KR20180111681A - Optical glass and optical element - Google Patents

Abstract

Provided is an optical glass comprising P^(5+), Al^(3+), Nb^(5+), O^(2-), and F^- as essential components, wherein the molar ratio (Al^(3+) / P^(5+)) of the content of Al^(3+) to the content of P^(5+) is 0.30 or more, the content of Nb^(5+) is 1.0 cation % or more, the content of O^(2-) is 10-85 anion %, the content of F^- is 15-90 anion %, and the molar ratio (O^(2-)/(P^(5+) + Nb^(5+))) of the content of O^(2-) to the total content of P^(5+) and Nb^(5+) is 3.0 or more. According to the present invention, it is possible to provide an optical glass which is suitable for chromatic aberration correction since a partial dispersion ratio is large while the volatility of glass fluorophosphate in a high temperature process is reduced.

Description

[0001] OPTICAL GLASS AND OPTICAL ELEMENT [0002]

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

Phosphorus phosphate glass containing phosphorus, oxygen and fluorine is known as an optical glass exhibiting low dispersion and positive ideal dispersion.

Fluorophosphoric acid glass has a high utility value as an optical element material for correcting high order chromatic aberration because it has the above excellent optical properties.

Examples of such glass fluorophosphate are described in Patent Documents 1 to 4.

Japanese Patent Application Laid-Open No. 2005-112717 Japanese Laid-Open Patent Publication No. 2013-151410 Japanese Laid-Open Patent Publication No. 51-114412 Japanese Patent Application Laid-Open No. 58-217451

Thus, fluorophosphoric acid glass has excellent optical characteristics, but exhibits remarkable volatility in a high-temperature process for melting and molding glass. The occurrence of volatilization from the glass melt during melting and molding may cause phenomena such as deterioration of glass, fluctuation of optical characteristics, and deterioration of homogeneity of glass.

Further, in the process of grinding and polishing a glass material made of optical glass and manufacturing an optical element such as a lens or a prism, the polished glass is usually cleaned. On the other hand, on the surface of the polished glass, there is a minute scratch that is not visually recognized by the naked eye, which is generally called a latent image. However, if the surface of the glass is eroded by cleaning, the latent image is enlarged and becomes a scattering source of light, resulting in a decrease in the surface quality of the glass. Further, deterioration of the glass surface due to cleaning may degrade the surface quality of the glass.

In order to suppress the deterioration of the surface quality of the glass as described above with respect to the glass fluorophosphate, it is desirable to enhance the chemical durability of the glass fluorophosphate.

It is an object of the present invention to provide an optical glass which has a large partial dispersion ratio and is suitable for chromatic aberration correction while reducing the volatility of fluorophosphoric acid glass in a high temperature process and to provide an optical element comprising the optical glass do.

Another aspect of the present invention is to provide an optical glass having excellent chemical durability and having a large partial dispersion ratio and being suitable for chromatic aberration correction, and to provide an optical element comprising the optical glass .

According to an aspect of the present invention,

As essential components, it includes P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2- and F ^-

The molar ratio of the content of Al ³⁺ to the content of ^{P 5+ (Al 3+ / P 5+} ) of 0.30 or more,

The content of Nb ⁵⁺ is 1.0 cation% or more,

The content of O &^lt; ^2- &^gt; is 10 to 85%

The content of F < ^- > is 15 to 90%

(O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) of the content of O ^2- with respect to the total content of P ⁵⁺ and Nb ⁵⁺ is 3.0 or more,

(Hereinafter also referred to as " optical glass 1 "),

.

The above optical glass preferably has an ideal or more dispersibility.

As an index of the ideal anomalous dispersion, the partial dispersion ratios Pg and F are used. The partial dispersion ratios Pg and F are obtained by using the refractive index nF at the F line (wavelength 486.13 nm), the nC at the C line (wavelength 656.27 nm), and the refractive index ng at the g line (wavelength 435.84 nm) As shown in Fig.

Pg, F = (ng - nF) / (nF - nC) (1)

It is known that Nb contained in the glass is close to the visible range of the intrinsic absorption wavelength of the ultraviolet region and has a high absorption intensity. As a result, the wavelength dispersion of the refractive index tends to be high-molecular-weight. That is, the refractive index difference nF - nC between the F line and the C line increases, and the Abbe number vd tends to decrease. On the other hand, the refractive index difference ng - nF between the g line and the F line also becomes larger.

Here, when the effect of increasing ng - nF exceeds the effect of increasing nF - nC, Pg and F become larger as is evident from the expression (1).

The present inventors paid attention to this point and introduced Nb as a glass component to greatly increase the partial dispersion ratio Pg, F while maintaining the low dispersibility (large? D) within the same range as that of the conventional glass fluorophosphate glass I found out I could.

However, fluorophosphoric acid glass containing Nb is liable to volatilize Nb from the glass melt in its melting process. When Nb and F are combined in the melting process, niobium fluoride is formed. Niobium fluoride has a high vapor pressure and is liable to volatilize from the glass melt.

In order to prevent Nb introduced for increasing the partial dispersion ratio from promoting volatilization, the inventors of the present invention have made extensive studies and obtained the following findings.

It is considered that P ^{5 +} exists in the structure of -OPO- in the glass and contributes to the formation of a glass network. It is believed that Nb ⁵⁺ , which is equivalent to P ⁵⁺ , also contributes to the formation of a free network by occupying the position of P in the -OPO- structure.

When Nb ⁵⁺ enters the network structure, fluorine niobium having a high vapor pressure is hardly produced, and as a result, it is considered that the volatility of the glass is lowered.

However, in order for Nb ⁵⁺ to enter the network structure, a sufficient number of O ^2- is required. Considering the case where Nb ⁵⁺ exists, the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) of the content of O ^2- to the total content of the cations (P ⁵⁺ and Nb ⁵⁺ ) , Nb < ^{5 +} > is easily entered into the network, so that an increase in volatility can be suppressed.

Based on the above findings, the present inventors have completed the optical glass according to one aspect of the present invention.

In another aspect of the present invention,

As an optical glass made of glass fluorophosphate,

The mass reduction amount D _NaOH per unit area when immersed in an aqueous NaOH solution for 15 hours was less than 0.25 mg / cm 2 15 h,

Abbe number vd and partial dispersion ratio Pg, F satisfy the following expression (4)

Pg, F > - 0.0004v + 0.5718 (4)

(Hereinafter, also referred to as " optical glass 2 "),

.

According to one aspect of the present invention, it is possible to provide an optical glass which is suitable for correcting chromatic aberration and which has a large partial dispersion ratio while reducing the volatility of glass fluorophosphate in a high-temperature process, and can provide an optical element comprising the optical glass .

According to another aspect of the present invention, there is provided an optical element comprising the optical glass, which can provide an optical glass having a large partial dispersion ratio, which is preferable for chromatic aberration correction and has excellent chemical durability, as glass fluorophosphate .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows the optical characteristics of the optical glass of the embodiment in Abbe number uv-refractive index nd chart. Fig.
Fig. 2 shows the optical characteristics of the optical glass and the optical characteristics of the conventional optical glass in the embodiment in the Abbe number vd - partial dispersion ratio Pg, F. Fig.

In the present invention and in the present specification, the content and the total content of the cationic component are expressed as cationic percentages unless otherwise specified, and the content and the total content of the anionic component are expressed as anionic% do.

Here, " cationic% " is a value calculated as " (total number of cationic groups of interest / total number of cationic groups of the free acid component) x 100 ", and the molar percentage with respect to the total amount of the cationic components of the noticed cationic it means.

"Anion%" is a value calculated as "(the number of anions to be observed / the total number of anions of the free component) × 100", and the mole percentage with respect to the total amount of the anion component of the anionic amount of interest it means.

The molar ratio of the contents of the cationic components to the content of the anionic components is equal to the ratio of the contents of the cationic components expressed by the cationic% Is equal to the ratio of the content by weight.

The molar ratio of the content of the cationic component to the content of the anionic component is the ratio of the contents (expressed in mol%) of the components of interest when the total amount of all the cationic components and all anionic components is 100 mol%.

The content of each component can be quantified by a known method, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), ion chromatography and the like.

In the present invention and in the present specification, " glass fluorophosphate " refers to glass containing at least phosphorus, oxygen and fluorine as an element constituting glass.

[Optical Glass 1]

<Glass component>

Hereinafter, an optical glass 1 according to an embodiment of the present invention will be described.

P ⁵⁺ has a function as a network forming component. Al ³⁺ is a component that functions to maintain the thermal stability of the glass and improve chemical durability and processability. In that it satisfactorily maintain the thermal stability of the glass, the molar ratio of the content of Al ³⁺ to the content of ^{P 5+ (Al 3+ / P 5+} ) is at least 0.30. It is effective that the molar ratio (Al ³⁺ / P ⁵⁺ ) is 0.30 or more in increasing the refractive index while maintaining the Abbe number.

The preferred lower limit of the molar ratio (Al ³⁺ / P ⁵⁺ ) is 0.5. On the other hand, the preferable upper limit of the molar ratio (Al ³⁺ / P ⁵⁺ ) is 2, and the more preferable upper limit is 1 in order to keep the thermal stability of the glass well.

Nb ⁵⁺ has the function of maintaining the thermal stability of the glass as a network forming component together with P ⁵⁺ and increasing the partial dispersion ratio. In order to obtain such an effect, the content of Nb ⁵⁺ is 1.0% or more. A preferable lower limit of the content of Nb ⁵⁺ is 1.5%, a more preferable lower limit is 2%, a more preferable lower limit is 2.5%, and a more preferable lower limit is 3%. On the other hand, if the content of Nb ⁵⁺ is excessive, the volatility during glass melting becomes remarkable, and the homogeneity of the glass tends to decrease. Therefore, the preferable upper limit of the content of Nb ⁵⁺ is 15%, the more preferable upper limit is 13%, and the more preferable upper limit is 10%. The relationship between Nb ⁵⁺ and the chemical durability of the glass will be described later.

In view of maintaining the thermal stability of the glass, the total content (P ⁵⁺ + Nb ⁵⁺ ) of P ⁵⁺ and Nb ⁵⁺ is preferably at least 15%. The preferred lower limit of P ⁵⁺ and the total content of ^{Nb 5+ (P 5+ + Nb 5+} ) is 20%.

O ^2- functions to maintain the thermal stability of the glass. In order to obtain such a function, the content of O ^2- is at least 10% by atom. If the content of O ^2- becomes larger than 85% O O%, the content of F ^- is insufficient and it becomes difficult to obtain low dispersibility. Therefore, the content of O ^2- is from 10 to 85% by atom. The preferable lower limit of the content of O ^2- is 20%, more preferably the lower limit is 30%, the preferable upper limit is 80%, the more preferable upper limit is 75%, the more preferable upper limit is 70.93%, and the more preferable upper limit is 70%.

F ^- has a function of imparting an ideal dispersibility to a glass with a low dispersion and a function of lowering a glass transition temperature or improving chemical durability. If the content of F &lt; ^- &gt; is less than 15 &lt; RTI ID = 0.0 &gt;%,&lt; / RTI &gt; On the other hand, if the content of F ^- exceeds 90% by weight, it becomes difficult to maintain the thermal stability of the glass. Further, when the content of F ^- is excessive, each value of D _NaOH , D _STPP and D ₀ described later tends to increase.

From the above viewpoint, the content of F ^- is from 15 to 90% by atom. The lower limit of the content of F ^- is preferably 20%, more preferably 25%, still more preferably 28.86%, still more preferably 30%, still more preferably 80% and still more preferably 70%.

, In view of reducing the volatility of the glass melt increases 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⁺ (O ^2- / as described above (P ⁵⁺ + Nb ⁵⁺ )) is 3.0 or more. The preferred lower limit of the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 3.2. In terms of maintaining the thermal stability of the glass, the preferred upper limit of the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 4.0, and the more preferable upper limit is 3.8.

The alkaline earth metal components, that is, Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ are components that function to adjust the viscosity and refractive index of the glass and improve the thermal stability. In order to obtain the above effect, it is preferable that the total content R ²⁺ (Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ ) of the alkaline earth metal components is 20 cationic% or more, more preferably 30% desirable.

On the other hand, when the total content R ²⁺ of the alkaline earth metal components is excessive, the thermal stability tends to decrease. Therefore, it is preferable that the total content R ²⁺ of the alkaline earth metal components is 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 contain at least one rare earth component selected from the group consisting of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ .

(La ³⁺ + Gd) of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ with respect to the content of Al ³⁺ it ^{3+ + Y 3+ + Lu 3+ +} Yb 3+) molar ratio of ^{((La 3+ + Gd 3+ +} Y 3+ + Lu 3+ + Yb 3+) / Al 3+) of 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 be zero.

Next, contents of the individual components will be described.

P ⁵⁺ is an essential component for forming a network of glass. In order to keep the thermal stability favorable, the lower limit of the content of P ⁵⁺ is preferably 5%, more preferably 10%, even more preferably 20%. The preferable upper limit of the content of P ⁵⁺ is 40%, the more preferable upper limit is 38%, and the more preferable upper limit is 35% in view of maintaining good chemical durability and maintaining low dispersibility and anomalous partial dispersion.

Al ³⁺ is an essential component that functions to improve thermal stability, chemical durability and processability, and also functions to increase the refractive index. In view of the above, the preferable lower limit of the content of Al ³⁺ is 5%, the lower limit is 7%, the lower limit is 9%, and the more preferable lower limit is 11%. In view of the above, the preferable upper limit of the content of Al ³⁺ is 40%, the more preferable upper limit is 38%, the more preferable upper limit is 36%, and the more preferable upper limit is 34%.

In the glass composition is represented by atomic%, O of O ^2- to the content of Al ³⁺ content ratio ^2- / Al ³⁺ is not less than 12 is preferred, more preferably preferred, and less than 8, more preferably less than 10 . When the content of O ^2- increases, the content of F ^- is relatively decreased and the glass transition temperature shows an upward trend. On the other hand, Al ³⁺ is a useful component in improving the thermal stability, chemical durability and processability as described above and having desired optical properties. While sufficiently obtain the effect of the Al ^3+, glass transition In order to suppress the temperature rise of the glass content of the composition ratio O ^2- / Al ³⁺ of O ^2- to the content of Al ³⁺ in the represented by the atomic% . The lower limit of the above-mentioned non-O ^2- / Al ³⁺ may be, for example, 2 or more or 3 or more from the viewpoint of suppressing a decrease in resistance to devitrification caused by a relative increase in the content of Al ³⁺ .

The content of each component in the glass composition expressed by atomic% is calculated as a value representing the content of each component in terms of mole percentage when the total content of the entire cationic component and the total anionic component is 100 mol% do.

The preferable contents of the respective components of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ are as follows.

The Mg ²⁺ content is preferably 0 to 10%, more preferably 0 to 8%.

The content of Ca ²⁺ is preferably 0 to 20%, more preferably 0 to 15%.

A preferable range of the content of Sr ²⁺ is 0 to 40%, and a more preferable range is 0 to 30%.

The lower limit of the Ba ²⁺ content is preferably 5%, more preferably 10%, the upper limit is 50%, and the more preferable upper limit is 40%.

Each preferable content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Lu ³⁺ is as follows.

The preferable range of the content of La ³⁺ is 0 to 5%, more preferably 0 to 3%.

A preferable range of the content of Gd ³⁺ is 0 to 5%, and a more preferable range is 0 to 3%.

A preferable range of the content of Y ³⁺ is 0 to 5%, and a 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 preferable for use for imaging by infrared light because it has light absorption in the infrared region. Therefore, the content of Yb ³⁺ is, using a molar ratio of the total content of other rare-earth elements ^{(Yb 3+ / (La 3+ +} Gd 3+ + Y 3+ + Lu 3+ + Yb 3+)) is preferably limited as follows. That is, the ^{La 3+, Gd 3+, Y 3+} , Lu 3+ , and the molar ratio of the content of the Yb ³⁺ to the total content of ^{Yb 3+ (Yb 3+ / (La} 3+ + Gd 3+ + Y 3+ + Lu 3+ + Yb 3+)) 0.5 Or less, more preferably 0.1 or less, and even more preferably 0 (Yb ³⁺ content is 0%).

Zn ²⁺ functions to improve the thermal stability while maintaining the refractive index, but if it is contained in excess, the dispersion becomes high, and it becomes difficult to obtain the required optical characteristics. Therefore, it is preferable that the content of Zn ²⁺ is in the 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 be 0%.

The alkali metal component is a cation component having a function of adjusting the viscosity of the glass or improving the thermal stability. If the total content R ⁺ of the alkali metal components is excessive, the thermal stability is lowered. Therefore, the preferable range of the total content R ⁺ of the alkali metal components is 0 to 30%. In view of the above, 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%, even more preferably 7%. Further, when the total content R ⁺ of the alkali metal components is excessive, respective values of D _STPP and D _{0 described} later tend to increase. Therefore, from the viewpoint of imparting excellent chemical durability to the glass, it is preferable to set R ⁺ within 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%.

An alkali metal component ^{R +, Li +, Na +} , K +, Rb +, Cs ⁺ may represent. Rb ⁺ and Cs ⁺ are liable to cause an increase in the specific gravity of the glass as compared with other alkali metal components.

Therefore, the content of Rb ⁺ is preferably 0 to 3%, more preferably 0 to 2%, even more preferably 0 to 1%, and even more preferably 0%.

The content of Cs ⁺ is preferably 0 to 3%, more preferably 0 to 2%, even more preferably 0 to 1%, and even more preferably 0%.

From the viewpoint of maintaining the thermal stability of the glass, the preferable range of the content of Li ⁺ is 0 to 30%, more preferably 2 to 20%, still more preferably 4 to 10%.

From the viewpoint of maintaining the thermal stability of the glass, the preferable range of the content of Na ⁺ is 0 to 10%, more preferably 0 to 8%, still more preferably 0 to 6%.

In order to maintain the thermal stability of the glass, the preferable range of the content of K ⁺ is 0 to 10%, more preferably 0 to 8%, still more preferably 0 to 6%.

The Si ⁴⁺ can be contained in a small amount, but if it is contained in excess, the meltability and thermal stability deteriorate. Therefore, the content of Si ⁴⁺ is preferably in the range of 0 to 5%, more preferably in the range of 0 to 3%, still more preferably in the range of 0 to 1%, and even more preferably 0% .

B ³⁺ exhibits remarkable volatility even in a small amount. In order not to promote volatilization, the content of B ³⁺ is preferably 2% or less. The preferable range of the content of B ³⁺ is 0 to 1%, more preferably 0 to 0.1%, and still more preferably 0%.

It is effective to contain Cl ^- in order to suppress the wetting of the glass melt with respect to the outer periphery of the pipe and suppress the deterioration of the quality of the glass due to wetting when the molten glass flows out from the pipe attached to the glass melting apparatus. The preferable range of the content of Cl ^- is 0 to 1%, more preferably 0 to 0.5%, still more preferably 0 to 0.3%. Cl ^- also has an effect as a fining agent.

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

Pb, Cd, As, and Th are components in which environmental load is a concern.

Therefore, it is preferable that the optical glass 1 does not substantially contain 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%, particularly preferably substantially no 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%, particularly preferably substantially free of Cd ²⁺ .

The content of As ³⁺ is preferably 0 to 0.1%, more preferably 0 to 0.05%, even more preferably 0 to 0.01%, particularly preferably substantially no As ³⁺ .

The content of Th ⁴⁺ is preferably 0 to 0.1%, more preferably 0 to 0.05%, even more preferably 0 to 0.01%, particularly preferably substantially not containing Th ⁴⁺ .

The optical glass 1 preferably exhibits a high transmittance over a wide range of the visible region. In order to take advantage of this feature, it is preferable that the optical glass does not contain a coloring agent. As the coloring agent, Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, V and the like can be exemplified. It is preferable that the optical glass 1 does not substantially contain 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 by the cationic% display is preferably in a range of less than 100 ppm, more preferably 0 to 80 ppm, More preferably 0 to 50 ppm or less, and particularly preferably substantially not. Here, ppm refers to cationic ppm.

Further, Hf, Ga, Ge, Te, and Tb are expensive components. Therefore, it is preferable that the optical glass 1 does not substantially contain at least one of Hf, Ga, Ge, Te and Tb. The content of Hf, Ga, Ge, Te and Tb by the cationic% display is preferably 0 to 0.1%, more preferably 0 to 0.05%, and most preferably 0 to 0.01% , Still more preferably from 0 to 0.005%, even more preferably from 0 to 0.001%, and particularly preferably substantially from 0 to 0.005%.

The optical glass can exhibit various properties without introducing Hf, Ga, Ge, Te, or Tb.

<Glass characteristics>

(Abbe number υd, refractive index nd)

In the optical glass 1, it is preferable that the Abbe number υd is in the range of 45 or more from the viewpoint of realizing the ideal partial dispersion.

Abbe number vd is a value indicating the property of dispersion and is represented by υd = (nd-1) / (nF - nC) using refractive indices nd, nF and nC in the d line, F line and C line.

The preferable upper limit of the Abbe number vd is 80, and the more preferable upper limit is 70. [ On the other hand, in order to obtain low dispersibility, the preferable lower limit of the Abbe number vd is 45, more preferably 50, and still more preferably 55.

Also, by setting the refractive index nd in the range below, the absolute value of the curvature of the optically functional surface of the lens can be reduced (the curvature of the optically functional surface of the lens can be made gentle) with the same light-converging power. In precision press molding, grinding and polishing, since the curvature of the optically functional surface of the lens is gentle, it is easy to produce. Therefore, productivity of the optical element can be increased by using high refractive index glass. Further, by increasing the refractive index, it is also possible to provide a glass material suitable for an optical element used in a high-performance, compact optical system.

In the optical glass 1, a preferable range of the refractive index nd is a range that satisfies the following expression (2), and a more preferable range of the refractive index nd is a range that satisfies the following expression (3).

nd ≥ 1.80653 - 0.00459 × υd (2)

nd ≥ 1.84303 - 0.00459 × υd (3)

Fig. 1 shows expressions when equality holds in equations (2) and (3).

The optical glass 1 preferably exhibits an ideal or more dispersibility. The ideal dispersibility is quantitatively expressed by? Pg, F. (Pg, F = (ng-nF) / (nF), (ng-nF), - nC)).

As a commercially available low dispersion glass having an Abbe number υd of 45 or more, FCD100 manufactured by HOYA, FCD515, and the like are known.

The FCD100 is plotted on the coordinate (95.1 0.5334), the FCD 515 is plotted on the coordinate (68.63 0.5441), and the straight line L connecting the two points is plotted in the graph of the Abbe number vd on the abscissa axis and the partial dispersion ratio Pg, F on the ordinate axis. . This straight line L indicates approximately "Pg, F = -0.0004υd + 0.5718".

And a straight line L is shown in Fig.

As shown in Fig. 2, a commercially available low-dispersion glass having a Abbe number υd of 45 or more (conventional glass) has an Abbe number υd - partial dispersion ratio Pg, Pg, F are located on the smaller side.

In a preferred embodiment of the optical glass 1, the Abbe number υd and the partial dispersion ratios Pg and F satisfy the following expression (4).

Pg, F &gt; - 0.0004v + 0.5718 (4)

The optical glass having an Abbe number vd of 45 or more and satisfying the above formula (4) has a large partial dispersion ratio Pg, F with respect to a specific Abbe number υd, and is preferable as a high order optical compensation glass for chromatic aberration correction.

(Transmittance)

The optical glass 1 preferably has a very small coloration and is preferable as a material for an optical element for image pickup such as a camera lens or a transmission optical element such as a projector.

A preferred embodiment of the optical glass 1 is a glass having an internal transmittance of 96.5% or more at a wavelength of 400 nm to 700 nm and a thickness of 10 mm.

A preferable range of the internal transmittance is 97% or more, a more preferable range is 98% or more, and a more preferable range is 99% or more.

Further, glass containing luminescent ions such as glass for lasers, for example, Nd, Eu, Er, V, etc., has absorption in the visible region and therefore can be used as an optical element for image pickup such as a camera lens, It is not suitable as a material for an optical element for projection.

(Glass transition temperature Tg)

A preferred embodiment of the optical glass 1 is an optical glass having a glass transition temperature Tg of 550 캜 or less. When the glass transition temperature is low, the heating temperature at the time of press molding by reheating or softening the glass can be lowered. As a result, fusion of the glass and the press-molding mold can be easily suppressed. Further, since the heating temperature can be lowered, the thermal consumption of the glass heating apparatus, the press molding mold, and the like can be reduced. Further, since the annealing temperature of the glass can be lowered, the lifetime of the annealing furnace can be prolonged. A more preferable range of the glass transition temperature is 530 DEG C or less, and a more preferable range is 500 DEG C or less.

(Liquid temperature)

A preferred embodiment of the optical glass 1 is an optical glass having a liquidus temperature of 850 캜 or lower. If the liquidus temperature is low, melting and molding temperatures of the glass can be lowered. As a result, the volatility of the glass during melting and molding can be reduced, and occurrence of fogging and fluctuation of optical characteristics can be suppressed.

A more preferable range of the liquidus temperature is 800 DEG C or less, and a more preferable range is 750 DEG C or less.

(importance)

The optical glass 1 can increase the partial dispersion ratio mainly by the incorporation of Nb ⁵⁺ without depending on the rare earth which increases the partial dispersion ratio but also increases the specific gravity. Thus, the optical glass 1 has a relatively small specific gravity in the glass fluorophosphate having a large partial dispersion ratio.

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 preferable range of the specific gravity is 4.1 or less, and a more preferable range is 4 or less.

[Optical Glass 2]

Hereinafter, the optical glass 2 according to one embodiment of the present invention will be described.

<Glass characteristics>

In the optical glass 2, the Abbe number υd and the partial dispersion ratio Pg, F satisfy the following expression (4).

Pg, F &gt; - 0.0004v + 0.5718 (4)

The optical glass 2 in which the Abbe number υd and the partial dispersion ratios Pg and F satisfy the formula (4) is preferable as the optical glass for higher order chromatic aberration correction.

In the optical glass 2, the Abbe number υd is preferably in the range of 45 or more in terms of making the ideal partial dispersion possible. The preferable upper limit of the Abbe number vd is 80, and the more preferable upper limit is 70. [ On the other hand, in order to obtain low dispersibility, the lower limit of the Abbe number υd is more preferably 50, and still more preferably the lower limit is 55. [

<Chemical Durability>

(D _NaOH )

The optical glass 2 has a chemical durability in which the weight loss D _NaOH per unit area when immersed in an aqueous NaOH solution for 15 hours is less than 0.25 mg / (cm 2 15 h).

The mass reduction amount D _NaOH is obtained by the following method.

First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm is prepared. The two opposing surfaces of 43.7 mm in diameter are faced to each other and the side surface is coated with a tape (for example, polyimide tape or the like) having chemical durability against an aqueous solution of sodium hydroxide (NaOH) Lt; / RTI &gt; Accordingly, the two surfaces of the glass sample on the disk are exposed to an aqueous solution of the following sodium hydroxide (NaOH). The sum of the areas of these two surfaces (hereinafter referred to as &quot; surface area of the glass sample &quot;) is 30 cm 2.

Next, after measuring the mass M _before of the glass sample, the glass sample was immersed in an aqueous solution of sodium hydroxide (NaOH) sufficiently stirred at a liquid temperature of 50 DEG C and a concentration of 0.01 mol / L for 15 hours, _after . 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 is D _NaOH . That is, the value obtained by "(M _before - M _after ) / 30" is D _NaOH .

The optical glass 2 has chemical durability such that D _NaOH is less than 0.25 mg / cm 2 15 h. According to the optical glass having D _NaOH within the above range, it is possible to suppress the occurrence of deterioration of the surface quality due to the activation of the latent image or the like. In view of maintaining a high surface quality, D _NaOH is preferably less than 0.20 mg / (cm 2 15 h), more preferably less than 0.10 mg / (cm 2 15 h). The lower limit of the D _NaOH is not particularly limited, but may be, for example, 0.02 mg / (cm 2 15 h) or more.

(About D _A )

The optical glass 2 preferably has chemical durability such that D _A is less than 0.35%.

D _A is measured according to the measurement method of the acid-resistant weight loss ratio Da specified in Japan Optical Glass Industry Standard JOGIS06-2009. Specifically, the measurement method is as follows.

Powdered glass (particle size: 425 탆 to 600 탆) having a mass corresponding to the specific gravity (M _before , unit: g) was placed in a platinum basket and immersed in 80 ml of a nitric acid aqueous solution having a concentration of 0.01 mol / l in a round bottom flask made of quartz glass, This is treated for 60 minutes in a boiling water bath, and the mass M _after (unit: g) of the powdery glass after the treatment is measured. Calculated by dividing the weight difference between the powder of glass before and after the treatment by the mass of powder glass before the treatment _{(M before - M after) /} M to the _before as a _{percentage, [(M before - M after} ) / M before] × 100, This is D _A. The optical glass having the above-mentioned range of D _A is preferable as a glass material for an outdoor installation surveillance camera or an optical element mounted on a vehicle camera which requires excellent acid resistance.

The lower limit of D _A is not particularly limited, but can be considered as a standard of, for example, 0.20% or more.

(For D _STPP )

It is also preferable that the optical glass 2 has a chemical durability such that D _STPP is less than 0.40 mg / (cm 2 · h).

The measurement method of _DSTPP is as follows.

First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm is prepared. Two opposing surfaces of 43.7 mm in diameter were faced to each other and the side surfaces were masked by a method of attaching a chemical durable tape (for example, polyimide tape or the like) to an aqueous solution of sodium tripolyphosphate described below do. Thus, the two surfaces of the glass sample on the disk are exposed to an aqueous solution of sodium tripolyphosphate described below. The sum of the areas of these two surfaces (surface area of the glass sample) is 30 cm 2.

Next, the mass M _before of the glass sample was measured, and then immersed in an aqueous solution of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) sufficiently stirred at a liquid temperature of 50 ° C and a concentration of 0.01 mol / l for 1 hour, The mass M _after is 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 is defined as D _STPP . That is, the value obtained by "(M _before - M _after ) / (30 × 1)" is D _STPP .

It is more preferable that the optical glass 2 has a chemical durability such that _DSTPP is less than 0.20 mg / (cm &lt; 2 &gt;. H). The lower limit of the _DSTPP is not particularly limited, but may be, for example, 0.02 mg / (㎠ · h) or more.

When the _DSTPP is in the above range, the occurrence of a decrease in surface quality can be further suppressed.

As for the other glass properties of the optical glass 2, one or two or more of the above-described various items can be applied to the optical glass 1 in any combination. As regards the glass properties of the optical glass 1, one or two or more of the above-mentioned various items may be applied to the optical glass 2 in any combination.

(D ₀ )

In the optical glass 2, it is preferable that D ₀ is less than 5.0 × 10 ^-3 mg / (㎠ · h). D ₀ is sometimes referred to as true chemical durability to water.

The measurement method of D ₀ is as follows.

First, a disk-shaped glass sample having a diameter of 43.7 mm and a thickness of 5 mm is prepared. Two facing surfaces of 43.7 mm in diameter are faced to each other and the side surface is masked by a method of affixing a chemical durable tape (for example, polyimide tape or the like) to the following pure water. Thus, the two surfaces of the glass sample on the disk are exposed to the following pure water. The sum of the areas of these two surfaces (surface area of the glass sample) is 30 cm 2.

Next, after measuring the mass M _before , the glass sample is circulated through the ion exchange resin at a rate of 1 liter per minute, and maintained at a temperature of 50 ° C and a pH of 7.0 ± 0.2, and is immersed in a sufficiently stirred pure water. The mass M _after of the glass sample after immersion in the pure water for 20 hours or more (preferably 40 hours or more) is 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 is D ₀ . That is, the value obtained by "(M _before - M _after ) / (30 × immersion time (unit: hour))" is D ₀ .

When D ₀ is in the above range, deterioration of the surface quality of the glass under a cleaning or high humidity environment can be suppressed. The lower limit of D ₀ is not particularly limited, but it can be considered as a standard, for example, 0.4 x 10 ^-3 mg / (cm 2 · h) or more.

<Glass Composition>

The optical glass 2 preferably contains Nb ⁵⁺ .

Nb ⁵⁺ has a function of increasing the partial dispersion ratio and improving the chemical durability, and in particular, it functions to lower the values of D _NaOH and D _A. In order to obtain such effects, the preferable range of the content of Nb ⁵⁺ is 1.0% or more, more preferably 1.5% or more, still more preferably 2% or more, still more preferably 2.5% %. Further, by the inclusion of Nb ⁵⁺ , an effect of maintaining the thermal stability of the glass can be obtained. From the standpoint of suppressing the volatility at the time of melting the glass, the preferable upper limit of the content of Nb ⁵⁺ is 15%.

Al ³⁺ and Nb ⁵⁺ all contribute to enhancement of chemical durability, so that the total content of Al ³⁺ and Nb ⁵⁺ is preferably 10% or more, more preferably 12% or more in view of imparting excellent chemical durability to the glass , And more preferably 15% or more. The total content of Al ³⁺ and Nb ⁵⁺ is preferably 45% or less, more preferably 35% or less, from the viewpoint of maintaining thermal stability.

As for the other glass compositions of the optical glass 2, one or two or more of the above-mentioned various items can be applied to the optical glass 1 in any combination. With regard to the glass composition of the optical glass 1, one or two or more of the above-mentioned various items may be applied to the optical glass 2 in any combination.

<Production Method of Glass>

The optical glasses 1 and 2 can be obtained, for example, by combining, melting and molding a glass raw material so as to obtain necessary characteristics. As the glass raw material, for example, a phosphate, a fluoride, an alkali metal compound, an alkaline earth metal compound or the like may be used. As the melting method and the molding method of the glass, a known method may be used.

[Glass material for press molding, manufacturing method thereof, and manufacturing method of glass molded article]

According to one aspect of the present invention, it is possible to provide a glass material for press molding comprising the optical glass 1 or the optical glass 2, a glass molded article comprising the optical glass, and a method of manufacturing the same.

The glass material for press molding means a glass mass which is heated and is provided for press molding. An example of the press-molding glass material may be a glass mass having a mass corresponding to the mass of a press-molded product such as a preform for precision press molding and a glass material (press-molding glass product) for press-molding an optical element blank .

The glass material for press molding is manufactured through a process of processing a glass molded article. The glass molded body can be produced by heating and melting the glass raw material as described above, and molding the obtained molten glass. Examples of the processing method of the glass molded body include cutting, grinding, polishing and the like.

[Optical Element Blank and Manufacturing Method Thereof]

According to one aspect of the present invention, it is possible to provide an optical element blank comprising the optical glass 1 or the optical glass 2. The optical element blank is a glass shaped article having a shape approximating the shape of an optical element to be produced. The optical element blank may be manufactured by a method of molding a glass in a shape in which a processing stand to be removed by machining is added to the shape of an optical element to be manufactured. For example, a method of heating and softening a glass material for press molding (press reheating method), a method of supplying a molten glass mass to a press molding mold by a known method and press molding (direct press method) An optical element blank can be manufactured.

[Optical element and manufacturing method thereof]

According to one aspect of the present invention, an optical element comprising the optical glass 1 or the optical glass 2 can be provided. Examples of the type of the optical element include a lens such as a spherical lens and an aspherical lens, a prism, a diffraction grating and the like. As the shape of the lens, various shapes such as a biconvex lens, a plano-convex lens, a biconcave lens, a flat concave lens, a convex meniscus lens, a concave meniscus lens, and the like can be shown. The optical element can be manufactured by a method including a step of processing a glass formed body made of the optical glass. Examples of the processing include cutting, cutting, rough grinding, fine grinding, polishing and the like. By using the above-mentioned optical glass at the time of performing such processing, breakage can be reduced, and high-quality optical elements can be stably supplied.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments shown in the embodiments.

(Example 1)

The raw materials were weighed and sufficiently mixed by using phosphoric acid salts, fluorides, oxides, etc. corresponding respectively to the raw materials for introducing the respective components so as to have the glass compositions shown in Table 1, and they were used as combined raw materials.

The combined raw materials were placed in a crucible made of platinum, and heated and melted. After melting, the molten glass was poured into a mold and allowed to cool to a temperature close to the glass transition temperature and immediately put in an annealing furnace. After annealing for about 1 hour in the glass transition temperature range, the furnace was allowed to cool to room temperature, Was obtained.

As a result of observation of the obtained optical glass by an optical microscope, no precipitation of crystals, foreign substances such as platinum particles and bubbles were observed, and no fog was observed.

Table 1 shows various properties of the optical glass thus obtained.

Various properties of the optical glass were measured by the following methods.

(1) Refractive indices nd, ng, nF, nC and Abbe number υd

The refractive indices nd, ng, nF, nC and Abbe number υd were measured by a refractive index measurement method of the Japan Optical Glass Industry Association, for the glass obtained by lowering the temperature at a cooling rate of -30 캜 / hour.

In addition, in Fig. 1, the Abbe number υd and the refractive index nd of each optical glass are plotted.

(2) the deviations? Pg, F from the normal line of the partial dispersion ratios Pg, F and Pg, F

The partial dispersion ratios Pg and F from the refractive indices ng, nF and nC were calculated and the partial dispersion ratios Pg on the normal line calculated from the Abbe number vd and the deviation Pg and F from F (0) were calculated.

Table 1 shows Pg, F, and Pg, F calculated from refractive index nd, Abbe number υd, and ng, nF, nC.

2, Abbe number vd and partial dispersion ratios Pg, F of the respective optical glasses are plotted.

(3) Glass transition temperature Tg

The glass transition temperature Tg was measured using a differential scanning calorimeter (DSC3300) manufactured by NETZSCH at a heating rate of 10 ° C / min.

(4) Liquid phase temperature LT

50 g of glass was placed in a platinum crucible and dissolved in a platinum cover at 1100 DEG C for 20 minutes and then held at a predetermined temperature for 2 hours. The glass after keeping for 2 hours was observed, and the liquidus temperature LT was determined from the presence or absence of crystal precipitation.

For each of the glasses shown in Table 1, the glass was held at 850 占 폚 for 2 hours by the above method, and then subjected to magnified observation (100 times) using a naked eye and an optical microscope. As a result, precipitation of crystals was not observed.

Therefore, the liquidus temperature LT of each glass shown in Table 1 is 850 DEG C or less.

(5) Specific gravity

The specific gravity was measured by the Archimedes method.

(6) Evaluation of volatilization reduction amount during dissolution

The glass batch (150-200 g in terms of water) was charged into a platinum crucible and covered with a platinum cover to measure mass X and then dissolved at 1050 ° C for 1.5 hours. Subsequently, immediately before casting the molten glass into the mold, the mass Y of the platinum crucible containing the molten glass and covered with platinum was measured again to obtain the rate of change in mass (X-Y) / X. When the glass batch is prepared so that the yield is 150 g, X becomes 150 g, and when the glass batch is prepared so that the yield becomes 200 g, X becomes 200 g.

When the glass batch contains a carbonate, CO ₂ in the carbonate is discharged during dissolution. When the glass batch contains sulfates, nitrates, and hydroxides, SO ₃ , NO ₂ , and H ₂ O are discharged during dissolution.

The mass of the gas component such as CO ₂ , SO ₃ , NO ₂ and H ₂ O contained in the glass batch was calculated in advance and the glass batch was prepared so that the mass obtained by subtracting the mass of the gas component from the mass of the glass batch was the mass X .

In Table 1, A having a mass change rate of 2% or less, B having a mass change rate of 2% or more and 4% or less, and C having a mass change rate of 4% or more.

The internal transmittance at a thickness of 10 mm was measured for each glass of the examples shown in Table 1 according to the internal transmittance measurement (JOGIS-17) of the Japan Optical Glass Industry Association standard. As a result, the transmittance was 96.50% .

(7) D _NaOH

A glass sample (two surfaces were polished on both sides) having a diameter of 43.7 mm and a thickness of 5 mm was immersed in an aqueous solution of sodium hydroxide (NaOH) sufficiently stirred at a liquid temperature of 50 캜 and a concentration of 0.01 mol / l for 15 hours, The amount of decrease in mass before and after immersion, divided by the surface area of the glass sample, was defined as D _NaOH .

(8) D _A

Powdered glass (particle size: 425 μm to 600 μm) having a specific gravity of g (mass) was placed in a platinum basket and immersed in 80 mL of a nitric acid aqueous solution having a concentration of 0.01 mol / L in a round bottom flask made of quartz glass, And the percentage of the amount of reduction in mass of the powder glass before and after the treatment divided by the mass of the powder glass before the immersion was defined as D _A.

(9) D _STPP

A glass sample having a diameter of 43.7 mm and a thickness of 5 mm was dipped in an aqueous solution of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) sufficiently stirred at a liquid temperature of 50 ° C and a concentration of 0.01 mol / l for 1 hour, The value obtained by dividing the reduction amount by the surface area of the glass sample and the immersion time was defined as D _STPP .

(10) D ₀

A glass sample on a disk having a diameter of 43.7 mm and a thickness of 5 mm was circulated through the ion exchange resin at a rate of 1 liter per minute and immersed in pure water which was maintained at a water temperature of 50 캜 and a pH of 7.0 짹 0.2 for 45 hours , And the value obtained by dividing the mass difference before and after immersion by the unit surface area of the glass sample and the immersed time was D ₀ .

(Comparative Example 1)

The glass having the composition of Comparative Example 1 shown in Table 1 was prepared and the refractive index nd, Abbe number υd, partial dispersion ratio Pg, F, glass transition temperature Tg, specific gravity and volatilization reduction amount during dissolution were evaluated by the above method. Comparative Example 1 is glass of Comparative Example relating to optical glass 1, and the amount of decrease in volatilization during dissolution was evaluated. As a result, the mass change rate was larger than 4% (evaluation result C).

(Comparative Example 2)

Glass having the composition of Comparative Example 2 shown in Table 1 was _prepared and evaluated for refractive index nd, Abbe number υd, partial dispersion ratio Pg, F, glass transition temperature Tg, specific gravity, amount of volatilization during dissolution, and D _NaOH . Table 1 shows the evaluation results. Comparative Example 2 is glass of Comparative Example relating to optical glass 2, and D _NaOH is larger than 0.25 mg / (cm 2 15 h), and expression (4) is not satisfied.

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

[Table 1-1]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-2]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-3]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-4]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-5]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-6]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

[Table 1-7]

(Note) In the case of a positive value, the following formula is satisfied.

Pg, F &gt; -0.0004 [deg.] + 0.5718

The glass compositions expressed in atomic% of the examples in Table 1 are shown in Table 2 (Tables 2-1 to 2-3).

[Table 2-1]

[Table 2-2]

[Table 2-3]

(Example 2)

Using each of the optical glasses of Example 1, a lens blank was produced by the above-described known method. The produced lens blank was grinded and polished to produce various lenses (biconvex lens, convex meniscus lens, concave meniscus lens, biconcave lens, flat convex lens, flat concave lens).

Any lens is lightweight, and is preferable for high order chromatic aberration correction.

Finally, we summarize each of the aspects described above.

According to one embodiment, the molar ratio (Al ³⁺ / P ⁵⁺ ) of the content of Al ^{3+ to} the content of P ⁵⁺ , including P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2- and F ^- , the content of Nb ⁵⁺ 1.0 cation% or more, the content of O ^2- 10 ~ 85 anionic%, F ^- is 15 to 90 anionic%, O ^2- to the total content of P ⁵⁺ and Nb ⁵⁺ content of (O ² / (P ⁵⁺ + Nb ⁵⁺ )) of 3.0 or more in terms of the content of the optical glass 1 is provided.

In one embodiment, the optical glass 1, the sum of Mg ^2+, Ca ^2+, Sr ^2+, and the alkali earth metal component selected from the group consisting of Ba ²⁺ comprises at least one member, Mg ^2+, Ca ^2+, Sr ²⁺ and Ba ²⁺ The content may be 20% by weight or more.

In one embodiment, the optical glass 1 may have a P ⁵⁺ content of 5 to 40 cationic% and an Al ³⁺ content of 5 to 30 cationic%.

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

In one embodiment, the optical glass 1, La ^3+, Gd ^3+, Y ^3+, Lu ^3+, and may include at least one type of rare earth element selected from the group consisting of Yb ^3+, La on the content of Al ^{3+ 3+,} (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) of the total content of Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ (La ³⁺ + Gd ³⁺ + Y ³⁺ + Lu ³⁺ + Yb ³⁺ ) Al ³⁺ ) may be 0.3 or less.

According to an aspect of the present invention, there is provided an optical glass comprising fluorophosphoric acid glass, wherein the weight loss D _NaOH per unit area when immersed in an aqueous NaOH solution for 15 hours is less than 0.25 mg / cm 2 15 h, Pg, and F satisfy the above-mentioned formula (4).

According to an embodiment, the optical glass 2 may have a D _A of less than 0.35%.

According to an embodiment, the optical glass 2 may have a D _STPP of less than 0.40 mg / (cm 2 · h).

According to one embodiment, the optical glass 2 may have a D ₀ of less than 5.0 × 10 ^-3 mg / (cm 2 · h).

According to one embodiment, the optical glass 2 may include Nb ⁵⁺ .

According to one embodiment, the optical glass 2 may include 1.0% or more of Nb ⁵⁺ .

According to one embodiment, the content of Nb ^{5+ in} the optical glass 2 may be 15% or less.

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

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

According to one embodiment, the optical glass 2 may have an Al ³⁺ content of 5 to 40%.

According to one embodiment, the Mg ²⁺ content of the optical glass 2 may be 0 to 10%.

According to one embodiment, the Ca ²⁺ content of the optical glass 2 may be 0 to 20%.

According to one embodiment, the Sr ²⁺ content of the optical glass 2 may be 0 to 40%.

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

According to one embodiment, the La ³⁺ content of the optical glass 2 may be 0 to 5%.

According to one embodiment, the Gd ³⁺ content of the optical glass 2 may be 0 to 5%.

According to one embodiment, the Y ³⁺ content of the optical glass 2 may be 0 to 5%.

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

According to one aspect, La ^3+, the optical glass ^{2 Gd 3+, Y 3+, Lu} 3+ , and the molar ratio of the content of the Yb ³⁺ to the total content of ^{Yb 3+ (Yb 3+ / (La} 3+ + Gd 3+ + Y 3+ + Lu ³⁺ + Yb ³⁺ )) may be 0.5 or less.

According to one embodiment, the Zn ²⁺ content of the optical glass 2 may be 0 to 10%.

According to one embodiment, the total content of the alkali metal components of the optical glass 2 may be 0 to 30%.

According to one embodiment, the Rb ⁺ content of the optical glass 2 may be 0 to 1%.

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

According to one embodiment, the Li ⁺ content of the optical glass 2 may be 0 to 30%.

According to one embodiment, the Li ⁺ content of the optical glass 2 may be 2% or more.

According to one embodiment, the Li ⁺ content of the optical glass 2 may be 4 to 10%.

According to one embodiment, the Na ⁺ content of the optical glass 2 may be 0 to 10%.

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

According to one embodiment, the Si ⁴⁺ content of the optical glass 2 may be 0 to 5%.

According to one embodiment, the B ³⁺ content of the optical glass 2 may be 2% or less.

According to one embodiment, the Cl ^- content of the optical glass 2 may be 0 to 1%.

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

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

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

According to one aspect, Abbe number vd of the optical glass 2 may be 45 or more.

According to one embodiment, Abbe number vd of the optical glass 2 may be 80 or less.

According to an embodiment, in the optical glass 2, the refractive index nd and the Abbe number υd can satisfy the following expression (2).

nd ≥ 1.80653 - 0.00459 × υd (2)

According to an embodiment, in the optical glass 2, the refractive index nd and the Abbe number υd can satisfy the following expression (3).

nd ≥ 1.84303 - 0.00459 × υd (3)

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

According to one embodiment, the glass transition temperature Tg of the optical glass 2 may be 550 캜 or less.

According to one embodiment, the liquidus temperature of the optical glass 2 may be 850 DEG C or less.

According to one aspect, the specific gravity of the optical glass 2 may be 4.2 or less.

According to another aspect, an optical element comprising the optical glass 1 or the optical glass 2 is provided.

The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. It is intended that the scope of the invention be indicated by the appended claims rather than by the foregoing description, and that all changes and modifications within the meaning and range of equivalency of the claims are intended to be embraced therein.

For example, with respect to the exemplified glass composition described above, the glass according to one embodiment of the present invention can be obtained by performing the compositional adjustment described in the specification.

In addition, it is of course possible to arbitrarily combine two or more of the matters described as examples or preferable ranges in the specification.

Claims (7)

As essential components, it includes P ⁵⁺ , Al ³⁺ , Nb ⁵⁺ , O ^2- and F ^-
The molar ratio of the content of Al ³⁺ to the content of ^{P 5+ (Al 3+ / P 5+} ) of 0.30 or more,
The content of Nb ⁵⁺ is 1.0 cation% or more,
The content of O &^lt; ^2- &^gt; is 10 to 85%
The content of F &lt; ^- &gt; is 15 to 90%
(O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) of the content of O ^2- with respect to the total content of P ⁵⁺ and Nb ⁵⁺ is 3.0 or more. The method according to claim 1,
At least one alkaline earth metal component selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ ,
^Wherein the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is 20 cationic% or more. 3. The method according to claim 1 or 2,
The content of P ⁵⁺ is 5 to 40% by mass,
And an Al ³⁺ content of 5 to 30% by weight. 4. The method according to any one of claims 1 to 3,
Wherein the molar ratio (O ^2- / (P ⁵⁺ + Nb ⁵⁺ )) is 4.0 or less. 5. The method according to any one of claims 1 to 4,
At least one rare earth component selected from the group consisting of La ³⁺ , Gd ³⁺ , Y ³⁺ , Lu ³⁺ and Yb ³⁺ ,
La ³⁺ for the content of ^{Al 3+, Gd 3+, Y 3+} , Lu 3+ , and the total content of ^{Yb 3+ (La 3+ + Gd 3+} + Y 3+ + Lu 3+ + Yb 3+) molar ratio of ^{((La 3+ + Gd 3+ +} Y of ³⁺ + Lu ³⁺ + Yb ³⁺ ) / Al ³⁺ ) is not more than 0.3. As an optical glass made of glass fluorophosphate,
The mass reduction amount D _NaOH per unit area when immersed in an aqueous NaOH solution for 15 hours was less than 0.25 mg / cm 2 15 h,
Abbe number vd and partial dispersion ratio Pg, F satisfy the following expression (4)
Pg, F &gt; - 0.0004v + 0.5718 (4)
Lt; / RTI &gt; An optical element comprising the optical glass according to any one of claims 1 to 6.

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