JP7194861B6 - Optical glass, glass materials for press molding, optical element blanks and optical elements - Google Patents

Description

The present invention relates to an optical glass, a glass material for press molding, an optical element blank, and an optical element.

Optical glass having a high refractive index and low dispersion (high refractive index low dispersion glass) is useful as a material for optical elements. Such a high refractive index low dispersion glass is disclosed in Patent Document 1, for example.

Japanese Patent Application Publication No. 2009-203155

The high refractive index, low dispersion glass disclosed in Patent Document 1 corrects chromatic aberration and improves the optical system by combining a lens made of this glass with a lens made of ultra-low dispersion glass to form a cemented lens. It can be made more compact.
However, the optical glass described in Patent Document 1 contains a large amount of a relatively expensive component (for example, Ta ₂ O ₅ ) among various glass components. However, in order to reduce the cost of optical elements made of high refractive index, low dispersion glass, it is desirable to reduce the proportion of expensive glass components in the glass composition of the optical glass.

One aspect of the present invention provides an optical glass that has a low proportion of expensive glass components in the glass composition, a high refractive index, and low dispersion.

One aspect of the present invention is
In the glass composition expressed as cation%,
Ta ⁵⁺ content is in the range of 0 to 5 cation%,
The cation ratio of Ti ⁴⁺ content to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ /(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 0. ranges from .60 to 1.00,
Cation ratio of the total content of Si ⁴⁺ and B ³⁺ to the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ ((Si ⁴⁺ + B ³⁺ )/(La ³⁺ + Gd ³⁺ + Y ^{3 +} )) is in the range of 0.30 to 2.40,
The cation ratio of the total content of Si ⁴⁺ and B ³⁺ to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ ((Si ⁴⁺ +B ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is in the range of 0.30 to 34.00,
Cation ratio of the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ ((La ³⁺ + Gd ³⁺ + Y ³⁺ ) /(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is in the range of 0.30 to 33.00,
The cation ratio of the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ to the total content of La ³⁺ and Y ³⁺ ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(La ³⁺ +Y ³⁺ )) is in the range of 0.00 to 1.50,
The cation ratio of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba 2+ and Zn ²⁺ to the total content ^of Si ⁴⁺ and B ³⁺ ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )) is in the range of 0.00 to 1.00,
Cation ratio of the total content of Gd ³⁺ , Nb 5+ and ^{W 6+ to} the total content of Si ⁴⁺ , B ³⁺ , Zn ²⁺ , La ³⁺ , Y ³⁺ , Zr ⁴⁺ and Ti ⁴⁺ ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is in the range of 0.000 to 0.100,
an optical glass having a refractive index nd in the range of 1.9000 to 2.1500 and an Abbe number νd in the range of 20.0 to 35.0;
Regarding.

Among the raw material compounds for optical glass, Ta compounds, Gd compounds, Nb compounds, and W compounds are relatively expensive. On the other hand, the Ta ⁵⁺ content of the optical glass is suppressed within the above range. Furthermore, the proportions of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ in the glass composition are also suppressed. Specifically, regarding Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ , the cation ratio ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is within the above range. That is, in the glass composition of the above-mentioned optical glass, the proportion of expensive glass components Ta ⁵⁺ , Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ is low. In such a glass composition, by adjusting the glass composition so as to satisfy the various cation ratios described above, an optical glass having a high refractive index nd within the above range and an Abbe number νd within the above range (i.e., low dispersion) can be obtained. Can be done.

According to one aspect of the present invention, it is possible to provide an optical glass that has optical properties (nd and vd) useful as a material for optical elements and can contribute to cost reduction of optical elements. Also, according to one embodiment, an optical glass can be provided that further has one or more physical properties of high glass stability, low specific gravity, and low coloration (high transmittance). Furthermore, according to one aspect of the present invention, it is possible to provide a press-molding glass material, an optical element blank, and an optical element made of the above optical glass.

[Optical glass]
In the present invention and this specification, the content and total content of cationic components shall be expressed as cation% unless otherwise specified, and the content and total content of anionic components shall be expressed as anion% unless otherwise specified.
Here, "cation %" is a value calculated by "(number of cations of interest/total number of cations of glass components) x 100", and is the molar percentage of the amount of cations of interest to the total amount of cation components. means.
In addition, "anion %" is a value calculated by "(number of anions of interest/total number of anions of glass components) x 100", and means the molar percentage of the amount of anions of interest to the total amount of anion components. do.
The molar ratio of the contents of the cationic components is equal to the content ratio of the cationic components of interest expressed in cation%, and the molar ratio of the contents of the anionic components of interest is equal to the content of the anionic components of interest expressed as anion%. equal to ratio.
The molar ratio between the content of cationic components and the content of anionic components is the ratio of the contents (expressed in mol%) of the components of interest when the total amount of all cationic components and all anionic components is 100 mol%. be.
The content of each component can be determined by known methods such as inductively coupled plasma optical emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and ion chromatography.
In addition, in the present invention and this specification, the content of a constituent component of 0%, not included, or not introduced means that this constituent component is not substantially included, and the content of this constituent component is at an impurity level. It means that it is less than that. The term "below the impurity level" means, for example, less than 0.01%.

Hereinafter, the above optical glass (sometimes simply referred to as "glass") will be explained in more detail.

<Glass composition>
The optical glass has a Ta ⁵⁺ content in the range of 0 to 5 cation%, and has a low Ta ⁵⁺ content, which is an expensive glass component. From the viewpoint of further cost reduction of optical elements, the Ta ⁵⁺ content is preferably 4% or less, more preferably 3% or less, even more preferably 2% or less, It is more preferable that it is 1% or less, and even more preferable that it does not contain Ta ⁵⁺ .

In the above optical glass, ^the sum of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ with respect to the total content of Si 4+ , B ³⁺ , Zn ²⁺ , La ³⁺ , Y ³⁺ , Zr ⁴⁺ and Ti ⁴⁺ The cation ratio of the content ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is 0.000 to 0. The range is 100. That is, the optical glass has a low proportion of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ in the glass composition. From the viewpoint of further cost reduction of optical elements, the above cation ratio ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is preferably 0.090 or less, more preferably 0.080 or less, even more preferably 0.070 or less, even more preferably 0.060 or less, and 0. It is even more preferably not more than .050, even more preferably not more than 0.040, even more preferably not more than 0.030, not more than 0.025, not more than 0.020, not more than 0.015 , 0.010 or less, 0.007 or less, 0.005 or less, 0.004 or less, 0.003 or less, 0.002 or less, or even more preferably 0.001 or less, and 0.000. is even more preferred. That is, it is even more preferred not to contain Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ .

In the above optical glass, the total content of Gd ³⁺ and W ⁶⁺ (Gd ³⁺ + W ⁶⁺ ) is preferably 8% or less from the viewpoint of reducing the cost of optical elements and lowering the specific gravity of the glass. It is preferably at most 6%, even more preferably at most 5%, even more preferably at most 4%, even more preferably at most 3%, and even more preferably at most 2%. It is even more preferred, and even more preferred that it is 1% or less. The total content (Gd ³⁺ +W ⁶⁺ ) can be 0% or more, and is particularly preferably 0%.

Furthermore, in the above optical glass, the total content of Gd ³⁺ and W ⁶⁺ with respect to the total content of Si ⁴⁺ , B ³⁺ , Zn ²⁺ , La ³⁺ , Y ³⁺ , Zr ⁴⁺ and Ti ⁴⁺ The cation ratio ((Gd ³⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is in the range of 0.000 to 0.080. It is preferable that there be. From the viewpoint of further reducing the cost of optical elements and lowering the specific gravity of glass, the above cation ratio ((Gd ³⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ^{3 +} +Zr ⁴⁺ +Ti ⁴⁺ )) is preferably 0.070 or less, more preferably 0.060 or less, even more preferably 0.050 or less, and 0.045 or less. is more preferably 0.040 or less, even more preferably 0.035 or less, even more preferably 0.030 or less, still more preferably 0.025 or less. More preferably, it is not more than 0.020, even more preferably not more than 0.015, even more preferably not more than 0.010, even more preferably not more than 0.007. is particularly preferably 0.005 or less, particularly more preferably 0.004 or less, even more preferably 0.003 or less, and even more preferably 0.002 or less. It is especially even more preferable, and it is even more preferable that it is 0.001 or less. The above cation ratio ((Gd ³⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is particularly preferably 0.000. That is, it is particularly preferable that the optical glass does not contain Gd ³⁺ and W ⁶⁺ .

Si ⁴⁺ and B ³⁺ are network forming components of the glass. From the viewpoint of improving glass stability, the total content of Si ⁴⁺ and B ³⁺ (Si ⁴⁺ + B ³⁺ ) is preferably 25% or more, more preferably 27% or more, It is more preferably 28% or more, even more preferably 29% or more, even more preferably 30% or more, and even more preferably 31% or more. On the other hand, from the viewpoint of suppressing a decrease in the refractive index, the total content (Si ⁴⁺ +B ³⁺ ) is preferably 55% or less, more preferably 45% or less, and 40% or less. It is more preferably at most 37%, even more preferably at most 35%, even more preferably at most 34%.

From the viewpoint of further increasing the glass stability of the optical glass, which is a high refractive index and low dispersion glass, and from the viewpoint of further increasing the refractive index, the cation of the B ³⁺ content relative to the total content of Si ⁴⁺ and B ³⁺ The ratio (B ³⁺ /(Si ⁴⁺ +B ³⁺ )) is preferably 0.20 or more, more preferably 0.30 or more, even more preferably 0.40 or more, and 0. It is more preferably .50 or more, even more preferably 0.55 or more, even more preferably 0.60 or more, even more preferably 0.61 or more, 0.62 It is even more preferable that it is 0.63 or more, even more preferably that it is 0.64 or more, and even more preferably that it is 0.65 or more. Further, from the same viewpoint, the cation ratio (B ³⁺ /(Si ⁴⁺ +B ³⁺ )) is preferably 0.95 or less, more preferably 0.90 or less, and 0.95 or less. It is more preferably 85 or less, even more preferably 0.83 or less, even more preferably 0.80 or less, even more preferably 0.79 or less, and even more preferably 0.78 or less. Even more preferably, it is 0.77 or less, even more preferably 0.76 or less, and even more preferably 0.75 or less. It is preferable that the cation ratio (B ³⁺ /(Si ⁴⁺ +B ³⁺ )) is equal to or higher than the above-exemplified lower limit from the viewpoint of improving the meltability of the glass. It is preferable that the cation ratio (B ³⁺ /(Si ⁴⁺ +B ³⁺ )) be less than or equal to the upper limit exemplified above in order to increase the viscosity of the glass during melting. Furthermore, the fact that the cation ratio (B ³⁺ /(Si ⁴⁺ +B ³⁺ )) is below the upper limit exemplified above is from the viewpoint of reducing fluctuations in the glass composition due to volatilization during melting and fluctuations in optical properties due to this. It is also preferable from the viewpoint of improving one or more of the chemical durability, weather resistance, and machinability of the glass, and from the viewpoint of reducing coloring.

The total content of Si ⁴⁺ and B ³⁺ , which are network forming components of the glass, is as described above. Preferred ranges for each of the Si ⁴⁺ content and B ³⁺ content from the viewpoint of improving glass stability, meltability, moldability, chemical durability, weather resistance, machinability, etc. and from the viewpoint of reducing coloration. is as follows.
The Si ⁴⁺ content is preferably 2% or more, more preferably 3% or more, even more preferably 4% or more, even more preferably 5% or more, and even more preferably 6% or more. It is even more preferable that it be present, and even more preferable that it be 7% or more. Further, the Si ⁴⁺ content is preferably 20% or less, more preferably 18% or less, even more preferably 16% or less, even more preferably 14% or less, and even more preferably 12% or less. The following is even more preferable.
The B ³⁺ content is preferably 10% or more, more preferably 15% or more, even more preferably 16% or more, even more preferably 17% or more, and even more preferably 18% or more. It is even more preferable that it be present, and even more preferable that it be 19% or more. Further, the B ³⁺ content is preferably 40% or less, more preferably 40% or less, even more preferably 35% or less, even more preferably 30% or less, and 26% or less. It is even more preferably at most 25%, even more preferably at most 24%, even more preferably at most 23%.

La ³⁺ , Gd ³⁺ and Y ³ are components that have the function of increasing the refractive index while suppressing a decrease in the Abbe number. These components also have the function of improving the chemical durability and/or weather resistance of the glass and increasing the glass transition temperature.
The total content of La ³⁺ , Gd ³⁺ and Y ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ ) is preferably 20% or more, and 22% or more from the viewpoint of suppressing a decrease in the refractive index. It is more preferably at least 24%, even more preferably at least 26%, even more preferably at least 28%, even more preferably at least 30%, It is even more preferable that it is 32% or more, even more preferably that it is 33% or more, even more preferably that it is 34% or more, even more preferably that it is 35% or more, and even more preferably that it is 36% or more. Even more preferably. Furthermore, from the viewpoint of suppressing a decrease in the chemical durability and/or weather resistance of the glass, and from the perspective of suppressing a decrease in the glass transition temperature, the above-mentioned total content (La ³⁺ +Gd ³⁺ +Y ³⁺ ) is It is preferable that it is equal to or higher than the lower limit illustrated. When the glass transition temperature decreases, the glass becomes more likely to break when mechanically processed (cutting, cutting, grinding, polishing, etc.) (decreased machinability). Therefore, suppressing the decrease in glass transition temperature leads to improving machinability. It is also preferable from the above viewpoint that the total content (La ³⁺ +Gd ³⁺ +Y ³⁺ ) is equal to or higher than the lower limit exemplified above.
On the other hand, the above total content (La ³⁺ +Gd ³⁺ +Y ³⁺ ) is preferably 60% or less, more preferably 55% or less, and 50% or less from the viewpoint of increasing glass stability. It is more preferably 47% or less, even more preferably 45% or less, even more preferably 44% or less, and even more preferably 43% or less. , even more preferably 42% or less, even more preferably 41% or less, even more preferably 40% or less, and even more preferably 39% or less.

From the viewpoint of increasing glass stability and lowering specific gravity, in the above optical glass, Si ⁴⁺ and B ³⁺ , which are network forming components of the glass, are added to the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ . The cation ratio of the total content ((Si ⁴⁺ +B ³⁺ )/(La ³⁺ +Gd ³⁺ +Y ³⁺ )) is 0.30 or more, preferably 0.50 or more, and 0. It is more preferably .60 or more, even more preferably 0.65 or more, even more preferably 0.70 or more, even more preferably 0.75 or more, and 0.77 or more. It is even more preferable that it is 0.79 or more, even more preferably that it is 0.80 or more.
The above cation ratio ((Si ⁴⁺ +B ³⁺ )/(La ³⁺ +Gd ³⁺ +Y ³⁺ )) is 2.40 or less, and preferably 2.00 or less, from the viewpoint of increasing the refractive index. preferably, 1.50 or less, more preferably 1.30 or less, even more preferably 1.10 or less, even more preferably 1.05 or less, 1.00 It is even more preferable that it is less than or equal to 0.95, even more preferably that it is less than or equal to 0.94, even more preferably that it is less than or equal to 0.93, and even more preferably that it is less than or equal to 0.92. It is even more preferable that it is less than or equal to 0.91, even more preferably that it is less than or equal to 0.91, and particularly preferably that it is less than or equal to 0.90.

The preferable ranges for the content of each component of La ³⁺ , Gd ³⁺ and Y ³⁺ are as follows.
The La ³⁺ content is preferably 20% or more, more preferably 21% or more, even more preferably 22% or more, even more preferably 23% or more, and even more preferably 24% or more. It is even more preferable that it be at least 25%, even more preferably that it is at least 26%, even more preferably that it is at least 27%. Further, the La ³⁺ content is preferably 60% or less, more preferably 57% or less, even more preferably 55% or less, even more preferably 53% or less, and 50% or less. It is even more preferable that it is less than or equal to 47%, even more preferably that it is less than or equal to 45%, even more preferably that it is less than or equal to 43%, and even more preferably that it is less than or equal to 40%. Even more preferably, it is still more preferably 37% or less, even more preferably 35% or less, particularly preferably 34% or less, and even more preferably 33% or less. , 32% or less is especially more preferred, 31% or less is even more preferred, 30% or less is even more preferred, and 29% or less is even more preferred.
The Gd ³⁺ content is preferably 8% or less, more preferably 6% or less, even more preferably 4% or less, even more preferably 3% or less, and 2% or less. It is even more preferable that it be present, and even more preferable that it be 1% or less. The Gd ³⁺ content can be 0% or more, and from the viewpoint of further cost reduction and lower specific gravity of the optical element, the Gd ³⁺ content is 0%, that is, Gd ³⁺ It is particularly preferable that it not be included.
From the viewpoint of improving meltability and glass stability, the Y ³⁺ content is preferably 0% or more, more preferably 1% or more, even more preferably 2% or more, and 4%. It is more preferably at least 6%, even more preferably at least 7%, even more preferably at least 8%, and even more preferably at least 9%. More preferred. Further, the Y ³⁺ content is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, even more preferably 17% or less, and 15% or less. It is even more preferably less than or equal to 14%, even more preferably less than or equal to 13%, even more preferably less than or equal to 12%, and even more preferably less than or equal to 11%. Even more preferred.

Yb has a large atomic weight among rare earth elements and tends to increase the specific gravity of glass. Moreover, Yb has absorption in the near-infrared region. On the other hand, it is desirable for interchangeable lenses for single-lens reflex cameras and lenses for surveillance cameras to have high light transmittance in the near-infrared region. Therefore, in order to make the glass useful for producing these lenses, it is desirable that the Yb ³⁺ content be small. From the above viewpoint, the Yb ³⁺ content is preferably 10% or less, more preferably 5% or less, even more preferably 3% or less, and even more preferably 1% or less. . Moreover, the Yb ³⁺ content can be 0% or more, and it is particularly preferable that the Yb ³⁺ content is 0%, that is, no Yb ³⁺ is included.

Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ are components that have the function of increasing the refractive index, and when included in appropriate amounts, they also have the function of increasing glass stability. The total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ) should be 0% or more from the viewpoint of improving glass stability. is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, even more preferably 16% or more, and even more preferably 17% or more. is even more preferably at least 18%, even more preferably at least 19%, even more preferably at least 20%, and even more preferably at least 21%. preferable. On the other hand, the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ) is determined from the viewpoint of maintaining glass stability and suppressing the decrease in Abbe number. It is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 29% or less, and even more preferably 28% or less. More preferably, it is less than or equal to 27%, even more preferably less than or equal to 26%, even more preferably less than or equal to 25%, and even more preferably less than or equal to 24%.

From the viewpoint of suppressing high dispersion while maintaining glass stability and reducing coloration, in the above optical glass, La ³⁺ , relative to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ , The cation ratio of the total content of Gd ³⁺ and Y ³⁺ ((La ³⁺ +Gd ³⁺ +Y ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 0.30 or more. , more preferably 0.40 or more, even more preferably 0.50 or more, even more preferably 0.60 or more, even more preferably 0.70 or more, 0.80 or more It is even more preferably that it is 0.90 or more, even more preferably that it is 1.00 or more, even more preferably that it is 1.10 or more, and even more preferably that it is 1.20 or more. Still more preferably, it is 1.30 or more, even more preferably 1.40 or more, and even more preferably 1.50 or more. On the other hand, from the viewpoint of maintaining glass stability while suppressing a decrease in the refractive index and from the viewpoint of lowering the specific gravity, the cation ratio ((La ³⁺ +Gd ³⁺ +Y ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 33.00 or less, preferably 20.00 or less, more preferably 10.00 or less, and even more preferably 5.00 or less. It is preferably 4.00 or less, even more preferably 3.00 or less, even more preferably 2.50 or less, and even more preferably 2.20 or less. , even more preferably 2.00 or less, even more preferably 1.90 or less, even more preferably 1.80 or less, and especially 1.70 or less. preferable.

From the viewpoint of increasing the refractive index, in the optical glass, Si ⁴⁺ and B ³⁺ , which are network forming components of the glass, are smaller than the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ The cation ratio of the total content ((Si ⁴⁺ +B ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 34.00 or less, preferably 30.00 or less, It is more preferably 20.00 or less, even more preferably 10.00 or less, even more preferably 5.00 or less, even more preferably 4.00 or less, and 3.00 or less. It is even more preferably that it is 2.50 or less, even more preferably that it is 2.20 or less, even more preferably that it is 2.00 or less, Even more preferably, it is less than or equal to 1.80, even more preferably less than or equal to 1.70, even more preferably less than or equal to 1.60. On the other hand, from the viewpoint of suppressing high dispersion, maintaining glass stability, and reducing coloring, the above cation ratio ((Si ⁴⁺ +B ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 0.30 or more, preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.60 or more, even more preferably 0.70 or more, It is even more preferably 0.80 or more, even more preferably 0.85 or more, even more preferably 0.90 or more, even more preferably 0.95 or more, 1 .00 or more is even more preferable, 1.05 or more is even more preferable, 1.10 or more is particularly preferable, 1.15 or more is especially more preferable, 1. It is especially even more preferable that it is .20 or more, it is especially even more preferable that it is 1.25 or more, and it is especially even more preferable that it is 1.30 or more.

From the viewpoint of maintaining glass stability and reducing coloring, the cation ratio of Ti ⁴⁺ content to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ / (Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is in the range of 0.60 to 1.00. The cation ratio (Ti ⁴⁺ /(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is preferably 0.70 or more, more preferably 0.75 or more, and 0.80 or more. It is more preferably 0.85 or more, even more preferably 0.90 or more, even more preferably 0.95 or more, and even more preferably 1.00. Even more preferred.

Regarding the content of each component of Ti ⁴⁺ , Nb ⁵⁺ and W ⁶⁺ , preferred ranges are as follows.
The Ti ⁴⁺ content is preferably 0% or more, more preferably 5% or more, even more preferably 10% or more, even more preferably 15% or more, and even more preferably 16% or more. It is even more preferable that it is at least 17%, even more preferably that it is at least 18%, even more preferably that it is at least 19%, even more preferably it is at least 20%. More preferably, it is 21% or more, even more preferably. Further, the Ti ⁴⁺ content is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 29% or less, and 28% or less. It is even more preferable that it is less than or equal to 27%, even more preferably that it is less than or equal to 26%, even more preferably that it is less than or equal to 25%, and even more preferably that it is less than or equal to 24%. Even more preferred.
The Nb ⁵⁺ content is preferably 8% or less, more preferably 6% or less, even more preferably 5% or less, even more preferably 4% or less, and 3% or less. It is even more preferable that it be present, even more preferably that it is 2% or less, and even more preferably that it is 1% or less. The Nb ⁵⁺ content can be 0% or more, and from the viewpoint of further cost reduction of optical elements, the Nb ⁵⁺ content should be 0%, that is, Nb ⁵⁺ is not included. This is particularly preferred.
The W ⁶⁺ content is preferably 8% or less, more preferably 6% or less, even more preferably 5% or less, even more preferably 4% or less, and 3% or less. It is even more preferable that it be present, even more preferably that it is 2% or less, and even more preferably that it is 1% or less. The W ⁶⁺ content can be 0% or more, and from the viewpoint of further reducing the cost of optical elements, lowering the specific gravity of glass, and reducing coloring, the W ⁶⁺ content should be 0%. , that is, it is particularly preferable that W ⁶⁺ is not included.

The total content of Nb ⁵⁺ and W ⁶⁺ (Nb ⁵⁺ + W ⁶⁺ ) is preferably 8% or less, and 6% or less, from the viewpoint of reducing the cost of optical elements and lowering the specific gravity of glass. It is more preferably at most 5%, even more preferably at most 4%, even more preferably at most 3%, even more preferably at most 2%, It is even more preferably 1% or less. The total content (Nb ⁵⁺ +W ⁶⁺ ) can be 0% or more, and is particularly preferably 0%.

The total content of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ (Gd ³⁺ + Nb ⁵⁺ + W ⁶⁺ ) is 8% or less from the viewpoint of reducing the cost of optical elements and lowering the specific gravity of glass. It is preferably 6% or less, even more preferably 5% or less, even more preferably 4% or less, even more preferably 3% or less, and 2% or less. Even more preferably, it is 1% or less, and even more preferably 1% or less. The total content (Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ ) can be 0% or more, and is particularly preferably 0%.

Bi ³⁺ is a component that increases the refractive index and decreases the Abbe number. It is also a component that tends to increase specific gravity and coloration. In order to produce a glass having the above-mentioned optical properties and having little coloration and low specific gravity, the preferable range of the Bi ³⁺ content is as follows.
The Bi ³⁺ content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 5% or less. It is even more preferable that it be present, even more preferably that it is 3% or less, and even more preferably that it is 1% or less. Further, the Bi ³⁺ content can be 0% or more, and may be 0%.

The total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ (Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) is determined from the viewpoint of maintaining glass stability, high refractive index, and low dispersion. From the viewpoint of reduction, the content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 6% or less. is even more preferably at most 5%, even more preferably at most 4%, even more preferably at most 3%, even more preferably at most 2%. , even more preferably 1% or less. Further, the total content (Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) can be 0% or more. In one aspect, the total content (Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) is preferably 0%.

The total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ (Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ ) improves the meltability of glass, From the viewpoint of maintaining stability and suppressing an excessive increase in glass transition temperature, the content is preferably 0% or more, more preferably 0.05% or more, and even more preferably 0.1% or more. preferable. On the other hand, from the viewpoint of maintaining glass stability, increasing the refractive index, and reducing dispersion, the above total content (Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ ) should be 30% or less. It is preferably at most 25%, even more preferably at most 20%, even more preferably at most 15%, even more preferably at most 10%, and even more preferably at most 8%. Even more preferably, it is at most 6%, even more preferably at most 4%, even more preferably at most 4%.

From the viewpoint of maintaining glass stability, increasing the refractive index, and decreasing dispersion, in the above optical glass, Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ² with respect to the total content of La ³⁺ and Y ³⁺ The cation ratio of the total content of ⁺ and Zn ²⁺ ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(La ³⁺ +Y ³⁺ )) is 1.500 or less, and 1 It is preferably at most .000, more preferably at most 0.800, even more preferably at most 0.500, even more preferably at most 0.400, and most preferably at most 0.300. It is even more preferable that it is 0.250 or less, even more preferably that it is 0.200 or less, even more preferably that it is 0.150 or less, and even more preferably that it is 0.100 or less. It is even more preferable that it is 0.080 or less, even more preferably that it is 0.060 or less, it is particularly preferable that it is 0.040 or less, and it is particularly preferable that it is 0.020 or less. It is especially more preferably 0.010 or less, even more preferably 0.007 or less, even more preferably 0.005 or less. Further, the cation ratio ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(La ³⁺ +Y ³⁺ )) is 0.00 or more, which improves the meltability of glass and From the viewpoint of maintaining stability and suppressing excessive increase in glass transition temperature, it is preferably 0.00 or more, more preferably 0.001 or more, even more preferably 0.003 or more, More preferably, it is 0.005 or more.

From the viewpoint of maintaining glass stability and reducing specific gravity, Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ are added to the total content of Si ⁴⁺ and B ³⁺ in the above optical glass. The cation ratio ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )) is 1.000 or less, preferably 0.900 or less, It is more preferably 0.800 or less, even more preferably 0.700 or less, even more preferably 0.600 or less, even more preferably 0.550 or less, and even more preferably 0.500 or less. It is even more preferable that the It is even more preferable that the It is especially more preferable that it be 0.090 or less, and even more preferable that it be 0.090 or less. Further, the cation ratio ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )) is 0.00 or more, which improves the meltability of glass and From the viewpoint of suppressing an excessive rise in the transition temperature, it is preferably 0.001 or more, more preferably 0.003 or more, and even more preferably 0.005 or more.

Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ are all components that have the function of improving the meltability of glass. However, when the content of these components increases, the glass stability tends to decrease. From the above viewpoint, the preferable range of the content of each of these components is as follows.
The Mg ²⁺ content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 6% or less. It is even more preferable that it is present, even more preferably that it is 5% or less, even more preferably that it is 4% or less, even more preferably that it is 3% or less, and even more preferably that it is 2% or less. More preferably, 1% or less is even more preferred. Further, the Mg ²⁺ content can be 0% or more, and may be 0%.
The Ca ²⁺ content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 6% or less. It is even more preferable that it is present, even more preferably that it is 5% or less, even more preferably that it is 4% or less, even more preferably that it is 3% or less, and even more preferably that it is 2% or less. More preferably, 1% or less is even more preferred. Further, the Ca ²⁺ content can be 0% or more, and may be 0%.
The Sr ²⁺ content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 6% or less. It is even more preferable that it is present, even more preferably that it is 5% or less, even more preferably that it is 4% or less, even more preferably that it is 3% or less, and even more preferably that it is 2% or less. More preferably, 1% or less is even more preferred. Further, the Sr ²⁺ content can be 0% or more, and may be 0%.
The Ba ²⁺ content is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 7% or less, and 6% or less. It is even more preferable that it is present, even more preferably that it is 5% or less, even more preferably that it is 4% or less, even more preferably that it is 3% or less, and even more preferably that it is 2% or less. More preferably, 1% or less is even more preferred. Moreover, the Ba ²⁺ content can be 0% or more, and may be 0%.

From the viewpoint of improving the meltability, stability, moldability, machinability, etc. of the glass and realizing the above-mentioned optical properties, the preferred range of the Zn ²⁺ content is as follows.
The Zn ²⁺ content can be 0% or more, preferably 0.03% or more, more preferably 0.05% or more, even more preferably 0.08% or more. , more preferably 0.1% or more. Further, the Zn ²⁺ content is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, and 10% or less. It is even more preferably at most 8%, even more preferably at most 6%, even more preferably at most 4%.

Regarding Zn ²⁺ , from the viewpoint of achieving the above optical properties while improving glass stability, the cation ratio of Zn ²⁺ content to the total content of La ³⁺ and Y ³⁺ (Zn ²⁺ /(La ³⁺ +Y ³ )) is preferably 0.66 or less, more preferably 0.50 or less, even more preferably 0.40 or less, and even more preferably 0.30 or less. , even more preferably 0.25 or less, even more preferably 0.20 or less, even more preferably 0.15 or less, even more preferably 0.13 or less, It is even more preferably 0.12 or less, even more preferably 0.11 or less, even more preferably 0.10 or less, and particularly preferably 0.090 or less. , 0.085 or less is especially more preferable, and 0.080 or less is particularly more preferable. Furthermore, it is preferable that the cation ratio (Zn ²⁺ /(La ³⁺ + Y ³⁺ )) is small from the viewpoint of suppressing a decrease in the glass transition temperature (thereby improving machinability) and improving chemical durability. . The above cation ratio (Zn ²⁺ /(La ³⁺ +Y ³⁺ )) can be 0.00 or more, and from the viewpoint of improving meltability and suppressing excessive increase in glass transition temperature, it is 0.00 or more . It is preferable that it exceeds .00%. The cation ratio (Zn ²⁺ /(La ³⁺ +Y ³⁺ )) is more preferably 0.001 or more, even more preferably 0.003 or more, and even more preferably 0.005 or more. preferable.

The cation ratio of the total content of Zn ^{2+ and} Ba ²⁺ to the La 3+ content ((Zn ²⁺ + Ba ²⁺ )/La ³⁺ ) achieves the above optical properties while improving glass stability. From the viewpoint of It is even more preferable that it is the above. The cation ratio ((Zn ²⁺ +Ba ²⁺ )/La ³⁺ ) is preferably 0.66 or less from the viewpoint of improving meltability, lowering specific gravity, and suppressing excessive increase in glass transition temperature, It is more preferably at most 0.50, even more preferably at most 0.40, even more preferably at most 0.30, even more preferably at most 0.25, and even more preferably at most 0.20. It is even more preferably that it is 0.16 or less, even more preferably that it is 0.14 or less, even more preferably that it is 0.13 or less, Even more preferably, it is less than or equal to 0.11, even more preferably less than or equal to 0.10, even more preferably less than or equal to 0.090.

The cation ratio of the total content of Zn ²⁺ and Ba ²⁺ to the total content of La ³⁺ and Y ³⁺ ((Zn ²⁺ + Ba ²⁺ )/(La ³⁺ + Y ³⁺ )) is From the viewpoint of achieving the above optical properties while improving stability, it is preferably 0.00 or more, more preferably 0.001 or more, even more preferably 0.003 or more, and 0.00 or more. More preferably, it is 005 or more. The above cation ratio ((Zn ²⁺ +Ba ²⁺ )/(La ³⁺ +Y ³⁺ )) should be 0.66 or less from the viewpoint of improving meltability, lowering specific gravity, and suppressing excessive increase in glass transition temperature. It is preferably at most 0.50, even more preferably at most 0.40, even more preferably at most 0.30, even more preferably at most 0.25, It is even more preferably 0.20 or less, even more preferably 0.15 or less, even more preferably 0.13 or less, even more preferably 0.12 or less, It is even more preferably not more than 0.11, even more preferably not more than 0.10, especially preferably not more than 0.090, even more preferably not more than 0.085, It is especially more preferable that it is 0.080 or less.

Since Li ⁺ has a strong effect of lowering the glass transition temperature, as its content increases, machinability tends to decrease. Furthermore, glass stability, chemical durability, and weather resistance also tend to decrease. Therefore, the Li ⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it be present, even more preferably that it is 2% or less, and even more preferably that it is 1% or less. Moreover, the Li ⁺ content can be 0% or more, and may be 0%.

Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ all have the function of improving the meltability of glass, but when their content increases, glass stability, chemical durability, weather resistance, and machining properties deteriorate. The gender shows a decreasing trend. Therefore, the preferred ranges of each content of Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ are as follows.
The Na ⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it is 2% or less, even more preferably that it is 1% or less. Further, the Na ⁺ content can be 0% or more, and may be 0%.
The K ⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it is 2% or less, even more preferably that it is 1% or less. Further, the K ⁺ content can be 0% or more, and may be 0%.
The Rb ⁺ content is preferably 10% or less, more preferably 8 % or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it is 2% or less, even more preferably that it is 1% or less. Further, the Rb ⁺ content can be 0% or more, and may be 0%.
The Cs ⁺ content is preferably 10% or less, more preferably 8 % or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it is 2% or less, even more preferably that it is 1% or less. Further, the Cs ⁺ content can be 0% or more, and may be 0%.

Al ³⁺ is a component that functions to improve the chemical durability and weather resistance of glass. However, when the content of Al ³⁺ increases, there may be a tendency for the refractive index to decrease, the glass stability to decrease, and the meltability to decrease. Considering the above points, the preferable range of Al ³⁺ content is as follows.
The Al ³⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 3% or less. It is even more preferable that it be present, even more preferably that it is 2% or less, and even more preferably that it is 1% or less. Further, the Al ³⁺ content can be 0% or more, and may be 0%.

Zr ⁴⁺ is a component that has the function of increasing the refractive index, and by containing it in an appropriate amount, it also has the function of improving glass stability. Zr ⁴⁺ also has the function of making the glass less likely to break during mechanical processing by increasing the glass transition temperature. From the viewpoint of obtaining these effects favorably, the Zr ⁴⁺ content is preferably 0% or more, more preferably 1% or more, even more preferably 2% or more, and even more preferably 3% or more. It is more preferable that the amount is 4% or more, and even more preferably that it is 4% or more. From the viewpoint of improving glass stability, the Zr ⁴⁺ content is preferably 15% or less, more preferably 13% or less, even more preferably 10% or less, and 9% or less. It is more preferable that it is 8% or less, even more preferably that it is 7% or less, and even more preferably that it is 6% or less.

P ⁵⁺ is a component that lowers the refractive index and is also a component that lowers glass stability, but if it is introduced in a very small amount, it may improve glass stability. In order to obtain a glass having the above optical properties and excellent glass stability, the preferable range of the P ⁵⁺ content is as follows.
The P ⁵⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the P ⁵⁺ content can be 0% or more, and may be 0%.

Ga ³⁺ , In ³⁺ , Sc ³⁺ and Hf ⁴⁺ all have the function of increasing the refractive index. However, these components are not essential components for obtaining the above glass. The preferred ranges of each content of Ga ³⁺ , In ³⁺ , Sc ³⁺ and Hf ⁴⁺ are as follows.
The Ga ³⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the Ga ³⁺ content can be 0% or more, and may be 0%.
The In ³⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the In ³⁺ content can be 0% or more, and may be 0%.
The Sc ³⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the Sc ³⁺ content can be 0% or more, and may be 0%.
The Sc ³⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the Sc ³⁺ content can be 0% or more, and may be 0%.
The Hf ⁴⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, even more preferably 4% or less, and even more preferably 2% or less. It is even more preferable that there be. Further, the Hf ⁴⁺ content can be 0% or more, and may be 0%.

Lu ³⁺ has the function of increasing the refractive index, but is also a component that increases the specific gravity of the glass. Further, since Lu is a heavy rare earth element like Gd and Yb, from the viewpoint of stable supply of glass, it is desirable that the Lu ³⁺ content is low. From the above viewpoint, the Lu ³⁺ content is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, and even more preferably 4% or less. , 2% or less is even more preferable. Moreover, the Lu ³⁺ content can be 0% or more, and may be 0%.

Ge ⁴⁺ has the function of increasing the refractive index, but from the viewpoint of further cost reduction of optical elements, the Ge ⁴⁺ content is preferably 10% or less, and preferably 8% or less. It is more preferably 6% or less, even more preferably 4% or less, even more preferably 2% or less. Moreover, the Ge ⁴⁺ content can be 0% or more, and may be 0%.

Te ⁴⁺ is a component that increases the refractive index, but from the viewpoint of environmental considerations, it is preferable that the Te ⁴⁺ content is small. The Te ⁴⁺ content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and 1% or less. It is even more preferable that there be. Further, the Te ⁴⁺ content can be 0% or more, and may be 0%.

Pb, As, Cd, Tl, Be and Se each have toxicity. Therefore, it is preferable not to contain these elements, that is, not to introduce these elements into the glass as glass components.
U, Th, and Ra are all radioactive elements. Therefore, it is preferable not to contain these elements, that is, not to introduce these elements into the glass as glass components.
V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm and Ce increase the coloring of the glass and become sources of fluorescence. , is not preferable as an element to be included in glass for optical elements. Therefore, it is preferable not to contain these elements, that is, not to introduce these elements into the glass as glass components.

Sb and Sn are optional elements that function as refining agents.
The Sb content of the optical glass is, for example, ^0.40 % or less, 0.20% or less, 0.10% or less, 0.05% or less, 0.02% or less, 0. 0.01% or less. The Sb ³⁺ content can be greater than or equal to 0.00%, and can also be 0.00%.
The Sn content of the optical glass is, for example, ^0.40 % or less, 0.20% or less, 0.10% or less, 0.05% or less, 0.02% or less, 0. 0.01% or less. The Sn ^{2 +} content can be greater than or equal to 0.00%, and can also be 0.00%.

The cation component has been explained above. Next, the anion component will be explained.

The optical glass may be an oxide glass and may include O ^2- as an anion component. The O ^2- content is preferably 95.0 anion% or more, more preferably 97.0 anion% or more, even more preferably 98.0 anion% or more, and 99.0 anion%. The content is more preferably 99.5% or more, even more preferably 99.5% anions, and may be 100% anions.

Examples of anion components other than O ^{2 -} include F ^- , Cl ^- , Br ^- and I ^- . However, F ^- , Cl ^- , Br ^- and I ^- all easily volatilize during melting of the glass. Volatilization of these components tends to change the physical properties of the glass, reduce the homogeneity of the glass, and significantly wear out the melting equipment. Therefore, it is preferable to suppress the total content of F ^- , Cl ^- , Br ^- and I ^- to an amount obtained by subtracting the O ^{2 -} content from 100 anion %.

<Glass physical properties>
(Refractive index nd, Abbe number νd)
The optical glass is a high refractive index, low dispersion glass having a refractive index nd in the range of 1.9000 to 2.1500 and an Abbe number νd in the range of 20.0 to 35.0. From the viewpoint of usefulness as a material for optical elements, the preferred ranges of the refractive index nd and Abbe number νd are as follows.
The refractive index nd is 1.9000 or more, preferably 1.9500 or more, more preferably 1.9600 or more, even more preferably 1.9700 or more, and 1.9800 or more. is even more preferable, it is even more preferable that it is 1.9850 or more, it is even more preferable that it is 1.9900 or more, it is even more preferable that it is 1.9950 or more, and it is even more preferable that it is 2.0000 or more. Even more preferred. Further, the refractive index nd is 2.1500 or less, preferably 2.1000 or less, more preferably 2.0500 or less, even more preferably 2.0300 or less, and 2.0100 or less. It is more preferable that it is, and it is even more preferable that it is 2.0020 or less.
The Abbe number νd is a value that represents the properties related to dispersion, and is expressed as νd = (nd-1)/(nF-nC) using the refractive indices nd, nF, and nC at the d-line, F-line, and C-line. . The Abbe number is 35.0 or less, preferably 34.0 or less, more preferably 33.0 or less, even more preferably 32.0 or less, and 31.0 or less. is more preferably 30.5 or less, even more preferably 30.0 or less, and even more preferably 29.5 or less. Further, the Abbe number νd is 20.0 or more, preferably 21.0 or more, more preferably 22.0 or more, even more preferably 23.0 or more, and 24.0 or more. It is more preferably 25.0 or more, even more preferably 26.0 or more, even more preferably 27.0 or more, and even more preferably 27.5 or more. Even more preferably, it is 28.0 or more, even more preferably 28.3 or more.
Further, it is also preferable that the refractive index nd and the Abbe number νd satisfy one or more of the following relational expressions.
nd≧2.3700-0.0140×νd
nd≧2.1450-0.0070×νd
nd≧2.3900-0.0140×νd
nd≧2.1510-0.0070×νd
nd≧2.3960-0.0140×νd
nd≧2.1550-0.0070×νd
nd≧2.4000-0.0140×νd
nd≧2.1600-0.0070×νd
nd≧2.1700-0.0070×νd
nd≧2.0715-0.0380×νd
nd≧2.0915-0.0380×νd
nd≧2.1015-0.0380×νd
nd≦2.4900-0.0140×νd
nd≦2.4500-0.0140×νd
nd≦2.4300-0.0140×νd
nd≦2.4200-0.0140×νd
In the present invention and this specification, unless otherwise specified, "refractive index" means "refractive index nd", and "Abbe number" means "Abbe number νd".

(Partial dispersion characteristics Pg, F)
From the viewpoint of chromatic aberration correction, the optical glass is preferably a glass having a small partial dispersion ratio when the Abbe number νd is fixed.
Here, the partial dispersion ratios Pg and F are expressed as (ng-nF)/(nF-nc) using the refractive indexes ng, nF, and nc at the g-line, F-line, and c-line, respectively.
From the viewpoint of providing a high refractive index, low dispersion glass suitable for high-order chromatic aberration correction, the preferable ranges of the partial dispersion ratios Pg and F of the optical glass are as follows.
The partial dispersion ratio Pg,F is preferably 0.6500 or less, more preferably 0.6300 or less, even more preferably 0.6200 or less, and even more preferably 0.6100 or less. , 0.6000 or less is even more preferable. Further, the partial dispersion ratio Pg,F is preferably 0.5700 or more, more preferably 0.5800 or more, even more preferably 0.5820 or more, and preferably 0.5850 or more. More preferably, it is 0.590 or more.

(Liquidus temperature LT)
From the viewpoint of suppressing crystallization during glass production, the liquidus temperature LT of the optical glass is preferably 1400°C or lower, more preferably 1380°C or lower, and even more preferably 1360°C or lower. The temperature is preferably 1340°C or lower, even more preferably 1320°C or lower, even more preferably 1310°C or lower, even more preferably 1300°C or lower, and even more preferably 1290°C or lower. Still more preferably at most 1280°C, even more preferably at most 1270°C, still even more preferably at most 1260°C. The liquidus temperature LT can be, for example, 1150° C. or higher. However, since it is preferable that the liquidus temperature is low, the liquidus temperature may be lower than 1150°C, and the lower limit is not particularly limited.

(Glass transition temperature Tg)
The glass transition temperature Tg of the optical glass is not particularly limited, but from the viewpoint of machinability, it is preferably 630° C. or higher. By setting the glass transition temperature to 630° C. or higher, it is possible to make the glass less likely to be damaged when machining the glass, such as cutting, cutting, grinding, and polishing. From the viewpoint of machinability, the glass transition temperature Tg is more preferably 640°C or higher, even more preferably 700°C or higher, even more preferably 710°C or higher, and even more preferably 720°C or higher . The temperature is even more preferably 730°C or higher, even more preferably 740°C or higher, and even more preferably 745°C or higher. On the other hand, from the viewpoint of reducing the burden on the annealing furnace and mold, the glass transition temperature Tg is preferably 800°C or lower, more preferably 790°C or lower, and even more preferably 780°C or lower. The temperature is more preferably 775°C or lower, even more preferably 770°C or lower, even more preferably 765°C or lower, and even more preferably 760°C or lower.

(specific gravity, specific gravity/nd)
The refractive power of the optical elements (lenses) that make up the optical system is determined by the refractive index of the glass that makes up the lens and the curvature of the optically functional surface of the lens (the surface through which the light beam to be controlled enters and exits). Increasing the curvature of the optically functional surface also increases the thickness of the lens. As a result, the lens becomes heavier. On the other hand, if glass with a high refractive index is used, a large refractive power can be obtained without increasing the curvature of the optically functional surface.
From the above, if the refractive index can be increased while suppressing an increase in the specific gravity of glass, it is possible to reduce the weight of an optical element having a certain refractive power.
From the above viewpoint, the specific gravity of the optical glass is preferably 5.40 or less, more preferably 5.35 or less, even more preferably 5.30 or less, and 5.25 or less. is more preferably 5.20 or less, even more preferably 5.15 or less, even more preferably 5.10 or less, and even more preferably 5.05 or less. It is even more preferred, and even more preferred that it is 5.00 or less. Since the lower the specific gravity is, the more preferable it is from the viewpoint of reducing the weight of the optical element, the lower limit of the specific gravity of the optical glass is not particularly limited. In one embodiment, the specific gravity of the optical glass is, for example, 4.30 or more, 4.40 or more, 4.50 or more, 4.60 or more, 4.70 or more, 4.75 or more, 4.77 or more, 4. It can be 80 or more or 4.85 or more.
From the same viewpoint, the value obtained by dividing the specific gravity of the optical glass by the refractive index nd (specific gravity/nd) is preferably 2.80 or less, more preferably 2.70 or less, and 2. It is more preferably 65 or less, even more preferably 2.60 or less, even more preferably 2.56 or less, even more preferably 2.54 or less, and even more preferably 2.52 or less. Even more preferably, it is 2.51 or less, even more preferably 2.50 or less. Since the smaller the value of "specific gravity/nd" is, the more preferable it is from the viewpoint of reducing the weight of the optical element, the lower limit of the value of "specific gravity/nd" of the optical glass is not particularly limited. In one aspect, the "specific gravity/nd" of the optical glass is, for example, 2.20 or more, 2.30 or more, 2.35 or more, 2.36 or more, 2.37 or more, 2.38 or more, 2.39. or more, 2.40 or more, 2.41 or more, 2.42 or more, or 2.43 or more.

(Coloring degree λ5, λ70)
The light transmittance of the glass, specifically, the fact that the light absorption edge on the short wavelength side is suppressed from becoming longer in wavelength can be evaluated by the degree of coloration λ5. The degree of coloring λ5 represents a wavelength at which the spectral transmittance (including surface reflection loss) of a 10 mm thick glass is 5% from the ultraviolet region to the visible region. λ5 shown in Examples below is a value measured in a wavelength range of 250 to 700 nm. Spectral transmittance refers to, for example, using a glass sample polished to a thickness of 10.0 ± 0.1 mm and having planes parallel to each other, and incident light from a direction perpendicular to the polished surface. The spectral transmittance obtained is Iout/Iin, where Iin is the intensity of the light incident on the glass sample, and Iout is the intensity of the light transmitted through the glass sample.
According to the coloring degree λ5, the absorption edge on the short wavelength side of the spectral transmittance can be quantitatively evaluated. When joining lenses together using an ultraviolet curable adhesive to produce a cemented lens, the adhesive is cured by irradiating the adhesive with ultraviolet rays through an optical element. From the viewpoint of efficiently curing the ultraviolet curable adhesive, it is preferable that the absorption edge on the short wavelength side of the spectral transmittance is in a short wavelength range. The degree of coloration λ5 can be used as an index for quantitatively evaluating the absorption edge on the short wavelength side. The optical glass preferably has a particle diameter of 400 nm or less, more preferably 390 nm or less, still more preferably 385 nm or less, even more preferably 380 nm or less, even more preferably 378 nm or less, even more preferably 376 nm or less, even more preferably 374 nm or less, Even more preferably it can exhibit a λ5 of 372 nm or less, even more preferably 370 nm or less. The lower λ5 is, the more preferable it is, and the lower limit is not particularly limited. In one aspect, λ5 of the optical glass is 330 nm or more, 340 nm or more, 345 nm or more, 350 nm or more, 355 nm or more, 356 nm or more, 357 nm or more, 358 nm or more, 359 nm or more, 360 nm or more, 361 nm or more, 362 nm or more, or 363 nm or more. Something can happen.

On the other hand, as an index of the degree of coloration of glass, the degree of coloration λ70 can also be mentioned. λ70 represents a wavelength at which the spectral transmittance measured by the method described for λ5 is 70%. From the viewpoint of obtaining a glass with little coloration, λ70 is preferably 500 nm or less, more preferably 490 nm or less, even more preferably 480 nm or less, even more preferably 470 nm or less, even more preferably 460 nm or less, even more preferably 457 nm or less, and even more preferably 457 nm or less. Even more preferably 455 nm or less, even more preferably 450 nm or less, even more preferably 445 nm or less, even more preferably 440 nm or less. The lower λ70 is, the more preferable it is, and the lower limit is not particularly limited. In one aspect, λ70 of the optical glass can be 370 nm or more, 380 nm or more, 390 nm or more, 400 nm or more, 410 nm or more, 420 nm or more, 425 nm or more, 430 nm or more, or 435 nm or more.

(λ5/nd, λ5/νd, λ70/nd, λ70/νd)
Regarding the degree of coloration, it is preferable that the refractive index can be increased while suppressing an increase in the degree of coloration of the glass. Further, it is also preferable that dispersion can be reduced while suppressing an increase in the degree of coloration of the glass.
From the above viewpoint, the value obtained by dividing λ5 by the refractive index nd (λ5/nd) of the optical glass is preferably 195.00 nm or less, more preferably 190.00 nm or less, and 188.00 nm or less. It is more preferably 187.00 nm or less, even more preferably 187.50 nm or less, even more preferably 187.00 nm or less, and even more preferably 186.50 nm or less. Even more preferably, it is 186.00 nm or less, even more preferably 185.55 nm or less, and even more preferably 185.00 nm or less. Moreover, the lower λ5/nd is, the more preferable it is, and the lower limit is not particularly limited. In one aspect, λ5/nd of the optical glass is 160.00 nm or more, 170.00 nm or more, 171.00 nm or more, 172.00 nm or more, 173.00 nm or more, 174.00 nm or more, 175.00 nm or more, 176.0 nm or more. 00 nm or more, 177.00 nm or more, or 178.00 nm or more.
The value (λ5/νd) obtained by dividing λ5 by the Abbe number νd of the optical glass is preferably 20.00 nm or less, more preferably 15.00 nm or less, and even more preferably 14.00 nm or less. It is preferably 13.00 nm or less, even more preferably 12.90 nm or less, even more preferably 12.80 nm or less, and even more preferably 12.70 nm or less. Further, the lower λ5/νd is, the more preferable it is, and the lower limit is not particularly limited. In one aspect, λ5/νd of the optical glass is 8.00 nm or more, 8.50 nm or more, 9.00 nm or more, 9.50 nm or more, 10.00 nm or more, 10.50 nm or more, 11.00 nm or more, 11. It can be 50 nm or more, 11.70 nm or more, 12.00 nm or more, 12.10 nm or more, 12.20 nm or more, 12.30 nm or more, 12.40 nm or more, or 12.50 nm or more.
The value obtained by dividing λ70 by the refractive index nd (λ70/nd) of the optical glass is preferably 270.00 nm or less, more preferably 260.00 nm or less, and still more preferably 250.00 nm or less. preferably, 240.00 nm or less, more preferably 235.00 nm or less, even more preferably 230.00 nm or less, even more preferably 227.00 nm or less, Even more preferred is 225.00 nm or less. Further, the lower λ70/nd is, the more preferable it is, and the lower limit is not particularly limited. In one embodiment, the optical glass has a λ70/nd of 190.00 nm or more, 200.00 nm or more, 205.00 nm or more, 210.00 nm or more, 212.00 nm or more, 214.00 nm or more, 216.00 nm or more, 218. 00 nm or more, or 220.00 nm or more.
The value (λ70/νd) obtained by dividing λ70 by the Abbe number νd of the optical glass is preferably 25.00 nm or less, more preferably 22.00 nm or less, and still more preferably 20.00 nm or less. It is preferably 19.00 nm or less, even more preferably 18.00 nm or less, even more preferably 17.00 nm or less, and even more preferably 16.00 nm or less. Moreover, the lower λ70/νd is, the more preferable it is, and the lower limit is not particularly limited. In one embodiment, the optical glass has a λ70/νd of 8.00 nm or more, 9.00 nm or more, 10.00 nm or more, 11.00 nm or more, 12.00 nm or more, 13.00 nm or more, 14.00 nm or more, or 15.0 nm or more. 00 nm or more.

<Glass manufacturing method>
The above-mentioned optical glass can be obtained, for example, by blending, melting, and molding glass raw materials so as to obtain desired characteristics. As the glass raw material, for example, phosphates, fluorides, alkali metal compounds, alkaline earth metal compounds, etc. may be used. Known methods may be used for glass melting and molding.

[Glass material for press molding, optical element blank, and manufacturing method thereof]
Another aspect of the present invention is
Glass material for press molding made of the above optical glass;
An optical element blank made of the above optical glass,
Regarding.

According to another aspect of the present invention,
A method for producing a press-molding glass material, comprising a step of forming the optical glass into a press-molding glass material;
A method for producing an optical element blank, comprising the step of producing an optical element blank by press-molding the glass material for press-molding using a press mold;
A method for producing an optical element blank, comprising a step of molding the optical glass into an optical element blank;
is also provided.

An optical element blank is a material that approximates the shape of the intended optical element, and can be polished to the shape of the optical element (the surface layer will be removed by polishing), or ground as necessary (the surface layer will be removed by grinding). This is an optical element base material with a surface layer) added. The optical element is finished by grinding and polishing the surface of the optical element blank. In one embodiment, an optical element blank can be produced by a method of press-molding a molten glass obtained by melting an appropriate amount of the optical glass (referred to as a direct press method). In another aspect, an optical element blank can also be produced by melting an appropriate amount of the above glass and solidifying a molten glass.

In another aspect, an optical element blank can be produced by producing a press-molding glass material and press-molding the produced press-molding glass material.

Press molding of the glass material for press molding can be performed by a known method of pressing the glass material for press molding that has been heated and softened using a press mold. Both heating and press molding can be performed in the atmosphere. By annealing the glass after press molding to reduce distortion inside the glass, a homogeneous optical element blank can be obtained.

Press-molding glass materials are used in their original state as press-molding glass gobs to produce optical element blanks, and in addition to press-molding glass gobs that are subjected to mechanical processing such as cutting, grinding, and polishing. It also includes those that are subjected to press molding after passing through the process. The cutting method is to form grooves on the surface of the glass plate where you want to cut using a method called scribing, and then apply local pressure to the grooved area from the back side of the surface where the groove was formed, so that the glass plate is cut in the grooved area. There are methods such as breaking the glass plate and cutting the glass plate with a cutting blade. Furthermore, examples of the grinding and polishing methods include barrel polishing.

The glass material for press molding can be produced, for example, by casting molten glass into a mold to form a glass plate, and cutting the glass plate into a plurality of glass pieces. Alternatively, a glass gob for press molding can also be produced by molding an appropriate amount of molten glass. An optical element blank can also be produced by reheating, softening, and press-molding a glass gob for press molding. The method of producing an optical element blank by reheating and softening glass and press-molding it is called a reheat press method, as opposed to a direct press method.

[Optical element and its manufacturing method]
Another aspect of the present invention is
The present invention relates to an optical element made of the optical glass described above.
The optical element is manufactured using the optical glass. In the above optical element, one or more coatings such as a multilayer film such as an antireflection film may be formed on the glass surface.

Further, according to one aspect of the present invention,
A method for manufacturing an optical element, comprising a step of manufacturing an optical element by grinding and/or polishing the optical element blank;
is also provided.

In the above method for manufacturing an optical element, known methods may be used for grinding and polishing, and by thoroughly cleaning and drying the surface of the optical element after processing, it is possible to obtain an optical element with high internal quality and surface quality. can. In this way, an optical element made of the above optical glass can be obtained. Examples of optical elements include various lenses such as spherical lenses, aspherical lenses, and microlenses, prisms, and the like.

Further, the optical element made of the above optical glass is also suitable as a lens constituting a cemented optical element. Examples of the cemented optical element include one in which lenses are cemented together (a cemented lens), and one in which a lens and a prism are cemented together. For example, a bonded optical element is manufactured by precisely processing (e.g., spherical polishing) the bonding surfaces of two optical elements to be bonded so that the shape is inverted, and using an ultraviolet curing adhesive used to bond the bonded lens. It can be manufactured by coating the adhesive, bonding it together, and then irradiating it with ultraviolet light through a lens to harden the adhesive. The above-mentioned optical glass is preferable as an optical element material for producing a bonded optical element in this way. By manufacturing a plurality of optical elements to be bonded using a plurality of types of optical glass having different Abbe numbers νd and bonding them, an element suitable for correcting chromatic aberration can be obtained.

As a result of quantitative analysis of the glass composition, the glass components may be expressed on an oxide basis, and the content of the glass components may be expressed in mass %. The composition expressed as % by mass on an oxide basis can be converted into a composition expressed as cation % or anion %, for example, by the following method.
When glass contains N types of glass components, the k-th glass component is expressed as A(k) _m O _n . However, k is any integer greater than or equal to 1 and less than or equal to N.
A(k) is a cation, O is oxygen, and m and n are integers determined stoichiometrically. For example, when the oxide-based notation is B ₂ O ₃ , m=2 and n=3, and when it is SiO ₂ , m=1 and n=2.
Next, the content of A(k) _m O _n is defined as X(k) [mass%]. Here, if the atomic weight of A(k) is P(k) and the atomic number of oxygen O is Q, then the formal molecular weight R(k) of A(k) _m O _n is
R(k)=P(k)×m+Q×n
becomes.
Furthermore,
B=100/{Σ[m×X(k)/R(k)]}
Then, the content (cation %) of the cation component A(k) ^s+ is [X(k)/R(k)]×m×B (cation %). Here, Σ means the sum of m×X(k)/R(K) from k=1 to N. m changes depending on k. s is 2n/m.
Further, the molecular weight R(k) may be calculated by rounding off the fourth decimal place and displaying the value up to the third decimal place. The molecular weights of some glass components and additives expressed on an oxide basis are shown in Table 1 below.

EXAMPLES Below, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the embodiments shown in the examples.

<Example 1>
In order to obtain the glass composition shown in the table below, the corresponding nitrates, sulfates, carbonates, hydroxides, oxides, boric acids, etc. are used as raw materials for introducing each component, and the raw materials are weighed, The mixture was thoroughly mixed and used as a raw material for preparation.
This mixed raw material was placed in a platinum crucible, heated and melted. After melting, the molten glass is poured into a mold, allowed to cool to around the glass transition temperature, then immediately placed in an annealing furnace, annealed for about 1 hour within the glass transition temperature range, and then allowed to cool to room temperature in the furnace. , each optical glass (oxide glass) shown in Table 1 was obtained.
For the anionic components of each optical glass shown in the table below, the O ^2- content is 100% anion.
When the obtained optical glass was observed under magnification using an optical microscope, no crystal precipitation, foreign matter such as platinum particles, or bubbles were observed, and no striae were observed.
The physical properties of the optical glass thus obtained are shown in the table below.
Various physical properties of the optical glass were measured by the methods shown below.

<Evaluation of physical properties of optical glass>
(1) Refractive index nd, ng, nF, nC and Abbe number νd
The refractive index nd, ng, nF, nC, and Abbe number νd of the glass obtained by lowering the temperature at a cooling rate of −30° C./hour were measured by the refractive index measurement method specified by the Japan Optical Glass Industry Association.

(2) Partial dispersion ratio Pg,F
Partial dispersion ratios Pg and F were calculated from the refractive indices ng, nF, and nC determined in (1) above.

(3) Glass transition temperature Tg
Using a differential scanning calorimeter (DSC3300) manufactured by NETZSCH, the glass transition temperature Tg was measured at a heating rate of 10° C./min.

(4) Liquidus temperature LT
A glass sample (volume: 10 cm ³ ) made of each glass shown in the table below was placed in a platinum crucible and kept in a glass melting furnace set at 1400°C for 20 minutes to fully melt the glass sample and bring it to a molten state. After that, the platinum crucible was taken out from the glass melting furnace, and the glass sample was left to cool in the platinum crucible until the temperature of the glass sample became 500° C. or lower. Thereafter, the above-mentioned platinum crucible was placed in a glass melting furnace set at a temperature of T°C and maintained for 2 hours. After taking it out of the furnace, the platinum crucible containing the glass sample was immediately (within 8 seconds) heated to room temperature. Placed on a refractory (such as brick), the glass sample was cooled to room temperature. The room temperature here is a temperature in the range of -10 to 80°C. Thereafter, the surface and interior of the glass sample were visually observed to confirm the presence or absence of crystals. The above experiment was repeated by changing the temperature T° C. in the range of 1100 to 1350° C. in 10° C. increments, and the lowest temperature at which no crystals were observed on the surface or inside of the glass sample was taken as the liquidus temperature LT.

(5) Specific gravity, specific gravity/nd
Specific gravity was measured by Archimedes method.
A value (specific gravity/nd) was calculated by dividing the measured specific gravity by the refractive index nd determined in (1) above.

(6) Coloring degree λ5, λ70
Using a glass sample with a thickness of 10 ± 0.1 mm and having two optically polished planes facing each other, light with an intensity of Iin was incident on the polished surface from a direction perpendicular to the glass sample using a spectrophotometer. The intensity Iout of the transmitted light was measured, the spectral transmittance Iout/Iin was calculated, and the wavelength at which the spectral transmittance was 5% was defined as λ5, and the wavelength at which the spectral transmittance was 70% was defined as λ70.

(7) λ5/nd, λ5/νd, λ70/nd, λ70/νd
λ5/nd, λ5/νd, λ70/nd and λ70/νd were calculated from nd, νd, λ5 and λ70 determined above.

The above results are shown in Table 2 below (Tables 2-1 to 2-6).

<Evaluation of glass stability>
Glass is obtained by molding molten glass. When glass stability is low, the number of crystal grains contained in the glass obtained by pouring molten glass into a mold and forming it increases. Therefore, glass stability, particularly devitrification resistance when molding a glass melt, can be evaluated by the number of crystals contained in the glass melted and molded under certain conditions. An example of the evaluation method is shown below.
Nitrate, sulfate, carbonate, hydroxide, oxide, boric acid, etc. are used as raw materials. Each raw material powder is weighed and thoroughly mixed to form a compounded raw material. This compounded raw material is placed in a platinum crucible with a capacity of 300 ml. The mixture was heated and melted in a glass melting furnace set at 1400° C. for 2 hours to produce 150 g of homogeneous molten glass. During this time, the molten glass is stirred and shaken several times.
After 2 hours, the crucible containing the molten glass was taken out from the above furnace, stirred and shaken for 15 to 20 seconds, and then poured into a carbon mold (50 mm x 40 mm x 8 mm to 12 mm) and placed in a slow cooling furnace. inside to remove distortion.
Observe the inside of the obtained glass using an optical microscope (100x magnification), count the number of precipitated crystals, calculate the number of crystals contained per 1 kg of glass, and calculate the number density of crystals (number of crystals). /kg).
The number density of crystals evaluated by the above method is preferably 2000 pieces/kg or less, more preferably 1000 pieces/kg or less, still more preferably 800 pieces/kg or less, and 600 pieces/kg or less. kg or less, even more preferably 400 pieces/kg or less, even more preferably 200 pieces/kg or less, even more preferably 100 pieces/kg or less, and even more preferably 50 pieces/kg or less. /kg or less is even more preferred, still more preferably 30 pieces/kg or less, and particularly preferably 0 pieces/kg. The number density of crystals of each glass shown in Table 2 above evaluated by the above method was all 0 crystals/kg.

<Example 2>
Using the various glasses obtained in Example 1, glass gobs for press molding were produced. This glass gob was heated and softened in the atmosphere and press-molded using a press mold to produce a lens blank (optical element blank). The produced lens blank was taken out from the press mold, annealed, and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

<Example 3>
A desired amount of the molten glass produced in Example 1 was press-molded using a press mold to produce a lens blank (optical element blank). The produced lens blank was taken out from the press mold, annealed, and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

<Example 4>
A glass lump (optical element blank) produced by solidifying the molten glass produced in Example 1 was annealed and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

<Example 5>
The spherical lenses produced in Examples 2 to 4 were bonded to spherical lenses made of other types of glass to produce cemented lenses. The cemented surfaces of the spherical lenses produced in Examples 2 to 4 were convex, and the cemented surfaces of the spherical lenses made of other types of optical glasses were concave. The two bonding surfaces were fabricated so that the absolute values of their radii of curvature were equal to each other. An ultraviolet curing adhesive for bonding optical elements was applied to the bonding surfaces, and the two lenses were bonded together. Thereafter, the adhesive applied to the joint surface was irradiated with ultraviolet rays through the spherical lenses prepared in Examples 2 to 4 to solidify the adhesive.
A cemented lens was produced as described above.

Finally, each aspect mentioned above will be summarized.

According to one aspect, in the glass composition expressed in cation %, the Ta ⁵⁺ content is in the range of 0 to 5 cation %, relative to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ . The cation ratio of Ti ⁴⁺ content (Ti ⁴⁺ / (Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ )) is in the range of 0.60 to 1.00, and La ³⁺ , Gd ³⁺ and Y The cation ratio of the total content of Si ⁴⁺ and B ³⁺ to the total content of 3+ (( ^{Si 4+ +} B ³⁺ )/(La ³⁺ +Gd ³⁺ +Y ³⁺ )) is 0.30 to 2. The cation ratio of the total content of Si ^{4+ and} B ³⁺ to the total content of Ti 4+ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ ((Si ⁴⁺ + B ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is in the range of 0.30 to 34.00, relative to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ The cation ratio of the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ ((La ³⁺ +Gd ³⁺ +Y ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 0.30. 33.00, and the cation ratio of the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ to the total content of La ³⁺ and Y ³⁺ (( Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(La ³⁺ +Y ³⁺ )) is in the range of 0.00 to 1.50, and the total content of Si ⁴⁺ and B ³⁺ Cation ratio of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ to the amount ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )) is in the range of 0.00 to 1.00, and Gd ³⁺ with respect to the total content of Si ⁴⁺ , B ³⁺ , Zn ²⁺ , La ³⁺ , Y ³⁺ , Zr ⁴⁺ and Ti ⁴⁺ , the cation ratio of the total content of Nb ⁵⁺ and W ⁶⁺ ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is in the range of 0.000 to 0.100, the refractive index nd is in the range of 1.9000 to 2.1500, and the Abbe number νd is in the range of 20.0 to 35.0. provided.

The optical glass has optical properties (nd and vd) useful as a material for optical elements. Furthermore, the optical glass described above has a low proportion of expensive glass components such as Ta ⁵⁺ , Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ , so it is an optical glass that can contribute to cost reduction of optical elements.

In one embodiment, the optical glass may have a total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ in a range of 0 to 30 cation%.

In one embodiment, the optical glass may have a total content of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ in a range of 0 to 8 cation%.

In one embodiment, the optical glass may have a total content of La ³⁺ , Gd ³⁺ and Y ³⁺ in a range of 20 to 60 cation%.

According to one aspect, a press-molding glass material made of the optical glass described above is provided.

According to one aspect, an optical element blank made of the optical glass described above is provided.

The glass material for press molding and the optical element blank are made of the optical glass in which the proportion of expensive glass components Ta ⁵⁺ , Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ is low, so that the cost of the optical element can be reduced. This can contribute to the

According to one aspect, an optical element made of the optical glass described above is provided.

The above-mentioned optical element is made of the above-mentioned optical glass in which the proportion of Ta ⁵⁺ , Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ which are expensive glass components is low, and therefore it can be manufactured at low cost.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.
For example, an optical glass according to one embodiment of the present invention can be obtained by adjusting the composition described in the specification with respect to the glass composition exemplified above.
Furthermore, it is of course possible to arbitrarily combine two or more of the items described as examples or preferred ranges in the specification.

Claims (6)

In the glass composition expressed as cation%,
Y ³⁺ content is in the range of 1 to 20 cation%,
Ta ⁵⁺ content is in the range of 0 to 5 cation%,
Zr ⁴⁺ content is in the range of 1 to 15 cation%,
The total content of Si ⁴⁺ and B ³⁺ (Si ⁴⁺ + B ³⁺ ) is in the range of 28 to 45 cation%,
The total content of La ³⁺ , Gd ³⁺ and Y ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ ) is in the range of 36 to 55 cation%,
The total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ) is in the range of 10 to 28 cation%,
The cation ratio of Ti ⁴⁺ content to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ (Ti ⁴⁺ /(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 0. ranges from .60 to 1.00,
The cation ratio of the total content of Si ⁴⁺ and B ³⁺ to the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ ((Si ⁴⁺ + B ³⁺ )/(La ³⁺ + Gd ³⁺ + Y ^{3 +} )) is 0. 7 ranges from 0 to 0.95 ,
The cation ratio of the total content of Si ⁴⁺ and B ³⁺ to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ ((Si ⁴⁺ +B ³⁺ )/(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 1.1 0 to 2 . 00 range,
Cation ratio of the total content of La ³⁺ , Gd ³⁺ and Y ³⁺ to the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ ((La ³⁺ + Gd ³⁺ + Y ³⁺ ) /(Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ )) is 1.0 0 to 2 . 00 range,
The cation ratio of the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ to the total content of La ³⁺ and Y ³⁺ ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(La ³⁺ +Y ³⁺ )) is in the range of 0.00 1 to 0.150 ,
The cation ratio of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba 2+ and Zn ²⁺ to the total content ^of Si ⁴⁺ and B ³⁺ ((Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )) is in the range of 0.00 1 to 0.150 ,
The cation ratio of Zn ²⁺ to the total content of La ³⁺ and Y ³⁺ (Zn ²⁺ /(La ³⁺ + Y ³⁺ )) is in the range of 0.001 to 0.15,
Cation ratio of the total content of Gd ³⁺ , Nb 5+ and ^{W 6+ to} the total content of Si ⁴⁺ , B ³⁺ , Zn ²⁺ , La ³⁺ , Y ³⁺ , Zr ⁴⁺ and Ti ⁴⁺ ((Gd ³⁺ +Nb ⁵⁺ +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is 0.000 to 0. 070 range,
Cation ratio ^{of the total} content of ^{Gd 3+} and ^{W 6+} ( ( Gd _ ^_ _ ^{_ 3+} +W ⁶⁺ )/(Si ⁴⁺ +B ³⁺ +Zn ²⁺ +La ³⁺ +Y ³⁺ +Zr ⁴⁺ +Ti ⁴⁺ )) is in the range of 0.000 to 0.002,
Refractive index nd is 1.9800 to 2. 03 00, and the Abbe number νd is 2 5 . 0-3 4 . Optical glass that is in the range of 0. The optical glass according to claim 1 , wherein the total content of Gd ³⁺ , Nb ⁵⁺ and W ⁶⁺ is in the range of 0 to 8 cation%. The optical glass according to claim 1 or 2, having a glass transition temperature Tg of 720°C or higher. A press-molding glass material comprising the optical glass according to any one of claims 1 to 3 . An optical element blank made of the optical glass according to any one of claims 1 to 3 . An optical element made of the optical glass according to any one of claims 1 to 3 .