CN110691760A

CN110691760A - Glass, optical glass and optical element

Info

Publication number: CN110691760A
Application number: CN201880035996.6A
Authority: CN
Inventors: 根岸智明; 庄司昂浩; 福井聪史; 桑谷俊伍; 佐佐木勇人
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2017-06-02
Filing date: 2018-05-31
Publication date: 2020-01-14
Also published as: CN117945649A; CN117945646A; JP7226927B2; JP2019104671A; CN117945647A; CN117945648A

Abstract

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

Description

Glass, optical glass and optical element

Technical Field

The invention relates to glass, optical glass and optical element.

In designing an optical system, an optical glass having a high refractive index and a high dispersibility corrects chromatic aberration, and has a high utility value in terms of high functionality and compactness of the optical system.

Such glass is described below in accordance with the embodiments of the invention 1, the invention 2, the invention 3 and the invention 4.

In the present invention and the present specification, unless otherwise specified, the glass composition is expressed on an oxide basis. Here, the "oxide-based glass composition" refers to a glass composition obtained by converting all glass raw materials into substances existing in the form of oxides in glass through decomposition at the time of melting, and the expression of each glass component is conventionally described as SiO₂、TiO₂And the like. Unless otherwise specified, "%" means "% by mass" with respect to the content and total content of glass components.

The content of the glass component can be determined 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 and the present invention, the content of the constituent component of 0% means that the constituent component is not substantially contained, and the content of the constituent component is allowed to be at an inevitable impurity level.

In the present specification, unless otherwise specified, the refractive index is a refractive index nd of helium with respect to d-rays (wavelength 587.56 nm).

The abbe number ν d is used as a value representing a property related to dispersion, and is represented by the following formula. Here, nF is the refractive index of blue hydrogen at F-ray (wavelength 486.13nm), and nC is the refractive index of red hydrogen at C-ray (656.27 nm).

νd＝(nd-1)/(nF-nC)

Invention 1

[ background of the invention 1]

As a method for producing an optical glass used in an optical system, there is a reheat press method in which a glass is reheated and formed. In this method, in the case of silicate optical glass having a high refractive index and high dispersibility, phase separation is likely to occur during reheating. If phase separation occurs, the fluidity of the glass during reheating is deteriorated, and it may be difficult to form the glass into a desired shape. In addition, this phase separation causes internal defects (for example, bright spots, cracks, streaks, and the like in reflected light) in optical elements such as lenses. Therefore, in the reheat press method, there is a demand for a silicate-based optical glass having a high refractive index and a high dispersibility, which can be formed into a desired shape, i.e., a desired shape with good reheat press formability, while suppressing the occurrence of internal defects.

In designing the optical system, two kinds of glasses having different abbe numbers may be combined for primary chromatic aberration correction. The glass used for the second-order chromatic aberration correction is selected in consideration of relative partial dispersion in addition to the abbe number. In particular, optical glasses having a high refractive index and high dispersibility are suitable for second-order chromatic aberration correction with respect to optical glasses having a small relative partial dispersion.

Patent documents 1-1 to 1-5 disclose silicate-based optical glasses having a high refractive index and a high dispersibility. However, from the viewpoint of abbe number and relative partial dispersion, further improvement in the correction of chromatic aberration in the second order is required for any glass.

[ Prior Art document of the invention 1]

Patent document

Patent documents 1 to 1: japanese patent laid-open No. 2001 and 342035

Patent documents 1 to 2: japanese patent laid-open publication No. 2012-206894

Patent documents 1 to 3: japanese patent laid-open No. 2014-201476

Patent documents 1 to 4: japanese laid-open patent publication No. 60-21828

Patent documents 1 to 5: japanese laid-open patent publication No. 59-8637

[ summary of the invention 1]

[ problem to be solved by invention 1]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a glass, an optical glass, and an optical element which have good reheat press formability and are suitable for secondary chromatic aberration correction.

[ means for solving problems ]

The gist of the invention 1 is as follows.

[1] A silicate glass having an Abbe number ν d of 20 to 35,

containing P₂O₅And Nb₂O₅，

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

Pg,F≤-0.00286×νd+0.68900···(1-1)。

[2] a silicate glass having an Abbe number ν d of 20 to 35,

containing P₂O₅And Nb₂O₅，

And Nb₂O₅Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Greater than 0.6110.

[3] An optical glass formed from the glass according to [1] or [2 ].

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

[ Effect of the invention 1]

According to the invention 1, there can be provided a glass, an optical glass and an optical element which have excellent reheat press formability and are suitable for secondary chromatic aberration correction.

[ embodiment of the invention 1]

The glass of embodiment 1 will be described in detail below. First, as embodiment 1-1, a glass will be described from the viewpoint of relative partial dispersion Pg, F, and next, as embodiment 1-2, a glass will be described from the viewpoint of mass ratio of glass components. Further, as another embodiment, embodiment a, embodiment B, and embodiment C will be described.

1 st embodiment

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

containing P₂O₅And Nb₂O₅，

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

Pg,F≤-0.00286×νd+0.68900···(1-1)。

the glass of embodiment 1-1 is mainly composed of SiO₂Silicate glass as a network forming component of the glass. SiO 2₂The content of (b) is preferably more than 0%, and the lower limit thereof is more preferably 1%, 5%, 10%, 15%, 20%, 25% in this order. In addition, SiO₂The upper limit of the content of (b) is preferably 60%, and more preferably 50%, 40%, 39%, 38%, 37%, 36%, 35% in this order.

SiO₂The network forming component of the glass has the effects of improving the thermal stability, chemical durability and weather resistance of the glass, increasing the viscosity of the molten glass, and facilitating the molding of the molten glass. On the other hand, SiO₂When the amount of (b) is large, devitrification resistance of the glass tends to be lowered, and Pg and F tend to be increased. Therefore, SiO is preferably used₂The content of (b) is in the above range.

The glass of embodiment 1-1 contains P₂O₅。P₂O₅The lower limit of the content of (b) is preferably 0.1%, and more preferably 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, and 1.9% in this order. In addition, P₂O₅The upper limit of the content of (b) is preferably 10%, and more preferably 7%, 5%, and 3% in this order.

By making P₂O₅The lower limit of the content (b) satisfies the above range, and the reheat press formability can be improved. In addition, by making P₂O₅In an amount ofWhen the upper limit of the dispersion is within the above range, the increase of the relative partial dispersions Pg and F can be suppressed, the thermal stability of the glass can be maintained, and the hot press formability can be improved.

The glass of embodiment 1-1 contains Nb₂O₅。Nb₂O₅The lower limit of the content of (b) may be 1%, and further, may be 10%, 20%, 24%, 25%, 30%, 35%, 40%, or 43%. In addition, Nb₂O₅The upper limit of the content of (b) is preferably 80%, and more preferably 60%, 55%, 50%, and 45% in this order.

By making Nb₂O₅The lower limit of the content of (B) satisfies the above range, and a glass having a reduced relative partial dispersion Pg, F, a high refractive index and a high dispersibility can be obtained. In addition, Nb₂O₅And also a glass component for improving the thermal stability and chemical durability of the glass. Therefore, by using Nb₂O₅The upper limit of the content (b) satisfies the above range, and the glass can be improved in reheat press formability while maintaining good thermal stability and chemical durability.

In the glass of embodiment 1-1, Abbe number vd is 20 to 35. The Abbe number ν d may be 22 to 33, or 23 to 31, or 23 to 27, or 23 to 26.

When the abbe number ν d is in the above range, a glass having high dispersibility can be obtained.

The Abbe number ν d can be adjusted by adjusting Nb as a glass component contributing to high dispersion₂O₅、TiO₂、WO₃And Bi₂O₃The content of (c) is controlled.

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

Pg,F≤-0.00286×νd+0.68900···(1-2)

Pg,F≤-0.00286×νd+0.68800···(1-3)

Pg,F≤-0.00286×νd+0.68600···(1-4)

Pg,F≤-0.00286×νd+0.68400···(1-5)

For the partial dispersion Pg, F can be expressed by the following formulas (1 to 6) using the refractive indices ng, nF, nC for g-rays, F-rays, and C-rays.

Pg,F＝(ng-nF)/(nF-nC)···(1-6)

Relative to the partial dispersions Pg, F by adjusting the mass ratio [ (Li) to be described later₂O+Na₂O+K₂O+Cs₂O)/(SiO₂+P₂O₅+B₂O₃)]Mass ratio of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ P ]₂O₅/(SiO₂+P₂O₅+B₂O₃)]Mass ratio of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The mass ratio of [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]To control.

(glass component)

The contents and ratios of the glass components other than those described above in embodiment 1-1 of invention 1 are described in detail below.

In the glass of embodiment 1-1, B₂O₃The content of (b) is preferably 20% or less, and more preferably 10% or less, 5% or less, 3% or less, and 1% or less in this order. B is₂O₃The content of (B) may be 0%.

B₂O₃Is a network forming component of the glass, and has the function of improving the thermal stability of the glass. On the other hand, B₂O₃When the content of (A) is large, there is a glass component at the time of melting the glassThe volatile amount of (b) increases. In addition, the dispersion tends to be inhibited from increasing, and resistance to devitrification tends to be reduced. Thus, B₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Al₂O₃The content of (b) is preferably 20% or less, and more preferably 10% or less, 5% or less, and 3% or less in this order. Al (Al)₂O₃The content of (B) may be 0%.

Al₂O₃The glass component is a glass component having an effect of improving the chemical durability and weather resistance of the glass, and can be considered as a network-forming component. On the other hand, Al₂O₃When the content (c) is increased, the devitrification resistance of the glass is lowered. In addition, problems such as an increase in glass transition temperature Tg and a decrease in thermal stability tend to occur. From the viewpoint of avoiding such a problem, Al₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, SiO₂And P₂O₅Total content of [ SiO ]₂+P₂O₅]The lower limit of (b) is preferably 5%, and more preferably 10%, 15%, 17%, 19%, 21% in this order. In addition, total content [ SiO₂+P₂O₅]The upper limit of (b) is preferably 50%, and more preferably 40%, 37%, 35%, 33%, 31%, 29%, 27% in this order.

By making SiO₂And P₂O₅Total content of [ SiO ]₂+P₂O₅]The lower limit of (2) satisfies the above conditions, and the reheat press formability can be improved. In addition, by making the total content [ SiO ]₂+P₂O₅]Satisfies the above conditions, the relative partial dispersion Pg, F can be suppressed from increasing, and the thermal stability of the glass can be maintained.

In the glass of embodiment 1-1, SiO₂、P₂O₅And B₂O₃Total content of [ SiO ]₂+P₂O₅+B₂O₃]The lower limit of (b) is preferably 5%, and more preferably 10%, 15%, 17%, 19%, 21% in this order. In addition, it is alwaysContent [ SiO ]₂+P₂O₅+B₂O₃]The upper limit of (b) is preferably 50%, and more preferably 40%, 37%, 35%, 33%, 31%, 29%, 27% in this order.

SiO₂、P₂O₅And B₂O₃Is a network forming component of the glass, and mainly improves the thermal stability and devitrification resistance of the glass. Has the effect of increasing the viscosity of the molten glass and facilitating the molding of the molten glass. Thus, SiO₂、P₂O₅And B₂O₃The total content of (b) is preferably in the above range.

Further, in the glass of embodiment 1-1, P₂O₅In a content relative to SiO₂And P₂O₅The mass ratio of the total content of [ P ]₂O₅/(SiO₂+P₂O₅)]The lower limit of (b) is preferably 0.001, and more preferably 0.005, 0.010, 0.020, 0.030, 0.040, 0.050, 0.060, and 0.070 in this order. In addition, mass ratio [ P ]₂O₅/(SiO₂+P₂O₅)]The upper limit of (b) is preferably 0.910, and more preferably 0.700, 0.500, 0.300, 0.200, 0.150, and 0.100 in this order.

P₂O₅In a content relative to SiO₂And P₂O₅The mass ratio of the total content of [ P ]₂O₅/(SiO₂+P₂O₅)]When the dispersion is too low, the hot-press formability is deteriorated, and when the dispersion is too high, the relative partial dispersions Pg and F are increased. Thus, mass ratio [ P₂O₅/(SiO₂+P₂O₅)]Preferably within the above range.

Furthermore, in the glass of the embodiment 1-1, P₂O₅In a content relative to SiO₂、P₂O₅And B₂O₃The mass ratio of the total content of [ P ]₂O₅/(SiO₂+P₂O₅+B₂O₃)]The lower limit of (b) is preferably 0.001, and more preferably 0.005, 0.010, 0.020, 0.030.0.040, 0.050, 0.060, and 0.070 in this order. In addition, mass ratio [ P ]₂O₅/(SiO₂+P₂O₅+B₂O₃)]The upper limit of (b) is preferably 0.910, and more preferably 0.700, 0.500, 0.300, 0.200, 0.150, and 0.100 in this order.

Furthermore, in the glass of embodiment 1-1, SiO₂In a content relative to SiO₂、P₂O₅And B₂O₃Mass ratio of the total content of [ SiO ]₂/(SiO₂+P₂O₅+B₂O₃)]The lower limit of (b) is preferably 0.100, and more preferably 0.300, 0.500, 0.600, 0.700 and 0.800 in this order. In addition, mass ratio [ SiO ]₂/(SiO₂+P₂O₅+B₂O₃)]The upper limit of (b) is preferably 1.000, and more preferably 0.999, 0.990, 0.980, 0.970, 0.960, 0.950, 0.940, 0.930 in this order.

In the glass of embodiment 1-1, ZrO₂The lower limit of the content of (b) is preferably 0%, more preferably more than 0%, and further more preferably 1%, 2%, 3%, 4%, 5%, 6% in this order. In addition, ZrO₂The upper limit of the content of (b) is preferably 15%, and more preferably 13%, 11%, 10%, 9%, and 8% in this order.

By making ZrO₂The lower limit of the content (C) satisfies the above range, and a glass having a high refractive index and a high dispersibility can be obtained. In addition, by using ZrO₂The upper limit of the content of (b) satisfies the above range, and the glass can maintain the meltability and thermal stability in addition to the reduction of relative partial dispersions Pg and F and the suppression of the occurrence of defects as an optical element.

In the glass of embodiment 1-1, TiO₂The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in this order. In addition, TiO₂The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 13%, 11%, 9%, 7%, 6%, and 5% in this order.

TiO₂Is a component contributing to high dispersion, improves glass stability, and improves reheat press formability. On the other hand, excessive introduction of TiO₂Relative partial dispersion Pg, FAnd (4) rising. Thus, TiO₂The content of (b) is preferably in the above range. Note that TiO is₂And Nb₂O₅Can be mutually replaced if replaced by Nb₂O₅The relative partial dispersion Pg, F can be reduced.

In the glass of embodiment 1-1, Nb₂O₅And TiO₂Total content of [ Nb ]₂O₅+TiO₂]The lower limit of (b) may be 10%, and further may be 20%, 25%, 30%, 35%, 40%, or 45%. In addition, the total content [ Nb ]₂O₅+TiO₂]The upper limit of (b) is preferably 80%, and more preferably 70%, 65%, 60%, and 55% in this order.

Nb₂O₅And TiO₂Is a component contributing to high dispersion of high refractive index. Therefore, in order to obtain a glass having a desired abbe number ν d, Nb is preferable₂O₅And TiO₂The total content of (a) is within the above range.

In the glass of embodiment 1-1, P₂O₅Relative to the content of Nb₂O₅Mass ratio of contents of [ P ]₂O₅/Nb₂O₅]The lower limit of (b) is preferably 0.001, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, and 0.040 in this order. In addition, mass ratio [ P ]₂O₅/Nb₂O₅]The upper limit of (b) is preferably 0.125, and more preferably 0.120, 0.100, 0.090, 0.080, 0.070, 0.060, and 0.050 in this order.

Nb₂O₅Is a component contributing to high dispersion, but tends to deteriorate the hot-press formability. On the other hand, P₂O₅The hot-formability can be improved. Therefore, the mass ratio [ P ] is preferred from the viewpoint of the reheat press formability₂O₅/Nb₂O₅]Within the above range.

In the glass of embodiment 1-1, P₂O₅Relative to the content of Nb₂O₅And TiO₂The mass ratio of the total content of [ P ]₂O₅/(Nb₂O₅+TiO₂)]The lower limit of (b) is preferably 0.001, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035 in this order. In addition, mass ratio [ P ]₂O₅/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 0.125, and more preferably 0.120, 0.100, 0.090, 0.080, 0.070, 0.060, and 0.050 in this order.

Nb₂O₅And TiO₂Is a component contributing to high dispersion, but tends to deteriorate the hot-press formability. On the other hand, P₂O₅The hot-formability can be improved. Therefore, the mass ratio [ P ] is considered from the viewpoint of the reheat press formability₂O₅/(Nb₂O₅+TiO₂)]Preferably within the above range.

In the glass of the embodiment 1-1, WO₃The lower limit of the content of (b) is preferably 0%, and may be 1%, 3%, or 5%. In addition, WO₃The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 10%, and 5% in this order.

WO₃Is a component for improving the glass stability and the reheat press formability. On the other hand, WO₃The relative partial dispersions Pg and F are increased to increase the specific gravity. In addition, the coloring of the glass is likely to cause deterioration of the transmittance. Thus, WO₃The content of (b) is preferably in the above range.

In embodiment 1-1, Bi₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, Bi₂O₃The lower limit of the content of (b) is preferably 0%.

Bi₂O₃Has the effect of improving the thermal stability of the glass by containing the glass in a proper amount. On the other hand, if Bi is increased₂O₃The content of (b) increases F and specific gravity relative to the partial dispersion Pg. In addition, the coloring of the glass increases. Thus, Bi₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Nb₂O₅、TiO₂、WO₃And Bi₂O₃Total content of [ Nb ]₂O₅+TiO₂+WO₃+Bi₂O₃]The upper limit of (b) may be 80%, and further may be 70%, 60%, or 55%. In addition, the total content [ Nb ]₂O₅+TiO₂+WO₃+Bi₂O₃]The lower limit of (b) may be 10%, and further may be 20%, 25%, 30%, 35%, 40%, or 45%.

TiO₂、WO₃And Bi₂O₃Is a reaction with Nb₂O₅And components contributing to increase in refractive index and dispersion. Thus, total content [ Nb₂O₅+TiO₂+WO₃+Bi₂O₃]Preferably within the above range.

In the glass of embodiment 1-1, Nb is added to the glass in order to obtain the desired relative partial dispersion Pg, F₂O₅Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (d) is preferably 1.000, but may be set to 0.990, 0.970, 0.950, 0.930, or 0.910. Mass ratio [ Nb₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.100, and more preferably 0.200, 0.300, 0.400, 0.500, 0.600, 0.6110, 0.700, 0.800, 0.855, in that order.

Further, in the glass of embodiment 1-1, ZrO₂Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) is preferably 1.000, and more preferably 0.800, 0.600, 0.400, 0.300, 0.250 and 0.200 in this order. In addition, mass ratio [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0, and more preferably 0.001, 0.005, 0.007 and 0.010 in this order.

Furthermore, in the glass of embodiment 1-1, SiO₂、P₂O₅And B₂O₃Relative to the total content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ (SiO ]₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) may be 5.000, and may be 3.000, 2.000, 1.500, 1.000, or 0.900. In addition, mass ratio [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) may be 0.013, or may be 0.100, 0.200, 0.300, 0.350, or 0.400.

By mixing the mass ratio of [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The Abbe number ν d and the relative partial dispersions Pg and F can be controlled within the above ranges.

In the glass of embodiment 1-1, Li₂The upper limit of the content of O may be 10%, and further may be 9%, 7%, 5%, or 3%. Li₂The lower limit of the content of O may be 0%, and further may be 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, or 4.0%.

In the glass of embodiment 1-1, Na₂The upper limit of the content of O may be 30%, and further, may be 20%, 15%, 10%, 8%, 6%, 5%, or 4%. Na (Na)₂The lower limit of the content of O may be 0%, and further may be 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 7.0%, 9.0%, 11.0%, or 12.0%.

In the glass of embodiment 1-1, K₂The upper limit of the content of O may be 30%, and further, the upper limit may be setMay be set to 25%, 20%, 17%, 15%, 13%, 11%, 9%, 7%, 5%, 3%, or 1%. K₂The lower limit of the content of O may be 0%, and further may be 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, 5.0%, 7.0%, 9.0%, 11.0%, or 13.0%.

Li₂O、Na₂O and K₂All of O has the effect of lowering the liquidus temperature and improving the thermal stability of the glass, but when the content thereof is increased, the chemical durability and weather resistance are lowered. Thus, Li₂O、Na₂O and K₂The respective contents of O are preferably within the above ranges.

In addition, in the glass of the embodiment 1-1, Li₂Content of O relative to Li₂O、Na₂O and K₂Mass ratio of total content of O [ Li ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (d) may be set to 1.000, and may be set to 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. In addition, mass ratio [ Li₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) may be 0.000, and may be 0.100, 0.200, 0.300, 0.500, or 0.700.

Further, in the glass of embodiment 1-1, Na₂Content of O relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (b) may be set to 1.000, and further may be set to 0.970, 0.960, 0.950, 0.900, 0.850, 0.800, 0.750, 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. In addition, mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) may be 0.000, and further may be 0.100, 0.200, 0.300, 0.330, 0.340, 0.350, 0.360, 0.370, 0.450, 0.460, 0.470, 0.480, 0.490, 0.500, or 0.700.

Furthermore, in the glass of the embodiment 1-1, K₂Content of O relative to Li₂O、Na₂O and K₂Mass ratio of total content of O [ K ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit may be set to 1.000, and may be set to 0.700, 0.500, 0.300, 0.200, 0.100, or 0.000. Mass ratio [ K ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) may be 0.000, and may be 0.100, 0.200, 0.300, 0.500, or 0.700.

In the glass of the embodiment 1-1, Cs₂The upper limit of the content of O is preferably 10%, and more preferably 5%, 3%, and 1% in this order. Cs₂The lower limit of the content of O is preferably 0%.

Cs₂O has an effect of improving the thermal stability of the glass, but when the content thereof is increased, the chemical durability and weather resistance are lowered. Thus, Cs₂The respective contents of O are preferably in the above ranges.

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

The alkali metal oxide is preferably selected from Li₂O、Na₂O、K₂O and Cs₂More than 1 oxide of O. In addition, the alkali metals may be replaced, respectively.

When the lower limit of the total content of the alkali metal oxide satisfies the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature can be lowered. In addition, by making the upper limit of the total content of the alkali metal oxide satisfy the above range, the occurrence of defects as an optical element can be suppressed.

In addition, in the glass of the embodiment 1-1, Li₂O、Na₂O and K₂Total content of O [ Li₂O+Na₂O+K₂O]The lower limit of (b) is preferably 1%, more preferably more than 1.1%, and further more preferably 3%, 5%, 7%, 9%, 10%, 11%, 13%, 15% in this order. In addition, total content [ Li₂O+Na₂O+K₂O]The upper limit of (b) is preferably 40%, and more preferably 35%, 30%, 25%, 22.0%, 21.7%, 21%.The order of 4%, 21.1%, 20% is more preferred.

Further, in the glass of the embodiment 1-1, P₂O₅Relative to Li₂O、Na₂O、K₂O、Cs₂O、Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ P ]₂O₅/(Li₂O+Na₂O+K₂O+Cs₂O+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) is preferably 1.000, and more preferably 0.500, 0.300, and 0.100 in this order. In addition, mass ratio [ P ]₂O₅/(Li₂O+Na₂O+K₂O+Cs₂O+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.001, and more preferably 0.003, 0.005, 0.007, 0.009, 0.011, 0.013, 0.015, 0.017, 0.019, and 0.021 in this order.

By appropriate introduction of Li₂O、Na₂O、K₂O、Cs₂O、Nb₂O₅、TiO₂、WO₃And Bi₂O₃As the glass component, a desired Abbe number ν d and relative partial dispersions Pg, F can be obtained. However, if these components are introduced into silicate glass, there is a possibility that the reheat press formability is deteriorated. On the other hand, P₂O₅Is a component for improving the hot-formability. Thus, mass ratio [ P₂O₅/(Li₂O+Na₂O+K₂O+Cs₂O+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]If the dispersion is too high, the stability of the glass may be deteriorated, and the relative partial dispersion Pg and F may be increased. Therefore, the mass ratio [ P ] is preferably set₂O₅/(Li₂O+Na₂O+K₂O+Cs₂O+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Within the above range.

And, in the second place1-1 embodiment of the glass, Li₂O、Na₂O、K₂O and Cs₂Total content of O relative to SiO₂、P₂O₅And B₂O₃The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(SiO₂+P₂O₅+B₂O₃)]The upper limit of (b) is preferably 5.000, and more preferably 3.000, 2.000, 1.500, 1.300, 1.100, 1.000, and 0.900 in this order. In addition, mass ratio [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(SiO₂+P₂O₅+B₂O₃)]The lower limit of (b) is preferably 0.020, and more preferably 0.100, 0.200, 0.300, 0.400 and 0.500 in this order.

Mass ratio [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(SiO₂+P₂O₅+B₂O₃)]If the amount is too low, the meltability may be deteriorated, and the relative partial dispersion Pg and F may be increased, and if the amount is too high, the glass stability may be lowered, and the hot press formability may be deteriorated.

In addition, in the glass of the embodiment 1-1, Li₂O、Na₂O、K₂O and Cs₂Total content of O relative to Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) is preferably 4.000, and more preferably 3.000, 2.000, 1.000, 0.900, 0.700 and 0.500 in this order. In addition, mass ratio [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.015, and more preferably 0.050, 0.100, 0.150, 0.200, and 0.250 in this order.

Mass ratio [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]If the dispersion is too low, the relative partial dispersion Pg may increase, F may increase, and transmittance may deteriorate, and if it is too high, glass stability may decrease, and reheat press formability may deteriorate.

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

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

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

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

MgO, CaO, SrO and BaO are glass components having the effect of improving the thermal stability and devitrification resistance of the glass. However, when the content of these glass components is increased, the specific gravity increases, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably within the above range.

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

ZnO is a glass component having an effect of improving the thermal stability of the glass. However, when the content of ZnO is too large, the specific gravity increases. 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 characteristics.

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

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

In the glass of embodiment 1-1, the total content of MgO, CaO, SrO, BaO and ZnO is based on Li₂O、Na₂O、K₂O and Cs₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]The upper limit of (b) is preferably 20.000, and more preferably 10.000, 5.000, 3.000, 1.000, and 0.500 in this order. Further, the mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]The lower limit of (b) is preferably 0.000. Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]The lower limit of (c) may also be 0.000.

In the glass of embodiment 1-1, La₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, La₂O₃The lower limit of the content of (b) is preferably 0%.

La₂O₃When the content (c) is increased, the specific gravity increases and the thermal stability of the glass is lowered. Therefore, La is considered to suppress an increase in specific gravity and a decrease in thermal stability of the glass₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Y₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, Y₂O₃The lower limit of the content of (b) is preferably 0%.

Y₂O₃When the content of (b) is too large, the thermal stability of the glass is lowered, and the glass is easily devitrified during production. Therefore, from the viewpoint of suppressing the decrease in thermal stability of the glass, Y is₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Ta₂O₅The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, and 3% in this order. In addition, Ta₂O₅The lower limit of the content of (b) is preferably 0%.

Ta₂O₅A glass component having an effect of improving the thermal stability of the glass, wherein Nb is₂O₅、TiO₂、WO₃、Bi₂O₃Among the components, those which lower Pg and F are included. On the other hand, Ta₂O₅When the content (b) is increased, the thermal stability of the glass is lowered, and when the glass is melted, the glass raw material is likely to be melted and remain. Further, the specific gravity increases. Thus, Ta₂O₅The content of (b) is preferably in the above range.

Further, in the glass of embodiment 1-1, Ta₂O₅Relative to Ta₂O₅、Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Ta ]₂O₅/(Ta₂O₅+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (d) is preferably 0.900, and more preferably 0.700, 0.500, 0.300, 0.100, 0.050, and 0.010 in this order. The lower limit is 0.000.

Mass ratio [ Ta ]₂O₅/(Ta₂O₅+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]If the ratio is too high, the specific gravity increases and the cost increases.

In the glass of embodiment 1-1, Sc₂O₃The content of (b) is preferably 2% or less. In addition, Sc₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 1-1, HfO₂The content of (b) is preferably 2% or less. Further, HfO₂The lower limit of the content of (b) is preferably 0%.

Sc₂O₃、HfO₂Has the effect of improving the high dispersibility of the glass, but is an expensive component. Thus, Sc₂O₃、HfO₂The respective contents of (a) are preferably within the above ranges.

In the glass of embodiment 1-1, Lu₂O₃The content of (b) is preferably 2% or less. In addition, Lu₂O₃The lower limit of the content of (b) is preferably 0%.

Lu₂O₃The glass component has the effect of improving the high dispersibility of the glass, but is also a glass component that increases the specific gravity of the glass due to its large molecular weight. Thus, Lu₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, GeO₂The content of (b) is preferably 2% or less. In addition, GeO₂The lower limit of the content of (b) is preferably 0%.

GeO₂The glass composition has an effect of improving the high dispersibility of the glass, but is a very expensive component among glass components generally used. Therefore, GeO is considered from the viewpoint of reducing the production cost of glass₂The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Gd₂O₃The content of (b) is preferably 2% or less. In addition, Gd₂O₃The lower limit of the content of (b) is preferably 0%.

Gd₂O₃When the content of (b) becomes too large, the thermal stability of the glass is lowered. In addition, Gd₂O₃When the content of (b) is too large, the specific gravity of the glass increases, which is not preferable. Therefore, Gd is considered to be good in terms of keeping thermal stability of the glass and suppressing an increase in specific gravity₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 1-1, Yb₂O₃Has excellent content ofThe concentration is selected to be less than 2%. In addition, Yb₂O₃The lower limit of the content of (b) is preferably 0%.

Yb₂O₃And La₂O₃、Gd₂O₃、Y₂O₃Compared with a large molecular weight, and therefore, the specific gravity of the glass is increased. When the specific gravity of the glass increases, the mass of the optical element increases. For example, when a large-mass lens is incorporated in an auto-focus type imaging lens, the power required for driving the lens during auto-focusing increases, and the battery consumption becomes severe. Therefore, it is preferable to reduce Yb₂O₃To suppress an increase in the specific gravity of the glass.

In addition, Yb₂O₃When the content of (A) is too large, the thermal stability of the glass is lowered. Yb is considered to prevent the thermal stability of the glass from decreasing and to suppress the increase in specific gravity₂O₃The content of (b) is preferably in the above range.

The glass of embodiment 1-1 is preferably composed mainly of the above-described glass component, i.e., SiO₂、P₂O₅、B₂O₃、Al₂O₃、TiO₂、Nb₂O₅、WO₃、Bi₂O₃、Li₂O、Na₂O、K₂O、Cs₂O、MgO、CaO、SrO、BaO、ZnO、ZrO₂、Ta₂O₅、Sc₂O₃、HfO₂、Lu₂O₃、GeO₂、La₂O₃、Gd₂O₃、Y₂O₃And Yb₂O₃The total content of the above glass components is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

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 interfering with the action and effect of embodiment 1. In addition, in the invention 1, the inevitable impurities are not excluded.

(glass Properties)

< refractive index nd >

In the example of the glass of embodiment 1-1, the lower limit of the refractive index nd may be 1.55, and further may be 1.60, 1.65, 1.70, 1.75, or 1.80. The upper limit of the refractive index nd may be 1.95, or may be 1.90, 1.85, 1.80, or 1.75. Nb as a glass component contributing to increase in refractive index can be adjusted in refractive index₂O₅、TiO₂、WO₃And Bi₂O₃The content of (c) is controlled.

Specific gravity of glass

The glass of embodiment 1-1 is a high-refractivity high-dispersibility glass, but has a small specific gravity. In general, if the specific gravity of glass can be reduced, the weight of the lens can be reduced. As a result, power consumption for automatic focusing drive of the camera lens with the lens mounted thereon can be reduced. On the other hand, if the specific gravity is excessively reduced, thermal stability is lowered.

Therefore, in the example of the glass of embodiment 1-1, the specific gravity is preferably in the range of 4.5 or less, and more preferably in the order of 4.3 or less, 4.1 or less, 4.0 or less, 3.9 or less, 3.8 or less, 3.7 or less, and 3.6 or less. The specific gravity can be adjusted by adjusting the mass ratio [ P ]₂O₅/(SiO₂+P₂O₅+B₂O₃)]The mass ratio of [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]Mass ratio of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ Ta ]₂O₅/(Ta₂O₅+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]To control.

< glass transition temperature Tg >

In the example of the glass of embodiment 1-1, the upper limit of the glass transition temperature Tg is preferably 700 ℃, and more preferably 670 ℃, 650 ℃, 630 ℃, 610 ℃ and 590 ℃. The lower limit of the glass transition temperature Tg is preferably 450 ℃ and more preferably 500 ℃, 510 ℃, 530 ℃ and 550 ℃. The glass transition temperature Tg can be adjusted by adjusting the mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]Mass ratio of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]To control.

When the upper limit of the glass transition temperature Tg satisfies the above condition, the rise of the forming temperature and the annealing temperature at the time of reheat pressing of the glass can be suppressed, and the damage of heat to the facilities for reheat press forming and the annealing facilities can be reduced.

When the lower limit of the glass transition temperature Tg satisfies the above condition, the reheat press formability and the thermal stability of the glass can be favorably maintained while the desired abbe number and refractive index are easily maintained.

< transmittance >

The optical glass of embodiment 1-1 is an optical glass with very little coloration. The optical glass is suitable for use as a material for an optical element for image pickup such as a camera lens and an optical element for projection such as a projector.

The degree of coloration of optical glass is generally represented by λ 70, λ 5, and the like. A glass sample having a thickness of 10.0 mm. + -. 0.1mm was measured for spectral transmittance in a wavelength range of 200 to 700nm, and λ 70 was defined as a wavelength at which the external transmittance reached 70%, and λ 5 was defined as a wavelength at which the external transmittance reached 5%.

In the glass of embodiment 1-1, λ 70 is preferably 500nm or less, more preferably 470nm or less, 450nm or less, 430nm or less, 410nm or less, and 405nm or less. Further, λ 5 is preferably 390nm or less, more preferably 380nm or less, 370nm or less, and 360nm or less. λ 70 and λ 5 can be obtained by adjusting the mass ratio [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ (SiO)₂+P₂O₅+B₂O₃)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ Ta ]₂O₅/(Ta₂O₅+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Mass ratio [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]To control.

< processability >

The glass of embodiment 1-1 is formed by containing P₂O₅Thereby, the reheat press formability (workability) can be improved. In the reheat pressing, the glass is heated, and the softened state (viscosity) of the glass is controlled. The glass of embodiment 1-1 is less likely to cause internal defects and devitrification even when reheated over a wide temperature range, and therefore, is easy to adjust the softened state (viscosity) of the glass and is excellent in workability.

The heating temperature at the time of reheat pressing is generally a temperature at which glass softens or deforms. Specifically, the heating temperature is assumed to be a temperature higher by about 50 ℃ than the glass transition temperature Tg in a low case, and is assumed to be a temperature higher by about 200 to 300 ℃ than the glass transition temperature Tg in a high case.

When the heating temperature at the time of reheat pressing is low, that is, when the glass is heated at a temperature higher than the glass transition temperature Tg by about 50 ℃, phase separation hardly occurs in the glass, even if P is not contained₂O₅The glass of (3) can also suppress the occurrence of internal defects and devitrification.

However, when the heating temperature in the reheat press is low, a high pressure needs to be applied in the press forming. As a result, the possibility of cracking or breaking of the glass during cooling of the pressed glass molded article (e.g., lens or lens blank) is increased. Therefore, when the heating temperature at the time of reheat pressing is low, the production yield is liable to be lowered, and the shape of the press-formable glass formed article is liable to be limited.

On the other hand, when the heating temperature at the time of reheat pressing is high, that is, when heating is performed at a temperature higher than the glass transition temperature Tg by about 200 to 300 ℃, P is not contained₂O₅The glass of (3) is likely to cause phase separation in the glass, and is likely to cause internal defects and devitrification.

However, when the heating temperature in the reheat pressing is high, it is not necessary to apply a high pressure in the press forming, and the glass formed product is less likely to crack. Therefore, the reduction of the yield can be suppressed, and the shape of the glass molded article is not easily restricted.

The glass of embodiment 1-1 is formed by containing P₂O₅Thus, even when reheat pressing is performed at an arbitrary heating temperature, internal defects are less likely to occur. In particular, even when the reheat pressing is performed at a high temperature, there is a problem that internal defects and devitrification are less likely to occur, and thus a reduction in yield and a limitation in shape are less likely to occur.

In the example of the glass of embodiment 1-1, the upper limit of the number of internal defects generated when heat treatment is performed at a temperature at which the glass softens and deforms is preferably 1000/g, and more preferably 900/g, 700/g, 500/g, 300/g, 100/g, 70/g, 50/g, 40/g, 35/g, 30/g, 25/g, 20/g, 15/g, 13/g, 10/g, 9/g, 7/g, 5/g, 3/g, 2/g, 1/g, and 0/g. The upper limit of the number of internal defects allowed varies depending on the use of the glass. The internal defect has a size in the range of 1 to 300 μm.

Further, the glass of embodiment 1-1 is not P-containing₂O₅The number of internal defects generated when the glass is heat-treated at a temperature at which the glass softens or deforms is small as compared with the glass of (1). The glass (containing P) of embodiment 1-1₂O₅) The number of internal defects is Ip [ pieces/g ]]Will remove P₂O₅Except that the glass composition is the same and does not contain P₂O₅The number of internal defects of the glass is I [ pieces/g ]]When, Δ I [ pieces/g ]]I-Ip is preferably 1.0 or more, and more preferably 2 or more, 5 or more, 7 or more, 10 or more, 20 or more, 50 or more, 100 or more, 1000 or more, 10000 or more, 100000 or more in this order. The internal defect has a size in the range of 1 to 300 μm.

(production of optical glass)

The glass according to embodiment 1 of the present invention may be produced by blending glass raw materials so as to have the above-described predetermined composition and using the blended glass raw materials according to a known glass production method. 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 rapidly cooled and crushed to produce cullet. Further, the cullet was placed in a platinum crucible and heated and remelted (remelt) to prepare a molten glass, and after further clarification and homogenization, the molten glass was shaped and slowly cooled to obtain an 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.

As the optical glass of the embodiment of the invention 1, the glass of the embodiment of the invention 1 can be used as it is.

(production of optical element, etc.)

When the optical glass of the embodiment of the invention 1 is used to manufacture 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 made of the optical glass of the present invention. The obtained glass material is appropriately cut, ground and polished to produce chips having a size and 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 the 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 produced optical element may be coated with an antireflection film, a total reflection film, or the like.

According to one embodiment of the invention 1, an optical element formed of the above optical glass can be provided. Examples of the type of the optical element include a lens such as a spherical lens or an aspherical lens, a prism, a diffraction grating, and the like. Examples of the shape of the lens include 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. The optical element can be produced by a method including a step of processing a glass molded body formed of the above optical glass. Examples of the machining include cutting, rough grinding, finish grinding, and polishing. When such processing is performed, the use of the glass can reduce breakage and provide a high-quality optical element stably.

1 st to 2 nd embodiments

Hereinafter, as embodiments 1 to 2, the glass of the invention 1 will be described based on the mass ratio of the glass component. The action and effect of each glass component in embodiments 1 to 2 are the same as those of each glass component in embodiments 1 to 1. Therefore, the overlapping description of the embodiment 1-1 will be omitted as appropriate.

The glass of embodiment 1-2 is a silicate glass having an Abbe number vd of 20 to 35,

containing P₂O₅And Nb₂O₅，

The glass of the 1 st to 2 nd embodiments is mainly composed of SiO₂Silicate glass as a network forming component of the glass. SiO 2₂The content of (b) is preferably more than 0%, and the lower limit thereof is more preferably 1%, 5%, 10%, 15%, 20% in this order. In addition, SiO₂The upper limit of the content of (b) is preferably 60%, and more preferably 50%, 40%, 39%, 38%, 37%, 36%, 35% in this order.

SiO₂The network forming component of the glass has the effects of improving the thermal stability, chemical durability and weather resistance of the glass, increasing the viscosity of the molten glass, and facilitating the molding of the molten glass. On the other hand, SiO₂When the amount of (B) is large, the devitrification resistance of the glass tends to be low, and Pg and F tend to be increased. Therefore, SiO is preferably used₂The content of (b) is in the above range.

The glass of embodiment 1-2 contains P₂O₅。P₂O₅The lower limit of the content of (b) is preferably 0.1%, and more preferably 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, and 1.9% in this order. In addition, P₂O₅The upper limit of the content of (b) is preferably 10%, and more preferably 7%, 5%, and 3% in this order.

By making P₂O₅The lower limit of the content (b) satisfies the above range, and the reheat press formability can be improved. In addition, by making P₂O₅The upper limit of the content (b) satisfies the above range, and the glass can maintain thermal stability and improve reheat press formability.

Glass of embodiments 1-2Containing Nb₂O₅。Nb₂O₅The lower limit of the content of (b) may be 1%, and further may be 10%, 20%, 24%, 25%, 30%, 35%, 40%, or 43%. In addition, Nb₂O₅The upper limit of the content of (b) is preferably 80%, and more preferably 60%, 55%, 50%, and 45% in this order.

Nb₂O₅Is a component contributing to high dispersion. Therefore, by using Nb₂O₅The lower limit of the content (C) satisfies the above range, and a glass having a high refractive index and a high dispersibility can be obtained. In addition, Nb₂O₅And also a glass component for improving the thermal stability and chemical durability of the glass. Therefore, by using Nb₂O₅The upper limit of the content of (b) satisfies the above range, and the occurrence of defects as an optical element can be suppressed while maintaining the thermal stability and chemical durability of the glass satisfactorily.

In the glass of embodiment 1-2, Abbe number vd is 20 to 35. The Abbe number ν d may be 22 to 33, or 23 to 31, or 23 to 27, or 23 to 26.

By setting the abbe number ν d within the above range, a glass having high dispersibility can be obtained.

In the glass of embodiment 1-2, Nb₂O₅Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Greater than 0.6110. Mass ratio [ Nb₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.700, and more preferably 0.750, 0.800 and 0.850 in this order. In addition, mass ratio [ Nb₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of the content of (b) is preferably 1.000, and more preferably 0.990, 0.970, 0.950, 0.930, and 0.910 in this order.

By mixing the mass ratio [ Nb₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]With the above range, it is possible to provide an optical glass suitable for secondary chromatic aberration correction.

The glass composition in embodiment 1-2 can be the same as in embodiment 1-1. The glass characteristics, the production of optical glass, the production of optical elements, and the like in embodiments 1 to 2 may be the same as those in embodiment 1 to 1.

(other embodiments)

Hereinafter, embodiment a, embodiment B, and embodiment C will be described as glasses of other embodiments of the 1 st invention.

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

Therefore, when the characteristics of the glasses of embodiments a, B, and C are different from those of the glasses of embodiments 1-1 and 1-2, the preferable ranges of the characteristics of the glasses of embodiments a, B, and C apply to the ranges described below.

Embodiment A

The glass of embodiment A is characterized in that,

abbe number vd of 26.0 or more,

B₂O₃in a content relative to SiO₂Mass ratio of contents of [ B ]₂O₃/SiO₂]The content of the compound is below 0.800,

SiO₂and B₂O₃Relative to the total content of Nb₂O₅And TiO₂The mass ratio of the total content of [ (SiO ]₂+B₂O₃)/(Nb₂O₅+TiO₂)]Is a content of not more than 0.950%,

total content of MgO, CaO, SrO, BaO and ZnOAmount relative to Li₂O、Na₂O and K₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]The content of the compound is less than 0.480,

TiO₂relative to the content of Nb₂O₅Mass ratio of contents of [ TiO ]₂/Nb₂O₅]Is a content of not more than 0.340,

Li₂O、Na₂o and K₂Total content of O relative to TiO₂And Nb₂O₅The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]Is a content of not more than 0.700%,

SiO₂、B₂O₃、P₂O₅、Al₂O₃、Li₂O、Na₂O、K₂O、MgO、CaO、ZnO、La₂O₃、Y₂O₃、Gd₂O₃、ZrO₂、TiO₂and Nb₂O₅The total content of (A) is more than 96.0%,

PbO, CdO and As₂O₃The content of (A) is 0.01% or less.

The glass of embodiment a has an abbe number ν d of 26.0 or more, a relatively small specific gravity, and a relative partial dispersion Pg, F, with respect to the abbe number ν d, of small.

In the glass of embodiment A, B₂O₃In a content relative to SiO₂Mass ratio of contents of [ B ]₂O₃/SiO₂]The upper limit of (b) may be 0.800, and more preferably 0.700, 0.600, 0.550, 0.500, 0.450, 0.350, 0.300, 0.250, and 0.200. Mass ratio [ B₂O₃/SiO₂]And may be 0.

By mixing the mass ratio [ B₂O₃/SiO₂]With the above range, the increase in specific gravity and the coloring of the glass can be suppressed.

In the glass of embodiment A, SiO₂And B₂O₃Relative to the total content of Nb₂O₅And TiO₂The mass ratio of the total content of [ (SiO ]₂+B₂O₃)/(Nb₂O₅+TiO₂)]The upper limit of (b) may be set to 0.950, and more preferably to 0.930, 0.920, 0.910, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, 0.840, 0.830, 0.820, 0.810, 0.800, 0.790, and 0.780 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]The lower limit of (b) is preferably 0.300, and more preferably 0.350, 0.400, 0.450, 0.500, 0.550, 0.600, 0.630, 0.650, 0.670, 0.680, 0.690 in this order.

By mixing the mass ratio of [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]The above range provides desired optical constants. Further, the lowering of the network forming action of the glass can be suppressed, and the lowering of the stability at the time of reheating of the glass can be suppressed.

In the glass of embodiment A, the total content of MgO, CaO, SrO, BaO and ZnO is based on Li₂O、Na₂O and K₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]The upper limit of (b) may be 0.480, and more preferably 0.400, 0.350, 0.300, 0.250, 0.200, 0.150 and 0.100 in this order. Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]And may be 0.

By mixing the mass ratio of [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]Within the above range, the increase in specific gravity and the decrease in thermal stability can be suppressed. Further, a decrease in the refractive index nd can be suppressed.

In the glass of embodiment A, TiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ TiO ]₂/Nb₂O₅]The upper limit of (b) may be set to 0.340, and more preferably to 0.300, 0.280, 0.260, 0.240, 0.220, 0.200 and 0.180 in this order. Mass ratio [ TiO ]₂/Nb₂O₅]The lower limit of (3) is preferably 0, and more preferably 0.001, 0.002, 0.003, 0.004 and 0.005 in this order。

By mixing the mass ratio of [ TiO ]₂/Nb₂O₅]With the above range, the increase in the relative partial dispersions Pg, F can be suppressed. Further, it is possible to suppress a decrease in the network forming action of the glass, a decrease in the stability at the time of reheating the glass, and an increase in the specific gravity.

In the glass of embodiment A, Li₂O、Na₂O and K₂Total content of O relative to TiO₂And Nb₂O₅The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]The upper limit of (b) may be set to 0.700, and more preferably to 0.650, 0.600, 0.570, 0.550, 0.530, 0.510, 0.500, 0.490, 0.480, 0.470, 0.460, and 0.450. Mass ratio [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0.100, and more preferably 0.150, 0.200, 0.250, 0.270, 0.290, 0.300, 0.310, 0.320, 0.330, and 0.340 in this order.

By mixing the mass ratios of [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]The above range provides desired optical constants. In addition, the lowering of the meltability of the glass can be suppressed.

In the glass of embodiment A, SiO₂、B₂O₃、P₂O₅、Al₂O₃、Li₂O、Na₂O、K₂O、MgO、CaO、ZnO、La₂O₃、Y₂O₃、Gd₂O₃、ZrO₂、TiO₂And Nb₂O₅The lower limit of the total content of (b) may be 96.0%, and more preferably 96.5%, 97.0%, 97.5%, 98.0%, 98.2%, 98.4%, 98.6%, 98.8%, 99.0%. The total content may also be 100%.

By setting the total content to the above range, desired optical constants can be obtained. Further, the lowering of the network forming action of the glass, the lowering of the stability of the glass at the time of reheating and the increase of the specific gravity can be suppressed. Further, an increase in relative partial dispersion can be suppressed.

In the glass of embodiment A, PbO, CdO and As₂O₃The upper limit of the content of (b) may be 0.01%, and more preferably 0.005%, 0.003%, 0.002% and 0.001%, respectively. PbO, CdO and As are preferable₂O₃When the content of (3) is small, the content may be 0%. These components are components that may cause environmental burden, and are preferably substantially not contained.

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

(characteristics of glass of embodiment A)

Abbe number ν d >

In the glass of embodiment a, the lower limit of the abbe number ν d is preferably 26.0, and more preferably 26.5, 27.0, 27.2, 27.4, 27.6, 27.8, 28.0, 28.2, 28.4, 28.6, 28.8, and 29.0 in this order. The upper limit of the abbe number ν d is preferably 31.0, 30.8, 30.6, 30.4, 30.2, and 30.0 in this order. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. . The component capable of relatively increasing Abbe number vd is SiO₂、P₂O₅、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

< refractive index nd >

In the glass of embodiment A, the refractive index nd is preferably 1.70 to 1.90. The refractive index nd may be 1.72 to 1.85 or 1.73 to 1.83. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting these compositionsThe content of the component can control the refractive index nd.

< relative partial dispersion Pg, F >

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

By setting the relative partial dispersions Pg, F to the above ranges, an optical glass suitable for high-order chromatic aberration correction can be obtained. The component of F is Nb which relatively increases the relative partial dispersion Pg₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component of F is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the relative partial dispersions Pg, F can be controlled.

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

The upper limit of Δ Pg, F' of the glass of embodiment a is preferably 0.0000, and more preferably-0.0010, -0.0020, -0.0030, -0.0040, -0.0050, and-0.0060. The lower the Δ Pg, F' is, the lower the limit is preferably-0.0200, and may be-0.0180, -0.0160, -0.0140, -0.0130 or-0.0120. P is a component which relatively increases Δ Pg, F₂O₅、B₂O₃、TiO₂. Nb is a component which relatively lowers Δ Pg, F₂O₅、La₂O₃、Y₂O₃、ZrO₂、Li₂O、Na₂O、K₂And O. By properly adjusting the contents of these components, Δ Pg can be controlled,F’。

in the glass of embodiment a, the deviations Δ Pg, F' are shown as follows.

ΔPg,F’＝Pg,F+(0.00286×νd)-0.68900

Specific gravity of glass

The specific gravity of the glass of embodiment a is preferably 3.60 or less, and more preferably 3.55 or less, 3.50 or less, 3.48 or less, 3.46 or less, 3.45 or less, 3.44 or less, 3.43 or less, 3.42 or less, 3.41 or less, and 3.40 or less in this order. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.00. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the glass of embodiment A is preferably 700 ℃, and more preferably 670 ℃, 650 ℃, 630 ℃, 620 ℃, 610 ℃, 600 ℃ and 590 ℃ in this order. The lower limit of the glass transition temperature Tg is preferably 450 ℃ and more preferably 470 ℃, 500 ℃, 510 ℃, 520 ℃, 530 ℃ and 540 ℃. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< light transmittance of glass >

The light transmittance of the glass of embodiment a can be evaluated by the coloring degrees λ 70 and λ 5.

A glass sample having a thickness of 10.0 mm. + -. 0.1mm was measured for spectral transmittance in a wavelength range of 200 to 700nm, and λ 70 was defined as a wavelength at which the external transmittance reached 70%, and λ 5 was defined as a wavelength at which the external transmittance reached 5%.

The λ 70 of the glass of embodiment A is preferably 500nm or less, more preferably 470nm or less, even more preferably 450nm or less, and even more preferably 430nm or less. Further, λ 5 is preferably 400nm or less, more preferably 380nm or less, and further preferably 370nm or less. The degree of coloration of the resultant composition is adjusted to λ 70 and λ 5 by adjusting the amount of ZrO₂、Nb₂O₅、TiO₂、SiO₂、B₂O₃The content of (c) is controlled.

< stability on reheating >

The glass of embodiment A is preferably free from cloudiness when heated for 5 minutes in a test furnace set at a temperature 200 to 220 ℃ higher than the glass transition temperature Tg. More preferably, the number of crystals precipitated by the heating is 100 or less per 1 sample. The stability during reheating can be adjusted by adjusting Nb₂O₅、TiO₂、SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、P₂O₅The content of (c) is controlled.

The stability upon reheating was measured as follows. A glass sample having a size of 10mm × 10mm × 7.5mm is heated in a test furnace set at a temperature 200 to 220 ℃ higher than the glass transition temperature Tg of the glass sample for 5 minutes, and then the number of crystals per 1 sample is measured by an optical microscope (observation magnification: 40 to 200 times). The presence or absence of cloudiness of the glass was visually confirmed.

Glass characteristics other than those described above in embodiment a can be set in the same manner as in embodiment 1-1. The same applies to the production of optical glass and the production of optical elements and the like as in embodiment 1-1.

Embodiment B

The glass of embodiment B is characterized in that,

SiO₂relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]Is greater than 1.05 percent of the total weight of the composition,

ZrO₂relative to the content of Nb₂O₅The quality ofQuantitative ratio [ ZrO ]₂/Nb₂O₅]Is greater than the range of 0.25,

TiO₂and Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.65.

The glass of embodiment B has a relatively small specific gravity and a small relative partial dispersion Pg, F.

In the glass of embodiment B, SiO may be used₂Relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]More than 1.05, and the lower limit thereof is more preferably 1.09, 1.11, 1.15, 1.17 in this order. In addition, mass ratio [ SiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By mixing the mass ratio of SiO₂/Nb₂O₅]The above range allows the specific gravity of the glass to be reduced while maintaining desired optical constants (refractive index nd, Abbe number ν d).

In the glass of embodiment B, ZrO may be present₂Relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]More than 0.25, and the lower limit thereof is more preferably 0.26, 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, 0.315 in this order. In addition, mass ratio [ ZrO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.65, and more preferably 0.61, 0.57 or 0.53. By mixing the mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is in the above range, so that the relative partial dispersions Pg and F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the glass of embodiment B, TiO may be used₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.65 with lower limits of 0.66, 0.67, 0.69, 0The sequence of 70, 0.71, 0.73, 0.75, 0.76, 0.77, 0.79, 0.80, 0.83, 0.86, 0.88 is more preferred. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.20, and more preferably 1.15, 1.14, 1.13, 1.12, 1.11, 1.10, and 1.09. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The above range allows the glass to have desired optical constants while maintaining thermal stability.

In the glass of embodiment B, TiO₂And total content of BaO [ TiO ]₂+BaO]Preferably less than 10%, and more preferably in the order of 8.0%, 7.8%, 7.6%, 7.4% in the upper limit. In addition, total content [ TiO₂+BaO]The lower limit of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. By mixing the total content of [ TiO ]₂+BaO]The relative partial dispersions Pg, F can be reduced and the specific gravity of the glass can be reduced by setting the upper limit of (2) to the above range.

In the glass of embodiment B, Ta₂O₅In relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Preferably less than 0.3, and the upper limit thereof is more preferably in the order of 0.25, 0.20, 0.15. In addition, mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0, and more preferably 0.05, 0.07 or 0.10. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]And may be 0. By mixing the mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is set to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the glass of embodiment B, the content of ZnO relative to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, 0.105. In addition, the mass ratio [ ZnO/Nb₂O₅]Lower limit of (2)Preferably 0, and more preferably 0.02, 0.05 and 0.07 in this order. Mass ratio [ ZnO/Nb₂O₅]And may be 0. By mixing the mass ratio [ ZnO/Nb₂O₅]The upper limit of (2) is set to the above range, the specific gravity of the glass can be reduced, and desired optical constants can be obtained.

For the glass of embodiment B, Li may be used₂O、Na₂O and K₂Total content R of O₂Total content of O and total content R' O of MgO, CaO, SrO and BaO, total content R₂Mass ratio of O [ R ]₂O/(R₂O+R’O)]Greater than 0.05. Mass ratio [ R ]₂O/(R₂O+R’O)]Preferably greater than 0.6, and the lower limits thereof are more preferably in the order of 0.80, 0.82, 0.84, 0.86. In addition, the mass ratio [ R ]₂O/(R₂O+R’O)]The upper limit of (b) is preferably 1.00, and more preferably 0.99, 0.98 and 0.95 in this order. By mixing the mass ratio [ R ]₂O/(R₂O+R’O)]Within the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

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

(characteristics of glass of embodiment B)

< refractive index nd >

In the glass of embodiment B, the refractive index nd is preferably 1.69 to 1.76. The refractive index nd may be 1.695 to 1.755, or 1.70 to 1.75. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the refractive index nd can be controlled.

Abbe number ν d >

In the glass of embodiment B, abbe number ν d is preferably 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

Specific gravity of glass

The specific gravity of the glass of embodiment B is preferably 3.19 or less, and more preferably 3.18 or less, 3.17 or less, and 3.16 or less in this order. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.05. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< relative partial dispersion Pg, F >

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

The relative partial dispersion Pg of the glass of embodiment B, the deviation Δ Pg of F, the upper limit of F is preferably 0.0015, and more preferably 0.0012, 0.0010, and 0.0008 in this order. The lower limit of the variation Δ Pg, F is preferably-0.0060, and more preferably-0.0048, -0.0045, -0.0042, -0.0040, -0.0035, and-0.0025.

< liquid phase temperature >

The liquidus temperature LT of the glass of embodiment B is preferably 1200 ℃ or lower, and more preferably 1190 ℃ or lower, 1180 ℃ or lower, and 1170 ℃ or lower in this order. By bringing the liquid phase to a temperatureThe above range can lower the melting and forming temperature of the glass, and as a result, erosion of a glass melting tool (for example, a crucible, a stirrer for molten glass, or the like) in the melting step can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000 ℃. The liquidus temperature LT is determined according to the balance of the contents of all glass components. Wherein, SiO₂、B₂O₃、Li₂O、Na₂O、K₂The content of O or the like has a large influence on the liquidus temperature LT.

The liquidus temperature is determined as follows. 10cc (10ml) 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 less, and placed in a melting furnace at a predetermined temperature together with the platinum crucible and held for 2 hours. The glass was kept at a temperature of 1000 ℃ or higher at intervals of 5 ℃ or 10 ℃ for 2 hours, cooled, and then observed for the presence or absence of crystals in the glass with an optical microscope of 100 magnifications. The lowest temperature at which no crystal is precipitated is set as the liquidus temperature.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the glass of embodiment B is preferably 580 ℃, and more preferably 575 ℃, 570 ℃ and 565 ℃. The lower limit of the glass transition temperature Tg is preferably 510 ℃ and more preferably 515 ℃, 520 ℃ and 525 ℃ in this order. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< stability on reheating >

In the glass of embodiment B, the number of crystals observed per 1g is preferably 20 or less, more preferably 10 or less, when the glass is heated at the glass transition temperature Tg for 10 minutes and further at a temperature 140 to 250 ℃ higher than Tg for 10 minutes.

The stability during reheating was measured as follows. A glass sample having a size of 1cm × 1cm × 0.8cm is heated in a 1 st test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and further heated in a 2 nd test furnace set to a temperature 140 to 250 ℃ higher than the glass transition temperature Tg for 10 minutes, and then the presence or absence of crystal is confirmed by an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1g was measured. The presence or absence of cloudiness of the glass was visually confirmed.

Glass characteristics other than those described above in embodiment B can be set in the same manner as in embodiment 1-1. The same applies to the production of optical glass and the production of optical elements and the like as in embodiment 1-1.

Embodiment C

The glass of embodiment C is characterized in that,

SiO₂relative to the content of Nb₂O₅And TiO₂Mass ratio of the total content of [ SiO ]₂/(Nb₂O₅+TiO₂)]Is greater than 0.80 of the total weight of the rubber,

SiO₂、B₂O₃and P₂O₅Relative to the total content of Li₂O、Na₂O and K₂Mass ratio of total content of O [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]Is 1.45 to 4.55 percent,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Is 62 to 84 percent.

The glass of embodiment C has a low specific gravity and a low relative partial dispersion Pg, F.

In the glass of embodiment C, SiO₂Relative to the content of Nb₂O₅And TiO₂Mass ratio of the total content of [ SiO ]₂/(Nb₂O₅+TiO₂)]Preferably greater than 0.80, and the lower limit thereof is more preferably in the order of 0.83, 0.85, 0.86, 0.87, 0.88. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]Preferably has an upper limit of1.50, and more preferably 1.40, 1.30 and 1.20. By mixing the mass ratio of SiO₂/(Nb₂O₅+TiO₂)]With the above range, crystallization of the glass can be suppressed, and a glass excellent in homogeneity and stability during reheating can be obtained.

In the glass of embodiment C, SiO₂Relative to Na₂Mass ratio of O content [ SiO ]₂/Na₂O]Preferably 2.5 to 8.5. Mass ratio [ SiO ]₂/Na₂O]The lower limit of (b) is more preferably 2.6, and further more preferably 2.65, 2.70, and 2.75 in this order. In addition, mass ratio [ SiO ]₂/Na₂O]The upper limit of (b) is more preferably 8.2, and further more preferably 8.0, 7.8, and 7.6 in this order. By mixing the mass ratio of SiO₂/Na₂O]By setting the above range, glass having excellent homogeneity and stability during reheating can be obtained.

In the glass of embodiment C, SiO₂、B₂O₃And P₂O₅Relative to the total content of Li₂O、Na₂O and K₂Mass ratio of total content of O [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The range of the ratio can be set to 1.45-4.55. Mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is more preferably 1.70, and further more preferably 1.72, 1.74 and 1.76 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is more preferably 4.20, and further more preferably 4.00, 3.95, and 3.90 in this order. By mixing the mass ratio of [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]With the above range, crystallization of the glass can be suppressed.

In the glass of embodiment C, SiO₂And Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]The concentration of the organic solvent can be set to 62-84%. Total content [ SiO₂+Nb₂O₅]The lower limit of (b) is more preferably 63.0%, and still more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, total content [ SiO₂+Nb₂O₅]The upper limit of (b) is more preferably 83%, and further more preferably 82.7%, 82.3%, and 82.1% in this order. By mixing the total content of [ SiO ]₂+Nb₂O₅]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed.

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

(characteristics of glass of embodiment C)

< refractive index nd >

In the glass of embodiment C, the refractive index nd is preferably 1.690 to 1.760. The refractive index nd may be 1.695 to 1.755, or 1.700 to 1.750. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the refractive index nd can be controlled.

Abbe number ν d >

In the glass of embodiment C, abbe number ν d is preferably 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

Specific gravity of glass

The specific gravity of the glass of embodiment C is preferably 3.40 or less, and more preferably 3.35 or less and 3.30 or lessAnd 3.25 or less are more preferable. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.10. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< relative partial dispersion Pg, F >

The upper limit of the relative partial dispersion Pg, F of the glass of embodiment C is preferably 0.5980, and further more preferably 0.5970, 0.5960, 0.5950 and 0.5940 in this order. In addition, when the relative partial dispersion Pg, F is preferably low, the lower limit thereof is preferably 0.5780, and may be 0.5800, 0.5820, 0.5840, 0.5860. By setting the relative partial dispersions Pg, F to the above ranges, an optical glass suitable for high-order chromatic aberration correction can be obtained. Relative partial dispersion Pg, F can be adjusted by SiO₂、B₂O₃、TiO₂、Nb₂O₅Etc. are added.

The relative partial dispersion Pg of the glass of embodiment C, the deviation Δ Pg of F, and the upper limit of F are preferably 0.0030, and more preferably 0.0025, 0.0020, and 0.0015 in this order. When the deviation Δ Pg, F is preferably low, the lower limit thereof is preferably-0.0060, and may be-0.0050, -0.0040, -0.0030, or-0.0020.

< liquid phase temperature >

The liquidus temperature LT of the glass of embodiment C is preferably 1200 ℃ or lower, and more preferably 1190 ℃ or lower, 1180 ℃ or lower, and 1170 ℃ or lower in this order. By setting the liquidus temperature in the above range, the melting and forming temperature of the glass can be lowered, and as a result, erosion of a glass melting tool (for example, a crucible, a stirrer for molten glass, or the like) in the melting step can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000 ℃. The liquidus temperature LT is determined according to the balance of the contents of all glass components. Wherein, SiO₂、B₂O₃、Li₂O、Na₂O、K₂The content of O or the like has a large influence on the liquidus temperature LT.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the glass of embodiment C is preferably 670 ℃, and more preferably 650 ℃, 630 ℃ and 610 ℃. The lower limit of the glass transition temperature Tg is preferably 510 ℃ and more preferably 520 ℃, 525 ℃ and 530 ℃. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< stability on reheating >

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

The stability during reheating was measured as follows. A glass sample having a size of 1cm × 1cm × 0.8cm is heated in a 1 st test furnace set to a glass transition temperature Tg of the glass sample for 10 minutes, and further heated in a 2 nd test furnace set to a temperature 140 to 220 ℃ higher than the glass transition temperature Tg for 10 minutes, and then the presence or absence of crystal is confirmed by an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1g was measured. The presence or absence of cloudiness of the glass was visually confirmed.

Glass characteristics other than those described above in embodiment C can be set in the same manner as in embodiment 1-1. The same applies to the production of optical glass and the production of optical elements and the like as in embodiment 1-1.

Invention 2

[ background of the invention 2]

For an optical element mounted in an optical system of an autofocus system, weight reduction is required to reduce power consumption when driving an autofocus function. If the specific gravity of glass can be reduced, the weight of an optical element such as a lens can be reduced. In addition, for correction of chromatic aberration, the relative partial dispersions Pg, F are required to be small.

Further, as a method for producing such an optical glass used in an optical system, there is a reheat press method in which glass is reheated and formed. In this method, devitrification is observed when reheating silicate optical glass having a high refractive index and a high dispersibility. Further, high stability is required such that devitrification is not easily generated in the glass during reheating of the glass.

Patent documents 2-1 to 2-3 disclose optical glasses having predetermined optical constants and aiming at reducing relative partial dispersion. However, the optical glasses disclosed in patent documents 2-1 to 2-3 have a large specific gravity.

In patent documents 2 to 4, it is an object to obtain an optical glass having a small relative partial dispersion at low cost. However, the optical glasses disclosed in patent documents 2 to 4 are glasses having relatively low dispersibility, and do not have the optical constants desired in the invention of patent document 2.

[ Prior Art document of invention 2]

Patent document

Patent document 2-1: japanese laid-open patent publication No. 2015-193515

Patent documents 2 to 2: japanese patent laid-open publication No. 2015-193516

Patent documents 2 to 3: japanese patent laid-open publication No. 2016-88759

Patent documents 2 to 4: japanese patent laid-open publication No. 2017-105702

[ summary of the invention 2]

[ problem to be solved by invention 2]

The object of the invention 2 is to provide an optical glass having desired optical constants, a relatively small specific gravity, a small relative partial dispersion Pg and F with respect to an abbe's number vd, and excellent stability in reheating, and an optical element formed of the optical glass.

[ means for solving problems ]

The gist of the invention 2 is as follows.

(1) An optical glass having an Abbe's number vd of 26.0 or more,

SiO₂is more than 0 mass% and less than 40 mass%,

TiO₂the content of (B) is 0 to 15% by mass,

Nb₂O₅the content of (B) is 25 to 45 mass%,

ZrO₂the content of (B) is more than 0 mass%,

Li₂O、Na₂o and K₂Total content of O [ Li₂O+Na₂O+K₂O]10 to 25% by mass,

Na₂content of O relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Is a content of at least 0.330,

the total content of MgO, CaO, SrO, BaO and ZnO based on Li₂O、Na₂O and K₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]The content of the compound is less than 0.480,

SiO₂、B₂O₃、P₂O₅、Al₂O₃、Li₂O、Na₂O、K₂O、MgO、CaO、ZnO、La₂O₃、Y₂O₃、Gd₂O₃、ZrO₂、TiO₂and Nb₂O₅The total content of (B) is 96.0 mass% or more,

PbO, CdO and As₂O₃The content of (b) is 0.01 mass% or less, respectively.

(2) An optical element formed of the optical glass according to the above (1).

[ Effect of the invention 2]

According to the invention of claim 2, there can be provided an optical glass having a desired optical constant, a relatively small specific gravity, a small relative partial dispersion Pg, F with respect to the abbe's number ν d, and excellent stability in reheating, and an optical element comprising the optical glass.

[ embodiment of the invention in the 2 nd ]

Hereinafter, the glass of embodiment 2 of the present invention will be described as embodiment 2.

In embodiment 2, F is expressed by using the refractive indices ng, nF, nC of g-rays, F-rays, and C-rays with respect to the partial dispersion Pg, as follows.

Pg,F＝(ng-nF)/(nF-nC)

In a plane in which the horizontal axis is the abbe number ν d and the vertical axis is the relative partial dispersion Pg, F, the normal line in embodiment 2 is expressed by the following equation.

Pg,F(0)’＝0.68900-0.00286×νd

The deviation Δ Pg, F' of the relative partial dispersion Pg, F with respect to the normal line is expressed as follows.

ΔPg,F’＝Pg,F-Pg,F(0)’

The optical glass of embodiment 2 is characterized in that it has an Abbe number vd of 26.0 or more,

SiO₂is more than 0% and less than 40%,

TiO₂the content of (a) is 0 to 15%,

Nb₂O₅the content of (a) is 25-45%,

ZrO₂the content of (A) is more than 0%,

Li₂O、Na₂o and K₂Total content of O [ Li₂O+Na₂O+K₂O]10 to 25 percent of the total weight of the composition,

PbO, CdO and As₂O₃The content of (A) is 0.01% or less.

In the optical glass of embodiment 2, the abbe number ν d is 26.0 or more. The lower limit of the abbe number ν d is preferably 26.5, and more preferably 27.0, 27.2, 27.4, 27.6, 27.8, 28.0, 28.2, 28.4, 28.6, 28.8, and 29.0 in this order. The upper limit of the abbe number ν d is preferably 31.0, 30.8, 30.6, 30.4, 30.2, and 30.0 in this order. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、P₂O₅、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

In the optical glass of embodiment 2, SiO₂The content of (A) is more than 0% and less than 40%. SiO 2₂The lower limit of the content of (b) is preferably 10%, and more preferably 15%, 17%, 19%, 21%, 23%, 25%, 26%, 27%, 28% in this order. In addition, SiO₂The upper limit of the content of (b) is preferably 39%, and more preferably 38%, 37%, 36%, 35%, 34%, 33% in this order.

SiO₂Is a network forming component of the glass. SiO 2₂When the content of (B) is too small, the compound is storedA network forming action of the glass is reduced, and stability of the glass during reheating is reduced. SiO 2₂If the content of (b) is too large, desired optical constants may not be obtained.

In the optical glass of embodiment 2, TiO₂The content of (A) is 0-15%. TiO 2₂The upper limit of the content of (b) is preferably 14%, and more preferably 13%, 12%, 11%, 10%, 9%, 8%, 7%, and 6% in this order. TiO 2₂The lower limit of the content of (b) is preferably 0.05%, and more preferably 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35% in this order.

TiO₂Is a component for highly dispersing glass. TiO 2₂If the content of (b) is too large, there is a risk that the relative partial dispersion Pg and F increases. TiO 2₂When the content of (b) is too small, desired optical constants may not be obtained. In addition, there is a possibility that the network forming action of the glass is lowered and the stability at the time of reheating the glass is lowered.

In the optical glass of embodiment 2, Nb₂O₅The content of (A) is 25-45%. Nb₂O₅The lower limit of the content of (b) is preferably 27%, and more preferably 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% in this order. In addition, Nb₂O₅The upper limit of the content of (b) is preferably 44.5%, and more preferably 44.0%, 43.5%, 43.2%, 43.0%, 42.7%, and 42.5% in this order.

Nb₂O₅Is a component for making the glass highly dispersed and reducing the relative partial dispersion Pg, F. Nb₂O₅When the content of (b) is too large, there are problems that the thermal stability of the glass is lowered and the cost of raw materials is increased. Nb₂O₅When the content of (b) is too small, there is a possibility that relative partial dispersion Pg and F increase and desired optical constants cannot be obtained.

In the optical glass of embodiment 2, ZrO₂The content of (A) is more than 0%. ZrO (ZrO)₂The lower limit of the content of (b) is preferably 1%, and more preferably 2%, 3%, 4%, 5%, 6%, 7%, and 8% in this order. In addition, ZrO₂The upper limit of the content of (B) is preferablyThe content is 15%, and further 14%, 13.5%, 13.2%, 13.0%, 12.8%, 12.6%, and 12.4% in this order are more preferable.

ZrO₂Is a component for making the glass highly dispersed and reducing the relative partial dispersion Pg, F. ZrO (ZrO)₂If the content of (b) is too large, the network forming action of the glass may be reduced, and the stability of the glass during reheating may be reduced. ZrO (ZrO)₂When the content of (b) is too small, there is a possibility that relative partial dispersion Pg and F increase and desired optical constants cannot be obtained.

In the optical glass of embodiment 2, B₂O₃In a content relative to SiO₂Mass ratio of contents of [ B ]₂O₃/SiO₂]Is 0.800 or less. Mass ratio [ B₂O₃/SiO₂]The upper limit of (b) is preferably 0.700, and more preferably 0.600, 0.550, 0.500, 0.450, 0.350, 0.300, 0.250, and 0.200 in this order. Mass ratio [ B₂O₃/SiO₂]And may be 0.

Mass ratio [ B₂O₃/SiO₂]If the amount is too large, the specific gravity increases, and the coloring of the glass may increase.

In the optical glass of embodiment 2, SiO₂And B₂O₃Relative to the total content of Nb₂O₅And TiO₂The mass ratio of the total content of [ (SiO ]₂+B₂O₃)/(Nb₂O₅+TiO₂)]Is 0.950 or less. Mass ratio [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 0.930, and more preferably 0.920, 0.910, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, 0.840, 0.830, 0.820, 0.810, 0.800, 0.790, and 0.780 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]The lower limit of (b) is preferably 0.300, and more preferably 0.350, 0.400, 0.450, 0.500, 0.550, 0.600, 0.630, 0.650, 0.670, 0.680, 0.690 in this order.

Mass ratio [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]If the value is too large, desired optical constants may not be obtained. Mass ratio [ (SiO)₂+B₂O₃)/(Nb₂O₅+TiO₂)]If the amount is too small, the network forming action of the glass may be reduced, and the stability of the glass during reheating may be reduced.

For the optical glass of embodiment 2, Li₂O、Na₂O and K₂Total content of O [ Li₂O+Na₂O+K₂O]10 to 25%. Total content [ Li₂O+Na₂O+K₂O]The lower limit of (b) is preferably 11.0%, and more preferably 12.0%, 12.5%, 13.0%, 13.5%, 13.7%, 13.9%, 14.1%, 14.3%, 14.5% in this order. In addition, total content [ Li₂O+Na₂O+K₂O]The upper limit of (b) is preferably 23%, and more preferably 22%, 21.5%, 21.0%, 20.5%, 20.0%, 19.5%, and 19.0%, in this order.

Total content [ Li₂O+Na₂O+K₂O]If the amount is too large, the network forming action of the glass may be reduced, and the stability of the glass during reheating may be reduced. In addition, there is a risk of shortening the life of refractory materials such as glass furnaces. Total content [ Li₂O+Na₂O+K₂O]If too small, the meltability of the glass may be reduced.

In the optical glass of embodiment 2, Na₂Content of O relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Is 0.330 or more. Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is preferably 0.380, and more preferably 0.420, 0.440, 0.460, 0.480, 0.500, 0.520, 0.540, 0.560, 0.580, and 0.600 in this order. In addition, mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 1.000, and more preferably 0.950, 0.900, 0.880, 0.860, 0.840, 0.820, 0.800, 0.780, 0.760, 0.740, 0.720, and 0.700 in this order.

Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]If too large, there is a risk that the thermal stability of the glass is lowered. Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]If the amount is too small, there are problems of an increase in specific gravity and a decrease in thermal stability, and an increase in raw material cost.

In the optical glass of embodiment 2, the total content of MgO, CaO, SrO, BaO and ZnO is based on Li₂O、Na₂O and K₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]Is 0.480 or less. Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 0.400, and more preferably 0.350, 0.300, 0.250, 0.200, 0.150, and 0.100 in this order. Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]And may be 0.

Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]If too large, the specific gravity increases and the thermal stability decreases. Mass ratio [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O)]If the refractive index nd is too small, the refractive index nd may decrease.

In the optical glass of embodiment 2, TiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ TiO ]₂/Nb₂O₅]Is 0.340 or less. Mass ratio [ TiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.300, and more preferably 0.280, 0.260, 0.240, 0.220, 0.200 or 0.180 in this order. Mass ratio [ TiO ]₂/Nb₂O₅]The lower limit of (b) is preferably 0, and more preferably 0.001, 0.002, 0.003, 0.004, and 0.005 in this order.

Mass ratio [ TiO ]₂/Nb₂O₅]If the dispersion is too large, the relative partial dispersion Pg and F may increase. Mass ratio [ TiO ]₂/Nb₂O₅]If the ratio is too small, the network forming action of the glass may be reduced, the stability of the glass during reheating may be reduced, and the specific gravity may be increased.

In the optical glass of embodiment 2, Li₂O、Na₂O and K₂Total content of O relative to TiO₂And Nb₂O₅The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]Is 0.700 or less. Mass ratio [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]The upper limit of (b) is preferably 0.650, and more preferably 0.600, 0.570, 0.550, 0.530, 0.510, 0.500, 0.490, 0.480, 0.470, 0.460, 0.450 in this order. Mass ratio [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0.100, and more preferably 0.150, 0.200, 0.250, 0.270, 0.290, 0.300, 0.310, 0.320, 0.330, and 0.340 in this order.

Mass ratio [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]If the value is too large, desired optical constants may not be obtained. Mass ratio [ (Li)₂O+Na₂O+K₂O)/(TiO₂+Nb₂O₅)]When the amount is too small, the meltability of the glass may be reduced.

In the optical glass of the present embodiment, SiO₂、B₂O₃、P₂O₅、Al₂O₃、Li₂O、Na₂O、K₂O、MgO、CaO、ZnO、La₂O₃、Y₂O₃、Gd₂O₃、ZrO₂、TiO₂And Nb₂O₅The total content of (A) is more than 96.0%. The lower limit of the total content is preferably 96.5%, and more preferably 97.0%, 97.5%, 98.0%, 98.2%, 98.4%, 98.6%, 98.8%, 99.0% in this order. The total content may also be 100%.

When the total content is too small, desired optical constants may not be obtained. Further, there are also a risk of lowering the network forming action of the glass and lowering the stability at the time of reheating the glass, a risk of increasing the specific gravity, and a risk of increasing the relative partial dispersion.

In the optical glass of embodiment 2, PbO, CdO and As₂O₃The content of (A) is 0.01% or less. PbO, CdO and As₂O₃The upper limit of the content of (b) is preferably 0.005%, and more preferably 0.003%, 0.002%, and 0.001%, respectively. PbO, CdO and As are preferable₂O₃When the content of (3) is small, the content may be 0%. These components are components that may cause environmental burden, and are preferably substantially not contained.

The contents and ratios of glass components other than those described above in the optical glass of embodiment 2 will be described in detail below.

In the optical glass of embodiment 2, B₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1% in this order. In addition, B is preferred₂O₃In the case of a small content of (B)₂O₃The content of (B) may be 0%.

By making B₂O₃The content of (b) is in the above range, the specific gravity of the glass can be reduced, and the thermal stability of the glass can be improved.

In the optical glass of embodiment 2, P₂O₅The upper limit of the content of (b) is preferably 2.50%, and more preferably 2.00%, 1.00%, 0.90%, 0.80%, 0.70%, 0.60%, 0.50% in this order. In addition, P₂O₅The lower limit of the content of (b) is preferably 0%, and more preferably 0.05%, 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20% in this order. P₂O₅The content of (B) may be 0%. P₂O₅Is a glass network-forming component, and therefore, by making the content thereof satisfy the above-mentioned lower limit, the thermal stability of the glass can be improved. On the other hand, P₂O₅Since the dispersion is reduced and Δ Pg, F' is relatively increased, the dispersion can be suppressed from being reduced and the thermal stability of the glass can be maintained by making the content of the component satisfy the upper limit.

In the optical glass of embodiment 2, Al₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 13%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3% in this order. Al (Al)₂O₃The content of (B) may be 0%. By making Al₂O₃The content of (b) is in the above range, whereby devitrification resistance and thermal stability of the glass can be maintained.

In the optical glass of embodiment 2, SiO₂And P₂O₅Total content of [ SiO ]₂+P₂O₅]The upper limit of (b) is preferably 40%, and more preferably 39%, 38%, 37%, 36%, 35%, and 34% in this order. In addition, total content [ SiO₂+P₂O₅]The lower limit of (b) is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30% in this order. By bringing the total content [ SiO ]₂+P₂O₅]Within the above range, the relative partial dispersions Pg and F can be suppressed from increasing, and the thermal stability of the glass can be maintained.

In addition, in the optical glass of embodiment 2, SiO₂、P₂O₅And B₂O₃Total content of [ SiO ]₂+B₂O₃+P₂O₅]The upper limit of (b) is preferably 40%, and more preferably 39%, 38%, 37%, 36%, 35%, and 34% in this order. In addition, total content [ SiO₂+B₂O₃+P₂O₅]The lower limit of (b) is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30% in this order.

In the optical glass of embodiment 2, P₂O₅In a content relative to SiO₂And P₂O₅The mass ratio of the total content of [ P ]₂O₅/(SiO₂+P₂O₅)]The upper limit of (d) is preferably 0.200, and more preferably 0.100, 0.050, 0.030, 0.020, 0.018, and 0.015 in this order. Mass ratio [ P₂O₅/(SiO₂+P₂O₅)]And may be 0.

By making the mass ratio [ P ]₂O₅/(SiO₂+P₂O₅)]Within the above range, the relative partial dispersions Pg and F can be suppressed from increasing.

In the optical glass of embodiment 2, P represents₂O₅In a content relative to SiO₂、P₂O₅And B₂O₃The mass ratio of the total content of [ P ]₂O₅/(SiO₂+B₂O₃+P₂O₅)]The upper limit of (d) is preferably 0.200, and more preferably 0.100, 0.050, 0.030, 0.020, 0.018, and 0.015 in this order. Mass ratio [ P₂O₅/(SiO₂+B₂O₃+P₂O₅)]And may be 0.

Further, in the optical glass of embodiment 2, SiO₂In a content relative to SiO₂、P₂O₅And B₂O₃Mass ratio of the total content of [ SiO ]₂/(SiO₂+B₂O₃+P₂O₅)]The upper limit of (b) is preferably 1. In addition, mass ratio [ SiO ]₂/(SiO₂+B₂O₃+P₂O₅)]The lower limit of (b) is preferably 0.900, and more preferably 0.905, 0.910, 0.915 and 0.920.

In the optical glass of embodiment 2, Nb₂O₅And TiO₂Total content of [ Nb ]₂O₅+TiO₂]The lower limit of (b) is preferably 30%, and more preferably 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% in this order. In addition, the total content [ Nb ]₂O₅+TiO₂]The upper limit of the content of (b) is preferably 55%, and more preferably 53%, 51%, 49%, 47%, 45%, 44%, and 43% in this order. By making the total content [ Nb ]₂O₅+TiO₂]Within the above range, desired optical constants can be achieved.

In the optical glass of embodiment 2, P₂O₅Relative to the content of Nb₂O₅Mass ratio of contents of [ P ]₂O₅/Nb₂O₅]The upper limit of (B) is preferably 0.200, more preferably 0.100. The order of 0.050, 0.020, 0.018, 0.015, 0.014, 0.013, and 0.012 is more preferable. Mass ratio [ P₂O₅/Nb₂O₅]And may be 0. By making the mass ratio [ P ]₂O₅/Nb₂O₅]Within the above range, the increase in Δ Pg, F' can be suppressed.

In the optical glass of embodiment 2, P₂O₅Relative to the content of Nb₂O₅And TiO₂The mass ratio of the total content of [ P ]₂O₅/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 0.200, and more preferably 0.100, 0.050, 0.020, 0.018, 0.015, 0.014, 0.013, 0.012, 0.011, and 0.010 in this order. Mass ratio [ P₂O₅/(Nb₂O₅+TiO₂)]And may be 0. By making the mass ratio [ P ]₂O₅/(Nb₂O₅+TiO₂)]Within the above range, the increase in Δ Pg, F' can be suppressed.

In the optical glass of embodiment 2, WO₃The upper limit of the content of (b) is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.3%, 0.1% in this order. In addition, WO₃The lower limit of the content of (b) is preferably 0%. WO₃The content of (B) may be 0%. By reacting WO₃The upper limit of the content of (b) is in the above range, the transmittance can be improved, and the relative partial dispersions Pg, F and specific gravity can be reduced.

In the optical glass of embodiment 2, Bi₂O₃The upper limit of the content of (b) is 5.0%, and more preferably 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.3%, 0.1% in this order. In addition, Bi₂O₃The lower limit of the content of (b) is preferably 0%. Bi₂O₃The content of (B) may be 0%. By reacting Bi₂O₃The content of (b) is in the above range, the thermal stability of the glass can be improved, and the relative partial dispersions Pg, F and specific gravity can be reduced.

In the optical glass of embodiment 2, Nb₂O₅、TiO₂、WO₃And Bi₂O₃Total content of [ Nb ]₂O₅+TiO₂+WO₃+Bi₂O₃]The lower limit of (b) is preferably 30%, and more preferably 32%, 34%, 36%, 38%, 39%, 40% in this order. In addition, the total content [ Nb ]₂O₅+TiO₂+WO₃+Bi₂O₃]The upper limit of (b) is preferably 55%, and more preferably 53%, 51%, 50%, 49%, 48%, 47%, 46%, 45%, 44%, 43% in this order. By making the total content [ Nb ]₂O₅+TiO₂+WO₃+Bi₂O₃]Within the above range, desired optical constants can be achieved.

In the optical glass of embodiment 2, Nb is added₂O₅Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.500, and more preferably 0.5500, 0.600, 0.650, 0.700, 0.750, 0.800, 0.820, 0.840, and 0.850 in this order. The upper limit of the mass ratio is preferably 1.000, and more preferably 0.999, 0.998, 0.997, 0.996, and 0.995.

Further, in the optical glass of embodiment 2, ZrO₂Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ ZrO ]₂/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.05, and more preferably 0.07, 0.09, 0.11, 0.13, 0.15, 0.17, and 0.18 in this order. The upper limit of the mass ratio is preferably 0.40, and more preferably 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, and 0.32 in this order. By setting the mass ratio in the above range, the abbe number ν d and the relative partial dispersions Pg, F can be controlled.

Furthermore, in the optical glass of embodiment 2, SiO₂、P₂O₅And B₂O₃Relative to the total content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ (SiO ]₂+B₂O₃+P₂O₅)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The lower limit of (b) is preferably 0.400, and more preferably 0.450, 0.500, 0.550, 0.600, 0.650, 0.670, 0.680, 0.690, 0.700 in this order. The upper limit of the mass ratio is preferably 1.000, and more preferably 0.980, 0.960, 0.940, 0.920, 0.900, 0.890, 0.880, 0.870, 0.860, 0.850, and 0.840 in this order. By setting the mass ratio in the above range, the abbe number ν d and the relative partial dispersions Pg, F can be controlled.

In the optical glass of embodiment 2, Li₂The upper limit of the content of O is preferably 10%, and more preferably 9%, 8%, 7%, and 6% in this order. Li₂The lower limit of the content of O is preferably 0%, and more preferably 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0% in this order. By mixing Li₂When the content of O is in the above range, the relative partial dispersions Pg and F can be prevented from increasing, and chemical durability, weather resistance and stability at reheating can be maintained.

In the optical glass of embodiment 2, Na₂The upper limit of the content of O is preferably 30%, and more preferably 25%, 23%, 21%, 19%, 17%, 15%, 13% in this order. Na (Na)₂The lower limit of the content of O is preferably 0%, and more preferably 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8% in this order. By mixing Na₂When the content of O is in the above range, the relative partial dispersions Pg and F can be reduced.

In the optical glass of embodiment 2, K₂The upper limit of the content of O is preferably 30%, and more preferably 25%, 20%, 15%, 10%, 8%, 6%, 4%, 2% in this order. K₂The lower limit of the content of O is preferably 0%, and more preferably 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% in this order. By mixing K₂The content of O in the above range improves the thermal stability of the glass。

In the optical glass of embodiment 2, Cs₂The upper limit of the content of O is preferably 10%, and more preferably 8%, 6%, 5%, 4%, 3%, 2%, and 1% in this order. Cs₂The lower limit of the content of O is preferably 0%. Cs₂The content of O may be 0%.

Cs₂O has an effect of improving the thermal stability of the glass, but when the content thereof is increased, the chemical durability and weather resistance are lowered. And there is a risk of an increase in specific gravity. Thus, Cs₂The respective contents of O are preferably in the above ranges.

In the optical glass of embodiment 2, Li₂O、Na₂O、K₂O and Cs₂Total content of O [ Li₂O+Na₂O+K₂O+Cs₂O]The upper limit of (b) is preferably 40%, and more preferably 35%, 30%, 28%, 26%, 24%, 22%, 21%, 20%, 19% in this order. Total content [ Li₂O+Na₂O+K₂O+Cs₂O]The lower limit of (b) is preferably 3%, and more preferably 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14% in this order. By mixing the total content [ Li₂O+Na₂O+K₂O+Cs₂O]Within the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature can be lowered.

In addition, in the optical glass of embodiment 2, Li₂O、Na₂O、K₂O and Cs₂Total content of O relative to SiO₂、P₂O₅And B₂O₃The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(SiO₂+B₂O₃+P₂O₅)]The upper limit of (b) is preferably 5.000, and more preferably 3.000, 2.000, 1.500, 1.300, 1.100, 1.000, 0.900, 0.800, 0.780, 0.760, 0.740, 0.720, 0.700, 0.680, 0.660, 0.640, 0.620, and 0.600 in this order. The lower limit of the mass ratio is preferably 0.100, and more preferably 0.200, 0.300, 0.350, 0.400, 0.420, 0.440, 0.460, and 0.480 in this order. When the mass ratio is too low, the mass ratio is storedThe melting property is deteriorated, the relative partial dispersion Pg and F are increased, and if the relative partial dispersion Pg and F are too high, the glass stability is lowered.

Further, in the optical glass of embodiment 2, Li₂O、Na₂O、K₂O and Cs₂Total content of O relative to Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ (Li)₂O+Na₂O+K₂O+Cs₂O)/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) is preferably 4.000, and more preferably 3.000, 2.000, 1.000, 0.900, 0.800, 0.750, 0.700, 0.650, 0.600, 0.550, 0.520, 0.500, 0.490, 0.480, and 0.470. The lower limit of the mass ratio is preferably 0.100, and more preferably 0.150, 0.200, 0.240, 0.260, 0.280, 0.300, 0.310, 0.320, and 0.330 in this order. If the mass ratio is too low, the relative partial dispersion Pg and F may increase, and the transmittance may deteriorate, while if it is too high, the glass stability may decrease.

Furthermore, in the optical glass of embodiment 2, P₂O₅Relative to Li₂O、Na₂O、K₂O and Nb₂O₅The mass ratio of the total content of [ P ]₂O₅/(Li₂O+Na₂O+K₂O+Nb₂O₅)]The upper limit of (b) is preferably 0.500, and more preferably 0.300, 0.100, 0.090, 0.080, 0.050, 0.030, 0.020, 0.015, 0.013, 0.011, 0.010, 0.009, and 0.008 in this order. Mass ratio [ P₂O₅/(Li₂O+Na₂O+K₂O+Nb₂O₅)]And may be 0. By setting the mass ratio in the above range, the increase in Δ Pg, F' can be suppressed.

In the optical glass of embodiment 2, P₂O₅Relative to Li₂O、Na₂O、K₂O、Cs₂O、Nb₂O₅、TiO₂、WO₃And Bi₂O₃The mass ratio of the total content of [ P ]₂O₅/(Li₂O+Na₂O+K₂O+Cs₂O+Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]The upper limit of (b) is preferably 0.500, and more preferably 0.300, 0.100, 0.090, 0.080, 0.050, 0.030, 0.020, 0.015, 0.013, 0.011, 0.010, 0.009, and 0.008 in this order. The mass ratio may be 0. By setting the mass ratio in the above range, the increase in Δ Pg, F' can be suppressed.

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

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

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

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

MgO, CaO, SrO and BaO are glass components having an effect of improving the thermal stability and devitrification resistance of the glass. However, when the content of these glass components is increased, the specific gravity increases and the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably within the above range.

In the optical glass of embodiment 2, the upper limit of the total content [ MgO + CaO ] of MgO and CaO is preferably 20%, and more preferably 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, 2% in this order. The lower limit of the total content [ MgO + CaO ] is preferably 0%. The total content [ MgO + CaO ] may be 0%. By setting the total content [ MgO + CaO ] within the above range, thermal stability can be maintained without hindering high dispersion.

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

ZnO is a glass component having an effect of improving the thermal stability of the glass. However, when the content of ZnO is too large, the specific gravity increases. 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 2, the upper limit of the total content of MgO, CaO, SrO, BaO and ZnO [ MgO + CaO + SrO + BaO + ZnO ] is preferably 20%, and more preferably 15%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, 2% in this order. In addition, the lower limit of the total content is preferably 0%. The total content may also be 0%. When the total content is in the above range, the increase in specific gravity can be suppressed, and thermal stability can be maintained without hindering the high dispersion.

In the optical glass of embodiment 2, the total content of MgO, CaO, SrO, BaO and ZnO is based on Li₂O、Na₂O、K₂O and Cs₂The mass ratio of the total content of O [ (MgO + CaO + SrO + BaO + ZnO)/(Li)₂O+Na₂O+K₂O+Cs₂O)]The upper limit of (b) is preferably 20.000, and more preferably 15.000, 10.000, 7.000, 5.000, 3.000, 2.000, 1.000, 0.900, 0.800, 0.700, 0.600, 0.500, 0.400, 0.300, 0.200, 0.100, 0.050, and 0.030. The lower limit of the mass ratio is preferably 0. The mass ratio may be 0.

In the optical glass of embodiment 2, La₂O₃The upper limit of the content of (C) is preferably 20%, andthe one-step is more preferably 15%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, 2% in this order. In addition, La₂O₃The lower limit of the content of (B) is preferably 0%, La₂O₃The content of (B) may be 0%. By passing La₂O₃The content of (b) is in the above range, and the relative partial dispersions Pg and F can be reduced while achieving desired optical constants and suppressing an increase in specific gravity.

In the optical glass of embodiment 2, Y₂O₃The upper limit of the content of (b) is preferably 20%, and more preferably 18%, 16%, 15%, 14%, 13%, 12%, 10%, 9%, and 8% in this order. In addition, Y₂O₃The lower limit of the content of (b) is preferably 0%.

In the optical glass of embodiment 2, Ta₂O₅The upper limit of the content of (b) is preferably 20%, and more preferably 15%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, 2% in this order. In addition, Ta₂O₅The lower limit of the content of (b) is preferably 0%.

Ta₂O₅Is a glass component having an effect of improving the thermal stability of the glass, and is a component causing a decrease in relative partial dispersion Pg, F. On the other hand, Ta₂O₅When the content (b) is increased, the thermal stability of the glass is lowered, and the glass raw material is likely to be melted and left when the glass is melted. And, the specific gravity rises. Also, the raw material cost rises. Thus, Ta₂O₅The content of (b) is preferably in the above range.

In the optical glass of embodiment 2, Sc₂O₃The content of (b) is preferably 2% or less. In addition, Sc₂O₃The lower limit of the content of (b) is preferably 0%.

In the optical glass of embodiment 2, HfO₂The content of (B) is preferably 2%The following. Further, HfO₂The lower limit of the content of (b) is preferably 0%, and more preferably 0.05% and 0.1% in this order.

Sc₂O₃、HfO₂Is an expensive component having an effect of improving the high dispersibility of the glass. Thus, Sc₂O₃、HfO₂The respective contents of (a) are preferably within the above ranges.

In the optical glass of embodiment 2, Lu₂O₃The content of (b) is preferably 2% or less. In addition, Lu₂O₃The lower limit of the content of (b) is preferably 0%.

Lu₂O₃The glass component has the effect of improving the high dispersibility of the glass, but is also a glass component which increases the specific gravity of the glass due to its large molecular weight. Thus, Lu₂O₃The content of (b) is preferably in the above range.

In the optical glass of embodiment 2, GeO₂The content of (b) is preferably 2% or less. In addition, GeO₂The lower limit of the content of (b) is preferably 0%.

GeO₂The glass has the effect of improving the high dispersibility of the glass, but is an extremely expensive component among glass components generally used. Therefore, GeO is considered from the viewpoint of reducing the production cost of glass₂The content of (b) is preferably in the above range.

In the optical glass of embodiment 2, Gd₂O₃The content of (b) is preferably 2% or less. In addition, Gd₂O₃The lower limit of the content of (b) is preferably 0%.

Gd₂O₃When the content of (b) becomes too large, the thermal stability of the glass is lowered. In addition, Gd₂O₃When the content of (b) is too large, the specific gravity of the glass increases. In addition, the raw material cost rises. Therefore, Gd is considered to be good in terms of keeping thermal stability of the glass and suppressing an increase in specific gravity₂O₃The content of (b) is preferably in the above range.

In the optical glass of embodiment 2, Yb₂O₃The content of (b) is preferably 2% or less. In addition, Yb₂O₃The lower limit of the content of (B) is preferablyIs selected as 0%.

Yb₂O₃And La₂O₃、Gd₂O₃、Y₂O₃This is because the specific gravity of the glass is increased because of its large molecular weight. Therefore, it is preferable to reduce Yb₂O₃To suppress an increase in the specific gravity of the glass.

The optical glass of embodiment 2 is preferably composed mainly of the above-mentioned glass component, i.e., SiO, which is an essential component₂、Nb₂O₅、ZrO₂B as an optional component₂O₃、P₂O₅、Al₂O₃、TiO₂、WO₃、Bi₂O₃、Li₂O、Na₂O、K₂O、Cs₂O、MgO、CaO、SrO、BaO、ZnO、La₂O₃、Y₂O₃、Ta₂O₅、Sc₂O₃、HfO₂、Lu₂O₃、GeO₂、Gd₂O₃And Yb₂O₃The total content of the glass components is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

The optical glass of embodiment 2 is preferably composed substantially of the above glass components, but may contain other components within a range not interfering with the operational effects of embodiment 2. In addition, in the invention 2, the inevitable impurities are not excluded.

(other Components)

The optical glass of embodiment 2 may contain a small amount of Sb₂O₃、CeO₂And the like as clarifying agents. The total amount of the clarifying agent (the amount added in an external proportion) is preferably 0% or more and less than 1%, more preferably 0% or more and 0.5%The following.

The external proportion addition amount is a value expressed by a weight percentage of the addition amount of the refining agent when the total content of all glass components except the refining agent is set to 100%.

The above optical glass can obtain high transmittance in a wide range of the visible region. In order to effectively utilize such a characteristic, it is preferable that the coloring element is not contained. Examples of the coloring element include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. Any element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, further preferably 0 to 50 mass ppm, and particularly preferably substantially not contained.

Further, Ga, Te, Tb, and the like are components that do not need to be introduced, and are expensive components. Therefore, Ga in mass%₂O₃、TeO₂、TbO₂The content ranges of (A) 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 Properties)

< refractive index nd >

In the optical glass of embodiment 2, the refractive index nd is preferably 1.70 to 1.90. The refractive index nd may be 1.72 to 1.85 or 1.73 to 1.83. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the refractive index nd can be controlled.

< relative partial dispersion Pg, F >

The upper limit of the relative partial dispersion Pg, F of the optical glass of embodiment 2 is preferably 0.6500, and more preferably in the order of 0.6400, 0.6300, 0.6200, 0.6100, 0.6050, 0.6040, 0.6030, 0.6020, 0.6010, and 0.6000. The lower limit of F is preferably 0.5500 as the relative partial dispersion Pg is lower, and may be 0.5600, 0.5700, 0.5800, 0.5840, 0.5850, 0.5870, 0.5890, 0.5900, 0.5910, 0.5920, 0.5930, 0.5940.

In the optical glass of embodiment 2, F preferably satisfies the following formula (2-1), more preferably satisfies the following formula (2-2), still more preferably satisfies the following formula (2-3), and particularly preferably satisfies the following formula (2-4) with respect to the partial dispersion Pg. By making the relative partial dispersions Pg, F satisfy the following expression, an optical glass suitable for the second-order chromatic aberration correction can be provided.

Pg,F≤-0.00286×νd+0.68900···(2-1)

Pg,F≤-0.00286×νd+0.68800···(2-2)

Pg,F≤-0.00286×νd+0.68600···(2-3)

Pg,F≤-0.00286×νd+0.68400···(2-4)

The upper limit of Δ Pg, F' of the optical glass of embodiment 2 is preferably 0.0000, and more preferably-0.0010, -0.0020, -0.0030, -0.0040, -0.0050, and-0.0060. The lower the Δ Pg, F' is, the lower the limit is preferably-0.0200, and further-0.0180, -0.0160, -0.0140, -0.0130 and-0.0120. P is a component which relatively increases Δ Pg, F₂O₅、B₂O₃、TiO₂. Nb is a component which relatively lowers Δ Pg, F₂O₅、La₂O₃、Y₂O₃、ZrO₂、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components,. DELTA.Pg, F' can be controlled.

Specific gravity of glass

The specific gravity of the optical glass of embodiment 2 is preferably 3.60 or less, and more preferably 3.55 or less, 3.50 or less, 3.48 or less, 3.46 or less, 3.45 or less, 3.44 or less, 3.43 or less, 3.42 or less, 3.41 or less, and 3.40 or less in this order. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.00. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the optical glass of embodiment 2 is preferably 700 ℃, and more preferably 670 ℃, 650 ℃, 630 ℃, 620 ℃, 610 ℃, 600 ℃ and 590 ℃. The lower limit of the glass transition temperature Tg is preferably 450 ℃ and more preferably 470 ℃, 500 ℃, 510 ℃, 520 ℃, 530 ℃ and 540 ℃. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. 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 2 can be evaluated for light transmittance by the coloring degrees λ 70 and λ 5.

The λ 70 of the optical glass of embodiment 2 is preferably 500nm or less, more preferably 470nm or less, still more preferably 450nm or less, and still more preferably 430nm or less. Further, λ 5 is preferably 400nm or less,more preferably 380nm or less, and still more preferably 370nm or less. The degree of coloration of the resultant composition is adjusted to λ 70 and λ 5 by adjusting the amount of ZrO₂、Nb₂O₅、TiO₂、SiO₂、B₂O₃The content of (c) is controlled.

< stability on reheating >

Preferably, the optical glass of embodiment 2 does not cause clouding when heated for 5 minutes in a test furnace set at a temperature 200 to 220 ℃ higher than the glass transition temperature Tg. More preferably, the number of crystals deposited by the heating is 100 or less per 1 sample. The stability during reheating can be adjusted by adjusting Nb₂O₅、TiO₂、SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、P₂O₅The content of (c) is controlled.

The optical glass of embodiment 2 can be produced in the same manner as in embodiment 1. The same procedure as in embodiment 1 can be applied to the manufacture of optical elements and the like.

Invention 3

[ background of the invention 3]

Patent document 3-1 discloses an optical glass having a refractive index nd of 1.674 or more and an abbe number ν d of 30.2 or more. However, the optical glass described in patent document 3-1 has low homogeneity, and does not satisfy the conditions of low specific gravity and low Pg, F. Therefore, there is a need for an optical glass having desired optical constants and higher performance.

[ Prior Art document of invention 3]

Patent document

Patent document 3-1: japanese patent laid-open publication No. 2017-105702

[ summary of the invention 3]

[ problem to be solved by invention 3]

In order to reduce power consumption when driving the autofocus function, it is required to reduce the weight of an optical element mounted in an optical system of the autofocus system. If the specific gravity of glass can be reduced, the weight of an optical element such as a lens can be reduced. Further, for correction of chromatic aberration, it is required that relative partial dispersions Pg, F are small.

Accordingly, the object of the invention 3 is to provide an optical glass having a desired optical constant, a relatively small specific gravity, and a small relative partial dispersion Pg, F, and an optical element formed of the optical glass.

[ means for solving problems ]

The gist of invention 3 is as follows.

(1) An optical glass, wherein,

ZrO₂relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Is greater than the range of 0.25,

TiO₂and Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Is greater than 0.65 of the total weight of the rubber,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

and the optical glass satisfies 1 or more of the following (a) and (b):

(a)Li₂O、Na₂o and K₂Total content R of O₂O is more than 9 mass percent,

(b) total content R₂O relative to the total content R₂Mass ratio of O to the total content of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.6, the total content R₂O is Li₂O、Na₂O and K₂The total content of O, wherein the total content R' O is the total content of MgO, CaO, SrO and BaO.

(2) An optical glass, wherein,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

Ta₂O₅in relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Less than 0.3 of the total weight of the composition,

and the optical glass satisfies 1 or more of the following (c) and (d):

(c)Li₂O、Na₂o and K₂Total content R of O₂O is more than 1.1 percent by mass,

(d) total content R₂O relative to the total content R₂Mass ratio of O to the total content of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.05, the total content R₂O is Li₂O、Na₂O and K₂The total content of O, wherein the total content R' O is the total content of MgO, CaO, SrO and BaO.

(3) An optical glass, wherein,

ZrO₂relative to the content ofNb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Is greater than the range of 0.25,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

content of ZnO to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Less than the range of 0.14, or less,

and the optical glass satisfies 1 or more of the following (e) and (f):

(e)Li₂O、Na₂o and K₂Total content R of O₂O is more than 1.1 percent by mass,

(f) total content R₂O relative to the total content R₂Mass ratio of O to the total content of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.05, the total content R₂O is Li₂O、Na₂O and K₂The total content of O, wherein the total content R' O is the total content of MgO, CaO, SrO and BaO.

(4) An optical glass having an Abbe's number vd of 30 to 36,

the specific gravity of the resin is below 3.19,

the deviation Δ Pg, F of the relative partial dispersion Pg, F is 0.0015 or less.

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

[ Effect of the invention 3]

According to the invention 3, there can be provided an optical glass having a desired optical constant, a relatively small specific gravity, and a small relative partial dispersion Pg, F, and an optical element formed of the above optical glass.

[ embodiment of the invention 3]

The optical glass of the invention 3 will be described below as the embodiment 3-1, the embodiment 3-2, the embodiment 3-3 and the embodiment 3-4. The action and effect of each glass component in embodiments 3-2, 3-3, and 3-4 are the same as those of each glass component in embodiment 3-1. Therefore, in embodiments 3-2, 3-3, and 3-4, the description of embodiment 3-1 will be omitted as appropriate.

In the embodiments 3-1, 3-2, 3-3, and 3-4, the refractive indices ng, nF, nC of g-rays, F-rays, and C-rays are used as F for the relative partial dispersion Pg, as described below.

Pg,F＝(ng-nF)/(nF-nC)

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

Pg,F(0)＝0.6483-(0.0018×νd)

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

ΔPg,F＝Pg,F-Pg,F(0)

3 st embodiment

For the optical glass of embodiment 3-1,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

further, it satisfies 1 or more of the following (a) and (b):

In the optical glass of embodiment 3-1, SiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]Greater than 1.05. Mass ratio [ SiO ]₂/Nb₂O₅]The lower limit of (b) is preferably 1.09, and more preferably 1.11, 1.15, and 1.17. In addition, mass ratio [ SiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By mixing the mass ratio of SiO₂/Nb₂O₅]The above range allows the specific gravity of the glass to be reduced while maintaining desired optical constants (refractive index nd, Abbe number ν d).

In the optical glass of embodiment 3-1, ZrO₂Relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Greater than 0.25. Mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is preferably 0.26, and more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, 0.315 in this order. In addition, mass ratio [ ZrO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.65, and more preferably 0.61, 0.57 or 0.53. By mixing the mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is in the above range, so that the relative partial dispersions Pg and F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of embodiment 3-1, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.65. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is preferably 0.66, and more preferably 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 in this order. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.20, and more preferably 1.14, 1.12, and 1.10. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The above range allows the glass to have desired optical constants while maintaining thermal stability.

In the optical glass of embodiment 3-1, TiO₂And total content of BaO [ TiO ]₂+BaO]Less than 10%. Total content [ TiO ]₂+BaO]The upper limit of (b) is preferably 8.0%, and more preferably 7.8%, 7.6%, and 7.4% in this order. In addition, total content [ TiO₂+BaO]The lower limit of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. By mixing the total content of [ TiO ]₂+BaO]The relative partial dispersions Pg, F can be reduced and the specific gravity of the glass can be reduced by setting the upper limit of (2) to the above range.

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

(a)Li₂O、Na₂o and K₂Total content R of O₂The content of O is more than 9 percent,

That is, in the optical glass of embodiment 3-1, Li₂O、Na₂O and K₂Total content R of O₂O may be greater than 9%. Total content R₂The lower limit of O is preferably 15.0%, and more preferably 15.5%, 16.0%, and 16.5% in this order. In addition, the total content R₂The upper limit of O is preferably 22.0%, and more preferably 21.7%, 21.4%, and 21.1% in this order. By mixing the total content R₂When O is in the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In addition, in the optical glass of embodiment 3-1, with respect to Li₂O、Na₂O and K₂Total content R of O₂Total content of O and total content R' O of MgO, CaO, SrO and BaO, total content R₂Mass ratio of O [ R ]₂O/(R₂O+R’O]And may be greater than 0.6. Mass ratio [ R ]₂O/(R₂O+R’O)]The lower limit of (b) is preferably 0.80, and more preferably 0.82, 0.84, and 0.86 in this order. In addition, the mass ratio [ R ]₂O/(R₂O+R’O)]The upper limit of (b) is preferably 0.95, and more preferably 0.98, 0.99, and 1.00 in this order. By mixing the mass ratio [ R ]₂O/(R₂O+R’O)]Within the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In the optical glass of embodiment 3-1, Ta₂O₅In relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Preferably less than 0.3, and the upper limit thereof is more preferably in the order of 0.25, 0.20, 0.15. In addition, mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0, and more preferably 0.05, 0.07 or 0.10. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]And may be 0. By mixing the mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is set to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glass of embodiment 3-1, the content of ZnO is relative to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, 0.105. In addition, the mass ratio [ ZnO/Nb₂O₅]Lower limit of (2)0 is selected, and the order of 0.02, 0.05 and 0.07 is more preferable. Mass ratio [ ZnO/Nb₂O₅]And may be 0. By mixing the mass ratio [ ZnO/Nb₂O₅]The upper limit of (2) is set to the above range, the specific gravity of the glass can be reduced, and desired optical constants can be obtained.

The contents and ratios of glass components other than those described above in the optical glass of embodiment 3-1 are described in detail below.

In the optical glass of embodiment 3-1, SiO₂The lower limit of the content of (b) is preferably 25%, and more preferably 28%, 30%, and 32% in this order. In addition, SiO₂The upper limit of the content of (b) is preferably 45%, and more preferably 43%, 41%, and 39% in this order. By mixing SiO₂When the content of (b) is in the above range, the specific gravity of the glass can be reduced, and the stability during reheating of the glass and desired optical constants can be obtained.

In the optical glass of embodiment 3-1, B₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. In addition, B₂O₃The lower limit of the content of (b) is preferably 0%, and more preferably 0.2%, 0.4%, and 0.6% in this order. B is₂O₃The content of (b) may be 0%. By mixing B₂O₃When the content of (b) is in the above range, the specific gravity of the glass can be reduced and the thermal stability of the glass can be improved.

In the optical glass of embodiment 3-1, SiO₂And B₂O₃Total content of [ SiO ]₂+B₂O₃]The upper limit of (b) is preferably 45%, and more preferably 43%, 41%, and 39% in this order. In addition, total content [ SiO₂+B₂O₃]The lower limit of the content of (b) is preferably 25%, and more preferably 28%, 30%, and 32% in this order. By mixing the total content of [ SiO ]₂+B₂O₃]When the specific gravity of the glass is within the above range, the thermal stability of the glass is improved, and desired optical constants can be obtained.

In the optical glass of embodiment 3-1, P₂O₅The upper limit of the content of (b) is preferably 1.5%, and more preferably 1.3%, 1.1%, and 0.9% in this order. In addition, P₂O₅The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.2%, and 0.3% in this order. P₂O₅The content of (b) may be 0%. By adding P₂O₅The content of (b) is in the above range, so that the increase of the relative partial dispersions Pg, F can be suppressed and the thermal stability of the glass can be maintained.

In the glass of embodiment 3-1, Al₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. Al (Al)₂O₃The content of (b) may be 0%. By mixing Al₂O₃The content of (b) is in the above range, whereby devitrification resistance and thermal stability of the glass can be maintained.

In the optical glass of embodiment 3-1, TiO₂The upper limit of the content of (b) is preferably 10%, and more preferably 9.5%, 9.0%, and 8.5% in this order. TiO 2₂The lower limit of the content of (b) is preferably 0%. TiO 2₂The content of (B) may be 0%. By making TiO₂The content of (b) is in the above range, a desired optical constant can be realized, and the raw material cost of the glass can be reduced.

In the optical glass of embodiment 3-1, Nb₂O₅The lower limit of the content of (b) is preferably 18%, and more preferably 20%, 22%, and 24% in this order. In addition, Nb₂O₅The upper limit of the content of (b) is preferably 38%, and more preferably 35%, 33%, and 31% in this order. By adding Nb₂O₅The content of (b) is in the above range, and the relative partial dispersions Pg and F can be reduced while achieving a desired optical constant and suppressing an increase in specific gravity.

In the optical glass of embodiment 3-1, TiO₂And Nb₂O₅Total content of [ TiO ]₂+Nb₂O₅]The lower limit of (b) is preferably 25%, and more preferably 29%, 30%, and 31% in this order. In addition, total content [ TiO₂+Nb₂O₅]The upper limit of the content of (b) is preferably 42%, and further 40%, 38%, 36% of cisThe sequence is more preferred. By mixing the total content of [ TiO ]₂+Nb₂O₅]With the above range, desired optical constants can be realized.

In the glass of the embodiment 3-1, WO₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. WO₃The content of (B) may be 0%. By reacting WO₃The upper limit of the content of (b) is in the above range, the transmittance can be improved, and the relative partial dispersions Pg, F and specific gravity can be reduced.

In embodiment 3-1, Bi₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. In addition, Bi₂O₃The lower limit of the content of (b) is preferably 0%. By adding Bi₂O₃The content of (b) is in the above range, whereby the thermal stability of the glass can be improved and the relative partial dispersions Pg, F and specific gravity can be reduced.

In the glass of embodiment 3-1, ZrO₂The lower limit of the content of (b) is preferably 5%, and more preferably 6%, 7%, and 8% in this order. In addition, ZrO₂The upper limit of the content of (b) is preferably 15%, and more preferably 14%, 13%, and 12% in this order. By reacting ZrO₂The content of (b) is in the above range, and the relative partial dispersions Pg, F can be reduced while achieving desired optical constants.

In the glass of embodiment 3-1, Li₂The upper limit of the content of O is preferably 10%, and more preferably 9%, 8%, and 7% in this order. Li₂The lower limit of the content of O is preferably 2%, and more preferably 3%, 4%, and 5% in this order. By mixing Li₂When the content of O is in the above range, desired optical constants can be achieved, and chemical durability, weather resistance, and stability during reheating can be maintained.

In the glass of embodiment 3-1, Na₂The upper limit of the content of O is preferably 18%, and more preferably 15%, 14%, and 13% in this order. Na (Na)₂The lower limit of the content of O is preferably 8%, and more preferably 9%, 10%, and 11% in this order.

In embodiment 3-1In the glass of (2), K₂The upper limit of the content of O is preferably 4.0%, and more preferably 3.0%, 2.5%, and 2.0% in this order. K₂The lower limit of the content of O is preferably 0%, and more preferably 0.2%, 0.4%, and 0.6% in this order. K₂The content of O may be 0%.

Na₂O and K₂O is a component that lowers the relative partial dispersion Pg, F, and has the effect of lowering the liquidus temperature and improving the thermal stability of the glass, but when the content thereof is increased, the chemical durability and weather resistance are lowered. Thus, Na₂O and K₂The respective contents of O are preferably within the above ranges.

In the glass of the embodiment 3-1, Cs₂The upper limit of the content of O is preferably 5%, and more preferably 3%, 1%, and 0.5% in this order. Cs₂The lower limit of the content of O is preferably 0%.

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

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

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

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

In the glass of embodiment 3-1, the upper limit of the total content R' O of MgO, CaO, SrO and BaO is preferably 10%, and more preferably 4%, 2% and 1% in this order. In addition, the lower limit of the total content R' O is preferably 0%. The total content R' O can also be 0%. By setting the total content R' O in the above range, it is possible to suppress an increase in specific gravity and maintain thermal stability without hindering high dispersion.

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

In the optical glass of embodiment 3-1, La₂O₃The upper limit of the content of (b) is preferably 10%, and more preferably 5%, 3%, and 1% in this order. In addition, La₂O₃The lower limit of the content of (B) is preferably 0%, La₂O₃The content of (B) may be 0%. By mixing La₂O₃The content of (b) is in the above range, and the relative partial dispersions Pg and F can be reduced while achieving a desired optical constant and suppressing an increase in specific gravity.

In the glass of embodiment 3-1, Y₂O₃The upper limit of the content of (b) is preferably 10%, and more preferably 5%, 3%, and 1% in this order. In addition, Y₂O₃The lower limit of the content of (b) is preferably 0%.

Y₂O₃BecomesIf the amount is too large, the thermal stability of the glass is lowered, and the glass is easily devitrified during production. Therefore, from the viewpoint of suppressing the decrease in thermal stability of the glass, Y is₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, Ta₂O₅The upper limit of the content of (b) is preferably 20%, and more preferably 10%, 5%, 3%, 1%, and 0.5% in this order. In addition, Ta₂O₅The lower limit of the content of (b) is preferably 0%.

Ta₂O₅Is a glass component having an effect of improving the thermal stability of the glass, and is a component causing a decrease in relative partial dispersion Pg, F. On the other hand, Ta₂O₅When the content (b) is increased, the thermal stability of the glass is lowered, and the glass raw material is likely to be melted and left when the glass is melted. In addition, the specific gravity increases. Thus, Ta₂O₅The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, Sc₂O₃The content of (b) is preferably 2% or less. In addition, Sc₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 3-1, HfO₂The content of (b) is preferably 2% or less. Further, HfO₂The lower limit of the content of (b) is preferably 0%, and more preferably 0.05% and 0.1% in this order.

In the glass of the embodiment 3-1, Lu₂O₃The content of (b) is preferably 2% or less. In addition, Lu₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 3-1, GeO₂The content of (b) is preferably 2% or less. In addition, GeO₂The lower limit of the content of (b) is preferably 0%.

In the glass of the 3-1 embodiment, Gd₂O₃The content of (b) is preferably 2% or less. In addition, Gd₂O₃The lower limit of the content of (b) is preferably 0%.

Gd₂O₃When the content of (b) becomes too large, the thermal stability of the glass is lowered. In addition, Gd₂O₃When the content of (b) is too large, the specific gravity of the glass increases. Therefore, Gd is considered to be good in terms of keeping thermal stability of the glass and suppressing an increase in specific gravity₂O₃The content of (b) is preferably in the above range.

In the glass of embodiment 3-1, Yb₂O₃The content of (b) is preferably 2% or less. In addition, Yb₂O₃The lower limit of the content of (b) is preferably 0%.

Yb₂O₃And La₂O₃、Gd₂O₃、Y₂O₃Compared with a large molecular weight, and therefore, the specific gravity of the glass is increased. When the specific gravity of the glass increases, the mass of the optical element increases. For example, if a large-mass lens is incorporated in an auto-focus type image pickup lens, the power required for driving the lens at the time of auto-focus increases, and the consumption of a battery becomes severe. Therefore, it is preferable to reduce Yb₂O₃To suppress an increase in the specific gravity of the glass.

The glass of the 3-1 embodiment is preferably composed mainly of the glass described aboveGlass component, i.e. SiO₂、B₂O₃、P₂O₅、Al₂O₃、TiO₂、Nb₂O₅、WO₃、Bi₂O₃、ZrO₂、Li₂O、Na₂O、K₂O、Cs₂O、MgO、CaO、SrO、BaO、ZnO、La₂O₃、Y₂O₃、Ta₂O₅、Sc₂O₃、HfO₂、Lu₂O₃、GeO₂、Gd₂O₃And Yb₂O₃The total content of the above glass components is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

The glass of embodiment 3-1 is preferably composed substantially of the above glass components, but may contain other components within a range not interfering with the action and effect of invention 3. In addition, in the invention 3, the inevitable impurities are not excluded.

(other Components)

In addition to the above components, the above optical glass may contain a small amount of Sb₂O₃、CeO₂And the like as clarifying agents. The total amount of the clarifying agent (the amount added in an external proportion) is preferably 0% or more and less than 1%, more preferably 0% or more and 0.5% or less.

Pb, Cd, As, Th, etc. are components that may cause environmental burdens. Thus, PbO, CdO, ThO₂The content of each is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially free of PbO, CdO, ThO₂。

As₂O₃The content of (B) is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably substantially not containing As₂O₃。

Further, the above optical glass can obtain a high transmittance in a wide range of the visible region. In order to effectively utilize such a characteristic, it is preferable that the coloring element is not contained. Examples of the coloring element include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. Any element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, further preferably 0 to 50 mass ppm, and particularly preferably substantially not contained.

(glass Properties)

< refractive index nd >

In the optical glass of embodiment 3-1, the refractive index nd is preferably 1.69 to 1.76. The refractive index nd may be 1.695 to 1.755, or 1.70 to 1.75. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the refractive index nd can be controlled.

Abbe number ν d >

In the optical glass of embodiment 3-1, the abbe number ν d is preferably 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By adjusting these appropriatelyThe Abbe number vd can be controlled by the content of the components.

Specific gravity of glass

The optical glass of embodiment 3-1 preferably has a specific gravity of 3.19 or less, more preferably 3.18 or less, 3.17 or less, and 3.16 or less in this order. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.05. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< relative partial dispersion Pg, F >

The relative partial dispersion Pg, F of the optical glass of embodiment 3-1 has an upper limit of 0.5950 preferably, and 0.5945, 0.5940 and 0.5935 are more preferably performed in this order. The lower limit of F with respect to the partial dispersion Pg is preferably 0.5780, and further more preferably 0.5785, 0.5790, 0.5795, 0.5805, 0.5815, and 0.5830 in this order. By setting the relative partial dispersions Pg, F to the above ranges, an optical glass suitable for high-order chromatic aberration correction can be obtained.

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

< liquid phase temperature >

The liquidus temperature LT of the optical glass of embodiment 3-1 is preferably 1200 ℃ or lower, and more preferably 1190 ℃ or lower, 1180 ℃ or lower, and 1170 ℃ or lower in this order. By setting the liquidus temperature in the above range, the melting and forming temperature of the glass can be lowered, and as a result, erosion of a glass melting tool (for example, a crucible, a stirrer for molten glass, or the like) in the melting step can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000 ℃. Liquid phase temperatureThe degree LT is determined according to the balance of the contents of all glass components. Wherein, SiO₂、B₂O₃、Li₂O、Na₂O、K₂The content of O or the like has a large influence on the liquidus temperature LT.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the optical glass of embodiment 3-1 is preferably 580 ℃, and more preferably 575 ℃, 570 ℃ and 565 ℃. The lower limit of the glass transition temperature Tg is preferably 510 ℃ and more preferably 515 ℃, 520 ℃ and 525 ℃ in this order. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< stability on reheating >

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

The optical glass of embodiment 3-1 can be produced in the same manner as in embodiment 1. The same procedure as in embodiment 1 can be applied to the manufacture of optical elements and the like.

3 st to 2 nd embodiments

For the optical glass of embodiment 3-2,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

further, the optical glass satisfies 1 or more of the following (c) and (d):

(d) total content R₂O relative to the total content R₂Mass ratio of O to the total content of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.05, the total content R₂O is Li₂O、Na₂O and K₂Total content of OThe total content R' O is the total content of MgO, CaO, SrO and BaO.

In the optical glass of embodiment 3-2, SiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]Greater than 1.05. Mass ratio [ SiO ]₂/Nb₂O₅]The lower limit of (b) is preferably 1.09, and more preferably 1.11, 1.15, and 1.17. In addition, mass ratio [ SiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By mixing the mass ratio of SiO₂/Nb₂O₅]The above range allows the specific gravity of the glass to be reduced while maintaining desired optical constants (refractive index nd, Abbe number ν d).

In the optical glass of embodiment 3-2, ZrO₂Relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Greater than 0.25. Mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is preferably 0.26, and more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, 0.315 in this order. In addition, mass ratio [ ZrO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.65, and more preferably 0.61, 0.57 or 0.53. By mixing the mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is in the above range, so that the relative partial dispersions Pg and F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of embodiment 3-2, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.65. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is preferably 0.66, and more preferably 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 in this order. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.20, and more preferably 1.14, 1.12, and 1.10. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The above range allows the glass to have desired optical constants while maintaining thermal stability.

In the optical glass of embodiment 3-2, TiO₂And total content of BaO [ TiO ]₂+BaO]Less than 10%. Total content [ TiO ]₂+BaO]The upper limit of (b) is preferably 8.0%, and more preferably 7.8%, 7.6%, and 7.4% in this order. In addition, total content [ TiO₂+BaO]The lower limit of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. By mixing the total content of [ TiO ]₂+BaO]The upper limit of (b) is set to the above range, the relative partial dispersions Pg, F can be reduced, and the specific gravity of the glass can be reduced.

In the optical glass of embodiment 3-2, Ta₂O₅In relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Less than 0.3. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is preferably 0.25, and more preferably 0.20 and 0.15 in this order. In addition, mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0, and more preferably 0.05, 0.07 or 0.10. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]And may be 0. By mixing the mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is set to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

The optical glass of embodiment 3-2 satisfies 1 or more of the following (c) and (d):

(c)Li₂O、Na₂o and K₂Total content R of O₂The content of O is more than 1.1 percent,

(d) total content R₂O relative to the total content R₂O andthe mass ratio of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.05, the total content R₂O is Li₂O、Na₂O and K₂The total content of O, wherein the total content R' O is the total content of MgO, CaO, SrO and BaO.

That is, in the optical glass of embodiment 3-2, Li may be used₂O、Na₂O and K₂Total content R of O₂O is more than 1.1 percent. Total content R₂O is preferably more than 9%, and the lower limit thereof is more preferably 15.0%, 15.5%, 16.0%, 16.5% in this order. In addition, the total content R₂The upper limit of O is preferably 22.0%, and more preferably 21.7%, 21.4%, and 21.1% in this order. By mixing the total content R₂When O is in the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In addition, in the optical glass of embodiment 3-2, with respect to Li₂O、Na₂O and K₂Total content R of O₂The total content R 'O of O and the total content R' O of MgO, CaO, SrO and BaO can be adjusted to₂Mass ratio of O [ R ]₂O/(R₂O+R’O)]Greater than 0.05. Mass ratio [ R ]₂O/(R₂O+R’O)]Preferably greater than 0.6, and the lower limits thereof are more preferably in the order of 0.80, 0.82, 0.84, 0.86. In addition, the mass ratio [ R ]₂O/(R₂O+R’O)]The upper limit of (b) is preferably 1.00, and more preferably 0.99, 0.98 and 0.95 in this order. By mixing the mass ratio [ R ]₂O/(R₂O+R’O)]Within the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In the optical glass of embodiment 3-2, the content of ZnO is relative to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, 0.105. In addition, the mass ratio [ ZnO/Nb₂O₅]The lower limit of (b) is preferably 0, and more preferably 0.02, 0.05 or 0.07 in this order. Mass ratio [ ZnO/Nb₂O₅]And may be 0. By mixing the mass ratio [ ZnO/Nb₂O₅]Is set to the above rangeThe specific gravity of the glass can be reduced and desired optical constants can be obtained.

The optical glass of embodiment 3-2 can be made similar to embodiment 3-1 in the content and ratio of the glass components other than those described above. The glass characteristics, the production of optical glass, the production of optical elements, and the like in embodiment 3-2 can be the same as those in embodiment 3-1.

Embodiments 3 to 3

For the optical glasses of the embodiments 3 to 3,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

further, the optical glass satisfies 1 or more of the following (e) and (f):

In 3 to 3In the optical glass of mode (A), SiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]Greater than 1.05. Mass ratio [ SiO ]₂/Nb₂O₅]The lower limit of (b) is preferably 1.09, and more preferably 1.11, 1.15, and 1.17. In addition, mass ratio [ SiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 2.10, and more preferably 2.05, 2.00, and 1.95 in this order. By mixing the mass ratio of SiO₂/Nb₂O₅]The above range allows the specific gravity of the glass to be reduced while maintaining desired optical constants (refractive index nd, Abbe number ν d).

In the optical glass of the embodiments 3 to 3, ZrO₂Relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Greater than 0.25. Mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is preferably 0.26, and more preferably 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, 0.315 in this order. In addition, mass ratio [ ZrO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.65, and more preferably 0.61, 0.57 or 0.53. By mixing the mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is in the above range, so that the relative partial dispersions Pg and F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the embodiments 3 to 3, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.65. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is preferably 0.66, and more preferably 0.67, 0.70, 0.73, 0.76, 0.80, 0.83, 0.86, and 0.88 in this order. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (B) is preferably 1.20, and more preferably 1.14, 1.12 and 1.10And (4) selecting. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The above range allows the glass to have desired optical constants while maintaining thermal stability.

In the optical glass of the embodiments 3 to 3, TiO₂And total content of BaO [ TiO ]₂+BaO]Less than 10%. Total content [ TiO ]₂+BaO]The upper limit of (b) is preferably 8.0%, and more preferably 7.8%, 7.6%, and 7.4% in this order. In addition, total content [ TiO₂+BaO]The lower limit of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. By mixing the total content of [ TiO ]₂+BaO]The relative partial dispersions Pg, F can be reduced and the specific gravity of the glass can be reduced by setting the upper limit of (2) to the above range.

In the optical glass of embodiment 3 to 3, the content of ZnO relative to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Less than 0.14. Nb₂O₅The upper limit of (b) is preferably 0.125, and more preferably 0.115 and 0.105 in this order. In addition, the mass ratio [ ZnO/Nb₂O₅]The lower limit of (b) is preferably 0, and more preferably 0.02, 0.05 or 0.07 in this order. Mass ratio [ ZnO/Nb₂O₅]And may be 0. By mixing the mass ratio [ ZnO/Nb₂O₅]The upper limit of (2) is set to the above range, the specific gravity of the glass can be reduced, and desired optical constants can be obtained.

The optical glass of the embodiments 3 to 3 satisfies 1 or more of the following (e) and (f):

(e)Li₂O、Na₂o and K₂Total content R of O₂The content of O is more than 1.1 percent,

That is, in the optical glass of the embodiments 3 to 3, Li may be used₂O、Na₂O and K₂Total content R of O₂O is more than 1.1 percent. Total content R₂O is preferably more than 9%, and the lower limit thereof is more preferably 15.0%, 15.5%, 16.0%, 16.5% in this order. In addition, the total content R₂The upper limit of O is preferably 22.0%, and more preferably 21.7%, 21.4%, and 21.1% in this order. By mixing the total content R₂When O is in the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In addition, in the optical glass of the embodiments 3 to 3, with respect to Li₂O、Na₂O and K₂Total content R of O₂The total content R 'O of O and the total content R' O of MgO, CaO, SrO and BaO can be adjusted to₂Mass ratio of O [ R ]₂O/(R₂O+R’O)]Greater than 0.05. Mass ratio [ R ]₂O/(R₂O+R’O)]Preferably greater than 0.6, and the lower limits thereof are more preferably in the order of 0.80, 0.82, 0.84, 0.86. In addition, the mass ratio [ R ]₂O/(R₂O+R’O)]The upper limit of (b) is preferably 0.95, and more preferably 0.98, 0.99, and 1.00 in this order. By mixing the mass ratio [ R ]₂O/(R₂O+R’O)]Within the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In the optical glass of embodiment 3-3, Ta₂O₅In relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Preferably less than 0.3, and the upper limit thereof is more preferably in the order of 0.25, 0.20, 0.15. In addition, mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0, and more preferably 0.05, 0.07 or 0.10. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]And may be 0. By mixing the mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is set to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glass of embodiment 3-3, the content and ratio of the glass components other than those described above can be set in the same manner as in embodiment 3-1. The glass characteristics, the production of optical glass, the production of optical elements, and the like in embodiment 3 to 3 may be the same as those in embodiment 3 to 1.

Embodiments 3 to 4

The optical glass of the embodiment 3-4 has an Abbe number vd of 30 to 36,

the specific gravity of the resin is below 3.19,

In the optical glass of the embodiment 3-4, Abbe number vd is 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

In the optical glass of the embodiments 3 to 4, the specific gravity is 3.19 or less. The specific gravity is preferably 3.18 or less, more preferably 3.17 or less, and still more preferably 3.16 or less. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.05.

In the optical glasses according to embodiments 3 to 4, the deviation Δ Pg, F of the relative partial dispersion Pg, F is 0.0015 or less. The upper limit of the deviation Δ Pg, F is preferably 0.0012, and more preferably 0.0010 and 0.0008 in this order. The lower limit of the variation Δ Pg, F is preferably-0.0060, and more preferably-0.0048, -0.0045, -0.0042, -0.0040, -0.0035, and-0.0025.

In general, F shows a tendency to decrease with an increase in abbe number vd with respect to partial dispersion Pg. Therefore, in embodiments 3 to 4, the relative partial dispersions Pg, F are defined using Δ Pg, F described above, instead of the relative partial dispersions Pg, F itself. The abbe number ν d can be increased by setting Δ Pg, F to 0.0015 or less, which is an optical glass suitable for correction of chromatic aberration of high order. Further, by setting the specific gravity to 3.19 or less, the optical element can be reduced in weight.

Next, preferred embodiments of the content and ratio of the glass component in the optical glass of embodiments 3 to 4 will be described in detail below.

In the optical glasses of embodiments 3 to 4, SiO₂Relative to the content of Nb₂O₅Mass ratio of contents of [ SiO ]₂/Nb₂O₅]Preferably greater than 1.05, the lower limit of which is more preferred in the order of 1.09, 1.11, 1.15, 1.17. In addition, mass ratio [ SiO ]₂/Nb₂O₅]The upper limit of (b) is preferably 1.50, and more preferably 1.48, 1.46 and 1.44. By mixing the mass ratio of SiO₂/Nb₂O₅]The above range allows the specific gravity of the glass to be reduced while maintaining desired optical constants (refractive index nd, Abbe number ν d).

In the optical glasses of embodiments 3 to 4, ZrO₂Relative to the content of Nb₂O₅Content of [ ZrO ]₂/Nb₂O₅]Preferably greater than 0.25, the lower limits of which are more preferably in the order of 0.26, 0.27, 0.28, 0.29, 0.30, 0.305, 0.310, 0.315. In addition, mass ratio [ ZrO ]₂/Nb₂O₅]The upper limit of (b) is preferably 0.50, and more preferably 0.47, 0.44 or 0.41. By mixing the mass ratio [ ZrO ]₂/Nb₂O₅]The lower limit of (b) is in the above range, so that the relative partial dispersions Pg and F can be reduced, the raw material cost can be reduced, and desired optical constants and solubility can be maintained.

In the optical glass of the embodiments 3 to 4, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Preferably greater than 0.65, and the lower limits thereof are more preferably in the order of 0.66, 0.67, 0.69, 0.71, 0.73, 0.76, 0.80, 0.83, 0.86, 0.88. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.20, and more preferably 1.14, 1.12, and 1.10. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The above range allows the glass to have desired optical constants while maintaining thermal stability.

In the optical glass of the embodiments 3 to 4, TiO₂And total content of BaO [ TiO ]₂+BaO]Preferably less than 10%, and more preferably in the order of 8.0%, 7.8%, 7.6%, 7.4% in the upper limit. In addition, total content [ TiO₂+BaO]The lower limit of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. By mixing the total content of [ TiO ]₂+BaO]The upper limit of (b) is set to the above range, the relative partial dispersions Pg, F can be reduced, and the specific gravity of the glass can be reduced.

In the optical glass of the embodiments 3 to 4, Ta₂O₅In relation to TiO₂And Nb₂O₅Mass ratio of the total content of [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]Preferably less than 0.3, and the upper limit thereof is more preferably in the order of 0.25, 0.20, 0.15. In addition, mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The lower limit of (b) is preferably 0, and more preferably 0.05, 0.07 or 0.10. Mass ratio [ Ta ]₂O₅/(TiO₂+Nb₂O₅)]And may be 0. By mixing the mass ratio [ Ta₂O₅/(TiO₂+Nb₂O₅)]The upper limit of (b) is set to the above range, the specific gravity of the glass can be reduced, and the raw material cost can be reduced.

In the optical glasses of embodiments 3 to 4, the content of ZnO is relative to Nb₂O₅Mass ratio of contents of [ ZnO/Nb ]₂O₅]Preferably less than 0.14, and the upper limit thereof is more preferably in the order of 0.125, 0.115, 0.105. In addition, the mass ratio [ ZnO/Nb₂O₅]The lower limit of (b) is preferably 0, and more preferably 0.02, 0.05 or 0.07 in this order. Mass ratio [ ZnO/Nb₂O₅]And may be 0. By mixing the mass ratio [ ZnO/Nb₂O₅]Is set to be upperIn the above range, the specific gravity of the glass can be reduced to obtain desired optical constants.

The optical glass of the embodiments 3 to 4 preferably satisfies 1 or more of the following (g) and (h):

(g)Li₂O、Na₂o and K₂Total content R of O₂The content of O is more than 1.1 percent,

(h) total content R₂O relative to the total content R₂Mass ratio of O to the total content of the total content R' O [ R₂O/(R₂O+R’O)]Greater than 0.05, the total content R₂O is Li₂O、Na₂O and K₂The total content of O, wherein the total content R' O is the total content of MgO, CaO, SrO and BaO.

That is, in the optical glasses of embodiments 3 to 4, Li may be used₂O、Na₂O and K₂Total content R of O₂O is more than 1.1 percent. Total content R₂O is preferably more than 9%, and the lower limit thereof is more preferably 15.0%, 15.5%, 16.0%, 16.5% in this order. In addition, the total content R₂The upper limit of O is preferably 22.0%, and more preferably 21.7%, 21.4%, and 21.1% in this order. By mixing the total content R₂When O is in the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

In addition, in the optical glasses of embodiments 3 to 4, with respect to Li₂O、Na₂O and K₂Total content R of O₂The total content R 'O of O and the total content R' O of MgO, CaO, SrO and BaO can be adjusted to₂Mass ratio of O [ R ]₂O/(R₂O+R’O)]Greater than 0.05. Mass ratio [ R ]₂O/(R₂O+R’O)]Preferably greater than 0.6, and the lower limits thereof are more preferably in the order of 0.80, 0.82, 0.84, 0.86. In addition, the mass ratio [ R ]₂O/(R₂O+R’O)]The upper limit of (b) is preferably 0.95, and more preferably 0.98, 0.99, and 1.00 in this order. By mixing the mass ratio [ R ]₂O/(R₂O+R’O)]Within the above range, the specific gravity of the glass can be reduced and the stability of the glass during reheating can be maintained.

The optical glass of embodiment 3 to 4 can be made similar to embodiment 3 to 1 in the content and ratio of the glass components other than those described above. In embodiments 3 to 4, glass characteristics other than those described above, production of optical glass, production of optical elements, and the like may be the same as those of embodiment 3 to 1.

In embodiment 3-4, any of embodiments 3-1 to 3-3 can be employed.

Invention 4

[ background of the invention of the 4 th ]

Further, as a method for producing such an optical glass used in an optical system, there is a reheat press method in which glass is reheated and molded. In this method, silicate-based optical glass having a high refractive index and high dispersibility is likely to devitrify during reheating. Therefore, high stability is required in which the inside of the glass is not easily devitrified when the glass is reheated.

Patent document 4-1 discloses an optical glass having a refractive index nd of 1.674 or more and an abbe number ν d of 30.2 or more. However, the optical glass described in patent document 4-1 has low homogeneity and devitrification is observed when it is reheated. Further, the conditions of low specific gravity and low Pg, F are not satisfied. Therefore, an optical glass having desired optical constants and higher performance is desired.

[ Prior Art document of invention 4]

Patent document

Patent document 4-1: japanese patent laid-open publication No. 2017-105702

[4 th invention ]

[ problem to be solved by invention 4]

The object of the 4 th invention is to provide an optical glass having desired optical constants, a specific gravity as small as possible, relative partial dispersions Pg and F as small as possible, excellent stability during reheating, and high homogeneity, and an optical element formed of the optical glass.

[ means for solving problems ]

The gist of the invention 4 is as follows.

(1) An optical glass, wherein,

SiO₂relative to Na₂Mass ratio of O content [ SiO ]₂/Na₂O]2.5 to 8.5 percent of the total weight of the alloy,

Na₂o content relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The content of the organic acid is more than 0.45,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]62 to 84 mass%.

(2) An optical glass, wherein,

TiO₂and Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Is greater than 0.7 of the total weight of the rubber,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]62 to 84 mass%.

(3) An optical glass having an Abbe's number vd of 30 to 36,

the specific gravity of the composite material is below 3.4,

the deviation Δ Pg, F of the relative partial dispersion Pg, F is 0.0030 or less.

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

[ Effect of the invention 4]

According to the invention 4, there can be provided an optical glass having desired optical constants, a specific gravity as small as possible, relative partial dispersions Pg and F as small as possible, excellent stability at reheating, and high homogeneity, and an optical element formed of the optical glass.

[ embodiment of the invention in 4]

νd＝(nd-1)/(nF-nC)

Hereinafter, the optical glass of the invention 4 will be described as the 4 th embodiment 1, the 4 th embodiment 2 and the 4 th embodiment 3. The action and effect of each glass component in embodiments 4-2 and 4-3 are the same as those of each glass component in embodiment 4-1. Therefore, in embodiments 4-2 and 4-3, the overlapping description of embodiment 4-1 is omitted as appropriate.

In embodiments 4-1, 4-2, and 4-3, F is expressed by using the refractive indices ng, nF, nC of g-rays, F-rays, and C-rays with respect to the partial dispersion Pg, as follows.

Pg,F＝(ng-nF)/(nF-nC)

Pg,F(0)＝0.6483-(0.0018×νd)

ΔPg,F＝Pg,F-Pg,F(0)

4 th embodiment

The optical glass of the 4 th to 1 mode is characterized in that,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Is 62 to 84 percent.

In the optical glass of embodiment 4-1, SiO₂Relative to the content of Nb₂O₅And TiO₂Mass ratio of the total content of [ SiO ]₂/(Nb₂O₅+TiO₂)]Greater than 0.80. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]The lower limit of (b) is preferably 0.83, and more preferably 0.85, 0.86, 0.87, and 0.88 in this order. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 1.50, and more preferably 1.40, 1.30 and 1.20. By mixing the mass ratio of SiO₂/(Nb₂O₅+TiO₂)]By setting the above range, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of embodiment 4-1, SiO₂Relative to Na₂Mass ratio of O content [ SiO ]₂/Na₂O]2.5 to 8.5. Mass ratio [ SiO ]₂/Na₂O]The lower limit of (b) is preferably 2.6, and more preferably 2.65, 2.70 and 2.75 in this order. In addition, mass ratio [ SiO ]₂/Na₂O]The upper limit of (b) is more preferably 8.2, and further more preferably 8.0, 7.8, and 7.6 in this order. By mixing the mass ratio of SiO₂/Na₂O]With the above range, an optical glass having excellent homogeneity and stability during reheating can be obtained.

In the optical glass of embodiment 4-1, SiO₂、B₂O₃And P₂O₅Relative to the total content of Li₂O、Na₂O and K₂Mass ratio of total content of O [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]Is 1.45 to 4.55. Mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is preferably 1.70, and more preferably 1.72, 1.74 and 1.76 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 4.20, and more preferably 4.0, 3.95 and 3.90 in this order. By mixing the mass ratio of [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]With the above range, crystallization of the glass can be suppressed.

In the optical glass of embodiment 4-1, Na₂O content relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Is 0.45 or more. Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is preferably 0.46, and more preferably 0.47, 0.48, and 0.49 in this order. In addition, mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 0.97, and more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By mixing the mass ratio of [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of embodiment 4-1, SiO₂And Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Is 62 to 84 percent. Total content [ SiO₂+Nb₂O₅]The lower limit of (b) is preferably 63.0%, and more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, total content [ SiO₂+Nb₂O₅]The upper limit of (b) is preferably 83%, and more preferably 82.7%, 82.3%, and 82.1% in this order. By mixing the total content of [ SiO ]₂+Nb₂O₅]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed.

In the optical glass of the 4 th to 1 st embodiment, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Preferably greater than 0.7. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is more preferably 0.73, and still more preferably 0.75, 0.77 or 0.79. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.15, and more preferably 1.13, 1.11, and 1.09. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass.

The contents and ratios of glass components other than those described above in the optical glass of embodiment 4-1 are described in detail below.

In the optical glass of embodiment 4-1, SiO₂The lower limit of the content of (b) is preferably 33.0%, and more preferably 33.5%, 34.0%, and 34.5% in this order. In addition, SiO₂The upper limit of the content of (b) is preferably 44.0%, and more preferably 43.5%, 43.0%, and 42.5% in this order. By mixing SiO₂When the content of (b) is in the above range, the specific gravity of the glass can be reduced, and the stability during reheating of the glass and desired optical constants can be obtained.

In the optical glass of embodiment 4-1, B₂O₃The upper limit of the content of (b) is preferably 5.0%, and more preferably 4.5%, 4.0%, and 3.5% in this order. In addition, B₂O₃The lower limit of the content of (b) is preferably 0%, and more preferably 0.1%, 0.2%, and 0.3% in this order. B is₂O₃The content of (B) may be 0%. By making B₂O₃The content of (b) is in the above range, the specific gravity of the glass can be reduced, and the thermal stability of the glass can be improved.

In the optical glass of embodiment 4-1, P₂O₅The upper limit of the content of (b) is preferably 1.5%, and more preferably 1.4%, 1.3%, and 1.2% in this order. In addition, P₂O₅The lower limit of the content of (b) is preferably 0%, and more preferably 0.2%, 0.4%, and 0.6% in this order. P₂O₅The content of (B) may be 0%. By making P₂O₅The content of (b) is in the above range, so that the increase of the relative partial dispersions Pg, F can be suppressed, and the thermal stability of the glass can be maintained.

In the glass of embodiment 4-1, Al₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. Al (Al)₂O₃The content of (B) may be 0%. By making Al₂O₃The content of (b) is in the above range, whereby devitrification resistance and thermal stability of the glass can be maintained.

In the optical glass of embodiment 4-1, SiO₂And B₂O₃Total content of [ SiO ]₂+B₂O₃]The upper limit of (b) is preferably 48.0%, and more preferably 47.0%, 46.0%, 45.0%, and 44.5% in this order. In addition, total content [ SiO₂+B₂O₃]The lower limit of the content of (b) is preferably 32.0%, and more preferably 33.0%, 34.0%, 35.0%, and 35.5% in this order. By mixing the total content of [ SiO ]₂+B₂O₃]When the specific gravity of the glass is within the above range, the thermal stability of the glass is improved, and desired optical constants can be obtained.

Further, in the optical glass of embodiment 4-1, SiO₂、B₂O₃And P₂O₅Total content of [ SiO ]₂+B₂O₃+P₂O₅]The upper limit of (b) is preferably 48.0%, and more preferably 47.0%, 46.0%, 45.0%, and 44.5% in this order. In addition, total content [ SiO₂+B₂O₃+P₂O₅]The lower limit of the content of (b) is preferably 33.0%, and more preferably 34.0%, 35.0%, 36.0%, and 36.5% in this order. By mixing the total content of [ SiO ]₂+B₂O₃+P₂O₅]When the specific gravity of the glass is within the above range, the thermal stability of the glass is improved, and desired optical constants can be obtained.

In the optical glass of the 4 th to 1 st embodiment, TiO₂The upper limit of the content of (b) is preferably 10%, and more preferably 9.5%, 9%, and 8.5% in this order. TiO 2₂The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. TiO 2₂The content of (B) may be 0%. By making TiO₂The content of (b) is in the above range, a desired optical constant can be realized, and the raw material cost of the glass can be reduced.

In the optical glass of embodiment 4-1, Nb₂O₅The lower limit of the content of (b) is preferably 45%, and more preferably 44%, 43%, and 42% in this order. In addition, Nb₂O₅The upper limit of the content of (b) is preferably 24%, and more preferably 25%, 26%, and 27% in this order. By adding Nb₂O₅The content of (b) is in the above range, and the relative partial dispersions Pg and F can be reduced while achieving a desired optical constant and suppressing an increase in specific gravity.

In the optical glass of the 4 th to 1 st embodiment, TiO₂And Nb₂O₅Total content of [ TiO ]₂+Nb₂O₅]The lower limit of (b) is preferably 28%, and more preferably 29%, 30%, and 31% in this order. In addition, total content [ TiO₂+Nb₂O₅]The upper limit of the content of (b) is preferably 45%, and more preferably 44%, 43%, and 42% in this order. By mixing the total content of [ TiO ]₂+Nb₂O₅]With the above range, desired optical constants can be realized.

In the glass of the 4 th to 1 st embodiment, WO₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. WO₃The content of (B) may be 0%. By reacting WO₃The upper limit of the content of (b) is in the above range, the transmittance can be improved, and the relative partial dispersions Pg, F and specific gravity can be reduced.

In the 4 th-1 st embodiment, Bi₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. In addition, Bi₂O₃The lower limit of the content of (b) is preferably 0%. Bi₂O₃The content of (B) may be 0%. By reacting Bi₂O₃The content of (A) is in the above range, the thermal stability of the glass can be improved, and the relative partial dispersion Pg, F and the ratio can be reducedAnd (4) heavy.

In the glass of the 4 th to 1 embodiment, ZrO₂The lower limit of the content of (b) is preferably 0%, and more preferably 1%, 2%, and 3% in this order. In addition, ZrO₂The upper limit of the content of (b) is preferably 12.5%, and more preferably 12.2%, 11.8%, and 11.4% in this order. ZrO (ZrO)₂The content of (B) may be 0%. By making ZrO₂The content of (b) is in the above range, a desired optical constant can be realized, and relative partial dispersions Pg, F can be reduced.

In the glass of the 4-1 embodiment, Li₂The upper limit of the content of O is preferably 10%, and more preferably 9%, 8%, and 7% in this order. Li₂The lower limit of the content of O is preferably 0%, and more preferably 1%, 2%, and 3% in this order. Li₂The content of O may be 0%. By reacting Li₂The content of O is in the above range, and the desired optical constants can be achieved while maintaining chemical durability, weather resistance, and stability at reheating.

In the glass of embodiment 4-1, Na₂The upper limit of the content of O is preferably 15%, and more preferably 14%, 13.5%, and 13% in this order. Na (Na)₂The lower limit of the content of O is preferably 4%, and more preferably 4.5%, 5%, and 5.5% in this order. By mixing Na₂When the content of O is in the above range, the relative partial dispersions Pg and F can be reduced.

In the glass of the 4 th to 1 st embodiment, K₂The upper limit of the content of O is preferably 5%, and more preferably 4.5%, 4%, and 3.5% in this order. K₂The lower limit of the content of O is preferably 0%, and more preferably 0.1%, 0.2%, and 0.3% in this order. K₂The content of O may be 0%. By making K₂The content of O is in the above range, and the thermal stability of the glass can be improved.

In the glass of the 4-1 embodiment, Li₂O、Na₂O and K₂Total content of O [ Li₂O+Na₂O+K₂O]The upper limit of (b) is preferably 22%, and more preferably 21%, 20.5% and 20% in this order. The lower limit of the total content is preferably 11%, and more preferably 11.1%, 11%The order of 2%, 11.3% is more preferred. By setting the total content to the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature can be lowered.

In the glass of the 4 th to 1 embodiment, Cs₂The upper limit of the content of O is preferably 5%, and more preferably 3%, 1%, and 0.5% in this order. Cs₂The lower limit of the content of O is preferably 0%.

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

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

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

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

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

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

In the optical glass of embodiment 4-1, La₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. In addition, La₂O₃The lower limit of the content of (b) is preferably 0%. La₂O₃The content of (B) may be 0%. By passing La₂O₃The content of (b) is in the above range, and the relative partial dispersions Pg and F can be reduced while achieving desired optical constants and suppressing an increase in specific gravity.

In the glass of the 4 th to 1 st embodiment, Y₂O₃The upper limit of the content of (b) is preferably 5%, and more preferably 4%, 3%, and 2% in this order. In addition, Y₂O₃The lower limit of the content of (b) is preferably 0%. Y is₂O₃The content of (B) may be 0%.

In the glass of embodiment 4-1, Ta₂O₅The upper limit of the content of (C) is preferably 5%, andthe one-step process is more preferably 4%, 3% or 2%. In addition, Ta₂O₅The lower limit of the content of (b) is preferably 0%. Ta₂O₅The content of (B) may be 0%.

In the glass of the 4 th to 1 st embodiment, Sc₂O₃The content of (b) is preferably 2% or less. In addition, Sc₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of the 4 th-1 embodiment, HfO₂The content of (b) is preferably 2% or less. Further, HfO₂The lower limit of the content of (b) is preferably 0%, and more preferably 0.05% and 0.1% in this order.

In the glass of the 4 th to 1 st embodiment, Lu₂O₃The content of (b) is preferably 2% or less. In addition, Lu₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of the 4-1 embodiment, GeO₂The content of (b) is preferably 2% or less. In addition, GeO₂The lower limit of the content of (b) is preferably 0%.

GeO₂Has the effect of improving the high dispersibility of the glass, but is an extremely expensive component among the glass components generally used. Therefore, GeO is considered from the viewpoint of reducing the production cost of glass₂The content of (b) is preferably in the above range.

In the glass of the 4 th-1 embodiment, Gd₂O₃The content of (b) is preferably 2% or less. In addition, Gd₂O₃The lower limit of the content of (b) is preferably 0%.

In the glass of embodiment 4-1, Yb₂O₃The content of (b) is preferably 2% or less. In addition, Yb₂O₃The lower limit of the content of (b) is preferably 0%.

Yb₂O₃And La₂O₃、Gd₂O₃、Y₂O₃This is because the glass has a large specific gravity. When the specific gravity of the glass increases, the mass of the optical element increases. For example, if a large-mass lens is incorporated in an auto-focus type image pickup lens, the power required for driving the lens at the time of auto-focus increases, and the consumption of a battery becomes severe. Therefore, it is preferable to reduce Yb₂O₃To suppress an increase in the specific gravity of the glass.

The glass of embodiment 4-1 is preferably composed mainly of the above-mentioned glass component, i.e., SiO as an essential component₂、Na₂O, B as an optional component₂O₃、P₂O₅、Al₂O₃、TiO₂、Nb₂O₅、WO₃、Bi₂O₃、ZrO₂、Li₂O、K₂O、Cs₂O、MgO、CaO、SrO、BaO、ZnO、La₂O₃、Y₂O₃、Ta₂O₅、Sc₂O₃、HfO₂、Lu₂O₃、GeO₂、Gd₂O₃And Yb₂O₃The total content of the above glass components is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

The glass of embodiment 4-1 is preferably composed substantially of the above glass components, but may contain other components within a range not interfering with the action and effect of embodiment 4. In the invention 4, the inevitable impurities are not excluded.

(other Components)

(glass Properties)

< refractive index nd >

In the optical glass of embodiment 4-1, the refractive index nd is preferably 1.690 to 1.760. The refractive index nd may be 1.695 to 1.755, or 1.700 to 1.750. Nb is a component which relatively increases the refractive index nd₂O₅、TiO₂、ZrO₂、Ta₂O₅、La₂O₃. The component which relatively lowers the refractive index nd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂And O. By appropriately adjusting the contents of these components, the refractive index nd can be controlled.

Abbe number ν d >

In the optical glass of the embodiment 4-1, the abbe number ν d is preferably 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

Specific gravity of glass

The optical glass of embodiment 4-1 preferably has a specific gravity of 3.40 or less, and further 3.35 or less, 3.30 or less, and 3.25 or less in this orderMore preferably. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.10. The components capable of relatively increasing the specific gravity are BaO and La₂O₃、ZrO₂、Nb₂O₅、Ta₂O₅And the like. The component which relatively lowers the specific gravity is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O, and the like. The specific gravity can be controlled by adjusting the contents of these components.

< relative partial dispersion Pg, F >

The relative partial dispersion Pg, F of the optical glass of embodiment 4-1 has an upper limit of 0.5980, and 0.5970, 0.5960, 0.5950 and 0.5940 are more preferable. In addition, when the relative partial dispersion Pg, F is preferably low, the lower limit thereof is preferably 0.5780, and may be 0.5800, 0.5820, 0.5840, 0.5860. By setting the relative partial dispersions Pg, F to the above ranges, an optical glass suitable for high-order chromatic aberration correction can be obtained. Relative partial dispersion Pg, F can be adjusted by SiO₂、B₂O₃、TiO₂、Nb₂O₅Etc. are added.

The relative partial dispersion Pg of the optical glass of embodiment 4-1, the deviation Δ Pg of F, and the upper limit of F are preferably 0.0030, and more preferably 0.0025, 0.0020, and 0.0015 in this order. When the deviation Δ Pg, F is preferably low, the lower limit is preferably-0.0060, and further-0.0050, -0.0040, -0.0030, and-0.0020.

< liquid phase temperature >

The liquidus temperature LT of the optical glass of the embodiment 4-1 is preferably 1200 ℃ or lower, and more preferably 1190 ℃ or lower, 1180 ℃ or lower, and 1170 ℃ or lower in this order. By setting the liquidus temperature in the above range, the melting and forming temperature of the glass can be lowered, and as a result, erosion of a glass melting tool (for example, a crucible, a stirrer for molten glass, or the like) in the melting step can be reduced. The lower limit of the liquidus temperature LT is not particularly limited, but is generally about 1000 ℃. The liquidus temperature LT is determined according to the balance of the contents of all glass components. Wherein, SiO₂、B₂O₃、Li₂O、Na₂O、K₂The content of O or the like has a large influence on the liquidus temperature LT.

< glass transition temperature Tg >

The upper limit of the glass transition temperature Tg of the optical glass of embodiment 4-1 is preferably 670 ℃, and more preferably 650 ℃, 630 ℃ and 610 ℃. The lower limit of the glass transition temperature Tg is preferably 510 ℃ and more preferably 520 ℃, 525 ℃ and 530 ℃. The component which relatively lowers the glass transition temperature Tg is Li₂O、Na₂O、K₂O, and the like. La as a component which relatively increases the glass transition temperature Tg₂O₃、ZrO₂、Nb₂O₅And the like. By appropriately adjusting the contents of these components, the glass transition temperature Tg can be controlled.

< stability on reheating >

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

The optical glass of embodiment 4-1 can be produced in the same manner as in embodiment 1. The same procedure as in embodiment 1 can be applied to the manufacture of optical elements and the like.

4 th to 2 th embodiments

The optical glass of the 4 th to 2 th embodiments is characterized in that,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Is 62 to 84 percent.

In the optical glass of embodiment 4-2, SiO₂Relative to the content of Nb₂O₅And TiO₂Mass ratio of the total content of [ SiO ]₂/(Nb₂O₅+TiO₂)]Greater than 0.80. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]The lower limit of (B) is preferably 0.83, more preferably 0.85, 0.86, 0.87, 0.8The order of 8 is more preferred. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 1.50, and more preferably 1.40, 1.30 and 1.20. By mixing the mass ratio of SiO₂/(Nb₂O₅+TiO₂)]By setting the above range, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of the 4 th to 2 th embodiment, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Greater than 0.7. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is preferably 0.73, and more preferably 0.75, 0.77, and 0.79 in this order. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.15, and more preferably 1.13, 1.11, and 1.09. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass.

In the optical glass of embodiment 4-2, SiO₂、B₂O₃And P₂O₅Relative to the total content of Li₂O、Na₂O and K₂Mass ratio of total content of O [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]Is 1.45 to 4.55. Mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is preferably 1.70, and more preferably 1.72, 1.74 and 1.76 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 4.2, and more preferably 4.0, 3.95 and 3.9. By passingThe mass ratio of [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]With the above range, crystallization of the glass can be suppressed.

In the optical glass of embodiment 4-2, Na₂O content relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Is 0.45 or more. Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is preferably 0.46, and more preferably 0.47, 0.48, and 0.49 in this order. In addition, mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 0.97, and more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By mixing the mass ratio of [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of embodiment 4-2, SiO₂And Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Is 62 to 84 percent. Total content [ SiO₂+Nb₂O₅]The lower limit of (b) is preferably 63.0%, and more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, total content [ SiO₂+Nb₂O₅]The upper limit of (b) is preferably 83%, and more preferably 82.7%, 82.4%, and 82.1% in this order. By mixing the total content of [ SiO ]₂+Nb₂O₅]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed.

In the optical glass of embodiment 4-2, SiO₂Relative to Na₂Mass ratio of O content [ SiO ]₂/Na₂O]Preferably 2.5 to 8.5. Mass ratio [ SiO ]₂/Na₂O]The lower limit of (b) is more preferably 2.6, and further more preferably 2.65, 2.7, and 2.75 in this order. In addition, theMass ratio of [ SiO ]₂/Na₂O]The upper limit of (b) is more preferably 8.2, and further more preferably 8.0, 7.8, and 7.6 in this order. By mixing the mass ratio of SiO₂/Na₂O]With the above range, an optical glass having excellent homogeneity and stability during reheating can be obtained.

In the optical glass of embodiment 4-2, the content and ratio of the glass components other than those described above can be set in the same manner as in embodiment 4-1. The glass characteristics, the production of optical glass, the production of optical elements, and the like in embodiment 4-2 can be the same as those in embodiment 4-1.

4 th to 3 rd embodiments

The optical glass of the embodiment 4-3 has an Abbe number vd of 30 to 36,

the specific gravity of the composite material is below 3.4,

In the optical glass of the embodiment 4-3, Abbe number vd is 30 to 36. The Abbe number ν d may be set to 30.5-35.8 or 31-35.5. The component which relatively lowers the Abbe number vd is Nb₂O₅、TiO₂、ZrO₂、Ta₂O₅. The component capable of relatively increasing Abbe number vd is SiO₂、B₂O₃、Li₂O、Na₂O、K₂O、La₂O₃BaO, CaO, SrO. By appropriately adjusting the contents of these components, the abbe number ν d can be controlled.

In the optical glass of the embodiment 4 to 3, the specific gravity is 3.4 or less. The specific gravity is preferably 3.35 or less, more preferably 3.30 or less, and still more preferably 3.25 or less. The lower limit is not particularly limited as the specific gravity is smaller, but is generally about 3.10.

In the optical glass of the embodiment 4-3, the deviation Δ Pg of F from the partial dispersion Pg is 0.0030 or less. The upper limit of the deviation Δ Pg, F is preferably 0.0025, and more preferably 0.0020 and 0.0015 in this order. When the deviation Δ Pg, F is preferably low, the lower limit is preferably-0.0060, and further-0.0050, -0.0040, -0.0030, and-0.0020.

In general, F shows a tendency to decrease with an increase in abbe number vd with respect to partial dispersion Pg. Therefore, in the 4 th to 3 rd embodiments, the relative partial dispersions Pg, F are defined using Δ Pg, F described above, instead of the relative partial dispersions Pg, F itself. The abbe number ν d can provide an optical glass suitable for high-order chromatic aberration correction by setting Δ Pg and F to 0.0030 or less when ν d ≈ 30 and setting Δ Pg and F to 0.0010 or less when ν d ≈ 32, for example. Further, the specific gravity is 3.4 or less, more preferably 3.25 or less, whereby the weight of the optical element can be reduced.

Next, preferred embodiments of the content and ratio of the glass component in the optical glass of embodiments 4 to 3 will be described in detail below.

In the optical glass of the 4 th to 3 rd embodiments, SiO₂Relative to the content of Nb₂O₅And TiO₂Mass ratio of the total content of [ SiO ]₂/(Nb₂O₅+TiO₂)]Preferably greater than 0.80, and the lower limit thereof is more preferably in the order of 0.83, 0.85, 0.86, 0.87, 0.88. Mass ratio [ SiO ]₂/(Nb₂O₅+TiO₂)]The upper limit of (b) is preferably 1.50, and more preferably 1.40, 1.30 and 1.20. By mixing the mass ratio of SiO₂/(Nb₂O₅+TiO₂)]By setting the above range, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of the 4 th to 3 rd embodiments, SiO₂Relative to Na₂Mass ratio of O content [ SiO ]₂/Na₂O]Preferably 2.5 to 8.5. Mass ratio [ SiO ]₂/Na₂O]The lower limit of (b) is more preferably 2.6, and further more preferably 2.65, 2.7, and 2.75 in this order. In addition, mass ratio [ SiO ]₂/Na₂O]The upper limit of (b) is more preferably 8.2, and further more preferably 8.0, 7.8, and 7.6 in this order. By mixing the mass ratio of SiO₂/Na₂O]With the above range, an optical glass having excellent homogeneity and stability during reheating can be obtained.

The optical glass according to embodiment 4 to 3In, SiO₂、B₂O₃And P₂O₅Relative to the total content of Li₂O、Na₂O and K₂Mass ratio of total content of O [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]Preferably 1.45 to 4.55. Mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is more preferably 1.70, and further more preferably 1.72, 1.74 and 1.76 in this order. In addition, mass ratio [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is more preferably 4.2, and further more preferably 4.0, 3.95 and 3.9 in this order. By mixing the mass ratio of [ (SiO)₂+B₂O₃+P₂O₅)/(Li₂O+Na₂O+K₂O)]With the above range, crystallization of the glass can be suppressed.

In the optical glass of the embodiments 4 to 3, Na₂O content relative to Li₂O、Na₂O and K₂Mass ratio of total O content [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Preferably 0.45 or more. Mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The lower limit of (b) is more preferably 0.46, and still more preferably 0.47, 0.48, and 0.49 in this order. In addition, mass ratio [ Na ]₂O/(Li₂O+Na₂O+K₂O)]The upper limit of (b) is preferably 0.97, and more preferably 0.96, 0.90, 0.85, 0.80, 0.75, and 0.70 in this order. By mixing the mass ratio of [ Na ]₂O/(Li₂O+Na₂O+K₂O)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed, and an optical glass excellent in homogeneity and stability at the time of reheating can be obtained.

In the optical glass of the 4 th to 3 rd embodiments, SiO₂And Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]Preferably 62 to 84%. Total content [ SiO₂+Nb₂O₅]The lower limit of (b) is more preferably 63.0%, and still more preferably 63.5%, 64.0%, and 64.5% in this order. In addition, total content [ SiO₂+Nb₂O₅]The upper limit of (b) is more preferably 83%, and further more preferably 82.7%, 82.4%, and 82.1% in this order. By mixing the total content of [ SiO ]₂+Nb₂O₅]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass. Further, crystallization of the glass can be suppressed.

In the optical glass of the 4 th to 3 rd embodiments, TiO₂And Nb₂O₅Relative to SiO₂And B₂O₃Mass ratio of the total content of [ (TiO ]₂+Nb₂O₅)/(SiO₂+B₂O₃)]Preferably greater than 0.7. Mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The lower limit of (b) is more preferably 0.73, and still more preferably 0.75, 0.77 or 0.79. In addition, mass ratio [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]The upper limit of (b) is preferably 1.15, and more preferably 1.13, 1.11, and 1.09. By mixing the mass ratio of [ (TiO)₂+Nb₂O₅)/(SiO₂+B₂O₃)]Within the above range, the liquidus temperature can be lowered to improve the thermal stability of the glass.

In the optical glass of embodiment 4-3, the content and ratio of the glass components other than those described above can be set in the same manner as in embodiment 4-1. In addition, the glass characteristics other than those described above in embodiment 4-3, the production of optical glass, the production of optical elements, and the like may be the same as those in embodiment 4-1.

In embodiment 4-3, any of embodiments 4-1 or 4-2 may be employed.

Examples

EXAMPLE 1 OF THE INVENTION

Hereinafter, the invention 1 will be described in more detail with reference to examples. However, the invention 1 is not limited to the embodiment shown in the examples.

(example 1-1)

Glass samples having glass compositions shown in tables 1-1 to 1-5 and 1-23 were prepared in the following order, and various evaluations were performed. In tables 1-1 to 1-5 and 1-23, P is contained in order to show₂O₅The brought effect is that P is removed₂O₅The content of the other glass components was expressed as constant.

[ 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 composition of the obtained optical glass was each composition shown in tables 1-1 to 1-5, and 1-23, and then the raw materials were sufficiently mixed. The prepared raw materials (batch raw materials) thus obtained were put into a platinum crucible, heated at 1350 to 1400 ℃ for 2 hours to prepare molten glass, stirred to homogenize the molten glass, clarified, and then cast into a mold preheated to an appropriate temperature. The cast glass was subjected to heat treatment at a temperature 100 ℃ lower than 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 respective compositions were in accordance with those shown in tables 1-1 to 1-5 and 1-23.

[ processability ]

The obtained glass sample was cut and chipped to obtain a sample of 10mm × 10mm × 8 mm. The sample was heated in a heat treatment furnace set at a predetermined temperature for 5 minutes, and then taken out, and the glass sample was cooled. The end of the cooled glass sample was optically polished, and the inside of the glass sample was observed with an optical microscope (100 times). The number of internal defects (bright spots) in the glass sample was counted and converted into the number per g. The internal defect has a size in the range of 1 to 300 μm. Will remove P₂O₅Group of glass components other thanIn the same glass, without P₂O₅The number of internal defects of the glass is I [ pieces/g ]]Will contain P₂O₅The number of internal defects of the glass (2) is Ip [ pieces/g ]]When the ratio of Δ I to I-Ip is 1.0[ piece/g ]]The above is preferable. In addition, no cracks or streaks were observed in the glass samples.

[ 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 samples were measured for refractive indices nd, ng, nF and nC, Abbe number vd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ 70 and λ 5. The results are shown in tables 1-1 to 1-5 and 1-23.

(i) Refractive indices nd, ng, nF, nC and Abbe number vd

For the above annealed sample, refractive indices nd, ng, nF, nC were measured by a refractometry method according to JIS B7071-1, and Abbe number ν d was calculated based on the formula (1-7).

νd＝(nd-1)/(nF-nC)···(1-7)

(ii) Relative partial dispersion Pg, F

The relative partial dispersions Pg, F are calculated based on the expressions (1 to 6) using the respective refractive indices ng, nF, nC for g-ray, F-ray, C-ray.

Pg,F＝(ng-nF)/(nF-nC)···(1-6)

(iii) Specific gravity of

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 (DSC3300SA) manufactured by NETZSCH JAPAN.

(v)λ70、λ5

The annealed sample was processed into a thickness of 10mm and optically polished flat surfaces parallel to each other, and the spectral transmittance in a wavelength region of 280 to 700nm was measured. The spectral transmittance B/a was calculated by taking the intensity of a light ray perpendicularly incident on one optically polished plane as intensity a and the intensity of a light ray exiting from the other plane as intensity B. The wavelength with a spectral transmittance of 70% is λ 70, and the wavelength with a spectral transmittance of 5% is λ 5. The spectral transmittance also includes reflection loss of light on the sample surface.

(examples 1 to 2)

Glass samples having glass compositions shown in tables 1-6 to 1-22 were prepared in the same procedure as in example 1-1, and the glass component compositions were confirmed and the optical properties were measured in the same manner as in example 1-1. The results are shown in tables 1-6 to 1-22. The fluoride content is described as an external ratio. With respect to the workability, it was confirmed that the formability was good in any of the glass samples at the time of reheating.

[ tables 1 to 6]

Sample No.	1	2	3	4	5	6	7	8
									P2O5	1.41	2.13	0.94	1.42	0.97	0.96	2.35	0.94
SiO2	22.71	22.52	24.70	24.01	23.77	23.47	29.91	23.02
									Nb2O5	44.95	48.57	47.58	45.14	43.52	48.33	42.73	47.41
Li2O	-	4.95	-	-	-	0.80	4.96	-
									Na2O	13.15	3.99	12.74	12.59	13.53	11.69	11.15	11.05
K2O	-	5.49	-	-	-	-	0.67	3.11
									Cs2O	-	-	-	-	-	-	-	-
ZrO2	8.17	7.44	9.80	8.21	8.41	8.30	8.24	8.14
									TiO2	6.36	4.91	4.24	6.38	9.81	6.46		6.33
B2O3	-	-	-	-	-	-	-	-
									MgO	-	-	-	-	-	-	-	-
CaO	-	-	-	-	-	-	-	-
									SrO	-	-	-	-	-	-	-	-
BaO	-	-	-	-	-	-	-	-
									ZnO	-	-	-	-	-	-	-	-
La2O3	3.24	-	-	-	-	-	-	-
									Y2O3	-	-	-	2.26	-	-	-	-
WO3	-	-	-	-	-	-	-	-
									Total up to	100	100	100	100	100	100	100	100
F-(anion％)	-	-	-	-	-	-	-	-
									Refractive index (nd)	1.849 72	1.765 60	1.840 29	1.843 93	1.853 21	1.864 85	1.762 30	1.839 55
Abbe number (vd)	24.46	29.46	24.54	24.45	23.55	23.57	30.11	24.33
									Relative partial dispersion (Pg, F)	0.616	0.598	0.613	0.614	0.617	0.616	0.594	0.618
Specific gravity of	3.58	3.47	3.51	3.53	3.49	3.55	3.31	3.49
									Glass transition temperature Tg (. degree. C.)	654	559	653	556	631	626	570	628
λ70[nm]	416	422	412	418	420	438	381	420
									λ5[nm]	361	357	359	362	365	364	333	360
-0.00286×vd+0.68900	0.619	0.605	0.619	0.619	0.622	0.622	0.603	0.619
									SiO2+P2O5	24.12	24.65	25.64	25.43	24.74	24.43	32.26	23.96
SiO2+B2O3+p2O5	24.12	24.65	25.64	25.43	24.74	24.43	32.26	23.96
									Li2O+Na2O+K2O+Cs2O	13.15	14.43	12.74	12.59	13.53	12.49	16.78	14.16
Li2O+Na2O+K2O	13.15	14.43	12.74	12.59	13.53	12.49	16.78	14.16
									Nb2O5+TiO2	51.31	53.48	51.82	51.52	53.33	54.79	42.73	53.74
Nb2O5+TiO2+WO3+Bi2O3	51.31	53.48	51.82	51.52	53.33	54.79	42.73	53.74
									MgO+CaO+SrO+BaO+ZnO	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
MgO+CaO	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
									P2O5/(Nb2O5+TiO2)	0.027	0.040	0.018	0.028	0.018	0.018	0.055	0.017
P2O5/Nb2O5	0.031	0.044	0.020	0.031	0.022	0.020	0.055	0.020
									P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+ TiO2+WO3+Bi2O3)	0.022	0.031	0.015	0.022	0.015	0.014	0.039	0.014
P2O5/(Li2O+Na2O+K2O+Nb2O5)	0.024	0.034	0.016	0.025	0.017	0.016	0.039	0.015
									Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3)	0.876	0.908	0.918	0.876	0.816	0.882	1.000	0.882
SiO2/(SiO2+B2O3+p2O5)	0.942	0.914	0.963	0.944	0.961	0.961	0.927	0.961
									P2O5/(SiO2+P2O5)	0.058	0.086	0.037	0.056	0.039	0.039	0.073	0.039
P2O5/(SiO2+B2O3+P2O5)	0.058	0.086	0.037	0.056	0.039	0.039	0.073	0.039
									(MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O +K2O+Cs2O)	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
(Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+ P2O5)	0.545	0.585	0.497	0.495	0.547	0.511	0.520	0.591
									(Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2 +WO3+Bi2O3)	0.256	0.270	0.246	0.244	0.254	0.228	0.393	0.263
(SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3 +Bi2O3)	0.470	0.461	0.495	0.494	0.464	0.446	0.755	0.446
									ZrO2/(Nb2O5+TiO2+WO3+Bi2O3)	0.159	0.139	0.189	0.159	0.158	0.151	0.193	0.151

[ tables 1 to 7]

Sample No.	9	10	11	12	13	14	15	16
									P2O5	2.22	0.92	0.92	0.90	0.95	0.95	0.89	0.95
SiO2	23.51	22.54	22.68	22.18	23.26	23.24	21.93	23.27
									Nb2O5	50.69	46.42	46.71	45.68	47.91	47.86	45.17	47.92
Li2O	4.68	-	1.56	-	2.99	-	-	-
									Na2O	10.51	6.81	1.61	11.44	0.83	12.81	12.48	13.24
K2O	0.63	9.14	12.26	-	9.43	-	-	-
									Cs2O	-	-	-	-	-	-	-	-
ZrO2	7.77	7.97	8.02	7.84	8.23	8.22	7.75	8.23
									TiO2	-	6.20	6.24	6.10	6.40	6.39	3.02	6.40
B2O3	-	-	-	-	-	-	-	-
									MgO	-	-	-	-	-	0.54	-	-
CaO	-	-	-	-	-	-	-	-
									SrO	-	-	-	-	-	-	-	-
BaO	-	-	-	5.86	-	-	-	-
									ZnO	-	-	-	-	-	-	-	-
La2O3	-	-	-	-	-	-	-	-
									Y2O3	-	-	-	-	-	-	-	-
WO3	-	-	-	-	-	-	8.75	-
									Total up to	100	100	100	100	100	100	100	100
F-(anion％)	-	-	-	-	-	-	-	-
									Refractive index (nd)	1.818 81	1.805 76	1.804 17	1.863 18	1.829 98	1.856 08	1.844 62	1.854 32
Abbe number (vd)	27.09	25.67	26.07	24.03	25.28	23.77	24.30	23.74
									Relative partial dispersion (Pg, F)	0.604	0.610	0.608	0.614	0.612	0.612	0.615	0.615
Specific gravity of	3.48	3.40	3.38	3.66	3.42	3.53	3.66	3.53
									Glass transition temperature Tg (. degree. C.)	567	610	585	654	582	635	622	645
λ70[nm]	396	402	399	423	414	433	425	421
									λ5[nm]	340	353	352	362	356	363	363	362
-0.00286×vd+0.68900	0.612	0.616	0.614	0.620	0.617	0.621	0.620	0.621
									SiO2+P2O5	25.73	23.46	23.60	23.08	24.21	24.19	22.82	24.22
SiO2+B2O3+P2O5	25.73	23.46	23.60	23.08	24.21	24.19	22.82	24.22
									Li2O+Na2O+K2O+Cs2O	15.82	15.95	15.43	11.44	13.25	12.81	12.48	13.24
Li2O+Na2O+K2O	15.82	15.95	15.43	11.44	13.25	12.81	12.48	13.24
									Nb2O5+TiO2	50.69	52.62	52.95	51.78	54.31	54.25	48.19	54.32
Nb2O5+TiO2+WO3+Bi2O3	50.69	52.62	52.95	51.78	54.31	54.25	56.94	54.32
									MgO+CaO+SrO+BaO+ZnO	0.00	0.00	0.00	5.86	0.00	0.54	0.00	0.00
MgO+CaO	0.00	0.00	0.00	0.00	0.00	0.54	0.00	0.00
									P2O5/(Nb2O5+TiO2)	0.044	0.017	0.017	0.017	0.017	0.018	0.018	0.017
P2O5/Nb2O5	0.044	0.020	0.020	0.020	0.020	0.020	0.020	0.020
									P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+ TiO2+WO3+Bi2O3)	0.033	0.013	0.013	0.014	0.014	0.014	0.013	0.014
P2O5/(Li2O+Na2O+K2O+Nb2O5)	0.033	0.015	0.015	0.016	0.016	0.016	0.015	0.016
									Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3)	1.000	0.882	0.882	0.882	0.882	0.882	0.793	0.882
SiO2/(SiO2+B2O3+P2O5)	0.914	0.961	0.961	0.961	0.961	0.961	0.961	0.961
									P2O5/(SiO2+P2O5)	0.086	0.039	0.039	0.039	0.039	0.039	0.039	0.039
P2O5/(SiO2+B2O3+P2O5)	0.086	0.039	0.039	0.039	0.039	0.039	0.039	0.039
									(MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O +K2O+Cs2O)	0.000	0.000	0.000	0.512	0.000	0.042	0.000	0.000
(Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+ P2O5)	0.615	0.680	0.654	0.496	0.547	0.530	0.547	0.547
									(Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2 +WO3+Bi2O3)	0.312	0.303	0.291	0.221	0.244	0.236	0.219	0.244
(SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3 +Bi2O3)	0.508	0.446	0.446	0.446	0.446	0.446	0.401	0.446
									ZrO2/(Nb2O5+TiO2+WO3+Bi2O3)	0.153	0.151	0.151	0.151	0.152	0.152	0.136	0.152

[ tables 1 to 8]

Sample No.	17	18	19	20	21	22	23	24
									P2O5	0.92	0.95	0.91	0.96	0.94	0.92	0.95	5.67
SiO2	22.51	22.54	22.43	21.07	25.38	22.47	23.44	20.82
									Nb2O5	44.65	48.08	46.20	48.41	47.36	54.85	46.46	47.82
Li2O	-	-	-	-	-	-	-	-
									Na2O	12.81	13.29	11.57	13.38	11.86	12.79	13.33	13.22
K2O	-	-	-	-	-	-	-	-
									Cs2O	-	-	-	-	-	-	-	-
ZrO2	7.96	8.25	7.93	8.31	8.13	7.95	8.28	8.21
									TiO2	5.16	6.42	6.17	6.47	6.33	1.03	6.44	4.26
B2O3	-	0.47	-	1.41	-	-	-	-
									MgO	-	-	-	-	-	-	-	-
CaO	-	-	0.43	-	-	-	-	-
									SrO	-	-	0.80	-	-	-	-	-
BaO	-	-	3.55	-	-	-	-	-
									ZnO	-	-	-	-	-	-	1.09	-
La2O3	-	-	-	-	-	-	-	-
									Y2O3	-	-	-	-	-	-	-	-
WO3	5.99	-	-	-	-	-	-	-
									Total up to	100	100	100	100	100	100	100	100
F-(anion％)	-	-	-	-	-	-	-	-
									Refractive index (nd)	1.847 90	1.857 93	1.862 53	1.862 28	1.849 14	1.857 14	1.850 35	1.834 63
Abbe number (vd)	24.02	23.60	24.05	23.43	23.75	23.98	24.06	24.24
									Relative partial dispersion (Pg, F)	0.617	0.617	0.615	0.616	0.617	0.613	0.617	0.616
Specific gravity of	3.60	3.53	3.64	3.54	3.50	3.59	3.53	3.49
									Glass transition temperature Tg (. degree. C.)	628	632	654	620	645	626	620	644
λ70[nm]	426	427	422	430	435	421	417	466
									λ5[nm]	363	364	362	363	364	357	360	364
-0.00286×vd+0.68900	0.620	0.622	0.620	0.622	0.621	0.620	0.620	0.620
									SiO2+P2O5	23.43	23.49	23.34	22.03	26.32	23.39	24.39	26.49
SiO2+B2O3+P2O5	23.43	23.96	23.34	23.44	26.32	23.39	24.39	26.49
									Li2O+Na2O+K2O+Cs2O	12.81	13.29	11.57	13.38	11.86	12.79	13.33	13.22
Li2O+Na2O+K2O	12.81	13.29	11.57	13.38	11.86	12.79	13.33	13.22
									Nb2O5+TiO2	49.81	54.50	52.37	54.88	53.69	55.88	52.90	52.08
Nb2O5+TiO2+WO3+Bi2O3	55.80	54.50	52.37	54.88	53.69	55.88	52.90	52.08
									MgO+CaO+SrO+BaO+ZnO	0.00	0.00	4.78	0.00	0.00	0.00	1.09	0.00
MgO+CaO	0.00	0.00	0.43	0.00	0.00	0.00	0.00	0.00
									P205/(Nb2O5+TiO2)	0.018	0.017	0.017	0.017	0.018	0.016	0.018	0.109
P2O5/Nb2O5	0.021	0.020	0.020	0.020	0.020	0.017	0.020	0.119
									P2O5/(Li2O+Na2O+K2O+Cs2O+Nb2O5+ TiO2+WO3+Bi2O3)	0.013	0.014	0.014	0.014	0.014	0.013	0.014	0.087
P2O5/(Li2O+Na2O+K2O+Nb2O5)	0.016	0.015	0.016	0.016	0.016	0.014	0.016	0.093
									Nb2O5/(Nb2O5+TiO2+WO3+Bi2O3)	0.800	0.882	0.882	0.882	0.882	0.982	0.878	0.918
SiO2/(SiO2+B2O3+P2O5)	0.961	0.941	0.961	0.899	0.964	0.961	0.961	0.786
									P2O5/(SiO2+P2O5)	0.039	0.040	0.039	0.044	0.036	0.039	0.039	0.214
P2O5/(SiO2+B2O3+P2O5)	0.039	0.040	0.039	0.041	0.036	0.039	0.039	0.214
									(MgO+CaO+SrO+BaO+ZnO)/(Li2O+Na2O +K2O+Cs2O)	0.000	0.000	0.413	0.000	0.000	0.000	0.082	0.000
(Li2O+Na2O+K2O+Cs2O)/(SiO2+B2O3+ P2O5)	0.547	0.555	0.496	0.571	0.451	0.547	0.547	0.499
									(Li2O+Na2O+K2O+Cs2O)/(Nb2O5+TiO2 +WO3+Bi2O3)	0.230	0.244	0.221	0.244	0.221	0.229	0.252	0.254
(SiO2+B2O3+P2O5)/(Nb2O5+TiO2+WO3 +Bi2O3)	0.420	0.440	0.446	0.427	0.490	0.419	0.461	0.509
									ZrO2/(Nb2O5+TiO2+WO3+Bi2O3)	0.143	0.151	0.151	0.151	0.151	0.142	0.157	0.158

[ tables 1 to 9]

[ tables 1 to 10]

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

[ tables 1 to 11]

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

[ tables 1 to 12]

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

[ tables 1 to 13]

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

[ tables 1 to 14]

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

[ tables 1 to 15]

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

[ tables 1 to 16]

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

[ tables 1 to 17]

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

[ tables 1 to 18]

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

[ tables 1 to 19]

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

[ tables 1 to 20]

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

[ tables 1 to 21]

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

[ tables 1 to 22]

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

(examples 1 to 3)

Using each of the optical glasses produced in examples 1-1 and 1-2, 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 produced is a lenticular lens, a biconcave lens, a plano-convex lens, a plano-concave lens, a concave meniscus lens, a convex meniscus lens, or the like.

The various lenses can be combined with lenses made of other types of optical glass to favorably correct the secondary chromatic aberration.

Further, since glass has a low specific gravity, each lens is lighter than a lens having the same optical characteristics and size, and therefore, can be suitably used for various image pickup apparatuses, particularly for an automatic focusing type image pickup apparatus for the reason of energy saving and the like. Similarly, prisms were produced using the various optical glasses produced in examples 1-1 and 1-2.

EXAMPLE 2 of the invention

Hereinafter, the invention 2 will be described in more detail with reference to examples. However, the invention 2 is not limited to the embodiment shown in the example.

(example 2-1)

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

[ 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 composition of the obtained optical glass was each composition shown in tables 2-1 to 2-4, and the raw materials were thoroughly mixed. The prepared raw materials (batch raw materials) thus obtained are put into a platinum crucible, heated at 1350 to 1450 ℃ for 2 to 5 hours to produce molten glass, stirred to homogenize the molten glass, clarified, and then cast into a mold preheated to an appropriate temperature. The cast glass was subjected to heat treatment at a temperature 100 ℃ lower than 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 were consistent with those shown in tables 2-1 to 2-4.

[ 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 samples were measured for refractive indices nd, ng, nF and nC, Abbe number vd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ 70 and λ 5. The results are shown in tables 2-1 to 2-4.

(i) Refractive indices nd, ng, nF, nC and Abbe number vd

For the above annealed sample, refractive indices nd, ng, nF, nC were measured by a refractive index measuring method in JIS standard JIS B7071-1, and Abbe number ν d was calculated based on the following formula.

νd＝(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg, F

The relative partial dispersions Pg, F are calculated based on the following equation using the refractive indices ng, nF, nC for g-ray, F-ray, and C-ray.

Pg,F＝(ng-nF)/(nF-nC)

(iii) Deviation Δ Pg, F 'of relative partial dispersion Pg, F'

The relative partial dispersions Pg, F and abbe number ν d were used, and calculated based on the following formula.

ΔPg,F’＝Pg,F+(0.00286×νd)-0.68900

(iv) Specific gravity of

Specific gravity was measured by the archimedes method.

(v) Glass transition temperature Tg

(ⅵ)λ70、λ5

The annealed sample was processed into a thickness of 10mm and optically polished flat surfaces parallel to each other, and the spectral transmittance in a wavelength region of 280 to 700nm was measured. The spectral transmittance B/a was calculated by setting the intensity of light perpendicularly incident on one optically polished plane as intensity a and the intensity of light exiting from the other plane as intensity B. The spectral transmittance B/a was calculated by setting λ 70 as the wavelength at which the spectral transmittance was 70%. The wavelength at which the spectral transmittance is 5% is λ 5. The spectral transmittance also includes reflection loss of light on the sample surface.

[ stability upon reheating ]

The obtained glass sample was cut to obtain chips of 10mm × 10mm × 7.5mm in size. The chips are heated for 5 minutes in a test furnace set to a temperature 200 to 220 ℃ higher than the glass transition temperature Tg of the glass sample. The number of crystals per 1 chip was measured by an optical microscope (observation magnification: 40 to 200 times). In addition, the presence or absence of crystals was visually confirmed. The number of crystals per 1 chip was evaluated as a, the number of crystals per 1 chip was evaluated as B, and the number of crystals per 1 chip was evaluated as C. The results are shown in tables 2-1 to 2-4.

[ Table 2-1]

[ tables 2-2]

[ tables 2 to 3]

[ tables 2 to 4]

(example 2-2)

Using each of the optical glasses produced in example 2-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as polishing to produce various lenses.

Further, since glass has a low specific gravity, each lens is lighter than a lens having the same optical characteristics and size, and therefore, can be suitably used for various image pickup apparatuses, particularly for an automatic focusing type image pickup apparatus for the reason of energy saving and the like. Similarly, prisms were produced using the various optical glasses produced in example 2-1.

EXAMPLE 3 of the invention

Hereinafter, the invention 3 will be described in more detail with reference to examples. However, the 3 rd invention is not limited to the embodiment shown in the examples.

(example 3-1)

Glass samples having glass compositions shown in tables 3-1 and 3-2-1 to 3-2-2 were prepared in the following order, and various evaluations were performed.

[ 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 composition of the obtained optical glass was each composition shown in table 3-1, and the raw materials were thoroughly mixed. The prepared raw materials (batch raw materials) thus obtained were put into a platinum crucible, heated at 1350 to 1400 ℃ for 2 hours to prepare molten glass, stirred to homogenize the molten glass, clarified, and then cast into a mold preheated to an appropriate temperature. The cast glass was subjected to heat treatment at a temperature 100 ℃ lower than 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 of the obtained glass samples were measured by inductively coupled plasma emission spectrometry (ICP-AES), and it was confirmed that the compositions were consistent with those shown in Table 3-1.

[ stability upon reheating ]

The obtained glass sample was cut into a size of 1cm × 1cm × 0.8cm, heated in a 1 st test furnace set to the glass transition temperature Tg of the glass sample for 10 minutes, and further heated in a 2 nd test furnace set to a temperature 140 to 250 ℃ higher than the glass transition temperature Tg thereof for 10 minutes. Then, the presence or absence of the crystal was confirmed by an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1g was measured. The presence or absence of cloudiness of the glass was visually confirmed. The number of crystals per 1g was 20 or less, and no white turbidity was observed, and the number of crystals per 1g was determined as "good", and the number of crystals per 1g was more than 20, or at least one of white turbidity was observed as "bad". The results are shown in tables 3-3-1 to 3-3-2.

[ 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 samples were measured for refractive indices nd, ng, nF and nC, Abbe number vd, relative partial dispersion Pg, F, specific gravity, glass transition temperature Tg, λ 80, λ 70 and λ 5. The results are shown in tables 3-3-1 to 3-3-2.

(i) Refractive indices nd, ng, nF, nC and Abbe number vd

νd＝(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg, F

Pg,F＝(ng-nF)/(nF-nC)

(iii) Deviation Δ Pg, F of relative partial dispersion Pg, F

ΔPg,F＝Pg,F+(0.0018×νd)-0.6483

(iv) Specific gravity of

Specific gravity was measured by the archimedes method.

(v) Liquid phase temperature LT

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

(vi) Glass transition temperature Tg

(vii)λ80、λ70、λ5

The annealed sample was processed into a thickness of 10mm and optically polished flat surfaces parallel to each other, and the spectral transmittance in a wavelength region of 280 to 700nm was measured. The spectral transmittance B/a was calculated by setting the intensity of light that perpendicularly entered one optically polished plane as intensity a and the intensity of light that exited the other plane as intensity B. The spectral transmittance B/a was calculated by setting the wavelength at which the spectral transmittance was 80% to λ 80. The wavelength with a spectral transmittance of 70% is λ 70, and the wavelength with a spectral transmittance of 5% is λ 5. The spectral transmittance also includes reflection loss of light on the sample surface.

[ Table 3-1]

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

(example 3-2)

Using each of the optical glasses produced in example 3-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as polishing, thereby producing various lenses.

Further, since glass has a low specific gravity, each lens is lighter than a lens having the same optical characteristics and size, and therefore, can be suitably used for various image pickup apparatuses, particularly for an automatic focusing type image pickup apparatus for the reason of energy saving and the like. Similarly, prisms were produced using the various optical glasses produced in example 3-1.

Example 4 of the invention

Hereinafter, the invention of claim 4 will be described in more detail with reference to examples. However, the 4 th invention is not limited to the embodiment shown in the examples.

(example 4-1)

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

[ 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 composition of the obtained optical glass was each composition shown in tables 4-1 to 4-4, and the raw materials were thoroughly mixed. The prepared raw materials (batch raw materials) thus obtained are put into a platinum crucible, heated at 1350 to 1450 ℃ for 2 to 3 hours to prepare molten glass, stirred to homogenize the molten glass, clarified, and then cast into a mold preheated to an appropriate temperature. The cast glass was subjected to heat treatment at a temperature of Tg. + -. 10 ℃ 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 were consistent with those shown in tables 4-1 to 4-4.

[ 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 samples were measured for refractive indices nd, ng, nF and nC, Abbe number vd, relative partial dispersion Pg, F, deviation Δ Pg, F, specific gravity, glass transition temperature Tg, λ 80, λ 70 and λ 5. The results are shown in tables 4-1 to 4-4. In addition, since the glass sample obtained in comparative example A, B was found to have remarkable striae and very unevenness, the refractive index nd, the abbe number vd, the relative partial dispersions Pg, F, and the deviations Δ Pg, F could not be measured.

(i) Refractive indices nd, ng, nF, nC and Abbe number vd

νd＝(nd-1)/(nF-nC)

(ii) Relative partial dispersion Pg, F

Pg,F＝(ng-nF)/(nF-nC)

(iii) Deviation Δ Pg, F of relative partial dispersion Pg, F

ΔPg,F＝Pg,F+(0.0018×νd)-0.6483

(iv) Specific gravity of

Specific gravity was measured by the archimedes method.

(v) liquid phase temperature LT

(vi) Glass transition temperature Tg

(vii)λ80、λ70、λ5

[ stability upon reheating ]

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

[ evaluation of vitrification ]

The presence or absence of crystals in the obtained glass sample was confirmed by the naked eye or by an optical microscope (observation magnification: 40 times), and the glass sample was evaluated as "acceptable" if no crystals were present and "unacceptable" if any.

Each of the optical glasses of example 4-1 was also optically homogeneous, and no striae were observed. On the other hand, the glasses of comparative examples A and B, which were produced under the same conditions as in example 4-1, were observed to have marked striae and very uneven appearance. Also in comparative example C, crystal formation was visually confirmed.

(example 4-2)

Using each of the optical glasses produced in example 4-1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as polishing, thereby producing various lenses.

Further, since glass has a low specific gravity, each lens is lighter than a lens having the same optical characteristics and size, and therefore, can be suitably used for various image pickup apparatuses, particularly for an automatic focusing type image pickup apparatus for the reason of energy saving and the like. Similarly, prisms were produced using the various optical glasses produced in example 4-1.

It should be understood that the embodiments disclosed herein are all exemplary and not limiting. The scope of the invention is indicated by the appended claims, rather than 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 1 st to 4 th inventions can be produced by adjusting the composition of the glass composition shown in the above example as described in the specification.

It is needless to say that 2 or more of the items exemplified in the description or described as the preferable ranges may be arbitrarily combined.

Claims

1. Silicate glass with Abbe number vd of 20-35 and P content₂O₅And Nb₂O₅And the relative partial dispersion Pg, F satisfies the following formula (1-1),

Pg,F≤-0.00286×νd+0.68900···(1-1)。

2. silicate glass with Abbe number vd of 20-35 and P content₂O₅And Nb₂O₅And Nb₂O₅Relative to the content of Nb₂O₅、TiO₂、WO₃And Bi₂O₃Mass ratio of the total content of [ Nb ]₂O₅/(Nb₂O₅+TiO₂+WO₃+Bi₂O₃)]Greater than 0.6110.

3. An optical glass having an Abbe's number vd of 26.0 or more,

SiO₂is more than 0 mass% and less than 40 mass%,

TiO₂the content of (B) is 0 to 15% by mass,

Nb₂O₅the content of (B) is 25 to 45 mass%,

ZrO₂the content of (B) is more than 0 mass%,

PbO, CdO and As₂O₃The content of (b) is 0.01 mass% or less, respectively.

4. An optical glass, wherein,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

the optical glass satisfies 1 or more of the following (a) and (b):

5. An optical glass, wherein,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

the optical glass satisfies 1 or more of the following (c) and (d):

6. An optical glass, wherein,

TiO₂and total content of BaO [ TiO ]₂+BaO]Less than 10% by mass,

the optical glass satisfies 1 or more of the following (e) and (f):

7. An optical glass having an Abbe's number vd of 30 to 36, a specific gravity of 3.19 or less, and a deviation Δ Pg of relative partial dispersion Pg, F of 0.0015 or less.

8. An optical glass, wherein,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]62 to 84 mass%.

9. An optical glass, wherein,

SiO₂and Nb₂O₅Total content of [ SiO ]₂+Nb₂O₅]62 to 84 mass%.

10. An optical glass having an Abbe's number vd of 30 to 36, a specific gravity of 3.4 or less, and a deviation Δ Pg of relative partial dispersion Pg, F of 0.0030 or less.

11. An optical glass formed from the glass according to claim 1 or 2.

12. An optical element formed of the optical glass as defined in any one of claims 3 to 11.