JP5296110B2 - Optical glass, preform and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical glass useful for correcting chromatic aberration of an optical element, and hardly generating clouding on a glass surface when being polished, cleaned or the like, and to provide a preform using the optical glass. <P>SOLUTION: This optical glass contains Bi<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component, SiO<SB POS="POST">2</SB>component and/or B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component, and F component in terms of an oxide conversion composition, and has chemical durability (water resistance) by the powder method of Class 1-5, wherein the partial dispersion ratio [&theta;g, F] is &ge;0.63, and the Abbe number [&nu;d] is &le;27, and an inequality: partial dispersion ratio [&theta;g, F]&gt;-0.0131&times;[&nu;d]+0.9000 is satisfied. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

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 an optical glass that contains a Bi ₂ O ₃ component as a main component and focuses attention on the partial dispersion ratio (θg, F) of the glass, for example, optical glasses shown in Patent Documents 1 and 2 are known.

JP 2009-203135 A JP 2009-234805 A

  However, although the optical glasses shown in Patent Documents 1 and 2 have a large partial dispersion ratio, the Abbe number is small, and it cannot be said that the partial dispersion ratio is sufficiently large as compared with a general glass having a similar Abbe number. The anomalous dispersibility was never great. Therefore, in order to more effectively correct the chromatic aberration, it is necessary to further increase the partial dispersion ratio of the optical glass in order to further increase the difference in partial dispersion ratio with a general glass having a similar Abbe number. .

  Further, when manufacturing an optical element used for communication, video, etc., a polishing process is often performed on the obtained optical glass. However, the optical element manufactured through the polishing process has a problem that the surface is likely to be fogged. Further, even when the glass is not subjected to a polishing step as in precision press molding, there is a problem that the surface is likely to be clouded when the surface is cleaned with water or the like. It has been difficult to produce an optical element that can control light in the visible region, especially from glass that has once fogged.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is useful for correcting chromatic aberration of an optical element, and fogging occurs on a glass surface during polishing or cleaning. It is to obtain a difficult optical glass and a preform using the same.

As a result of intensive studies and studies to solve the above problems, the present inventors have further increased the partial dispersion ratio (θg, F) of glass by using the Bi ₂ O ₃ component and the F component together. However, the present inventors have found that the chemical durability of glass, particularly acid resistance and water resistance, can be improved, and the present invention has been completed. In particular, the present inventors are thought to greatly reduce the devitrification resistance in a glass containing a Bi ₂ O ₃ component. It was found that the dispersion ratio (θg, F) can be further increased. Specifically, the present invention provides the following.

(1) It contains Bi ₂ O ₃ component, SiO ₂ component and / or B ₂ O ₃ component and F component in oxide equivalent composition, and chemical durability (water resistance) by powder method is class 1-5 The partial dispersion ratio [θg, F] is 0.63 or more, the Abbe number [νd] is 27 or less, and the partial dispersion ratio [θg, F]> − 0.0131 × [νd] +0.9000 is satisfied. Optical glass characterized.

(2) The optical glass according to (1), which contains 10 to 50% of Bi ₂ O ₃ component in mol% with respect to the total amount of the oxide-converted composition.

(3) In mol% with respect to the total amount of substances in oxide equivalent composition,
B ₂ O ₃ component 0% to 50.0% and / or SiO ₂ component 0% to 40.0%
The optical glass according to (1) or (2), which contains

(4) The optical glass according to any one of (1) to (3), wherein a molar sum (SiO ₂ + B ₂ O ₃ ) with respect to the total amount of the oxide conversion composition is 1.0% or more and 60.0% or less.

  (5) The optical glass according to any one of (1) to (4), containing an F component in an externally divided mol% with respect to the oxide-based substance amount of more than 0% and 30.0% or less.

(6) the molar sum to the total amount of substance of the oxide composition in terms of _{(Bi 2 O} 3 + F) is most 80.0% less than 10.0% (1) to (5) any description of the optical glass.

(7) In mol% with respect to the total amount of substances in oxide equivalent composition,
Li ₂ O component from 0 to 30.0% and / or Na ₂ O component from 0 to 20.0% and / or _{K 2} O ingredient from 0 to 20.0%
The optical glass according to any one of (1) to (6).

(8) The molar sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) with respect to the total amount of glass in the oxide equivalent composition is 40.0% or less. (7) The optical glass as described.

(9) The optical glass according to (7) or (8), wherein a molar sum (Na ₂ O + K ₂ O) with respect to the total amount of the glass having an oxide conversion composition is 15.0% or less.

(10) The optical glass according to (9), wherein the molar ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) in the oxide equivalent composition is 1.00 or less.

(11) 0 to 30.0% of MgO component and / or 0 to 30.0% of CaO component and / or 0 to 30.0% of SrO component and in mol% with respect to the total amount of glass in the oxide conversion composition / Or BaO component 0-45.0% and / or ZnO component 0-30.0%
The optical glass according to any one of (1) to (10).

  (12) The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) with respect to the total amount of glass in the oxide equivalent composition is 50.0% or less. (11) The optical glass as described.

  (13) The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) with respect to the total amount of glass in the oxide equivalent composition is 1.0% or more. The optical glass according to (11) or (12).

(14) The optical glass according to any one of (1) to (13), wherein the molar ratio (Rn ₂ O) / (Bi ₂ O ₃ + SiO ₂ + B ₂ O ₃ + CaO) in the oxide equivalent composition is 0.400 or less. .

(15) The optical glass according to any one of (1) to (14), wherein the molar ratio (SiO ₂ + B ₂ O ₃ ) / (Bi ₂ O ₃ + Rn ₂ O) in the oxide equivalent composition is 0.700 or more.

(16) La ₂ O ₃ component 0 to 10.0% and / or Gd ₂ O ₃ component 0 to 10.0% and / or Y ₂ O in mol% with respect to the total amount of glass in the oxide conversion composition ₃ components 0 to 10.0% and / or Yb ₂ O ₃ components 0 to 10.0% and / or Lu ₂ O ₃ components 0 to 10.0%
The optical glass according to any one of (1) to (15).

(17) The molar sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) with respect to the total amount of glass in the oxide equivalent composition is 15. The optical glass according to (16), which is 0% or less.

(18) TiO ₂ component 0 to 20.0% and / or Nb ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0% by mol% with respect to the total amount of glass in the oxide conversion composition 10.0%
The optical glass according to any one of (1) to (17).

(19) The optical glass according to (18), wherein a molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) with respect to the total amount of glass having an oxide conversion composition is 20.0% or less.

(20) the glass the total amount of substance of the oxide composition in terms of, 0~10.0% _P 2 _{O 5} component in mol% and / or GeO ₂ component from 0 to 30.0% and / or _Ta 2 _{O 5} component 0 to 15.0% and / or ZrO ₂ component 0 to 10.0% and / or TeO ₂ component 0 to 35.0% and / or Al ₂ O ₃ component 0 to 20.0% and / or Ga ₂ O ₃ components 0 to 20.0% and / or CeO ₂ components 0 to 3.0% and / or Sb ₂ O ₃ components 0 to 30.0%
The optical glass according to any one of (1) to (19).

  (21) The optical glass according to any one of (1) to (20), wherein chemical durability (acid resistance) by a powder method is class 1 to 5.

  (22) A preform for polishing and / or precision press molding comprising the optical glass of any one of (1) to (21).

  (23) An optical element obtained by polishing the preform of (22).

  (24) An optical element obtained by precision press-molding the preform of (22).

  (25) An optical element comprising the optical glass according to any one of (1) to (21).

  (26) An optical apparatus having the optical element according to any one of (23) to (26).

According to the present invention, by using the Bi ₂ O ₃ component and the F component in combination, the partial dispersion ratio (θg, F) of the glass is further increased, and the chemical durability of the glass is increased. Accordingly, it is possible to obtain an optical glass which has a very high partial dispersion ratio (θg, F) and a low Abbe number, and hardly causes fogging on the surface during polishing or cleaning, and a preform using the same. it can.

It is a figure which shows the normal line in the orthogonal coordinate whose vertical axis is a partial dispersion ratio ((theta) g, F) and whose horizontal axis is Abbe number ((nu) d).

The optical glass of the present invention contains a Bi ₂ O ₃ component, a SiO ₂ component and / or a B ₂ O ₃ component and an F component in an oxide equivalent composition, and has chemical durability (water resistance) of class 1 by a powder method. ˜5, the partial dispersion ratio [θg, F] is 0.63 or more, the Abbe number [νd] is 27 or less, and the partial dispersion ratio [θg, F]> − 0.0131 × [νd] +0.9000. Meet. Bi ₂ O ₃ Abbe number of the glass with the components ([nu] d) even while being kept low by the combined use of _Bi 2 _{O 3} component and F components, high partial dispersion ratio ([theta] g, F) is obtained. In addition, by the combined use of Bi ₂ O ₃ component and F components, it is possible to reduce the content of alkali metal components, chemical durability of the glass, in particular water resistance and acid resistance is enhanced. That is, an optical glass having high chemical durability and being preferably used for visible light can be obtained while having an extremely high partial dispersion ratio (θg, F) and a low Abbe number (νd). Accordingly, it is possible to obtain an optical glass that is useful for correcting chromatic aberration of the optical element and hardly causes fogging on the surface during polishing or cleaning, and a preform using the optical glass.

  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. Unless otherwise specified, the content of each component is expressed in mol% based on oxide. Here, the “oxide standard” is generated when it is assumed that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed and changed to oxides during melting. This is a composition in which each component contained in the glass is described with the total amount of the oxides as 100 mol%.

<About essential and optional components>
The Bi ₂ O ₃ component is a component that increases the partial dispersion ratio (θg, F) of the glass, increases the refractive index (nd) of the glass, and is effective for reducing the dispersion of the glass. Further, it is a component that is also effective for lowering Tg and improving water resistance, and is an indispensable component for the glass of the present invention. Here, by the content of Bi ₂ O ₃ component to 10.0%, it is possible to easily obtain the above-mentioned technical effect. On the other hand, by the content of Bi ₂ O ₃ component below 50.0%, the stability of the glass is increased, thereby reducing the coloration of the glass. Further, when the content of Bi ₂ O ₃ component is too large, the acid resistance of the glass tends to deteriorate. Therefore, the content of the Bi ₂ O ₃ component with respect to the total amount of the oxide conversion composition is preferably 10.0% as a lower limit, more preferably more than 15.0%, and more preferably 18.0%. The lower limit is set, and most preferably 20.0% is set as the lower limit. Further, the content of the Bi ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 50.0%, more preferably 40.0%, and most preferably 30.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The B ₂ O ₃ component is a component that improves the stability of the glass, reduces devitrification, and increases the water resistance and acid resistance of the glass. Further, it is a component that has an effect of maintaining a high partial dispersion ratio (θg, F) of glass. However, if the content of the B ₂ O ₃ component is too large, the stability of the glass tends to decrease, devitrification tends to occur, and the glass tends to have a low refractive index and low dispersion. Therefore, the content of the B ₂ O ₃ component is preferably 50.0%, more preferably 40.0%, still more preferably 30.0%, and most preferably 20.0% with respect to the total amount of the oxide equivalent composition. % Is the upper limit. 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.

SiO ₂ component is a component that reduces devitrification and improving stability of the glass is a component and improve the water resistance and acid resistance of the glass. Moreover, it is a component which has the effect of achieving low dispersion | distribution of glass, and the effect of improving the transmittance | permeability. However, if the content of the SiO ₂ component is too large, the refractive index (nd) and the partial dispersion ratio (θg, F) of the glass are likely to be lowered, and the meltability of the glass is likely to be deteriorated. Accordingly, the content of the SiO ₂ component with respect to the total amount of the oxide-converted composition is preferably 40.0%, more preferably 30.0%, and most preferably 20.0%. On the other hand, devitrification can be reduced by increasing the stability of the glass while reducing the coloring of the glass by making the SiO ₂ component more than 0%. Accordingly, the content of the SiO ₂ component with respect to the total amount of the oxide-converted composition is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and most preferably 5%. More than 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.

In the optical glass of the present invention, the SiO ₂ component and the B ₂ O ₃ component are glass-forming components that can reduce devitrification, and can improve chemical durability (water resistance and acid resistance), abrasion degree, and Knoop hardness. Since it is a component, it is preferable that at least one of both is contained by 1.0% or more. However, if the content is too large, it is difficult to obtain a desired partial dispersion ratio (θg, F), refractive index (nd), and Abbe number (νd). Therefore, the molar sum (SiO ₂ + B ₂ O ₃ ) with respect to the total substance amount of the oxide conversion composition is preferably 1.0%, more preferably 5.0%, still more preferably 10.0%, and most preferably 20%. 0.0% is the lower limit. On the other hand, the molar sum (SiO ₂ + B ₂ O ₃ ) with respect to the total amount of the oxide-converted composition is preferably 60.0%, more preferably 50.0%, still more preferably 40.0%, and most preferably 34. 0.0% is the upper limit.

The F component is a glass containing a Bi ₂ O ₃ component, and even if the alkali metal component is reduced, a desired high partial dispersion ratio (θg, F) can be obtained. Therefore, the partial dispersion ratio (θg, F), particularly Knoop It is a component that can increase the mechanical strength of glass while increasing the hardness and the degree of wear. For this reason, the content of the F component in an external ratio with respect to the oxide-based substance amount is preferably more than 0%, more preferably 1.0%, and even more preferably 5.0%. On the other hand, by increasing the content of the F component to 30.0% or less with the mol% of the oxide-based substance amount, it is possible to suppress an increase in the glass Abbe number and to visible light. An optical glass having high transparency can be easily obtained. Therefore, the upper limit of the content of the F component with respect to the oxide-based substance amount is preferably 30.0%, more preferably 20.0%, and most preferably 15.0%. The F component can be contained in the glass using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

  Note that the content of the F component in this specification is based on the assumption that all of the cation components constituting the glass are made of oxides combined with oxygen that balances the charge, and the entire glass material made of these oxides. The amount is 100%, and the amount of substance of the F component is expressed in mol% (extra mol% with respect to the oxide-based substance amount).

In the optical glass of the present invention, the sum of the contents of the Bi ₂ O ₃ component and the F component is preferably more than 10.0% and not more than 80.0%. In particular, when the sum is more than 10.0%, a glass having a low glass transition point (Tg) can be obtained while increasing the partial dispersion ratio (θg, F) of the glass. On the other hand, by making this sum 80.0% or less, it is possible to easily obtain glass having desired devitrification resistance. Therefore, the molar sum (Bi ₂ O ₃ + F) with respect to the total amount of the oxide-converted composition is preferably more than 10.0%, more preferably more than 20.0%, and most preferably 25.0%. Do more. On the other hand, the upper limit of the molar sum (Bi ₂ O ₃ + F) with respect to the total substance amount of the oxide conversion composition is preferably 80.0%, more preferably 60.0%, and most preferably 40.0%. In this content ratio, the content of the F component refers to the content of the oxide based material amount, and the content of the Bi ₂ O ₃ component is based on the total glass material amount of the oxide equivalent composition. Refers to the content.

The Li ₂ O component is a component that improves the devitrification resistance of the glass to reduce devitrification and coloring, and is an effective component for lowering the Tg of the glass, and is an optional component of the optical glass of the present invention. is there. However, when the content of the Li ₂ O component is too large, the stability of the glass tends to be lowered, the partial dispersion ratio (θg, F) is lowered, and the water resistance and acid resistance are likely to be lowered. Therefore, the content of the Li ₂ O component with respect to the total amount of the oxide-converted composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. Note that the optical glass of the present invention may not contain Li 2 _O component, Li 2 _O component is a strong action to improve the stability of the glass among alkali metals, containing Li 2 _O component Thus, the devitrification resistance of the glass can be further improved. Therefore, the content of the Li ₂ O component with respect to the total amount of the oxide-converted composition is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and most preferably More than 5.0%. 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 and the K ₂ O component are components that can adjust the partial dispersion ratio (θg, F) and Abbe number (νd) of the glass, and are optional components of the optical glass of the present invention. However, if the content of the Na ₂ O component or the K ₂ O component is too large, the stability of the glass tends to decrease, the mechanical strength such as Knoop hardness and abrasion degree of the glass, and chemical durability (water resistance) Property and acid resistance) are likely to decrease. Therefore, the content of each of the Na ₂ O component and the K ₂ O component is preferably 20.0%, more preferably 10.0%, and most preferably 5.0% with respect to the total amount of substances in oxide equivalent composition. The upper limit. The Na ₂ O component and the K ₂ O component use, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ as raw materials. It can be contained in glass.

In the optical glass of the present invention, the molar sum of the contents of the Rn ₂ O component (Rn is one or more selected from Li, Na and K) is preferably 40.0% or less. By adjusting the molar sum to 40.0% or less, the stability of the glass can be further improved and the decrease in transmittance can be suppressed while adjusting the Abbe number (νd) of the glass to a desired range. Moreover, it can be made hard to reduce the water resistance and acid resistance of glass by making this molar sum into 40.0% or less. In particular, by setting the molar sum of the Rn ₂ O component to 20.0% or less, a decrease in the partial dispersion ratio (θg, F) is suppressed, so that a desired high partial dispersion ratio (θg, F) is obtained more. Can be made easier. Therefore, the upper limit of the content of the Rn ₂ O component is preferably 40.0%, more preferably 30.0%, still more preferably 20.0%, and most preferably 16.0%.

In the optical glass of the present invention, the sum of the contents of the Na ₂ O component and the K ₂ O component is preferably 15.0% or less. By reducing this sum, it is possible to obtain an optical glass having high devitrification resistance, high mechanical strength such as Knoop hardness and abrasion degree, and high chemical durability, particularly water resistance and acid resistance. it can. Accordingly, the molar sum (Na ₂ O + K ₂ O) 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 3.4%. And In particular, from the viewpoint of obtaining a glass having high chemical durability and high devitrification resistance, it is more preferable to set the molar sum to 1.0% or less.

In the optical glass of the present invention, the ratio of the content of the Rn ₂ O component to the sum of the contents of the SiO ₂ component and the B ₂ O ₃ component is preferably 0.40 or less. By reducing this ratio, a glass having high chemical durability such as water resistance and acid resistance can be obtained, so that the white turbidity of the surface during polishing or cleaning of the optical glass can be reduced. Moreover, since the viscosity at the liquidus temperature of glass can be increased by reducing this ratio, it is possible to easily obtain glass that can be easily formed. Therefore, the molar ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) in the oxide equivalent composition is preferably 1.00, more preferably 0.80, and most preferably 0.60. _{Incidentally, Rn 2 O / (SiO 2} + B 2 O 3) is may be _{0, Rn 2 O / (SiO} 2 + B 2 O 3) to be more than 0.01, in particular _{Li 2} O / (SiO 2 By making + B ₂ O ₃ ) 0.01 or more, an optical glass with higher devitrification resistance can be obtained. Therefore, the molar ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) in the oxide equivalent composition is preferably 0.01, more preferably 0.05, and most preferably 0.10.

The MgO component is a component useful for reducing dispersion of glass and improving devitrification resistance, and is an optional component of the optical glass of the present invention. However, when the content of the MgO component is too large, the stability of the glass tends to be lowered, so that the visible light transmittance is liable to be lowered, and the glass is easily devitrified by reheating treatment during press molding. Therefore, the content of the MgO component in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. 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 useful for improving the chemical durability, particularly water resistance, by reducing the dispersion and devitrification resistance of the glass, and is an optional component of the optical glass of the present invention. However, when there is too much content of a CaO component, the devitrification resistance of glass will fall easily. Therefore, the content of the CaO component in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 15.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component useful for improving the devitrification resistance of the glass, and is an optional component of the optical glass of the present invention. However, when there is too much content of a SrO component, devitrification resistance will fall easily. Further, it becomes difficult to obtain a desired partial dispersion ratio (θg, F) and Abbe number (νd). Therefore, the content of the SrO component in the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 22.0%. 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 useful for improving the devitrification resistance of the glass, and is an optional component of the optical glass of the present invention. However, if the content of the BaO component is too large, it becomes difficult to obtain a desired partial dispersion ratio (θg, F) and Abbe number (νd). Therefore, the content of the BaO component in the oxide equivalent composition is preferably 45.0%, more preferably 35.0%, and most preferably 30.0%. In addition, although content of BaO component is good also as 0%, devitrification resistance of glass can be improved, keeping the refractive index of glass high by containing BaO component. Therefore, the content of the BaO component in the oxide equivalent composition is preferably more than 0%, more preferably 1.0%, and most preferably 3.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

The ZnO component is a useful component for increasing the stability of the glass to reduce the coloration and improving the devitrification resistance while keeping the partial dispersion ratio (θg, F) of the glass high. It is an optional component of the optical glass. However, if the content of the ZnO component is too large, the Abbe number (νd) tends to increase. Therefore, the content of the ZnO component in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. 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 (R is one or more selected from Mg, Ca, Sr, Ba, Zn) has all physical properties such as devitrification resistance, dispersion, and mechanical strength of the glass. It is a useful component for adjusting. However, if the total content of the RO components is too large, it is difficult to obtain a desired partial dispersion ratio (θg, F), Abbe number (νd), Knoop hardness, and degree of wear. Therefore, the total content of the RO components in the oxide conversion composition is preferably 50.0%, more preferably 45.0%, and most preferably 40.0%. The total amount of the RO component may be 0%. However, by containing at least one of the RO components, the partial dispersion ratio (θg, F) of the glass is increased while improving the devitrification resistance of the glass. The Abbe number (νd) can be easily adjusted. Therefore, the total content of RO components in the oxide equivalent composition is preferably more than 0%, more preferably 10.0%, still more preferably 15.0%, and most preferably 25.0%. Among them, from the viewpoint of easily obtaining a desired high refractive index, the sum of the contents of the SrO component and the BaO component is preferably 1.0% or more, more preferably 5.0% or more, Most preferred is greater than 10.0%.

In the optical glass of the present invention, the ratio of the sum of the contents of the Rn ₂ O component to the sum of the contents of the Bi ₂ O ₃ component, the SiO ₂ component, the B ₂ O ₃ component, and the CaO component is 0.400 or less. It is preferable that Thereby, since content of the component which reduces water resistance with respect to content of the component which raises water resistance reduces, it can make it easy to obtain optical glass with higher water resistance. Therefore, the molar ratio (Rn ₂ O) / (Bi ₂ O ₃ + SiO ₂ + B ₂ O ₃ + CaO) in the oxide equivalent composition is preferably 0.400, more preferably 0.300, and most preferably 0.250. The upper limit. Although this ratio may be 0, it is possible to increase the devitrification resistance of the glass by making this ratio larger than 0, that is, by making the content of the Rn ₂ O component larger than 0. become. Therefore, the molar ratio (Rn ₂ O) / (Bi ₂ O ₃ + SiO ₂ + B ₂ O ₃ + CaO) in the oxide equivalent composition is preferably greater than 0, more preferably 0.050, and most preferably 0.080. May be the lower limit.

In the optical glass of the present invention, the ratio of the sum of the contents of the SiO ₂ component and the B ₂ O ₃ component to the sum of the contents of the Bi ₂ O ₃ component and the Rn ₂ O component is 0.700 or more. preferable. As a result, the content of the component that increases acid resistance relative to the content of the component that decreases acid resistance decreases, so that it is possible to reduce the white turbidity of the glass due to an acidic solution that is often used during polishing or washing. it can. Therefore, the molar ratio (SiO ₂ + B ₂ O ₃ ) / (Bi ₂ O ₃ + Rn ₂ O) in the oxide equivalent composition is preferably 0.700, more preferably 0.800, still more preferably 0.900, Preferably, 1.052 is set as the lower limit. The upper limit of this ratio is not particularly limited as long as a glass having desired devitrification resistance and optical properties can be obtained, but a decrease in refractive index due to excessive inclusion of SiO ₂ component and B ₂ O ₃ component can be suppressed. In this respect, the upper limit is preferably 8.00, more preferably 5.00, and even more preferably 3.00.

La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ component, and Lu ₂ O ₃ component are optional components that adjust the dispersion of the glass low. However, when these contents are too large, the partial dispersion ratio of the glass is lowered, and the stability of the glass is lowered and the glass tends to be devitrified. Therefore, the content of each of the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, the Yb ₂ O ₃ component, and the Lu ₂ O ₃ component is mol% based on the oxide, preferably 10. The upper limit is 0%, more preferably 8.0%, and most preferably 5.0%. Further, the molar sum of the Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of La, Gd, Y, Yb and Lu) is preferably a mol% based on the oxide. Is 15.0%, more preferably 10.0%, and still more preferably 5.0%. In particular, the molar sum of the Ln ₂ O ₃ component is most preferably set to less than 2.0% because coloring of the glass, a decrease in the partial dispersion ratio, and an increase in the Abbe number can be further reduced. La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ component and Lu ₂ O ₃ component are, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O ( X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O ₃ , Lu ₂ O _{3 and the} like can be used.

The TiO ₂ component and the Nb ₂ O ₅ component are components that increase the refractive index (nd), dispersion, and partial dispersion ratio (θg, F) of the glass. However, when there is too much the content, stability of glass will fall and it will become easy to fall in the transmittance. Therefore, the upper limit of 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 10.0%, and most preferably 5.0%. Further, the content of the Nb 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%. TiO ₂ component and _Nb 2 _{O 5} component may be contained in the glass by using as a raw material such as _TiO 2, _Nb 2 _{O 5} or the like.

The WO ₃ component is an optional component useful for improving the partial dispersion ratio (θg, F) of the glass and reducing the Tg. However, when there is too much the content, stability of glass will fall and it will become easy to fall in the transmittance. 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 5.0%, and most preferably 3.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The optical glass of the present invention maintains high transmittance by using a Bi ₂ O ₃ component and an F component together with one or more members selected from the group consisting of a TiO ₂ component, an Nb ₂ O ₅ component, and a WO ₃ component. As it is, the partial dispersion ratio (θg, F) of the glass can be further increased. On the other hand, by making the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component 20.0% or less, the stability of the glass can be increased and devitrification can hardly occur. Therefore, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 5.0%. %.

The P ₂ O ₅ component is an optional component useful for improving the transmittance of glass. However, when the P ₂ O ₅ component is contained, the stability and meltability of the glass tends to be lowered. Therefore, the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 8.0%, still more preferably 4.0%, and even more preferably 2.% with respect to the total amount of glass in the oxide conversion composition. The upper limit is 0%. In particular, from the viewpoint of obtaining a glass having high devitrification resistance, it is most preferable not to contain a P ₂ O ₅ component. The P ₂ O ₅ component contains, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , Na (PO ₃ ), BPO ₄ , H ₃ PO _{4, and the} like as raw materials. It can contain.

The GeO ₂ component is an optional component useful for improving the devitrification resistance of the glass. However, if the content of the GeO ₂ component is too large, the meltability of the glass tends to be lowered. Therefore, the content of the GeO ₂ component with respect to the total amount of the glass having an oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The Ta ₂ O ₅ component is an optional component useful for improving the stability of the glass. However, if the content of the Ta ₂ O ₅ component is too large, the stability of the glass is lowered, the transmittance tends to be lowered, and the raw material cost of the glass is significantly increased. Therefore, the content of the Ta ₂ O ₅ component is preferably 15.0%, more preferably 10.0%, still more preferably 8.0%, most preferably 5. The upper limit is 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 ZrO ₂ component is an optional component useful for improving the chemical durability and mechanical strength of glass. However, if the content of the ZrO ₂ component is too large, the transmittance tends to decrease the stability of the glass is lowered. Therefore, the content of the ZrO ₂ component is preferably 10.0%, more preferably 5.0%, and most preferably 3.0% with respect to the total amount of glass in the oxide equivalent composition. 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 TeO ₂ component is an optional component that has an effect of promoting glass clarification. However, when there is too much the content, the devitrification resistance of glass will fall easily. Therefore, the content of the TeO ₂ component with respect to the total glass material amount of the oxide conversion composition is preferably 35.0%, more preferably 25.0%, still more preferably 15.0%, most preferably 10.0%. Is the upper limit. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components useful for improving the chemical durability and mechanical strength of the glass. However, the _Al 2 _{O 3} content of component and _Ga 2 _{O 3} component is too large, the melting property of the glass tends to decrease. Accordingly, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component with respect to the total amount of the glass having an oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10. The upper limit is 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 CeO ₂ component is an optional component that increases the partial dispersion ratio (θg, F) of the glass. However, if the content is too large, the glass is colored and the transmittance tends to decrease. Therefore, the content of the CeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 3.0%, more preferably 2.0%, still more preferably 1.5%, and even more preferably 1.0%. It is. Most preferably, it is substantially free of CeO ₂ component. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

The Sb ₂ O ₃ component is an optional component that has an effect of promoting clarification of glass. However, when there is too much the content, the devitrification resistance of glass will fall. Therefore, the content of the Sb ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, even more preferably 15.0%, and most preferably 10.5% with respect to the total amount of glass in the oxide equivalent composition. The upper limit is 0%. In particular, from the viewpoint of reducing the environmental load due to the inclusion of the Sb ₂ O ₃ component, the content of the Sb ₂ O ₃ component may be 1.0% or less. 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.

Incidentally, components of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

<About ingredients that should not be included>
In this invention, another component can be added as needed in the range which does not impair the characteristic of the glass of this invention. However, transitions such as V, Cr, Mn, Co, Ni, Cu, Ag, Mo, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Lu except Ti, Zr, and Nb Even when each of the metal components is contained alone or in combination with a small amount, the glass is colored to cause absorption at a specific wavelength in the visible region. Therefore, it is preferable that the optical glass of the present invention does not substantially contain the above components. Here, “substantially does not contain” means that it is not contained artificially 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.

The glass that is preferably used as the optical glass of the present invention cannot be expressed directly in the description of mass% or cation% because the composition is expressed in mol% based on the oxide, but is required in the present invention. The composition of mass% in the oxide conversion composition and the composition of cation% and anion% of each component present in the glass composition satisfying various properties generally take the following values.
(Composition by mass% display)
Bi ₂ O ₃ component 15.0 to 85.0 mass% and F component more than 0 mass% to 8.0 mass%
And B ₂ O ₃ component 0 to 20.0 mass%, and / or SiO ₂ component 0 to 15.0 mass%, and / or Li ₂ O component 0 to 5.0 mass%, and / or Na ₂ O component 0 to 7.0 wt%, and / or _{K 2} O ingredient 0 to 10.0 wt%, and / or MgO component from 0 to 6.0 wt%, and / or CaO component 0 to 10.0 wt%, and / or SrO component 0 to 20.0 wt%, and / or BaO components from 0 to 40.0 wt%, and / or ZnO component 0 to 20.0 wt%, and / or _La 2 _{O 3} component 0-20. 0% by mass and / or Gd ₂ O ₃ component 0-20.0% by mass and / or Y ₂ O ₃ component 0-15.0% by mass and / or Yb ₂ O ₃ component 0-20.0% by mass %, and / or _Lu 2 _{O 3} component 0 to 20.0 wt%, and / or TiO ₂ component 0 10.0 wt%, and / or _Nb 2 _{O 5} component from 0 to 15.0% by weight, and / or WO ₃ components 0 to 15.0 wt%, and / or _P 2 _{O 5} component 0 to 10.0 mass % And / or GeO ₂ component 0 to 35.0 mass%, and / or Ta ₂ O ₅ component 0 to 30.0 mass%, and / or ZrO ₂ component 0 to 10.0 mass%, and / or TeO ₂ components from 0 to 30.0% by weight, and / or _Al 2 _{O 3} component from 0 to 15.0 wt%, and / or _Ga 2 _{O 3} component from 0 to 30.0 wt%, and / or CeO ₂ component 0 6.0 wt%, and / or _Sb 2 _{O 3} component from 0 to 40.0% by weight,

(Composition by cation% / anion% display)
Bi ³⁺ 13.0-65.0 cation%,
And B ^{3+ 0 to} 65.0 cation%, and / or Si ^{4+ 0 to} 50.0 cation%, and / or Li ^{+ 0 to} 35.0 cation%, and / or Na ^{+ 0 to} 25.0 cation%, And / or K ^{+ 0 to} 25.0 cation%, and / or Mg ^{2+ 0 to} 20.0 cation%, and / or Ca ^{2+ 0 to} 20.0 cation%, and / or Sr ^{2+ 0 to} 20.0 cation. % And / or Ba ^{2+ 0 to} 30.0 cation% and / or Zn ^{2+ 0 to} 20.0 cation% and / or La ^{3+ 0 to} 13.0 cation% and / or Gd ^{3+ 0 to} 13. 0 cation% and / or Y ³⁺ 0 to 13.0 cation% and / or Yb ^{3+ 0 to} 13.0 cation% and / or Lu ³⁺ 0 to 13.0 cation% and / or Ti ⁴⁺ 0 15.0 On%, and / or ^Nb 5+ 0-25.0 cationic%, and / or ^W 6+ 0 to 7.0 cation%, and / or ^P 5+ from 0 to 12.0 cationic%, and / or ^Ge 4+ 0 to 20 0.0 cation% and / or Ta ⁵⁺ 0 to 20.0 cation% and / or Zr ^{4+ 0 to} 7.0 cation% and / or Te ⁴⁺ 0 to 25.0 cation% and / or Al ³⁺ 0 ˜25.0 cation%, and / or Ga ³⁺ 0-25.0 cation%, and / or Ce ⁴⁺ 0-2.5 cation%, and / or Sb ³⁺ 0-40.0 cation%,
And F ^{-0 to} 20.0 anion%

[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 in a quartz crucible or a gold crucible and melted at a temperature range of 750 ° C. to 950 ° C. for 2 to 3 hours. Then, the mixture is homogenized by stirring, and after about 1 hour has passed since the temperature is lowered to about 800 to 650 ° C., it is cast into a mold and gradually cooled.

<Physical properties>
The optical glass of the present invention has a high partial dispersion ratio (θg, F) and a low Abbe number [νd]. More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably 0.63, more preferably 0.64, and most preferably 0.65. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 27, more preferably 25, and most preferably 22 as the upper limit. As a result, an optical glass having a high partial dispersion ratio (θg, F) and a low Abbe number [νd] can be obtained. Therefore, it is combined with an optical glass having a low partial dispersion ratio (θg, F) and a high Abbe number [νd]. Thus, the chromatic aberration of the optical element can be corrected more accurately. The upper limit of the partial dispersion ratio (θg, F) of the optical glass of the present invention is not particularly limited, but is generally 0.70 or less, more specifically 0.69 or less, and more specifically 0.68 or less. There are often. Further, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but is generally 10 or more, more specifically 12 or more, and more specifically 15 or more in many cases.

Here, the optical glass of the present invention has an Abbe number [νd] of 27 or less and satisfies a partial dispersion ratio [θg, F]> − 0.0131 × [νd] +0.9000. Accordingly, in the plot of the partial dispersion ratio [θg, F] and the Abbe number [νd], the optical element using this optical glass is greatly separated from the general glass νd−θg, F line. It can be inferred that it is useful in reducing chromatic aberration more significantly. Here, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably larger than (−0.0131 × [νd] +0.9000), more preferably (−0.0131 × [νd]). Greater than +0.9040), and most preferably greater than (−0.0131 × [νd] +0.9080). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass of the present invention is not particularly limited, but is, for example, (−0.0131 × [νd] +0.9500) or less, more specifically (−0.0131). × [νd] +0.9450), more specifically, (−0.0131 × [νd] +0.9400) or less in many cases. In the case of a glass having a small Abbe number (ν _d ) like the optical glass of the present application, the partial dispersion ratio (θg, F) of a general glass is higher than that of a normal line, and the partial dispersion of a general glass The relationship between the ratio (θg, F) and the Abbe number (ν _d ) is represented by a curve in which the variation in the partial dispersion ratio increases as the Abbe number decreases. However, since it is difficult to approximate this curve, in the present invention, the partial dispersion ratio (θg, F) is lower than that of a general glass νd−θg, F line. Expressed.

Moreover, the optical glass of the present invention has high chemical durability.
More specifically, the optical glass of the present invention has a chemical durability (water resistance) by a glass powder method according to JOGIS06-1999, preferably class 1 to 5, more preferably class 1 to 4, most preferably Preferably it is class 1-3. 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 polishing and cleaning can be performed more easily. 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 0.10% by mass. In class 1, the weight loss rate of the sample before and after the measurement is less than 0.05% by mass, class 2 is 0.05% by mass or more and less than 0.10% by mass, and class 3 is 0%. It is 10 mass% or more and less than 0.25 mass%.

  Further, the optical glass of the present invention has a chemical durability (acid resistance) by a glass powder method according to JOGIS06-1999, preferably class 1 to 5, more preferably class 1 to 4, most preferably class 1 ~ 3. Thus, 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 polishing process and the cleaning can be performed more easily. 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. In addition, “the chemical durability (acid resistance) by the powder method is class 1 to 5” 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 2.20% 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.

Moreover, it is preferable that the optical glass of this invention has little coloring. 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 600 nm or less, more preferably 580 nm or less, and most preferably. Is 550 nm or less. The wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% is 480 nm or less, more preferably 460 nm or less, and most preferably 440 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 is preferably used as a material for an optical element that handles visible light such as a lens. be able to.

The optical glass of the present invention preferably has a high refractive index. More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.80, still more preferably 1.85, and most preferably 1.90. . Here, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is not particularly limited, but is generally 2.30 or less, more specifically 2.20 or less, and more specifically 2.10 or less. There are many cases. 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. In addition, since the number of elements in the optical system can be reduced, the entire optical system can be reduced in size.

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. Among them, it is particularly preferable to produce optical elements such as lenses, prisms, and mirrors from the optical glass of the present invention using means such as reheat press molding and precision press molding. As a result, when used in optical devices that transmit visible light to optical elements such as cameras and projectors, the optical system in these optical devices can be miniaturized while realizing high-definition and high-precision imaging characteristics. Can be planned. In addition, since an optical element using this optical glass is useful for reducing chromatic aberration, high-definition and high-precision imaging characteristics can be realized when used in an optical device such as a camera or a projector.

  Here, in order to produce an optical element made of the optical glass of the present invention, a strip material (plate-like hot-formed product) formed from the optical glass or a polishing process formed by press-molding the strip material is used. The preform may be manufactured by cold working such as grinding and polishing, and molten glass is dropped from the outlet of an outflow pipe of platinum or the like for precision press molding such as spherical A preform may be produced and precision press molding may be performed on the precision press molding preform. In particular, by forming a preform for polishing processing from the optical glass of the present invention, white turbidity on the glass surface due to polishing processing is reduced, so that an optical element suitable for the purpose of transmitting visible light can be obtained. In addition, by forming a preform for precision press molding from the optical glass of the present invention, the white turbidity of the glass surface when this preform or glass after precision press molding is washed is reduced, so that visible light is transmitted. An optical element suitable for the intended use can be obtained. In addition, the means for producing the glass molded body is not limited to these means.

Compositions of Examples (No. 1 to No. 21) and Comparative Examples (No. 1) of the present invention, refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), Tables 1 to 3 show the results of chemical durability (acid resistance, water resistance) by the powder method and wavelength (λ ₅ ) indicating a spectral transmittance of 5%. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of Examples (No. 1 to No. 21) and Comparative Examples (No. 1) 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 glasses such as hydroxides and metaphosphoric acid compounds are selected, and the glass weight is 400 g with the compositions of the examples and comparative examples shown in Tables 1 to 3. Are weighed and mixed uniformly, and then put into a quartz crucible or a gold crucible, and melted in an electric furnace at a temperature range of 750 ° C. to 950 ° C. for 2 to 3 hours according to the degree of melting difficulty of the glass composition. After about 1 hour has passed since the temperature was lowered to about 800 to 650 ° C., it was cast into a mold and slowly cooled.

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. 21) and Comparative Example (No. 1) 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 intercept when the slope a is 0.0131 in the relational expression (θg, F) = − a × ν _d + b 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 water resistance of the glass of an Example (No.1-No.21) and a comparative example (No.1) is Japan Optical Glass Industry Association standard "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, the acid resistance of the glass of an Example (No.1-No.21) and a comparative example (No.1) 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 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, about the transmittance | permeability of the glass of an Example (No.1-No.21) and a comparative example (No.1), it measured according to Japan Optical Glass Industry Association standard JOGIS02. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. Specifically, a face-parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722 to obtain λ ₅ (wavelength at a transmittance of 5%).

As shown in Tables 1 to 3, the optical glass of the examples of the present invention had a partial dispersion ratio (θg, F) of 0.63 or more, more specifically 0.6640 or more. Moreover, the optical glass of the Example of this invention had Abbe number ((nu) _d ) of 27 or less, more specifically 20 or less, and all were in the desired range. Further, in the optical glass of the example of the present invention, the partial dispersion ratio (θg, F) is larger than (−0.0131 × [νd] +0.9000) in relation to the Abbe number (ν _d ). More specifically, it was larger than (−0.0131 × [νd] +0.9200) and was within the desired range. Therefore, since the optical glass of the embodiment of the present invention has a desired high partial dispersion ratio (θg, F) and a low Abbe number (ν _d ), it may be useful for correcting chromatic aberration of an optical element. It was revealed.

  In addition, the optical glasses of the examples of the present invention all had chemical durability (water resistance) by the powder method of class 1 to 5, more specifically class 2 to 3. In addition, the optical glasses of the examples of the present invention all have chemical durability (acid resistance) by the powder method of class 1 to 5, more specifically class 1 to 4, and all are within a desired range. It was. On the other hand, the glass of the comparative example was class 6 in both chemical durability (water resistance) and chemical durability (acid resistance) by the powder method. For this reason, it became clear that the optical glass of the Example of this invention did not generate | occur | produce fogging on the surface at the time of grinding | polishing or a washing | cleaning compared with the glass of a comparative example.

In addition, in all the optical glasses of the examples of the present invention, λ ₅ (wavelength at 5% transmittance) was 480 nm or less, more specifically, 476 nm or less. For this reason, it became clear that the optical glass of the Example of this invention has little coloring, and its transparency with respect to the light of the wavelength of a visible region is high.

In addition, the optical glasses of the examples of the present invention all had a refractive index (n _d ) of 1.75 or more, more specifically 1.93 or more, and were within a desired range.

  Therefore, the optical glass of the example of the present invention has a very large partial dispersion ratio (θg, F) and a low Abbe number, but is difficult to cause fogging on the surface during polishing or cleaning, and has a high refractive index. It has become clear that it is preferably used for an optical element or the like that handles the wavelength in the visible region.

  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)

In mol% with respect to the total amount of substances in oxide equivalent composition ,
Bi ₂ O ₃ component from 15.0 to 40.0%,
SiO ₂ component及beauty _B 2 _{O 3} component in total 20.0% more than 50.0% or less, and
Containing 25.0% or more and 50.0% or less of a molar sum of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr and Ba);
The content of SiO ₂ component is 40.0% or less,
Containing 5.0% or more and 15.0% or less of the F component in the mol% of the external ratio with respect to the oxide-based substance amount
Chemical durability (water resistance) by the powder method is class 1-5,
The partial dispersion ratio [θg, F] is 0.63 or more, the Abbe number [νd] is 27 or less, and the partial dispersion ratio [θg, F]> − 0.0131 × [νd] +0.9000 is satisfied. Optical glass. In mol% with respect to the total amount of substances in oxide equivalent composition,
B ₂ O ₃ component 0% to 50.0 %
Claim 1 Symbol mounting an optical glass containing. Molar sum _{(Bi 2 O} 3 + F) is most 60.0% less than 20.0% according to claim 1 or 2, wherein the optical glass with respect to the total amount of substance of the oxide composition in terms. In mol% with respect to the total amount of substances in oxide equivalent composition,
Li ₂ O component from 0 to 30.0% and / or Na ₂ O component from 0 to 20.0% and / or _{K 2} O ingredient from 0 to 20.0%
The optical glass according to any one of claims 1 to 3 . (Wherein, Rn is Li, Na, 1 or more selected from the group consisting of K) Rn ₂ O component to the glass the total amount of substance of the oxide composition in terms of claim 4 molar sum of at most 40.0% The optical glass described. The optical glass according to claim 4 or 5 , wherein a molar sum (Na ₂ O + K ₂ O) with respect to the total amount of glass having an oxide conversion composition is 15.0% or less. The optical glass according to claim 6, wherein the molar ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) in the oxide equivalent composition is 1.00 or less. MgO component 0 to 30.0% and / or CaO component 0 to 30.0% and / or SrO component 0 to 30.0% and / or BaO in mol% with respect to the total amount of glass in the oxide conversion composition Component 0-45.0% and / or ZnO component 0-30.0%
The optical glass according to any one of claims 1 to 7 . Molar ratio _{(Rn 2 O) / (Bi} 2 O 3 + SiO 2 + B 2 O 3 + CaO) is 0.400 or less either described optical glass of claims 1 to 8 which is in terms of oxide composition. The optical glass according to any one of claims 1 to 9, wherein a molar ratio (SiO ₂ + B ₂ O ₃ ) / (Bi ₂ O ₃ + Rn ₂ O) in an oxide equivalent composition is 0.700 or more. The glass the total amount of substance of the oxide composition in terms of, from 0 to 10.0% _La 2 _{O 3} component in mol% and / or _Gd 2 _{O 3} component from 0 to 10.0% and / or _Y 2 _{O 3} component 0 10.0% and / or _Yb 2 _{O 3} component from 0 to 10.0% and / or _Lu 2 _{O 3} component from 0 to 10.0%
The optical glass according to any one of claims 1 to 10 . The molar sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) with respect to the total amount of glass in the oxide equivalent composition is 15.0% or less The optical glass according to claim 11 . TiO ₂ component 0 to 20.0% and / or Nb ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0 to 10.0 in mol% with respect to the total amount of glass in oxide conversion composition %
The optical glass according to any one of claims 1 to 12 . The optical glass according to claim 13 , wherein a molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) with respect to the total amount of the glass having an oxide conversion composition is 20.0% or less. The glass the total amount of substance of the oxide composition in terms of, 0~10.0% _P 2 _{O 5} component in mol% and / or GeO ₂ component from 0 to 30.0% and / or _Ta 2 _{O 5} component 0 to 15 .0% and / or ZrO ₂ component from 0 to 10.0% and / or TeO ₂ component from 0 to 35.0% and / or _Al 2 _{O 3} component from 0 to 20.0% and / or _Ga 2 _{O 3} component 0 20.0% and / or CeO ₂ component from 0 to 3.0% and / or _Sb 2 _{O 3} component from 0 to 30.0%
The optical glass according to any one of claims 1 to 14 . The optical glass according to any one of claims 1 to 15 , wherein chemical durability (acid resistance) by a powder method is class 1 to 5. A preform for polishing and / or precision press molding comprising the optical glass of any one of claims 1 to 16 . An optical element obtained by polishing the preform of claim 17 . An optical element formed by precision press-molding the preform of claim 17 . An optical element formed of the optical glass of claims 1 16 any one. An optical apparatus having an optical element according to any of claims 18 20.

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