JP2019137571A - Optical glass, preform, and optical element - Google Patents

Abstract

To provide an optical glass which has a refractive index and an Abbe number (high dispersion), and a low partial dispersion ratio, in which the relative refractive index has a small temperature coefficient.SOLUTION: The optical glass comprises, in mass%: 10.0% to 35.0% of an SiOcomponent; 10.0% to 35.0% of an NbOcomponent; more than 0% and up to 15.0% of an NaO component; more than 0% and up to 20.0% of a BaO component; more than 5.0% and up to 30.0% of an RnO component; and 5.0% to 30.0% of an RO component. The partial dispersion ratio (θg, F) satisfies the following relationship with the Abbe number (ν): (-0.008×ν+0.828)≤(θg, F)≤(-0.008×ν+0.876). The temperature coefficient (40°C to 60°C) of the relative refractive index (589.29 nm) is in a range of +6.0×10to -2.0×10(°C). (In the formula, R is at least one element selected from the group consisting of Mg, Ca, Sr and Ba; and Rn is at least one element selected from the group consisting of Li, Na and K.)SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical glass and an optical element.

  Optical systems such as digital cameras and video cameras, although large and small, contain blurs called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration. In particular, the chromatic aberration is strongly dependent on the material characteristics of the lens used in the optical system.

  In general, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens. However, this combination can only correct aberrations in the red region and the green region, and remains in the blue region. This blue region aberration that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, it is necessary to perform an optical design in consideration of 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 to be noticed in the optical design. In the optical system combining the low dispersion lens and the high dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low dispersion side lens, and the partial dispersion ratio ( By using an optical material having a small θg, F), the secondary spectrum is corrected well.

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

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing 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). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by Ohara, Inc., PBM2 has an Abbe number (ν _d ) of 36.3, a partial dispersion ratio (θg, F) of 0.5828, and NSL7 Abbe number (ν _d ). Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

In recent years, glass having an Abbe number (ν _d ) of 25 or more and 40 or less is often used as an optical material having a small partial dispersion ratio (θg, F) due to needs in optical design.

  In recent years, optical elements incorporated in in-vehicle optical devices such as in-vehicle cameras and optical elements incorporated in optical devices that generate a lot of heat, such as projectors, copiers, laser printers, and broadcasting equipment, Use in high temperature environments is increasing. In such a high temperature environment, the temperature at the time of use of the optical element constituting the optical system is likely to fluctuate greatly, and the temperature often reaches 100 ° C. or more. At this time, since the adverse effect on the imaging characteristics and the like of the optical system due to temperature fluctuation is so large that it cannot be ignored, it is required to construct an optical system in which the imaging characteristics and the like are hardly affected even by temperature fluctuation.

  When constructing an optical system that does not easily affect the imaging characteristics, etc. due to temperature fluctuations, an optical element made of glass whose refractive index decreases when the temperature rises and the temperature coefficient of the relative refractive index becomes negative. The combined use of an optical element made of glass that increases the refractive index when the temperature rises and has a positive temperature coefficient of relative refractive index can correct the influence on the imaging characteristics and the like due to the temperature change. This is preferable.

On the other hand, in an optical material having a small partial dispersion ratio (θg, F), the relative refractive index is increased by components (for example, Nb ₂ O ₅ component, CaO component, etc.) contained in order to obtain various excellent optical properties. The temperature coefficient tends to increase. As such an optical glass, a glass composition disclosed in Patent Document 1 is known.
Furthermore, optical glasses having a small partial dispersion ratio (θg, F) and a small temperature coefficient of relative refractive index are often used in various environments such as a vehicle-mounted lens and an interchangeable lens used in recent years. It has been demanded.

JP 2014-047098 A

However, the glass disclosed in Patent Document 1 contains a large amount of CaO component that increases the partial dispersion ratio and at the same time contains a large amount of Nb ₂ O ₅ component that increases the temperature coefficient of the relative refractive index. Therefore, it is not sufficient for correcting the secondary spectrum and using it as a lens having a small temperature index of relative refractive index.

The present invention has been made in view of the above-mentioned problems. The object of the present invention is to achieve a partial dispersion ratio (n _d ) and an Abbe number (ν _d ) within a desired range. The object is to obtain an optical glass having a small θg, F) and a small temperature coefficient of relative refractive index.

As a result of intensive studies and studies to solve the above problems, the present inventor, as a glass containing SiO ₂ component and Nb ₂ O ₅ component, contains Na ₂ O component and BaO component as essential components, and Rn ₂ O component is limited to 5.0 to 30.0% and RO component is limited to a range of 5.0 to 30.0% (R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) Rn is one or more selected from the group consisting of Li, Na, and K), and has a high refractive index and Abbe number (high dispersion) within a desired range, a low partial dispersion ratio, and relative It has been found that an optical glass having a small temperature coefficient of refractive index can be obtained, and the present invention has been completed.

(1) In mass%,
SiO ₂ component 10.0-35.0%,
Nb ₂ O ₅ component 10.0-35.0%
Na ₂ O component more than 0 to 15.0%,
BaO component more than 0 to 20.0%,
Rn ₂ O component more than 5.0 to 30.0%
RO component 5.0 to 30.0% contained,
Between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ),
The relationship of (−0.008 × ν _d +0.828) ≦ (θg, F) ≦ (−0.008 × ν _d +0.876) is satisfied,
An optical glass having a temperature coefficient (40 to 60 ° C.) of a relative refractive index (589.29 nm) within a range of + 6.0 × 10 ⁻⁶ to −2.0 × 10 ⁻⁶ (° C. ⁻¹ ) R is one or more selected from the group consisting of Mg, Ca, Sr and Ba, and Rn is one or more selected from the group consisting of Li, Na and K).

(2) The optical glass according to (1), wherein the mass ratio (BaO / Rn ₂ O) is 0.30 or more, wherein Rn is selected from the group consisting of Li, Na, and K More than species).

(3) Refractive index _{(n d)} and Abbe number ([nu _d) is, - satisfies the relation of _{(0.01 × ν d +2.03) ≦} n d ≦ (-0.01 × ν d +2.13) The optical glass according to (1) or (2).

(4) A preform material made of the optical glass according to any one of (1) to (3).

(5) An optical element comprising the optical glass according to any one of (1) to (3).

(6) An optical apparatus comprising the optical element according to (5).

According to the present invention, an optical glass having a low partial dispersion ratio and a small temperature coefficient of relative refractive index while having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range is obtained. Can do.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the Example of this application. Is a diagram showing the relationship between the refractive index of the present embodiment (n _d) and Abbe number (ν _d).

The optical glass of the present invention is the mass% of the oxide conversion composition, the SiO ₂ component is 10.0 to 35.0%, the Nb ₂ O ₅ component is 10.0 to 35.0%, and the Na ₂ O component is 0. It contains more than 15.0% and BaO component more than 0-15.0%, Rn ₂ O component more than 5.0-30.0%, RO component 5.0-30.0%, partial dispersion ratio (Θg, F) and Abbe number (ν _d ), (−0.008 × ν _d +0.828) ≦ (θg, F) ≦ (−0.008 × ν _d +0.876) And the temperature coefficient (40 to 60 ° C.) of the relative refractive index (589.29 nm) is in the range of + 6.0 × 10 ⁻⁶ to −5.0 × 10 ⁻⁶ (° C. ⁻¹ ). And
In optical glass containing a predetermined amount of SiO ₂ component and Nb ₂ O ₅ component, and containing Na ₂ O component and BaO component as essential components, high refractive index and Abbe number (high dispersion) within a desired range and low A glass having a partial dispersion ratio can be obtained. In particular, the Na ₂ O component is more than 0 to 15.0%, the BaO component is more than 0 to 15.0%, and the Rn ₂ O component is more than 5.0 to 30. By setting the RO component to 0% and 30.0%, the temperature coefficient of the relative refractive index can be reduced while keeping the partial dispersion ratio (θg, F) small.
Therefore, while having a desired high refractive index (n _d ) and low Abbe number (ν _d ), the partial dispersion ratio (θg, F) is small, useful for reducing chromatic aberration of the optical system, and relative refractive index. An optical glass having a small temperature coefficient can be obtained.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of 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 contents of the respective components are all expressed in mass% with respect to the total mass of the glass in terms of oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass component of the present invention are all decomposed and changed into an oxide when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

<About essential and optional components>
Since the SiO ₂ component promotes stable glass formation and can lower the liquidus temperature, it is an essential component for reducing devitrification (generation of crystal) that is not preferable for optical glass.
In particular, when the content of the SiO ₂ component is 10.0% or more, a glass having excellent devitrification resistance can be obtained without significantly increasing the partial dispersion ratio. Moreover, devitrification and coloring can be reduced. Therefore, the content of the SiO ₂ component is preferably 10.0% or more, more preferably 13.0% or more, and further preferably 15.0% or more.
On the other hand, when the content of the SiO ₂ component is 35.0% or less, the refractive index is less likely to be lowered, whereby a desired high refractive index can be easily obtained, and an increase in the partial dispersion ratio can be suppressed. Moreover, the fall of the meltability of a glass raw material can be suppressed by this. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 35.0% or less, more preferably 30.0% or less, further preferably 27.0% or less, and most preferably 25.0% or less.
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 that can increase the refractive index and reduce the Abbe number and the partial dispersion ratio.
In particular, by setting the content of the Nb ₂ O ₅ component to 10.0% or more, the refractive index is increased to the target optical constant, and the anomalous dispersion is reduced by adjusting the component within the range of the present invention. can do. Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0% or more, more preferably 11.5% or more, and further preferably 13.0% or more.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 35.0% or less, the temperature coefficient of the relative refractive index can be reduced and the material cost of the glass can be reduced.
Furthermore, devitrification of the glass can be reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably 35.0% or less, more preferably 33.0% or less, more preferably 31.0% or less, more preferably 28.0% or less, and still more preferably The upper limit is 25.0% or less.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When the Na ₂ O component exceeds 0%, it is an essential component that can enhance the meltability of the glass raw material, reduce the coloration, increase the thermal expansion coefficient, and decrease the temperature coefficient of the relative refractive index. Therefore, the content of the Na ₂ O component is preferably more than 0%, more preferably more than 1.0%, and still more preferably more than 3.0%.
On the other hand, by setting the content of the Na ₂ O component to 15.0% or less, a decrease in the refractive index can be suppressed, and devitrification due to excessive content can be reduced.
Therefore, the content of the Na ₂ O component is preferably 15.0% or less, more preferably 12.5% or less, and even more preferably less than 10.0%.
As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like can be used as a raw material.

The BaO component is an essential component that can increase the refractive index, increase the thermal expansion coefficient, and decrease the temperature coefficient of the relative refractive index when contained in excess of 0%. Accordingly, the lower limit of the BaO content is preferably more than 0%, more preferably more than 3.0%, and still more preferably more than 5.0%.
On the other hand, by setting the content of the BaO component to 20.0% or less, an increase in the partial dispersion ratio can be suppressed, and devitrification during reheat pressing can be reduced. Accordingly, the upper limit of the BaO component content is preferably 20.0% or less, more preferably less than 18.0%, and even more preferably less than 15.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ or the like can be used as a raw material.

Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) is a coefficient of thermal expansion when the sum of contents (mass sum) exceeds 5.0% Is an essential component capable of increasing the temperature and reducing the temperature coefficient of the relative refractive index. Therefore, the sum of the Rn ₂ O components is preferably more than 5.0%, more preferably more than 6.0%, more preferably more than 7.0%.
On the other hand, the sum (mass sum) of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 30.0% or less. Decrease in refractive index can be suppressed, and devitrification due to excessive inclusion can be reduced. Accordingly, the upper limit is preferably 30.0% or less, more preferably 28.0% or less, and still more preferably 25.0% or less.

RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr and Ba) has a coefficient of thermal expansion when the sum of contents (mass sum) is 5.0% or more. It is an essential component that can be increased and the temperature coefficient of the relative refractive index can be reduced. Therefore, the lower limit of the sum of RO components is preferably 5.0% or more, more preferably 7.0% or more, more preferably 9.0% or more, and further preferably 13.0% or more.
On the other hand, the sum (mass sum) of the content of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba) is 30.0% or less. An increase in the partial dispersion ratio can be suppressed, and devitrification due to excessive inclusion can be reduced. Therefore, the upper limit is preferably 30.0% or less, more preferably 29.0% or less, and still more preferably 28.0% or less.

The TiO ₂ component is an optional component that increases the refractive index and decreases the Abbe number when it is contained in excess of 0%. Accordingly, the TiO ₂ component is preferably more than 0%, more preferably 5.0% or more, and even more preferably 7.0% or more.
On the other hand, when the TiO ₂ component is contained in a large amount, the partial dispersion ratio increases. Further, by setting the content of the TiO ₂ component below 15.0%, it is possible to reduce the coloring of the glass, increasing the internal transmittance. In addition, this makes it difficult to increase the partial dispersion ratio, so that a desired low partial dispersion ratio close to the normal line can be easily obtained. Therefore, the upper limit of the content of the TiO ₂ component is preferably 15.0% or less, more preferably 12.5% or less, and still more preferably less than 10.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The K ₂ O component is an optional component that reduces coloring, increases the thermal expansion coefficient, and decreases the temperature coefficient of the relative refractive index when it is contained in excess of 0%.
Therefore, the lower limit of the content of the K ₂ O component is preferably more than 0%, more preferably more than 1.0%, and most preferably more than 3.0%.
On the other hand, by setting the content of the K ₂ O component to 15.0% or less, an increase in the partial dispersion ratio can be suppressed, an increase in the refractive index can be suppressed, and devitrification can be reduced. Accordingly, the upper limit of the content of the K ₂ O component is preferably 15.0% or less, more preferably less than 14.0%, and even more preferably less than 13.0%.
As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used as a raw material.

B ₂ O ₃ component is an optional component that, when contained in excess of 0%, promotes stable glass formation, lowers the liquidus temperature, enhances devitrification resistance, and enhances the meltability of the glass raw material. It is an ingredient. Therefore, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably more than 1.0%, and still more preferably more than 2.0%.
On the other hand, by making the content of the B ₂ O ₃ component 10.0% or less, it is possible to suppress a decrease in refractive index and an increase in partial dispersion ratio. Therefore, the content of the B ₂ O ₃ component is preferably 10.0% or less, more preferably 9.0%, more preferably 8.0% or less.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The Li ₂ O component is an optional component that can reduce the partial dispersion ratio, increase the thermal expansion coefficient, and decrease the temperature coefficient of the relative refractive index when it exceeds 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 0.5%, more preferably more than 1.0%.
On the other hand, by making the content of the Li ₂ O component 15.0% or less, devitrification due to excessive inclusion can be reduced, and devitrification of the reheat press can also be reduced.
Therefore, the content of the Li ₂ O component is preferably 15.0% or less, more preferably 10.0% or less, and even more preferably less than 7.0%.
For the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can increase the refractive index and Abbe number of the glass and lower the partial dispersion ratio when it is contained in excess of 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 1.0%, more preferably more than 3.0%, and still more preferably more than 5.0%.
On the other hand, when the content of the ZrO ₂ component is 15.0% or less, devitrification can be reduced, and more uniform glass can be easily obtained. Therefore, the content of the ZrO ₂ component is preferably 15.0% or less, more preferably 12.0% or less, and more preferably 10.0% or less.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The MgO component is an optional component that can reduce the temperature coefficient of the relative refractive index and 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. Accordingly, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.
As the MgO component, MgO, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

The CaO component is an optional component that can reduce the temperature coefficient of the relative refractive index, reduce devitrification, and increase the meltability of the glass raw material when it contains more than 0%. Accordingly, the content of the CaO component is preferably more than 0%, more preferably more than 3.0%, and still more preferably more than 5.0%.
On the other hand, an increase in the partial dispersion ratio can be suppressed by setting the content of the CaO component to 15.0% or less. Accordingly, the content of the CaO component is preferably 15.0% or less, more preferably less than 14.0%, and still more preferably less than 13.0%.
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 increase the resistance to devitrification when it contains more than 0%.
In particular, when the content of the SrO component is 10.0% or less, the glass is stabilized and the devitrification property of the glass can be suppressed. Therefore, the content of the SrO component is preferably 10.0% or less, more preferably less than 8.0%, further preferably less than 6.0%, and still more preferably less than 5.0%.
As the SrO component, Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

The ZnO component is an optional component that is inexpensive and can be adjusted to the high dispersion side when it contains more than 0%. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.
On the other hand, devitrification and coloring can be reduced by making the content of the ZnO component 10.0% or less. Therefore, the content of the ZnO component is preferably 10.0% or less, more preferably 8.0% or less, and more preferably less than 5.0%.

La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are optional components that can increase the refractive index and reduce the partial dispersion ratio by containing at least 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, Gd ₂ O ₃ component, Y ₂ O ₃ component, and Yb ₂ O ₃ component to 10.0% or less, an increase in the Abbe number can be suppressed. Throughness can be reduced and coloring can be reduced. Accordingly, the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component is preferably 10.0% or less, more preferably 9.0% or less, Preferably, the upper limit is less than 8.0%.
La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are 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 that can increase the refractive index, decrease the Abbe number and the partial dispersion ratio, and increase the devitrification resistance when the content exceeds 0%.
On the other hand, by making the content of Ta ₂ O ₅ component 10.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is easily melted at a lower temperature. Glass production costs can be reduced. Moreover, this can reduce the devitrification of the glass due to excessive inclusion of the Ta ₂ O ₅ component. Accordingly, the content of the Ta ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, even more preferably less than 3.0%, and even more preferably less than 1.0%. . In particular, from the viewpoint of reducing the material cost of glass, the Ta ₂ O ₅ component may not be contained.
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 that can increase the refractive index to lower the Abbe number and improve the meltability of the glass raw material when it contains more than 0%.
On the other hand, by making the content of the WO ₃ component 10.0% or less, it is possible to make it difficult to raise the partial dispersion ratio of the glass, and to reduce the coloring of the glass and to increase the internal transmittance. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, and still more preferably less than 1.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances the stability of the glass.
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%, and even more preferably less than 3.0%.
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 or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index and reduce devitrification when it contains more than 0%.
On the other hand, by making the content of the GeO ₂ component 10.0% or less, the amount of expensive GeO ₂ component used is 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%, and still more preferably less than 3.0%.
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 increase the refractive index and improve the devitrification resistance when at least one of them contains more than 0%.
On the other hand, devitrification due to excessive inclusion of Al ₂ O ₃ component or Ga ₂ O ₃ component is reduced by making each content of Al ₂ O ₃ component and Ga ₂ O ₃ component 10.0% or less. it can. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.
For 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 or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the Abbe number and lower the glass transition point when it 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%, and even 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 that can increase the refractive index, lower the partial dispersion ratio, and lower the glass transition point when contained in excess of 0%.
On the other hand, by setting 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. Moreover, glass with lower material costs can be obtained by reducing the use of expensive TeO ₂ components. Therefore, the content of the TeO ₂ component is preferably 5.0% or less, more preferably less than 3.0%, and even more preferably less than 1.0%.
TeO ₂ component can use TeO ₂ or the like 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 making the content of the SnO ₂ component 1.0% or less, it is possible to make it difficult to cause coloration of the glass due to the reduction of the molten glass and devitrification of the glass. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a 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 even more preferably less than 0.1%.
For 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 accelerates the defoaming of the glass when it contains more than 0% and clarifies the glass, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ component, by a content relative to the glass total weight 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially Pt And the like can be made difficult to alloy. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.6% or less. .
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · ₅ H ₂ O, or the like can be used as a raw material.

Incidentally, components of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

RO component (wherein R is selected from the group consisting of Mg, Ca, Sr, Ba) for Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K) 1 The ratio of seeds or more is preferably 0.30 or more. As a result, the partial dispersion ratio is reduced, and the desired refractive index and Abbe number are obtained. Therefore, the mass ratio RO / Rn ₂ O is preferably 0.30 or more, more preferably 0.40 or more, and more preferably 0.50 or more.
On the other hand, the mass ratio RO / Rn ₂ O is preferably 3.30 or less. As a result, the temperature coefficient of the relative refractive index can be reduced while suppressing an increase in the partial dispersion ratio. Preferably it is 3.30 or less, More preferably, it is 3.20 or less, More preferably, it is 3.10 or less, More preferably, it is 3.00 or less, More preferably, you may be 2.50 or less.

The BaO ratio to the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 2.50 or less. Thereby, glass with a small partial dispersion ratio can be obtained. Accordingly, the mass ratio BaO / Rn ₂ O is preferably 2.50 or less, more preferably 2.30 or less, more preferably 1.90 or less, and further preferably 1.60 or less.
On the other hand, when the mass ratio BaO / Rn ₂ O exceeds 0, the thermal expansion coefficient can be increased and the temperature coefficient of the relative refractive index can be decreased. Accordingly, the lower limit is preferably more than 0, more preferably 0.20 or more, and still more preferably 0.30 or more.

The ratio of BaO to Nb ₂ O ₅ is preferably 0.90 or less. Thereby, it has a desired refractive index and the devitrification property of glass can be reduced. Accordingly, the mass ratio BaO / Nb ₂ O ₅ is preferably 0.90 or less, more preferably 0.85 or less, and still more preferably 0.75 or less.
On the other hand, when the mass ratio BaO / Nb ₂ O ₅ is more than 0, the glass is stable and the partial dispersion ratio can be reduced. Accordingly, the lower limit is preferably more than 0, more preferably 0.05 or more, more preferably 0.10 or more, and still more preferably 0.30 or more.

The ratio of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) to Nb ₂ O ₅ is preferably 1.70 or less. Thereby, it has a desired refractive index and a partial dispersion ratio becomes small. Therefore, the mass ratio RO / Nb ₂ O ₅ is preferably 1.70 or less, more preferably 1.50 or less, and even more preferably 1.30 or less.
On the other hand, by setting the ratio of the mass ratio RO / Nb ₂ O ₅ to 0.10 or more, the temperature coefficient of the relative refractive index can be reduced, and the partial dispersion ratio is reduced. Therefore, it is preferably 0.10 or more, more preferably 0.30 or more, and further preferably 0.50 or more.

The ratio of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) to SiO ₂ and B ₂ O ₃ is preferably 0.10 or more. Thereby, the thermal expansion coefficient can be increased and the temperature coefficient of the relative refractive index can be decreased. Accordingly, the mass ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) is preferably 0.10 or more, more preferably 0.20 or more, and further preferably 0.30 or more.
On the other hand, the mass ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) is preferably 1.10 or less. Thereby, the glass is stabilized, and a desired refractive index and Abbe number can be obtained. Accordingly, the upper limit is preferably 1.00 or less, more preferably 0.90 or less.

The total content (mass sum) of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y and Yb) is preferably less than 13.0%. Thus, due to excessive content of Ln ₂ O ₃ component is suppressed and decline in devitrification of the refractive index of the glass. Therefore, the upper limit of the mass sum of the Ln ₂ O ₃ component is preferably less than 13.0%, more preferably 10.0% or less, and still more preferably 7.0% or less.

<About 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 preferably contained will be described.

  Other components can be added as necessary within the range not impairing the properties 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 independent of each other. Or, even when it is contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. .

Moreover, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with high environmental loads, it is desirable that they are not substantially contained, that is, not contained at all except for inevitable mixing.

  Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to be refrained from being used as a harmful chemical substance in recent years. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, 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 and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1000 to 1400 ° C. for 2 to 5 hours, stir to homogenize, blow out bubbles, etc., then lower the temperature to 950 to 1250 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention has a high refractive index and an Abbe number in a predetermined range.
The refractive index (n _d ) of the optical glass of the present invention is preferably 1.67 or more, more preferably 1.69 or more, and still more preferably 1.70 or more. The upper limit of the refractive index is preferably 1.90 or less, more preferably 1.85 or less, and more preferably 1.83 or less.
The Abbe number (ν _d ) of the optical glass of the present invention is preferably 25.0, more preferably 27.0, and still more preferably 29.0. On the other hand, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 40.0, more preferably 39.0, and further preferably 38.0.
The optical glass of the present invention having such a refractive index and Abbe number is useful in optical design, and the optical system can be miniaturized while achieving particularly high imaging characteristics. Can expand the degree.

Here, the optical glass of the present invention is a refractive index _{(n d)} and Abbe number ([nu _{d) is, (- 0.01 × ν d +2.03} ) ≦ n d ≦ (-0.01 × ν d +2 .13) is preferably satisfied. In the glass having the composition specified by the present invention, a stable glass can be obtained even if the refractive index (n _d ) and the Abbe number (ν _d ) satisfy this relationship.
Therefore, in the optical glass of the present invention, the refractive index (n _d ) and the Abbe number (ν _d ) preferably satisfy the relationship of n _d ≧ (−0.01 × ν _d +2.03), and n _d ≧ more preferably satisfies (-0.01 × ν _d +2.04) relationship, it is further preferable to satisfy the relation of _{n d ≧ (-0.01 × ν d} +2.05).
On the other hand, in the optical glass of the present invention, the refractive index (n) and the Abbe number (ν _d ) preferably satisfy the relationship of n _d ≦ (−0.01 × ν _d +2.13), and n _d ≦ more preferably satisfies (-0.01 × ν _d +2.12) relationship, it is further preferable to satisfy the relation of _{n d ≦ (-0.01 × ν d} +2.11).

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 (−0.008 × ν _d +0.828) ≦ (θg, F) with the Abbe number (ν _d ). ) ≦ (−0.008 × ν _d +0.876).
Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) preferably satisfy the relationship θg, F ≧ (−0.008 × ν _d +0.828). It is more preferable to satisfy the relationship of θg, F ≧ (−0.008 × ν _d +0831), and it is more preferable to satisfy the relationship of θg, F ≧ (−0.008 × ν _d +0.834).
On the other hand, 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 θg, F ≦ (−0.008 × ν _d +0.876). , Θg, F ≦ (−0.008 × ν _d +0.873) is more preferable, and it is more preferable to satisfy the relationship θg, F ≦ (−0.008 × ν _d +0.870). .
As a result, an optical glass having a low partial dispersion ratio (θg, F) can be obtained. Therefore, an optical element formed from the optical glass can be used to reduce chromatic aberration of the optical system.

In particular, in the region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of a general glass is higher than that of the normal line, the Abbe number (ν _d ) on the horizontal axis and the vertical axis on the vertical axis. When the partial dispersion ratio (θg, F) is taken, the relationship between the general glass partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is expressed by a curve having a larger slope than the normal line. . In the relational expression of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) described above, by defining these relations using a straight line having a larger slope than the normal line, partial dispersion can be achieved as compared with general glass. This indicates that a glass having a small ratio (θg, F) can be obtained.

The optical glass of the present invention has a low temperature coefficient (dn / dT) of relative refractive index.
More specifically, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably + 6.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably + 5.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably. + 4.0 × 10 ⁻⁶ ° C. ⁻¹ is the upper limit, and this upper limit or a lower value (minus side) can be taken.
On the other hand, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably −2.0 × 10 ⁻⁶ ° C.− ¹ , more preferably −1.0 × 10 ⁻⁶ ° C. ⁻¹ , and further preferably −. 0.5 × 10 ⁻⁶ ° C. ⁻¹ is set as the lower limit value, and this lower limit value or a value higher than that (plus side) can be taken.
Of these, many glasses having a low refractive index temperature coefficient are present as glass having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 25 or more and 40 or less. Therefore, it is possible to expand the options for correction such as image formation deviation due to temperature change, and to make the correction easier. Accordingly, by setting the temperature coefficient of the relative refractive index in such a range, it is possible to contribute to correction of image formation deviation due to a temperature change.
The temperature coefficient of the relative refractive index of the optical glass of the present invention is the temperature coefficient of the refractive index (589.29 nm) in air at the same temperature as the optical glass, and when the temperature is changed from 40 ° C. to 60 ° C. Of change per 1 ° C. (° C. ⁻¹ ).

In the optical glass of the present invention, the average linear thermal expansion coefficient α at 100 to 300 ° C is preferably 80 ( ^10-7 ° C- ¹ ) or more. That is, the average linear thermal expansion coefficient α at 100 to 300 ° C. of the optical glass of the present invention is preferably 80 (10 ⁻⁷ ° C.− ¹ ) or more, more preferably 85 (10 ⁻⁷ ° C. ⁻¹ ) or more, more preferably. ^{Has a} lower limit of 90 (10 ⁻⁷ ° C. ⁻¹ ) or more, more preferably 95 (10 ⁻⁷ ° C. ⁻¹ ) or more.
In general, if the average linear thermal expansion coefficient α is large, cracks are likely to occur when glass is processed. Therefore, it is desirable that the average linear thermal expansion coefficient α is small. On the other hand, in terms of joining in combination with a glass material having a low relative refractive index temperature coefficient and a large average linear thermal expansion coefficient α, the glass material and the average linear thermal expansion coefficient α are the same or approximate. It is desirable.
Among these, in a glass having a refractive index (n _d ) of 1.67 or more and an Abbe number (ν _d ) of 25 or more and 40 or less, there are few glass materials having a large average linear thermal expansion coefficient α, and a low refractive index. When used in combination with a low dispersion glass material, it is more useful that the average linear thermal expansion coefficient α has a large value as in the present invention.

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

  The glass molded body 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, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

Composition of Examples (No. 1 to No. 15) and Comparative Example A of the present invention, as well as refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), relative refractive index Tables 1 and 2 show the results of temperature coefficient (dn / dT) and average linear thermal expansion coefficient (100 to 300 ° C.). The following examples are merely for illustrative purposes and are not limited to these examples.

  The glasses of Examples and Comparative Examples are high-purity materials used in ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds corresponding to the raw materials of the respective components. After selecting the raw materials, weighing them so as to have the composition ratios of the examples and comparative examples shown in the table and mixing them uniformly, stone crucibles (platinum crucibles and alumina crucibles depending on the melting property of the glass) And then melted in an electric furnace at a temperature range of 1100 to 1400 ° C. for 0.5 to 5 hours according to the degree of melting difficulty of the glass composition, then transferred to a platinum crucible and stirred and homogenized to remove bubbles. Then, the temperature was lowered to 1000 to 1200 ° C., homogenized with stirring, cast into a mold, and slowly cooled to produce glass.

The refractive index (n _d ) and Abbe number (ν _d ) of the glass of the example and the comparative example are shown as measured values with respect to the d-line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is a value of the refractive index of the d-line, a refractive index (nF) for the F-line (486.13 nm) of the hydrogen lamp, and a refractive index (nC) for the C-line (656.27 nm). Was calculated from the equation of Abbe number (ν _d ) = [(n _d −1) / (nF−nC)].
Then, in the measured Abbe number (ν _d ), from the difference between the value of the partial dispersion ratio (θg, F) on the normal line in FIG. 1 and the value of the measured partial dispersion ratio (θg, F), Anomalous dispersibility (Δθg, F) was determined.

  The temperature coefficient (dn / dT) of the relative refractive index of the glass of Examples and Comparative Examples is a method described in Japan Optical Glass Industry Association Standard JOGIS18-2008 “Measurement Method of Temperature Index of Refractive Index of Optical Glass” The value of the temperature coefficient of the relative refractive index at 40 to 60 ° C. for light having a wavelength of 589.29 nm was measured by the interferometry.

Moreover, the average linear thermal expansion coefficient (100-300 degreeC) of the glass of an Example and a comparative example is temperature and elongation of a sample according to Japan Optical Glass Industry Association standard JOGIS08-2003 "Measurement method of thermal expansion of optical glass". From the thermal expansion curve obtained by measuring the relationship of.

Each of the optical glasses of the examples of the present invention has a refractive index (n _d ) of 1.67 or more, more specifically 1.70 or more, and this refractive index (n _d ) is 1.90 or less. More specifically, it was 1.88 or less, which was within the desired range.
The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 25 or more, more specifically 29 or more, and the Abbe number (ν _d ) of 40 or less. Was 38 or less, and was within the desired range.

As shown in these tables, the optical glass of the example of the present invention has a partial dispersion ratio (θg, F) and an Abbe number (ν _d ) of (−0.008 × ν _d +0.828) ≦ (θg, F ) ≦ (−0.008 × ν _d +0.876), and more specifically, (−0.008 × ν _d +0.834) ≦ (θg, F) ≦ (−0.008 × ν _d +0.870). That is, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the example of the present application is as shown in FIG.
On the other hand, the optical glass of the comparative example did not satisfy the relationship of (−0.008 × ν _d +0.828) ≦ (θg, F) ≦ (−0.008 × ν _d +0.876).

In addition, the optical glass of the example of the present invention has a refractive index (n _d ) and an Abbe number (ν _d ) of (−0.01 × ν _d +2.03) ≦ n _d ≦ (−0.01 × ν _d +2.13), and more specifically, (−0.01 × ν _d +2.05) ≦ n _d ≦ (−0.01 × ν _d +2.11). It was. That is, the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) of the glass of the example of the present application is as shown in FIG.
On the other hand, the optical glass of the comparative example, - did not satisfy the relation of _{(0.01 × ν d +2.03) ≦} n d ≦ (-0.01 × ν d +2.13).

As shown in the table, the optical glasses of the examples all have a temperature coefficient of relative refractive index in the range of + 6.0 × 10 ⁻⁶ to −0.5 × 10 ⁻⁶ (° C. ⁻¹ ). Was within the desired range.

In addition, the optical glass of the present invention had an average linear thermal expansion coefficient α at 100 to 300 ° C. of 80 (10 ⁻⁷ ° C. ⁻¹ ) or more.

  Furthermore, a glass block was formed using the optical glass of the example of the present invention, and this 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 into various lens and prism shapes.

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

Claims (6)

% By mass
SiO ₂ component 10.0-35.0%,
Nb ₂ O ₅ component 10.0-35.0%
Na ₂ O component more than 0 to 15.0%,
BaO component more than 0 to 20.0%,
Rn ₂ O component more than 5.0 to 30.0%
RO component 5.0 to 30.0% contained,
Between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ),
The relationship of (−0.008 × ν _d +0.828) ≦ (θg, F) ≦ (−0.008 × ν _d +0.876) is satisfied,
An optical glass having a temperature coefficient (40 to 60 ° C.) of a relative refractive index (589.29 nm) within a range of + 6.0 × 10 ⁻⁶ to −2.0 × 10 ⁻⁶ (° C. ⁻¹ ) R is one or more selected from the group consisting of Mg, Ca, Sr and Ba, and Rn is one or more selected from the group consisting of Li, Na and K). The optical glass according to claim 1, wherein the mass ratio (BaO / Rn ₂ O) is 0.30 or more (wherein Rn is one or more selected from the group consisting of Li, Na, and K). . Refractive index _{(n d)} and Abbe number ([nu _{d) is, (- 0.01 × ν d +2.03} ) satisfies the relationship of _{≦ n d ≦ (-0.01 × ν} d +2.13) according to claim 1 Or the optical glass of 2. A preform material comprising the optical glass according to claim 1. An optical element made of the optical glass according to claim 1. An optical apparatus comprising the optical element according to claim 5.

Images