CN115140936A

CN115140936A - Optical glass and optical element

Info

Publication number: CN115140936A
Application number: CN202210326735.8A
Authority: CN
Inventors: 岛田惠太; 庄司昂浩; 根岸智明
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2021-03-31
Filing date: 2022-03-29
Publication date: 2022-10-04

Abstract

The invention provides an optical glass and an optical element having a small Abbe number ν d and a high relative partial dispersion PC, t in an infrared wavelength region. Among the optical glasses, siO ₂ Is 20 mass% or more, B ₂ O ₃ Is 15 mass% or more, zrO ₂ Is 5 mass% or more, nb ₂ O ₅ The content of (B) exceeds 5 mass%, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ SiO and the sum of the total contents R' O of O, mgO, caO, srO, baO and ZnO ₂ And B ₂ O ₃ (ii) the mass ratio of the total content of [ (R) ₂ O+R’O)/(SiO ₂ +B ₂ O ₃ )]0.36 or less, B ₂ O ₃ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ B ] ₂ O ₃ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]Is 0.74 or more, zrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Is 22 mass% or more, and the optical glass contains substantially no Pb.

Description

Optical glass and optical element

Technical Field

The present invention relates to an optical glass and an optical element having desired optical properties.

Background

Most of surveillance cameras and security cameras have a night vision function, and imaging performance in an infrared wavelength region is required for their imaging optical systems. In general, imaging performance in the infrared wavelength region is not required for optical systems such as single-lens reflex cameras and mirror-less cameras, which place importance on imaging performance in the visible short wavelength region.

In order to compensate for the chromatic aberration of the higher order, two lenses are sometimes combined. Examples of the two lenses include a combination of a convex lens and a concave lens, a combination of a low dispersion lens and a high dispersion lens, and the like. For these two lenses, it is desirable that the difference in abbe number is large and the difference in relative partial dispersion in each wavelength region is small.

Of the two lenses, a fluorophosphate glass having low dispersibility and anomalous dispersibility may be used as one lens. Fluorophosphate glasses having low dispersibility and anomalous partial dispersibility are generally higher in abbe number vd and relative partial dispersion PC in the infrared wavelength region, and t than lenses used in combination with them. Therefore, in the case of improving the imaging performance in the near infrared region, it is required that the abbe number ν d of a glass used as another lens combined with a fluorophosphate glass lens is smaller than the fluorophosphate glass, and PC, t is as close as possible to the value of the fluorophosphate glass, that is, Δ PC, t is large. In order to improve the imaging performance in the visible short wavelength region, it is required that Δ Pg and F be small for the same reason as the glass used as another lens combined with the fluorophosphate glass lens.

In the case of a glass having high dispersion properties, when the abbe number ν d is reduced by increasing the content of glass components contributing to high dispersion in the glass composition, it is common that the relative partial dispersion Pg, F in the short wavelength region is increased and the relative partial dispersion PC, t in the infrared wavelength region is decreased. Since the difference between PC and t of the above-mentioned fluorophosphate glass is large, the lens made of such a glass having high dispersion cannot sufficiently compensate for chromatic aberration in the visible long wavelength region, and is not particularly suitable as a lens used for a night vision camera.

Patent documents 1 and 2 propose optical glasses having dispersion properties in a predetermined range, focusing on anomalous partial dispersion properties, but do not pay any attention to relative partial dispersion PC, t in the infrared wavelength region.

Therefore, as a lens combined with a fluorophosphate glass lens in order to compensate for high-order chromatic aberration over the entire near-infrared wavelength region, a lens made of a glass having a high PC, t is required.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 10-130033

Patent document 2: japanese patent laid-open publication No. 2017-095348

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical glass and an optical element having a small abbe number ν d and a high relative partial dispersion PC, t in an infrared wavelength region. In view of the above, a glass in which t is not excessively decreased with respect to the partial dispersion PC even when the dispersion is made high has been searched for, and the present invention has been completed.

Means for solving the problems

The gist of the present invention is as follows.

(1) An optical glass, wherein,

SiO ₂ the content of (B) is 20% by mass or more,

B ₂ O ₃ the content of (B) is 15% by mass or more,

ZrO ₂ the content of (B) is 5% by mass or more,

Nb ₂ O ₅ the content of (B) exceeds 5 mass%,

Li ₂ O、Na ₂ o and K ₂ Total content R of O ₂ The sum of O and the total content R' O of MgO, caO, srO, baO and ZnO, and SiO ₂ And B ₂ O ₃ (ii) the mass ratio of the total content of [ (R) ₂ O+R’O)/(SiO ₂ +B ₂ O ₃ )]Is a content of not more than 0.36,

B ₂ O ₃ with ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ B ] ₂ O ₃ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]Is a content of at least 0.74,

ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ and Ta ₂ O ₅ The total content of (B) is 22 mass% or more,

the optical glass contains substantially no Pb.

(2) An optical glass, wherein,

as a component of the glass, a glass,

containing SiO ₂ 、B ₂ O ₃ 、ZrO ₂ And Nb ₂ O ₅ ，

And contains Li ₂ O、Na ₂ O and K ₂ At least one of O and a nitrogen-containing compound,

the optical glass has a Δ PC, t of 0.0250 or more.

(3) An optical glass, wherein,

Si ⁴⁺ the content of (A) is more than 10 cation percent,

B ³⁺ the content of (A) is more than 20 cation percent,

Si ⁴⁺ and B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]Is more than 50 percent of positive ions,

B ³⁺ with Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is not less than 0.44 of the total weight of the composition,

Li ⁺ 、Na ⁺ and K ⁺ With the total content R and Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (B) is [ R/(R + R')]Is a content of at least 0.55,

Nb ⁵⁺ the content of (A) is more than 0 cation% and 11.5 cation% or less,

the optical glass satisfies one or more of the following (i) and (ii).

(i)Zr ⁴⁺ The content of (B) and the total content R' and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]Is 0.17 or more.

(ii)Zr ⁴⁺ And Ta ⁵⁺ The total content of (A) and the above total content of R' and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]Is 0.25 or more.

(4) The optical glass according to (3), wherein Zr ⁴⁺ And Ta ⁵⁺ The total content of (A) is 8.5 cation% or less.

(5) The optical glass according to (3) or (4), wherein Zr ⁴⁺ And Ta ⁵⁺ Total content of (A) and R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]Is less than 3.10, allR' is Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (a).

(6) An optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

And contains Li ⁺ 、Na ⁺ And K ⁺ One or more of the above-mentioned (B) compounds,

the optical glass has a Δ PC, t of 0.0250 or more.

(7) An oxide optical glass, wherein,

Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ and Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ ]Is more than 6.5 percent of positive ions,

Li ⁺ 、Na ⁺ and K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is a content of at least 0.55,

Zr ⁴⁺ content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the organic acid is more than 0.4,

Si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ and Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the organic acid is more than 8.6,

the oxide optical glass is substantially free of Pb and As,

PC, t of the oxide optical glass satisfies the following formula [2-2],

PC,t≥0.5711+0.004667×νd···[2-2]

the oxide optical glass satisfies one or more of the following (I) to (IV),

(I)Li ⁺ 、Na ⁺ and K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]The content of the compound is less than 0.85,

(II)Li ⁺ 、Na ⁺ and K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]The content of the compound is less than 0.97%,

Li ⁺ 、Na ⁺ 、Mg ²⁺ and Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is a content of at least 0.75,

(III)B ³⁺ with Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is a content of at least 0.46,

(IV)Li ⁺ 、Na ⁺ and K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is a content of at least 0.75,

B ³⁺ and Li ⁺ Total content of (D) and Si ⁴⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]Is 0.31 or more.

(8) An oxide optical glass, wherein,

Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ and Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ ]Is more than 6.5 cation percent,

B ³⁺ with Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is 0.41 or more and less than 1,

Li ⁺ 、Na ⁺ and K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is a content of at least 0.55,

Zr ⁴⁺ in an amount of and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the organic acid is more than 0.4,

Si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ and Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the acid-resistant agent is more than 8.6,

the oxide optical glass is substantially free of Pb and As,

the oxide optical glass satisfies one or more of the following (I) to (IV),

(II)Li ⁺ 、Na ⁺ and K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]The content of the compound is less than 0.97%,

B ³⁺ and Li ⁺ Total content of (A) and Si ⁴⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]Is 0.31 or more.

(9) An oxide optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

the oxide optical glass has Δ Pg, F and Δ PC, t satisfying the following (i) or (ii),

(i) When the delta Pg and the F are more than-0.0037, the delta PC, t is more than or equal to 2.875 multiplied by the delta Pg and F +0.031.

(ii) When Δ Pg and F are-0.0037 or less, Δ PC, t is not less than 4.750 XΔ Pg and F +0.038.

(10) An oxide optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

And contains Li ⁺ 、Na ⁺ And K ⁺ One of the method comprises the following steps of (1) preparing a mixture of the seed and the seed,

PC, t of the oxide optical glass satisfies the following formula [2-1],

PC,t≥0.5661+0.004667×νd···[2-1]。

(11) The oxide optical glass according to (10), wherein Pg and F satisfy the following formula [1-1],

Pg,F≤0.6463-0.001802×νd···[1-1]。

(12) The optical glass according to any one of (7) to (11),

Nb ⁵⁺ and Ti ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Nb) ⁵⁺ +Ti ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]Is 0.5 or more.

(13) An optical element comprising the optical glass according to any one of the above (1) to (12).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided an optical glass and an optical element having a small Abbe's number ν d and a high relative partial dispersion PC, t in an infrared wavelength region.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The content of the glass component can be quantified by a known method, for example, inductively coupled plasma emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), or the like.

In the present specification, the thermal stability of glass and the stability during reheating both mean the degree of difficulty in crystal precipitation in glass. In particular, thermal stability refers to the degree of difficulty in crystal precipitation when the glass in a molten state is solidified, and stability at the time of reheating refers to the degree of difficulty in crystal precipitation when the solidified glass is reheated as in reheat pressing.

In the present specification, unless otherwise specified, the refractive index is a refractive index nd of helium at d-ray (wavelength 587.56 nm).

Hereinafter, the optical glass of the present invention will be described in embodiments 1 (embodiments 1-1 and 1-2), 2 (embodiments 2-1 and 2-2), and 3 (embodiments 3-1, 3-2, 3-3, and 3-4).

Embodiment 1

In embodiment 1 (embodiment 1-1 and embodiment 1-2), the glass composition of the optical glass is expressed on an oxide basis unless otherwise specified. Here, the "oxide-based glass composition" refers to a glass composition obtained by converting all glass raw materials decomposed during melting into substances existing in the form of oxides in optical glass, and the expression of each glass component is conventionally described as SiO ₂ 、TiO ₂ And so on. In embodiment 1 (embodiment 1-1 and embodiment 1-2), the content and the total content of the glass component are based on mass, and "%" means "% by mass" unless otherwise specified. In the present specification and the present invention, the content of the constituent component of 0% means that the constituent component is not substantially containedIn particular, it is allowable to contain the component at a level of inevitable impurities.

1 st embodiment

In the 1 st to 1 st embodiments, the glass composition is designed based on the criteria shown below. That is to say that the first and second electrodes,<1>in SiO containing a large amount of a component which causes a relative partial dispersion PC, t in the infrared wavelength region to increase ₂ And B ₂ O ₃ At the same time, the utility model can simultaneously,<2>SiO is appropriately mixed ₂ Is partially replaced by B ₂ O ₃ High dispersion is realized without greatly reducing PC, t,<3>for the purpose of improving the meltability and moldability due to further increase in the dispersion and decrease in the viscosity, an alkali metal oxide and an alkaline earth metal oxide are appropriately introduced,<4>the amount of a high-dispersion component which is required for obtaining a desired Abbe number and which also reduces the PC, t component is minimized, thereby positively introducing Nb which can relatively reduce the reduction of PC, t among the high-dispersion components ₂ O ₅ And ZrO capable of simultaneously achieving suppression of reduction in PC, t and improvement in chemical durability of glass ₂ Thus, the optical glass with small Abbe number vd and high relative partial dispersion PC, t in the infrared wavelength region is completed. The optical glass of the embodiment 1-1 is as follows.

In the optical glass of embodiment 1-1,

SiO ₂ the content of (A) is more than 20%,

B ₂ O ₃ the content of (A) is more than 15%,

ZrO ₂ the content of (A) is more than 5%,

Nb ₂ O ₅ the content of (a) is more than 5%,

ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ and Ta ₂ O ₅ The total content of (A) is more than 22%,

and the optical glass contains substantially no Pb.

In the optical glass of embodiment 1-1, siO ₂ The content of (A) is 20% or more. SiO 2 ₂ The lower limit of the content of (b) is preferably 24%, and more preferably 26% and 28%. In addition, siO ₂ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, and 35% in this order. SiO 2 ₂ Is a network forming component of the glass. By making SiO ₂ The content of (b) is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving chemical durability. SiO 2 ₂ When the content of (b) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability and chemical durability of the glass may be lowered. SiO 2 ₂ When the content of (b) is too large, there is a possibility that the meltability of the glass is lowered, and the viscosity of the molten glass is increased to deteriorate the moldability.

In the optical glass of embodiment 1-1, B ₂ O ₃ The content of (A) is more than 15%. B is ₂ O ₃ The lower limit of the content of (b) is preferably 17%, and more preferably 19% and 21%. In addition, B ₂ O ₃ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, and 35% in this order. B is ₂ O ₃ Is a network forming component of the glass. By making B ₂ O ₃ The content of (b) is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be improved. B is ₂ O ₃ When the content of (A) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability of the glass is loweredPatients suffer from it. B is ₂ O ₃ If the content of (2) is too large, the chemical durability of the glass may be deteriorated.

In the optical glass of embodiment 1-1, zrO ₂ The content of (A) is 5% or more. ZrO (ZrO) ₂ The lower limit of the content of (b) is preferably 6.5%, and more preferably 8.0% and 9.5%. In addition, zrO ₂ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, and 15% in this order. By making ZrO ₂ The content of (b) is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving chemical durability. ZrO (ZrO) ₂ When the content of (b) is too small, there is a possibility that chemical durability is lowered. ZrO (ZrO) ₂ If the content (b) is too large, there is a possibility that the liquid phase temperature LT increases and the stability during reheating decreases.

In the optical glass of embodiment 1-1, nb ₂ O ₅ The content of (2) exceeds 5%. Nb ₂ O ₅ The lower limit of the content of (b) is preferably 6.5%, and more preferably 8.0% and 9.5%. In addition, nb ₂ O ₅ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, and 15% in this order. By making Nb ₂ O ₅ The content of (b) is in the above range, and the relative partial dispersion PC, t in the infrared wavelength region can be suppressed from lowering while maintaining high dispersion. Nb ₂ O ₅ When the content of (B) is too small, there is a possibility that the high dispersibility cannot be maintained. Nb ₂ O ₅ If the content of (b) is too large, there is a risk of lowering the relative partial dispersion PC, t in the infrared wavelength region.

In the optical glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ The sum of O and the total content R' O of MgO, caO, srO, baO and ZnO, and SiO ₂ And B ₂ O ₃ (ii) the mass ratio of the total content of [ (R) ₂ O+R’O)/(SiO ₂ +B ₂ O ₃ )]Is 0.36 or less. The upper limit of the mass ratio is preferably 0.35, and more preferably 0.34 and 0.33 in this order. The lower limit of the mass ratio is preferably 0.05, and more preferably 0.10, 0.15, and 0.20 in this order. By passingWhen the mass ratio is within the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, and the chemical durability can be improved.

In this specification, li is sometimes used ₂ O、Na ₂ O and K ₂ The total content of O is referred to as R ₂ The total content of O, mgO, caO, srO, baO and ZnO is sometimes referred to as R' O.

In the optical glass of embodiment 1-1, B ₂ O ₃ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ B ] ₂ O ₃ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]Is 0.74 or more. The lower limit of the mass ratio is preferably 0.84, and more preferably 0.94 and 1.04 in this order. The upper limit of the mass ratio is preferably 3.0, and more preferably 2.5, 2.0, and 1.5. By setting the mass ratio in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be improved.

In the optical glass of embodiment 1-1, zrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Total content of [ ZrO ] ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ]Is more than 22 percent. The lower limit of the total content is preferably 22.5%, and more preferably 23.0% and 23.5% in this order. The upper limit of the total content is preferably 40%, and more preferably 35%, 30%, and 25% in this order. When the total content is in the above range, the refractive index nd can be increased to set the abbe number ν d in a desired range.

The optical glass of embodiment 1-1 contains substantially no Pb which is a component having an environmental burden. That is, the content of Pb is preferably 0% in terms of oxide. As and Th are also components having a potential for environmental burden, similarly to Pb. Therefore, the content of each of As and Th is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01% in terms of oxide. The respective contents of As and Th are preferably 0% in terms of oxide. That is, both As and Th are preferably substantially not included.

Hereinafter, preferred contents of glass components in the optical glass of embodiment 1 to 1 will be described.

In the optical glass of embodiment 1-1, siO ₂ And B ₂ O ₃ Total content of [ SiO ] ₂ +B ₂ O ₃ ]The lower limit of (b) is preferably 35%, and more preferably 40%, 45%, and 50% in this order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, and 57% in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region and maintaining the thermal stability of the glass, it is preferable to set the total content to the above range. When the total content is too small, the relative partial dispersion PC, t in the infrared wavelength region is reduced, and there is a risk that the thermal stability and chemical durability of the glass cannot be maintained. If the total content is too large, the viscosity of the molten glass may increase, and the moldability may deteriorate. In addition, there is a risk of lowering the refractive index.

In the optical glass of embodiment 1-1, B ₂ O ₃ Content of (D) and SiO ₂ And B ₂ O ₃ The mass ratio of the total content of [ B ] ₂ O ₃ /(SiO ₂ +B ₂ O ₃ )]The lower limit of (b) is preferably 0.20, and more preferably 0.25, 0.30, and 0.35 in this order. The upper limit of the mass ratio is preferably 0.65, and more preferably 0.60, 0.55, and 0.50. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the mass ratio to the above range. When the mass ratio is too small, there is a risk that the relative partial dispersion PC, t is reduced. If the mass ratio is too large, the chemical durability of the glass may be reduced.

In the optical glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ O and the total content R ₂ The mass ratio [ R ] of O to the total of the total contents R' O of MgO, caO, srO, baO and ZnO ₂ O/(R ₂ O+R’O)]The lower limit of (b) is preferably 0.20, and more preferably 0.25, 0.30 or 0.35 in this order. The upper limit of the mass ratio is preferably 1, and more preferably 0.95, 0.90, and 0.85 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the mass ratio in the above range. When the mass ratio is too small, there is a risk that the relative partial dispersion PC, t decreases. When the mass ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

In the optical glass of embodiment 1-1, zrO ₂ With respect to the total content of MgO, caO, srO, baO and ZnO R' O and Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ ZrO ] ₂ /(R’O+Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]The lower limit of (b) is preferably 0.20, and more preferably 0.25, 0.30 or 0.35. The upper limit of the mass ratio is preferably 1.5, and more preferably 1.25, 1.00, and 0.70 in this order. From the viewpoint of improving chemical durability, increasing refractive index nd, and maintaining high dispersion properties, it is preferable to set the mass ratio within the above range. When the mass ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. If the mass ratio is too large, there is a possibility that the liquid phase temperature LT increases and the stability during reheating decreases.

In the optical glass of embodiment 1-1, zrO ₂ And Ta ₂ O ₅ The total content of (A) and the total contents of MgO, caO, srO, baO and ZnO R' O and Nb ₂ O ₅ 、TiO ₂ 、Bi ₂ O ₃ And WO ₃ (iii) the mass ratio of the total content of [ (ZrO) ₂ +Ta ₂ O ₅ )/(R’O+Nb ₂ O ₅ +TiO ₂ +Bi ₂ O ₃ +WO ₃ )]The lower limit of (b) is preferably 0.1, and more preferably 0.2, 0.3, and 0.4 in this order. The upper limit of the mass ratio is preferably 1.3, and more preferably 1.1, 0.9, and 0.7 in this order. From increasing the infrared wavelengthThe mass ratio is preferably in the above range from the viewpoints of relative partial dispersion PC, t of the region, improvement of refractive index nd, maintenance of high dispersion properties, and maintenance of chemical durability of the glass. When the mass ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. When the mass ratio is too large, there is a risk that the thermal stability of the glass is lowered.

In the optical glass of embodiment 1-1, zrO ₂ And Ta ₂ O ₅ Total content of [ ZrO ] ₂ +Ta ₂ O ₅ ]The lower limit of (b) is preferably 6%, and more preferably 7%, 8%, and 9% in this order. The upper limit of the total content is preferably 20%, and more preferably 18%, 16%, and 14% in this order. From the viewpoint of maintaining the thermal stability of the glass, it is preferable to set the total content to the above range. When the total content is too small, the chemical durability of the glass may be deteriorated. When the total content is too large, there is a risk of lowering the thermal stability of the glass and a risk of increasing the cost of raw materials.

The contents and ratios of the glass components other than those described above in the optical glass of embodiment 1-1 are non-limiting examples as follows.

In the optical glass of embodiment 1-1, P ₂ O ₅ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, and 5% in this order. In addition, P ₂ O ₅ The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.5%, and 1% in this order. P ₂ O ₅ The content of (B) may be 0%. By making P ₂ O ₅ The content of (b) is in the above range, and the thermal stability of the glass can be maintained.

In the optical glass of embodiment 1-1, al ₂ O ₃ The upper limit of the content of (b) is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1.75%, 1.50%, and 1.25% in this order. In addition, al ₂ O ₃ The lower limit of the content of (b) is preferably 0%, and more preferably 0.25%, 0.50%, and 0.75% in this order. Al (Al) ₂ O ₃ The content of (B) may be 0%. Al (Al) ₂ O ₃ Has a through holeThe glass is excessively contained in an appropriate amount to inhibit the phase separation of the glass. On the other hand, from the viewpoint of maintaining the thermal stability of the glass, it is preferable to use Al ₂ O ₃ The content of (B) is in the above range.

In the optical glass of embodiment 1-1, siO ₂ 、B ₂ O ₃ And Al ₂ O ₃ Total content of [ SiO ] ₂ +B ₂ O ₃ +Al ₂ O ₃ ]The lower limit of (b) is preferably 42%, and more preferably 45%, 48%, and 51%, in this order. The upper limit of the total content is preferably 74%, and more preferably 71%, 68%, and 65% in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, maintaining the thermal stability of the glass, and the stability at reheating, it is preferable to set the total content to the above range.

In the glass of embodiment 1-1, li ₂ The upper limit of the content of O is preferably 20%, and more preferably 15%, 10%, and 6% in this order. In addition, li ₂ The lower limit of the content of O is preferably 0%, and more preferably 1%, 2%, and 3% in this order. Li ₂ The content of O may be 0%. Li ₂ O is a component contributing to lowering the viscosity of the glass, and in alkali metals, the effect of increasing the relative partial dispersion PC, t in the infrared wavelength region is large. Li ₂ When the content of O is too large, stability during reheating may be lowered. In addition, li ₂ When the content of O is too small, the viscosity of the glass may increase.

In the glass of embodiment 1-1, na ₂ The upper limit of the content of O is preferably 20%, and more preferably 18%, 16%, and 14% in this order. In addition, na ₂ The lower limit of the content of O is preferably 0%, further, 1%, 2%, and 3% are more preferable in this order. Na (Na) ₂ O and Li ₂ O is a component contributing to the low viscosity of the glass as well. Na (Na) ₂ When the content of O is too large, stability during reheating may be lowered. In addition, na ₂ When the content of O is too small, the viscosity of the glass may increase.

In the optical glass of embodiment 1-1, K ₂ Upper limit of O contentPreferably 20%, and more preferably 18%, 16%, and 14% in this order. In addition, K ₂ The lower limit of the content of O is preferably 0%, and more preferably 1%, 2%, and 3% in this order. K ₂ The content of O may be 0%.

K ₂ O has the functions of lowering the liquid phase temperature and improving the thermal stability of the glass. On the other hand, K ₂ When the content of O is too large, chemical durability, weather resistance, and stability at reheating are lowered. Thus, K ₂ The content of O is preferably in the above range.

In the optical glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ O[Li ₂ O+Na ₂ O+K ₂ O]The upper limit of (b) is preferably 25%, and more preferably 20%, 15%, and 10% in this order. In addition, the total content R ₂ The lower limit of O is preferably 1%, and more preferably 2.5%, 4.0%, and 5.5% in this order. From the viewpoint of suppressing the decrease in stability during reheating, it is preferable to set the total content R ₂ O is in the above range.

In the optical glass of embodiment 1-1, li ₂ Content of O and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ Mass ratio of O [ Li ] ₂ O/R ₂ O]The upper limit of (b) is preferably 1, and more preferably 0.8, 0.6 or 0.4. The lower limit of the mass ratio is preferably 0, and more preferably 0.1, 0.2, and 0.3 in this order. The mass ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, na (Na) ₂ Content of O and Li ₂ O、Na ₂ O and K ₂ Total of O content R ₂ Mass ratio of O [ Na ] ₂ O/R ₂ O]The upper limit of (b) is preferably 1, and more preferably 0.9, 0.8, and 0.7 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.1, 0.2, and 0.3 in this order. The mass ratio may be 0. From the viewpoint of suppressing the decrease in stability during reheating, the mass ratio is preferably in the above range.

In the optical glass of embodiment 1-1, K ₂ Content of O and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ Mass ratio of O [ K ] ₂ O/R ₂ O]The upper limit of (b) is preferably 1, and more preferably 0.8, 0.6 and 0.4 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.1, 0.2, and 0.3 in this order. The mass ratio may be 0. From the viewpoint of suppressing the reduction in stability during reheating, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, cs ₂ The upper limit of the content of O is preferably 20%, and more preferably 15%, 10%, and 5% in this order. Cs ₂ The lower limit of the content of O is preferably 0%. Cs ₂ The content of O may be 0%.

Cs ₂ O has an effect of improving the thermal stability of the glass, but when the content is increased, there is a risk of lowering the chemical durability and weather resistance. Thus, cs ₂ The content of O is preferably in the above range.

In the optical glass of embodiment 1-1, tiO ₂ The upper limit of the content of (b) is preferably 30%, and more preferably 15%, 8%, 6%, and 4% in this order. In addition, tiO ₂ The lower limit of the content of (b) is preferably 0%. TiO 2 ₂ The content of (B) may be 0%. By making TiO ₂ The content of (b) is within the above range, and thus a desired optical constant can be realized while suppressing an increase in specific gravity.

In the optical glass of the embodiment 1-1, WO ₃ The upper limit of the content of (b) is preferably 30%, and more preferably 15%, 8%, 6%, 4%, 2%, 1% in this order. WO ₃ The lower limit of the content of (b) is preferably 0%. WO ₃ The content of (B) may be 0%. From the viewpoints of improving the transmittance, suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region, and reducing the specific gravity, it is preferable to use WO ₃ The content of (B) is in the above range.

In the optical glass of embodiment 1-1, bi ₂ O ₃ The upper limit of the content of (b) is preferably 30%, and more preferably 15%, 10%, and 8% in this order. In addition, the first and second substrates are,Bi ₂ O ₃ the lower limit of the content of (b) is preferably 0%, and more preferably 2%, 4%, and 6% in this order. Bi ₂ O ₃ The content of (b) may be 0%. From the viewpoint of improving the transmittance and reducing the specific gravity, and from the viewpoint of reducing damage to platinum manufacturing equipment, it is preferable to use Bi ₂ O ₃ The content of (B) is in the above range.

In the optical glass of embodiment 1-1, ta ₂ O ₅ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4%, 2% in this order. In addition, ta ₂ O ₅ The lower limit of the content of (b) is preferably 0%, and more preferably 0.5%, 1%, and 1.5% in this order. Ta ₂ O ₅ The content of (b) may be 0%.

Ta ₂ O ₅ The component (A) is a component which imparts high refraction and low dispersion to glass and increases relative partial dispersion PC, t in an infrared wavelength region. On the other hand, ta ₂ O ₅ When the content of (B) is increased, the raw material cost is increased. Further, there is a risk of an increase in specific gravity. Thus, ta ₂ O ₅ The content of (b) is preferably in the above range.

In the optical glass of embodiment 1-1, nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Bi ₂ O ₃ Total content of [ Nb ] ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ ]The upper limit of (b) is preferably 40%, and more preferably 35%, 30%, and 25% in this order. The lower limit of the total content is preferably 5%, and more preferably 7%, 9%, and 11% in this order. From the viewpoint of maintaining a high refractive index, the total content is preferably set to the above range.

In the optical glass of embodiment 1-1, nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ Total content of [ Nb ] ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ ]The upper limit of (b) is preferably 40%, and more preferably 35%, 30%, and 25% in this order. The lower limit of the total contentPreferably 5%, and more preferably 7%, 9%, and 11% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of embodiment 1-1, zrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ Total content of [ ZrO ] ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ ]The upper limit of (b) is preferably 50%, and more preferably 45%, 40%, and 37% in this order. The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, and 23% in this order. From the viewpoint of maintaining a high refractive index, the total content is preferably set to the above range.

In the optical glass of embodiment 1-1, zrO ₂ And Nb ₂ O ₅ Total content of [ ZrO ] ₂ +Nb ₂ O ₅ ]The upper limit of (b) is preferably 50%, and more preferably 45%, 40%, 37% in this order. The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, and 23% in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersion, it is preferable to make the total content be in the above range.

In the optical glass of embodiment 1-1, nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Total content of [ Nb ] ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ]The upper limit of (b) is preferably 40%, and more preferably 35%, 30%, and 25% in this order. The lower limit of the total content is preferably 5%, and more preferably 7%, 9%, and 11% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of embodiment 1-1, nb ₂ O ₅ Content of (2) and Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ Nb ] ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 1, and more preferably 0.95, 0.90 or 0.85. The lower limit of the mass ratio is preferably 0, and more preferably 0.50, 0.60, 0.70, and 0.80 in this order. The mass ratio may be 1. From the viewpoint of maintaining a high refractive index, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, ta ₂ O ₅ Content of (b) and Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of total content of [ Ta ] ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 1, and more preferably 0.5, 0.3, and 0.1 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.01, 0.03, and 0.05 in this order. The mass ratio may be 0. From the viewpoint of suppressing an increase in the raw material cost of the glass, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, tiO ₂ Content of (2) and Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ TiO ] ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 1, and more preferably 0.5, 0.3, and 0.1 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.01, 0.03, and 0.05 in this order. The mass ratio may be 0. From the viewpoint of maintaining a high refractive index, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, zrO ₂ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ ZrO ] ₂ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 0.8, and more preferably 0.7, 0.6, and 0.5 in this order. In the mass ratio ofThe lower limit is preferably 0.10, and more preferably 0.20, 0.25, and 0.30 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersion, it is preferable to set the mass ratio to the above range.

In the optical glass of embodiment 1-1, nb ₂ O ₅ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ Nb ] ₂ O ₅ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 0.95, and more preferably 0.9, 0.8, and 0.7 in this order. The lower limit of the mass ratio is preferably 0.1, and more preferably 0.2, 0.3, 0.4, and 0.5 in this order. The mass ratio may be 1. From the viewpoint of maintaining high dispersibility, it is preferable to set the mass ratio within the above range.

In the optical glass of the embodiment 1-1, ta ₂ O ₅ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ Ta ] ₂ O ₅ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, and 0.2 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. The mass ratio may be 0. From the viewpoint of suppressing an increase in the cost of raw materials, it is preferable to set the mass ratio within the above range.

In the optical glass of the embodiment 1-1, tiO ₂ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Mass ratio of the total content of [ TiO ] ₂ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, and 0.2 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. The mass ratio may beAnd is 0. From the viewpoint of maintaining high dispersibility, it is preferable to set the mass ratio within the above range.

In the optical glass of embodiment 1-1, the upper limit of the content of MgO is preferably 20%, and more preferably 15%, 10%, and 5% in this order. The lower limit of the content of MgO is preferably 0%. The MgO content may be 0%.

MgO is a component of the alkaline earth metal that increases the relative partial dispersion PC, t in the infrared wavelength region. However, when the content of MgO is increased, high dispersion properties are impaired, and thermal stability and devitrification resistance of the glass may be reduced. Therefore, the content of MgO is preferably in the above range.

In the optical glass of embodiment 1-1, the upper limit of the content of CaO is preferably 20%, and more preferably 15%, 10%, and 5% in this order. The lower limit of the CaO content is preferably 0%, and more preferably 3.0%, 4.0%, and 4.5% in this order. The content of CaO may be 0%.

CaO is a component of alkaline earth metals that increases the relative partial dispersion PC, t in the infrared wavelength region. However, when the content of CaO is increased, high dispersion properties are impaired, and thermal stability and devitrification resistance of the glass may be lowered. Therefore, the content of CaO is preferably in the above range.

In the optical glass of embodiment 1-1, the upper limit of the content of SrO is preferably 30%, and more preferably 20%, 10%, and 5% in this order. The lower limit of the SrO content is preferably 0%. The SrO content may be 0%.

SrO is a refractive index-increasing component of alkaline earth metals. However, when the content of SrO is increased, the high dispersion property is impaired, and the relative partial dispersion PC in the infrared wavelength region may decrease. Therefore, the SrO content is preferably in the above range.

In the optical glass of embodiment 1-1, the upper limit of the content of BaO is preferably 30%, and more preferably in the order of 25%, 20%, 15%, and 13%. The lower limit of the content of BaO is preferably 0%, and more preferably 5%, 8%, and 10% in this order. The content of BaO may be 0%.

BaO is a component for increasing the refractive index, and also a component for lowering the liquidus temperature and improving the thermal stability of the glass. However, if the content of BaO is too large, the high dispersion property is impaired, and the relative partial dispersion PC in the infrared wavelength region may decrease. When the content of BaO is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the content of BaO is preferably in the above range.

In the optical glass of embodiment 1-1, the upper limit of the content of ZnO is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3%, 2% in this order. The lower limit of the ZnO content is preferably 0%, and more preferably 0.5%, 0.8%, and 1% in this order. The content of ZnO may be 0%.

ZnO is a glass component having an effect of improving the thermal stability of the glass. However, if the content of ZnO is too large, the specific gravity may increase, and the relative partial dispersion PC in the infrared wavelength range may decrease. Therefore, the content of ZnO is preferably in the above range from the viewpoint of improving the thermal stability of the glass and maintaining desired optical constants.

In the optical glass of embodiment 1-1, the upper limit of the total content of MgO, caO, srO and BaO [ MgO + CaO + SrO + BaO ] is preferably 40%, and more preferably 35%, 30%, 25%, 20%, 15%, 12% in this order. The lower limit of the total content is preferably 0%, and more preferably 2%, 4%, 6%, 8%, and 10% in this order. The total content of MgO, caO, srO and BaO [ MgO + CaO + SrO + BaO ] may be 0%. When the total content is too large, the high dispersion property is impaired, and there is a risk that the relative partial dispersion PC, t in the infrared wavelength region is lowered. When the total content is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the total content is preferably in the above range.

In the optical glass of embodiment 1-1, the upper limit of the total content R' O [ MgO + CaO + SrO + BaO + ZnO ] of MgO, caO, srO, baO and ZnO is preferably 40%, and more preferably 35%, 30%, 25%, 20%, 15%, 12% in this order. The lower limit of the total content R' O is preferably 0%, and more preferably 2%, 4%, 6%, 8%, 10% in this order. R' O may be 0%. When R' O is too much, the high dispersion property is impaired, and there is a risk that relative partial dispersion PC, t in the infrared wavelength region is lowered. When R' O is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, R' O is preferably in the above range.

In the glass of embodiment 1-1, Y ₂ O ₃ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, 15%, 10%, and 5% in this order. In addition, Y ₂ O ₃ The lower limit of the content of (b) is preferably 0%, and more preferably 0.5%, 1.0%, and 1.5% in this order. Y is ₂ O ₃ The content of (B) may be 0%.

By introducing a certain amount of Y ₂ O ₃ The refractive index nd can be increased. However, Y ₂ O ₃ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass tends to be devitrified during production. In addition, there is a risk that the high dispersibility is impaired. Therefore, from the viewpoint of suppressing the decrease in thermal stability of the glass, Y is ₂ O ₃ The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, sc ₂ O ₃ The content of (b) is preferably 2% or less. In addition, sc ₂ O ₃ The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 1-1, hfO ₂ The content of (b) is preferably 2% or less. In addition, hfO ₂ The lower limit of the content of (b) is preferably 0%.

Sc ₂ O ₃ 、HfO ₂ Has the effect of improving the high dispersion of glass, but is an expensive component. Thus, sc ₂ O ₃ 、HfO ₂ The respective contents of (a) are preferably within the above ranges.

In the glass of embodiment 1-1, lu ₂ O ₃ The content of (b) is preferably 2% or less. In addition, lu ₂ O ₃ The lower limit of the content of (b) is preferably 0%.

Lu ₂ O ₃ Has the function of improving the high dispersion of glass, but has large molecular weightThis is also a glass component that increases the specific gravity of the glass. Thus, lu ₂ O ₃ The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, geO ₂ The content of (b) is preferably 2% or less. In addition, geO ₂ The lower limit of the content of (b) is preferably 0%.

GeO ₂ Has the effect of improving the high dispersion of glass, but is a very expensive component among commonly used glass components. Therefore, geO is considered from the viewpoint of reducing the production cost of glass ₂ The content of (b) is preferably in the above range.

In the optical glass of embodiment 1-1, la ₂ O ₃ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, 15%, 10%, and 5% in this order. In addition, la ₂ O ₃ The lower limit of the content of (b) is preferably 0%, and more preferably 0.5%, 1.0%, and 1.5% in this order. La ₂ O ₃ The content of (B) may be 0%. By introducing a certain amount of La ₂ O ₃ The refractive index nd can be increased. However, la ₂ O ₃ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass tends to be devitrified during production. In addition, there is a risk of deterioration of high dispersion, and there is a risk of lowering of relative partial dispersion PC, t in the infrared wavelength region. Thus, la ₂ O ₃ The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, gd ₂ O ₃ Preferably in an amount of 2% or less. In addition, gd ₂ O ₃ The lower limit of the content of (b) is preferably 0%.

Gd ₂ O ₃ When the content of (A) is too large, the thermal stability of the glass is lowered. In addition, gd ₂ O ₃ When the content (c) is too large, the specific gravity of the glass increases, which is not preferable. Moreover, there is a risk of an increase in raw material cost. Therefore, from the viewpoint of suppressing the increase in specific gravity while well maintaining the thermal stability of the glass, gd is used ₂ O ₃ The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, la ₂ O ₃ 、Gd ₂ O ₃ And Y ₂ O ₃ Total content of [ La ] ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ ]The upper limit of (b) is preferably 30%, and more preferably 25%, 20%, 15%, 10%, 5%, 3%, 1% in this order. The lower limit of the total content is preferably 0%. From the viewpoint of suppressing the decrease in thermal stability of the glass and the viewpoint of preventing the relative partial dispersion PC, t in the infrared wavelength region from decreasing, it is preferable to set the total content to the above range.

In the glass of embodiment 1-1, yb ₂ O ₃ The content of (b) is preferably 2% or less. In addition, yb ₂ O ₃ The lower limit of the content of (b) is preferably 0%.

And La ₂ O ₃ 、Gd ₂ O ₃ 、Y ₂ O ₃ In contrast, yb ₂ O ₃ Has a large molecular weight, and thus increases the specific gravity of the glass. In addition, yb ₂ O ₃ When the content of (A) is too large, the thermal stability of the glass is lowered. Yb from the viewpoint of preventing the thermal stability of the glass from lowering and suppressing the increase in specific gravity ₂ O ₃ The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ O and SiO ₂ And B ₂ O ₃ Mass ratio of the total content of [ R ] ₂ O/(SiO ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.50, and more preferably 0.45, 0.40, 0.35, 0.30 or 0.25. The lower limit of the mass ratio is preferably 0.05, and more preferably 0.07, 0.09, and 0.11 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, the total content of MgO, caO, srO and BaO is SiO ₂ And B ₂ O ₃ The mass ratio of the total content of [ (MgO + CaO + SrO + BaO)/(SiO) ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.50, and more preferably 0.40, 0.35, 0.30 or 0.25. The lower limit of the mass ratio is preferably 0, and more preferablyMore preferably 0.05, 0.10 and 0.15. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the mass ratio to the above range.

In the glass of embodiment 1-1, the total content R' O of MgO, caO, srO, baO and ZnO, and SiO ₂ And B ₂ O ₃ The mass ratio of the total content of [ R' O/(SiO) ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.50, and more preferably 0.40, 0.35, 0.30 and 0.25 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, la ₂ O ₃ 、Gd ₂ O ₃ And Y ₂ O ₃ Total content of (A) and SiO ₂ And B ₂ O ₃ The mass ratio of the total content of (A)/(La) ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ )/(SiO ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.50, and more preferably 0.40, 0.35, 0.30 or 0.25. The lower limit of the mass ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. The mass ratio may be 0. From the viewpoint of suppressing a decrease in thermal stability of the glass, it is preferable to set the mass ratio to the above range.

In the glass of embodiment 1-1, nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Total content of (A) and SiO ₂ And B ₂ O ₃ The mass ratio of the total content of [ (Nb) ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )/(SiO ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.70, and more preferably 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30 or 0.25. The lower limit of the mass ratio is preferably 0.05, and more preferably 0.10, 0.14, 0.16, 0.18, and 0.20 in this order. From the viewpoint of maintaining a high refractive index, it is preferable that the mass ratio is as described aboveAnd (3) a range.

In the glass of embodiment 1-1, the total content of MgO, caO, srO and BaO and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ The mass ratio of O [ (MgO + CaO + SrO + BaO)/R ₂ O]The upper limit of (b) is preferably 5, and more preferably 4.0, 3.0, 2.5, 2.0, 1.8 and 1.6. The lower limit of the mass ratio is preferably 0, and more preferably 0.20, 0.40, 0.60, 0.80, 1.00, 1.20, and 1.40 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and reducing the viscosity of the molten glass to improve the moldability, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, the total content R' O of MgO, caO, srO, baO and ZnO and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ Mass ratio of O [ R' O/R ₂ O]The upper limit of (b) is preferably 5, and more preferably 4.0, 3.0, 2.5, 2.0, 1.8 and 1.6. The lower limit of the mass ratio is preferably 0, and more preferably 0.20, 0.40, 0.60, 0.80, 1.00, 1.20, and 1.40 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and reducing the viscosity of the molten glass to improve the moldability, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, la ₂ O ₃ 、Gd ₂ O ₃ And Y ₂ O ₃ Total content of (2) and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ Mass ratio of O [ (La) ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ )/R ₂ O]The upper limit of (b) is preferably 3.0, and more preferably 2.0, 1.0, 0.8, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.01, 0.05, and 0.08 in this order. The mass ratio may be 0. From the viewpoint of suppressing the decrease in thermal stability of the glass, it is preferable to set the mass ratio within the above range.

In the glass of embodiment 1-1, nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Total content of (2) and Li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ Mass ratio of O [ (Nb) ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )/R ₂ O]The upper limit of (b) is preferably 5.0, and more preferably 4.0, 3.5, 3.0, 2.8, 2.6, 2.4, 2.2, 2.0 and 1.8 in this order. The lower limit of the mass ratio is preferably 0.3, and more preferably 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, and 1.7 in this order. From the viewpoint of maintaining a high refractive index, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the mass ratio within the above range.

In the glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ O and the total content R ₂ Mass ratio of total contents of O, mgO, caO, srO and BaO [ R ] ₂ O/(R ₂ O+MgO+CaO+SrO+BaO)]The upper limit of (b) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, and 0.45 in this order. The lower limit of the mass ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, and 0.35 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ The total content of O, mgO, and CaO and the total content R ₂ The mass ratio of O to the total of MgO, caO, srO, baO and ZnO contents R' O [ (R) ₂ O+MgO+CaO)/(R ₂ O+R’O)]The upper limit of (b) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, and 0.45 in this order. The lower limit of the mass ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, and 0.35 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the mass ratio in the above range.

In the glass of embodiment 1-1, la ₂ O ₃ 、Gd ₂ O ₃ And Y ₂ O ₃ Total content of (B) and Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ (La) ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ )/(Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ )]The upper limit of (b) is preferably 1, and more preferably 0.8, 0.6, 0.4, and 0.2 in this order. The lower limit of the mass ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. The mass ratio may be 0. From the viewpoint of suppressing a decrease in thermal stability of the glass and maintaining a high refractive index, it is preferable to set the mass ratio to the above range.

The glass of embodiment 1-1 is preferably composed mainly of the above-described glass components, i.e., siO as an essential component ₂ 、B ₂ O ₃ 、ZrO ₂ And Nb ₂ O ₅ P as an optional component ₂ O ₅ 、Al ₂ O ₃ 、Li ₂ O、Na ₂ O、K ₂ O、Cs ₂ O、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ 、Ta ₂ O ₅ 、MgO、CaO、SrO、BaO、ZnO、Y ₂ O ₃ 、Sc ₂ O ₃ 、HfO ₂ 、Lu ₂ O ₃ 、GeO ₂ 、La ₂ O ₃ 、Gd ₂ O ₃ And Yb ₂ O ₃ And (4) forming. The total content of the glass components is preferably 95% or more, more preferably 98% or more, still more preferably 99% or more, and particularly preferably 99.5% or more.

The glass of embodiment 1 to 1 is preferably substantially composed of the above glass components, but may contain other components within a range not impairing the action and effect of the present invention. In the present invention, the inclusion of unavoidable impurities is not excluded.

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

The additional amount is a value obtained by expressing the amount of the refining agent in weight percent, assuming that the total content of all glass components except the refining agent is 100%.

In addition, the above optical glass can obtain a high transmittance over a wide range of the visible light region. In order to fully utilize such characteristics, it is preferable that the coloring element is not included. Examples of the coloring element include Cu, co, ni, fe, cr, eu, nd, er, V, and Ag. All the elements are preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably substantially not contained.

Ga. Te, tb, etc. are components that do not need to be introduced, and are also expensive components. Therefore, ga in mass% ₂ O ₃ 、TeO ₂ 、TbO ₂ The content ranges of (b) are preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, still more preferably 0 to 0.005%, still more preferably 0 to 0.001%, and particularly preferably substantially none.

(glass characteristics)

[ Abbe number ν d ]

In the optical glass of embodiment 1-1, the abbe number ν d is preferably 30 to 60, and may be 35 to 55, 40 to 50, 41 to 48, 42 to 46, 43 to 45, or 32 to 50, 34 to 45, 36 to 40, 37 to 39.

The abbe number ν d can be set to a desired value by appropriately adjusting the content of each glass component. A component capable of relatively reducing Abbe number vd, that is, a high dispersion component Nb ₂ O ₅ 、TiO ₂ 、ZrO ₂ 、WO ₃ 、Bi ₂ O ₃ 、Ta ₂ O ₅ (represented by a cation as Nb) ⁵⁺ 、Ti ⁴⁺ 、Zr ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ 、Ta ⁵⁺ ) And the like. On the other hand, the low dispersion component, which is a component that relatively increases the abbe number ν d, is SiO ₂ 、B ₂ O ₃ 、Li ₂ O、Na ₂ O、K ₂ O、La ₂ O ₃ BaO, caO, srO (cation is Si) ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ 、La ³⁺ 、Ba ²⁺ 、Ca ²⁺ 、Sr ²⁺ ) And so on.

In the present invention, the abbe number ν d, relative partial dispersions PC, t and relative partial dispersions Pg, F, which will be described later, are calculated as follows. That is, a refractive index measurement method by Japanese Industrial Standard (JIS) B7071-1 optical glass-part 1: the refractive index at 12 wavelengths shown in Table A was measured by the minimum skew method. Next, the refractive index of each spectral line obtained by the measurement was substituted into the refractive index measurement method for optical glass according to JIS B7071-1, part 1: in the Schott dispersion equation defined in annex B of the least-squares method, the constants of the Schott dispersion equation are determined by the least-squares method. Then, using a Schott dispersion formula having a constant, abbe number ν d, relative partial dispersion PC, t and relative partial dispersion Pg, F described later are calculated from the obtained values of the refractive index of each spectral line.

[ Table A ]

Wavelength (nm)	Spectral line	Light source
			1013.98	t-ray (Infrared mercury)	Hg
852.11	s-ray (Infrared Cesium)	Cs
			706.52	Gamma ray (Red helium)	He
656.27	C ray (Red hydrogen)	H
			643.85	C' ray (Red cadmium)	Cd
587.56	d ray (yellow helium)	He
			546.07	e-ray (Green mercury)	Hg
486.13	F ray (blue hydrogen)	H
			479.99	F' ray (blue cadmium)	Cd
435.84	g-ray (blue mercury)	Hg
			404.66	h ray (purple mercury)	Hg
365.01	i-ray (ultraviolet mercury)	Hg

Schott dispersion formula: n is ² ＝a ₀ +a ₁ λ ² +a ₂ λ ^-2 +a ₃ λ ^-4 +a ₄ λ ^-6 +a ₅ λ ^-8

Wherein n is a refractive index, λ is a wavelength (μm), a ₀ 、a ₁ 、a ₂ 、a ₃ 、a ₄ 、a ₅ Is a constant.

The abbe number ν d is represented by using refractive indices nd, nF, and nC for d-ray, F-ray, and C-ray as follows.

νd＝(nd-1)/(nF-nC)

< refractive index nd >

In the optical glass of embodiment 1-1, the refractive index nd may be preferably 1.50 to 1.80, and may be 1.55 to 1.70, 1.58 to 1.65, 1.60 to 1.62, 1.60 to 1.70, 1.63 to 1.69, or 1.66 to 1.68.

The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The component having the effect of relatively increasing the refractive index nd (high refractive index component) is Nb ₂ O ₅ 、TiO ₂ 、ZrO ₂ 、Ta ₂ O ₅ 、La ₂ O ₃ (represented by a cation as Nb) ⁵⁺ 、Ti ⁴⁺ 、Zr ⁴⁺ 、Ta ⁵⁺ 、La ³⁺ ) And the like. On the other hand, the component having the effect of relatively lowering the refractive index nd (low refractive index lowering component) is SiO ₂ 、B ₂ O ₃ 、Li ₂ O、Na ₂ O、K ₂ O (represented by cation as Si) ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ ) And so on.

< relative partial dispersion PC, t >

In the optical glass of the embodiment 1 to 1, the lower limit of the relative partial dispersion PC, t in the infrared wavelength region is preferably 0.7300, and is further more preferably in the order of 0.7400, 0.7500, 0.7600, 0.7700, 0.7750, 0.7800, 0.7850, 0.7860, 0.7870, 0.7880, 0.7890, 0.7900, 0.7910, 0.7920, 0.7930, 0.7940, 0.7950. By making the relative partial dispersion PC, t the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of t for the partial dispersion PC is not particularly limited, but is usually 0.9000, preferably 0.8700, and more preferably 0.8500 and 0.8400 in this order.

In the optical glass of embodiment 1-1, t preferably satisfies the following formula [1] with respect to the partial dispersion PC.

PC,t≥0.5711+0.004667×νd···[1]

It is more preferable that F satisfies the following formula [2] with respect to the partial dispersion Pg, and it is further more preferable that F satisfies the following formula [3], the following formula [4], the following formula [5], the following formula [6], and the following formula [7] in this order.

PC,t≥0.5731+0.004667×νd···[2]

PC,t≥0.5751+0.004667×νd···[3]

PC,t≥0.5771+0.004667×νd···[4]

PC,t≥0.5791+0.004667×νd···[5]

PC,t≥0.5811+0.004667×νd···[6]

PC,t≥0.5831+0.004667×νd···[7]

By making the relative partial dispersions PC, t satisfy the above expression, the optical element made of the optical glass of embodiment 1-1 can compensate chromatic aberration well over a wide wavelength range.

In the optical glass of embodiment 1-1, the lower limit of the deviation Δ PC, t is preferably 0.0250, and more preferably 0.0270, 0.0290, 0.0310, 0.0330, 0.0350, and 0.0370 in this order. By setting the deviation Δ PC, t in the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of the deviation Δ PC, t is not particularly limited, but is usually 0.0900, preferably 0.0800.

The relative partial dispersion PC, t is calculated using the Schott dispersion equation described above.

The relative partial dispersion PC, t is expressed by the following refractive indices nt, nF, nC for t-ray, F-ray, and C-ray.

PC,t＝(nC-nt)/(nF-nC)

In a plane in which the abbe number ν d is represented by the horizontal axis and the relative partial dispersion PC, t is represented by the vertical axis, the normal line is represented by the following equation.

PC,t(0)＝0.5461-(0.004667×νd)

Further, the deviation Δ PC, t of the relative partial dispersion PC, t from the normal line is expressed as follows.

ΔPC,t＝PC,t-PC,t(0)

The relative partial dispersion PC, t can be set to a desired value by appropriately adjusting the content of each glass component. The component having the effect of relatively increasing the relative partial dispersion PC, t is SiO ₂ 、B ₂ O ₃ 、Al ₂ O ₃ 、Li ₂ O (represented by cation as Si) ⁴⁺ 、B ³⁺ 、Al ³⁺ 、Li ⁺ ) And the like. On the other hand, the components having the effect of relatively reducing the relative partial dispersion PC, t are SrO, baO, znO and La ₂ O ₃ 、TiO ₂ 、Nb ₂ O ₅ 、WO ₃ (represented by cation as Sr ²⁺ 、Ba ²⁺ 、Zn ²⁺ 、La ³⁺ 、Ti ⁴⁺ 、Nb ⁵⁺ 、W ⁶⁺ ) And the like. In the present embodiment, in particular by<1>Contains a large amount of SiO as a component for increasing PC, t ₂ And B ₂ O ₃ (represented by cations as Si) ⁴⁺ And B ³⁺ ) At the same time, the utility model can simultaneously,<2>SiO is appropriately mixed ₂ (Si ⁴⁺ ) Is replaced by B ₂ O ₃ (B ³⁺ ) High dispersion is achieved without a large reduction in PC, t,<3>for the purpose of further improving the moldability by increasing the dispersion and lowering the viscosity, an alkali metal oxide and an alkaline earth metal oxide are appropriately introduced,<4>the amount of a high-dispersion component which is required for obtaining a desired Abbe number and which also reduces the PC, t component is minimized, thereby positively introducing Nb which can relatively reduce the reduction of PC, t among the high-dispersion components ₂ O ₅ (Nb ⁵⁺ ) And the reduction of PC, t and the chemical durability of the glass can be simultaneously realizedZrO of nature ₂ (Zr ⁴⁺ ) Thereby obtaining the optical glass with small Abbe number vd and higher relative partial dispersion PC, t.

< relative partial dispersion Pg, F >

In the optical glass of embodiment 1-1, the relative partial dispersion Pg in the visible short-wavelength region, the upper limit of F is preferably 0.5800, and more preferably 0.5750, 0.5720, 0.5690, 0.5660, 0.5640, 0.5630, 0.5620, 0.5610, and 0.5600 in this order. By making the relative partial dispersions Pg, F in the above ranges, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the lower limit of F relative to the partial dispersion Pg is not particularly limited, but is usually 0.5500, and preferably 0.5550.

In the optical glass of embodiment 1-1, it is preferable that the relative partial dispersion Pg, F satisfies the following formula [8].

Pg,F≤0.6483-0.001802×νd···[8]

It is more preferable that F satisfies the following formula [9] with respect to the partial dispersion Pg, and it is further more preferable that F satisfies the following formula [10], the following formula [11], the following formula [12], the following formula [13], and the following formula [14] in this order.

Pg,F≤0.6470-0.001802×νd···[9]

Pg,F≤0.6460-0.001802×νd···[10]

Pg,F≤0.6450-0.001802×νd···[11]

Pg,F≤0.6444-0.001802×νd···[12]

Pg,F≤0.6439-0.001802×νd···[13]

Pg,F≤0.6433-0.001802×νd···[14]

By making the relative partial dispersions Pg, F satisfy the above formula, the optical element made of the optical glass of embodiment 1-1 can compensate for chromatic aberration well in a wide wavelength range.

In the optical glass of embodiment 1-1, the lower limit of the deviation Δ Pg, F is preferably 0, and more preferably-0.0013, -0.0023, -0.0033, -0.0039, -0.0044, and-0.0050 in this order. By setting the deviations Δ Pg, F to the above ranges, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of the deviation Δ Pg, F is not particularly limited, but is usually-0.0300, preferably-0.0250.

The relative partial dispersion Pg, F was calculated using the Schott dispersion equation described above.

The refractive indices ng, nF, nC of the partial dispersion Pg and F in g-ray, F-ray, and C-ray are expressed as follows.

Pg,F＝(ng-nF)/(nF-nC)

In a plane in which the abbe number ν d is represented by the horizontal axis and the relative partial dispersion Pg, F is represented by the vertical axis, the normal line is represented by the following equation.

Pg,F(0)＝0.6483-(0.001802×νd)

The relative partial dispersion Pg against the normal line, the deviation Δ Pg, F of F is expressed as follows.

ΔPg,F＝Pg,F-Pg,F(0)

Specific gravity of glass

The specific gravity of the optical glass of embodiment 1 to 1 is preferably 4.00 or less, more preferably 3.50 or less, and further preferably 3.10 or less.

The components which can relatively increase the specific gravity are BaO and La ₂ O ₃ 、ZrO ₂ 、Nb ₂ O ₅ 、Ta ₂ O ₅ (cation is Ba ²⁺ 、La ³⁺ 、Zr ⁴⁺ 、Nb ⁵⁺ 、Ta ⁵⁺ ) And the like. On the other hand, the component which relatively lowers the specific gravity is SiO ₂ 、B ₂ O ₃ 、Li ₂ O、Na ₂ O、K ₂ O (represented by cation as Si) ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ ) And the like. By appropriately adjusting the contents of these components, the specific gravity can be controlled.

< liquid phase temperature LT >

The upper limit of the liquidus temperature LT of the optical glass of embodiment 1-1 is preferably 1300 ℃, and more preferably 1270 ℃, 1240 ℃, 1210 ℃, 1180 ℃, 1150 ℃ and 1100 ℃. By setting the liquidus temperature in the above range, the melting and forming temperatures of the glass can be lowered, and as a result, erosion by glass melting equipment (for example, a crucible, a stirrer for molten glass, etc.) in the melting step and erosion by the glass melting equipment can be reducedThe generation of striae due to the volatilization of the glass component itself. The lower limit of the liquidus temperature LT is not particularly limited, but is usually 1000 ℃ and preferably 1050 ℃. The liquidus temperature LT is determined by the balance of the contents of all glass components. Wherein, siO ₂ 、B ₂ O ₃ 、Li ₂ O、Na ₂ O、K ₂ O (represented by cation as Si) ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ ) Etc. have a large influence on the liquidus temperature LT. In addition, zrO ₂ 、Al ₂ O ₃ (cation is Zr) ⁴⁺ 、Al ³⁺ ) When the content of the component (B) is large, the liquid phase temperature rises.

The liquidus temperature is determined as follows. 10cc (10 ml) of glass was put into a platinum crucible, melted at 1250 to 1400 ℃ for 15 to 30 minutes, cooled to a glass transition temperature Tg or lower, and then placed in a melting furnace at a predetermined temperature together with the platinum crucible and held for 2 hours. The holding temperature was set to 5 ℃ or 10 ℃ at 1000 ℃ or higher, and after holding for 2 hours, the glass was cooled, and the presence or absence of crystals inside the glass was observed by an optical microscope at 100 magnifications. The lowest temperature at which crystals did not precipitate was taken as the liquidus temperature.

< glass transition temperature Tg >

The lower limit of the glass transition temperature Tg of the optical glass of embodiment 1-1 is preferably 400 ℃, and more preferably 450 ℃, 470 ℃ and 490 ℃. The upper limit of the glass transition temperature Tg is preferably 600 ℃ and more preferably 580 ℃, 560 ℃ and 550 ℃.

The component relatively lowering the glass transition temperature Tg is Li ₂ O、Na ₂ O、K ₂ O (represented by Li as cation) ⁺ 、Na ⁺ 、K ⁺ ) And the like. The component which relatively increases the glass transition temperature Tg is La ₂ O ₃ 、ZrO ₂ 、Nb ₂ O ₅ (cation is La) ³⁺ 、Zr ⁴⁺ 、Nb ⁵⁺ ) And so on. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< light transmittance of glass >

The optical glass of embodiment 1-1 can be evaluated for light transmittance based on the coloring degrees λ 80 and λ 5.

The spectral transmittance of a glass sample having a thickness of 10.0 mm. + -. 0.1mm was measured at a wavelength of 200 to 700nm, and λ 80 was defined as the wavelength at which the external transmittance reached 80%, and λ 5 was defined as the wavelength at which the external transmittance reached 5%.

The λ 80 of the optical glass of embodiment 1-1 is preferably 450nm or less, more preferably 430nm or less, and still more preferably 410nm or less. λ 5 is preferably 400nm or less, more preferably 380nm or less, and further preferably 360nm or less.

< chemical durability Water resistance Dw >

In the optical glass of embodiment 1-1, the water resistance Dw is preferably grade 5 or more, more preferably grade 4 or more, and still more preferably grade 3 or more.

Powder glass (particle size 425 to 600 μm) having a mass corresponding to the specific gravity was placed in a platinum cage, immersed in a 80mL round-bottomed flask made of quartz glass containing pure water (pH =6.5 to 7.5), treated in a boiling water bath for 60 minutes, classified according to the mass reduction rate (%) in the scale of table B, and evaluated for water resistance Dw.

[ Table B ]

Grade	Mass loss (%)
		1	Less than 0.05 percent
2	More than 0.05 percent and less than 0.10 percent
		3	0.10％Above and less than 0.25%
4	More than 0.25 percent and less than 0.60 percent
		5	More than 0.60 percent and less than 1.10 percent
6	More than 1.10 percent

< chemical durability acid resistance Da >

In the optical glass of embodiment 1-1, the acid resistance Da is preferably 5 or more, more preferably 4 or more, and further preferably 3 or more.

Powdery glass (particle size: 425 to 600 μm) having a mass corresponding to the specific gravity was placed in a platinum cage, and the resultant was immersed in a quartz glass round-bottomed flask containing 80mL of a 0.01mol/L nitric acid aqueous solution, treated for 60 minutes, and classified according to the degree of mass reduction (%) in Table C to evaluate the acid resistance Da.

[ Table C ]

Grade of	Mass loss (%)
		1	Less than 0.20 percent
2	More than 0.20 percent and less than 0.35 percent
		3	More than 0.35 percent and less than 0.65 percent
4	More than 0.65% and less than 1.20%
		5	More than 1.20 percent and less than 2.20 percent
6	2.20% or more

< chemical durability scratch resistance D _NaOH ＞

In the optical glass of embodiment 1-1, the scratch resistance D _NaOH Preferably 4 or more, more preferably 3 or more, and still more preferably 2 or more.

The diameter of the tube is 43.7mm (both sides are 30 cm) ² ) The glass sample having a thickness of about 5mm and polished on the opposite side was immersed in a sufficiently stirred aqueous NaOH solution at 50 ℃ and 0.01mol/L for 15 hours, and at this time, the mass per unit area was decreased by [ mg/(cm) ² ·15h)]Classification according to the grade of Table D, and resistance to scratch D _NaOH Evaluation was carried out.

[ Table D ]

Grade	Mass reduction [ mg/(cm) ² ·15h)]
		1	Less than 0.02
2	0.02 or more and less than 0.10
		3	0.10 or more and less than 0.20
4	0.20 or more and less than 0.30
		5	0.30 or more

< chemical durability scratch resistance D _STPP ＞

In the optical glass of embodiment 1-1, the scratch resistance D _STPP Preferably 4 or more, more preferably 3 or more, and still more preferably 2 or more.

The diameter of the sample is 43.7mm (both sides are 30 cm) ² ) The glass sample having a thickness of about 5mm and polished on the opposite side was subjected to a sufficient stirring at 50 ℃ with 0.01mol/L Na ₅ P ₃ O ₁₀ (STPP) was immersed in the aqueous solution for 1 hour, at which time the mass per unit area decreased by [ mg/(cm) ² ·h)]Classification according to the grade of Table E, and resistance to scratch D _STPP Evaluation was carried out.

[ Table E ]

Grade of	Mass loss [ mg/(cm) ² ·h)]
		1	Less than 0.02
2	0.02 or more and less than 0.20
		3	0.20 or more and less than 0.40
4	0.40 or more and less than 0.60
		5	0.60 or more

< chemical durability D ₀ ＞

Chemical durability D in the optical glass of embodiment 1-1 ₀ Preferably, the number of stages is 4 or more, more preferably 3 or more, and further preferably 2 or more.

The diameter of the sample is 43.7mm (both sides are 30 cm) ² ) When a glass sample having a size of about 5mm in thickness and polished on the opposite side was immersed in sufficiently stirred pure water maintained at 50 ℃ and pH =7.0 ± 0.2 by passing and circulating through an ion exchange resin layer at a rate of 1L per minute, the mass reduction per unit area was [10] ^-3 mg/(cm ² ·h)]Chemical durability D was classified according to the grade of Table F ₀ Evaluation was carried out.

[ Table F ]

Grade	Mass reduction [10] ^-3 mg/(cm ² ·h)]
		1	Less than 0.4
2	0.4 or more and less than 5.0
		3	5.0 or more and less than 10.0
4	10.0 or more and less than 15.0
		5	15.0 or more

(production of optical glass)

The glass of embodiment 1 to 1 may be produced by a known glass production method using a glass raw material prepared so as to have the above-described predetermined composition. For example, a plurality of compounds are prepared and mixed well to prepare a batch of raw materials, and the batch of raw materials is put into a quartz crucible or a platinum crucible to be roughly melted (rough melt). The melt obtained by the coarse melting is quenched and pulverized to produce cullet. Further, the cullet was placed in a platinum crucible and heated and remelted (remelt) to prepare molten glass, and after further clarification and homogenization, the molten glass was molded and slowly cooled to obtain optical glass. The molten glass may be formed and slowly cooled by a known method.

The compound used in preparing the batch materials is not particularly limited as long as a desired glass component can be introduced into the glass to have a desired content, and examples of such a compound include oxides, carbonates, nitrates, hydroxides, fluorides, and the like.

(production of optical element, etc.)

When the optical glass of embodiment 1-1 is used to produce an optical element, a known method may be used. For example, in the production of the above optical glass, a molten glass is poured into a mold and molded into a plate shape to produce a glass material comprising the optical glass of the present invention. The obtained glass material is appropriately cut, ground, polished, and made into pieces having a size and a shape suitable for press molding. The chips are heated and softened, and press-formed (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, and then ground and polished by a known method to produce an optical element.

Depending on the purpose of use, the optically functional surface of the optical element to be produced may be coated with an antireflection film, a total reflection film, or the like.

According to one embodiment of the present invention, there is provided an optical element made of the above optical glass. Examples of the optical element include a lens such as a spherical lens or an aspherical lens, a prism, and a diffraction grating. 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. The optical element can be produced by a method including a step of processing a glass molded body made of the above optical glass. As the machining, cutting, rough grinding, finish grinding, polishing, and the like can be exemplified. When such processing is performed, the use of the glass can reduce breakage and can stably supply high-quality optical elements.

1 st to 2 nd embodiments

In the optical glass of the embodiments 1-2,

as a component of the glass, a glass,

containing SiO ₂ 、B ₂ O ₃ 、ZrO ₂ And Nb ₂ O ₅ ，

the optical glass has a Δ PC, t of 0.0250 or more.

The optical glass of embodiment 1-2 contains SiO ₂ As a glass component. SiO 2 ₂ The lower limit of the content of (b) is preferably 20%, and more preferably 24%, 26%, and 28% in this order. In addition, siO ₂ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, and 35% in this order. SiO 2 ₂ Is a network forming component of the glass. By containing SiO ₂ As the glass component, the relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving chemical durability. From the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region and suppressing the decrease in thermal stability and chemical durability of the glass, siO ₂ The lower limit of the content of (b) is preferably set as described above. From the viewpoints of suppressing a decrease in the melting property of glass and preventing an increase in the viscosity of molten glass to deteriorate the moldability ₂ The upper limit of the content of (b) is preferably set as described above.

The optical glass of embodiment 1-2 contains B ₂ O ₃ As a glass component. B is ₂ O ₃ The lower limit of the content of (b) is preferably 15%, and more preferably 17%, 19%, and 21% in this order. In addition, B ₂ O ₃ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, and 35% in this order. B is ₂ O ₃ Is a network forming component of the glass. By containing B ₂ O ₃ As the glass component, the relative partial dispersion PC, t in the infrared wavelength region can be increased. From the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region and suppressing the decrease in thermal stability of the glass, B ₂ O ₃ The lower limit of the content of (b) is preferably set as described above. From the viewpoint of suppressing the decrease in chemical durability of the glass, B ₂ O ₃ The upper limit of the content of (b) is preferably set as described above.

The optical glass of the 1 st to 2 nd embodiments contains ZrO ₂ As a glass component. ZrO (ZrO) ₂ The lower limit of the content of (b) is preferably 5.0%, and more preferably 6.5%, 8.0%, and 9.5% in this order. In addition, zrO ₂ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, and 15% in this order. By containing ZrO ₂ As a glass component, the infrared ray can be improvedThe relative partial dispersion of the wavelength region PC, t improves chemical durability. From the viewpoint of suppressing the decrease in chemical durability, zrO ₂ The lower limit of the content of (b) is preferably set as described above. From the viewpoint of suppressing an increase in the liquidus temperature LT and suppressing a decrease in the stability during reheating, zrO ₂ The upper limit of the content of (b) is preferably set as described above.

The optical glass of embodiment 1-2 contains Nb ₂ O ₅ As a glass component. Nb ₂ O ₅ The content of (b) is preferably more than 5.0%, and the lower limit thereof is more preferably 6.5%, 8.0%, and 9.5% in this order. In addition, nb ₂ O ₅ The upper limit of the content of (b) is preferably 30%, and more preferably 25%, 20%, and 15% in this order. By containing Nb ₂ O ₅ As the glass component, it is possible to maintain high dispersion property while suppressing a decrease in relative partial dispersion PC, t in the infrared wavelength region. Nb from the viewpoint of maintaining high dispersibility ₂ O ₅ The lower limit of the content of (b) is preferably set as described above. Nb from the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region ₂ O ₅ The lower limit of the content of (b) is preferably set as described above.

The optical glass of the 1 st to 2 nd embodiments contains Li ₂ O、Na ₂ O and K ₂ At least one of O and O is used as a glass component. Preferably contains Na ₂ O, may contain Li ₂ O and Na ₂ O, may contain Na ₂ O and K ₂ O, may contain Li ₂ O and K ₂ O, may also contain Li ₂ O、Na ₂ O and K ₂ And O. By containing elements selected from Li ₂ O、Na ₂ O and K ₂ More than one of O as a glass component can increase the relative partial dispersion PC, t in the infrared wavelength region, thereby improving the chemical durability.

In the optical glass of embodiment 1-2, li ₂ O、Na ₂ O and K ₂ Total content R of O ₂ SiO and the total of O, mgO, caO, srO, baO and ZnO contents R' O ₂ And B ₂ O ₃ (ii) the mass ratio of the total content of [ (R) ₂ O+R’O)/(SiO ₂ +B ₂ O ₃ )]The upper limit of (b) is preferably 0.36, and more preferably 0.35, 0.34, and 0.33 in this order. The lower limit of the mass ratio is preferably 0.05, and more preferably 0.10, 0.15, and 0.20 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the mass ratio in the above range.

In the optical glass of embodiment 1-2, B ₂ O ₃ With ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ B ] ₂ O ₃ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]The lower limit of (b) is preferably 0.74, and more preferably 0.84, 0.94 and 1.04 in this order. The upper limit of the mass ratio is preferably 3.0, and more preferably 2.5, 2.0, and 1.5 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the mass ratio to the above range.

In the optical glass of the embodiment 1-2, zrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ And Ta ₂ O ₅ Total content of [ ZrO ] ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ]The lower limit of (b) is preferably 22%, and more preferably 22.5%, 23.0%, and 23.5% in this order. The upper limit of the total content is preferably 40%, and more preferably 35%, 30%, and 25% in this order. From the viewpoint of increasing the refractive index nd and setting the abbe number ν d to a desired range, it is preferable to set the total content to the above range.

The optical glass of embodiment 1-2 preferably does not substantially contain Pb, which is a component having an environmental burden. That is, the content of Pb is preferably 0% in terms of oxide. As and Th are also components having a potential for environmental burden, similarly to Pb. Therefore, the content of each of As and Th is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01% in terms of oxide. The respective contents of As and Th are preferably 0% in terms of oxide. That is, it is preferable that substantially none of As and Th is contained.

In the optical glass of embodiment 1-2, the content, ratio, and the like of the glass components other than those described above may be the same as those of embodiment 1-1.

In the optical glass of embodiment 1-2, the deviation Δ PC, t is 0.0250 or more. The lower limit of the deviation Δ PC, t is preferably 0.0270, and more preferably 0.0290, 0.0310, 0.0330, 0.0350, and 0.0370. By setting the deviation Δ PC, t in the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of the deviation Δ PC, t is not particularly limited, but is usually 0.0900, preferably 0.0800. The method of calculating the deviation Δ PC, t is as described in embodiment 1-1.

In the optical glass of embodiment 1-2, glass characteristics other than those described above may be the same as those of embodiment 1-1.

The optical glass and the optical element according to embodiments 1 to 2 may be manufactured in the same manner as in embodiment 1 to 1.

Embodiment 2

In embodiment 2 (embodiment 2-1 and embodiment 2-2), the glass composition of the optical glass is expressed in terms of cation% unless otherwise specified. Cation% means a molar percentage in which the total content of all the cation components is 100%. In embodiment 2 (embodiment 2-1 and embodiment 2-2), the content and total content of the glass component are based on% cations, and "%" means "% cations", unless otherwise specified. In the present specification and the present invention, the content of 0% of a constituent component means that the constituent component is not substantially contained, it is permissible to contain the component at a level of unavoidable impurities.

The anion% refers to a molar percentage in which the total content of all anion components is 100%.

Valence of cationic component (e.g. B) ³⁺ Has a valence of +3,Si ⁴⁺ Has a valence of +4,La ³⁺ Valence number is +3) Is a value determined conventionally when B, si and La are expressed on an oxide basis as glass components and expressed as B ₂ O ₃ 、SiO ₂ 、La ₂ O ₃ The same is true. Therefore, when analyzing the glass composition, the valence number of the cation component may not be analyzed. In addition, the valence number (e.g., O) of the anionic component ^2- Valence number of-2) is also a value determined conventionally, as described above, of a glass component expressed on an oxide basis with, for example, the formula B ₂ O ₃ 、SiO ₂ 、La ₂ O ₃ The same is true. Therefore, when analyzing the glass composition, the valence number of the anion component may not be analyzed.

2 nd embodiment mode

In embodiment 2-1, the glass composition is designed based on the criteria shown below. That is to say that the first and second electrodes,<1>in a large amount of Si containing a component for increasing the relative partial dispersion PC, t in the infrared wavelength region ⁴⁺ And B ³⁺ At the same time, the utility model can simultaneously,<2>appropriately mixing Si ⁴⁺ Is partially replaced by B ³⁺ High dispersion is achieved without a large reduction in PC, t,<3>for the purpose of further improving moldability by increasing the dispersion and lowering the viscosity, an alkali metal oxide and an alkaline earth metal oxide are appropriately introduced,<4>the amount of the high-dispersion component which is required for obtaining a desired Abbe number and also reduces the PC, t is minimized, and thus Nb which can relatively reduce the PC, t among the high-dispersion components is positively introduced ⁵⁺ And Zr capable of simultaneously achieving suppression of reduction in PC, t and chemical durability of glass ⁴⁺ Thus, the optical glass with small Abbe number vd and high relative partial dispersion PC, t of an infrared wavelength region is completed. The optical glass of the embodiment 2-1 is as follows.

In the optical glass of embodiment 2-1,

Si ⁴⁺ the content of (A) is more than 10%,

B ³⁺ the content of (A) is more than 20%,

Si ⁴⁺ and B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]Is 50 percentIn the above-mentioned manner,

B ³⁺ with Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is a content of at least 0.44,

Nb ⁵⁺ the content of (B) is more than 0% and 11.5% or less,

the optical glass satisfies one or more of the following (i) and (ii).

(i)Zr ⁴⁺ The content of (D) and the total content of R' and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]Is 0.17 or more.

(ii)Zr ⁴⁺ And Ta ⁵⁺ To the above total content R' and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]Is 0.25 or more.

In the optical glass of the embodiment 2-1, si ⁴⁺ The content of (A) is more than 10%. Si ⁴⁺ The lower limit of the content of (b) is preferably 12%, and more preferably 14%, 16%, 18%, 20%, 22%, 23%, and 24% in this order. In addition, si ⁴⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 43%, 40%, 38%, 36%, 34%, 32%, and 30% in this order. Si ⁴⁺ Is a network forming component of the glass. By reacting Si ⁴⁺ The content of (b) is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving the chemical durability. Si ⁴⁺ When the content of (b) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability and chemical durability of the glass may be lowered. Si ⁴⁺ When the content of (b) is too large, there is a possibility that the meltability of the glass is lowered, and the viscosity of the molten glass is increased to deteriorate the moldability.

In the optical glass of embodiment 2-1, B ³⁺ The content of (A) is 20% or more. B ³⁺ The lower limit of the content of (b) is preferably 25%, and more preferably 28%, 29%, 30%, 31%, 32% in this order. In addition, B ³⁺ The upper limit of the content of (b) is preferably 60%, and more preferably 55%, 50%, 48%, 46%, 44% in this order. B is ³⁺ Is a network forming component of the glass. By making B ³⁺ The content of (b) is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be improved. B ³⁺ When the content of (b) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability of the glass may be lowered. B is ³⁺ If the content of (b) is too large, the chemical durability of the glass may be deteriorated.

In the optical glass of embodiment 2-1, si ⁴⁺ And B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]Is more than 50%. The lower limit of the total content is preferably 52%, and more preferably 54%, 56%, and 57% in this order. The upper limit of the total content is preferably 80%, and more preferably 78%, 76%, 74%, 72%, and 71%, in this order. By setting the total content to the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, and the thermal stability of the glass can be maintained. When the total content is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and there is a possibility that the thermal stability and chemical durability of the glass cannot be maintained. If the total content is too large, the viscosity of the molten glass may increase, and the moldability may deteriorate. In addition, there is a risk of lowering the refractive index.

In the optical glass of embodiment 2-1, B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is 0.44 the above. The lower limit of the cation ratio is preferably 0.47, and more preferably 0.50, 0.53, and 0.56 in this order. In addition, the upper limit of the cation ratio is preferably 0.80, further oneMore preferably, the steps are performed in the order of 0.75, 0.71, 0.67, 0.63, and 0.61. By setting the cation ratio to the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. If the cation ratio is too large, the chemical durability of the glass may be reduced.

In the optical glass of the embodiment 2-1, li ⁺ 、Na ⁺ And K ⁺ With the total content R and Mg ²⁺ 、Ca ² ⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (B) is [ R/(R + R')]Is 0.55 or more. The lower limit of the cation ratio is preferably 0.60, and more preferably 0.65, 0.70, and 0.75 in this order. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.95, 0.90, and 0.85 in this order. When the cation ratio is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, the meltability of the glass can be improved, and the viscosity of the molten glass can be reduced to improve the moldability. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

In this specification, li is sometimes used ⁺ 、Na ⁺ And K ⁺ Is referred to as R, and Mg is sometimes referred to as ²⁺ 、Ca ² ⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (A) is referred to as R'.

In the optical glass of embodiment 2-1, nb ⁵⁺ The content of (b) is more than 0% and 11.5% or less. Nb ⁵⁺ The lower limit of the content of (b) is preferably 2.0%, and more preferably 3.0%, 3.5%, 4.0%, 4.5%, and 5.0% in this order. In addition, nb ⁵⁺ The upper limit of the content of (b) is preferably 10%, and more preferably 9.5%, 9.0%, 8.5%, 8.0%, 7.5%, 7.0%, 6.5%, 6.0% in this order. By making Nb ⁵⁺ The content of (b) is in the above range, it is possible to maintain high dispersion property while suppressing the decrease of relative partial dispersion PC, t in the infrared wavelength region. Nb ⁵⁺ In a content ofWhen too small, there is a possibility that the high dispersibility cannot be maintained. Nb ⁵ ⁺ If the content of (b) is too large, there is a risk of lowering the relative partial dispersion PC, t in the infrared wavelength region.

The optical glass of embodiment 2-1 satisfies one or more of the following (i) and (ii).

(i) In the 2 nd to 1 st embodiment in the optical glass of (1), in the case of, zr ⁴⁺ With Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]The lower limit of (b) is preferably 0.17, and more preferably 0.20, 0.25, 0.30, 0.35, 0.37, 0.39, 0.40 in this order. The upper limit of the cation ratio is preferably 2.00, and more preferably 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, and 0.60 in this order. From the viewpoint of improving chemical durability, increasing refractive index nd, and maintaining high dispersion properties, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. If the cation ratio is too large, the liquid phase temperature LT may increase, and the stability during reheating may decrease.

(ii) In the optical glass of embodiment 2-1, zr ⁴⁺ And Ta ⁵⁺ Total content of (A) and Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]The lower limit of (b) is preferably 0.25, and more preferably 0.30, 0.35, 0.37, 0.39, and 0.40 in this order. The upper limit of the cation ratio is preferably 3.10, and more preferably 2.80, 2.60, 2.40, 2.20, 2.00, 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, and 0.60 in this order. From the increase of the relative partial dispersion PC in the infrared wavelength region,t, the cation ratio is preferably in the above range from the viewpoint of improving the refractive index nd, maintaining high dispersion properties, and maintaining chemical durability of the glass. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. When the cation ratio is too large, there is a risk that the thermal stability of the glass is lowered.

Hereinafter, preferred contents of glass components in the optical glass of embodiment 2-1 will be described.

In the optical glass of embodiment 2-1, zr ⁴⁺ And Ta ⁵⁺ Total content of [ Zr ] ⁴⁺ +Ta ⁵⁺ ]The upper limit of (b) is preferably 8.5%, and more preferably 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, and 5.5% in this order. The lower limit of the total content is preferably 1.0%, and more preferably 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, and 4.5% in this order. From the viewpoint of maintaining the thermal stability of the glass, it is preferable to set the total content to the above range. When the total content is too small, the chemical durability of the glass may be deteriorated. When the total content is too large, there is a risk of lowering the thermal stability of the glass and a risk of increasing the cost of the raw material.

In the optical glass of embodiment 2-1, zr ⁴⁺ The lower limit of the content of (b) is preferably 1.0%, and more preferably 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% in this order. In addition, zr ⁴⁺ The upper limit of the content of (b) is preferably 8.5%, and more preferably 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, and 5.5% in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to use Zr ⁴⁺ The content of (B) is in the above range. Zr ⁴⁺ When the content of (b) is too small, there is a possibility that chemical durability is lowered. Zr ⁴⁺ If the content (b) is too large, there is a possibility that the liquid phase temperature LT increases and the stability during reheating decreases.

In the optical glass of embodiment 2-1, li ⁺ 、Na ⁺ And K ⁺ Total content of R and Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of (3) R' in total with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (R + R')/(Si) ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 1.00, and more preferably 0.90, 0.80, 0.70, 0.60, and 0.50 in this order. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, and 0.24 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 2-1, B ³⁺ Content of (2) and Zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of the total content [ B ] ³⁺ /(Zr ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 7.0, and more preferably 6.0, 5.5, 5.0, 4.5, and 4.0. The lower limit of the cation ratio is preferably 1.0, and more preferably 1.2, 1.4, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, and 2.2 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 2-1, zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Total content of [ Zr ] ⁴⁺ +Nb ⁵⁺ +Ti ⁴ ⁺ +W ⁶⁺ +Ta ⁵⁺ ]The lower limit of (b) is preferably 5.0%, and more preferably 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10% in this order. The upper limit of the total content is preferably 20%, and more preferably 19%, 18%, 17%, 16%, and 15% in this order. From the viewpoint of increasing the refractive index nd and adjusting the Abbe number vd, it is preferable to make the total content in the above range.

Optical system of embodiment 2-1 the glass preferably contains substantially no Pb ²⁺ . Namely, pb is preferred ²⁺ The content of (B) is 0%. As and Th are also components having a potential for environmental burden, similarly to Pb. Thus, of As, thThe content of each is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01% in terms of oxide. The respective contents of As and Th are preferably 0% in terms of oxide. That is, it is preferable that substantially none of As and Th is contained.

The contents and ratios of the glass components other than those described above in the optical glass of embodiment 2-1 are non-limiting examples as follows.

In the optical glass of the embodiment 2-1, P ⁵⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, P ⁵⁺ The lower limit of the content of (b) is preferably 0.1%, and more preferably 0.5%, 0.8%, and 1% in this order. P ⁵⁺ The content of (B) may be 0%. By making P ⁵⁺ The content of (b) is in the above range, and the thermal stability of the glass can be maintained.

In the optical glass of embodiment 2-1, al ³⁺ The upper limit of the content of (b) is preferably 10%, and more preferably 8%, 6%, 4%, and 2% in this order. In addition, al ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 0.01%, 0.05%, 0.10%, 0.15%, and 0.20% in this order. Al (Al) ³⁺ The content of (b) may be 0%. Al (Al) ³⁺ Has the effect of suppressing phase separation of the glass by containing an appropriate amount. On the other hand, from the viewpoint of maintaining the thermal stability of the glass, it is preferable to use Al ³⁺ The content of (b) is within the above range.

In the optical glass of the embodiment 2-1, si ⁴⁺ 、B ³⁺ And Al ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ +Al ³⁺ ]The lower limit of (b) is preferably 50%, and more preferably 52%, 54%, 56%, and 57% in this order. The upper limit of the total content is preferably 80%, and more preferably 78%, 76%, 74%, and 72% in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, maintaining the thermal stability of the glass, and the stability at reheating, it is preferable to set the total content to the above range.

In the glass of embodiment 2-1, li ⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, 35%, 3The order of 0%, 25%, 20%, 18%, 16% is more preferred. In addition, li ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 5%, 10%, and 15% in this order. Li ⁺ The content of (b) may be 0%. Li ⁺ Is a component contributing to lowering the viscosity of the glass, and has a large effect of increasing the relative partial dispersion PC, t in the infrared wavelength region among alkali metals. Li ⁺ If the content of (b) is too large, stability during reheating may be lowered. In addition, li ⁺ When the content of (2) is too small, the viscosity of the glass may increase.

In the glass of embodiment 2-1, na ⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16% in this order. In addition, na ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 5%, 10%, and 12% in this order. Na (Na) ⁺ With Li ⁺ Similarly, the component contributes to lowering the viscosity of the glass. Na (Na) ⁺ If the content of (b) is too large, stability during reheating may be lowered. In addition, na ⁺ When the content of (b) is too small, the viscosity of the glass may increase.

In the optical glass of embodiment 2-1, K ⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, and 5% in this order. In addition, K ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. K is ⁺ The content of (B) may be 0%.

K ⁺ Has the functions of lowering the liquid phase temperature and improving the thermal stability of the glass. On the other hand, K ⁺ When the content of (b) is increased, chemical durability, weather resistance and stability upon reheating are lowered. Thus, K ⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, li ⁺ 、Na ⁺ And K ⁺ Of content R [ Li ] ⁺ +Na ⁺ +K ⁺ ]The upper limit of (b) is preferably 50%, and more preferably 45%, 40%, 35%, 30%, and 27% in this order. The lower limit of the total content R is preferably 5%, more preferably 8% or 11%The order of 13% is more preferable. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the total content R within the above range.

In the optical glass of embodiment 2-1, li ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content R [ Li ] ⁺ /R]The upper limit of (b) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75 and 0.70 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 2-1, na ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of total content R [ Na ] ⁺ /R]The upper limit of (b) is preferably 1, and more preferably 0.90, 0.80, 0.70, 0.60, 0.50, 0.40, and 0.35 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, and 0.25 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 2-1, K ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of total content R [ K ] ⁺ /R]The upper limit of (b) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the cation ratio in the above range.

In the optical glass of the embodiment 2-1, cs ⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, and 5% in this order. Cs ⁺ The lower limit of the content of (b) is preferably 0%. Cs ⁺ The content of (b) may be 0%.

Cs ⁺ The glass has an effect of improving the thermal stability of the glass, but when the content is increased, there is a risk of lowering the chemical durability and weather resistance. Thus, cs ⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, ti ⁴⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4% in this order. In addition, ti ⁴⁺ The lower limit of the content of (b) is preferably 0%. Ti ⁴⁺ The content of (B) may be 0%. By making Ti ⁴⁺ The content of (b) is in the above range, and a desired optical constant can be realized while suppressing an increase in specific gravity.

In the optical glass of embodiment 2-1, W ⁶⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4%, 2%, 1%, 0.5%, and 0.1% in this order. W ⁶⁺ The lower limit of the content of (b) is preferably 0%. W ⁶⁺ The content of (B) may be 0%. From the viewpoints of improving the transmittance, suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region, and reducing the specific gravity, it is preferable to use W ⁶⁺ The content of (B) is in the above range.

In the optical glass of embodiment 2-1, bi ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, and 6% in this order. In addition, bi ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, 3%, 4%, and 5% in this order. Bi ³⁺ The content of (B) may be 0%. From the viewpoint of improving the transmittance and reducing the specific gravity, and from the viewpoint of reducing damage to platinum manufacturing equipment, it is preferable to use Bi ³⁺ The content of (B) is in the above range.

In the optical glass of the embodiment 2-1, ta ⁵⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 9%, 8%, and 6% in this order. In addition, ta ⁵⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in this order. Ta ⁵⁺ The content of (B) may be 0%.

Ta ⁵⁺ Is a component which imparts high refractive index and low dispersion to glass and increases relative partial dispersion PC, t in the infrared wavelength region. On the other hand, ta ⁵⁺ When the content of (B) is increased, the raw material cost is increased. Further, there is a risk of an increase in specific gravity. Thus, ta ⁵⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³ ⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 14%, 13%, 12%, 11%, and 10% in this order. The lower limit of the total content is preferably 0.5%, and more preferably 1%, 2%, 3%, and 4% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of the embodiment 2-1, nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +W ⁶ ⁺ +Bi ³⁺ +Ta ⁵⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 14%, 13%, 12%, 11%, and 10% in this order. The lower limit of the total content is preferably 0.5%, and more preferably 1%, 2%, 3%, and 4% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of embodiment 2-1, zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Total content of [ Zr ] ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ ]The upper limit of (b) is preferably 20%, and more preferably 19%, 18%, 17%, 16%, and 15% in this order. The lower limit of the total content is preferably 5%, and more preferably 6%, 7%, 8%, 9%, and 10% in this order. From the viewpoint of maintaining a high refractive index, the total content is preferably set to the above range.

Light in embodiment 2-1In learning glass, zr ⁴⁺ And Nb ⁵⁺ Total content of [ Zr ] ⁴⁺ +Nb ⁵⁺ ]The upper limit of (b) is preferably 20%, and more preferably 19%, 18%, 17%, 16%, and 15% in this order. The lower limit of the total content is preferably 5%, and more preferably 6%, 7%, 8%, 9%, and 10% in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersion, it is preferable to make the total content be in the above range.

In the optical glass of embodiment 2-1, nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵ ⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 14%, 13%, 12%, 11%, and 10% in this order. The lower limit of the total content is preferably 0.5%, and more preferably 1%, 2%, 3%, and 4% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of embodiment 2-1, nb ⁵⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of the total content of [ Nb ] ⁵⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.99, 0.98, 0.97, 0.96, 0.95, 0.94, 0.93, 0.92, and 0.91 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.5, 0.6, 0.7, 0.8, and 0.9 in this order. The cation ratio may be 1. From the viewpoint of maintaining a high refractive index, the cation ratio is preferably in the above range.

In the optical glass of embodiment 2-1, ta ⁵⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of the total content of [ Ta ] ⁵⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From supressionFrom the viewpoint of an increase in the cost of raw materials for production, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 2-1, ti ⁴⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of the total content [ Ti ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of maintaining a high refractive index, the cation ratio is preferably in the above range.

In the optical glass of embodiment 2-1, zr ⁴⁺ Content of (2) and Zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Zr ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.9, and more preferably 0.8, 0.7, 0.6, and 0.55. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.15, 0.20, 0.25, and 0.30 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersibility, it is preferable to set the cation ratio to the above range.

In the optical glass of embodiment 2-1, nb ⁵⁺ Content of (2) and Zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of the total content of [ Nb ] ⁵⁺ /(Zr ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.9, and more preferably 0.8, 0.75, and 0.7 in this order. The lower limit of the cation ratio is preferably 0.1, and more preferably 0.2, 0.3, 0.4, and 0.45 in this order. From the viewpoint of maintaining high dispersibility, the cation ratio is preferably in the above range.

In the optical glass of embodiment 2-1, ta ⁵⁺ Content of (2) and Zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Total content of (A)Cation ratio of [ Ta ] ⁵⁺ /(Zr ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of suppressing an increase in the cost of raw materials, it is preferable to set the cation ratio within the above range.

In the optical glass of the embodiment 2-1, ti ⁴⁺ Content of (2) and Zr ⁴⁺ 、Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Cation ratio of the total content [ Ti ⁴⁺ /(Zr ⁴⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of maintaining high dispersibility, the cation ratio is preferably in the above range.

In the optical glass of embodiment 2-1, mg ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, mg ²⁺ The lower limit of the content of (b) is preferably 0%. Mg (magnesium) ²⁺ The content of (B) may be 0%.

Mg ²⁺ Is a component of alkaline earth metals that increases the relative partial dispersion PC, t in the infrared wavelength region. However, mg ²⁺ When the content (b) is increased, the high dispersion property is impaired, and the thermal stability and devitrification resistance of the glass may be lowered. Thus, mg ²⁺ The content of (b) is preferably in the above range.

In the optical glass of the embodiment 2-1, ca ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, ca ²⁺ The lower limit of the content of (b) is preferably 0%. Ca ²⁺ The content of (b) may be 0%.

Ca ²⁺ Is a component of the alkaline earth metal that increases the relative partial dispersion PC, t in the infrared wavelength region. However, ca ²⁺ When the content (b) is increased, the high dispersion property is impaired, and the thermal stability and devitrification resistance of the glass may be lowered. Thus, ca ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, sr ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, sr ²⁺ The lower limit of the content of (b) is preferably 0%. Sr (strontium) ²⁺ The content of (B) may be 0%.

Sr ²⁺ Is a component of the alkaline earth metal that increases the refractive index. However, sr ²⁺ When the content of (b) is increased, the high dispersion property is impaired, and there is a risk that the relative partial dispersion PC, t in the infrared wavelength region is lowered. Thus, sr ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, ba ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 9%, 8%, 7%, 6%, 5%, 4.5% in this order. Ba ²⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1.0%, 1.5%, and 2.0% in this order. Ba ²⁺ The content of (B) may be 0%.

Ba ²⁺ Is a component for increasing the refractive index of the composition, and at the same time is a component that lowers the liquidus temperature to improve the thermal stability of the glass. However, ba ²⁺ If the content of (b) is too large, the high dispersion property is impaired, and there is a risk that the relative partial dispersion PC, t in the infrared wavelength region is lowered. In addition, ba ²⁺ When the content of (b) is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Thus, ba ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, zn ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, zn ²⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.5%, and 0.7% in this order. Zn ²⁺ The content of (B) may be 0%.

Zn ²⁺ Has the function of improving the thermal stability of the glassGlass component (c). However, zn ²⁺ If the content (c) is too large, there is a risk of increasing the specific gravity, and there is a risk of decreasing the relative partial dispersion PC and t in the infrared wavelength region. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining desired optical constants, zn ²⁺ The content of (b) is preferably in the above range.

In the optical glass of the embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of [ Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4% in this order. The lower limit of the total content is preferably 0%, and more preferably 0.3%, 0.6%, 0.9%, 1.0%, 1.2%, 1.5%, 1.7%, 1.9% in this order. Mg (magnesium) ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of [ Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ]May be 0%. When the total content is too large, the high dispersion property is impaired, and there is a risk that the relative partial dispersion PC, t in the infrared wavelength region is lowered. When the total content is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the total content is preferably in the above range.

In the optical glass of embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content R' [ Mg ] ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4% in this order. The lower limit of the total content R' is preferably 0%, and more preferably 0.3%, 0.6%, 0.9%, 1.0%, 1.2%, 1.5%, 1.7%, 1.9% in this order. The total content R' may be 0%. When the total content R' is too large, high dispersion is impaired, and there is a risk of lowering the relative partial dispersion PC, t in the infrared wavelength region. When the total content R' is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the total content R' is preferably in the above range.

In the glass of embodiment 2-1, Y ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, and 3% in this order. In addition, Y ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1% and 2%. Y is ³⁺ The content of (B) may be 0%.

By introducing a certain amount of Y ³⁺ The refractive index nd can be increased. However, Y ³⁺ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass tends to be devitrified during production. In addition, there is a risk that the high dispersibility is impaired. Therefore, from the viewpoint of suppressing the decrease in thermal stability of the glass, Y is ³⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 2-1, sc ³⁺ The content of (b) is preferably 2% or less. Further, sc ³⁺ The lower limit of the content of (b) is preferably 0%.

In the glass of the 2 nd to 1 st embodiment, hf ⁴⁺ The content of (b) is preferably 2% or less. In addition, hf ⁴⁺ The lower limit of the content of (b) is preferably 0%.

Sc ³⁺ 、Hf ⁴⁺ Has the effect of improving the high dispersion of glass, but is an expensive component. Thus, sc ³⁺ 、Hf ⁴⁺ The respective contents of (a) and (b) are preferably within the above ranges.

In the glass of the embodiment 2-1, lu ³⁺ The content of (b) is preferably 2% or less. In addition, lu ³⁺ The lower limit of the content of (b) is preferably 0%.

Lu ³⁺ The glass component has the effect of improving the high dispersibility of the glass, but also increases the specific gravity of the glass because of its large molecular weight. Thus, lu ³⁺ The content of (b) is preferably in the above range.

In the glass of the embodiment 2-1, ge ⁴⁺ The content of (b) is preferably 2% or less. In addition, ge ⁴⁺ The lower limit of the content of (b) is preferably 0%.

Ge ⁴⁺ Has an effect of improving the high dispersion property of glass, but is a very expensive component among glass components generally used. Therefore, the manufacturing cost of the glass is reducedFrom the viewpoint of (1), ge ⁴⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 2-1, la ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, and 3% in this order. In addition, Y ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1% and 2%. La ³⁺ The content of (B) may be 0%. By introducing a certain amount of La ³⁺ The refractive index nd can be increased. However, la ³⁺ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass tends to be devitrified during production. In addition, there is a risk of deterioration in high dispersion, and there is a risk of lowering the relative partial dispersion PC, t in the infrared wavelength region. Thus, la ³⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 2-1, gd ³⁺ The content of (b) is preferably 2% or less. In addition, gd ³⁺ The lower limit of the content of (b) is preferably 0%.

Gd ³⁺ When the content of (A) is too large, the thermal stability of the glass is lowered. In addition, gd ³⁺ When the content (c) is too large, the specific gravity of the glass increases, which is not preferable. Moreover, there is a risk of an increase in raw material cost. Therefore, from the viewpoint of suppressing the increase in specific gravity while well maintaining the thermal stability of the glass, gd is used ³⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 2-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of [ La ] ³⁺ +Gd ³⁺ +Y ³⁺ ]The upper limit of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. The lower limit of the total content is preferably 0%. From the viewpoint of suppressing the decrease in thermal stability of the glass and the viewpoint of preventing the relative partial dispersion PC, t in the infrared wavelength region from decreasing, it is preferable to set the total content to the above range.

In the glass of embodiment 2-1, yb ³⁺ The content of (b) is preferably 2% or less. In addition, yb ³⁺ The lower limit of the content of (b) is preferably 0%.

And La ³⁺ 、Gd ³⁺ 、Y ³⁺ Compare，Yb ³⁺ Has a large molecular weight, and thus increases the specific gravity of the glass. In addition, yb ³⁺ When the content of (A) is too large, the thermal stability of the glass is lowered. Yb from the viewpoint of preventing the thermal stability of the glass from lowering and suppressing the increase in specific gravity ³⁺ The content of (b) is preferably in the above range.

In the glass of the 2 nd to 1 st embodiment, li ⁺ 、Na ⁺ And K ⁺ Total content of R and Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ R/(Si) ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 2.0, and more preferably 1.5, 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5 in this order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1 and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R' and Si ⁴⁺ And B ³⁺ Cation ratio of total contents [ R'/(Si) ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1, and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the glass of the embodiment 2-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ The cation ratio of the total content of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1, and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. The cation ratio may be 0. From the viewpoint of suppressing the decrease in thermal stability of the glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Nb) ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.50, and more preferably 0.40, 0.35, 0.30, 0.25 and 0.20 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.02, 0.04, and 0.06 in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the cation ratio to the above range.

In the glass of the embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content R [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )/R]The upper limit of (b) is preferably 0.6, and more preferably 0.5, 0.4, and 0.35 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.02, 0.04, and 0.06 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R' and Li ⁺ 、Na ⁺ And K ⁺ The cation ratio [ R'/R ] of the total content R]The upper limit of (b) is preferably 0.6, and more preferably 0.5, 0.4, and 0.35 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.02, 0.04, and 0.06 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content R of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/R]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, and 0.2 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.03, and 0.05 in this order. The cation ratio may be 0. From the viewpoint of suppressing the decrease in thermal stability of the glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ Of the total content R of [ (Nb) ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )/R]The upper limit of (b) is preferably 0.60, and more preferably 0.55, 0.50, 0.45, and 0.40 in this order. The lower limit of the cation ratio is preferably 0.05, and more preferably 0.10, 0.15, and 0.17 in this order. From the viewpoint of maintaining a high refractive index, improving the meltability of the glass, and reducing the viscosity of the molten glass to improve the moldability, it is preferable that the cation ratio is in the above range.

In the glass of embodiment 2-1, li ⁺ 、Na ⁺ And K ⁺ Total content R of (A) and the total content R, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Cation ratio of the total content [ R/(R + Mg ] ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.99, 0.98, 0.97, 0.96, 0.95 and 0.94 in this order. The lower limit of the cation ratio is preferably 0.50, and more preferably 0.55 or 0The order of 60, 0.65, 0.70, 0.75 is more preferred. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of the 2 nd to 1 st embodiment, li ⁺ 、Na ⁺ And K ⁺ Total content of R, mg ²⁺ And Ca ²⁺ To the total content of R and Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content R' of [ (R + Mg) ²⁺ +Ca ²⁺ )/(R+R’)]The upper limit of (b) is preferably 1, and more preferably 0.99, 0.98, 0.97, 0.96, 0.95 and 0.94 in this order. The lower limit of the cation ratio is preferably 0.50, and more preferably 0.55, 0.60, 0.65, 0.70, and 0.75 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 2-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Ta ⁵⁺ The cation ratio of the total content of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in thermal stability of the glass and maintaining a high refractive index, it is preferable to set the cation ratio to the above range.

The glass of embodiment 2-1 is preferably composed mainly of the above-mentioned glass component, i.e., si as an essential component ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ P as an optional component ⁵⁺ 、Al ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ 、Cs ⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ 、Ta ⁵⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ² ⁺ 、Zn ²⁺ 、Y ³⁺ 、Sc ³⁺ 、Hf ⁴⁺ 、Lu ³⁺ 、Ge ⁴⁺ 、La ³⁺ 、Gd ³⁺ And Yb ³⁺ And (4) forming. The total content of the above glass components is preferably 95% or more, more preferably 98% or more, still more preferably 99% or more, and particularly preferably 99.5% or more.

The optical glass of embodiment 2-1 contains O as an anionic component ^2- 。O ^2- The content of (b) is preferably 90 to 100 anionic%, more preferably 95 to 100 anionic%.

The optical glass of embodiment 2-1 may contain F as an anionic component ^- 。

F ^- The content of (b) is preferably 0 to 10 anionic%, more preferably 0 to 5 anionic%.

The optical glass of the 2 nd to 1 st embodiment may contain other than O ^2- And F ^- The other components are anionic components. As for removing O ^2- And F ^- Other anionic components, cl may be exemplified ^- 、Br ^- 、I ^- . However, cl ^- 、Br ^- 、I ^- Are easily volatilized during the melting of the glass. As these components volatilize, there are problems such as fluctuation in glass characteristics, reduction in glass homogeneity, and significant consumption of melting equipment. Thus, cl ^- The content of (b) is preferably less than 5 anionic%, more preferably less than 3 anionic%, further preferably less than 1 anionic%, particularly preferably less than 0.5 anionic%, still further preferably less than 0.25 anionic%. In addition, br ^- And I ^- The total content of (A) is preferably less than 5 anions%, more preferably less than 3 anions%, further preferably less than 1 anion%, particularly preferably less than 0.5 anions%, further preferably less than 0.1 anions%, further preferably 0 anions%.

The glass of embodiment 2-1 is preferably composed substantially of the above glass components, but may contain other components within a range not detrimental to the action and effect of the present invention. In the present invention, the inclusion of unavoidable impurities is not excluded.

In addition to the above components, the above optical glass may contain a small amount of Sb ³⁺ (Sb ₂ O ₃ ) And the like as clarifying agents. The total amount (additional addition amount) of the clarifying agent is preferably 0% or more and less than 1%, more preferably 0% or more and 0.5% or less, 0% or more and 0.3% or less, 0% or more and 0.2% or less, 0% or more and 0.1% or less, 0% or more and 0.05% or less, and 0% or more and 0.03% or less.

The additional amount is added when the total content of all glass components except the fining agent is 100%, the value obtained by expressing the amount of the clarifying agent added in percentage by weight.

In addition, the above optical glass can obtain high transmittance over a wide range of the visible light region. In order to fully utilize such a characteristic, it is preferable that the coloring element is not included. Examples of the coloring element include Cu, co, ni, fe, cr, eu, nd, er, V, and Ag. All the elements are preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably substantially not contained.

In the optical glass of embodiment 2-1, the glass characteristics may be the same as those of embodiment 1-1.

The optical glass and the optical element according to embodiment 2-1 may be manufactured in the same manner as embodiment 1-1.

2 nd to 2 nd embodiments

In the optical glass of the embodiment 2-2,

as glass the components of the components are mixed and stirred,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

the optical glass has a Δ PC, t of 0.0250 or more.

The optical glass of embodiment 2-2 contains Si ⁴⁺ As a glass component. Si ⁴⁺ The lower limit of the content of (b) is preferably 10%, and more preferably 12%, 14%, 16%, 18%, 20%, 22%, 23%, and 24% in this order. In addition, si ⁴⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 43%, 40%, 38%, 36%, 34%, 32%, 30% in this order. Si ⁴⁺ Is a network forming component of the glass. By containing Si ⁴⁺ The relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving chemical durability. From the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region and suppressing the decrease in thermal stability and chemical durability of the glass, siO ₂ The lower limit of the content of (b) is preferably set as described above. From the viewpoints of suppressing a decrease in the melting property of glass and preventing an increase in the viscosity of molten glass to deteriorate the moldability ₂ The upper limit of the content of (b) is preferably set as described above.

The optical glass of embodiment 2-2 contains B ³⁺ As a glass component. B is ³⁺ The lower limit of the content of (b) is preferably 20%, and more preferably 25%, 28%, 29%, 30%, 31%, 32% in this order. In addition, B ³⁺ The upper limit of the content of (b) is preferably 60%, and more preferably 55%, 50%, 48%, 46%, 44% in this order. B is ³⁺ Is a network forming component of the glass. By containing B ³⁺ As the glass component, the relative partial dispersion PC, t in the infrared wavelength region can be increased. From the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region and suppressing the decrease in thermal stability of the glass, B ³⁺ The lower limit of the content of (b) is preferably set as described above. From the viewpoint of suppressing the decrease in chemical durability of the glass, B ³⁺ The upper limit of the content of (b) is preferably set as described above.

The optical glass of embodiment 2-2 contains Zr ⁴⁺ As a glass component. Zr ⁴⁺ The lower limit of the content of (b) is preferably 1.0%, and more preferably 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% in this order. In addition, zr ⁴⁺ The upper limit of the content of (b) is preferably 8.5%, and more preferably 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, and 5.5% in this order. By containing Zr ⁴⁺ As the glass component, the relative partial dispersion PC, t in the infrared wavelength region can be increased, thereby improving chemical durability. From the viewpoint of suppressing the decrease in chemical durability, zr ⁴⁺ The lower limit of the content of (b) is preferably set as described above. From the viewpoint of suppressing the increase in liquidus temperature LT and suppressing the decrease in stability during reheating, zr ⁴⁺ The upper limit of the content of (b) is preferably set as described above.

The optical glass of embodiment 2-2 contains Nb ⁵⁺ As a glass component. Nb ⁵⁺ The content of (b) is preferably more than 0%, and the lower limit thereof is more preferably 2.0%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% in this order. In addition, nb ⁵⁺ The upper limit of the content of (b) is preferably 11.5%, and more preferably 10%, 9.5%, 9.0%, 8.5%, 8.0%, 7.5%, 7.0%, 6.5%, 6.0% in this order. By containing Nb ⁵⁺ As the glass component, it is possible to maintain high dispersion property while suppressing a decrease in relative partial dispersion PC, t in the infrared wavelength region. Nb, from the viewpoint of maintaining high dispersion ⁵⁺ The lower limit of the content of (b) is preferably set as described above. Nb from the viewpoint of suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region ⁵⁺ The upper limit of the content of (b) is preferably set as described above.

The optical glass of the 2 nd to 2 nd embodiments contains Li ⁺ 、Na ⁺ And K ⁺ As a glass component. Preferably contains Na ⁺ May contain Li ⁺ And Na ⁺ May contain Na ⁺ And K ⁺ May contain Li ⁺ And K ⁺ May contain Li ⁺ 、Na ⁺ And K ⁺ . By containing elements selected from Li ⁺ 、Na ⁺ And K ⁺ In (1)More than one glass component can increase relative partial dispersion PC, t in infrared wavelength region, thereby improving chemical durability.

In the optical glass of embodiment 2-2, si ⁴⁺ And B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]The lower limit of (b) is preferably 50%, and more preferably 52%, 54%, 56%, and 57% in this order. The upper limit of the total content is preferably 80%, and more preferably 78%, 76%, 74%, 72%, and 71%, in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining the thermal stability of the glass, it is preferable to set the total content to the above range. When the total content is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and there is a possibility that the thermal stability and chemical durability of the glass cannot be maintained. If the total content is too large, the viscosity of the molten glass may increase, and the moldability may deteriorate. In addition, there is a risk of lowering the refractive index.

In the optical glass of embodiment 2-2, B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]The lower limit of (b) is preferably 0.44, and more preferably 0.47, 0.50, 0.53, and 0.56 in this order. The upper limit of the cation ratio is preferably 0.80, and more preferably 0.75, 0.71, 0.67, 0.63, and 0.61 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. If the cation ratio is too large, the chemical durability of the glass may be deteriorated.

In the optical glass of embodiment 2-2, li ⁺ 、Na ⁺ And K ⁺ With the total content R and Mg ²⁺ 、Ca ² ⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (B) is [ R/(R + R')]The lower limit of (b) is preferably 0.55, and more preferably 0.60, 0.65, 0.70 and 0.75 in this order. The upper limit of the cation ratio is preferably 1.00, and further, 0.95, 0.90, and 0.85 are given in this orderMore preferably. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

The optical glass of embodiment 2-2 preferably satisfies one or more of the following (i) and (ii).

(i) In the optical glass of embodiment 2-2, zr ⁴⁺ With Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]The lower limit of (b) is preferably 0.17, and more preferably 0.20, 0.25, 0.30, 0.35, 0.37, 0.39, 0.40 in this order. The upper limit of the cation ratio is preferably 2.00, and more preferably 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, and 0.60 in this order. From the viewpoint of improving chemical durability, increasing the refractive index nd, and maintaining high dispersibility, it is preferable to set the cation ratio to the above range. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. If the cation ratio is too large, the liquidus temperature LT may increase, and the stability during reheating may decrease.

(ii) In the optical glass of embodiment 2-2, zr ⁴⁺ And Ta ⁵⁺ Total content of (2) and Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]The lower limit of (b) is preferably 0.25, and more preferably 0.30, 0.35, 0.37, 0.39, and 0.40 in this order. In additionThe upper limit of the cation ratio is preferably 3.10, and more preferably 2.80, 2.60, 2.40, 2.20, 2.00, 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, and 0.60 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, increasing the refractive index nd, maintaining high dispersion, and maintaining the chemical durability of the glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. When the cation ratio is too large, there is a risk that the thermal stability of the glass is lowered.

The contents, ratios, and the like of the glass components other than those described above in the optical glass of embodiment 2-2 may be the same as those in embodiment 2-1.

In the optical glass of embodiment 2-2, the deviation Δ PC, t is 0.0250 or more. The lower limit of the deviation Δ PC, t is preferably 0.0270, and more preferably 0.0290, 0.0310, 0.0330, 0.0350, and 0.0370 in this order. By setting the deviation Δ PC, t in the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of the deviation Δ PC, t is not particularly limited, but is usually 0.0900, preferably 0.0800. The method of calculating the deviation Δ PC, t is as described in embodiment 1-1.

In the optical glass of embodiment 2-2, glass characteristics other than those described above may be the same as those of embodiment 1-1.

The optical glass of embodiment 2-2 and the optical element can be manufactured in the same manner as embodiment 1-1.

Embodiment 3

In embodiment 3 (embodiment 3-1, embodiment 3-2, embodiment 3-3, and embodiment 3-4), the glass composition of the optical glass is expressed as cation% unless otherwise specified. In embodiment 3-1, the optical glass of the present invention is described based on the glass composition and the relative partial dispersion PC, t expressed as a function of the Abbe's number vd. In embodiment 3-2, the optical glass of the present invention will be described based on the glass composition. In embodiment 3-3, the optical glass of the present invention will be described by expressing the relationship between Δ PC, t and Δ Pg, F as a function of Δ Pg, F. In embodiments 3 to 4, the optical glass of the present invention will be described by expressing the relative partial dispersion PC, t as a function of the abbe number ν d.

3 st embodiment

In the oxide optical glass of embodiment 3-1,

Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ and Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ ]The content of the active carbon is more than 6.5 percent,

Zr ⁴⁺ content of (b) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the acid-resistant agent is more than 0.4,

the oxide optical glass is substantially free of Pb and As,

the PC, t of the oxide optical glass satisfies the following formula [2-2]:

PC,t≥0.5711+0.004667×νd···[2-2]，

the oxide optical glass satisfies one or more of the following (I) to (IV).

(I)Li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]Is 0.85 or less.

(II)Li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]The content of the compound is less than 0.97,

Li ⁺ 、Na ⁺ 、Mg ²⁺ and Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Of total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.75 or more.

(III)B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is 0.46 or more.

(IV)Li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.75 or more, B ³⁺ And Li ⁺ Total content of (D) and Si ⁴⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]Is 0.31 or more.

In 3-1In the optical glass of the embodiment, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵ ⁺ +W ⁶⁺ +Bi ³⁺ ]Is more than 6.5 percent. The lower limit of the total content is preferably 7%, 7.5%, 8%, 8.5%, and more preferably in this order. The upper limit of the total content is preferably 30%, and more preferably 20%, 15%, 12%, 11.5%, 11%, 10.5%, and 10% in this order. By setting the total content to the above range, a high refractive index and a desired abbe number ν d can be maintained.

In the optical glass of embodiment 3-1, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ² ⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.55 or more. The lower limit of the cation ratio is preferably 0.75, and more preferably 0.80, 0.85, and 0.90 in this order. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96, and 0.94 in this order. By setting the cation ratio in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, the melting property of the glass can be improved, and the viscosity of the molten glass can be reduced to improve the moldability. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

In the optical glass of embodiment 3-1, zr ⁴⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]Is 0.4 or more. The lower limit of the cation ratio is preferably 0.42, and more preferably 0.44, 0.46, 0.48, and 0.50. The cation ratio is higher thanThe limit is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.65, 0.6, and 0.55. By making the cation ratio in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be improved, and high dispersibility can be maintained.

In the optical glass of embodiment 3-1, si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³ ⁺ )]Is 8.6 or more. The lower limit of the cation ratio is preferably 8.8, and more preferably 9.0, 9.2, 9.4, 9.6 and 9.8 in this order. The upper limit of the cation ratio is preferably 20, and more preferably 18, 16, 14, 13, 12 and 11 in this order. By setting the cation ratio in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased and the abbe number can be adjusted.

The optical glass of embodiment 3-1 does not substantially contain Pb and As which are components having an environmental burden. That is, the respective contents of Pb ions and As ions are 0%. In addition, th is also a component having a potential for environmental burden, similarly to Pb and As. Therefore, the content of the Th ion is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01%. The content of Th ions is preferably 0%. That is, it is preferable that substantially no Th is contained. The Pb ions are removed from Pb ²⁺ In addition, the compound also contains Pb ions with different valences. The As ion and the Th ion also include ions having different valences.

In the optical glass of embodiment 1, the relative partial dispersion PC, t satisfies the following formula [2-2].

PC,t≥0.5711+0.004667×νd···[2-2]

It is more preferable that t satisfies the following formula [2-3] with respect to the partial dispersion PC, and it is further more preferable that t satisfies the following formula [2-4], the following formula [2-5], the following formula [2-6], the following formula [2-7] and the following formula [2-8] in this order.

PC,t≥0.5731+0.004667×νd···[2-3]

PC,t≥0.5751+0.004667×νd···[2-4]

PC,t≥0.5771+0.004667×νd···[2-5]

PC,t≥0.5791+0.004667×νd···[2-6]

PC,t≥0.5811+0.004667×νd···[2-7]

PC,t≥0.5831+0.004667×νd···[2-8]

By making the relative partial dispersions PC, t satisfy the above expression, the optical element made of the optical glass of embodiment 3-1 can compensate chromatic aberration well over a wide wavelength range.

The optical glass of embodiment 3-1 satisfies one or more of the following (I) to (IV).

(I)Li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]Is 0.85 or less.

(IV)Li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.75 or more, B ³⁺ And Li ⁺ Total content of (A) and Si ⁴⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]Is 0.31 or more.

That is, in the optical glass of the embodiment 3-1, in the case of the above (I), li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]May be set to 0.85 or less. In the case of the above (I), the upper limit of the cation ratio may be set to 0.80, 0.75, 0.70, 0.65, 0.60 or 0.55. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, in the case of (II) above, li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]May be set to 0.97 or less. In the case of the above (II), the upper limit of the cation ratio may be set to 0.85, 0.80, 0.75, 0.70, 0.65, 0.60 or 0.55. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, the optical glass of embodiment (II) isBelow, li ⁺ 、Na ⁺ 、Mg ²⁺ And Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ² ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]It may be set to 0.75 or more. In the case of the above (II), the lower limit of the cation ratio may be set to 0.77, 0.79, 0.81, 0.83, 0.85, 0.87, or 0.89. The upper limit of the cation ratio is preferably 1, and more preferably 0.99, 0.98 and 0.95 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the optical glass of the embodiment 3-1, in the case of the above-mentioned (III), B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]It may be set to 0.46 or more. In the case of the above (III), the lower limit of the cation ratio may be set to 0.50, 0.51, 0.53, 0.55, 0.57 or 0.59. The cation ratio is preferably less than 1, and the upper limits thereof are more preferably 0.90, 0.85, 0.80, 0.75, 0.70, and 0.65 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. If the cation ratio is too large, the chemical durability of the glass may be reduced.

In the optical glass of the embodiment 3-1, in the case of the above (IV), li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]It may be set to 0.75 or more. In the case of the above (IV), the lower limit of the cation ratio may be set to 0.80, 0.85 or 0.90. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96, and 0.94 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

In the optical glass of embodiment 3-1, in the case of (IV) above, B ³⁺ And Li ⁺ Total content of (D) and Si ⁴⁺ 、Na ⁺ And K ⁺ Of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]It may be set to 0.31 or more. The lower limit of the cation ratio may be set to 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10 or 1.20. The upper limit of the cation ratio is preferably 10, and more preferably 9, 8, 7, 6, 5, 4, 3, 2, and 1.8 in this order. The cation ratio is preferably in the above range from the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region.

The contents and ratios of the glass components other than those described above in the optical glass of embodiment 3-1 are not limited to the following examples.

The optical glass of embodiment 3-1 preferably contains Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ As a glass component.

In the optical glass of embodiment 3-1, si ⁴⁺ The lower limit of the content of (b) is preferably 5%, and more preferably 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21% in this order. In addition, si ⁴⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 40%, 35%, 32%, 30%, 28%, 26%, and 24% in this order. Si ⁴⁺ Is a network forming component of the glass. FromFrom the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, si is preferably used ⁴⁺ The content of (b) is set to the above range. Si ⁴⁺ When the content of (b) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability and chemical durability of the glass may be lowered. Si ⁴⁺ When the content of (b) is too large, there is a possibility that the meltability of the glass is lowered, and the viscosity of the molten glass is increased to deteriorate the moldability.

In the optical glass of embodiment 3-1, B ³⁺ The lower limit of the content of (b) is preferably 10%, and more preferably 15%, 20%, 25%, 28%, 30%, 32% in this order. In addition, B ³⁺ The upper limit of the content of (b) is preferably 60%, and more preferably 55%, 50%, 45%, 40%, 38%, 36% in this order. B ³⁺ Is a network forming component of the glass. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to use B ³⁺ The content of (b) is in the above range. B is ³⁺ When the content of (2) is too small, the relative partial dispersion PC, t in the infrared wavelength region is lowered, and the thermal stability of the glass may be lowered. B is ³⁺ If the content of (2) is too large, the chemical durability of the glass may be deteriorated.

In the optical glass of embodiment 3-1, zr ⁴⁺ The lower limit of the content of (b) is preferably 0.1%, and more preferably 1%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% in this order. In addition, zr ⁴⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 5% in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, zr is preferably used ⁴⁺ The content of (b) is in the above range. Zr ⁴⁺ When the content of (b) is too small, there is a possibility that chemical durability is lowered. Zr ⁴⁺ If the content (b) is too large, there is a possibility that the liquid phase temperature LT increases and the stability during reheating decreases.

In the optical glass of embodiment 3-1, nb ⁵⁺ The lower limit of the content of (b) is preferably 0.1%, and further 1%, 3%, 5%, 7%, 7.5%, 8% of cisThe sequence is more preferred. In addition, nb ⁵⁺ The upper limit of the content of (b) is preferably 30%, and more preferably 20%, 15%, 12%, 11.5%, 11%, 10.5%, 10% in this order. By adding Nb ⁵⁺ The content of (b) is set to the above range, it is possible to maintain high dispersion property while suppressing the decrease of relative partial dispersion PC, t in the infrared wavelength region. Nb ⁵⁺ When the content of (B) is too small, there is a possibility that the high dispersibility cannot be maintained. Nb ⁵⁺ If the content of (b) is too large, there is a risk of lowering the relative partial dispersion PC, t in the infrared wavelength region.

The optical glass of the embodiment 3-1 preferably contains Li ⁺ 、Na ⁺ And K ⁺ As a glass component. The optical glass of embodiment 3-1 more preferably contains Li ⁺ And Na ⁺ 。

In the glass of the 3-1 embodiment, li ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 5%, 10%, and 15% in this order. In addition, li ⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 40%, 30%, and 25% in this order. Li ⁺ Is a component contributing to lowering the viscosity of the glass, and has a large effect of increasing the relative partial dispersion PC, t in the infrared wavelength region among alkali metals. Li ⁺ If the content of (b) is too large, stability during reheating may be lowered. In addition, li ⁺ When the content of (b) is too small, the viscosity of the glass may increase.

In the glass of embodiment 3-1, na ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 2%, 4%, 6%, and 8% in this order. In addition, na ⁺ The upper limit of the content of (b) is preferably 50%, and more preferably 40%, 30%, 25%, 20%, 15%, 10% in this order. Na (Na) ⁺ With Li ⁺ Similarly, the component contributes to lowering the viscosity of the glass. Na (Na) ⁺ If the content of (b) is too large, stability during reheating may be lowered. In addition, na ⁺ When the content of (b) is too small, the viscosity of the glass may increase.

In the optical glass of embodiment 3-1, K ⁺ The upper limit of the content (c) of (d) is preferably 50%, more preferably 40%,30%, 25%, 20%, 15%, 10%, 5% are more preferred in this order. In addition, K ⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. K ⁺ The content of (b) may be 0%. K is ⁺ Has the functions of lowering the liquid phase temperature and improving the thermal stability of the glass. On the other hand, K ⁺ When the content of (b) is increased, chemical durability, weather resistance and stability upon reheating are lowered. Thus, K ⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, li ⁺ 、Na ⁺ And K ⁺ Total content of [ Li ] ⁺ +Na ⁺ +K ⁺ ]The lower limit of (b) is preferably 1%, and more preferably 5%, 10%, 15%, 20%, and 25% in this order. Further, the total content [ Li ⁺ +Na ⁺ +K ⁺ ]The upper limit of (b) is preferably 60%, and more preferably 50%, 40%, 35%, and 30% in this order. From the viewpoint of suppressing a decrease in stability during reheating, the total content is preferably in the above range.

In the optical glass of the embodiment 3-1, al ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 2%, and 1% in this order. In addition, al ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.2%, and 0.3% in this order. Al (Al) ³⁺ The content of (B) may be 0%. Al (aluminum) ³⁺ Has the effect of suppressing phase separation of the glass by containing an appropriate amount. On the other hand, from the viewpoint of maintaining the thermal stability of the glass, it is preferable to use Al ³⁺ The content of (b) is in the above range.

In the optical glass of embodiment 3-1, P ⁵⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, P ⁵⁺ The lower limit of the content of (b) is preferably 0.1%, and more preferably 0.5%, 0.8%, and 1% in this order. P ⁵⁺ The content of (B) may be 0%. By adding P ⁵⁺ The content of (b) is in the above range, and the thermal stability of the glass can be maintained.

In the optical glass of embodiment 3-1, cs ⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, and 5% in this order. Cs ⁺ The lower limit of the content of (b) is preferably 0%. Cs ⁺ The content of (B) may be 0%.

In the optical glass of embodiment 3-1, mg ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, mg ²⁺ The lower limit of the content of (b) is preferably 0%. Mg (magnesium) ²⁺ The content of (B) may be 0%.

Mg ²⁺ Is a component of the alkaline earth metal that increases the relative partial dispersion PC, t in the infrared wavelength region. However, mg ²⁺ When the content (b) is increased, the high dispersion property is impaired, and the thermal stability and devitrification resistance of the glass may be lowered. Thus, mg ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, ca ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, ca ²⁺ The lower limit of the content of (b) is preferably 0%. Ca ²⁺ The content of (B) may be 0%.

Ca ²⁺ Is a component of the alkaline earth metal that increases the relative partial dispersion PC, t in the infrared wavelength region. However, ca ²⁺ When the content of (b) is increased, the high dispersion property is impaired, and the thermal stability and devitrification resistance of the glass may be lowered. Thus, ca ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, sr ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, sr ²⁺ The lower limit of the content of (b) is preferably 0%. Sr (strontium) ²⁺ The content of (B) may be 0%.

In the optical glass of embodiment 3-1, ba ²⁺ The upper limit of the content of (b) is preferably 20%, further, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3% are more preferable in this order. Ba ²⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 0.5%, 1.0%, and 1.5% in this order. Ba ²⁺ The content of (B) may be 0%.

Ba ²⁺ Is a component for increasing the refractive index and, at the same time, is a component for decreasing the liquidus temperature to increase the thermal stability of the glass. However, ba ²⁺ If the content of (b) is too large, the high dispersion property is impaired, and there is a risk that the relative partial dispersion PC, t in the infrared wavelength region is lowered. In addition, ba ²⁺ When the content of (b) is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Thus, ba ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, zn ²⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. In addition, zn ²⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.5%, and 0.7% in this order. Zn ²⁺ The content of (B) may be 0%.

Zn ²⁺ Is a glass component having an effect of improving the thermal stability of the glass. However, zn ²⁺ If the content (c) is too large, there is a risk of increasing the specific gravity, and there is a risk of decreasing the relative partial dispersion PC and t in the infrared wavelength region. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining desired optical constants, zn ²⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, la ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, and 3% in this order. In addition, la ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1% and 2% in this orderPreferably. La ³⁺ The content of (B) may be 0%. By introducing a certain amount of La ³⁺ The refractive index nd can be increased. However, la ³⁺ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass is likely to be devitrified during production. In addition, there is a risk of deterioration of high dispersion, and there is a risk of lowering of relative partial dispersion PC, t in the infrared wavelength region. Thus, la ³⁺ The content of (b) is preferably in the above range.

In the glass of the 3 rd to 1 st embodiment, gd ³⁺ The content of (b) is preferably 2% or less. In addition, gd ³⁺ The lower limit of the content of (b) is preferably 0%. Gd (Gd) ³⁺ When the content of (A) is too large, the thermal stability of the glass is lowered. In addition, gd ³⁺ When the content of (2) is too large, the specific gravity of the glass increases, which is not preferable. Moreover, there is a risk of an increase in raw material cost. Therefore, from the viewpoint of suppressing the increase in specific gravity while well maintaining the thermal stability of the glass, gd is used ³⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, Y ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 4%, and 3% in this order. In addition, Y ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1% and 2% in this order. Zxfoom Y ³⁺ The content of (B) may be 0%.

By introducing a certain amount of Y ³⁺ The refractive index nd can be increased. However, Y ³⁺ When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass is likely to be devitrified during production. In addition, there is a risk that the high dispersibility is impaired. Therefore, from the viewpoint of suppressing the decrease in thermal stability of the glass, Y is ³⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, ti ⁴⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4% in this order. In addition, ti ⁴⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. Ti ⁴⁺ The content of (b) may be 0%. By mixing Ti ⁴⁺ The content of (b) is set to the above range, a desired optical constant can be realized,but also to suppress an increase in specific gravity.

In the optical glass of embodiment 3-1, ta ⁵⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 9%, 8%, and 6% in this order. In addition, ta ⁵⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in this order. Ta ⁵⁺ The content of (B) may be 0%.

Ta ⁵⁺ Is a component which imparts high refraction and low dispersion to the glass and improves the relative partial dispersion PC, t in the infrared wavelength region. On the other hand, in the case of a liquid, ta ⁵⁺ When the content of (B) is increased, the raw material cost is increased. In addition, there is a risk of an increase in specific gravity. Thus, ta ⁵⁺ The content of (b) is preferably in the above range.

In the optical glass of embodiment 3-1, W ⁶⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4%, 2%, 1%, 0.5%, and 0.1% in this order. W is a group of ⁶⁺ The lower limit of the content of (b) is preferably 0%. W ⁶⁺ The content of (b) may be 0%. From the viewpoints of improving the transmittance, suppressing the decrease in relative partial dispersion PC, t in the infrared wavelength region, and reducing the specific gravity, it is preferable to use W ⁶⁺ The content of (b) is set to the above range.

In the optical glass of embodiment 3-1, bi ³⁺ The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, 8%, and 6% in this order. In addition, bi ³⁺ The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, 3%, 4%, and 5% in this order. Bi ³⁺ The content of (B) may be 0%. From the viewpoint of improving the transmittance and lowering the specific gravity, and from the viewpoint of reducing damage to platinum manufacturing equipment, bi is preferably used ³⁺ The content of (b) is in the above range.

In the glass of embodiment 3-1, sc ³⁺ The content of (b) is preferably 2% or less. In addition, sc ³⁺ The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 3-1, hf ⁴⁺ The content of (b) is preferably 2% or less. In addition, hf ⁴⁺ In an amount ofLower limit of (2) preferably 0%.

Sc ³⁺ 、Hf ⁴⁺ Has an effect of improving the high dispersion of glass, but is an expensive component. Thus, sc ³⁺ 、Hf ⁴⁺ The respective contents of (a) and (b) are preferably within the above ranges.

In the glass of the embodiment 3-1, lu ³⁺ The content of (b) is preferably 2% or less. In addition, lu ³⁺ The lower limit of the content of (b) is preferably 0%.

Lu ³⁺ The glass component has an effect of improving the high dispersion property of glass, but is also a glass component that increases the specific gravity of glass due to its large molecular weight. Thus, lu ³⁺ The content of (b) is preferably in the above range.

In the glass of the embodiment 3-1, ge ⁴⁺ The content of (b) is preferably 2% or less. In addition, ge ⁴⁺ The lower limit of the content of (b) is preferably 0%.

Ge ⁴⁺ Has the effect of improving the high dispersion of glass, but is a very expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, ge ⁴⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, yb ³⁺ The content of (b) is preferably 2% or less. In addition, yb ³⁺ The lower limit of the content of (b) is preferably 0%.

And La ³⁺ 、Gd ³⁺ 、Y ³⁺ In contrast, yb ³⁺ Has a large molecular weight, and therefore, the specific gravity of the glass increases. In addition, yb ³⁺ When the content of (A) is too large, the thermal stability of the glass is lowered. Yb from the viewpoint of preventing the thermal stability of the glass from lowering and suppressing the increase in specific gravity ³⁺ The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, the upper limit of the content of each of Cu ions and Ag ions is preferably 1%, and more preferably 0.5%, 0.2%, 0.1%, 0.05%, and 0.03%, in this order. The lower limit of the content of each of Cu ions and Ag ions is preferably 0%. The respective contents of Cu ions and Ag ions are preferably in the above ranges from the viewpoint of suppressing coloring of the glass. The Cu ions and the Ag ions each contain ions having different valences.

In the glass of embodiment 3-1, nb ⁵⁺ And Ti ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Nb) ⁵⁺ +Ti ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]The lower limit of (b) is preferably 0.5, and more preferably 0.6, 0.7, 0.8, 0.9, and 0.95 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.99, 0.98 and 0.97 in this order. The cation ratio is preferably in the above range from the viewpoint of suppressing a decrease in relative partial dispersion PC, t in the infrared wavelength region.

In the optical glass of the embodiment 3-1, si ⁴⁺ And B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]The lower limit of (b) is preferably 20%, and more preferably 25%, 30%, 35%, 40%, 45%, 50%, 52%, 54%, and 56% in this order. The upper limit of the total content is preferably 80%, and more preferably 75%, 70%, 65%, and 60% in this order. By setting the total content to the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, and the thermal stability of the glass can be maintained. When the total content is too small, the relative partial dispersion PC, t in the infrared wavelength region is reduced, and the thermal stability and chemical durability of the glass cannot be maintained. If the total content is too large, the viscosity of the molten glass may increase, and the moldability may deteriorate. In addition, there is a risk of lowering the refractive index.

In the optical glass of embodiment 3-1, si ⁴⁺ 、B ³⁺ And Al ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ +Al ³⁺ ]The lower limit of (b) is preferably 20%, and more preferably 25%, 30%, 35%, 40%, 45%, 50%, 52%, 54%, 56% in this order. The upper limit of the total content is preferably 80%, and more preferably 75%, 70%, 65%, and 60% in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, the thermal stability of the holding glass, and the stability at reheating, it is preferable to set the total content to the above range.

In the optical glass of the embodiment 3-1, li ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content [ Li ] ⁺ /(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, and 0.75 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, and 0.65 in this order. From the viewpoint of suppressing the reduction in stability during reheating, it is preferable to set the cation ratio within the above range.

In the optical glass of embodiment 3-1, na ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content of [ Na ] ⁺ /(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.90, 0.80, 0.70, 0.60, 0.50, 0.40, and 0.35 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, and 0.25 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, K ⁺ With Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content [ K ] ⁺ /(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, and 0.25 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability during reheating, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of [ Mg ] ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ]The upper limit of (B) is preferably 20%, more preferably 15%, 10%, 9%And 8%, 7%, 6%, 5%, 4%, 3% are more preferred in this order. The lower limit of the total content is preferably 0%, and more preferably 0.3%, 0.6%, 0.9%, 1.0%, 1.2%, 1.5%, 1.7%, and 1.9% in this order. The total content may be 0%. If the total content is too large, the high dispersion property is impaired, and the relative partial dispersion PC, t in the infrared wavelength region may decrease. When the total content is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the total content is preferably in the above range.

In the optical glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of [ Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ ]The upper limit of (b) is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3% in this order. The lower limit of the total content is preferably 0%, and more preferably 0.3%, 0.6%, 0.9%, 1.0%, 1.2%, 1.5%, 1.7%, and 1.9% in this order. The total content may be 0%. If the total content is too large, the high dispersion property is impaired, and the relative partial dispersion PC, t in the infrared wavelength region may decrease. When the total content is too small, the refractive index nd may decrease, and the thermal stability and devitrification resistance of the glass may decrease. Therefore, the total content is preferably in the above range.

In the glass of embodiment 3-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of [ La ] ³⁺ +Gd ³⁺ +Y ³⁺ ]The upper limit of (b) is preferably 20%, and more preferably 10%, 5%, 4%, 3%, 2%, 1% in this order. The lower limit of the total content is preferably 0%. From the viewpoint of suppressing the decrease in thermal stability of the glass and the viewpoint of preventing the relative partial dispersion PC, t in the infrared wavelength region from decreasing, it is preferable to set the total content to the above range.

In the optical glass of embodiment 3-1, nb ⁵⁺ And Zr ⁴⁺ Total content of [ Nb ] ⁵⁺ +Zr ⁴⁺ ]The upper limit of (2) is preferably 30%, and more preferablyThe order of 25%, 20%, 18%, 16%, 15% is more preferred. The lower limit of the total content is preferably 5%, and more preferably 7%, 9%, 10%, 11%, and 12% in this order. From the viewpoint of minimizing the decrease in relative partial dispersion PC, t in the infrared wavelength range without impairing the high dispersibility, it is preferable to set the total content to the above range.

In the optical glass of embodiment 3-1, ta ⁵⁺ And Zr ⁴⁺ Total content of [ Ta ] ⁵⁺ +Zr ⁴⁺ ]The upper limit of (3 a) is preferably 20.0%, and more preferably 15.0%, 12.0%, 10.0%, 9.5%, 9.0%, 8.5%, 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, 5.5%, 5.0% in this order. The lower limit of the total content is preferably 1.0%, and more preferably 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, and 4.5% in this order. From the viewpoint of maintaining the thermal stability of the glass, the total content is preferably in the above range. When the total content is too small, the chemical durability of the glass may be deteriorated. When the total content is too large, there is a risk of lowering the thermal stability of the glass and a risk of increasing the raw material cost.

In the optical glass of the embodiment 3-1, nb ⁵⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ Nb ] ⁵⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.99, 0.98, 0.97, 0.96, 0.95, 0.94, 0.93, 0.92, and 0.91 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.5, 0.6, 0.7, 0.8, and 0.9 in this order. The cation ratio may be 1. From the viewpoint of maintaining a high refractive index, the cation ratio is preferably in the above range.

In the optical glass of embodiment 3-1, ta ⁵⁺ Content of (b) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Ta ] ⁵⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of suppressing an increase in raw material cost, it is preferable to set the cation ratio within the above range.

In the optical glass of embodiment 3-1, ti ⁴⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content [ Ti ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of maintaining high dispersion properties and suppressing an increase in relative partial dispersion Pg, F in the visible short wavelength region, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Zr ⁴ ⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ ]The lower limit of (b) is preferably 5.0%, and more preferably 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13% in this order. The upper limit of the total content is preferably 20%, and more preferably 19%, 18%, 17%, 16%, and 15% in this order. From the viewpoint of increasing the refractive index nd and adjusting the abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of embodiment 3-1, nb ⁵⁺ Content of (b) and Nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ Nb ] ⁵⁺ /(Nb ⁵⁺ +Zr ⁴⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]Preferably has an upper limit of0.9, and more preferably 0.8, 0.75, and 0.7. The lower limit of the cation ratio is preferably 0.1, and more preferably 0.2, 0.3, 0.4, and 0.45 in this order. From the viewpoint of maintaining high dispersibility, the cation ratio is preferably in the above range.

In the optical glass of embodiment 3-1, zr ⁴⁺ Content of (2) and Nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Zr ⁴⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 0.9, and more preferably 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in this order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.15, 0.20, 0.25, and 0.30 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersion, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-1, ta ⁵⁺ Content of (b) and Nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ Ta ] ⁵⁺ /(Nb ⁵⁺ +Zr ⁴⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, and 0.07 in this order. The cation ratio may be 0. From the viewpoint of suppressing an increase in the cost of raw materials, it is preferable to set the cation ratio within the above range.

In the optical glass of embodiment 3-1, ti ⁴⁺ Content of (2) and Nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content [ Ti ⁴⁺ /(Nb ⁵⁺ +Zr ⁴⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.03, 0.05, or 0.07The order of (a) is more preferable. The cation ratio may be 0. From the viewpoint of maintaining high dispersion properties and suppressing an increase in relative partial dispersion Pg, F in the visible short wavelength region, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of (A) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1, and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. The cation ratio may be 0. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the cation ratio to the above range.

In the glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1, and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. The cation ratio may be 0. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the cation ratio to the above range.

In the optical glass of the embodiment 3-1, li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of (A) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 1.50, more preferably 1.40, 1.30, 1.20, 1.10. The order of 1.00, 0.90, 0.80, 0.70, 0.60, 0.55 is more preferred. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and 0.45 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the cation ratio to the above range.

In the glass of embodiment 3-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ The cation ratio of the total content of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, 0.1, and 0.08 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in this order. The cation ratio may be 0. From the viewpoint of suppressing the decrease in thermal stability of the glass, it is preferable to set the cation ratio in the above range.

In the glass of the embodiment 3-1, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of (D) and Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Nb) ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )/(Si ⁴⁺ +B ³⁺ )]The upper limit of (b) is preferably 0.50, and more preferably 0.40, 0.35, 0.30, 0.25, 0.20, and 0.18 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12 in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the cation ratio to the above range.

In the glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content of [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 0.6, and more preferably 0.5, 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and the cation ratio is more preferably 0.02, 0.04,The order of 0.06 is more preferable. The cation ratio may be 0. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 3-1, mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (Mg) ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 0.6, and more preferably 0.5, 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.02, 0.04, and 0.06 in this order. The cation ratio may be 0. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 3-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 0.5, and more preferably 0.4, 0.3, and 0.2 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.03, and 0.05 in this order. The cation ratio may be 0. From the viewpoint of suppressing the decrease in thermal stability of the glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 3-1, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of (2) and Li ⁺ 、Na ⁺ And K ⁺ Cation ratio of the total content of [ (Nb) ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )/(Li ⁺ +Na ⁺ +K ⁺ )]The upper limit of (b) is preferably 0.60, and further 0.55, 0.50, 0.45 and 0.40 in this orderPreferably. The lower limit of the cation ratio is preferably 0.05, and more preferably 0.10, 0.15, 0.17, 0.19, 0.21, 0.23, and 0.25 in this order. From the viewpoint of maintaining a high refractive index, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio within the above range.

In the glass of embodiment 3-1, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ And Ba ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.99, 0.98, 0.97, 0.96, 0.95 and 0.94 in this order. The lower limit of the cation ratio is preferably 0.50, and more preferably 0.55, 0.60, 0.65, 0.70, and 0.75 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, improving the melting property of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the glass of embodiment 3-1, la ³⁺ 、Gd ³⁺ And Y ³⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ The cation ratio of the total content of [ (La) ³⁺ +Gd ³⁺ +Y ³⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in thermal stability of the glass and maintaining a high refractive index, it is preferable to set the cation ratio to the above range.

In the optical glass of embodiment 3-1, B ³⁺ Content of (2) and Nb ⁵⁺ 、Zr ⁴⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Of (2) to cation ratio [ B ³⁺ /(Nb ⁵⁺ +Zr ⁴⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The upper limit of (b) is preferably 7.0, and more preferably 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, and 3.0. The lower limit of the cation ratio is preferably 1.0, and more preferably 1.2, 1.4, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, and 2.2 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the cation ratio to the above range.

In the optical glass of embodiment 3-1, zr ⁴⁺ Content of (b) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ 、Bi ³⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]The lower limit of (b) is preferably 0.17, and more preferably 0.20, 0.25, 0.30, 0.35, 0.37, 0.39, 0.40 in this order. The upper limit of the cation ratio is preferably 2.00, and more preferably 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, and 0.60 in this order. From the viewpoint of improving chemical durability, increasing refractive index nd, and maintaining high dispersion properties, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. If the cation ratio is too large, the liquid phase temperature LT may increase, and the stability during reheating may decrease.

In the optical glass of the embodiment 3-1, zr ⁴⁺ And Ta ⁵⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]The lower limit of (b) is preferably 0.25, and more preferably 0.30, 0.35, 0.37, 0.39, and 0.40 in this order. The upper limit of the cation ratio is preferably 3.10, and more preferably 2.80, 2.60, 2.40, 2.20, 2.00, 1.80, 1.60, 1.40, 1.20, 1.00, 0.80, 0.60, and 0.55. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, increasing the refractive index nd, maintaining high dispersion, and maintaining the chemical durability of the glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, the refractive index nd may decrease, and the chemical durability of the glass may decrease. When the cation ratio is too large, there is a risk that the thermal stability of the glass is lowered.

The glass of embodiment 3-1 is preferably composed mainly of the above-described glass component, i.e., si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ 、Nb ⁵⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ 、Al ³⁺ 、P ⁵⁺ 、Cs ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ 、Zn ²⁺ 、La ³⁺ 、Gd ³⁺ 、Y ³⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ 、Bi ³⁺ 、Sc ³⁺ 、Hf ⁴⁺ 、Lu ³ ⁺ 、Ge ⁴⁺ And Yb ³⁺ And (4) forming. The total content of the glass components is preferably 95% or more, more preferably 98% or more, still more preferably 99% or more, and particularly preferably 99.5% or more.

The optical glass of the 3-1 embodiment is an oxide glass containing O ^2- As the anionic component. O is ^2- The content of (b) is preferably 90 to 100 anionic%, more preferably 95 to 100 anionic%.

The optical glass of embodiment 3-1 may contain F ^- As the anionic component. F ^- The content of (b) is preferably 0 to 10 anionic%, more preferably 0 to 5 anionic%.

The optical glass of the 3-1 embodiment may contain other than O ^2- And F ^- The other components are anionic components. As for removing O ^2- And F ^- The other of the anionic components is an anionic component,cl can be exemplified ^- 、Br ^- 、I ^- . However, cl ^- 、Br ^- 、I ^- Are easily volatilized during the melting of the glass. As these components volatilize, there are problems such as fluctuation of glass characteristics, reduction of glass homogeneity, and remarkable consumption of melting equipment. Therefore, the content of Cl "is preferably less than 5 anions%, more preferably less than 3 anions%, further preferably less than 1 anion%, particularly preferably less than 0.5 anions%, further preferably less than 0.25 anions%. The total content of Br-and I-is preferably less than 5 anions%, more preferably less than 3 anions%, still more preferably less than 1 anion%, particularly preferably less than 0.5 anions%, still more preferably less than 0.1 anions%, and still more preferably 0 anions%.

In the optical glass of embodiment 3-1, F ^- 、Cl ^- 、Br ^- And I ^- Total content of [ F ] ^- +Cl ^- +Br ^- +I ^- ]The upper limit of (b) is preferably 5 anionic%, and more preferably 3 anionic%, 1 anionic%, 0.5 anionic%, and 0.1 anionic% in this order. The lower limit of the total content is 0 anion%. The total content may be 0 anionic%. As these components volatilize, there are problems such as fluctuation in glass characteristics, reduction in glass homogeneity, and significant consumption of melting equipment. Therefore, the total content is preferably in the above range.

The glass of embodiment 3-1 is preferably composed substantially of the above glass components, but may contain other components within a range not detrimental to the effects of the invention. In the present invention, the inclusion of unavoidable impurities is not excluded.

In addition to the above components, the above optical glass may contain a small amount of Sb ³⁺ And the like as clarifying agents. The total amount (additional addition amount) of the clarifying agent is preferably 0% or more and less than 1%, more preferably 0% or more and 0.9% or less, 0% or more and 0.8% or less, 0% or more and 0.7% or less, 0% or more and 0.6% or less, 0% or more and 0.5% or less, 0% or more and 0.4% or less, 0% or more and 0.3% or less, 0% or more and 0.2% or lessLower, 0% to 0.1%, 0% to 0.05%, 0% to 0.03%.

The additional amount is a value obtained by expressing the amount of the clarifying agent added in mole percentage, assuming that the total content of all the cationic components except the clarifying agent is 100%.

In addition, the above optical glass can obtain high transmittance over a wide range of the visible light region. In order to fully utilize such characteristics, it is preferable that the coloring element is not included. Examples of the coloring element include Co, ni, fe, cr, eu, nd, er, and V. All the elements are preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, still more preferably 0 to 50 mass ppm, and particularly preferably substantially not contained.

(glass Properties)

Abbe number ν d >

In the optical glass of embodiment 3-1, the abbe number ν d is preferably 30 to 60, and may be set to 32 to 50, 34 to 45, 36 to 40, or 37 to 39.

The abbe number ν d can be set to a desired value by appropriately adjusting the content of each glass component. A component capable of relatively lowering the Abbe number ν d, i.e., a high dispersion component Nb ⁵⁺ 、Ti ⁴⁺ 、Zr ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ 、Ta ⁵⁺ And so on. On the other hand, the low dispersion component, which is a component that relatively increases the abbe number ν d, is Si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ 、La ³⁺ 、Ba ²⁺ 、Ca ²⁺ 、Sr ²⁺ And so on.

< refractive index nd >

In the optical glass of embodiment 3-1, the refractive index nd may be preferably 1.50 to 1.80, and may be 1.60 to 1.70, 1.63 to 1.69, or 1.66 to 1.68.

The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The component having the effect of relatively increasing the refractive index nd (high refractive index component) is Nb ⁵⁺ 、Ti ⁴⁺ 、Zr ⁴⁺ 、Ta ⁵⁺ 、La ³⁺ And the like. On the other hand, the component having the effect of relatively lowering the refractive index nd (low refractive index lowering component) is Si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And the like.

< relative partial dispersion Pg, F >

In the optical glass of embodiment 3-1, the upper limit of the relative partial dispersion Pg, F of the visible short-wavelength region is preferably 0.5900, and more preferably in the order of 0.5850, 0.5820, 0.5780, 0.5770, 0.5760, 0.5750. By making the relative partial dispersions Pg, F in the above ranges, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the lower limit of F with respect to the partial dispersion Pg is not particularly limited, but is usually 0.5600, preferably 0.5650.

In the optical glass of embodiment 3-1, the relative partial dispersions Pg, F preferably satisfy the following formula [1-1].

Pg,F≤0.6463-0.001802×νd···[1-1]

The relative partial dispersion Pg, F more preferably satisfies the following formula [1-2], and further preferably satisfies the following formula [1-3], the following formula [1-4], the following formula [1-5] and the following formula [1-6] in this order.

Pg,F≤0.6458-0.001802×νd···[1-2]

Pg,F≤0.6453-0.001802×νd···[1-3]

Pg,F≤0.6448-0.001802×νd···[1-4]

Pg,F≤0.6446-0.001802×νd···[1-5]

Pg,F≤0.6443-0.001802×νd···[1-6]

In the optical element made of the optical glass of embodiment 3-1, the relative partial dispersion Pg, F preferably satisfies the above formula from the viewpoint of satisfactorily compensating chromatic aberration in a wide wavelength range.

In the optical glass of embodiment 3-1, the upper limit of Δ Pg, F is preferably-0.0020, and more preferably-0.0025, -0.0030, -0.0035, -0.0037, and-0.0040. On the other hand, the lower limit of Δ Pg, F is not particularly limited, but is usually-0.0100, preferably-0.0080. By setting Δ Pg, F in the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained.

< relative partial dispersion PC, t >

In the optical glass of the embodiment 3 to 1, the lower limit of the relative partial dispersion PC, t in the infrared wavelength region is preferably 0.7200, and more preferably 0.7300, 0.7400, 0.7450, 0.7500, 0.7550, 0.7560, 0.7570, 0.7580, 0.7590, and 0.7600 in this order. By making the relative partial dispersion PC, t the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained. On the other hand, the upper limit of t for the partial dispersion PC is not particularly limited, but is usually 0.8500, preferably 0.8400, and more preferably in the order of 0.8300, 0.8200, 0.8100, and 0.8000.

In the optical glass of embodiment 3-1, the lower limit of Δ PC, t is preferably 0.0200, and more preferably 0.0250, 0.0270, 0.0290, 0.0310, 0.0330, 0.0350, and 0.0370. On the other hand, the upper limit of Δ PC, t is not particularly limited, but is usually 0.0900, preferably 0.0800. By setting Δ PC, t to the above range, an optical glass suitable for compensating for high-order chromatic aberration can be obtained.

The relative partial dispersion PC, t can be set to a desired value by appropriately adjusting the content of each glass component. The component having the effect of relatively increasing the relative partial dispersion PC, t is Si ⁴⁺ 、B ³⁺ 、Al ³⁺ 、Li ⁺ And so on. On the other hand, the component having the effect of relatively reducing the relative partial dispersion PC, t is Sr ²⁺ 、Ba ²⁺ 、Zn ²⁺ 、La ³⁺ 、Ti ⁴⁺ 、Nb ⁵⁺ 、W ⁶⁺ And so on.

< Δ Pg, F and Δ PC, t >

In the optical glass of the embodiment 3-1, Δ Pg, F and Δ PC, t preferably satisfy the following (i) or (ii).

(i) When the delta Pg and the F are more than-0.0037, the delta PC and t are more than or equal to 2.875 Xdelta Pg and F +0.031.

(ii) When Δ Pg and F are-0.0037 or less, Δ PC, t is not less than 4.750 × Δ Pg, F +0.038.

(i) In the optical glass of embodiment 3-1, when Δ Pg, F is greater than-0.0037, it is more preferable that the following formula (A1), and further the following formula (A2), the following formula (A3), the following formula (A4), and the following formula (A5) are satisfied in this order.

ΔPC,t≥2.875×ΔPg,F+0.031···(A1)

ΔPC,t≥2.875×ΔPg,F+0.035···(A2)

ΔPC,t≥2.875×ΔPg,F+0.037···(A3)

ΔPC,t≥2.875×ΔPg,F+0.039···(A4)

ΔPC,t≥2.875×ΔPg,F+0.041···(A5)

(ii) In the optical glass of embodiment 3-1, when Δ Pg, F is-0.0037 or less, it is preferable to satisfy the following formula (B1), and it is more preferable to satisfy the following formula (B2), the following formula (B3), the following formula (B4), and the following formula (B5) in this order.

ΔPC,t≥4.750×ΔPg,F+0.038···(B1)

ΔPC,t≥4.750×ΔPg,F+0.042···(B2)

ΔPC,t≥4.750×ΔPg,F+0.044···(B3)

ΔPC,t≥4.750×ΔPg,F+0.046···(B4)

ΔPC,t≥4.750×ΔPg,F+0.048···(B5)

In the optical glass of embodiment 3-1, the glass characteristics other than those described above may be the same as those of embodiment 1-1.

The optical glass of embodiment 3-1 and the optical element can be manufactured in the same manner as embodiment 1-1.

3 st to 2 nd embodiments

In the oxide optical glass of embodiment 3-2,

Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ and Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ ]Is 6.5 percentIn the above-mentioned manner,

the oxide optical glass is substantially free of Pb and As,

the oxide optical glass satisfies one or more of the following (I) to (IV).

(I)Li ⁺ 、Na ⁺ And K ⁺ To total content of Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]Is 0.85 or less.

(IV)Li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.75 or more, B ³⁺ And Li ⁺ Total content of (D) and Si ⁴⁺ 、Na ⁺ And K ⁺ Of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]Is 0.31 or more.

In the optical glass of embodiment 3-2, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵ ⁺ +W ⁶⁺ +Bi ³⁺ ]Is more than 6.5 percent. The lower limit of the total content is preferably 7%, 7.5%, 8%, 8.5%, and more preferably in this order. The upper limit of the total content is preferably 30%, and more preferably 20%, 15%, 12%, 11.5%, 11%, 10.5%, and 10% in this order. By setting the total content to the above range, a high refractive index and a desired abbe number ν d can be maintained.

In the optical glass of embodiment 3-2, B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]Is 0.41 or more and less than 1. The lower limit of the cation ratio is preferably 0.46, and more preferably 0.50, 0.51, 0.53, 0.55, 0.57 and 0.59 in this order. The upper limit of the cation ratio is preferably 0.90, and more preferably 0.85, 0.80, 0.75, 0.70, and 0.65 in this order. By setting the cation ratio to the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. If the cation ratio is too large, the chemical durability of the glass may be reduced.

In the optical glass of embodiment 3-2, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ² ⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.55 or more. The lower limit of the cation ratio is preferably 0.75, and more preferably 0.80, 0.85, and 0.90 in this order. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96, and 0.94 in this order. When the cation ratio is in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, the meltability of the glass can be improved, and the viscosity of the molten glass can be reduced to improve the moldability. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, the thermal stability of the glass is lowered and the refractive index nd may be lowered.

In the optical glass of embodiment 3-2, zr ⁴⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]Is 0.4 or more. The lower limit of the cation ratio is preferably 0.42, and more preferably 0.44, 0.46, 0.48, and 0.50. The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.65, 0.6, and 0.55. By making the cation ratio in the above range, the relative partial dispersion PC, t in the infrared wavelength region can be improved and the high dispersion property can be maintained.

In the optical glass of the embodiment 3-2, si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³ ⁺ )]Is 8.6 or more. The lower limit of the cation ratio is preferably 8.8, and more preferably 9.0, 9.2, 9.4, 9.6, and 9.8 in this order. The upper limit of the cation ratio is preferably 20, and more preferably 18, 16, 14, 13, 12 and 11 in this order. By setting the cation ratio to the above range, the relative partial dispersion PC, t in the infrared wavelength region can be increased, and the abbe number can be adjusted.

The optical glass of embodiment 3-2 does not substantially contain Pb and As which are components having an environmental burden. That is, the respective contents of Pb ions and As ions are 0%. In addition, like Pb and As, th is also a component having a potential for environmental burden. Therefore, the content of the Th ion is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01%. The content of Th ions is preferably 0%. That is, it is preferable that substantially no Th is contained. The Pb ions are removed from Pb ²⁺ In addition, the compound also contains Pb ions with different valences. The As ion and the Th ion also include ions having different valences.

The optical glass of embodiment 3-2 satisfies one or more of the following (I) to (IV).

(I)Li ⁺ 、Na ⁺ And K ⁺ To total content of Si ⁴⁺ And B ³⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]Is 0.85 or less.

Li ⁺ 、Na ⁺ 、Mg ²⁺ and Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is 0.75 or more.

That is, in the optical glass of embodiment 3-2, the case (I) described above, li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]May be set to 0.85 or less. In the above (I)In this case, the upper limit of the cation ratio may be set to 0.80, 0.75, 0.70, 0.65, 0.60, or 0.55. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving the chemical durability, it is preferable to set the cation ratio to the above range.

In the optical glass of the embodiment 3-2, in the case of the above (II), li ⁺ 、Na ⁺ And K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]May be set to 0.97 or less. In the case of the above (II), the upper limit of the cation ratio may be set to 0.85, 0.80, 0.75, 0.70, 0.65, 0.60 or 0.55. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and improving chemical durability, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-2, in the case of (II) above, li ⁺ 、Na ⁺ 、Mg ²⁺ And Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ² ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]It may be set to 0.75 or more. In the case of the above (II), the lower limit of the cation ratio may be set to 0.77, 0.79, 0.81, 0.83, 0.85, 0.87, or 0.89. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.99, 0.98, and 0.95 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range.

In the optical glass of embodiment 3-2, in the case of (III) above, B ³⁺ With Si ⁴⁺ And B ³⁺ Cation ratio of the total content [ B ] ³⁺ /(Si ⁴⁺ +B ³⁺ )]It may be set to 0.46 or more. In the case of the above (III), the lower limit of the cation ratio may be set to 0.50, 0.51, 0.53, 0.55, 0.57 or 0.59. Further, the cation ratio is preferably less than 1, and the upper limits thereof are more preferably in the order of 0.90, 0.85, 0.80, 0.75, 0.70, 0.65. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. If the cation ratio is too large, the chemical durability of the glass may be reduced.

In the optical glass of embodiment 3-2, in the case of (IV) above, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]It may be set to 0.75 or more. In the case of the above (IV), the lower limit of the cation ratio may be set to 0.80, 0.85 or 0.90. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96, and 0.94 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass is lowered and refractive index nd may be lowered.

In the optical glass of embodiment 3-2, in the case of (IV) above, B ³⁺ And Li ⁺ Total content of (D) and Si ⁴⁺ 、Na ⁺ And K ⁺ The cation ratio of the total content of [ (B) ³⁺ +Li ⁺ )/(Si ⁴⁺ +Na ⁺ +K ⁺ )]It may be set to 0.31 or more. The lower limit of the cation ratio may be set to 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10 or 1.20. The upper limit of the cation ratio is preferably 10, and more preferably 9, 8, 7, 6, 5, 4, 3, 2, and 1.8. The cation ratio is preferably in the above range from the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region.

In the optical glass of embodiment 3-2, t is preferably a relative partial dispersion PC satisfying the following formula [2-1].

PC,t≥0.5661+0.004667×νd···[2-1]

It is more preferable that t satisfies the following formula [2-2] with respect to the partial dispersion PC, and it is further more preferable that t satisfies the following formula [2-3], the following formula [2-4], the following formula [2-5], the following formula [2-6], the following formula [2-7] and the following formula [2-8] in this order.

PC,t≥0.5711+0.004667×νd···[2-2]

PC,t≥0.5731+0.004667×νd···[2-3]

PC,t≥0.5751+0.004667×νd···[2-4]

PC,t≥0.5771+0.004667×νd···[2-5]

PC,t≥0.5791+0.004667×νd···[2-6]

PC,t≥0.5811+0.004667×νd···[2-7]

PC,t≥0.5831+0.004667×νd···[2-8]

In the optical element made of the optical glass of embodiment 3-2, the relative partial dispersion PC, t preferably satisfies the above formula from the viewpoint of satisfactorily compensating for chromatic aberration in a wide wavelength range.

In the optical glass of embodiment 3-2, the content and ratio of the glass components other than those described above may be the same as those of embodiment 1.

In the optical glass of embodiment 3-2, other glass characteristics than those described above may be the same as those of embodiment 3-1.

The production of the optical glass and the production of the optical element and the like according to embodiment 3-2 may be the same as those according to embodiment 3-1.

Embodiments 3 to 3

In the oxide optical glass of the embodiments 3 to 3,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

the oxide optical glass has Δ Pg, F and Δ PC, t satisfying the following (i) or (ii).

The optical glass of the embodiments 3 to 3 contains Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ As a glass component.

In addition, the optical glass of the embodiments 3 to 3 contains Li ⁺ 、Na ⁺ And K ⁺ As a glass component. The optical glass of embodiment 3-2 preferably contains Li ⁺ And Na ⁺ 。

In the optical glass of the embodiment 3-3, Δ Pg, F and Δ PC, t satisfy the following (i) or (ii).

(i) In the optical glass of the embodiment 3 to 3, Δ Pg, F is preferably larger than-0.0037 and more preferably satisfies the following formula (A1), and further satisfies the following formula (A2), the following formula (A3), the following formula (A4), and the following formula (A5) in this order.

ΔPC,t≥2.875×ΔPg,F+0.031···(A1)

ΔPC,t≥2.875×ΔPg,F+0.035···(A2)

ΔPC,t≥2.875×ΔPg,F+0.037···(A3)

ΔPC,t≥2.875×ΔPg,F+0.039···(A4)

ΔPC,t≥2.875×ΔPg,F+0.041···(A5)

(ii) In the optical glass of the embodiment 3 to 3, when Δ Pg, F is-0.0037 or less, it is preferable to satisfy the following formula (B1), and it is more preferable to satisfy the following formula (B2), the following formula (B3), the following formula (B4), and the following formula (B5) in this order.

ΔPC,t≥4.750×ΔPg,F+0.038···(B1)

ΔPC,t≥4.750×ΔPg,F+0.042···(B2)

ΔPC,t≥4.750×ΔPg,F+0.044···(B3)

ΔPC,t≥4.750×ΔPg,F+0.046···(B4)

ΔPC,t≥4.750×ΔPg,F+0.048···(B5)

In the optical glass of the embodiment 3-3, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵ ⁺ +W ⁶⁺ +Bi ³⁺ ]The lower limit of (b) is preferably 6.5%, and more preferably 7%, 7.5%, 8%, and 8.5% in this order. The upper limit of the total content is preferably 30%, and more preferably 20%, 15%, 12%, 11.5%, 11%, 10.5%, and 10% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of the embodiment 3-3, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ² ⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]The lower limit of (b) is preferably 0.55, and more preferably 0.75, 0.80, 0.85, and 0.90 in this order. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96 and 0.94 in this order. The relative partial dispersion PC, t in the infrared wavelength region is increased, the melting property of the glass is improved, and the viscosity of the molten glass is reducedFrom the viewpoint of improving moldability, the cation ratio is preferably in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass may be lowered and refractive index nd may be lowered.

In the optical glass of embodiment 3-3, zr ⁴⁺ Content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The lower limit of (b) is preferably 0.4, and more preferably 0.42, 0.44, 0.46, 0.48, and 0.50 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.65, 0.6, and 0.55. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersion, it is preferable to set the cation ratio in the above range.

In the optical glass of the embodiments 3 to 3, si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Of total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³ ⁺ )]The lower limit of (b) is preferably 8.6, and more preferably 8.8, 9.0, 9.2, 9.4, 9.6 and 9.8 in this order. The upper limit of the cation ratio is preferably 20, and more preferably 18, 16, 14, 13, 12 and 11 in this order. The cation ratio is preferably in the above range from the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and adjusting the abbe number.

The optical glass of embodiment 3 to 3 preferably does not substantially contain Pb and As which are components having an environmental burden. That is, the respective contents of Pb ions and As ions are preferably 0%. In addition, like Pb and As, th is also a component having a potential for environmental burden. Therefore, the content of Th ions is preferably 0 to 0.1%, and may be 0 to 0.05 percent or 0 to 0.01 percent. The content of Th ions is preferably 0%. That is, it is preferable that substantially no Th is contained. The Pb ions are removed from Pb ²⁺ In addition, the compound also contains Pb ions with different valences. The As ion and the Th ion also include ions having different valences, respectively.

In the optical glass of the embodiments 3 to 3, t is preferably a relative partial dispersion PC satisfying the following formula [2-1].

PC,t≥0.5661+0.004667×νd···[2-1]

PC,t≥0.5711+0.004667×νd···[2-2]

PC,t≥0.5731+0.004667×νd···[2-3]

PC,t≥0.5751+0.004667×νd···[2-4]

PC,t≥0.5771+0.004667×νd···[2-5]

PC,t≥0.5791+0.004667×νd···[2-6]

PC,t≥0.5811+0.004667×νd···[2-7]

PC,t≥0.5831+0.004667×νd···[2-8]

In the optical element made of the optical glass of embodiments 3 to 3, the relative partial dispersion PC, t preferably satisfies the above formula from the viewpoint of satisfactorily compensating chromatic aberration in a wide wavelength range.

The optical glass of embodiments 3 to 3 may satisfy one or more of (I) to (IV) described in detail in embodiment 1.

The content and ratio of the glass components other than those described above in the optical glass of embodiment 3 to 3 may be the same as those in embodiment 3 to 1.

In the optical glass of embodiment 3 to 3, other glass characteristics than those described above may be the same as those of embodiment 3 to 1.

The production of the optical glass and the production of the optical element and the like according to embodiments 3 to 3 may be the same as embodiment 1.

Embodiments 3 to 4

In the oxide optical glass of the embodiments 3 to 4,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

And contains Li ⁺ 、Na ⁺ And K ⁺ In (1) the seed-coating agent is prepared by the following steps of,

the oxide optical glass PC, t satisfies the following formula [2-1].

PC,t≥0.5661+0.004667×νd···[2-1]

The optical glass of the embodiments 3 to 4 contains Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ As a glass component.

In addition, the optical glasses of embodiments 3 to 4 contain Li ⁺ 、Na ⁺ And K ⁺ As a glass component. The optical glass of the embodiments 3 to 4 preferably contains Li ⁺ And Na ⁺ 。

In the optical glass of the embodiments 3 to 4, the relative partial dispersion PC, t satisfies the following formula [2-1].

PC,t≥0.5661+0.004667×νd···[2-1]

In the optical glass of the embodiment 3 to 4, t preferably satisfies the following formula [2-2] with respect to the partial dispersion PC, and more preferably satisfies the following formula [2-3], the following formula [2-4], the following formula [2-5], the following formula [2-6], the following formula [2-7] and the following formula [2-8] in this order.

PC,t≥0.5711+0.004667×νd···[2-2]

PC,t≥0.5731+0.004667×νd···[2-3]

PC,t≥0.5751+0.004667×νd···[2-4]

PC,t≥0.5771+0.004667×νd···[2-5]

PC,t≥0.5791+0.004667×νd···[2-6]

PC,t≥0.5811+0.004667×νd···[2-7]

PC,t≥0.5831+0.004667×νd···[2-8]

The calculation method of the relative partial dispersion PC, t is as described in embodiment 3-1. By making the relative partial dispersions PC, t satisfy the above-described formula, the optical element made of the optical glass of embodiments 3 to 4 can excellently compensate for chromatic aberration over a wide wavelength range.

In the optical glasses of the embodiments 3 to 4, the relative partial dispersions Pg, F preferably satisfy the following formula [1-1].

Pg,F≤0.6463-0.001802×νd···[1-1]

In the optical glass of the embodiments 3 to 4, it is more preferable that the relative partial dispersion Pg, F satisfies the following formula [1-2], and it is further more preferable that the following formula [1-3], the following formula [1-4], the following formula [1-5] and the following formula [1-6] are satisfied in this order.

Pg,F≤0.6458-0.001802×νd···[1-2]

Pg,F≤0.6453-0.001802×νd···[1-3]

Pg,F≤0.6448-0.001802×νd···[1-4]

Pg,F≤0.6446-0.001802×νd···[1-5]

Pg,F≤0.6443-0.001802×νd···[1-6]

The relative partial dispersion Pg, F is calculated as described in embodiment 3-1. By making the relative partial dispersions Pg, F satisfy the above formula, the optical element made of the optical glass of embodiments 3 to 4 can compensate for chromatic aberration well over a wide wavelength range.

In the optical glass of the embodiments 3 to 4, nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Total content of [ Nb ] ⁵⁺ +Ti ⁴⁺ +Ta ⁵ ⁺ +W ⁶⁺ +Bi ³⁺ ]The lower limit of (b) is preferably 6.5%, and more preferably 7%, 7.5%, 8%, and 8.5% in this order. The upper limit of the total content is preferably 30%, and more preferably 20%, 15%, 12%, 11.5%, 11%, 10.5%, and 10% in this order. From the viewpoint of maintaining a high refractive index and a desired abbe number ν d, it is preferable to set the total content to the above range.

In the optical glass of the embodiments 3 to 4, li ⁺ 、Na ⁺ And K ⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ² ⁺ 、Ba ²⁺ And Zn ²⁺ Of total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]The lower limit of (b) is preferably 0.55, and more preferably 0.75, 0.80, 0.85, and 0.90 in this order. The upper limit of the cation ratio is preferably 1.00, and more preferably 0.98, 0.96, and 0.94 in this order. From the viewpoint of improving the relative partial dispersion PC, t in the infrared wavelength region, improving the meltability of the glass, and improving the moldability by reducing the viscosity of the molten glass, it is preferable to set the cation ratio in the above range. When the cation ratio is too small, there is a risk that the relative partial dispersion PC and t are lowered. When the cation ratio is too large, thermal stability of the glass may be lowered and refractive index nd may be lowered.

In the optical glass of the embodiments 3-4, zr ⁴⁺ Content of (b) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The lower limit of (b) is preferably 0.4, and more preferably 0.42, 0.44, 0.46, 0.48, and 0.50 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.65, 0.6, and 0.55. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and maintaining high dispersibility, it is preferable to set the cation ratio to the above range.

In the optical glass of the embodiments 3 to 4, si ⁴⁺ 、B ³⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And Zr ⁴⁺ Total content of (B) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Si) ⁴⁺ +B ³⁺ +Li ⁺ +Na ⁺ +K ⁺ +Zr ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³ ⁺ )]The lower limit of (2) is preferably 8.6, orOne step with 8.8, 9.0, 9.2, 9.4 the order of 9.6 and 9.8 is more preferred. The upper limit of the cation ratio is preferably 20, and more preferably 18, 16, 14, 13, 12 and 11 in this order. From the viewpoint of increasing the relative partial dispersion PC, t in the infrared wavelength region and adjusting the abbe number, it is preferable to set the cation ratio to the above range.

The optical glass of embodiments 3 to 4 preferably does not substantially contain Pb and As which are components having an environmental burden. That is, the respective contents of Pb ions and As ions are preferably 0%. In addition, like Pb and As, th is also a component having a potential for environmental burden. Therefore, the content of the Th ion is preferably 0 to 0.1%, and may be 0 to 0.05% or 0 to 0.01%. The content of Th ions is preferably 0%. That is, it is preferable that substantially no Th is contained. The Pb ions are removed from Pb ²⁺ In addition, the compound also contains Pb ions with different valences. The As ion and the Th ion also include ions having different valences, respectively.

The optical glass of embodiment 3 to 4 may satisfy one or more of (I) to (IV) described in detail in embodiment 3 to 1.

The content and ratio of the glass components other than those described above in the optical glass of embodiment 3 to 4 may be the same as those in embodiment 3 to 1.

In the optical glass of embodiment 3 to 4, other glass characteristics than those described above may be the same as those of embodiment 3 to 1.

The production of the optical glass and the production of the optical element and the like according to embodiments 3 to 4 may be the same as those according to embodiment 3 to 1.

Examples

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiment shown in the examples.

(example 1)

Glass samples having glass compositions shown in the table were produced according to the following procedures, and various evaluations were performed.

Here, table 1 shows the glass composition in mass%, and table 2 shows the glass composition in cation%. That is, in tables 1 and 2, although the glass compositions are shown in different ways, the optical glasses having the same sample number refer to the same optical glasses having the same compositions. Thus, tables 1 and 2 show substantially the same optical glasses and the results thereof.

In Table 2, the glass composition is represented by cation%, and all the anionic components are O ^2- . Namely, O in the composition shown in Table 2 ^2- The contents of (A) are all 100 anion%.

In addition, the composition expressed by mass% in table 1 is obtained by converting the composition expressed by cation% in table 2.

[ production of optical glass ]

First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of the glass were prepared as raw materials, and the raw materials were weighed and blended so that the glass compositions of the obtained optical glasses were each as shown in tables 1 and 2, and the raw materials were thoroughly mixed. The prepared raw materials (batch raw materials) are put into a platinum crucible, heated at 1350-1400 ℃ for 2-4 hours to prepare molten glass, stirred to homogenize the molten glass, and the molten glass is poured into a mold preheated to a proper temperature after being clarified. The injected glass was subjected to a heat treatment at a temperature near the glass transition temperature Tg for 30 minutes, and naturally cooled to room temperature in a furnace, thereby obtaining a glass sample.

[ confirmation of glass composition ]

The contents of the respective glass components in the obtained glass samples were measured by inductively coupled plasma emission spectrometry (ICP-AES), and it was confirmed that the compositions shown in tables 1 to 12 were shown.

[ measurement of optical Properties ]

The obtained glass sample was further annealed at around the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a cooling rate of-30 ℃/hour to obtain an annealed sample. The obtained annealed sample was measured for refractive index, abbe number ν d, relative partial dispersion Pg, F, deviation Δ Pg, F, relative partial dispersion PC, t, deviation Δ PC, t, specific gravity, glass transition temperature Tg, liquid phase temperature LT, λ 80, and λ 5. The results are shown in tables 1 to 12.

(i) Refractive indices nd, ng, nF, nC, abbe number vd, relative partial dispersion PC, t and relative partial dispersion Pg, F

For the above annealed sample, the refractive index measurement method by JIS B7071-1 optical glass-part 1: the refractive index at 12 wavelengths shown in Table A was measured by the minimum declination method.

Next, the refractive indices of the spectral lines obtained by the measurement were substituted into the refractive index measurement method for optical glass according to JIS B7071-1 — part 1: in the Schott dispersion formula defined in annex B of the minimum deviation angle method, the constants of the Schott dispersion formula were obtained by the least square method. Then, using a Schott dispersion formula in which constants are determined, an abbe number ν d, relative partial dispersions PC, t, and relative partial dispersions Pg, F are calculated.

[ Table A ]

Wavelength (nm)	Spectral line	Light source
			1013.98	t-ray (Infrared mercury)	Hg
852.11	s-ray (Infrared Cesium)	Cs
			706.52	Gamma ray (Red helium)	He
656.27	C-ray (Red hydrogen)	H
			643.85	C' ray (Red cadmium)	Cd
587.56	d ray (yellow helium)	He
			546.07	e-ray (Green mercury)	Hg
486.13	F ray (blue hydrogen)	H
			479.99	F' ray (blue cadmium)	Cd
435.84	g-ray (blue mercury)	Hg
			404.66	h ray (purple mercury)	Hg
365.01	i-ray (ultraviolet mercury)	Hg

Schott dispersion formula: n is a radical of an alkyl radical ² ＝a ₀ +a ₁ λ ² +a ₂ λ ^-2 +a ₃ λ ^-4 +a ₄ λ ^-6 +a ₅ λ ^-8

Wherein n 12399 ₀ 、a ₁ 、a ₂ 、a ₃ 、a ₄ 、a ₅ Is a constant.

The refractive index nd is a refractive index at a wavelength of 587.56 nm.

νd＝(nd-1)/(nF-nC)

The relative partial dispersion PC, t is expressed by the refractive indices nt, nF, nC for t-rays, F-rays, and C-rays, as follows.

PC,t＝(nC-nt)/(nF-nC)

Pg,F＝(ng-nF)/(nF-nC)

(ii) Deviation Δ PC, t, deviation Δ Pg, F

In a plane in which the abbe number ν d is represented by the horizontal axis and the relative partial dispersion PC, t is represented by the vertical axis, the normal PC, t (0) is represented by the following formula.

PC,t(0)＝0.5461-(0.004667×νd)

The deviation Δ PC, t of the relative partial dispersion PC, t from the normal is calculated based on the following equation.

ΔPC,t＝PC,t-PC,t(0)

In a plane in which the abbe number ν d is represented by the horizontal axis and the relative partial dispersion Pg, F is represented by the vertical axis, the normal Pg, F (0) is represented by the following formula.

Pg,F(0)＝0.6483-(0.001802×νd)

The deviation Δ Pg, F of the relative partial dispersion Pg, F from the normal is calculated based on the following equation.

ΔPg,F＝Pg,F-Pg,F(0)

(iii) Specific gravity of

The specific gravity was measured by the archimedes method.

(iv) Glass transition temperature Tg

The glass transition temperature Tg was measured at a temperature increase rate of 10 ℃ per minute using a differential scanning calorimetry analyzer (DSC 3300 SA) manufactured by NETZSCH JAPAN.

(v) Liquid phase temperature LT

The glass was placed in a furnace heated to a predetermined temperature, held for about 2 hours, cooled, and then the inside of the glass was observed with an optical microscope of 40 to 100 times, and the liquid phase temperature was measured depending on the presence or absence of crystallization.

(vi)λ80、λ5

The above annealed sample was processed to have a thickness of 10mm and to have mutually parallel and optically polished planes, and the spectral transmittance in the wavelength region from 280nm to 700nm was measured. The spectral transmittance B/a was calculated by setting the intensity of light perpendicularly incident to 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 reaches 80% is defined as λ 80, and the wavelength at which the spectral transmittance reaches 5% is defined as λ 5. The spectral transmittance also includes a light reflection loss on the surface of the sample.

[ chemical durability Water resistance Dw ]

The obtained glass sample was made into powder glass (particle size: 425 to 600 μm), and the powder glass having a mass equivalent to the specific gravity was put in a platinum cage, immersed in a 80mL round-bottomed flask made of quartz glass containing pure water (pH =6.5 to 7.5), and treated in a boiling water bath for 60 minutes. The samples were classified and evaluated according to the grade shown in Table B based on the mass reduction ratio (%).

[ Table B ]

[ chemical durability acid resistance Da ]

The obtained glass sample was made into powder glass (particle size: 425 to 600 μm), and the powder glass having a mass equivalent to the specific gravity was placed in a platinum cage, and the powder glass was immersed in a quartz glass round-bottomed flask containing 80mL of a 0.01mol/L nitric acid aqueous solution, and treated for 60 minutes. The samples were classified and evaluated according to the grade shown in Table C based on the mass reduction ratio (%).

[ Table C ]

Grade	Mass loss (%)
		1	Less than 0.20 percent
2	More than 0.20 percent and less than 0.35 percent
		3	More than 0.35 percent and less than 0.65 percent
4	More than 0.65% and less than 1.20%
		5	More than 1.20 percent and less than 2.20 percent
6	More than 2.20 percent

[ chemical durability scratch resistance D _NaOH ]

The resulting glass sample was processed to a diameter of 43.7mm (30 cm on both sides) ² ) And a size of about 5mm in thickness. The resulting material was immersed in a 0.01mol/L NaOH aqueous solution at 50 ℃ for 15 hours while being sufficiently stirred, and the mass per unit area was decreased by [ mg/(cm) ] ² ·15h)]The samples were classified and evaluated according to the ranks in Table D.

[ Table D ]

Grade	Mass loss [ mg/(cm) ² ·15h)]
		1	Less than 0.02
2	0.02 or more and less than 0.10
		3	0.10 or more and less than 0.20
4	0.20 or more and less than 0.30
		5	0.30 or more

[ chemical durability scratch resistance D _STPP ]

The resulting glass sample was processed to a diameter of 43.7mm (30 cm on both sides) ² ) And a size of about 5mm in thickness. Subjecting the mixture to a sufficient stirring of 0.01mol/L Na at 50 DEG C ₅ P ₃ O ₁₀ (STPP) in an aqueous solution for 1 hour, at which time the mass per unit area decreased by [ mg/(cm) ² ·h)]The samples were classified and evaluated according to the grades in Table E.

[ Table E ]

Grade	Mass reduction [ mg/(cm) ² ·h)]
		1	Less than 0.02
2	0.02 or more and less than 0.20
		3	0.20 or more and less than 0.40
4	0.40 or more and less than 0.60
		5	0.60 or more

Chemical durability D ₀ ]

The resulting glass sample was processed to a diameter of 43.7mm (30 cm on both sides) ² ) And a size of about 5mm in thickness. When the resin was immersed in pure water, which was maintained at 50 ℃ and pH =7.0 ± 0.2 by circulating the resin through the layer of ion exchange resin at a rate of 1L per minute and sufficiently stirred, the mass per unit area decreased [ 10% ^-3 mg/(cm ² ·h)]According to the tableAnd F grade is classified and evaluated.

[ Table F ]

(example 2)

Using each of the optical glasses produced in example 1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as polishing to produce various lenses.

The optical lens is various lenses such as a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, a concave meniscus lens, a convex meniscus lens, and the like.

Various lenses can well compensate for high-order chromatic aberration in the infrared region by combining with a lens made of low-dispersion glass having an abbe number of 65 or more, for example, fluorophosphate glass.

Further, since glass has a low specific gravity, each lens has a smaller weight than a lens having the same optical characteristics and size, and is suitable for various imaging apparatus applications, particularly for the reason of energy saving, etc., an autofocus type imaging apparatus application is suitable. Similarly, prisms were produced using various optical glasses produced in example 1.

It should be understood that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

For example, the optical glass according to one embodiment of the present invention can be produced by adjusting the composition described in the specification with respect to the glass composition exemplified above.

It is needless to say that two or more items described as examples or preferable ranges in the specification may be arbitrarily combined.

Claims

1. An optical glass, wherein,

SiO ₂ the content of (B) is 20% by mass or more,

B ₂ O ₃ the content of (B) is 15 mass% or more,

ZrO ₂ the content of (B) is 5% by mass or more,

Nb ₂ O ₅ the content of (B) exceeds 5 mass%,

Li ₂ O、Na ₂ o and K ₂ Total content R of O ₂ The sum of O and the total content R' O of MgO, caO, srO, baO and ZnO, and SiO ₂ And B ₂ O ₃ (ii) mass ratio of total content [ (R) ₂ O+R’O)/(SiO ₂ +B ₂ O ₃ )]Is a content of not more than 0.36,

B ₂ O ₃ and ZrO ₂ 、Nb ₂ O ₅ 、TiO ₂ 、WO ₃ 、Bi ₂ O ₃ And Ta ₂ O ₅ The mass ratio of the total content of [ B ] ₂ O ₃ /(ZrO ₂ +Nb ₂ O ₅ +TiO ₂ +WO ₃ +Bi ₂ O ₃ +Ta ₂ O ₅ )]Is a content of at least 0.74,

the optical glass contains substantially no Pb.

2. An optical glass, wherein,

as a component of the glass, a glass,

containing SiO ₂ 、B ₂ O ₃ 、ZrO ₂ And Nb ₂ O ₅ ，

the optical glass has a Δ PC, t of 0.0250 or more.

3. An optical glass, wherein,

Si ⁴⁺ the content of (A) is more than 10 cation percent,

B ³⁺ the content of (A) is more than 20 cation percent,

Si ⁴⁺ and B ³⁺ Total content of [ Si ] ⁴⁺ +B ³⁺ ]Is more than 50 percent of cation, and the cation,

Nb ⁵⁺ the content of (A) is more than 0 cation% and 11.5 cation% or less,

the optical glass satisfies one or more of the following (i) and (ii):

(i)Zr ⁴⁺ the content of (D) and the total content of R' and Nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ 、Bi ³⁺ And Ta ⁵⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ +Ta ⁵⁺ )]Is a content of at least 0.17,

4. The optical glass according to claim 3,

Zr ⁴⁺ and Ta ⁵⁺ The total content of (A) is 8.5 cation% or less.

5. The optical glass according to claim 3 or 4,

Zr ⁴⁺ and Ta ⁵⁺ Total content of (A) and R', nb ⁵⁺ 、Ti ⁴⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of the total content of [ (Zr) ⁴⁺ +Ta ⁵⁺ )/(R’+Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ )]Is less than 3.10, and R' is Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ The total content of (a).

6. An optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

the optical glass has a Δ PC, t of 0.0250 or more.

7. An oxide optical glass, wherein,

Zr ⁴⁺ content of (2) and Nb ⁵⁺ 、Ti ⁴⁺ 、Ta ⁵⁺ 、W ⁶⁺ And Bi ³⁺ Cation ratio of total content [ Zr ] ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )]The content of the acid-resistant agent is more than 0.4,

the oxide optical glass is substantially free of Pb and As,

the PC, t of the oxide optical glass satisfies the following formula [2-2]:

PC,t≥0.5711+0.004667×νd···[2-2]，

the oxide optical glass satisfies one or more of the following (I) to (IV):

Li ⁺ 、Na ⁺ 、Mg ²⁺ and Ca ²⁺ Total content of (2) and Li ⁺ 、Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ And Zn ²⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +Mg ²⁺ +Ca ²⁺ )/(Li ⁺ +Na ⁺ +K ⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ )]Is not less than 0.75 of the total weight of the composition,

8. An oxide optical glass, wherein,

the oxide optical glass is substantially free of Pb and As,

the oxide optical glass satisfies one or more of the following (I) to (IV):

(I)Li ⁺ 、Na ⁺ and K ⁺ Total content of (a) with Si ⁴⁺ And B ³⁺ Cation ratio of the total content of [ (Li) ⁺ +Na ⁺ +K ⁺ )/(Si ⁴⁺ +B ³⁺ )]The content of the acid-resistant acrylic resin is less than 0.85,

9. An oxide optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

Δ Pg, F and Δ PC, t of the oxide optical glass satisfy the following (i) or (ii):

(i) When the delta Pg and the F are more than-0.0037, the delta PC and t are more than or equal to 2.875 multiplied by the delta Pg and F +0.031,

10. An oxide optical glass, wherein,

as a component of the glass, a glass,

containing Si ⁴⁺ 、B ³⁺ 、Zr ⁴⁺ And Nb ⁵⁺ ，

PC, t of the oxide optical glass satisfies the following formula [2-1]:

PC,t≥0.5661+0.004667×νd···[2-1]。

11. the oxide optical glass according to claim 10, wherein Pg, F satisfy the following formula [1-1]:

Pg,F≤0.6463-0.001802×νd···[1-1]。

12. the optical glass according to any one of claims 7 to 11,

13. An optical element made of the optical glass according to any one of claims 1 to 12.