JP2013126935A - Optical glass, perform, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass, which is used preferably for correction of chromatic aberration and can contribute to weight reduction of an optical device, though having a refractive index (n) and an Abbe number (ν) in desired ranges; and to provide a lens perform using the same.SOLUTION: The optical glass contains, with respect to the total amount of the glass in terms of oxide composition, in mass%, 5.0 to 55.0% of a BOcomponent, 10.0 to 55.0% of a LaOcomponent, and further a YOcomponent and an F component. The lens perform is constituted of the optical glass.

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 a glass having a high refractive index (n _d ) of 1.68 or more and a high Abbe number (ν _d ) of 40 or more, for example, La ₂ O ₃ as disclosed in Patent Documents 1 to 7 is used. Optical glasses containing a large amount of rare earth elements such as components are known.

JP-A-55-003329 Japanese Patent Laid-Open No. 57-034044 JP 59-169952 A Japanese Patent Laid-Open No. 03-016932 JP 2006-117503 A JP 2005-170782 A JP 2007-269584 A

However, the optical glasses of Patent Documents 1 to 7 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.

  Moreover, the glass disclosed by patent documents 1-7 had the problem that the specific gravity of glass is large and the mass of an optical element is large. That is, when these glasses are used in optical devices such as cameras and projectors, there is a problem that the mass of the entire optical device tends to increase.

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. An object of the present invention is to obtain an optical glass that can be preferably used and contribute to weight reduction of an optical device, and a lens preform using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and research. As a result, the Y ₂ O ₃ component and the F component are used in combination with the B ₂ O ₃ component and the La ₂ O ₃ component. Even if it contains a rare earth element component such as La ₂ O ₃ component that has a strong effect of increasing the specific gravity of the glass and a strong effect of reducing the partial dispersion ratio of the glass, while achieving a high refractive index and low dispersion of It has been found that the partial dispersion ratio is increased and the specific gravity of the glass is reduced, and the present invention has been completed. Specifically, the present invention provides the following.

(1) 5.0 to 55.0% of B ₂ O ₃ component and 10.0 to 55.0% of La ₂ O ₃ component in mass% with respect to the total glass mass of oxide conversion composition, An optical glass further containing a Y ₂ O ₃ component and an F component.

(2) The optical glass according to (1), which contains 0.1% or more and 50.0% or less of a Y ₂ O ₃ component by mass% with respect to the total mass of the glass having an oxide equivalent composition.

  (3) The optical glass according to (1) or (2), which contains 0.1% or more and 30.0% or less of an F component in an externally divided mass% with respect to the oxide-based mass.

(4) as oxide entire mass of the glass composition, the content of SiO ₂ component is less than 40.0% by mass% (1) to (3) any description of the optical glass.

(5) Gd ₂ O ₃ component 0 to 40.0% and / or Yb ₂ O ₃ component 0 to 20.0% and / or Lu ₂ O _{3 in} mass% with respect to the total glass mass of the oxide equivalent composition. Ingredient 0-10.0%
The optical glass according to any one of (1) to (4), further comprising:

(6) 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, and Lu) with respect to the total glass mass of the oxide equivalent composition is 38.0. % To 70.0% of the optical glass according to any one of (1) to (5).

(7) mass ratio _Y 2 _O oxide composition in terms of ₃ / _Ln 2 _O 3 is 0.100 or more (6) The optical glass according.

(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% (1) 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 glass according to (9), wherein a mass sum (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ + WO ₃ ) with respect to the total glass mass of the oxide equivalent composition is 0.1% or more.

(11) The mass ratio (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ + WO ₃ ) / (La ₂ O ₃ + Gd ₂ O ₃ ) of the oxide equivalent composition is 0.010 or more (9) or (10) Optical glass.

(12) 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 1.0% or more and 30.0% or less (1) to (11 ) Any one of the optical glasses.

(13) ZrO ₂ component 0 to 15.0% and / or Ta ₂ O ₅ component 0 to 15.0% and / or Li ₂ O component 0 to 0% by mass with respect to the total glass mass of the oxide equivalent composition 5.0%
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 1.30 or less (1) To (13).

(15) Any one of (1) to (14), wherein the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ ) of the oxide equivalent composition with respect to the total glass mass is 0.1% or more The optical glass described.

(16) 0 to 10.0% of MgO component and / or 0 to 25.0% of CaO component and / or 0 to 25.0% of SrO component and / or% by mass with respect to the total glass mass of the oxide equivalent composition. Or BaO component 0-55.0%
The optical glass according to any one of (1) to (15), further comprising:

  (17) 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 ( 16) The optical glass as described.

(18) The optical glass according to any one of (1) to (17), wherein the content of the Na ₂ O component is 10.0% by mass or less with respect to the total glass mass of the oxide equivalent composition.

(19) 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 ( 18) The optical glass described.

(20) ZnO component 0 to 25.0% and / or GeO ₂ component 0 to 10.0% and / or P ₂ O ₅ 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 0 to 10.0% 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 to 1.0%
The optical glass according to any one of (1) to (19), further comprising:

(21) The optical glass according to any one of (1) to (20), having a refractive index (n _d ) of 1.68 or more and an Abbe number (ν _d ) of 45 or more.

(22) The optical glass according to any one of (1) to (21), wherein the Abbe number (ν _d ) satisfies a relationship of ν _d ≧ −100 × n _d +220 with respect to the refractive index (n _d ).

(23) The partial dispersion ratio (θg, F) satisfies the relationship (θg, F) ≧ (−0.00170 × ν _d +0.63750) with the Abbe number (ν _d ) from (1) to (22 ) Any one of the optical glasses.

  (24) The optical glass according to any one of (1) to (23), having a specific gravity of 5.00 or less.

  (25) A preform material comprising the optical glass according to any one of (1) to (24).

  (26) An optical element produced by press-molding the preform material according to (25).

  (27) An optical element having the optical glass according to any one of (1) to (24) as a base material.

  (28) An optical apparatus comprising the optical element according to any one of (26) or (27).

According to the present invention, an optical glass that is preferably used for correction of chromatic aberration and can contribute to weight reduction of an optical device while the refractive index (n _d ) and the Abbe number (ν _d ) are within a desired range; A preform and an optical element using the same can be obtained.

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

The optical glass of the present invention, the entire mass of the glass in terms of oxide composition, 5.0 to 55.0% of _B 2 _{O 3} component in mass%, a _La 2 _{O 3} component from 10.0 to 55.0 %, And further contains a Y ₂ O ₃ component and an F component. By containing the B ₂ O ₃ component and the La ₂ O ₃ component in a predetermined content range, the refractive index of the glass is increased, dispersion is reduced, and transparency to visible light is increased. Even when a rare earth element component such as an La ₂ O ₃ component having a strong effect of lowering the partial dispersion ratio is contained by using the F component in combination with the B ₂ O ₃ component and the La ₂ O ₃ component, the partial dispersion ratio (θg , F). Furthermore, by containing the Y ₂ O ₃ component, an increase in the specific gravity of the glass can be suppressed even if a rare earth element component such as a La ₂ O ₃ component that has a strong action of increasing the specific gravity is contained. For this reason, an optical glass that can be preferably used for correcting chromatic aberration while having a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, and that can contribute to weight reduction of an optical device, and A preform and an optical element using can be obtained.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be suitably abbreviate | omitted 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” is assumed when the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass constituent 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 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 decrease in the refractive index can be suppressed, so that a desired refractive index and dispersion 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 10.0%, and most preferably 15.0%, and preferably 55%. The upper limit is 0.0%, more preferably 40.0%, and most preferably less than 35.0%. 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 making the content of the La ₂ O ₃ component 10.0% or more, it is easy to obtain a glass having a desired high refractive index and a high Abbe number and a high transmittance for visible light. it can. On the other hand, by making the content of the La ₂ O ₃ component 55.0% or less, it is difficult to devitrify the glass and an increase in the specific gravity of the glass can be suppressed. Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0% as a lower limit, more preferably more than 15.0%, and even more preferably 20.0%, Most preferably, the lower limit is 25.0%, preferably 55.0%, more preferably 50.0%, and most preferably 45.0%. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like as a raw material.

The Y ₂ O ₃ component is a component that increases the refractive index of the glass to reduce the dispersion and decreases the specific gravity of the glass. In particular, by containing the Y ₂ O ₃ component, it is possible to easily obtain an optical glass having a desired high refractive index and a high Abbe number and a small specific gravity. Therefore, the content of the Y ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably 0.1% as a lower limit, further preferably more than 5.0%, and still more preferably. Over 10.0%, most preferably over 15.0%. On the other hand, it is possible to make the glass difficult to devitrify by setting the content of the Y ₂ O ₃ component to 30.0% or less. Therefore, the content of the Y ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 50.0%, more preferably 40.0%, and most preferably 30.0%. The Y ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ or the like as a raw material.

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. Therefore, the content of the F component on an external basis with respect to the mass based on the oxide is preferably more than 0%, more preferably 0.1% as a lower limit, more preferably more than 1.0%, still more preferably 3. More than 0%, more preferably more than 5.0%, most preferably more than 8.0%. On the other hand, by making the content of the F component 30.0% or less, it is possible to suppress an increase in the specific gravity of the glass and to make the glass difficult to devitrify. Therefore, the content of the F component in an outer ratio with respect to the mass based on the oxide is preferably 30.0%, more preferably 20.0%, and still more 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 the cation components constituting the glass are made of an oxide combined with oxygen that balances the charge, and the total mass of the glass made of these oxides. Is 100%, and the mass of the F component is expressed in 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 20.0%, most preferably 10.0. %. 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 2.3%, and even more preferably 3. Over 0%, most preferably over 5.0%. 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 making the content of the Gd ₂ O ₃ component 40.0% or less, it is possible to suppress an increase in the specific gravity of the glass, suppress a decrease in the partial dispersion ratio of the glass, and make the glass difficult to devitrify. it can. Therefore, the content of the Gd ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 40.0%, more preferably 30.0%, and even more preferably less than 25.0%, even more preferably Is less than 20.0%, most preferably less than 15.0%. 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 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, by making the content of the Yb ₂ O ₃ component 20.0% or less, or making the content of the Lu ₂ O ₃ component 10.0% or less, making the glass difficult to devitrify. Can do. In particular, by making the content of the Yb ₂ O ₃ component 10.0% or less, it becomes difficult for absorption to occur on the long wavelength side of the glass (near the wavelength of 1000 nm). it can. Therefore, the content of the Yb ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and even more preferably 5.0%. Here, the content of the Yb ₂ O ₃ component may be less than 1.0%. 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 8.0%, and most preferably 5.0%. The Yb ₂ O ₃ component and the Lu ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ , Lu ₂ O ₃ or the like as a raw material.

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 38.0%. It is preferably 70.0% or less. Here, by setting this mass sum to 38.0% or more, it is possible to easily obtain a desired high refractive index and Abbe number, to reduce coloring, and to reduce the photoelastic constant. 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. On the other hand, by setting the mass sum to 70.0% or less, devitrification of the glass when the glass is produced 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 38.0%, more preferably 43.0%, still more preferably 45.0%, most preferably The lower limit is 48.0%, preferably 70.0%, more preferably 68.0%, and most preferably 67.0%.

In the optical glass of the present invention, the ratio of the content of the Y ₂ O ₃ component to the total amount of the Ln ₂ O ₃ component is preferably 0.10 or more. Thereby, the specific gravity of the optical glass can be lowered while obtaining a high refractive index and Abbe number. Therefore, the mass ratio Y ₂ O ₃ / Ln ₂ O ₃ of the oxide equivalent composition is preferably 0.100, more preferably 0.150, and most preferably 0.200. Note that the upper limit of the mass ratio Y ₂ O ₃ / Ln ₂ O ₃ of the oxide equivalent composition is approximately 0.800 or less, more specifically 0.600 or less, and more specifically 0.500 or less. There are many.

In the optical glass of the present invention, the sum of the contents of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is preferably 26.0% or less. Accordingly, since the content of easily Gd ₂ O ₃ component and Yb ₂ O ₃ component increases the specific gravity of the glass is reduced, can easily obtain a more small specific gravity glass. Moreover, since content of these components which are easy to lower | hang the partial dispersion ratio of glass is reduced, it can be easy to obtain glass with a larger partial dispersion ratio. Therefore, the mass sum (Gd ₂ O ₃ + Yb ₂ O ₃ ) with respect to the total glass mass of the oxide conversion composition is preferably 26.0%, more preferably 20.0%, and most preferably 15.0%. To do.

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 conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. 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 decreases the specific gravity of the glass, and is an optional component in the optical glass of the present invention. 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 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%, still more preferably 7.0%, and most preferably 5.0%. The upper limit. 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 decreases the specific gravity of the glass, and is an optional component in the optical glass of the present invention. . 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%. Incidentally, Nb ₂ O ₅ component may not contain, but viewpoint of easier to obtain a more small specific gravity glass preferably contains Nb ₂ O ₅ component. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably 0.1%, still more preferably 0.5%, most preferably 0.7%. Is the lower limit. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The 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. . Accordingly, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 12.0%, still more preferably 10.0%, and most preferably 7.0%. The upper limit. Although it is possible to obtain an optical glass having a desired high partial dispersion ratio without containing the WO ₃ component, it is possible to obtain a glass portion by making the content of the WO ₃ component 0.1% or more. Since the dispersion ratio is increased, a glass having a desired high partial dispersion ratio can be easily obtained. Therefore, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.3%, and most preferably 0.5%. 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 making the content of the K ₂ O component 10.0% or less, it is difficult to lower the refractive index of the glass, and devitrification of the glass can be reduced. 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 Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component and Nb ₂ O ₅ is preferably 0.1% or more. Thereby, since the specific gravity of glass becomes small and the partial dispersion ratio of glass is increased, it is easy to obtain an optical glass having a desired small specific gravity and a high partial dispersion ratio. Accordingly, the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ ) with respect to the total mass of the glass in terms of oxide is preferably 0.1%, more preferably 0.5%, and most preferably 1.0. % Is the lower limit. On the other hand, by making the sum of these contents 20.0% or less, devitrification of the glass due to excessive inclusion of these components can be suppressed, and thus the devitrification resistance of the glass can be further improved. . Therefore, the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ ) with respect to the total mass of the glass in terms of oxide is preferably 20.0%, more preferably 15.0%, and most preferably 10.0. % Is the upper limit.

The optical glass of the present invention is the sum of the contents of Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component and Nb ₂ O ₅ with respect to the sum of the contents of La ₂ O ₃ component and Gd ₂ O ₃ component. Is preferably 0.010 or more. Thereby, relative to the contents of La ₂ O ₃ component and Gd ₂ O ₃ component, which are components that increase the specific gravity of glass, Bi ₂ O ₃ component, TiO ₂ component, which are components that decrease the specific gravity of glass, Since the contents of the WO ₃ component and Nb ₂ O ₅ are increased, an optical glass having a smaller specific gravity can be obtained. Accordingly, the mass ratio (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ + WO ₃ ) / (La ₂ O ₃ + Gd ₂ O ₃ ) of the oxide equivalent composition is preferably 0.010, more preferably 0.020, most preferably Preferably, 0.025 is set as the lower limit. On the other hand, the upper limit of the mass ratio is preferably 0.300, preferably 0.250, and preferably 0.200, from the viewpoint of easily obtaining an optical glass having a higher Abbe number.

In the optical glass of the present invention, the sum of at least one content selected from the group consisting 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 1.0% or more is preferable. By setting this sum to 1.0% or more, the partial dispersion ratio of the glass is increased, so that the partial dispersion ratio can have a desired relationship with the Abbe number. Therefore, the sum of the contents of these components with respect to the mass of the oxide equivalent composition is preferably 1.0%, more preferably 3.0%, still more preferably 6.6%, and most preferably 8.7%. The lower limit. On the other hand, the upper limit of the sum of the contents of these components is not particularly limited as long as a stable glass can be obtained. For example, it is assumed that devitrification is likely to occur when it exceeds 30.0%. Therefore, the sum of the contents of these components with respect to the mass of the oxide equivalent composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%.

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 still more preferably 8.5%. Although the ZrO ₂ component is an optional component, it does not have to be contained. However, by containing more than 0% of the ZrO ₂ component, the refractive index of the glass can be increased and the devitrification resistance of the glass can be improved. . Therefore, the content of the ZrO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably more than 0.5%, and most preferably more than 1.0%. 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 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. In addition, by reducing the content of Ta ₂ O ₅ component to 15.0% or less, the material cost of the glass is reduced, and melting at a high temperature is avoided to increase the production cost due to energy loss during glass production. Can be suppressed. 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.

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 setting the content of the Li ₂ O component to 5.0% or less, a decrease in the partial dispersion ratio of the glass can be suppressed. Further, by the content of Li 2 _O component below 5.0%, while reduction in the refractive index of the glass, it is possible to hardly occurs devitrification etc. due to excessive content of Li 2 _O component. Therefore, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 5.0% as an upper limit, more preferably less than 3.0%, and even more preferably less than 1.0%. Here, in terms of easily obtaining an optical glass having a higher partial dispersion ratio, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition may be less than 0.5%, 0.35% It may be less than it, and does not need to contain substantially. 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 Ta ₂ O ₅ component, ZrO ₂ component and Li _{2 with} respect to the sum of F component, Bi ₂ O ₃ component, TiO ₂ component, WO ₃ component, Nb ₂ O ₅ component and K ₂ O component. The ratio of the sum of O components is preferably 1.30 or less. Thereby, the content of the Ta ₂ O ₅ component, the ZrO ₂ component and the Li ₂ O component, which are components that lower the partial dispersion ratio, causes the F component, Bi ₂ O ₃ component, and TiO ₂ component, which are components that increase the partial dispersion ratio. , WO ₃ component, Nb ₂ O ₅ component and K ₂ O component, the optical 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 1.30, more preferably 1 .10, most preferably 0.95. On the other hand, this mass ratio is preferably 0.01, more preferably 0.05, and most preferably 0.10.

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, Nb ₂ O ₅ component and Ta ₂ O ₅ is preferably 0.1% or more. Thereby, the refractive index of glass can be raised and the devitrification resistance of glass can be improved. Accordingly, the mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ ) with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.5%, most preferably. Has a lower limit of 1.0%. On the other hand, the sum of the contents of these components is preferably 20.0% or less. Thereby, since the fall of the stability of glass by containing these components excessively 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 mass of the glass in terms of oxide is preferably 20.0%, more preferably 15.0%, and most preferably 10.0. % Is the upper limit.

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, the content of MgO component is 10.0% or less, the content of CaO component or SrO component is 25.0% or less, or the content of BaO component is 55.0% or less. It is difficult to reduce the rate, and devitrification of the glass can be reduced. Therefore, the content of the MgO component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. Further, the content of the CaO component and the SrO component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and more preferably less than 16.0%, Most preferably, it is less than 10.0%. Further, the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 55.0% as an upper limit, more preferably less than 40.0%, more preferably less than 30.0%, most preferably. Is less than 20.0%. 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, etc. 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 at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 55.0% or less. . 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 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 35.0%, still more preferably 25.0%, and most preferably 15.0. % Is the upper limit.

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 10.0%, more preferably 5.0%, and most preferably 3.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

The 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 mass sum of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 15.0%, and most preferably 5.0%.

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 the raw material price of the GeO ₂ component is high, the material cost increases when the amount of the GeO ₂ component is large, so that the obtained glass becomes impractical. Therefore, the content of the GeO ₂ component with respect to the total glass mass of the oxide-converted composition is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, and most preferably 2.%. Less than 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 5.0%, and most preferably 3.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material. .

The 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 contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component are each 10.0% or less, a decrease in the Abbe number of the glass can be suppressed. Therefore, the content of the Al ₂ O ₃ component and 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%, respectively. Is the upper limit. 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.

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% as an upper limit, more preferably 5.0%, and most preferably 3.0%. 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.

  Moreover, each transition metal component such as Hf, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, Even when a small amount is contained alone or in combination, the glass is colored and has the property of absorbing light of a specific wavelength in the visible range. It is preferable not to include.

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 tended to refrain 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%,
La ₂ O ₃ component 10.0～25.0Mol% and _Y 2 _{O 3} component 0 mol% ultra ～40.0Mol%
And SiO ₂ component 0～70.0Mol% and / or _Gd 2 _{O 3} component 0～20.0Mol% and / or _Yb 2 _{O 3} component 0～10.0Mol% and / or _Lu 2 _{O 3} component 0-10. 0 mol% and / or Bi ₂ O ₃ component 0 to 4.0 mol% and / or TiO ₂ component 0 to 30.0 mol% and / or Nb ₂ O ₅ component 0 to 10.0 mol% and / or WO ₃ component 0 10.0 mol% and / or _{K 2} O ingredient 0～15.0Mol% and / or ZrO ₂ component 0～15.0Mol% and / or _Ta 2 _{O 5} component 0～4.0Mol% and / or Li ₂ O component 0 to 15.0 mol% and / or MgO component 0 to 35.0 mol% and / or CaO component 0 to 50.0 mol% and / or SrO component 0 to 35.0 mol% and / or Ba Component 0～50.0Mol% and / or Na ₂ O component 0～25.0Mol% and / or ZnO component 0～25.0Mol% and / or GeO ₂ component 0～20.0Mol% and / or _P 2 _{O 5} component 0～10.0Mol% and / or _Al 2 _{O 3} component 0～15.0Mol% and / or _Ga 2 _{O 3} component 0～8.0Mol% and / or TeO ₂ component 0～8.0Mol% 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 There is a means of slowly cooling by casting into a mold.

[Physical properties]
The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.68, more preferably 1.70, and most preferably 1.75. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is not particularly limited, but is generally 2.20 or less, more specifically 2.10 or less, and more specifically 2.00 or less. There are many. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 42, and most preferably 44. 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 60 or less, and more specifically 57 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). As a result, the degree of freedom in optical design is increased, and a large amount of light refraction can be obtained even if the device is made thinner.

The optical glass of the present invention has a low specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 5.00 [g / cm ³ ] or less. Thereby, since the mass of an optical element and an optical apparatus using the same is reduced, it can contribute to the weight reduction of an optical apparatus. Accordingly, the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.80, and preferably 4.70. The specific gravity of the optical glass of the present invention is generally about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more in many cases.

  The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 “Measurement Method of Specific Gravity of Optical Glass”.

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) ≧ (−0.00170 × ν _d +0.63750) with the Abbe number (ν _d ). ) 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 +0.63750), more preferably (−0.00170 × ν _d +0.63950), Preferably, it is (−0.00170 × ν _d +0.64050). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass is not particularly limited, but is approximately (−0.00170 × ν _d +0.68000) or less, more specifically (−0.00170 × ν). _d +0.67900) or less, more specifically, (−0.00170 × ν _d +0.67800) or less 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 Japan 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 ₈₀ ) showing a spectral transmittance of 80% 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. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₈₀ (wavelength at 80% transmittance) and λ ₅ (transmittance). Wavelength at 5%). The values of λ ₈₀ and λ ₅ listed in the table of the examples of the present invention were also measured by this method.

  The optical glass of the present invention preferably has high devitrification resistance. In particular, the optical glass of the present invention preferably has a low liquidus temperature of 1200 ° C. or lower. More specifically, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C, more preferably 1180 ° C, and most preferably 1150 ° C. As a result, the stability of the glass is increased and crystallization is reduced, so that the devitrification resistance when the glass is formed from the molten state can be improved, and the optical properties of the optical element using the glass are affected. Can be reduced. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 500 ° C. or higher, specifically 550 ° C. or higher, more specifically 600. Often above ℃. In addition, in the “heat insulation test” in this specification, in order to confirm that the glass has high devitrification resistance, a glass raw material is placed in a 30 cc platinum crucible and covered with a furnace at 1200 ° C. to 1250 ° C. After melting for about 10 to 20 minutes and stirring and homogenizing, the obtained glass is covered in a furnace set at 1000 to 1150 ° C. and held for 2 hours, and the glass surface and inside, and This was carried out by observing crystals precipitated on the contact surface with the inner wall of the crucible.

[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. 151) and Comparative Example (No. 1) of the present invention, and the refractive index (n _d ) and Abbe number (ν _d ) and partial dispersion ratio (θg) of these glasses , F) and specific gravity values are shown in Tables 1 to 20. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 151) of the present invention and the glass of Comparative Example (No. 1) are all oxides, hydroxides, carbonates and nitrates corresponding to the raw materials of the respective components. Select high-purity raw materials used in ordinary optical glass such as fluorides, hydroxides, metaphosphoric acid compounds, etc., so that the composition ratios of the examples and comparative examples shown in Tables 1 to 20 are obtained. After weighing and mixing uniformly, it is put into a platinum crucible and melted in a temperature range of 1000 to 1400 ° C. for 1 to 6 hours according to the melting difficulty of the glass composition. Then, the temperature was lowered to 1200 ° C. or lower, and the mixture was homogenized with stirring, cast into a mold, and slowly cooled to produce 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. 151) and Comparative Example (No. 1) are as follows. It measured based on optical glass industry association standard JOGIS01-2003. Then, with respect to the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F), the intercept when the slope a is 0.0017 in the relational expression (θg, F) = − a × ν _d + b 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.

  Moreover, specific gravity of the glass of an Example (No.1-No.151) and a comparative example (No.1) was measured based on Japan Optical Glass Industry Association standard JOGIS05-1975 "measurement method of specific gravity of optical glass". .

  Each of the optical glasses of the examples of the present invention had a specific gravity of 5.00 or less, more specifically 4.70 or less, and more specifically 4.65 or less. On the other hand, the specific gravity of the glass of the comparative example of the present invention was larger than 5.00. Therefore, it became clear that the optical glass of the Example of this invention has small specific gravity compared with the glass of a comparative example.

The optical glass of the example of the present invention has a partial dispersion ratio (θg, F) of (−0.00170 × ν _d +0.63750) or more, more specifically (−0.00170 × ν _d +0. 64110) or more. 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. .

Each of the optical glasses of the examples of the present invention has a refractive index (n _d ) of 1.68 or more, more specifically 1.71 or more, and this refractive index (n _d ) of 2.20 or less. Specifically, it was 1.80 or less, which was within a desired range.
The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 40 or more, more specifically 42 or more, and the Abbe number (ν _d ) of 63 or less, more specifically 56 or less, which was within the desired range.
Further, in the optical glass of the example of the present invention, the refractive index (n _d ) and the Abbe number (ν _d ) satisfied the relationship of (ν _d ) ≧ (−100 × n _d +220).

Therefore, it has been clarified that the optical glass of the example of the present invention has small chromatic aberration and small specific gravity while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges.

  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 this 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 (28)

Containing 5.0 to 55.0% of B ₂ O ₃ component and 10.0 to 55.0% of La ₂ O ₃ component in terms of mass% with respect to the total mass of the oxide-converted composition, Y ₂ O An optical glass further containing _three components and an F component. Oxide entire mass of the glass composition in terms of mass% in _Y 2 _{O 3} optical glass of claim 1, wherein the component containing less 50.0% 0.1% or more.   3. The optical glass according to claim 1, wherein the optical component contains 0.1% or more and 30.0% or less of an F component in an externally divided mass% with respect to the oxide-based mass. The optical glass according to any one of claims 1 to 3, wherein the content of the SiO ₂ component is 40.0% or less by mass with respect to the total mass of the glass having an oxide equivalent composition. The entire mass of the glass in terms of oxide composition, 0~40.0% _Gd 2 _{O 3} component in% by weight and / or _Yb 2 _{O 3} component from 0 to 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, Yb, and Lu) with respect to the total glass mass of the oxide equivalent composition is 38.0% or more and 70 The optical glass according to claim 1, which is 0.0% or less. The optical glass according to claim 6, wherein a mass ratio Y ₂ O ₃ / Ln ₂ O _{3 of the} oxide equivalent composition is 0.100 or more. 8. The optical glass according to claim 1, wherein a mass sum (Gd ₂ O ₃ + Yb ₂ O ₃ ) with respect to the total glass mass of the oxide equivalent 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 (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ + WO ₃ ) with respect to the total mass of the glass in an oxide conversion composition is 0.1% or more. The optical glass according to claim 9 or 10, wherein the mass ratio of the oxide equivalent composition (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ + WO ₃ ) / (La ₂ O ₃ + Gd ₂ O ₃ ) is 0.010 or more. 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 1.0% or more and 30.0% or less. Optical glass. ZrO ₂ component 0 to 15.0% and / or Ta ₂ O ₅ component 0 to 15.0% and / or Li ₂ O component 0 to 5.0% by mass with respect to the total glass mass of the oxide conversion composition %
The optical glass according to claim 1, further comprising: 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 1.30 or less. Or an optical glass. The optical glass according to any one of claims 1 to 14, wherein a mass sum (Bi ₂ O ₃ + TiO ₂ + WO ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ ) with respect to the total glass mass of the oxide conversion composition is 0.1% or more. MgO component 0 to 10.0% and / or CaO component 0 to 25.0% and / or SrO component 0 to 25.0% 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-converted composition is 55.0% or less. Optical glass. The optical glass according to any one of claims 1 to 17, wherein the content of the Na ₂ O component is 10.0% or less by mass with respect to the total mass of the oxide-converted 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-converted composition is 25.0% or less. Optical glass. ZnO component 0 to 25.0% and / or GeO ₂ component 0 to 10.0% and / or P ₂ O ₅ component 0 to 10.0% by mass% with respect to the total glass mass of the oxide equivalent composition / Or Al ₂ O ₃ component 0 to 10.0% 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 to 1.0%
The optical glass according to claim 1, further comprising: 21. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.68 or more and an Abbe number (ν _d ) of 40 or more. The optical glass according to claim 1, wherein the Abbe number (ν _d ) satisfies a relationship of ν _d ≧ −100 × n _d +220 with respect to the refractive index (n _d ). The partial dispersion ratio (θg, F) satisfies the relationship of (θg, F) ≧ (−0.00170 × ν _d +0.63750) with the Abbe number (ν _d ) 23. Optical glass.   24. The optical glass according to claim 1, wherein the specific gravity is 5.00 or less.   A preform material comprising the optical glass according to any one of claims 1 to 24.   An optical element produced by press-molding the preform material according to claim 25.   An optical element using the optical glass according to any one of claims 1 to 24 as a base material.   An optical apparatus comprising the optical element according to claim 26 or 27.

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