JP2011230997A - Optical glass, optical element and preform for precision press forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain optical glass that has a low Abbe number (ν) despite having a refractive index (n) within a desired range, shows a high resistance to solarization, is highly transparent to visible light, has a small partial dispersion ratio, readily softens at a low temperature and can be easily polished, and an optical element and a preform for precision press forming using the same.SOLUTION: The optical glass comprises, based on the whole mass of the glass in a composition expressed in terms of oxide, in mol%, 30.0-70.0% TeOcomponent, 0-25.0% POcomponent and 0-≤20.0% BiOcomponent and undergoes ≤5.0% solarization. The optical element and the preform for precision press forming are made of the optical glass.

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.

For this reason, among optical glasses for producing optical elements, in particular, it has a high refractive index (n _d ) of 1.80 or more and 2.20 or less, which can reduce the weight and size of optical elements and optical systems. The demand for high refractive index and high dispersion glass having an Abbe number (ν _d ) of 25.0 or less is greatly increasing. As such a high refractive index and high dispersion glass, for example, as an optical glass having a refractive index (n _d ) of 1.8 or more and an Abbe number (ν _d ) of around 20, it is represented by Patent Documents 1 and 2. Such tellurite glass is known.

JP 2001-180971 A JP 2006-182577 A JP 2008-105869 A

  When producing an optical element using such glass, a method of grinding and polishing a glass molded product obtained by softening and molding glass (reheat press molding), or cutting and polishing a gob or a glass block There is used a method (precise press molding) in which a preform material or a preform material formed by known flotation molding is heat-softened and pressure-molded with a mold having a highly accurate molding surface.

  However, the glass disclosed in Patent Document 1 and Patent Document 2 has a high glass transition point (Tg), and these glasses were difficult to soften even when heated. For this reason, when preparing a preform material from the glass of Patent Document 1, and trying to fabricate an optical element by heat-softening and press-molding the preform material, it is necessary to increase the temperature at which the preform material is heat-softened. The mold used for press molding and the preform material cause fusion, and the optical characteristics of the optical element are affected.

On the other hand, the glass disclosed in Patent Document 2 has a low Abbe number (ν _d ) because it contains a large amount of TiO ₂ and WO _3, but these glasses are all colored, The transmittance for visible light was low. For this reason, it was difficult for the glass disclosed in Patent Document 2 to achieve both a low Abbe number (ν _d ) of glass and high transparency to visible light.

  On the other hand, the glass disclosed in Patent Document 3 was a glass having a high degree of wear (Aa) as produced by the present inventors. For this reason, all of the glasses disclosed in Patent Document 3 are prone to scratches on the surface and difficult to polish, and it was difficult to improve the polishing processability.

The present invention has been made in view of the above-mentioned problems, and its object is to have a low Abbe number (ν _d ) while the refractive index (n _d ) is within a desired range, Optical glass with good solarization, high transparency to visible light, small partial dispersion ratio, easy to soften at low temperature and easy to polish, optical element using this, and precision press molding preform There is in getting.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and researches. As a result, the TeO ₂ component is contained as an essential component, and the P ₂ O ₅ component and the Bi ₂ O ₃ component are added as necessary. By containing the TeO ₂ component, the P ₂ O ₅ component, and the Bi ₂ O ₃ component within a predetermined range, the glass has a high refractive index, but the dispersion is enhanced and the low Abbe The glass transition point (Tg) is low, the solarization resistance is good, the transmittance for visible light of the glass is increased, the partial dispersion ratio is small, and the wear degree is low. The invention has been completed. Specifically, the present invention provides the following.

(1) 30.0-70.0% of TeO ₂ component, 0-25.0% of P ₂ O ₅ component, Bi ₂ O ₃ component in mol% with respect to the total amount of glass of oxide conversion composition Of 0 to 20.0% or less, and solarization is 5.0% or less.

(2) The optical glass according to (1), wherein 0 to 25.0% of Nb ₂ O ₅ component is contained in mol% with respect to the total amount of the glass having an oxide equivalent composition.

(3) The optical glass according to (2), which has a degree of wear of 300 to 800.

(4) Li ₂ O component 0 to 20.0% in mol% with respect to the total amount of glass in oxide equivalent composition
Na ₂ O component 0 to 20.0%
K ₂ O component 0 to 15.0%
Cs ₂ O component 0 to 15.0%
The optical glass according to any one of (1) to (3), further comprising:

(5) The substance amount sum Rn ₂ O (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) with respect to the total glass substance amount of the oxide equivalent composition is 20.0% or less. The optical glass according to any one of (1) to (4).

(6) The optical glass according to any one of (1) to (5), wherein a wavelength (λ ₇₀ ) showing 70% in spectral transmittance is 500 nm or less.

(7) 0 to 30.0% of ZnO component in mol% with respect to the total amount of glass in oxide equivalent composition
MgO component 0 to 15.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
BaO component 0 to 20.0%
The optical glass according to any one of (1) to (6), further comprising:

(8) Substance amount sum RO (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, Ba) with respect to the total amount of glass of oxide-converted composition is less than 25.0% The optical glass according to any one of (1) to (7).

(9) WO ₃ component 0 to 10.0% in terms of mol% with respect to the total amount of glass in oxide equivalent composition
B ₂ O ₃ component 0 to 30.0%
La ₂ O ₃ component 0 to 10.0%
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 contains substantially no lead compound.

(11) 0 to 30.0% of SiO ₂ component in mol% with respect to the total amount of glass in oxide-converted composition
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 30.0%
ZrO ₂ component 0 to 20.0%
Ga ₂ O ₃ component from 0 to 20.0%
In ₂ O ₃ component 0 to 20.0%
Ta ₂ O ₅ component 0 to 20.0%
TiO ₂ component 0 to 30.0%
Gd ₂ O ₃ component 0 to 25.0%
Y ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 20.0%
Ag ₂ O component 0 to less than 20.0% Sb ₂ O ₃ component 0 to 1.0%
CeO ₂ component 0-1.0%
The optical glass according to any one of (1) to (10), further comprising:

(12) The refractive index (n _d ) of 1.80 or more and 2.20 or less, and the Abbe number (ν _d ) of 16.0 or more and 30.0 or less, according to any one of (1) to (11) Optical glass.

(13) (−0.0016 × ν _d +0.63460) ≦ (θg, F) ≦ () in the range where the partial dispersion ratio (θg, F) is Abbe number (ν _d ) and ν _d ≦ 25. −0.00563 × ν _d +0.75873), and in the range of ν _d > 25, (−0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.0034 × ν _d +0.70300) The optical glass according to any one of (1) to (12).

(14) The optical glass according to any one of (1) to (13), wherein the glass transition point (Tg) is higher than 250 ° C. and lower than or equal to 550 ° C.

(15) An optical element comprising the optical glass according to any one of (1) to (14).

(16) A precision press-molding preform comprising the optical glass according to any one of (1) to (14).

(17) An optical element obtained by precision press molding the preform for precision press molding according to (16).

According to the present invention, the TeO ₂ component is contained as an essential component, and the P ₂ O ₅ component and the Bi ₂ O ₃ component are contained as necessary, thereby increasing the refractive index of the glass. The dispersion is increased, a low Abbe number is obtained, the solarization resistance is improved, the visible light transmittance of the glass is increased, the partial dispersion ratio is small, and the degree of wear is decreased. For this reason, the refractive index (n _d ) has a low Abbe number (ν _d ) while being in the desired range, good solarization resistance, high transparency to visible light, and easy to soften at a low temperature, In addition, an optical glass that can be easily polished, an optical element using the glass, and a preform for precision press molding can be obtained.

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.

In the optical glass of the present invention, the TeO ₂ component is 30.0 to 70.0%, P ₂ O ₅ is 0 to 25.0%, and Bi _{2 in} mol% with respect to the total amount of glass in the oxide equivalent composition. O _3, with a 0 to 20.0%. By suppressing the TeO ₂ component, P ₂ O ₅ component, and Bi ₂ O ₃ component to a predetermined range, the glass has a high refractive index, but the dispersion is increased and a low Abbe number is obtained. Low, the transmittance of the glass to visible light is increased, the glass transition point (Tg) is lowered, and an appropriate degree of wear is brought about. Therefore, the refractive index (n _d ) is within the desired range, but has a low Abbe number (ν _d ), low solarization, high transparency to visible light, small partial dispersion ratio, and low temperature. An optical glass that can be easily softened and easily polished, an optical element using the optical glass, and a preform for precision press molding can be obtained.

  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 expressed in terms of mass% with respect to the total amount of glass in the 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 oxides when melted. It is a composition in which each component contained in the glass is described with the total amount of the generated oxide as 100%.

<About essential and optional components>
The TeO ₂ component is a glass-forming component, and is a component that increases the transmittance while increasing the refractive index and dispersion of the glass. In particular, by setting the content of the TeO ₂ component to 30.0% or more, the dispersion and refractive index of the glass can be increased, so that a desired Abbe number (ν _d ) and refractive index can be obtained. On the other hand, by setting the content of the TeO ₂ component to 70.0% or less, the liquidus temperature of the glass can be lowered and the devitrification resistance at the time of glass formation can be increased. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. Therefore, the content ratio of the TeO ₂ component with respect to the total glass material amount of the oxide conversion composition is preferably 30.0%, more preferably 35.0%, and most preferably 40.0%. Further, the content of the TeO ₂ component is preferably 70.0%, more preferably 65.0%, still more preferably 60.0%, and most preferably less than 55%.
The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The P ₂ O ₅ component is a component that promotes stable glass formation and reduces devitrification of the glass. In particular, by setting the content of the P ₂ O ₅ component to 25.0% or less, it is possible to increase the transmittance and suppress an increase in the glass transition point (Tg) while suppressing a decrease in the refractive index of the glass. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. 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 25.0%, more preferably 23.0%, and most preferably 20.0%. In addition, since the P ₂ O ₅ component is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to easily exhibit the effect, preferably 2.0%, The lower limit is more preferably 4.0%, and most preferably 6.0%.
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. .

The Bi ₂ O ₃ component is a component that increases the refractive index of the glass. In particular, by making the content of the Bi ₂ O ₃ component 20.0% or less, it is possible to facilitate vitrification of the TeO ₂ component and obtain a desired Abbe number (ν _d ) while increasing the dispersion of the glass. Solarization can be reduced, wear resistance can be improved, and at the same time, the liquidus temperature and glass transition point (Tg) of the glass are lowered. It is possible to facilitate press molding. Moreover, if it is contained in a large amount, the transmittance is deteriorated. Therefore, the upper limit of the content ratio of the Bi ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 18.0%, and most preferably 16.0%. Further, since the Bi ₂ O ₃ component is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to facilitate the above effect, it preferably exceeds 0%, The lower limit is more preferably 2.0%, still more preferably 4.0%, and most preferably 8.0%.
The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

Nb ₂ O ₅ component is a component for increasing the refractive index and dispersion of the glass. In particular, by controlling the content of the Nb ₂ O ₅ component to 25.0% or less, while suppressing a decrease in the devitrification resistance of the glass, the transmittance is increased, and at the same time, the abrasion resistance is improved. An increase in Tg) can be suppressed. Moreover, when contained in a large amount, the resistance to solarization is deteriorated. Therefore, the content of the Nb ₂ O ₅ component is preferably 25.0%, more preferably 20.0%, still more preferably 18.0%, most preferably 15.5% with respect to the total amount of glass in the oxide equivalent composition. The upper limit is 0%. In addition, since the Nb ₂ O ₅ component is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to easily exhibit the effect, it is preferably more than 0%, More preferably, the lower limit is 2.0%, more preferably more than 3.0%, and most preferably more than 5.0%.
The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

Li 2 _O component is a component that lowers the melting temperature and the glass transition point of the glass (Tg), which is an optional component of the optical glass of the present invention. In particular, by reducing the Li ₂ O component content to 20.0% or less, the glass expansion coefficient can be reduced to facilitate accurate transfer of the lens surface during press molding while reducing the refractive index of the glass. While suppressing, the transmittance | permeability can be improved and the chemical durability of glass can be improved. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. Therefore, the upper limit of the content of the Li ₂ O 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%.
Further, since Li ₂ O is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to facilitate the above effect, it is preferably 0.5%, more preferably Is 1.0%, more preferably 2.0%.
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.

The Na ₂ O component is a component that lowers the melting temperature and glass transition point (Tg) of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Na ₂ O component to 20.0% or less, it is possible to increase the transmittance and suppress the chemical durability of the glass while suppressing a decrease in the refractive index of the glass. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. Therefore, the upper limit of the content 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 15.0%, and most preferably 10.0%.
Further, since Na ₂ O is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to facilitate the above effect, it is preferably 0.5%, more preferably Is 1.0%, more preferably 2.0%.
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 (Tg), which is an optional component of the optical glass of the present invention. In particular, by setting the content of the K ₂ O component to 15.0% or less, it is possible to increase the transmittance and suppress the chemical durability of the glass while suppressing a decrease in the refractive index of the glass. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. 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 15.0%, more preferably 13.0%, and most preferably 10.0%.
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 of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Cs ₂ O component to 15.0% or less, it is possible to increase the transmittance and suppress the chemical durability of the glass while suppressing a decrease in the refractive index of the glass. Moreover, when it contains abundantly, abrasion resistance will be deteriorated. 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 15.0%, more preferably 13.0%, and most preferably 10.0%.
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.

The ZnO component is a component that increases devitrification resistance at the time of glass formation, reduces coloration of the glass, improves wear resistance, and improves the solubility of the glass, and is an optional component in the optical glass of the present invention. is there. In particular, by setting the content of the ZnO component to 30.0% or less, an increase in the liquidus temperature of the glass due to excessive inclusion of the ZnO component can be suppressed. Accordingly, the content of the ZnO 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%. An optical glass having a desired high dispersion and high press workability can be obtained without containing a ZnO component. However, by containing 1.0% or more of the ZnO component, the glass is transparent to visible light. Since the property is enhanced, the coloring of the glass can be reduced. Therefore, in this case, the content of the ZnO component with respect to the total amount of glass in the oxide-converted composition is preferably 1.0%, more preferably 3.0%, and even more 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.

The MgO component is a component that increases the transmittance in the visible region of the glass and improves the solubility and stability of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the MgO component to 15.0% or less, an increase in the liquidus temperature of the glass can be suppressed while suppressing a decrease in the refractive index of the glass. Therefore, the upper limit of 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 13.0%, 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.

A CaO component is a component which improves the transmittance | permeability in the visible region of glass, improves the solubility and stability of glass, and is an arbitrary component in the optical glass of this invention. In particular, by setting the content of the CaO component to 20.0% or less, it is possible to suppress an increase in the liquidus temperature of the glass while suppressing a decrease in the refractive index of the glass. Accordingly, the content of the CaO 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 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 increases the transmittance in the visible region of the glass and improves the solubility and stability of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the SrO component to 20.0% or less, it is possible to suppress an increase in the liquidus temperature of the glass while suppressing a decrease in the refractive index of the glass. 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 15.0%, and most preferably 10.0%.
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 solubility and stability of the glass, and is an optional component in the optical glass of the present invention. In particular, by controlling the content of the BaO component to 20.0% or less, an increase in the liquidus temperature of the glass can be suppressed while suppressing a decrease in the refractive index of the glass. 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 20.0%, more preferably 15.0%, and most preferably 10.0%.
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 WO ₃ component is a component that increases the refractive index and dispersion of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the WO ₃ component is set to 10.0% or less, the glass transition point (Tg) and the liquidus temperature are prevented from rising, so that a good press is maintained while maintaining good devitrification resistance. Characteristics can be obtained. Moreover, when it contains abundantly, the transmittance | permeability will be deteriorated. 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 less than 5.0%.
The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The B ₂ O ₃ component is a component that constitutes a glass network and increases the devitrification resistance of the glass to homogenize the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the B ₂ O ₃ component 30.0% or less, it is easy to obtain a desired refractive index, the liquidus temperature of the glass is increased, the devitrification resistance is increased, and the wear resistance is improved. Can be.
Therefore, the content of the B ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, still more preferably 9.0%, most preferably 6. The upper limit is 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.

La 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 making the content of the La ₂ O ₃ component 10.0% or less, it is easy to maintain good devitrification resistance while suppressing an increase in the glass transition point (Tg), and to improve wear resistance. can do. Moreover, when it contains abundantly, devitrification resistance will be deteriorated. 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 10.0%, more preferably 8.0%, still more preferably 5.0%, and most preferably 3. The upper limit is 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 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 setting the content of the SiO ₂ component to 30.0% or less, an increase in the glass transition point (Tg) can be suppressed while suppressing a decrease in the refractive index of the glass. Therefore, the content of the SiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, 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.

The GeO 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, an increase in the glass transition point (Tg) can be suppressed by setting the content of the GeO ₂ component to 10.0% or less. Accordingly, the content of the GeO ₂ 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 GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

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, when the content ratio of the Al ₂ O ₃ component is 30.0% or less, a decrease in the refractive index of the glass can be suppressed. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%.
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, by setting the content of the ZrO ₂ component to 20.0% or less, an increase in the glass transition point (Tg) can be suppressed while suppressing a decrease in the devitrification resistance of the glass. Therefore, 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 15.0%, and most preferably 10.0%.
The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

Ga 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 Ga ₂ O ₃ component to 20.0% or less, it is possible to increase the abrasion degree of the glass and facilitate the polishing while enhancing the devitrification resistance of the glass. Therefore, the upper limit of the content of the Ga 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 Ga ₂ O ₃ component can be contained in the glass using, for example, Ga ₂ O ₃ , GaF ₃ or the like 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 the In ₂ O ₃ component to 20.0% or less, it is possible to increase the degree of wear of the glass and facilitate the polishing while enhancing the devitrification resistance of the glass. Therefore, the content ratio 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 even more preferably less than 10.0%. Most preferably, it is less than 5.0%.
The In ₂ O ₃ component can be contained in the glass using, for example, In ₂ O ₃ , InF 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 the Ta ₂ O ₅ component to 20.0% or less, it is possible to suppress an increase in the glass transition point (Tg) while suppressing a decrease in the devitrification resistance of the glass. 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 TiO ₂ component is a component that increases the refractive index and dispersion of the glass and lowers the liquidus temperature of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the TiO ₂ component to 30.0% or less, an increase in the glass transition point (Tg) can be suppressed while suppressing a decrease in the devitrification resistance of the glass. Moreover, when it contains abundantly, the transmittance | permeability will be deteriorated. Therefore, the content of the TiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%.
TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

Gd 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 Gd ₂ O ₃ component to 25.0% or less, an increase in the glass transition point (Tg) can be suppressed while suppressing a decrease in the devitrification resistance of the glass. 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 25.0%, more preferably 20.0%, and most preferably 10.0%.
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.

Y ₂ O ₃ component increases the refractive index of the glass, or to enhance the chemical durability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Y ₂ O ₃ component to 20.0% or less, it is possible to suppress an increase in the glass transition point (Tg) while suppressing a decrease in the devitrification resistance of the glass. Therefore, the content of the Y 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 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.

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 upper limit of 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 15.0%, and most preferably 10.0%.
The Yb ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

The Ag ₂ O component is a component that lowers the glass transition point (Tg) and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Ag ₂ O component to 20.0% or less, good devitrification resistance can be maintained, and deterioration of the transmittance due to the generation of Ag colloid can be suppressed. Therefore, the upper limit of the content ratio of the Ag ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%.
The Ag ₂ O component can be contained in the glass using, for example, AgNO ₃ , AgI or the like 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 made difficult, and the Sb ₂ O ₃ component can be dissolved in a melting facility (especially a noble metal such as Pt). ) And alloying can be made difficult. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.8%, and most preferably 0.5%.
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, it is possible to obtain an optical glass with little coloration and good internal quality. Accordingly, the CeO ₂ component content relative to the total amount of glass in the oxide equivalent composition is preferably 1.0%, more preferably 0.8%, and most preferably 0.5%.
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, excluding Ti, Nb, W, Zr, Ta, La, Gd, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, Eu, Nd, Sm, Tb, Dy, Er, etc. Each of the transition metal components in the glass is colored even when it is contained alone or in combination with a small amount, and the glass is colored and absorbs light at a specific wavelength in the visible range. In glass, it is preferable not to contain substantially. Here, “substantially does not contain” means that it does not contain unless it is mixed as an impurity.

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.

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. By making the total amount of this substance 20.0% or less, the chemical durability of the glass can be enhanced while suppressing a decrease in the refractive index of the glass. In particular, the amount of Rn ₂ O component content relative to the total amount of glass in the oxide-converted composition is preferably 20.0% in that the degree of wear of the optical glass can be reduced to facilitate polishing. The upper limit is more preferably 18.0%, still more preferably 15.0%, and most preferably 10.0%.

  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, and Ba) is 25.0% or less. Is preferred. By making this amount of substance sum 25.0% or less, the abrasion degree of glass becomes low, so that it is possible to facilitate the polishing process to glass. Therefore, the total amount of the RO component content relative to the total glass material amount in oxide equivalent composition is preferably 25.0%, more preferably 23.0%, even more preferably 20.0%, and most preferably 15%. 0.0% is the upper limit.

The glass composition of the present invention, the composition is mol% with respect to the total amount of glass glass oxide composition
However, the composition expressed by mass% of each component present in the glass composition satisfying various properties required in the present invention is not converted to oxide. The composition generally takes the following values.
TeO ₂ component 30.0-75.0 mass% and P ₂ O ₅ component 0-30.0 mass% and Bi ₂ O ₃ component 0-55.0 mass%
And _Nb 2 _{O 5} component from 0 to 35.0% by weight and / or Li ₂ O component 0 to 10.0% by weight and / or Na ₂ O component from 0 to 12.0% by weight and / or _{K 2} O ingredient 0 18.0% by mass and / or Cs ₂ O component 0-40.0% by mass and / or ZnO component 0-30.0% by mass and / or MgO component 0-10.0% by mass and / or CaO component 0 10.0% by mass and / or SrO component 0-15.0% by mass and / or BaO component 0-20.0% by mass and / or WO ₃ component 0-35.0% by mass and / or B ₂ O ₃ component 0 to 30.0% by mass and / or La ₂ O ₃ component 0 to 40.0% by mass and / or SiO ₂ component 0 to 13.0% by mass and / or GeO ₂ component 0 to 20.0% by mass and / or or _Al 2 _{O 3} component 0 to 20.0% by weight and / or Z O ₂ component from 0 to 15.0% by weight and / or _Ga 2 _{O 3} component from 0 to 25.0% by weight and / or _In 2 _{O 3} component from 0 to 25.0% by weight and / or _Ta 2 _{O 5} component 0 40.0% by weight and / or TiO ₂ component from 0 to 15.0% by weight and / or _Gd 2 _{O 3} component from 0 to 40.0% by weight and / or _Y 2 _{O 3} component from 0 to 30.0% by weight and / or _Yb 2 _{O 3} component from 0 to 35.0% by weight and / or Ag ₂ O component from 0 to 30.0% by weight and / or _Sb 2 _{O 3} component 0-1.0% by weight and / or CeO ₂ component 0 1.0% by mass

[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 500 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 predetermined high refractive index (n _d ) and high dispersion. In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.80, more preferably 1.85, most preferably 1.90, preferably 2.20, more preferably 2.20. 18, most preferably 2.15.
Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 16.0, more preferably 16.5, most preferably 17.0, preferably 30.0, more preferably 28. The upper limit is 0, most preferably 25.0. 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.

  The optical glass of the present invention preferably has low solarization. In particular, the solarization in the measurement method according to “Measurement method of solarization of JOGIS04-2005 optical glass” of the optical glass preferably has a solarization of 5.0% or less. As a result, the device incorporating the optical glass is unlikely to deteriorate in color balance even after long-term use. In particular, since the solarization is greatly reduced as the operating temperature is higher, the optical glass of the present invention is particularly effective when used at high temperatures such as in-vehicle use. Therefore, the wear degree of the optical glass of the present invention is preferably 5.0%, more preferably 4.5%, still more preferably 4.0%, and most preferably 3.5%.

  The optical glass of the present invention preferably has a predetermined degree of wear. In particular, the abrasion degree (Aa) in the measuring method according to “JOGIS 10-1994 Measuring method of abrasion degree of optical glass” of optical glass preferably has an abrasion degree of 300 or more and 800 or less. By setting the degree of wear to 300 or more, the glass is easily polished when the polishing process is performed, so that the processing efficiency of the polishing process can be increased and the polishing process can be easily performed. On the other hand, by setting the degree of wear to 800 or less, unnecessary wear and scratches of the optical glass are reduced, so that the optical glass can be easily handled in the polishing process, and the polishing process can be facilitated. Therefore, the abrasion degree of the optical glass of the present invention is preferably 300, more preferably 330, most preferably 350, and the upper limit is preferably 800, more preferably 750, and most preferably 700.

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 500 nm or less, more preferably 480 nm or less, and still more preferably. Is 450 nm or less, and most preferably 440 nm or less. In the optical glass of the present invention, a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is 420 nm or less, more preferably 410 nm or less, still more preferably 405 nm or less, and most preferably 400 nm or less. Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be used as a material for an optical element such as a lens.

  Moreover, it is preferable that the optical glass of this invention has a glass transition point (Tg) higher than 300 degreeC and below 550 degreeC. When the glass transition point (Tg) is higher than 300 ° C., particularly when glass is subjected to polishing, adverse effects due to frictional heat generated by the polishing can be reduced. On the other hand, since the glass transition point (Tg) is 550 ° C. or lower, softening at a lower temperature enables press molding at a lower temperature, reducing oxidation of the mold used for press molding and reducing the mold. The life of the mold can be extended. Accordingly, the glass transition point (Tg) of the optical glass of the present invention is preferably more than 250 ° C., more preferably 280 ° C., further preferably 300 ° C., most preferably 310 ° C., preferably 550 ° C. The upper limit is preferably 530 ° C, and most preferably 500 ° C.

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis. It is represented by a straight line connecting two points and is called a normal line (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 the optical glass of the present invention, the partial dispersion ratio (θg, F) needs to be close to the normal line, and the partial dispersion ratio is preferably small.
More specifically, in the optical glass of the present invention, the partial dispersion ratio (θg, F) is in the range of ν _d ≦ 25 between the Abbe number (ν _d ) and the formula (1): [(−0. 0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0.00563 × ν _d +0.75873)]. 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.
In such a range of ν _d ≦ 25, it is preferable to satisfy the relationship (−0.0016 × ν _d +0.63660) ≦ (θg, F), and (−0.0016 × ν _d +0.63860) ≦ ( It is more preferable to satisfy the relationship of θg, F).
Further, in such a range of ν _d ≦ 25, it is preferable to satisfy the relationship (θg, F) ≦ (−0.00563 × ν _d +0.755673), and (θg, F) ≦ (−0.00563 ×). It is more preferable to satisfy the relationship of ν _d +0.75473), and it is further preferable to satisfy the relationship of (θg, F) ≦ (−0.00563 × ν _d +0.75273).
Further, in the optical glass of the present invention, the partial dispersion ratio (θg, F) is in the range of ν _d > 25 between the Abbe number (ν _d ) and the formula (2): [(−0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.0034 × ν _d +0.70300)].
In such a range of ν _d > 25, it is preferable to satisfy the relationship (−0.0025 × ν _d +0.65910) ≦ (θg, F), and (−0.0025 × ν _d +0.66110) ≦ ( It is more preferable to satisfy the relationship of θg, F).
In such a range of ν _d > 25, it is preferable to satisfy the relationship of (θg, F) ≦ (−0.00340 × ν _d +0.70100), and (θg, F) ≦ (−0.00340 × (ν _d +0.69900) is more preferable, and (θg, F) ≦ (−0.00340 × ν _d +0.69700) is more preferable. 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 curves. 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.
The optical glass of the present invention satisfies such a relationship. That is, it is an optical glass having a high refractive index and high dispersibility and a small partial dispersion ratio.

  In the present invention, the partial dispersion ratio (θg, F) is the refractive index (nC) in the C line (wavelength 656.27 nm) and the F line for the optical glass obtained at a slow cooling rate of -25 ° C / hour. The refractive index (nF) at (wavelength 486.13 nm) and the refractive index (ng) at the g line (wavelength 435.835 nm) are measured, and the formula by (θg, F) = (ng−nF) / (nF−nC) It means the value calculated in.

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. Among them, in particular, it is used for applications of optical elements that transmit visible light into glass, such as lenses, prisms, and mirrors. Is preferred. As a result, chromatic aberration due to the optical element using this optical glass is reduced. Therefore, when used in an optical device such as a camera or a projector, the optical element and the optical system are miniaturized, and high definition and high accuracy are achieved. Imaging characteristics can be realized. 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. 54) and Comparative Examples (No. 1 to No. 2) of the present invention, and refractive indexes (n _d ) and Abbe numbers (ν _d ) of these glasses, Tables 1 to 1 show the results of wavelengths (λ ₇₀ , λ ₅ ), solarization, glass transition point (Tg), abrasion degree (Aa), and partial dispersion ratio (θg, F) at which the spectral transmittance is 70% and 5%. It is shown in FIG. In the table, the composition of each component is indicated by mass%. 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.54) of this invention, and the glass of a comparative example (No.1-No.2), all are an oxide, a hydroxide, respectively equivalent as a raw material of each component, High purity raw materials used in ordinary optical glass such as carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. are selected so that the composition ratios of the respective examples shown in Tables 1 to 6 are obtained. And then uniformly mixed, put into a quartz crucible or platinum crucible, melted in a temperature range of 500-1200 ° C. in an electric furnace depending on the melting difficulty of the glass composition, homogenized with stirring, and then into a mold The glass was produced by casting and slow cooling.

Here, the optical glass of Embodiment (No.1~No.54), the refractive index of the glass of Comparative Example (No.1~No.2) _{(n d)} and Abbe number ([nu _d) is Nippon Kogaku It measured based on glass industry association standard JOGIS01-2003. The glass used in this measurement was annealed under a slow cooling furnace with a slow cooling rate of −25 ° C./hr.

Moreover, about the transmittance | permeability of the optical glass of an Example (No.1-No.54) and the glass of a comparative example (No.1-No.2), it measured according to Japan Optical Glass Industry Association standard JOGIS02-2003. . 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 is measured in accordance with JISZ8722 to measure the spectral transmittance with respect to light having a wavelength of 200 to 800 nm, and λ ₇₀ (wavelength at 70% transmittance) and λ ₅ (wavelength at 5% transmittance) was determined.

  Moreover, about the solarization of the optical glass of an Example (No.1-No.54) and the glass of a comparative example (No.1-No.2), it measured according to Japan Optical Glass Industry Association standard JOGIS04-2005. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured in accordance with JISZ8722 to measure the spectral transmittance with respect to light having a wavelength of 200 to 800 nm before and after ultraviolet irradiation, and the transmittance before ultraviolet irradiation is 70%. The amount of decrease in transmittance after irradiation at the corresponding wavelength was determined.

  Moreover, the glass transition point (Tg) of the optical glass of an Example (No.1-No.54) and the glass of a comparative example (No.1-No.2) is a differential heat measuring apparatus (STAC 409 CD made by Netchgeretebau). ). The sample particle size at this time was set to 425-600 micrometers, and the temperature increase rate was 10 degrees C / min.

Moreover, the abrasion degree of the optical glass of an Example (No.1-No.54) and the glass of a comparative example (No.1-No.2) is based on "the measuring method of the abrasion degree of JOGIS10-1994 optical glass". Measured. That is, a sample of a glass square plate having a size of 30 × 30 × 10 mm is placed on a fixed position of 80 mm from the center of a flat plate made of cast iron (250 mmφ) horizontally rotating 60 times per minute, and a load of 9.8 N (1 kgf) is applied. While applying vertically, a polishing solution obtained by adding 10 g of lapping material (alumina A abrasive grains) of # 800 (average particle size 20 μm) to 20 mL of water is uniformly fed for 5 minutes to cause friction, and the sample mass before and after the lapping is measured. Then, the wear mass was obtained. Similarly, the wear mass of the standard sample specified by the Japan Optical Glass Industry Association was obtained,
Abrasion degree = {(wear weight / specific gravity of sample) / (wear weight / specific gravity of standard sample)} × 100.

Moreover, the partial dispersion ratio (θg, F) of the optical glass of the example (No. 1 to No. 54) and the glass of the comparative example (No. 1 to No. 2) is set to -25 ° C. / About the optical glass obtained sometimes, refractive index (nC) in C line (wavelength 656.27 nm), refractive index (nF) in F line (wavelength 486.13 nm), refractive index in g line (wavelength 435.835 nm) (Ng) was measured and calculated by an equation according to θg, F = (ng−nF) / (nF−nC).

As shown in Tables 1 to 6, all of the optical glasses according to the examples of the present invention have a refractive index (n _d ) of 1.80 or more, more specifically 1.90 or more. The rate (n _d ) was 2.20 or less, more specifically 2.10 or less, and was within the desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 30.0 or less, more specifically 25.0 or less, and an Abbe number (ν _d ) of 16.0 or more. there were. For this reason, it became clear that the optical glass of the Example of this invention has a desired low Abbe number ((nu) _d ).

Further, in all of the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at a transmittance of 70%) was 500 nm or less, more specifically 450 nm or less. Further, in the optical glass of the example of the present invention, λ ₅ (wavelength at 5% transmittance) was 420 nm or less, more specifically, 405 nm or less. For this reason, it became clear that the optical glass of the Example of this invention was difficult to color, and its transparency with respect to visible light was high.

Moreover, the optical glass of the Example of this invention all had the solarization of 5.0% or less. On the other hand, in the optical glasses of Comparative Examples 1 and 2, solarization was 5.0% or more. For this reason, it became clear that the optical glass of the Example of this invention has a good solarization compared with the glass of Comparative Examples 1 and 2.

  Further, the optical glass of the example of the present invention had a glass transition point (Tg) of 550 ° C. or lower, more specifically 420 ° C. or lower. Moreover, the optical glass of the Example of this invention had a glass transition point (Tg) higher than 250 degreeC, and was 370 degreeC or more in detail. For this reason, it became clear that the optical glass of the Example of this invention has a low glass transition point (Tg), and is easy to soften at low temperature.

  In addition, the optical glasses of the examples of the present invention all had a wear degree of 800 or less, more specifically 700 or less, and the wear degree was 300 or more, more specifically 400 or more. For this reason, it became clear that the optical glass of the Example of this invention has a low abrasion degree, and its workability at the time of glass grinding | polishing is favorable. On the other hand, the degree of wear of the optical glass of Comparative Example 2 was 702. For this reason, it became clear that the optical glass of the Example of this invention has a favorable abrasion degree compared with the glass of the comparative example 2. FIG.

In the optical glass of the example of the present invention, the partial dispersion ratio (θg, F) is (−0.00250 × ν _d +0.65710) or more at ν _d > 25 in relation to the Abbe number (ν _d ). More specifically, it is (−0.00250 × ν _d +0.66110) or more, (−0.00340 × ν _d +0.70300) or less, and more specifically (−0.00340 × ν d + 0.70100) or less. And (−0.00160 × ν _d +0.63460) or more at νd ≦ 25, more specifically (−0.00160 × ν _d +0.63860) or more, and (−0.00563 × ν _d). +0.758583) or less. For this reason, it became clear that the optical glass of the example of the present invention has a partial dispersion ratio (θg, F) close to the normal line and small chromatic aberration.

Therefore, the optical glass of the embodiment of the present invention has good solarization and is easy to soften at a low temperature while having a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, and in the visible range. It became clear that the transparency of the film was high and polishing was easy to perform.

  Furthermore, using the optical glass of the example of the present invention, after forming a preform for polishing, grinding and polishing were performed to form lenses and prisms. In addition, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded into a lens and a prism. In either case, it could be processed into various lens and prism 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 (17)

TeO ₂ component is 30.0-70.0%, P ₂ O ₅ component is 0-25.0%, Bi ₂ O ₃ component is 0 Optical glass containing 20.0% or less and solarization of 5.0% or less. The glass the total amount of substance of the oxide composition in terms of the mole percent _Nb 2 _{O 5} component containing from 0 to 25.0% claim 1, wherein the optical glass. The optical glass according to claim 2, having an abrasion degree of 300 to 800. Li ₂ O component 0 to 20.0% in mol% with respect to the total amount of glass in oxide-converted composition
Na ₂ O component 0 to 20.0%
K ₂ O component 0 to 15.0%
Cs ₂ O component 0 to 15.0%
The optical glass according to claim 1, further comprising: The total amount of substances Rn ₂ O (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) with respect to the total amount of glass in an oxide equivalent composition is 20.0% or less. Optical glass in any one of 1-4. The optical glass according to any one of claims 1 to 5, wherein a wavelength (λ ₇₀ ) showing a spectral transmittance of 70% is 500 nm or less. ZnO component 0 to 30.0% in mol% with respect to the total amount of glass in oxide-converted composition
MgO component 0 to 15.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
BaO component 0 to 20.0%
The optical glass according to claim 1, further comprising: The total amount of substances RO (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, Ba) with respect to the total amount of glass in oxide-converted composition is less than 25.0%. The optical glass according to any one of 1 to 7. WO ₃ component 0 to 10.0% in mol% with respect to the total amount of glass in oxide-converted composition
B ₂ O ₃ component 0 to 30.0%
La ₂ O ₃ component 0 to 10.0%
The optical glass according to claim 1, further comprising: The optical glass according to any one of claims 1 to 9, which contains substantially no lead compound. SiO ₂ component 0 to 30.0% in mol% with respect to the total amount of glass in oxide-converted composition
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 30.0%
ZrO ₂ component 0 to 20.0%
Ga ₂ O ₃ component from 0 to 20.0%
In ₂ O ₃ component 0 to 20.0%
Ta ₂ O ₅ component 0 to 20.0%
TiO ₂ component 0 to 30.0%
Gd ₂ O ₃ component 0 to 25.0%
Y ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 20.0%
Ag ₂ O component 0 to less than 20.0% Sb ₂ O ₃ component 0 to 1.0%
CeO ₂ component 0-1.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 1, which has a refractive index (n _d ) of 1.80 or more and 2.20 or less and an Abbe number (ν _d ) of 16.0 or more and 30.0 or less. (−0.0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0...) In a range where the partial dispersion ratio (θg, F) is Abbe number (ν _d ) and ν _d ≦ 25. 00563 × ν _d +0.75873) is satisfied, and (−0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ − (0.0034 × ν _d +0.70300) in the range of ν _d > 25. The optical glass according to claim 1, wherein the optical glass satisfies the relationship of The optical glass according to any one of claims 1 to 13, wherein the glass transition point (Tg) is higher than 250 ° C and lower than 550 ° C. An optical element made of 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 16.

Images