CN106966589B

CN106966589B - Glass, glass material for press molding, optical element blank, and optical element

Info

Publication number: CN106966589B
Application number: CN201610837080.5A
Authority: CN
Inventors: 根岸智明
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2014-11-07
Filing date: 2015-11-06
Publication date: 2020-06-16
Anticipated expiration: 2035-11-06
Also published as: CN111233318A; CN106255672B; JP6587286B2; CN106255672A; JPWO2016072523A1; TWI610900B; WO2016072523A1; CN106966589A; TW201623174A

Abstract

One embodiment of the present invention relates to a glass which is an oxide glass and is represented by cation%, B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺The total content of (a) is 90% or more, the Abbe number ν d is in the range of 39.5 to 41.5, and the refractive index nd satisfies the following formula (1) with respect to the Abbe number ν d: nd is not less than 2.0927 and 0.0058 x ν D … (1), and for a specific cationic component, the sum D of the values obtained by multiplying the content of each cationic component by a specific coefficient satisfies the following expression (B) with respect to the refractive index nd: d is less than or equal to 6.242 x nd-6.8042 … (B). According to the present invention, it is possible to provide glass having optical characteristics useful in an optical system and contributing to weight reduction of an optical element.

Description

Glass, glass material for press molding, optical element blank, and optical element

The present application is a divisional application of the invention patent application having chinese application No. 201580009854.9, entitled "glass, glass material for press molding, optical element blank, and optical element", filed on 2015, 11/6.

Technical Field

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

Background

By combining a lens made of high-refractive-index low-dispersion glass with a lens made of ultra-low-dispersion glass or the like to form a cemented lens, it is possible to make the optical system compact while correcting chromatic aberration. Therefore, the high-refractive-index low-dispersion glass occupies a very important position as an optical element constituting a projection optical system such as an imaging optical system and a projector. Such high-refractive-index low-dispersion glasses are described in, for example, patent documents 1 to 20.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007 and 063071;

patent document 2: japanese patent laid-open publication No. 2007-230835;

patent document 3: japanese patent laid-open No. 2007-249112;

patent document 4: japanese patent laid-open publication No. 2007-261826;

patent document 5: japanese patent laid-open publication No. 2003-267748;

patent document 6: japanese patent laid-open No. 2009-203083;

patent document 7: japanese patent laid-open publication No. 2011-230992;

patent document 8: japanese patent laid-open publication No. 2012 and 025638;

patent document 9: japanese patent laid-open publication No. Sho 54-090218;

patent document 10: japanese patent laid-open No. 56-160340;

patent document 11: japanese patent laid-open No. 2001-348244;

patent document 12: japanese patent laid-open No. 2008-001551;

patent document 13: japanese Kokai publication Nos. 2013-536791;

patent document 14: WO 10/053214;

patent document 15: japanese patent laid-open publication No. 2012 and 180278;

patent document 16: japanese patent laid-open publication No. 2012 and 236754;

patent document 17: japanese patent laid-open publication No. 2014-084235;

patent document 18: japanese patent laid-open publication No. 2014-062025;

patent document 19: japanese patent laid-open publication No. 2014-062026;

patent document 20: japanese patent laid-open publication No. 2011-93780.

Disclosure of Invention

Problems to be solved by the invention

For glasses for optical elements, an optical characteristic map (also referred to as an abbe chart) is widely used in order to show the distribution of optical characteristics. The optical characteristic map is prepared such that the abbe number ν d is taken on the horizontal axis, the refractive index nd is taken on the vertical axis, the abbe number ν d increases from the right side to the left side of the horizontal axis, and the refractive index increases from the lower side to the upper side of the vertical axis. In the following, unless otherwise specified, the refractive index and abbe number refer to the refractive index nd of helium d-line (wavelength 587.56nm) and abbe number ν d of helium d-line (wavelength 587.56 nm).

In the optical characteristic map, as for the optical characteristics of the high-refractive-index low-dispersion glass (high nd high ν d glass), the refractive index increases as the abbe number becomes smaller, and the refractive index decreases as the abbe number increases, that is, a distribution that generally rises to the right is shown. This is considered to be due to the following reason.

High refractive index low dispersion glass often contains rare earth oxides such as boron oxide and lanthanum oxide. In such a glass, the content of the rare earth oxide is increased in order to increase the refractive index without decreasing the abbe number. However, in conventional high refractive index low dispersion glass, when the content of rare earth oxide is increased, the thermal stability of the glass is lowered, and the glass tends to devitrify during the process of producing the glass. Therefore, in the conventional high-refractive-index low-dispersion glass, it is difficult to suppress devitrification of the glass to be used as an optical element material and to increase the abbe number and the refractive index together. This is considered to be the reason why the conventional high-refractive-index low-dispersion glass shows such a distribution in the optical characteristic map.

On the other hand, in designing an optical system, a glass having a high refractive index and a large abbe number (low dispersion) is a material for an optical element which is extremely effective for correction of chromatic aberration, high functionality, and compactness of the optical system. Therefore, it is very significant to set a straight line rising to the right on the optical characteristic map and provide glass having a higher refractive index (region located on the left side of the straight line on the map) on and above the straight line.

From the above points, a glass having an Abbe's number ν d of 39.5 to 41.5 and a refractive index nd of 2.0927 to 0.0058 × ν d or more with respect to the Abbe's number, that is, a glass satisfying a relationship of n d. 2.0927 to 0.0058 × ν d is a high-refractive-index low-dispersion glass useful in an optical system.

In contrast, in the glasses described in patent documents 1 to 20, the high-refractive-index low-dispersion glass having an Abbe's number ν d in the range of 39.5 to 41.5 and satisfying the relation nd ≧ 2.0927-0.0058 × ν d contains any of Gd and Ta. However, Gd and Ta are rare and high-value elements, but their demands in various industrial fields have been increasing in recent years, and therefore their supply is insufficient for the market demand. Therefore, from the viewpoint of stable supply of the high-refractivity low-dispersion glass, it is desirable to reduce the content of Gd and Ta in the high-refractivity low-dispersion glass.

On the other hand, in the glass composition of conventional high refractive index low dispersion glass, when it is intended to reduce the content of Gd and Ta while maintaining both optical characteristics and thermal stability, the light absorption edge on the short wavelength side of the glass tends to be longer and the transmittance of ultraviolet rays tends to be greatly reduced.

In order to correct chromatic aberration, a method of manufacturing a cemented lens by manufacturing a plurality of lenses using glasses having different optical characteristics and bonding the lenses is known. In the process of manufacturing cemented lenses, an ultraviolet curing adhesive is generally used in order to bond the lenses to each other. The details are as follows. An ultraviolet-curable adhesive is applied to the surfaces to which the lenses are bonded, and the lenses are bonded. In this case, an extremely thin coating layer of an ultraviolet-curable adhesive is usually formed between the lenses. Next, the ultraviolet-curable adhesive is cured by irradiating the coating layer with ultraviolet light through a lens. Therefore, when the ultraviolet transmittance of the lens is low, a sufficient amount of ultraviolet light cannot be transmitted to the coating layer through the lens, and curing becomes insufficient. Or curing may take a long time.

In addition, in the case where the lens is bonded and fixed to the lens barrel using an ultraviolet-curable adhesive, similarly, when the ultraviolet transmittance of the lens is low, curing becomes insufficient or it takes a long time to cure.

Therefore, in order to produce a glass having transmittance characteristics suitable for the production of an optical system, it is desirable to suppress the wavelength of the short-wavelength side light absorption edge of the glass from increasing.

An object of one embodiment of the present invention is to provide glass having an Abbe's number ν d of 39.5 to 41.5, satisfying the relation nd ≥ 2.0927-0.0058 × ν d, being stably supplied, and being suitable for production of an optical system.

One embodiment of the present invention relates to a glass (hereinafter referred to as "glass a") which is an oxide glass and is expressed in terms of cation%,

B³⁺and Si⁴⁺The total content of (B) is 43 to 65%,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺The total content of (a) is 25 to 50%,

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺and W⁶⁺The total content of (a) is 3 to 12%,

Zr⁴⁺the content of (a) is 2-8%,

B³⁺and Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴ ⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.75,

B³⁺and Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴ ⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value of the water quality index is below 9.00,

Zn²⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) The rate of the reaction is less than 0.2,

La³⁺content of (D) relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { La³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.50 to 0.95,

Y³⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Y }³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 to 0.50,

Gd³⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) The value of the water content is less than 0.10,

Nb⁵⁺relative to the content of Nb⁵⁺、Ti⁴⁺And W⁶⁺The cation ratio of the total content of (1) { N b⁵⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) The value of the water content is more than 0.80,

Ta⁵⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵ ⁺+W⁶⁺) The value of the water content is less than 0.2,

the range of Abbe number vd is 39.5-41.5, and the refractive index nd relative to Abbe number vd satisfies the following formula (1):

nd≥2.0927-0.0058×νd…(1)。

one embodiment of the present invention relates to a glass (hereinafter referred to as "glass B") which is an oxide glass and is represented by mass%,

B₂O₃and SiO₂The total content of (a) is 17.5 to 35%,

La₂O₃、Y₂O₃、Gd₂O₃and Yb₂O₃The total content of (a) is 45 to 70%,

Nb₂O₅、TiO₂、Ta₂O₅and WO₃The total content of (a) is 3 to 16%,

ZrO₂the content of (a) is 2-10%,

B₂O₃and SiO₂The total content of (A) to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.2 to 0.5,

B₂O₃and SiO₂The total content of (B) relative to Nb₂O₅、TiO₂、Ta₂O₅And WO₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The value of the water quality index is below 2.8,

content of ZnO relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (1), (ZnO/(La))₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) The (A) is less than 0.10,

La₂O₃relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { La }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.55 to 0.98,

Y₂O₃relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { Y }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.02 to 0.45,

Gd₂O₃relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃(iii) the total content of (a) to (b) { Gd }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) The value of the water content is less than 0.10,

Nb₂O₅relative to the content of Nb₂O₅、TiO₂And WO₃Mass ratio of the total content of (1) { Nb }₂O₅/(Nb₂O₅+TiO₂+WO₃) The value of the water content is more than 0.81,

Ta₂O₅relative to the content of Nb₂O₅、TiO₂、Ta₂O₅And WO₃Mass ratio of the total content of (1) { Ta }₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The value of the water content is less than 0.3,

the range of Abbe number vd is 39.5-41.5, and the refractive index nd relative to Abbe number vd satisfies the above formula (1).

The glass A is glass with Abbe number vd ranging from 39.5 to 41.5 and satisfying nd being not less than 2.0927-0.0058 x vd, and comprises Gd³⁺Each component (i.e., La) of³⁺、Y³⁺、Gd³⁺、Yb³⁺) And contains Ta⁵⁺Each component (i.e., Nb)⁵ ⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺) In the above range, Gd is contained in the denominator or numerator³⁺、Ta⁵⁺The above cation ratio. Therefore, the ratio of Gd and Ta in the glass composition decreases. By adjusting the composition satisfying the above-described content, total content, and cation ratio among the compositions satisfying the above-described total content and cation ratio, the glass can achieve both high thermal stability (property of being less susceptible to devitrification) and suppression of a longer wavelength of a light absorption edge on a shorter wavelength side.

The glass B is glass with Abbe number vd ranging from 39.5 to 41.5 and satisfying the relation that nd is not less than 2.0927-0.0058 x vd, and comprises Gd₂O₃Each component (i.e., La) of₂O₃、Y₂O₃、Gd₂O₃、Yb₂O₃) And contains Ta₂O₅Each component (i.e., Nb)₂O₅、Ti O₂、Ta₂O₅、WO₃) In the above range, Gd is contained in the denominator or numerator₂O₃、Ta₂O₅The above mass ratio. Therefore, the ratio of Gd and Ta in the glass composition decreases. By adjusting the composition satisfying the above-described content, total content, and mass ratio among the compositions satisfying the above-described total content and mass ratio, the glass can achieve both high thermal stability (property of being less susceptible to devitrification) and suppression of a longer wavelength of a light absorption edge on a shorter wavelength side.

According to one embodiment of the present invention, it is possible to provide glass having optical characteristics useful in an optical system, capable of being stably supplied, and having transmittance characteristics suitable for manufacturing the optical system. Further, according to an aspect of the present invention, a glass material for press molding, an optical element blank, and an optical element, each of which is formed of the above glass, can be provided.

Further, weight reduction of optical elements constituting a projection optical system such as an imaging optical system and a projector is desired. The reduction in weight of the optical element is related to the reduction in weight of an imaging optical system and a projection optical system incorporating the optical element. For example, when a heavy optical element is incorporated in an autofocus camera, power consumption increases when autofocus is driven, and a battery is consumed too quickly. In contrast, if the optical element is made lightweight, power consumption during driving of the autofocus can be reduced, and the battery life can be extended.

However, it is considered that the optical elements made of the glasses described in patent documents 1 to 20 using the high-refractive-index low-dispersion glass having an Abbe's number ν d in the range of 39.5 to 41.5 and satisfying the relation nd ≧ 2.0927-0.0058 × ν d tend to be heavy. This is because the composition adjustment for high refractive index and low dispersion described in patent documents 1 to 20 tends to increase the specific gravity of the glass.

An object of one embodiment of the present invention is to provide glass having an Abbe's number ν d of 39.5 to 41.5, satisfying the relation nd ≥ 2.0927-0.0058 × ν d, and contributing to weight reduction of an optical element.

One embodiment of the present invention relates to a glass (hereinafter referred to as "glass C") which is an oxide glass and is expressed in terms of cation%,

B³⁺and Si⁴⁺The total content of (B) is 43 to 65%,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺The total content of (a) is 25 to 50%,

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺and W⁶⁺The total content of (a) is 3 to 12%,

Zr⁴⁺the content of (a) is 2-8%,

B³⁺and Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴ ⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.42,

B³⁺and Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴ ⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 5.80 to 7.70 in terms of the number of the branches,

W⁶⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value of the water content is less than 0.50,

Zn²⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) The value of the water content is less than 0.17,

One embodiment of the present invention relates to a glass (hereinafter referred to as "glass D") which is an oxide glass and is represented by cation%, B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺The total content of (A) is 90% or more,

the Abbe number vd is in the range of 39.5-41.5,

the refractive index nd relative to the Abbe number vd satisfies the following formula (1):

nd is not less than 2.0927-0.0058 x ν d … (1), and

for the cationic components shown in table 1 below, the total D of the values obtained by multiplying the content of each cationic component by the coefficients shown in table 1 satisfies the following expression (B) with respect to the refractive index nd:

D≤6.242×nd-6.8042…(B)。

the glass C is glass with Abbe number vd ranging from 39.5 to 41.5 and satisfying the relation that nd is not less than 2.0927-0.0058 x vd, and comprises Gd³⁺Each component (i.e., La) of³⁺、Y³⁺、Gd³⁺、Yb³⁺) And contains Ta⁵⁺Each component (i.e., Nb)⁵ ⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺) In the above range, Gd is contained in the denominator or numerator³⁺、Ta⁵⁺The above cation ratio. Therefore, the ratio of Gd and Ta in the glass composition decreases. The glass can achieve high thermal stability (property of being less susceptible to devitrification) and low specific gravity by adjusting the composition satisfying the above-described content, total content, and cation ratio in the composition satisfying the above-described total content and cation ratio. The optical element made of the glass can be reduced in weight by the glass having a reduced specific gravity.

Glass D in cation%,% B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺(hereinafter, these cationic components are referred to as "main cationic components") is 90% or more in total. The present inventors have made extensive studies to achieve the above object, and have noticed that the above main cationic components have different influences on the specific gravity of the glass. Further, as a result of conducting a considerable number of trial and error experiments, coefficients shown in table 1 were determined for each main cation component. By performing composition adjustment so that the total D calculated using these coefficients satisfies expression (B), it can be mentioned thatDisclosed is a glass which contributes to the weight reduction of a high-refractive-index low-dispersion glass, i.e., an optical element, wherein the Abbe's number ν d is in the range of 39.5-41.5 and nd is not less than 2.0927-0.0058 × ν d.

According to one embodiment of the present invention, it is possible to provide glass having optical characteristics useful in an optical system and contributing to weight reduction of an optical element. Further, according to an aspect of the present invention, a glass material for press molding, an optical element blank, and an optical element, each of which is formed of the above glass, can be provided.

Drawings

FIG. 1 is a photograph of a glass evaluated in comparative example 6.

FIG. 2 is a graph in which the horizontal axis represents the ratio of each glass of example 1 to each glass of comparative examples 1 to 4, and the vertical axis represents the total D of the values obtained by multiplying the contents of the respective cationic components by the coefficients shown in Table 1.

FIG. 3 is a graph in which Abbe number ν d is plotted on the horizontal axis and value A calculated by the following expression (A) is plotted on the vertical axis for each glass of example 1 and each glass of comparative examples 1 to 4.

Detailed Description

The glass composition of the present invention can be quantified by, for example, an ICP-AES (Inductively Coupled Plasma-atomic emission Spectrometry) method or the like. The analytical value obtained by ICP-AES may contain a measurement error of about. + -. 5% of the analytical value. In the present specification and the present invention, the content of a constituent of 0% is not included or not introduced, meaning that the constituent is not substantially included, and means that the content of the constituent is not more than the impurity level.

In the following, the numerical ranges may be shown by (more) preferable lower limits and (more) preferable upper limits in the table. In the table, the lower the numerical value, the more preferable the lowest numerical value. Unless otherwise specified, the lower limit of (more) preferably means not less than the specified value, and the upper limit of (more) preferably means not more than the specified value. The numerical range can be defined by arbitrarily combining the numerical values described in the column of the (more) preferred lower limit and the numerical values described in the column of the (more) preferred upper limit in the table.

[ glass A ]

The glass A according to one embodiment of the present invention is an oxide glass having the above glass composition, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above formula (1) with respect to the Abbe's number ν d. The details of the glass a will be described below.

In the present invention, the glass compositions of glass a, glass C and glass D are expressed in terms of cation% with respect to the cation component. Cation% is known as a percentage in which the total content of all the cation components contained in the glass is 100%.

Hereinafter, unless otherwise specified, the contents of the cationic components of the glass a, the glass C and the glass D and the total (total content) of the contents of the plurality of cationic components are expressed as cationic%. Further, in the expression of cation%, the ratio of the contents of the cation components (including the total content of the plurality of cation components) is referred to as a cation ratio.

< glass composition >

B³⁺、Si⁴⁺Is a network forming component of the glass. When B is present³⁺And Si⁴⁺Total content (B) of³⁺+Si⁴⁺) When the content is 43% or more, the thermal stability of the glass is improved, and crystallization of the glass during production can be suppressed. On the other hand, when B³⁺Content of (A) and Si⁴⁺When the total content of (b) is 65% or less, the decrease in refractive index nd can be suppressed, and therefore, glass having the above optical properties can be produced. Thus, B of the above glass³⁺And Si⁴⁺The total content of (C) is set to 43-65%. B is³⁺And Si⁴⁺The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 1]

La³⁺、Y³⁺、Gd³⁺And Yb³⁺To have a refractive index increased while suppressing a decrease in Abbe's number ν dThe ingredients used. In addition, these components also have the effect of improving the chemical durability, weather resistance and glass transition temperature of the glass.

When La³⁺、Y³⁺、Gd³⁺And Yb³⁺Total content of (La)³⁺+Y³⁺+Gd³⁺+Yb³⁺) When the refractive index nd is 25% or more, the decrease in refractive index nd can be suppressed, and therefore, glass having the above optical characteristics can be produced. Further, the deterioration of the chemical durability and weather resistance of the glass can be suppressed. In addition, when the glass transition temperature is lowered, the glass becomes easily broken (machinability is lowered) when the glass is machined (cut, ground, polished, etc.), and when La is used, the glass becomes easily broken (machinability is lowered)³⁺、Y³⁺、Gd³⁺And Yb³⁺When the total content of (b) is 25% or more, since a decrease in glass transition temperature can be suppressed, machinability can be improved. On the other hand, if La³⁺、Y³⁺、Gd³⁺And Yb³⁺When the total content of the respective components (a) is 50% or less, the thermal stability of the glass can be improved, and therefore, crystallization in producing the glass can be suppressed, and the melting residue of the raw material in melting the glass can be reduced. Further, the increase in specific gravity can be suppressed. Therefore, in the above glass, La³⁺、Y³⁺、Gd³⁺And Yb³⁺The total content of (C) is 25 to 50%. La³ ⁺、Y³⁺、Gd³⁺And Yb³⁺The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 2]

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺The glass composition can also have an effect of improving the thermal stability of the glass by containing an appropriate amount of a component having an effect of increasing the refractive index. If Ti is present⁴⁺、Nb⁵⁺、Ta⁵⁺And W⁶⁺Total content of (Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Is composed of3% or more, the above optical properties can be realized while maintaining thermal stability. On the other hand, when Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺When the total content of (3) is 12% or less, the decrease in thermal stability and the decrease in Abbe number ν d can be suppressed. Further, the ultraviolet transmittance of the glass can be improved by suppressing an increase in the coloring degree λ 5 described later. Therefore, in the above glass, Nb⁵⁺、Ti⁴ ⁺、Ta⁵⁺And W⁶⁺The total content of (C) is set to 3-12%. Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 3]

Zr⁴⁺The glass composition can also have an effect of improving the thermal stability of the glass by containing an appropriate amount of a component having an effect of increasing the refractive index. In addition, Zr⁴⁺Further, the glass transition temperature is increased, so that the glass is not easily broken during machining. In order to obtain these effects well, Zr is added to the above glass⁴⁺The content of (B) is set to 2% or more. On the other hand, if Zr⁴⁺When the content of (b) is 8% or less, the thermal stability of the glass can be improved, and therefore, crystallization during glass production and the occurrence of a melt residue during glass melting can be suppressed. Thus, Zr of the above glass⁴⁺The content of (C) is set to 2 to 8%. Zr⁴⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 4]

In order to improve the thermal stability of the glassThe glass can realize the optical characteristics that Abbe number vd is 39.5-41.5 and the refractive index nd and the Abbe number vd satisfy the relation of the formula (1), and B in the glass³⁺And Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.75. If the cation ratio ((B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 or more), the thermal stability of the glass can be improved, and therefore devitrification of the glass can be suppressed. Further, an increase in the specific gravity of the glass can be suppressed. When the specific gravity of glass increases, an optical element made using the glass becomes heavy. As a result, the optical system incorporating the optical element becomes heavy. For example, when a heavy optical element is incorporated in an autofocus camera, power consumption increases when autofocus is driven, and a battery is consumed too quickly. From the viewpoint of reducing the weight of an optical element produced using the glass and an optical system incorporating the optical element, it is preferable to suppress an increase in the specific gravity of the glass. On the other hand, if the cation ratio { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) When the value is 1.75 or less, the above optical characteristics can be realized. Cation ratio { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 5]

In order to improve the thermal stability of the glass and to suppress the decrease in refractive index nd and to realize the above optical characteristics, B is added to the above glass³⁺And Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value is set to 9.00 or less.

In order to improve the thermal stability of the glass while suppressing the decrease in Abbe's number ν d, it is preferable to set the cation ratio { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 5.00 or more. Furthermore, in order to further suppress the wavelength of the short-wavelength side light absorption edge of the glass from increasing, it is preferable to set the cation ratio { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 5.00 or more. As a result, when a glass lens is cemented with an ultraviolet-curable adhesive, ultraviolet rays are easily transmitted to the coating layer of the adhesive through the lens. This makes it easier to cure the adhesive by ultraviolet irradiation.

Cation ratio { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The more preferred lower limits and the preferred upper limits of } are shown in the following table.

[ Table 6]

In order to improve the thermal stability of the glass, to suppress crystallization of the glass, and to realize the above optical characteristics, Zn is added to the glass²⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) It is set to less than 0.2. Cation ratio { Zn²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 7]

Among rare earth elements La, Y, Gd and Yb, Gd is a heavy rare earth element and is a component required to reduce the content in glass from the viewpoint of stable supply of glass. Gd is also a component that increases the specific gravity of the glass due to its large atomic weight.

Yb also belongs to a heavy rare earth element and has a large atomic weight. In addition, Yb has absorption in the near infrared region. On the other hand, the lens of the exchange lens or the monitoring camera for the single inverter is desired to have high light transmittance in the near infrared region. Therefore, in order to produce glasses useful for the production of these lenses, it is desirable to reduce the Yb content.

On the other hand, La and Y are useful components for providing a high-refractive-index, low-dispersion glass which does not adversely affect the optical transmittance in the near infrared region, has improved thermal stability and is suppressed in increase of specific gravity by appropriately distributing the total content of rare earth elements.

Therefore, in the above glass, La is preferable³⁺Adding La³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { La³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) The range of the speed is set to be 0.50-0.95. Cation ratio { La³⁺/(La³⁺+Y³ ⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 8]

In addition, for Y³⁺Is a reaction of Y³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Y }³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) The range of the unit is set to 0.10 to 0.50. Cation ratio { Y³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 9]

For Gd³⁺As described above, the content of the component in the glass is to be reduced from the viewpoint of stable supply of the glass. In the above glass, Gd³⁺In an amount of L a³⁺、Y³⁺、Gd³⁺And Yb³⁺And Gd is contained in the total amount of³⁺Is determined. Among the above glasses, Gd is added to stably supply a high-refractivity low-dispersion glass having the above optical characteristics³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Y b³⁺Cation ratio of the total content of (1) { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) It is set to 0.10 or less. Further, satisfying the cation ratio can contribute to a low specific gravity of the glass. Cation ratio { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 10]

For La³⁺、Y³⁺、Gd³⁺And Yb³⁺And La³⁺Content of (A), Y³⁺Content of (b), Gd³⁺The cation ratio of the content (b) to the total content is as described above. La³⁺、Y³⁺、Gd³⁺、Yb³⁺The preferable lower limit and the preferable upper limit of the content of each component (a) are shown in the following table. In addition, for Y³⁺The content of (b) is preferably lower limit as shown in the following table from the viewpoint of improving thermal stability and meltability of the glass.

[ Table 11]

[ Table 12]

[ Table 13]

[ Table 14]

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺When the glass composition is contained in an appropriate amount, the refractive index is increased and the thermal stability of the glass is improved. However, when Ti is increased⁴⁺、W⁶⁺In the case of (3), the absorption edge on the short wavelength side of the visible light region is shifted to the long wavelength side. As a result, the short-wavelength side light absorption edge of the glass is increased in wavelength. Therefore, in the above optical glass, Nb is considered for the purpose of improving the thermal stability of the glass and suppressing the wavelength increase of the short wavelength side light absorption edge of the glass⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺On the basis of the properties of (a), the ratio of the contents of these is determined. The details are as follows.

Nb⁵⁺The glass composition has the effects of increasing the refractive index nd and improving the thermal stability of the glass without increasing the specific gravity, coloring and manufacturing cost of the glass. Further, Nb⁵⁺With Ti⁴⁺、W⁶⁺In contrast, the absorption edge on the short wavelength side of the glass is not easily made longer. It is known that the absorption edge on the short wavelength side of glass can be expressed by an index called λ 5. That is, Nb⁵⁺With Ti⁴⁺、W⁶⁺In contrast, the component is not likely to increase λ 5. Details will be described later for λ 5.

On the other hand, when Ti⁴⁺When the content of (b) is increased, λ 5 is increased. In addition, the transmittance in the visible light region of the glass tends to decrease, and the coloring of the glass tends to increase.

Ta⁵⁺Has an effect of increasing the refractive index, and is reacted with Nb⁵⁺、Ti⁴⁺、W⁶⁺The absorption edge on the shorter wavelength side of the glass is not easily made longer than the wavelength of the glass, but is an extremely expensive component. Therefore, it is not preferable to actively use Ta from the viewpoint of stable supply of glass⁵⁺. In addition, when Ta⁵⁺When the content of (b) is large, the raw materials tend to be melted and remain when the glass is melted. In addition, the specific gravity of the glass increases.

For W⁶⁺When the content thereof becomes larger, λ 5 increases. Further, the transmittance in the visible light region decreases, and the specific gravity increases.

As mentioned above, Ta⁵⁺Is an ingredient whose content should be reduced. Therefore, it is not preferable to actively use Ta⁵⁺. In order to improve thermal stability and suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, reducing λ 5), Nb is added to the above glass⁵⁺Relative to the content in Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺In addition to Ta⁵⁺Nb other than Nb⁵⁺、Ti⁴⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) It is set to 0.80 or more. Cation ratio { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 15]

For Ta⁵⁺In order to improve the thermal stability of glass and to reduce the high refractive index and dispersion and the amount of Ta used, Ta is used⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or less. Cation ratio { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 16]

In addition, for Nb⁵⁺In order to stably supply glass, Gd is reduced³⁺、Ta⁵⁺In addition to the amount of (A), is desirably in combination with Gd³⁺、Ta⁵⁺Decrease Yb together³⁺In addition to the content of (b), it is preferable to consider Nb in consideration of a high-refractive-index low-dispersion glass which is excellent in thermal stability by suppressing the wavelength of the short-wavelength side light absorption edge from increasing (preferably, by making λ 5 small)⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺Based on the above-mentioned effects, Nb⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.4 or more. In addition, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing, it is preferable to set the cation ratio { Nb }⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Large. Cation ratio { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The more preferred lower limits and the preferred upper limits of } are shown in the following table.

[ Table 17]

Further, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, further suppress the increase of λ 5) and to accelerate the curing of the ultraviolet-curable adhesive by ultraviolet irradiation, Ti is preferably used⁴⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ti }⁴⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.6 or less. Cation ratio { Ti⁴ ⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 18]

Similarly, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, further suppress the increase of λ 5), W is preferably set to be W⁶⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or less. Cation ratio { W⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 19]

At Nb⁵⁺、Ti⁴⁺、W⁶⁺In (Ti)⁴⁺The glass tends to be colored more strongly, and the effect of increasing λ 5 is also relatively strong. In order to suppress the increase of λ 5, it is preferable to use Ti⁴⁺Relative to the content of Nb⁵⁺、Ti⁴⁺And W⁶⁺Total content of (Nb)⁵⁺+Ti⁴⁺+W⁶⁺) Cation ratio of { Ti⁴⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) The upper limit of } is the value of the preferred upper limit shown in the following table. In addition, cations can also be madeRatio { Ti⁴⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) Is 0.

[ Table 20]

In order to suppress the lowering of Abbe's number vd while maintaining the thermal stability of the glass, La is preferably used³⁺、Y³⁺、Gd³⁺And Yb³⁺Total content of (La)³⁺+Y³⁺+Gd³⁺+Yb³⁺) Relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Total content of (Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Cation ratio of (A) { (La)³⁺+Y³⁺+Gd³⁺+Yb³⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The lower limit of } is the value of the preferred lower limit shown in the following table.

On the other hand, in order to maintain the thermal stability of the glass while suppressing the decrease in refractive index, it is preferable to set the cation ratio { (La)³⁺+Y³⁺+Gd³⁺+Yb³⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The upper limit of } is the value of the preferred upper limit shown in the following table.

[ Table 21]

The glass composition of the glass a will be further described below.

Network Forming component B for glass³⁺And Si⁴⁺The total content of (A) and (B) are as described above. For B³⁺And Si⁴⁺Albeit B³⁺Bisi⁴⁺The effect of improving the meltability is excellent, but the volatility is high during melting. On the other hand, Si⁴⁺Has the effects of improving the chemical durability, weather resistance and machinability of the glass and improving the viscosity of the glass during melting.

In general, in the presence of B³⁺And La³⁺Such rare earth elements have a low dispersion and a high refractive index, and the viscosity of the glass at the time of melting is low. However, when the viscosity of the glass at the time of melting is low, crystallization becomes easy. Crystallization in glass production is caused by the fact that the state of crystallization is more stable than that of an amorphous state (amorphous), and ions constituting the glass move in the glass and are arranged in such a manner as to have a crystal structure. Therefore, B is adjusted so that the viscosity at the time of melting becomes high³⁺And Si⁴⁺The content ratio of each component (a) makes it difficult for the ions to align with a crystal structure, and crystallization of the glass can be further suppressed to further improve devitrification resistance of the glass.

From the above viewpoints, B³⁺Relative to B³⁺And Si⁴⁺Cation ratio of the total content of (1) { B³⁺/(B³⁺+Si⁴⁺) Preferred lower limits and preferred upper limits of } are shown in the following table. It is also preferable to set the lower limit or more shown in the following table from the viewpoint of improving the meltability of the glass. It is preferable to set the viscosity of the glass at the time of melting to be not more than the upper limit shown in the following table. Further, it is preferable to set the upper limit or less shown in the following table from the viewpoint of reducing the variation in glass composition due to volatilization at the time of melting and the variation in optical characteristics due to the variation, and further, from the viewpoint of improving 1 or more of chemical durability, weather resistance and machinability of the glass.

[ Table 22]

For B³⁺Content of (A), Si⁴⁺The contents of (b) are shown in the following table from the viewpoint of improving the devitrification resistance, melting property, moldability, chemical durability, weather resistance, machinability, etc. of the glass, and preferred lower limits and preferred upper limits thereof are shown in the following table, respectively.

[ Table 23]

[ Table 24]

Zn²⁺Has an action of promoting melting of glass raw materials at the time of melting glass, that is, an action of improving meltability. In addition, the glass transition temperature is lowered by adjusting the refractive index nd or Abbe number ν d. From the viewpoints of suppressing a decrease in abbe number ν d, improving thermal stability of glass, and suppressing a decrease in glass transition temperature (thereby improving machinability), it is preferable to use Zn²⁺Is divided by B³⁺And Si⁴⁺The value of the total content of (1) { Zn } is the cation ratio²⁺/(B³⁺+Si⁴⁺) It is set to 0.15 or less. In the above glass, Zn is an optional component which may or may not be contained, and therefore the cation ratio { Zn²⁺/(B³⁺+Si⁴⁺) The value is 0 or more, but it is more preferable to contain Zn so that the cation ratio { Zn } is set to be higher than that of the glass for improving the meltability and easily producing a homogeneous glass²⁺/(B³⁺+Si⁴⁺) Is set to exceed 0. Cation ratio { Zn²⁺/(B³⁺+Si⁴⁺) The more preferred lower limits and the more preferred upper limits of } are shown in the following tables.

[ Table 25]

Zn is added to improve the melting property, thermal stability, moldability, machinability and the like of the glass to realize the above optical properties²⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 26]

To further improve the glassFrom the viewpoints of thermal stability of glass, suppression of lowering of glass transition temperature (thereby improving machinability), and improvement of chemical durability, Zn is preferable²⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of { Zn }²⁺/(Ti⁴⁺+Nb⁵⁺+Ta⁵⁺+W⁶⁺) The value is 1.0 or less. On the other hand, Zn is an optional component, and therefore the cation ratio { Zn²⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The lower limit of 0 is more preferably 0 or more from the viewpoint of improving the meltability and further suppressing the wavelength increase of the light absorption edge on the shorter wavelength side (preferably, further suppressing the increase of λ 5). When the above aspect is considered, cation ratio { Zn²⁺/(Ti⁴⁺+Nb⁵⁺+Ta⁵⁺+W⁶⁺) The more preferred lower limits and the more preferred upper limits of } are shown in the following tables.

[ Table 27]

For Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺In consideration of the above-mentioned action/effect, Nb is added⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺Preferred ranges of the contents of the respective components are shown in the following table.

[ Table 28]

[ Table 29]

[ Table 30]

[ Table 31]

Next, optional components other than the above-described components will be described.

Li⁺Since the effect of lowering the glass transition temperature is strong, when the content thereof is increased, the machinability tends to be lowered. Further, the chemical durability and weather resistance tend to be lowered. Therefore, Li is preferably used⁺The content of (B) is 5% or less. Li⁺The preferable lower limit and more preferable upper limit of the content of (b) are shown in the following table. Li⁺The content of (B) may be 0%.

[ Table 32]

Na⁺、K⁺、Rb⁺、Cs⁺All of them have an effect of improving the meltability of the glass, but when their content is increased, the thermal stability, chemical durability, weather resistance and machinability of the glass tend to be lowered. Thus, Na⁺、K⁺、Rb⁺、Cs⁺The lower limit and the upper limit of each content of (a) are preferably as shown in the following table, respectively.

[ Table 33]

[ Table 34]

[ Table 35]

[ Table 36]

In order to improve the melting property of glass while maintaining the thermal stability, chemical durability, weather resistance and machinability of glass, Li⁺、Na⁺And K⁺Total content of (Li)⁺+Na⁺+K⁺) The preferred lower limits and preferred upper limits of (b) are shown in the following table.

[ Table 37]

Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺All of them are components having an effect of improving the meltability of the glass. However, when the content of these components is increased, the thermal stability of the glass is lowered and devitrification tends to occur. Therefore, the content of each of these components is preferably not less than the lower limit described below, and preferably not more than the upper limit described below.

[ Table 38]

[ Table 39]

[ Table 40]

[ Table 41]

Furthermore, to maintain the thermal stability of the glass, Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺Total content (Mg) of²⁺+Ca²⁺+Sr²⁺+Ba²⁺) The lower limit shown in the following table is preferably set to be not less than the lower limit, and the upper limit shown in the following table is preferably set to be not more than the upper limit.

[ Table 42]

Al³⁺Is a component having an effect of improving the chemical durability and weather resistance of the glass. However, when Al is used³⁺When the content (d) is increased, the refractive index nd tends to be lowered, the thermal stability of the glass tends to be lowered, and the meltability tends to be lowered. In view of the above, Al³⁺The content of (b) is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 43]

Ga³⁺、In³⁺、Sc³⁺、Hf⁴⁺Both have the effect of increasing the refractive index nd. However, these components are expensive and are not essential for obtaining the above optical glass. Thus, Ga³⁺、In³⁺、Sc³⁺、Hf⁴⁺The content of (b) is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 44]

[ Table 45]

[ Table 46]

[ Table 47]

Lu³⁺Has the effect of increasing the refractive index nd, but is also a component that increases the specific gravity of the glass. In addition, Lu is a heavy rare earth element as in Gd and Yb, and therefore it is preferable to reduce the content of Lu. From the above points of view, Lu³⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 48]

Ge⁴⁺The glass composition has a function of increasing the refractive index nd, but is a remarkably expensive component among glass compositions generally used. To reduce the manufacturing cost of the glass, Ge⁴⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 49]

Bi³⁺Is a component that lowers the Abbe's number ν d while increasing the refractive index nd. Further, it is also a component which tends to increase the coloring of the glass. In order to produce a glass having the above optical properties and less coloration, Bi³⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 50]

In order to obtain the various actions and effects described above well, the total content (total content) of the respective contents of the cationic components described above is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

In the cation component other than the cation component described above, P is⁵⁺The component that lowers the refractive index nd is also a component that lowers the thermal stability of the glass, but if the amount is very small, the thermal stability of the glass may be improved. P for producing a glass having the above-mentioned optical characteristics and excellent thermal stability⁵⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 51]

Te⁴⁺Is a component for increasing the refractive index nd, but is a component having toxicity, so it is preferable to reduce Te⁴⁺The content of (a). Te (Te)⁴⁺The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 52]

In the above tables, it is described that the content of the component having the (more) preferable lower limit or 0% is also preferably 0%. The same applies to the total content of the plurality of components.

Pb, As, Cd, Tl, Be, Se are toxic respectively. Therefore, it is preferable that these elements are not contained, that is, these elements are not introduced into the glass as a glass component.

U, Th and Ra are radioactive elements. Therefore, it is preferable that these elements are not contained, that is, these elements are not introduced into the glass as a glass component.

V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Ce increase the coloration of the glass or become a source of fluorescence, and are not preferred as elements contained in the glass for optical elements. Therefore, it is preferable that these elements are not contained, that is, these elements are not introduced into the glass as a glass component.

Sb and Sn are elements that can be optionally added and function as clarifiers.

The amount of Sb added is converted into Sb₂O₃And Sb₂O₃The amount of Sb added is preferably in the range of 0 to 0.11% by mass, more preferably in the range of 0.01 to 0.08% by mass, and still more preferably in the range of 0.02 to 0.05% by mass, when the total content of the other glass components is 100% by mass.

The amount of Sn added is converted into SnO₂And SnO₂The amount of Sn added is preferably in the range of 0 to 0.5 mass%, more preferably in the range of 0 to 0.2 mass%, and even more preferably 0 mass%, when the total content of the other glass components is 100 mass%.

The cationic component is explained above. Next, the anion component will be described.

Since the above glass is an oxide glass, O is contained as an anion component^2-。O^2-The content of (b) is preferably 98 to 100 anionic%, more preferably 99 to 100 anionic%, and further preferably 100 anionic%.

As O^2-Other thanAn anionic component, which can be exemplified by F^-、Cl^-、Br^-、I^-. However, F^-、Cl^-、Br^-、I^-Are volatile in the melting of the glass. These components volatilize, and the characteristics of the glass fluctuate, so that the homogeneity of the glass tends to be lowered, and the consumption of melting equipment tends to be remarkable. Therefore, F is preferably added^-、Cl^-、Br^-And I^-Is suppressed to a total content of O subtracted from 100 anion%^2-Amount of (b).

Further, it is known that the anion% is a percentage in which the total content of all anion components contained in the glass is 100%.

[ glass B ]

Next, the glass B will be described.

The glass B of one embodiment of the present invention is an oxide glass having the above glass composition, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above formula (1) with respect to the Abbe's number ν d. The details of the glass B will be described below.

In the present invention, the glass composition of glass B is expressed on an oxide basis. Here, the "oxide-based glass composition" means a glass composition obtained by decomposing all glass raw materials at the time of melting and converting the glass raw materials into substances existing as oxides in the glass. Unless otherwise specified, the glass composition of the glass B is represented by mass (mass%, mass ratio).

< glass composition >

B₂O₃、SiO₂Is a network forming component of the glass. When B is present₂O₃And SiO₂Total content (B) of₂O₃+SiO₂) When the content is 17.5% or more, the thermal stability of the glass is improved, and crystallization of the glass during production can be suppressed. On the other hand, when B₂O₃And SiO₂When the total content of (b) is 35% or less, the decrease in refractive index nd can be suppressed, and therefore, glass having the above optical properties can be produced. Thus, B of glass B₂O₃And SiO₂The total content of (a) is set to 17.5 to 35%. B is₂O₃And SiO₂The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 53]

La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The composition has an effect of increasing the refractive index while suppressing a decrease in Abbe's number ν d. In addition, these components also have the effect of improving the chemical durability, weather resistance and glass transition temperature of the glass.

When La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Total content of (La)₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) When the refractive index nd is 45% or more, the decrease in refractive index nd can be suppressed, and therefore, glass having the above optical characteristics can be produced. Further, the deterioration of the chemical durability and weather resistance of the glass can be suppressed. In addition, when the glass transition temperature is lowered, the glass becomes easily broken (machinability is lowered) when the glass is machined (cut, ground, polished, etc.), and when La is used, the glass becomes easily broken (machinability is lowered)₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃When the total content of (b) is 45% or more, the decrease in glass transition temperature can be suppressed, and therefore, the machinability can be improved. On the other hand, if La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The total content of the components (a) is 70% or less, since the thermal stability of the glass can be improved, crystallization in the production of the glass can be suppressed, and the melting residue of the raw material in melting the glass can be reduced. Further, the increase in specific gravity can be suppressed. Therefore, in the above glass, La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The total content of (C) is set to 45-70%. La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 54]

Nb₂O₅、TiO₂、Ta₂O₅And WO₃The glass composition can also have an effect of improving the thermal stability of the glass by containing an appropriate amount of a component having an effect of increasing the refractive index. If Nb₂O₅、TiO₂、Ta₂O₅And WO₃Total content of (Nb)₂O₅+TiO₂+Ta₂O₅+WO₃) At 3% or more, the above optical properties can be achieved while maintaining thermal stability. On the other hand, when Nb₂O₅、TiO₂、Ta₂O₅And WO₃When the total content of (b) is 16% or less, the decrease in thermal stability and the decrease in Abbe number ν d can be suppressed. Further, the ultraviolet transmittance of the glass can be improved by suppressing an increase in the coloring degree λ 5 described later. Therefore, in the above glass, Nb₂O₅、TiO₂、Ta₂O₅And WO₃The total content of (C) is set to 3-16%. Nb₂O₅、TiO₂、Ta₂O₅And WO₃The preferable lower limit and the preferable upper limit of the total content of (a) are shown in the following table.

[ Table 55]

ZrO₂The component having the effect of increasing the refractive index is contained in an appropriate amount to improve the thermal stability of the glass. Furthermore, ZrO₂Further, the glass transition temperature is increased to make the glass less likely to break during machining. In order to obtain these effects well, ZrO is added to the above glass₂The content of (B) is set to 2% or more. On the other hand, if ZrO₂When the content of (b) is 10% or less, the thermal stability of the glass can be improved, and therefore, crystallization during glass production and the occurrence of a melt residue during glass melting can be suppressed. Thus, ZrO of the above glass₂The content of (C) is set to 2-10%. ZrO (ZrO)₂The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 56]

In order to improve the thermal stability of the glass and realize the optical characteristics that the Abbe number vd is 39.5-41.5 and the refractive index nd and the Abbe number vd satisfy the relation of the formula (1), in the glass, B₂O₃And SiO₂The total content of (A) to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.2 to 0.5. If the mass ratio is { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) When the value is 0.2 or more, the thermal stability of the glass can be improved, and therefore devitrification of the glass can be suppressed. Further, an increase in the specific gravity of the glass can be suppressed. When the specific gravity of glass increases, an optical element made using the glass becomes heavy. As a result, the optical system incorporating the optical element becomes heavy. For example, when grouping in an autofocus cameraWhen a heavy optical element is mounted, power consumption for driving autofocus increases, and a battery is consumed too quickly. From the viewpoint of reducing the weight of an optical element produced using the glass and an optical system incorporating the optical element, it is preferable to suppress an increase in the specific gravity of the glass. On the other hand, if the mass ratio { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) When the value is 0.5 or less, the above optical characteristics can be realized. Mass ratio { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 57]

In order to improve the thermal stability of the glass and to suppress the decrease in refractive index nd and to realize the above optical characteristics, B is added to the above glass₂O₃And SiO₂The total content of (B) relative to Nb₂O₅、TiO₂、Ta₂O₅And WO₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The value is set to 2.8 or less.

In order to improve the thermal stability of the glass while suppressing the decrease in Abbe's number ν d, it is preferable to set the mass ratio { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The value is 1.2 or more. Further, in order to further suppress the wavelength of the short wavelength side light absorption edge of the glass from increasing, it is preferable to set the mass ratio { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The value is 1.2 or more. As a result, when a glass lens is cemented with an ultraviolet-curable adhesive, ultraviolet rays are easily transmitted to the coating layer of the adhesive through the lens. This makes it easier to cure the adhesive by ultraviolet irradiation.

Mass ratio { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The more preferred lower limits and the preferred upper limits of } are shown in the following table.

[ Table 58]

In order to improve the thermal stability of the glass and to realize the above optical properties, the content of ZnO in the above glass is adjusted to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (1), (ZnO/(La))₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) It is set to less than 0.10. Mass ratio { ZnO/(La) }₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 59]

Among rare earth elements La, Y, Gd and Yb, Gd is a heavy rare earth element, and is a component required to reduce the content in glass from the viewpoint of stable supply of glass. Gd is also a component that increases the specific gravity of the glass due to its large atomic weight.

Yb also belongs to a heavy rare earth element and has a large atomic weight. In addition, Yb has absorption in the near infrared region. On the other hand, the lens of the exchange lens or the monitoring camera for the single inverter is desired to have high light transmittance in the near infrared region. Therefore, in order to be useful glass for producing these lenses, it is desirable to reduce the Yb content.

On the other hand, La and Y are components useful for providing a high-refractive-index low-dispersion glass that does not adversely affect the optical transmittance in the near infrared region, and that improves thermal stability and suppresses an increase in specific gravity by appropriately distributing the total content of rare earth elements.

Therefore, in the above glass, La is used as La₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { La }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) The range of the mass ratio is set to 0.55-0.98, and the mass ratio is { La }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 60]

Thus, for Y, Yb₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { Y }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) The range of 0.02 to 0.45, mass ratio { Y }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 61]

As described above, Gd is a component to be reduced in content in glass from the viewpoint of stable supply of glass. In the above glass, Gd content is represented by La₂O₃、Y₂O₃、Gd₂O₃、Yb₂O₃And Gd is contained in the total amount of₂O₃Is determined. Among the above glasses, Gd is added to stably supply a high-refractivity low-dispersion glass having the above optical characteristics₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃(iii) the total content of (a) to (b) { Gd }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) It is set to 0.10 or less. Further, satisfying the above mass ratio also contributes to a low specific gravity of the glass. Mass ratio { Gd₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 62]

For La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Of (2)Measured content, and La₂O₃Content of (A), Y₂O₃Content of (b), Gd₂O₃The mass ratio of the content (b) to the total content is as described above. La₂O₃、Y₂O₃、Gd₂O₃、Yb₂O₃The preferable lower limit and the preferable upper limit of the content of each component (a) are shown in the following table. In addition, for Y₂O₃The content of (b) is preferably lower limit as shown in the following table from the viewpoint of improving thermal stability and meltability of the glass.

[ Table 63]

[ Table 64]

[ Table 65]

[ Table 66]

Nb, Ti, Ta and W are contained in an appropriate amount to exhibit the effects of increasing the refractive index and improving the thermal stability of the glass. However, when the contents of Ti and W are increased, the absorption edge on the short wavelength side of the visible light region shifts to the long wavelength side. As a result, the short-wavelength side light absorption edge of the glass is increased in wavelength. Therefore, in the above optical glass, in order to improve the thermal stability of the glass and to suppress the wavelength increase of the short-wavelength side light absorption edge of the glass, the ratio of the content of Nb, Ti, Ta, and W is determined in consideration of the properties thereof. The details are as follows.

Nb has the effect of increasing the refractive index nd and improving the thermal stability of the glass without increasing the specific gravity, coloring, and production cost of the glass. Further, Nb is also a component which is less likely to make the absorption edge on the shorter wavelength side of the glass longer than Ti and W. It is known that the absorption edge on the short wavelength side of glass can be expressed by an index called λ 5. That is, Nb is a component which is less likely to increase λ 5 than Ti or W. Details will be described later for λ 5.

On the other hand, when the content of Ti becomes larger, λ 5 increases. In addition, the transmittance in the visible light region of the glass tends to decrease, and the coloring of the glass tends to increase.

Ta has an action of increasing the refractive index, and is a component which is less likely to make the absorption edge on the shorter wavelength side of the glass longer than Nb, Ti, and W, but is an extremely expensive component. Therefore, it is not preferable to actively use Ta from the viewpoint of stable supply of glass⁵⁺. Further, when the content of Ta is large, the raw material tends to melt and remain when the glass is melted. In addition, the specific gravity of the glass increases.

For W, λ 5 increases as its content becomes higher. Further, the transmittance in the visible light region decreases, and the specific gravity increases.

As described above, Ta is a component whose content should be reduced. Therefore, it is not preferable to actively use Ta. In order to improve thermal stability and suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, reducing λ 5), Nb is added to the above glass₂O₅Relative to the content in Nb₂O₅、TiO₂、Ta₂O₅、WO₃In addition to Ta₂O₅Nb other than Nb₂O₅、TiO₂And WO₃Mass ratio of the total content of (1) { Nb }₂O₅/(Nb₂O₅+TiO₂+WO₃) 0.81 or more. Mass ratio { Nb₂O₅/(Nb₂O₅+TiO₂+WO₃) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 67]

In order to improve the thermal stability of glass and to reduce the high refractive index and dispersion and the amount of Ta used, Ta is used₂O₅Relative to the content of Nb₂O₅、T iO₂、Ta₂O₅And WO₃Mass ratio of the total content of (1) { Ta }₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 0.3 or less. Mass ratio { Ta₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 68]

In addition, in Nb, in order to reduce the content of Gd and Ta for stable supply of glass, and in addition to reducing the content of Yb together with Gd and Ta, it is desirable to suppress the increase in wavelength of the short-wavelength light absorption edge (preferably, λ 5 is small) and provide high-refractive-index low-dispersion glass having excellent thermal stability, it is preferable to use Nb in consideration of the above-described actions of Nb, Ti, Ta, and W₂O₅Relative to the content of Nb₂O₅、TiO₂、Ta₂O₅And WO₃Mass ratio of the total content of (1) { Nb }₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 0.5 or more. In addition, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing, the mass ratio { Nb is preferably set to₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) Large. Mass ratio { Nb₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The more preferred lower limits and the preferred upper limits of } are shown in the following table.

[ Table 69]

Further, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, further suppress the increase of λ 5) and to accelerate the curing of the ultraviolet-curable adhesive by ultraviolet irradiation, it is preferable to use TiO₂Relative to the content of Nb₂O₅、TiO₂、Ta₂O₅And WO₃Mass ratio of the total content of (3) { TiO } {₂/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 0.40 or less. Mass ratio { TiO }₂/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 70]

Similarly, in order to further suppress the wavelength of the short-wavelength side light absorption edge from increasing (preferably, further suppress the increase of λ 5), WO is preferably used₃Relative to the content of Nb₂O₅、TiO₂、Ta₂O₅And WO₃(iii) mass ratio of the total content of (1) { WO }₃/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 0.3 or less. Mass ratio { WO₃/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 71]

Among Nb, Ti and W, Ti is highly likely to increase the coloring of the glass, and the action of increasing λ 5 is also relatively strong. To suppress the increase of λ 5, TiO is preferably used₂Relative to the content of Nb₂O₅、TiO₂And WO₃Total content of (Nb)₂O₅+TiO₂+WO₃) Mass ratio of (3) { TiO₂/(Nb₂O₅+TiO₂+WO₃) The upper limit of } is the value of the preferred upper limit shown in the following table. In addition, the mass ratio { TiO } can also be made₂/(Nb₂O₅+TiO₂+WO₃) Is 0.

[ Table 72]

In order to suppress the lowering of Abbe's number vd while maintaining the thermal stability of the glass, La is preferably used₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Total content of (La)₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Relative to Nb₂O₅、TiO₂、Ta₂O₅And WO₃Total content of (Nb)₂O₅+TiO₂+Ta₂O₅+WO₃) Mass ratio of (A) { (La)₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The lower limit of } is the value of the preferred lower limit shown in the following table.

On the other hand, it is preferable to maintain the thermal stability of the glass while suppressing the decrease in refractive indexChoosing the mass ratio { (La)₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) The upper limit of } is the value of the preferred upper limit shown in the following table.

[ Table 73]

The glass composition of the above glass will be further described below.

Network Forming component B for glass₂O₃And SiO₂The total content of (A) and (B) are as described above. For B₂O₃And SiO₂Albeit B₂O₃SiO 2₂The effect of improving the meltability is excellent, but the volatility is high during melting. On the other hand, SiO₂Has the effects of improving the chemical durability, weather resistance and machinability of the glass and improving the viscosity of the glass during melting.

Generally, in a high-refractive-index low-dispersion glass containing rare earth elements such as B and La, the viscosity of the glass at the time of melting is low. However, when the viscosity of the glass at the time of melting is low, crystallization becomes easy. For crystallization in glass production, the crystallized state is more stable than the amorphous state (amorphous), and is generated by arranging ions constituting the glass in such a manner as to have a crystal structure by moving in the glass. Therefore, B is adjusted so that the viscosity at the time of melting becomes high₂O₃And SiO₂The content ratio of each component (a) makes it difficult for the ions to align with a crystal structure, and crystallization of the glass can be further suppressed to further improve devitrification resistance of the glass.

From the above viewpoints, B₂O₃Relative to B₂O₃And SiO₂Mass ratio of the total content of (1) { B }₂O₃/(B₂O₃+SiO₂) Preferred lower limits and preferred upper limits of } are shown in the following table. From the viewpoint of improving the meltability of glassFrom the viewpoint of the above, it is also preferable to set the lower limit shown in the following table to be not less than the lower limit. In addition, the viscosity of the glass at the time of melting is preferably not more than the upper limit shown in the following table. Further, it is preferable to set the upper limit or less shown in the following table from the viewpoint of reducing the variation in glass composition due to volatilization at the time of melting and the variation in optical characteristics due to the variation, and further, from the viewpoint of improving 1 or more of chemical durability, weather resistance and machinability of the glass.

[ Table 74]

For B₂O₃Content of (2), SiO₂The contents of (b) are shown in the following table from the viewpoint of improving the devitrification resistance, melting property, moldability, chemical durability, weather resistance, machinability, etc. of the glass, and preferred lower limits and preferred upper limits thereof are shown in the following table, respectively.

[ Table 75]

[ Table 76]

ZnO has an action of promoting melting of glass raw materials, that is, an action of improving meltability when melting glass. In addition, the glass transition temperature is lowered by adjusting the refractive index nd or Abbe number ν d. From the viewpoints of suppressing a decrease in abbe number ν d, improving thermal stability of glass, and suppressing a decrease in glass transition temperature (thereby improving machinability), it is preferable to divide the content of ZnO by B₂O₃And SiO₂The value of the total content of (1), (B) is the mass ratio { ZnO/(B) }₂O₃+SiO₂) It is set to 0.30 or less. In addition, the first and second substrates are,in the above glass, ZnO is an optional component which may or may not be contained, and therefore the mass ratio { ZnO/(B) } is preferable₂O₃+SiO₂) The ratio { ZnO/(B) } is 0 or more, but in order to improve meltability and to easily produce homogeneous glass, it is more preferable to contain Zn in such a manner that the mass ratio is { ZnO/(B) }₂O₃+SiO₂) Is set to exceed 0. Mass ratio { ZnO/(B)₂O₃+SiO₂) The more preferred lower limits and the more preferred upper limits of } are shown in the following tables.

[ Table 77]

From the viewpoint of improving the melting property, thermal stability, moldability, machinability, etc. of the glass to realize the above optical properties, the preferable lower limit and the preferable upper limit of the ZnO content are shown in the following table.

[ Table 78]

From the viewpoints of further improving the thermal stability of the glass, suppressing the lowering of the glass transition temperature (thereby improving the machinability), and improving the chemical durability, the content of ZnO is preferably set to Nb₂O₅、TiO₂、Ta₂O₅And WO₃The mass ratio of the total content of (1), (ZnO/(Nb))₂O₅+TiO₂+Ta₂O₅+WO₃) Less than 0.61. On the other hand, ZnO is an optional component, and therefore the mass ratio { ZnO/(Nb) is preferable₂O₅+TiO₂+Ta₂O₅+WO₃) The lower limit of 0 is more preferably more than 0 from the viewpoint of improving the meltability and further suppressing the wavelength increase of the light absorption edge on the shorter wavelength side (preferably, further suppressing the increase of λ 5). When the above aspects are considered, the mass ratio { ZnO/(Nb) }₂O₅+TiO₂+Ta₂O₅+WO₃) The more preferred lower limits and the more preferred upper limits of } are shown in the following tables.

[ Table 79]

For Nb₂O₅、TiO₂、Ta₂O₅、WO₃In consideration of the above-mentioned action/effect, Nb is added₂O₅、TiO₂、Ta₂O₅、WO₃Preferred ranges of the contents of the respective components are shown in the following table.

[ Table 80]

[ Table 81]

[ Table 82]

[ Table 83]

Li₂Since O has a strong effect of lowering the glass transition temperature, when the content thereof is increased, the machinability tends to be lowered. Further, the chemical durability and weather resistance tend to be lowered. Therefore, Li is preferably used₂The content of O is 5% or less. Li₂Preferred lower limits and more preferred upper limits of the content of O are shown in the following table. Li₂The content of O may also beThe content was 0%.

[ Table 84]

Na₂O、K₂O、Rb₂O、Cs₂All of O has an effect of improving the meltability of the glass, but when the content thereof is increased, the thermal stability, chemical durability, weather resistance and machinability of the glass tend to be lowered. Thus, Na₂O、K₂O、Rb₂O、Cs₂The lower limit and the upper limit of each content of O are preferably as shown in the following tables, respectively.

[ Table 85]

[ Table 86]

[ Table 87]

[ Table 88]

Li is intended to improve the meltability of glass while maintaining the thermal stability, chemical durability, weather resistance and machinability of glass₂O、Na₂O and K₂Total content of O (Li)₂O+Na₂O+K₂O) are shown in the following table.

[ Table 89]

MgO, CaO, SrO and BaO are all components having an effect of improving the meltability of the glass. However, when the content of these components is increased, the thermal stability of the glass is lowered and devitrification tends to occur. Therefore, the content of each of these components is preferably not less than the lower limit described below, and preferably not more than the upper limit described below.

[ Table 90]

[ Table 91]

[ Table 92]

[ Table 93]

In order to maintain the thermal stability of the glass, the total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 94]

Al₂O₃Is a component having an effect of improving the chemical durability and weather resistance of the glass. However, when Al is used₂O₃When the content (d) is increased, the refractive index nd tends to be lowered, the thermal stability of the glass tends to be lowered, and the meltability tends to be lowered. In view of the above, Al₂O₃The content of (b) is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 95]

Ga₂O₃、In₂O₃、Sc₂O₃、HfO₂Both have the effect of increasing the refractive index nd. However, these components are expensive and are not essential for obtaining the above optical glass. Thus, Ga₂O₃、In₂O₃、Sc₂O₃、HfO₂The content of (b) is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 96]

[ Table 97]

[ Table 98]

[ Table 99]

Lu₂O₃Has the effect of increasing the refractive index nd, but is also a component that increases the specific gravity of the glass. In addition, Lu is a heavy rare earth element as in Gd and Yb, and therefore it is preferable to reduce the content of Lu. From the above points of view, Lu₂O₃The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 100]

GeO₂The glass composition has a function of increasing the refractive index nd, but is a remarkably expensive component among glass compositions generally used. In order to reduce the manufacturing cost of glass, GeO₂The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ watch 101]

Bi₂O₃Is a component that lowers the Abbe's number ν d while increasing the refractive index nd. Further, it is also a component which tends to increase the coloring of the glass. In order to produce a glass having the above optical properties and less coloration, Bi₂O₃The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 102]

In order to obtain the various actions and effects described above well, the total content (total content) of the glass components described above is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, and still more preferably more than 99.5%.

In the aboveIn the glass components other than the glass components described, P₂O₅The component that lowers the refractive index nd is also a component that lowers the thermal stability of the glass, but if the amount is very small, the thermal stability of the glass may be improved. P for producing a glass having the above-mentioned optical characteristics and excellent thermal stability₂O₅The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 103]

TeO₂Is a component for increasing the refractive index nd, but is a component having toxicity, so it is preferable to reduce TeO₂The content of (a). TeO₂The preferred lower limit and the preferred upper limit of the content of (b) are shown in the following table.

[ Table 104]

In each of the tables, the content of the component whose lower limit or upper limit (more) indicates 0% is also preferably 0%. The same applies to the total content of the plurality of components.

V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Ce increase the coloration of the glass or become a source of fluorescence, and are not preferred as elements contained in the glass for optical elements. Therefore, it is preferable that these elements are not contained, that is, these elements are not introduced into the glass as a glass component.

Sb and Sn are elements that can be optionally added and function as clarifiers.

[ glass C ]

Next, the glass C will be explained.

The glass C according to one embodiment of the present invention is an oxide glass having the above glass composition, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above formula (1) with respect to the Abbe's number ν d. The details of the glass C will be described below.

< glass composition >

In order to realize optical characteristics in which Abbe's number ν d is 39.5 to 41.5 and refractive index nd and Abbe's number ν d satisfy the relationship of the above formula (1), in the above glass, Zr is added⁴⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Zr⁴⁺Content of (A)/(Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The range of the speed is set to be 0.48-2.20. From the viewpoint of suppressing a decrease in glass transition temperature (thereby improving machinability), it is also preferable that the cation ratio is in the range of 0.48 to 2.20. In addition, from the viewpoint of improving thermal stability and reducing the dispersion of the glass, it is also preferable that the cation ratio is 0.48 or more. On the other hand, from the viewpoint of improving the meltability and suppressing crystallization, it is also preferable that the cation ratio is 2.20 or less. Cation ratio { Zr⁴⁺Content of (A)/(Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The more preferred lower limits and the more preferred upper limits of } are shown in the following tables.

[ Table 105]

In order to improve the thermal stability of the glass and realize the optical characteristics that the Abbe number vd is 39.5-41.5 and the refractive index nd and the Abbe number vd satisfy the relation of the formula (1), in the glass, B³⁺And Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.42. If the cation ratio ((B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 or more), the thermal stability of the glass can be improved, and therefore devitrification of the glass can be suppressed. Further, an increase in the specific gravity of the glass can be suppressed. On the other hand, if the cation ratio { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) When the value is 1.42 or less, the above optical characteristics can be realized. Cation ratio { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 106]

In order to improve the thermal stability of the glass and to suppress the decrease in refractive index nd and to realize the above optical characteristics, B is added to the above glass³⁺And Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) It is set to 7.70 or less.

In order to improve the thermal stability of the glass while suppressing the decrease in Abbe's number ν d, the cation ratio is { (B)³⁺+Si⁴ ⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 5.80 or more. Further, from the viewpoint of reducing the specific gravity, the cation ratio { (B)³⁺+Si⁴ ⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) It is also preferable that the value is 5.80 or less.

Cation ratio { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 107]

W is added to improve the thermal stability of the glass to suppress crystallization of the glass and to reduce the specific gravity of the glass⁶⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.50 or less. Further, from the viewpoint of increasing the refractive index of the glass and reducing the coloring, the cation ratio { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) It is also preferable that the value is 0.50 or less. Cation ratio { W⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 108]

In order to improve the thermal stability of the glass, to suppress crystallization of the glass, and to realize the above optical characteristics, Zn is added to the glass²⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) It is set to 0.17 or less. Further, from the viewpoint of suppressing a decrease in glass transition temperature (thereby improving machinability) and improving chemical durability, { Zn ratio²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) It is also preferable that the value is 0.17 or less. From the viewpoint of improving meltability, cation ratio { Zn } is preferred²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0% or more, more preferably more than 0%. Cation ratio { Zn²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 109]

[ Table 110]

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺When the glass composition is contained in an appropriate amount, the refractive index is increased and the thermal stability of the glass is improved. However, Ta⁵⁺Albeit withThe effect of increasing the refractive index, but is an extremely expensive component. Therefore, it is not preferable to actively use Ta from the viewpoint of stable supply of glass⁵⁺. In addition, when Ta⁵⁺When the content of (B) is large, the raw materials tend to melt and remain when the glass is melted. In addition, the specific gravity of the glass increases. Like this, Ta⁵⁺Is an ingredient whose content should be reduced. Therefore, it is not preferable to actively use Ta⁵⁺. For Ta⁵⁺In order to improve the thermal stability of glass and to reduce the high refractive index and dispersion and the amount of Ta used, Ta is used⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or less. Cation ratio { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and preferred upper limits of } are shown in the following table.

[ Table 111]

In addition, for Nb⁵⁺It is preferable to stably supply the glass and to reduce Gd³⁺、Ta⁵⁺In addition to the amount of (A), is desirably in combination with Gd³⁺、Ta⁵⁺Decrease Yb together³⁺While providing a high-refractive-index low-dispersion glass excellent in thermal stability, Nb is being considered⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺Based on the above-mentioned effects, Nb⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or more. Further, Nb⁵⁺And Ta⁵、W⁶⁺In contrast, the refractive index tends to be increased without increasing the specific gravity. Therefore, in order to suppress the increase in specific gravity, it is preferable to set the cation ratio { Nb }⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Large. Cation ratio { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The more preferred lower limits and the preferred upper limits of } are shown in the following table.

[ Table 112]

Further, from the viewpoint of preventing high dispersion and from the viewpoint of coloring, it is preferable to use Ti⁴⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ti }⁴⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.6 or less. Cation ratio { Ti⁴ ⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Preferred lower limits and more preferred upper limits of } are shown in the following table.

[ Table 113]

The present inventors have made extensive studies on the various cationic components described above, and have focused on the fact that the effects of the cationic components on the dispersion (abbe number) of the glass may differ from one another. Further, as a result of further extensive studies, the present inventors have specified coefficients considering the influence of chromatic dispersion given to the glass for each cationic component, and have found that in order to realize optical characteristics in which the abbe number ν d is 39.5 to 41.5 and the refractive index nd and the abbe number ν d satisfy the relationship of the above expression (1), it is preferable to adjust the composition so that the range of the value calculated by the following expression (a) is 8.5000 to 11.000.

A＝0.01×Si⁴⁺In an amount of

+0.01×B³⁺In an amount of

+0.05×La³⁺In an amount of

+0.07×Y³⁺In an amount of

+0.07×Yb³⁺In an amount of

+0.085×Zn²⁺In an amount of

+0.3×Zr⁴⁺In an amount of

+0.5×Ta⁵⁺In an amount of

+0.8×Nb⁵⁺In an amount of

+0.9×W⁵⁺In an amount of

+0.95×Ti⁴⁺Content of … (A)

More preferable lower limits and more preferable upper limits of the value a calculated by the above formula (a) are shown in the following table.

[ Table 114]

Glass C is an oxide glass and therefore contains O as an anionic component^2-。O^2-The preferred lower limits of the amounts of (b) are shown in the following table.

[ Table 115]

O^2-In an amount of
	Preferred lower limit (%)
95
	97
98
	99
99.5
	100

As O^2-Other anionic component, for example, F^-、Cl^-、Br^-、I^-. However, F^-、Cl^-、Br^-、I^-Are volatile in the melting of the glass. Volatilization of these components tends to cause fluctuation in the characteristics of the glass, which lowers the homogeneity of the glass and causes significant consumption of melting equipment. Therefore, F is preferably added^-、Cl^-、Br^-And I^-Is suppressed to a total content of O subtracted from 100 anion%^2-Amount of (b).

For other details regarding the glass composition of glass C, the description regarding the glass composition of glass a can be applied.

[ glass D ]

Next, the glass D will be described.

Glass D according to one embodiment of the present invention is oxide glass: expressed as% of cation, B³⁺、Si⁴⁺、La³⁺、Y³ ⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺The total content of (a) is 90% or more, the Abbe number ν D is in the range of 39.5 to 41.5, the refractive index nd satisfies the above expression (1) with respect to the Abbe number ν D, and the total D of the values obtained by multiplying the content of each cationic component by the coefficient described in Table 1 satisfies the above expression (B) with respect to the refractive index nd, with respect to the cationic components described in Table 1 shown below.

[ Table 116]

TABLE 1

Cationic component	Coefficient of performance
		B³⁺	0.032
Si⁴⁺	0.029
		La³⁺	0.066
Y³⁺	0.053
		Gd³⁺	0.093
Yb³⁺	0.094
		Nb⁵⁺	0.049
Ti⁴⁺	0.045
		Ta⁵⁺	0.104
W⁶⁺	0.111
		Zr⁴⁺	0.080
Zn²⁺	0.051
		Mg²⁺	0.030
Ca²⁺	0.024
		Sr²⁺	0.043
Ba²⁺	0.055
		Li⁺	0.031
Na⁺	0.021
		K⁺	0.012
Al³⁺	0.034
		Bi³⁺	0.090

The details of the glass D will be described below.

< glass composition >

For glasses D, B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺The total content of (main cationic component) is 90% or more. The cation component contained in the above glass may be only the main cation component (that is, the total content of the main cation components is 100%), or 1 or more kinds of other cation components may be contained in addition to the main cation component. Preferred lower limits of the total content of the main cationic components are shown in the following table.

[ Table 117]

The glass composition of the glass D can be adjusted so that the total D of the values obtained by multiplying the contents of the respective cationic components by the coefficients shown in table 1 with respect to the respective cationic components of the main cationic components satisfies the following expression (B) with respect to the refractive index nd.

D≤6.242×nd-6.8042…(B)

Thus, the high-refractive-index low-dispersion glass having an Abbe's number ν d in the range of 39.5 to 41.5 and a refractive index nd satisfying the above expression (1) with respect to the Abbe's number ν d can be reduced in weight. This point is a new finding discovered by the present inventors through intensive studies. The details of the total D are as follows. The following contents are in units of cation%.

D＝B³⁺Content of (2) is 0.032

+Si⁴⁺Content of (b) 0.029

+La³⁺Content of (2) x 0.066

+Y³⁺Content of (2) x 0.053

+Gd³⁺Content of (2) x 0.093

+Yb³⁺Content of (2) x 0.094

+Nb⁵⁺Content of (2) 0.049

+Ti⁴⁺Content of (2) x 0.045

+Ta⁵⁺Content of (2) x 0.104

+W⁶⁺Content of (2) x 0.111

+Zr⁴⁺Content of (2) x 0.080

+Zn²⁺Content of (b) is 0.051

+Mg²⁺Content of (2) x 0.030

+Ca²⁺Content of (2) x 0.024

+Sr²⁺Content of (2) x 0.043

+Ba²⁺Content of (2) × 0.055

+Lⁱ⁺Content of (2) x 0.031

+Na⁺Content of (2) x 0.021

+K⁺Content of (2) 0.012

+Al³⁺Content of (2) x 0.034

+Bi³⁺Content of (2) x 0.090

The above-mentioned formula (B) is preferably the following formula (B-1), more preferably the following formula (B-2), still more preferably the following formula (B-3), yet more preferably the following formula (B-4), yet more preferably the following formula (B-5), yet more preferably the following formula (B-6), yet more preferably the following formula (B-7), yet more preferably the following formula (B-8), and yet more preferably the following formula (B-9).

D≤6.242×nd-6.8142…(B-1)

D≤6.242×nd-6.8242…(B-2)

D≤6.242×nd-6.8342…(B-3)

D≤6.242×nd-6.8442…(B-4)

D≤6.242×nd-6.8542…(B-5)

D≤6.242×nd-6.8642…(B-6)

D≤6.242×nd-6.8742…(B-7)

D≤6.242×nd-6.8842…(B-8)

D≤6.242×nd-6.8942…(B-9)

The glass composition of the glass may be such that the total content of the main cationic components is 90% or more and the formula (B) is satisfied, and a cationic component not contained in the glass (that is, a content of 0%) may be present in the main cationic components. The above description of the glass a and/or the glass C can be applied to the preferable ranges of the contents of the respective cationic components, and the like, and the above description of the glass C can be preferably applied. Further, the above description of the glass a and/or the glass C can be applied to the details of the anion component contained in the glass C, and preferably the above description of the glass C can be applied. However, the glass D is not limited to the ranges described for the glass a and/or the glass C. In addition, as for the glass composition of the glass D, it is also possible to apply the ranges described for the glass a and/or the glass C in consideration of making a glass having transmittance characteristics suitable for the production of an optical system.

Next, the glass characteristics common to the glass a, the glass B, the glass C, and the glass D will be described. The following glasses are referred to as glass a, glass B, glass C, and glass D.

< glass characteristics >

(optical Properties of glass)

The glass has an Abbe number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the following formula (1) with respect to the Abbe number ν d.

nd≥2.0927-0.0058×vd…(1)

Glass having an abbe number ν d of 39.5 or more is effective for correction of chromatic aberration as a material for an optical element. On the other hand, when the abbe number ν d is larger than 41.5, the thermal stability of the glass is significantly lowered if the refractive index is not lowered, and devitrification is liable to occur in the process of manufacturing the glass. Preferred lower limits and preferred upper limits of the abbe number ν d are shown in the following table.

[ Table 118]

The glass has a refractive index nd satisfying the formula (1) with respect to an Abbe's number ν d. The glass having an Abbe number ν d in the range of 39.5 to 41.5 and a refractive index nd satisfying the formula (1) is a glass having a high value of use in designing an optical system.

The upper limit of the refractive index nd is naturally determined depending on the glass composition. In order to obtain a glass which is improved in thermal stability and is less likely to devitrify, it is preferable that the refractive index nd satisfies the following formula (2).

nd≤2.1270-0.0058×vd…(2)

Preferred lower limits and preferred upper limits of the refractive index nd with respect to the abbe number ν d are shown in the following table.

[ Table 119]

The refractive index nd is preferably not less than the lower limit shown in the following table, and preferably not more than the upper limit shown in the following table.

[ Table 120]

(partial Dispersion characteristics)

From the viewpoint of correcting chromatic aberration, the glass is preferably a glass having a small relative dispersion when the abbe number ν d is fixed.

Here, F is expressed as (ng-nF)/(nF-nc) using the refractive indices ng, nF, nc of the g line, F line, and c line, respectively, with respect to the partial dispersion Pg.

In order to provide a glass suitable for the chromatic aberration correction of a high order, preferred lower limits and preferred upper limits of relative partial dispersions Pg, F of the above glasses are shown in the following table.

[ Table 121]

(glass transition temperature)

The glass transition temperature of the glass is not particularly limited, but is preferably 640 ℃ or higher. By setting the glass transition temperature to 640 ℃ or higher, the glass is less likely to be broken when the glass is subjected to mechanical processing such as cutting, polishing, and the like. Further, since the components such as Li and Zn having a strong action of lowering the glass transition temperature are not contained in a large amount, the thermal stability can be easily improved even if the content of Gd and Ta is small and further even if the content of Yb is small.

On the other hand, when the glass transition temperature is too high, the glass must be annealed at a high temperature, and the annealing furnace is considerably consumed. In addition, when glass is molded, it is necessary to mold the glass at a high temperature, and thus the consumption of a mold used for molding becomes significant.

In order to improve the machinability and reduce the burden on the annealing furnace and the molding die, the preferred lower limit and the preferred upper limit of the glass transition temperature are shown in the following table.

[ Table 122]

(light transmittance of glass)

The light transmittance of the glass, specifically, the wavelength increase of the light absorption edge on the short wavelength side can be suppressed, and can be evaluated by the coloring degree λ 5. The coloring degree λ 5 represents a wavelength at which the spectral transmittance (including surface reflection loss) of glass having a thickness of 10mm from the ultraviolet region to the visible region becomes 5%. λ 5 in the examples described later is a value measured in a wavelength region of 250 to 700 nm. The spectral transmittance is, for example, more specifically, a spectral transmittance obtained by using a glass sample polished to a thickness of 10.0 ± 0.1mm and having planes parallel to each other, and by using light incident from a vertical direction on the polished surface, that is, Iout/Iin when the intensity of light incident on the glass sample is Iin and the intensity of light transmitting the glass sample is Iout.

The absorption edge on the short wavelength side of the spectral transmittance can be quantitatively evaluated from the coloring degree λ 5. As described above, when lenses are bonded to each other with an ultraviolet-curable adhesive in order to produce a cemented lens, the adhesive is cured by irradiating ultraviolet rays through an optical element. In order to efficiently cure the ultraviolet-curable adhesive, the absorption edge on the short wavelength side of the spectral transmittance is preferably in the short wavelength region. As an index for quantitatively evaluating the absorption edge on the short wavelength side, the coloring degree λ 5 can be used. The glass can exhibit λ 5 of preferably 335nm or less, more preferably 332nm or less, still more preferably 330nm or less, yet still more preferably 328nm or less, and still more preferably 326nm or less by the composition adjustment described above. As an example, the lower limit of λ 5 can be set to 315nm, but the lower limit is more preferable and is not particularly limited.

On the other hand, an index of the coloring degree of glass is a coloring degree λ 70.λ 70 represents a wavelength at which the spectral transmittance measured by the method described for λ 5 becomes 70%. In order to produce a glass with less coloration, λ 70 is preferably 420nm or less, more preferably 400nm or less, still more preferably 390nm or less, and still more preferably 380nm or less. The lower limit of λ 70 is set to 350nm, but the lower the value, the more preferable, and is not particularly limited.

Further, as an index of the coloring degree of the glass, coloring degree λ 80 can be also mentioned. λ 80 represents a wavelength at which the spectral transmittance measured by the method described for λ 5 becomes 80%. In order to produce a glass with less coloration, λ 80 is preferably 550nm or less, more preferably 500nm or less, still more preferably 490nm or less, and still more preferably 480nm or less. The lower limit of λ 80 is targeted to 355nm, but the lower the value, the more preferable, and is not particularly limited.

(specific gravity of glass)

In an optical element (lens) constituting an optical system, refractive power is defined by the refractive index of glass constituting the lens and the curvature of an optically functional surface (a surface on which light rays to be controlled enter and exit) of the lens. When the curvature of the optically functional surface is intended to be large, the thickness of the glass is also increased. As a result, the lens becomes heavy. On the other hand, if glass having a high refractive index is used, a large refractive power can be obtained even if the curvature of the optically functional surface is large.

From the above, as long as the refractive index can be increased while suppressing an increase in the specific gravity of the glass, it is possible to reduce the weight of the optical element having a fixed refractive power.

The contribution of the refractive index nd to the refractive power can be used as an index for reducing the weight of the optical element by taking the ratio of the specific gravity d of the glass to the value (nd-1) obtained by subtracting the refractive index 1 in vacuum from the refractive index nd of the glass. That is, the weight of the lens can be reduced by using d/(nd-1) as an index for reducing the weight of the optical element and reducing the value.

Since the glass a to C has a small proportion of Gd and Ta which increase the specific gravity and can reduce the proportion of Yb, it is a high-refractive-index low-dispersion glass and can reduce the specific gravity. In the glass D, the total D satisfies the above formula (B) with respect to the refractive index nd, and thus the glass D can have a high refractive index and a low dispersion and can have a low specific gravity. Therefore, the glass can have a d/(nd-1) of, for example, 5.70 or less. However, when d/(nd-1) is excessively decreased, the thermal stability of the glass tends to be lowered. Therefore, d/(nd-1) is preferably set to 5.00 or more. More preferred lower limits and more preferred upper limits of d/(nd-1) are shown in the following tables.

[ Table 123]

Further, preferable lower limits and preferable upper limits of the specific weight d of the glass are shown in the following table. From the viewpoint of weight reduction of an optical element formed of the glass, it is preferable that the specific gravity d is not more than the upper limit shown in the following table. In addition, in order to further improve the thermal stability of the glass, it is preferable to set the specific gravity to be not less than the lower limit shown in the following table.

[ Table 124]

(liquidus temperature)

The liquidus temperature is one of the indicators of the thermal stability of glass. In order to suppress crystallization and devitrification during glass production, the liquidus temperature LT is preferably 1300 ℃ or less, more preferably 1250 ℃ or less. The lower limit of the liquidus temperature LT is 1100 ℃ or more as an example, but the temperature is preferably low and is not particularly limited.

The glass a, the glass B, the glass C and the glass D according to one embodiment of the present invention described above have a large refractive index nd and an abbe number ν D, and are useful as glass materials for optical elements. Further, the above-described composition adjustment can homogenize the glass and reduce coloring. Therefore, the above glass is suitable as an optical glass.

Next, a method for producing glass common to glass a, glass B, glass C, and glass D will be described. The following glasses are referred to as glass a, glass B, glass C, and glass D.

< method for producing glass >

The glass can be obtained by weighing and mixing oxides, carbonates, sulfates, nitrates, hydroxides, and the like as raw materials in such a manner that a target glass composition can be obtained, sufficiently mixing them to prepare a mixed batch, heating, melting, defoaming, stirring them in a melting vessel to prepare a homogeneous molten glass containing no bubbles, and molding it. Specifically, the resin composition can be produced by a known melting method. The glass is a high-refractive-index low-dispersion glass having the above optical properties and is excellent in thermal stability, and therefore can be stably produced by a known melting method or a known molding method.

[ glass Material for Press Molding, optical element blank, and methods for producing these ]

Another mode of the invention relates to

A glass material for press molding comprising the above glass A, glass B, glass C and glass D;

an optical element blank comprising the above-mentioned glass A, glass B, glass C and glass D.

According to another mode of the present invention, there can be also provided

A method for producing a glass material for press molding, which comprises a step of molding the glass A, the glass B, the glass C and the glass D into a glass material for press molding;

a method for producing an optical element blank, which comprises a step of press-molding the glass material for press molding using a press molding die to produce an optical element blank;

a method for producing an optical element blank, comprising the step of molding the above-mentioned glass A, glass B, glass C and glass D into an optical element blank.

The optical element blank is an optical element base material having a shape similar to that of a target optical element, and having a shape of the optical element added with a polishing margin (a surface layer removed by polishing) and, if necessary, a polishing margin (a surface layer removed by polishing). The surface of the optical element blank is ground and polished to complete the optical element. In one embodiment, the optical element blank can be produced by a method of press-molding a molten glass obtained by melting an appropriate amount of the above glass (referred to as a direct press method). In another embodiment, the optical element blank may be produced by solidifying a molten glass obtained by melting an appropriate amount of the above glass.

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

The press molding of the glass material for press molding can be performed by a known method of pressing the glass material for press molding in a softened state by heating with a press mold. Both heating and press forming can be carried out in the atmosphere. The stress inside the glass can be reduced by annealing after press forming, thereby obtaining a homogeneous optical element blank.

The glass material for press molding includes a glass material for press molding which is supplied in an original state to a glass gob for press molding called press molding for producing an optical element blank, and a glass material for press molding which is subjected to mechanical processing such as cutting, grinding, polishing, etc. and is supplied to press molding via the glass gob for press molding. The cutting method includes the following methods: a method of forming a groove in a portion of the surface of a glass plate to be cut by a method called scribing, and cutting the glass plate at the groove portion by applying a local pressure to the groove portion from the side opposite to the side where the groove is formed; a method for cutting a glass sheet by a cutting blade. Further, as a method of polishing, barrel polishing and the like can be cited.

The glass material for press molding can be produced, for example, by casting molten glass into a mold to mold a glass plate, and cutting the glass plate into a plurality of glass sheets. Further, a glass gob for press molding can be produced by molding an appropriate amount of molten glass. The optical element blank can also be produced by heating and softening a press-molding glass gob to perform press molding. A method of manufacturing an optical element blank by heating and softening glass and performing press molding is called a reheating press method as opposed to a direct press method.

[ optical element and method for producing the same ]

Another mode of the invention relates to

An optical element comprising the above glass A, glass B, glass C and glass D.

The optical element is manufactured using the glass. In the optical element, one or more coating layers such as a multilayer film, for example, an antireflection film may be formed on the glass surface.

In addition, according to another mode of the present invention, there can be provided

The method for manufacturing an optical element includes a step of grinding and/or polishing the optical element blank to manufacture the optical element.

In the above-described method for producing an optical element, a known method may be applied for polishing and buffing, and an optical element having high internal quality and surface quality can be obtained by sufficiently washing and drying the surface of the optical element after processing. In this manner, an optical element made of the above glass can be obtained. Examples of the optical element include various lenses such as a spherical lens, an aspherical lens, and a microlens, and a prism.

Further, an optical element formed of the above glass is also suitable as a lens constituting a cemented optical element. Examples of the cemented optical element include an optical element (cemented lens) in which lenses are cemented to each other, and an optical element in which a lens and a prism are cemented to each other. For example, the cemented optical element can be manufactured by precisely processing the cemented surfaces of the two cemented optical elements so that the shapes thereof are reversed (for example, spherical surface polishing), applying an ultraviolet-curable adhesive used for bonding the cemented lens, and irradiating the lens with ultraviolet light to cure the adhesive. In order to produce the cemented optical element in this manner, the above glass is preferable. By producing a plurality of cemented optical elements using a plurality of types of glasses having different abbe numbers ν d, respectively, and performing the cementing, an element suitable for correction of chromatic aberration can be produced.

As a result of quantitative analysis of the glass composition, the glass component may be expressed in terms of oxide, and the content of the glass component may be expressed in terms of mass%. The composition expressed in mass% based on the oxide can be converted into a composition expressed in terms of cation% and anion% by the following method, for example.

When N glass components are contained in the glass, the k-th glass component is represented by A (k)_mO_n. Wherein k is an integer of 1 to N.

A (k) is a cation, O is oxygen, and m and n are integers determined by stoichiometry. For example, B is represented by oxide₂O₃When m is 2, n is 3; in SiO₂In the case of (2), m is 1 and n is 2.

Then, A (k)_mO_nThe content of (c) is X (k) (mass%)]. Here, when the atomic weight of A (k) is P (k) and the atomic number of oxygen O is Q, A (k)_mO_nFormally having a molecular weight R (k) of

R(k)＝P(k)×m+Q×n。

Further, when it is set to

B＝100/{Σ[m×X(k)/R(k)]}

When the cationic component A (k)^s+The content (cation%) of (A) is [ X (k)/R (k)]Xm.times.B (% cation). Here, "Σ" means the sum of m × x (k)/r (k) from k to N. m varies according to k. s is 2 n/m.

The molecular weight r (k) may be calculated by rounding the 4 th digit after the decimal point and expressing the value up to 3 digits after the decimal point. In addition, the molecular weights of some glass components and additives, which are expressed on the basis of oxides, are shown in table a below.

[ Table 125]

TABLE A

Oxide compound	Molecular weight	Oxide compound	Molecular weight
				B₂O₃	69.621	Cs₂O	281.810
SiO₂	60.084	ZnO	81.389
				La₂O₃	325.809	MgO	40.304
Y₂O₃	225.810	CaO	56.077
				Gd₂O₃	362.498	SrO	81.389
Yb₂O₃	394.084	BaO	153.326
				Nb₂O₅	265.810	Al₂O₃	101.961
TiO₂	79.882	Ga₂O₃	187.444
				WO₃	231.839	In₂O₃	277.634
Ta₂O₅	441.893	Sc₂O₃	137.910
				Bi₂O₃	465.959	HfO₂	210.489
ZrO₂	123.223	Lu₂O₃	397.932
				Li₂O	29.882	GeO₂	104.629
Na₂O	61.979	P₂O₅	141.945
				K₂O	94.196	TeO₂	159.599
Rb₂O	186.935	Sb₂O₃	291.518

[ examples ]

The present invention will be further described below based on examples. However, the present invention is not limited to the embodiment shown in the examples.

(example 1)

Compounds such as oxides and boric acid were weighed as raw materials and sufficiently mixed to prepare a batch material so as to obtain glasses having compositions shown in the following tables.

The batch of raw materials are put into a platinum crucible, and are heated to 1350-1450 ℃ together with the crucible, and the glass is melted and clarified for 2-3 hours. After homogenizing molten glass by stirring, the molten glass is cast into a preheated molding die, left to cool to a temperature near the glass transition temperature, and immediately placed in an annealing furnace together with the molding die. Thereafter, annealing was performed at around the glass transition temperature for about 1 hour. After annealing, the resultant was left to cool to room temperature in an annealing furnace.

When the glass thus produced was observed, no crystal precipitation, no bubble, no streak, and no residual melt of the raw material were observed. In this way, glass having high homogeneity can be produced.

In the following tables, Nos. 1-1 to 1-52 are glass A and glass D, Nos. 1-9 and 1-11 to 1-52 are glass C, and Nos. 2-1 to 2-52 are glass B.

Comparative examples 1 to 4

A glass was obtained in the same manner as in example 1, except that compounds such as oxides and boric acid were weighed as raw materials and sufficiently mixed to prepare a batch material so as to obtain glasses having each composition of comparative examples 1 to 4 shown in the following table.

The composition of comparative example 1 is a glass composition expressed in cation% in terms of the composition of glass No.11 of patent document 20;

the composition of comparative example 2 is a glass composition expressed in cation% in terms of the composition of glass No.25 of patent document 20;

the composition of comparative example 3 is a glass composition expressed in cation% in terms of the composition of glass No.45 of patent document 20;

the composition of comparative example 4 is a glass composition expressed in cation% in terms of the composition of glass No.49 of patent document 20.

The glass properties of the obtained glass were measured by the following methods. The measurement results are shown in the following table.

(1) Refractive index nd, nF, nc, ng, Abbe number vd

The glass obtained by cooling at a cooling rate of-30 ℃/hr was measured for refractive indices nd, nF, nc, and ng by a refractometry method standardized by the Japan optical glass industry Association. Abbe number ν d is calculated using the measured values of refractive indices nd, nF, and nc.

(2) Glass transition temperature Tg

The temperature was measured at a temperature rising rate of 10 ℃ per minute using a Differential Scanning Calorimetry (DSC).

(3) Specific gravity of

The measurement was performed by the archimedes method.

(4) The coloring degree is lambda 5, lambda 70, lambda 80

A glass sample having a thickness of 10 + -0.1 mm and having 2 optically polished planes opposed to each other was used, and the intensity Iout of light transmitted through the glass sample was measured by a spectrophotometer with respect to light having an intensity Iin of a polished surface incident from a vertical direction, and the spectral transmittance Iout/Iin was calculated, where λ 5 was a wavelength having a spectral transmittance of 5%, λ 70 was a wavelength having a spectral transmittance of 70%, and λ 80 was a wavelength having a spectral transmittance of 80%.

(5) Relative partial dispersion Pg, F

Calculated from the values of nF, nc and ng measured in the above (1).

(6) Liquidus temperature

The glass was placed in a furnace heated to a predetermined temperature and held for 2 hours, and after cooling, the inside of the glass was observed with an optical microscope of 100 magnifications, and the liquidus temperature was determined depending on the presence or absence of crystals.

[ Table 126-1]

[ Table 126-2]

[ Table 126-3]

[ Table 126-4]

[ tables 126-5]

[ tables 126-6]

[ Table 127-1]

[ Table 127-2]

[ Table 127-3]

[ Table 127-4]

[ Table 127-5]

[ Table 127-6]

FIG. 1 is a graph in which the horizontal axis represents the ratio of each glass of example 1 to each glass of comparative examples 1 to 4, and the vertical axis represents the total D of the values obtained by multiplying the contents of the respective cationic components by the coefficients shown in Table 1.

As shown in fig. 1, the total D of the values obtained by multiplying the contents of the respective cationic components by the coefficients shown in table 1 shows a good correlation with the specific gravity. From the results, it was confirmed that a glass having a low specific gravity was obtained by adjusting the composition so as to satisfy the formula (B) based on the total D.

FIG. 2 is a graph in which Abbe number ν d of each glass of example 1 and each glass of comparative examples 1 to 4 is plotted on the horizontal axis and value A calculated by the above expression (A) is plotted on the vertical axis.

As shown in fig. 2, the value a calculated by the above expression (a) shows a good correlation with the abbe number. From the results, it was confirmed that it is preferable to adjust the abbe number to perform composition adjustment based on the value a.

(example 2)

Using the various glasses obtained in example 1, glass gobs (glass gobs) for press molding were produced. The glass block was heated and softened in the atmosphere, and press-molded with a press mold to prepare a lens blank (optical element blank). The produced lens blank was taken out of the press mold, annealed, and subjected to machining including polishing, thereby producing a spherical lens formed of each glass produced in example 1.

(example 3)

A desired amount of the molten glass prepared in example 1 was press-molded with a press mold to prepare a lens blank (optical element blank). The produced lens blank was taken out of the press mold, annealed, and subjected to machining including polishing, thereby producing a spherical lens formed of each glass produced in example 1.

(example 4)

A glass block (optical element blank) prepared by solidifying the molten glass prepared in example 1 was annealed and subjected to machining including polishing, thereby preparing a spherical lens formed of each glass prepared in example 1.

(example 5)

The spherical lenses produced in examples 2 to 4 were bonded to spherical lenses made of other kinds of glass to produce cemented lenses. The cemented surface of the spherical lenses manufactured in examples 2 to 4 was a convex surface, and the cemented surface of the spherical lens formed of another kind of optical glass was a concave surface. The 2 bonding surfaces are formed so that the absolute values of the radii of curvature of the bonding surfaces are equal to each other. An ultraviolet-curable adhesive for optical element bonding was applied to the bonding surface, and 2 lenses were bonded to each other with the bonding surface. Then, the adhesive applied to the bonding surface was irradiated with ultraviolet rays through the spherical lens manufactured in examples 2 to 4, and the adhesive was cured.

Cemented lenses were produced as described above. The cemented lens has a sufficiently high cemented strength and is a cemented lens having an optical strength of a sufficient degree.

Comparative example 5

Reproduction was performed on glass No.51 (hereinafter referred to as glass I) shown in Table 8 of Japanese patent application laid-open No. 2014-62026. λ 5 of the glass I described in Table 8 of Japanese patent laid-open No. 2014-62026 is 337 nm.

Next, in the same manner as in example 5, a spherical lens made of glass I was produced, and an attempt was made to produce a cemented lens using the produced spherical lens. However, the ultraviolet-curable adhesive applied to the bonding surface is irradiated with ultraviolet rays through a lens made of glass I, and as a result, the ultraviolet transmittance of glass I is low, and therefore, the adhesive cannot be sufficiently cured.

Comparative example 6

Glass A according to one embodiment of the present invention has a cation ratio { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Less than 0.2, and the cation ratio of the glass C is 0.17 or less.

Glass B according to one embodiment of the present invention has a mass ratio of { ZnO/(La) }₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Less than 0.10.

In contrast, the glass of No.6 shown in Table 1 of Japanese patent application laid-open No. 2014-62026 had the cation ratio of 0.578 and the mass ratio of 0.325. In the glass composition of glass No.6 shown in Table 1 of Japanese patent application laid-open No. 2014-62026, if only the composition adjustment is performed to reduce the cation ratio of the glass composition expressed by cation% and the mass ratio of the glass composition expressed by mass%, it appears that it is difficult to suppress crystal precipitation, and therefore, the following glasses are produced.

In the glass composition of No.6 glass shown in Table 1 of Japanese patent application laid-open No. 2014-62026, the mass ratio of the cations in the glass composition expressed by cation% to the glass composition expressed by mass% is made smaller for Zn²⁺(ZnO) was reduced, and the reduced portion was distributed to other components so that the balance of the contents of the other components did not change much, and composition adjustment was performed as shown in the following tables B and C to prepare glasses. The ratios of the glass components in table B are cation ratios, and the ratios of the glass components in table C are mass ratios of the contents of the respective components of the glass composition based on oxides. Specifically, 170g of the glass raw material was mixed and put into a platinum crucible to be melted and clarified at 1400 ℃ for 2 hours. After homogenizing molten glass by stirring, the molten glass is cast into a preheated molding die, left to cool to a temperature near the glass transition temperature, and immediately placed in an annealing furnace together with the molding die. Thereafter, annealing was performed at around the glass transition temperature for about 1 hour. After annealing, the resultant was left to cool to room temperature in an annealing furnace.

Thereafter, the inside of the glass was observed.

FIG. 1 is a photograph of a glass evaluated in comparative example 6. As is apparent from fig. 1, a large amount of crystals precipitated in the glass, and the glass was clouded and lost in transparency.

On the other hand, in the glass a, the glass B, and the glass C according to one embodiment of the present invention, the inclusion ratio of { Zn to + ions { Zn } is performed²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Or mass ratio { ZnO/(La) } or₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) The composition as described in detail earlier is adjusted so that crystal precipitation can be suppressed. In addition, in the glass D, crystal precipitation can also be suppressed.

[ Table 128]

TABLE B

[ Table 129]

Watch C

Finally, the above-described modes are summarized.

According to one embodiment, there is provided a glass a which is an oxide glass in which B is represented by cation%³⁺And Si⁴⁺The total content of La is 43-65%³⁺、Y³⁺、Gd³⁺And Yb³⁺In a total content of 25 to 50%, Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺In a total amount of 3 to 12%, Zr⁴⁺Is 2-8%, B³⁺And Si⁴⁺The total content of (A) to La³ ⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.75, B³ ⁺And Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴ ⁺+Ta⁵⁺+W⁶⁺) 9.00 or less, Zn²⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }² ⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) Less than 0.2, La³⁺Content of (D) relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { La³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.50 to 0.95, Y³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Y }³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 to 0.50 of Gd³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 or less, Nb⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) 0.80 or more, Ta⁵⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or less, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above expression (1) with respect to the Abbe's number ν d.

Further, according to one embodiment, there can be provided a glass B which is an oxide glass, wherein B represents by mass%₂O₃And SiO₂In a total content of 17.5 to 35%, La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The total content of (A) is 45-70%, Nb₂O₅、TiO₂、Ta₂O₅And WO₃The total content of (a) is 3-16%, ZrO₂Is 2-10%, B₂O₃And SiO₂The total content of (A) to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.2 to 0.5, B₂O₃And SiO₂The total content of (B) relative to Nb₂O₅、TiO₂、Ta₂O₅And WO₃The mass ratio of the total content of (A) { (B)₂O₃+SiO₂)/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 2.8 or less, and the content of ZnO relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃The mass ratio of the total content of (1), (ZnO/(La))₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) Less than 0.10, La₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { La }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.55 to 0.98, Y₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃Mass ratio of the total content of (1) { Y }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.02-0.45 of Gd₂O₃Relative to La₂O₃、Y₂O₃、Gd₂O₃And Yb₂O₃(iii) the total content of (a) to (b) { Gd }₂O₃/(La₂O₃+Y₂O₃+Gd₂O₃+Yb₂O₃) 0.10 or less, Nb₂O₅Relative to the content of Nb₂O₅、TiO₂And WO₃Mass ratio of the total content of (1) { Nb }₂O₅/(Nb₂O₅+TiO₂+WO₃) 0.81 or more, Ta₂O₅Relative to the content of Nb₂O₅、TiO₂、Ta₂O₅And WO₃Mass ratio of the total content of (1) { Ta }₂O₅/(Nb₂O₅+TiO₂+Ta₂O₅+WO₃) 0.3 or less, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above expression (1) with respect to the Abbe's number ν d.

The glass a and the glass B satisfy the formula (1), and are high-refractive-index low-dispersion glasses useful in optical systems. Because the ratio of Gd and Ta in the glass composition expressed as cation% in glass A and the ratio of Gd in the glass composition expressed as mass% in glass B are reduced respectively₂O₃、Ta₂O₅The ratio of the cation to the short wavelength side is set so that the supply can be stabilized, and the high thermal stability can be obtained and the wavelength of the short wavelength side light absorption edge can be suppressed from increasing by satisfying the above-mentioned contents, total contents, cation ratio, or mass ratio.

In one embodiment, Gd in the glass A is contained in the glass A from the viewpoint of stable supply of the glass³⁺The content of (B) is preferably 3 cation% or less, Gd in the glass B₂O₃The content of (b) is preferably 6% by mass or less.

In one embodiment, Ta in the glass A is used from the viewpoint of stable supply of the glass⁵⁺Preferably 3.0 cation% or less, Ta₂O₅The content of (b) is preferably 5% by mass or less.

In one embodiment, each of the glass a and the glass B is preferably such that the coloring degree λ 5 is 335nm or less to suppress the wavelength of the short-wavelength side light absorption edge of the glass from increasing.

Further, according to one embodiment, there can be provided a glass C which is an oxide glass, wherein B is³⁺And Si⁴⁺The total content of La is 43-65%³⁺、Y³⁺、Gd³⁺And Yb³⁺In a total content of 25 to 50%, Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶ ⁺In a total amount of 3 to 12%, Zr⁴⁺Is 2-8%, B³⁺And Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70 to 1.42, B³⁺And Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) W is 5.80-7.70⁶⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.50 or less, Zn²⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }² ⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) La of 0.17 or less³⁺Content of (D) relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { La³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.50 to 0.95, Y³⁺Relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Y }³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 to 0.50 of La³⁺、Gd³⁺Relative to the content of Y³ ⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 or less, Ta⁵⁺Relative content ofIn Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ta⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.2 or less, an Abbe's number ν d in the range of 39.5 to 41.5, and a refractive index nd satisfying the above expression (1) with respect to the Abbe's number ν d.

The glass C satisfies the formula (1), and is a high-refractive-index, low-dispersion glass useful in optical systems. The glass can be stably supplied because the ratio of Gd and Ta is reduced in the glass composition, and can obtain high thermal stability and suppress the wavelength increase of the short-wavelength side light absorption edge by satisfying the content, the total content, and the cation ratio.

In one embodiment, the glass C preferably has a value a calculated by the following formula (a) in a range of 8.5000 to 11.0000 in a glass composition expressed in cation%.

In one embodiment, Zr in glass C is preferable⁴⁺Relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Zr⁴⁺Content of (A)/(Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The range of the speed is 0.48-2.20.

In one embodiment, the specific gravity of the glass C is preferably 5.20 or less.

Further, according to one embodiment, there can be provided a glass D which is an oxide glass in which B represents cation%³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺Has a total content of 90% or more, an Abbe's number ν d in the range of 39.5 to 41.5, a refractive index nd satisfying the above expression (1) with respect to the Abbe's number ν d, and a product of the content of each cationic component and a coefficient described in Table 1 with respect to the cationic components described in Table 1The total D of the values satisfies the above expression (B) with respect to the refractive index nd.

The glass D has an Abbe number ν D in the range of 39.5 to 41.5, satisfies the formula (1), and is a high-refractive-index low-dispersion glass useful in an optical system. Further, the glass D can contribute to weight reduction of the optical element.

In one embodiment, the glass D is preferably B³⁺And Si⁴⁺The total content of (B) is in the range of 43 to 65 cation%.

In one embodiment, the glass D is preferably La³⁺、Y³⁺、Gd³⁺And Yb³⁺The total content of (a) is in the range of 25 to 45%.

In one embodiment, glass D is preferably Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺The total content of (a) is in the range of 3 to 12%.

The glass material for press molding, the optical element blank, and the optical element can be produced from the glass a, the glass B, the glass C, or the glass D described above. That is, according to another embodiment, a glass material for press molding, an optical element blank, and an optical element, each of which is formed of glass a, glass B, glass C, or glass D, can be provided.

Further, according to another embodiment, there is provided a method for producing a glass material for press molding, including a step of molding glass a, glass B, glass C, and glass D into a glass material for press molding.

Further, according to another aspect, there is provided a method for manufacturing an optical element blank, including a step of press-molding the glass material for press molding using a press mold to manufacture the optical element blank.

Further, according to another aspect, there is provided a method for producing an optical element blank, comprising the step of molding the above-described glass a, glass B, glass C, and glass D into an optical element blank.

Further, according to another aspect, there is provided a method for manufacturing an optical element including a step of grinding and/or polishing the optical element blank to manufacture an optical element.

The presently disclosed embodiments are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the scope of the claims, not by the description above, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

For example, a glass according to an embodiment of the present invention can be obtained by adjusting the composition described in the specification with respect to the above-described exemplary glass composition.

It is needless to say that 2 or more items described as examples or preferable ranges in the specification can be arbitrarily combined.

In addition, there are cases where a certain glass corresponds to 2 or more kinds of glass among glass a, glass B, glass C, and glass D.

The present invention is useful in the field of manufacturing various optical elements.

Claims

1. One type of glass, which is an oxide glass,

expressed as% of cation, B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺And Bi³⁺The total content of (A) is 90% or more,

Gd³⁺the content of (A) is 3 cation% or less,

Zn²⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³ ⁺) The rate of the reaction is less than 0.2,

the Abbe number vd is in the range of 39.5-41.5,

the refractive index nd is 1.8600 or more, and satisfies the following formula (1) with respect to the Abbe number vd:

nd is not less than 2.0927-0.0058 x ν d … (1), and

for the cationic components described in table 1, the total D of the values obtained by multiplying the contents of the cationic components by the coefficients described in table 1 satisfies the following expression (B) with respect to the refractive index nd:

D≤6.242×nd-6.8042 …(B)，

the cation% means a molar percentage in which the total content of all the cation components contained in the glass is 100%,

the content of each cationic component is a value before% in terms of cation%,

[ Table 1]

2. The glass according to claim 1, wherein,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺The total content of (a) is in the range of 25 to 45%.

3. The glass according to claim 1, wherein,

Zr⁴⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Zr⁴⁺Content of (A)/(Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.5 or more.

4. The glass according to claim 1, wherein,

Zr⁴⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Zr⁴⁺Content of (A)/(Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value is 1.80 or less.

5. The glass according to claim 1, wherein,

B³⁺and Si⁴⁺The total content of (A) to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.70-1.75.

6. The glass according to claim 1, wherein,

B³⁺and Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value is 6.00 or more.

7. The glass according to claim 1, wherein,

B³⁺and Si⁴⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total amount of (A) { (B)³⁺+Si⁴⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 9.00 or less.

8. The glass according to claim 1, wherein,

Nb⁵⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶ ⁺) 0.50 or more.

9. The glass according to claim 1, wherein,

W⁶⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { W }⁶⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 0.45 or less.

10. The glass according to claim 1, wherein,

Zn²⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of { Zn }²⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³ ⁺) It exceeds 0.

11. The glass according to claim 1, wherein,

La³⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { La³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³ ⁺) 0.50-0.95.

12. The glass according to claim 1, wherein,

Y³⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Y }³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³⁺) 0.10 to 0.50.

13. The glass according to claim 1, wherein,

Gd³⁺relative to La³⁺、Y³⁺、Gd³⁺And Yb³⁺Cation ratio of the total content of (1) { Gd³⁺/(La³⁺+Y³⁺+Gd³⁺+Yb³ ⁺) 0.10 or less.

14. The glass according to claim 1, wherein,

La³⁺the content of (A) is 16 cation% or more.

15. The glass according to claim 1, wherein,

Y³⁺the content of (A) is 1 cation% or more.

16. The glass according to claim 1, wherein,

Y³⁺the content of (A) is 20 cation% or less.

17. The glass according to claim 1, wherein,

Yb³⁺the content of (B) is 3.0 cation% or less.

18. The glass according to claim 1, wherein,

Nb⁵⁺relative to the content of Nb⁵⁺、Ti⁴⁺And W⁶⁺Cation ratio of the total content of (1) { Nb⁵⁺/(Nb⁵⁺+Ti⁴⁺+W⁶⁺) 0.85 or more.

19. The glass according to claim 1, wherein,

Ti⁴⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (1) { Ti }⁴⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶ ⁺) 0.50 or less.

20. The glass according to claim 1, wherein,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (A) { (La)³ ⁺+Y³⁺+Gd³⁺+Yb³⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) The value is 4.0 or more.

21. The glass according to claim 1, wherein,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺The total content of (B) relative to Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of (A) { (La)³ ⁺+Y³⁺+Gd³⁺+Yb³⁺)/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 9.0 or less.

22. The glass according to claim 1, wherein,

B³⁺relative to B³⁺And Si⁴⁺Cation ratio of the total content of (1) { B³⁺/(B³⁺+Si⁴⁺) 0.66 or more.

23. The glass according to claim 1, wherein,

B³⁺relative to B³⁺And Si⁴⁺Cation ratio of the total content of (1) { B³⁺/(B³⁺+Si⁴⁺) 0.95 or less.

24. The glass according to claim 1, wherein,

B³⁺the content of (A) is 20 cation% or more.

25. The glass according to claim 1, wherein,

B³⁺the content of (A) is 55 cation% or less.

26. The glass according to claim 1, wherein,

Si⁴⁺the content of (A) is 3 cation% or more.

27. The glass according to claim 1, wherein,

Si⁴⁺the content of (A) is 20 cation% or less.

28. The glass according to claim 1, wherein,

Zn²⁺relative to B³⁺And Si⁴⁺Cation ratio of the total content of { Zn }²⁺/(B³⁺+Si⁴⁺) It exceeds 0.

29. The glass according to claim 1, wherein,

Zn²⁺relative to B³⁺And Si⁴⁺Cation ratio of the total content of { Zn }²⁺/(B³⁺+Si⁴⁺) 0.15 or less.

30. The glass according to claim 1, wherein,

Zn²⁺the content of (A) is 0.05 cation% or more.

31. The glass according to claim 1, wherein,

Zn²⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of { Zn }²⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶ ⁺) It exceeds 0.

32. The glass according to claim 1, wherein,

Zn²⁺relative to the content of Nb⁵⁺、Ti⁴⁺、Ta⁵⁺And W⁶⁺Cation ratio of the total content of { Zn }²⁺/(Nb⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶ ⁺) The value is 1.0 or less.

33. The glass according to claim 1, wherein,

Nb⁵⁺the content of (B) is 1% or more.

34. The glass according to claim 1, wherein,

Nb⁵⁺the content of (B) is 12% or less.

35. The glass according to claim 1, wherein,

Ti⁴⁺the content of (B) is 3.0% or less.

36. The glass according to claim 1, wherein,

Ta⁵⁺the content of (B) is 3.0% or less.

37. The glass according to claim 1, wherein,

W⁶⁺the content of (B) is 3.0% or less.

38. The glass according to claim 1, wherein,

Li⁺the content of (A) is 5 cation% or less.

39. The glass according to claim 1, wherein,

Na⁺the content of (A) is 5 cation% or less.

40. The glass according to claim 1, wherein,

K⁺the content of (A) is 5 cation% or less.

41. The glass according to claim 1, wherein,

Rb⁺the content of (A) is 5 cation% or less.

42. The glass according to claim 1, wherein,

Cs⁺the content of (A) is 5 cation% or less.

43. The glass according to claim 1, wherein,

Li⁺、Na⁺and K⁺Total content of (Li)⁺+Na⁺+K⁺) 5 cation% or less.

44. The glass according to claim 1, wherein,

Mg²⁺the content of (A) is 10 cation% or less.

45. The glass according to claim 1, wherein,

Ca²⁺the content of (A) is 10 positiveIon% or less.

46. The glass according to claim 1, wherein,

Sr²⁺the content of (A) is 10 cation% or less.

47. The glass according to claim 1, wherein,

Ba²⁺the content of (A) is 10 cation% or less.

48. The glass according to claim 1, wherein,

Mg²⁺、Ca²⁺、Sr²⁺and Ba²⁺Total content (Mg) of²⁺+Ca²⁺+Sr²⁺+Ba²⁺) 10 cation% or less.

49. The glass according to claim 1, wherein,

Al³⁺the content of (A) is 10 cation% or less.

50. The glass according to claim 1, wherein,

Ga³⁺the content of (A) is 5 cation% or less.

51. The glass according to claim 1, wherein,

In³⁺the content of (A) is 5 cation% or less.

52. The glass according to claim 1, wherein,

Sc³⁺the content of (A) is 5 cation% or less.

53. The glass according to claim 1, wherein,

Hf⁴⁺the content of (A) is 10 cation% or less.

54. The glass according to claim 1, wherein,

Lu³⁺the content of (A) is 10 cation% or less.

55. The glass according to claim 1, wherein,

Ge⁴⁺the content of (A) is 10 cation% or less.

56. The glass according to claim 1, wherein,

Bi³⁺the content of (A) is 10 cation% or less.

57. The glass according to claim 1, wherein,

B³⁺、Si⁴⁺、La³⁺、Y³⁺、Gd³⁺、Yb³⁺、Nb⁵⁺、Ti⁴⁺、Ta⁵⁺、W⁶⁺、Zr⁴⁺、Zn²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Li⁺、Na⁺、K⁺、Al³⁺、Ga³⁺、In³⁺、Sc³⁺、Hf⁴⁺、Lu³⁺、Ge⁴⁺and Bi³⁺The total content of (A) is 95 cation% or more.

58. The glass according to claim 1, wherein,

P⁵⁺the content of (A) is 4 cation% or less.

59. The glass according to claim 1, wherein,

Te⁴⁺the content of (A) is 5 cation% or less.

60. The glass according to claim 1, wherein,

does not contain Pb, As, Cd, Tl, Be and Se.

61. The glass according to claim 1, wherein,

does not contain U, Th and Ra.

62. The glass according to claim 1, wherein,

the amount of Sb added is converted into Sb₂O₃And Sb₂O₃The amount of Sb added is 0 to 0.11% by mass, assuming that the total content of the other glass components is 100% by mass.

63. The glass according to claim 1, wherein,

the amount of Sn added is converted into SnO₂And SnO₂The amount of Sn added is 0 to 0.5% by mass, assuming that the total content of the other glass components is 100% by mass.

64. The glass according to claim 1, wherein,

the value A calculated by the following formula (A) is 8.5000-11.000,

A＝0.01×Si⁴⁺content of (2) +0.01 XB³⁺Content of (2) +0.05 × La³⁺Content of (2) +0.07 XY³⁺Content of +0.07 XYb³⁺Content of (2) +0.085 XZn²⁺Content of +0.3 XZr⁴⁺Content of (2) +0.5 × Ta⁵⁺Content of +0.8 XNb⁵⁺Content of (2) +0.9 XW⁵⁺Content of (2) +0.95 XTi⁴⁺… (A).

65. The glass according to claim 1, wherein,

O^2-the content of (A) is 95% or more of anion.

66. The glass according to claim 1, wherein,

B³⁺and Si⁴⁺The total content of (B) is in the range of 43 to 65 cation%.

67. The glass according to claim 1, wherein,

La³⁺、Y³⁺、Gd³⁺and Yb³⁺Total content of (La)³⁺+Y³⁺+Gd³⁺+Yb³⁺) Is 25 to 50 cation%.

68. The glass according to claim 1, wherein,

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺and W⁶⁺The total content of (a) is in the range of 3 to 12%.

69. The glass according to claim 1, wherein,

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺and W⁶⁺Total content of (Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) Is 5.5 cation% or more.

70. The glass according to claim 1, wherein,

Nb⁵⁺、Ti⁴⁺、Ta⁵⁺and W⁶⁺Total content of (Nb)⁵⁺+Ti⁴⁺+Ta⁵⁺+W⁶⁺) 11.0 cation% or less.

71. The glass according to claim 1, wherein,

Zr⁴⁺the content of (B) is 2-8 cation%.

72. The glass according to claim 1, wherein,

abbe number vd is 39.6 or more.

73. The glass according to claim 1, wherein,

the Abbe number ν d is 41.4 or less.

74. The glass according to claim 1, wherein,

the nd is more than or equal to 2.0950-0.0058 x ν d.

75. The glass according to claim 1, wherein,

the nd is more than or equal to 2.0970-0.0058 x ν d.

76. The glass according to claim 1, wherein,

the nd is more than or equal to 2.0990-0.0058 x ν d.

77. The glass according to claim 1, wherein,

the nd is more than or equal to 2.101-0.0058 x ν d.

78. The glass according to claim 1, wherein,

the nd is more than or equal to 2.103-0.0058 x ν d.

79. The glass according to claim 1, wherein,

satisfy nd is more than or equal to 2.105-0.0058 x ν d.

80. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1270-0.0058 x ν d.

81. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1230-0.0058 x ν d.

82. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1200-0.0058 x ν d.

83. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1170-0.0058 x ν d.

84. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1140-0.0058 x ν d.

85. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1110-0.0058 x ν d.

86. The glass according to claim 1, wherein,

the nd is less than or equal to 2.1080-0.0058 x ν d.

87. The glass according to claim 1, wherein,

the refractive index nd is 1.8900 or less.

88. The glass according to claim 1, wherein,

f is 0.562 or more relative to the partial dispersion Pg.

89. The glass according to claim 1, wherein,

a glass transition temperature Tg of 640 ℃ or higher.

90. The glass according to claim 1, wherein,

the glass transition temperature Tg is 770 ℃ or lower.

91. The glass according to claim 1, wherein,

the coloring degree lambda 5 is 335nm or less.

92. The glass according to claim 1, wherein,

the coloring degree lambda 70 is 420nm or less.

93. The glass according to claim 1, wherein,

the degree of coloration lambda 80 is 550nm or less.

94. The glass according to claim 1, wherein,

the ratio { d/(nd-1) } of the specific gravity d of the glass to a value (nd-1) obtained by subtracting the refractive index 1 in vacuum from the refractive index nd of the glass is 5.70 or less.

95. The glass according to claim 1, wherein,

the ratio { d/(nd-1) } of the specific gravity d of the glass to a value (nd-1) obtained by subtracting the refractive index 1 in vacuum from the refractive index nd of the glass is 5.00 or more.

96. The glass according to claim 1, wherein,

the specific gravity d is 5.20 or less.

97. The glass according to claim 1, wherein,

the specific gravity d is 4.0 or more.

98. The glass according to claim 1, wherein,

the liquidus temperature LT is 1300 ℃.