TW201841848A - Optical glass and optical element capable of preventing the quality of glass surface from being degraded so as to increase the chemical durability of glass - Google Patents

Abstract

The present invention provides an optical glass and an optical element. The above optical glass contains P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2- and F ^- as essential components, and the molar content of Al ³⁺ relative to the content of P ⁵⁺ The ratio (Al ³⁺ /P ⁵⁺ ) is 0.30 or more, the Nb ⁵⁺ content is 1.0 cation% or more, the O ^2- content is 10 to 85 anion %, the F ^- content is 15 to 90 anion %, O ^2- The molar ratio (O ^2- /(P ⁵⁺ +Nb ⁵⁺ )) of the content of R to the total content of P ⁵⁺ and Nb ⁵⁺ is 3.0 or more.

Description

Optical glass and optical components

The invention relates to an optical glass and an optical element.

A fluorophosphate glass containing phosphorus, oxygen, and fluorine is widely known as an optical glass having low dispersion and showing positive abnormal dispersion. Since the fluorophosphate glass has the above-mentioned excellent optical characteristics, it is highly useful as an optical element material for correcting high-order chromatic aberration. Examples of such a fluorophosphate glass are described in Patent Documents 1 to 4.

[Prior Art Document] [Patent Document] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-112717. Patent Document 2: Japanese Patent Application Laid-Open No. 2013-151410. Patent Document 3: Japanese Patent Application Laid-Open No. 51-114412. Patent Document 4: Japanese Patent Application Laid-Open No. 58-217451.

[Problems to be solved by the invention]

Although such a fluorophosphate glass has excellent optical characteristics, it exhibits significant volatility in a high-temperature step of melting and molding the glass. The volatilization from the glass melt during the melting and molding process may cause the deterioration of the glass, the change in the optical characteristics, and the decrease in the uniformity of the glass.

In addition, in the process of grinding and polishing a glass material formed of optical glass, and manufacturing optical elements such as a lens and a prism, the polished glass is usually cleaned. On the other hand, on the surface of polished glass, there are usually tiny flaws that are not visually recognizable and are called potential flaws. However, when the surface of the glass is eroded due to cleaning, the potential scars may expand and become visible and become a source of light scattering, and the surface quality of the glass may decrease. In addition, the surface quality of the glass may be reduced due to the deterioration of the glass surface due to cleaning. In the fluorophosphate glass, in order to suppress the degradation of the glass surface quality as described above, it is desirable to improve the chemical durability of the fluorophosphate glass.

An object of an embodiment of the present invention is to provide an optical glass having a low partial volatility and a high partial dispersion ratio and being suitable for correction of chromatic aberration while reducing the volatility of the fluorophosphate glass in the high-temperature step; and an optical element formed of the optical glass. .

In addition, an object of another aspect of the present invention is to provide an optical glass made of a fluorophosphate glass having excellent chemical durability and a large partial dispersion ratio and suitable for correction of chromatic aberration; and the above-mentioned optical glass Optical components. [Technical means to solve the problem]

An embodiment of the present invention relates to an optical glass (hereinafter also referred to as "optical glass 1"), which includes P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2-, and F ^- as essential components; Al ³⁺ the molar ratio of the content with respect to the content of P ⁵⁺ (Al ³⁺ / P ⁵⁺⁾ of 0.30 or more; Nb ⁵⁺ content is at least 1.0 cation%; O ^2- content of 10 to 85 anionic%; F ^- an amount of 15 to 90 anionic%; molar ratio ^{(O 2- / (P 5+ +} Nb 5+)) O ^2- content relative to the total content of Nb ⁵⁺ and P ⁵⁺ is less than 3.0.

The optical glass preferably has positive abnormal dispersion. As an index of positive anomalous dispersion, partial dispersion ratios Pg, F can be used. Partial dispersion ratios Pg, F use the refractive index nF at the F-line (wavelength 486.13nm), the refractive index nC at the C-line (wavelength 656.27nm), and the refractive index ng at the g-line (wavelength 435.84nm), as shown in the following formula . Pg, F = (ng-nF) / (nF-nC) ... (1) It is known that the intrinsic absorption wavelength of Nb contained in glass in the ultraviolet region is close to the visible light region, and the absorption intensity is also large. As a result, the wavelength dispersion of the refractive index shows a tendency of high dispersion. That is, the refractive index difference nF-nC of the F-line and the C-line tends to increase and the Abbe number νd decreases. On the other hand, the refractive index difference ng-nF of the g-line and the F-line also increases. Here, if the effect of increasing ng-nF is greater than the effect of increasing nF-nC, it can be known from the formula (1) that Pg, F increases. The present inventors paid attention to this point and found that the introduction of Nb as a glass component can significantly increase the partial dispersion ratio Pg, F while maintaining low dispersion (large νd) within the same range as that of the conventional fluorophosphate glass. . However, during the melting process of Nb-containing fluorophosphate glass, Nb is easily volatilized from the glass melt. When Nb and F are combined during the melting process, niobium fluoride is formed. Niobium fluoride has a high vapor pressure and is easily volatilized from glass melts. The present inventors conducted intensive studies in order to prevent Nb introduced for improving the partial dispersion ratio, and as a result, obtained the following findings. It is generally believed that P ⁵⁺ exists in the -OPO- structure in glass, which is helpful to the formation of the network of the glass. It is also believed that Nb ^{5+, which} has the same valence as P ^5+, also contributes to the formation of the glass network by occupying the position of P in the -OPO- structure. It is generally believed that when Nb ⁵⁺ is introduced into the network structure, it is difficult to produce niobium fluoride with a high vapor pressure, and as a result, the volatility of the glass is reduced. However, in order to introduce Nb ⁵⁺ into the network structure, a sufficient amount of O ^{2- is required} . When considering the presence of Nb ⁵⁺ , if the content of O ^2- is relative to the molar content of the total content of cations (P ⁵⁺ and Nb ⁵⁺ ) constituting the network (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 3.0 or more, Nb ^{5+ is} easily introduced into the network, thereby suppressing an increase in volatility. Based on the above findings, the present inventors have completed an optical glass according to an embodiment of the present invention.

Another embodiment of the present invention relates to an optical glass formed of a fluorophosphate glass; the mass reduction per unit area D _NaOH when immersed in an aqueous NaOH solution for 15 hours is less than 0.25 mg / (cm ² · 15h); In addition, the Abbe number νd and the partial dispersion ratio Pg, F satisfy the following formula (4): Pg, F> -0.0004νd + 0.5718 (4) formula. [Inventive effect]

According to an embodiment of the present invention, it is possible to provide optical glass suitable for correction of chromatic aberration while reducing the volatility of the fluorophosphate glass in the high-temperature step and having a large partial dispersion ratio; Optical element. In addition, according to another aspect of the present invention, it is possible to provide an optical glass that is a fluorophosphate glass with a large partial dispersion ratio, is suitable for correction of chromatic aberration, and has excellent chemical durability; Optical element.

In the present invention and the present specification, as long as the content and total content of the cationic component are not specifically described, they are expressed as cationic%, and as long as the content and total content of the anionic component are not specifically described, they are expressed as anionic%. Here, “cation%” means a value calculated by “(number of cations of interest / total number of cations in glass component) × 100”, and means a mole of the amount of cations of interest relative to the total amount of cation components percentage. In addition, "anion%" is a value calculated by "(number of anions of interest / total number of anions in glass component) x 100", and means a mole percentage of the amount of anions of interest with respect to the total amount of anion components . The molar ratio of the contents of the cationic components to each other is equal to the content ratio of the cationic component of interest in terms of cationic%, and the molar ratio of the contents of the anionic components to each other is equal to the content ratio of the anionic component of interest to the content expressed in% anion. The molar ratio of the content of the cationic component and the content of the anionic component is a ratio of the content of the components of interest (represented in mole%) when the total amount of all the cationic components and all the anionic components is 100 mole%. The content of each component can be quantified by a known method such as inductively coupled plasma emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and ion chromatography.

In addition, in this invention and this specification, "fluorophosphate glass" means the glass which contains at least phosphorus, oxygen, and fluorine as an element which comprises glass.

[Optical glass 1] <Glass component> Hereinafter, the optical glass 1 which concerns on one Embodiment of this invention is demonstrated. P ⁵⁺ functions as a network-forming component. Al ³⁺ is a component that functions to maintain the thermal stability of glass, improve chemical durability, and workability. From the aspect of maintaining good thermal stability of the glass, the content of Al ³⁺ with respect to the molar ratio of the content of P ⁵⁺ (Al ³⁺ / P ⁵⁺⁾ is 0.30 or more. It is effective to increase the refractive index while maintaining the Abbe number, and to set the molar ratio (Al ³⁺ / P ⁵⁺ ) to 0.30 or more. A preferable lower limit of the molar ratio (Al ³⁺ / P ⁵⁺ ) is 0.5. On the other hand, from the viewpoint of maintaining the thermal stability of glass well, a preferable upper limit of the molar ratio (Al ³⁺ / P ⁵⁺ ) is 2 and a more preferable upper limit is 1.

Nb ⁵⁺ acts as a network forming component together with P ⁵⁺ to maintain the thermal stability of the glass and increase the partial dispersion ratio. In order to obtain such an effect, the content of Nb ⁵⁺ is 1.0% or more. A preferred lower limit of the content of Nb ⁵⁺ is 1.5%, a more preferred lower limit is 2%, a further preferred lower limit is 2.5%, and a further preferred lower limit is 3%. On the other hand, when the content of Nb ⁵⁺ is excessive, the volatility when the glass is melted becomes significant, and the uniformity of the glass tends to decrease. Therefore, a preferable upper limit of the content of Nb ⁵⁺ is 15%, a more preferable upper limit is 13%, and a more preferable upper limit is 10%. The relationship between Nb ⁵⁺ and the chemical durability of glass will be described later.

From the viewpoint of maintaining the thermal stability of the glass, the total content of P ⁵⁺ and Nb ⁵⁺ (P ⁵⁺ + Nb ⁵⁺ ) is preferably 15% or more. A preferable lower limit of the total content of P ⁵⁺ and Nb ⁵⁺ (P ⁵⁺ + Nb ⁵⁺ ) is 20%.

O ^2- has the effect of maintaining the thermal stability of the glass. In order to obtain such an effect, the content of O ^2- is 10 anionic% or more. When the content of O ^2- is more than 85% of anion, the content of F ^- is insufficient, and it is difficult to obtain low dispersion. Therefore, the content of O ^2- is 10 to 85% of anion. The preferred lower limit of the content of O ^2- is 20%, the more preferred lower limit is 30%, the preferred upper limit is 80%, the preferred upper limit is 75%, the further preferred upper limit is 70.93%, A good upper limit is 70%.

F ^- has the effect of reducing the dispersion of the glass and imparting abnormal dispersion, reducing the glass transition temperature, and improving the chemical durability. When the content of F ^- to 15 anionic% is small, the above effect is difficult to obtain. On the other hand, when the content of F ⁻ exceeds 90 anionic%, it is difficult to maintain the thermal stability of the glass. When the content of F ⁻ is excessive, the values of D _NaOH , D _STPP , and D ₀ described below tend to increase. From the above point of view, F ^- the anion content of 15 to 90%. F ^- a preferred minimum content of 20%, the lower limit is more preferably 25%, more preferably lower limit of 28.86%, and further preferred lower limit is 30% upper limit is preferably 80%, more preferably The upper limit is 70%.

As described above, from the viewpoint of reducing the increase in volatilization from the glass melt due to the introduction of Nb ⁵⁺ , the molar ratio of the content of O ^2- to the total content of P ⁵⁺ and Nb ^{5+ 2-} / (P ⁵⁺ + Nb ⁵⁺ )) is 3.0 or more. The lower limit of the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is preferably 3.2. From the viewpoint of maintaining the thermal stability of the glass, a preferable upper limit of the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 4.0, and a more preferable upper limit is 3.8.

Alkaline earth metal components, namely Mg ²⁺ , Ca ²⁺ , Sr ^2+, and Ba ²⁺ are components that play a role in adjusting the viscosity and refractive index of glass and improving thermal stability. In order to obtain the above effects, the total content of alkaline earth metal components R ²⁺ (Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ ) is preferably 20 cation% or more, more preferably 30% or more, and even more preferably More than 35%. On the other hand, when the total content R ^{2+ of the} alkaline earth metal component is excessive, the thermal stability tends to decrease. Therefore, the total content R ²⁺ of the alkaline earth metal component is preferably 50% or less. A more preferable upper limit of R ²⁺ is 45%, and a more preferable upper limit is 40%.

The optical glass may include one or more rare earth components selected from La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ . While suppressing the increase of the specific gravity of the glass and reducing the dispersion for a certain refractive index, the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ^3+, and Yb ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) relative to the content of Al ³⁺ ((La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) It is preferably 0.3 or less. A more preferable upper limit of the molar ratio ((La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) is 0.2, and a more preferable upper limit is 0.1. The mole ratio ((La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) may also be 0.

Next, the content of each component will be described.

P ⁵⁺ is an essential component to form a network of glass. From the viewpoint of maintaining the thermal stability well, a preferable lower limit of the content of P ⁵⁺ is 5%, a more preferable lower limit is 10%, and a more preferable lower limit is 20%. From the viewpoint of maintaining good chemical durability, maintaining low dispersion, and abnormal partial dispersion, a preferable upper limit of the content of P ⁵⁺ is 40%, a more preferable upper limit is 38%, and a more preferable upper limit is 35. %.

Al ³⁺ is an essential component that exerts the effects of improving thermal stability, chemical durability, and workability, and also functions of increasing the refractive index. From the above point of view, the preferred lower limit of the content of Al ³⁺ is 5%, the more preferred lower limit is 7%, the further preferred lower limit is 9%, and the further preferred lower limit is 11%. From the above point of view, a preferred upper limit of the content of Al ³⁺ is 40%, a more preferred upper limit is 38%, a further preferred upper limit is 36%, and a further preferred upper limit is 34%.

In the glass composition expressed in atomic%, the ratio of the content of O ^{2- to} the content of Al ³⁺ O ² / Al ^{3+ is} preferably less than 12, more preferably less than 10, even more preferably less than 8. When the content of O ^2- is too large, the content of F ^- is relatively decreased, and the glass transition temperature tends to increase. On the other hand, as described above, Al ³⁺ is a useful component in order to improve thermal stability, chemical durability, and workability, and to have desired optical characteristics. In order to suppress the increase of the glass transition temperature while fully obtaining the effect of Al ³⁺ , it is preferable that the ratio of the content of O ^{2- to} the content of Al ³⁺ in the glass composition expressed as atomic% O ^2- / Al ³⁺ is the above range. From suppressing devitrification resistance decreases viewpoint since the content of Al ³⁺ caused by relative increase, regarding the lower limit of the above ratio O ^2- / Al ^3+, it is possible for example, 2 or more, or 3 or more as a reference. In addition, the content of each component in the glass composition expressed in atomic% may be a value expressed as a mole percentage when the total content of all cationic components and all anionic components is 100 mole%. Figure it out.

The preferable content of each component of ^{Mg2 +} , Ca2 ⁺ , Sr2 ⁺ , and Ba2 ⁺ is as follows. The preferable range of the content of Mg ²⁺ is 0 to 10%, and the more preferable range is 0 to 8%. The preferable range of the Ca ²⁺ content is 0 to 20%, and the more preferable range is 0 to 15%. The preferable range of the content of Sr ²⁺ is 0 to 40%, and the more preferable range is 0 to 30%. A preferred lower limit of the Ba ²⁺ content is 5%, a more preferred lower limit is 10%, a preferred upper limit is 50%, and a more preferred upper limit is 40%.

The preferable contents of La ³⁺ , Gd ³⁺ , Y ³⁺ , and Lu ³⁺ are as follows. The content of La ³⁺ is preferably in the range of 0 to 5%, and more preferably in the range of 0 to 3%. The preferable range of the content of Gd ³⁺ is 0 to 5%, and the more preferable range is 0 to 3%. The preferable range of the content of Y ³⁺ is 0 to 5%, and the more preferable range is 0 to 3%. The preferable range of the content of Lu ³⁺ is 0 to 5%, and the more preferable range is 0 to 3%.

Yb ³⁺ is not suitable for infrared-based imaging because it has light absorption in the infrared region. Therefore, as for the content of Yb ³⁺ , it is preferable to use a molar ratio (Yb ³⁺ / (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ )) to the total content of other rare earth components according to the following The method is restricted. That is, the preferred content of the Yb ³⁺ molar ratio of the total content of ^{La 3+, Gd 3+, Y 3+} , Lu 3+ and Yb ³⁺ is ^{(Yb 3+ / (La 3+ +} Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ )) is set to 0.5 or less, more preferably 0.1 or less, and even more preferably 0 (the content of Yb ³⁺ is 0%).

Zn ²⁺ has the effect of improving the thermal stability while maintaining the refractive index. However, if it is contained excessively, dispersion becomes high, and it is difficult to obtain desired optical characteristics. Therefore, the content of Zn ²⁺ is preferably set to a range of 0 to 10%. In order to obtain the above effect, a more preferable upper limit of the content of Zn ²⁺ is 8%, and a more preferable upper limit is 5%. The content of Zn ²⁺ may also be 0%.

An alkali metal component is a cationic component which has the effect | action which adjusts the viscosity of glass, and improves thermal stability. When the total content R ^{+ of the} alkali metal component is excessive, the thermal stability decreases. Therefore, a preferable range of the total content R ⁺ of the alkali metal component is 0 to 30%. From the above viewpoint, a more preferable range of R ⁺ is 0 to 20%, and a more preferable range is 0 to 15%. The upper limit of R ⁺ is more preferably 10%, even more preferably 8%, and still more preferably 7%. When the total content R ^{+ of the} alkali metal component is excessive, the values of D _STPP and D ₀ described below tend to increase. Therefore, from the viewpoint of imparting excellent chemical durability to glass, R ^{+ is} preferably in the above range. On the other hand, from the viewpoint of lowering the glass transition temperature, a preferable lower limit of R ⁺ is 1%, a more preferable lower limit is 2%, and a more preferable lower limit is 3%. Examples of the alkali metal component R ^{+ include} Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , and Cs ⁺ . Compared with other alkali metal components, Rb ⁺ and Cs ⁺ tend to cause the specific gravity of glass to increase. Therefore, the content of Rb ⁺ is preferably 0 to 3%, more preferably 0 to 2%, still more preferably 0 to 1%, and may also be 0%. The content of Cs ⁺ is preferably 0 to 3%, more preferably 0 to 2%, still more preferably 0 to 1%, and may also be 0%. From the viewpoint of maintaining the thermal stability of the glass, a preferable range of the Li ⁺ content is 0 to 30%, a more preferable range is 2 to 20%, and a more preferable range is 4 to 10%. From the viewpoint of maintaining the thermal stability of the glass, a preferable range of the content of Na ⁺ is 0 to 10%, a more preferable range is 0 to 8%, and a more preferable range is 0 to 6%. From the viewpoint of maintaining the thermal stability of the glass, a preferred range of the K ⁺ content is 0 to 10%, a more preferred range is 0 to 8%, and a more preferred range is 0 to 6%.

Si ⁴⁺ can be contained even in a small amount, but if it is contained in an excessive amount, meltability and thermal stability are reduced. Therefore, the content of Si ⁴⁺ is preferably set to a range of 0 to 5%, more preferably set to a range of 0 to 3%, still more preferably set to a range of 0 to 1%, and may also be set to 0%.

B ³⁺ shows significant volatility even when contained in small amounts. In order not to promote volatilization, the content of B ³⁺ is preferably set to 2% or less. The preferable range of the content of B ³⁺ is 0 to 1%, the more preferable range is 0 to 0.1%, and the more preferable range is 0%.

When molten glass flows out of a tube installed in a glass melting device, it is effective to contain Cl ^- in order to suppress wetting of the glass molten liquid to the outer periphery of the tube and to suppress degradation of the glass due to wetting. The preferable range of the content of Cl ^- is 0 to 1%, the more preferable range is 0 to 0.5%, and the more preferable range is 0 to 0.3%. Cl ^- has an effect as a refining agent.

In addition, a small amount of Sb ³⁺ , Ce ⁴⁺ and the like can be added as a clarifying agent. The total amount of the fining agent can be 0% or more, and preferably less than 1%. For example, the total content of Sb ³⁺ and Ce ⁴⁺ can be 0% or more, and preferably less than 1%.

Pb, Cd, As, and Th are components that may cause environmental burden. Therefore, it is preferable that the optical glass 1 does not substantially include at least one of Pb, Cd, As, and Th. The content of Pb ²⁺ is preferably 0 to 0.5%, more preferably 0 to 0.1%, still more preferably 0 to 0.05%, and particularly preferably not substantially containing Pb ²⁺ . The content of Cd ²⁺ is preferably 0 to 0.5%, more preferably 0 to 0.1%, still more preferably 0 to 0.05%, and particularly preferably not substantially containing Cd ²⁺ . The content of As ³⁺ is preferably from 0 to 0.1%, more preferably from 0 to 0.05%, even more preferably from 0 to 0.01%, and particularly preferably not substantially containing As ³⁺ . The content of Th ⁴⁺ is preferably 0 to 0.1%, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and particularly preferably does not substantially include Th ⁴⁺ .

The optical glass 1 is preferably capable of displaying high transmittance over a wide range of the entire visible light region. In order to effectively utilize such advantages, it is preferable that the optical glass does not contain a colorant. Examples of the colorant include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. The optical glass 1 preferably does not substantially include at least one of Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. The content of Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V in the range of cation% is preferably less than 100 ppm, more preferably 0 to 80 ppm, and still more preferably 0 to 50 ppm. It is particularly preferably not substantially included. Here, ppm is cationic ppm. In addition, Hf, Ga, Ge, Te, and Tb are expensive components. Therefore, the optical glass 1 preferably does not substantially include at least one of Hf, Ga, Ge, Te, and Tb. The content of Hf, Ga, Ge, Te, and Tb in the range of cationic% is preferably 0 to 0.1% for any element, more preferably 0 to 0.05%, still more preferably 0 to 0.01%, and further more It is preferably 0 to 0.005%, more preferably 0 to 0.001%, and particularly preferably not substantially contained. The optical glass described above can exhibit various characteristics without introducing Hf, Ga, Ge, Te, and Tb.

<Glass Characteristics> (Abbe Number νd, Refractive Index nd) In the optical glass 1 described above, the Abbe number νd is preferably in a range of 45 or more from the viewpoint of effectively utilizing the abnormal partial dispersion. The Abbe number νd is a value indicating properties related to dispersion, and each refractive index nd, nF, and nC at the d-line, F-line, and C-line is expressed as νd = (nd-1) / (nF-nC). A preferable upper limit of the Abbe number νd is 80, and a more preferable upper limit is 70. On the other hand, in order to effectively utilize the low dispersion property, a preferable lower limit of the Abbe number νd is 45, a more preferable lower limit is 50, and a more preferable lower limit is 55.

Furthermore, by setting the refractive index nd to be in the following range, it is possible to reduce the absolute value of the curvature of the optical functional surface of the lens (ease the curvature of the optical functional surface of the prism) while having the same condensing power. Whether it is precision press molding, grinding, or polishing, the gentler the curvature of the optical functional surface of the lens, the easier it is to manufacture. Therefore, the use of high-refractive-index glass can improve the productivity of optical elements. Furthermore, by increasing the refractive index, it is also possible to provide a glass material suitable for use in an optical element in a high-function, compact optical system. In the optical glass 1 described above, a preferable range of the refractive index nd is a range that satisfies the following formula (2), and a more preferable range of the refractive index nd is a range that satisfies the following formula (3). nd≥1.80653-0.00459 × νd ・ (2) formula nd≥1.84303-0.00459 × νd ・ (3) formula

In FIG. 1, expressions when the equal signs are established in the formulas (2) and (3) are shown. The optical glass 1 described above preferably exhibits positive abnormal dispersion. Anomalous dispersion can be expressed quantitatively using ΔPg, F. For the partial dispersion ratios Pg and F, each refractive index ng, nF, and nC at the g-line, the F-line, and the C-line can be used. -nC)). As commercially available low-dispersion glass having an Abbe number νd of 45 or more, FCD100, FCD515, etc. manufactured by HOYA are known. In the graph with the abscissa νd on the horizontal axis and the partial dispersion ratio Pg, F on the vertical axis, the FCD100 is plotted at the coordinates (95.1 0.5334), and the FCD515 is plotted at the coordinates (68.63 0.5441). Let us study the straight line L connecting the two points. This straight line L can be roughly expressed as "Pg, F = -0.0004 νd + 0.5718". A straight line L is illustrated in FIG. 2. As shown in FIG. 2, a commercially available low-dispersion glass (existing glass) having an Abbe number νd of 45 or more is located on the line of the straight line L or partially dispersed in the graph of the Abbe number νd-partial dispersion ratio Pg, F. One side smaller than Pg, F than the straight line L. With regard to the optical glass 1 described above, in a preferred embodiment, the Abbe number νd and the partial dispersion ratios Pg, F satisfy the following formula (4). Pg, F ＞ -0.0004νd + 0.5718 ・ ・ ・ (4) An optical glass with an Abbe number νd of 45 or more and satisfying the above formula (4), with respect to a specific Abbe number νd, the partial dispersion ratio is larger than Pg, F , Suitable for high-order chromatic aberration correction optical glass.

(Transmittance) The optical glass 1 is preferably a material having very little coloring, and is suitable as an optical element for imaging, such as a camera lens, and an optical element for projection, such as a projector. A preferable aspect of the optical glass 1 is a glass having a wavelength of 400 to 700 nm and an internal transmittance of 96.5% or more at a thickness of 10 mm. The preferable range of the above-mentioned internal transmittance is 97% or more, the more preferable range is 98% or more, and the more preferable range is 99% or more. In addition, glass containing laser light such as Nd, Eu, Er, V, and the like for laser light is not suitable for use in imaging optical elements such as camera lenses and projection optical elements because they have absorption in the visible light region. s material.

(Glass Transition Temperature Tg) The optical glass 1 is preferably an optical glass having a glass transition temperature Tg of 550 ° C or lower. When the glass transition temperature is low, the heating temperature when the glass is reheated and softened to perform press molding can be reduced. As a result, it becomes easy to suppress fusion | melting of glass and a press mold. In addition, since the heating temperature can be lowered, the heat consumption of a glass heating device, a press molding die, and the like can also be reduced. Furthermore, since the annealing temperature of glass can also be reduced, the life of an annealing furnace can be extended. A more preferable range of the glass transition temperature is 530 ° C or lower, and a more preferable range is 500 ° C or lower.

(Liquid Phase Temperature) A preferred embodiment of the optical glass 1 is an optical glass having a liquid phase temperature of 850 ° C or lower. When the liquidus temperature is low, the melting and molding temperature of the glass can be reduced. As a result, the volatility of the glass during melting and molding can be reduced, and the occurrence of streaks and changes in optical characteristics can be suppressed. A more preferred range of the liquidus temperature is 800 ° C or lower, and a more preferred range is 750 ° C or lower.

(Specific Gravity) The optical glass 1 described above can not rely on a rare earth that increases the partial dispersion ratio but also increases the specific gravity. Instead, it can mainly increase the partial dispersion ratio by containing Nb ^5+, and the fluorophosphate having a large partial dispersion ratio. The specific gravity in glass is relatively small. A preferred embodiment of the optical glass 1 is an optical glass having a specific gravity of 4.2 or less. By reducing the specific gravity, it is possible to reduce the weight of the optical element. A more specific range is 4.1 or less, and a more preferable range is 4 or less.

[Optical Glass 2] Hereinafter, an optical glass 2 according to an embodiment of the present invention will be described.

<Glass Characteristics> The Abbe number νd and the partial dispersion ratios Pg, F of the optical glass 2 satisfy the following formula (4). Pg, F> -0.0004νd + 0.5718 (4) The above-mentioned optical glass 2 in which the Abbe number νd and the partial dispersion ratio Pg, F satisfy the formula (4) is suitable as an optical glass for high-order chromatic aberration correction. In addition, in the optical glass 2 described above, the Abbe number νd is preferably in a range of 45 or more from the viewpoint of effectively utilizing the abnormal partial dispersion. A preferable upper limit of the Abbe number νd is 80, and a more preferable upper limit is 70. On the other hand, in order to effectively utilize the low dispersion, a more preferable lower limit of the Abbe number νd is 50, and a more preferable lower limit is 55.

<Chemical Durability> (D _NaOH ) The optical glass 2 described above has chemical durability when the amount of mass reduction D _NaOH per unit area when immersed in an aqueous NaOH solution for 15 hours is less than 0.25 mg / (cm ² · 15h). The mass reduction amount D _NaOH can be obtained by the following method. First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm was prepared. The opposite two surfaces with a diameter of 43.7mm are polished on both sides. As for the side, an adhesive tape (for example, polyimide tape, etc.) having chemical durability against an aqueous solution of sodium hydroxide (NaOH) described below is attached. Method of masking. Therefore, the two surfaces of the disc-shaped glass sample were exposed to an aqueous solution of sodium hydroxide (NaOH) described below. The total area of these two surfaces (hereinafter referred to as "surface area of the glass sample") is 30 cm ² . Subsequently, after measuring the mass M _before the glass specimen, the liquid temperature at 50 ℃, well stirred aqueous sodium hydroxide concentration of 0.01 mol / l of (NaOH) in glass sample was immersed for 15 hours was measured glass samples after immersion Of quality M _after . The value of the mass difference _{before and after} immersion (M _before -M _after ) (unit: mg) divided by the surface area of the glass sample was D _NaOH . That is, the value obtained by "(M _before -M _after ) / 30" is D _NaOH . The optical glass 2 has a chemical durability with D _{NaOH of} less than 0.25 mg / (cm ² · 15h). According to the optical glass having D _NaOH in the above range, it is possible to suppress a reduction in surface quality due to the appearance of a potential flaw or the like. From the viewpoint of maintaining high surface quality, D _{NaOH is} preferably less than 0.20 mg / (cm ² · 15h), and more preferably less than 0.10 mg / (cm ² · 15h). The lower limit of D _NaOH is not particularly limited, and, for example, 0.02 mg / (cm ² · 15h) or more can be considered as a reference.

(About D _A ) The optical glass 2 described above preferably has a chemical durability with a D _{A of} less than 0.35%. D _A is measured according to the measuring method of the acid-resistant weight loss rate Da prescribed by the Japan Optical Glass Industry Association standard JOGIS06-2009. Specifically, the measurement method is as follows. A powder glass (particle size 425 μm to 600 μm) with a mass (M _before , unit: g) equivalent to the specific gravity was placed in a platinum basket, and 80 ml of nitric acid at a concentration of 0.01 mol / l was immersed in a quartz glass round bottom flask The solution was treated in a boiling water solution for 60 minutes, and the mass M _after (unit: g) of the powder glass after the treatment was measured. Divide the mass difference of the powder glass before and after the treatment by the value of the mass of the powder glass before the treatment (M _before ‐M _after ) / M _before the result expressed as a percentage [(M _before ‐M _after ) / M _before ] × 100 Is D _A. The optical glass having D _A in the above range is suitable as a glass material for an optical element provided in a surveillance camera or an on-vehicle camera installed outdoors that requires excellent acid resistance. The lower limit of D _A is not particularly limited, and for example, 0.20% or more can be considered as a reference.

(About D _STPP ) The optical glass 2 preferably has a chemical durability with a D _{STPP of} less than 0.40 mg / (cm ² · h). The measurement method of D _STPP is as follows. First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm was prepared. The two opposite surfaces with a diameter of 43.7mm are polished on both sides, and the side surface is bonded by a method such as a polyimide tape that has chemical durability against an aqueous solution of sodium tripolyphosphate described below. Masking. Therefore, the two surfaces of the disc-shaped glass sample were exposed to an aqueous solution of sodium tripolyphosphate described below. The total area of these two surfaces (surface area of the glass sample) was 30 cm ² . Subsequently, the glass sample mass M _before the measurement, the well-stirred solution of l liquid temperature 50 ℃, a concentration of 0.01 mol / sodium tripolyphosphate (Na ₅ P ₃ O ₁₀₎ immersed for 1 hour was measured after the immersion of The mass of the glass specimen M _after . The value obtained by dividing the mass difference (M _before- M _after ) (unit: mg) _{before and after} immersion by the surface area and immersion time of the glass sample is D _STPP . That is, the value obtained by "(M _before -M _after ) / (30 × 1)" is D _STPP . The optical glass 2 more preferably has a chemical durability with a D _{STPP of} less than 0.20 mg / (cm ² · h). The lower limit of D _STPP is not particularly limited, and, for example, 0.02 mg / (cm ² · h) or more can be considered as a reference. When D _STPP is within the above range, it is possible to further suppress a decrease in surface quality.

Regarding other glass characteristics of the optical glass 2, one or two or more of the various matters described in the optical glass 1 can be arbitrarily combined and applied. In addition, regarding the glass characteristics of the optical glass 1, one or two or more of the various matters described in the optical glass 2 may be arbitrarily combined and applied.

(D ₀ ) In the optical glass 2 described above, D ₀ is preferably less than 5.0 × 10 ^-3 mg / (cm ² · h). D ₀ is also sometimes called a true chemical durability in water. The method of measuring D ₀ is as follows. First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm was prepared. The two opposite surfaces having a diameter of 43.7 mm were polished on both sides, and the side surfaces were masked by a method such as bonding a tape (for example, a polyimide tape) having chemical durability to pure water described below. Therefore, the two surfaces of the disc-shaped glass sample were exposed to pure water described below. The total area of these two surfaces (surface area of the glass sample) was 30 cm ² . Subsequently, after measuring the mass M _before the glass sample, the glass sample was immersed in 1 liter per minute by circulating an ion exchange resin, the water temperature maintained at 50 ℃, pH = 7.0 ± 0.2 , stirring sufficiently pure In the water. The mass M _after of the glass sample after being immersed in the pure water for 20 hours or more (preferably 40 hours or more) was measured. The value obtained by dividing the mass difference (M _before- M _after ) (unit: mg) _{before and after} immersion by the surface area of the glass sample and the immersion time was D ₀ . That is, the value obtained by "(M _before -M _after ) / (30 x immersion time (unit: hour))" is D ₀ . By making D ₀ into the above range, it is possible to suppress a reduction in the surface quality of the glass in a cleaning and high-humidity environment. The lower limit of D ₀ is not particularly limited, and, for example, 0.4 × 10 ^-3 mg / (cm ² · h) or more can be considered as a reference.

<Glass Composition> The optical glass 2 preferably contains Nb ⁵⁺ . Nb ⁵⁺ has the effect of increasing the partial dispersion ratio and improving the chemical durability, and particularly has the effect of reducing the values of D _NaOH and D _A. From the viewpoint of obtaining such an effect, a preferred range of the content of Nb ⁵⁺ is 1.0% or more, a more preferred range is 1.5% or more, a more preferred range is 2% or more, and a more preferred range is 2.5% or more, and a more preferable range is 3% or more. In addition, by containing Nb ⁵⁺ , the effect of maintaining the thermal stability of glass can be obtained. From the viewpoint of suppressing the volatility at the time of glass melting, a preferable upper limit of the content of Nb ⁵⁺ is 15%.

Since both Al ³⁺ and Nb ⁵⁺ contribute to the improvement of chemical durability, the total content of Al ³⁺ and Nb ⁵⁺ is preferably set to 10% or more from the viewpoint of imparting excellent chemical durability to glass. It is preferably set to 12% or more, and more preferably set to 15% or more. From the viewpoint of maintaining thermal stability, the total content of Al ³⁺ and Nb ⁵⁺ is preferably 45% or less, and more preferably 35% or less.

Regarding the other glass composition of the optical glass 2, one or two or more of the various matters described in the optical glass 1 can be arbitrarily combined and applied. In addition, as for the glass composition of the optical glass 1, one or two or more of the various matters described in the optical glass 2 can be arbitrarily combined and applied.

<The manufacturing method of glass> The said optical glass 1 and the optical glass 2 can be obtained, for example, by blending, melting, and shaping a glass raw material so that a desired characteristic may be obtained. As a glass raw material, a phosphate, a fluoride, an alkali metal compound, an alkaline-earth metal compound, etc. can be used, for example. As the glass melting method and the molding method, a known method can be used.

[Glass material for press molding, method for manufacturing the same, and method for manufacturing glass molded body] According to an embodiment of the present invention, it is possible to provide the glass material for press molding made of the optical glass 1 or the optical glass 2 and the optical material made of the optical A glass formed body made of glass and a method for producing the same. The glass material for press molding means the glass block which is heated and supplied for press molding. As examples of glass materials for press molding, it can be shown that precision press molding preforms, glass materials for press molding of optical element blanks (glass gobs for press molding), and the like have qualities comparable to those of press molded products. Glass blocks. The glass material for press molding can be manufactured through the process of processing a glass molded object. The glass molded body can be produced by heating and melting glass raw materials as described above, and molding the obtained molten glass. Examples of the processing method of the glass molded body include cutting, grinding, and polishing.

[Optical element blank and manufacturing method thereof] According to an embodiment of the present invention, an optical element blank formed from the optical glass 1 or the optical glass 2 can be provided. The optical element blank is a glass molded body having a shape similar to that of an optical element to be manufactured. The optical element blank can be produced by a method of molding glass into a shape that adds a machining allowance removed by processing to the shape of the optical element to be produced, or the like. For example, a method (secondary pressing method) in which a glass material for press molding is heated and softened (pressing method); a method in which a molten glass block is supplied to a pressing mold using a known method (direct pressing method) can be used. Etc. to produce an optical element blank.

[Optical Element and Manufacturing Method thereof] According to an embodiment of the present invention, an optical element formed of the optical glass 1 or the optical glass 2 can be provided. Examples of the types of optical elements include lenses such as spherical lenses and aspheric lenses, prisms, and diffraction gratings. Examples of the shape of the lens include various shapes such as a lenticular lens, a plano-convex lens, a bi-concave lens, a plano-concave lens, a convex-concave lens, and a meniscus lens. The optical element can be manufactured by a method including a step of processing a glass molded body formed of the optical glass. Examples of the processing include cutting, cutting, rough grinding, fine grinding, and polishing. By using the above-mentioned glass when performing such processing, breakage can be reduced, and high-quality optical elements can be stably supplied.

[Examples] Hereinafter, the present invention will be described in more detail by examples. However, the present invention is not limited to the embodiments shown in the examples.

(Example 1) In order to have the glass composition shown in Table 1, phosphates, fluorides, oxides, and the like corresponding to the respective glass compositions were used as raw materials for introducing each component, the raw materials were weighed, and thoroughly mixed to Made into blending materials. This blended raw material was put into a crucible made of platinum, and heated and melted. After melting, the molten glass was poured into a mold, left to cool to near the glass transition temperature, and then immediately placed in an annealing furnace. After an annealing treatment in the glass transition temperature range for about one hour, it was left to cool to room temperature in the furnace. Each optical glass shown. Observation of the obtained optical glass under magnification using an optical microscope revealed no precipitation of crystals, foreign matter such as platinum particles, bubbles, and no streaks. The characteristics of the optical glass obtained in this manner are shown in Table 1. Each characteristic of optical glass is measured by the method shown below.

(1) Refractive index nd, ng, nF, nC, and Abbe number νd The refractive index nd was measured by using a refractive index measurement method standardized by the Japan Optical Glass Industry Association at a temperature lowered at a temperature of -30 ° C / hour. , Ng, nF, nC, Abbe number νd. In addition, in FIG. 1, Abbe number νd and refractive index nd of each optical glass are plotted.

(2) Deviations of partial dispersion ratios Pg, F and Pg, F from standard lines ΔPg, F Calculate partial dispersion ratios Pg, F based on refractive indices ng, nF, nC, and calculate from standard lines calculated from Abbe number νd The partial dispersion ratio Pg, F (0) deviates from the deviation ΔPg, F. Table 1 shows the refractive index nd, the Abbe number νd, and Pg, F and ΔPg, F calculated from ng, nF, and nC. In addition, in FIG. 2, the Abbe numbers νd and the partial dispersion ratios Pg, F of the respective optical glasses are plotted.

(3) Glass transition temperature Tg A differential scanning calorimeter (DSC3300) manufactured by NETZSCH was used to measure the glass transition temperature Tg at a temperature increase rate of 10 ° C / minute.

(4) Liquid phase temperature LT 50 g of glass was put into a platinum crucible, and the platinum lid was fused at 1100 ° C for 20 minutes, and then maintained at a predetermined temperature for 2 hours. The glass after being held for 2 hours was observed, and the liquidus temperature LT was determined based on the presence or absence of crystal precipitation. For each glass shown in Table 1, after the glass was held at 850 ° C. for 2 hours by the above method, visual observation and magnification observation (100 times) using an optical microscope were performed, and as a result, no crystals were found. Therefore, the liquidus temperature LT of each glass shown in Table 1 is 850 ° C or lower.

(5) Specific gravity The specific gravity was measured by the Archimedes method.

(6) Evaluation of the amount of reduced volatilization during melting A glass batch (150 to 200 g in terms of yield) was filled into a platinum crucible, the platinum lid was covered, the mass X was measured, and the mixture was thawed at 1050 ° C for 1.5 hours. Then, immediately before the molten glass was cast into the mold, the mass Y of the platinum crucible with a platinum lid in which molten glass was added was measured again to obtain a mass change rate (XY) / X. When the glass batch is prepared such that the yield becomes 150 g, X is 150 g, and when the glass batch is prepared such that the yield is 200 g, X is 200 g. In the case where the glass batch contains carbonate, the CO ₂ in the carbonate is discharged during the melting. When the glass batch contains sulfates, nitrates, and hydroxides, SO ₃ , NO ₂ , and H ₂ O are discharged during melting. The mass of gas components such as CO ₂ , SO ₃ , NO ₂ , and H ₂ O included in the glass batch can be calculated in advance, and prepared by subtracting the mass of the gas component from the mass of the glass batch into the mass X. Glass batch. In Table 1, the mass change rate is 2% or less is referred to as A, the mass change rate is greater than 2% and 4% or less is referred to as B, and the mass change rate is greater than 4% is referred to as C. In addition, for each glass of the examples shown in Table 1, the internal transmittance was measured at a thickness of 10 mm according to the internal transmittance measurement (JOGIS-17) standard of the Japan Optical Glass Industry Association. As a result, all the samples had 96.50 % Transmission.

(7) D _NaOH A 43.7 mm diameter and 5 mm thick disc-shaped glass sample (two surfaces are polished on both sides) is immersed in a fully stirred sodium hydroxide (NaOH) solution at a temperature of 50 ° C and a concentration of 0.01 mol / l. ) In an aqueous solution for 15 hours, the value obtained by dividing the mass reduction before and after immersion by the surface area of the glass sample was D _NaOH .

(8) D _A Put powder glass (particle size 425 μm to 600 μm) of mass (g) equivalent to the specific gravity into a platinum basket, and immerse it in a 80 ml nitric acid concentration of 0.01 mol / l in a quartz glass round bottom flask aqueous solution, 60 minutes in a boiling water bath, to reduce the mass of the glass powder before and after the treatment divided by the mass percentage of the powder to the glass before immersion D _a.

(9) D _STPP A 43.7 mm diameter and 5 mm thick disc-shaped glass sample was immersed in a fully stirred aqueous solution of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) at a liquid temperature of 50 ° C. and a concentration of 0.01 mol / l. For 1 hour, the value of the mass reduction before and after the immersion was divided by the surface area of the glass sample and the value of the immersion time as D _STPP .

(10) D ₀ A circular glass sample with a diameter of 43.7 mm and a thickness of 5 mm is immersed in an ion exchange resin at a rate of 1 liter per minute, maintained at a water temperature of 50 ° C, pH = 7.0 ± 0.2, The value of the mass difference before and after immersion for 45 hours in the fully stirred pure water divided by the specific surface area of the glass sample and the immersion time was defined as D ₀ .

(Comparative Example 1) A glass having the composition of Comparative Example 1 shown in Table 1 was prepared, and the refractive index nd, Abbe's number νd, partial dispersion ratio Pg, F, glass transition temperature Tg, specific gravity, and melting were performed according to the method described above. The amount of volatility reduction was evaluated. Comparative Example 1 is a glass of a comparative example with respect to optical glass 1. When the amount of reduction in volatilization during melting was evaluated, the mass change rate was greater than 4% (evaluation result C).

(Comparative Example 2) A glass having the composition of Comparative Example 2 shown in Table 1 was prepared, and the refractive index nd, Abbe number νd, partial dispersion ratio Pg, F, glass transition temperature Tg, specific gravity, and the amount of volatilization reduction during melting were produced. And D _NaOH for evaluation. The evaluation results are shown in Table 1. Comparative example 2 is a glass of a comparative example regarding optical glass 2. D _{NaOH is} greater than 0.25 mg / (cm ² · 15h) and does not satisfy the formula (4).

The above results are shown in Table 1 (Tables 1-1 to 1-7).

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

(Note) In the case of a positive value, the following formula is satisfied. Pg, F ＞ -0.0004νd + 0.5718

The glass composition represented by atomic% in the examples in Table 1 is shown in Table 2 (Tables 2-1 to 2-3).

(Example 2) Using each optical glass of Example 1 described above, a lens blank was produced according to the known method described above. The produced lens blank is ground and polished to produce various lenses (bi-convex lenses, convex-concave lenses, concave-convex lenses, bi-concave lenses, plano-convex lenses, plano-concave lenses). All lenses are lightweight and suitable for high-order chromatic aberration correction.

Finally, the above-mentioned methods are summarized.

According to an embodiment, an optical glass 1 may be provided. The optical glass 1 includes P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2-, and F ^- as an essential component. The content of Al ³⁺ is relative to that of P ⁵⁺ . The molar ratio (Al ³⁺ / P ⁵⁺ ) of the content is 0.30 or more, the content of Nb ⁵⁺ is 1.0 cation% or more, the content of O ^2- is 10 to 85 anion%, and the content of F ^- is 15 to 90 anion. The mole ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) of the content of% and O ^2- to the total content of P ⁵⁺ and Nb ⁵⁺ is 3.0 or more.

In an embodiment, the optical glass 1 can include at least one alkaline earth metal component selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and The total content of Ba ^{2+ is} at least 20 cation%.

In one embodiment, the content of P ⁵⁺ in the optical glass 1 can be 5 to 40 cation%, and the content of Al ³⁺ can be 5 to 30 cation%.

In one embodiment, the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) of the optical glass 1 can be 4.0 or less.

In one embodiment, the optical glass 1 can include at least one rare earth component selected from La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ , La ³⁺ , Gd ³⁺ , Y Molar ratio of the total content of ³⁺ , Lu ^3+, and Yb ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) to the content of Al ³⁺ ((La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) can be 0.3 or less.

According to an embodiment, an optical glass 2 may be provided. The optical glass 2 is formed of a fluorophosphate glass and is dipped in a NaOH aqueous solution for 15 hours. The mass reduction per unit area D _{NaOH is} less than 0.25 mg / (cm ² · 15h), and the Abbe number νd and the partial dispersion ratios Pg, F satisfy the formula (4) above.

According to an embodiment, the D _{A of} the optical glass 2 can be less than 0.35%.

According to an embodiment, the D _{STPP of} the optical glass 2 can be less than 0.40 mg / (cm ² · h).

According to an embodiment, D _{0 of} the optical glass 2 can be less than 5.0 × 10 ^-3 mg / (cm ² · h).

According to an embodiment, the optical glass 2 can include Nb ⁵⁺ .

According to an embodiment, the optical glass 2 can contain 1.0% or more of Nb ⁵⁺ .

According to an embodiment, the content of Nb ⁵⁺ in the optical glass 2 can be 15% or less.

According to an embodiment, the total content of Al ³⁺ and Nb ⁵⁺ of the optical glass 2 can be 10% or more.

According to an embodiment, the content of P ⁵⁺ in the optical glass can be 5 to 40%.

According to an embodiment, the content of Al ³⁺ in the optical glass 2 can be 5 to 40%.

According to an embodiment, the content of Mg ²⁺ in the optical glass 2 can be 0 to 10%.

According to an embodiment, the content of Ca ²⁺ in the optical glass 2 can be 0 to 20%.

According to an embodiment, the content of Sr ²⁺ in the optical glass 2 can be 0 to 40%.

According to an embodiment, the Ba ²⁺ content of the optical glass 2 can be 5 to 40%.

According to an embodiment, the content of La ³⁺ in the optical glass 2 can be 0 to 5%.

According to an embodiment, the content of Gd ³⁺ in the optical glass 2 can be 0 to 5%.

According to an embodiment, the content of Y ³⁺ in the optical glass 2 can be 0 to 5%.

According to an embodiment, the content of Lu ³⁺ of the optical glass 2 can be 0 to 5%.

According to an embodiment, the molar ratio of the content of Yb ³⁺ of the optical glass 2 to the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ^3+, and Yb ³⁺ (Yb ³⁺ / ( La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ )) can be 0.5 or less.

According to an embodiment, the content of Zn ²⁺ in the optical glass 2 can be 0 to 10%.

According to an embodiment, the total content of the alkali metal components in the optical glass 2 can be 0 to 30%.

According to an embodiment, the content of Rb ⁺ in the optical glass 2 can be 0 to 1%.

According to an embodiment, the Cs ⁺ content of the optical glass 2 can be 0 to 1%.

According to an embodiment, the content of Li ⁺ in the optical glass 2 can be 0 to 30%.

According to an embodiment, the content of Li ⁺ in the optical glass 2 can be 2% or more.

According to an embodiment, the content of Li ⁺ in the optical glass 2 can be 4 to 10%.

According to an embodiment, the content of Na ⁺ in the optical glass 2 can be 0 to 10%.

According to an embodiment, the K ⁺ content of the optical glass 2 can be 0 to 10%.

According to an embodiment, the content of Si ⁴⁺ in the optical glass 2 can be 0 to 5%.

According to an embodiment, the content of B ³⁺ in the optical glass 2 can be 2% or less.

According to an embodiment, the content of Cl ⁻ in the optical glass 2 can be 0 to 1%.

According to an embodiment, the total content of Sb ³⁺ and Ce ⁴⁺ of the optical glass 2 can be 0% or more and less than 1%.

According to an embodiment, the optical glass 2 may not substantially include at least one of Pb, Cd, As, and Th.

According to an embodiment, the optical glass 2 may not substantially include at least one of Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V.

According to an embodiment, the optical glass 2 may not substantially include at least one of Hf, Ga, Ge, Te, and Tb.

According to an embodiment, the Abbe number νd of the optical glass 2 can be 45 or more.

According to an embodiment, the Abbe number νd of the optical glass 2 can be 80 or less.

According to an embodiment, the refractive index nd and the Abbe number νd of the optical glass 2 can satisfy the following expression (2). nd≥1.80653-0.00459 × νd (2)

According to an embodiment, the refractive index nd and the Abbe number νd of the optical glass 2 can satisfy the following expression (3). nd≥1.84303-0.00459 × νd (3)

According to an embodiment, the internal transmittance of the optical glass 2 at a wavelength of 400 nm to 700 nm and a thickness of 10 mm can be 96.5% or more.

According to an embodiment, the glass transition temperature Tg of the optical glass 2 can be 550 ° C. or lower.

According to an embodiment, the liquidus temperature of the optical glass 2 can be 850 ° C. or lower.

According to an embodiment, the specific gravity of the optical glass 2 can be 4.2 or less.

Furthermore, according to another aspect, an optical element formed of the optical glass 1 or the optical glass 2 can be provided.

It should be understood that the embodiments disclosed this time are illustrative and not restrictive in all respects. The scope of the present invention is shown by the scope of patent protection rather than the description above, and is intended to include all modifications within the meaning and scope equivalent to the scope of patent protection. For example, for the glass composition exemplified above, the optical glass according to an embodiment of the present invention can be obtained by adjusting the composition described in the description. It is needless to say that the matters described as examples or preferable ranges in the two or more specifications can be arbitrarily combined.

no.

FIG. 1 shows the optical characteristics of the optical glass of the example in the Abbe number νd-refractive index nd diagram. FIG. 2 shows the optical characteristics of the optical glass of the example and the optical characteristics of the conventional optical glass in the Abbe number νd-partial dispersion ratio Pg, F diagram.

Claims (7)

An optical glass containing P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2- and F ^- as essential components; a molar ratio of the content of Al ^{3+ to} the content of P ⁵⁺ (Al ³⁺ / P ^{5 +} ) Is 0.30 or more; the content of Nb ⁵⁺ is more than 1.0 cation%; the content of O ^2- is 10 to 85 anionic%; the content of F ^- is 15 to 90 anionic%; the content of O ^2- is relative to P ⁵⁺ and the total content of Nb ⁵⁺ molar ratio ^{(O 2- / (P 5+ +} Nb 5+)) is 3.0 or more. The optical glass according to item 1 of the patent application scope, which comprises at least one alkaline earth metal component selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ ; Mg ²⁺ , Ca ²⁺ , Sr The total content of ²⁺ and Ba ²⁺ is 20 cation% or more. The optical glass according to item 1 or 2 of the scope of patent application, wherein the content of P ⁵⁺ is 5 to 40 cation%; the content of Al ³⁺ is 5 to 30 cation%. The optical glass according to any one of claims 1 to 3, wherein the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 4.0 or less. The optical glass according to any one of claims 1 to 4 in the patent application scope, which comprises at least one rare earth component selected from La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ^3+, and Yb ³⁺ ; The total content of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ^3+, and Yb ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) content relative to Al ³⁺ The molar ratio ((La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) is 0.3 or less. An optical glass formed of fluorophosphate glass, and the mass reduction per unit area D _{NaOH is} less than 0.25 mg / (cm ² · 15h) when immersed in an aqueous NaOH solution for 15 hours; Pg, F satisfies the following formula (4): Pg, F> -0.0004νd + 0.5718 (4) formula. An optical element is formed of the optical glass according to any one of claims 1 to 6 of the scope of patent application.