JP2012240909A - Optical glass, preform and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass having a small partial dispersion ratio (θg, F), while a refractive index and an Abbe number are in each desired range, and having a high transmittance and little coloring to a wider wavelength of a visible ray, and to provide a preform and an optical element using the optical glass.SOLUTION: This optical glass contains in mol%, a 10.0-60.0% SiOcomponent and a >0% TaOcomponent with respect to the glass whole material amount having a composition in terms of oxides, and the wavelength (λ) at which the spectral transmittance shows 70% is ≤500 nm.

Description

  The present invention relates to an optical glass, a preform, and an optical element.

  Optical systems such as digital cameras and video cameras, although large and small, contain blurs called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration. In particular, the chromatic aberration is strongly dependent on the material characteristics of the lens used in the optical system.

  In general, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens. However, this combination can only correct aberrations in the red region and the green region, and remains in the blue region. This blue region aberration that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, it is necessary to perform an optical design in consideration of the trend of the g-line (435.835 nm) in the blue region. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics to be noticed in the optical design. In the optical system combining the low dispersion lens and the high dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low dispersion side lens, and the partial dispersion ratio ( By using an optical material having a small θg, F), the secondary spectrum is corrected well.

The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

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.)

  Here, as glass with a small partial dispersion ratio, for example, optical glasses as shown in Patent Documents 1 to 3 are known.

JP 2008-297198 A International Publication No. 2001/072650 Pamphlet JP-A-10-265238

However, since the glass disclosed in Patent Documents 1 to 3 has low refractive index (n _d ) and high Abbe number (ν _d ), and thus has low dispersion, it is a lens that corrects the secondary spectrum described above. Not suitable for use. That is, an optical glass having both a small partial dispersion ratio (θg, F) and high refractive index and high dispersion optical characteristics is required.

  Further, when correcting the secondary spectrum using an optical glass having both a small partial dispersion ratio (θg, F) and high refractive index and high dispersion optical characteristics, visible light is transmitted through the optical glass. Therefore, there is a demand for optical glass that has high transmittance with respect to visible light and less coloring in order to obtain light with a corrected secondary spectrum with higher accuracy.

  The present invention has been made in view of the above-described problems, and the object of the present invention is that the partial dispersion ratio (θg, F) is small while the refractive index and the Abbe number are within the desired ranges, and Another object of the present invention is to obtain an optical glass having a high transmittance with respect to a wider wavelength range of visible light and a little coloring, and a preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted extensive test studies. As a result, the SiO ₂ component and the Ta ₂ O ₅ component are used in combination, and by adjusting the content thereof, the high refractive index of glass. In addition, the wavelength at which the partial dispersion ratio (θg, F) of the glass has a desired relationship with the Abbe number (ν _d ) and the spectral transmittance is 70% while achieving high dispersion (λ ₇₀ ) has been found to be shorter and the present invention has been completed. Specifically, the present invention provides the following.

(1) It contains 10.0 to 60.0% of SiO ₂ component and more than 0% of Ta ₂ O ₅ component in mol% with respect to the total amount of glass in oxide conversion composition, and the spectral transmittance is An optical glass having a wavelength (λ ₇₀ ) showing 70% of 500 nm or less.

(2) as oxide with respect to the glass the total amount of substance of the composition, the content of _Ta 2 _{O 5} component is not more than 25.0% by mole% (1), wherein the optical glass.

(3) the glass the total amount of substance of the oxide composition in terms of, from 0 to 30.0% Li ₂ O component in mol% and / or Na ₂ O component from 0 to 30.0% and / or _{K 2} O ingredient 0 15.0% and / or Cs ₂ O component from 0 to 10.0%
The optical glass according to (1) or (2), further comprising:

(4) The sum of the contents of the Rn ₂ O component (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 5.0. % Or more and 50.0% or less of the optical glass according to (3).

(5) The optical glass according to (3) or (4), wherein the molar ratio Ta ₂ O ₅ / (Li ₂ O + Na ₂ O) with respect to the total amount of glass having an oxide conversion composition is 0.010 or more.

(6) Nb ₂ O ₅ component 0 to 30.0% and / or TiO ₂ component 0 to 20.0% in mol% with respect to the total amount of glass in the oxide conversion composition
The optical glass according to any one of (1) to (5).

(7) the molar ratio of _{Ta 2 O 5 / Nb 2 O} 5 with respect to the glass the total amount of substance of oxide basis composition is 0.060 or more (6), wherein the optical glass.

  (8) The optical glass according to any one of (1) to (7), wherein the content of the BaO component is 15.0% or less in terms of mol% with respect to the total amount of glass having an oxide equivalent composition.

(9) The sum of the content of at least one selected from the group consisting of Ta ₂ O ₅ component, Nb ₂ O ₅ component, Na ₂ O component and BaO component is _{5 with} respect to the total amount of glass in oxide equivalent composition Optical glass in any one of (1) to (8) which is 0.0% or more and 50.0% or less.

(10) the glass the total amount of substance of the oxide composition in terms of, from 0 to 10.0% _P 2 _{O 5} component in mol% and / or _B 2 _{O 3} component from 0 to 10.0% and / or GeO ₂ component 0 to 10.0%
The optical glass according to any one of (1) to (9).

(11) The optical glass according to (10), wherein a sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ ) with respect to the total amount of glass having an oxide conversion composition is 20.0% or more and 60.0% or less.

(12) 0 to 10.0% of MgO component and / or 0 to 10.0% of CaO component and / or 0 to 10.0% of SrO component in mol% with respect to the total amount of glass in the oxide conversion composition / Or ZnO component 0 to 15.0%
The optical glass according to any one of (1) to (11).

  (13) The sum of the contents of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) with respect to the total amount of glass in an oxide equivalent composition is 40.0. % Or less of the optical glass according to (12).

(14) the glass the total amount of substance of the oxide composition in terms of, from 0 to 10.0% _Y 2 _{O 3} component in mol% and / or _La 2 _{O 3} component from 0 to 10.0% and / or _Gd 2 O ₃ components 0 to 10.0% and / or Yb ₂ O ₃ components 0 to 10.0%
The optical glass according to any one of (1) to (13).

(15) The sum of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb, and Lu) with respect to the total amount of glass in the oxide equivalent composition is The optical glass according to (14), which is 30.0% or less.

(16) Bi ₂ O ₃ component 0 to 10.0% and / or TeO ₂ component 0 to 10.0% and / or WO ₃ component 0 to mol% with respect to the total amount of glass in the oxide conversion composition 15.0% and / or Al ₂ O ₃ component 0 to 10.0% and / or Ga ₂ O ₃ component 0 to 10.0% and / or In ₂ O ₃ component 0 to 10.0% and / or ZrO ₂ components 0 to 20.0% and / or Sb ₂ O ₃ components 0 to 5.0% and / or CeO ₂ components 0 to 5.0%
The optical glass according to any one of (1) to (15).

  (17) The optical glass according to any one of (1) to (16), having a refractive index (nd) of 1.75 to 2.00 and an Abbe number (νd) of 20 to 40.

(18) (−0.00160 × ν _d +0.63460) ≦ (θg, F) ≦ () in the range where the partial dispersion ratio (θg, F) is Abbe number (ν _d ) and v _d ≦ 25. −0.00563 × ν _d +0.75573), and in the range of ν _d > 25, (−0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.00340 × ν _d +0.70000) The optical glass as described in any one of (1) to (17).

  (19) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (18).

  (20) An optical element obtained by grinding and / or polishing the optical glass according to any one of (1) to (18).

  (21) An optical element obtained by precision press-molding the optical glass according to any one of (1) to (18).

  According to the present invention, while the refractive index and the Abbe number are within the desired ranges, the partial dispersion ratio (θg, F) is small, and the transmittance is high with respect to a wider wavelength range of visible light and the color is less colored. Glass, a preform using the glass, and an optical element 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. 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.

The optical glass of the present invention contains 10.0 to 60.0% of a SiO ₂ component and more than 0% of a Ta ₂ O ₅ component in mol% with respect to the total amount of glass in an oxide conversion composition, The wavelength (λ ₇₀ ) at which the spectral transmittance is 70% is 500 nm or less. The SiO ₂ component and the Ta ₂ O ₅ component are used in combination, and by adjusting their contents, the glass has a low partial dispersion ratio (θg, F) while achieving high refractive index and high dispersion of the glass. Thus, the wavelength (λ ₇₀ ) having a desired relationship with the Abbe number (ν _d ) and having a spectral transmittance of 70% is shortened. Therefore, an optical glass having a high refractive index and a high dispersion optical property, a small partial dispersion ratio (θg, F), a high transmittance with respect to a wider wavelength range of visible light, and a low coloration. A preform and an optical element using the same 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 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 oxides when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mol%.

<About essential and optional components>
The SiO ₂ component is a glass-forming oxide and is a useful component for forming a glass skeleton. In particular, when the content of the SiO ₂ component is 60.0% or less, the refractive index of the glass is hardly lowered, and an optical glass having a desired refractive index can be easily obtained. Therefore, the content of the SiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 60.0%, more preferably 55.0%, and most preferably 50.0%. On the other hand, by setting the content of the SiO ₂ component to 10.0% or more, the glass network structure increases to such an extent that a stable glass can be obtained, so that the devitrification resistance of the glass can be improved. Accordingly, the content of the SiO ₂ component is preferably 10.0%, more preferably 20.0%, still more preferably 30.0%, and most preferably 35.0% with respect to the total amount of glass in the oxide conversion composition. Is the lower limit. SiO ₂ component as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 and the like can contain in the glass by using.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass and decreases the liquidus temperature of the glass. Further, the Ta ₂ O ₅ component is a component that imparts a desired low partial dispersion ratio (θg, F) to the glass and makes the glass less likely to be colored. In particular, by containing more than 0% of the Ta ₂ O ₅ component, an optical glass having a high refractive index, high devitrification resistance, and low partial dispersion ratio (θg, F) can be obtained. Therefore, the content of the Ta ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably more than 0%, more preferably 1.4%, even more preferably 2.2%, and most preferably 2. .5% is the lower limit. On the other hand, by setting the content of the Ta ₂ O ₅ component to 25.0% or less, devitrification due to excessive inclusion of the Ta ₂ O ₅ component can be reduced. Therefore, the content of the Ta ₂ O ₅ 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 15.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The Li ₂ O component is a component that lowers the partial dispersion ratio (θg, F) of the glass, lowers the liquidus temperature of the glass, and lowers the glass transition point. In particular, by the content of Li ₂ O component below 30.0%, it can be reduced devitrification of the glass due to excessive content of Li ₂ O component. Moreover, since the devitrification resistance at the time of reheating is improved, the press moldability of glass can be improved. 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 30.0%, more preferably 25.0%, and most preferably 23.0%. In addition, although it does not need to contain a Li ₂ O component, in order to easily adjust the partial dispersion ratio (θg, F) of the glass to a desired low value while ensuring a low glass transition point, it is converted to an oxide. The content of the Li ₂ O component with respect to the total amount of glass in the composition is preferably 0.1%, more preferably 1.0%, even more preferably 5.0%, and most preferably 8.0%. Good. 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 partial dispersion ratio (θg, F) of the glass, increases the chemical durability of the glass, particularly the water resistance, and lowers the glass transition point. In particular, by setting the content of the Na ₂ O component to 30.0% or less, glass devitrification due to excessive content of the Na ₂ O component can be reduced. Moreover, since the devitrification resistance at the time of reheating is also improved, the press moldability of glass can be improved. 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 30.0%, more preferably 25.0%, and most preferably 20.0%. In the present invention, the Na ₂ O component may not be contained, but from the viewpoint of obtaining a glass having a low partial dispersion ratio (θg, F) and high chemical durability, it contains the Na ₂ O component. Also good. In this case, the content of the Na ₂ O component with respect to the total glass material amount of the oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 5.0%. 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.

The K ₂ O component is a component that lowers the glass transition point. In particular, by setting the content of the K ₂ O component to 15.0% or less, devitrification of the glass due to excessive inclusion of the K ₂ O component can be reduced. Moreover, since the devitrification resistance at the time of reheating is improved, the press moldability of glass can be improved. 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 10.0%, and even more preferably 5.0%. In particular, from the viewpoint of further improving the devitrification resistance and press formability of the glass, the upper limit of the content of the K ₂ O component may be 1.4%. 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.

The Cs ₂ O component is a component that lowers the glass transition point. In particular, by setting the content of the Cs ₂ O component to 10.0% or less, devitrification of the glass due to excessive inclusion of the Cs ₂ O component can be reduced. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total amount of the glass having an oxide conversion composition is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%. Cs ₂ O component, the raw material as, for example, using _Cs 2 _{CO 3,} CsNO 3, etc. can be contained in the glass.

In the optical glass of the present invention, the sum of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K and Cs) is 5.0% or more and 50.0. % Or less is preferable. In particular, by setting this sum to 5.0% or more, devitrification resistance at the time of reheating is enhanced, so that it is possible to obtain a glass that is easy to press-mold. Accordingly, the total content of the Rn ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 5.0%, more preferably 10.0%, and most preferably 20.0%. On the other hand, by making this sum 50.0% or less, the devitrification resistance of the glass can be increased, and the fogging at high humidity can be reduced by increasing the chemical durability. Accordingly, the total content of the Rn ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 50.0%, more preferably 40.0%, and most preferably 35.0%. In particular, from the viewpoint of suppressing a decrease in refractive index, the total content of Rn ₂ O components is preferably 20.0% with respect to the total glass mass of the oxide equivalent composition, and preferably 15.0%. Is more preferable, and 13.0% is most preferable.

Further, the optical glass of the present invention, to the sum of Li ₂ O content component and Na ₂ O component, it is preferable the ratio of content of _Ta 2 _{O 5} component is 0.010 or more. Thereby, since the devitrification resistance at the time of preparation and reheating of the glass is enhanced, it is possible to obtain a glass that is easy to press-mold. Therefore, the molar ratio Ta ₂ O ₅ / (Li ₂ O + Na ₂ O) in the oxide conversion composition is preferably 0.010, more preferably 0.060, and most preferably 0.100. On the other hand, the upper limit of this molar ratio is generally 2.50 or less, more specifically 1.50 or less, and more specifically 1.00 or less in many cases.

The Nb ₂ O ₅ component is a component that lowers the partial dispersion ratio (θg, F) of the glass while increasing the refractive index and dispersion of the glass. In particular, by setting the content of the Nb ₂ O ₅ component to 30.0% or less, the liquidus temperature of the glass is lowered, so that an optical glass with high devitrification resistance can be obtained. Further, by setting the content of _Nb 2 _{O 5} component below 30.0%, since the coloring by _Nb 2 _{O 5} component is reduced, resulting a glass highly transparent to visible light. Therefore, the content of the Nb ₂ O ₅ component is preferably 30.0%, more preferably 25.0%, and most preferably 20.0% with respect to the total amount of glass in the oxide equivalent composition. The Nb ₂ O ₅ component may not be contained, but from the viewpoint of obtaining an optical glass having a high refractive index and high dispersion, the Nb ₂ O ₅ component may be contained. Therefore, the content of the Nb ₂ O ₅ component is preferably 0.1%, more preferably 1.0%, still more preferably 5.0%, most preferably 8. 0% is the lower limit. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The TiO ₂ component is a component that increases the refractive index of the glass and decreases the Abbe number. In particular, when the content of the TiO ₂ component is 20.0% or less, the coloration of the glass is reduced, so that the transmittance of visible light can be hardly deteriorated. Further, this can suppress an increase in the partial dispersion ratio (θg, F). Therefore, the content of the TiO 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%. In the present invention, a TiO ₂ component may not be contained, but a TiO ₂ component may be contained in order to obtain a glass having high refractive index and high dispersion and high devitrification resistance. Accordingly, the content of the TiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 0.7%. The TiO ₂ component can be contained in the glass using, for example, TiO ₂ as a raw material.

In the optical glass of the present invention, the ratio of the content of the Ta ₂ O ₅ component to the content of the Nb ₂ O ₅ component is preferably 0.060 or more. Thereby, the absorption edge of glass shifts to the short wavelength side, whereby a glass having a high transmittance for visible light and a little coloring can be obtained. Therefore, the molar ratio Ta ₂ O ₅ / Nb ₂ O ₅ in the oxide equivalent composition is preferably 0.060, more preferably 0.100, and most preferably 0.175. On the other hand, the upper limit of this molar ratio is generally 3.000 or less, more specifically 2.000 or less, and more specifically 1.500 or less.

The BaO component is a component that lowers the partial dispersion ratio (θg, F) of the glass and increases the devitrification resistance of the glass. In particular, the devitrification resistance of the glass can be increased by setting the content of the BaO component to 15.0% or less. 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 15.0%, more preferably 10.0%, and most preferably 5.0%. 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.

In the optical glass of the present invention, the sum of at least one content selected from the group consisting of Ta ₂ O ₅ component, Nb ₂ O ₅ component, Na ₂ O component and BaO component is 5.0% or more and 50.0. % Or less is preferable. Thereby, since the component which makes the partial dispersion ratio ((theta) g, F) of glass low is contained, it can be easy to obtain a desired low partial dispersion ratio. Therefore, the lower limit of the sum of the contents is preferably 5.0%, more preferably 15.0%, and most preferably 24.2% with respect to the total amount of glass in the oxide conversion composition. On the other hand, by making this sum 50.0% or less, the devitrification resistance of the glass can be improved. Moreover, since this can increase the content of the glass-forming component, it is possible to increase the viscosity of the optical glass and reduce striae. Therefore, the upper limit of the total content is preferably 50.0%, more preferably 45.0%, and most preferably 43.0% with respect to the total amount of glass having an oxide equivalent composition.

P ₂ O ₅ component is a component to increase the stability of the glass. In _particular, by setting the content of P 2 _{O 5} component to 10.0% or _less, it can be reduced devitrification due to excessive content of P 2 _{O 5} component. Therefore, the upper limit of the content of the P ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. 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 B ₂ O ₃ component is a useful component for forming a glass skeleton. In particular, by making the content of the B ₂ O ₃ component 10.0% or less, it is possible to suppress a decrease in the refractive index of the glass and to suppress a deterioration in the visible light transmittance. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, most preferably 3. The upper limit is 5%. 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 refractive index of glass and reduces devitrification during molding. In particular, by making the content of the GeO ₂ component 10.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the glass material cost can be reduced. 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 6.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

In the optical glass of the present invention, the sum of the contents of the SiO ₂ component, the P ₂ O ₅ component, the B ₂ O ₃ component and the GeO ₂ component is preferably 20.0% or more and 60.0% or less. When the sum of these contents is 20.0% or more, an increase in the partial dispersion ratio (θg, F) can be suppressed, so that a glass having a low partial dispersion ratio (θg, F) can be easily obtained. Moreover, since stability of glass is improved, the devitrification resistance of glass can be improved. Therefore, the sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ ) with respect to the total amount of glass of the oxide conversion composition is preferably 20.0%, more preferably 30.0%, and most preferably 35.0. % Is the lower limit. On the other hand, when the sum of these contents is 60.0% or less, the refractive index and the Abbe number can be hardly lowered, and the devitrification resistance of the glass can be improved. Accordingly, the sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ ) with respect to the total amount of glass in the oxide conversion composition is preferably 60.0%, more preferably 56.7%, and even more preferably 55.0. %, Most preferably 50.0%.

In the optical glass of the present invention, the sum of the contents of the SiO ₂ component, the B ₂ O ₃ component and the Rn ₂ O component is preferably 30.0% or more and 90.0% or less. When the sum of these contents is 30.0% or more, the deterioration of the visible light transmittance of the glass can be suppressed by reducing the coloring of the glass. Therefore, the sum (SiO ₂ + B ₂ O ₃ + Rn ₂ O) of the oxide equivalent composition with respect to the total amount of glass is preferably 30.0%, more preferably 40.0%, and most preferably 50.0%. And On the other hand, when the sum of these contents is 90.0% or less, the refractive index and the Abbe number can be hardly lowered, and the devitrification resistance of the glass can be improved. Therefore, the sum (SiO ₂ + B ₂ O ₃ + Rn ₂ O) with respect to the total amount of glass of the oxide conversion composition is preferably 90.0%, more preferably 85.0%, and most preferably 80.0%. And

The MgO component is a component that lowers the melting temperature of the glass. In particular, by making the content of the MgO component 10.0% or less, it is possible to increase the chemical durability of the glass and increase the devitrification resistance of the glass while obtaining a desired high refractive index. Therefore, the content of the MgO component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The MgO component can be contained in the glass using, for example, MgO, MgCO ₃ , MgF ₂ or the like as a raw material.

The CaO component is a component that lowers the liquidus temperature of the glass. In particular, by making the content of the CaO component 10.0% or less, it is possible to suppress a decrease in the refractive index of the glass, increase the chemical durability of the glass, and increase the devitrification resistance of the glass. Therefore, the CaO component content is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, and most preferably 2.7% with respect to the total amount of glass in the oxide equivalent composition. The upper limit. 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 lowers the liquidus temperature of the glass and adjusts the refractive index of the glass. In particular, by setting the content of the SrO component to 10.0% or less, it is possible to improve the devitrification resistance of the glass while obtaining a desired high refractive index. 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 10.0%, more preferably 8.0%, and most preferably 5.0%. 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 ZnO component is a component that lowers the liquidus temperature of the glass and lowers the glass transition point. In particular, by setting the content of the ZnO component to 15.0% or less, the chemical durability of the glass can be enhanced while obtaining a desired high refractive index. Therefore, the content of the ZnO component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 8.0%. 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 RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) increases the devitrification resistance of the glass as described above. However, if the total content of these RO components is too large, the devitrification resistance of the glass tends to deteriorate, and the refractive index of the glass tends to decrease. Therefore, the total content of the RO component with respect to the total glass material amount of the oxide conversion composition is preferably 40.0%, more preferably 25.0%, and most preferably 10.0%.

Y ₂ O ₃ component, _La 2 _{O 3} component, _Gd 2 _{O 3} component and _Yb 2 _{O 3} component, while increasing the refractive index of glass and is a component for improving the glass in devitrification resistance. In particular, the devitrification resistance of the glass is increased by making each content of the Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component 10.0% or less, Moreover, it is possible to make it difficult to lower the dispersion of the glass. Therefore, the content of each of the Y ₂ O ₃ component, the La ₂ O ₃ component, the Gd ₂ O ₃ component, and the Yb ₂ O ₃ component with respect to the total glass material amount of the oxide conversion composition is preferably 10.0%, more The upper limit is preferably 5.0%, and most preferably 3.0%. Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component are, for example, Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ as raw materials. O (X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used.

In the optical glass of the present invention, the total content of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y and Yb) is 30.0% or less. It is preferable. Thereby, the devitrification resistance of glass can be improved, suppressing the fall of dispersion | distribution of glass. Therefore, the sum of the contents of the Ln 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 Bi ₂ O ₃ component and the TeO ₂ component are components that increase the refractive index of the glass and lower the glass transition point. Here, by suppressing the coloring of the glass by reducing the content of each of the Bi ₂ O ₃ component and the TeO ₂ component to 10.0% or less, it is possible to suppress the deterioration of the visible light transmittance of the glass. it can. In particular, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio (θg, F) of the glass. Therefore, the content of each of the Bi ₂ O ₃ component and the TeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. Is the upper limit. Bi ₂ O ₃ component and TeO ₂ component can be contained in the glass using, for example, Bi ₂ O ₃ , TeO ₂ or the like as raw materials.

The WO ₃ component is a component that increases the refractive index of the glass and decreases the liquidus temperature of the glass. In particular, by setting the content of the WO ₃ component to 15.0% or less, the coloring of the glass can be reduced, and the visible light transmittance of the glass can be increased. This also makes it difficult to increase the partial dispersion ratio (θg, F) of the glass. Accordingly, 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 15.0%, more preferably 10.0%, and most preferably 5.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The Al ₂ O ₃ component, the Ga ₂ O ₃ component, and the In ₂ O ₃ component are components that improve the chemical durability of the glass. In particular, the devitrification resistance of the glass can be enhanced by adjusting the content of these components to 10.0% or less. Therefore, the content of the Al ₂ O ₃ component, the Ga ₂ O ₃ component, and the In ₂ O ₃ component with respect to the total glass material amount of the oxide conversion composition is preferably 10.0%, more preferably 5.0%, respectively. Most preferably, the upper limit is 3.0%. Al ₂ O ₃ component, Ga ₂ O ₃ component and In ₂ O ₃ component are, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ , In ₂ O as raw materials. ₃ , In (OH) ₃ or the like can be used for inclusion in the glass.

The ZrO ₂ component is a component that lowers the partial dispersion ratio (θg, F) of the glass while increasing the refractive index of the glass. In particular, by setting the content of the ZrO ₂ component to 20.0% or less, the liquidus temperature of the glass can be lowered to increase the devitrification resistance. Therefore, the content of the ZrO ₂ component is preferably 20.0%, more preferably 15.0%, and most preferably 10.0% with respect to the total amount of glass in the oxide conversion composition. The ZrO ₂ component may not be contained, but in order to easily obtain a glass having a high refractive index and a low partial dispersion ratio, the content of the ZrO ₂ component with respect to the total glass material amount of the oxide conversion composition is: The lower limit is preferably 0.1%, more preferably 0.2%, and most preferably 0.3%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

The Sb ₂ O ₃ component is a component that accelerates defoaming of the glass and clarifies the glass. Sb ₂ O ₃ component can make it difficult to produce excessive foaming at the time of glass melting by setting the content with respect to the total amount of glass to 5.0% or less, and Sb ₂ O ₃ component and melting equipment (particularly Alloying with noble metals such as Pt can be suppressed. Therefore, the content of the Sb ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 5.0%, more preferably 3.0%, and even more preferably 1.0%. However, when importance is attached to the environmental impact of the optical glass, it is preferable not to contain the Sb ₂ O ₃ component. 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 that clarifies the glass and adjusts the optical constant of the glass. In particular, coloring by the CeO ₂ component can be reduced by setting the content of the CeO ₂ component to 5.0% or less. Accordingly, the CeO ₂ component content with respect to the total glass material amount of the oxide conversion composition is preferably 5.0%, more preferably 3.0%, and even more preferably 1.0%. However, when a CeO ₂ component is contained, absorption easily occurs at a specific wavelength in the visible range. Therefore, when obtaining a glass having a particularly high visible light transmittance, it is preferable that the CeO ₂ component is not substantially contained. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

The components for clarifying and defoaming the glass are not limited to the above Sb ₂ O ₃ component and CeO ₂ component, and well-known fining agents and defoaming agents in the field of glass production, or combinations 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.

  If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass are not impaired.

  However, the transition metal components such as V, Cr, Mn, Co, Ni, Cu, Ag, and Mo, excluding Ta, Nb, Ti, Zr, and W, are contained in a small amount even if they are contained individually or in combination. In particular, optical glass using a wavelength in the visible region is preferably substantially free from being colored because it has a property of being colored and absorbing at a specific wavelength in the visible region.

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 that is preferably used as the optical glass of the present invention cannot be expressed directly in the description of mass% because the composition is expressed in mol% with respect to the total amount of glass of oxide conversion composition. The composition expressed by mass% of each component present in the glass composition satisfying various required properties generally takes the following values in terms of oxide composition.
SiO ₂ component 5.0-40.0 mass% and Ta ₂ O ₅ component more than 0% -60.0 mass%
And Li ₂ O component 0 to 20.0 mass% and / or Na ₂ O component 0 to 20.0 mass% and / or K ₂ O component 0 to 15.0 mass% and / or Cs ₂ O component 0 to 20 0.0% by mass and / or Nb ₂ O ₅ component 0-55.0% by mass and / or TiO ₂ component 0-18.0% by mass and / or BaO component 0-25.0% by mass and / or P ₂ O ₅ components from 0 to 15.0% by weight and / or _B 2 _{O 3} component 0 to 10.0% by weight and / or GeO ₂ component 0 to 10.0% by weight and / or MgO component 0 to 10.0% by weight and // CaO component 0 to 10.0% by mass and / or SrO component 0 to 10.0% by mass and / or ZnO component 0 to 15.0% by mass and / or Y ₂ O ₃ component 0 to 10.0% by mass and / or _La 2 _{O 3} component from 0 to 15.0% by weight and / or d ₂ O ₃ component from 0 to 15.0% by weight and / or _Yb 2 _{O 3} component from 0 to 15.0% by weight and / or _Bi 2 _{O 3} component from 0 to 40.0% by weight and / or TeO ₂ component 0 15.0% by mass and / or WO ₃ component 0-35.0% by mass and / or Al ₂ O ₃ component 0-10.0% by mass and / or Ga ₂ O ₃ component 0-15.0% by mass and / or or _In 2 _{O 3} component from 0 to 15.0% by weight and / or ZrO ₂ component from 0 to 25.0% by weight and / or _Sb 2 _{O 3} component from 0 to 15.0% by weight and / or CeO ₂ component 0-15 .0 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 platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1100 to 1400 ° C. for 3 to 5 hours, stir to homogenize, blow out bubbles, etc., then lower the temperature to 1000 to 1300 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.78, and most preferably 1.80. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is generally 2.00 or less, more specifically 1.98 or less, and more specifically 1.95 or less in many cases. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 35, still more preferably 30, and most preferably 29.2. On the other hand, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but is generally about 20 or more, more specifically about 21 or more, and more specifically about 22 or more. 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.

Moreover, the optical glass of the present invention has a low partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−0.00160 × ν _d +0...) In the range of ν _d ≦ 25 with respect to the Abbe number (ν _d ). 63460) ≦ (θg, F) ≦ (−0.00563 × ν _d +0.75573) and in the range of ν _d > 25, (−0.00250 × ν _d +0.65710) ≦ (θg , F) ≦ (−0.00340 × ν _d +0.70000). As a result, an optical glass having a low partial dispersion ratio (θg, F) while having high dispersion can be obtained, so that chromatic aberration of an optical element formed from the optical glass can be reduced. Here, the lower limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−0.00160 × ν _d +0.63460), more preferably (−0.00160 × ν _d +0). .63660), most preferably (−0.00160 × ν _d +0.63860). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−0.00563 × ν _d +0.75573), more preferably (−0.00563 × ν _d +0). .75473), and most preferably (−0.00563 × ν _d +0.75373). Further, the lower limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−0.00250 × ν _d +0.65710), and more preferably (−0.00250 × ν _d +0. 65910), most preferably (−0.00250 × ν _d +0.66110). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−0.00340 × ν _d +0.70000), more preferably (−0.00340 × ν _d +0). 69900), and most preferably (−0.00340 × ν _d +0.69800). 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.

Further, the optical glass of the present invention is less colored and has a high visible light permeability. 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 460 nm or less, and most preferably. Is 420 nm or less. In addition, the optical glass of the present invention has a wavelength (λ ₈₀ ) indicating a spectral transmittance of 80% in a sample having a thickness of 10 mm in terms of the transmittance of the glass is 600 nm or less, more preferably 560 nm or less, and most preferably. Is 520 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 440 nm or less, more preferably 400 nm or less, and most preferably 380 nm or less. As a result, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and coloring is reduced by increasing the transmittance of the glass with respect to light having a wider wavelength in the visible region, thereby transmitting visible light. This optical glass can be preferably used as a material for an optical element that corrects the secondary spectrum.

  The optical glass of the present invention preferably has high water resistance. In particular, the chemical durability (water resistance) of the glass powder method according to JOGIS06-1999 is preferably class 1 to 3, more preferably class 1 to 2, and most preferably class 1. Accordingly, when the optical glass is polished, the fogging of the glass due to the aqueous polishing liquid or the cleaning liquid is reduced, so that the optical element can be easily manufactured from the glass. Here, “water resistance” means durability against erosion of glass by water, and this water resistance is measured according to the Japan Optical Glass Industry Association Standard “Measurement Method of Chemical Durability of Optical Glass” JOGIS06-1999. Can do. Further, “the chemical durability (water resistance) by the powder method is class 1 to 3” means that the chemical durability (water resistance) performed according to JOGIS06-1999 is the mass of the sample before and after the measurement. The weight loss rate means less than 0.25% by mass. In addition, “Class 1” of chemical durability (water resistance) indicates that the weight loss rate of the sample before and after measurement is less than 0.05 mass%, and “Class 2” indicates weight loss of the sample before and after measurement. The rate is 0.05 mass% or more and less than 0.10 mass%, “Class 3”, the weight loss rate of the sample before and after the measurement is 0.10 mass% or more and less than 0.25 mass%, “4” indicates that the weight loss rate of the sample before and after the measurement is 0.25 mass% or more and less than 0.60 mass%, and “Class 5” indicates that the weight loss rate of the sample before and after the measurement is 0.60 mass%. The above is less than 1.10% by mass, and in “Class 6”, the weight loss rate of the sample before and after the measurement is 1.10% by mass or more.

  The optical glass of the present invention preferably has high acid resistance. In particular, the chemical durability (acid resistance) of the glass powder method according to JOGIS06-1999 is preferably class 1 to 3, more preferably class 1 to 2, and most preferably class 1. Thereby, when the optical glass is polished, the fogging of the glass due to the acidic polishing liquid or the cleaning liquid is reduced, so that the optical element can be more easily produced from the glass. Here, “acid resistance” means durability against erosion of glass by acid, and this acid resistance is measured according to the Japan Optical Glass Industry Association Standard “Measurement Method of Chemical Durability of Optical Glass” JOGIS06-1999. Can do. “The chemical durability (acid resistance) by the powder method is class 1 to 3” means that the chemical durability (acid resistance) performed according to JOGIS06-1999 is the mass of the sample before and after the measurement. It means a weight loss rate of less than 0.65% by mass. In addition, “Class 1” of chemical durability (acid resistance) indicates that the weight loss rate of the sample before and after measurement is less than 0.20% by mass, and “Class 2” indicates weight loss of the sample before and after measurement. The rate is 0.20% by mass or more and less than 0.35% by mass, and “Class 3” indicates that the weight loss rate of the sample before and after the measurement is 0.35% by mass or more and less than 0.65% by mass. “4” indicates that the weight loss rate of the sample before and after the measurement is 0.65% by mass or more and less than 1.20% by mass, and “Class 5” indicates that the sample weight loss rate before and after the measurement is 1.20% by mass. The amount is less than 2.20% by mass, and “Class 6” has a mass reduction rate of the sample before and after the measurement of 2.20% by mass or more.

  The optical glass of the present invention 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 when used for a long period of time, so that the secondary spectrum can be corrected with higher accuracy over a longer period of time. In particular, since the solarization becomes larger as the use temperature becomes higher, the optical glass of the present invention is particularly effective when used at a high temperature such as in-vehicle use. Accordingly, the upper limit of solarization of the optical glass of the present invention is preferably 5.0%, more preferably 4.5%, and most preferably 4.0%. In the present specification, “solarization” refers to the amount of degradation of spectral transmittance at 450 nm when glass is irradiated with ultraviolet rays, and specifically, Japanese Optical Glass Industry Association Standard JOGIS04-1994 “Optical”. According to “Measurement Method of Solarization of Glass”, the spectral transmittance before and after being irradiated with light from a high-pressure mercury lamp is measured.

  The optical glass of the present invention preferably has good press formability. That is, the optical glass of the present invention is preferably free from devitrification and milky white before and after the reheating test (ii). This makes it difficult for devitrification and coloring to occur even in a reheating test assuming reheat press processing, so that the light transmittance of the glass is less likely to be lost. Processing can be facilitated. That is, since an optical element having a complicated shape can be produced by press molding, it is possible to realize optical element production with low production cost and high productivity.

  Here, in the reheating test (A), a test piece of 15 mm × 15 mm × 30 mm is placed on an indented refractory and placed in an electric furnace and reheated, and the transition temperature (Tg) of each sample is 150 minutes from room temperature. After raising the temperature to a temperature 80 ° C to 150 ° C higher (temperature falling into the refractory), keeping the temperature at that temperature for 30 minutes, cooling to room temperature, taking it out of the furnace, and facing the two surfaces so that they can be observed inside After polishing to a thickness of 10 mm, the polished glass sample can be visually observed.

  It should be noted that the presence or absence of devitrification and milky white before and after the reheating test (A) can be confirmed, for example, visually, and that “devitrification and milky white do not occur” means that, for example, after the reheating test (A) The value obtained by dividing the transmittance of light (d-line) having a wavelength of 587.56 nm of the test piece by the d-line transmittance of the test piece before the reheating test is approximately 0.80 or more.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

Composition of Examples (No. 1 to No. 112) and Comparative Example (No. A) of the present invention, as well as refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), Tables 1 to 15 show the results of water resistance, acid resistance, solarization, reheating test, and wavelengths (λ ₅ , λ ₇₀ , λ ₈₀ ) at which the spectral transmittance is 5%, 70%, and 80%. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of Examples (No. 1 to No. 112) and Comparative Example (No. A) of the present invention are all oxides, hydroxides, carbonates, nitrates, fluorides corresponding to the raw materials of the respective components. The raw materials of high purity used for ordinary optical glass such as hydroxide, metaphosphate compound, etc. are selected and weighed so as to have the composition ratios of the examples and comparative examples shown in Tables 1 to 15. After mixing uniformly, the mixture was put into a platinum crucible and melted in a temperature range of 1100 to 1400 ° C. for 3 to 5 hours in an electric furnace according to the melting difficulty of the glass composition, and the mixture was stirred and homogenized to remove bubbles. Thereafter, the temperature was lowered to 1000 to 1300 ° C., and the mixture was homogenized with stirring, cast into a mold, and gradually cooled to produce glass.

Here, the refractive index (n _d ), Abbe number (ν _d ) and partial dispersion ratio (θg, F) of the glass of Examples (No. 1 to No. 112) and Comparative Example (No. A) are as follows. It measured based on 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 0.00160, 0.00250. , 0.00340 and 0.00563, the intercept b was determined. In addition, the glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

Moreover, the transmittance | permeability of the glass of an Example (No.1-No.112) and a comparative example (No.A) was 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. More 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 ₅ (wavelength when the transmittance was 5%), λ ₇₀ (transmittance). The wavelength at 70%) and λ ₈₀ (wavelength at 80% transmittance) were determined.

  Moreover, the acid resistance of the glass of an Example (No.1-No.112) and a comparative example (No.A) is Japan Optical Glass Industry Association standard "measurement method of the chemical durability of optical glass" JOGIS06-1999. Measured accordingly. That is, a glass sample crushed to a particle size of 425 to 600 μm was taken in a specific gravity bottle and placed in a platinum basket. The platinum basket was placed in a quartz glass round bottom flask containing a 0.01N nitric acid aqueous solution and treated in a boiling water bath for 60 minutes. Calculate the weight loss rate (mass%) of the glass sample after treatment, class 1 when this weight loss ratio (mass%) is less than 0.20, class when the weight loss rate is less than 0.20 to 0.35 2. When the weight loss rate is less than 0.35 to 0.65, class 3, when the weight loss rate is less than 0.65 to 1.20, class 4, and when the weight loss rate is less than 1.20 to 2.20. Class 5 and the weight loss rate of 2.20 or higher were classified as Class 6. At this time, it means that the acid resistance of glass is excellent, so that the number of classes is small.

  Moreover, the water resistance of the glass of an Example (No.1-No.112) and a comparative example (No.A) is Japan Optical Glass Industry Association standard "the measuring method of the chemical durability of optical glass" JOGIS06-1999. Measured accordingly. That is, a glass sample crushed to a particle size of 425 to 600 μm was taken in a specific gravity bottle and placed in a platinum basket. The platinum basket was placed in a quartz glass round bottom flask containing pure water (pH 6.5-7.5) and treated in a boiling water bath for 60 minutes. The weight loss rate (mass%) of the glass sample after the treatment is calculated, class 1 when this weight loss rate is less than 0.05, class 2 when the weight loss rate is less than 0.05 to 0.10, and weight loss rate. Is less than 0.10 to 0.25 class 3, when the weight loss rate is less than 0.25 to 0.60, class 4 and when the weight loss rate is less than 0.60 to 1.10, class 5. The case where the rate was 1.10 or higher was classified as class 6. At this time, the smaller the number of classes, the better the water resistance of the glass.

  Moreover, solarization of the glass of an Example (No.1-No.112) and a comparative example (No.A) is light according to Japan Optical Glass Industry Association Standard JOGIS04-1994 "Measurement method of optical glass solarization". The change (%) in light transmittance at a wavelength of 450 nm before and after irradiation was measured. Here, the light irradiation was performed by heating an optical glass sample to 100 ° C. and irradiating light with a wavelength of 450 nm for 4 hours using an ultrahigh pressure mercury lamp.

  Moreover, about the glass of an Example (No.1-No.112) and a comparative example (No.A), the presence or absence of devitrification and milky white before and after a reheating test was confirmed visually. Here, confirmation of devitrification and milky white before and after the reheating test is carried out by placing a test piece of 15 mm × 15 mm × 30 mm on a concave refractory and placing it in an electric furnace to reheat it to the reheating temperature. After being kept warm for 30 minutes, cooled to room temperature and taken out of the furnace, the opposing two surfaces were polished to a thickness of 10 mm so that they could be observed inside, and then visually checked for devitrification and milky white in the polished glass sample It was done by observing. At this time, devitrification and milky white do not occur when the reheating temperature is (Tg + 80 ° C. to 150 ° C.), and also when the reheating temperature is higher than (Tg + 80 ° C. to 150 ° C.) For the glass in which no milk white was produced, the “result of reheating test” was set to “◯”. Moreover, although devitrification and milky white did not occur when the reheating temperature was set within a range of (Tg + 80 ° C. to 150 ° C.), the reheating temperature was more within the range of (Tg + 80 ° C. to 150 ° C.). For the glass in which devitrification or milky white was produced when the temperature was raised, the “result of reheating test” was set to “Δ”.

As shown in Tables 1 to 15, the optical glasses according to the examples of the present invention have a partial dispersion ratio (θg, F) of (v0.003 × ν _d +0.75573) when ν _d ≦ 25. In more detail below, it was (−0.00563 × ν _d +0.75001) or less. In the case of ν _d > 25, the partial dispersion ratio (θg, F) is (−0.00340 × ν _d +0.70000) or less, more specifically (−0.00340 × ν _d +0.695540) or less. Met. On the other hand, the partial dispersion ratio (θg, F) of the optical glass obtained in the example of the present invention is (−0.00160 × ν _d +0.63460) or more when ν _d ≦ 25, and ν _d Those of> 25 were (−0.00250 × ν _d +0.65710) or more. Therefore, it was found that the optical glass of the example of the present invention has a partial dispersion ratio (θg, F) within a desired range. On the other hand, the glass of Comparative Example (No. A) of the present invention had ν _d > 25, but the partial dispersion ratio (θg, F) exceeded (−0.00340 × ν _d +0.70000). Therefore, it was clarified that the optical glass of the example of the present invention has a small partial dispersion ratio (θg, F) in relation to the Abbe number (ν _d ) as compared with the glass of the comparative example.

In addition, in the optical glass of the example of the present invention, each of λ ₇₀ (wavelength at 70% transmittance) was 500 nm or less, more specifically 420 nm or less. The optical glasses of the examples of the present invention each had a λ ₈₀ (wavelength at 80% transmittance) of 600 nm or less, more specifically 520 nm or less. In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength at a transmittance of 5%) was 440 nm or less, more specifically, 370 nm or less. For this reason, it became clear that the optical glass of the Example of this invention was hard to be colored and had high visible light permeability.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.75 or more, more specifically 1.83 or more, and this refractive index (n _d ) is 2.00 or less. More specifically, it was 1.92 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 20 or more, more specifically 23 or more, and this Abbe number (ν _d ) of 40 or less, more specifically 27. And within the desired range.

Therefore, the optical glass of the embodiment of the present invention has high visible light transmittance, low coloration, and small chromatic aberration, while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. Became clear.

  Furthermore, the optical glasses of the examples of the present invention all had a chemical durability (water resistance) by the powder method of class 1 to 3, more specifically class 1, and were within a desired range. In addition, the optical glasses of the examples of the present invention all had chemical durability (acid resistance) by class 1 to class 1-3, more specifically class 1, and were within a desired range. For this reason, it became clear that the optical glass of the Example of this invention is excellent also in water resistance and acid resistance.

  Furthermore, the optical glasses of the examples of the present invention all have a solarization of 5.0% or less, more specifically 4.5% or less, and the solarization of the optical glass by long-time irradiation with ultraviolet rays is reduced. It became clear.

  Moreover, the optical glass of the Example of this invention did not produce devitrification and milky white both before and after performing a reheating test (ii). Therefore, it was also clarified that the optical glass of the example of the present invention hardly causes devitrification or milk white due to reheating.

  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 (21)

It contains 10.0 to 60.0% of SiO ₂ component and more than 0% of Ta ₂ O ₅ component in mol% with respect to the total amount of glass in oxide conversion composition, and the spectral transmittance is 70%. Optical glass whose wavelength ((lambda) ₇₀ ) to show is 500 nm or less. _2. The optical glass according to claim 1, wherein the content of the Ta ₂ O ₅ component is 25.0% or less in terms of mol% with respect to the total amount of the glass having an oxide equivalent composition. Li ₂ O component 0 to 30.0% and / or Na ₂ O component 0 to 30.0% and / or K ₂ O component 0 to 15 in mol% with respect to the total amount of glass in the oxide conversion composition. 0% and / or Cs ₂ O component from 0 to 10.0%
The optical glass according to claim 1 or 2, further comprising: The total content of Rn ₂ O components (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 5.0% to 50% The optical glass according to claim 3, which is 0.0% or less. _5. The optical glass according to claim 3, wherein a molar ratio Ta ₂ O ₅ / (Li ₂ O + Na ₂ O) with respect to the total amount of the glass having an oxide conversion composition is 0.010 or more. Nb ₂ O ₅ component 0 to 30.0% and / or TiO ₂ component 0 to 20.0% in mol% with respect to the total amount of glass in the oxide conversion composition
The optical glass according to any one of claims 1 to 5. The optical glass according to claim 6, wherein the molar ratio Ta ₂ O ₅ / Nb ₂ O ₅ with respect to the total amount of glass in the oxide equivalent composition is 0.060 or more.   The optical glass according to any one of claims 1 to 7, wherein the content of the BaO component is 15.0% or less in terms of mol% with respect to the total amount of the glass having an oxide conversion composition. The sum of the content of one or more selected from the group consisting of Ta ₂ O ₅ component, Nb ₂ O ₅ component, Na ₂ O component and BaO component is 5.0% with respect to the total amount of glass in oxide conversion composition The optical glass according to any one of claims 1 to 8, which is 50.0% or less. The glass the total amount of substance of the oxide composition in terms of, from 0 to 10.0% _P 2 _{O 5} component in mol% and / or _B 2 _{O 3} component from 0 to 10.0% and / or GeO ₂ component 0 .0%
The optical glass according to any one of claims 1 to 9. 11. The optical glass according to claim 10, wherein a sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ ) with respect to the total amount of glass having an oxide conversion composition is 20.0% or more and 60.0% or less. MgO component 0 to 10.0% and / or CaO component 0 to 10.0% and / or SrO component 0 to 10.0% and / or ZnO in mol% with respect to the total amount of glass in oxide conversion composition Ingredient 0-15.0%
The optical glass according to any one of claims 1 to 11.   The sum of the content of RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) with respect to the total amount of glass in oxide-converted composition is 40.0% or less The optical glass according to claim 12. The glass the total amount of substance of the oxide composition in terms of the mole percent _Y 2 _{O 3} component from 0 to 10.0% and / or _La 2 _{O 3} component from 0 to 10.0% and / or _Gd 2 _{O 3} component 0 10.0% and / or _Yb 2 _{O 3} component from 0 to 10.0%
The optical glass according to any one of claims 1 to 13. The sum of the contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb and Lu) with respect to the total amount of glass in oxide-converted composition is 30.0 The optical glass according to claim 14, which is not more than%. Bi ₂ O ₃ component 0 to 10.0% and / or TeO ₂ component 0 to 10.0% and / or WO ₃ component 0 to 15.0 in mol% with respect to the total amount of glass in the oxide conversion composition % And / or Al ₂ O ₃ component 0 to 10.0% and / or Ga ₂ O ₃ component 0 to 10.0% and / or In ₂ O ₃ component 0 to 10.0% and / or ZrO ₂ component 0 20.0% and / or _Sb 2 _{O 3} component from 0 to 5.0% and / or CeO ₂ component from 0 to 5.0%
The optical glass according to any one of claims 1 to 15.   The optical glass according to claim 1, which has a refractive index (nd) of 1.75 or more and 2.00 or less and an Abbe number (νd) of 20 or more and 40 or less. Partial dispersion ratio ([theta] g, F) between the Abbe number (ν _d), in the region of _{ν d ≦ 25 (-0.00160 × ν} d +0.63460) ≦ (θg, F) ≦ (-0. 00563 × ν _d +0.75573), and (−0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.00340 × ν _d +0.70000) in the range of ν _d > 25. The optical glass according to claim 1, wherein the optical glass satisfies the relationship of   A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 18.   An optical element obtained by grinding and / or polishing the optical glass according to claim 1.   An optical element formed by precision press-molding the optical glass according to claim 1.

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