JP2011093731A - Optical glass, preform, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical glass containing Bi<SB>2</SB>O<SB>3</SB>which has high transparency to visible light although having very high relative partial dispersion (θg, F) and allows reduction in size of an element or an optical system, and to provide a preform using the same. <P>SOLUTION: The optical glass contains a SiO<SB>2</SB>component and/or a B<SB>2</SB>O<SB>3</SB>component and contains a Bi<SB>2</SB>O<SB>3</SB>component in an amount of 40.0% or more and 90.0% or less in terms of mass% of oxides and has a relative partial dispersion (θg, F) of 0.63 or more, a refractive index (nd) of 1.90 or more, and an Abbe number (νd) of 27 or less, wherein the wavelength (λ<SB>5</SB>) which shows a spectral transmittance of 5% with a 10 mm thick sample is 460 nm or less. <P>COPYRIGHT: (C)2011,JPO&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 particular, optical glasses having a specific partial dispersion ratio (θg, F) have a remarkable effect in correcting aberrations, and various glasses have been developed in order to increase the degree of freedom in optical design. When these lenses made of anomalous dispersion glass are used in combination with other lenses, chromatic aberration can be corrected in a wide wavelength range from ultraviolet to infrared.

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, the optical glasses disclosed in Patent Documents 1 and 2 have not sufficient refractive index. Therefore, it is necessary to further increase the refractive index in order to reduce the number of optical elements used in the optical system and reduce the thickness of the optical elements, and to meet the demands for high accuracy, light weight, and downsizing of the optical system. is there.

Further, a glass containing a Bi ₂ O ₃ component as a main component is often colored yellow or orange, and the transmittance for light having a wavelength in the visible region is often lost. Therefore, there is a demand for an optical glass having both a high partial dispersion ratio (θg, F), a high refractive index, and high transparency with respect to light having a wavelength in the visible region.

The present invention has been made in view of the above problems, and the object of the present invention is an optical glass containing Bi ₂ O ₃ while having a very high partial dispersion ratio (θg, F). An object of the present invention is to obtain an optical glass that is highly transparent to visible light and that can reduce the size of elements and optical systems, and a preform using the optical glass.

As a result of intensive studies and studies to solve the above-mentioned problems, the present inventors have set the partial dispersion ratio (θg, F) of the glass by making at least the content of Bi ₂ O ₃ within a predetermined range. While increasing, it has been found that the transmittance of the glass for light on the short wavelength side in the visible region is increased and the refractive index (nd) of the glass is increased, and the present invention has been completed. Specifically, the present invention provides the following.

(1) It contains a SiO ₂ component and / or a B ₂ O ₃ component, contains 40.0% or more and 90.0% or less of a Bi ₂ O ₃ component in mass% based on oxide, and has a partial dispersion ratio (θg, F) is 0.63 or more, refractive index (nd) is 1.90 or more, Abbe number (νd) is 27 or less, and a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is 460 nm. Optical glass that is:

(2) The optical glass according to (1), which contains 67.0% or more of a Bi ₂ O ₃ component in mass% based on an oxide.

(3) The optical glass according to (1) or (2), which contains less than 85.0% of Bi ₂ O ₃ component by mass% based on oxide.

(4)% by mass based on oxide,
SiO ₂ component 0 to 20.0% and / or B ₂ O ₃ component 0 to 30.0%
The optical glass according to any one of (1) to (3), which contains each component of

(5) The optical glass according to (4), wherein the mass of the oxide is based on the mass, and the mass sum of the SiO ₂ component and the B ₂ O ₃ component is more than 0% and 20.0% or less.

(6)% by mass based on oxide,
TiO ₂ component 0 to 10.0% and / or Nb ₂ O ₅ component 0 to 10.0%
The optical glass according to any one of (1) to (5), further comprising:

(7) The optical glass according to (6), in which the mass sum of the TiO ₂ component and the Nb ₂ O ₅ component is greater than 0% and equal to or less than 15.0% by mass% based on the oxide.

(8)% by mass based on oxide,
MgO component 0-20.0%, and / or CaO component 0-20.0%, and / or SrO component 0-20.0%, and / or BaO component 0-20.0%, and / or ZnO component 0 to 20.0%
The optical glass according to any one of (1) to (7), further containing each component of:

  (9) The mass sum of the oxide component is 3% by mass of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn). The optical glass described in (8) below.

  (10) On the oxide basis, the mass sum (SrO + ZnO) of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) The optical glass according to (8) or (9), wherein the mass ratio is 0.40 or more.

(11)% by mass based on oxide,
Li ₂ O component 0 to 10.0% and / or Na ₂ O component 0 to 10.0% and / or K ₂ O component 0 to 10.0% and / or Rb ₂ O component 0 to 5. 0%, and / or Cs ₂ O component from 0 to 5.0%
The optical glass according to any one of (1) to (10), further containing each component of

(12) The mass sum of the Rn ₂ O component (wherein Rn is at least one selected from the group consisting of Li, Na, K, Rb, and Cs) in terms of mass% based on oxide is 5. The optical glass according to (11), which is 0% or less.

(13)% by mass based on oxide,
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 ₃ component 0 to 10.0% and / or Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (12), further comprising:

(14) The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) in terms of mass% based on oxide is 20.0. % Or less of the optical glass according to (13).

(15) In mass% based on oxide,
GeO ₂ component 0-20.0% and / or P ₂ O ₅ component 0-10.0% and / or Al ₂ O ₃ component 0-10.0% and / or ZrO ₂ component 0-10. 0% and / or Ta ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0 to 10.0% and / or TeO ₂ component 0 to 20.0% and / or Tl ₂ O ₃ components 0 to 10.0% and / or CeO ₂ components 0 to 10.0% and / or Sb ₂ O ₃ components 0 to 3.0%
The optical glass according to any one of (1) to (14), further comprising:

  (16) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (15).

  (17) An optical element obtained by polishing the preform for polishing according to (16).

  (18) An optical element obtained by precision press molding the preform for precision press molding described in (16).

According to the present invention, by setting the content of at least Bi ₂ O ₃ within a predetermined range, the partial dispersion ratio (θg, F) of the glass is increased, but the light on the short wavelength side in the visible region is increased. The transmittance of the glass is increased and the refractive index (nd) of the glass is increased. Therefore, an optical glass that has a very large partial dispersion ratio (θg, F), has high transparency to visible light, and can be miniaturized in elements and optical systems, and a preform using the optical glass Can be obtained.

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 SiO ₂ component and / or a B ₂ O ₃ component, contains a Bi ₂ O ₃ component in an amount of 40.0% or more and 90.0% or less by mass% based on the oxide, and is partially dispersed. A wavelength (λ ₅ ) having a spectral transmittance of 5% in a sample having a ratio (θg, F) of 0.63 or more, an Abbe number (νd) of 27 or less, and a thickness of 10 mm is 460 nm or less. By making the content of at least Bi ₂ O ₃ within a predetermined range, the transmittance of the glass for light on the short wavelength side in the visible region is increased while the partial dispersion ratio (θg, F) of the glass is increased. And the refractive index (nd) of the glass is increased. For this reason, an optical glass that has a very high partial dispersion ratio (θg, F), has high transparency to visible light, and can reduce the size of elements and optical systems, and Renovation 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. Unless otherwise specified, the content of each component is expressed in terms of mass% 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. It is the composition which described each component contained in glass by making the sum total of the mass of the said oxide 100 mass%. In addition, the total amount of F in which a part or all of the oxide is fluoride-substituted is the fluorine content that may be present in the glass composition of the present invention, based on the oxide-based composition of 100%. This is expressed in mass% when calculated as F atoms.

<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 than 40.0%, it is possible to easily obtain the above-mentioned technical effect. In particular, by making the content of the Bi ₂ O ₃ component 67.0% or more, an optical glass having a desired high refractive index (nd) can be easily obtained. On the other hand, when the content of the Bi ₂ O ₃ component is 90.0% or less, and more preferably less than 85.0%, the stability of the glass is enhanced, so that the coloring of the glass can be reduced. Therefore, the content of the Bi ₂ O ₃ component is in mass% based on the oxide, preferably 40.0%, more preferably 50.0%, and most preferably 67.0%. The content of the Bi ₂ O ₃ component is preferably 90.0%, more preferably 88.0%, and most preferably less than 85.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The SiO ₂ component is a component that improves the stability of the glass and reduces devitrification, and has the effect of reducing the dispersion of the glass and the effect of improving the transmittance. The optical glass of the present invention Is an optional component. 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. Therefore, the content of the SiO ₂ component is, by mass% based on oxide, preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The B ₂ O ₃ component is a component having an effect of improving the stability of the glass to reduce devitrification and maintaining a high partial dispersion ratio (θg, F) of the 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 in mass% based on the oxide, preferably 30.0%, more preferably 23.0%, and most preferably 15.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material.

The SiO ₂ component and the B ₂ O ₃ component do not necessarily need to be contained, but these are glass-forming components and components that can reduce devitrification, so at least one of them is contained in excess of 0%. It is preferable. However, if these contents are too large, it is difficult to obtain a desired partial dispersion ratio (θg, F) and Abbe number (νd). Therefore, the mass sum of the SiO ₂ component and the B ₂ O ₃ component is mass% based on the oxide, preferably more than 0%, more preferably 0.5%, and most preferably 1.0%. . On the other hand, the mass sum of the SiO ₂ component and the B ₂ O ₃ component is preferably 50.0%, more preferably 45.0%, and most preferably 35.0%.

The TiO ₂ component is a component that increases 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. Accordingly, the content of the TiO ₂ component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The Nb ₂ O ₅ component is a useful component for improving the refractive index (nd) and the partial dispersion ratio (θg, F) of the glass. However, when the content of Nb ₂ O ₅ component is too large, the transmittance tends to decrease the stability of the glass is lowered. Therefore, the content of the Nb ₂ O ₅ component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. 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 and the Nb ₂ O ₅ component do not necessarily have to be contained, but it is high by using a predetermined amount of the Bi ₂ O ₃ component and the TiO ₂ component and / or the Nb ₂ O ₅ component in combination. The partial dispersion ratio (θg, F) of the glass can be further increased while maintaining the transmittance. Accordingly, the total content of the TiO ₂ component and the Nb ₂ O ₅ component is, in terms of mass% based on the oxide, preferably more than 0%, more preferably 0.5%, and most preferably 0.9%. To do. On the other hand, when the total content of the TiO ₂ component and the Nb ₂ O ₅ component is too large, the stability of the glass is lowered, and the transmittance for light having a wavelength in the visible region is likely to be lowered. Therefore, the total content of the TiO ₂ component and the Nb ₂ O ₅ component is mass% based on the oxide, preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. To do.

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 is preferably 20.0%, more preferably 15.0%, and most preferably 10.0% in terms of mass% based on the oxide. 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 reducing the dispersion of glass and improving devitrification resistance and chemical durability, 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 upper limit of the content of the CaO component and the mass% based on the oxide is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component 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 is preferably 20.0%, more preferably 15.0%, and most preferably 10.0% in terms of mass% based on the oxide. 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 upper limit of the content of the BaO component is 20.0%, more preferably 15.0%, and most preferably 10.0% in terms of mass% based on the oxide. 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 upper limit of the content of the ZnO component is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. An optical glass having desired characteristics in the present invention can be produced without containing a ZnO component. However, by containing a ZnO component, the glass has a partial dispersion ratio (θg, F) and an Abbe number (νd). Adjustment can be made easily. Accordingly, the content of the ZnO component is, in terms of mass% based on the oxide, preferably exceeding 0%, more preferably 0.5%, and most preferably 1.0%. 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 RO components is too large, it becomes difficult to obtain a desired partial dispersion ratio (θg, F) and Abbe number (νd). Therefore, the total content of RO components is preferably 35.0%, more preferably 30.0%, and most preferably 25.0%. In addition, although it does not contain the RO component, it can produce an optical glass having the desired characteristics in the present invention, but by containing any of the RO component, while increasing the devitrification resistance of the glass, The partial dispersion ratio (θg, F) and Abbe number (νd) of the glass can be easily adjusted. Accordingly, the total content of the RO component is, in terms of mass% based on oxides, preferably exceeding 0%, more preferably 1.0%, and most preferably 2.0%.

  In the optical glass of the present invention, the mass sum (SrO + ZnO) with respect to the mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn). The mass ratio is preferably 0.40 or more. This increases the proportion of the SrO component and ZnO component that hardly affect the transmittance of the glass among the RO components that increase the stability of the glass, so that the wavelength in the visible region is maintained while having the devitrification resistance of the glass. Can be obtained statistically high glass for light. This tendency becomes particularly remarkable when the mass ratio is 0.70 or more. Therefore, the mass ratio (SrO + ZnO) / RO based on oxide is preferably 0.40, more preferably 0.60, and most preferably 0.70.

The Li ₂ O component is a component that improves the stability of the glass to reduce devitrification and coloring, and is an effective component for lowering the glass Tg, and is an optional component of the optical glass of the present invention. However, if 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 mechanical strength tends to be lowered. Therefore, the upper limit of the content of the Li ₂ O component is 10.0% by mass, preferably 10.0%, more preferably 8.0%, and most preferably 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.

Na 2 _O component, the partial dispersion ratio of glass ([theta] g, F) and a component capable of adjusting the Abbe number ([nu] d), are optional components of the optical glass of the present invention. However, when the content of Na 2 _O component is too much, it tends to decrease. Stability of the glass, the chemical durability and mechanical strength of the glass becomes liable to lower. Therefore, the content of the Na ₂ O component is mass% based on the oxide, preferably 10.0%, more preferably 8.0%, 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.

K 2 _O component, the partial dispersion ratio of glass ([theta] g, F) and a component capable of adjusting the Abbe number ([nu] d), are optional components of the optical glass of the present invention. However, when the content of K 2 _O component is too much, it tends to decrease. Stability of the glass, the chemical durability and mechanical strength of the glass becomes liable to lower. Therefore, the upper limit of the content of the K ₂ O component is, based on oxide, mass%, preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

The Rb ₂ O component and the Cs 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, when these are contained excessively, the chemical durability and the mechanical strength are likely to be lowered like the other alkali metal components. In addition, the Rb ₂ O component is low in output and is not suitable for optical glass materials. Accordingly, the content of each of the Rb ₂ O component and the Cs ₂ O component is preferably 5.0%, more preferably 4.0%, and most preferably 3.0% as the upper limit of mass% based on the oxide. And

In the optical glass of the present invention, the mass sum of the contents of the Rn ₂ O component (Rn is one or more selected from Li, Na, K, Rb and Cs) may be 5.0% or less. preferable. By adjusting the mass sum to 5.0% or less, the stability of the glass can be further increased and the decrease in transmittance can be suppressed while adjusting the Abbe number (νd) of the glass to a desired range. In particular, by setting the mass sum of the Rn ₂ O component to 1.6% or less, a decrease in the partial dispersion ratio (θg, F) is suppressed, so that a desired high partial dispersion ratio (θg, F) can be obtained more. Can be made easier. Therefore, the content of the Rn ₂ O component (Rn is at least one selected from Li, Na, K, Rb, and Cs) is preferably 5.0%, more preferably 3.0%, and most preferably 1. The upper limit is 6%.

The La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, and Yb ₂ O ₃ component are optional components that adjust the dispersion of the glass to a low level. However, when there is too much these content, stability of glass will fall and the transmittance | permeability with respect to the light of visible region will fall easily. Therefore, the content of each of the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component is mass% based on the oxide, preferably 10.0%, more preferably The upper limit is 8.0%, and most preferably 6.0%. Further, the mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y and Yb) is mass% based on the oxide, preferably 20 0.0%, more preferably 10.0%, and still more preferably 6.0%. In particular, it is most preferable that the mass sum of the Ln ₂ O ₃ component is less than 1.0% because the coloring of the glass can be further reduced. _La 2 _{O 3} component of the glass, _Gd 2 _{O 3 component,} Y 2 _{O 3} component and _Yb 2 _{O 3} component is, for example, as raw materials _{La 2 O 3, La (NO} 3) 3 · XH 2 O (X is any Integer), Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O _{3 and the} like can be used.

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 is, by mass% based on oxide, preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The P ₂ O ₅ component is an optional component useful for improving the transmittance of glass. However, when the content of P ₂ O ₅ component is too large, the melting property of the glass tends to decrease. Therefore, the upper limit of the content of the P ₂ O ₅ component is an oxide-based mass%, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. 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 Al ₂ O ₃ component is an optional component useful for improving the chemical durability and mechanical strength of the glass. However, the content of Al ₂ O ₃ component is too large, the melting property of the glass tends to decrease. Therefore, the content of the Al ₂ O ₃ component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The ZrO ₂ component is 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 mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

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 mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The 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 is 10.0% by mass, 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 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 is, by mass% based on the oxide, preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The Tl ₂ O ₃ component is an optional component useful for adjusting the partial dispersion ratio (θg, F) and Abbe number (νd) of the glass. However, when there is too much the content, the transmittance | permeability of glass will fall easily easily. Therefore, the content of the Tl ₂ O ₃ component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Tl ₂ O ₃ component can be contained in the glass using, for example, Tl ₂ O ₃ 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 is preferably 3.0%, more preferably 2.0%, and even more preferably 1.0% by mass% based on the oxide. 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 expressed by mass% based on the oxide, preferably 3.0%, more preferably 2.0%, and most preferably 1.0%. 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 .

The F component is an effective component for reducing the glass dispersion and improving the meltability. However, when there is too much content of F component, since the devitrification resistance of glass will fall significantly, transparency with respect to visible light will be lost easily. Therefore, the total amount of F in which part or all of the oxide is fluoride-substituted is preferably 10.0%, more preferably 5.0%, and more preferably 1.0%. In particular, when increasing the devitrification resistance of the glass, it is most preferable not to contain the F component. 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.

<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 preferably used as the optical glass of the present invention cannot be expressed directly in the description of mol% because its composition is expressed by mass% based on the oxide, but it exhibits various properties required in the present invention. The composition represented by mol% of each component present in the glass composition to be filled generally takes the following values on an oxide basis.
Bi ₂ O ₃ component from 20.0 to 80.0 mol%
And SiO ₂ component 0 to 15.0 mol%, and / or B ₂ O ₃ component 0 to 30.0 mol%, and / or Li ₂ O component 0 to 25.0 mol%, and / or Na ₂ O component 0 to 25.0 mol%, and / or _{K 2} O ingredient from 0 to 25.0 mol%, and / or Rb ₂ O component from 0 to 25.0 mol%, and / or Cs ₂ O component 0 to 25.0 Mol% and / or MgO component 0 to 15.0 mol% and / or CaO component 0 to 15.0 mol% and / or SrO component 0 to 15.0 mol% and / or BaO component 0 to 20 2.0 mol%, and / or ZnO component from 0 to 15.0 mol%, and / or _La 2 _{O 3} component from 0 to 15.0 mol%, and / or _Gd 2 _{O 3} component from 0 to 15.0 mol%, and / or _Y 2 _{O 3} component from 0 to 15.0 mol%, and / or _Yb 2 _{O 3} formed 0 to 15.0 mol%, and / or GeO ₂ component 0 to 20.0 mol%, and / or _P 2 _{O 5} component from 0 to 15.0 mol%, and / or _Al 2 _{O 3} component 0-15. 0 mol%, and / or TiO ₂ component from 0 to 15.0 mol%, and / or ZrO ₂ component from 0 to 15.0 mol%, and / or _Nb 2 _{O 5} component from 0 to 15.0 mol%, and / Or Ta ₂ O ₅ component 0 to 15.0 mol%, and / or WO ₃ component 0 to 15.0 mol%, and / or TeO ₂ component 0 to 10.0 mol%, and / or Tl ₂ O ₃ component 0 to 10.0 mol%, and / or _Sb 2 _{O 3} component 0-3.0 mol%, and / or CeO ₂ component 0 to 10.0 mol%, and / or F component 0 to 10.0 mol%

[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). 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. As a result, an optical glass having a large abnormal partial dispersion (Δθg, F) can be obtained, so that a remarkable effect can be obtained in correcting chromatic aberration of the optical element, and the degree of freedom in optical design can be expanded. 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.

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 460 nm or less, more preferably 455 nm or less, further preferably 440 nm or less, and most preferably 432 nm or less. Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be preferably used as a material for an optical element such as a lens.

The optical glass of the present invention preferably has a high refractive index and high dispersion (low Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.90, more preferably 2.10, still more preferably 2.13, and most preferably 2.15. . 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 about 2.40 or less, more specifically 2.35 or less, and more specifically 2.30 or less. There are many cases. On the other hand, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 27, more preferably 25, and most preferably 20. Here, 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 10 or more, more specifically 12 or more, and more specifically 14 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. 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]
A glass molded body can be produced from the produced optical glass using means 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. The glass molded body made of the optical glass of the present invention can be used for applications of optical elements such as lenses, prisms, and mirrors, and can be typically used for digital cameras and projectors. In addition, the means for producing the glass molded body is not limited to these means.

Compositions of Examples (No. 1 to No. 91) 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 10 show the results of the anomalous partial dispersion (Δθg, F) and the wavelengths (λ ₇₀ , λ ₅ ) showing the spectral transmittances of 70% and 5%. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of Examples (No. 1 to No. 91) 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 10. 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. 91) and Comparative Example (No. 1) are as follows: Measurements were made based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, the abnormal partial dispersion (Δθg, F) representing the magnitude of the deviation from the normal line was determined for the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F). 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, about the transmittance | permeability of the glass of an Example (No.1-No.91) 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, and λ ₅ and λ ₇₀ (wavelengths at 5% and 70% transmittance). )

  As shown in Tables 1 to 10, the optical glasses of the examples of the present invention had a partial dispersion ratio (θg, F) of 0.63 or more, more specifically 0.66 or more. On the other hand, the partial dispersion ratio (θg, F) of the optical glass of the example of the present invention was 0.70 or less, more specifically 0.68 or less. Therefore, it became clear that the optical glass of the example of the present invention has a desired large partial dispersion ratio (θg, F).

  The optical glass of the example of the present invention had an abnormal partial dispersion (Δθg, F) of 0.05 or more. Therefore, it was also revealed that the optical glass of the example of the present invention has a desired large anomalous partial dispersion (Δθg, F).

In addition, in all the optical glasses of the examples of the present invention, λ ₅ (wavelength at 5% transmittance) was 460 nm or less, more specifically, 429 nm or less. Further, in all of the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 600 nm or less, more specifically, 550 nm or less. On the other hand, the glass of the comparative example had a λ ₅ larger than 440 nm. For this reason, it became clear that the optical glass of the Example of this invention was hard to color compared with the glass of a comparative example.

Further, the optical glasses of the examples of the present invention all had a refractive index (n _d ) of 1.90 or more, more specifically 2.09 or more, and were within a desired range. In particular, all of Examples (Nos. 10 to 13, 23, and 27 to 91) had a refractive index (n _d ) of 2.13 or more. The refractive index (n _d ) was 2.40 or less, more specifically 2.18 or less, and was within a desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 10 or more, more specifically 16 or more, and the Abbe number (ν _d ) of 27 or less, more specifically 18 And within the desired range.

Therefore, the optical glass of the example of the present invention has a high refractive index (n _d ) and high dispersion (low Abbe number ν _d ) while having a very large partial dispersion ratio (θg, F), and It became clear that the transparency with respect to the light of the wavelength of visible region was high.

  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 (18)

SiO ₂ component and / or B ₂ O ₃ component is contained, Bi ₂ O ₃ component is contained in an amount of 40.0% to 90.0% by mass% based on oxide, and the partial dispersion ratio (θg, F) is 0.63 or more, refractive index (nd) is 1.90 or more, Abbe number (νd) is 27 or less, and wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is 460 nm or less. Optical glass. _2. The optical glass according to claim 1, comprising 67.0% or more of a Bi ₂ O ₃ component by mass% based on an oxide. _3. The optical glass according to claim 1, wherein the optical glass contains less than 85.0% of a Bi ₂ O ₃ component by mass% based on an oxide. % By mass based on oxide,
SiO ₂ component 0 to 20.0% and / or B ₂ O ₃ component 0 to 30.0%
The optical glass according to any one of claims 1 to 3, comprising each of the following components. 5. The optical glass according to claim 4, wherein the total mass of the SiO ₂ component and the B ₂ O ₃ component is greater than 0% and not greater than 20.0% by mass% based on the oxide. % By mass based on oxide,
TiO ₂ component 0 to 10.0% and / or Nb ₂ O ₅ component 0 to 10.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 6, wherein the total mass of the TiO ₂ component and the Nb ₂ O ₅ component is more than 0% and not more than 15.0% by mass% based on the oxide. % By mass based on oxide,
MgO component 0-20.0%, and / or CaO component 0-20.0%, and / or SrO component 0-20.0%, and / or BaO component 0-20.0%, and / or ZnO component 0 to 20.0%
The optical glass according to claim 1, further comprising:   The mass sum of the RO component (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) is 30.0% or less based on the oxide-based mass%. The optical glass according to claim 8.   On the oxide basis, the mass ratio of the mass sum (SrO + ZnO) to the mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) is The optical glass according to claim 8 or 9, which is 0.40 or more. % By mass based on oxide,
Li ₂ O component 0 to 10.0% and / or Na ₂ O component 0 to 10.0% and / or K ₂ O component 0 to 10.0% and / or Rb ₂ O component 0 to 5. 0%, and / or Cs ₂ O component from 0 to 5.0%
The optical glass according to claim 1, further comprising: The mass sum of the Rn ₂ O component (wherein, Rn is at least one selected from the group consisting of Li, Na, K, Rb, and Cs) is 5.0% or less in terms of mass% based on oxide. The optical glass according to claim 11. % By mass based on oxide,
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 ₃ component 0 to 10.0% and / or Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to claim 1, further comprising: The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) in terms of mass% based on oxide is 20.0% or less. The optical glass according to claim 13. % By mass based on oxide,
GeO ₂ component 0-20.0% and / or P ₂ O ₅ component 0-10.0% and / or Al ₂ O ₃ component 0-10.0% and / or ZrO ₂ component 0-10. 0% and / or Ta ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0 to 10.0% and / or TeO ₂ component 0 to 20.0% and / or Tl ₂ O ₃ components 0 to 10.0% and / or CeO ₂ components 0 to 10.0% and / or Sb ₂ O ₃ components 0 to 3.0%
The optical glass according to claim 1, further comprising:   A preform for polishing and / or precision press molding comprising the optical glass according to claim 1.   An optical element obtained by polishing the preform for polishing according to claim 16.   An optical element obtained by precision press molding the preform for precision press molding according to claim 16.

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