so that the material cost of the glass can be reduced. Therefore, _{the content of the GeO 2} component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the GeO _{2 component, GeO 2} or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can enhance chemical durability and devitrification resistance when at least one of them is contained in an amount of more than 0%.
On the other hand, _{by reducing the content of each of the Al 2} O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, devitrification due to the excessive content _{of the Al 2} O ₃ component and the Ga ₂ O _{3 component is reduced.} can. Therefore, _{the respective contents of the Al 2} O ₃ component and the Ga ₂ O ₃ component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1. It shall be less than 0.0%.
As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) _{3 and the} like can be used as raw materials.

The Bi ₂ O ₃ component is an optional component capable of increasing the refractive index, lowering the Abbe number, and lowering the glass transition point when the content exceeds 0%.
On the other hand, by _{setting the content of the Bi 2} O ₃ component to 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio, and it is possible to reduce the coloring of the glass and increase the internal transmittance. Therefore, _{the content of the Bi 2} O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the Bi ₂ O _{3 component, Bi 2} O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component capable of increasing the refractive index, lowering the partial dispersion ratio, and lowering the glass transition point when the content exceeds 0%.
On the other hand, _{by reducing the content of the TeO 2} component to 5.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. Further, by reducing the use of the expensive TeO ₂ component, a glass having a lower material cost can be obtained. Therefore, _{the content of the TeO 2} component is preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 1.0%.
As the TeO _{2 component, TeO 2} or the like can be used as a raw material.

The SnO ₂ component is an optional component that can clarify (defoam) the molten glass and increase the visible light transmittance of the glass when it contains more than 0%.
On the other hand, by _{setting the content of the SnO 2} component to 1.0% or less, it is possible to prevent the glass from being colored or devitrified by the reduction of the molten glass. Further, since _{the alloying of the SnO 2} component and the melting equipment (particularly noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, _{the content of the SnO 2} component is preferably 1.0% or less, more preferably less than 0.5%, and further preferably less than 0.1%.
As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF _4, or the like can be used as a raw material.

The Sb ₂ O ₃ component is a component that promotes defoaming of the glass and clarifies the glass when it is contained in excess of 0%, and is an optional component in the optical glass of the present invention. By _{setting the content of the Sb 2} O ₃ component to 1.0% or less of the total mass of the glass, it is possible to prevent excessive foaming during glass melting, and the Sb ₂ O ₃ component is a melting facility (particularly Pt). It can be made difficult to alloy with precious metals such as. _{Therefore, the content of the Sb 2} O ₃ component with respect to the total mass of the glass in the oxide conversion composition is preferably 1.0%, more preferably 0.8%, still more preferably 0.6%. Here, particularly from the viewpoint of facilitating the acquisition of optical glass having low solarization, _{the content of the total glass mass Sb 2} O ₃ component of the oxide conversion composition is preferably 0.5%, more preferably 0.3%, and further. The upper limit is preferably 0.1%.

The component that clarifies and defoams the _{glass is not limited to the above Sb 2} O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the field of glass production can be used. ..

The ratio of the sum of the contents of the _{Li 2} O component and the K ₂ O component to the sum of the contents of the ZrO ₂ component and the Li ₂ O component is preferably more than 0 and less than 2.5.
In particular, by setting this mass ratio to more than 0, devitrification and transmittance can be improved. Therefore, _{the lower limit of (Li 2} O + K ₂ O) / (ZrO ₂ + Li ₂ O) can be preferably more than 0, more preferably more than 0.1, and even more preferably more than 0.3.
On the other hand, by setting this mass ratio to less than 2.5, the anomalous dispersibility of the glass can be reduced while maintaining the refractive index of the glass. Therefore, _{the upper limit of (Li 2} O + K ₂ O) / (ZrO ₂ + Li ₂ O) is preferably less than 2.5, more preferably less than 2.0, still more preferably less than 1.5, still more preferably 1. It may be less than 0, more preferably less than 0.5.

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 15.0% or less. As a result, the devitrification of the glass can be reduced, the increase in the Abbe number can be suppressed, and the material cost of the glass can be reduced. Therefore, _{the mass sum of the Ln 2} O ₃ components is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%.

The sum (mass sum) of the contents of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 30.0% or less. As a result, it is difficult to reduce the refractive index of the glass, and devitrification during glass formation can be reduced. Therefore, _{the total content of the Rn 2} O component is preferably 30.0%, more preferably 25.0%, still more preferably 20.0%, still more preferably 17.0%.
On the other hand, _{the mass sum of the Rn 2} O components is preferably more than 0%, more preferably more than 5.0%, still more preferably 10. It may be more than 0%, more preferably more than 13.0%.

The sum (mass sum) of the contents of the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 20.0% or less. Thereby, the devitrification of the glass due to the excessive inclusion of these components can be reduced. Therefore, the mass sum of the RO components is preferably 20.0% or less, more preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%.
On the other hand, the mass sum of the RO components is preferably more than 0%, more preferably 1.0% or more, still more preferably 2.0% or more, from the viewpoint of increasing the meltability of the glass raw material and reducing devitrification. May be.

<Ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferable to be contained will be described.

Other components can be added as needed within a range that does not impair the characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb and Lu, is used alone. Alternatively, even if it is compounded and contained in a small amount, the glass is colored and has a property of causing absorption at a specific wavelength in the visible region. ..

Further, since lead compounds such as PbO and _{arsenic compounds such as As 2} O ₃ are components having a high environmental load, it is desirable that they are not substantially contained, that is, they are not contained at all except for unavoidable contamination.

Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical substance in recent years, and is used not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Up to this point, environmental measures are required. Therefore, when the environmental impact is emphasized, it is preferable that these are not substantially contained.

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible to be roughly melted, and then a gold crucible and a platinum crucible. , Platinum alloy crucible or iridium crucible, melt in a temperature range of 1000 to 1400 ° C for 3 to 5 hours, homogenize with stirring to break bubbles, etc., then lower to a temperature of 900 to 1100 ° C and then finish stirring. It is produced by removing the crucible, casting it in a mold, and slowly cooling it.

<Physical characteristics>
The optical glass of the present invention has a high refractive index and an Abbe number in a predetermined range.
_{The refractive index (nd} ) of the optical glass of the present invention is preferably 1.60, more preferably 1.63, and even more preferably 1.65 as the lower limit. The upper limit of the refractive index is preferably 1.75, more preferably 1.73, and even more preferably 1.70.
_{The Abbe number (ν d} ) of the optical glass of the present invention is preferably 30, more preferably 31, and even more preferably 33 as the lower limit. On the other hand, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 47, more preferably 45, more preferably 43, and even more preferably 40.
The optical glass of the present invention having such a refractive index and an Abbe number is useful in optical design, and the optical system can be miniaturized while achieving particularly high imaging characteristics, so that the optical design is free. You can increase the degree.

The optical glass of the present invention has a low partial dispersion ratio (θg, F).
More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is different from the Abbe number (ν _d ) of the partial dispersion ratio (θg, F) of the optical glass of the present invention. , (-0.00256 x ν _d +0.637) ≤ (θg, F) ≤ (-0.00256 x ν _d +0.684).
Therefore, in the optical glass of the present invention, it is preferable that the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) satisfy the relationship of θg, F ≧ (−0.00256 × ν _{d +0.637).} [theta] g, more preferably satisfies the relationship _{F ≧ (-0.00256 × ν d +0.647} ), θg, it is more preferable to satisfy the relation of _{F ≧ (-0.00256 × ν d +0.657} ).
On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) preferably satisfy the relationship of θg, F ≦ (−0.00256 × νd + 0.684), and θg. , F ≦ (−0.00256 × νd + 0.681), and more preferably θg, F ≦ (−0.00256 × νd + 0.677).
As a result, an optical glass having a low partial dispersion ratio (θg, F) can be obtained, and the optical element formed from the optical glass can be used to reduce the chromatic aberration of the optical system.

Especially in the region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the horizontal axis is the Abbe number (ν _d ) and the vertical axis is the vertical axis. The relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of general glass when the partial dispersion ratio (θg, F) is taken is represented by a curve with a larger inclination than the normal line. .. In the above-mentioned relational expression of partial dispersion ratio (θg, F) and Abbe number (ν _d ), by defining these relations by using a straight line having a larger inclination than the normal line, the partial dispersion is larger than that of general glass. This means that glass with a small ratio (θg, F) can be obtained.

The optical glass of the present invention is preferably less colored.
_{In particular, the optical glass of the present invention has a wavelength (λ 80} ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm, preferably 420 nm or less, more preferably 400 nm or less, still more preferably. It is 380 nm or less.
_{Further, the optical glass of the present invention has a wavelength (λ 5} ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm, preferably 365 nm or less, more preferably 345 nm or less, and further preferably 330 nm or less.
As a result, the absorption edge of the glass is located near the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be preferably used as a material for an optical element such as a lens.

Further, the optical glass of the present invention needs to have high devitrification resistance. As a result, a decrease in transmittance due to crystallization of the glass during glass production is suppressed, so that this optical glass can be preferably used for an optical element such as a lens that transmits visible light. In particular, the optical glass of the present invention preferably has a low liquidus temperature of 1200 ° C. or lower. More specifically, the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C., more preferably 1150 ° C., more preferably 1100 ° C., and more preferably 1050 ° C. as the upper limit. As a result, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is reduced, so that the devitrification resistance when the glass is formed from the molten state can be improved, and the glass is used. It is possible to reduce the influence on the optical characteristics of the optical element. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 500 ° C. or higher, specifically 550 ° C. or higher, and more specifically 600. Often above ° C. The term "liquid phase temperature" as used herein refers to a glass sample crushed into granules having a diameter of about 2 mm placed on a platinum plate and held for 30 minutes in a furnace having a temperature gradient of 800 ° C. to 1220 ° C. It is the lowest temperature at which no crystals are observed in the glass and devitrification does not occur, which is measured by observing the presence or absence of crystals in the glass with a microscope at a magnification of 80 times after taking out the sample and cooling the glass.

[Preforms and optics]
From the produced optical glass, a glass molded body can be produced by using a mold press molding means such as reheat press molding or precision press molding. That is, a preform for mold press molding is produced from optical glass, and after reheat press molding is performed on this preform, polishing is performed to produce a glass molded body, or for example, polishing is performed to produce the preform. A glass molded body can be produced by performing precision press molding on the preform. The means for producing the glass molded body is not limited to these means.

The glass molded product thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, an object to be photographed can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

The composition of Example (No.1~No.31) and comparative examples of the present invention, and a refractive index _(n d), Abbe number ([nu _d), the partial dispersion ratio ([theta] g, F), the spectral transmittance 5 _{The results of the wavelengths (λ 5} , λ ₈₀ ) showing% and 80%, and the liquidus temperature are shown in Tables 1 to 5. The following examples are for purposes of illustration only, and are not limited to these examples.

The glasses of Examples and Comparative Examples are both used as ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to each component as raw materials. High-purity raw materials are selected, weighed so as to have the composition ratio of each example and comparative example shown in the table, and mixed uniformly. It may be put into a glass (a glass may be used), melted in an electric furnace in a temperature range of 1100 to 1400 ° C. for 0.5 to 5 hours depending on the difficulty of melting the glass composition, and then transferred to a platinum glass to be stirred and homogenized. After the bubbles were cut off, the temperature was lowered to 1000 to 1400 ° C., the mixture was stirred and homogenized, cast into a mold, and slowly cooled to prepare glass.

The refractive index of the glass of the Examples and Comparative Examples _(n d), Abbe number ([nu _d) and partial dispersion ratio ([theta] g, F) were measured according to Japan Optical Glass Industry Society Standard JOGIS01-2003.
The glass used for this measurement was treated in a slow cooling furnace at a slow cooling rate of −25 ° C./hr.

The transmittance of the glass of Examples and Comparative Examples was measured according to the Japan Optical Glass Industry Association standard JOBIS02. In the present invention, the presence or absence and degree of coloring of the glass were determined by measuring the transmittance of the glass. Specifically, a face-to-face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm according to JISZ8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₈₀ (transmittance). The wavelength at 80%) was determined.

For the liquidus temperature of Examples and Comparative Examples, crushed glass samples were placed on a platinum plate at 10 mm intervals, held in a furnace having a temperature gradient of 800 ° C. to 1200 ° C. for 30 minutes, then taken out and cooled. Later, the presence or absence of crystals in the glass sample was measured by observing with a microscope at a magnification of 80 times. At this time, as a sample, optical glass was pulverized into granules having a diameter of about 2 mm.

As shown in these tables, the optical glass of the embodiment of the present invention has a partial dispersion ratio (θg, F) and an Abbe number (ν _d ) of (-0.00256 × ν _d +0.637) ≦ (θg, F). ) ≤ (-0.00256 x ν _d +0.684), more specifically (-0.00256 x νd +0.657) ≤ (θg, F) ≤ (-0.00256 x ν _d) The relationship of +0.679) was satisfied. Here, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the embodiment of the present application is shown in FIG.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.60 or more, with more particularly 1.65 or more, the refractive index _{(n d)} is 1.75 or less, more The details were 1.73 or less, which was within the desired range.
Further, all of the optical glasses of the examples of the present invention have an Abbe number (ν _d ) of 30 or more, and the Abbe number (ν _d ) is 47 or less, more specifically 43 or less, which is a desired range. It was inside.

In addition, the optical glass of the examples of the present invention had a λ ₈₀ (wavelength at a transmittance of 80%) of 420 nm or less, more specifically 400 nm or less, and more specifically 390 nm or less.
Further, in the optical glass of the example of the present invention, λ ₅ (wavelength at a transmittance of 5%) was 365 nm or less, more specifically 345 nm or less, and more specifically 335 nm or less.
Therefore, it has been clarified that the optical glass of the embodiment of the present invention has a high transmittance for visible light and is difficult to be colored.

In addition, the optical glass of the examples of the present invention had a liquidus temperature of 1200 ° C. or lower, more specifically 1110 ° C. or lower, and more specifically 1050 ° C. or lower. Therefore, it is presumed that the optical glass of the embodiment of the present invention has high reheat press moldability because devitrification due to reheating and milky white are less likely to get angry.

Further, a glass block was formed using the optical glass of the embodiment of the present invention, and the glass block was ground and polished to be processed into the shape of a lens and a prism. As a result, it was possible to stably process various lens and prism shapes.

Although the present invention has been described in detail above for the purpose of exemplification, the present embodiment is merely for the purpose of exemplification, and many modifications can be made by those skilled in the art without departing from the idea and scope of the present invention. Will be understood.

Claims (7)

By mass% of oxide equivalent composition,
SiO ₂ component 32.66 to 60.0%,
Nb ₂ O ₅ component is 20.0 to 45.0% and ZrO ₂ component is 1.0 to 20.0%,
ZnO component is over 0% to 25.0% ,
Li ₂ O component 2.00 to 20.0%,
B ₂ O ₃ component more than 0.1% to 15.0% or less,
Contains less than 1.0% of _{Ta 2} O _{5 component,}
Mass ratio (Li ₂ O + K ₂ O) / (ZrO ₂ + Li ₂ O) is more than 0.1 and less than 2.5,
The mass sum of the Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is more than 10.0% and 20.0% or less.
The mass sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 0 to 3.86% .
The liquidus temperature is 1200 ° C or less,
_{Refractive index (nd} ) of 1.60 or more and 1.75 or less,
_{It has an Abbe number (ν d} ) of 30 or more and 47 or less,
The partial dispersion ratio (θg, F) is _{between the Abbe number (ν d} ) and (-0.00256 x ν _d +0.637) ≤ (θg, F) ≤ (-0.00256 x ν _d +0.684). ) Satisfying the relationship. By mass% of oxide equivalent composition,
Na ₂ O component 0 to 20.0%,
K ₂ O component 0 to 10.0%,
The optical glass according to claim 1. By mass% of oxide equivalent composition,
TiO ₂ component 0 to 15.0%,
La ₂ O ₃ component 0 to 10.0%,
Gd ₂ O ₃ component 0 to 10.0%,
Y ₂ O ₃ component 0 to 10.0%,
Yb ₂ O ₃ component 0 to 10.0%,
WO ₃ component 0-10.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0-10.0%,
Al ₂ O ₃ component 0 to 10.0%,
Ga ₂ O ₃ component 0 to 10.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ component 0-5.0%,
SnO ₂ component 0-1.0%,
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of claims 1 or 2. By mass% based on oxide,
The mass sum of the Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 0 to 15.0%.
The optical glass according to any one of claims 1 to 3. _{The wavelength (λ 80} ) showing a spectral transmittance of 80% is 420 nm or less, and the spectral transmittance is 5%.
The optical glass according to any one of claims 1 to 4, wherein the wavelength (λ _{5) indicating the above is 365 nm or less.} A preform for polishing and / or precision press molding made of the optical glass according to any one of claims 1 to 5. An optical element made of the optical glass according to any one of claims 1 to 5.

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