TWI780088B - Optical glasses, preform structures, and optical elements - Google Patents

Abstract

The invention provides an optical glass, a preformed body material and an optical element. The optical glass has the optical properties of high refractive index and high dispersion, the partial dispersion ratio is high, and the production cost of the glass is low. The optical glass contains, by mass %, _La2O3 components greater _than 0% to 35.0%, _TiO2 components greater than 0% to 45.0%, and BaO components greater _{than 0} % to 45.0%, _SiO2 components and B2O3 components The total amount of TiO 2 /(TiO 2 +BaO) is not less than 5.0% and not more than 30.0%, the mass ratio of TiO ₂ /(TiO ₂ +BaO) is not less than 0.10 and not more than 0.90, and has an optical constant in the following range: the refractive index (n _d ) is not less than 1.80, Abbe The number (ν _d ) is 35.0 or less, and the partial dispersion ratio (θ g,F) is 0.57 or more.

Description

Optical glass, preform structure and optical element

The present invention relates to optical glass, preform and optical element.

In recent years, the digitalization of devices using optical systems, and the high-definition of images and videos are rapidly developing. In particular, the high-definition of images and videos is extremely prominent in optical devices such as digital cameras, video recorders, and projectors. In addition, at the same time, weight reduction and miniaturization can be achieved by reducing the number of optical elements, such as lenses and lenses, incorporated in the optical system of these optical devices.

Among the optical glasses used for making optical elements, the demand for high-refractive-index and high-dispersion glasses with a high refractive index (n _d ) of 1.80 or higher and a low Abbe number (ν _d ) of 15.0 or higher and 35.0 or lower is increasing, because The optical glass can reduce the weight and miniaturization of the optical system as a whole. As such a high-refractive-index high-dispersion glass, a glass composition represented by Patent Document 1 is known.

[Prior Art Literature]

[Patent Document]

Patent Document 1: Japanese Unexamined Patent Publication No. 2010-215503.

Patent Document 2: Japanese Unexamined Patent Publication No. 2011-178571.

However, in the glass described in Patent Document 1, in order to promote high refractive index and high dispersion, the content of rare earth such as Nb ₂ O ₅ components and La ₂ O ₃ components is large, and there is a problem that the production cost becomes high. Therefore, it is desired to have an optical glass that not only has high refractive index/high dispersion, but also has low production cost.

On the other hand, regarding the correction of the aberration (secondary spectrum) in the blue region among the chromatic aberrations, the partial dispersion ratio (θ g,F) is used as an index of optical characteristics that is important in optical design. The partial dispersion ratio (θ g, F) can be represented by the following formula 1).

θ g,F=(n _g -n _F )/(n _F -n _C ). ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． (Formula 1)

Here, in an optical system that corrects chromatic aberration by combining a convex lens with low dispersion and a concave lens with high dispersion, an optical material with a small partial dispersion ratio (θ g, F) is used for the lens on the low dispersion side. The lens on the high dispersion side uses an optical material with a large partial dispersion ratio (θ g, F), and by combining these optical materials, the secondary spectrum can be corrected.

However, even though the glass described in Patent Document 2 has a high refractive index and high dispersion, it is expensive to produce because Ta ₂ O ₅ is an essential component, and the glass has a small partial dispersion ratio, so it is used as a correction Lenses for the secondary spectrum are deficient. In other words, in addition to having a high refractive index ( _nd ) and a low Abbe number (ν _d ), the optical glass still expects to have a large partial dispersion ratio.

In view of the above problems, the object of the present invention is to provide an optical glass with high refractive index and high dispersion and low production cost, as well as a preform and an optical element using the optical glass.

Furthermore, the object of the present invention is to provide an optical glass which has a high refractive index and high dispersion and is suitable for correcting chromatic aberration, and a preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the inventors of the present invention focused on accumulating the results of experimental studies, and found that by adjusting the total amount of the SiO ₂ component and the B ₂ O ₃ component while using the La ₂ O ₃ component, the TiO ₂ component, and the BaO component together, , or the mass ratio of TiO ₂ /(TiO ₂ +BaO), the desired high refractive index and high dispersion can be obtained, the production cost can be reduced, and the desired partial dispersion ratio can be obtained, thus completing the present invention.

Specifically, the present invention provides the following.

(1) An optical glass, based on oxide-based mass %, containing La ₂ O ₃ components greater than 0% to 35.0%, TiO ₂ components greater than 0% to 45.0%, and BaO components greater than 0% to 45.0%; SiO The total amount of ₂ components and B ₂ O ₃ components is 5.0% or more and 30.0% or less; the mass ratio of TiO ₂ /(TiO ₂ +BaO) is 0.10 or more and 0.90 or less; and has an optical constant in the following range: refractive index (n _d ) is 1.80 or more, the Abbe number (ν _d ) is 35.0 or less, and the partial dispersion ratio (θ g,F) is 0.57 or more.

(2) The optical glass according to (1), wherein the SiO ₂ component is 0% to 30.0% and the B ₂ O ₃ component is 0% to 30.0% in mass % based on oxide.

(3) The optical glass according to (1) or (2), wherein the ZnO component is 0% to 30.0%, the Y ₂ O ₃ is 0% to 15.0%, and the Nb ₂ The O ₅ composition is 0% to 25.0%, the Yb ₂ O ₃ composition is 0% to 15.0%, the Gd ₂ O ₃ composition is 0% to 15.0%, and the Bi ₂ O ₃ composition is 0% to 10.0%.

(4) The optical glass according to any one of (1) to (3), wherein (La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is calculated by mass % based on oxides. The mass sum of is greater than 0% and less than 40.0%.

(5) The optical glass according to any one of (1) to (4), wherein the Ln ₂ O ₃ component (in the formula, Ln is selected from La, Gd, Y, and Yb) is based on the mass % of oxides. The total amount of one or more types in a group) is more than 0% and 50.0% or less.

(6) The optical glass according to any one of (1) to (5), based on oxides, the ratio of TiO ₂ /(La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) The mass ratio is greater than 0 and less than or equal to 5.00.

(7) The optical glass according to any one of (1) to (6), wherein the Rn ₂ O component (in the formula, Rn is selected from the group consisting of Li, Na, and K) is based on the mass % of oxides. The mass sum of one or more of them) is 15.0% or less.

(8) The optical glass according to any one of (1) to (7), wherein the RO component (in the formula, R is selected from the group consisting of Mg, Ca, Sr, Ba The mass sum of one or more of them) is more than 0% and 45.0% or less.

(9) The optical glass according to any one of (1) to (8), which contains 0% to 20.0% of the ZrO2 component, ₀ % to 10.0% _of the WO3 component, Ta ₂ O ₅ composition 0% to 10.0%, MgO composition 0% to 15.0%, CaO composition 0% to 30.0%, SrO composition 0% to 30.0%, Li ₂ O composition 0% to 15.0%, Na ₂ O composition 0% % to 15.0%, K ₂ O composition 0~15.0%, P ₂ O ₅ composition 0~10.0%, GeO ₂ composition 0% to 10.0%, Al ₂ O ₃ composition 0% to 15.0%, Ga ₂ O ₃ composition 0 % to 15.0%, TeO ₂ composition 0% to 10.0%, SnO ₂ composition 0% to 3.0%, and Sb ₂ O ₃ composition 0% to 1.0%.

(10) A preform member made of the optical glass according to any one of (1) to (9).

(11) An optical element made of the optical glass according to any one of (1) to (9).

(12) An optical device comprising the optical element as described in (11).

According to the present invention, it is possible to provide an optical glass with high refractive index and high dispersion and low production cost, as well as a preform and an optical element using the optical glass.

Furthermore, according to the present invention, it is possible to provide an optical glass which has a high refractive index and high dispersion and is suitable for correcting chromatic aberration, and a preform and an optical element using the optical glass.

FIG. 1 is a schematic diagram of normal lines represented by rectangular coordinates with partial dispersion ratio (θ g, F) as the vertical axis and Abbe number (ν _d ) as the horizontal axis.

Fig. 2 is a schematic diagram of the relationship between the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) of the glass of the embodiment of the present invention.

The optical glass of the present invention, in terms of mass %, contains _La2O3 component greater _than 0% to 35.0%, _TiO2 component greater than 0% to 45.0%, and BaO component greater than ₀ % to 45.0%; _SiO2 component and B2 The total amount of O ₃ components is not less than 5.0% and not more than 30.0%; the mass ratio of TiO ₂ /(TiO ₂ +BaO) is not less than 0.10 and not more than 0.90; and has an optical constant in the following range: the refractive index (n _d ) is not less than 1.80 , the Abbe number (ν _d ) is 35.0 or less, and the partial dispersion ratio (θ g,F) is 0.57 or more.

According to the present invention, by adjusting the content of each component while using the La ₂ O ₃ component, the TiO ₂ component, and the BaO component together, a high refractive index and high dispersion of the glass can be expected, and the stability of the glass can be improved. Therefore, it is possible to provide an optical glass with high refractive index and high dispersion and low production cost, as well as a preform and an optical element using the optical glass.

In addition, by adjusting the content of each component, not only high refractive index and high dispersion of glass can be expected, but also the partial dispersion ratio of glass can be further increased. Therefore, it is possible to provide an optical glass that has a high refractive index and high dispersion and is suitable for correcting chromatic aberration, and a preform and an optical element using the optical glass.

[glass ingredient]

The composition range of each component which comprises the optical glass of this invention is as follows. In this specification, unless otherwise specified, the content of each component is represented by mass % with respect to the total mass of glass based on an oxide. Here, the "oxide standard" means that the oxides, compound salts, metal fluorides, etc. used as raw materials for the glass composition of the present invention are all decomposed into oxides when they are melted. The total mass of is set to 100% by mass to represent the composition of various components contained in the glass.

<About essential ingredients, optional ingredients>

The La ₂ O ₃ component is a component that can increase the refractive index of the glass and reduce the dispersion. In particular, by containing more than 0% of the La ₂ O ₃ component, a desired high refractive index can be obtained, and it is an essential component. Therefore, the lower limit of the content of the La ₂ O ₃ component is preferably greater than 0%, preferably 1.0%, more preferably 2.0%, still more preferably 3.0%, and still more preferably 4.5%.

On the other hand, by setting the content of the La ₂ O ₃ component to 35.0% or less, the devitrification resistance of the glass can be improved, the Abbe number can be reduced, the increase in the specific gravity of the glass can be suppressed, and the production cost can be reduced. Therefore, the upper limit of the content of the La ₂ O ₃ component is preferably 35.0%, more preferably 24.0%, more preferably 21.0%, and still more preferably 18.0%.

As the La ₂ O ₃ component, La ₂ O ₃ , La(NO ₃ ) ₃ ‧XH ₂ O (X is an arbitrary integer) and the like can be used as a raw material.

When the TiO ₂ component is more than 0%, the refractive index of the glass can be increased, the Abbe number can be lowered, the partial dispersion ratio can be increased, and the devitrification resistance can be improved. Therefore, the lower limit of the content of the TiO ₂ component is preferably greater than 0%, preferably 10.0%, more preferably 17.0%, further preferably 21.5%, and still more preferably 23.5%.

On the other hand, by reducing the content of the TiO ₂ component to 45.0% or less, the coloring of the glass can be reduced and the visible light transmittance can be increased. In addition, it is also possible to suppress devitrification caused by containing an excess TiO ₂ component. Therefore, the upper limit of the content of the TiO ₂ component is preferably 45.0%, more preferably 38.0%, more preferably 35.0%, and still more preferably 32.0%.

TiO ₂ component, TiO ₂ etc. can be used as a raw material.

When the BaO component is more than 0%, the refractive index and devitrification resistance of glass can be improved, and the essential component which can improve the meltability of a glass raw material. Therefore, the lower limit of the content of the BaO component is preferably greater than 0%, preferably 5.0%, more preferably 8.0%, and still more preferably 10.0%.

On the other hand, by making content of a BaO component 45.0 % or less, it becomes difficult to reduce the refractive index of glass, and can reduce devitrification of glass. Therefore, the upper limit of the content of the BaO component is preferably 45.0%, more preferably 35.0%, more preferably 32.0%, and still more preferably 30.0%.

As the BaO component, BaCO ₃ , Ba(NO ₃ ) ₂ and the like can be used as raw materials.

The sum (mass sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably at least 5.0% and at most 30.0%.

In particular, by setting this sum to 5.0% or more, it is possible to suppress a decrease in devitrification resistance due to a shortage of the B ₂ O ₃ component or the SiO ₂ component. Therefore, the lower limit of the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 5.0%, more preferably 10.0%, more preferably 13.0%, and still more preferably 15.0%.

On the other hand, by setting the sum to 30.0% or less, it is possible to suppress a decrease in the refractive index due to excessive inclusion of these components, and thus a desired high refractive index can be easily obtained. Therefore, the upper limit of mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 30.0%, more preferably 24.0%, more preferably 22.0%.

Here, the ratio (mass ratio) of the content of the TiO ₂ component to the sum of the contents of the TiO ₂ component and the BaO component is preferably 0.10 or more. Thereby, in addition to maintaining a high refractive index and high dispersion, the partial dispersion ratio can also be increased. Therefore, the lower limit of the mass ratio TiO ₂ /(TiO ₂ +BaO) is preferably 0.10, more preferably 0.30, more preferably 0.40, and still more preferably 0.45.

On the other hand, by making this mass ratio 0.90 or less, coloring of glass can be reduced, visible light transmittance can be improved, and devitrification can be suppressed. Therefore, the upper limit of the mass ratio TiO ₂ /(TiO ₂ +BaO) is preferably 0.90, more preferably 0.80, more preferably 0.75.

The SiO ₂ component is an arbitrary component that can improve the devitrification resistance when the content is more than 0%. Therefore, the lower limit of the SiO ₂ component content is preferably greater than 0%, preferably greater than 0.5%, more preferably greater than 1.0%, and even more preferably greater than 2.0%.

On the other hand, by making the content of the SiO ₂ component 30.0% or less, the SiO ₂ component can be easily melted in the molten glass, and melting at a high temperature can be avoided. Therefore, the upper limit of the content of the SiO ₂ component is preferably 30.0%, preferably 28.0%, more preferably 23.0%, further preferably 18.0%, and still more preferably 16.0%.

As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ and the like can be used as raw materials.

The B ₂ O ₃ component is an arbitrary component capable of forming a network structure inside the glass when its content is greater than 0%, promoting stable glass formation, and improving devitrification resistance. Therefore, the lower limit of the content of the B ₂ O ₃ component is preferably greater than 0%, preferably greater than 0.5%, more preferably greater than 1.0%, and even more preferably greater than 2.0%.

On the other hand, by making the content of the B ₂ O ₃ component 30.0% or less, the decrease in the refractive index can be suppressed, the Abbe number can be reduced, and the deterioration of the chemical durability can be suppressed. Therefore, the upper limit of the content of the B ₂ O ₃ component is preferably 30.0%, more preferably 28.0%, more preferably 25.0%, further preferably 23.0%, and still more preferably 20.0%.

As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ ‧10H ₂ O, BPO ₄ , etc. can be used as raw materials.

When the ZnO component is more than 0%, the meltability of glass can be improved, the glass transition point can be lowered, and the arbitrary component which can reduce devitrification. Therefore, the lower limit of the content of the ZnO component is preferably greater than 0%, preferably greater than 0.5%, more preferably greater than 1.0%, and even more preferably greater than 2.0%.

On the other hand, by setting the content of the ZnO component to 30.0% or less, it is possible to reduce a decrease in the refractive index or devitrification. Moreover, since the viscosity of molten glass can be improved by this, the occurrence of streaks of glass can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 30.0%, more preferably 23.0%, more preferably 17.0%, and still more preferably 14.0%.

As the ZnO component, ZnO, ZnF ₂ , etc. can be used as raw materials.

When the Y ₂ O ₃ component is more than 0%, the increase in the material cost of the glass can be suppressed, and an optional component that can increase the refractive index.

By making the content of the Y ₂ O ₃ component 15.0% or less, the decrease in the refractive index of the glass can be suppressed, the Abbe number can be reduced, and the devitrification resistance of the glass can be improved. Therefore, the upper limit of the Y ₂ O ₃ component content is preferably 15.0%, more preferably 10.0%, and more preferably 5.0%.

As a _{Y2O3 component} , _Y2O3 , _YF3 , _etc. can be used as a raw material.

When the Nb ₂ O ₅ component is more than 0%, the refractive index of the glass can be increased, the partial dispersion ratio of the glass can be increased, and the devitrification resistance can be improved. Therefore, the lower limit of the content of the Nb ₂ O ₅ component is preferably greater than 0%, preferably 0.5%, and more preferably 1.0%.

On the other hand, by setting the content of the Nb ₂ O ₅ component to 25.0% or less, it is possible to suppress a reduction in the devitrification resistance of the glass due to excessive Nb ₂ O ₅ content, or to suppress a reduction in the transmittance of visible light. , and can make the Abbe number smaller. Therefore, the upper limit of the content of the Nb ₂ O ₅ component is preferably 25.0%, more preferably 18.0%, more preferably 13.0%, and still more preferably 10.0%.

As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component that increases the refractive index of the glass and reduces the dispersion when the content is greater than 0%.

On the other hand, by making the content of the Yb ₂ O ₃ component 15.0% or less, the devitrification resistance of the glass can be improved and the production cost can be suppressed. Therefore, the upper limit of the content of Yb ₂ O ₃ is preferably 15.0%, more preferably 10.0%, more preferably 5.0%.

As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

When the Gd ₂ O ₃ component is more than 0%, the refractive index of the glass can be increased and the Abbe number can be increased.

On the other hand, by reducing the particularly expensive Gd ₂ O ₃ component among the rare earth elements to less than 15.0%, the material cost of the glass can be reduced, so that an even cheaper optical glass can be produced. Furthermore, this makes it possible to prevent the Abbe number of the glass from rising more than necessary. Therefore, the upper limit of the content of Gd ₂ O ₃ is preferably 15.0%, more preferably 10.0%, more preferably 5.0%.

As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , etc. can be used as raw materials.

The Bi ₂ O ₃ component is an arbitrary component capable of increasing the refractive index and lowering the glass transition point when the content thereof exceeds 0%.

On the other hand, by setting the content of the Bi ₂ O ₃ component below 10.0%, the devitrification resistance of the glass can be improved, the production cost can be suppressed, and the coloring of the glass can be reduced to increase the visible light transmittance. Furthermore, this makes it possible to prevent the Abbe number of the glass from rising more than necessary. Therefore, the upper limit of the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and more preferably 3.0%.

As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

In addition, in the optical glass of the present invention, the sum (mass sum) of the La ₂ O ₃ , Nb ₂ O ₅ , Gd ₂ O ₃ , and Yb ₂ O ₃ components is preferably 40.0% or less. Thereby, since content of these expensive components can be reduced, the material cost of glass can be suppressed. Therefore, the mass sum (La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ), the upper limit is preferably 40.0%, preferably 30.0%, more preferably 25.0%, and even more preferably 23.0%.

On the other hand, by containing the mass sum of these components greater than 0%, a desired high refractive index can be obtained. Therefore, the lower limit thereof is preferably greater than 0%, more preferably 5.0%, more preferably 8.0%.

The sum (mass sum) of Ln ₂ O ₃ components (wherein, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably greater than 0% and less than 50%.

In particular, since the refractive index of glass can be increased by setting this mass sum to more than 0%, glass with a high refractive index can be easily obtained. In addition, coloring of the glass can be reduced by this. Therefore, the lower limit of the mass sum of the contents of Ln ₂ O ₃ is preferably greater than 0%, more preferably 1.0%, more preferably 3.0%, and even more preferably 5.0%.

On the other hand, by setting the mass sum to 50.0% or less, the devitrification resistance can be improved, the production cost can be suppressed, and the Abbe number of the glass can be prevented from increasing more than necessary. Therefore, the upper limit of the mass sum of the contents of Ln ₂ O ₃ is preferably 50.0%, preferably less than 40.0%, more preferably 31.0%, further preferably 26.0%, and still more preferably 21.0%.

Here, the ratio (mass ratio) of the content of the TiO ₂ component to the sum of the contents of the La ₂ O ₃ component, Nb ₂ O ₅ component, Gd ₂ O ₃ component, and Yb ₂ O ₃ component is preferably greater than zero. Thereby, in addition to maintaining a high refractive index and high dispersion, a high partial dispersion ratio can also be obtained, and the production cost can be suppressed. Therefore, the lower limit of the mass ratio TiO ₂ /(La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is preferably greater than 0, preferably 0.50, more preferably 0.80, and even more preferably is 1.00.

On the other hand, by making this mass ratio 5.0 or less, coloring of glass can be reduced, visible light transmittance can be improved, and devitrification can be suppressed. Therefore, the upper limit of the mass ratio TiO ₂ /(La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is preferably 5.00, more preferably 4.00, more preferably 3.00, and even more preferably 2.80.

The total amount of Rn ₂ O components (wherein, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 15.0% or less. Thereby, the reduction in the refractive index of glass can be suppressed, and devitrification resistance can be improved. Therefore, the mass sum of Rn ₂ O components preferably has an upper limit of 15.0%, more preferably 10.0%, more preferably 5.0%.

The sum (mass sum) of the RO components (where R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably greater than 0% and less than 45.0%. Thereby, devitrification caused by containing an excess RO component can be reduced, and a decrease in the refractive index can be suppressed. Therefore, the mass sum of the content of the RO component preferably has an upper limit of 45.0%, preferably less than 40.0%, more preferably 38.0%, still more preferably less than 35.0%, and still more preferably 32.0%.

On the other hand, by making this mass sum larger than 0%, the meltability of a glass raw material and the stability of glass can be improved. Therefore, the lower limit of the total content of RO components is preferably greater than 0%, preferably 5.0%, more preferably 15.0%, and even more preferably greater than 20.0%.

When the ZrO ₂ component is more than 0%, it contributes to high refractive index and low dispersion of glass, and is an optional component that can improve the devitrification resistance of glass. Therefore, the lower limit of the content of the ZrO2 component is preferably greater than ₀ %, preferably 0.5%, and more preferably 1.0%.

On the other hand, by making the ZrO ₂ component 20.0% or less, it is possible to suppress the decrease in glass devitrification resistance caused by containing an excess ZrO ₂ component. Therefore, the upper limit of the content of the _ZrO2 component is preferably 20.0%, more preferably 15.0%, and more preferably 10.0%.

As the ZrO ₂ component, ZrO ₂ , ZrF ₄ , etc. can be used as raw materials.

When the WO ₃ component is more than 0%, the refractive index can be increased, the partial dispersion ratio can be increased, and the devitrification resistance of glass can be improved. In addition, the WO ₃ component is also a component capable of lowering the glass transition point. Therefore, the lower limit of the content of WO ₃ is preferably greater than 0%, preferably 0.1%, more preferably 0.3%, and even more preferably greater than 0.5%.

On the other hand, by setting the content of the WO ₃ component below 10.0%, it is possible to reduce glass coloring caused by the WO ₃ component and increase the visible light transmittance. Therefore, the upper limit of the content of WO ₃ is preferably 10.0%, preferably 5.0%, and more preferably 3.0%.

WO ₃ components, WO ₃ etc. can be used as raw materials.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of glass and improve devitrification resistance when the content thereof exceeds 0%.

On the other hand, by reducing the high-priced Ta ₂ O ₅ component to less than 10.0%, the material cost of the glass can be reduced, so it is possible to produce an optical glass with a lower price. In addition, by setting the content of the Ta ₂ O ₅ component below 10.0%, the melting temperature of the raw material can be lowered, and the energy required for melting the raw material can be reduced, thereby reducing the manufacturing cost of the optical glass. Therefore, the upper limit of the content of Ta ₂ O ₅ is preferably 10.0%, more preferably 8.0%, more preferably 5.0%. Especially from the viewpoint of making optical glass with a lower price, the upper limit of the content of Ta ₂ O ₅ is preferably 4.0%, more preferably 3.0%, more preferably less than 1.0%, and most preferably does not contain .

As a _Ta2O5 component, _{Ta2O5 etc.} can be _used as a raw material.

When the MgO component is more than 0%, it is an optional component that can improve the meltability of the glass raw material or the devitrification resistance of the glass.

On the other hand, by making the content of the MgO component 15.0% or less, it is possible to suppress a decrease in the refractive index or a decrease in devitrification resistance due to excessive inclusion of these components. Therefore, the upper limit of the content of the MgO component is preferably 15.0%, more preferably 10.0%, more preferably 5.0%.

As the MgO component, MgCO ₃ , MgF ₂ , etc. can be used as raw materials.

When the CaO component is more than 0%, the refractive index and devitrification resistance of glass can be improved and the meltability of glass raw material can be improved. Therefore, the lower limit of the content of the CaO component is preferably greater than 0%, preferably 0.5%, more preferably 1.5%, and even more preferably 3.0%.

On the other hand, by making content of a CaO component 30.0 % or less, it becomes difficult to reduce the refractive index of glass, and can reduce devitrification of glass. Therefore, the upper limit of the content of the CaO component is preferably 30.0%, preferably 25.0%, more preferably 20.0%, still more preferably 16.0%, and still more preferably 13.0%.

As the CaO component, CaCO ₃ , CaF ₂ , etc. can be used as raw materials.

When the SrO component is more than 0%, the refractive index and devitrification resistance of glass can be improved and the meltability of a glass raw material can be improved. Therefore, the lower limit of the content of the SrO component is preferably greater than 0%, more preferably 0.5%, more preferably 1.5%.

On the other hand, by making content of a SrO component 30.0 % or less, it becomes difficult to reduce the refractive index of glass, and can reduce devitrification of glass. Therefore, the upper limit of the content of the SrO component is preferably 30.0%, preferably 25.0%, more preferably 20.0%, further preferably 17.0%, and still more preferably 15.0%.

As the SrO component, SrCO ₃ and SrF ₂ can be used as raw materials.

Li ₂ O components, Na ₂ O components, and K ₂ O components are arbitrary components that can improve the meltability of glass when the content of at least any one of them exceeds 0%. In particular, the K ₂ O component is also a component that can further increase the partial dispersion ratio of glass.

_On the other hand, by reducing content of _Li2O component, Na2O component, or K2O component, it can suppress that the refractive index of glass _falls , and can reduce devitrification. In particular, reduction in the partial dispersion ratio of glass can be suppressed by reducing the content of the Li ₂ O component. Therefore, the content of at least any one of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component is preferably 15.0% or less, more preferably less than 10.0%, more preferably less than 5.0%.

As the Li ₂ O component, Na ₂ O component and K ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ etc. are used as raw materials.

When the P ₂ O ₅ component is more than 0%, it is an optional component that can improve glass devitrification resistance. Especially, by making content of a _P2O5 component 10.0% or less, the _fall of the chemical durability of glass, especially the fall of water resistance can be suppressed. Therefore, the upper limit of the content of P ₂ O ₅ is preferably 10.0%, more preferably 5.0%, and more preferably 3.0%.

As the P ₂ O ₅ component, Al(PO ₃ ) ₃ , Ca(PO ₃ ) ₂ , Ba(PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ , etc. can be used as raw materials.

The GeO ₂ component is an optional component that can increase the refractive index of glass and improve devitrification resistance when the content thereof is greater than 0%. However, since the raw material of GeO ₂ is expensive, if the amount of GeO 2 is used in a large amount, the cost of the material will increase, which will damage the cost reduction effect brought about by reducing the composition of Gd ₂ O ₃ or Ta ₂ O ₅ . Therefore, the upper limit of the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, more preferably 1.0%, and most preferably not contained.

GeO ₂ component, GeO ₂ etc. can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are arbitrary components that can improve the chemical durability of the glass and can improve the devitrification resistance of the glass when the content is greater than 0%.

On the other hand, by making the contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 15.0% or less, the reduction in glass devitrification resistance due to excessive inclusion of these components can be suppressed. Therefore, the upper limit of the respective contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0%, more preferably 8.0%, and more preferably 3.0%.

For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga(OH) ₃ , etc. can be used as raw materials.

The TeO ₂ component is an arbitrary component capable of increasing the refractive index and lowering the glass transition point when its content exceeds 0%.

However, when the glass raw material is placed in a platinum crucible or the part in contact with the molten glass is melted in a melting tank made of platinum, there is a problem that the TeO ₂ component may alloy with platinum. Therefore, the upper limit of the content of the TeO ₂ component is preferably 10.0%, more preferably 5.0%, more preferably 3.0%, and still more preferably not contained.

For the TeO ₂ component, TeO ₂ and the like can be used as raw materials.

When the F component is greater than 0%, the Abbe number of the glass can be increased, the glass transition point can be lowered, and the devitrification resistance can be improved.

However, if the content of the F component exceeds 10.0%, the volatilization amount of the F component will increase, so it becomes difficult to obtain stable optical constants, and it is difficult to obtain a homogeneous glass. In addition, the Abbe number can rise to a greater than desired extent. Here, the content of the F component is the total amount of F which is a fluoride in which a part or all of the oxides of one or more than two metal elements are substituted.

Therefore, the content of component F is preferably 10.0% or less, preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably not contained.

When the SnO ₂ component is more than 0%, the oxidation of the molten glass can be reduced to make the molten glass clear, and any component that is difficult to deteriorate the light transmittance of the glass.

On the other hand, by making the content of the SnO ₂ component 3.0% or less, glass coloring or glass devitrification due to reduction of molten glass is less likely to occur. In addition, due to the reduced alloying of the _SnO2 component with the melting equipment, especially precious metals such as Pt, the service life of the melting equipment can be expected to be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, preferably less than 2.0%, more preferably less than 1.0%, and still more preferably not contained.

As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ , etc. can be used as raw materials.

When the Sb ₂ O ₃ component is more than 0%, it is an optional component that can defoam the molten glass.

On the other hand, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, excessive foaming is less likely to occur, and alloying with melting equipment (particularly precious metals such as Pt) is reduced. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, preferably less than 0.5%, more preferably less than 0.3%, and still more preferably less than 0.1%.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, etc. can be used as raw materials.

In addition, the component that clarifies and defoams the glass is not limited to the above-mentioned Sb ₂ O ₃ component, and a clarifier, defoamer, or a combination thereof known in the field of glass production can be used.

<About ingredients that should not be contained>

Next, the components which should not be contained in the optical glass of this invention, and the components which should not be contained are demonstrated.

In the optical glass of the present invention, other components may be added as necessary within the range not affecting the properties of the glass of the present invention. However, the GeO ₂ component will improve the dispersion of the glass, so it is better not to contain it substantially.

In addition, various transition metal components other than Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, such as Hf, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, Ce, Nd etc., when they are contained alone or in a composite form, even a small amount will still color the glass and absorb light of a specific wavelength in the visible light region. Therefore, especially in optical glasses using wavelengths in the visible light region , it is better not to contain substantially.

In addition, lead compounds such as _PbO and arsenic _compounds such as As2O3, as well as components of Th, Cd, Tl, Os, Be, and Se, have been regarded as harmful chemical substances in recent years, and tend to be avoided. In the manufacturing steps of glass, even the processing steps and the treatment after productization, there must be disposal in response to environmental countermeasures. Therefore, from the viewpoint of emphasizing the impact on the environment, it is preferable not to contain these components substantially except for unavoidable contamination. Thereby, the optical glass can be substantially free from substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental countermeasures.

[Production method]

The optical glass of the present invention can be produced, for example, as follows. That is, make each component within the specified content range, mix the above-mentioned raw materials uniformly, put the prepared mixture into a platinum crucible, quartz crucible or alumina crucible for preliminary melting, and then put it into a gold crucible, platinum crucible, etc. In the crucible, platinum alloy crucible, or iridium crucible, it takes 1 hour to 5 hours to melt at a temperature range of 900°C to 1400°C, stir to homogenize it, and perform defoaming and other steps, then cool down to below 1200°C, and then It is produced by stirring in the final stage to remove streaks, and then shaping it with a forming die. Here, as a method of obtaining glass shaped using a shaping mold, there are, for example, a method of drawing molten glass from the other end of the shaping mold while pouring molten glass into one end of the shaping mold, or casting the molten glass on A method of slowly cooling the mold in the mold.

[property]

The optical glass of the present invention has high refractive index and high dispersion.

In particular, the lower limit of the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.80, more preferably 1.85, and more preferably 1.90. The upper limit of the refractive index is preferably 2.20 or less, more preferably 2.10 or less, and more preferably less than 2.05.

In addition, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 15.0 or more, preferably 20.0 or more, more preferably 21.0 or more, and even more preferably 22.0 or more, and the upper limit is 35.0 or less. Good, preferably below 30.0, more preferably below 27.0.

The optical glass of the present invention, since it has such a refractive index and Abbe number, can be used in optical design. In particular, in addition to expecting high imaging characteristics, etc., it is also possible to realize the miniaturization of the optical system, so that The degree of freedom in optical design increases.

The optical glass of the present invention preferably has a high transmittance of visible light, especially a high transmittance of short-wavelength light in visible light, thereby reducing coloring.

In particular, the optical glass of the present invention, if represented by the transmittance of the glass, represents the wavelength (λ ₇₀ ) of 70% of the spectral transmittance in a sample with a thickness of 10mm, and the upper limit is preferably 520nm, preferably 510nm, more preferably 500nm, and even more preferably 490nm.

In addition, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) representing a spectral transmittance of 5% in a sample with a thickness of 10mm is preferably 400nm, preferably 390nm, and more preferably 380nm.

As a result, the absorption edge of the glass becomes near the ultraviolet region, and the transparency of the glass to visible light can be improved. Therefore, this optical glass can be applied to optical elements such as lenses that allow light to pass through.

The optical glass of the present invention preferably has a high partial dispersion ratio (θ g,F). Specifically, the lower limit of the partial dispersion ratio (θ g, F) of the optical glass of the present invention is preferably 0.570, more preferably 0.580, more preferably 0.595, still more preferably 0.605, and still more preferably 0.612. In addition, the relationship between the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) of the optical glass of the present invention preferably conforms to (θ g, F)≧(-0.00162×ν _d +0.6450) Relationship.

Thus, the optical glass of the present invention still has a high partial dispersion ratio (θ g,F) even compared to conventional glasses containing many rare earth elements. Therefore, in addition to expecting a high refractive index and high dispersion of the glass, an optical element formed of this optical glass is also suitable for correcting chromatic aberration.

Here, the lower limit of the partial dispersion ratio (θ g, F) of the optical glass of the present invention is preferably (-0.00162×ν _d +0.6450), preferably (-0.00162×ν _d +0.6470), more preferably (-0.00162× _νd +0.6500). On the other hand, although the upper limit of the partial dispersion ratio (θ g, F) of the optical glass of the present invention is not particularly limited, it is mostly about (-0.00162 × ν _d + 0.6800), specifically (-0.00162 × ν _d +0.6700) or less, more specifically (-0.00162×ν _d +0.6650) or less. As long as the partial dispersion ratio (θ g, F) and Abbe number (ν _d ) of the glass with the specific composition of the present invention comply with this relationship, a stable glass can be obtained.

The relationship between the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) above is used in a rectangular coordinate with the partial dispersion ratio as the vertical axis and the Abbe number as the horizontal axis, which is parallel to the normal represented by a straight line. The normal line represents the linear relationship observed between the partial dispersion ratio (θ g,F) and the Abbe number (ν _d ) of glass known in the past, and the partial dispersion ratio (θ g,F) is used as On the vertical axis, the Abbe number (ν _d ) is on the rectangular coordinate of the horizontal axis, and it is expressed by a straight line connecting two points of the partial dispersion ratio and the Abbe number of NSL7 and PBM2 (please refer to Figure 1) . Furthermore, the conventionally known relationship between the partial dispersion ratio of glass and the Abbe number is roughly the same as that of the normal line.

Here, NSL7 and PBM2 are optical glasses manufactured by Ohara Co., Ltd., the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θ g, F) is 0.5828, and the Abbe number (ν _d ) of NSL7 is 60.5. The partial dispersion ratio (θ g, F) is 0.5436.

[Preforms and Optical Elements]

A glass molded body can be produced from the produced optical glass by a method such as grinding, or a compression molding method such as reheat press molding, precision press molding, or the like. That is, the glass molded body can be produced in the following manner: the glass molded body is produced by mechanical processing such as grinding and grinding of optical glass; Processing to produce glass moldings; preforms produced by grinding, or preforms formed by well-known floating molding, etc., are subjected to precision press molding to produce glass moldings, etc. However, the method of producing the glass molded article is not limited to the above.

Thus, the glass molded article formed from the optical glass of the present invention can function in various optical elements and optical designs, and is particularly suitable for use in optical elements such as lenses and lenses. By improving the stability of the glass, it is possible to form a glass molded body with a large diameter. Therefore, in addition to expecting an increase in the size of the optical element, it can also achieve high-definition and high-precision imaging characteristics when used in optical devices such as cameras. and projection properties.

In addition, by increasing the partial dispersion ratio, the optical element can be effectively used for chromatic aberration correction of the optical system. Therefore, for example, when the optical element is used in a camera, it is possible to express the subject of photography more accurately. Using the optical element When using a projector, the projected image can be presented more beautifully.

[Example]

The glass composition of the examples (No.1 to No.55) of the present invention, and the refractive index ( _nd ), Abbe number (ν _d ), transmittance (λ ₅ , λ ₇₀ ), and partial The values of the dispersion ratio (θ g, F) are shown in Table 1 to Table 10. In addition, the following examples are for illustrative purposes only, and the present invention is not limited to these examples.

In the glass of the embodiment, the raw materials of each component are selected from the high-purity raw materials used in general optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, meta-acid compounds, etc. , and then weigh the raw materials and mix them uniformly, put them into a platinum crucible, and use an electric furnace with a temperature set at 1250°C to 1300°C to melt the glass raw materials for 2 hours and stir the molten glass After the raw materials are defoamed, the temperature is lowered to 1080°C to 1180°C, stirred again to make it homogenized, then cast into a mold, and then slowly cooled to produce glass.

The refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θ g,F) of the glass in the examples are expressed as measured values relative to the d-line (587.56 nm) of the helium lamp. In addition, the Abbe's number (ν _d ) is the refractive index of the above-mentioned d-line, the refractive index (n _F ) of the F-line (486.13nm) of the hydrogen lamp, and the refractive index of the C-line (656.27nm) ( The value of n _C ) is calculated by the formula of Abbe's number (ν _d )=[(n _d -1)/(n _F -n _C )].

The partial dispersion ratio is determined by measuring the refractive index n _C in the C-line (wavelength 656.27nm), the refractive index n _F in the F-line (wavelength 486.13nm), and the refractive index ng in the _g -line (wavelength 435.835nm). Calculate the partial dispersion ratio from the formula (θ g, F)=(n _g -n _F )/(n _F -n _C ).

The transmittance of the glass of the example was measured according to JOGIS02-2003 standard of Japan Optical Glass Industry Association. In addition, in the present invention, whether the glass is colored or not and the degree of coloring is determined by measuring the transmittance of the glass. Specifically, the thickness of 10 ± 0.1mm relatively parallel abrasives, according to JISZ8722, measure the spectral transmittance of 200nm to 800nm, and obtain λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (Wavelength at 70% transmittance).

In addition, the glass used for this measurement was what was processed in the slow cooling furnace with the slow cooling temperature-fall rate set to -25 degreeC/hr.

As shown in the table, the optical glass of the embodiment of the present invention has a refractive index ( _nd ) of 1.80 or more, and the refractive index ( _nd ) is also 2.20 or less, more specifically, 2.10 or less, are all within the expected range.

In addition, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) of 35.0 or less, more specifically 30.0 or less, and the Abbe number (ν _d ) is also 15.0 or more, and more Specifically, it is 20.0 or more, and both are within the expected range.

In addition, the optical glass of the embodiment of the present invention has a partial dispersion ratio (θ g, F) of 0.570 or more, more specifically, 0.605 or more, which is a high partial dispersion ratio.

Furthermore, in the optical glass of the embodiment of the present invention, the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) conform to the relationship of (θ g, F)≧(-0.00162 ν _d +0.6450) , more specifically, it conforms to the relationship of (θ g, F)≧(-0.00162 ν _d +0.6500). Furthermore, the relationship between the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) of the glass of the embodiment of the present invention is shown in Fig. 2 .

It can be clearly seen from the above that the optical glass of the embodiment of the present invention has a large partial dispersion ratio (θ g, F), and the optical element obtained from the optical glass can play a role in correcting chromatic aberration.

Therefore, it can be clearly seen that the optical glass of the embodiment of the present invention has high refractive index and high dispersion, and has a high partial dispersion ratio, and is suitable for correcting chromatic aberration.

Furthermore, using the optical glass obtained in the embodiment of the present invention, after reheating and pressing, grinding and grinding were carried out, and then processed into the shape of a lens and an oval. In addition, using the optical glass of the example of the present invention, a preform for precision press molding was formed, and the preform for precision press molding was subjected to precision press molding. In any case, the heat-softened glass can be stably processed into a variety of lens and lens shapes without problems such as opalescence and devitrification.

Above, although the present invention has been described in detail for the purpose of illustration, the purpose of this embodiment is only for illustration, and those skilled in the art should understand that without departing from the spirit and scope of the present invention, The invention is still susceptible to many variations.

Claims (7)

An optical glass, in terms of mass % based on oxides, containing a _La2O3 component greater _than 0% to 35.0%; a _TiO2 component of 20.65% to 45.0%; a BaO component greater _{than 0} % to 45.0%; and a B2O3 component 0% to 17.56%; the total amount of SiO ₂ components and B ₂ O ₃ components is more than 5.0% to less than 30.0%; Ln ₂ O ₃ components (wherein, Ln is selected from the group consisting of La, Gd, Y, and Yb 1 or more in the group) the total amount is 5% to 50.0%; the mass ratio of TiO ₂ /(TiO ₂ +BaO) is 0.10 to 0.59; TiO ₂ /(La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) has a mass ratio of 0.51 or more and 3.00 or less; and has an optical constant in the following range: the refractive index (n _d ) is 1.80 or more, and the Abbe number (ν _d ) is 35.0 Hereinafter, the partial dispersion ratio (θg, F) is 0.57 or more. The optical glass as described in claim 1, wherein the SiO ₂ component is 0% to 30.0% based on the mass % of the oxide. The optical glass as described in claim 1 or 2, wherein the mass sum of (La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is greater than 0% based on mass % of oxides to below 40.0%. The optical glass as described in claim 1 or 2, wherein the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is based on the mass % of oxides. The mass sum is greater than 0% to less than 45.0%. A preform member made of the optical glass described in claim 1 or 2. An optical element made of the optical glass described in claim 1 or 2. An optical device comprising the optical element described in claim 6.

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