TW202112690A - Optical glass and optical element capable of reducing occurrence of streaks while being manufactured and suitable for chromatic aberration correction - Google Patents

Abstract

The object of the invention is to provide an optical glass capable of reducing occurrence of streaks while being manufactured and suitable for chromatic aberration correction. Accordingly, the invention provides a fluorophosphate optical glass which viscosity at the liquidus temperature is 10.0dPa.s or more, and satisfies Pg, F>- 0.0004 [nu]d+0.5720, and the content of cations, based on %, includes the following ranges: from 5% or more to 55% or less, the content of P<SP>5+</SP>; from 5% or more to 50% or less, the content of Al<SP>3+</SP>;, and the content of Ba<SP>2+</SP>; from 3% or more to 50% or less.

Description

Optical glass and optical components

The present invention relates to optical glass and optical elements containing the optical glass.

Optical glass having abnormal dispersion has been known from the past, and an optical glass having high abnormal dispersion can be a suitable lens for chromatic aberration correction.

As one of optical glasses with high abnormal dispersion, fluorophosphate-based optical glasses can be cited. Fluorophosphate-based optical glass is easy to volatilize at high temperature, and when molten glass is poured into the mold, if the viscosity of the molten glass is low, the convection of the glass in the mold becomes obvious, and the homogeneity of the glass composition cannot be maintained. Streaks are produced. Streaks refer to homogeneous parts of optical properties such as refractive index, and are not preferable for optical glass materials.

In order to solve the above-mentioned problems, a method of lowering the temperature of the molten glass can be considered. By lowering the temperature of the molten glass, volatilization is reduced and the viscosity of the glass is also increased. Therefore, the convection of the glass can be suppressed. However, when the temperature of the glass is excessively lowered, it becomes easy to devitrify, and the difficulty of manufacturing becomes higher.

For example, Patent Document 1 discloses an abnormal dispersion and a viscosity of 4dPa at the liquidus temperature. Fluorophosphate optical glass of s or more. However, although the glass of the example of Patent Document 1 improves the viscosity at the liquidus temperature to some extent, it does not have the desired abnormal dispersion. Prior art literature Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2008-137877

The problem to be solved by the invention

The object of the present invention is to provide an optical glass that reduces the occurrence of streaks during manufacture and is more suitable for chromatic aberration correction. way of solving the problem

The inventors of the present invention have repeatedly conducted in-depth studies, and as a result, have found an optical glass that reduces the occurrence of streaks during manufacture and is more suitable for chromatic aberration correction, thereby completing the present invention. That is, the present invention includes the following contents. [1] A fluorophosphate-based optical glass with a viscosity of 10.0dPa at the liquidus temperature. s or more, and satisfies Pg, F>-0.0004νd+0.5720. [2] The optical glass according to [1], which has a refractive index (nd) of 1.45000 or more and 1.65000 or less, and an Abbe number (νd) of 45.0 or more and 85.0 or less. [3] The optical glass according to [1] or [2], which contains components in the following range in cationic %: P ⁵⁺ 5% or more and 55% or less, Al ³⁺ 5% or more and 50% or less, Ba ²⁺ 3% or more and 50% or less. [4] The optical glass according to any one of [1] to [3], which contains 20% or less of Ti ⁴⁺ in cationic %. [5] The optical glass according to any one of [1] to [4], which contains 30% or less of Nb ⁵⁺ in cationic %. [6] An optical element comprising the optical glass according to any one of [1] to [5]. The effect of the invention

The optical glass of the present invention is an optical glass that reduces the occurrence of streaks during manufacture and is more suitable for chromatic aberration correction.

Hereinafter, the present invention will be described, but the present invention is not limited to specific embodiments.

First, the glass characteristics of the present invention and the composition of the optical glass will be described. In the present specification, unless otherwise specified, the cation content and the total content of cationic components% (cation%) represents, unless otherwise stated, the anionic component (in the present specification, is O ^2-, F ^-, Cl ^-, Br ^-, I ^-) content and total anion content expressed in% (anion%). Here, the cation% is a value calculated by "(number of cations of interest/total number of cations of the glass component)×100", and represents the molar percentage of the amount of cations of interest to the total amount of cation components. In addition, the anion% is a value calculated by "(number of anions of interest/total anions of the glass component)×100", and represents the mole percentage of the amount of anions of interest to the total amount of anion components.

The ratio of the content of the cation components is equal to the ratio of the content of the cation component of interest expressed in cation %, and the ratio of the content of the anion components is equal to the ratio of the content of the anion component of interest expressed in anion %.

In addition, the content of glass constituents can be quantified by known methods such as inductively coupled plasma emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), ion chromatography, etc. In the present invention, the content of the glass constituent component being 0% means that the constituent component is not substantially contained, and it is allowed to contain the component to an unavoidable degree of impurities.

The refractive index of each wavelength is measured to the sixth place after the decimal point in accordance with JIS B 7071, and expressed in five places after the decimal point. The main dispersion nF-nC (in this specification, nF-nC is sometimes expressed as "D") and ng-nF are also expressed with five decimal places. Therefore, the changes of nd, D, and ng-nF are expressed with five decimal places. The Abbe number νd is expressed in two decimal places, and the amount of change in the Abbe number is also expressed in two decimal places. Pg, F are expressed with four decimal places, and the change of Pg, F is also expressed with four decimal places.

The optical glass of the present invention is specifically the optical glass of the "first embodiment" and the "second embodiment", and the present invention includes these first and second embodiments. In the following description, the "first embodiment" and the "second embodiment" are sometimes described separately.

[Optical Glass Features] (Partial specific dispersion Pg, F) The optical glass of the present invention is suitable for chromatic aberration correction, and preferably has high abnormal dispersion. As an index showing abnormal dispersion, partial dispersion ratios Pg, F are used.

The partial dispersion ratio Pg, F uses the refractive index nF under F rays (wavelength 486.13nm), the refractive index nC under C rays (wavelength 656.27nm), and the refractive index ng under g rays (wavelength 435.84nm), as in the formula ( 1) Represented as shown. Pg, F=(ng-nF)/(nF-nC)　　. . . (1)

It is preferable that the partial dispersion ratios Pg, F and Abbe number νd of the optical glass of the present invention satisfy the formula (2). Pg, F＞-0.0004νd＋0.5720　　. . . (2) The optical glass whose partial dispersion ratio Pg, F and Abbe number νd satisfy the formula (2) can be suitably used as an optical glass for high-order chromatic aberration correction.

Regarding the values of Pg and F of the optical glass of the present invention, the lower limit can be set to 0.5200 or more, 0.5250 or more, or 0.5300 or more, and the upper limit can be set to 0.6000 or less, 0.5950 or less, or 0.5900 or less.

In the optical glass of the first embodiment, the lower limits of the Pg and F values are preferably in the order of 0.545 or more, 0.550 or more, and 0.555 or more, and the upper limits are preferably in the order of 0.600 or less, 0.595 or less, and 0.590 or less. In the optical glass of the second embodiment, the lower limits of the values of Pg and F are preferably in the order of 0.520 or more, 0.525 or more, and 0.530 or more, and the upper limits are preferably in the order of 0.570 or less, 0.565 or less, and 0.560 or less.

(Viscosity at liquidus temperature LT) The viscosity of the optical glass of the present invention at the liquidus temperature LT is 10.0dPa. s above. If the viscosity at the liquidus temperature LT is 10.0dPa. s or more, when casting molten glass, streaks can be suppressed, and homogeneous glass can be obtained. The viscosity at the liquidus temperature LT is preferably 10.3dPa. s or more, more preferably 10.5dPa. s or more, more preferably 10.8dPa. s or more, more preferably 11.0dPa. s above. It should be noted that in this specification, the unit of viscosity is represented by "dPa.s", and its value is the same as "poise". It should be noted that in this specification, the viscosity of the glass melt is based on the viscosity measurement method of JIS standard Z8803, using a coaxial double rotating cylindrical rotary viscometer (manufactured by Tokyo Kogyo Co., Ltd., high-temperature viscosity measuring device RHEOTRONIC II (improved) Type)) and measured. The temperature of the optical glass as the sample was changed, the viscosity of the glass at each temperature was measured, and a graph representing the relationship between the viscosity and the temperature was created, and the graph was used to read the viscosity of the glass at the liquidus temperature.

(Liquid temperature LT) The optical glass of the present invention has a characteristic of high viscosity at the liquidus temperature LT, but the liquidus temperature LT itself is not particularly limited. The lower limit of the liquidus temperature LT of the optical glass of the present invention may be 450°C or higher, 470°C or higher, or 480°C or higher, and the upper limit may be 900°C or lower, 890°C or lower, or 880°C or lower.

In the optical glass of the first embodiment, the lower limit of the liquidus temperature LT is preferably 700°C or higher, 720°C or higher, 730°C or higher, 740°C or higher, and 750°C or higher, and the upper limit of the liquidus temperature LT is 900°C or lower , 890°C or lower, 880°C or lower, 870°C or lower, and 860°C or lower in the order of preference. In the optical glass of the second embodiment, the lower limit of the liquidus temperature LT is preferably in the order of 450°C or higher, 470°C or higher, 480°C or higher, 490°C or higher, and 500°C or higher, and the upper limit of the liquidus temperature LT is 720°C or lower , 700 or less, 690°C or less, 680°C or less, and 670°C or less in the order of preference. It should be noted that in this specification, for the liquidus temperature LT, 50g of glass is weighed in a given platinum crucible, kept at a given temperature for 2 hours, and then cooled to room temperature, through visual observation and utilization The surface and the inside of the glass were observed under magnification (at a magnification of 100 times) with an optical microscope, the presence or absence of precipitation of crystals was examined, and the lowest temperature (10° C. width) at which no crystals were confirmed was the liquidus temperature LT.

(Refractive index nd) The refractive index nd of the optical glass of the present invention is not particularly limited. The lower limit of the refractive index nd of the optical glass of the present invention can be 1.44000 or more, 1.44500 or more, or 1.45000 or more, and the upper limit of the refractive index nd can be 1.65000 or less, 1.64500 or less, or 1.64000 or less.

In the optical glass of the first embodiment, the lower limit of the refractive index nd is preferably in the order of 1.57000 or higher, 1.57500 or higher, 1.58000 or higher, 1.58500 or higher, and 1.59000 or higher. In addition, the upper limit of the refractive index nd is preferably in the order of 1.66000 or less, 1.65500 or less, 1.65000 or less, and 1.64500 or less. In the optical glass of the second embodiment, the lower limit of the refractive index nd is preferably in the order of 1.44000 or higher, 1.44500 or higher, 1.45000 or higher, 1.45500 or higher, and 1.46000 or higher. In addition, the upper limit of the refractive index nd is preferably in the order of 1.48500 or less, 1.48000 or less, 1.47500 or less, and 1.47000 or less.

(Abbe number νd) The Abbe number νd of the optical glass of the present invention is not particularly limited. The lower limit can be 44.00 or more, 44.50 or more, 45.00 or more, or 45.50 or more, and the upper limit can be 86.00 or less, 85.50 or less, or 85.00 or less. In the optical glass of the first embodiment, the lower limit of the Abbe number νd is preferably in the order of 45.00 or more, 45.50 or more, 46.00 or more, 46.50 or more, 47.00 or more, and 47.50 or more. In addition, the upper limit of the Abbe number νd is preferably in the order of 53.50 or less, 53.00 or less, 52.50 or less, 52.00 or less, and 51.50 or less. In the optical glass of the second embodiment, the lower limit of the Abbe number νd is preferably in the order of 75.00 or more, 75.50 or more, 76.00 or more, 76.50 or more, 77.00 or more, and 77.50 or more. In addition, the upper limit of the Abbe number νd is preferably in the order of 86.00 or less, 85.50 or less, 85.00 or less, 84.50 or less, 84.00 or less, and 83.50 or less.

[Optical glass composition] Below, the glass components which can be contained in the optical glass of this invention are demonstrated. The optical glass of the present invention is a fluorophosphate glass and contains at least fluorine (F), phosphorus (P), and oxygen (O).

(P ⁵⁺ component) In the optical glass of the present invention, the P ⁵⁺ component, which is an essential component, is a component that constitutes the skeleton of the glass, and is a component that improves the thermal stability of the glass. Furthermore, it is a component that contributes to low refractive index and low dispersion. ^{The lower limit of the P 5+} component contained in the optical glass of the present invention can be 5% or more and 7% or more, and the upper limit can be 55% or less, 50% or less, or 45% or less. In order to form a viscosity of 10.0dPa. For a glass skeleton that is greater than or equal to s and satisfies the formula: Pg, F>-0.0004νd+0.5720, for example, it is preferable that ^{the lower limit of the P 5+} component is 5% or more and the upper limit is 55% or less.

In the first embodiment, ^{the lower limit of P 5+} is preferably 10% or more, 15% or more, 20% or more, 22%, 25%, 28%, 29% or more, and the upper limit is 55% or less and 50% or less. , 45% or less, 42% or less, 40% or less, 39% or less, and 38% or less in the order of preference. In the second embodiment, ^{the lower limit of P 5+} is preferably in the order of 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, and 10% or more, and the upper limit is 35% or less, 30% or less, The order of 25% or less, 20% or less, 19% or less, 18% or less, and 17% or less is preferable.

(Si ⁴⁺ , B ³⁺ component) As the components of the optical glass of the present invention, in addition to the P ⁵⁺ component, as a component constituting the skeleton of the glass, a Si ⁴⁺ component and/or a B ³⁺ component may be contained. The Si ⁴⁺ component and the B ³⁺ component are components that improve the thermal stability of glass, and are components that contribute to low refractive index and low dispersion. The ^{content of each of the Si 4+} and B ³⁺ components is not particularly limited and may be arbitrarily contained. The upper limit of the content is preferably 10% or less, 5% or less, 3% or less, 1% or less, 0.1% or less, and 0% in this order. In this specification, the above 0% or more includes that the component is not contained substantially. It should be noted that ^{the preferable ranges of the Si 4+} component and the B ³⁺ component are the same in both the first embodiment and the second embodiment.

The total content of Si ⁴⁺ and B ³⁺ components is also preferably in the order of 10% or less, 5% or less, 3% or less, 1% or less, 0.1% or less, and 0%.

(Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ components) The optical glass of the present invention may contain Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ components (hereinafter these components are sometimes referred to as One or more of "alkali metal components"). Li ⁺ , Na ⁺ , K ⁺ , Rb ^+, and Cs ⁺ components are components that can improve the meltability and adjust the viscosity and refractive index of the glass, but when too much, they may be unstable to heat. The content of Li ⁺ component is not particularly limited. The upper limit is 30% or less, 25% or less, 20% or less, 15% or less, 13% or less, 11% or less, 9.0% or less, 7.5% or less, and 6.0% or less in the order Preferred. The lower limit is preferably in the order of 0% or more, more than 0%, 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, and 2.5% or more. It should be noted that ^{the above-mentioned content of the Li +} component is the same in both the first embodiment and the second embodiment.

Regarding the Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ components, the content is also arbitrary, but the upper limit of each content is 10% or less, 6.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% Below, the order of 0.5% or less is preferable. It is also possible to set all components to 0%. The above-mentioned contents of the Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ components are the same in the first embodiment and the second embodiment. It should be noted that, if necessary, ^{a part of the Li +} component may be replaced with another basal component (Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ component).

(Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ components) Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ components improve the melting and adjustment of glass If there are too many components of the viscosity and refractive index of the glass, it may become unstable to heat. The upper limit of the content of each of the Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ components can be 50% or less, 45% or less, or 40% or less, and the lower limit of the respective content can be set to 0, for example. % Above, above 0%, above 1%, above 3%.

Specifically, in the first embodiment, ^{the upper limit of the Mg 2+} content is preferably in the order of 8% or less, 6% or less, 4% or less, 2% or less, 1% or less, and 0.5% or less, and can be set to 0 % (Does not contain). In the second embodiment, ^{the upper limit of the Mg 2+} content is preferably in the order of 15% or less, 10% or less, 8% or less, 7% or less, 6% or less, and 5% or less. The lower limit is not particularly limited, and is preferably in the order of 0% or more, more than 0%, 1.0% or more, 1.5% or more, and 2.0% or more.

In the first embodiment, ^{the upper limit of Ca 2+} is preferably in the order of 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, and 4% or less, and it can also be set to 0% (not contained) . In the second embodiment, ^{the upper limit of Ca 2+} is not particularly limited, and is preferably in the order of 30% or less, 27% or less, 25% or less, 23% or less, 22% or less, 21% or less, and 20% or less. The lower limit is not particularly limited, and is preferably in the order of 0% or more, more than 0%, 1.0% or more, 5% or more, 7% or more, 9% or more, 11% or more, and 12% or more.

In the first embodiment, ^{the upper limit of Sr 2+} is preferably 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, and 4% or less in the order of 0% (not contained). In the second embodiment, ^{the upper limit of Sr 2+} is preferably in the order of 30% or less, 25% or less, 23% or less, 22% or less, 21% or less, and 20% or less. The lower limit is not particularly limited, but the order of 0% or more, more than 0%, 1.0% or more, 5% or more, 7% or more, 9% or more, 10% or more, and 11% or more is preferable.

In the first embodiment, ^{the upper limit of Ba 2+} is preferably in the order of 50% or less, 45% or less, 43% or less, 42% or less, 41% or less, 40% or less, and 39% or less. The lower limit is preferably in the order of 10% or more, 15% or more, 22% or more, 25% or more, 26% or more, 27%, 28% or more, and 29% or more. In the second embodiment, ^{the upper limit of Ba 2+} is preferably in the order of 25% or less, 23% or less, 20% or less, 18% or less, and 16% or less. The lower limit is not particularly limited, and is preferably in the order of 0% or more, 1.0% or more, 2% or more, 3% or more, and 4% or more. Among them, Ba ²⁺ is a component that contributes to viscosity and high refractive index/low dispersion. Therefore, in the fluorophosphate optical glass of the present invention, in order to achieve 10.0dPa. For the viscosity of s or more to achieve the desired refractive index/Abbe number, it is preferable that Ba ²⁺ be 3% or more and 50% or less. In addition, depending on the situation, a part of ^{Ba 2+ may be replaced with Mg 2+} , Ca ²⁺ , Sr ²⁺ , or Zn ²⁺ .

Regarding the Zn ²⁺ component, the content is also arbitrary, and the upper limit of each content is preferably in the order of 10% or less, 6.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, and 0.5% or less. It can also be set to 0%. The above-mentioned content of the Zn ²⁺ component is the same in both the first embodiment and the second embodiment.

The lower limit of the total content of each of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ^{2+ (Mg 2+} +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ ) can be set It is, for example, 15% or more, 20% or more, 25% or more, 27% or more, 28% or more, or 29% or more. The upper limit can be 60% or less, 55% or less, 52% or less, 50% or less, or 48% or less. It should be noted that ^{the value that the total content of the Mg 2+} +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Zn ²⁺ components can take is the same in both the first embodiment and the second embodiment.

(La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ components) La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ components and Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ Compared with the components, it is a component that increases the refractive index and contributes to high refractive index and low dispersion. However, if it is too large, the meltability may deteriorate. The content of each of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ components is not particularly limited, ^{and the upper limit of the content of each of La 3+} , Gd ³⁺ , Y ³⁺ and Yb ³⁺ components may be, for example, 20% or less , 10% or less, 7% or less, 5% or less. The lower limit is not particularly limited, and it can be set to 0% or more. In particular, regarding ^{the content of the Y 3+} component, in the first embodiment, the upper limit is preferably in the order of 20% or less, 10% or less, 7% or less, and 5% or less, and may be 0% (not contained). Regarding the content of the Y ³⁺ component, in the second embodiment, the upper limit may be 20% or less, 10% or less, 7% or less, or 5% or less. The lower limit is not particularly limited, and is preferably in the order of 0% or more, more than 0%, 0.5% or more, and 1.0% or more.

The total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ^{3+ components (La 3+} +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ) is also not particularly limited. La ³⁺ +Gd ³⁺ + The upper limit of Y ³⁺ +Yb ³⁺ may be, for example, 20% or less, 10% or less, 7% or less, or 5% or less.

(Ti ⁴⁺ component) The Ti ⁴⁺ component is a component that contributes to a higher refractive index and higher Pg and F, but if it is too much, it may cause higher dispersion. The upper limit of the content of the Ti ⁴⁺ component is preferably in the order of 20% or less, 10% or less, 5% or less, 4% or less, and 3% or less, and may be 0% (not contained). It should be noted that only in the second embodiment, the lower limit may be 1.0% or more.

(Nb ⁵⁺ component) Nb ⁵⁺ is a component that contributes to higher refractive index and higher Pg and F, but if it is too much, it may cause higher dispersion. The upper limit of the content of the Nb ⁵⁺ component is preferably in the order of 30% or less, 20% or less, 15% or less, 14% or less, and 13% or less, and may be 0% (not contained). In addition, in the first embodiment, the lower limit is preferably in the order of 1% or more, 3% or more, and 5% or more. In the fluorophosphate-based glass of the present invention, by setting ^{the upper limit of the content of the Ti 4+} component to the above-mentioned value and/or setting ^{the upper limit of the content of the Nb 5+} component to the above-mentioned value, it is easy to change the content of Pg, F The value is set to a value exceeding "-0.0004νd+0.5720". For example, by setting ^{the content of Ti 4+} component to 20% or less and/or setting ^{the content of Nb 5+} component to 30% or less, it is easy to set the values of Pg and F to exceed "-0.0004νd+0.5720" value.

Ta ⁵⁺ , W ^6+, and Bi ³⁺ components are components that contribute to a higher refractive index and higher Pg and F, but too much may cause higher dispersion. These components can be contained in the range which does not impair the characteristic of the optical glass of this invention. The content of each of the Ta ⁵⁺ , W ⁶⁺ and Bi ³⁺ components is not particularly limited, and the upper limit of each content can be set to 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less , It can also be set to 0% (not contained).

The total content of each of Ta ⁵⁺ , W ⁶⁺ and Bi ^{3+ components (Ta 5+} +W ⁶⁺ +Bi ³⁺ ) is also not particularly limited, and the upper limit can be 10% or less, 5% or less, or 4% or less , 3% or less, 2% or less, 1% or less. The lower limit can be set to 0% or more.

It should be noted that the optical glass of the present invention preferably contains Ti ⁴⁺ and/or Nb ⁵⁺ . In the case of optical glass with abnormal dispersion, Pg and F can be increased by adding these components. By adding these components, it may be possible to achieve high Pg and F such as the formula (1), which is preferable.

^{When the P 5+} component and Ti ⁴⁺ component are contained in the optical glass of the present invention, from the viewpoint of suppressing volatilization, the molar ratio of the ^{O 2-} component to the P ⁵⁺ component + Ti ^{4+ component (O 2-} /( P ⁵⁺ +Ti ⁴⁺ )) is preferably in the order of 3.0 or more, 3.1 or more, and 3.2 or more. From the viewpoint of the thermal stability of the glass, the upper limit is preferably in the order of 4.0 or less, 3.9 or less, and 3.8 or less. It should be noted that the value of the molar ratio (O ^2- /(P ⁵⁺ +Ti ⁴⁺ )) is calculated from the value of atomic %.

When the optical glass of the present invention contains a P ⁵⁺ component and a Nb ⁵⁺ component, from the viewpoint of suppressing volatilization, the molar ratio of the ^{O 2-} component to the P ⁵⁺ component + Nb ^{5+ component (O 2-} /( P ⁵⁺ +Nb ⁵⁺ )) is preferably in the order of 3.0 or more, 3.1 or more, and 3.2 or more. From the viewpoint of the thermal stability of the glass, the upper limit is preferably in the order of 4.0 or less, 3.9 or less, and 3.8 or less. It should be noted that the value of the molar ratio (O ^2- /(P ⁵⁺ +Nb ⁵⁺ )) is also calculated from the value of atomic %.

(Al ³⁺ component) The Al ³⁺ component is a component that improves chemical durability, and the introduction of this component may improve the thermal stability of the glass. In addition, Al ³⁺ sometimes has an effect of improving workability. When it is contained excessively, meltability may deteriorate. The content of the Al ³⁺ component is also not particularly limited. From the viewpoint of meltability, the ^{upper limit of the content of each Al 3+} component can be, for example, 50% or less, 45% or less, or 40% or less, and the lower limit can be 5% or more. , 8% or more, 10% or more. For example, by setting ^{the content of the Al 3+} component to be 5% or more and 50% or less, good chemical durability can be imparted to the fluorophosphate glass of the present invention, and depending on the situation, it can be made difficult to devitrify and can be easily stabilized. Realize the production of the glass.

In the first embodiment, ^{the upper limit of the Al 3+} component is preferably in the order of 30% or less, 25% or less, 22% or less, 21% or less, and 20% or less, and the lower limit is 5% or more, 8% or more, and 10% or more. , 12% or more, and 13% or more in the order of preference. Specifically, in the second embodiment, ^{the upper limit of the Al 3+} component is preferably in the order of 50% or less, 45% or less, 42% or less, 40% or less, and 38% or less, and the lower limit is 10% or more and 12% or more. , 15% or more, 17% or more, and 20% or more in the order of preference.

It should be noted that ^{the ratio of P 5+} to Al ³⁺ is not particularly limited, and the effect can be confirmed whether it is an optical glass with a relatively large amount of ^{P 5+} or a glass with a relatively large amount of ^{Al 3+.}

(Zr ⁴⁺ component) The Zr ⁴⁺ component is also a component that improves chemical durability. By introducing this component, the thermal stability of the glass may be improved. It can be contained in a small amount in the optical glass of the present invention, but if it is contained in an excessive amount, there will be It will cause deterioration of meltability. Therefore, ^{the upper limit of the content of each Zr 4+} component may be, for example, 10% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, It can be set to 0% (not contained). The ^{acceptable content of the Zr 4+} component is the same in both the first embodiment and the second embodiment.

If necessary, at least one cation of As, Sb, and Sn may be added to the glass. The cations of As, Sb, and Sn have a clarification effect when the glass is melted, and an effect of reducing the bulk platinum in the obtained glass. In addition, the oxidation/reduction state of glass may be adjusted in some cases. The content of the cations of As, Sb, and Sn is not particularly limited. The upper limit of the content of each of the cations of As, Sb, and Sn can be 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, or 0.5% or less. , 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, 0.04% or less, 0.03% or less, 0.02% or less, 0.01 % Or less, 0.009% or less, 0.008% or less, 0.007% or less, 0.006% or less, 0.005% or less, 0.004% or less, 0.003% or less, 0.002% or less, 0.001% or less. In addition, the lower limit of the content of each cation of As, Sb, and Sn may be 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% Above, 0.009% or more, 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.06% or more, 0.07% or more, 0.08% or more, 0.09% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more. It can also be set to not contain. The acceptable contents of the As, Sb, and Sn components are the same in the first embodiment and the second embodiment.

Optical Glass ^- (F component) of the present invention containing fluorine (F ^-) as an anion component. The content of F ^- is not particularly limited, and can be 90% or less, 85% or less, or 80% or less, and ^{the lower limit of the content of F-} can be 10% or more, 15% or more, or 20% or more.

^{Specifically, the upper limit of the F-} content in the first embodiment is preferably in the order of 50% or less, 45% or less, 43% or less, 40% or less, and 39% or less, and the lower limit is 15% or more and 20%. The order of above, 22% or above, 25% or above, and 27% or above is preferable. Further, the second embodiment of the F ^- content in accordance with the upper limit of 90% or less, 85% or less, 83% or less, 80% or less, preferably 78% or less of the order of addition, in accordance with the lower limit of 60% or more, 62% or more, The order of 65% or more, 68% or more, 70% or more, and 72% or more is preferable.

^{(Cl -, Br -, I} - component) in addition to the optical glass of the present invention is F ^-, it also may contain Cl ^-, Br ^-, I ^- halogen ions. The upper limit of each content can be 10% or less, 7% or less, 5% or less, 3% or less, 1% or less, 0.5% or less, and can be 0% (not contained).

Among these, by introducing F ^- and Cl ^-, of low dispersion can be achieved, and the effect of imparting a glass having anomalous dispersion properties, decrease the glass transition temperature and improve chemical durability.

It should be noted that when the inclusion of radioactive substances in the material is a problem depending on the application, it is preferable to suppress the radioisotope content to a certain level or less, or to intentionally not contain the radioisotope (but not to prevent mixing in the form of impurities). ).

[Method of manufacturing optical glass] The optical glass of the present invention can be obtained by, for example, mixing, melting, and molding glass raw materials so as to obtain predetermined characteristics. As the glass raw material, for example, a phosphate, a fluoride, an alkali metal compound, or an alkaline earth metal compound may be used. Regarding the melting method and molding method of glass, a known method may be used.

It should be noted that the "given temperature" of melting in the present invention refers to the temperature at which glass can be completely melted. The specific given temperature is (A) 950℃, or (B) the liquidus temperature of the glass (hereinafter sometimes referred to as LT) + 150℃~400℃, the temperature at which melting occurs (LT plus the temperature of 150℃~ LT plus a temperature of 400°C). Therefore, the given temperature satisfies either of the above (A) or (B). As a specific predetermined temperature, for example, 850, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C and the like can be mentioned.

The gas atmosphere in the melting of the optical glass of the present invention may be in the atmosphere, a non-oxidizing gas atmosphere, a reducing gas atmosphere, etc., and is preferably a non-oxidizing gas atmosphere (specifically, N ₂ gas atmosphere, Ar gas atmosphere, etc.), etc. melt. Example

Hereinafter, the present invention will be explained in detail using examples, but the present invention is not limited to the examples.

(Determination of optical glass properties) The method of using optical glass grade high-purity oxides, hydroxides, carbonates, nitrates, chlorides, fluorides, sulfates and other raw materials to obtain glasses with the compositions of the respective examples/comparative examples in Table 1 The raw materials were weighed and mixed to obtain the blended raw materials. Next, put each blended raw material into a platinum crucible and heat it to the given temperature as described above. After melting for 2 or 4 hours from the start of melting in a nitrogen atmosphere, it is stirred and homogenized, and then it is statically heated. Set, clarify, and then inject into the mold. After the glass is solidified, it moves to an electric furnace preheated to the vicinity of the slow cooling point of the glass, and slowly cools to room temperature. In this way, the glass-formed block of each Example/Comparative Example was produced. A test piece required for the measurement was cut out from each obtained glass block, polished, and characteristics were evaluated.

(1) Determination of nd, ng, nF, nC and Abbe number νd The refractive index nd, ng, nF, nC, and Abbe number νd of the glass obtained by the refractive index measurement method of JIS B 7071 were measured at a temperature reduction rate of -30°C/hour.

(2) Measurement of partial dispersion ratio Pg, F The partial dispersion ratios Pg, F are calculated from the nd, ng, nF, and nC obtained in (1) above.

The composition of the optical glass used in the Examples and Comparative Examples is shown in Table 1 (indicated by cationic% (cat.%) and anionic% (ani.%)) and Table 2 (indicated by atomic% (atom.%)) , Table 3 shows the characteristics of each optical glass. It should be noted that the values of nd, νd, Pg, and F in Table 3 are the values when the glass is melted for 1.5 hours.

It should be noted that LT (liquid phase temperature) and LT viscosity (viscosity at liquidus temperature) in Table 2 are values measured by the method described in the specification. It should be noted that the optical glass used in the measurement is 50 g in the case of the liquidus temperature LT measurement, and the glass volume is in the range of 12.5 ml ± 2.0 ml. In addition, the measurement of LT viscosity is performed under a glass volume of 20-25 cc.

Furthermore, the photograph when the optical glass obtained in Example 1 was polished is shown in FIG. 1, and the photograph when the optical glass obtained in Comparative Example 2 was polished is shown in FIG. Since the optical glass of Comparative Example 2 has low LT viscosity, streaks are observed due to the influence of convection and the like during casting. On the other hand, the optical glass of FIG. 1 has very few streaks and is useful as an optical glass.

The optical glass of the present invention can be used as a material for optical elements.

no.

[Fig. 1] A photograph of the polished surface of the optical glass of Example 1. [Fig. 2] A photograph of the polished surface of the optical glass of Comparative Example 2. [Fig.

Claims (6)

A fluorophosphate optical glass whose viscosity at the liquidus temperature is 10.0dPa. s or more, and satisfies Pg, F>-0.0004νd+0.5720. The optical glass according to claim 1, which has a refractive index (nd) of 1.45000 or more and 1.65000 or less, and an Abbe number (νd) of 45.0 or more and 85.0 or less. The optical glass according to claim 1 or 2, which contains the following components in cationic %: P ⁵⁺ 5% or more and 55% or less, Al ³⁺ 5% or more and 50% or less, Ba ²⁺ 3 % Above and below 50%. The optical glass according to any one of claims 1 to 3, which contains 20% or less of Ti ⁴⁺ in terms of cation %. The optical glass according to any one of claims 1 to 4, which contains 30% or less of Nb ⁵⁺ in terms of cation %. An optical element comprising the optical glass according to any one of claims 1 to 5.

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