CN110691760A - Glass, optical glass and optical element - Google Patents

Abstract

The invention provides glass, optical glass and an optical element which have good hot-press formability and are suitable for secondary chromatic aberration correction. The solution is a silicate glass, the Abbe number vd of which is 20-35, and which contains P₂O₅And Nb₂O₅And the relative partial dispersion Pg, F satisfies the formula (1-1): pg, F is less than or equal to-0.00286 x ν d +0.68900 (1-1).

Description

Glass, Optical Glass and Optical Components

technical field

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

In the design of an optical system, an optical glass with a high refractive index and high dispersibility corrects chromatic aberration and has high utility value in making the optical system highly functional and compact.

Such glass will be described below according to the aspects of the first invention, the second invention, the third invention, and the fourth invention.

In addition, in this invention and this specification, unless otherwise stated, the glass composition is shown on the oxide basis. Here, the "glass composition based on oxides" refers to the glass composition obtained by converting all the glass raw materials during melting to those that exist in the form of oxides in the glass, and the expressions of the respective glass components are described according to conventions. For SiO ₂ , TiO ₂ and so on. Unless otherwise specified, the content and total content of the glass components are based on mass, and "%" means "mass %".

The content of the glass component can be quantified by a known method, for example, inductively coupled plasma optical emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). In addition, in this specification and this invention, content of a structural component is 0%, and it means that this structural component is not substantially contained, and it is permissible to contain this component at the level of an unavoidable impurity.

In this specification, unless otherwise specified, the refractive index refers to the refractive index nd of helium in d rays (wavelength: 587.56 nm).

The Abbe number νd is used as a value representing a property related to dispersion, and is represented by the following formula. Here, nF is the refractive index of blue hydrogen under F rays (wavelength 486.13 nm), and nC is the refractive index of red hydrogen under C rays (656.27 nm).

νd=(nd-1)/(nF-nC)

"First Invention"

[Background Art of the First Invention]

As a manufacturing method of the optical glass used for an optical system, the reheat pressing method of reheating and shaping|molding glass is mentioned. In this production method, the silicate-based high-refractive-index and high-dispersity optical glass tends to undergo phase separation upon reheating. When phase separation occurs, the fluidity of the glass during reheating deteriorates, and it may be difficult to shape into a desired shape. In addition, this phase separation causes internal defects (for example, bright spots, cracks, streaks, etc.) to reflected light in optical elements such as lenses. Therefore, in the reheat pressing method, a silicate-based high-refractive-index and high-dispersity optical glass capable of suppressing the occurrence of internal defects and forming into a desired shape, that is, good reheat press formability is required.

In addition, in the design of the optical system, the primary chromatic aberration correction can be performed by combining two types of glasses having different Abbe numbers. The glass used for the secondary chromatic aberration correction is selected in consideration of the relative partial dispersion in addition to the Abbe number. Especially in the optical glass with high refractive index and high dispersion, the optical glass with small relative partial dispersion is suitable for secondary chromatic aberration correction.

Patent Documents 1-1 to 1-5 disclose silicate-based high-refractive-index and high-dispersity optical glasses. However, from the viewpoints of Abbe number and relative partial dispersion, further improvement of the secondary chromatic aberration correction is required for any glass.

[Prior Art Document of the First Invention]

Patent Literature

Patent Document 1-1: Japanese Patent Laid-Open No. 2001-342035

Patent Document 1-2: Japanese Patent Laid-Open No. 2012-206894

Patent Documents 1-3: Japanese Patent Laid-Open No. 2014-201476

Patent Documents 1-4: Japanese Patent Laid-Open No. 60-21828

Patent Documents 1-5: Japanese Patent Laid-Open No. 59-8637

[Content of the first invention]

[Problems to be solved by the first invention]

The first invention was made in view of such a situation, and an object thereof is to provide a glass, an optical glass, and an optical element suitable for secondary chromatic aberration correction with good reheat press formability.

[way of solving the problem]

The gist of the first invention is as follows.

[1] A silicate glass whose Abbe number νd is 20 to 35,

Contains P ₂ O ₅ and Nb ₂ O ₅ ,

And the relative partial dispersion Pg,F satisfies the following formula (1-1):

Pg,F≤-0.00286×νd+0.68900...(1-1).

[2] A silicate glass whose Abbe number νd is 20 to 35,

Contains P ₂ O ₅ and Nb ₂ O ₅ ,

And the mass ratio of the content of Nb ₂ O ₅ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is greater than 0.6110.

[3] An optical glass comprising the glass according to the above [1] or [2].

[4] An optical element formed of the optical glass according to the above [3].

[Effect of the first invention]

According to the first invention, it is possible to provide a glass, an optical glass, and an optical element which have good reheat press formability and are suitable for secondary chromatic aberration correction.

[Specific embodiment of the first invention]

Hereinafter, the glass of the embodiment of the first invention will be described in detail. First, glass will be described from the viewpoint of relative partial dispersion Pg,F as 1-1 embodiment, and next, glass will be described from the viewpoint of mass ratio of glass components as 1-2 embodiment. Furthermore, Embodiment A, Embodiment B, and Embodiment C will be described as other embodiments.

Embodiment 1-1

The glass of the 1-1 embodiment is a silicate glass having an Abbe number νd of 20 to 35,

Contains P ₂ O ₅ and Nb ₂ O ₅ ,

And the relative partial dispersion Pg,F satisfies the following formula (1-1),

Pg,F≤-0.00286×νd+0.68900...(1-1).

The glass of the 1-1 embodiment is a silicate glass mainly containing SiO ₂ as a network-forming component of the glass. The content of SiO ₂ is preferably more than 0%, and the lower limit thereof is more preferably in the order of 1%, 5%, 10%, 15%, 20%, and 25%. In addition, the upper limit of the content of SiO ₂ is preferably 60%, and more preferably in the order of 50%, 40%, 39%, 38%, 37%, 36%, and 35%.

As a network-forming component of glass, SiO ₂ has the functions of improving thermal stability, chemical durability, weather resistance of glass, increasing the viscosity of molten glass, and making molten glass easy to form. On the other hand, when the content of SiO ₂ is large, the devitrification resistance of the glass tends to decrease, and Pg and F increase. Therefore, it is preferable to make content of _SiO2 into the said range.

The glass of the 1-1 embodiment contains P ₂ O ₅ . The lower limit of the content of P ₂ O ₅ is preferably 0.1%, and more preferably in the order of 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, and 1.9%. In addition, the upper limit of the content of P ₂ O ₅ is preferably 10%, and more preferably in the order of 7%, 5%, and 3%.

By making the lower limit of the content of P ₂ O ₅ satisfy the above range, the reheat press formability can be improved. Moreover, by making the upper limit of content of _{P2O5 satisfy} the said range, the increase of relative partial dispersion Pg,F can be suppressed, the thermal stability of glass can be maintained, and reheat press formability can be improved.

The glass of the 1-1 embodiment contains Nb ₂ O ₅ . The lower limit of the content of Nb ₂ O ₅ may be 1%, and further may be 10%, 20%, 24%, 25%, 30%, 35%, 40%, or 43%. In addition, the upper limit of the content of Nb ₂ O ₅ is preferably 80%, and more preferably in the order of 60%, 55%, 50%, and 45%.

By making the lower limit of the content of Nb ₂ O ₅ satisfy the above-mentioned range, a glass with a high refractive index and high dispersibility in which the partial dispersion Pg,F is reduced can be obtained. In addition, Nb ₂ O ₅ is also a glass component that improves thermal stability and chemical durability of glass. Therefore, when the upper limit of the content of Nb ₂ O ₅ satisfies the above-mentioned range, the thermal stability and chemical durability of the glass can be favorably maintained, and the reheat press formability can be improved.

In the glass of 1-1 Embodiment, Abbe's number νd is 20-35. The Abbe's number νd may be 22-33, 23-31, 23-27, or 23-26.

By making Abbe's number νd in the above-mentioned range, a highly dispersive glass can be obtained.

The Abbe number νd can be controlled by adjusting the contents of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ as glass components contributing to high dispersion.

In the glass of the 1-1 embodiment, the relative partial dispersion Pg,F satisfies the following formula (1-2). The relative partial dispersion Pg,F preferably satisfies the following formula (1-3), more preferably the following formula (1-4), and further preferably the following formula (1-5). By making the relative partial dispersion Pg,F satisfy the following formula, an optical glass suitable for secondary chromatic aberration correction can be provided.

Pg,F≤-0.00286×νd+0.68900...(1-2)

Pg,F≤-0.00286×νd+0.68800...(1-3)

Pg,F≤-0.00286×νd+0.68600...(1-4)

Pg,F≤-0.00286×νd+0.68400...(1-5)

The relative partial dispersion Pg,F can be represented by the following formula (1-6) using the respective refractive indices ng, nF, and nC in g-rays, F-rays, and C-rays.

Pg,F=(ng-nF)/(nF-nC)...(1-6)

The relative partial dispersion Pg,F was adjusted by adjusting the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )], the mass ratio described later [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [(SiO ₂ +P ₂ O ₅ + B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [ZrO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], Mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )], mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] , mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)] to control.

(glass composition)

Hereinafter, the content and ratio of the glass components other than the above in the 1-1 embodiment of the first invention will be described in detail.

In the glass of the 1-1 embodiment, the content of B ₂ O ₃ is preferably 20% or less, and more preferably 10% or less, 5% or less, 3% or less, and 1% or less in this order. The content of B ₂ O ₃ may also be 0%.

B ₂ O ₃ is a network-forming component of glass, and has the effect of improving the thermal stability of glass. _On the other hand, when there is much content _of B2O3, there exists a possibility that the volatilization amount of a glass component may increase at the time of glass melting. In addition, there is a tendency that high dispersion is hindered and devitrification resistance is lowered. Therefore, the content of B ₂ O ₃ is preferably within the above range.

In the glass of the 1-1 embodiment, the content of Al ₂ O ₃ is preferably 20% or less, and more preferably 10% or less, 5% or less, and 3% or less in this order. The content of Al ₂ O ₃ may also be 0%.

Al ₂ O ₃ is a glass component that has the effect of improving the chemical durability and weather resistance of glass, and can be considered as a network-forming component. On the other hand, when the content of Al ₂ O ₃ increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability tend to occur. From the viewpoint of avoiding such a problem, the content of Al ₂ O ₃ is preferably within the above range.

In the glass of the 1-1st embodiment, the lower limit of the total content of SiO ₂ and P ₂ O ₅ [SiO ₂ +P ₂ O ₅ ] is preferably 5%, and more preferably 10%, 15%, 17%, and 19% , the order of 21% is more preferred. In addition, the upper limit of the total content [SiO ₂ +P ₂ O ₅ ] is preferably 50%, and more preferably in the order of 40%, 37%, 35%, 33%, 31%, 29%, and 27%.

When the lower limit of the total content of SiO ₂ and P ₂ O ₅ [SiO ₂ +P ₂ O ₅ ] satisfies the above conditions, the reheat press formability can be improved. In addition, by making the upper limit of the total content [SiO ₂ +P ₂ O ₅ ] satisfy the above conditions, the increase in relative partial dispersion Pg,F can be suppressed, and the thermal stability of the glass can be maintained.

In the glass of the 1-1 embodiment, the lower limit of the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ [SiO ₂ +P ₂ O ₅ +B ₂ O ₃ ] is preferably 5%, and more preferably 10%. The order of %, 15%, 17%, 19%, 21% is more preferable. In addition, the upper limit of the total content [SiO ₂ +P ₂ O ₅ +B ₂ O ₃ ] is preferably 50%, and further increased in the order of 40%, 37%, 35%, 33%, 31%, 29%, and 27% Preferred.

SiO ₂ , P ₂ O ₅ and B ₂ O ₃ are network-forming components of glass, and mainly improve the thermal stability and devitrification resistance of glass. It has the function of increasing the viscosity of the molten glass and making it easy to form the molten glass. Therefore, the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ is preferably within the above range.

Moreover, in the glass of the 1-1st embodiment, the mass ratio of the content of P ₂ O ₅ to the total content of SiO ₂ and P ₂ O ₅ [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] The lower limit of is preferably 0.001, more preferably in the order of 0.005, 0.010, 0.020, 0.030, 0.040, 0.050, 0.060, and 0.070. In addition, the upper limit of the mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] is preferably 0.910, and more preferably in the order of 0.700, 0.500, 0.300, 0.200, 0.150, and 0.100.

When the mass ratio of the content of P ₂ O ₅ to the total content of SiO ₂ and P ₂ O ₅ [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] is too low, the reheat press formability is deteriorated, and excessive When it is high, the relative partial dispersion Pg,F increases. Therefore, the mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] is preferably within the above range.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the content of P ₂ O ₅ to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ [P ₂ O ₅ /(SiO ₂ +P The lower limit of ₂ O ₅ +B ₂ O ₃ )] is preferably 0.001, more preferably in the order of 0.005, 0.010, 0.020, 0.030.0.040, 0.050, 0.060, and 0.070. In addition, the upper limit of the mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )] is preferably 0.910, and more preferably in the order of 0.700, 0.500, 0.300, 0.200, 0.150, and 0.100.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the content of SiO ₂ to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ [SiO ₂ /(SiO ₂ +P ₂ O ₅ + The lower limit of B ₂ O ₃ )] is preferably 0.100, and more preferably in the order of 0.300, 0.500, 0.600, 0.700, and 0.800. In addition, the upper limit of the mass ratio [SiO ₂ /(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )] is preferably 1.000, and more preferably in the order of 0.999, 0.990, 0.980, 0.970, 0.960, 0.950, 0.940, and 0.930 .

In the glass of the 1-1 embodiment, the lower limit of the content of ZrO ₂ is preferably 0%, more preferably more than 0%, and further more in the order of 1%, 2%, 3%, 4%, 5%, and 6% Preferred. In addition, the upper limit of the content of ZrO ₂ is preferably 15%, more preferably 13%, 11%, 10%, 9%, and 8% in this order.

By making the lower limit of the content of ZrO ₂ satisfy the above-mentioned range, glass with high refractive index and high dispersibility can be obtained. Further, by making the upper limit of the content of ZrO ₂ to satisfy the above range, the relative partial dispersion Pg,F can be reduced and the occurrence of defects as optical elements can be suppressed, and the meltability and thermal stability of the glass can be maintained.

In the glass of the 1-1 embodiment, the lower limit of the content of TiO ₂ is preferably 0%, and more preferably in the order of 1%, 2%, 3%, and 4%. In addition, the upper limit of the content of TiO ₂ is preferably 20%, and more preferably in the order of 15%, 13%, 11%, 9%, 7%, 6%, and 5%.

TiO ₂ is a component that contributes to high dispersion, improves glass stability, and improves reheat press formability. On the other hand, when TiO ₂ is introduced excessively, the relative partial dispersion Pg,F increases. Therefore, the content of TiO ₂ is preferably within the above range. It should be noted that TiO ₂ and Nb ₂ O ₅ can be substituted for each other, and when substituted with Nb ₂ O ₅ , the relative partial dispersion Pg,F can be reduced.

In the glass of the 1-1st embodiment, the lower limit of the total content of Nb ₂ O ₅ and TiO ₂ [Nb ₂ O ₅ +TiO ₂ ] may be 10%, and further may be 20%, 25%, 30%, 35% %, 40%, or 45%. In addition, the upper limit of the total content [Nb ₂ O ₅ +TiO ₂ ] is preferably 80%, and more preferably in the order of 70%, 65%, 60%, and 55%.

Nb ₂ O ₅ and TiO ₂ are components that contribute to high refractive index and high dispersion. Therefore, in order to obtain a glass having a desired Abbe number νd, it is preferable that the total content of Nb ₂ O ₅ and TiO ₂ is in the above-mentioned range.

In the glass of the 1-1st embodiment, the lower limit of the mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] of the content of P ₂ O ₅ to the content of Nb ₂ O ₅ is preferably 0.001, and more preferably 0.005, 0.010 , 0.015, 0.020, 0.025, 0.030, 0.035, 0.040 in the order of more preferable. In addition, the upper limit of the mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] is preferably 0.125, and more preferably in the order of 0.120, 0.100, 0.090, 0.080, 0.070, 0.060, and 0.050.

Nb ₂ O ₅ is a component that contributes to high dispersion, but tends to cause deterioration of reheat press formability. On the other hand, P ₂ O ₅ can improve reheat press formability. Therefore, from the viewpoint of reheat press formability, the mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] is preferably within the above range.

The lower limit of the mass ratio [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] of the content of P ₂ O ₅ to the total content of Nb ₂ O ₅ and TiO ₂ in the glass of the first embodiment It is preferably 0.001, and more preferably in the order of 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035. In addition, the upper limit of the mass ratio [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.125, and more preferably in the order of 0.120, 0.100, 0.090, 0.080, 0.070, 0.060, and 0.050.

Nb ₂ O ₅ and TiO ₂ are components that contribute to high dispersion, but tend to cause deterioration in reheat press formability. On the other hand, P ₂ O ₅ can improve reheat press formability. Therefore, from the viewpoint of reheat press formability, the mass ratio [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] is preferably within the above range.

In the glass of the 1-1 embodiment, the lower limit of the content of WO ₃ is preferably 0%, and may be 1%, 3%, or 5%. In addition, the upper limit of the content of WO ₃ is preferably 20%, and more preferably in the order of 15%, 10%, and 5%.

WO ₃ is a component that improves glass stability and reheat press formability. On the other hand, WO ₃ increases the relative partial dispersion Pg,F and increases the specific gravity. In addition, it is easy to cause coloration of glass and deteriorate the transmittance. Therefore, the content of WO ₃ is preferably within the above range.

In Embodiment 1-1, the upper limit of the content of Bi ₂ O ₃ is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of Bi ₂ O ₃ is preferably 0%.

Bi ₂ O ₃ has an effect of improving the thermal stability of glass by containing it in an appropriate amount. On the other hand, when the content of Bi ₂ O ₃ is increased, the relative partial dispersion Pg,F increases, and the specific gravity also increases. In addition, the coloring of the glass increases. Therefore, the content of Bi ₂ O ₃ is preferably within the above range.

In the glass of Embodiment 1-1, the upper limit of the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] can be set It is 80%, and may further be 70%, 60%, or 55%. In addition, the lower limit of the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] may be set to 10%, and further may be set to 20%, 25%, 30%, 35%, 40%, or 45%.

TiO ₂ , WO ₃ and Bi ₂ O ₃ are components that contribute to high refractive index and high dispersion together with Nb ₂ O ₅ . Therefore, the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] is preferably in the above range.

Moreover, in the glass of the 1-1 embodiment, from the viewpoint of obtaining the desired relative partial dispersion Pg,F, the content of Nb ₂ O ₅ is relative to Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The upper limit of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] of the total content of the 0.910. The lower limit of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.100, more preferably 0.200, 0.300, 0.400, 0.500, 0.600, 0.6110, The order of 0.855 is more preferred.

Moreover, in the glass of the 1-1st embodiment, the mass ratio of the content of ZrO ₂ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [ZrO ₂ /(Nb ₂ O ₅ + The upper limit of TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 1.000, and more preferably in the order of 0.800, 0.600, 0.400, 0.300, 0.250, and 0.200. In addition, the lower limit of the mass ratio [ZrO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0, and more preferably in the order of 0.001, 0.005, 0.007, and 0.010.

Moreover, in the glass of the 1-1 embodiment, the mass of the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ relative to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The upper limit of the ratio [(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] may be set to 5.000, and further may be set to 3.000 and 2.000 , 1.500, 1.000, or 0.900. In addition, the lower limit of the mass ratio [(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] may be set to 0.013, and may be further set to 0.100, 0.200, 0.300, 0.350, or 0.400.

By setting the mass ratio _[ ( _SiO2 + _{P2O5 +} B2O3 ₎ / _{( Nb2O5} + _{TiO2 +} WO3+ _{Bi2O3 )} ] to the above range, the Abbe number νd and Relative partial dispersion Pg,F.

In the glass of the 1-1 embodiment, the upper limit of the content of Li ₂ O may be 10%, and further may be 9%, 7%, 5%, or 3%. The lower limit of the content of Li ₂ O may be 0%, and further may be 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, or 4.0%.

In the glass of the 1-1 embodiment, the upper limit of the content of Na ₂ O may be 30%, and further may be 20%, 15%, 10%, 8%, 6%, 5%, or 4% . The lower limit of the content of Na ₂ O may be 0%, and further may be 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 7.0%, 9.0%, 11.0%, or 12.0%.

In the glass of the 1-1 embodiment, the upper limit of the content of K ₂ O may be set to 30%, and further may be set to 25%, 20%, 17%, 15%, 13%, 11%, 9%, 7%, 5%, 3%, or 1%. The lower limit of the content of K ₂ O may be set to 0%, and further may be set to 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, 5.0%, 7.0%, 9.0%, 11.0%, or 13.0% %.

Li ₂ O, Na ₂ O, and K ₂ O all have the effect of lowering the liquidus temperature and improving the thermal stability of the glass, but when the content of these increases, chemical durability and weather resistance decrease. Therefore, each content of Li ₂ O, Na ₂ O, and K ₂ O is preferably within the above range.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the content of Li ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O/(Li ₂ O+Na ₂ O The upper limit of +K ₂ O)] may be set to 1.000, and further may be set to 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. In addition, the lower limit of the mass ratio [Li ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] may be set to 0.000, and further may be set to 0.100, 0.200, 0.300, 0.500, or 0.700.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the content of Na ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O The upper limit of +K ₂ O)] may be set to 1.000, and further may be set to 0.970, 0.960, 0.950, 0.900, 0.850, 0.800, 0.750, 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. In addition, the lower limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] may be set to 0.000, and further may be set to 0.100, 0.200, 0.300, 0.330, 0.340, 0.350, 0.360, 0.370 , 0.450, 0.460, 0.470, 0.480, 0.490, 0.500, or 0.700.

Moreover, in the glass of the 1-1st embodiment, the mass ratio of the content of K ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [K ₂ O/(Li ₂ O+Na ₂ O The upper limit of +K ₂ O)] may be set to 1.000, and further may be set to 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. The lower limit of the mass ratio [K ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] may be set to 0.000, and further may be set to 0.100, 0.200, 0.300, 0.500, or 0.700.

In the glass of the 1-1 embodiment, the upper limit of the content of Cs ₂ O is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. The lower limit of the content of Cs ₂ O is preferably 0%.

Cs ₂ O has the effect of improving the thermal stability of glass, but when the content thereof increases, chemical durability and weather resistance decrease. Therefore, it is preferable that each content of _Cs2O is the said range.

In the glass of the 1-1 embodiment, the lower limit of the total content of alkali metal oxides is preferably 1%, and the lower limit is further increased in the order of 3%, 5%, 7%, 9%, 11%, 13%, and 15%. Preferred. In addition, the upper limit of the total content of the alkali metal oxides is preferably 40%, and more preferably in the order of 35%, 30%, 25%, and 20%.

The alkali metal oxide is preferably one or more oxides selected from the group consisting of Li ₂ O, Na ₂ O, K ₂ O, and Cs ₂ O. In addition, each alkali metal may be substituted.

By making the lower limit of the total content of alkali metal oxides satisfy the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature can be lowered. Moreover, by making the upper limit of the total content of alkali metal oxide satisfy|fill the said range, generation|occurrence|production of the defect as an optical element can be suppressed.

Moreover, in the glass of the 1-1st embodiment, the lower limit of the total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O+Na ₂ O+K ₂ O] is preferably 1%, and more preferably more than 1.1%, more preferably in the order of 3%, 5%, 7%, 9%, 10%, 11%, 13%, and 15%. In addition, the upper limit of the total content [Li ₂ O+Na ₂ O+K ₂ O] is preferably 40%, and more preferably 35%, 30%, 25%, 22.0%, 21.7%, 21.4%, 21.1%, 20% The order is more preferred.

Furthermore, in the glass of the first-1 embodiment, the content of P ₂ O ₅ relative to Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ The upper limit of the mass ratio of the total content of O ₃ [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] It is preferably 1.000, more preferably 0.500, 0.300, and 0.100 in the order. In addition, the lower limit of the mass ratio [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.001, More preferably, the order is 0.003, 0.005, 0.007, 0.009, 0.011, 0.013, 0.015, 0.017, 0.019, 0.021.

Desired Abbe number νd and relative partial dispersion can be obtained by appropriately introducing Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ as glass components Pg, F. However, if these components are introduced into the silicate glass, there is a possibility that the reheat press formability will be deteriorated. _On the other hand, _P2O5 is a component which improves reheat press formability. Therefore, when the mass ratio [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is too high, the presence of glass There is a possibility that the stability of Pg will deteriorate and the relative partial dispersion Pg and F will increase. In addition, if it is too low, there is a possibility that the reheat press formability will deteriorate. Therefore, the mass ratio [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably within the above range.

Moreover, in the glass of the 1-1 embodiment, the mass of the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O with respect to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ The upper limit of the ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )] is preferably 5.000, more preferably 3.000, 2.000, 1.500, 1.300 , 1.100, 1.000, 0.900 in the order of more preferable. In addition, the lower limit of the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )] is preferably 0.020, and more preferably 0.100, 0.200, The order of 0.300, 0.400, and 0.500 is more preferable.

When the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )] is too low, the solubility deteriorates and the relative partial dispersion Pg , There is a risk that F will rise, and if it is too high, there is a risk that the glass stability will decrease and the reheat press formability will deteriorate.

Moreover, in the glass of the 1-1 embodiment, the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O is relative to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The upper limit of the mass ratio of the content [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 4.000, and more preferably 3.000 , 2.000, 1.000, 0.900, 0.700, 0.500 in the order of more preferable. In addition, the lower limit of the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.015, more preferably 0.050 , 0.100, 0.150, 0.200, 0.250 in the order of more preferable.

When the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is too low, there will be relative partial dispersion Pg,F There is a risk of rise and transmittance deterioration, and if it is too high, there is a risk that the glass stability will be lowered and the reheat press formability will be deteriorated.

In the glass of the 1-1 embodiment, the upper limit of the content of MgO is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of MgO is preferably 0%.

In the glass of the 1-1 embodiment, the upper limit of the content of CaO is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of CaO is preferably 0%.

In the glass of the 1-1 embodiment, the upper limit of the content of SrO is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of SrO is preferably 0%.

In the glass of the 1-1 embodiment, the upper limit of the content of BaO is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of BaO is preferably 0%.

MgO, CaO, SrO, and BaO are all glass components having the effect of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, the specific gravity increases, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass decrease. Therefore, it is preferable that each content of these glass components is the said range, respectively.

In the glass of the 1-1 embodiment, the upper limit of the content of ZnO is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of ZnO is preferably 0%.

ZnO is a glass component that has the effect of improving the thermal stability of glass. However, when the content of ZnO is too large, the specific gravity increases. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining desired optical properties, the content of ZnO is preferably within the above range.

In the glass of the 1-1 embodiment, the upper limit of the total content [MgO+CaO] of MgO and CaO is preferably 20%, and more preferably 10%, 5%, and 3% in the order. In addition, the lower limit of the total content [MgO+CaO] is preferably 0%. The total content [MgO+CaO] may also be 0%. The total content [MgO+CaO] is preferably within the above-mentioned range from the viewpoint of not preventing high dispersion and maintaining thermal stability.

Moreover, in the glass of the 1st-1st embodiment, the upper limit of the total content of MgO, CaO, SrO, BaO and ZnO [MgO+CaO+SrO+BaO+ZnO] is preferably 20%, more preferably 10%, 5% , the order of 3% is more preferable. In addition, the lower limit of the total content [MgO+CaO+SrO+BaO+ZnO] is preferably 0%. The total content [MgO+CaO+SrO+BaO+ZnO] may also be 0%. The total content [MgO+CaO+SrO+BaO+ZnO] is preferably within the above-mentioned range from the viewpoints of suppressing an increase in specific gravity, not hindering high dispersion, and maintaining thermal stability.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O [( The upper limit of MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)] is preferably 20.000, more preferably in the order of 10.000, 5.000, 3.000, 1.000, 0.500 . In addition, the lower limit of the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)] is preferably 0.000. The lower limit of the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)] may be 0.000.

In the glass of the 1-1 embodiment, the upper limit of the content of La ₂ O ₃ is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of La ₂ O ₃ is preferably 0%.

When the content of La ₂ O ₃ increases, the specific gravity increases and the thermal stability of the glass decreases. Therefore, from the viewpoint of suppressing an increase in specific gravity and a decrease in thermal stability of the glass, the content of La ₂ O ₃ is preferably within the above-mentioned range.

In the glass of the 1-1 embodiment, the upper limit of the content of Y ₂ O ₃ is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of Y ₂ O ₃ is preferably 0%.

When the content of Y ₂ O ₃ becomes too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. Therefore, it is preferable that content _{of Y2O3} is the said range from a viewpoint of suppressing the fall of the thermal stability of glass.

In the glass of the 1-1 embodiment, the upper limit of the content of Ta ₂ O ₅ is preferably 20%, and more preferably in the order of 10%, 5%, and 3%. In addition, the lower limit of the content of Ta ₂ O ₅ is preferably 0%.

Ta ₂ O ₅ is a glass component having an effect of improving the thermal stability of glass, and is a component that reduces Pg and F among Nb ₂ O ₅ , TiO ₂ , WO ₃ , and Bi ₂ O ₃ components. On the other hand, when the content of Ta ₂ O ₅ increases, the thermal stability of the glass decreases, and when the glass is melted, the melting residue of the glass raw material tends to occur. Moreover, the specific gravity rose. Therefore, the content of Ta ₂ O ₅ is preferably within the above range.

Moreover, in the glass of the 1-1 embodiment, the mass ratio of the content of Ta ₂ O ₅ to the total content of Ta ₂ O ₅ , Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Ta ₂ The upper limit of O ₅ /(Ta ₂ O ₅ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.900, and more preferably in the order of 0.700, 0.500, 0.300, 0.100, 0.050, and 0.010. The lower limit is 0.000.

When the mass ratio [Ta ₂ O ₅ /(Ta ₂ O ₅ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is too high, the specific gravity may increase and the cost may increase.

In the glass of the 1-1 embodiment, the content of Sc ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Sc ₂ O ₃ is preferably 0%.

In the glass of the 1-1 embodiment, the content of HfO ₂ is preferably 2% or less. In addition, the lower limit of the content of HfO ₂ is preferably 0%.

Sc ₂ O ₃ and HfO ₂ have the effect of improving the high dispersibility of glass, but are expensive components. Therefore, each content of Sc ₂ O ₃ and HfO ₂ is preferably within the above range.

In the glass of the 1-1 embodiment, the content of Lu ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Lu ₂ O ₃ is preferably 0%.

Although Lu ₂ O ₃ has the effect of improving the high dispersibility of glass, it is also a glass component that increases the specific gravity of glass because of its large molecular weight. Therefore, the content of Lu ₂ O ₃ is preferably within the above range.

In the glass of the 1-1 embodiment, the content of GeO ₂ is preferably 2% or less. In addition, the lower limit of the content of GeO ₂ is preferably 0%.

GeO ₂ has the effect of improving the high dispersibility of glass, but is a very expensive component among commonly used glass components. Therefore, the content of GeO ₂ is preferably within the above-mentioned range from the viewpoint of reducing the production cost of glass.

In the glass of the 1-1 embodiment, the content of Gd ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Gd ₂ O ₃ is preferably 0%.

When the content of Gd ₂ O ₃ becomes too large, the thermal stability of the glass decreases. In addition, when the content of Gd ₂ O ₃ is too large, the specific gravity of the glass increases, which is not preferable. Therefore, the content of Gd ₂ O ₃ is preferably within the above-mentioned range from the viewpoint of keeping the thermal stability of the glass well and suppressing an increase in specific gravity.

In the glass of the 1-1 embodiment, the content of Yb ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Yb ₂ O ₃ is preferably 0%.

Yb ₂ O ₃ has a larger molecular weight than La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , and thus increases the specific gravity of glass. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a high-mass lens is incorporated into an autofocus-type imaging lens, power required for driving the lens during autofocusing increases, and battery consumption becomes severe. Therefore, it is preferable to reduce the content of Yb ₂ O ₃ in order to suppress an increase in the specific gravity of the glass.

In addition, when the content of Yb ₂ O ₃ is too large, the thermal stability of the glass decreases. The content of Yb ₂ O ₃ is preferably within the above-mentioned range from the viewpoints of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.

It is preferable that the glass of the 1-1st embodiment mainly consists of the above-mentioned glass components, that is, SiO ₂ , P ₂ O ₅ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ , WO ₃ , and Bi ₂ O ₃ . , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, ZrO ₂ , Ta ₂ O ₅ , Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ and Yb ₂ O ₃ , the total content of the above-mentioned glass components is preferably more than 95%, more preferably more than 98%, further preferably more than 99%, more More preferably more than 99.5%.

In addition, although it is preferable that the glass of 1-1 Embodiment consists basically of the said glass component, you may contain other components in the range which does not inhibit the effect of 1st invention. In addition, in the first invention, the inclusion of unavoidable impurities is not excluded.

(glass properties)

<Refractive index nd>

In an example of the glass of the 1-1 embodiment, the lower limit of the refractive index nd may be 1.55, and further may be 1.60, 1.65, 1.70, 1.75, or 1.80. In addition, the upper limit of the refractive index nd may be set to 1.95, and further may be set to 1.90, 1.85, 1.80, or 1.75. The refractive index can be controlled by adjusting the contents of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ as glass components that contribute to high refractive index.

<Specific gravity of glass>

The glass of the 1-1 embodiment is a high-refractive index and high-dispersity glass, but has a low specific gravity. In general, if the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus driving of the lens-mounted camera lens can be reduced. On the other hand, if the specific gravity is excessively reduced, thermal stability will decrease.

Therefore, in an example of the glass of the 1-1 embodiment, the preferred range of specific gravity is 4.5 or less, and more preferably 4.3 or less, 4.1 or less, 4.0 or less, 3.9 or less, 3.8 or less, 3.7 or less, and 3.6 or less in order. Specific gravity can be adjusted by mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )], mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)], mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ) ], mass ratio [(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [Ta ₂ O ₅ /(Ta _{2 )} O ₅ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [ZrO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )].

<Glass transition temperature Tg>

In an example of the glass of the 1-1 embodiment, the upper limit of the glass transition temperature Tg is preferably 700°C, and more preferably 670°C, 650°C, 630°C, 610°C, and 590°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 450°C, more preferably 500°C, 510°C, 530°C, and 550°C in this order. The glass transition temperature Tg can be adjusted by adjusting the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)], mass ratio [(Li ₂ O+ Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [(SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )/ (Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [ZrO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] to control.

By making the upper limit of the glass transition temperature Tg satisfy the above-mentioned conditions, it is possible to suppress an increase in the forming temperature and the annealing temperature during reheat pressing of the glass, and reduce heat damage to the reheat press forming facility and the annealing facility.

By making the lower limit of the glass transition temperature Tg satisfy the above-mentioned conditions, it becomes easy to maintain the desired Abbe number and refractive index, while maintaining the reheat press formability and the thermal stability of the glass favorably.

<Transmittance>

The optical glass of the 1-1 embodiment is an optical glass with very little coloration. This optical glass is suitably used as a material of optical elements for imaging such as camera lenses, and optical elements for projection such as projectors.

The degree of coloration of optical glass is generally represented by λ70, λ5, and the like. For a glass sample with a thickness of 10.0 mm±0.1 mm, the spectral transmittance was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance reached 70% was set as λ70, and the wavelength at which the external transmittance reached 5% was set as λ5 .

In an example of the glass of the 1-1 embodiment, λ70 is preferably 500 nm or less, more preferably 470 nm or less, 450 nm or less, 430 nm or less, 410 nm or less, and 405 nm or less. In addition, λ5 is preferably 390 nm or less, more preferably 380 nm or less, 370 nm or less, and 360 nm or less. λ70 and λ5 can be adjusted by mass ratio [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [( SiO ₂ +P ₂ O ₅ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [Ta ₂ O ₅ /(Ta ₂ O ₅ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )], mass ratio [ZrO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] to control.

＜Processability＞

By containing P ₂ O ₅ in the glass of the 1-1 embodiment, reheat press formability (workability) can be improved. During reheat pressing, the glass is heated and the softened state (viscosity) of the glass is controlled. Even when the glass of the 1-1 embodiment is subjected to reheat pressing in a wide temperature range, since internal defects and devitrification are unlikely to occur, the softening state (viscosity) of the glass can be easily adjusted, and it is excellent in workability.

The heating temperature at the time of reheat pressing is usually a temperature at which the glass is softened and deformed, for example. Specifically, when the heating temperature is low, it is assumed to be about 50°C higher than the glass transition temperature Tg, and when it is high, it is assumed to be about 200 to 300°C higher than the glass transition temperature Tg temperature.

When the heating temperature during reheat pressing is low, that is, when heated at a temperature about 50°C higher than the glass transition temperature Tg, phase separation does not easily occur inside the glass, and even glass that does not contain P ₂ O ₅ can suppress the internal The occurrence of defects and devitrification.

However, when the heating temperature during reheat pressing is low, it is necessary to apply a high pressure during press molding. As a result, in the process of cooling a pressed glass molded product (for example, a lens and a lens blank), there is a high possibility that cracks will occur in the glass or cracks will occur in the glass. Therefore, when the heating temperature during reheat pressing is low, the yield of production tends to decrease, and the shape of the press-molded glass molded product tends to be limited.

On the other hand, when the heating temperature during reheat pressing is high, that is, when heating is performed at a temperature higher than the glass transition temperature Tg by about 200 to 300° C., in glass that does not contain P ₂ O ₅ , it is easy to penetrate inside the glass. Phase separation occurs, and internal defects and devitrification are prone to occur.

However, when the heating temperature during reheat pressing is high, it is not necessary to apply a high pressure during press molding, and cracks and the like are less likely to occur in the glass molded product. Therefore, the decrease in yield can be suppressed, and the shape of the glass molded product is less likely to be restricted.

Since the glass of the 1-1 embodiment contains P ₂ O ₅ , even when reheat pressing is performed at any assumed heating temperature, internal defects are less likely to occur. In particular, even when reheat pressing is performed at a high temperature, since internal defects and devitrification are less likely to occur, problems such as a decrease in yield and limitation of shape are less likely to occur.

In an example of the glass according to the first embodiment, the upper limit of the number of internal defects generated when the glass is softened and deformed by heat treatment is preferably 1,000 pieces/g, and more preferably 900 pieces/g and 700 pieces/g. g, 500/g, 300/g, 100/g, 70/g, 50/g, 40/g, 35/g, 30/g, 25/g, 20/g g, 15/g, 13/g, 10/g, 9/g, 7/g, 5/g, 3/g, 2/g, 1/g, 0/ The order of g is more preferred. The upper limit of the allowable number of internal defects varies depending on the application of the glass. In addition, the internal defect was made into the magnitude|size in the range of 1-300 micrometers.

Moreover, compared with the glass which does not contain _P2O5 , the glass of _1-1st Embodiment has less internal defects which generate|occur|produce when heat-processing at the temperature which softens and deform|transforms the glass. Glass (containing P ₂ O ₅ ) of the first embodiment with the number of internal defects being Ip [pieces/g], glass having the same composition of glass components other than P ₂ O ₅ and not containing P ₂ O ₅ When the number of internal defects is 1 [pieces/g], ΔI[pieces/g]=I-Ip is preferably 1.0 or more, and further 2 or more, 5 or more, 7 or more, 10 or more, 20 or more, 50 or more, 100 or more The order of more than or equal to 1,000, more than or equal to 10,000, and more than 100,000 is more preferable. In addition, the internal defect was made into the magnitude|size of the range of 1-300 micrometers.

(Manufacture of optical glass)

The glass which concerns on embodiment of 1st invention may mix|blend glass raw material so that the said predetermined composition may be obtained, and what is necessary is just to manufacture it according to a well-known glass manufacturing method using the mixed glass raw material. For example, a plurality of compounds are prepared and mixed sufficiently to prepare a batch raw material, and the batch raw material is put into a quartz crucible or a platinum crucible for rough melting (rough melt). The molten material obtained by rough melting was rapidly cooled and pulverized to produce cullet. Further, the cullet was placed in a platinum crucible, heated and remelted to obtain a molten glass, and after further clarification and homogenization, the molten glass was shaped and slowly cooled to obtain optical glass. The shaping|molding and slow cooling of a molten glass should just use a well-known method.

In addition, the compound used when preparing the batch raw material is not particularly limited as long as the desired glass component can be introduced into the glass and the desired content can be achieved, and examples of such compounds include oxides, carbonic acid Salts, nitrates, hydroxides, fluorides, etc.

As the optical glass of the embodiment of the first invention, the glass of the embodiment of the first invention can be used as it is.

(Manufacture of optical elements, etc.)

When producing an optical element using the optical glass of the embodiment of the first invention, a known method may be employed. For example, in the manufacture of the above-mentioned optical glass, molten glass is poured into a mold, and it is formed into a plate shape, and the glass material which consists of the optical glass of this invention is produced. The obtained glass material is appropriately cut, ground, and ground to produce pieces of a size and shape suitable for press molding. The chips are heated and softened, and are press-molded (reheat-pressed) by a known method to produce an optical element blank having a shape similar to that of an optical element. The optical element blank is annealed, ground and polished by a known method to produce an optical element.

Depending on the purpose of use, an antireflection film, a total reflection film, etc. may be coated on the optical function surface of the optical element to be produced.

According to one Embodiment of 1st invention, the optical element which consists of the said optical glass can be provided. As types of optical elements, lenses such as spherical lenses and aspherical lenses, prisms, diffraction gratings, and the like can be exemplified. As the shape of the lens, various shapes such as a biconvex lens, a plano-convex lens, a biconcave lens, a plano-concave lens, a convex meniscus lens, and a concave meniscus lens can be exemplified. An optical element can be manufactured by the method including the process of processing the glass molded object which consists of the said optical glass. As processing, dicing, cutting, rough grinding, fine grinding, grinding, and the like can be exemplified. When such a process is performed, by using the above-mentioned glass, breakage can be reduced, and a high-quality optical element can be stably provided.

Embodiment 1-2

Hereinafter, the glass of 1st invention is demonstrated based on the mass ratio of glass components as 1-2 embodiment. In addition, the function and effect of each glass component in 1-2 Embodiment are the same as that of each glass component in 1-1 Embodiment. Therefore, matters that overlap with the description of the 1-1 embodiment are appropriately omitted.

The glass of the first and second embodiments is a silicate glass having an Abbe number νd of 20 to 35,

Contains P ₂ O ₅ and Nb ₂ O ₅ ,

And the mass ratio of the content of Nb ₂ O ₅ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is greater than 0.6110.

The glass of the 1st-2nd embodiment is a silicate glass mainly containing SiO ₂ as a network-forming component of the glass. The content of SiO ₂ is preferably more than 0%, and the lower limit thereof is more preferably in the order of 1%, 5%, 10%, 15%, and 20%. In addition, the upper limit of the content of SiO ₂ is preferably 60%, and more preferably in the order of 50%, 40%, 39%, 38%, 37%, 36%, and 35%.

As a network-forming component of glass, SiO ₂ has the functions of improving thermal stability, chemical durability, weather resistance of glass, increasing the viscosity of molten glass, and making molten glass easy to form. On the other hand, when the content of SiO ₂ is large, the devitrification resistance of the glass tends to decrease, and Pg and F increase. Therefore, it is preferable to make content of _SiO2 into the said range.

The glass of the 1st _- 2nd embodiment contains _P2O5 . The lower limit of the content of P ₂ O ₅ is preferably 0.1%, and more preferably in the order of 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, and 1.9%. In addition, the upper limit of the content of P ₂ O ₅ is preferably 10%, and more preferably in the order of 7%, 5%, and 3%.

By making the lower limit of the content of P ₂ O ₅ satisfy the above range, the reheat press formability can be improved. Moreover, by making the upper limit of content of _{P2O5 satisfy} |fill the said range, the thermal stability of glass can be maintained, and reheat press formability can be improved.

The glass of the 1-2 embodiment contains Nb ₂ O ₅ . The lower limit of the content of Nb ₂ O ₅ may be 1%, and further may be 10%, 20%, 24%, 25%, 30%, 35%, 40%, or 43%. In addition, the upper limit of the content of Nb ₂ O ₅ is preferably 80%, and more preferably in the order of 60%, 55%, 50%, and 45%.

Nb ₂ O ₅ is a component that contributes to high dispersion. Therefore, by making the lower limit of the content of Nb ₂ O ₅ satisfy the above-mentioned range, glass with high refractive index and high dispersibility can be obtained. In addition, Nb ₂ O ₅ is also a glass component that improves thermal stability and chemical durability of glass. Therefore, when the upper limit of the content of Nb ₂ O ₅ satisfies the above-mentioned range, the thermal stability and chemical durability of the glass can be well maintained, and the occurrence of defects as optical elements can be suppressed.

In the glass of 1-2 embodiment, Abbe's number νd is 20-35. The Abbe's number νd may be 22-33, 23-31, 23-27, or 23-26.

By making Abbe's number (nu)d into the said range, the glass with high dispersibility can be obtained.

The Abbe number νd can be controlled by adjusting the contents of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ as glass components contributing to high dispersion.

In the glass of the 1st-2nd embodiment, the mass ratio of the content of Nb ₂ O ₅ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is greater than 0.6110. The lower limit of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.700, and more preferably in the order of 0.750, 0.800, and 0.850. In addition, the upper limit of the content of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 1.000, and further increased in the order of 0.990, 0.970, 0.950, 0.930, and 0.910 Preferred.

By setting the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] to the above range, an optical glass suitable for secondary chromatic aberration correction can be provided.

The glass composition in the 1-2 embodiment can be the same as that in the 1-1 embodiment. In addition, the glass properties in the 1-2 embodiment, the manufacture of the optical glass, and the manufacture of the optical element and the like may be the same as those in the 1-1 embodiment.

(Other Embodiments)

Hereinafter, Embodiment A, Embodiment B, and Embodiment C will be described as glass according to other embodiments of the first invention.

The glasses of Embodiment A, Embodiment B, and Embodiment C shown below also have preferable characteristics different from those of the glasses of Embodiments 1-1 and 1-2.

Therefore, when the characteristics of the glass of Embodiment A, Embodiment B, and Embodiment C are different from the characteristics of the glass of Embodiment 1-1 and Embodiment 1-2, Embodiment A, Embodiment B, and Embodiment C The preferable ranges of the characteristics of the glass are applied to the ranges described below.

Embodiment A

The glass of Embodiment A is characterized in that,

Abbe's number νd is 26.0 or more,

The mass ratio of the content of B ₂ O ₃ to the content of SiO ₂ [B ₂ O ₃ /SiO ₂ ] is 0.800 or less,

The mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is 0.950 or less,

The mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is below 0.480,

The mass ratio of the content of TiO ₂ to the content of Nb ₂ O ₅ [TiO ₂ /Nb ₂ O ₅ ] is 0.340 or less,

Mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is below 0.700,

SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , the total content of ZrO ₂ , TiO ₂ and Nb ₂ O ₅ is more than 96.0%,

The contents of PbO, CdO and As ₂ O ₃ are respectively 0.01% or less.

The glass of Embodiment A is a glass with an Abbe number νd of 26.0 or more, a relatively small specific gravity, and a small relative partial dispersion Pg,F with respect to the Abbe number νd.

In the glass of Embodiment A, the upper limit of the mass ratio [B ₂ O ₃ /SiO ₂ ] of the content of B ₂ O ₃ to the content of SiO ₂ may be set to 0.800, and further may be set to 0.700, 0.600, 0.550, The order of 0.500, 0.450, 0.350, 0.300, 0.250, 0.200 is more preferable. The mass ratio [B ₂ O ₃ /SiO ₂ ] may be zero.

By making the mass ratio [B ₂ O ₃ /SiO ₂ ] in the above range, an increase in specific gravity and coloration of glass can be suppressed.

In the glass of Embodiment A, the mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ + The upper limit of TiO ₂ )] can be set to 0.950, more preferably in the order of 0.930, 0.920, 0.910, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, 0.840, 0.830, 0.820, 0.810, 0.800, 0.790, 0.780. In addition, the lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.300, and more preferably 0.350, 0.400, 0.450, 0.500, 0.550, 0.600, 0.630, 0.650, 0.670 , 0.680 and 0.690 are more preferred.

Desired optical constants can be obtained by setting the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] to the above range. Furthermore, it is possible to suppress a decrease in the network forming action of the glass, and to suppress a decrease in the stability of the glass during reheating.

In the glass of Embodiment A, the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO+ZnO )/(Li ₂ O+Na ₂ O+K ₂ O)], the upper limit can be set to 0.480, and more preferably in the order of 0.400, 0.350, 0.300, 0.250, 0.200, 0.150, and 0.100. The mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] may be zero.

By setting the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] to the above range, an increase in specific gravity and a decrease in thermal stability can be suppressed. Also, the decrease in the refractive index nd can be suppressed.

In the glass of Embodiment A, the upper limit of the mass ratio [TiO ₂ /Nb ₂ O ₅ ] of the content of TiO ₂ to the content of Nb ₂ O ₅ can be set to 0.340, and further set to 0.300, 0.280, 0.260, 0.240, 0.220 , 0.200, and 0.180 are more preferred. The lower limit of the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is preferably 0, and more preferably in the order of 0.001, 0.002, 0.003, 0.004, and 0.005.

By setting the mass ratio [TiO ₂ /Nb ₂ O ₅ ] to the above range, the increase in relative partial dispersion Pg,F can be suppressed. Furthermore, it is possible to suppress a decrease in the network forming action of the glass, a decrease in the stability of the glass during reheating, and an increase in the specific gravity.

In the glass of Embodiment A, the mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O )/(TiO ₂ +Nb ₂ O ₅ )] can be set to an upper limit of 0.700, more preferably in the order of 0.650, 0.600, 0.570, 0.550, 0.530, 0.510, 0.500, 0.490, 0.480, 0.470, 0.460, and 0.450. The lower limit of the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is preferably 0.100, more preferably 0.150, 0.200, 0.250, 0.270, 0.290, 0.300, 0.310, 0.320 , 0.330 and 0.340 are more preferred.

Desired optical constants can be obtained by setting the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] to the above range. Moreover, the fall of the meltability of glass can be suppressed.

In the glass of Embodiment A, SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , Y The lower limit of the total content of ₂ O ₃ , Gd ₂ O ₃ , ZrO ₂ , TiO ₂ and Nb ₂ O ₅ can be set to 96.0%, and further 96.5%, 97.0%, 97.5%, 98.0%, 98.2%, 98.4%, The order of 98.6%, 98.8%, and 99.0% is more preferable. The total content may also be 100%.

A desired optical constant can be obtained by making this total content into the said range. Moreover, it can suppress the fall of the network formation effect of glass, and the fall of the stability of glass at the time of reheating, and the increase of specific gravity can be suppressed. Furthermore, an increase in relative partial dispersion can be suppressed.

In the glass of Embodiment A, the upper limit of the content of PbO, CdO, and As ₂ O ₃ can be set to 0.01%, respectively, and more preferably in the order of 0.005%, 0.003%, 0.002%, and 0.001%. The content of PbO, CdO and As ₂ O ₃ is preferably small, but may be 0%. These components are components that may cause a burden on the environment, and it is preferable not to contain them substantially.

About the content and ratio of the glass component other than the above in Embodiment A, it can be made the same as that of 1-1 Embodiment.

(Characteristics of the glass of the embodiment A)

<Abbé number νd>

In the glass of the embodiment A, the lower limit of the Abbe number νd is preferably 26.0, and more preferably in the order of 26.5, 27.0, 27.2, 27.4, 27.6, 27.8, 28.0, 28.2, 28.4, 28.6, 28.8, and 29.0. In addition, the upper limit of Abbe's number νd is more preferably in the order of 31.0, 30.8, 30.6, 30.4, 30.2, and 30.0. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . . Components that relatively increase the Abbe number νd are SiO ₂ , P ₂ O ₅ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

<Refractive index nd>

In the glass of Embodiment A, the refractive index nd is preferably 1.70 to 1.90. The refractive index nd may be 1.72 to 1.85, or 1.73 to 1.83. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the glass of Embodiment A is preferably 0.6500, and more preferably in the order of 0.6400, 0.6300, 0.6200, 0.6100, 0.6050, 0.6040, 0.6030, 0.6020, 0.6010, and 0.6000. Further, the relative partial dispersion Pg,F is preferably as low as possible, and the lower limit thereof is preferably 0.5500, and may be further 0.5600, 0.5700, 0.5800, 0.5840, 0.5850, 0.5870, 0.5890, 0.5900, 0.5910, 0.5920, 0.5930, and 0.5940.

By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained. The relative partial dispersion Pg will be relatively improved, and the components of F are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ and Ta ₂ O ₅ . The relative partial dispersion Pg will be relatively reduced, and the components of F are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. By appropriately adjusting the content of these components, the relative partial dispersion Pg,F can be controlled.

In the glass of Embodiment A, the relative partial dispersion Pg,F preferably satisfies the above formula (1-2), more preferably satisfies the above formula (1-3), further preferably satisfies the above formula (1-4), and particularly preferably satisfies the above formula Formula (1-5). By satisfying the above formula, an optical glass suitable for secondary chromatic aberration correction can be provided.

In addition, the upper limit of ΔPg,F' of the glass of Embodiment A is preferably 0.0000, more preferably -0.0010, -0.0020, -0.0030, -0.0040, -0.0050, and -0.0060 in the order. The lower ΔPg,F' is more preferable, and the lower limit thereof is preferably -0.0200, and further, -0.0180, -0.0160, -0.0140, -0.0130, and -0.0120 may be used. ΔPg is relatively increased, and the components of F' are P ₂ O ₅ , B ₂ O ₃ , and TiO ₂ . ΔPg is relatively decreased, and the components of F' are Nb ₂ O ₅ , La ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , Li ₂ O, Na ₂ O, and K ₂ O. By appropriately adjusting the content of these components, ΔPg,F' can be controlled.

In addition, in the glass of Embodiment A, the deviation ΔPg,F' is represented as follows.

ΔPg,F’=Pg,F+(0.00286×νd)-0.68900

<Specific gravity of glass>

The specific gravity of the glass of Embodiment A is preferably 3.60 or less, and more preferably 3.55 or less, 3.50 or less, 3.48 or less, 3.46 or less, 3.45 or less, 3.44 or less, 3.43 or less, 3.42 or less, 3.41 or less, and 3.40 or less in order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.00. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the glass of Embodiment A is preferably 700°C, more preferably 670°C, 650°C, 630°C, 620°C, 610°C, 600°C, and 590°C in the order. In addition, the lower limit of the glass transition temperature Tg is preferably 450°C, more preferably 470°C, 500°C, 510°C, 520°C, 530°C, and 540°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

＜Transparency of glass＞

The light transmittance of the glass of Embodiment A can be evaluated by coloration degrees λ70 and λ5.

For a glass sample having a thickness of 10.0 mm±0.1 mm, the spectral transmittance was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance reached 70% was λ70, and the wavelength at which the external transmittance reached 5% was λ5.

λ70 of the glass of Embodiment A is preferably 500 nm or less, more preferably 470 nm or less, still more preferably 450 nm or less, and still more preferably 430 nm or less. In addition, λ5 is preferably 400 nm or less, more preferably 380 nm or less, and further preferably 370 nm or less. The coloring degrees λ70 and λ5 can be controlled by adjusting the contents of ZrO ₂ , Nb ₂ O ₅ , TiO ₂ , SiO ₂ , and B ₂ O ₃ .

<Stability during reheating>

It is preferable that the glass of Embodiment A does not become cloudy when heated in a test furnace set to a temperature 200 to 220° C. higher than the glass transition temperature Tg for 5 minutes. More preferably, the number of crystals precipitated by the above heating is 100 or less per one sample. The stability during reheating can be controlled by adjusting the contents of Nb ₂ O ₅ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and P ₂ O ₅ .

Stability upon reheating was measured as described below. After heating a glass sample with a size of 10 mm × 10 mm × 7.5 mm in a test furnace set to a temperature 200 to 220° C. higher than the glass transition temperature Tg of the glass sample for 5 minutes, it was observed with an optical microscope (observation magnification). : 40 to 200 times) to measure the number of crystals per sample. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The glass properties other than those described above in Embodiment A can be the same as those in Embodiment 1-1. Moreover, about manufacture of an optical glass, manufacture of an optical element, etc., it can also be made the same as 1-1 Embodiment.

Embodiment B

The glass of Embodiment B is characterized in that,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65.

The glass of the embodiment B is relatively small in specific gravity and small in relative partial dispersion Pg and F.

In the glass of Embodiment B, the mass ratio [SiO ₂ /Nb ₂ O ₅ ] of the content of SiO ₂ to the content of Nb ₂ O ₅ may be greater than 1.05, and the lower limit thereof may be increased in the order of 1.09, 1.11, 1.15, and 1.17. Preferred. In addition, the upper limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By setting the mass ratio [SiO ₂ /Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be reduced while maintaining desired optical constants (refractive index nd, Abbe number νd).

In the glass of Embodiment B, the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] of the content of ZrO ₂ to the content of Nb ₂ O ₅ may be greater than 0.25, and the lower limit thereof may be 0.26, 0.27, 0.28, 0.29, 0.30, The order of 0.305, 0.310, 0.315 is more preferable. In addition, the upper limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.65, and more preferably 0.61, 0.57, and 0.53 in this order. By setting the lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] to the above range, the relative partial dispersion Pg,F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the glass of Embodiment B, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ can be made [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ + B ₂ O ₃ )] is more than 0.65, and its lower limit is more preferably in the order of 0.66, 0.67, 0.69, 0.70, 0.71, 0.73, 0.75, 0.76, 0.77, 0.79, 0.80, 0.83, 0.86, 0.88. In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.20, and more preferably in the order of 1.15, 1.14, 1.13, 1.12, 1.11, 1.10, and 1.09 . By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the thermal stability of the glass can be maintained and a desired optical constant can be obtained.

In the glass of Embodiment B, the total content of TiO ₂ and BaO [TiO ₂ +BaO] is preferably less than 10%, and the upper limit thereof is more preferably in the order of 8.0%, 7.8%, 7.6%, and 7.4%. In addition, the lower limit of the total content [TiO ₂ +BaO] is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. By setting the upper limit of the total content [TiO ₂ +BaO] to the above range, the relative partial dispersion Pg,F can be reduced, and the specific gravity of the glass can be reduced.

In the glass of Embodiment B, the mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably less than 0.3, which The upper limit is more preferably in the order of 0.25, 0.20, and 0.15. In addition, the lower limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0, and more preferably 0.05, 0.07, and 0.10 in the order. The mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] may be zero. By setting the upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the glass of Embodiment B, the mass ratio [ZnO/Nb ₂ O ₅ ] of the content of ZnO to the content of Nb ₂ O ₅ is preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, and 0.105. In addition, the lower limit of the mass ratio [ZnO/Nb ₂ O ₅ ] is preferably 0, and more preferably 0.02, 0.05, and 0.07 in this order. The mass ratio [ZnO/Nb ₂ O ₅ ] may be zero. By setting the upper limit of the mass ratio [ZnO/Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be lowered, and a desired optical constant can be obtained.

For the glass of Embodiment B, the total content of R ₂ O and the total content of MgO, CaO, SrO, and BaO relative to the total content of Li ₂ O, Na ₂ O, and K ₂ O can be the total content of R'O, the total content of The mass ratio of R ₂ O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05. The mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably greater than 0.6, and the lower limit thereof is more preferably in the order of 0.80, 0.82, 0.84, and 0.86. In addition, the upper limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 1.00, and more preferably 0.99, 0.98, and 0.95 in this order. By making the mass ratio [R ₂ O/(R ₂ O+R'O)] in the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

The content and ratio of the glass components other than those described above in Embodiment B can be the same as those in Embodiment 1-1.

(Characteristics of the glass of Embodiment B)

<Refractive index nd>

In the glass of Embodiment B, the refractive index nd is preferably 1.69 to 1.76. The refractive index nd may be set to 1.695 to 1.755, or 1.70 to 1.75. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Abbé number νd>

In the glass of Embodiment B, it is preferable that Abbe's number νd is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

<Specific gravity of glass>

The specific gravity of the glass of Embodiment B is preferably 3.19 or less, and more preferably 3.18 or less, 3.17 or less, and 3.16 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.05. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the glass of Embodiment B is preferably 0.5950, and more preferably 0.5945, 0.5940, and 0.5935 in this order. In addition, the lower limit of the relative partial dispersion Pg,F is preferably 0.5780, and more preferably in the order of 0.5785, 0.5790, 0.5795, 0.5805, 0.5815, and 0.5830. By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained.

In addition, the upper limit of the deviation ΔPg,F of the relative partial dispersion Pg,F of the glass of Embodiment B is preferably 0.0015, and more preferably 0.0012, 0.0010, and 0.0008 in the order. In addition, the lower limit of the deviation ΔPg,F is preferably -0.0060, more preferably -0.0048, -0.0045, -0.0042, -0.0040, -0.0035, -0.0025 in the order.

<Liquid phase temperature>

The liquidus temperature LT of the glass of Embodiment B is preferably 1200°C or lower, and more preferably 1190°C or lower, 1180°C or lower, and 1170°C or lower in this order. By making the liquidus temperature into the above-mentioned range, the melting and forming temperature of glass can be lowered, and as a result, erosion of glass melting equipment (eg, crucible, stirring equipment for molten glass, etc.) in the melting process can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000°C. The liquidus temperature LT is determined according to the balance of the contents of all the glass components. Among them, the contents of SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like have a great influence on the liquidus temperature LT.

In addition, the liquidus temperature is determined as follows. Put 10cc (10ml) of glass into a platinum crucible, melt at 1250℃～1400℃ for 15～30 minutes, cool down to below the glass transition temperature Tg, put the glass together with the platinum crucible into a melting furnace at a given temperature and melt it. Hold for 2 hours. The temperature was kept at 1000°C or higher, the interval was set to 5°C or 10°C, the temperature was kept for 2 hours, and then cooled, and the presence or absence of crystals in the glass was observed with a 100-fold optical microscope. The lowest temperature at which no crystals were precipitated was set as the liquidus temperature.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the glass of Embodiment B is preferably 580°C, and more preferably 575°C, 570°C, and 565°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 510°C, and more preferably 515°C, 520°C, and 525°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

<Stability during reheating>

In the glass of Embodiment B, the glass transition temperature Tg is heated for 10 minutes, and further heated at a temperature 140 to 250°C higher than the Tg for 10 minutes, and at this time, the number of crystals observed per 1 g is preferably 20 or less, More preferably, it is 10 or less.

In addition, the stability at the time of reheating was measured as follows. A glass sample with a size of 1 cm x 1 cm x 0.8 cm was heated for 10 minutes in the first test furnace set to the glass transition temperature Tg of the glass sample, and further set to be higher than the glass transition temperature Tg of the glass sample. After heating in the second test furnace at a temperature of 140 to 250° C. for 10 minutes, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The glass properties other than those described above in Embodiment B can be the same as those in Embodiment 1-1. Moreover, about manufacture of an optical glass, manufacture of an optical element, etc., it can also be made the same as 1-1 Embodiment.

Embodiment C

The glass of Embodiment C is characterized in that,

The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80,

Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55,

The total content of SiO ₂ and Nb ₂ O ₅ [SiO ₂ +Nb ₂ O ₅ ] is 62 to 84%.

The glass of the embodiment C is small in specific gravity and small in relative partial dispersion Pg,F.

In the glass of Embodiment C, the mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably greater than 0.80, and the lower limit thereof is further set to 0.83 , 0.85, 0.86, 0.87, 0.88 are more preferred. The upper limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 1.50, and more preferably 1.40, 1.30, and 1.20 in this order. By setting the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] to the above range, crystallization of glass can be suppressed, and glass having excellent homogeneity and stability during reheating can be obtained.

In the glass of Embodiment C, the mass ratio of the content of SiO ₂ to the content of Na ₂ O [SiO ₂ /Na ₂ O] is preferably 2.5 to 8.5. The lower limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 2.6, and more preferably 2.65, 2.70, and 2.75 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 8.2, and even more preferably 8.0, 7.8, and 7.6 in this order. By setting the mass ratio [SiO ₂ /Na ₂ O] to the above range, glass excellent in homogeneity and stability during reheating can be obtained.

In the glass of Embodiment C, the mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] can be set to 1.45 to 4.55. The lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is more preferably 1.70, and more preferably 1.72, 1.74, and 1.76 in this order . In addition, the upper limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is more preferably 4.20, and furthermore is 4.00, 3.95, and 3.90 in this order More preferred. Crystallization of glass can be suppressed by making mass ratio _[ ( _SiO2 +B2O3+ _{P2O5 )} /( _{Li2O +} Na2O ₊ K2O ₎ ] into the said range.

In the glass of Embodiment C, the total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ can be set to 62 to 84%. The lower limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is more preferably 63.0%, and more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, the upper limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is more preferably 83%, and more preferably 82.7%, 82.3%, and 82.1% in this order. By making the total content [SiO ₂ +Nb ₂ O ₅ ] in the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. Furthermore, crystallization of glass can be suppressed.

The content and ratio of the glass components other than those described above in Embodiment C can be the same as those in Embodiment 1-1.

(Characteristics of the glass of Embodiment C)

<Refractive index nd>

In the glass of Embodiment C, the refractive index nd is preferably 1.690 to 1.760. The refractive index nd may be set to 1.695 to 1.755, or 1.700 to 1.750. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Abbé number νd>

In the glass of Embodiment C, it is preferable that Abbe's number νd is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

<Specific gravity of glass>

The specific gravity of the glass of Embodiment C is preferably 3.40 or less, and more preferably 3.35 or less, 3.30 or less, and 3.25 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.10. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the glass of Embodiment C is preferably 0.5980, and more preferably 0.5970, 0.5960, 0.5950, and 0.5940 in this order. In addition, it is preferable that the relative partial dispersion Pg,F is low, and the lower limit thereof is preferably 0.5780, and may be further 0.5800, 0.5820, 0.5840, and 0.5860. By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained. The relative partial dispersion Pg,F can be controlled by adjusting the content of SiO ₂ , B ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ and the like.

In addition, the upper limit of the deviation ΔPg,F of the relative partial dispersion Pg,F of the glass of Embodiment C is preferably 0.0030, and more preferably 0.0025, 0.0020, and 0.0015 in the order. In addition, when the deviation ΔPg,F is preferably low, the lower limit is preferably -0.0060, and further, -0.0050, -0.0040, -0.0030, and -0.0020 may be used.

<Liquid phase temperature>

The liquidus temperature LT of the glass of Embodiment C is preferably 1200°C or lower, and more preferably 1190°C or lower, 1180°C or lower, and 1170°C or lower in this order. By making the liquidus temperature into the above-mentioned range, the melting and forming temperature of glass can be lowered, and as a result, erosion of glass melting equipment (eg, crucible, stirring equipment for molten glass, etc.) in the melting process can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000°C. The liquidus temperature LT is determined according to the balance of the contents of all the glass components. Among them, the contents of SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like have a great influence on the liquidus temperature LT.

In addition, the liquidus temperature is determined as follows. Put 10cc (10ml) of glass into a platinum crucible, melt at 1250℃～1400℃ for 15～30 minutes, cool down to below the glass transition temperature Tg, put the glass together with the platinum crucible into a melting furnace at a given temperature and melt it. Hold for 2 hours. The temperature was kept at 1000°C or higher, the interval was set to 5°C or 10°C, the temperature was kept for 2 hours, and then cooled, and the presence or absence of crystals in the glass was observed with a 100-fold optical microscope. The lowest temperature at which no crystals were precipitated was set as the liquidus temperature.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the glass of Embodiment C is preferably 670°C, and more preferably 650°C, 630°C, and 610°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 510°C, and more preferably 520°C, 525°C, and 530°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

<Stability during reheating>

In the glass of Embodiment C, the glass transition temperature Tg is heated for 10 minutes, and further heated at a temperature 140 to 220° C. higher than the Tg for 10 minutes, and the number of crystals observed per 1 g is preferably 20 or less. More preferably, it is 10 or less.

In addition, the stability at the time of reheating was measured as follows. A glass sample having a size of 1 cm x 1 cm x 0.8 cm was heated in a first test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and was further set to be higher than the glass transition temperature Tg of the glass sample. After heating in the second test furnace at a temperature of 140 to 220° C. for 10 minutes, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The glass properties other than those described above in Embodiment C can be the same as those in Embodiment 1-1. Moreover, about manufacture of an optical glass, manufacture of an optical element, etc., it can also be made the same as 1-1 Embodiment.

"Second Invention"

[Background Art of the Second Invention]

In order to reduce the power consumption when driving the autofocus function, the optical element mounted in the optical system of the autofocus system is required to be reduced in weight. If the specific gravity of glass can be reduced, the weight of optical elements such as lenses can be reduced. In addition, in order to correct the chromatic aberration, the relative partial dispersion Pg and F are required to be small.

Moreover, as a manufacturing method of such an optical glass used for an optical system, the reheat pressing method of reheating and shaping|molding glass is mentioned. In this production method, devitrification at the time of reheating is observed in the silicate-based high-refractive-index and high-dispersity optical glass. In addition, high stability such that devitrification does not easily occur inside the glass during reheating of the glass is required.

Patent Documents 2-1 to 2-3 disclose optical glasses that have a predetermined optical constant and reduce relative partial dispersion. However, the optical glasses disclosed in Patent Documents 2-1 to 2-3 have a large specific gravity.

In Patent Documents 2-4, it is a problem to obtain an optical glass with a small relative partial dispersion at a low cost. However, the optical glasses disclosed in Patent Documents 2-4 are glasses with relatively low dispersibility, and do not have the optical constants desired in the second invention.

[Prior Art Document of the Second Invention]

Patent Literature

Patent Document 2-1: Japanese Patent Laid-Open No. 2015-193515

Patent Document 2-2: Japanese Patent Laid-Open No. 2015-193516

Patent Document 2-3: Japanese Patent Application Laid-Open No. 2016-88759

Patent Document 2-4: Japanese Patent Laid-Open No. 2017-105702

[Content of the second invention]

[Problems to be solved by the second invention]

The object of the second invention is to provide an optical glass having a desired optical constant, a relatively small specific gravity, a small relative partial dispersion Pg,F with respect to Abbe's number νd, and excellent stability during reheating, and an optical glass formed of the above-mentioned optical glass optical components.

[way of solving the problem]

The gist of the second invention is as follows.

(1) An optical glass whose Abbe number νd is 26.0 or more,

The content of SiO ₂ is more than 0 mass % and less than 40 mass %,

The content of TiO ₂ is 0 to 15% by mass,

The content of Nb ₂ O ₅ is 25 to 45% by mass,

_The content of ZrO2 is greater than 0 mass%,

The mass ratio of the content of B ₂ O ₃ to the content of SiO ₂ [B ₂ O ₃ /SiO ₂ ] is 0.800 or less,

The mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is 0.950 or less,

The total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O+Na ₂ O+K ₂ O] is 10 to 25% by mass,

The mass ratio of the content of Na ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.330 or more,

The mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is below 0.480,

The mass ratio of the content of TiO ₂ to the content of Nb ₂ O ₅ [TiO ₂ /Nb ₂ O ₅ ] is 0.340 or less,

Mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is below 0.700,

SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , the total content of ZrO ₂ , TiO ₂ and Nb ₂ O ₅ is 96.0 mass % or more,

The contents of PbO, CdO and As ₂ O ₃ are respectively 0.01 mass % or less.

(2) An optical element formed of the optical glass described in (1) above.

[Effect of the second invention]

According to the second invention, it is possible to provide an optical glass having a desired optical constant, a relatively small specific gravity, a small relative partial dispersion Pg,F with respect to Abbe's number νd, and excellent stability during reheating, and an optical glass formed of the above-mentioned optical glass. optical components.

[Specific embodiment of the second invention]

Hereinafter, the glass according to the embodiment of the second invention will be described as the second embodiment.

In the second embodiment, the relative partial dispersion Pg and F are expressed as follows using the respective refractive indices ng, nF, and nC among g-rays, F-rays, and C-rays.

Pg,F=(ng-nF)/(nF-nC)

The normal line in the second embodiment is represented by the following formula on a plane in which the horizontal axis is the Abbe number νd and the vertical axis is the relative partial dispersion Pg,F.

Pg,F(0)’＝0.68900-0.00286×νd

Further, the deviation ΔPg,F' from the relative partial dispersion Pg,F from the normal line is expressed as follows.

ΔPg,F’=Pg,F-Pg,F(0)’

The optical glass of the second embodiment is characterized in that the Abbe number νd is 26.0 or more,

The content of _SiO2 is greater than 0% and less than 40%,

The content of TiO ₂ is 0-15%,

The content of Nb ₂ O ₅ is 25-45%,

_The content of ZrO2 is greater than 0%,

The mass ratio of the content of B ₂ O ₃ to the content of SiO ₂ [B ₂ O ₃ /SiO ₂ ] is 0.800 or less,

The mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is 0.950 or less,

The total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O+Na ₂ O+K ₂ O] is 10-25%,

The mass ratio of the content of Na ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.330 or more,

The mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is below 0.480,

The mass ratio of the content of TiO ₂ to the content of Nb ₂ O ₅ [TiO ₂ /Nb ₂ O ₅ ] is 0.340 or less,

Mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is below 0.700,

SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , the total content of ZrO ₂ , TiO ₂ and Nb ₂ O ₅ is more than 96.0%,

The contents of PbO, CdO and As ₂ O ₃ are respectively 0.01% or less.

In the optical glass of the second embodiment, the Abbe number νd is 26.0 or more. The lower limit of the Abbe number νd is preferably 26.5, and more preferably in the order of 27.0, 27.2, 27.4, 27.6, 27.8, 28.0, 28.2, 28.4, 28.6, 28.8, and 29.0. In addition, the upper limit of the Abbe number νd is more preferably 31.0, 30.8, 30.6, 30.4, 30.2, and 30.0 in the order. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , P ₂ O ₅ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

In the optical glass of the second embodiment, the content of SiO ₂ is more than 0% and less than 40%. The lower limit of the content of SiO ₂ is preferably 10%, and more preferably in the order of 15%, 17%, 19%, 21%, 23%, 25%, 26%, 27%, and 28%. In addition, the upper limit of the content of SiO ₂ is preferably 39%, and more preferably in the order of 38%, 37%, 36%, 35%, 34%, and 33%.

SiO ₂ is a network-forming component of glass. When the content of SiO ₂ is too small, there is a possibility that the network forming effect of the glass is lowered, and the stability of the glass during reheating is lowered. When the content of SiO ₂ is too large, there is a possibility that a desired optical constant cannot be obtained.

In the optical glass of the second embodiment, the content of TiO ₂ is 0 to 15%. The upper limit of the content of TiO ₂ is preferably 14%, and more preferably in the order of 13%, 12%, 11%, 10%, 9%, 8%, 7%, and 6%. The lower limit of the content of TiO ₂ is preferably 0.05%, and more preferably in the order of 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%.

TiO ₂ is a component that highly disperses glass. When the content of TiO ₂ is too large, there is a hidden danger that the relative partial dispersion Pg,F will increase. When the content of TiO ₂ is too small, there is a possibility that a desired optical constant cannot be obtained. Moreover, there exists a possibility that the network formation effect of glass will fall and the stability at the time of reheating of glass will fall.

In the optical glass of the second embodiment, the content of Nb ₂ O ₅ is 25 to 45%. The lower limit of the content of Nb ₂ O ₅ is preferably 27%, and more preferably in the order of 28%, 29%, 30%, 31%, 32%, 33%, 34%, and 35%. In addition, the upper limit of the content of Nb ₂ O ₅ is preferably 44.5%, and more preferably in the order of 44.0%, 43.5%, 43.2%, 43.0%, 42.7%, and 42.5%.

Nb ₂ O ₅ is a component that makes glass highly dispersed and reduces relative partial dispersion Pg,F. When the content of Nb ₂ O ₅ is too large, the thermal stability of the glass may be lowered, and the cost of raw materials may be increased. When the content of Nb ₂ O ₅ is too small, the relative partial dispersion Pg,F increases, and there is a possibility that a desired optical constant cannot be obtained.

In the optical glass of the second embodiment, the content of ZrO ₂ is greater than 0%. The lower limit of the content of ZrO ₂ is preferably 1%, and more preferably in the order of 2%, 3%, 4%, 5%, 6%, 7%, and 8%. In addition, the upper limit of the content of ZrO ₂ is preferably 15%, more preferably 14%, 13.5%, 13.2%, 13.0%, 12.8%, 12.6%, and 12.4% in this order.

ZrO ₂ is a component that makes glass highly dispersed and reduces relative partial dispersion Pg,F. When the content of ZrO ₂ is too large, there is a possibility that the network forming effect of the glass is lowered, and the stability of the glass during reheating is lowered. When the content of ZrO ₂ is too small, there is a possibility that the relative partial dispersion Pg,F increases, and the desired optical constant cannot be obtained.

In the optical glass of the second embodiment, the mass ratio [B ₂ O ₃ /SiO ₂ ] of the content of B ₂ O ₃ to the content of SiO ₂ is 0.800 or less. The upper limit of the mass ratio [B ₂ O ₃ /SiO ₂ ] is preferably 0.700, and more preferably in the order of 0.600, 0.550, 0.500, 0.450, 0.350, 0.300, 0.250, and 0.200. The mass ratio [B ₂ O ₃ /SiO ₂ ] may be zero.

When the mass ratio [B ₂ O ₃ /SiO ₂ ] is too large, there is a possibility that the specific gravity will increase and the coloring of the glass will increase.

In the optical glass of the second embodiment, the mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is 0.950 or less. The upper limit of the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.930, more preferably 0.920, 0.910, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, 0.840, 0.830 , 0.820, 0.810, 0.800, 0.790, 0.780 in the order of more preferable. In addition, the lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.300, and more preferably 0.350, 0.400, 0.450, 0.500, 0.550, 0.600, 0.630, 0.650, 0.670 , 0.680 and 0.690 are more preferred.

When the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is too large, there is a possibility that a desired optical constant cannot be obtained. When the mass ratio [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is too small, there is a possibility that the network forming effect of the glass is lowered, and the stability of the glass during reheating is lowered.

In the optical glass of the second embodiment, the total content [Li ₂ O+Na ₂ O+K ₂ O] of Li ₂ O, Na ₂ O and K ₂ O is 10 to 25%. The lower limit of the total content [Li ₂ O+Na ₂ O+K ₂ O] is preferably 11.0%, further 12.0%, 12.5%, 13.0%, 13.5%, 13.7%, 13.9%, 14.1%, 14.3%, 14.5% order is more preferred. In addition, the upper limit of the total content [Li ₂ O+Na ₂ O+K ₂ O] is preferably 23%, and more preferably in the order of 22%, 21.5%, 21.0%, 20.5%, 20.0%, 19.5%, and 19.0% .

When the total content [Li ₂ O+Na ₂ O+K ₂ O] is too large, there is a possibility that the network forming effect of the glass is lowered, and the stability of the glass during reheating is lowered. In addition, there is a risk of shortening the life of refractories such as glass kilns. When the total content [Li ₂ O+Na ₂ O+K ₂ O] is too small, there is a possibility that the solubility of the glass decreases.

In the optical glass of the second embodiment, the mass ratio of the content of Na ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.330 or more. The lower limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.380, and furthermore, it is in the order of 0.420, 0.440, 0.460, 0.480, 0.500, 0.520, 0.540, 0.560, 0.580, and 0.600 More preferred. In addition, the upper limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 1.000, and more preferably 0.950, 0.900, 0.880, 0.860, 0.840, 0.820, 0.800, 0.780, 0.760, 0.740 , 0.720, and 0.700 are more preferred.

When the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is too large, the thermal stability of the glass may be reduced. If the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is too small, the specific gravity increases, the thermal stability decreases, and the raw material cost increases.

In the optical glass of the second embodiment, the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO +ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.480 or less. The upper limit of the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.400, and the upper limit is further 0.350, 0.300, 0.250, 0.200, 0.150, 0.100 in this order More preferred. The mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] may be zero.

When the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is too large, the specific gravity increases and the thermal stability decreases. If the mass ratio [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is too small, the refractive index nd may decrease.

In the optical glass of the second embodiment, the mass ratio [TiO ₂ /Nb ₂ O ₅ ] of the content of TiO ₂ to the content of Nb ₂ O ₅ is 0.340 or less. The upper limit of the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is preferably 0.300, more preferably 0.280, 0.260, 0.240, 0.220, 0.200, and 0.180 in this order. The lower limit of the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is preferably 0, and more preferably in the order of 0.001, 0.002, 0.003, 0.004, and 0.005.

When the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is too large, there is a risk that the relative partial dispersion Pg,F will increase. When the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is too small, there is a possibility that the network forming effect of the glass is reduced, the stability of the glass during reheating is reduced, and the specific gravity is increased.

In the optical glass of the second embodiment, the mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is 0.700 or less. The upper limit of the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is preferably 0.650, more preferably 0.600, 0.570, 0.550, 0.530, 0.510, 0.500, 0.490, 0.480 , 0.470, 0.460, 0.450 in the order of more preferred. The lower limit of the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is preferably 0.100, more preferably 0.150, 0.200, 0.250, 0.270, 0.290, 0.300, 0.310, 0.320 , 0.330 and 0.340 are more preferred.

When the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is too large, there is a possibility that a desired optical constant cannot be obtained. When the mass ratio [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is too small, there is a possibility that the solubility of the glass is lowered.

In the optical glass of the present embodiment, SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , The total content of Y ₂ O ₃ , Gd ₂ O ₃ , ZrO ₂ , TiO ₂ and Nb ₂ O ₅ is 96.0% or more. The lower limit of the total content is preferably 96.5%, and more preferably in the order of 97.0%, 97.5%, 98.0%, 98.2%, 98.4%, 98.6%, 98.8%, and 99.0%. The total content may also be 100%.

When the total content is too small, there is a possibility that a desired optical constant cannot be obtained. In addition, there are risks that the network forming effect of the glass is reduced, the stability of the glass when reheated is reduced, and the specific gravity is increased, and the relative partial dispersion is increased.

In the optical glass of the second embodiment, the contents of PbO, CdO, and As ₂ O ₃ are respectively 0.01% or less. The upper limit of the content of PbO, CdO, and As ₂ O ₃ is preferably 0.005%, respectively, and more preferably 0.003%, 0.002%, and 0.001% in the order. The content of PbO, CdO and As ₂ O ₃ is preferably small, but may be 0%. These components are components that may cause a burden on the environment, and it is preferable not to contain them substantially.

The content and ratio of the glass components other than the above in the optical glass of the second embodiment will be described below in detail.

In the optical glass of the second embodiment, the upper limit of the content of B ₂ O ₃ is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 8%, 6%, 5%, 4% The order of %, 3%, 2%, and 1% is more preferable. In addition, it is preferable that the content of B ₂ O ₃ is small, but the content of B ₂ O ₃ may be 0%.

By making content _of B2O3 into the said range, the specific gravity of glass can be lowered| _hung , and the thermal stability of glass can be improved.

In the optical glass of the second embodiment, the upper limit of the content of P ₂ O ₅ is preferably 2.50%, and more preferably in the order of 2.00%, 1.00%, 0.90%, 0.80%, 0.70%, 0.60%, and 0.50%. In addition, the lower limit of the content of P ₂ O ₅ is preferably 0%, and more preferably in the order of 0.05%, 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, and 0.20%. The content of P ₂ O ₅ may also be 0%. Since P ₂ O ₅ is a glass network-forming component, the thermal stability of the glass can be improved by making the content thereof satisfy the above-mentioned lower limit. On the other hand, P ₂ O ₅ is a component that reduces dispersion and relatively increases ΔPg,F'. Therefore, when the content satisfies the above-mentioned upper limit, low dispersion can be suppressed and thermal stability of glass can be maintained. .

In the optical glass of the second embodiment, the upper limit of the content of Al ₂ O ₃ is preferably 20%, and further 15%, 13%, 11%, 10%, 9%, 8%, 7%, 6%, 5% The order of %, 4%, and 3% is more preferable. The content of Al ₂ O ₃ may also be 0%. _{Devitrification} resistance and thermal stability of glass can be maintained by making content of _Al2O3 into the said range.

In the optical glass of the second embodiment, the upper limit of the total content [SiO ₂ +P ₂ O ₅ ] of SiO ₂ and P ₂ O ₅ is preferably 40%, and further 39%, 38%, 37%, 36%, The order of 35% and 34% is more preferable. In addition, the lower limit of the total content [SiO ₂ +P ₂ O ₅ ] is preferably 10%, and more preferably in the order of 15%, 20%, 22%, 24%, 26%, 28%, and 30%. By making the total content [SiO ₂ +P ₂ O ₅ ] within the above range, the relative partial dispersion Pg,F can be suppressed from rising, and the thermal stability of the glass can be maintained.

In addition, in the optical glass of the second embodiment, the upper limit of the total content [SiO ₂ +B ₂ O ₃ +P ₂ O ₅ ] of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ is preferably 40%, and further The order of 39%, 38%, 37%, 36%, 35%, 34% is more preferable. In addition, the lower limit of the total content [SiO ₂ +B ₂ O ₃ +P ₂ O ₅ ] is preferably 10%, and is further increased in the order of 15%, 20%, 22%, 24%, 26%, 28%, and 30% Preferred.

In the optical glass of the second embodiment, the upper limit of the mass ratio of the content of P ₂ O ₅ to the total content of SiO ₂ and P ₂ O ₅ [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] is preferable It is 0.200, more preferably in the order of 0.100, 0.050, 0.030, 0.020, 0.018, and 0.015. The mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] may be zero.

By making the mass ratio [P ₂ O ₅ /(SiO ₂ +P ₂ O ₅ )] within the above range, the relative partial dispersion Pg,F can be suppressed from increasing.

In addition, in the optical glass of the second embodiment, the mass ratio of the content of P ₂ O ₅ to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ [P ₂ O ₅ /(SiO ₂ +B ₂ The upper limit of O ₃ +P ₂ O ₅ )] is preferably 0.200, more preferably in the order of 0.100, 0.050, 0.030, 0.020, 0.018, and 0.015. The mass ratio [P ₂ O ₅ /(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )] may be zero.

Further, in the optical glass of the second embodiment, the mass ratio of the content of SiO ₂ to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ [SiO ₂ /(SiO ₂ +B ₂ O ₃ +P The upper limit of ₂ O ₅ )] is preferably 1. In addition, the lower limit of the mass ratio [SiO ₂ /(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )] is preferably 0.900, and more preferably in the order of 0.905, 0.910, 0.915, and 0.920.

In the optical glass of the second embodiment, the lower limit of the total content of Nb ₂ O ₅ and TiO ₂ [Nb ₂ O ₅ +TiO ₂ ] is preferably 30%, and more preferably 31%, 32%, 33%, 34%, The order of 35%, 36%, 37%, 38%, 39%, 40% is more preferable. In addition, the upper limit of the content of the total content [Nb ₂ O ₅ +TiO ₂ ] is preferably 55%, and more preferably in the order of 53%, 51%, 49%, 47%, 45%, 44%, and 43%. By making the total content [Nb ₂ O ₅ +TiO ₂ ] in the above range, a desired optical constant can be achieved.

In the optical glass according to the second embodiment, the upper limit of the mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] of the content of P ₂ O ₅ to the content of Nb ₂ O ₅ is preferably 0.200, and more preferably 0.100, 0.050, The order of 0.020, 0.018, 0.015, 0.014, 0.013, 0.012 is more preferable. The mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] may be zero. By making the mass ratio [P ₂ O ₅ /Nb ₂ O ₅ ] within the above range, the increase in ΔPg,F' can be suppressed.

In the optical glass of the second embodiment, the upper limit of the mass ratio of the content of P ₂ O ₅ to the total content of Nb ₂ O ₅ and TiO ₂ [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] is preferable It is 0.200, more preferably in the order of 0.100, 0.050, 0.020, 0.018, 0.015, 0.014, 0.013, 0.012, 0.011, and 0.010. The mass ratio [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] may be zero. By making the mass ratio [P ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ )] within the above range, the increase in ΔPg,F′ can be suppressed.

In the optical glass of the second embodiment, the upper limit of the content of WO ₃ is preferably 5.0%, and more preferably in the order of 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.3%, and 0.1% . In addition, the lower limit of the content of WO ₃ is preferably 0%. The content of WO ₃ may also be 0%. By making the upper limit of the content of WO ₃ into the above range, the transmittance can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In the optical glass of the second embodiment, the upper limit of the content of Bi ₂ O ₃ is 5.0%, and further increased in the order of 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.3%, and 0.1% Preferred. In addition, the lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may also be 0%. By making the content of Bi ₂ O ₃ into the above range, the thermal stability of the glass can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In the optical glass of the second embodiment, the lower limit of the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] is preferably 30 %, more preferably in the order of 32%, 34%, 36%, 38%, 39%, and 40%. In addition, the upper limit of the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] is preferably 55%, and further 53%, 51%, 50%, 49%, 48%, 47%, 46% , 45%, 44%, 43% are more preferred. By making the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ] in the above range, a desired optical constant can be achieved.

In addition, in the optical glass of the second embodiment, the mass ratio of the content of Nb ₂ O ₅ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [Nb ₂ O ₅ /(Nb ₂ The lower limit of O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.500, more preferably in the order of 0.5500, 0.600, 0.650, 0.700, 0.750, 0.800, 0.820, 0.840, and 0.850. In addition, the upper limit of the mass ratio is preferably 1.000, and more preferably in the order of 0.999, 0.998, 0.997, 0.996, and 0.995.

Further, in the optical glass of the second embodiment, the mass ratio of the content of ZrO ₂ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ [ZrO ₂ /(Nb ₂ O ₅ +TiO The lower limit of ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.05, more preferably in the order of 0.07, 0.09, 0.11, 0.13, 0.15, 0.17, and 0.18. In addition, the upper limit of the mass ratio is preferably 0.40, and more preferably in the order of 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, and 0.32. By setting this mass ratio to the above-mentioned range, the Abbe number νd and the relative partial dispersion Pg,F can be controlled.

Furthermore, in the optical glass of the second embodiment, the mass ratio of the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The lower limit of [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.400, more preferably 0.450, 0.500, 0.550, 0.600, The order of 0.650, 0.670, 0.680, 0.690, 0.700 is more preferable. In addition, the upper limit of the mass ratio is preferably 1.000, and more preferably in the order of 0.980, 0.960, 0.940, 0.920, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, and 0.840. By setting this mass ratio to the above-mentioned range, the Abbe number νd and the relative partial dispersion Pg,F can be controlled.

In the optical glass of the second embodiment, the upper limit of the content of Li ₂ O is preferably 10%, and more preferably 9%, 8%, 7%, and 6% in the order. The lower limit of the content of Li ₂ O is preferably 0%, and more preferably in the order of 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, and 4.0%. By setting the content of Li ₂ O to the above range, the increase in relative partial dispersion Pg,F can be suppressed, and the chemical durability, weather resistance, and stability during reheating can be maintained.

In the optical glass of the second embodiment, the upper limit of the content of Na ₂ O is preferably 30%, and more preferably in the order of 25%, 23%, 21%, 19%, 17%, 15%, and 13%. The lower limit of the content of Na ₂ O is preferably 0%, and more preferably in the order of 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8%. By making content of _Na2O into the said range, relative partial dispersion Pg,F can be reduced.

In the optical glass of the second embodiment, the upper limit of the content of K ₂ O is preferably 30%, and further increased in the order of 25%, 20%, 15%, 10%, 8%, 6%, 4%, and 2% Preferred. The lower limit of the content of K ₂ O is preferably 0%, and more preferably in the order of 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%. By making content of _K2O into the said range, the thermal stability of glass can be improved.

In the optical glass of the second embodiment, the upper limit of the content of Cs ₂ O is preferably 10%, and more preferably in the order of 8%, 6%, 5%, 4%, 3%, 2%, and 1%. The lower limit of the content of Cs ₂ O is preferably 0%. The content of Cs ₂ O may also be 0%.

Cs ₂ O has the effect of improving the thermal stability of glass, but when the content thereof increases, chemical durability and weather resistance decrease. And there is a risk of increased proportion. Therefore, it is preferable that each content of _Cs2O is the said range.

In the optical glass of the second embodiment, the upper limit of the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O [Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O] is preferably 40 %, more preferably in the order of 35%, 30%, 28%, 26%, 24%, 22%, 21%, 20%, and 19%. The lower limit of the total content [Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O] is preferably 3%, and further 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14% The order of % is more preferred. By making the total content [Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O] in the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature can be lowered.

In addition, in the optical glass of the second embodiment, the mass ratio of the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O to the total content of SiO ₂ , P ₂ O ₅ and B ₂ O ₃ The upper limit of [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )] is preferably 5.000, more preferably 3.000, 2.000, 1.500, 1.300, The order of 1.100, 1.000, 0.900, 0.800, 0.780, 0.760, 0.740, 0.720, 0.700, 0.680, 0.660, 0.640, 0.620, 0.600 is more preferred. In addition, the lower limit of the mass ratio is preferably 0.100, and more preferably in the order of 0.200, 0.300, 0.350, 0.400, 0.420, 0.440, 0.460, and 0.480. When this mass ratio is too low, there is a possibility that the solubility may be deteriorated and the relative partial dispersion Pg,F may increase, and if it is too high, there is a possibility that the glass stability may be lowered.

Further, in the optical glass of the second embodiment, the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O is relative to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The upper limit of the mass ratio of [(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 4.000, and further 3.000, The order of 2.000, 1.000, 0.900, 0.800, 0.750, 0.700, 0.650, 0.600, 0.550, 0.520, 0.500, 0.490, 0.480, 0.470 is more preferred. In addition, the lower limit of the mass ratio is preferably 0.100, and more preferably in the order of 0.150, 0.200, 0.240, 0.260, 0.280, 0.300, 0.310, 0.320, and 0.330. When the mass ratio is too low, the relative partial dispersion Pg,F may increase and the transmittance may deteriorate, and if it is too high, the glass stability may be reduced.

Furthermore, in the optical glass of the second embodiment, the mass ratio of the content of P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O, K ₂ O and Nb ₂ O ₅ [P ₂ O ₅ /(Li The upper limit of ₂ O+Na ₂ O+K ₂ O+Nb ₂ O ₅ )] is preferably 0.500, further 0.300, 0.100, 0.090, 0.080, 0.050, 0.030, 0.020, 0.015, 0.013, 0.011, 0.010, 0.009, 0.008 order is more preferred. The mass ratio [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Nb ₂ O ₅ )] may be zero. By making this mass ratio into the said range, the rise of ΔPg,F' can be suppressed.

In the optical glass of the second embodiment, the content of P ₂ O ₅ is relative to the content of Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, Nb ₂ O ₅ , TiO ₂ , WO ₃ and Bi ₂ O ₃ The upper limit of the mass ratio of the total content [P ₂ O ₅ /(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] is preferably 0.500 , more preferably in the order of 0.300, 0.100, 0.090, 0.080, 0.050, 0.030, 0.020, 0.015, 0.013, 0.011, 0.010, 0.009, and 0.008. The mass ratio may also be zero. By making this mass ratio into the said range, the rise of ΔPg,F' can be suppressed.

In the optical glass of the second embodiment, the upper limit of the content of MgO is preferably 20%, and furthermore, it is 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in this order More preferred. In addition, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

In the optical glass of the second embodiment, the upper limit of the content of CaO is preferably 20%, and the upper limit is 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in this order. More preferred. In addition, the lower limit of the content of CaO is preferably 0%. The content of CaO may also be 0%.

In the optical glass of the second embodiment, the upper limit of the content of SrO is preferably 20%, and the upper limit is 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in this order. More preferred. In addition, the lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

In the optical glass of the second embodiment, the upper limit of the content of BaO is preferably 20%, and the upper limit of the content of BaO is further 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in this order. More preferred. In addition, when the content of BaO is preferably small, the content of BaO may be 0%.

MgO, CaO, SrO, and BaO are all glass components having the effect of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, the specific gravity increases, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass decrease. Therefore, it is preferable that each content of these glass components is the said range, respectively.

In the optical glass of the second embodiment, the upper limit of the total content of MgO and CaO [MgO+CaO] is preferably 20%, and further 15%, 10%, 8%, 7%, 6%, 5%, 4% , 3%, and 2% are more preferred. In addition, the lower limit of the total content [MgO+CaO] is preferably 0%. The total content [MgO+CaO] may also be 0%. By making the total content [MgO+CaO] into the above range, thermal stability can be maintained without preventing high dispersion.

In the optical glass of the second embodiment, the upper limit of the content of ZnO is preferably 20%, and the upper limit is further 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in this order More preferred. In addition, the lower limit of the content of ZnO is preferably 0%. The content of ZnO may be 0%.

ZnO is a glass component that has the effect of improving the thermal stability of glass. However, when the content of ZnO is too large, the specific gravity increases. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining a desired optical constant, the content of ZnO is preferably within the above range.

In the optical glass of the second embodiment, the upper limit of the total content of MgO, CaO, SrO, BaO, and ZnO [MgO+CaO+SrO+BaO+ZnO] is preferably 20%, and more preferably 15%, 10%, and 8% , 7%, 6%, 5%, 4%, 3%, 2% are more preferred. In addition, the lower limit of the total content is preferably 0%. The total content may also be 0%. By making this total content into the said range, the increase of specific gravity can be suppressed, and thermal stability can be maintained, without hindering high dispersion|distribution.

In the optical glass of the second embodiment, the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O [(MgO+CaO The upper limit of +SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O+Cs ₂ O)] is preferably 20.000, more The order of 0.800, 0.700, 0.600, 0.500, 0.400, 0.300, 0.200, 0.100, 0.050, 0.030 is more preferred. In addition, the lower limit of the mass ratio is preferably 0. The mass ratio may also be zero.

In the optical glass of the second embodiment, the upper limit of the content of La ₂ O ₃ is preferably 20%, and more preferably 15%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, 3% The order of % and 2% is more preferable. In addition, the lower limit of the content of La ₂ O ₃ is preferably 0%, and the content of La ₂ O ₃ may be 0%. By making the content of La ₂ O ₃ into the above-mentioned range, a desired optical constant can be achieved, an increase in specific gravity can be suppressed, and the relative partial dispersion Pg,F can be reduced.

In the optical glass of the second embodiment, the upper limit of the content of Y ₂ O ₃ is preferably 20%, and more preferably 18%, 16%, 15%, 14%, 13%, 12%, 10%, 9%, 8% The order of % is more preferred. In addition, the lower limit of the content of Y ₂ O ₃ is preferably 0%.

When the content of Y ₂ O ₃ becomes too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. Therefore, it is preferable that content _{of Y2O3} is the said range from a viewpoint of suppressing the fall of the thermal stability of glass.

In the optical glass of the second embodiment, the upper limit of the content of Ta ₂ O ₅ is preferably 20%, and further 15%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, 3% The order of % and 2% is more preferable. In addition, the lower limit of the content of Ta ₂ O ₅ is preferably 0%.

Ta ₂ O ₅ is a glass component that has an effect of improving the thermal stability of glass, and is a component that causes a decrease in relative partial dispersion Pg,F. On the other hand, when the content of Ta ₂ O ₅ is increased, the thermal stability of the glass is lowered, and the melting residue of the glass raw material tends to occur when the glass is melted. And the specific gravity rises. Also, the cost of raw materials increases. Therefore, the content of Ta ₂ O ₅ is preferably within the above range.

In the optical glass of the second embodiment, the content of Sc ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Sc ₂ O ₃ is preferably 0%.

In the optical glass of the second embodiment, the content of HfO ₂ is preferably 2% or less. In addition, the lower limit of the content of HfO ₂ is preferably 0%, and more preferably in the order of 0.05% and 0.1%.

Sc ₂ O ₃ and HfO ₂ are expensive components having an effect of improving the high dispersibility of glass. Therefore, each content of Sc ₂ O ₃ and HfO ₂ is preferably within the above range.

In the optical glass of the second embodiment, the content of Lu ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Lu ₂ O ₃ is preferably 0%.

Although Lu ₂ O ₃ has the effect of improving the high dispersibility of glass, it is also a glass component that increases the specific gravity of glass due to its large molecular weight. Therefore, the content of Lu ₂ O ₃ is preferably within the above range.

In the optical glass of the second embodiment, the content of GeO ₂ is preferably 2% or less. In addition, the lower limit of the content of GeO ₂ is preferably 0%.

GeO ₂ has the effect of improving the high dispersibility of glass, but is an extremely expensive component among commonly used glass components. Therefore, the content of GeO ₂ is preferably within the above-mentioned range from the viewpoint of reducing the production cost of glass.

In the optical glass of the second embodiment, the content of Gd ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Gd ₂ O ₃ is preferably 0%.

When the content of Gd ₂ O ₃ becomes too large, the thermal stability of the glass decreases. In addition, when the content of Gd ₂ O ₃ becomes too large, the specific gravity of the glass increases. In addition, raw material costs have risen. Therefore, the content of Gd ₂ O ₃ is preferably within the above-mentioned range from the viewpoint of keeping the thermal stability of the glass well and suppressing an increase in specific gravity.

In the optical glass of the second embodiment, the content of Yb ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Yb ₂ O ₃ is preferably 0%.

Yb ₂ O ₃ has a larger molecular weight than La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , and therefore increases the specific gravity of glass. Therefore, it is preferable to reduce the content of Yb ₂ O ₃ in order to suppress an increase in the specific gravity of the glass.

In addition, when the content of Yb ₂ O ₃ is too large, the thermal stability of the glass decreases. The content of Yb ₂ O ₃ is preferably within the above-mentioned range from the viewpoints of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.

The optical glass of the second embodiment is preferably mainly composed of the above-mentioned glass components, that is, SiO ₂ , Nb ₂ O ₅ , ZrO ₂ as essential components, B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , TiO ₂ , WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Ta ₂ O _5. It is composed of Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , Gd ₂ O ₃ and Yb ₂ O ₃ , and the total content of the glass components is preferably more than 95%, more preferably more than 98%, still more preferably More than 99%, more preferably more than 99.5%.

In addition, although it is preferable that the optical glass of 2nd Embodiment consists basically of the said glass component, you may contain other components in the range which does not inhibit the effect of 2nd invention. In addition, in the second invention, the inclusion of unavoidable impurities is not excluded.

(other ingredients)

The optical glass of the second embodiment may contain a small amount of Sb ₂ O ₃ , CeO ₂ or the like as a clarifying agent. The total amount of the clarifying agent (external ratio addition amount) is preferably 0% or more and less than 1%, and more preferably 0% or more and 0.5% or less.

The external ratio addition amount refers to the value shown by the weight percentage of the addition amount of the clarifying agent when the total content of all the glass components other than the clarifying agent is 100%.

The above-mentioned optical glass can obtain high transmittance in a wide range of the visible region. In order to utilize such a feature effectively, it is preferable not to contain a coloring element. As a coloring element, Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, V, etc. are illustrated. Any element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably not substantially contained.

In addition, Ga, Te, Tb, etc. are components that do not need to be introduced, and are also expensive components. Therefore, the ranges of the contents of Ga ₂ O ₃ , TeO ₂ , and TbO ₂ expressed in mass % are all preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and still more preferably 0 to 0.005%, more preferably 0 to 0.001%, and particularly preferably not substantially contained.

(glass properties)

<Refractive index nd>

In the optical glass of the second embodiment, the refractive index nd is preferably 1.70 to 1.90. The refractive index nd can be set to 1.72 to 1.85, or 1.73 to 1.83. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the optical glass of the second embodiment is preferably 0.6500, and more preferably in the order of 0.6400, 0.6300, 0.6200, 0.6100, 0.6050, 0.6040, 0.6030, 0.6020, 0.6010, and 0.6000. In addition, the relative partial dispersion Pg,F is preferably as low as possible, and the lower limit thereof is preferably 0.5500, and may further be 0.5600, 0.5700, 0.5800, 0.5840, 0.5850, 0.5870, 0.5890, 0.5900, 0.5910, 0.5920, 0.5930, and 0.5940.

By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained. The relative partial dispersion Pg will be relatively improved, and the components of F are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ and Ta ₂ O ₅ . The relative partial dispersion Pg will be relatively reduced, and the components of F are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. By appropriately adjusting the content of these components, the relative partial dispersion Pg,F can be controlled.

In the optical glass of the second embodiment, the relative partial dispersion Pg,F preferably satisfies the following formula (2-1), more preferably the following formula (2-2), and further preferably the following formula (2-3) , It is particularly preferable to satisfy the following formula (2-4). By making the relative partial dispersion Pg,F satisfy the following formula, an optical glass suitable for secondary chromatic aberration correction can be provided.

Pg,F≤-0.00286×νd+0.68900...(2-1)

Pg,F≤-0.00286×νd+0.68800...(2-2)

Pg,F≤-0.00286×νd+0.68600...(2-3)

Pg,F≤-0.00286×νd+0.68400...(2-4)

In addition, the upper limit of ΔPg,F' of the optical glass of the second embodiment is preferably 0.0000, more preferably -0.0010, -0.0020, -0.0030, -0.0040, -0.0050, and -0.0060 in the order. The lower ΔPg,F' is more preferable, and the lower limit thereof is preferably -0.0200, and more preferably -0.0180, -0.0160, -0.0140, -0.0130, and -0.0120. ΔPg is relatively increased, and the components of F' are P ₂ O ₅ , B ₂ O ₃ , and TiO ₂ . ΔPg is relatively decreased, and the components of F' are Nb ₂ O ₅ , La ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , Li ₂ O, Na ₂ O, and K ₂ O. By appropriately adjusting the content of these components, ΔPg,F' can be controlled.

<Specific gravity of glass>

The specific gravity of the optical glass of the second embodiment is preferably 3.60 or less, more preferably 3.55 or less, 3.50 or less, 3.48 or less, 3.46 or less, 3.45 or less, 3.44 or less, 3.43 or less, 3.42 or less, 3.41 or less, and 3.40 or less in order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.00. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the optical glass of the second embodiment is preferably 700°C, and more preferably 670°C, 650°C, 630°C, 620°C, 610°C, 600°C, and 590°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 450°C, more preferably 470°C, 500°C, 510°C, 520°C, 530°C, and 540°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

＜Transparency of glass＞

The light transmittance of the optical glass of the second embodiment can be evaluated by the coloring degrees λ70 and λ5.

For a glass sample with a thickness of 10.0 mm±0.1 mm, the spectral transmittance was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance reached 70% was set as λ70, and the wavelength at which the external transmittance reached 5% was set as λ5 .

λ70 of the optical glass of the second embodiment is preferably 500 nm or less, more preferably 470 nm or less, still more preferably 450 nm or less, and still more preferably 430 nm or less. In addition, λ5 is preferably 400 nm or less, more preferably 380 nm or less, and further preferably 370 nm or less. The coloring degrees λ70 and λ5 can be controlled by adjusting the contents of ZrO ₂ , Nb ₂ O ₅ , TiO ₂ , SiO ₂ , and B ₂ O ₃ .

<Stability during reheating>

It is preferable that the optical glass of the second embodiment does not become cloudy when heated for 5 minutes in a test furnace set to a temperature 200 to 220° C. higher than the glass transition temperature Tg. More preferably, the number of crystals precipitated by the above heating is 100 or less per one sample. The stability during reheating can be controlled by adjusting the contents of Nb ₂ O ₅ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and P ₂ O ₅ .

Stability upon reheating was measured as described below. After heating a glass sample with a size of 10 mm × 10 mm × 7.5 mm in a test furnace set to a temperature 200 to 220° C. higher than the glass transition temperature Tg of the glass sample for 5 minutes, it was observed with an optical microscope (observation magnification). : 40 to 200 times) to measure the number of crystals per sample. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The manufacture of the optical glass of 2nd Embodiment can be set as the same as that of Embodiment of 1st invention. In addition, about manufacture of an optical element etc., it can also be made the same as that of embodiment of 1st invention.

"Third Invention"

[Background Art of the Third Invention]

Patent Document 3-1 discloses an optical glass having a refractive index nd of 1.674 or more and an Abbe number νd of 30.2 or more. However, the optical glass described in Patent Document 3-1 has low homogeneity, and does not satisfy the conditions of low specific gravity and low Pg,F. Therefore, optical glasses having desired optical constants and higher performance are required.

[Prior Art Document of the Third Invention]

Patent Literature

Patent Document 3-1: Japanese Patent Laid-Open No. 2017-105702

[Content of the third invention]

[Problems to be solved by the third invention]

In order to reduce the power consumption when driving the autofocus function, there is a demand for weight reduction of the optical elements mounted in the optical system of the autofocus method. If the specific gravity of glass can be reduced, the weight of optical elements such as lenses can be reduced. In addition, in order to correct the chromatic aberration, the relative partial dispersion Pg,F is required to be small.

Therefore, the object of the third invention is to provide an optical glass having a desired optical constant, a relatively small specific gravity, and a small relative partial dispersion Pg,F, and an optical element formed of the above-mentioned optical glass.

[way of solving the problem]

The gist of the third invention is as follows.

(1) An optical glass wherein,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

And the optical glass satisfies one or more of the following (a) and (b):

(a) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 9 mass %,

(b) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.6, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

(2) An optical glass wherein,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

The mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is less than 0.3,

And the optical glass satisfies one or more of the following (c) and (d):

(c) the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %,

(d) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

(3) An optical glass wherein,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

The mass ratio of the content of ZnO to the content of Nb ₂ O ₅ [ZnO/Nb ₂ O ₅ ] is less than 0.14,

And the optical glass satisfies one or more of the following (e) and (f):

(e) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %,

(f) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

(4) An optical glass whose Abbe number νd is 30 to 36,

The specific gravity is below 3.19,

The deviation ΔPg,F relative to the partial dispersion Pg,F is 0.0015 or less.

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

[Effect of the third invention]

According to the third invention, it is possible to provide an optical glass having a desired optical constant, a relatively small specific gravity, and a small relative partial dispersion Pg,F, and an optical element formed of the above-mentioned optical glass.

[Specific embodiment of the third invention]

Hereinafter, the optical glass of 3rd invention is demonstrated as 3-1st Embodiment, 3-2nd Embodiment, 3-3rd Embodiment, and 3-4th Embodiment. In addition, the function and effect of each glass component in Embodiment 3-2, 3-3, and 3-4 are the same as those of each glass component in Embodiment 3-1. Therefore, in the 3-2nd, 3-3rd, and 3-4th embodiments, the matters overlapping the descriptions related to the 3-1st embodiment are appropriately omitted.

In the 3-1, 3-2, 3-3, and 3-4 embodiments, the relative partial dispersion Pg,F uses g-rays, F-rays, and C-rays. The respective refractive indices ng, nF, and nC are as follows expressed as described.

Pg,F=(ng-nF)/(nF-nC)

In a plane in which the horizontal axis is Abbe's number νd and the vertical axis is relative partial dispersion Pg,F, the normal is represented by the following formula.

Pg,F(0)=0.6483-(0.0018×νd)

In addition, the deviation ΔPg,F of the relative partial dispersion Pg,F with respect to the normal line is expressed as follows.

ΔPg,F=Pg,F-Pg,F(0)

3-1 Embodiment

In the optical glass of the 3-1 embodiment,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

In addition, it satisfies one or more of the following (a) and (b):

(a) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 9 mass %,

(b) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.6, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

In the optical glass of the 3-1st embodiment, the mass ratio [SiO ₂ /Nb ₂ O ₅ ] of the content of SiO ₂ to the content of Nb ₂ O ₅ is greater than 1.05. The lower limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 1.09, more preferably 1.11, 1.15, and 1.17 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By setting the mass ratio [SiO ₂ /Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be reduced while maintaining desired optical constants (refractive index nd, Abbe number νd).

In the optical glass of the 3-1st embodiment, the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] of the content of ZrO ₂ to the content of Nb ₂ O ₅ is greater than 0.25. The lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.26, more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, and 0.315 in this order. In addition, the upper limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.65, and more preferably 0.61, 0.57, and 0.53 in this order. By setting the lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] to the above range, the relative partial dispersion Pg,F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the 3-1st embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is greater than 0.65. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 0.66, and more preferably in the order of 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 . In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.20, and more preferably 1.14, 1.12, and 1.10 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the thermal stability of the glass can be maintained and a desired optical constant can be obtained.

In the optical glass of the 3-1st embodiment, the total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10%. The upper limit of the total content [TiO ₂ +BaO] is preferably 8.0%, and more preferably in the order of 7.8%, 7.6%, and 7.4%. In addition, the lower limit of the total content [TiO ₂ +BaO] is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. By setting the upper limit of the total content [TiO ₂ +BaO] to the above range, the relative partial dispersion Pg,F can be reduced, and the specific gravity of the glass can be reduced.

The optical glass of the 3-1st embodiment satisfies one or more of the following (a) and (b):

(a) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 9%,

(b) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.6, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

That is, in the optical glass of the 3-1st embodiment, the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O may be more than 9%. The lower limit of the total content of R ₂ O is preferably 15.0%, and more preferably 15.5%, 16.0%, and 16.5% in the order. In addition, the upper limit of the total content of R ₂ O is preferably 22.0%, more preferably 21.7%, 21.4%, and 21.1% in the order. By making the total content R ₂ O into the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

Moreover, in the optical glass of the 3-1st embodiment, the total content of R'O relative to the total content of Li ₂ O, Na ₂ O and K ₂ O, R ₂ O and the total content of MgO, CaO, SrO and BaO , the mass ratio [R ₂ O/(R ₂ O+R'O] of the total content of R ₂ O can be greater than 0.6. The lower limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 0.80, More preferably in the order of 0.82, 0.84, 0.86. In addition, the upper limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 0.95, and more preferably in the order of 0.98, 0.99, and 1.00. By When the mass ratio [R ₂ O/(R ₂ O+R'O)] is in the above range, the specific gravity of the glass can be lowered and the stability of the glass during reheating can be maintained.

In the optical glass of the 3-1st embodiment, the mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably Less than 0.3, the upper limit thereof is more preferably in the order of 0.25, 0.20, and 0.15. In addition, the lower limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0, and more preferably 0.05, 0.07, and 0.10 in the order. The mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] may be zero. By setting the upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glass of the 3-1st embodiment, the mass ratio [ZnO/Nb ₂ O ₅ ] of the content of ZnO to the content of Nb ₂ O ₅ is preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, and 0.105 . In addition, the lower limit of the mass ratio [ZnO/Nb ₂ O ₅ ] is preferably 0, and more preferably 0.02, 0.05, and 0.07 in this order. The mass ratio [ZnO/Nb ₂ O ₅ ] may be zero. By setting the upper limit of the mass ratio [ZnO/Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be lowered, and a desired optical constant can be obtained.

The content and ratio of the glass components other than the above in the optical glass of the 3-1st embodiment will be described in detail below.

In the optical glass of the 3-1st embodiment, the lower limit of the content of SiO ₂ is preferably 25%, and more preferably in the order of 28%, 30%, and 32%. In addition, the upper limit of the content of SiO ₂ is preferably 45%, and more preferably in the order of 43%, 41%, and 39%. By making content of _SiO2 into the said range, the specific gravity of glass can be lowered|hung, stability improvement at the time of glass reheating, and a desired optical constant can be acquired.

In the optical glass of the 3-1st embodiment, the upper limit of the content of B ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of B ₂ O ₃ is preferably 0%, and more preferably in the order of 0.2%, 0.4%, and 0.6%. The content of B ₂ O ₃ may be 0%. By making content _of B2O3 into the said range, the specific gravity of glass can be lowered| _hung , and the thermal stability of glass can be improved.

In the optical glass of the 3-1st embodiment, the upper limit of the total content [SiO ₂ +B ₂ O ₃ ] of SiO ₂ and B ₂ O ₃ is preferably 45%, and furthermore, 43%, 41%, and 39% in the order of More preferred. In addition, the lower limit of the content of the total content [SiO ₂ +B ₂ O ₃ ] is preferably 25%, and more preferably in the order of 28%, 30%, and 32%. By making the total content [SiO ₂ +B ₂ O ₃ ] in the above range, the specific gravity of the glass can be lowered, the thermal stability of the glass can be improved, and a desired optical constant can be obtained.

In the optical glass of the 3-1st embodiment, the upper limit of the content of P ₂ O ₅ is preferably 1.5%, and more preferably 1.3%, 1.1%, and 0.9% in the order. In addition, the lower limit of the content of P ₂ O ₅ is preferably 0%, and more preferably in the order of 0.1%, 0.2%, and 0.3%. _The content of _P2O5 may be 0%. By _making content of _P2O5 into the said range, the increase of relative partial dispersion Pg,F can be suppressed, and the thermal stability of glass can be maintained.

In the glass of the 3-1st embodiment, the upper limit of the content of Al ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. The content of Al ₂ O ₃ may be 0%. _{Devitrification} resistance and thermal stability of glass can be maintained by making content of _Al2O3 into the said range.

In the optical glass of the 3-1st embodiment, the upper limit of the content of TiO ₂ is preferably 10%, and more preferably 9.5%, 9.0%, and 8.5% in the order. The lower limit of the content of TiO ₂ is preferably 0%. The content of _TiO2 may also be 0%. By making content of _TiO2 into the said range, a desired optical constant can be achieved, and the raw material cost of glass can be reduced.

In the optical glass of the 3-1st embodiment, the lower limit of the content of Nb ₂ O ₅ is preferably 18%, and more preferably in the order of 20%, 22%, and 24%. In addition, the upper limit of the content of Nb ₂ O ₅ is preferably 38%, and more preferably in the order of 35%, 33%, and 31%. By setting the content of Nb ₂ O ₅ to the above range, a desired optical constant can be achieved, an increase in specific gravity can be suppressed, and the relative partial dispersion Pg,F can be reduced.

In the optical glass of the 3-1st embodiment, the lower limit of the total content of TiO ₂ and Nb ₂ O ₅ [TiO ₂ +Nb ₂ O ₅ ] is preferably 25%, and the lower limit is further 29%, 30%, and 31% in this order More preferred. In addition, the upper limit of the content of the total content [TiO ₂ +Nb ₂ O ₅ ] is preferably 42%, and more preferably in the order of 40%, 38%, and 36%. By setting the total content [TiO ₂ +Nb ₂ O ₅ ] to the above range, a desired optical constant can be achieved.

In the glass of the 3-1st embodiment, the upper limit of the content of WO ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. The content of WO ₃ may also be 0%. By making the upper limit of the content of WO ₃ into the above range, the transmittance can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In Embodiment 3-1, the upper limit of the content of Bi ₂ O ₃ is preferably 5%, and more preferably 4%, 3%, and 2% in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of Bi ₂ O ₃ is preferably 0%. By making the content of Bi ₂ O ₃ into the above range, the thermal stability of the glass can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In the glass of the 3-1st embodiment, the lower limit of the content of ZrO ₂ is preferably 5%, and more preferably in the order of 6%, 7%, and 8%. In addition, the upper limit of the content of ZrO ₂ is preferably 15%, and more preferably in the order of 14%, 13%, and 12%. By setting the content of ZrO ₂ to the above range, a desired optical constant can be achieved and the relative partial dispersion Pg,F can be reduced.

In the glass of the 3-1st embodiment, the upper limit of the content of Li ₂ O is preferably 10%, and more preferably 9%, 8%, and 7% in the order. The lower limit of the content of Li ₂ O is preferably 2%, and more preferably in the order of 3%, 4%, and 5%. By setting the content of Li ₂ O to the above-mentioned range, a desired optical constant can be achieved, and chemical durability, weather resistance, and stability during reheating can be maintained.

In the glass of the 3-1st embodiment, the upper limit of the content of Na ₂ O is preferably 18%, and more preferably in the order of 15%, 14%, and 13%. The lower limit of the content of Na ₂ O is preferably 8%, and more preferably in the order of 9%, 10%, and 11%.

In the glass of the 3-1st embodiment, the upper limit of the content of K ₂ O is preferably 4.0%, and more preferably 3.0%, 2.5%, and 2.0% in the order. The lower limit of the content of K ₂ O is preferably 0%, and more preferably in the order of 0.2%, 0.4%, and 0.6%. The content of K ₂ O may also be 0%.

Na ₂ O and K ₂ O are components that lower the relative partial dispersion Pg,F, and have the effect of lowering the liquidus temperature and improving the thermal stability of the glass, but when their content increases, chemical durability and weather resistance decrease. Therefore, the respective contents of Na ₂ O and K ₂ O are preferably within the above ranges.

In the glass of the 3-1st embodiment, the upper limit of the content of Cs ₂ O is preferably 5%, and more preferably in the order of 3%, 1%, and 0.5%. The lower limit of the content of Cs ₂ O is preferably 0%.

Cs ₂ O has the effect of improving the thermal stability of glass, but when the content thereof increases, chemical durability and weather resistance decrease. Therefore, it is preferable that each content of _Cs2O is the said range.

In the glass of the 3-1st embodiment, the upper limit of the content of MgO is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. In addition, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

In the glass of the 3-1st embodiment, the upper limit of the content of CaO is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. In addition, the lower limit of the content of CaO is preferably 0%. The content of CaO may also be 0%.

In the glass of the 3-1st embodiment, the upper limit of the content of SrO is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. In addition, the lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

In the optical glass of the 3-1st embodiment, the upper limit of the content of BaO is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. The lower limit of the content of BaO is preferably 0%. The content of BaO may also be 0%. By making content of BaO into the said range, the increase of specific gravity can be suppressed.

MgO, CaO, SrO, and BaO are all glass components having the effect of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, the specific gravity increases, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass decrease. Therefore, it is preferable that each content of these glass components is the said range, respectively.

In the glass of the 3-1st embodiment, the upper limit of the total content R'O of MgO, CaO, SrO and BaO is preferably 10%, more preferably 4%, 2%, and 1% in the order. In addition, the lower limit of the total content R'O is preferably 0%. The total content of R'O may also be 0%. By making the total content R'O into the above-mentioned range, an increase in specific gravity can be suppressed, and thermal stability can be maintained without hindering high dispersion.

In the glass of the 3-1st embodiment, the upper limit of the content of ZnO is preferably 10%, and more preferably in the order of 3%, 2.5%, and 2%. In addition, the lower limit of the content of ZnO is preferably 0%.

ZnO is a glass component that has the effect of improving the thermal stability of glass. However, when the content of ZnO is too large, the specific gravity increases. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining a desired optical constant, the content of ZnO is preferably within the above range.

In the optical glass of the 3-1st embodiment, the upper limit of the content of La ₂ O ₃ is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. In addition, the lower limit of the content of La ₂ O ₃ is preferably 0%, and the content of La ₂ O ₃ may be 0%. By setting the content of La ₂ O ₃ to be in the above range, a desired optical constant can be achieved, an increase in specific gravity can be suppressed, and the relative partial dispersion Pg,F can be reduced.

In the glass of the 3-1st embodiment, the upper limit of the content of Y ₂ O ₃ is preferably 10%, and more preferably in the order of 5%, 3%, and 1%. In addition, the lower limit of the content of Y ₂ O ₃ is preferably 0%.

When the content of Y ₂ O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. Therefore, it is preferable that content _{of Y2O3} is the said range from a viewpoint of suppressing the fall of the thermal stability of glass.

In the glass of the 3-1st embodiment, the upper limit of the content of Ta ₂ O ₅ is preferably 20%, and more preferably in the order of 10%, 5%, 3%, 1%, and 0.5%. In addition, the lower limit of the content of Ta ₂ O ₅ is preferably 0%.

Ta ₂ O ₅ is a glass component that has an effect of improving the thermal stability of glass, and is a component that causes a decrease in relative partial dispersion Pg,F. On the other hand, when the content of Ta ₂ O ₅ is increased, the thermal stability of the glass is lowered, and the melting residue of the glass raw material tends to occur when the glass is melted. In addition, the specific gravity increased. Therefore, the content of Ta ₂ O ₅ is preferably within the above range.

In the glass of the 3-1st embodiment, the content of Sc ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Sc ₂ O ₃ is preferably 0%.

In the glass of the 3-1st embodiment, the content of HfO ₂ is preferably 2% or less. In addition, the lower limit of the content of HfO ₂ is preferably 0%, and more preferably in the order of 0.05% and 0.1%.

Sc ₂ O ₃ and HfO ₂ are expensive components having an effect of improving the high dispersibility of glass. Therefore, each content of Sc ₂ O ₃ and HfO ₂ is preferably within the above range.

In the glass of the 3-1st embodiment, the content of Lu ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Lu ₂ O ₃ is preferably 0%.

Although Lu ₂ O ₃ has the effect of improving the high dispersibility of glass, it is also a glass component that increases the specific gravity of glass due to its large molecular weight. Therefore, the content of Lu ₂ O ₃ is preferably within the above range.

In the glass of the 3-1st embodiment, the content of GeO ₂ is preferably 2% or less. In addition, the lower limit of the content of GeO ₂ is preferably 0%.

GeO ₂ has the effect of improving the high dispersibility of glass, but is an extremely expensive component among commonly used glass components. Therefore, the content of GeO ₂ is preferably within the above-mentioned range from the viewpoint of reducing the production cost of glass.

In the glass of the 3-1st embodiment, the content of Gd ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Gd ₂ O ₃ is preferably 0%.

When the content of Gd ₂ O ₃ becomes too large, the thermal stability of the glass decreases. In addition, when the content of Gd ₂ O ₃ becomes too large, the specific gravity of the glass increases. Therefore, the content of Gd ₂ O ₃ is preferably within the above-mentioned range from the viewpoint of keeping the thermal stability of the glass well and suppressing an increase in specific gravity.

In the glass of the 3-1st embodiment, the content of Yb ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Yb ₂ O ₃ is preferably 0%.

Yb ₂ O ₃ has a larger molecular weight than La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , and therefore increases the specific gravity of glass. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a high-mass lens is incorporated into an autofocus-type imaging lens, power required for driving the lens during autofocusing increases, and battery consumption becomes severe. Therefore, it is preferable to reduce the content of Yb ₂ O ₃ in order to suppress an increase in the specific gravity of the glass.

In addition, when the content of Yb ₂ O ₃ is too large, the thermal stability of the glass decreases. The content of Yb ₂ O ₃ is preferably within the above-mentioned range from the viewpoints of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.

The glass of the 3-1st embodiment is preferably mainly composed of the above-mentioned glass components, that is, SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ , WO ₃ , and Bi ₂ O ₃ . , ZrO ₂ , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Ta ₂ O ₅ , Sc ₂ O ₃ , It is composed of HfO ₂ , Lu ₂ O ₃ , GeO ₂ , Gd ₂ O ₃ and Yb ₂ O ₃ , and the total content of the above glass components is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and even more More preferably more than 99.5%.

In addition, although it is preferable that the glass of 3-1st Embodiment consists basically of the said glass component, you may contain other components in the range which does not inhibit the effect of 3rd invention. In addition, in the third invention, the inclusion of unavoidable impurities is not excluded.

(other ingredients)

In addition to the above-mentioned components, the above-mentioned optical glass may contain a small amount of Sb ₂ O ₃ , CeO ₂ or the like as a clarifying agent. The total amount of the clarifying agent (external ratio addition amount) is preferably 0% or more and less than 1%, and more preferably 0% or more and 0.5% or less.

The external ratio addition amount refers to the value shown by the weight percentage of the addition amount of the clarifying agent when the total content of all the glass components other than the clarifying agent is 100%.

Pb, Cd, As, Th and the like are components that may cause environmental burdens. Therefore, the content of each of PbO, CdO, and ThO ₂ is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially free of PbO, CdO, and ThO ₂ .

The content of As ₂ O ₃ is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially free of As ₂ O ₃ .

In addition, the above-mentioned optical glass can obtain high transmittance in a wide range of the visible region. In order to utilize such a feature effectively, it is preferable not to contain a coloring element. As a coloring element, Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, V, etc. are illustrated. Any element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably not substantially contained.

In addition, Ga, Te, Tb, etc. are components that do not need to be introduced, and are also expensive components. Therefore, the ranges of the contents of Ga ₂ O ₃ , TeO ₂ , and TbO ₂ expressed in mass % are all preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and still more preferably 0 to 0.005%, more preferably 0 to 0.001%, and particularly preferably not substantially contained.

(glass properties)

<Refractive index nd>

In the optical glass of the 3-1st embodiment, the refractive index nd is preferably 1.69 to 1.76. The refractive index nd may be set to 1.695 to 1.755, or 1.70 to 1.75. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Abbé number νd>

In the optical glass of the 3-1st embodiment, it is preferable that Abbe's number νd is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

<Specific gravity of glass>

The specific gravity of the optical glass of the 3-1st embodiment is preferably 3.19 or less, more preferably 3.18 or less, 3.17 or less, and 3.16 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.05. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the optical glass according to the 3-1st embodiment is preferably 0.5950, and more preferably 0.5945, 0.5940, and 0.5935 in the order of 0.5945. In addition, the lower limit of the relative partial dispersion Pg,F is preferably 0.5780, and more preferably in the order of 0.5785, 0.5790, 0.5795, 0.5805, 0.5815, and 0.5830. By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained.

In addition, the upper limit of the deviation ΔPg,F of the relative partial dispersion Pg,F of the optical glass according to the 3-1st embodiment is preferably 0.0015, and more preferably 0.0012, 0.0010, and 0.0008 in the order of 0.0015. In addition, the lower limit of the deviation ΔPg,F is preferably -0.0060, more preferably -0.0048, -0.0045, -0.0042, -0.0040, -0.0035, -0.0025 in the order of

<Liquid phase temperature>

The liquidus temperature LT of the optical glass according to the 3-1st embodiment is preferably 1200°C or lower, more preferably 1190°C or lower, 1180°C or lower, and 1170°C or lower in this order. By making the liquidus temperature into the above-mentioned range, the melting and forming temperature of glass can be reduced, and as a result, the erosion of glass melting equipment (eg, crucible, stirring equipment for molten glass, etc.) in the melting process can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000°C. The liquidus temperature LT is determined according to the balance of the contents of all the glass components. Among them, the contents of SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like have a great influence on the liquidus temperature LT.

In addition, the liquidus temperature is determined as follows. Put 10cc (10ml) of glass into a platinum crucible, melt at 1250℃～1400℃ for 15～30 minutes, cool down to below the glass transition temperature Tg, put the glass together with the platinum crucible into a melting furnace at a given temperature and melt it. Hold for 2 hours. The temperature was kept at 1000°C or higher, the interval was set to 5°C or 10°C, the temperature was kept for 2 hours, and then cooled, and the presence or absence of crystals in the glass was observed with a 100-fold optical microscope. The lowest temperature at which no crystals were precipitated was set as the liquidus temperature.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the optical glass of the 3-1st embodiment is preferably 580°C, and more preferably 575°C, 570°C, and 565°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 510°C, and more preferably 515°C, 520°C, and 525°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

<Stability during reheating>

In the optical glass of the 3-1st embodiment, the number of crystals observed per 1 g is preferably 10 minutes at the glass transition temperature Tg and 140 to 250°C higher than the Tg for 10 minutes. 20 or less, more preferably 10 or less.

In addition, the stability at the time of reheating was measured as follows. A glass sample with a size of 1 cm x 1 cm x 0.8 cm was heated for 10 minutes in the first test furnace set to the glass transition temperature Tg of the glass sample, and further set to be higher than the glass transition temperature Tg of the glass sample. After heating in the second test furnace at a temperature of 140 to 250° C. for 10 minutes, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The manufacture of the optical glass of 3-1 Embodiment can be made the same as that of Embodiment of 1st invention. In addition, about manufacture of an optical element etc., it can also be made the same as that of embodiment of 1st invention.

Embodiment 3-2

In the optical glass of the 3-2nd embodiment,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

The mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is less than 0.3,

In addition, the optical glass satisfies one or more of the following (c) and (d):

(c) the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %,

(d) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

In the optical glass of the 3-2nd embodiment, the mass ratio [SiO ₂ /Nb ₂ O ₅ ] of the content of SiO ₂ to the content of Nb ₂ O ₅ is greater than 1.05. The lower limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 1.09, more preferably 1.11, 1.15, and 1.17 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By setting the mass ratio [SiO ₂ /Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be reduced while maintaining desired optical constants (refractive index nd, Abbe number νd).

In the optical glass of the 3-2nd embodiment, the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] of the content of ZrO ₂ to the content of Nb ₂ O ₅ is greater than 0.25. The lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.26, more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, and 0.315 in this order. In addition, the upper limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.65, and more preferably 0.61, 0.57, and 0.53 in this order. By setting the lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] to the above range, the relative partial dispersion Pg,F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the 3-2nd embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is greater than 0.65. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 0.66, and more preferably in the order of 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 . In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.20, and more preferably 1.14, 1.12, and 1.10 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the thermal stability of the glass can be maintained and a desired optical constant can be obtained.

In the optical glass of the 3-2nd embodiment, the total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10%. The upper limit of the total content [TiO ₂ +BaO] is preferably 8.0%, and more preferably in the order of 7.8%, 7.6%, and 7.4%. In addition, the lower limit of the total content [TiO ₂ +BaO] is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. By setting the upper limit of the total content [TiO ₂ +BaO] to the above range, the relative partial dispersion Pg,F can be reduced, and the specific gravity of the glass can be reduced.

In the optical glass of the 3-2nd embodiment, the mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is less than 0.3. The upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0.25, and more preferably 0.20 and 0.15 in this order. In addition, the lower limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0, and more preferably 0.05, 0.07, and 0.10 in the order. The mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] may be zero. By setting the upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

The optical glass of the 3-2 embodiment satisfies one or more of the following (c) and (d):

(c) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1%,

(d) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

That is, in the optical glass of the 3-2nd embodiment, the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O can be made larger than 1.1%. The total content of R ₂ O is preferably more than 9%, and the lower limit thereof is more preferably in the order of 15.0%, 15.5%, 16.0%, and 16.5%. In addition, the upper limit of the total content of R ₂ O is preferably 22.0%, more preferably 21.7%, 21.4%, and 21.1% in the order. By making the total content R ₂ O into the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

Moreover, in the optical glass of the 3-2nd embodiment, the total content of R ₂ O with respect to the total content of Li ₂ O, Na ₂ O and K ₂ O and the total content of R'O of MgO, CaO, SrO and BaO content, the mass ratio [R ₂ O/(R ₂ O+R'O)] of the total content of R ₂ O may be greater than 0.05. The mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably greater than 0.6, and the lower limit thereof is more preferably in the order of 0.80, 0.82, 0.84, and 0.86. In addition, the upper limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 1.00, and more preferably 0.99, 0.98, and 0.95 in this order. By making the mass ratio [R ₂ O/(R ₂ O+R'O)] in the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

In the optical glass of the 3-2nd embodiment, the mass ratio [ZnO/Nb ₂ O ₅ ] of the content of ZnO to the content of Nb ₂ O ₅ is preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, and 0.105 . In addition, the lower limit of the mass ratio [ZnO/Nb ₂ O ₅ ] is preferably 0, and more preferably 0.02, 0.05, and 0.07 in this order. The mass ratio [ZnO/Nb ₂ O ₅ ] may be zero. By setting the upper limit of the mass ratio [ZnO/Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be lowered, and a desired optical constant can be obtained.

In the optical glass of the 3-2nd embodiment, the content and ratio of the glass components other than the above may be the same as those of the 3-1st embodiment. In addition, about the glass characteristics in 3-2 embodiment, manufacture of optical glass, manufacture of an optical element, etc. can also be made the same as that of 3-1 embodiment.

Embodiment 3-3

In the optical glass of the 3-3rd embodiment,

The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05,

The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65,

The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass,

The mass ratio of the content of ZnO to the content of Nb ₂ O ₅ [ZnO/Nb ₂ O ₅ ] is less than 0.14,

In addition, the optical glass satisfies one or more of the following (e) and (f):

(e) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %,

(f) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

In the optical glass of the 3-3rd embodiment, the mass ratio [SiO ₂ /Nb ₂ O ₅ ] of the content of SiO ₂ to the content of Nb ₂ O ₅ is greater than 1.05. The lower limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 1.09, more preferably 1.11, 1.15, and 1.17 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By setting the mass ratio [SiO ₂ /Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be reduced while maintaining desired optical constants (refractive index nd, Abbe number νd).

In the optical glass of the 3-3rd embodiment, the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] of the content of ZrO ₂ to the content of Nb ₂ O ₅ is greater than 0.25. The lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.26, more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, and 0.315 in this order. In addition, the upper limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.65, and more preferably 0.61, 0.57, and 0.53 in this order. By setting the lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] to the above range, the relative partial dispersion Pg,F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the third-third embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is greater than 0.65. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 0.66, and more preferably in the order of 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 . In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.20, and more preferably 1.14, 1.12, and 1.10 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the thermal stability of the glass can be maintained and a desired optical constant can be obtained.

In the optical glass of the 3-3rd embodiment, the total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10%. The upper limit of the total content [TiO ₂ +BaO] is preferably 8.0%, and more preferably in the order of 7.8%, 7.6%, and 7.4%. In addition, the lower limit of the total content [TiO ₂ +BaO] is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. By setting the upper limit of the total content [TiO ₂ +BaO] to the above range, the relative partial dispersion Pg,F can be reduced, and the specific gravity of the glass can be reduced.

In the optical glass of the 3-3rd embodiment, the mass ratio [ZnO/Nb ₂ O ₅ ] of the content of ZnO to the content of Nb ₂ O ₅ is less than 0.14. The upper limit of Nb ₂ O ₅ is preferably 0.125, and more preferably in the order of 0.115 and 0.105. In addition, the lower limit of the mass ratio [ZnO/Nb ₂ O ₅ ] is preferably 0, and more preferably 0.02, 0.05, and 0.07 in this order. The mass ratio [ZnO/Nb ₂ O ₅ ] may be zero. By setting the upper limit of the mass ratio [ZnO/Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be lowered, and a desired optical constant can be obtained.

The optical glass of the 3-3rd embodiment satisfies one or more of the following (e) and (f):

(e) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1%,

(f) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

That is, in the optical glass of the 3-3rd embodiment, the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O can be made more than 1.1%. The total content of R ₂ O is preferably more than 9%, and the lower limit thereof is more preferably in the order of 15.0%, 15.5%, 16.0%, and 16.5%. In addition, the upper limit of the total content of R ₂ O is preferably 22.0%, more preferably 21.7%, 21.4%, and 21.1% in the order. By making the total content R ₂ O into the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

Moreover, in the optical glass of 3-3rd embodiment, with respect to the total content of Li ₂ O, Na ₂ O, and K ₂ O, R ₂ O, and the total content of MgO, CaO, SrO, and BaO, R'O content, the mass ratio [R ₂ O/(R ₂ O+R'O)] of the total content of R ₂ O may be greater than 0.05. The mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably greater than 0.6, and the lower limit thereof is more preferably in the order of 0.80, 0.82, 0.84, and 0.86. In addition, the upper limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 0.95, and more preferably 0.98, 0.99, and 1.00 in the order. By making the mass ratio [R ₂ O/(R ₂ O+R'O)] in the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

In the optical glass of the 3-3rd embodiment, the mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably Less than 0.3, the upper limit thereof is more preferably in the order of 0.25, 0.20, and 0.15. In addition, the lower limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0, and more preferably 0.05, 0.07, and 0.10 in the order. The mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] may be zero. By setting the upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glass of the 3-3rd embodiment, the content and ratio of the glass components other than those described above may be the same as those of the 3-1st embodiment. In addition, the glass characteristics in 3-3 embodiment, manufacture of optical glass, manufacture of an optical element, etc. can also be made the same as that of 3-1 embodiment.

Embodiments 3-4

The Abbe number νd of the optical glass according to the third-fourth embodiment is 30 to 36,

The specific gravity is below 3.19,

The deviation ΔPg,F relative to the partial dispersion Pg,F is 0.0015 or less.

In the optical glass of 3-4th Embodiment, Abbe's number (nu)d is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

In the optical glass of the 3rd-4th embodiment, the specific gravity is 3.19 or less. The specific gravity is preferably 3.18 or less, more preferably 3.17 or less, and more preferably 3.16 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.05.

In the optical glass of the 3rd-4th embodiment, the deviation ΔPg,F with respect to the partial dispersion Pg,F is 0.0015 or less. The upper limit of the deviation ΔPg,F is preferably 0.0012, and more preferably in the order of 0.0010 and 0.0008. In addition, the lower limit of the deviation ΔPg,F is preferably -0.0060, more preferably -0.0048, -0.0045, -0.0042, -0.0040, -0.0035, -0.0025 in the order.

In general, the relative partial dispersion Pg,F shows a tendency to decrease as the Abbe number νd increases. Therefore, in the third to fourth embodiments, the relative partial dispersion Pg,F is defined using the above-described ΔPg,F instead of the relative partial dispersion Pg,F itself. By setting ΔPg,F to be 0.0015 or less about the Abbe number νd, the optical glass suitable for high-order chromatic aberration correction can be improved. Moreover, by making specific gravity 3.19 or less, weight reduction of an optical element can be achieved.

Next, the preferable aspect of the content and ratio of the glass component in the optical glass of 3rd-4th embodiment is described in detail below.

In the optical glass of the third-fourth embodiment, the mass ratio [SiO ₂ /Nb ₂ O ₅ ] of the content of SiO ₂ to the content of Nb ₂ O ₅ is preferably greater than 1.05, and the lower limit thereof is 1.09, 1.11, 1.15, 1.17 order is more preferred. In addition, the upper limit of the mass ratio [SiO ₂ /Nb ₂ O ₅ ] is preferably 1.50, and more preferably 1.48, 1.46, and 1.44 in this order. By setting the mass ratio [SiO ₂ /Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be reduced while maintaining desired optical constants (refractive index nd, Abbe number νd).

In the optical glass of the 3rd-4th embodiment, the mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is preferably greater than 0.25, and the lower limit thereof is 0.26, 0.27, 0.28, and 0.29 , 0.30, 0.305, 0.310, 0.315 are more preferred. In addition, the upper limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] is preferably 0.50, and more preferably 0.47, 0.44, and 0.41 in this order. By setting the lower limit of the mass ratio [ZrO ₂ /Nb ₂ O ₅ ] to the above range, the relative partial dispersion Pg,F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the 3rd-4th embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is preferably greater than 0.65, and its lower limit is more preferably in the order of 0.66, 0.67, 0.69, 0.71, 0.73, 0.76, 0.80, 0.83, 0.86, 0.88. In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.20, and more preferably 1.14, 1.12, and 1.10 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the thermal stability of the glass can be maintained and a desired optical constant can be obtained.

In the optical glass of the 3rd-4th embodiment, the total content of TiO ₂ and BaO [TiO ₂ +BaO] is preferably less than 10%, and the upper limit thereof is more preferably in the order of 8.0%, 7.8%, 7.6%, and 7.4%. In addition, the lower limit of the total content [TiO ₂ +BaO] is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. By setting the upper limit of the total content [TiO ₂ +BaO] to the above range, the relative partial dispersion Pg,F can be reduced, and the specific gravity of the glass can be reduced.

In the optical glass of the 3rd-4th embodiment, the mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably Less than 0.3, the upper limit thereof is more preferably in the order of 0.25, 0.20, and 0.15. In addition, the lower limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is preferably 0, and more preferably 0.05, 0.07, and 0.10 in the order. The mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] may be zero. By setting the upper limit of the mass ratio [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glass of the third-fourth embodiment, the mass ratio [ZnO/Nb ₂ O ₅ ] of the content of ZnO to the content of Nb ₂ O ₅ is preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, and 0.105 . In addition, the lower limit of the mass ratio [ZnO/Nb ₂ O ₅ ] is preferably 0, and more preferably 0.02, 0.05, and 0.07 in this order. The mass ratio [ZnO/Nb ₂ O ₅ ] may be zero. By setting the upper limit of the mass ratio [ZnO/Nb ₂ O ₅ ] to the above range, the specific gravity of the glass can be lowered, and a desired optical constant can be obtained.

The optical glass of the 3rd-4th embodiment preferably satisfies one or more of the following (g) and (h):

(g) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1%,

(h) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO.

That is, in the optical glass of the 3rd-4th embodiment, the total content R ₂ O of Li ₂ O, Na ₂ O, and K ₂ O can be made more than 1.1%. The total content of R ₂ O is preferably more than 9%, and the lower limit thereof is more preferably in the order of 15.0%, 15.5%, 16.0%, and 16.5%. In addition, the upper limit of the total content of R ₂ O is preferably 22.0%, more preferably 21.7%, 21.4%, and 21.1% in the order. By making the total content R ₂ O into the above range, the specific gravity of the glass can be lowered, and the stability of the glass during reheating can be maintained.

Moreover, in the optical glass of 3-4th embodiment, with respect to the total content of Li ₂ O, Na ₂ O, and K ₂ O, R ₂ O, and the total content of MgO, CaO, SrO, and BaO, R'O content, the mass ratio [R ₂ O/(R ₂ O+R'O)] of the total content of R ₂ O may be greater than 0.05. The mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably greater than 0.6, and the lower limit thereof is more preferably in the order of 0.80, 0.82, 0.84, and 0.86. In addition, the upper limit of the mass ratio [R ₂ O/(R ₂ O+R'O)] is preferably 0.95, and more preferably 0.98, 0.99, and 1.00 in the order. By making the mass ratio [R ₂ O/(R ₂ O+R'O)] in the above-mentioned range, the specific gravity of the glass can be lowered and the stability of the glass at the time of reheating can be maintained.

In the optical glass of the 3-4th embodiment, the content and ratio of the glass components other than the above may be the same as those of the 3-1st embodiment. In addition, the glass properties other than those described above in the 3-4th embodiment, and the manufacture of the optical glass and the manufacture of the optical element and the like may be the same as those of the 3-1st embodiment.

In addition, in the 3-4th embodiment, any one of the aspects of the 3-1st to 3rd-3rd embodiments can be adopted.

"The Fourth Invention"

[Background Art of the Fourth Invention]

In order to reduce the power consumption when driving the autofocus function, there is a demand for weight reduction of the optical elements mounted in the optical system of the autofocus method. If the specific gravity of glass can be reduced, the weight of optical elements such as lenses can be reduced. In addition, in order to correct the chromatic aberration, the relative partial dispersion Pg,F is required to be small.

Moreover, as a manufacturing method of such an optical glass used for an optical system, the reheat pressing method of reheating and shaping|molding glass is mentioned. In this production method, the silicate-based high-refractive-index and high-dispersity optical glass tends to devitrify upon reheating. Therefore, when the glass is reheated, a high degree of stability is required so that the inside of the glass is not easily devitrified.

Patent Document 4-1 discloses an optical glass having a refractive index nd of 1.674 or more and an Abbe number νd of 30.2 or more. However, the optical glass described in Patent Document 4-1 has low homogeneity, and devitrification is observed upon reheating. In addition, the conditions of low specific gravity and low Pg,F are not satisfied. Therefore, optical glasses having desired optical constants and higher performance are desired.

[Prior Art Document of the Fourth Invention]

Patent Literature

Patent Document 4-1: Japanese Patent Laid-Open No. 2017-105702

[Content of the fourth invention]

[Problems to be solved by the fourth invention]

The object of the fourth invention is to provide an optical glass having a desired optical constant, a specific gravity as small as possible, a small relative partial dispersion Pg,F, excellent stability during reheating, and high homogeneity, and an optical glass composed of the above-mentioned optical glass. formed optical element.

[way of solving the problem]

The gist of the fourth invention is as follows.

(1) An optical glass wherein,

The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80,

The mass ratio of the content of SiO ₂ to the content of Na ₂ O [SiO ₂ /Na ₂ O] is 2.5 to 8.5,

Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55,

The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more,

The total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84% by mass.

(2) An optical glass wherein,

The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.7,

Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55,

The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more,

The total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84% by mass.

(3) An optical glass whose Abbe number νd is 30-36,

The specific gravity is below 3.4,

The deviation ΔPg,F from the partial dispersion Pg,F is 0.0030 or less.

(4) An optical element formed of the optical glass according to any one of (1) to (3) above.

[Effect of the fourth invention]

According to the fourth invention, it is possible to provide an optical glass having a desired optical constant, a specific gravity as small as possible, a relative partial dispersion Pg,F small, excellent stability during reheating, and high homogeneity, and an optical glass formed of the above-mentioned optical glass. Optical element.

[Specific embodiment of the fourth invention]

The Abbe number νd is used as a value representing a property related to dispersion, and is represented by the following formula. Here, nF is the refractive index of blue hydrogen under F rays (wavelength 486.13 nm), and nC is the refractive index of red hydrogen under C rays (656.27 nm).

νd=(nd-1)/(nF-nC)

Hereinafter, the optical glass of 4th invention is demonstrated as 4-1st Embodiment, 4-2nd Embodiment, and 4-3rd Embodiment. In addition, the action and effect of each glass component in 4-2, 4-3 embodiment are the same as the action and effect of each glass component in 4-1 embodiment. Therefore, in the 4-2nd and 4-3rd embodiments, the matters overlapping the descriptions related to the 4-1st embodiment are appropriately omitted.

In the 4-1, 4-2, and 4-3 embodiments, the relative partial dispersion Pg,F is expressed as follows using the respective refractive indices ng, nF, and nC among g-rays, F-rays, and C-rays.

Pg,F=(ng-nF)/(nF-nC)

In a plane in which the horizontal axis is Abbe's number νd and the vertical axis is relative partial dispersion Pg,F, the normal is represented by the following formula.

Pg,F(0)=0.6483-(0.0018×νd)

In addition, the deviation ΔPg,F of the relative partial dispersion Pg,F with respect to the normal line is expressed as follows.

ΔPg,F=Pg,F-Pg,F(0)

Embodiment 4-1

The optical glass of the 4-1 embodiment is characterized in that:

The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80,

The mass ratio of the content of SiO ₂ to the content of Na ₂ O [SiO ₂ /Na ₂ O] is 2.5 to 8.5,

Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55,

The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more,

The total content of SiO ₂ and Nb ₂ O ₅ [SiO ₂ +Nb ₂ O ₅ ] is 62 to 84%.

In the optical glass of the 4-1st embodiment, the mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80. The lower limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.83, and more preferably in the order of 0.85, 0.86, 0.87, and 0.88. The upper limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 1.50, and more preferably 1.40, 1.30, and 1.20 in this order. By setting the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] to the above range, crystallization of glass can be suppressed, and optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-1st embodiment, the mass ratio [SiO ₂ /Na ₂ O] of the content of SiO ₂ to the content of Na ₂ O is 2.5 to 8.5. The lower limit of the mass ratio [SiO ₂ /Na ₂ O] is preferably 2.6, and more preferably in the order of 2.65, 2.70, and 2.75. In addition, the upper limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 8.2, and even more preferably 8.0, 7.8, and 7.6 in this order. By making the mass ratio [SiO ₂ /Na ₂ O] into the above range, an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-1st embodiment, the mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is 1.45 to 4.55. The lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 1.70, and more preferably 1.72, 1.74, and 1.76 in this order. In addition, the upper limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 4.20, and more preferably 4.0, 3.95, and 3.90 in the order of Preferred. Crystallization of glass can be suppressed by making mass ratio _[ ( _SiO2 +B2O3+ _{P2O5 )} /( _{Li2O +} Na2O ₊ K2O ₎ ] into the said range.

In the optical glass of the 4-1st embodiment, the mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more. The lower limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.46, and more preferably 0.47, 0.48, and 0.49 in this order. In addition, the upper limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.97, more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By setting the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. In addition, crystallization of glass can be suppressed, and an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-1st embodiment, the total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84%. The lower limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is preferably 63.0%, and more preferably in the order of 63.5%, 64.0%, and 64.5%. In addition, the upper limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is preferably 83%, and more preferably 82.7%, 82.3%, and 82.1% in this order. By making the total content [SiO ₂ +Nb ₂ O ₅ ] in the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. Furthermore, crystallization of glass can be suppressed.

In the optical glass of the 4-1st embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is preferably greater than 0.7. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is more preferably 0.73, and more preferably 0.75, 0.77, and 0.79 in this order. In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.15, and more preferably 1.13, 1.11, and 1.09 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved.

The content and ratio of the glass components other than the above in the optical glass of the 4-1st embodiment will be described in detail below.

In the optical glass of the 4-1st embodiment, the lower limit of the content of SiO ₂ is preferably 33.0%, and more preferably 33.5%, 34.0%, and 34.5% in the order. In addition, the upper limit of the content of SiO ₂ is preferably 44.0%, and more preferably 43.5%, 43.0%, and 42.5% in the order. By making content of _SiO2 into the said range, the specific gravity of glass can be made low, and stability improvement at the time of glass reheating and a desired optical constant can be acquired.

In the optical glass of the 4-1st embodiment, the upper limit of the content of B ₂ O ₃ is preferably 5.0%, and more preferably in the order of 4.5%, 4.0%, and 3.5%. In addition, the lower limit of the content of B ₂ O ₃ is preferably 0%, and more preferably in the order of 0.1%, 0.2%, and 0.3%. The content of B ₂ O ₃ may also be 0%. By making content _{of B2O3} into the said range, the specific gravity of glass can be made low, and the thermal stability of glass can be improved.

In the optical glass of the 4-1st embodiment, the upper limit of the content of P ₂ O ₅ is preferably 1.5%, and more preferably 1.4%, 1.3%, and 1.2% in this order. In addition, the lower limit of the content of P ₂ O ₅ is preferably 0%, and more preferably in the order of 0.2%, 0.4%, and 0.6%. The content of P ₂ O ₅ may also be 0%. By making content of _{P2O5 into} the said range, the increase of relative partial dispersion Pg,F can be suppressed, and the thermal stability of glass can be maintained.

In the glass of the 4-1st embodiment, the upper limit of the content of Al ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. The content of Al ₂ O ₃ may also be 0%. _{Devitrification} resistance and thermal stability of glass can be maintained by making content of _Al2O3 into the said range.

In the optical glass according to the 4-1st embodiment, the upper limit of the total content [SiO ₂ +B ₂ O ₃ ] of SiO ₂ and B ₂ O ₃ is preferably 48.0%, and more preferably 47.0%, 46.0%, 45.0%, and 44.5%. The order of % is more preferred. In addition, the lower limit of the content of the total content [SiO ₂ +B ₂ O ₃ ] is preferably 32.0%, and more preferably in the order of 33.0%, 34.0%, 35.0%, and 35.5%. By making the total content [SiO ₂ +B ₂ O ₃ ] in the above range, the specific gravity of the glass can be lowered, the thermal stability of the glass can be improved, and a desired optical constant can be obtained.

In addition, in the optical glass of the 4-1st embodiment, the upper limit of the total content [SiO ₂ +B ₂ O ₃ +P ₂ O ₅ ] of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ is preferably 48.0%, Furthermore, it is more preferable in the order of 47.0%, 46.0%, 45.0%, and 44.5%. In addition, the lower limit of the content of the total content [SiO ₂ +B ₂ O ₃ +P ₂ O ₅ ] is preferably 33.0%, and more preferably in the order of 34.0%, 35.0%, 36.0%, and 36.5%. By making the total content [SiO ₂ +B ₂ O ₃ +P ₂ O ₅ ] in the above range, the specific gravity of the glass can be lowered, the thermal stability of the glass can be improved, and a desired optical constant can be obtained.

In the optical glass of the 4-1st embodiment, the upper limit of the content of TiO ₂ is preferably 10%, and more preferably 9.5%, 9%, and 8.5% in the order. The lower limit of the content of TiO ₂ is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. The content of _TiO2 may also be 0%. By making content of _TiO2 into the said range, a desired optical constant can be achieved, and the raw material cost of glass can be reduced.

In the optical glass of the 4-1st embodiment, the lower limit of the content of Nb ₂ O ₅ is preferably 45%, and more preferably in the order of 44%, 43%, and 42%. In addition, the upper limit of the content of Nb ₂ O ₅ is preferably 24%, and more preferably in the order of 25%, 26%, and 27%. By setting the content of Nb ₂ O ₅ to the above range, a desired optical constant can be achieved, an increase in specific gravity can be suppressed, and the relative partial dispersion Pg,F can be reduced.

In the optical glass according to the 4-1st embodiment, the lower limit of the total content of TiO ₂ and Nb ₂ O ₅ [TiO ₂ +Nb ₂ O ₅ ] is preferably 28%, and the lower limit is further 29%, 30%, and 31% in this order More preferred. In addition, the upper limit of the content of the total content [TiO ₂ +Nb ₂ O ₅ ] is preferably 45%, and more preferably 44%, 43%, and 42% in this order. By setting the total content [TiO ₂ +Nb ₂ O ₅ ] to the above range, a desired optical constant can be achieved.

In the glass of the 4-1st embodiment, the upper limit of the content of WO ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. The content of WO ₃ may also be 0%. By making the upper limit of the content of WO ₃ into the above range, the transmittance can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In the 4-1st embodiment, the upper limit of the content of Bi ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may also be 0%. By making the content of Bi ₂ O ₃ into the above range, the thermal stability of the glass can be improved, and the relative partial dispersion Pg, F and specific gravity can be reduced.

In the glass of the 4-1st embodiment, the lower limit of the content of ZrO ₂ is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. In addition, the upper limit of the content of ZrO ₂ is preferably 12.5%, and more preferably 12.2%, 11.8%, and 11.4% in this order. The content of ZrO ₂ may also be 0%. By making the content of ZrO ₂ into the above range, a desired optical constant can be achieved, and the relative partial dispersion Pg,F can be reduced.

In the glass of the 4-1st embodiment, the upper limit of the content of Li ₂ O is preferably 10%, and more preferably 9%, 8%, and 7% in the order. The lower limit of the content of Li ₂ O is preferably 0%, and more preferably in the order of 1%, 2%, and 3%. The content of Li ₂ O may be 0%. By making the content of Li ₂ O into the above range, a desired optical constant can be achieved, and chemical durability, weather resistance, and stability during reheating can be maintained.

In the glass of the 4-1st embodiment, the upper limit of the content of Na ₂ O is preferably 15%, and more preferably 14%, 13.5%, and 13% in the order. The lower limit of the content of Na ₂ O is preferably 4%, and more preferably in the order of 4.5%, 5%, and 5.5%. By making content of _Na2O into the said range, relative partial dispersion Pg,F can be reduced.

In the glass of the 4-1st embodiment, the upper limit of the content of K ₂ O is preferably 5%, and more preferably in the order of 4.5%, 4%, and 3.5%. The lower limit of the content of K ₂ O is preferably 0%, and more preferably in the order of 0.1%, 0.2%, and 0.3%. The content of K ₂ O may also be 0%. _The thermal stability of glass can be improved by making content of K2O into the said range.

In the glass of the 4-1st embodiment, the upper limit of the total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O+Na ₂ O+K ₂ O] is preferably 22%, and further 21%, The order of 20.5% and 20% is more preferable. The lower limit of the total content is preferably 11%, and more preferably in the order of 11.1%, 11.2%, and 11.3%. By making this total content into the said range, the meltability and thermal stability of glass can be improved, and a liquidus temperature can be lowered.

In the glass of the 4-1st embodiment, the upper limit of the content of Cs ₂ O is preferably 5%, and more preferably in the order of 3%, 1%, and 0.5%. The lower limit of the content of Cs ₂ O is preferably 0%.

Cs ₂ O has the effect of improving the thermal stability of glass, but when the content thereof increases, chemical durability and weather resistance decrease. Therefore, it is preferable that each content of _Cs2O is the said range.

In the glass of the 4-1st embodiment, the upper limit of the content of MgO is preferably 10%, and more preferably in the order of 8%, 6%, 4%, and 2%. In addition, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

In the glass of the 4-1st embodiment, the upper limit of the content of CaO is preferably 10%, and more preferably in the order of 8%, 6%, 4%, and 2%. In addition, the lower limit of the content of CaO is preferably 0%. The content of CaO may also be 0%.

In the glass of the 4-1st embodiment, the upper limit of the content of SrO is preferably 10%, and more preferably in the order of 8%, 6%, 4%, and 2%. In addition, the lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

In the optical glass of the 4-1st embodiment, the upper limit of the content of BaO is preferably 10%, and more preferably in the order of 8%, 6%, 4%, and 2%. The lower limit of the content of BaO is preferably 0%. The content of BaO may also be 0%. By making content of BaO into the said range, the increase of specific gravity can be suppressed.

MgO, CaO, SrO, and BaO are all glass components having the effect of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, the specific gravity increases, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass decrease. Therefore, it is preferable that each content of these glass components is the said range, respectively.

In the glass of the 4-1st embodiment, the upper limit of the total content of MgO, CaO, SrO and BaO [MgO+CaO+SrO+BaO] is preferably 10%, and further increased in the order of 7%, 6%, and 5% Preferred. In addition, the lower limit of the total content is preferably 0%. The total content may also be 0%. By making this total content into the said range, the increase of specific gravity can be suppressed, and thermal stability can be maintained, without hindering high dispersion|distribution.

In the glass of the 4-1st embodiment, the upper limit of the content of ZnO is preferably 10%, and more preferably in the order of 5%, 4%, and 3%. In addition, the lower limit of the content of ZnO is preferably 0%. The content of ZnO may be 0%.

ZnO is a glass component that has the effect of improving the thermal stability of glass. However, when the content of ZnO is too large, the specific gravity increases. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining a desired optical constant, the content of ZnO is preferably within the above range.

In the optical glass of the 4-1st embodiment, the upper limit of the content of La ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of La ₂ O ₃ is preferably 0%. The content of La ₂ O ₃ may also be 0%. By making the content of La ₂ O ₃ into the above-mentioned range, a desired optical constant can be achieved, an increase in specific gravity can be suppressed, and the relative partial dispersion Pg,F can be reduced.

In the glass of the 4-1st embodiment, the upper limit of the content of Y ₂ O ₃ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of Y ₂ O ₃ is preferably 0%. The content of Y ₂ O ₃ may also be 0%.

When the content of Y ₂ O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. Therefore, it is preferable that content _{of Y2O3} is the said range from a viewpoint of suppressing the fall of the thermal stability of glass.

In the glass of the 4-1st embodiment, the upper limit of the content of Ta ₂ O ₅ is preferably 5%, and more preferably in the order of 4%, 3%, and 2%. In addition, the lower limit of the content of Ta ₂ O ₅ is preferably 0%. The content of Ta ₂ O ₅ may also be 0%.

Ta ₂ O ₅ is a glass component that has an effect of improving the thermal stability of glass, and is a component that causes a decrease in relative partial dispersion Pg,F. On the other hand, when the content of Ta ₂ O ₅ is increased, the thermal stability of the glass is lowered, and the melting residue of the glass raw material tends to occur when the glass is melted. In addition, the specific gravity increased. Therefore, the content of Ta ₂ O ₅ is preferably within the above range.

In the glass of the 4-1st embodiment, the content of Sc ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Sc ₂ O ₃ is preferably 0%.

In the glass of the 4-1st embodiment, the content of HfO ₂ is preferably 2% or less. In addition, the lower limit of the content of HfO ₂ is preferably 0%, and more preferably in the order of 0.05% and 0.1%.

Sc ₂ O ₃ and HfO ₂ are expensive components having an effect of improving the high dispersibility of glass. Therefore, each content of Sc ₂ O ₃ and HfO ₂ is preferably within the above range.

In the glass of the 4-1st embodiment, the content of Lu ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Lu ₂ O ₃ is preferably 0%.

Although Lu ₂ O ₃ has the effect of improving the high dispersibility of glass, it is also a glass component that increases the specific gravity of glass due to its large molecular weight. Therefore, the content of Lu ₂ O ₃ is preferably within the above range.

In the glass of the 4-1st embodiment, the content of GeO ₂ is preferably 2% or less. In addition, the lower limit of the content of GeO ₂ is preferably 0%.

GeO ₂ has the effect of improving the high dispersibility of glass, but is an extremely expensive component among commonly used glass components. Therefore, the content of GeO ₂ is preferably within the above-mentioned range from the viewpoint of reducing the production cost of glass.

In the glass of the 4-1st embodiment, the content of Gd ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Gd ₂ O ₃ is preferably 0%.

When the content of Gd ₂ O ₃ becomes too large, the thermal stability of the glass decreases. In addition, when the content of Gd ₂ O ₃ becomes too large, the specific gravity of the glass increases. Therefore, the content of Gd ₂ O ₃ is preferably within the above-mentioned range from the viewpoint of keeping the thermal stability of the glass well and suppressing an increase in specific gravity.

In the glass of the 4-1st embodiment, the content of Yb ₂ O ₃ is preferably 2% or less. In addition, the lower limit of the content of Yb ₂ O ₃ is preferably 0%.

Yb ₂ O ₃ has a larger molecular weight than La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , and therefore increases the specific gravity of glass. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a high-mass lens is incorporated into an autofocus-type imaging lens, power required for driving the lens during autofocusing increases, and battery consumption becomes severe. Therefore, it is preferable to reduce the content of Yb ₂ O ₃ in order to suppress an increase in the specific gravity of the glass.

In addition, when the content of Yb ₂ O ₃ is too large, the thermal stability of the glass decreases. The content of Yb ₂ O ₃ is preferably within the above-mentioned range from the viewpoints of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.

The glass of the 4-1st embodiment is preferably mainly composed of the above-mentioned glass components, that is, SiO ₂ and Na ₂ O as essential components, B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , TiO ₂ as optional components, Nb ₂ O ₅ , WO ₃ , Bi ₂ O ₃ , ZrO ₂ , Li ₂ O, K ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Ta ₂ It is composed of O ₅ , Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , Gd ₂ O ₃ and Yb ₂ O ₃ , and the total content of the above-mentioned glass components is preferably more than 95%, more preferably more than 98%, More preferably more than 99%, still more preferably more than 99.5%.

In addition, although it is preferable that the glass of 4-1 Embodiment consists basically of the said glass component, you may contain other components in the range which does not inhibit the effect of 4th invention. In addition, in the fourth invention, the inclusion of unavoidable impurities is not excluded.

(other ingredients)

In addition to the above-mentioned components, the above-mentioned optical glass may contain a small amount of Sb ₂ O ₃ , CeO ₂ or the like as a clarifying agent. The total amount of the clarifying agent (external ratio addition amount) is preferably 0% or more and less than 1%, and more preferably 0% or more and 0.5% or less.

The external ratio addition amount refers to the value shown by the weight percentage of the addition amount of the clarifying agent when the total content of all the glass components other than the clarifying agent is 100%.

Pb, Cd, As, Th and the like are components that may cause environmental burdens. Therefore, the content of each of PbO, CdO, and ThO ₂ is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially free of PbO, CdO, and ThO ₂ .

The content of As ₂ O ₃ is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially free of As ₂ O ₃ .

In addition, the above-mentioned optical glass can obtain high transmittance in a wide range of the visible region. In order to utilize such a feature effectively, it is preferable not to contain a coloring element. As a coloring element, Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, V, etc. are illustrated. Any element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably not substantially contained.

In addition, Ga, Te, Tb, etc. are components that do not need to be introduced, and are also expensive components. Therefore, the ranges of the contents of Ga ₂ O ₃ , TeO ₂ , and TbO ₂ expressed in mass % are all preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and still more preferably 0 to 0.005%, more preferably 0 to 0.001%, and particularly preferably not substantially contained.

(glass properties)

<Refractive index nd>

In the optical glass of the 4-1st embodiment, the refractive index nd is preferably 1.690 to 1.760. The refractive index nd may be set to 1.695 to 1.755, or 1.700 to 1.750. Components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . Components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

<Abbé number νd>

In the optical glass of the 4-1st embodiment, it is preferable that Abbe's number νd is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

<Specific gravity of glass>

The specific gravity of the optical glass of the 4-1st embodiment is preferably 3.40 or less, more preferably 3.35 or less, 3.30 or less, and 3.25 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.10. Components that relatively increase the specific gravity include BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and the like. Components that relatively lower the specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and the like. Specific gravity can be controlled by adjusting the content of these components.

<Relative partial dispersion Pg,F>

The upper limit of the relative partial dispersion Pg,F of the optical glass of the 4-1st embodiment is preferably 0.5980, and more preferably 0.5970, 0.5960, 0.5950, and 0.5940 in this order. In addition, it is preferable that the relative partial dispersion Pg,F is low, and the lower limit thereof is preferably 0.5780, and may be further 0.5800, 0.5820, 0.5840, and 0.5860. By setting the relative partial dispersion Pg,F to the above-mentioned range, an optical glass suitable for high-order chromatic aberration correction can be obtained. The relative partial dispersion Pg,F can be controlled by adjusting the content of SiO ₂ , B ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ and the like.

In addition, the upper limit of the deviation ΔPg,F of the relative partial dispersion Pg,F of the optical glass according to the 4-1st embodiment is preferably 0.0030, and more preferably 0.0025, 0.0020, and 0.0015 in the order. In addition, when the deviation ΔPg,F is preferably low, the lower limit is preferably -0.0060, and further, -0.0050, -0.0040, -0.0030, and -0.0020.

<Liquid phase temperature>

The liquidus temperature LT of the optical glass of the 4-1st embodiment is preferably 1200°C or lower, and more preferably 1190°C or lower, 1180°C or lower, and 1170°C or lower in this order. By making the liquidus temperature into the above-mentioned range, the melting and forming temperature of glass can be lowered, and as a result, the erosion of glass melting equipment (eg, crucible, stirring equipment for molten glass, etc.) in the melting process can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000°C. The liquidus temperature LT is determined according to the balance of the contents of all the glass components. Among them, the contents of SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like have a great influence on the liquidus temperature LT.

In addition, the liquidus temperature is determined as follows. Put 10cc (10ml) of glass into a platinum crucible, melt at 1250℃～1400℃ for 15～30 minutes, cool down to below the glass transition temperature Tg, put the glass together with the platinum crucible into a melting furnace at a given temperature and melt it. Hold for 2 hours. The temperature was kept at 1000°C or higher, the interval was set to 5°C or 10°C, the temperature was kept for 2 hours, and then cooled, and the presence or absence of crystals in the glass was observed with a 100-fold optical microscope. The lowest temperature at which no crystals were precipitated was set as the liquidus temperature.

<Glass transition temperature Tg>

The upper limit of the glass transition temperature Tg of the optical glass of the 4-1st embodiment is preferably 670°C, and more preferably 650°C, 630°C, and 610°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 510°C, and more preferably 520°C, 525°C, and 530°C in this order. Components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. Components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ and the like. By appropriately adjusting the content of these components, the glass transition temperature Tg can be controlled.

<Stability during reheating>

In the optical glass of the 4-1st embodiment, the number of crystals observed per 1 g is preferably 10 minutes at the glass transition temperature Tg and 140 to 220°C higher than the Tg for 10 minutes. 20 or less, more preferably 10 or less.

In addition, the stability at the time of reheating was measured as follows. A glass sample having a size of 1 cm x 1 cm x 0.8 cm was heated in a first test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and was further set to be higher than the glass transition temperature Tg of the glass sample. After heating in the second test furnace at a temperature of 140 to 220° C. for 10 minutes, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. In addition, the presence or absence of cloudiness of the glass was confirmed with the naked eye.

The manufacture of the optical glass of the 4-1st embodiment can be made the same as that of the embodiment of the 1st invention. In addition, about manufacture of an optical element etc., it can also be made the same as that of embodiment of 1st invention.

Embodiment 4-2

The optical glass according to the 4-2nd embodiment is characterized in that:

The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80,

The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.7,

Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55,

The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more,

The total content of SiO ₂ and Nb ₂ O ₅ [SiO ₂ +Nb ₂ O ₅ ] is 62 to 84%.

In the optical glass of the 4-2nd embodiment, the mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80. The lower limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 0.83, and more preferably in the order of 0.85, 0.86, 0.87, and 0.88. The upper limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 1.50, and more preferably 1.40, 1.30, and 1.20 in this order. By setting the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] to the above range, crystallization of glass can be suppressed, and optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-2nd embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is greater than 0.7. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 0.73, and more preferably 0.75, 0.77, and 0.79 in this order. In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.15, and more preferably 1.13, 1.11, and 1.09 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved.

In the optical glass of the 4-2nd embodiment, the mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is 1.45 to 4.55. The lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 1.70, and more preferably 1.72, 1.74, and 1.76 in this order. In addition, the upper limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 4.2, and more preferably 4.0, 3.95, and 3.9 in the order of Preferred. Crystallization of glass can be suppressed by making mass ratio _[ ( _SiO2 +B2O3+ _{P2O5 )} /( _{Li2O +} Na2O ₊ K2O ₎ ] into the said range.

In the optical glass of the 4-2nd embodiment, the mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more. The lower limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.46, and more preferably 0.47, 0.48, and 0.49 in this order. In addition, the upper limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.97, more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By setting the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. In addition, crystallization of glass can be suppressed, and an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-2nd embodiment, the total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84%. The lower limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is preferably 63.0%, and more preferably in the order of 63.5%, 64.0%, and 64.5%. In addition, the upper limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is preferably 83%, and more preferably 82.7%, 82.4%, and 82.1% in this order. By making the total content [SiO ₂ +Nb ₂ O ₅ ] in the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. Furthermore, crystallization of glass can be suppressed.

In the optical glass of the 4-2nd embodiment, the mass ratio [SiO ₂ /Na ₂ O] of the content of SiO ₂ to the content of Na ₂ O is preferably 2.5 to 8.5. The lower limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 2.6, and more preferably 2.65, 2.7, and 2.75 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 8.2, and even more preferably 8.0, 7.8, and 7.6 in this order. By making the mass ratio [SiO ₂ /Na ₂ O] into the above range, an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-2nd embodiment, the content and ratio of the glass components other than the above may be the same as those of the 4-1st embodiment. In addition, the glass properties in the 4-2 embodiment, and the manufacture of the optical glass and the manufacture of the optical element and the like may be the same as those of the 4-1 embodiment.

Embodiment 4-3

The Abbe number νd of the optical glass according to the fourth-third embodiment is 30 to 36,

The specific gravity is below 3.4,

The deviation ΔPg,F from the partial dispersion Pg,F is 0.0030 or less.

In the optical glass of the 4-3rd embodiment, Abbe's number νd is 30-36. The Abbe number νd may be set to 30.5 to 35.8, or 31 to 35.5. Components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . Components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. By appropriately adjusting the content of these components, the Abbe number νd can be controlled.

In the optical glass of the 4-3rd embodiment, the specific gravity is 3.4 or less. The specific gravity is preferably 3.35 or less, more preferably 3.30 or less, and more preferably 3.25 or less in this order. The smaller the specific gravity, the more preferable, and the lower limit is not particularly limited, but is generally about 3.10.

In the optical glass of the 4th-3rd embodiment, the deviation ΔPg,F with respect to the partial dispersion Pg,F is 0.0030 or less. The upper limit of the deviation ΔPg,F is preferably 0.0025, and more preferably 0.0020 and 0.0015 in this order. In addition, when the deviation ΔPg,F is preferably low, the lower limit is preferably -0.0060, and further, -0.0050, -0.0040, -0.0030, and -0.0020.

In general, the relative partial dispersion Pg,F shows a tendency to decrease as the Abbe number νd increases. Therefore, in the fourth-third embodiment, the relative partial dispersion Pg,F is defined using the ΔPg,F described above, not the relative partial dispersion Pg,F itself. For the above Abbe number νd, for example, when νd≈30, ΔPg,F is set to 0.0030 or less, and when νd≈32, ΔPg,F is set to 0.0010 or less, thereby providing an optical glass suitable for high-order chromatic aberration correction. In addition, the specific gravity is 3.4 or less, and more preferably 3.25 or less, whereby weight reduction of the optical element can be achieved.

Next, the preferable aspect of the content and ratio of the glass component in the optical glass of 4th-3rd embodiment is described in detail below.

In the optical glass of the 4th-3rd embodiment, the mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably greater than 0.80, and The lower limit is more preferably in the order of 0.83, 0.85, 0.86, 0.87, and 0.88. The upper limit of the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is preferably 1.50, and more preferably 1.40, 1.30, and 1.20 in this order. By setting the mass ratio [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] to the above range, crystallization of glass can be suppressed, and optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-3rd embodiment, the mass ratio [SiO ₂ /Na ₂ O] of the content of SiO ₂ to the content of Na ₂ O is preferably 2.5 to 8.5. The lower limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 2.6, and more preferably 2.65, 2.7, and 2.75 in this order. In addition, the upper limit of the mass ratio [SiO ₂ /Na ₂ O] is more preferably 8.2, and even more preferably 8.0, 7.8, and 7.6 in this order. By making the mass ratio [SiO ₂ /Na ₂ O] into the above range, an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-3rd embodiment, the mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 1.45 to 4.55. The lower limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is more preferably 1.70, and more preferably 1.72, 1.74, and 1.76 in this order . In addition, the upper limit of the mass ratio [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/(Li ₂ O+Na ₂ O+K ₂ O)] is more preferably 4.2, and furthermore is 4.0, 3.95, and 3.9 in this order More preferred. Crystallization of glass can be suppressed by making mass ratio _[ ( _SiO2 +B2O3+ _{P2O5 )} /( _{Li2O +} Na2O ₊ K2O ₎ ] into the said range.

In the optical glass of the 4th-3rd embodiment, the mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.45 or more. The lower limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is more preferably 0.46, and more preferably 0.47, 0.48, and 0.49 in the order. In addition, the upper limit of the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 0.97, more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By setting the mass ratio [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. Furthermore, crystallization of glass can be suppressed, and an optical glass excellent in homogeneity and stability during reheating can be obtained.

In the optical glass of the 4-3rd embodiment, the total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is preferably 62 to 84%. The lower limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is more preferably 63.0%, and more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, the upper limit of the total content [SiO ₂ +Nb ₂ O ₅ ] is more preferably 83%, and more preferably 82.7%, 82.4%, and 82.1% in this order. By making the total content [SiO ₂ +Nb ₂ O ₅ ] in the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved. Furthermore, crystallization of glass can be suppressed.

In the optical glass of the 4-3rd embodiment, the mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO 2 ₂ +B ₂ O ₃ )] is preferably greater than 0.7. The lower limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is more preferably 0.73, and more preferably 0.75, 0.77, and 0.79 in this order. In addition, the upper limit of the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is preferably 1.15, and more preferably 1.13, 1.11, and 1.09 in this order. By setting the mass ratio [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] to the above range, the liquidus temperature can be lowered and the thermal stability of the glass can be improved.

In the optical glass of the 4-3rd embodiment, the content and ratio of the glass components other than the above may be the same as those of the 4-1st embodiment. In addition, the glass properties other than the above in the 4-3 embodiment, and the manufacture of the optical glass and the manufacture of the optical element, etc., may be the same as those of the 4-1 embodiment.

In addition, in the 4-3rd embodiment, any of the aspects of the 4-1st or 4-2nd embodiment may be adopted.

Example

"Example of the first invention"

Hereinafter, the first invention will be described in more detail with reference to Examples. However, the first invention is not limited to the embodiments shown in the examples.

(Example 1-1)

Glass samples having the glass compositions shown in Tables 1-1 to 1-5 and 1-23 were produced in the following procedure, and various evaluations were performed. In addition, in Tables 1-1 to _1-5 and 1-23, in order to show the effect by containing _P2O5 , the content of the glass components other _{than P2O5} was made constant and express.

[Manufacture of Optical Glass]

First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of glass are prepared as raw materials so that the glass compositions of the obtained optical glass are as shown in Tables 1-1 to 1-5 and 1-23. The above-mentioned raw materials were weighed and prepared in the manner of each composition shown, and the raw materials were thoroughly mixed. The prepared raw materials (batch raw materials) thus obtained are put into a platinum crucible, heated at 1350°C to 1400°C for 2 hours to prepare a molten glass, stirred for homogenization, and after clarification, the molten glass is preheated to an appropriate temperature by casting. 's mold. The glass after casting was heat-treated at a temperature lower than the glass transition temperature Tg by 100° C. for 30 minutes, and was naturally cooled to room temperature in a furnace to obtain a glass sample.

[Confirmation of glass composition]

About the obtained glass sample, content of each glass component was measured by inductively coupled plasma emission spectrometry (ICP-AES), and it was confirmed that it matched each composition shown in Tables 1-1 to 1-5 and 1-23.

[workability]

The obtained glass sample was cut and cut to obtain a sample of 10 mm×10 mm×8 mm. The sample was heated in a heat treatment furnace set to a predetermined temperature, taken out after 5 minutes, and the glass sample was cooled. The edge of the glass sample after cooling was optically polished, and the inside of the glass sample was observed with an optical microscope (100 times). The number of internal defects (bright spots) inside the glass sample was counted and converted into the number corresponding to each g. Internal defects are set to have a size in the range of 1 to 300 μm. Among the glasses having the same glass composition except for P ₂ O ₅ , the number of internal defects of the glass not containing P ₂ O ₅ is set to 1 [piece/g], and the number of internal defects of the glass containing P ₂ O ₅ is set to In the case of Ip [pieces/g], the case where ΔI=I-Ip was 1.0 [pieces/g] or more was considered good. In addition, cracks and streaks were not observed in the glass sample.

[Measurement of Optical Properties]

The obtained glass sample was further annealed in the vicinity of the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a temperature drop rate of -30°C/hour to obtain an annealed sample. The obtained annealed samples were measured for refractive index nd, ng, nF and nC, Abbe number νd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ70 and λ5. The results are shown in Tables 1-1 to 1-5 and 1-23.

(i) Refractive index nd, ng, nF, nC and Abbe number νd

For the above-mentioned annealed sample, the refractive indices nd, ng, nF, and nC were measured by the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the formula (1-7).

νd=(nd-1)/(nF-nC)...(1-7)

(ii) Relative partial dispersion Pg,F

The relative partial dispersion Pg,F is calculated based on the formula (1-6) using the respective refractive indices ng, nF, and nC under g-rays, F-rays, and C-rays.

Pg,F=(ng-nF)/(nF-nC)...(1-6)

(iii) Specific gravity

Specific gravity is determined by the Archimedes method.

(iv) Glass transition temperature Tg

The glass transition temperature Tg was measured at a temperature increase rate of 10° C./min using a differential scanning calorimetry analyzer (DSC3300SA) manufactured by NETZSCH JAPAN.

(v) λ70, λ5

The above-mentioned annealed sample was processed to have a thickness of 10 mm, and had mutually parallel and optically polished planes, and the spectral transmittance in the wavelength region of 280 nm to 700 nm was measured. The spectral transmittance B/A was calculated by setting the intensity of light perpendicularly incident on one optically polished plane as intensity A and the intensity of light emitted from the other plane as intensity B. The wavelength at which the spectral transmittance is 70% is λ70, and the wavelength at which the spectral transmittance is 5% is λ5. In addition, the reflection loss of the light beam on the sample surface is also included in the spectral transmittance.

(Example 1-2)

Glass samples having the glass compositions shown in Tables 1-6 to 1-22 were produced in the same procedure as in Example 1-1, the glass component compositions were confirmed in the same manner as in Example 1-1, and optical properties were measured. The results are shown in Tables 1-6 to 1-22. The fluoride content is reported as an external ratio. Regarding workability, it was confirmed that any glass samples had good formability during reheating.

[Table 1-6]

Sample No. 1 2 3 4 5 6 7 8 P2O5 1.41 2.13 0.94 1.42 0.97 0.96 2.35 0.94 SiO2 22.71 22.52 24.70 24.01 23.77 23.47 29.91 23.02 Nb2O5 44.95 48.57 47.58 45.14 43.52 48.33 42.73 47.41 Li2O - 4.95 - - - 0.80 4.96 - Na2O 13.15 3.99 12.74 12.59 13.53 11.69 11.15 11.05 K2O - 5.49 - - - - 0.67 3.11 Cs2O - - - - - - - - ZrO2 8.17 7.44 9.80 8.21 8.41 8.30 8.24 8.14 TiO2 6.36 4.91 4.24 6.38 9.81 6.46 6.33 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 3.24 - - - - - - - Y2O3 - - - 2.26 - - - - WO3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.84972 1.76560 1.84029 1.84393 1.85321 1.86485 1.76230 1.83955 Abbe number (νd) 24.46 29.46 24.54 24.45 23.55 23.57 30.11 24.33 Relative Partial Dispersion (Pg, F) 0.616 0.598 0.613 0.614 0.617 0.616 0.594 0.618 proportion 3.58 3.47 3.51 3.53 3.49 3.55 3.31 3.49 Glass transition temperature Tg(℃) 654 559 653 556 631 626 570 628 λ70[nm] 416 422 412 418 420 438 381 420 λ5[nm] 361 357 359 362 365 364 333 360 -0.00286×vd+0.68900 0.619 0.605 0.619 0.619 0.622 0.622 0.603 0.619 SiO2+P2O5 24.12 24.65 25.64 25.43 24.74 24.43 32.26 23.96 SiO2+B2O3+p2O5 24.12 24.65 25.64 25.43 24.74 24.43 32.26 23.96 Li2O+Na2O+K2O+Cs2O 13.15 14.43 12.74 12.59 13.53 12.49 16.78 14.16 Li2O+Na2O+K2O 13.15 14.43 12.74 12.59 13.53 12.49 16.78 14.16 Nb2O5+TiO2 51.31 53.48 51.82 51.52 53.33 54.79 42.73 53.74 Nb2O5+TiO2+WO3+Bi2O3 51.31 53.48 51.82 51.52 53.33 54.79 42.73 53.74 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.027 0.040 0.018 0.028 0.018 0.018 0.055 0.017 P2O5/Nb2O5 0.031 0.044 0.020 0.031 0.022 0.020 0.055 0.020 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.022 0.031 0.015 0.022 0.015 0.014 0.039 0.014 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.024 0.034 0.016 0.025 0.017 0.016 0.039 0.015 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.876 0.908 0.918 0.876 0.816 0.882 1.000 0.882 SiO2/(SiO2+B2O3+p2O5) 0.942 0.914 0.963 0.944 0.961 0.961 0.927 0.961 P2O5/(SiO2+P2O5) 0.058 0.086 0.037 0.056 0.039 0.039 0.073 0.039 P2O5/(SiO2+B2O3+P2O5) 0.058 0.086 0.037 0.056 0.039 0.039 0.073 0.039 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.545 0.585 0.497 0.495 0.547 0.511 0.520 0.591 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.256 0.270 0.246 0.244 0.254 0.228 0.393 0.263 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.470 0.461 0.495 0.494 0.464 0.446 0.755 0.446 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.159 0.139 0.189 0.159 0.158 0.151 0.193 0.151

[Table 1-7]

Sample No. 9 10 11 12 13 14 15 16 P2O5 2.22 0.92 0.92 0.90 0.95 0.95 0.89 0.95 SiO2 23.51 22.54 22.68 22.18 23.26 23.24 21.93 23.27 Nb2O5 50.69 46.42 46.71 45.68 47.91 47.86 45.17 47.92 Li2O 4.68 - 1.56 - 2.99 - - - Na2O 10.51 6.81 1.61 11.44 0.83 12.81 12.48 13.24 K2O 0.63 9.14 12.26 - 9.43 - - - Cs2O - - - - - - - - ZrO2 7.77 7.97 8.02 7.84 8.23 8.22 7.75 8.23 TiO2 - 6.20 6.24 6.10 6.40 6.39 3.02 6.40 B2O3 - - - - - - - - MgO - - - - - 0.54 - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - 5.86 - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - 8.75 - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.81881 1.80576 1.80417 1.86318 1.82998 1.85608 1.84462 1.85432 Abbe number (νd) 27.09 25.67 26.07 24.03 25.28 23.77 24.30 23.74 Relative Partial Dispersion (Pg, F) 0.604 0.610 0.608 0.614 0.612 0.612 0.615 0.615 proportion 3.48 3.40 3.38 3.66 3.42 3.53 3.66 3.53 Glass transition temperature Tg(℃) 567 610 585 654 582 635 622 645 λ70[nm] 396 402 399 423 414 433 425 421 λ5[nm] 340 353 352 362 356 363 363 362 -0.00286×vd+0.68900 0.612 0.616 0.614 0.620 0.617 0.621 0.620 0.621 SiO2+P2O5 25.73 23.46 23.60 23.08 24.21 24.19 22.82 24.22 SiO2+B2O3+P2O5 25.73 23.46 23.60 23.08 24.21 24.19 22.82 24.22 Li2O+Na2O+K2O+Cs2O 15.82 15.95 15.43 11.44 13.25 12.81 12.48 13.24 Li2O+Na2O+K2O 15.82 15.95 15.43 11.44 13.25 12.81 12.48 13.24 Nb2O5+TiO2 50.69 52.62 52.95 51.78 54.31 54.25 48.19 54.32 Nb2O5+TiO2+WO3+Bi2O3 50.69 52.62 52.95 51.78 54.31 54.25 56.94 54.32 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 5.86 0.00 0.54 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.54 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.044 0.017 0.017 0.017 0.017 0.018 0.018 0.017 P2O5/Nb2O5 0.044 0.020 0.020 0.020 0.020 0.020 0.020 0.020 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.033 0.013 0.013 0.014 0.014 0.014 0.013 0.014 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.033 0.015 0.015 0.016 0.016 0.016 0.015 0.016 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 1.000 0.882 0.882 0.882 0.882 0.882 0.793 0.882 SiO2/(SiO2+B2O3+P2O5) 0.914 0.961 0.961 0.961 0.961 0.961 0.961 0.961 P2O5/(SiO2+P2O5) 0.086 0.039 0.039 0.039 0.039 0.039 0.039 0.039 P2O5/(SiO2+B2O3+P2O5) 0.086 0.039 0.039 0.039 0.039 0.039 0.039 0.039 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.512 0.000 0.042 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.615 0.680 0.654 0.496 0.547 0.530 0.547 0.547 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.312 0.303 0.291 0.221 0.244 0.236 0.219 0.244 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.508 0.446 0.446 0.446 0.446 0.446 0.401 0.446 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.153 0.151 0.151 0.151 0.152 0.152 0.136 0.152

[Table 1-8]

Sample No. 17 18 19 20 twenty one twenty two twenty three twenty four P2O5 0.92 0.95 0.91 0.96 0.94 0.92 0.95 5.67 SiO2 22.51 22.54 22.43 21.07 25.38 22.47 23.44 20.82 Nb2O5 44.65 48.08 46.20 48.41 47.36 54.85 46.46 47.82 Li2O - - - - - - - - Na2O 12.81 13.29 11.57 13.38 11.86 12.79 13.33 13.22 K2O - - - - - - - - Cs2O - - - - - - - - ZrO2 7.96 8.25 7.93 8.31 8.13 7.95 8.28 8.21 TiO2 5.16 6.42 6.17 6.47 6.33 1.03 6.44 4.26 B2O3 - 0.47 - 1.41 - - - - MgO - - - - - - - - CaO - - 0.43 - - - - - SrO - - 0.80 - - - - - BaO - - 3.55 - - - - - ZnO - - - - - - 1.09 - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 5.99 - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.84790 1.85793 1.86253 1.86228 1.84914 1.85714 1.85035 1.83463 Abbe number (νd) 24.02 23.60 24.05 23.43 23.75 23.98 24.06 24.24 Relative Partial Dispersion (Pg, F) 0.617 0.617 0.615 0.616 0.617 0.613 0.617 0.616 proportion 3.60 3.53 3.64 3.54 3.50 3.59 3.53 3.49 Glass transition temperature Tg(℃) 628 632 654 620 645 626 620 644 λ70[nm] 426 427 422 430 435 421 417 466 λ5[nm] 363 364 362 363 364 357 360 364 -0.00286×vd+0.68900 0.620 0.622 0.620 0.622 0.621 0.620 0.620 0.620 SiO2+P2O5 23.43 23.49 23.34 22.03 26.32 23.39 24.39 26.49 SiO2+B2O3+P2O5 23.43 23.96 23.34 23.44 26.32 23.39 24.39 26.49 Li2O+Na2O+K2O+Cs2O 12.81 13.29 11.57 13.38 11.86 12.79 13.33 13.22 Li2O+Na2O+K2O 12.81 13.29 11.57 13.38 11.86 12.79 13.33 13.22 Nb2O5+TiO2 49.81 54.50 52.37 54.88 53.69 55.88 52.90 52.08 Nb2O5+TiO2+WO3+Bi2O3 55.80 54.50 52.37 54.88 53.69 55.88 52.90 52.08 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 4.78 0.00 0.00 0.00 1.09 0.00 MgO+CaO 0.00 0.00 0.43 0.00 0.00 0.00 0.00 0.00 P205/(Nb2O5+TiO2) 0.018 0.017 0.017 0.017 0.018 0.016 0.018 0.109 P2O5/Nb2O5 0.021 0.020 0.020 0.020 0.020 0.017 0.020 0.119 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.013 0.014 0.014 0.014 0.014 0.013 0.014 0.087 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.016 0.015 0.016 0.016 0.016 0.014 0.016 0.093 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.800 0.882 0.882 0.882 0.882 0.982 0.878 0.918 SiO2/(SiO2+B2O3+P2O5) 0.961 0.941 0.961 0.899 0.964 0.961 0.961 0.786 P2O5/(SiO2+P2O5) 0.039 0.040 0.039 0.044 0.036 0.039 0.039 0.214 P2O5/(SiO2+B2O3+P2O5) 0.039 0.040 0.039 0.041 0.036 0.039 0.039 0.214 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.413 0.000 0.000 0.000 0.082 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.547 0.555 0.496 0.571 0.451 0.547 0.547 0.499 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.230 0.244 0.221 0.244 0.221 0.229 0.252 0.254 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.420 0.440 0.446 0.427 0.490 0.419 0.461 0.509 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.143 0.151 0.151 0.151 0.151 0.142 0.157 0.158

[Table 1-9]

[Table 1-10]

Sample No. 33 34 35 36 37 38 39 40 P2O5 0.74 2.14 0.98 2.16 0.95 2.16 2.85 2.04 SiO2 20.25 22.69 24.12 21.08 25.60 22.88 23.32 25.16 Nb2O5 42.73 48.93 40.48 49.41 42.47 49.35 42.69 43.15 Li2O - 4.08 - 4.01 - 4.22 - 1.31 Na2O 10.38 9.17 13.73 9.02 13.20 9.49 13.27 14.32 K2O - 0.55 - 0.54 - 0.57 - - Cs2O - - - - - - - - ZrO2 7.00 7.50 8.53 7.57 8.20 7.56 8.25 8.90 TiO2 6.18 4.95 12.16 6.21 9.57 3.77 9.62 5.14 B2O3 2.82 - - - - - - - MgO - - - - - - - - CaO 0.83 - - - - - - - SrO - - - - - - - - BaO 3.58 - - - - - - ZnO 4.52 - - - - - - - La2O3 0.96 - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.85902 1.85339 1.85250 1.87087 1.84039 1.84540 1.84431 1.81127 Abbe number (νd) 24.59 24.95 23.45 24.20 23.94 25.45 23.68 26.05 Relative Partial Dispersion (Pg, F) 0.611 0.611 0.620 0.613 0.618 0.611 0.618 0.608 proportion 3.67 3.51 3.46 3.54 3.45 3.50 3.46 3.43 Glass transition temperature Tg(℃) 593 567 631 567 638 572 633 608 λ70[nm] 426 427 420 436 418 420 423 410 λ5[nm] 362 358 366 362 366 355 366 355 -0.00286×vd+0.68900 0.619 0.618 0.622 0.620 0.621 0.616 0.621 0.614 SiO2+P2O5 20.99 24.83 25.10 23.24 26.55 25.04 26.17 27.20 SiO2+B2O3+P2O5 23.81 24.83 25.10 23.24 26.55 25.04 26.17 27.20 Li2O+Na2O+K2O+Cs2O 10.38 13.80 13.73 13.57 13.20 14.28 13.27 15.63 Li2O+Na2O+K2O 10.38 13.80 13.73 13.57 13.20 14.28 13.27 15.63 Nb2O5+TiO2 48.91 53.88 52.64 55.62 52.04 53.12 52.31 48.29 Nb2O5+TiO2+WO3+Bi2O3 48.91 53.88 52.64 55.62 52.04 53.12 52.31 48.29 MgO+CaO+SrO+BaO+ZnO 8.93 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.83 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.015 0.040 0.019 0.039 0.018 0.041 0.054 0.042 p2O5/Nb2O5 0.017 0.044 0.024 0.044 0.022 0.044 0.067 0.047 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.012 0.032 0.015 0.031 0.015 0.032 0.043 0.032 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.014 0.034 0.018 0.034 0.017 0.034 0.051 0.035 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.874 0.908 0.769 0.888 0.816 0.929 0.816 0.894 SiO2/(SiO2+B2O3+P2O5) 0.850 0.914 0.961 0.907 0.964 0.914 0.891 0.925 P2O5/(SiO2+P2O5) 0.035 0.086 0.039 0.093 0.036 0.086 0.109 0.075 P2O5/(SiO2+B2O3+P2O5) 0.031 0.086 0.039 0.093 0.036 0.086 0.109 0.075 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.860 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.436 0.556 0.547 0.584 0.497 0.570 0.507 0.575 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.212 0.256 0.261 0.244 0.254 0.269 0.254 0.324 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.487 0.461 0.477 0.418 0.510 0.471 0.500 0.563 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.143 0.139 0.162 0.136 0.158 0.142 0.158 0.184

[Table 1-11]

Sample No. 41 42 43 44 45 46 47 48 P2O5 2.10 1.05 2.15 2.11 2.44 2.11 1.99 2.01 SiO2 25.84 24.12 22.74 22.35 30.97 22.31 21.05 21.24 Nb2O5 42.34 48.16 49.05 48.20 35.11 48.11 45.40 45.81 Li2O 1.79 3.91 5.00 3.92 5.12 4.01 1.69 1.71 Na2O 14.71 8.79 5.91 8.80 11.51 5.79 3.30 5.08 K2O - 0.53 2.69 0.53 0.69 5.43 15.03 12.50 Cs2O - - - - - - - - ZrO2 9.14 7.38 7.52 9.22 8.53 7.37 6.96 7.02 TiO2 4.08 6.06 4.96 4.87 5.63 4.86 4.59 4.63 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.79707 1.85773 1.85536 1.85721 1.76088 1.84267 1.80090 1.80856 Abbe number (νd) 27.01 24.68 25.04 24.98 29.64 25.22 26.33 26.03 Relative Partial Dispersion (Pg, F) 0.603 0.612 0.611 0.614 0.597 0.612 0.607 0.608 proportion 3.40 3.50 3.50 3.53 3.24 3.47 3.38 3.40 Glass transition temperature Tg(℃) 602 570 558 575 554 563 573 571 λ70[nm] 398 429 425 428 389 421 401 401 λ5[nm] 350 360 358 359 348 357 350 351 -0.00286×vd+0.68900 0.612 0.618 0.617 0.618 0.604 0.617 0.614 0.615 SiO2+P2O5 27.94 25.17 24.89 24.46 33.41 24.42 23.04 23.25 SiO2+B2O3+P2O5 27.94 25.17 24.89 24.46 33.41 24.42 23.04 23.25 Li2O+Na2O+K2O+Cs2O 16.50 13.23 13.60 13.25 17.32 15.23 20.02 19.29 Li2O+Na2O+K2O 16.50 13.23 13.60 13.25 17.32 15.23 20.02 19.29 Nb2O5+TiO2 46.42 54.22 54.01 53.07 40.74 52.97 49.99 50.44 Nb2O5+TiO2+WO3+Bi2O3 46.42 54.22 54.01 53.07 40.74 52.97 49.99 50.44 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.045 0.019 0.040 0.040 0.060 0.040 0.040 0.040 P2O5/Nb2O5 0.050 0.022 0.044 0.044 0.069 0.044 0.044 0.044 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.033 0.016 0.032 0.032 0.042 0.031 0.028 0.029 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.036 0.017 0.034 0.034 0.047 0.033 0.030 0.031 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.912 0.888 0.908 0.908 0.862 0.908 0.908 0.908 SiO2/(SiO2+B2O3+P2O5) 0.925 0.958 0.914 0.914 0.927 0.914 0.914 0.914 P2O5/(SiO2+P2O5) 0.075 0.042 0.086 0.086 0.073 0.086 0.086 0.086 P2O5/(SiO2+B2O3+P2O5) 0.075 0.042 0.086 0.086 0.073 0.086 0.086 0.086 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.591 0.526 0.546 0.542 0.518 0.624 0.869 0.830 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.355 0.244 0.252 0.250 0.425 0.288 0.400 0.382 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.602 0.464 0.461 0.461 0.820 0.461 0.461 0.461 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.197 0.136 0.139 0.174 0.209 0.139 0.139 0.139

[Table 1-12]

Sample No. 49 50 51 52 53 P2O5 2.03 1.25 0.78 2.40 2.37 SiO2 21.44 27.79 26.52 30.56 30.16 Nb2O5 46.23 28.96 26.49 34.65 34.19 Li2O 2.58 3.11 2.30 3.82 2.54 Na2O 3.36 5.92 3.67 13.94 16.29 K2O 12.61 0.35 0.22 0.68 0.67 Cs2O - - - - - ZrO2 7.09 8.40 8.35 8.41 8.30 TiO2 4.67 8.48 9.62 5.54 5.47 B2O3 - 1.30 1.82 - - MgO - - - - - CaO - - - - - SrO - 9.99 14.00 - - BaO - - - - - ZnO - 1.51 2.12 - - La2O3 - - - - - Y2O3 - 2.93 4.11 - - WO3 - - - - - Sb2O3 - 0.02 0.02 0.02 0.02 total 100 100 100 100 100 F-(anion%) - - - - - Refractive index (nd) 1.81481 1.80901 1.82488 1.76302 1.75584 Abbe number (νd) 25.92 29.58 29.75 29.34 29.38 Relative Partial Dispersion (Pg, F) 0.609 0.598 0.598 0.597 0.598 proportion 3.41 3.45 3.53 3.27 3.27 Glass transition temperature Tg(℃) 574 590 622 569 581 λ70[nm] 402 415 421 401 398 λ5[nm] 352 355 357 349 349 -0.00286×vd+0.68900 0.615 0.604 0.604 0.605 0.605 SiO2+P2O5 23.47 29.04 27.30 32.96 32.53 SiO2+B2O3+P2O5 23.47 30.34 29.12 32.96 32.53 Li2O+Na2O+K2O+Cs2O 18.55 9.38 6.19 18.44 19.50 Li2O+Na2O+K2O 18.55 9.38 6.19 18.44 19.50 Nb2O5+TiO2 50.90 37.44 36.11 40.19 39.66 Nb2O5+TiO2+WO3+Bi2O3 50.90 37.44 36.11 40.19 39.66 MgO+CaO+SrO+BaO+ZnO 0.00 11.50 16.12 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.040 0.033 0.022 0.060 0.060 P2O5/Nb2O5 0.044 0.043 0.029 0.069 0.069 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.029 0.027 0.018 0.041 0.040 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.031 0.033 0.024 0.045 0.044 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.908 0.774 0.734 0.862 0.862 SiO2/(SiO2+B2O3+P2O5) 0.914 0.916 0.911 0.927 0.927 P2O5/(SiO2+P2O5) 0.086 0.043 0.029 0.073 0.073 P2O5/(SiO2+B2O3+P2O5) 0.086 0.041 0.027 0.073 0.073 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 1.226 2.604 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.790 0.309 0.213 0.559 0.599 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.364 0.251 0.171 0.459 0.492 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.461 0.810 0.806 0.820 0.820 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.139 0.224 0.231 0.209 0.209

[Table 1-13]

Sample No. 54 55 56 57 58 59 60 61 P2O5 1.08 1.10 1.12 1.13 1.15 1.14 1.11 1.09 SiO2 23.69 23.27 23.63 24.00 24.43 24.12 23.53 23.06 Nb2O5 49.13 50.14 50.92 51.71 52.63 51.97 50.69 49.70 Li2O 5.23 5.61 5.83 6.07 6.33 6.25 6.10 5.56 Na2O 4.98 5.34 5.56 5.78 6.04 5.96 5.81 5.29 K2O 3.41 3.65 3.79 3.94 4.11 4.05 3.96 3.62 Cs2O - - - - - - - - ZrO2 7.53 5.82 4.01 2.15 - - - 5.76 TiO2 4.97 5.07 5.15 5.23 5.32 6.51 8.80 5.92 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.85517 1.85429 1.84806 1.84237 1.83588 1.84259 1.85537 1.85838 Abbe number (νd) 25.18 25.16 25.27 25.35 25.48 25.08 24.36 24.91 Relative Partial Dispersion (Pg, F) 0.610 0.610 0.610 0.610 0.610 0.611 0.614 0.611 proportion 3.49 3.48 3.45 3.43 3.40 3.40 3.41 3.48 Glass transition temperature Tg(℃) 560 548 544 538 529 530 531 550 λ70[nm] 426 426 424 423 422 424 429 433 λ5[nm] 357 357 357 356 355 357 360 359 -0.00286×vd+0.68900 0.617 0.617 0.617 0.616 0.616 0.617 0.619 0.618 SiO2+P2O5 24.77 24.37 24.75 25.13 25.58 25.26 24.64 24.15 SiO2+B2O3+P2O5 24.77 24.37 24.75 25.13 25.58 25.26 24.64 24.15 Li2O+Na2O+K2O+Cs2O 13.62 14.60 15.18 15.79 16.48 16.26 15.87 14.47 Li2O+Na2O+K2O 13.62 14.60 15.18 15.79 16.48 16.26 15.87 14.47 Nb2O5+TiO2 54.10 55.21 56.07 56.94 57.95 58.48 59.49 55.62 Nb2O5+TiO2+WO3+Bi2O3 54.10 55.21 56.07 56.94 57.95 58.48 59.49 55.62 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.020 0.020 0.020 0.020 0.020 0.019 0.019 0.020 p2O5/Nb2O5 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.016 0.016 0.016 0.016 0.015 0.015 0.015 0.016 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.017 0.017 0.017 0.017 0.017 0.017 0.017 0.017 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.908 0.908 0.908 0.908 0.908 0.889 0.852 0.894 SiO2/(SiO2+B2O3+P2O5) 0.956 0.955 0.955 0.955 0.955 0.955 0.955 0.955 P2O5/(SiO2+P2O5) 0.044 0.045 0.045 0.045 0.045 0.045 0.045 0.045 P2O5/(SiO2+B2O3+P2O5) 0.044 0.045 0.045 0.045 0.045 0.045 0.045 0.045 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.550 0.599 0.613 0.628 0.644 0.644 0.644 0.599 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.252 0.264 0.271 0.277 0.284 0.278 0.267 0.260 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.458 0.441 0.441 0.441 0.441 0.432 0.414 0.434 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.139 0.105 0.072 0.038 0.000 0.000 0.000 0.104

[Table 1-14]

Sample No. 62 63 64 65 66 67 68 69 P2O5 0.79 0.78 0.78 0.77 0.75 0.76 0.71 0.68 SiO2 32.99 34.69 32.49 32.19 31.18 31.60 29.52 28.52 Nb2O5 32.64 32.22 34.49 36.50 39.85 40.40 42.00 44.70 Li2O 5.71 5.39 5.38 5.33 5.16 5.23 4.43 4.07 Na2O 12.04 11.33 11.30 11.20 10.85 11.00 9.26 8.46 K2O 0.77 0.73 0.72 0.72 0.69 0.70 0.60 0.55 Cs2O - - - - - - - - ZrO2 9.08 8.96 8.94 8.86 8.58 8.70 8.12 7.85 TiO2 5.99 5.91 5.90 4.44 2.95 1.62 5.36 5.18 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.75115 1.74717 1.76307 1.76358 1.77103 1.76347 1.80632 1.82316 Abbe number (νd) 30.55 30.69 29.74 29.86 29.52 30.15 27.10 26.17 Relative Partial Dispersion (Pg, F) 0.594 0.594 0.596 0.596 0.596 0.594 0.604 0.607 proportion 3.21 3.20 3.24 3.26 3.30 3.29 3.36 3.41 Glass transition temperature Tg(℃) 541 563 562 565 563 567 575 581 λ70[nm] 396 394 401 398 399 395 415 423 λ5[nm] 347 348 349 347 346 342 355 358 -0.00286×vd+0.68900 0.602 0.601 0.604 0.604 0.605 0.603 0.611 0.614 SiO2+P2O5 33.78 35.47 33.27 32.96 31.93 32.36 30.23 29.20 SiO2+B2O3+P2O5 33.78 35.47 33.27 32.96 31.93 32.36 30.23 29.20 Li2O+Na2O+K2O+Cs2O 18.52 17.45 17.40 17.25 16.70 16.93 14.29 13.08 Li2O+Na2O+K2O 18.52 17.45 17.40 17.25 16.70 16.93 14.29 13.08 Nb2O5+TiO2 38.63 38.13 40.39 40.94 42.80 42.02 47.36 49.88 Nb2O5+TiO2+WO3+Bi2O3 38.63 38.13 40.39 40.94 42.80 42.02 47.36 49.88 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.020 0.020 0.019 0.019 0.018 0.018 0.015 0.014 P2O5/Nb2O5 0.024 0.024 0.023 0.021 0.019 0.019 0.017 0.015 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.014 0.014 0.013 0.013 0.013 0.013 0.012 0.011 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.015 0.016 0.015 0.014 0.013 0.013 0.013 0.012 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.845 0.845 0.854 0.892 0.931 0.961 0.887 0.896 SiO2/(SiO2+B2O3+P2O5) 0.977 0.978 0.977 0.977 0.977 0.977 0.977 0.977 P2O5/(SiO2+P2O5) 0.023 0.022 0.023 0.023 0.023 0.023 0.023 0.023 P2O5/(SiO2+B2O3+P2O5) 0.023 0.022 0.023 0.023 0.023 0.023 0.023 0.023 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+82O3+P2O5) 0.548 0.492 0.523 0.523 0.523 0.523 0.473 0.448 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.479 0.458 0.431 0.421 0.390 0.403 0.302 0.262 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.874 0.930 0.824 0.805 0.746 0.770 0.638 0.585 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.235 0.235 0.221 0.216 0.200 0.207 0.171 0.157

[Table 1-15]

Sample No. 70 71 72 73 74 75 76 77 P2O5 0.80 0.82 0.74 0.78 0.77 0.75 0.74 0.79 SiO2 37.79 41.06 29.27 34.66 30.26 33.51 30.88 33.01 Nb2O5 28.24 24.05 35.04 36.56 36.23 35.35 34.63 37.02 Li2O 5.53 5.68 5.15 5.37 5.57 4.96 4.85 5.69 Na2O 11.63 11.95 10.83 11.30 11.72 10.42 10.21 11.97 K2O 0.74 0.76 0.69 0.72 0.75 0.67 0.65 0.77 Cs2O - - - - - - - - ZrO2 9.20 9.45 12.62 4.71 8.86 8.64 12.47 4.77 TiO2 6.06 6.23 5.65 5.89 5.84 5.70 5.58 5.97 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.72379 1.70033 1.78562 1.75221 1.77335 1.76489 1.78130 1.75636 Abbe number (νd) 32.28 34.10 28.93 29.87 29.24 29.46 29.03 29.76 Relative Partial Dispersion (Pg, F) 0.590 0.586 0.598 0.597 0.597 0.598 0.598 0.598 proportion 3.12 3.05 3.33 3.19 3.28 3.24 3.32 3.21 Glass transition temperature Tg(℃) 554 552 560 552 548 567 575 541 λ70[nm] 384 376 405 399 405 399 401 399 λ5[nm] 346 344 350 350 349 350 350 349 -0.00286×vd+0.68900 0.597 0.591 0.606 0.604 0.605 0.605 0.606 0.604 SiO2+P2O5 38.59 41.88 30.01 35.44 31.03 34.26 31.62 33.80 SiO2+B2O3+P2O5 38.59 41.88 30.01 35.44 31.03 34.26 31.62 33.80 Li2O+Na2O+K2O+Cs2O 17.90 18.39 16.67 17.39 18.04 16.05 15.71 18.43 Li2O+Na2O+K2O 17.90 18.39 16.67 17.39 18.04 16.05 15.71 18.43 Nb2O5+TiO2 34.30 30.28 40.69 42.45 42.07 41.05 40.21 42.99 Nb2O5+TiO2+WO3+Bi2O3 34.30 30.28 40.69 42.45 42.07 41.05 40.21 42.99 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.023 0.027 0.018 0.018 0.018 0.018 0.018 0.018 P2O5/Nb2O5 0.028 0.034 0.021 0.021 0.021 0.021 0.021 0.021 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.015 0.017 0.013 0.013 0.013 0.013 0.013 0.013 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.017 0.019 0.014 0.014 0.014 0.015 0.015 0.014 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.823 0.794 0.861 0.861 0.861 0.861 0.861 0.861 SiO2/(SiO2+B2O3+P2O5) 0.979 0.980 0.975 0.978 0.975 0.978 0.977 0.977 P2O5/(SiO2+P2O5) 0.021 0.020 0.025 0.022 0.025 0.022 0.023 0.023 P2O5/(SiO2+B2O3+P2O5) 0.021 0.020 0.025 0.022 0.025 0.022 0.023 0.023 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.464 0.439 0.555 0.491 0.581 0.468 0.497 0.545 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.522 0.607 0.410 0.410 0.429 0.391 0.391 0.429 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 1.125 1.383 0.738 0.835 0.738 0.835 0.786 0.786 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.268 0.312 0.310 0.111 0.211 0.210 0.310 0.111

[Table 1-16]

Sample No. 78 79 80 81 82 83 84 85 P2O5 0.73 0.72 0.73 0.73 0.74 0.75 0.73 0.72 SiO2 32.44 30.35 30.75 30.48 30.98 31.28 30.67 30.28 Nb2O5 34.22 38.28 38.78 34.19 34.74 35.08 34.40 33.96 Li2O 4.56 4.77 4.83 4.79 4.87 4.55 3.86 4.17 Na2O 9.60 10.03 10.16 10.08 10.24 9.56 8.11 8.77 K2O 0.61 0.64 0.65 0.64 0.66 4.57 8.28 4.39 Cs2O - - - - - - - - ZrO2 12.32 12.26 12.41 8.36 8.49 8.58 8.41 12.23 TiO2 5.52 2.94 1.68 5.51 5.60 5.65 5.54 5.47 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - 5.22 - - - - Y2O3 - - - - 3.68 - - - WO3 - - - - - - - - Sb2O3 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.77627 1.78224 1.77543 1.77951 1.77583 1.75975 1.74960 1.77148 Abbe number (νd) 29.17 29.24 29.80 29.64 29.57 29.67 30.06 29.32 Relative Partial Dispersion (Pg, F) 0.598 0.597 0.595 0.596 0.597 0.597 0.596 0.597 proportion 3.30 3.35 3.34 3.37 3.32 3.24 3.32 3.29 Glass transition temperature Tg(℃) 580 579 583 568 565 556 551 571 λ70[nm] 399 400 398 402 401 399 398 402 λ5[nm] 351 347 343 350 350 349 347 349 -0.00286×vd+0.68900 0.606 0.605 0.604 0.604 0.604 0.604 0.603 0.605 SiO2+P2O5 33.17 31.07 31.48 31.21 31.72 32.03 31.40 31.00 SiO2+B2O3+P2O5 33.17 31.07 31.48 31.21 31.72 32.03 31.40 31.00 Li2O+Na2O+K2O+Cs2O 14.77 15.44 15.64 15.51 15.77 18.68 20.25 17.33 Li2O+Na2O+K2O 14.77 15.44 15.64 15.51 15.77 18.68 20.25 17.33 Nb2O5+TiO2 39.74 41.22 40.46 39.70 40.34 40.73 39.94 39.43 Nb2O5+TiO2+WO3+Bi2O3 39.74 41.22 40.46 39.70 40.34 40.73 39.94 39.43 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.018 0.017 0.018 0.018 0.018 0.018 0.018 0.018 P2O5/Nb2O5 0.021 0.019 0.019 0.021 0.021 0.021 0.021 0.021 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.013 0.013 0.013 0.013 0.013 0.013 0.012 0.013 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.015 0.013 0.013 0.015 0.015 0.014 0.013 0.014 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.861 0.929 0.958 0.861 0.861 0.861 0.861 0.861 SiO2/(SiO2+B2O3+P2O5) 0.978 0.977 0.977 0.977 0.977 0.977 0.977 0.977 P2O5/(SiO2+P2O5) 0.022 0.023 0.023 0.023 0.023 0.023 0.023 0.023 P2O5/(SiO2+82O3+P2O5) 0.022 0.023 0.023 0.023 0.023 0.023 0.023 0.023 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.445 0.497 0.497 0.497 0.497 0.583 0.645 0.559 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.372 0.375 0.387 0.391 0.391 0.459 0.507 0.440 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.835 0.754 0.778 0.786 0.786 0.786 0.786 0.786 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.310 0.297 0.307 0.211 0.210 0.211 0.211 0.310

[Table 1-17]

Sample No. 86 87 88 89 90 91 92 93 P2O5 0.71 0.80 0.80 0.80 0.82 0.82 0.81 0.82 SiO2 29.71 37.93 37.89 37.98 35.28 35.30 35.19 35.37 Nb2O5 33.32 28.35 28.31 28.39 28.79 28.81 28.72 28.87 Li2O 3.51 5.56 5.55 5.80 6.02 6.05 5.76 6.28 Na2O 7.38 11.68 12.15 11.69 12.69 12.70 13.16 12.22 K2O 7.99 0.75 0.00 0.00 0.84 0.76 0.84 0.85 Cs2O - - - - - - - - ZrO2 12.00 8.15 9.22 9.25 9.38 9.39 9.36 9.40 TiO2 5.37 6.79 6.07 6.09 6.18 6.18 6.16 6.19 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 0.02 - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.76183 1.72525 1.72481 1.72617 1.73006 1.72985 1.72873 1.73134 Abbe number (νd) 29.64 31.96 32.21 32.19 31.99 32.01 32.01 31.98 Relative Partial Dispersion (Pg, F) 0.597 0.591 0.590 0.590 0.590 0.590 0.590 0.590 proportion 3.27 3.12 3.13 3.13 3.15 3.15 3.15 3.15 Glass transition temperature Tg(℃) 568 552 559 557 538 542 540 540 λ70[nm] 399 383 382 383 387 389 387 387 λ5[nm] 348 348 347 346 345 345 345 345 -0.00286×vd+0.68900 0.604 0.598 0.597 0.597 0.598 0.597 0.597 0.598 SiO2+P2O5 30.42 38.74 38.69 38.79 36.10 36.12 36.00 36.19 SiO2+B2O3+P2O5 30.42 38.74 38.69 38.79 36.10 36.12 36.00 36.19 Li2O+Na2O+K2O+Cs2O 18.88 17.98 17.70 17.49 19.56 19.51 19.77 19.35 Li2O+Na2O+K2O 18.88 17.98 17.70 17.49 19.56 19.51 19.77 19.35 Nb2O5+TiO2 38.69 35.14 34.39 34.47 34.97 34.99 34.88 35.06 Nb2O5+TiO2+WO3+Bi2O0 38.69 35.14 34.39 34.47 34.97 34.99 34.88 35.06 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.018 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/Nb2O5 0.021 0.03 0.03 0.03 0.03 0.03 0.03 0.03 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.012 0.02 0.02 0.02 0.01 0.01 0.01 0.02 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.014 0.02 0.05 0.05 0.04 0.04 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.861 0.81 0.82 0.82 0.82 0.82 0.82 0.82 SiO2/(SiO2+B2O3+P2O5) 0.977 0.98 0.98 0.98 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.023 0.02 0.02 0.02 0.02 0.02 0.02 0.02 p2O5/(SiO2+B2O3+P2O5) 0.023 0.02 0.02 0.02 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.621 0.46 0.46 0.45 0.54 0.54 0.55 0.53 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.488 0.51 0.51 0.51 0.56 0.56 0.57 0.55 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.786 1.10 1.13 1.13 1.03 1.03 1.03 1.03 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.310 0.23 0.27 0.27 0.27 0.27 0.27 0.27

[Table 1-18]

Sample No. 94 95 96 97 98 99 100 101 P2O5 0.83 0.83 0.84 0.81 0.81 0.82 0.82 0.81 SiO2 33.57 33.70 31.81 35.23 35.26 35.33 35.31 35.26 Nb2O5 29.18 29.30 29.58 28.75 28.77 28.83 28.81 28.77 Li2O 6.37 6.79 6.74 5.94 5.95 6.09 6.09 6.01 Na2O 13.43 12.63 14.19 12.68 12.82 12.71 12.56 12.55 K2O 0.86 0.92 0.87 1.05 0.84 0.63 0.84 1.06 Cs2O - - - - - - - - ZrO2 9.51 9.55 9.64 9.37 9.37 9.39 9.39 9.37 TiO2 6.26 6.28 6.35 6.17 6.17 6.18 6.18 6.17 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.73294 1.73526 1.73663 1.72937 1.72942 1.73010 1.73018 1.72960 Abbe number (νd) 31.87 31.84 31.71 32.01 32.01 32.00 32.00 32.02 Relative Partial Dispersion (Pg, F) 0.590 0.590 0.590 0.590 0.590 0.590 0.590 0.590 proportion 3.16 3.16 3.17 3.15 3.15 3.15 3.15 3.15 Glass transition temperature Tg(℃) 528 529 516 537 540 546 540 540 λ70[nm] 391 392 393 387 388 389 389 387 λ5[nm] 344 345 343 345 345 345 345 345 -0.00286×vd+0.68900 0.598 0.598 0.598 0.597 0.597 0.597 0.597 0.597 SiO2+P2O5 34.39 34.53 32.64 36.04 36.07 36.15 36.12 36.07 SiO2+B2O3+P2O5 34.39 34.53 32.64 36.04 36.07 36.15 36.12 36.07 Li2O+Na2O+K2O+Cs2O 20.66 20.34 21.79 19.68 19.62 19.44 19.50 19.62 Li2O+Na2O+K2O 20.66 20.34 21.79 19.68 19.62 19.44 19.50 19.62 Nb2O5+TiO2 35.44 35.58 35.93 34.92 34.94 35.02 34.99 34.94 Nb2O5+TiO2+WO3+Bi2O3 35.44 35.58 35.93 34.92 34.94 35.02 34.99 34.94 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/Nb2O5 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.04 0.02 0.04 0.04 0.04 0.04 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82 SiO2/(SiO2+B2O3+P2O5) 0.98 0.98 0.97 0.98 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.02 0.02 0.03 0.02 0.02 0.02 0.02 0.02 P2O5/(SiO2+B2O3+P2O5) 0.02 0.02 0.03 0.02 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.60 0.59 0.67 0.55 0.54 0.54 0.54 0.54 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.58 0.57 0.61 0.56 0.56 0.56 0.56 0.56 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 0.97 0.97 0.91 1.03 1.03 1.03 1.03 1.03 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27

[Table 1-19]

Sample No. 102 103 104 105 106 107 108 109 P2O5 0.82 0.81 0.79 0.79 0.78 0.77 0.81 0.81 SiO2 35.31 35.20 37.44 37.09 36.76 36.33 36.55 36.45 Nb2O5 28.81 28.73 30.30 32.33 34.31 36.84 28.52 28.44 Li2O 6.02 5.94 5.48 5.43 5.38 5.32 5.78 5.77 Na2O 12.84 12.53 11.52 11.42 11.31 11.18 12.15 11.57 K2O 0.63 1.26 0.74 0.73 0.72 0.72 0.78 1.61 Cs2O - - - - - - - - ZrO2 9.39 9.36 9.12 9.03 8.95 8.85 9.29 9.26 TiO2 6.18 6.16 4.60 3.18 1.78 0.00 6.12 6.10 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.72987 1.72821 1.72436 1.72525 1.72579 1.72675 1.72708 1.72612 Abbe number (νd) 32.00 32.09 32.41 32.52 32.64 32.80 32.13 32.19 Relative Partial Dispersion (Pg, F) 0.590 0.590 0.589 0.589 0.588 0.587 0.590 0.590 proportion 3.15 3.15 3.14 3.17 3.18 3.21 3.14 3.14 Glass transition temperature Tg(℃) 541 540 557 562 566 568 549 547 λ70[nm] 387 389 384 380 377 382 385 385 λ5[nm] 347 345 344 341 338 327 345 345 -0.00286×vd+0.68900 0.597 0.597 0.596 0.596 0.596 0.595 0.597 0.597 SiO2+P2O5 36.12 36.02 38.23 37.88 37.53 37.10 37.36 37.25 SiO2+B2O3+P2O5 36.12 36.02 38.23 37.88 37.53 37.10 37.36 37.25 Li2O+Na2O+K2O+Cs2O 19.50 19.73 17.75 17.58 17.42 17.22 18.72 18.95 Li2O+Na2O+K2O 19.50 19.73 17.75 17.58 17.42 17.22 18.72 18.95 Nb2O5+TiO2 34.99 34.89 34.91 35.51 36.09 36.84 34.63 34.53 Nb2O5+TiO2+WO3+Bi2O3 34.99 34.89 34.91 35.51 36.09 36.84 34.63 34.53 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/Nb2O5 0.03 0.03 0.03 0.02 0.02 0.02 0.03 0.03 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.01 0.01 0.02 0.01 0.01 0.01 0.02 0.02 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.04 0.02 0.04 0.04 0.04 0.04 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.82 0.82 0.87 0.91 0.95 1.00 0.82 0.82 SiO2/(SiO2+B2O3+P2O5) 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/(SiO2+B2O3+p2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.54 0.55 0.46 0.46 0.46 0.46 0.50 0.51 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.56 0.57 0.51 0.50 0.48 0.47 0.54 0.55 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 1.03 1.03 1.10 1.07 1.04 1.01 1.08 1.08 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.27 0.27 0.26 0.25 0.25 0.24 0.27 0.27

[Table 1-20]

Sample No. 110 111 112 113 114 115 116 117 P2O5 0.81 0.80 0.78 0.76 0.77 0.76 0.80 0.81 SiO2 36.66 36.34 35.13 34.65 34.94 35.28 36.40 36.71 Nb2O5 28.60 28.35 37.18 36.37 38.12 38.12 28.39 28.64 Li2O 6.07 5.49 5.56 5.25 5.34 5.27 5.76 6.21 Na2O 11.64 12.08 11.68 11.04 11.23 11.08 11.28 11.37 K2O 0.78 1.61 0.75 0.71 0.72 0.71 2.03 0.78 Cs2O - - - - - - - - ZrO2 9.32 9.24 8.93 11.23 8.88 8.77 9.25 9.33 TiO2 6.13 6.08 0.00 0.00 0.00 0.00 6.09 6.14 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - - - - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.72816 1.72458 1.72970 1.73707 1.73492 1.73469 1.72527 1.72853 Abbe number (νd) 32.13 32.22 32.66 32.38 32.24 32.22 32.25 32.15 Relative Partial Dispersion (Pg, F) 0.590 0.590 0.587 0.588 0.588 0.589 0.590 0.590 proportion 3.14 3.14 3.21 3.24 3.23 3.23 3.13 3.14 Glass transition temperature Tg(℃) 549 548 566 572 571 570 547 550 λ70[nm] 385 386 378 377 380 377 386 388 λ5[nm] 345 345 329 330 330 330 345 346 -0.00286×vd+0.68900 0.597 0.597 0.596 0.596 0.597 0.597 0.597 0.597 SiO2+P2O5 37.47 37.15 35.90 35.40 35.71 36.04 37.20 37.52 SiO2+B2O3+P2O5 37.47 37.15 35.90 35.40 35.71 36.04 37.20 37.52 Li2O+Na2O+K2O+Cs2O 18.48 19.18 17.99 17.00 17.29 17.07 19.06 18.37 Li2O+Na2O+K2O 18.48 19.18 17.99 17.00 17.29 17.07 19.06 18.37 Nb2O5+TiO2 34.73 34.44 37.18 36.37 38.12 38.12 34.49 34.78 Nb2O5+TiO2+WO3+Bi2O3 34.73 34.44 37.18 36.37 38.12 38.12 34.49 34.78 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 p2O5/Nb2O5 0.03 0.03 0.02 0.02 0.02 0.02 0.03 0.03 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.02 0.01 0.01 0.01 0.01 0.01 0.02 0.02 p2O5/(Li2O+Na2O+K2O+Nb2O5) 0.04 0.02 0.04 0.04 0.04 0.04 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.82 0.82 1.00 1.00 1.00 1.00 0.82 0.82 SiO2/(SiO2+B2O3+P2O5) 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/(SiO2+B2O3+P2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.49 0.52 0.50 0.48 0.48 0.47 0.51 0.49 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.53 0.56 0.48 0.47 0.45 0.45 0.55 0.53 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 1.08 1.08 0.97 0.97 0.94 0.95 1.08 1.08 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.27 0.27 0.24 0.31 0.23 0.23 0.27 0.27

[Table 1-21]

Sample No. 118 119 120 121 122 123 124 125 P2O5 0.80 0.77 0.81 0.82 0.82 0.76 0.79 0.79 SiO2 36.24 34.94 36.82 36.89 37.24 36.33 35.58 36.34 Nb2O5 28.27 38.12 28.72 26.39 24.22 31.75 27.93 33.27 Li2O 5.34 5.34 6.50 5.84 5.89 4.89 5.47 5.44 Na2O 12.05 11.23 10.85 12.27 12.38 10.29 11.50 11.43 K2O 2.02 0.72 0.78 0.79 0.79 0.66 0.74 0.73 Cs2O - - - - - - - - ZrO2 9.21 8.88 9.36 9.38 9.46 9.57 10.60 9.04 TiO2 6.06 0.00 6.16 6.17 6.23 5.76 7.38 2.98 B2O3 - - - - - - - - MgO - - - - - - - - CaO - - - - - - - - SrO - - - - - - - - BaO - - - - - - - - ZnO - - - 1.46 2.96 - - - La2O3 - - - - - - - - Y2O3 - - - - - - - - WO3 - - - - - - - - Sb2O3 - - - - - - - - total 100 100 100 100 100 100 100 100 F-(anion%) - - - - - - - - Refractive index (nd) 1.72323 1.73528 1.72968 1.71989 1.71257 1.74515 1.74018 1.72937 Abbe number (νd) 32.27 32.21 32.15 32.78 33.45 30.70 31.16 32.26 Relative Partial Dispersion (Pg, F) 0.590 0.588 0.590 0.589 0.587 0.594 0.593 0.589 proportion 3.14 3.23 3.14 3.13 3.13 3.19 3.17 3.18 Glass transition temperature Tg(℃) 548 570 550 537 528 574 559 562 λ70[nm] 385 378 389 384 383 389 392 381 λ5[nm] 345 330 346 345 344 349 349 341 -0.00286×vd+0.68900 0.597 0.597 0.597 0.595 0.593 0.601 0.600 0.597 SiO2+P2O5 37.04 35.71 37.63 37.71 38.06 37.09 36.37 37.12 SiO2+B2O3+P2O5 37.04 35.71 37.63 37.71 38.06 37.09 36.37 37.12 Li2O+Na2O+K2O+Cs2O 19.41 17.29 18.13 18.89 19.07 15.83 17.71 17.59 Li2O+Na2O+K2O 19.41 17.29 18.13 18.89 19.07 15.83 17.71 17.59 Nb2O5+TiO2 34.34 38.12 34.88 32.56 30.46 37.50 35.31 36.24 Nb2O5+TiO2+WO3+Bi2O3 34.34 38.12 34.88 32.56 30.46 37.50 35.31 36.24 MgO+CaO+SrO+BaO+ZnO 0.00 0.00 0.00 1.46 2.96 0.00 0.00 0.00 MgO+CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.02 0.02 0.02 0.03 0.03 0.02 0.02 0.02 P2O5/Nb2O5 0.03 0.02 0.03 0.03 0.03 0.02 0.03 0.02 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.01 0.01 0.02 0.02 0.02 0.01 0.01 0.01 P2O5/(Li2O+Na2O+K2O+Nb2O5) 0.04 0.01 0.04 0.04 0.04 0.05 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.82 1.00 0.82 0.81 0.80 0.85 0.79 0.92 SiO2/(SiO2+B2O3+P2O5) 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 P2O5/(SiO2+B2O3+P2O5) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.00 0.00 0.00 0.08 0.15 0.00 0.00 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.52 0.48 0.48 0.50 0.50 0.43 0.49 0.47 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.57 0.45 0.52 0.58 0.63 0.42 0.50 0.49 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 1.08 0.94 1.08 1.16 1.25 0.99 1.03 1.02 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.27 0.23 0.27 0.29 0.31 0.26 0.30 0.25

[Table 1-22]

Sample No. 126 127 128 129 P2O5 0.79 0.78 0.77 0.79 SiO2 37.06 35.52 35.03 35.81 Nb2O5 30.78 27.71 27.33 32.95 Li2O 5.49 5.62 5.54 5.58 Na2O 11.53 11.81 11.65 11.73 K2O 0.74 0.76 0.75 0.75 Cs2O - - - - ZrO2 9.12 9.03 8.90 9.10 TiO2 4.50 5.94 5.86 3.30 B2O3 - - - - MgO - - - - CaO - - - - SrO - - - - BaO - - - - ZnO - 2.82 4.17 - La2O3 - - - - Y2O3 - - - - WO3 - - - - Sb2O3 - - - - total 100 100 100 100 F-(anion%) - - - - Refractive index (nd) 1.72634 1.72935 1.73080 1.73051 Abbe number (νd) 32.29 32.16 32.15 32.19 Relative Partial Dispersion (Pg, F) 0.590 0.590 0.590 0.589 proportion 3.16 3.18 3.20 3.18 Glass transition temperature Tg(℃) 559 539 534 55 λ70[nm] 383 390 389 383 λ5[nm] 345 345 345 342 -0.00286×vd+0.68900 0.597 0.597 0.597 0.597 SiO2+P2O5 37.85 36.31 35.80 36.60 SiO2+B2O3+P2O5 37.85 36.31 35.80 36.60 Li2O+Na2O+K2O+Cs2O 17.75 18.19 17.94 18.06 Li2O+Na2O+K2O 17.75 18.19 17.94 18.06 Nb2O5+TiO2 35.28 33.66 33.19 36.24 Nb2O5+TiO2+WO3+Bi2O3 35.28 33.66 33.19 36.24 MgO+CaO+SrO+BaO+ZnO 0.00 2.82 4.17 0.00 MgO+CaO 0.00 0.00 0.00 0.00 P2O5/(Nb2O5+TiO2) 0.02 0.02 0.02 0.02 P2O5/Nb2O5 0.03 0.03 0.03 0.02 P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3) 0.01 0.02 0.02 0.01 p2O5/(Li2O+Na2O+K2O+Nb2O5) 0.04 0.02 0.04 0.04 Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3) 0.87 0.82 0.82 0.91 SiO2/(SiO2+B2O3+P2O5) 0.98 0.98 0.98 0.98 P2O5/(SiO2+P2O5) 0.02 0.02 0.02 0.02 P2O5/(SiO2+B2O3+P2O5) 0.02 0.02 0.02 0.02 (MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O+K2O+Cs2O) 0.00 0.15 0.23 0.00 (Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+P2O5) 0.47 0.50 0.50 0.49 (Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2+WO3+Bi2O3) 0.50 0.54 0.54 0.50 (SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3+Bi2O3) 1.07 1.08 1.08 1.01 ZrO2/(Nb2O5+TiO2+WO3+Bi2O3) 0.26 0.27 0.27 0.25

(Example 1-3)

Using each optical glass produced in Example 1-1 and Example 1-2, a lens blank was produced by a known method, and the lens blank was processed by a known method such as grinding to produce various lenses.

The optical lenses produced are various lenses such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses.

Various types of lenses can favorably correct secondary chromatic aberration by combining with lenses made of other types of optical glass.

In addition, since glass has a low specific gravity, each lens is lighter in weight than a lens having the same optical characteristics and size, and can be suitably used for various imaging devices, especially for autofocus for reasons of saving energy. type camera equipment. Similarly, prisms were produced using various optical glasses produced in Example 1-1 and Example 1-2.

"Example of the Second Invention"

Hereinafter, the second invention will be described in more detail with reference to Examples. However, the second invention is not limited to the embodiments shown in the examples.

(Example 2-1)

Glass samples having the glass compositions shown in Tables 2-1 to 2-4 were produced in the following procedure, and various evaluations were performed.

[Manufacture of Optical Glass]

First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of the glass are prepared as raw materials so that the glass compositions of the obtained optical glass become the respective compositions shown in Tables 2-1 to 2-4 The above-mentioned raw materials are weighed in the way of preparation, and the raw materials are fully mixed. The prepared raw materials (batch raw materials) thus obtained are put into a platinum crucible, heated at 1350°C to 1450°C for 2 to 5 hours to prepare a molten glass, stirred for homogenization, and after clarification, the molten glass is cast until preheated to Mold at the proper temperature. The glass after casting was heat-treated at a temperature lower than the glass transition temperature Tg by 100° C. for 30 minutes, and was naturally cooled to room temperature in a furnace to obtain a glass sample.

[Confirmation of glass composition]

About the obtained glass sample, the content of each glass component was measured by inductively coupled plasma emission spectrometry (ICP-AES), and it was confirmed that it matched each composition shown in Tables 2-1 to 2-4.

[Measurement of Optical Properties]

The obtained glass sample was further annealed in the vicinity of the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a temperature drop rate of -30°C/hour to obtain an annealed sample. The obtained annealed samples were measured for refractive index nd, ng, nF and nC, Abbe number νd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ70 and λ5. The results are shown in Tables 2-1 to 2-4.

(i) Refractive index nd, ng, nF, nC and Abbe number νd

For the above-mentioned annealed sample, the refractive indices nd, ng, nF, and nC were measured by the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the following formula.

νd=(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg,F

Using the respective refractive indices ng, nF, and nC in g-rays, F-rays, and C-rays, the relative partial dispersion Pg,F was calculated based on the following formula.

Pg,F=(ng-nF)/(nF-nC)

(iii) Deviation ΔPg,F’ relative to partial dispersion Pg,F

Using the relative partial dispersion Pg,F and Abbe's number νd, the calculation was performed based on the following formula.

ΔPg,F’=Pg,F+(0.00286×νd)-0.68900

(iv) Specific gravity

Specific gravity is determined by the Archimedes method.

(v) Glass transition temperature Tg

The glass transition temperature Tg was measured at a temperature increase rate of 10° C./min using a differential scanning calorimetry analyzer (DSC3300SA) manufactured by NETZSCH JAPAN.

(ⅵ) λ70, λ5

The above-mentioned annealed sample was processed to have a thickness of 10 mm and had planes that were parallel to each other and optically polished, and the spectral transmittance in the wavelength region of 280 nm to 700 nm was measured. The spectral transmittance B/A was calculated by setting the intensity of light perpendicularly incident on one optically polished plane as intensity A, and the intensity of light emitted from the other plane as intensity B. The spectral transmittance B/A was calculated by setting the wavelength at which the spectral transmittance was 70% as λ70. The wavelength at which the spectral transmittance is 5% is λ5. In addition, the reflection loss of the light beam on the sample surface is also included in the spectral transmittance.

[Stability during reheating]

The obtained glass sample was cut to obtain pieces of 10 mm×10 mm×7.5 mm in size. This fragment was heated for 5 minutes in a test furnace set to a temperature 200 to 220°C higher than the glass transition temperature Tg of the glass sample. The number of crystals per chip was measured with an optical microscope (observation magnification: 40 to 200 times). In addition, the presence or absence of crystals was confirmed with the naked eye. The case where the number of crystals per chip was 100 or less was rated as A, the case where the number of crystals per chip was more than 100 was rated as B, and the case where crystals were confirmed by visual inspection was rated as C . The results are shown in Tables 2-1 to 2-4.

[table 2-1]

[Table 2-2]

[Table 2-3]

[Table 2-4]

(Example 2-2)

Using each optical glass produced in Example 2-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as grinding to produce various lenses.

The optical lenses produced are various lenses such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses.

Various types of lenses can favorably correct secondary chromatic aberration by combining with lenses made of other types of optical glass.

In addition, since glass has a low specific gravity, each lens is lighter in weight than a lens having the same optical characteristics and size, and can be suitably used for various imaging devices, especially for autofocus for reasons of saving energy. type camera equipment. Similarly, prisms were produced using various optical glasses produced in Example 2-1.

"Example of the third invention"

Hereinafter, the third invention will be described in more detail with reference to Examples. However, the third invention is not limited to the embodiments shown in the examples.

(Example 3-1)

Glass samples having the glass compositions shown in Table 3-1 and Tables 3-2-1 to 3-2-2 were produced in the following procedure, and various evaluations were performed.

[Manufacture of Optical Glass]

First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of glass are prepared as raw materials, and the glass compositions of the obtained optical glass are weighed so that the respective compositions shown in Table 3-1 are obtained. The above-mentioned raw materials are prepared, and the raw materials are thoroughly mixed. The prepared raw materials (batch raw materials) thus obtained are put into a platinum crucible, heated at 1350°C to 1400°C for 2 hours to prepare a molten glass, stirred for homogenization, and after clarification, the molten glass is preheated to an appropriate temperature by casting. 's mold. The glass after casting was heat-treated at a temperature lower than the glass transition temperature Tg by 100° C. for 30 minutes, and was naturally cooled to room temperature in a furnace to obtain a glass sample.

[Confirmation of glass composition]

About the obtained glass sample, content of each glass component was measured by inductively coupled plasma optical emission spectrometry (ICP-AES), and it was confirmed that it matched each composition shown in Table 3-1.

[Stability during reheating]

The obtained glass sample was cut into a size of 1 cm x 1 cm x 0.8 cm, heated in a first test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and further set to a glass transition temperature higher than the glass transition temperature of the glass sample. It heated for 10 minutes in the 2nd test furnace of the temperature of 140-250 degreeC high Tg. Then, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. The presence or absence of cloudiness of the glass was confirmed with the naked eye. When the number of crystals per 1g was 20 or less and no cloudiness was observed, it was judged as "pass", and when the number of crystals per 1g was confirmed to be more than 20 or at least one of cloudiness was determined. is "unqualified". The results are shown in Tables 3-3-1 to 3-3-2.

[Measurement of Optical Properties]

The obtained glass sample was further annealed in the vicinity of the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a temperature drop rate of -30°C/hour to obtain an annealed sample. The obtained annealed samples were measured for refractive index nd, ng, nF and nC, Abbe number νd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ80, λ70 and λ5. The results are shown in Tables 3-3-1 to 3-3-2.

(i) Refractive index nd, ng, nF, nC and Abbe number νd

For the above-mentioned annealed sample, the refractive indices nd, ng, nF, and nC were measured by the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the following formula.

νd=(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg,F

Using the respective refractive indices ng, nF, and nC in g-rays, F-rays, and C-rays, the relative partial dispersion Pg,F was calculated based on the following formula.

Pg,F=(ng-nF)/(nF-nC)

(iii) Deviation ΔPg,F relative to partial dispersion Pg,F

Using the relative partial dispersion Pg,F and Abbe's number νd, the calculation was performed based on the following formula.

ΔPg,F=Pg,F+(0.0018×νd)-0.6483

(iv) Specific gravity

Specific gravity is determined by the Archimedes method.

(v) Liquidus temperature LT

The glass was placed in a furnace heated to a predetermined temperature, kept for about 2 hours, and after cooling, the inside of the glass was observed with an optical microscope at a magnification of 40 to 100 times, and the liquidus temperature was determined based on the presence or absence of crystals.

(vi) Glass transition temperature Tg

The glass transition temperature Tg was measured at a temperature increase rate of 10° C./min using a differential scanning calorimetry analyzer (DSC3300SA) manufactured by NETZSCH JAPAN.

(vii) λ80, λ70, λ5

The above-mentioned annealed sample was processed to have a thickness of 10 mm, and had mutually parallel and optically polished planes, and the spectral transmittance in the wavelength region of 280 nm to 700 nm was measured. The spectral transmittance B/A was calculated by setting the intensity of light perpendicularly incident on one optically polished plane as intensity A, and the intensity of light emitted from the other plane as intensity B. The wavelength of the spectral transmittance of 80% was set to λ80, and the spectral transmittance B/A was calculated. The wavelength at which the spectral transmittance is 70% is λ70, and the wavelength at which the spectral transmittance is 5% is λ5. In addition, the reflection loss of the light beam on the sample surface is also included in the spectral transmittance.

[Table 3-1]

No. SiO2 P2O5 Li2O Na2O K2O CaO ZnO Nb2O5 ZrO2 TiO2 total Sb2O3 3-1 37.79 0.80 5.53 11.63 0.74 0.00 0.00 28.24 9.20 6.06 100.00 0.020 3-2 38.09 0.00 5.58 11.73 0.75 0.00 0.00 28.47 9.28 6.11 100.00 0.020 3-3 37.89 0.80 5.55 12.15 0.00 0.00 0.00 28.31 9.22 6.07 100.00 0.020 3-4 37.98 0.80 5.80 11.69 0.00 0.00 0.00 28.39 9.25 6.09 100.00 0.020 3-5 38.51 0.00 5.54 11.65 0.75 0.00 0.00 28.28 9.21 6.07 100.00 0.020 3-6 37.96 0.00 5.56 12.04 0.75 0.00 0.00 28.37 9.24 6.09 100.00 0.020 3-7 38.03 0.00 5.74 11.71 0.75 0.00 0.00 28.42 9.26 6.10 100.00 0.020 3-8 35.28 0.82 6.02 12.69 0.84 0.00 0.00 28.79 9.38 6.18 100.00 0.020 3-9 35.30 0.82 6.05 12.70 0.76 0.00 0.00 28.81 9.39 6.18 100.00 0.020 3-10 35.19 0.81 5.76 13.16 0.84 0.00 0.00 28.72 9.36 6.16 100.00 0.020 3-11 35.37 0.82 6.28 12.22 0.85 0.00 0.00 28.87 9.40 6.19 100.00 0.020 3-12 33.57 0.83 6.37 13.43 0.86 0.00 0.00 29.18 9.51 6.26 100.00 0.020 3-13 33.70 0.83 6.79 12.63 0.92 0.00 0.00 29.30 9.55 6.28 100.00 0.020 3-14 31.81 0.84 6.74 14.19 0.87 0.00 0.00 29.58 9.64 6.35 100.00 0.020 3-15 35.23 0.81 5.94 12.68 1.05 0.00 0.00 28.75 9.37 6.17 100.00 0.020 3-16 35.26 0.81 5.95 12.82 0.84 0.00 0.00 28.77 9.37 6.17 100.00 0.020 3-17 35.33 0.82 6.09 12.71 0.63 0.00 0.00 28.83 9.39 6.18 100.00 0.020 3-18 35.31 0.82 6.09 12.56 0.84 0.00 0.00 28.81 9.39 6.18 100.00 0.020 3-19 35.26 0.81 6.01 12.55 1.06 0.00 0.00 28.77 9.37 6.17 100.00 0.020 3-20 35.31 0.82 6.02 12.84 0.63 0.00 0.00 28.81 9.39 6.18 100.00 0.020 3-21 35.20 0.81 5.94 12.53 1.26 0.00 0.00 28.73 9.36 6.16 100.00 0.020 3-22 37.44 0.79 5.48 11.52 0.74 0.00 0.00 30.30 9.12 4.60 100.00 0.020 3-23 36.55 0.81 5.78 12.15 0.78 0.00 0.00 28.52 9.29 6.12 100.00 0.020 3-24 36.45 0.81 5.77 11.57 1.61 0.00 0.00 28.44 9.26 6.10 100.00 0.020 3-25 36.66 0.81 6.07 11.64 0.78 0.00 0.00 28.60 9.32 6.13 100.00 0.020 3-26 36.34 0.80 5.49 12.08 1.61 0.00 0.00 28.35 9.24 6.08 100.00 0.020 3-27 36.40 0.80 5.76 11.28 2.03 0.00 0.00 28.39 9.25 6.09 100.00 0.020 3-28 36.71 0.81 6.21 11.37 0.78 0.00 0.00 28.64 9.33 6.14 100.00 0.020 3-29 36.24 0.80 5.34 12.05 2.02 0.00 0.00 28.27 9.21 6.06 100.00 0.020 3-30 36.82 0.81 6.50 10.85 0.78 0.00 0.00 28.72 9.36 6.16 100.00 0.020 3-31 36.33 0.76 4.89 10.29 0.66 0.00 0.00 31.75 9.57 5.76 100.00 0.020 3-32 35.58 0.79 5.47 11.50 0.74 0.00 0.00 27.93 10.60 7.38 100.00 0.020 3-33 37.06 0.79 5.49 11.53 0.74 0.00 0.00 30.78 9.12 4.50 100.00 0.020 3-34 35.52 0.78 5.62 11.81 0.76 0.00 2.82 27.71 9.03 5.94 100.00 0.020 3-35 39.07 0.00 5.62 11.82 0.76 3.02 0.00 26.30 11.55 1.86 100.00 0.020 3-36 38.40 0.00 5.56 11.69 0.75 2.98 0.00 28.39 11.43 0.78 100.00 0.020 3-37 38.88 0.00 6.04 12.68 0.76 0.00 0.00 30.06 11.58 0.00 100.00 0.020 3-38 39.90 0.00 5.78 12.15 0.78 3.10 0.00 19.70 11.88 6.70 100.00 0.020 3-39 35.81 0.79 5.58 11.73 0.75 0.00 0.00 32.95 9.10 3.30 100.00 0.020

(Example 3-2)

Using each optical glass produced in Example 3-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as grinding to produce various lenses.

The optical lenses produced are various lenses such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses.

Various types of lenses can favorably correct secondary chromatic aberration by combining with lenses made of other types of optical glass.

In addition, since glass has a low specific gravity, each lens is lighter in weight than a lens having the same optical characteristics and size, and can be suitably used for various imaging devices, especially for autofocus for reasons of saving energy. type camera equipment. Similarly, prisms were produced using various optical glasses produced in Example 3-1.

"Example of the Fourth Invention"

Hereinafter, the fourth invention will be described in more detail with reference to Examples. However, the fourth invention is not limited to the embodiments shown in the examples.

(Example 4-1)

Glass samples having the glass compositions shown in Tables 4-1 to 4-4 were produced in the following procedure, and various evaluations were performed.

[Manufacture of Optical Glass]

First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of the glass are prepared as raw materials so that the glass compositions of the obtained optical glass are each of the compositions shown in Tables 4-1 to 4-4 The above-mentioned raw materials are weighed in the way of preparation, and the raw materials are fully mixed. The prepared raw material (batch raw material) thus obtained is put into a platinum crucible, heated at 1350°C to 1450°C for 2 to 3 hours to prepare a molten glass, stirred for homogenization, and after clarification, the molten glass is cast until preheated to Mold at the proper temperature. The glass after casting was heat-treated at a temperature of glass transition temperature Tg±10° C. for 30 minutes, and was naturally cooled to room temperature in a furnace to obtain a glass sample.

[Confirmation of glass composition]

About the obtained glass sample, content of each glass component was measured by inductively coupled plasma optical emission spectrometry (ICP-AES), and it was confirmed that it matched each composition shown in Tables 4-1 to 4-4.

[Measurement of Optical Properties]

The obtained glass sample was further annealed in the vicinity of the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a temperature drop rate of -30°C/hour to obtain an annealed sample. The obtained annealed samples were measured for refractive indices nd, ng, nF and nC, Abbe number νd, relative partial dispersion Pg,F, deviation ΔPg,F, specific gravity, glass transition temperature Tg, λ80, λ70 and λ5. The results are shown in Tables 4-1 to 4-4. It should be noted that the glass samples obtained in Comparative Examples A and B had obvious streaks and were very inhomogeneous. Therefore, the refractive index nd, Abbe's number νd, relative partial dispersion Pg, F, and deviation could not be measured. ΔPg,F.

(i) Refractive index nd, ng, nF, nC and Abbe number νd

For the above-mentioned annealed sample, the refractive indices nd, ng, nF, and nC were measured by the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the following formula.

νd=(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg,F

Using the respective refractive indices ng, nF, and nC in g-rays, F-rays, and C-rays, the relative partial dispersion Pg,F was calculated based on the following formula.

Pg,F=(ng-nF)/(nF-nC)

(iii) Deviation ΔPg,F relative to partial dispersion Pg,F

Using the relative partial dispersion Pg,F and Abbe's number νd, the calculation was performed based on the following formula.

ΔPg,F=Pg,F+(0.0018×νd)-0.6483

(iv) Specific gravity

Specific gravity is determined by the Archimedes method.

(ⅴ) Liquidus temperature LT

The glass was placed in a furnace heated to a predetermined temperature, kept for about 2 hours, and after cooling, the inside of the glass was observed with an optical microscope at a magnification of 40 to 100 times, and the liquidus temperature was determined based on the presence or absence of crystals.

(vi) Glass transition temperature Tg

The glass transition temperature Tg was measured at a temperature increase rate of 10° C./min using a differential scanning calorimetry analyzer (DSC3300SA) manufactured by NETZSCH JAPAN.

(vii) λ80, λ70, λ5

The above-mentioned annealed sample was processed to have a thickness of 10 mm and had planes that were parallel to each other and optically polished, and the spectral transmittance in the wavelength region of 280 nm to 700 nm was measured. The spectral transmittance B/A was calculated by setting the intensity of light perpendicularly incident on one optically polished plane as intensity A, and the intensity of light emitted from the other plane as intensity B. The wavelength of the spectral transmittance of 80% was set to λ80, and the spectral transmittance B/A was calculated. The wavelength at which the spectral transmittance is 70% is λ70, and the wavelength at which the spectral transmittance is 5% is λ5. In addition, the reflection loss of the light beam on the sample surface is also included in the spectral transmittance.

[Stability during reheating]

The obtained glass sample was cut into a size of 1 cm x 1 cm x 0.8 cm, heated in a first test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and further set to a glass transition temperature higher than the glass transition temperature of the glass sample. It heated for 10 minutes in the 2nd test furnace at the temperature of 140-220 degreeC high Tg. Then, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. The presence or absence of cloudiness of the glass was confirmed with the naked eye. When the number of crystals per 1 g was 20 or less and no white turbidity was observed, it was judged as "good", when the number of crystals per 1 g was confirmed as 21 to 60, it was judged as "acceptable", and each was judged as "good". When the number of crystals corresponding to 1 g was more than 60, or when white turbidity or crystals were visually recognized, it was judged as "unacceptable".

[Evaluation of vitrification]

For the obtained glass sample, the presence or absence of crystals was confirmed with the naked eye or an optical microscope (observation magnification: 40 times), and if there was no crystal, it was evaluated as "pass", and if there was, it was evaluated as "fail".

Each optical glass of Example 4-1 was also optically homogeneous, and no streaks were observed. On the other hand, on each glass of Comparative Examples A and B produced under the same conditions as Example 4-1, clear streaks and very unevenness were observed. In Comparative Example C, crystals were also observed with the naked eye.

(Example 4-2)

Using each optical glass produced in Example 4-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as grinding to produce various lenses.

The optical lenses produced are various lenses such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses.

Various types of lenses can favorably correct secondary chromatic aberration by combining with lenses made of other types of optical glass.

In addition, since glass has a low specific gravity, each lens is lighter in weight than a lens having the same optical characteristics and size, and can be suitably used for various imaging devices, especially for autofocus for reasons of saving energy. type camera equipment. Similarly, prisms were produced using various optical glasses produced in Example 4-1.

It should be understood that the embodiments disclosed this time are all exemplary and do not constitute a limitation. The scope of the present invention is defined by the claims rather than the above-mentioned description, and it is intended that the meaning of the claims and the equivalents and all modifications within the scope are included.

For example, the optical glass which concerns on one Embodiment of 1st - 4th invention can be produced by performing the composition adjustment as described in the specification with respect to the glass composition exemplified above.

In addition, it is needless to say that two or more of the matters exemplified in the specification or described as preferable ranges can be combined arbitrarily.

Claims (12)

1. A silicate glass whose Abbe number νd is 20 to 35, contains P ₂ O ₅ and Nb ₂ O ₅ , and the relative partial dispersion Pg,F satisfies the following formula (1-1), Pg,F≤-0.00286×νd+0.68900...(1-1). 2. A silicate glass whose Abbe number νd is 20 to 35, contains P ₂ O ₅ and Nb ₂ O ₅ , and the content of Nb ₂ O ₅ is relative to that of Nb ₂ O ₅ , TiO ₂ , WO ₃ and The mass ratio of the total content of Bi ₂ O ₃ [Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ )] was greater than 0.6110. 3. An optical glass whose Abbe number νd is 26.0 or more, The content of SiO ₂ is more than 0 mass % and less than 40 mass %, The content of TiO ₂ is 0 to 15% by mass, The content of Nb ₂ O ₅ is 25 to 45% by mass, _The content of ZrO2 is greater than 0 mass%, The mass ratio of the content of B ₂ O ₃ to the content of SiO ₂ [B ₂ O ₃ /SiO ₂ ] is 0.800 or less, The mass ratio of the total content of SiO ₂ and B ₂ O ₃ to the total content of Nb ₂ O ₅ and TiO ₂ [(SiO ₂ +B ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ )] is 0.950 or less, The total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O+Na ₂ O+K ₂ O] is 10 to 25% by mass, The mass ratio of the content of Na ₂ O to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.330 or more, The mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li ₂ O, Na ₂ O and K ₂ O [(MgO+CaO+SrO+BaO+ZnO)/(Li ₂ O+Na ₂ O+K ₂ O)] is below 0.480, The mass ratio of the content of TiO ₂ to the content of Nb ₂ O ₅ [TiO ₂ /Nb ₂ O ₅ ] is 0.340 or less, Mass ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of TiO ₂ and Nb ₂ O ₅ [(Li ₂ O+Na ₂ O+K ₂ O)/(TiO ₂ +Nb ₂ O ₅ )] is below 0.700, SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, ZnO, La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , the total content of ZrO ₂ , TiO ₂ and Nb ₂ O ₅ is 96.0 mass % or more, The contents of PbO, CdO and As ₂ O ₃ are respectively 0.01 mass % or less. 4. An optical glass, wherein, The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05, The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25, The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65, The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass, The optical glass satisfies one or more of the following (a) and (b): (a) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 9 mass %, (b) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.6, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO. 5. An optical glass, wherein, The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05, The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25, The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65, The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass, The mass ratio of the content of Ta ₂ O ₅ to the total content of TiO ₂ and Nb ₂ O ₅ [Ta ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ )] is less than 0.3, The optical glass satisfies one or more of the following (c) and (d): (c) the total content R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %, (d) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO. 6. An optical glass, wherein, The mass ratio of the content of SiO ₂ to the content of Nb ₂ O ₅ [SiO ₂ /Nb ₂ O ₅ ] is greater than 1.05, The mass ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ [ZrO ₂ /Nb ₂ O ₅ ] is greater than 0.25, The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.65, The total content of TiO ₂ and BaO [TiO ₂ +BaO] is less than 10% by mass, The mass ratio of the content of ZnO to the content of Nb ₂ O ₅ [ZnO/Nb ₂ O ₅ ] is less than 0.14, The optical glass satisfies one or more of the following (e) and (f): (e) the total content of R ₂ O of Li ₂ O, Na ₂ O and K ₂ O is more than 1.1 mass %, (f) The mass ratio of the total content of R ₂ O to the total content of the total content of R ₂ O and the total content of R'O [R ₂ O/(R ₂ O+R'O)] is greater than 0.05, and the total content of R ₂ O is the total content of Li ₂ O, Na ₂ O, and K ₂ O, and the total content R'O is the total content of MgO, CaO, SrO, and BaO. 7. An optical glass having an Abbe number νd of 30 to 36, a specific gravity of 3.19 or less, and a deviation ΔPg,F from partial dispersion Pg,F of 0.0015 or less. 8. An optical glass, wherein, The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80, The mass ratio of the content of SiO ₂ to the content of Na ₂ O [SiO ₂ /Na ₂ O] is 2.5 to 8.5, Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55, The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more, The total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84% by mass. 9. An optical glass, wherein, The mass ratio of the content of SiO ₂ to the total content of Nb ₂ O ₅ and TiO ₂ [SiO ₂ /(Nb ₂ O ₅ +TiO ₂ )] is greater than 0.80, The mass ratio of the total content of TiO ₂ and Nb ₂ O ₅ to the total content of SiO ₂ and B ₂ O ₃ [(TiO ₂ +Nb ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )] is greater than 0.7, Mass ratio of the total content of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ to the total content of Li ₂ O, Na ₂ O and K ₂ O [(SiO ₂ +B ₂ O ₃ +P ₂ O ₅ )/ (Li ₂ O+Na ₂ O+K ₂ O)] is 1.45～4.55, The mass ratio of the Na ₂ O content to the total content of Li ₂ O, Na ₂ O and K ₂ O [Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is 0.45 or more, The total content [SiO ₂ +Nb ₂ O ₅ ] of SiO ₂ and Nb ₂ O ₅ is 62 to 84% by mass. 10. An optical glass having an Abbe number νd of 30 to 36, a specific gravity of 3.4 or less, and a deviation ΔPg,F from partial dispersion Pg,F of 0.0030 or less. 11. An optical glass formed of the glass according to claim 1 or 2. 12 . An optical element formed of the optical glass according to claim 3 .