JP2010105906A - Optical glass, optical element, and preform for precision press-molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical glass having high thermal stability and less discoloring although the glass has a refractive index (n<SB>d</SB>) in a desired range, and to provide an optical element and a preform for precision press-molding using the optical glass. <P>SOLUTION: The optical glass contains, by mol% with respect to the whole mass of the glass having a composition in terms of oxides, 10.0 to 95.0% of TeO<SB>2</SB>component, 1.0 to 50.0% of B<SB>2</SB>O<SB>3</SB>component, 0 to 20.0% of GeO<SB>2</SB>component, 0 to 20.0% of SiO<SB>2</SB>component and 0 to 20.0% of P<SB>2</SB>O<SB>5</SB>component. The preform for precision press-molding comprises the optical glass; and the optical element is obtained by subjecting the optical glass to precision press-molding. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an optical glass, an optical element, and a precision press-molding preform.

  In recent years, the digitization and high definition of devices that use optical systems have been rapidly progressing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, The demand for light weight and downsizing is increasing.

Demand for a high refractive index glass having a high refractive index (n _d ) of 1.85 or more and 2.20 or less that can reduce the weight and size of the optical element, among optical glasses for producing optical elements. Is growing very much. As such a high refractive index glass, for example, a tellurite glass represented by Patent Document 1 is known as an optical glass having a refractive index (n _d ) of 1.886 or more and 1.963 or less. As an optical glass having a rate (n _d ) of 1.971 or more and 2.021 or less, tellurite glass represented by Patent Document 2 is known.

International Publication No. 2006/001346 Pamphlet JP 2006-182577 A

  As a method for manufacturing such an optical element, a preform material obtained by cutting and polishing a gob or a glass block, or a preform material formed by a known floating molding or the like is heated and softened to have a highly accurate molding surface. The pressure molding method (precision press molding) is used.

  However, many of the glasses disclosed in Patent Document 1 have a small difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx), and the thermal stability of these glasses was low. Therefore, when a preform material is produced from this glass and an optical element is produced by heating and softening and molding the preform material, the produced optical element is devitrified or optically deformed due to crystallization of the heat-softened glass. The optical characteristics of the element were affected.

  Moreover, many of the glasses disclosed in Patent Document 2 are colored brown overall. The colored glass has been greatly lost in transparency in the visible range, and is not suitable as a material for optical elements.

The present invention has been made in view of the above-mentioned problems, and the object thereof is to have high thermal stability and coloration while the refractive index (n _d ) is within a desired range. The object is to obtain a small amount of optical glass, an optical element using the same, and a preform for precision press molding.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies. As a result, the TeO ₂ component and the B ₂ O ₃ component are used together as essential components, and the TeO ₂ component, the B ₂ O ₃ component, the GeO _By suppressing the content of the _two components, the SiO ₂ component, and the P ₂ O ₅ component within a predetermined range, the refractive index of the glass is increased, and the transparency of the glass in the visible region is increased, and the glass transition point ( The difference ΔT between Tg) and the crystallization start temperature (Tx) was found to be large, and the present invention was completed. Specifically, the present invention provides the following.

(1) TeO ₂ component is 10.0 to 95.0%, B ₂ O ₃ component is 1.0 to 50.0%, and GeO ₂ component in mol% with respect to the total amount of glass in oxide conversion composition. 0 to 20.0%, SiO ₂ component 0 to 20.0%, and P ₂ O ₅ component 0 to 20.0% optical glass.

(2) The optical glass according to (1), wherein the substance amount ratio (GeO ₂ + SiO ₂ + P ₂ O ₅ ) / (TeO ₂ + B ₂ O ₃ ) of the oxide equivalent composition is less than 0.076.

(3) The optical glass according to (1) or (2), which further contains less than 2.5% of a TiO ₂ component in mol% with respect to the total amount of the glass having an oxide conversion composition.

(4) WO ₃ component 0 to 10.0% and / or Bi ₂ O ₃ component 0 to 10.0% in mol% with respect to the total amount of glass in the oxide equivalent composition
The optical glass according to any one of (1) to (3), further comprising:

(5) The optical glass according to (3) or (4), wherein the substance amount sum TiO ₂ + WO ₃ + Bi ₂ O ₃ with respect to the total amount of the glass having an oxide conversion composition is from 0% to 5.0% in mol%. .

(6) La ₂ O ₃ component 0 to 30.0% and / or Gd ₂ O ₃ component 0 to 30.0% and / or Y ₂ O in mol% with respect to the total amount of glass in the oxide conversion composition ₃ components 0 to 30.0% and / or Ta ₂ O ₅ components 0 to 20.0% and / or In ₂ O ₃ components 0 to 20.0%
The optical glass according to any one of (1) to (5), further comprising:

(7) The optical glass according to any one of (1) to (6), further containing less than 5.0% of a Ga ₂ O ₃ component in mol% with respect to the total amount of glass having an oxide equivalent composition.

(8) Substance amount ratio M / (TeO ₂ + B ₂ O ₃ ) in oxide equivalent composition (wherein, M is TiO ₂ , WO ₃ , Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂₎ Any one of (3) to (7), wherein at least one selected from the group consisting of O ₃ , Ta ₂ O ₅ , Ga ₂ O ₃ and In ₂ O ₃ is 0.020 or more and 0.240 or less. The optical glass described.

(9) relative to the glass the total amount of substance of the oxide composition in terms of, 0~25.0% Li ₂ O component in mol% and / or Na ₂ O component from 0 to 20.0% and / or _{K 2} O ingredient 0 20.0% and / or Cs ₂ O component 0 to 20.0% and / or MgO component from 0 to 15.0% and / or CaO component 0 to 20.0% and / or SrO component 0 to 20.0 % And / or BaO component 0 to 30.0% and / or ZnO component 0 to 50.0% and / or Al ₂ O ₃ component 0 to 20.0% and / or ZrO ₂ component 0 to 20.0% and / Or Nb ₂ O ₅ component 0 to 30.0% and / or Yb ₂ O ₃ component 0 to 20.0% and / or Sb ₂ O ₃ component 0 to 1.0% and / or CeO ₂ component 0 to 1 .0%
The optical glass according to any one of (1) to (8), further comprising:

(10) The optical glass according to any one of (1) to (9), which has a refractive index (n _d ) of 1.85 or more and 2.20 or less and an Abbe number (ν _d ) of 10 or more and 40 or less.

  (11) The optical glass according to any one of (1) to (10), wherein the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 100 ° C. or higher.

  (12) An optical element formed by precision press molding the optical glass according to any one of (1) to (11).

  (13) A precision press-molding preform comprising the optical glass according to any one of (1) to (11).

  (14) An optical element obtained by precision press-molding the precision press-molding preform described in (13).

According to the present invention, a TeO ₂ component and a B ₂ O ₃ component are used in combination as essential components, and the content of TeO ₂ component, B ₂ O ₃ component, GeO ₂ component, SiO ₂ component, and P ₂ O ₅ component By keeping the value within a predetermined range, the refractive index of the glass is increased, the transparency of the glass in the visible region is enhanced, and the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is large. Become. For this reason, an optical glass having high thermal stability and little coloring while having a refractive index ( _nd ) within a desired range, an optical element using the optical glass, and a precision press molding preform are obtained. Can do.

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

In the optical glass of the present invention, the TeO ₂ component is 10.0 to 95.0% and the B ₂ O ₃ component is 1.0 to 50.0 in mol% with respect to the total amount of the glass having an oxide equivalent composition. %contains. TeO ₂ component and B ₂ O ₃ component are used in combination as essential components, and the content of TeO ₂ component, B ₂ O ₃ component, GeO ₂ component, SiO ₂ component, and P ₂ O ₅ component is suppressed within the above range. As a result, the refractive index of the glass is increased, and the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is considered to be increased, so that the devitrification resistance of the glass can be increased. Further, by combining the TeO ₂ component and B ₂ O ₃ component, since the transparency of the glass is increased in the visible region, it is possible to reduce the coloration of the glass. Therefore, it is possible to obtain an optical glass having high thermal stability and little coloring while having a refractive index (n _d ) within a desired range.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In the present specification, unless otherwise specified, the content of each component is all expressed in mol% with respect to the total amount of glass having an oxide equivalent composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into an oxide when melted. The composition represents the respective components contained in the glass, with the total amount of the generated oxide as 100 mol%.

<About essential and optional components>
The TeO ₂ component is a component that constitutes a glass network, increases the refractive index of the glass, and lowers the partial dispersion ratio (θg, F) of the glass. In particular, vitrification can be facilitated by setting the content of the TeO ₂ component to 10.0% or more. On the other hand, by setting the content of TeO ₂ components below 95.0%, it is possible to improve the devitrification resistance of the glass. Accordingly, the content of the TeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 15.0%, and most preferably 20.0%, and preferably 95. The upper limit is 0%, more preferably 85.0%, and most preferably 75.0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The B ₂ O ₃ component is a component constituting a glass network. In particular, the stability of the glass can be further improved by setting the content of the B ₂ O ₃ component to 1.0% or more. On the other hand, by setting the content of the B ₂ O ₃ component to 50.0% or less, the refractive index of the glass is hardly lowered, and the chemical durability such as the water resistance of the glass can be increased. Accordingly, the content of the B ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 1.0%, more preferably 3.0%, and most preferably 5.0%, and preferably The upper limit is 50.0%, more preferably 45.0%, and most preferably 40.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material.

The GeO ₂ component is a component that increases the internal transmittance of the glass, constitutes a glass network, stabilizes the glass, and reduces devitrification during molding, and is an optional component in the optical glass of the present invention. . In particular, by setting the content of the GeO ₂ component to 20.0% or less, the glass transition point (Tg) and the melting temperature can be lowered. Accordingly, the content of the GeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The SiO ₂ component is a component that promotes stable glass formation and reduces devitrification of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the SiO ₂ component 20.0% or less, it is possible to easily obtain a desired refractive index of glass. Therefore, the content of the SiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

P ₂ O ₅ component is a component constituting the network of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the P ₂ O ₅ component to 20.0% or less, the devitrification tendency can be reduced and the stability of the glass can be increased. Therefore, the content of the P ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material. .

In the optical glass of the present invention, the substance amount ratio of the substance amount sum (GeO ₂ + SiO ₂ + P ₂ O ₅ ) to the substance amount sum (TeO ₂ + B ₂ O ₃ ) is preferably less than 0.076. By making the amount of this substance less than 0.076, the formation of crystal nuclei and crystal growth in the molten glass are reduced, and the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) becomes large. Since it is considered, it is possible to increase the devitrification resistance of the glass and to make the glass less milky. Therefore, the substance amount ratio (GeO ₂ + SiO ₂ + P ₂ O ₅ ) / (TeO ₂ + B ₂ O ₃ ) with respect to the total glass substance amount of the oxide conversion composition is preferably less than 0.076, more preferably 0.073. Most preferably, the upper limit is 0.070.

TiO ₂ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, when the content of the TiO ₂ component is less than 2.5%, a decrease in the internal transmittance of the glass due to the TiO ₂ component is suppressed, so that the glass having a desired high transmittance while having a high refractive index. Can be obtained. Therefore, the content of the TiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably less than 2.5%, more preferably 2.0%, and most preferably 1.5%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The WO ₃ component is a component that increases the refractive index and dispersibility of the glass and increases the partial dispersion ratio (θg, F) of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the WO ₃ component to 10.0% or less, it is possible to reduce the coloring of the glass when the glass is exposed to ultraviolet light. Therefore, the upper limit of the content of the WO ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. In particular, when a WO ₃ component is contained, absorption tends to occur at a specific wavelength in the visible range. Therefore, it is preferable that the WO ₃ component is not substantially contained in terms of coloring of the glass. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

Bi ₂ O ₃ component, increasing the refractive index of the glass, the partial dispersion ratio of glass ([theta] g, F) or to enhance the, are optional components of the optical glass of the present invention. In particular, the internal transmittance of the glass can be made difficult to decrease by setting the content of the Bi ₂ O ₃ component to 10.0% or less. Therefore, the content of the Bi ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

In the optical glass of the present invention, it is preferable that the substance amount sum of the contents of the TiO ₂ component, the WO ₃ component, and the Bi ₂ O ₃ component is more than 0% and not more than 5.0%. By making this amount of substance sum more than 0%, it is possible to maintain the desired refractive index of the glass while increasing the internal transmittance of the glass. Further, by setting the amount of this substance to 5.0% or less, it is possible to maintain the desired internal transmittance of the glass while increasing the refractive index of the glass. Therefore, the total amount of substances (TiO ₂ + WO ₃ + Bi ₂ O ₃ ) with respect to the total amount of glass in the oxide conversion composition is preferably more than 0%, more preferably 1.0%, and most preferably 2.0%. The lower limit is preferably set to 5.0%, more preferably 4.5%, and most preferably 4.0%.

The La ₂ O ₃ component is a component that suppresses devitrification during glass molding, and is an optional component in the optical glass of the present invention. In particular, by making the content of the La ₂ O ₃ component 30.0% or less, vitrification can be facilitated and the melting temperature can hardly be increased. Therefore, the content of the La ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like as a raw material.

The Gd ₂ O ₃ component is a component that suppresses devitrification during glass molding, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Gd ₂ O ₃ component 30.0% or less, vitrification can be facilitated and the melting temperature can hardly be increased. Therefore, the content of the Gd ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The Gd ₂ O ₃ component can be contained in the glass using, for example, Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

The Y ₂ O ₃ component is a component that suppresses devitrification during glass molding, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Y ₂ O ₃ component 30.0% or less, vitrification can be facilitated and the melting temperature can be made difficult to increase. Accordingly, the content of the Y ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The Y ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ or the like as a raw material.

Ta ₂ O ₅ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Ta ₂ O ₅ component below 20.0%, it is possible to reduce the devitrification of the glass during molding. Accordingly, the content of the Ta ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The In ₂ O ₃ component is a component that increases the refractive index of the glass and is an optional component in the optical glass of the present invention. In particular, by setting the content of _In 2 _{O 3} component below 20.0%, it is possible to increase the stability of the glass. Therefore, the content of the In ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The In ₂ O ₃ component can be contained in the glass using, for example, In ₂ O ₃ as a raw material.

Ga ₂ O ₃ component increases the refractive index of the glass, or to enhance the Knoop hardness of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of _Ga 2 _{O 3} component to less than 5.0%, it is possible to increase the stability of the glass. Further, since the Ga ₂ O ₃ component is a very expensive raw material, it is desirable that the content of the Ga ₂ O ₃ component is small in terms of suppressing the material cost of the glass. Therefore, the Ga ₂ O ₃ component content relative to the total amount of glass in the oxide equivalent composition is preferably less than 5.0%, more preferably 4.0%, and most preferably 3.0%. . The Ga ₂ O ₃ component can be contained in the glass using, for example, Ga ₂ O ₃ as a raw material.

In the optical glass of the present invention, the substance amount sum (TiO ₂ + WO ₃ + Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Y ₂ O ₃ + Ta ₂ O ₅ + Ga ₂ O with respect to the substance amount sum (TeO ₂ + B ₂ O ₃ ). ₃ + In ₂ O ₃ ) is preferably 0.020 or more and 0.240 or less. By making this amount of substance sum 0.020 or more, it is possible to easily obtain a glass having a desired high refractive index. Moreover, since it is considered that the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is increased by setting the total amount of this material to 0.240 or less, the devitrification resistance of the glass is increased. Can do. Therefore, the substance amount ratio (TiO ₂ + WO ₃ + Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Y ₂ O ₃ + Ta ₂ O ₅ + Ga ₂ O ₃ + In ₂ O ₃ ) / the total amount of glass in the oxide conversion composition / (TeO ₂ + B ₂ O ₃ ) is preferably 0.020, more preferably 0.050, still more preferably 0.080, most preferably 0.100, and preferably 0.240, more preferably 0. 220, most preferably 0.200.

Li 2 _O component is a component that lowers the melting temperature and the glass transition point of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Li 2 _O component below 25.0%, it is possible to improve the chemical durability of the glass. Therefore, the content ratio of the Li ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 25.0%, more preferably 20.0%, still more preferably 17.0%, and most preferably 15.0. % Is the upper limit. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

Na 2 _O component is a component that lowers the melting temperature and the glass transition point of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Na 2 _O component below 20.0%, it is possible to improve the chemical durability of the glass. Therefore, the upper limit of the content ratio of the Na ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component that lowers the melting temperature and the glass transition point of the glass, an optional component of the optical glass of the present invention. In particular, the content of K 2 _O component by below 20.0%, it is possible to improve the chemical durability of the glass. Therefore, the upper limit of the content of the K ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

Cs 2 _O component is a component that lowers the melting temperature and the glass transition point of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Cs 2 _O component below 20.0%, it is possible to improve the chemical durability of the glass. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. Cs ₂ O component may be contained in the glass by using as the starting material for example _Cs 2 _{CO 3,} CsNO 3, and the like.

In the optical glass of the present invention, the content amount of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is 20.0% or less. Preferably there is. The chemical durability of the glass can be increased by setting the total amount of these substances to 20.0% or less. Accordingly, the upper limit of the amount of the RO component content relative to the total amount of glass in the oxide equivalent composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%.

The MgO component is a component that improves the stability of the glass and is an optional component in the optical glass of the present invention. In particular, when the content of the MgO component is 15.0% or less, glass formation can be facilitated, and the melting temperature and the glass transition point (Tg) can be lowered. Therefore, the content of the MgO component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The MgO component can be contained in the glass using, for example, MgCO ₃ or MgF ₂ as a raw material.

The CaO component is a component that improves the stability of the glass and is an optional component in the optical glass of the present invention. In particular, when the content of the CaO component is 20.0% or less, glass formation can be facilitated, and the melting temperature and the glass transition point (Tg) can be lowered. Therefore, the upper limit of the CaO component content with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component that improves the stability of the glass and is an optional component in the optical glass of the present invention. In particular, when the content of the SrO component is 20.0% or less, glass formation can be facilitated, and the melting temperature and the glass transition point (Tg) can be lowered. Therefore, the upper limit of the content of the SrO component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

The BaO component is a component that improves the stability of the glass and is an optional component in the optical glass of the present invention. In particular, when the content of the BaO component is 30.0% or less, glass formation can be facilitated, and the melting temperature and the glass transition point (Tg) can be lowered. Therefore, the upper limit of the content of the BaO component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

The ZnO component is a component that stabilizes the glass and is an optional component in the optical glass of the present invention. In particular, the glass melting temperature can be lowered by setting the content of the ZnO component to 50.0% or less. Therefore, the content of the ZnO component with respect to the total amount of glass in the oxide conversion composition is preferably 50.0%, more preferably 45.0%, and most preferably 40.0%. Even when the ZnO component is not contained, it is possible to obtain an optical glass having high thermal stability and little coloration. However, by making the content of the ZnO component 1.0% or more, the glass can be obtained. Since the devitrification resistance is improved, it is possible to easily obtain an optical glass that transmits light having a wavelength in the visible range. At this time, the content of the ZnO component with respect to the total amount of glass in the oxide conversion composition is preferably 1.0%, more preferably 3.0%, and most preferably 5.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

  In the optical glass of the present invention, the content amount of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 30.0% or less. Preferably there is. By making this amount of substance sum 30.0% or less, glass formation can be made easy and a melting temperature and a glass transition point (Tg) can be made low. Accordingly, the upper limit of the amount of the RO component content relative to the total amount of glass in the oxide equivalent composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%.

The Al ₂ O ₃ component is a component that increases the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, the desired refractive index can be easily obtained by setting the content of the Al ₂ O ₃ component to 20.0% or less. Therefore, the upper limit of the content ratio of the Al ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The ZrO ₂ component is a component that increases the refractive index of the glass and suppresses devitrification in the process of cooling the glass from the molten state, and is an optional component in the optical glass of the present invention. In particular, when the content of the ZrO ₂ component is 20.0% or less, the glass is easily melted at a lower temperature, so that energy loss during glass production can be reduced. Therefore, the upper limit of the content of the ZrO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

Nb ₂ O ₅ component increases the refractive index of the glass, the partial dispersion ratio of glass ([theta] g, F) or to enhance the, are optional components of the optical glass of the present invention. In particular, by setting the content of Nb ₂ O ₅ component below 30.0%, it is possible to reduce the devitrification of the glass during molding. Accordingly, the content of the Nb ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material. If the content of the Nb ₂ O ₅ component is within this range, there is no technical disadvantage in particular, but if the content of the Nb ₂ O ₅ component is 1.0% or more, high refraction is achieved. A glass having a high transmittance and a high transmittance can be obtained. The content value of the Nb ₂ O ₅ component at this time is preferably 1.0%, more preferably 1.5%, and most preferably 2.0%.

Yb ₂ O ₃ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Yb ₂ O ₃ component to 20.0% or less, it is possible to easily maintain good devitrification resistance while maintaining a desired optical constant. Therefore, the content of the Yb ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Yb ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

The Sb ₂ O ₃ component is a component that promotes defoaming of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, excessive foaming at the time of melting the glass can be prevented, and the Sb ₂ O ₃ component can be dissolved in a melting facility (particularly a precious metal such as Pt). ) And alloying can be made difficult. Therefore, the upper limit of the content of the Sb ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 1.0%, more preferably 0.9%, and most preferably 0.8%. The Sb ₂ O ₃ component can be contained in the glass using, for example, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O, or the like as a raw material.

The CeO ₂ component is a component effective for clarifying the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the CeO ₂ component is 1.0% or less, an optical glass with good internal quality can be obtained. Accordingly, the CeO ₂ component content relative to the total amount of glass in the oxide equivalent composition is preferably 1.0%, more preferably 0.9%, and most preferably 0.8%. However, when a CeO ₂ component is contained, absorption tends to occur at a specific wavelength in the visible range. Therefore, it is preferable that the CeO ₂ component is not substantially contained in terms of coloring of the glass. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

In addition, the component which clarifies and defoams glass is not limited to the above Sb ₂ O ₃ component or CeO ₂ component, but a known clarifier or defoamer in the field of glass production, or a combination thereof. Can be used.

<About ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

Other components can be added as necessary within the range not impairing the properties of the glass of the present invention. However, the transition metal components such as Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding La, Gd, and Y, can be contained in a small amount by combining them individually or in combination. In particular, optical glass that transmits light having a wavelength in the visible region is preferably substantially free from being colored because it has the property of being colored and absorbing at a specific wavelength in the visible region. In addition, since the Nb ₂ O ₅ component also has a property that the glass is colored when the content is large, particularly in an optical glass that transmits light having a wavelength in the visible region, Nb relative to the total amount of glass in the oxide-converted composition. The content of ₂ O ₅ component is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

The glass composition of the present invention is not expressed directly in terms of mass% because the composition is expressed in terms of mol% with respect to the total amount of glass in the oxide-converted composition, but is required in the present invention. The composition represented by mass% of each component present in the glass composition satisfying the characteristics generally takes the following values in terms of oxide conversion.
TeO ₂ component 10.0-95.0 mass% and B ₂ O ₃ component 0.5-30.0 mass%
And GeO ₂ component 0 to 15.0% by mass and / or SiO ₂ component 0 to 10.0% by mass and / or P ₂ O ₅ component 0 to 20.0% by mass and / or TiO ₂ component 0 to 1.5 Mass% and / or WO ₃ component 0 to 15.0 mass% and / or Bi ₂ O ₃ component 0 to 30.0 mass% and / or La ₂ O ₃ component 0 to 45.0 mass% and / or Gd ₂ O ₃ component 0 to 45.0 mass% and / or Y ₂ O ₃ component 0 to 40.0 mass% and / or Ta ₂ O ₅ component 0 to 45.0 mass% and / or Ga ₂ O ₃ component 0 10.0% by mass and / or In ₂ O ₃ component 0-45.0% by mass and / or Li ₂ O component 0-7.0% by mass and / or Na ₂ O component 0-10.0% by mass and / or or _{K 2} O ingredient from 0 to 15.0% by weight and / or Cs ₂ O components 0-30. 0% by mass and / or MgO component 0-5.0% by mass and / or CaO component 0-8.0% by mass and / or SrO component 0-13.0% by mass and / or BaO component 0-30.0% by mass % And / or ZnO component 0 to 25.0 mass% and / or Al ₂ O ₃ component 0 to 13.0 mass% and / or ZrO ₂ component 0 to 15.0 mass% and / or Nb ₂ O ₅ component 0 40.0% by weight and / or _Yb 2 _{O 3} component from 0 to 40.0% by weight and / or _Sb 2 _{O 3} component 0-1.0% by weight and / or CeO ₂ component 0-1.0 wt%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a quartz crucible or an alumina crucible and roughly melted, and then a gold crucible, a platinum crucible, a platinum alloy It is prepared by putting in a crucible or iridium crucible, melting in a temperature range of 700 to 1200 ° C., stirring and homogenizing, blowing out bubbles, etc., then lowering to an appropriate temperature, casting into a mold and slow cooling. .

[Physical properties]
The optical glass of the present invention needs to have a high refractive index (n _d ) and preferably has an appropriate dispersibility. In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.85, more preferably 1.87, and most preferably 1.90, preferably 2.20, more preferably 2.10. 15, most preferably 2.10. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 10, more preferably 14, most preferably 18 as a lower limit, preferably 40, more preferably 38, most preferably 35. . As a result, the degree of freedom in optical design is increased, and a large amount of light refraction can be obtained even if the device is made thinner.

  Further, the optical glass of the present invention needs to have as high a thermal stability as possible. In particular, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is preferably 100 ° C., more preferably 120 ° C., still more preferably 125 ° C., and most preferably 129 ° C. Thereby, a preform material such as a precision press-molding preform was produced from the optical glass of the present invention, and even if an optical element was produced by heating and softening this, including devitrification due to crystallization of the glass, The influence on the optical characteristics of the optical element can be reduced.

Further, the optical glass of the present invention needs to be less colored. In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is 450 nm or less, more preferably 445 nm or less, and most preferably. Is 440 nm or less. Thereby, since the transparency of the glass in the visible region is enhanced, this optical glass can be preferably used as a material for an optical element such as a lens used for light having a wavelength in the visible region. Similarly, a wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 405 nm or less, more preferably 400 nm or less, and most preferably 395 nm or less.

In the optical glass of the present invention, the partial dispersion ratio (θg, F) is preferably close to the normal line. More specifically, the partial dispersion ratio of the optical glass of the present invention ([theta] g, F) is between the Abbe number ([nu _d), in the region of _{ν d ≦ 25 (-0.0016 × ν} d +0. 6346) ≦ (θg, F) ≦ (−0.0058 × ν _d +0.7559), and (−0.0025 × ν _d +0.6571) ≦ (θg) in the range of ν _d > 25. , F) ≦ (−0.0020 × ν _d +0.6609). Accordingly, the position of the plot of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is brought close to the normal line (Normal Line) in FIG. 1 while having high dispersion. Therefore, it can be inferred that chromatic aberration due to an optical element using this optical glass is reduced. Here, the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−0.0016 × ν _d +0.6346), more preferably (−0.0016 × ν _d +0.6366). ), Most preferably (−0.0016 × ν _d +0.6386) as the lower limit, preferably (−0.0058 × ν _d +0.7559), more preferably (−0.0058 × ν _d +0.7539). ), More preferably (−0.0058 × ν _d +0.7519), and most preferably (−0.0058 × ν _d +0.7509). The partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−0.0025 × ν _d +0.6571), more preferably (−0.0025 × ν _d +0.6591). Most preferably, (−0.0025 × ν _d +0.6611) is the lower limit, preferably (−0.0020 × ν _d +0.6609), more preferably (−0.0020 × ν _d +0.6589). The upper limit is more preferably (−0.0020 × ν _d +0.6569), and most preferably (−0.0020 × ν _d +0.6559).

Here, the partial dispersion ratio (θg, F) represents partial dispersibility in a short wavelength region, and is represented by the formula (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

The normal line is a straight line representing a linear relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ), and the vertical axis represents the partial dispersion ratio (θg, F). It is represented by a straight line connecting two points plotting the partial dispersion ratio and the Abbe number of NSL7 and PBM2 on the orthogonal coordinates adopting the Abbe number (ν _d ) on the horizontal axis (see FIG. 1). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA, Inc., and the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7. Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the partial dispersion ratio (θg, F) of general glass is high. And the Abbe number (ν _d ) are represented by a curve (in FIG. 2, a curve rising to the right). However, since it is difficult to approximate this curve, the present invention uses a straight line having a different slope from ν _d = 25 as a partial dispersion ratio (θg, F) lower than that of general glass. Expressed.

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. In particular, it is possible to produce an optical element such as a lens from the optical glass of the present invention using means such as precision press molding. preferable. As a result, when used in an optical device such as a camera, it is possible to reduce the size of the optical system in these optical devices while realizing high-definition and high-precision imaging characteristics. An optical element made of the optical glass of the present invention includes an objective lens and a solid immersion lens (SIL), optical fiber, optical waveguide, and optical amplification used for recording or reading of an optical recording medium such as a CD and a DVD. It can also be used as an element. Here, in order to produce an optical element made of the optical glass of the present invention, it is possible to omit cutting and polishing, so that glass in a molten state is dropped from an outlet of an outflow pipe of platinum or the like to form a spherical shape. It is preferable to prepare a precision press-molding preform such as, and perform precision press-molding on the precision press-molding preform.

Compositions of Examples (No. 1 to No. 15) and Reference Examples (No. 1 to 2) of the present invention, and refractive indexes (n _d ), Abbe numbers (ν _d ), and partial dispersion ratios of these glasses (Θg, F), glass transition point (Tg), crystallization start temperature (Tx), difference between glass transition point and crystallization start temperature (ΔT), and wavelength at which the spectral transmittance is 70% and 5% (λ ₇₀ , λ ₅ ) are shown in Tables 1 to 3. Moreover, the relationship between the Abbe number (ν _d ) and the partial dispersion ratio (θg, F) in the glasses of Examples (No. 5 to No. 15) and Comparative Examples (No. 1 to No. 2) is shown in FIG. Show. The following examples are merely for illustrative purposes, and are not limited to these examples.

  As for the optical glass of the Example (No.1-No.15) of this invention, and the glass of a reference example (No.1-2), all are an oxide, a hydroxide, and carbonate which are respectively corresponded as a raw material of each component. , Nitrates, fluorides, hydroxides, metaphosphoric acid compounds, and other high-purity raw materials used in ordinary optical glass are selected and weighed so as to have the composition ratios of the respective examples shown in Tables 1 to 3. And then uniformly mixed, then put into a quartz crucible or platinum crucible, melted in a temperature range of 700-1000 ° C. in an electric furnace according to the melting difficulty of the glass composition, stirred and homogenized, and cast into a mold, The glass was produced by slow cooling.

Here, the refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg) of the optical glass of the example (No. 1 to No. 15) and the glass of the reference example (No. _{1 to 2} ). , F) was determined by measuring the glass obtained at a slow cooling rate of -25 ° C / h based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, with respect to the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F), the slope a in the relational expression (θg, F) = − a × ν _d + b is 0.0016, 0.0020. , 0.0025 and 0.0058 were obtained.

  Moreover, (DELTA) T of the optical glass of an Example (No.1-No.15) and the glass of a reference example (No.1-2) was measured using the differential-thermal-measurement apparatus (STAC409CD by a Netchgeretebau company). It calculated | required from the difference of a transition point (Tg) and crystallization start temperature (Tx). The sample particle size at this time was set to 425-600 micrometers, and the temperature increase rate was 10 degrees C / min.

Moreover, about the transmittance | permeability of the optical glass of an Example (No.1-No.15) and the glass of a reference example (No.1-2), it measured according to Japan Optical Glass Industry Association standard JOGIS02. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₇₀ (wavelength at 70% transmittance) and λ ₅ (transmittance). Wavelength at 5%).

As shown in Tables 1 to 3, all of the optical glasses of the examples of the present invention have a λ ₇₀ (wavelength at 70% transmittance) of 450 nm or less, more specifically, 444 nm or less. It became clear that it was within the range and was less colored. In particular, optical glass lambda ₇₀ is equal to or less than 436nm examples (No.2 and 4,6), less the lambda ₇₀ as compared to Reference Example lambda ₇₀ is not less than 437 nm (No.1 and No.2) It was. In addition, in all the optical glasses of the examples of the present invention, λ ₅ (wavelength at 5% transmittance) was 405 nm or less, more specifically 395 nm or less, and was within a desired range. In particular, the optical glass of Examples (Nos. 2 to 13 and 15) has λ ₅ of 389 nm or less, and λ ₅ is smaller than those of Reference Examples (No. 1 and No. 2) in which λ ₅ is 390 nm or more. It was. For this reason, it became clear that the optical glass of an Example (No. 2 and 4, 6) was hard to color compared with the glass of a reference example.

  Further, in the optical glasses of the examples of the present invention, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 100 ° C. or more, more specifically 106 ° C. or more, and the desired range. It was found to have high thermal stability. Among these, the optical glass of Examples (No. 1, 3, 4, 6, 10, 12 to 15) has a difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) of 120 ° C. As mentioned above, it was 129 degreeC or more in detail. In particular, the optical glass of the examples (No. 1, 3, 4, 12 and 15) has a ΔT of 130 ° C. or higher and a reference value of ΔT of less than 129 ° C. (No. 1 and No. 2). ΔT was high. For this reason, it became clear that the optical glass of an Example (No. 1, 3, 4, 12, and 15) has high thermal stability compared with the glass of a reference example.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.85 or more, more specifically 1.92 or more, and this refractive index (n _d ) is 2.20 or less. More specifically, it was 2.04 or less, and was within a desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 10 or more, more specifically 19 or more, and the Abbe number (ν _d ) of 40 or less, more specifically 25. And within the desired range.

Therefore, it has been clarified that the optical glass of the example of the present invention has high thermal stability and little coloring while the refractive index (n _d ) is within a desired range.

Furthermore, as shown in FIG. 2, the optical glasses of Examples (No. 1 to No. 15) of the present invention all have ν _d ≦ 25 and the partial dispersion ratios (θg, F) are Abbe numbers. (−0.0016 × ν _d +0.6346) or more in relation to (ν _d ), more specifically, (−0.0016 × ν _d +0.6386) or more, and this partial dispersion ratio (θg, F) was (−0.0058 × ν _d +0.7559) or less, and was within the desired range. In particular, in the optical glasses of Examples (No. 1, No. 5 to No. 15) of the present invention, the partial dispersion ratio (θg, F) is (−0.0058 ×) in relation to the Abbe number (ν _d ). ν _d +0.7539) or less. On the other hand, in the glass of Reference Example (No. 2), the partial dispersion ratio (θg, F) exceeded (−0.0058 × ν _d +0.7539) while ν _d ≦ 25. The glass of Reference Example (No. 1) had a partial dispersion ratio (θg, F) exceeding (−0.0020 × ν _d +0.6589) while ν _d > 25. For this reason, the optical glass of the Example (No.1, No.5-No.15) of this invention is compared with the glass of a reference example (No.1 and No.2), partial dispersion ratio ((theta) g, F). ) Is close to the normal line, and chromatic aberration was found to be small.

  In addition, as for the optical glass of the Example of this invention, all have a glass transition point (Tg) of 100 degreeC or more, more specifically 400 degreeC or more, and this glass transition point (Tg) is 438 degreeC or less, and more details. Was 433 ° C. or lower. On the other hand, the glass of the reference examples (No. 1 and No. 2) had a glass transition point (Tg) higher than 438 ° C. Therefore, the optical glass of the example of the present invention has a glass transition point (Tg) lower than that of the glass of the reference example and is softened at a lower temperature, so that it is clear that press molding is easy at a low temperature. .

  Furthermore, when a precision press-molding preform was formed using the optical glass of the embodiment of the present invention, and the precision press-molding preform was precision press-molded, it could be stably processed into various lens shapes. .

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

Claims (14)

TeO ₂ component is 10.0 to 95.0%, B ₂ O ₃ component is 1.0 to 50.0%, and GeO ₂ component is Optical glass containing 20.0%, SiO ₂ component 0 to 20.0%, and P ₂ O ₅ component 0 to 20.0%. _2. The optical glass according to claim 1, wherein a substance amount ratio (GeO ₂ + SiO ₂ + P ₂ O ₅ ) / (TeO ₂ + B ₂ O ₃ ) having an oxide equivalent composition is less than 0.076. 3. The optical glass according to claim 1, further comprising less than 2.5% of a TiO ₂ component in mol% with respect to the total amount of the glass having an oxide conversion composition. WO ₃ component 0 to 10.0% and / or Bi ₂ O ₃ component 0 to 10.0% in mol% with respect to the total amount of glass in the oxide conversion composition
The optical glass according to claim 1, further comprising: 5. The optical glass according to claim 3, wherein the total amount of substances TiO ₂ + WO ₃ + Bi ₂ O ₃ with respect to the total amount of glass having an oxide equivalent composition is 0% to 5.0% by mol%. The glass the total amount of substance of the oxide composition in terms of, from 0 to 30.0% _La 2 _{O 3} component in mol% and / or _Gd 2 _{O 3} component from 0 to 30.0% and / or _Y 2 _{O 3} component 0 30.0% and / or _Ta 2 _{O 5} component from 0 to 20.0% and / or _In 2 _{O 3} component from 0 to 20.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 1, further containing less than 5.0% of a Ga ₂ O ₃ component in mol% with respect to the total amount of the glass having an oxide conversion composition. Substance amount ratio M / (TeO ₂ + B ₂ O ₃ ) in oxide equivalent composition (wherein M is TiO ₂ , WO ₃ , Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , The optical glass according to any one of claims 3 to 7, wherein one or more selected from the group consisting of Ta ₂ O ₅ , Ga ₂ O ₃ and In ₂ O ₃ is 0.020 or more and 0.240 or less. Li ₂ O component 0-25.0% and / or Na ₂ O component 0-20.0% and / or K ₂ O component 0-20. 0% and / or Cs ₂ O component 0-20.0% and / or MgO component 0-15.0% and / or CaO component 0-20.0% and / or SrO component 0-20.0% and / or Or BaO component 0 to 30.0% and / or ZnO component 0 to 50.0% and / or Al ₂ O ₃ component 0 to 20.0% and / or ZrO ₂ component 0 to 20.0% and / or Nb ₂ O ₅ component 0 to 30.0% and / or Yb ₂ O ₃ component 0 to 20.0% and / or Sb ₂ O ₃ component 0 to 1.0% and / or CeO ₂ component 0 to 1.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 1, having a refractive index (n _d ) of 1.85 or more and 2.20 or less and an Abbe number (ν _d ) of 10 or more and 40 or less.   The optical glass according to claim 1, wherein a difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 100 ° C. or more.   An optical element formed by precision press-molding the optical glass according to claim 1.   A precision press-molding preform comprising the optical glass according to claim 1.   An optical element formed by precision press-molding the precision press-molding preform according to claim 13.

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