JP2012126586A - Optical glass, preform, and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass preferably used to correct chromatic aberration, while having a refractive index (nd) and an Abbe number (νd) within a desired range, and a lens preform using the same.SOLUTION: The optical glass contains a BOcomponent and an F component, has an Abbe number and a refractive index within the range defined by four points A (50, 1.70), B (60, 1.60), C (63, 1.60) and D (63, 1.70) in xy orthogonal coordinates with Abbe number (νd) as the x axis and refractive index (nd) as the y axis, and shows a partial variance ratio (θg, F) satisfying the relationship of (θg, F) ≥-0.00170×νd+0.6375 between the ratio (θg, F) and Abbe number (νd).

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 the glass having a high refractive index (n _d ) of 1.60 or more and 1.70 or less and a high Abbe number (ν _d ) of 50 or more, for example, as shown in Patent Documents 1 to 4, Optical glass is known.

JP-A-56-096747 JP-A-62-087433 JP-A-11-157868 JP 2006-117504 A

However, the optical glasses of Patent Documents 1 to 4 have a small partial dispersion ratio and are not sufficient for use as a lens for correcting the secondary spectrum. That is, an optical glass having a high partial dispersion ratio (θg, F) while having a high refractive index (n _d ) and a high Abbe number (ν _d ) is required.

The present invention has been made in view of the above problems, and its object is to correct chromatic aberration while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. The object is to obtain a preferably used optical glass and a lens preform using the same.

In order to solve the above-mentioned problems, the present inventors have conducted earnest test research, and as a result, by using the B ₂ O ₃ component and the F component in combination, the low dispersion of the glass is achieved. It has been found that a desired relationship can be obtained with the Abbe number (ν _d ) by increasing the value, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A (50, 1.70), B in xy orthogonal coordinates containing B ₂ O ₃ component and F component, with Abbe number (νd) as x-axis and refractive index (nd) as y-axis (60, 1.60), C (63, 1.60), D (63, 1.70) having an Abbe number and a refractive index in a range surrounded by four points, and a partial dispersion ratio (θg, F ) Satisfies the relationship of (θg, F) ≧ −0.00170 × ν _d +0.6375 with respect to the Abbe number (ν _d ).

(2) the entire mass of the glass in terms of oxide composition, the _B 2 _{O 3} component in weight% containing 5.0 to 55.0%, _La 2 _{O 3} component content is less than 50.0% of The optical glass according to (1).

  (3) The optical glass according to (1) or (2), wherein the optical glass contains an F component in an amount of more than 0% and not more than 30.0% with respect to the oxide-based mass.

(4) The optical glass according to any one of (1) to (3), further containing 40.0% or less of a SiO ₂ component by mass% with respect to the total mass of the glass having an oxide equivalent composition.

(5) Gd ₂ O ₃ component 0 to 30.0% and / or Y ₂ O ₃ component 0 to 20.0% and / or Yb ₂ O _{3 in} mass% with respect to the total glass mass of the oxide equivalent composition. components from 0 to 20.0% and / or _Lu 2 _{O 3} component from 0 to 10.0%
The optical glass according to any one of (1) to (4), further comprising:

(6) 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) with respect to the total glass mass of the oxide equivalent composition is 63.5% or less. The optical glass according to any one of (1) to (5).

(7) The mass sum of Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) with respect to the total glass mass of the oxide equivalent composition is less than 53.0% The optical glass according to (6).

(8) any description of the optical glass of the mass sums for glass total weight of oxide composition in terms of _{(Gd 2 O 3 + Yb 2} O 3) is less than 26.0% (5) to (7).

(9) Bi ₂ O ₃ component 0 to 10.0% and / or TiO ₂ component 0 to 15.0% and / or Nb ₂ O ₅ component 0% by mass with respect to the total glass mass of the oxide equivalent composition 0 ˜20.0% and / or WO ₃ component 0-15.0% and / or K ₂ O component 0-10.0%
The optical glass according to any one of (1) to (8), further comprising:

(10) The optical component according to (9), wherein a mass sum (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) with respect to the total glass mass of the oxide conversion composition is 0.1% or more and 30.0% or less. Glass.

(11) The optical glass according to (9) or (10), wherein the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ ) with respect to the total glass mass of the oxide equivalent composition is 10.0% or less.

(12) The mass ratio F / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide equivalent composition is 0.36 or more and 1.00 or less, and any one of (9) to (11) The optical glass described.

(13) The Ta ₂ O ₅ component 0 to 15.0% and / or the ZrO ₂ component 0 to 15.0% and / or the Li ₂ O component 0 to 0% by mass with respect to the total glass mass of the oxide equivalent composition 15.0%
The optical glass according to any one of (1) to (12), further comprising:

(14) The mass ratio (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide equivalent composition is 2.00 or less (13) Optical glass.

(15) MgO component 0 to 20.0% and / or CaO component 0 to 40.0% and / or SrO component 0 to 40.0% and / Or BaO component 0-55.0%
The optical glass according to any one of (1) to (14), further comprising:

  (16) The mass 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 glass mass of the oxide equivalent composition is 55.0% or less ( 15) The optical glass as described.

(17) The optical glass according to any one of (1) to (16), wherein the content of the Na ₂ O component is 20.0% or less in terms of% by mass with respect to the total mass of the glass having an oxide equivalent composition.

(18) The mass 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 glass mass of the oxide equivalent composition is 25.0% or less ( 17) The optical glass as described.

(19) ZnO component 0 to 25.0% and / or P ₂ O ₅ component 0 to 10.0% and / or GeO ₂ component 0 to 10% by mass with respect to the total glass mass of the oxide equivalent composition. 0% and / or _Al 2 _{O 3} component from 0 to 20.0% and / or _Ga 2 _{O 3} component from 0 to 10.0% and / or TeO ₂ component from 0 to 10.0% and / or SnO ₂ component 0 5.0% and / or Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) to (18), further comprising:

  (20) A preform made of the optical glass according to any one of (1) to (19).

  (21) An optical element produced by press-molding the preform material according to (20).

  (22) An optical element having the optical glass according to any one of (1) to (19) as a base material.

  (23) An optical apparatus comprising the optical element according to any one of (21) and (22).

According to the present invention, an optical glass that is preferably used for correcting chromatic aberration while a refractive index (n _d ) and an Abbe number (ν _d ) are within a desired range, and a preform and an optical element using the optical glass are obtained. be able to.

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

The optical glass of the present invention contains a B ₂ O ₃ component and an F component, and in the xy orthogonal coordinates with the Abbe number (νd) as the x axis and the refractive index (nd) as the y axis, A (50, 1.. 70), B (60, 1.60), C (63, 1.60), D (63, 1.70), having an Abbe number and a refractive index in a range surrounded by four points, and a partial dispersion ratio (Θg, F) satisfies the relationship of (θg, F) ≧ −0.00170 × ν _d +0.6375 with the Abbe number (ν _d ). By using the B ₂ O ₃ component and the F component in combination, a desired relationship can be obtained with the Abbe number (ν _d ) by increasing the partial dispersion ratio while achieving low dispersion of the glass. Therefore, an optical glass that can be preferably used for correcting chromatic aberration while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges, and a preform and an optical element using the optical glass are obtained. Can do.

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

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In this specification, unless there is particular notice, content of each component shall be displayed by the mass% with respect to the glass total mass of an oxide conversion composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

<About essential and optional components>
The B ₂ O ₃ component is a component that forms a network structure inside the glass and promotes stable glass formation. In particular, by making the content of the B ₂ O ₃ component 5.0% or more, it is difficult to devitrify the glass, and a stable glass can be easily obtained. On the other hand, when the content of the B ₂ O ₃ component is 55.0% or less, a desired refractive index and dispersibility can be easily obtained. Therefore, the content of the B ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 5.0%, more preferably 8.0%, and most preferably 10.0%, and preferably 55%. The upper limit is 0.0%, more preferably 50.0%, and most preferably 45.0%. 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 La ₂ O ₃ component is a component that increases the refractive index of the glass and decreases dispersion. In particular, by setting the content of the La ₂ O ₃ component to 55.0% or less, it is possible to suppress the phase separation of the glass and make it difficult to devitrify the glass when producing the glass. Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 55.0%, more preferably 50.0%, and most preferably 45.0%. The lower limit of the content of La ₂ O ₃ component is appropriately set in a range obtained a glass having desired optical properties, by the content of La ₂ O ₃ component in more than 5.0% Further, it is possible to easily obtain a glass having a desired high refractive index and a high Abbe number and a high transmittance for visible light. Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 5.0% as a lower limit, more preferably 10.0%, still more preferably 13.0%, most preferably The lower limit is 15.0%. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like as a raw material.

F component is a component which raises the partial dispersion ratio of glass, and is a component which lowers | hangs the transition point (Tg) of glass. In particular, by containing the F component, it is possible to obtain an optical glass with little coloring while having a high partial dispersion ratio. On the other hand, by setting the content of the F component to 30.0% or less, the stability of the glass can be improved and devitrification can be made difficult. Therefore, the content of the F component on an external basis with respect to the oxide-based mass is preferably more than 0, more preferably more than 0.5%, still more preferably more than 1.0%, and still more preferably. Is more than 2.0%, most preferably more than 3.0%. Further, the content of the F component is preferably 30.0%, more preferably 20.0%, further preferably 15.0%, and most preferably 10.0%. The F component can be contained in the glass using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ , LaF ₃ 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 ceramic are made of an oxide combined with oxygen that balances the charge, and the entire glass made of these oxides. The mass is 100%, and the mass of the F component is represented by mass% (externally divided mass% with respect to the oxide-based mass).

The SiO ₂ component is a component that promotes stable glass formation and suppresses devitrification (generation of crystalline substances) when producing the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the SiO ₂ component to 40.0% or less, the SiO ₂ component can be easily dissolved in the molten glass, and dissolution at a high temperature can be avoided. The content of the SiO ₂ component with respect to the total glass mass of the oxide-converted composition is preferably 40.0%, more preferably 30.0%, more preferably less than 28.0%, still more preferably 25 Less than 0.0%, and most preferably less than 20.0%. Note that even without containing a SiO ₂ component, it is possible to obtain a glass having a desired high partial dispersion ratio, by setting the content of SiO ₂ component to 0.1% or more, the glass denitrification Permeability can be increased. Accordingly, the content of the SiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 1.0%, still more preferably 4.0%, 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.

The Gd ₂ O ₃ component is a component that increases the refractive index of the glass and decreases the dispersion. In particular, by setting the content of the Gd ₂ O ₃ component to 30.0% or less, it is possible to suppress the phase separation of the glass and to make the glass difficult to devitrify when producing the glass. Therefore, the content of the Gd ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably less than 28.0%, still more preferably less than 25.0%, most preferably Less than 20.0%. The Gd ₂ O ₃ component can be contained in the glass using, for example, Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

The Y ₂ O ₃ component, the Yb ₂ O ₃ component, and the Lu ₂ O ₃ component are components that increase the refractive index of the glass and reduce the dispersion. Here, the content of the Y ₂ O ₃ component or the Yb ₂ O ₃ component is set to 20.0% or less, or the content of the Lu ₂ O ₃ component is set to 10.0% or less, thereby reducing the glass. It can be made hard to devitrify. Therefore, the content of the Y ₂ O ₃ component and the Yb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, More preferably, the upper limit is 4.0%. Further, the content of the Lu ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. In particular, the content of the Yb ₂ O ₃ component with respect to the total mass of the glass in an oxide-converted composition from the viewpoint of enhancing the resistance to infrared rays of the glass by making it difficult to absorb on the long wavelength side of the glass (near the wavelength of 1000 nm). Is preferably less than 3.0%, and most preferably less than 1.0%. The Y ₂ O ₃ component, the Yb ₂ O ₃ component, and the Lu ₂ O ₃ component may be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ or the like as a raw material. it can.

In the optical glass of the present invention, the mass sum of the content 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) is 63.5%. The following is preferable. Thereby, the devitrification of the glass at the time of producing glass can be reduced. Therefore, the mass sum of the content of the Ln ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 63.5%, more preferably 60.0%, and even more preferably 55.0%, Most preferably, it is less than 50.0%. The lower limit of the total content of the Ln ₂ O ₃ component is appropriately selected within a range in which an optical glass having desired characteristics can be obtained. For example, by increasing it to more than 10.0%, a desired high refractive index and Abbe The number can be easily obtained, coloring can be reduced, and the photoelastic constant can be reduced. In particular, in the optical glass of the present invention, even if a large amount of rare earth is contained, the partial dispersion ratio does not easily decrease, so that it is easy to achieve both a desired high partial dispersion ratio, a high refractive index, and an Abbe number. Therefore, the mass sum of the content of the Ln ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably more than 10.0%, more preferably more than 15.0%, and still more preferably 16. More than 0%, most preferably more than 20.0%.

In the optical glass of the present invention, the sum of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is preferably 26.0% or less. Thereby, the use of strong Gd ₂ O ₃ component and Yb ₂ O ₃ component of action to increase the refractive index can be suppressed, it is also possible while increasing the partial dispersion ratio is easier to obtain a desired refractive index and dispersion. Accordingly, the mass sum (Gd ₂ O ₃ + Yb ₂ O ₃ ) of the oxide-converted composition with respect to the total glass mass is preferably 26.0%, more preferably 23.0%, still more preferably 20.0%, and most preferably The upper limit is 15.0%.

The Bi ₂ O ₃ component is a component that increases the partial dispersion ratio of the glass, is a component that increases the refractive index of the glass and lowers the glass transition point, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, it is possible to make it difficult to deteriorate the light transmittance at a visible short wavelength (500 nm or less). Therefore, the content of the Bi ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The TiO ₂ component is a component that increases the partial dispersion ratio of the glass, is a component that increases the refractive index and dispersion of the glass, and improves the chemical durability of the glass, and is an optional component in the optical glass of the present invention. is there. In particular, by making the content of the TiO ₂ component 15.0% or less, a desired high Abbe number can be easily obtained, and the light transmittance at a visible short wavelength (500 nm or less) can be made difficult to deteriorate. . Therefore, the upper limit of the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. 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 component that increases the partial dispersion ratio of the glass, is a component that increases the refractive index and dispersion of the glass, and improves the chemical durability of the glass, and is optional in the optical glass of the present invention. It is an ingredient. In particular, when the content of the Nb ₂ O ₅ component is 20.0% or less, a desired high Abbe number can be easily obtained. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The WO ₃ component is a component that increases the partial dispersion ratio of the glass, is a component that increases the refractive index and dispersion of the glass, and improves the chemical durability of the glass, and is an optional component in the optical glass of the present invention. is there. In particular, by making the content of the WO ₃ component 15.0% or less, a desired high Abbe number can be easily obtained, and the light transmittance at a visible short wavelength (500 nm or less) can be made difficult to deteriorate. . Therefore, the upper limit of the content of the WO ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The K ₂ O component is a component that further increases the partial dispersion ratio of the glass and improves the meltability of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the K ₂ O component to 10.0% or less, the refractive index of the glass is hardly lowered, the stability of the glass is increased, and devitrification and the like are hardly caused. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide-converted composition is 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.

In the optical glass of the present invention, the sum of the contents of F component, Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component, Nb ₂ O ₅ component and K ₂ O component is 0.1% or more and 30.0% or less. It is preferable that In particular, by setting this sum to 0.1% or more, a component that increases the partial dispersion ratio is essential, so that a glass having a desired high partial dispersion ratio can be obtained. Accordingly, the mass sum (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 1.0%, and still more preferably. The lower limit is 3.0%, and most preferably 4.0%. On the other hand, by making this sum 30.0% or less, the devitrification resistance of the glass can be further improved. Accordingly, the mass sum (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 25.0%, most preferably The upper limit is 20.0%.

In the optical glass of the present invention, the sum of the contents of Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component and Nb ₂ O ₅ component is preferably 10.0% or less. Thereby, since the component which raises dispersion | distribution is reduced, the glass which has desired dispersion | distribution can be obtained easily. Moreover, since the fall of stability of glass by excessive inclusion of these components is suppressed, the devitrification resistance of glass can be improved further. Therefore, the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ ) with respect to the total glass mass of the oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0. % Is the upper limit. Note that this mass sum may be less than 0.5% from the viewpoint of obtaining a glass with particularly small dispersion.

In the optical glass of the present invention, the content ratio of the F component to the sum of the contents of the F component, Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component, Nb ₂ O ₅ component, and K ₂ O component is It is preferable that it is 0.36 or more. In particular, by setting this ratio to 0.36 or more, a large amount of less colored components are contained while increasing the partial dispersion ratio, so that a transparent glass having a desired partial dispersion ratio can be obtained. Therefore, the mass ratio F / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide equivalent composition is preferably 0.36, more preferably 0.40, and still more preferably 0.50. The lower limit. The mass ratio is most preferably 1.00, but may be less than 1.00 from the viewpoint of obtaining a more stable glass.

The Ta ₂ O ₅ component is a component that stabilizes the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Ta ₂ O ₅ component 15.0% or less, it is possible to suppress a decrease in the partial dispersion ratio of the glass. Further, by setting the content of Ta ₂ O ₅ component below 15.0%, while reducing the material cost of the glass, it is possible to reduce the energy loss during the glass production to avoid dissolution at a high temperature . Therefore, the content of the Ta ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

ZrO ₂ component increases the refractive index of the glass is a component to improve the devitrification resistance of making the glass, are optional components in the optical glass of the present invention. In particular, by setting the content of the ZrO ₂ component to 15.0% or less, it is possible to suppress a decrease in the partial dispersion ratio of the glass. In addition, by reducing the ZrO ₂ component content to 15.0% or less, it is possible to suppress the glass Abbe number from being lowered, avoid melting at a high temperature during glass production, and reduce energy loss during glass production. can do. Therefore, the content of the ZrO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 7.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

Li 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by reducing the content of the Li ₂ O component to 15.0% or less, a reduction in the partial dispersion ratio of the glass can be suppressed. Moreover, by setting the content of the Li ₂ O component to 15.0% or less, devitrification or the like due to excessive inclusion of the Li ₂ O component can be made difficult to occur while suppressing a decrease in the refractive index of the glass. Therefore, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably Less than 3.0%. In particular, from the viewpoint of obtaining an optical glass having a high partial dispersion ratio, the content of this Li ₂ O component is most preferably 0.4% or less. 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 optical glass of the present invention comprises a Ta ₂ O ₅ component and a ZrO ₂ component with respect to the sum of the contents of the F component, Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component, Nb ₂ O ₅ component and K ₂ O component. And the ratio of the sum of the contents of the Li ₂ O component is preferably 2.00 or less. As a result, the content of the component having the effect of lowering the partial dispersion ratio is reduced relative to the component having the action of raising the partial dispersion ratio, so that a glass having a higher partial dispersion ratio can be obtained. . Therefore, the mass ratio (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide equivalent composition is preferably 2.00, more preferably 1 .40, more preferably 1.00, and most preferably 0.80. In addition, although this mass ratio may be 0, the devitrification resistance of glass can be further improved by making this mass ratio 0.10 or more. Therefore, the mass ratio (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide equivalent composition is preferably 0.10, more preferably 0. .20, most preferably 0.30.

The MgO component, CaO component, SrO component, and BaO component are components that improve the meltability of the glass and increase the devitrification resistance, and are optional components in the optical glass of the present invention. In particular, when the content of the MgO component is 20.0% or less, the content of the CaO component or SrO component is 40.0% or less, or the content of the BaO component is 55.0% or less, the refraction of the glass The rate can be made difficult to decrease. Therefore, the content of the MgO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. Further, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 40.0%, more preferably 30.0%, further preferably 25.0%, and further preferably 20.0%. And most preferably less than 10.0%. Further, the content of the SrO component with respect to the total glass mass of the oxide-converted composition is preferably 40.0%, more preferably 30.0%, further preferably 25.0%, and further preferably 20.0%. And most preferably less than 16.0%. Further, the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 55.0%, more preferably 45.0%, and most preferably 40.0%, and most preferably 30. Less than 0%. The MgO component, CaO component, SrO component and BaO component use, for example, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) _{2 and the} like as raw materials. Can be contained in the glass.

  In the optical glass of the present invention, the mass sum of the content of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 55.0% or less. preferable. Thereby, the devitrification of the glass due to excessive inclusion of the RO component can be reduced, and the refractive index of the glass can be made difficult to decrease. Therefore, the upper limit of the mass sum of the content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 55.0%, more preferably 45.0%, and most preferably 40.0%.

Na 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by making the content of the Na ₂ O component 10.0% or less, the refractive index of the glass is hardly lowered, the stability of the glass is increased, and devitrification and the like are hardly caused. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, and most preferably 5.0%. Is the upper limit. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

The Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) improves the meltability of the glass, lowers the glass transition point, and reduces the devitrification of the glass. It is an ingredient. Here, by making the content of the Rn ₂ O component 25.0% or less, the refractive index of the glass is hardly lowered, the stability of the glass is increased, and the occurrence of devitrification and the like can be reduced. Therefore, the upper limit of the mass sum of the Rn ₂ O component with respect to the total mass of the glass in oxide conversion composition is preferably 25.0%, more preferably 20.0%, and most preferably 15.0%.

The ZnO component is a component that improves the meltability of the glass, lowers the glass transition point, and easily forms a stable glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the ZnO component 25.0% or less, the photoelastic constant of the optical glass can be kept low. Therefore, the polarization characteristics of the transmitted light of the optical glass can be improved, and as a result, the color rendering properties of the projector and camera can be improved. Therefore, the content of the ZnO component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, further preferably 15.0%, further preferably 10.0%, most preferably Preferably, the upper limit is 7.7%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The GeO ₂ component is a component having an effect of increasing the refractive index of the glass and improving the devitrification resistance, and is an optional component in the optical glass of the present invention. However, since GeO ₂ has a high raw material price, the material cost increases when the amount of GeO ₂ is large, and the resulting glass becomes impractical. Therefore, the content of the GeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

P ₂ O ₅ component is a component having an effect of improving resistance to devitrification and lower the liquidus temperature of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress a decrease in chemical durability, particularly water resistance, of the glass. Therefore, the content of the P ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material. .

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are components that facilitate the formation of stable glass, and are optional components in the optical glass of the present invention. In particular, when the content of the Al ₂ O ₃ component is 20.0% or less and the content of the Ga ₂ O ₃ component is 10.0% or less, a decrease in the Abbe number of the glass can be suppressed. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. Further, the content of the Ga ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The Al ₂ O ₃ component and the Ga ₂ O ₃ component should be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) _3, etc. as raw materials. Can do.

Ga ₂ O ₃ component is a component to facilitate forming a stable glass, are optional components of the optical glass of the present invention. In particular, the decrease in the Abbe number of the glass can be suppressed by setting the content of the Ga ₂ O ₃ component to 10.0% or less. Therefore, the content of the Ga ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. Ga ₂ O ₃ component may be contained in the glass by using as the starting material for example _{Ga 2 O 3, Ga (OH} ) 3 and the like.

The TeO ₂ component is a component that raises the refractive index and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. However, TeO ₂ has a problem that it can be alloyed with platinum when melting a glass raw material in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Therefore, the content of the TeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The SnO ₂ component is a component that reduces the oxidation of the molten glass to clarify the molten glass and makes it difficult to deteriorate the transmittance of the glass against light irradiation, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the SnO ₂ component to 5.0% or less, it is possible to make it difficult to cause glass coloring or glass devitrification due to reduction of the molten glass. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.5%. Each is the upper limit. The SnO ₂ component can be contained in the glass using, for example, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like as a raw material.

The Sb ₂ O ₃ component is a component that defoams the molten glass and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, excessive foaming at the time of melting the glass can be made difficult, and the Sb ₂ O ₃ component can be dissolved in a melting facility (especially a noble metal such as Pt). ) And alloying can be made difficult. Therefore, the upper limit of the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 0.8%, and most preferably 0.5%. The Sb ₂ O ₃ component can be contained in the glass using, for example, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O, or the like as a raw material.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer or a combination thereof.

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

If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass of the present invention are not impaired. However, it is preferable that the GeO ₂ component is not substantially contained since it increases the dispersibility of the glass.

  In addition, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, except Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is independent of each other. Or, even when it is contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. .

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

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component 10.0～75.0Mol%
And _La 2 _{O 3} component 0～25.0Mol% and / or SiO ₂ component 0～70.0Mol% and / or _Gd 2 _{O 3} component 0～15.0Mol% and / or _Y 2 _{O 3} component 0-15. 0 mol% and / or Yb ₂ O ₃ component 0 to 10.0 mol% and / or Lu ₂ O ₃ component 0 to 10.0 mol% and / or Bi ₂ O ₃ component 0 to 4.0 mol% and / or TiO ₂ component 0～30.0Mol% and / or _Nb 2 _{O 5} component 0～10.0Mol% and / or WO ₃ components 0～10.0Mol% and / or _{K 2} O ingredient 0～15.0Mol% and / or Ta ₂ O ₅ component 0～3.0Mol% and / or ZrO ₂ component 0～25.0Mol% and / or Li ₂ O component 0～40.0Mol% and / or MgO component 0～50.0Mol% and Or CaO component 0～50.0Mol% and / or SrO component 0～50.0Mol% and / or BaO component 0～55.0Mol% and / or Na ₂ O component 0～25.0Mol% and / or ZnO component 0 ˜25.0 mol% and / or P ₂ O ₅ component 0 to 10.0 mol% and / or GeO ₂ component 0 to 20.0 mol% and / or Al ₂ O ₃ component 0 to 20.0 mol% and / or Ga ₂ O ₃ component 0-8.0 mol% and / or TeO ₂ component 0-8.0 mol% and / or SnO ₂ component 0-5.0 mol% and / or Sb ₂ O ₃ component 0-0.5 mol%
In addition, the total amount as F of the fluoride substituted with one or more oxides of one or more of the above metal elements as more than 0 mol% to 75.0 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 into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 900 to 1400 ° C. for 1 to 5 hours, stir to homogenize, blow out bubbles, etc., then lower the temperature to 1200 ° C. or lower and then stir to finish This is produced by removing the striae and molding using a mold. Here, as means for obtaining glass molded using a mold, means for drawing molten glass from the other end of the mold at the same time as flowing the molten glass to one end of the mold, or molten glass Means for casting into a mold and slow cooling.

[Physical properties]
The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, A (50, 1.70), B (60, 1.60), C in xy orthogonal coordinates with the Abbe number (νd) as the x axis and the refractive index (nd) as the y axis. It has an Abbe number and a refractive index in a range surrounded by four points (63, 1.60) and D (63, 1.70). 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. Here, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.50, more preferably 1.51, and most preferably 1.52. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably less than 1.70, and most preferably 1.69. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 50, more preferably 52, and most preferably 53. On the other hand, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but is generally 63 or less, more specifically 61 or less, and more specifically 60 or less in many cases. Further, the Abbe number (ν _d ) of the optical glass of the present invention preferably satisfies the relationship of (ν _d ) ≧ (−100 × n _d +220) with respect to the refractive index (n _d ). it is more preferable to satisfy the relationship _{d) ≧ (-100 × n d} +222), it is most preferable to satisfy the relation of _{(ν d) ≧ (-100 ×} n d +223).

Moreover, 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 (θg, F) ≧ (−0...) In the range of ν _d ≦ 25 with respect to the Abbe number (ν _d ). ₍ 00170 × ν _d +0.6375) is satisfied. Thereby, an optical glass having a higher partial dispersion ratio (θg, F) than a conventionally known glass containing a large amount of rare earth element components can be obtained. Therefore, chromatic aberration of an optical element formed from the optical glass can be reduced while achieving high refractive index and low dispersion of the glass. Here, the lower limit of the partial dispersion ratio (θg, F) of the optical glass is preferably (−0.00170 × ν _d +0.6375), more preferably (−0.00170 × ν _d +0.6395), most preferably Preferably, it is (−0.00170 × ν _d +0.6415). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is not particularly limited, but is generally (−0.00170 × ν _d +0.6575), more specifically (−0 .00170 × ν _d +0.6555), more specifically (−0.00170 × ν _d +0.6535) in many cases. In addition, since the preferable range of the partial dispersion ratio in this invention changes with the Abbe number of optical glass, it represented using the straight line parallel to a normal line.

  The partial dispersion ratio (θg, F) of the optical glass of the present invention is measured based on Japanese Optical Glass Industry Association Standard JOGIS01-2003. In addition, the glass used for this measurement uses what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

  The optical glass of the present invention preferably has a glass transition point (Tg) of 650 ° C. or lower. As a result, press molding at a lower temperature is possible, so that the oxidation of the mold used for mold press molding can be reduced to extend the life of the mold. Therefore, the upper limit of the glass transition point (Tg) of the optical glass of the present invention is preferably 650 ° C., more preferably 620 ° C., and most preferably 600 ° C. The lower limit of the glass transition point (Tg) of the optical glass of the present invention is not particularly limited, but the glass transition point (Tg) of the glass obtained by the present invention is generally 100 ° C. or higher, specifically 150 ° C. or higher. More specifically, it is often 200 ° C. or higher.

  The glass transition point (Tg) of the optical glass of the present invention is determined by performing measurement using a differential heat measuring device (STA 409 CD manufactured by Netchgeretebau). Here, the sample particle size at the time of measurement is set to 425 to 600 μm, and the heating rate is set to 10 ° C./min.

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 500 nm or less, more preferably 480 nm or less, and most preferably. Is 450 nm or less. In the optical glass of the present invention, a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is 450 nm or less, more preferably 430 nm or less, and most preferably 410 nm or less. Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be used as a material for an optical element such as a lens.

The transmittance of the optical glass of the present invention is measured according to Japan Optical Glass Industry Association Standard JOGIS02. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₇₀ (wavelength at 70% transmittance) and λ ₅ (transmittance). (Wavelength at 5%).

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

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

Composition of Examples (No. 1 to No. 6) and Comparative Example (No. 1) of the present invention, and refractive index (n _d ) and Abbe number (ν _d ) and partial dispersion ratio (θg) of these glasses , F) are shown in Table 1. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 6) of the present invention and the glass of Comparative Example (No. 1) are all oxides, hydroxides, carbonates and nitrates corresponding to raw materials of the respective components. Select high-purity raw materials used in ordinary optical glass such as fluorides, hydroxides, and metaphosphate compounds, and weigh them to the proportions of the examples and comparative examples shown in Table 1. After uniformly mixing, after putting into a platinum crucible, after melting for 1 to 6 hours in a temperature range of 1000 to 1400 ° C. in an electric furnace according to the melting difficulty of the glass composition, stirring and homogenizing to blow out bubbles, etc. The temperature was lowered to 1200 ° C. or lower, and the mixture was stirred and homogenized, then cast into a mold and slowly cooled to produce a glass.

Here, the refractive index (n _d ) and Abbe number (ν _d ) and partial dispersion ratio (θg, F) of the glass of Examples (No. 1 to No. 6) 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 relational expression (θg, F) = − a × ν _d + b when the slope a is −0.0017 The intercept b was determined. Moreover, the value of the relational expression −100 × n _d +220 was obtained for the obtained refractive index (n _d ) value. 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.

In the optical glass of the example of the present invention, the partial dispersion ratio (θg, F) is (−0.00170 × ν _d +0.6375) or more, more specifically (−0.00170 × ν _d +0.64486). That was all. Therefore, it has been clarified that the optical glass of the example of the present invention has a large partial dispersion ratio (θg, F) in the relational expression with the Abbe number (ν _d ) and small chromatic aberration when the optical element is formed. .

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.60 or more, more specifically 1.65 or more, and this refractive index (n _d ) is 1.70 or less. And within the desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 50 or more, more specifically 54 or more, and the Abbe number (ν _d ) of 63 or less, more specifically It was 57 or less, and was within the desired range.

Further, in the optical glass of the example of the present invention, the Abbe number (ν _d ) of the optical glass of the present invention is (ν _d ) ≧ (−100 × n _d +220) between the refractive index (n _d ). Met the relationship.

Therefore, the optical glass of the embodiment of the present invention has low refractive index (n _d ) and Abbe number (ν _d ) within a desired range, and has low chromatic aberration and high transparency to light in the visible wavelength range. Became clear.

  Furthermore, using the optical glass obtained in the example of the present invention, after performing reheat press molding, grinding and polishing were performed to process into the shape of a lens and a prism. Further, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded. In either case, the glass after heat softening did not cause problems such as opacification and devitrification, and could be stably processed into various lens and prism shapes.

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

Claims (23)

It contains B ₂ O ₃ component and F component, and A (50, 1.70) and B (60, 60) in xy orthogonal coordinates with Abbe number (νd) as x-axis and refractive index (nd) as y-axis 1.60), C (63, 1.60), and D (63, 1.70). The Abbe number and refractive index are in the range surrounded by four points, and the partial dispersion ratio (θg, F) is Abbe. An optical glass satisfying the relationship (θg, F) ≧ −0.00170 × ν _d +0.6375 with respect to the number (ν _d ). Claim the entire mass of the glass in terms of oxide composition, containing from 5.0 to 55.0% of _B 2 _{O 3} component in mass%, the content of _La 2 _{O 3} component is less 50.0% 1. The optical glass according to 1.   The optical glass according to claim 1 or 2, which contains an F component in an amount of more than 0% and not more than 30.0% by mass based on an oxide based mass. The optical glass according to any one of claims 1 to 3, further comprising 40.0% or less of a SiO ₂ component in terms of% by mass relative to the total mass of the glass having an oxide equivalent composition. The entire mass of the glass in terms of oxide composition, 0~30.0% _Gd 2 _{O 3} component in% by weight and / or _Y 2 _{O 3} component from 0 to 20.0% and / or _Yb 2 _{O 3} component 0 20.0% and / or Lu ₂ O ₃ component 0-10.0%
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) with respect to the total glass mass of the oxide equivalent composition is 63.5% or less Item 6. The optical glass according to any one of Items 1 to 5. Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) with respect to the total glass mass of the oxide equivalent composition is less than 53.0% Item 7. The optical glass according to Item 6. 8. The optical glass according to claim 5, wherein a mass sum (Gd ₂ O ₃ + Yb ₂ O ₃ ) with respect to the total glass mass of the oxide conversion composition is 26.0% or less. Bi ₂ O ₃ component 0 to 10.0% and / or TiO ₂ component 0 to 15.0% and / or Nb ₂ O ₅ component 0 to 20% by mass with respect to the total glass mass of the oxide equivalent composition. 0% and / or WO ₃ component 0 to 15.0% and / or K ₂ O component 0 to 10.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 9, wherein a mass sum (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) with respect to the total mass of the glass in terms of oxide is 0.1% or more and 30.0% or less. 11. The optical glass according to claim 9, wherein a mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ ) with respect to the total glass mass of the oxide conversion composition is 10.0% or less. The optical glass according to any one of claims 9 to 11, wherein a mass ratio F / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in an oxide equivalent composition is 0.36 or more and 1.00 or less. Ta ₂ O ₅ component 0 to 15.0% and / or ZrO ₂ component 0 to 15.0% and / or Li ₂ O component 0 to 15.0 by mass% with respect to the total glass mass of the oxide conversion composition %
The optical glass according to claim 1, further comprising: 14. The optical glass according to claim 13, wherein a mass ratio (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) / (F + Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + K ₂ O) in the oxide-converted composition is 2.00 or less. . MgO component 0 to 20.0% and / or CaO component 0 to 40.0% and / or SrO component 0 to 40.0% and / or BaO component in mass% with respect to the total mass of the glass in oxide conversion composition 0-55.0%
The optical glass according to claim 1, further comprising:   The mass 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 glass mass of the oxide equivalent composition is 55.0% or less. Optical glass. The optical glass according to any one of claims 1 to 16, wherein the content of the Na ₂ O component is 20.0% or less in terms of% by mass relative to the total glass mass of the oxide equivalent composition. The mass 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 glass mass of the oxide equivalent composition is 25.0% or less. Optical glass. ZnO component 0 to 25.0% and / or P ₂ O ₅ component 0 to 10.0% and / or GeO ₂ component 0 to 10.0% by mass% with respect to the total glass mass of the oxide conversion composition / Or Al ₂ O ₃ component 0 to 20.0% and / or Ga ₂ O ₃ component 0 to 10.0% and / or TeO ₂ component 0 to 10.0% and / or SnO ₂ component 0 to 5.0 % And / or Sb ₂ O ₃ component 0-1.0%
The optical glass according to claim 1, further comprising:   A preform material comprising the optical glass according to claim 1.   An optical element produced by press-molding the preform material according to claim 20.   An optical element using the optical glass according to claim 1 as a base material.   An optical apparatus comprising the optical element according to claim 21.

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