TWI585056B - Optical glass and optical components - Google Patents

Description

Optical glass and optical components

This invention relates to an optical glass and optical component.

In recent years, the digitization or high definition of machines using optical systems has been rapidly developed, in the field of various optical devices such as digital cameras or camera cameras, or image playback (projection) machines such as projectors and projection televisions. There is a strong demand to reduce the number of optical elements such as lenses and cymbals used in optical systems, and to reduce the weight and size of the optical system as a whole.

In the optical glass for producing an optical element, in particular, it is possible to reduce the refractive index (n _d ) of 1.80 or more and to have a high refractive index of Abbe number (ν _d ) of 35 or more and 50 or less in order to reduce the weight and size of the optical system as a whole. The demand for low-dispersion glass has become very high. As such a high refractive index low dispersion glass, a glass composition represented by Patent Documents 1 to 4 is known.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-348244

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-016293

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-102215

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2009-203083

As a method of producing an optical element from optical glass, for example, a method of grinding and polishing a glass paste ball or a glass tile formed of optical glass to obtain a shape of an optical element; a glass to be formed of optical glass is known a method of grinding and grinding a glass molded body obtained by reheating and shaping a resin ball or a glass brick (reheating pressure forming); and preforming a glass paste ball or a glass brick by using an ultra-precision processed mold A method of obtaining a shape of an optical element by forming a material (precision mold pressure forming). In either method, when a glass paste ball or a glass block is formed from a molten glass raw material, it is required to reduce the devitrification of the formed glass. Here, when devitrification occurs due to crystallization occurring inside the obtained glass paste ball or glass tile, a preferable glass is not obtained as an optical element.

Moreover, in order to reduce the material cost of the optical glass, it is desirable that the raw material cost of each component constituting the optical glass be as inexpensive as possible. Further, in order to reduce the manufacturing cost of the optical glass, it is desirable that the melting property of the raw material is high, that is, it is melted at a lower temperature. However, the glass compositions described in Patent Documents 1 to 4 are not sufficiently suitable for those various requirements.

The present invention has been made in view of the above problems, and an object thereof is to obtain a glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and having high devitrification resistance at a lower cost.

The present inventors have conducted intensive experimental research in order to solve the above problems, and as a result, it has been found that by reducing the content of the Ta ₂ O ₅ component relative to the glass containing the B ₂ O ₃ component and the La ₂ O ₃ component, The glass has a desired refractive index and Abbe number, and the material cost of the glass is lowered, and the liquidus temperature of the glass becomes low, thereby achieving the present invention. Specifically, the present invention provides the following.

(1) An optical glass containing, by mass%, 1.0 to 30.0% of a B ₂ O ₃ component and 10.0 to 55.0% of a La ₂ O ₃ component, and a Ta ₂ O ₅ component, based on the total mass of the oxide-converted composition. The content is 20.0% or less.

(2) The optical glass according to the above (1), which contains at least one selected from the group consisting of a TiO ₂ component, a Nb ₂ O ₅ component, and a WO ₃ component in an oxide-converted composition.

(3) The optical glass according to (2) above, wherein the sum of the content of one or more selected from the group consisting of a TiO ₂ component, a Nb ₂ O ₅ component, and a WO ₃ component is a total mass of the glass in terms of an oxide conversion composition. It is 0.5% or more and 40.0% or less.

(4) The optical glass according to the above (2) or (3), which contains, by mass%, TiO ₂ component 0 to 20.0% and/or Nb ₂ O ₅ component 0 with respect to the total mass of the glass in terms of oxide conversion composition. ~20.0% and / or WO ₃ ingredients 0 ~ 25.0%.

(5) The optical glass according to any one of the above (1) to (4), which further contains, in mass%, the following components: SiO ₂ component 0 to 20.0%, and / or ZrO ₂ composition 0 ~ 12.0%.

The optical glass of any one of the above-mentioned (1) to (5), wherein the sum of the content of the B ₂ O ₃ component and the SiO ₂ component is 25.0% or less based on the total mass of the glass of the oxide conversion composition.

(7) The optical glass according to any one of the above (1) to (6), wherein the mass ratio of the oxide conversion composition (ZrO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ ) / (B ₂ O ₃ + SiO ₂ ) is 2.00 or less.

(8) The optical glass according to any one of the above (1) to (7), which further contains, in mass%, the following components with respect to the total mass of the oxide-converted composition: Gd ₂ O ₃ component 0 to 45.0 % and / or Y ₂ O ₃ components 0 ~ 30.0% and / or Yb ₂ O ₃ components 0 ~ 20.0%.

(9) The optical glass according to any one of the above (1), wherein the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) The mass and the total mass of the glass relative to the oxide-converted composition are 30.0% or more and 75.0% or less.

(10) The optical glass according to the above (9), wherein the mass of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) and the conversion with respect to the oxide The total mass of the composed glass is more than 40.0%.

(11) The optical glass according to any one of (1) to (10) above, wherein the mass ratio of the oxide conversion composition is Ta ₂ O ₅ /(Ln ₂ O ₃ +ZrO ₂ +Nb ₂ O ₅ +WO ₃ ) It is 0.300 or less (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb).

(12) The optical glass according to any one of the above (1) to (11), which further contains, in mass%, the following components in terms of mass % of the oxide: 0 to 20.0% of the MgO component and/or Or CaO component 0~20.0% and/or SrO component 0~20.0% and/or BaO component 0~25.0%.

(13) The optical glass according to the above (12), wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) and the composition of the glass in terms of oxides The total mass is 25.0% or less.

(14) The optical glass according to any one of the above (1) to (13), which further contains, in mass%, the following components in terms of the total mass of the oxide-converted composition: Li ₂ O component 0 to 10.0% And/or Na ₂ O component 0~10.0% and/or K ₂ O component 0~10.0% and/or Cs ₂ O component 0~10.0%.

(15) The optical glass according to the above (14), wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) has a mass and is converted with respect to the oxide. The total mass of the glass is 15.0% or less.

(16) The optical glass according to any one of the above (1) to (15), wherein the mass ratio of the oxide conversion composition (B ₂ O ₃ + SiO ₂ + WO ₃ ) / (Ln ₂ O ₃ + ZrO ₂ + Li ₂ O) is 0.20 or more and 2.00 or less.

(17) The optical glass according to any one of the above (1) to (16), which further contains, in mass%, the following components in terms of the total mass of the oxide-converted composition: P ₂ O ₅ component 0 to 10.0 % and/or GeO ₂ component 0~10.0% and/or ZnO component 0~25.0% and/or Al ₂ O ₃ component 0~10.0% and/or Ga ₂ O ₃ component 0~10.0% and/or Bi ₂ O ₃ components 0 to 20.0% and/or TeO ₂ components 0 to 20.0% and/or SnO ₂ components 0 to 1.0% and/or Sb ₂ O3 components 0 to 1.0%.

(18) The optical glass according to any one of (1) to (17) above which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more and 50 or less.

(19) The optical glass according to any one of (1) to (18) above which has a liquidus temperature of 1300 ° C or lower.

(20) An optical element comprising the optical glass according to any one of the above (1) to (19) as a base material.

(21) An optical device comprising the optical element according to (20) above.

According to the present invention, by lowering the content of the Ta ₂ O ₅ component relative to the glass containing the B ₂ O ₃ component and the La ₂ O ₃ component, the glass has a desired refractive index and Abbe number, and the glass transition point is made. It becomes lower and the material cost of the glass is lowered. Therefore, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and having high devitrification resistance can be obtained at a lower cost.

The optical glass of the present invention contains, by mass%, 1.0 to 30.0% of the B ₂ O ₃ component and 10.0 to 50.0% of the La ₂ O ₃ component, and the content of the Ta ₂ O ₅ component, in terms of mass% of the glass. 20.0% or less. Since the amount of the Ta ₂ O ₅ component which is expensive and needs to be melted at a high temperature is reduced by lowering the content of the Ta ₂ O ₅ component, the raw material cost and the manufacturing cost of the optical glass are lowered. At the same time, the B ₂ O ₃ component and the La ₂ O ₃ component are used as a base, and have a refractive index (n _d ) of 1.80 or more and an Abbe number (ν _d ) of 35 or more and 50 or less, and a liquid phase. The temperature is easy to get low. Therefore, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and having high devitrification resistance and an optical element using the same can be obtained at a lower cost.

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 may be appropriately modified and implemented within the scope of the object of the present invention. In addition, the description of the repetitive description is omitted as appropriate, and the scope of the invention is not limited.

[Glass composition]

The composition range of each component constituting the optical glass of the present invention will be described below. In the case where there is no particular description in the present specification, the content of each component is expressed by mass% based on the total mass of the glass in terms of oxide composition. Here, the term "oxide-converting composition" means that when an oxide, a composite salt, or a metal fluoride which is used as a raw material of the glass constituent component of the present invention is equal to being completely decomposed and converted into an oxide at the time of melting, the formation is performed. The total mass of the oxide is set to 100% by mass, and the composition of each component contained in the glass is described.

<About essential ingredients, optional ingredients>

The B ₂ O ₃ component is an indispensable component for forming an oxide of glass in the optical glass of the present invention containing a rare earth oxide in a large amount. In particular, by making the content of the B ₂ O ₃ component 1.0% or more, the devitrification resistance of the glass can be improved, and the dispersion of the glass can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 1.0% as the lower limit, more preferably 5.0% as the lower limit, and more preferably 8.5% as the lower limit, based on the total mass of the glass in terms of the oxide conversion composition. The best is to set 10.0% to the lower limit. On the other hand, by setting the content of the B ₂ O ₃ component to 30.0% or less, a larger refractive index can be easily obtained, and deterioration in chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 30.0% as the upper limit, more preferably 20.0% as the upper limit, and more preferably 18.0% as the upper limit, based on the total mass of the glass in terms of the oxide conversion composition. The best is to set 15.0% as the upper limit. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ ‧10H ₂ O, BPO ₄ or the like as a raw material.

The La ₂ O ₃ component is a component that increases the refractive index of the glass and reduces the dispersion of the glass and increases the Abbe number. In particular, by setting the content of the La ₂ O ₃ component to 10.0% or more, the refractive index of the glass can be increased. Therefore, the content of the La ₂ O ₃ component is preferably 10.0% as the lower limit, more preferably 20.0% as the lower limit, and more preferably 25.0% as the lower limit, based on the total mass of the glass in terms of oxide conversion composition. The best is to set 30.0% as the lower limit. On the other hand, by setting the content of the La ₂ O ₃ component to 55.0% or less, more preferably 50.0% or less, the durability of the glass can be improved and the devitrification of the glass can be reduced. Therefore, the content of the La ₂ O ₃ component is preferably 55.0% as the upper limit, more preferably 50.0% as the upper limit, and even more preferably 49.0% as the upper limit. The best is to set 48.0% as the upper limit. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ or La(NO ₃ ) ₃ ‧XH ₂ O (X is an arbitrary integer) as a raw material.

The Ta ₂ O ₅ component is a component which increases the refractive index of the glass and lowers the liquid phase temperature of the glass to improve the devitrification resistance, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Ta ₂ O ₅ component to 20.0% or less, the content of the expensive Ta ₂ O ₅ component is lowered, so that an optical glass having a desired optical constant can be produced at a lower material cost. On the other hand, when the content of the Ta ₂ O ₅ component exceeds 20.0%, it becomes difficult to obtain a durable glass. Therefore, the content of the Ta ₂ O ₅ component is preferably 20.0% as the upper limit, more preferably less than 17.5%, and more preferably 13.9% as the upper limit of the total mass of the glass in terms of oxide conversion composition. . Here, in particular, by setting the content of the Ta ₂ O ₅ component to 9.5% or less, the temperature of the molten raw material can be lowered, and the energy required for melting the raw material can be lowered, so that the production cost of the optical glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component in the viewpoint is preferably 9.5% as the upper limit, more preferably 7.0% as the upper limit, and most preferably 5.0%. Set to the upper limit. On the other hand, when the content of the Ta ₂ O ₅ component is more than 9.5%, the coloring of the glass and the refractive index of the glass can be suppressed, and the devitrification resistance of the glass can be improved. Therefore, the content of the Ta ₂ O ₅ component in the viewpoint is preferably more than 9.5% based on the total mass of the glass in terms of oxide conversion composition, more preferably 11.0% is set as the lower limit, and further preferably 12.8% is set. The lower limit. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ or the like as a raw material.

The optical glass of the present invention preferably contains one or more selected from the group consisting of a TiO ₂ component, a WO ₃ component, and a Nb ₂ O ₅ component. Thereby, even if the content of the Ta ₂ O ₅ component is lowered in order to reduce the material cost of the glass, the refractive index of the glass can be increased, and the devitrification resistance of the glass can be improved. Therefore, the sum of the content of one or more selected from the group consisting of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably more than 0%, more preferably, the total mass of the glass in terms of oxide conversion composition. In order to set 0.5% as the lower limit, it is preferable to set 1.0% as the lower limit. On the other hand, when the sum is 40.0% or less, the coloring due to the components can be reduced, and the deterioration of the devitrification resistance due to the excessive inclusion of the components can be suppressed. Therefore, the sum of the content of one or more selected from the group consisting of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 40.0% as the upper limit of the total mass of the glass in terms of the oxide conversion composition. More preferably, 30.0% is set as the upper limit, and further preferably 20.0% is set as the upper limit, and it is preferable to set 8.0% as the upper limit.

The TiO ₂ component is a component which adjusts the refractive index and Abbe number of the glass and improves the resistance to devitrification, and is an optional component in the optical glass of the present invention. However, if the amount of TiO _{2 is} too large, the devitrification resistance is deteriorated, and the transmittance of the glass having a short wavelength (below 500 nm) is also deteriorated. Therefore, the content of the TiO ₂ component is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 8.0% as the upper limit. Jiawei sets 5.0% as the upper limit. The TiO ₂ component can be contained in the glass using, for example, TiO ₂ or the like as a raw material.

The Nb ₂ O ₅ component is a component which increases the refractive index and dispersion of the glass and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Nb ₂ O ₅ component to 20.0% or less, it is possible to suppress the deterioration of the devitrification resistance of the glass which is caused by the excessive inclusion of the Nb ₂ O ₅ component, and to suppress the transmittance of the visible light of the glass. reduce. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 12.0% as the upper limit. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ or the like as a raw material.

The WO ₃ component is a component that increases the refractive index and dispersion of the glass and improves the resistance to devitrification of the glass. In particular, by setting the content of the WO ₃ component to 25.0%, more preferably 20.0% or less, the coloring of the glass can be lowered, and in particular, the transmittance in the visible-short wavelength region (less than 500 nm) is hardly lowered. Therefore, the content of the WO ₃ component is preferably 25.0% as the upper limit, more preferably 20.0% as the upper limit, and even more preferably 15.0% as the upper limit. Jiawei sets 12.0% as the upper limit. Further, the optical glass of the present invention can obtain a glass having a desired optical constant and resistance to devitrification without containing the WO ₃ component. However, since the WO ₃ component is contained, the liquid phase temperature of the glass can be further lowered. It can further improve the resistance to devitrification of the glass. Therefore, the content of the WO ₃ component is preferably more than 0% based on the total mass of the glass in terms of oxide conversion composition, more preferably 0.1% is set as the lower limit, and most preferably 1.0% is set as the lower limit. The WO ₃ component can be contained in the glass using, for example, WO ₃ or the like as a raw material.

The SiO ₂ component is a component which is a component of the optical glass of the present invention which is a component which improves the viscosity of the molten glass, promotes the formation of a durable glass, and reduces the devitrification (production of crystals) which is a poor optical glass. In particular, by setting the content of the SiO ₂ component to 20.0% or less, it is possible to suppress an increase in the glass transition point (Tg) and suppress a decrease in the refractive index. Therefore, the content of the SiO ₂ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 10.0% as the upper limit. Further, although it is not technically disadvantageous even if the SiO ₂ component is not contained, since the liquid phase temperature of the glass is lowered by the inclusion of the SiO ₂ component, the glass is further hardly devitrified. Therefore, the content of the SiO ₂ component is preferably 0.1% as the lower limit, more preferably 1.0% as the lower limit, and even more preferably 2.0% as the lower limit. In particular, the content of the SiO ₂ component is preferably 4.0% or more from the viewpoint of making it difficult to color the glass even if the TiO ₂ component or the WO ₃ component is contained. The SiO ₂ component can be contained in the glass using, for example, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like as a raw material.

The ZrO ₂ component is a component which contributes to the high refractive index and low dispersion of the glass, and is an optional component in the optical glass of the present invention. However, if the amount of ZrO ₂ is too large, the devitrification resistance is deteriorated. Therefore, the content of the ZrO ₂ component is preferably 12.0% as the upper limit, more preferably 10.0% as the upper limit, and most preferably 8.0% as the upper limit. Further, although the desired glass can be obtained even without the ZrO ₂ component, the high refractive index and low dispersion property can be easily obtained by containing the ZrO ₂ component, and the effect of improving the devitrification resistance can be easily obtained. . Therefore, the content of the ZrO ₂ component is preferably more than 0% based on the total mass of the glass in terms of oxide conversion composition, more preferably 0.5% is set as the lower limit, and most preferably 1.0% is set as the lower limit. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ or ZrF ₄ as a raw material.

The optical glass of the present invention preferably has a mass of B ₂ O ₃ component and SiO ₂ component of 25.0% or less, more preferably 23.0% or less. Thereby, the decrease in the refractive index due to the inclusion of the B ₂ O ₃ component and the SiO ₂ component can be suppressed, so that a desired higher refractive index can be easily obtained. Therefore, the mass of the B ₂ O ₃ component and the SiO ₂ component and the total mass of the glass relative to the oxide-converted composition are preferably 25 or 0% as the upper limit, more preferably 23.0% as the upper limit, and further preferably In order to set 21.0% as the upper limit, it is best to set it to less than 20.0%.

Further, in the optical glass of the present invention, the ratio of the mass and (ZrO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ ) to the mass and (B ₂ O ₃ + SiO ₂ ) is preferably 2.00 or less. Since the content of the ZrO ₂ component, the Ta ₂ O ₅ component, and the Nb ₂ O ₅ component having a high material cost is lowered, the desired optical glass having a lower liquidus temperature can be produced at a lower cost. Therefore, the mass ratio of the oxide-converted composition (ZrO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ ) / (B ₂ O ₃ + SiO ₂ ) is preferably an upper limit of 2.00, and more preferably an upper limit of 1.80. The best is to set 1.50 as the upper limit.

The Gd ₂ O ₃ component is a component which increases the refractive index of the glass and increases the Abbe number, and is an arbitrary component in the optical glass of the present invention. In particular, when the content of the Gd ₂ O ₃ component is 45.0% or less, more preferably 40.0% or less, the desired optical constant of the glass can be easily obtained, and the excessive inclusion of Gd ₂ O ₃ can be suppressed. The increase in the glass transition point (Tg) produced by the composition and the resistance to devitrification of the glass. Moreover, by lowering the Gd ₂ O ₃ component, the material cost of the optical glass can be reduced. Therefore, the content of the Gd ₂ O ₃ component is preferably 45.0% as the upper limit, more preferably 40.0% as the upper limit, and even more preferably 30.0% as the upper limit. The best is to set 25.0% as the upper limit. Further, although it is not technically disadvantageous even if the Gd ₂ O ₃ component is not contained, since the liquid phase temperature of the glass can be lowered by containing more than 0%, the devitrification resistance can be improved. Therefore, the content of the Gd ₂ O ₃ component is preferably more than 0% based on the total mass of the glass in terms of oxide conversion composition, more preferably 1.0% is set as the lower limit, and further preferably 2.0% is set as the lower limit. Here, from the viewpoint of easily obtaining a desired optical constant by increasing the refractive index and Abbe number of the glass, the content of the Gd ₂ O ₃ component is preferably based on the total mass of the glass in terms of oxide conversion composition. More than 5.0%, more preferably 5.5% is set as the lower limit, and it is preferable to set 6.0% as the lower limit. Further, from the viewpoint of further improving the resistance to devitrification of the glass, the ratio of the content of the Gd ₂ O ₃ component to the content of the La ₂ O ₃ component (Gd ₂ O ₃ /La ₂ O ₃ ) is preferably 0.01 or more and 2.00. Hereinafter, it is more preferably 0.03 or more and 1.70 or less, and most preferably 0.05 or more and 1.50 or less. The Gd ₂ O ₃ component can be contained in the glass using, for example, Gd ₂ O ₃ or GdF ₃ as a raw material.

The Y ₂ O ₃ component and the Yb ₂ O ₃ component are components which increase the refractive index of the glass and reduce the dispersion, and are arbitrary components in the optical glass of the present invention. In particular, when the content of the Y ₂ O ₃ component is 30.0% or less, and/or the content of the Yb ₂ O ₃ component is 20.0% or less, the desired optical constant of the glass can be easily obtained. Improve the resistance to devitrification of glass. Therefore, the content of the Y ₂ O ₃ component is preferably an upper limit of 30.0%, more preferably 25.0%, and more preferably 20.0%, based on the total mass of the glass of the oxide conversion composition. The upper limit is best to set 15.0% as the upper limit. Therefore, the content of the Yb ₂ O ₃ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 10.0% as the upper limit, based on the total mass of the glass of the oxide conversion composition. . The Y ₂ O ₃ component and the Yb ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ , Yb ₂ O ₃ or the like as a raw material.

In the optical glass of the present invention, the mass of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 30.0% or more and 75.0% or less. Preferably, it is 30.0% or more and 70.0% or less. In particular, by making the mass of the Ln ₂ O ₃ component 30.0% or more, the refractive index and the Abbe number of the glass can be improved, and thus a glass having a desired refractive index and Abbe number can be easily obtained. Therefore, the mass of the Ln ₂ O ₃ component and the total mass of the glass relative to the oxide-converted composition are preferably 30.0% as the lower limit, more preferably 33.0% as the lower limit, and still more preferably more than 40.0%. The best is more than 55.0%. On the other hand, since the mass of the Ln ₂ O ₃ component is 75.0% or less, the liquidus temperature of the glass becomes low, so that devitrification of the glass can be reduced. Therefore, the mass of the Ln ₂ O ₃ component and the total mass of the glass in terms of the oxide conversion composition are preferably 75.0% as the upper limit, more preferably 70.0% as the upper limit, and further preferably 65.0%. The upper limit is further preferably 60.0% as the upper limit, and most preferably 55.0% as the upper limit.

In the optical glass of the present invention, the ratio of the content and mass of the Ta ₂ O ₅ component to (Ln ₂ O ₃ + ZrO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 0.300 or less. Since the content of the Ta ₂ O ₅ component having a high material cost among the components for increasing the refractive index is lowered, an optical glass having a high refractive index can be produced at a lower cost. Therefore, the mass ratio of the total mass of the glass of the oxide-converted composition, Ta ₂ O ₅ /(Ln ₂ O ₃ +ZrO ₂ +Nb ₂ O ₅ +WO ₃ ), is preferably set to an upper limit of 0.300, more preferably 0.280. For the upper limit, it is best to set 0.250 as the upper limit.

The MgO component, the CaO component, the SrO component, and the BaO component are components which adjust the refractive index, meltability, and devitrification property of the glass, and are arbitrary components in the optical glass of the present invention. In particular, when the content of each of the MgO component, the CaO component, the SrO component, and the BaO component is 20.0% or less, and/or the content of the BaO component is 25.0% or less, the refraction due to the components is suppressed. The rate is lowered, whereby the desired refractive index can be easily obtained, and the devitrification of the glass due to the excessive inclusion of the components can be reduced. Therefore, the content of each of the MgO component, the CaO component, and the SrO component is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and most preferably 5.0. % is set to the upper limit. Further, the content of the BaO component is preferably 25.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 10.0% as the upper limit. As the MgO component, the CaO component, the SrO component, and the BaO component, for example, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr(NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba(NO ₃ ) ₂ , BaF ₂ or the like can be used. The raw material is contained in the glass.

In the optical glass of the present invention, the total content of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 25.0% or less. Thereby, the desired refractive index can be easily obtained by suppressing a decrease in the refractive index due to the RO component. Therefore, the mass of the RO component and the total mass of the glass in terms of the oxide-converted composition are preferably 25.0% as the upper limit, more preferably 15.0% as the upper limit, and even more preferably less than 12.0%. Jia is set to less than 10.0%.

The Li ₂ O component, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component are components which improve the meltability of the glass and lower the glass transition point, and are arbitrary components in the optical glass of the present invention. Among them, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component are also components which improve the devitrification resistance of the glass. In particular by making ₂ O components Li, N _a2 O component, K ₂ O and Cs ₂ O component respective component content of 10.0% or less, make it difficult to reduce the refractive index of the glass, and enhance the durability of the glass, which reduces the loss Produce through. Therefore, the content of each of the Li ₂ O component, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component is preferably 10.0%, and more preferably 8.0, based on the total mass of the glass of the oxide conversion composition. % is set to the upper limit, and it is best to set 5.0% as the upper limit. As the Li ₂ O component, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component, for example, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , or the like can be used. KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ , Cs ₂ CO ₃ , CsNO ₃ and the like are contained in the glass as a raw material.

The Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is a component which lowers the meltability of the glass and reduces the devitrification of the glass. Here, by setting the total content of the Rn ₂ O components to 15.0% or less, it is difficult to lower the refractive index of the glass, and the durability of the glass is improved, and the occurrence of devitrification or the like is reduced. Therefore, the mass of the Rn ₂ O component and the total mass of the glass in terms of the oxide-converted composition are preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, and most preferably 5.0% as the upper limit.

In the optical glass of the present invention, the ratio of the mass and (B ₂ O ₃ + SiO ₂ + WO ₃ ) to the mass and (Ln ₂ O ₃ + ZrO ₂ + Li ₂ O) is preferably 0.20 or more and 2.00 or less, more preferably It is 0.27 or more and 2.00 or less. In particular, when the ratio is 0.27 or more, the component (Ln ₂ O ₃ component, ZrO ₂ component, and Li ₂ O component) having reduced devitrification resistance is improved, and the devitrification-resistant component is improved (B). _{The content of the 2} O ₃ component, the SiO ₂ component, and WO ₃ ) is increased, so that an optical glass having a lower liquidus temperature and more difficult to devitrify can be obtained. On the other hand, since the ratio is 2.00 or less, the Ln ₂ O ₃ component which is a component for increasing the refractive index and the Abbe number is easily contained in the glass, so that the desired refractive index and the desired refractive index can be easily obtained. Abbe number. Therefore, the mass ratio of the oxide-converted composition (B ₂ O ₃ + SiO ₂ + WO ₃ ) / (Ln ₂ O ₃ + ZrO ₂ + Li ₂ O) is preferably 0.20 as the lower limit, more preferably 0.27. The lower limit is further preferably 0.28 as the lower limit, and it is preferable to set 0.29 as the lower limit. Further, the quality is preferably set to 2.00 as the upper limit, more preferably 1.50 as the upper limit, and most preferably 1.00 as the upper limit.

The P ₂ O ₅ component is a component having an effect of lowering the liquidus temperature of the glass and improving the devitrification resistance, and is an optional component in 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, the chemical durability of the glass, particularly the water resistance, can be suppressed. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% as the upper limit, more preferably 8.0% as the upper limit, and most preferably 5.0% as the upper limit. 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 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, if the amount is large, the production cost becomes high, and the effect of lowering the Ta ₂ O ₅ component is reduced. Therefore, the content of the GeO ₂ component is preferably set to 10.0% as the upper limit, more preferably 5.0% as the upper limit, and most preferably 1.0% as the upper limit. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ or the like as a raw material.

The ZnO component is a component which lowers the glass transition temperature (Tg) and improves chemical durability, and is an optional component in the optical glass of the present invention. However, when the content of the ZnO component is too large, the devitrification resistance of the glass is likely to deteriorate. Therefore, the content of the ZnO component is preferably 25.0% as the upper limit, more preferably 20.0% as the upper limit, and more preferably 15.0% as the upper limit, and more preferably the total amount of the ZnO component. To set 10.0% as the upper limit. In addition, even if the ZnO component is not contained, a glass having desired characteristics can be obtained. However, since the glass transition point is lowered by containing the ZnO component, pressure molding can be easily performed, and the optical glass can be easily obtained. Therefore, the content of the ZnO component is preferably more than 0% based on the total mass of the glass in terms of the oxide conversion composition, more preferably 0.1% is the lower limit, and most preferably 1.0% is the lower limit. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are components which improve the chemical durability of the glass and improve the devitrification resistance of the molten glass, and are arbitrary components in the optical glass of the present invention. In particular, by setting the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, the devitrification tendency of the glass can be weakened, and the durability of the glass can be improved. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0% as the upper limit, more preferably 8.0% as the upper limit, and most preferably 8.0%. Set 5.0% to the upper limit. The Al ₂ O ₃ component and the Ga ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga(OH) ₃ or the like as a raw material.

The Bi ₂ O ₃ component is a component which increases the refractive index and lowers the glass transition point (Tg) and is an optional component in the optical glass of the present invention. In particular, when the content of the Bi ₂ O ₃ component is 20.0% or less, the increase in the liquidus temperature is suppressed, so that the deterioration of the devitrification resistance of the glass can be suppressed. Further, by setting the content of the Bi ₂ O ₃ component to 20.0% or less, the coloring of the glass can be reduced. Therefore, the content of the Bi ₂ O ₃ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 10.0% as the upper limit. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ or the like as a raw material.

The TeO ₂ component is a component which increases 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 in a crucible made of platinum or in a molten bath formed of platinum in a portion in contact with molten glass. Therefore, the content of the TeO ₂ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and most preferably 10.0% as the upper limit. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ or the like as a raw material.

The SnO ₂ component is a component which is used for the oxidization of molten glass to clarify the molten glass and which is difficult to deteriorate the transmittance of the glass to 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 1.0% or less, it is possible to cause coloring of the glass due to reduction of the molten glass or devitrification of the glass. Further, since the alloying of the SnO ₂ component and the melting device (especially a noble metal such as Pt) is lowered, the life of the melting device can be prolonged. Therefore, the content of the SnO ₂ component is preferably 1.0% as the upper limit, more preferably 0.7% as the upper limit, and most preferably 0.5% as the upper limit, based on the total mass of the glass in the oxide conversion composition. 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. When the amount of Sb ₂ O ₃ is too large, the transmittance in the short-wavelength region of the visible light region is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% as the upper limit, more preferably 0.7% as the upper limit, and most preferably 0.5% as the upper limit. 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.

Further, the component for clarifying the glass and defoaming is not limited to the above Sb ₂ O ₃ component, and a known clarifying agent, antifoaming agent or a combination thereof may be used in the field of glass production.

<About ingredients that should not be included>

Next, the components which should not be contained in the optical glass of the present invention and the components which are preferably not contained will be described.

Other ingredients may be added as needed insofar as they do not impair the characteristics of the glass of the invention of the present application. Among them, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, each of the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo is either alone or When it is compounded and contained in a small amount, it also has a property of absorbing glass and absorbing a specific wavelength in the visible light range, and particularly preferably, optical glass having a wavelength of a visible region is substantially not contained.

Further, since a lead compound such as PbO or an arsenic compound such as As ₂ O ₃ is a component having a high environmental load, it is preferable that it is substantially not contained, that is, it is not contained except for inevitable mixing.

Further, the components of Th, Cd, Tl, Os, Be, and Se have been in a controlled use as harmful chemical materials in recent years, and it is considered that not only the manufacturing steps of the glass but also the processing steps and the post-product processing require an environment. Countermeasures. Therefore, when it is important to pay attention to the influence of the environment, it is preferable that it does not substantially contain such.

The glass composition of the present invention is represented by the mass % of the total mass of the glass in terms of oxide composition, and therefore cannot be directly expressed by the description of the mole %, but in the present invention, it satisfies the requirements The composition of each of the glass compositions of various characteristics in terms of mole % is approximately the following value in terms of oxide composition.

B ₂ O ₃ component 2.0~55.0 mol%, and

La ₂ O ₃ component 5.0~35.0 mol%,

as well as

Ta ₂ O ₅ component 0~10.0 mol% and/or

TiO ₂ component 0~30.0 mol% and / or

Nb ₂ O ₅ component 0~15.0 mol% and / or

WO ₃ component 0~30.0% and/or

SiO ₂ component 0~50.0 mol% and/or

ZrO ₂ component 0~18.0 mol% and / or

Gd ₂ O ₃ composition 0~25.0% by mole and/or

Y ₂ O ₃ component 0~20.0 mol% and/or

Yb ₂ O ₃ composition 0~10.0 mol% and / or

MgO composition 0~50.0 mol% and / or

CaO composition 0~40.0 mol% and / or

SrO composition 0~30.0% by mole and/or

BaO composition 0~35.0% by mole and/or

Li ₂ O composition 0~30.0 mol% and/or

Na ₂ O composition 0~25.0% by mole and/or

K ₂ O composition 0~20.0 mol% and/or

Cs ₂ O composition 0~10.0 mol% and / or

P ₂ O ₅ component 0~15.0 mol% and/or

GeO ₂ component 0~10.0 mol% and / or

ZnO composition 0~50.0 mol% and / or

Al ₂ O ₃ composition 0~15.0 mol% and/or

Ga ₂ O ₃ component 0~5.0 mol% and/or

Bi ₂ O ₃ composition 0~10.0 mol% and/or

TeO ₂ component 0~25.0% by mole and/or

Sb ₂ O ₃ composition 0~0.5 mol%

[Production method]

The optical glass of the present invention can be produced, for example, in the following manner. That is, the raw materials are uniformly mixed so that the respective components are within a specific content range, and the produced mixture is put into a platinum crucible, and the melting difficulty of the glass composition is utilized in an electric furnace at a temperature range of 1100 to 1500 ° C. After melting for 2 to 5 hours, the mixture is homogenized, and then lowered to an appropriate temperature, and then cast into a mold and cooled to thereby produce.

[physical property]

The optical glass of the present invention must have a high refractive index (n _d ) and a low dispersion. In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75 as the lower limit, more preferably 1.80 as the lower limit, and further preferably 1.82 as the lower limit, and most preferably 1.85 as the lower limit. . Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably such that 30 is the lower limit, more preferably 35 is the lower limit, and further preferably 37 is the lower limit, and most preferably 39 is set. The lower limit is preferably an upper limit of 50, more preferably an upper limit of 47, and most preferably an upper limit of 45. Thereby, the degree of freedom of the optical design can be increased, and even if the thickness of the element is reduced, a large amount of refraction of light can be obtained. Further, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is, for example, 2.00 or less, more specifically 1.98 or less, and more specifically 1.95 or less.

Further, in the optical glass of the present invention, even if the content of the Ta ₂ O ₅ component is small, the devitrification resistance is high. In particular, the optical glass of the present invention preferably has a lower liquidus temperature of 1300 ° C or lower. More specifically, the liquidus temperature of the optical glass of the present invention is preferably 1300 ° C as the upper limit, more preferably 1280 ° C as the upper limit, and most preferably 1250 ° C as the upper limit. Thereby, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is lowered, so that the devitrification resistance when the glass is formed from the molten state can be improved, and the optical characteristics of the optical element using the glass can be lowered. The impact. Moreover, since the range of the temperature at which the glass can be stably formed is widened, even if the melting temperature of the glass is lowered, the glass can be molded, and the energy consumed at the time of molding the glass can be suppressed. 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 about 500 ° C or higher, specifically 550 ° C or higher, and more specifically More than 600 ° C or more. In addition, the "liquidus temperature" in the present specification means that 30 cc of a glassy glass sample is placed in a platinum crucible in a 50 ml capacity platinum crucible, and is completely molten at 1350 °C. The temperature was lowered to a specific temperature for 12 hours, and after being taken out to the outside of the furnace for cooling, the presence or absence of crystals in the glass surface and the glass was observed immediately, and the lowest temperature of crystallization was not observed. Here, the specific temperature means a temperature set at every 20 ° C from 1300 ° C to 1160 ° C.

Further, the optical glass of the present invention preferably has less coloration. In particular, when the optical glass of the present invention is expressed by the transmittance of glass, the sample having a thickness of 10 mm indicates that the wavelength of the spectral transmittance is 70% (λ ₇₀ ) is 450 nm or less, more preferably 430 nm or less. Good for 400 nm or less. Further, the wavelength (λ ₅ ) indicating that the spectral transmittance is 5% is 400 nm or less, more preferably 380 nm or less, and most preferably 360 nm or less. Thereby, since the absorption limit of the glass is in the vicinity of the ultraviolet region, the transparency of the glass in the visible light range is improved, so that the optical glass can be preferably used as a material of an optical element such as a lens.

Further, the optical glass of the present invention preferably has a lower partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the optical glass of the present invention satisfy (-2.50 × 10 ^-3 × ν _d + 0.6571) ≦ (θg, F) ≦ The relationship between (-2.50×10 ^-3 × ν _d +0.6971). Since the optical glass having a small partial dispersion ratio (θg, F) can be obtained by this, the chromatic aberration of the optical element formed by the optical glass can be reduced. The partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably such that (-2.50 × 10 ^-3 × ν _d + 0.6571) is the lower limit, and more preferably (-2.50 × 10 ^-3 × ν _d + 0.6591) is set as the lower limit, and it is preferable to set (-2.50 × 10 ^-3 × ν _d + 0.6611) as the lower limit. On the other hand, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably such that (-2.50 × 10 ^-3 × ν _d + 0.6971) is the upper limit, and more preferably (-2.50 × 10 ^{-3 ).} ×ν _d +0.6921) is the upper limit, and it is preferable to set (-2.50 × 10 ^-3 × ν _d + 0.6871) as the upper limit.

[Glass molded body and optical element]

The glass molded body can be produced from the produced optical glass by means of, for example, a grinding process or a mold pressure forming method such as reheating pressure forming or precision press forming. In other words, the optical glass can be subjected to mechanical processing such as grinding and polishing to produce a glass molded body, or the preform made of optical glass can be subjected to reheating and pressure forming, followed by polishing to prepare a glass molded body, and polishing can be performed. The produced preform or the preform formed by known floating forming or the like is subjected to precision press forming to produce a glass molded body. Furthermore, the means for producing the glass molded body is not limited to these means.

Thus, the glass molded body formed by the optical glass of the present invention can be used for various optical components and optical designs. Among them, it is particularly preferable to use an optical element such as a lens or a crucible. By this, it is possible to form a glass molded body having a large diameter, and it is possible to increase the size of the optical element, and to realize high-definition and high-precision imaging characteristics and projection characteristics when used in an optical device such as a camera or a projector.

[Examples]

The compositions of the examples (No. 1 to No. 285), the reference examples (No. A to No. B), and the comparative examples (No. A to No. B) of the present invention, and the refractive indices of the glasses ( Nd), Abbe number (ν _d ), partial dispersion ratio (θg, F), liquidus temperature, and the wavelengths indicating the spectral transmittance of 5% and 70% (λ ₅ and λ ₇₀ ) are shown in the table. 1~ Table 38. Further, the following examples are for illustrative purposes only and are not limited to the examples.

Any of the glasses of the examples (No. 1 to No. 285), the reference examples (No. A to No. B), and the comparative examples (No. A to No. B) of the present invention are each selected to have appropriate oxidation. A high-purity raw material used for ordinary optical glass such as a substance, a hydroxide, a carbonate, a nitrate, a fluoride, a hydroxide, or a metaphosphoric acid compound is used as a raw material of each component, and is represented by each of Tables 1 to 38. The ratio of the composition of the examples is weighed and uniformly mixed, and then poured into a platinum crucible. The melting difficulty of the glass composition is melted in an electric furnace at a temperature of 1100 to 1500 ° C for 2 to 5 hours, and then stirred and homogenized. After casting into a mold or the like and cooling, the glass is produced.

Here, in the examples (No. 1 to No. 285), reference examples (No. A to No. B), and comparative examples (No. A to No. B), the refractive index (n _d ) of the glass, Abbe The number (ν _d ) and the partial dispersion ratio (θg, F) were measured based on the Japanese Optical Glass Industry Association specification JOGIS01-2003. Further, for the values of the obtained Abbe number (ν _d ) and the partial dispersion ratio (θg, F), the relationship a (θg, F) = - a × ν _d + b is obtained when the slope a is 0.0025. Intercept b. Here, the refractive index (n _d ), the Abbe number (ν _d ), and the partial dispersion ratio (θg, F) are determined by measuring the glass obtained by setting the slow cooling rate to −25° C./hr. Out.

Moreover, the penetration ratio of the glass of the examples (No. 1 to No. 285), the reference examples (No. A to No. B), and the comparative examples (No. A to No. B) was based on the Japan Optical Glass Industry Association. It is measured by the specification JOGIS02. Furthermore, in the present invention, the presence or absence of the color of the glass is determined by measuring the transmittance of the glass. Specifically, a face to face parallel polishing product having a thickness of 10 ± 0.1 mm is used to measure the light transmittance of 200 to 800 nm based on JIS Z8722, and λ _{5 is} obtained (the penetration rate is 5%). Wavelength) and λ ₇₀ (wavelength at 70% penetration).

Further, the liquid phase temperatures of the glasses of the examples (No. 1 to No. 285), the reference examples (No. A to No. B), and the comparative examples (No. A to No. B) were in platinum of 50 ml capacity. In the crucible, a 30 cc glass-like glass sample was placed in a platinum crucible, and completely melted at 1350 ° C, and cooled to a temperature of 1300 ° C to 1160 ° C at any temperature set at 20 ° C. After maintaining for 12 hours, the mixture was taken out to the outside of the furnace for cooling, and the presence or absence of crystals on the surface of the glass and the glass was directly observed, and the lowest temperature at which no crystallization was observed was determined.

As shown in Tables 1 to 38, in any of the optical glasses of the examples (No. 1 to No. 285) of the present invention, the liquidus temperature is 1300 ° C or lower, and more specifically, 1260 ° C or lower. , within the expected range. Therefore, it is understood that the optical glass of the embodiment of the present invention has a low liquidus temperature. In addition, since any of the reference examples (No. A to No. B) and the comparative examples (No. A to No. B) were devitrified, it was estimated that the liquidus temperature was higher.

Further, in the optical glass of the embodiment of the present invention, any of λ ₇₀ (wavelength at a transmittance of 70%) is 420 nm or less, and more specifically 405 nm or less. Further, in the optical glass of the embodiment of the present invention, any of λ ₅ (wavelength at a transmittance of 5%) is 400 nm or less, and more specifically 360 nm or less. Therefore, it is understood that the optical glass of the embodiment of the present invention is difficult to color.

Further, in the optical glass of the embodiment of the present invention, the refractive index (n _d ) of any of them is 1.75 or more, more specifically 1.86 or more, and the refractive index (n _d ) is 2.00 or less, more detailed. In the case of 1.97 or less, it is within the desired range.

Further, in the optical glass of the embodiment of the present invention, the Abbe number (ν _d ) of any of the optical glasses of the present invention is 30 or more, and the Abbe number (ν _d ) is 50 or less, and more specifically 42 or less. Within the expected range.

Further, in the optical glass of the embodiment of the present invention, the partial dispersion ratio (θg, F) of either one is (-2.50 × 10 ^-3 × ν _d + 0.6571) or more, and more specifically (-2.50) ×10 ^-3 × ν _d +0.6665) or more. On the other hand, the partial dispersion ratio of the optical glass of the embodiment of the present invention is (-2.50 × 10 ^-3 × ν _d + 0.6971) or less, and more specifically (-2.50 × 10 ^-3 × ν _d + 0.6813) the following. Therefore, it can be seen that the partial dispersion ratios (θg, F) are within the desired range.

Therefore, it is understood that the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass of the embodiment of the present invention are within a desired range, and can be produced at low cost, with high devitrification resistance and less coloration. .

Further, the glass brick is formed using the optical glass of the embodiment of the present invention, and the glass brick is ground and polished to be processed into a shape of a lens and a crucible. As a result, it can be stably processed into various lenses and shapes of the crucible.

The present invention has been described in detail with reference to the preferred embodiments of the present invention.

Claims (20)

An optical glass comprising, by mass%, 1.0 to 30.0% of a B ₂ O ₃ component and 10.0 to 55.0% of a La ₂ O ₃ component, and a content of a Ta ₂ O ₅ component, relative to an oxide-converted composition. 9.5% or less, the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 21.0% or less. The optical glass of claim 1, which contains at least one selected from the group consisting of a TiO ₂ component, a Nb ₂ O ₅ component, and a WO ₃ component in an oxide-converted composition. The optical glass according to claim 2, wherein a sum of a content of one or more selected from the group consisting of a TiO ₂ component, a Nb ₂ O ₅ component, and a WO ₃ component is 0.5% or more based on the total mass of the oxide-converted composition. 40.0% or less. The optical glass of claim 2, which contains, by mass%, TiO ₂ component 0 to 20.0% and/or Nb ₂ O ₅ component 0 to 20.0% and/or WO ₃ with respect to the total mass of the oxide-converted glass. The composition is 0~25.0%. The optical glass of claim 1 further contains, in mass%, the following components in terms of mass%: 0 to 20.0% of the SiO ₂ component and/or 0 to 12.0% of the ZrO ₂ component. The optical glass of claim 1, wherein the mass ratio of the oxide-converted composition (ZrO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ ) / (B ₂ O ₃ + SiO ₂ ) is 2.00 or less. The optical glass of claim 1 which further contains, in mass%, the following components in terms of mass % of the glass of the oxide composition: 0 to 45.0% of the Gd ₂ O ₃ component and/or 0 to 30.0 of the Y ₂ O ₃ component. % and / or Yb ₂ O ₃ components 0 ~ 20.0%. The optical glass of claim 1, wherein the mass of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) and the total amount of the glass in terms of oxide conversion The mass is 30.0% or more and 75.0% or less. The optical glass of claim 8, wherein the mass of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) and the total amount of the glass in terms of oxide conversion The quality is more than 40.0%. The optical glass of claim 1, wherein the mass ratio of the oxide-converted composition is Ta ₂ O ₅ /(Ln ₂ O ₃ +ZrO ₂ +Nb ₂ O ₅ +WO ₃ ) is 0.300 or less (wherein Ln is selected from La One or more of the groups consisting of Gd, Y, and Yb). The optical glass of claim 1 which further contains, in mass%, the following components in terms of mass% of the glass: 0 to 20.0% of the MgO component and/or 0 to 20.0% of the CaO component and/or the SrO component. 0~20.0% and/or BaO composition 0~25.0%. The optical glass of claim 11, wherein the mass of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) and the total mass of the glass in terms of oxide conversion are 25.0. %the following. The optical glass of claim 1, which further contains, in mass%, the following components in terms of mass% of the glass: 0 to 10.0% of the Li ₂ O component and/or 0 to 10.0% of the Na ₂ O component, and / or K ₂ O composition 0 ~ 10.0% and / or Cs ₂ O composition 0 ~ 10.0%. The optical glass of claim 13, wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) and the total mass of the glass in terms of oxide conversion It is 15.0% or less. The optical glass of claim 1, wherein the mass ratio of the oxide-converted composition (B ₂ O ₃ + SiO ₂ + WO ₃ ) / (Ln ₂ O ₃ + ZrO ₂ + Li ₂ O) is 0.20 or more and 2.00 or less (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb. The optical glass of claim 1, which further contains, in mass%, the following components in terms of mass % of P ₂ O ₅ component 0 to 10.0% and/or GeO ₂ component 0 to 10.0%, and / or ZnO component 0 ~ 25.0% and / or Al ₂ O ₃ component 0 ~ 10.0% and / or Ga ₂ O ₃ component 0 ~ 10.0% and / or Bi ₂ O ₃ component 0 ~ 20.0% and / or TeO ₂ composition 0~20.0% and/or SnO ₂ component 0~1.0% and/or Sb ₂ O ₃ component 0~1.0%. The optical glass of claim 1, which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more and 50 or less. The optical glass of claim 1, which has a liquidus temperature of 1300 ° C or lower. An optical element having the optical glass according to any one of claims 1 to 18 as a base material. An optical machine having the optical component of claim 19.