CN112010554B

CN112010554B - Fluorophosphate glass, glass preform, optical element and optical instrument having the same

Info

Publication number: CN112010554B
Application number: CN201910473388.XA
Authority: CN
Inventors: 孙伟
Original assignee: CDGM Glass Co Ltd
Current assignee: CDGM Glass Co Ltd
Priority date: 2019-05-31
Filing date: 2019-05-31
Publication date: 2022-04-12
Anticipated expiration: 2039-05-31
Also published as: TWI738351B; WO2020238403A1; TW202104122A; CN112010554A

Abstract

The invention discloses fluorophosphate glass, a glass prefabricated member, an optical element and an optical instrument with the same, wherein the fluorophosphate glass comprises: a cation and an anion, the cation comprising: 25 to 40 mol% of P⁵⁺(ii) a 8 to 22 mol% of Al³⁺(ii) a 1 to 30 mol% Ln³⁺，Ln³⁺Is La³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of (a); 25 to 55 mol% of R²⁺，R²⁺Is Ba²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one of (a); the anion comprises: 38 to 50 mol% of F^‑(ii) a 50 to 62 mol% of O^2‑. The fluorophosphate glass has a refractive index of 1.52-1.60, an Abbe number of not less than 68, excellent optical properties and the like, and has a low high-temperature coefficient of the refractive index and a low stress optical coefficient, so that the market demand is met.

Description

Fluorophosphate glass, glass preform, optical element and optical instrument having the same

Technical Field

The invention belongs to the technical field of fluorophosphate glass, and particularly relates to fluorophosphate glass, a glass prefabricated member, an optical element and an optical instrument with the same.

Background

The fluorophosphate optical glass is used as a novel glass material with wider application, has the characteristic of low dispersion, can eliminate the special dispersion of a secondary spectrum in an optical system, improves the resolution ratio, obviously improves the imaging quality of the optical system, has lower softening temperature, and can be directly and precisely molded into a high-grade aspheric lens. In recent years, a large amount of optical glass applied to the fields of vehicle-mounted, security and the like is exposed outdoors for a long time, but the refractive index temperature coefficient and the stress optical coefficient of the existing fluorophosphate glass are often high, the thermal stability is poor and the glass is not suitable for high outdoor temperature, and particularly under the condition of high-power optical application, the glass has poor thermal performance, high energy density enters the glass to cause glass explosion, the internal structure of the glass is changed even if the glass is not exploded, and the imaging quality is reduced.

Therefore, there is an urgent need to develop a fluorophosphate optical glass having a higher refractive index and a low dispersion, a refractive index of 1.52 to 1.60, an Abbe number of 68 to 75, a low temperature coefficient of refractive index, and a low stress optical coefficient.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a fluorophosphate glass having a refractive index of 1.52 to 1.60, an abbe number of not less than 68, excellent optical properties and the like, and having a low temperature coefficient of refractive index and a low stress optical coefficient, and to provide a glass preform, an optical element and an optical instrument having the same, which satisfy market demands.

In one aspect of the invention, a fluorophosphate glass is presented. According to an embodiment of the invention, the fluorophosphate glass comprises: a cation and an anion, wherein the cation comprises: 25 to 40 mol% of P⁵⁺(ii) a 8 to 22 mol% of Al³⁺(ii) a 1 to 30 mol% Ln³⁺，Ln³⁺Is La³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of (a); 25 to 55 mol% of R²⁺，R²⁺Is Ba²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one of (a); the anion comprises: 38 to 50 mol% of F^-(ii) a 50 to 62 mol% of O^2-。

The inventor finds that the fluorophosphate glass has the refractive index of 1.52-1.60, the Abbe number of not less than 68, excellent optical performance and the like, and has a lower high-temperature coefficient of the refractive index and a lower stress optical coefficient by controlling the components and the content of the fluorophosphate glass, so that the fluorophosphate glass meets the market demand.

In addition, the fluorophosphate glass according to the above embodiment of the present invention can also have the following additional technical features:

in some embodiments of the present invention, the cations in the above fluorophosphate glass compositions comprise: 30 to 37 mol% of P⁵⁺Preferably 31 to 36 mol% of P⁵⁺(ii) a And/or 10 to 20 mol% of Al³⁺Preferably 12 to 17 mol% of Al³⁺(ii) a And/or 2 to 20 mol% of Ln³⁺Preferably 3 to 15 mol% of Ln³⁺(ii) a And/or 30 to 50 mol% of R²⁺Preferably 35 to 45 mol% of R²⁺. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the invention, Ln is present in the fluorophosphate glass composition described above³⁺The method comprises the following steps: 0 to 8 mol% of La³⁺Preferably 0 to 5 mol% of La³⁺Not containing endpoint 0, more preferably 0.54 mol% La³⁺(ii) a And/or 1 to 10 mol% of Gd³⁺Preferably 1 to 6 mol% of Gd³⁺More preferably 1 to 5 mol% of Gd³⁺(ii) a And/or 1 to 10 mol% of Y³⁺Preferably 1 to 8 mol% of Y³⁺More preferably 2 to 6 mol% of Y³⁺(ii) a And/or 0 to 10 mol% of Yb³⁺Preferably 0 to 5 mol% of Yb³⁺. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, R is as defined above for the fluorophosphate glass compositions²⁺The method comprises the following steps: 25 to 40 mol% of Ba²⁺Preferably 28 to 38 mol% of Ba²⁺More preferably 30 to 35 mol% of Ba²⁺(ii) a And/or 0 to 10 mol% of Ca²⁺Preferably 0 to 5 mol% of Ca²⁺(ii) a And/or 3 to 15 mol% of Sr²⁺Preferably 5 to 12 mol% of Sr²⁺More preferably 5 to 10 mol% of Sr²⁺(ii) a And/or 0 to 10 mol% of Mg²⁺Preferably 0 to 5 mol% of Mg²⁺. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, the anions in the above fluorophosphate glass compositions comprise: 41 to 48 mol% of F^-Preferably 42 to 46 mol% of F^-(ii) a And/or 52 to 59 mol% of O^2-Preferably 54 to 58 mol% of O^2-. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_Ln ³⁺/n_R ²⁺Greater than 0.11, preferably n_Ln ³⁺/n_R ²⁺More than 0.135, and more preferably 0.14 to 0.65. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, Ln is³⁺Is Y³⁺And/or La³⁺Said R is²⁺Is Sr²⁺And/or Ba²⁺. Thereby, the excellent properties of the fluorophosphate glass can be ensuredCan be used.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(Sr ²⁺+_Y ³⁺ ₎/n_(Al ³⁺ _+Ba ²⁺ ₎0.25 to 0.43, inclusive, of 0.25, preferably 0.265 to 0.375, exclusive, of 0.265. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(Gd ³⁺+_La ³⁺ ₎/n_(Y ³⁺ _+Ba ²⁺ ₎Greater than 0.085, preferably greater than 0.11, more preferably between 0.115 and 0.165. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(sr ²⁺+_Ba ²⁺ ₎/n_(Y ³⁺ _+Gd ³⁺ _+La ³⁺ ₎The content is 3.45 to 9, preferably 3.45 to 7.6, and more preferably 3.55 to 5.55. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(Y ³⁺+_Gd ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ ₎Greater than 0.08, preferably 0.105 to 0.26, more preferably 0.105 to 0.195. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(Y ³⁺+_Gd ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Ba ²⁺ ₎Less than 0.12, preferably 0.075 to 0.115. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the invention, the above-described fluorophosphorusIn the acid salt glass composition, n_(Y ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Y ³⁺ ₎Greater than 0.07, preferably 0.075 to 0.5. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, in the above fluorophosphate glass composition, n_(Y ³⁺+_Gd ³⁺+_Ba ²⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺+_Ba ²⁺ ₎0.435 to 0.505, preferably 0.44 to 0.5. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, the cations in the above fluorophosphate glass composition further comprise: 0 to 15 mol% of Li⁺Preferably 0 to 10 mol% of Li⁺(ii) a And/or 0 to 15 mol% of Na⁺Preferably 0 to 10 mol% of Na⁺(ii) a And/or 0 to 10 mol% of K⁺Preferably 0 to 5 mol% of K⁺(ii) a And/or 0 to 8 mol% of B³⁺Preferably 0 to 5 mol% of B³ ⁺(ii) a And/or 0 to 10 mol% of Zn²⁺Preferably 0 to 5 mol% of Zn²⁺(ii) a And/or 0 to 8 mol% of In³⁺Preferably 0 to 5 mol% of In³⁺(ii) a And/or 0 to 5 mol% of Nb⁵⁺Preferably 0 to 3 mol% of Nb⁵⁺(ii) a And/or 0 to 5 mol% of Ti⁴⁺Preferably 0 to 3 mol% of Ti⁴⁺(ii) a And/or 0 to 5 mol% of Zr⁴⁺Preferably 0 to 3 mol% of Zr⁴⁺(ii) a And/or 0 to 5 mol% of Ta⁵⁺Preferably 0 to 3 mol% of Ta⁵⁺(ii) a And/or 0 to 5 mol% Ge⁴⁺Preferably 0 to 3 mol% of Ge⁴⁺. Thus, the fluorophosphate glass can be ensured to have excellent properties.

In some embodiments of the present invention, the fluorophosphate glass has a refractive index of 1.52 to 1.60, preferably 1.53 to 1.58, more preferably 1.55 to 1.58, and an Abbe number of 68 to 75, preferably 69 to 74, more preferably 70 to 73.

In some embodiments of the invention, the fluorophosphate glass has a temperature coefficient of refractive index of-4.0X 10^-6Below centigrade, preferably-5.0X 10^-6Below per degree centigrade, more preferably-7.5X 10^-6Below/degree centigrade, the acid resistance stability is not less than 2 grade, preferably not less than 1 grade, the water resistance stability is not less than 2 grade, preferably not less than 1 grade, the transition temperature is not more than 510 degree centigrade, preferably not more than 500 degree centigrade, more preferably not more than 495 degree centigrade, lambda₈₀No more than 370nm, preferably no more than 360nm, more preferably no more than 350nm, lambda₅Not greater than 310nm, preferably not greater than 300nm, more preferably not greater than 295nm, and an abrasion degree of not greater than 500, preferably not greater than 450.

In yet another aspect of the present invention, a glass preform is provided. According to an embodiment of the present invention, the glass preform is made of the above-described fluorophosphate glass.

In a third aspect of the invention, an optical element is presented. According to an embodiment of the present invention, the optical element is made of the above-described fluorophosphate glass or the above-described glass preform.

In a fourth aspect of the invention, an optical instrument is presented. According to an embodiment of the present invention, the optical instrument has the optical element described above.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Detailed Description

The following detailed description of embodiments of the invention is intended to be illustrative, and is not to be construed as limiting the invention.

Unless otherwise indicated in a particular context, numerical ranges set forth herein include both upper and lower limits, and "above" and "below" include the endpoints, all integers and fractions within the range, and are not limited to the specific values listed in the defined range. As used herein, "and/or" is inclusive, e.g., "A and/or B," and means A alone, B alone, or both A and B.

The ion valence of each component described below is a representative value used for convenience, and is not different from other ion valence. The ion valence of each component in the optical glass may be out of the representative value. For example, P is usually present in the glass in a state where the ion valence is +5, and hence "P" is used in the present invention⁵⁺"as a representative value, but may exist in other ion valence states, and this is within the scope of the present invention.

In one aspect of the invention, a fluorophosphate glass is presented. According to an embodiment of the invention, the fluorophosphate glass comprises: a cation and an anion, the cation comprising: 25 to 40 mol% of P⁵⁺(ii) a 8 to 22 mol% of Al³⁺(ii) a 1 to 30 mol% Ln³⁺，Ln³⁺Is La³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of (a); 25 to 55 mol% of R²⁺，R²⁺Is Ba²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one of (a); the anion comprises: 38 to 50 mol% of F^-(ii) a 50 to 62 mol% of O^2-. It should be noted that the mole% of the component in the cation is the ratio of the cation to the total moles of all the cations, and the mole% of the component in the anion is the ratio of the anion to the total moles of all the anions.

Glass composition:

P⁵⁺is an important component for reducing dispersion in fluorophosphate glass, and is a main component affecting glass imaging and outdoor high-temperature durability. When the amount incorporated is less than 25 mol%, the glass stability is lowered, the tendency to devitrify increases, and the temperature coefficient of refractive index is low, but when the amount incorporated is more than 40 mol%, the predetermined optical properties cannot be satisfied. Thus, P of the present invention⁵⁺The content of (A) is 25 to 40 mol%, preferably P⁵⁺The content of (b) is 30 to 37 mol%, more preferably 31 to 36 mol%.

Al³⁺Is an important component for improving the stability of glass formation, and is a structural component serving as a network skeleton in the fluorophosphate glass. When the amount incorporated is less than 8 mol%, the glass stability is low, but when the amount incorporated is more than 22 mol%, the glass transition temperature and the crystallization upper limit temperature are greatly increased, resulting in an increase in the forming temperature. Thus, Al of the present invention³⁺The content of (C) is 8 to 22 mol%, preferably Al³⁺The content of (b) is 10 to 20 mol%, more preferably 12 to 17 mol%.

La³⁺、Gd³⁺、Y³⁺And Yb³⁺The refractive index of the glass can be increased, but Ln³⁺(selected from La)³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of) less than 1 mol%, the influence on the refractive index of the glass is small, but Ln³⁺Above 30 mol%, the stability of the glass is deteriorated, and the glass transition temperature is increased, resulting in a decrease in the stability of the glass. Thus, Ln of the present invention³⁺1 to 30 mol%, preferably 2 to 20 mol%, more preferably 3 to 15 mol%, wherein the La is contained in an amount of 0 to 8 mol%³⁺Preferably 0 to 5 mol% of La³⁺La is not contained at 0% by mole, and more preferably 0.5 to 4% by mole³⁺(ii) a And/or 1 to 10 mol% of Gd³⁺Preferably 1 to 6 mol% of Gd³⁺More preferably 1 to 5 mol% of Gd³⁺(ii) a And/or 1 to 10 mol% of Y³⁺Preferably 1 to 8 mol% of Y³⁺More preferably 2 to 6 mol% of Y³⁺(ii) a And/or 0 to 10 mol% of Yb³⁺Preferably 0 to 5 mol% of Yb³⁺More preferably, it is not incorporated.

Ba²⁺、Ca²⁺、Sr²⁺And Mg²⁺The stability and refractive index of the glass can be improved, but R²⁺(selected from Ba)²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one of) less than 25 mol%, the effect on the stability of the glass and the improvement in the stability of the glass are not significant, but R is not substantially equal to²⁺Above 55 mol%, this results in a sharp decrease in the stability of the glass and also in a significant decrease in the glass dispersion. Thus, R of the present invention²⁺25 to 55 mol%, preferably30 to 50 mol%, more preferably 35 to 45 mol%, can improve the refractive index and simultaneously can not excessively reduce the dispersion of the glass, wherein the Ba comprises 25 to 40 mol%²⁺Preferably 28 to 38 mol% of Ba²⁺More preferably 30 to 35 mol% of Ba²⁺(ii) a And/or 0 to 10 mol% of Ca²⁺Preferably 0 to 5 mol% of Ca²⁺More preferably not incorporated; and/or 3 to 15 mol% of Sr²⁺Preferably 5 to 12 mol% of Sr²⁺More preferably 5 to 10 mol% of Sr²⁺(ii) a And/or 0 to 10 mol% of Mg²⁺Preferably 0 to 5 mol% of Mg²⁺More preferably, it is not incorporated.

F^-The melting point and dispersion of the glass can be reduced, and the temperature coefficient of refractive index of the glass can also be reduced. When the amount of incorporation is less than 38 mol%, the melting point of the glass is high, resulting in poor processability, and the high temperature resistance of the glass is poor, but when it is more than 50 mol%, the volatility of the glass during melting increases, the degree of glass loss increases, and the refractive index property also becomes poor. Thus, F of the present invention^-The content of (A) is 38 to 50 mol%, preferably F^-The content of (b) is 41 to 48 mol%, more preferably 42 to 46 mol%.

O^2-Is an essential component of a glass network structure, can improve the stability of glass, inhibit the devitrification of the glass and reduce the abrasion degree. When the amount incorporated is less than 50 mol%, the effect of suppressing devitrification and abrasion of the glass is insignificant, but when the amount incorporated is more than 62 mol%, the viscosity of the glass is increased and the melting temperature is increased, resulting in deterioration of transmittance. Thus, O of the present invention^2-Is 50 to 62 mol%, preferably O^2-The content of (b) is 52 to 59 mol%, more preferably 54 to 58 mol%.

The inventors have found that the fluorophosphate glass of the present invention has a refractive index of 1.52 to 1.60, preferably 1.53 to 1.58, more preferably 1.55 to 1.58, an Abbe number of 68 to 75, preferably 69 to 74, more preferably 70 to 73, and λ by controlling the components and the content thereof₈₀No more than 370nm, preferably no more than 360nm, more preferably no more than 350nm, lambda₅Not greater than 310nm, preferably not greaterAt 300nm, more preferably not more than 295nm, and a temperature coefficient of refractive index of-4.0X 10^-6Below centigrade, preferably-5.0X 10^-6Below per degree centigrade, more preferably-7.5X 10^-6Below centigrade, stress optical coefficient not higher than 0.6 x 10^-12/Pa, preferably not higher than 0.5X 10^-12/Pa, more preferably not higher than 0.4X 10^-12and/Pa, meeting the market demand.

Meanwhile, the fluorophosphate glass of the present application is required to have excellent stability against water and acid resistance, etc., and the inventors of the present application have found through extensive studies that Ln in the glass component can be controlled³⁺(selected from La)³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of) and R)²⁺(selected from Ba)²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one) of the above-mentioned components is used_Ln ³⁺/n_R ²⁺More than 0.11, the components play a synergistic effect, the refractive index of the glass and the stability of acid resistance and water resistance can be further improved, the dispersion and the temperature coefficient of the refractive index are further reduced, the stability of the acid resistance of the obtained fluorophosphate glass is not lower than 2 grade, the stability of the water resistance is not lower than 2 grade, and the Ln in the glass components is further preferably controlled³⁺Number of moles and R²⁺Ratio of moles n_Ln ³⁺/n_R ²⁺More than 0.135, the obtained fluorophosphate glass has acid resistance stability of not less than grade 1, water resistance stability of not less than grade 1, and Ln in the glass component can be controlled preferably³⁺Number of moles and R²⁺Ratio of moles n_Ln ³⁺/n_R ²⁺0.14 to 0.65. Further, Ln is preferable³⁺Is Y³⁺And/or La³⁺More preferably Ln³⁺Is Y³⁺And La³⁺Sum, preferably R²⁺Is Sr²⁺And/or Ba²⁺More preferably R²⁺Is Sr²⁺And Ba²⁺In sum, the resulting fluorophosphate glass has excellent optical properties as well as a lower temperature coefficient of refractive index and a lower stress optical coefficient.

Further, the fluorophosphate glass of the present applicationThe glass is required to have excellent glass forming stability and lower abrasion degree, and the inventors of the present invention found through extensive studies that by controlling Sr in the glass component²⁺And Y³⁺The total mole number of (3) and Al³⁺And Ba²⁺Ratio of total number of moles (n)_(Sr ²⁺+_Y ³⁺ ₎/n_(Al ³⁺ _+Ba ²⁺ ₎) 0.25-0.43, no endpoint of 0.25, synergistic action among the components, glass forming stability and optical property of the glass can be further improved, abrasion degree is reduced, processability of the glass is improved, abrasion degree of the obtained fluorophosphate glass is not higher than 500, and Sr in glass components is preferably controlled²⁺And Y³⁺The total mole number of (3) and Al³⁺And Ba²⁺Ratio of total number of moles (n)_(Sr ²⁺+_Y ³⁺ ₎/n_(Al ³⁺ _+Ba ²⁺ ₎) 0.265-0.375, and no endpoint 0.265, so that the abrasion degree of the obtained fluorophosphate glass is not higher than 450.

Further, the inventors have found that by controlling Gd in the glass component²⁺And La³⁺The total mole number of (2) and Y³⁺And Ba²⁺Ratio of total number of moles (n)_(Gd ³⁺+_La ³⁺ ₎/n_(Y ³⁺ _+Ba ²⁺ ₎) More than 0.085, the glass forming stability and optical property of the glass can be further improved, and the transition temperature is obviously lower, so that the glass is easy to mold, the damage to a mold is small, the service life of the mold is ensured, the transition temperature of the obtained fluorophosphate glass is not higher than 510 ℃, and Gd in the glass components is further preferably controlled²⁺And La³⁺The total mole number of (2) and Y³⁺And Ba²⁺Ratio of total number of moles (n)_(Gd ³⁺+_La ³⁺ ₎/n_(Y ³⁺ _+Ba ²⁺ ₎) More than 0.11, the transition temperature of the resulting fluorophosphate glass is not higher than 500 degrees centigrade, and Gd in the glass component is more preferably controlled²⁺And La³⁺The total mole number of (2) and Y³⁺And Ba²⁺Ratio of total number of moles (n)_(Gd ³⁺+_La ³⁺ ₎/n_(Y ³⁺ _+Ba ²⁺ ₎) The temperature is 0.115-0.165, and the transition temperature of the obtained fluorophosphate glass is not higher than 495 ℃.

Further, the inventors have also found that by controlling Sr in the glass component²⁺And Ba²⁺The total mole number of (2) and Y³⁺、Gd³⁺And La³⁺Ratio of total number of moles (n)_(sr ²⁺+_Ba ²⁺ ₎/n_(Y ³⁺ _+Gd ³⁺ _+La ³⁺ ₎) 3.45 to 9, can further improve the glass forming stability of the glass, can not excessively reduce dispersion while improving the refractive index of the glass, and preferably controls Sr in the glass component²⁺And Ba²⁺The total mole number of (2) and Y³⁺、Gd³⁺And La³⁺Ratio of total number of moles (n)_(sr ²⁺+_Ba ²⁺ ₎/n_(Y ³⁺ _+Gd ³⁺ _+La ³⁺ ₎) Is 3.45 to 7.6, more preferably 3.55 to 5.55.

Further, the fluorophosphate glass of the present application is also required to have a low specific gravity, and the inventors have found that by controlling Y in the glass component³⁺And Gd³⁺、La³⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ ₎) More than 0.08, the components have synergistic effect, the refractive index and dispersion of the glass can be further adjusted, the specific gravity and abrasion degree are further reduced, and the density of the obtained fluorophosphate glass is not higher than 4.7g/cm³Further preferably by controlling Y in the glass component³⁺And Gd³⁺、La³⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ ₎) 0.105 to 0.26, and the density of the obtained fluorophosphate glass is not higher than 4.6g/cm³More preferably, Y in the glass component is controlled³⁺And Gd³⁺、La³⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ ₎) 0.105 to 0.195, and the density of the obtained fluorophosphate glass is not higher than 4.5g/cm³。

Further, the inventors have found that by controlling Y in the glass component³⁺And Gd³⁺The total mole number of (2) and P⁵⁺、Al³⁺、Sr²⁺And Ba²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Ba ²⁺ ₎) More than 0.12, can further facilitate the adjustment of the refractive index of the glass, ensure the dispersion performance, have good glass forming stability and lower transition temperature, and preferably control Y in the glass component³⁺And Gd³⁺The total mole number of (2) and P⁵⁺、Al³⁺、Sr²⁺And Ba²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Ba ²⁺ ₎) 0.075-0.115.

Further, the inventors have found that by controlling Y in the glass component³⁺And La³⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺、Y³⁺Ratio of total number of moles (n)_(Y ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Y ³⁺ ₎) More than 0.07, the optical characteristics of the glass can be further improved, and the stress optical coefficient is further lowered and the temperature coefficient of the refractive index is further lowered, and it is further preferable to control Y in the glass component³⁺And La³⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺、Y³⁺Ratio of total number of moles (n)_(Y ³⁺+_La ³⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Y ³⁺ ₎) 0.075-0.5.

Further, the inventors have found that by controlling Y in the glass component³⁺And Gd³⁺、Ba²⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺、Ba²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺+_Ba ²⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺+_Ba ²⁺ ₎) Is 0.435-0.505, is more favorable for reducing F volatilization, can further improve the optical property and refractive index stability of the glass, can further reduce the specific gravity of the glass, and preferably controls Y in the glass component³⁺And Gd³⁺、Ba²⁺The total mole number of (2) and P⁵⁺And Al³⁺、Sr²⁺、Ba²⁺Ratio of total number of moles (n)_(Y ³⁺+_Gd ³⁺+_Ba ²⁺ ₎/n_(P ⁵⁺ _+Al ³⁺ _+Sr ²⁺+_Ba ²⁺ ₎) 0.44 to 0.5.

According to yet another embodiment of the present invention, the positive ions in the above fluorophosphate glass composition further comprise: 0 to 15 mol% of Li⁺Preferably 0 to 10 mol% of Li⁺(ii) a And/or 0 to 15 mol% of Na⁺Preferably 0 to 10 mol% of Na⁺(ii) a And/or 0 to 10 mol% of K⁺Preferably 0 to 5 mol% of K⁺(ii) a And/or 0 to 8 mol% of B³⁺Preferably 0 to 5 mol% of B³ ⁺(ii) a And/or 0 to 10 mol% Zn²⁺Preferably 0 to 5 mol% of Zn²⁺(ii) a And/or 0 to 8 mol% of In³⁺Preferably 0 to 5 mol% of In³⁺(ii) a And/or 0 to 5 mol% of Nb⁵⁺Preferably 0 to 3 mol% of Nb⁵⁺(ii) a And/or 0 to 5 mol% of Ti⁴⁺Preferably 0 to 3 mol% of Ti⁴⁺(ii) a And/or 0 to 5 mol% of Zr⁴⁺Preferably 0 to 3 mol% of Zr⁴⁺(ii) a And/or 0 to 5 mol% of Ta⁵⁺Preferably 0 to 3 mol% of Ta⁵⁺(ii) a And/or 0 to 5 mol% Ge⁴⁺Preferably 0 to 3 mol% of Ge⁴⁺. The inventors found that Li⁺The glass transition temperature can be lowered without impairing the glass stability, and when the incorporation amount thereof is more than 35 mol%, the glass stability is lowered and the glass processability is deteriorated. Thus, Li of the present invention⁺The content of (B) is 0 to 15 mol%, preferably Li⁺The content of (b) is 0 to 10 mol%, and more preferably, it is not incorporated. Na (Na)⁺The glass can be improved in melting property, resistance to devitrification, and transmittance in the visible light region, but when the incorporation amount thereof is more than 15 mol%, the stability of the glass is lowered. Thus, Na of the invention⁺The content of (b) is 0 to 15 mol%, preferably 0 to 10 mol%, more preferably not incorporated. K⁺The viscosity and transition temperature of the glass can be lowered, but when it is incorporated in an amount of more than 10 mol%, the stability of the glass is lowered. Thus, K of the invention⁺The content of (b) is 0 to 10 mol%, preferably 0 to 5 mol%, more preferably not incorporated. B is³⁺The stability of the glass can be improved, but when it is incorporated in an amount of more than 8 mol%, it is easy to form BF in the course of melting₃The forms volatilize and thus cause streaks. Thus, B of the present invention³⁺The content of (b) is 0 to 8 mol%, preferably 0 to 5 mol%, more preferably not incorporated. Zn²⁺The devitrification resistance, stability and processability of the glass can be improved, and when the incorporation amount thereof is more than 10 mol%, the devitrification resistance of the glass is rather remarkably reduced. Thus, Zn of the present invention²⁺Is 0 to 10 mol%, preferably Zn²⁺The content of (b) is 0 to 5 mol%, and more preferably, it is not incorporated. In³⁺The glass stability can be improved, but when it is incorporated in an amount of more than 8 molAt this point, the stability of the glass is drastically lowered. Thus, In of the present invention³⁺Is 0 to 8 mol%, preferably In³⁺The content of (b) is 0 to 5 mol%, and more preferably, it is not incorporated. Nb⁵⁺And Ti⁴⁺The refractive index of the glass can be increased, but Nb⁵⁺And Ti⁴⁺When the amount of each of (A) and (B) is more than 5 mol%, the stability of the glass is lowered, and therefore, the Nb of the present invention⁵⁺Is 0 to 5 mol%, preferably 0 to 3 mol%, more preferably not introduced, and Ti⁴⁺The content of (b) is 0 to 5 mol%, preferably 0 to 3 mol%, more preferably not incorporated. Zr⁴⁺The Zr content in the present invention is because the Zr content in the glass of the present invention can increase the refractive index of the glass and can suppress the glass striae caused by volatilization of components in the glass, but when the content is more than 5 mol%, the stability of the glass is lowered⁴⁺The content of (b) is 0 to 5 mol%, preferably 0 to 3 mol%, more preferably not incorporated. Ta⁵⁺The refractive index of the glass can be increased and the devitrification of the glass can be reduced, but when the incorporation amount thereof is more than 5 mol%, the stability of the glass is lowered, and therefore, the Ta of the present invention⁵⁺The content is 0 to 5 mol%, preferably 0 to 3 mol%, and more preferably, no incorporation is performed. Ge (germanium) oxide⁴⁺The refractive index and devitrification resistance of the glass can be improved, but the incorporation thereof more than 5 mol% leads to an increase in glass cost, and therefore, the Ge of the present invention⁴⁺The content is 0 to 5 mol%, and 0 to 3 mol, preferably no introduction is performed.

In the present invention, "not including", "not containing", "not introducing" and "0%" mean that the compound, molecule, element or the like is not intentionally added to the glass of the present invention as a raw material; however, it is also within the scope of the present invention that certain impurities or components, which are not intentionally added, may be present as raw materials and/or equipment for producing the glass, and may be present in small or trace amounts in the final glass.

The performance and the test method of the fluorophosphate glass of the present invention will be described below.

1. Degree of coloration (. lamda.)₈₀/λ₅)

Short wave transmission of the glass of the inventionDegree of coloration (lambda) for spectral characteristics₈₀/λ₅) And (4) showing. Lambda [ alpha ]₈₀Refers to the wavelength, lambda, corresponding to a glass having a transmittance of 80%₅Refers to the wavelength corresponding to the glass transmittance of 5%, wherein₈₀Was measured using a glass having a thickness of 10. + -. 0.1mm with two opposing planes parallel to each other and optically polished, measuring the spectral transmittance in the wavelength region from 280nm to 700nm and showing a wavelength of transmittance of 80%. The spectral transmittance or transmittance is the intensity I of light incident perpendicularly to the surface of the glass_inLight transmitted through the glass and having an intensity I emitted from a plane_outIn the case of light of (1) through (I)_out/I_inThe quantity expressed and also the transmission of the surface reflection losses on the above-mentioned surface of the glass. The higher the refractive index of the glass, the greater the surface reflection loss. Therefore, in the optical glass of the present invention, λ₈₀A small value of (b) means that the glass itself is less colored. The optical glass of the present invention has a wavelength (lambda) corresponding to 80% transmittance₈₀) Not more than 370nm, preferably not more than 360nm, more preferably not more than 350nm, and a wavelength (. lamda.) corresponding to a glass transmittance of 5%₅) Not greater than 310nm, preferably not greater than 300nm, more preferably not greater than 295 nm.

The spectral transmittance was measured using a glass sample having a thickness of 10. + -. 0.1mm with two optically polished planes opposed to each other, and calculated from the result thereof.

2. Density of

The density of the fluorophosphate glass is the weight per unit volume at a temperature of 20 ℃ in g/cm³It is shown that the density of the fluorophosphate glass of the present invention is not higher than 4.7g/cm³Preferably not higher than 4.6g/cm³More preferably not higher than 4.5g/cm³。

The measurement was carried out according to the method specified in GB/T7962.20-2010.

3. Transition temperature T_g

The fluorophosphate glass gradually changes from a solid state to a plastic state in a certain temperature interval. Transition temperature T_gMeans that the temperature of the glass sample is raised from room temperature to the sag temperature T_sLow temperature region and highThe temperature corresponding to the intersection point of the extension lines of the straight line part of the temperature area. Transition temperature T_gThe measurement was carried out according to the method specified in GB/T7962.16-2010.

Transition temperature (T) of the glasses according to the invention_g) Not higher than 510 deg.C, preferably not higher than 500 deg.C, and more preferably not higher than 495 deg.C.

4. Refractive index and Abbe number

The fluorophosphate glass has a refractive index nd of 1.52-1.60, preferably 1.53-1.58, more preferably 1.55-1.58, and an Abbe number vd of 68-75, preferably 69-74, more preferably 70-73.

The refractive index and Abbe number were measured according to the method specified in GB/T7962.1-2010.

5. Temperature coefficient of refractive index

The temperature coefficient of the refractive index of the glass is-4.0 multiplied by 10^-6Below centigrade, preferably-5.0X 10^-6Below per degree centigrade, more preferably-7.5X 10^-6Below degree centigrade.

And testing the temperature coefficient of the refractive index according to a method specified in GB/T7962.4-2010, and determining the temperature coefficient of the refractive index at-40-80 ℃.

6. Chemical stability (stability to Water action DW, stability to acid action DA)

The ability of the polished surface of the optical glass element to resist the action of various erosion media such as water, acid and the like during the manufacturing and use process is called the chemical stability of the optical glass, which mainly depends on the chemical components of the glass, and the stability Dw (powder method) of the optical glass of the invention to water action is not less than 2 grades, preferably not less than 1 grade; the acid resistance stability DA (powder method) is not less than grade 2, preferably not less than grade 1.

The stability to water action Dw and the stability to acid action DA were tested according to the test method of GB/T17129.

7. Stress optical coefficient

The stress optical coefficient of the glass of the invention is less than 0.6 multiplied by 10^-12a/Pa, preferably less than 0.5X 10^-12a/Pa, more preferably less than 0.4X 10^-12/Pa。

The stress optical coefficient test was performed as follows:

sample requirement

The sample is processed into a cylinder, the light-passing surfaces at two ends are polished, the side surface of the cylinder is finely ground, the size is phi 20mm multiplied by 15mm, the sample can also be processed into other specifications according to the condition of test equipment, the parallelism of the two light-passing surfaces is less than or equal to 1/100, the roundness is less than or equal to 5/100, and the side surface taper is less than or equal to 1/100.

Test method

The stress optical coefficient is tested by adopting a disc to compress a sample in a diameter-matching way, putting a cylindrical sample into a stress birefringence test light path in a way that a circular end face is vertical to the light path, applying acting forces P on two end points of a diameter D of the circular end face on the side face of the cylinder in an opposite direction, keeping the position of the sample unchanged, and testing the stress birefringence optical path difference delta at the position of the circle center. By the formula

Calculating the photoelastic coefficient, wherein D is the diameter of the light-passing surface of the cylindrical sample and can be measured by a micrometer; p is the load applied to the side of the cylindrical sample, and can be obtained by a pressure gauge; delta is the birefringence optical path difference when the optical path vertically passes through the sample light-transmitting surface, and can be measured by a stress meter. In order to improve the precision and reduce the error, a plurality of times of measuring methods for testing the corresponding birefringence optical path difference under different loads are generally adopted to draw a delta-P curve, then linear regression processing is carried out to obtain the slope of the straight line, and further the stress optical coefficient B is calculated.

In a second aspect of the present invention, a glass preform is provided. According to an embodiment of the present invention, the glass preform is made of the above-described fluorophosphate glass. Thus, the optical preform of the present invention has low dispersion and the like, and at the same time, has a low high temperature coefficient of refractive index and a low stress optical coefficient, and is useful in various optical elements and optical designs. In particular, optical elements such as lenses, prisms, and mirrors are preferably produced from the fluorophosphate glass of the present invention by means of precision press molding or the like. It should be noted that the features and advantages described above for fluorophosphate glasses apply equally to the glass preform and are not described in further detail here.

In a third aspect of the invention, an optical element is presented. According to an embodiment of the present invention, the optical element is made of the above fluorophosphate glass or the above glass preform. Thus, the optical element of the present invention has low dispersion characteristics, and has low refractive index high temperature coefficient and stress optical coefficient, and can provide various optical elements such as lenses and prisms having excellent performance. For example, the optical element of the present invention may be a spherical lens, an aspherical lens, various lenses such as a microlens, a diffraction grating, a lens with a diffraction grating, a lens array, a prism, or the like. In addition, an optical thin film such as an antireflection film, a total reflection film, a partial reflection film, or a film having spectroscopic characteristics may be provided on the optical element as necessary. It should be noted that the features and advantages described above for the fluorophosphate glass and the glass preform apply equally to the optical element and are not described in detail here.

In a fourth aspect of the invention, an optical instrument is presented. According to an embodiment of the present invention, the optical instrument has the optical element described above. Thus, the optical device can be applied to outdoor high-temperature environments by using the optical element having excellent performance. Specifically, the optical device of the present invention may be an optical device that transmits visible light in a camera, a projector, or the like. It should be noted that the features and advantages described above for the optical element apply equally to the optical instrument and are not described in detail here.

The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.

In order to obtain glasses having the compositions shown in tables 1 to 5, the melting and molding method for producing the optical glass of the present invention may employ techniques well known to those skilled in the art. For example: the preparation method comprises the steps of weighing and mixing glass raw materials (fluoride, carbonate, nitrate, metaphosphate, oxide and the like) according to the proportion of glass ions, putting the mixture into a smelting device (such as a platinum crucible), then carrying out proper stirring, clarification and homogenization at 800-1250 ℃, cooling to below 900 ℃, pouring or leaking into a forming die, and finally carrying out post-treatment such as annealing and processing or directly carrying out compression forming by a precise compression technology. The characteristics of each glass were measured by the methods described above, and the measurement results are shown in tables 1 to 5.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Note: the total of 100% in the above table is data with measurement errors, equipment accuracy and inevitable impurities subtracted.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A fluorophosphate glass, characterized by comprising: a cation and an anion, and a salt thereof,

the cations include:

25 to 40 mol% of P⁵⁺；

8 to 22 mol% of Al³⁺；

1 to 30 mol% Ln³⁺，Ln³⁺Is La³⁺、Gd³⁺、Y³⁺And Yb³⁺At least one of (a);

25 to 55 mol% of R²⁺，R²⁺Is Ba²⁺、Ca²⁺、Sr²⁺And Mg²⁺At least one of (a);

Ca²⁺and Mg²⁺Is 0;

the anion comprises:

38 to 50 mol% of F^-；

50 to 62 mol% of O^2-

Wherein n is_Ln ³⁺/n_R ²⁺0.14 to 0.209, n_（Y ³⁺+_La ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Y ³⁺ _）0.120 to 0.5.

2. The fluorophosphate glass according to claim 1, wherein the cations comprise:

30 to 37 mol% of P⁵⁺(ii) a And/or

10 to 20 mol% of Al³⁺(ii) a And/or

2 to 20 mol% Ln³⁺(ii) a And/or

30 to 50 mol% of R²⁺。

3. The fluorophosphate glass according to claim 2, characterized in that the cations comprise:

31 to 36 mol% of P⁵⁺(ii) a And/or

12 to 17 mol% of Al³⁺(ii) a And/or

3 to 15 mol% Ln³⁺(ii) a And/or

35-45 mol% of R²⁺。

4. The fluorophosphate glass of any of claims 1-3, wherein the Ln is selected from the group consisting of³⁺The method comprises the following steps:

0 to 8 mol% of La³⁺(ii) a And/or

1 to 10 mol% of Gd³⁺(ii) a And/or

1 to 10 mol% of Y³⁺(ii) a And/or

0 to 10 mol% of Yb³⁺。

5. The fluorophosphate glass of claim 4, wherein Ln is defined as³⁺The method comprises the following steps:

0 to 5 mol% of La³⁺Is not limited toIncluding endpoint 0; and/or

1-6 mol% Gd³⁺(ii) a And/or

1 to 8 mol% of Y³⁺(ii) a And/or

0 to 5 mol% of Yb³⁺。

6. The fluorophosphate glass of claim 5, wherein Ln is defined as³⁺The method comprises the following steps:

0.5 to 4 mol% of La³⁺(ii) a And/or

1-5 mol% Gd³⁺(ii) a And/or

2 to 6 mol% of Y³⁺(ii) a And/or

0 to 5 mol% of Yb³⁺。

7. The fluorophosphate glass according to any one of claims 1 to 3, wherein R is²⁺The method comprises the following steps:

25 to 40 mol% of Ba²⁺(ii) a And/or

3 to 15 mol% of Sr²⁺。

8. The fluorophosphate glass according to claim 7, wherein R is²⁺The method comprises the following steps:

28 to 38 mol% of Ba²⁺(ii) a And/or

5 to 12 mol% of Sr²⁺。

9. The fluorophosphate glass according to claim 8, wherein R is²⁺The method comprises the following steps:

30 to 35 mol% of Ba²⁺(ii) a And/or

5 to 10 mol% of Sr²⁺。

10. The fluorophosphate glass according to any of claims 1 to 3, characterized in that the anions comprise:

41 to 48 mol% of F^-(ii) a And/or

52 to 59 mol% of O^2-。

11. The fluorophosphate glass according to claim 10, wherein the anions comprise:

42 to 46 mol% of F^-(ii) a And/or

54 to 58 mol% of O^2-。

12. The fluorophosphate glass of any of claims 1-3, wherein the Ln is selected from the group consisting of³⁺Is Y³⁺And/or La³⁺Said R is²⁺Is Sr²⁺And/or Ba²⁺。

13. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（Sr ²⁺+_Y ³⁺ _）/n_（Al ³⁺ _+Ba ²⁺ _）0.25 to 0.43, not including 0.25.

14. The fluorophosphate glass according to claim 13, wherein n is_（Sr ²⁺+_Y ³⁺ _）/n_（Al ³⁺ _+Ba ²⁺ _）0.265-0.375, excluding 0.265 as the end point.

15. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（Gd ³⁺+_La ³⁺ _）/n_（Y ³⁺ _+Ba ²⁺ _）Greater than 0.085.

16. The fluorophosphate glass according to claim 15, wherein n is_（Gd ³⁺+_La ³⁺ _）/n_（Y ³⁺ _+Ba ²⁺ _）Greater than 0.11.

17. The fluorophosphate glass according to claim 16, characterized in thatIn that n is_（Gd ³⁺+_La ³⁺ _）/n_（Y ³⁺ _+Ba ²⁺ _）Is 0.115 to 0.165.

18. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（sr ²⁺+_Ba ²⁺ _）/n_（Y ³⁺ _+Gd ³⁺ _+La ³⁺ _）=3.45~9。

19. The fluorophosphate glass according to claim 18, wherein n is_（sr ²⁺+_Ba ²⁺ _）/n_（Y ³⁺ _+Gd ³⁺ _+La ³⁺ _）= 3.45~7.6。

20. The fluorophosphate glass according to claim 19, wherein n is_（sr ²⁺+_Ba ²⁺ _）/n_（Y ³⁺ _+Gd ³⁺ _+La ³⁺ _）= 3.55~5.55。

21. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（Y ³⁺+_Gd ³⁺+_La ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _）Greater than 0.08.

22. The fluorophosphate glass according to claim 21, wherein n is_（Y ³⁺+_Gd ³⁺+_La ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _）Is 0.105 to 0.26.

23. According to claim22 the fluorophosphate glass according to claim 22, wherein n is_（Y ³⁺+_Gd ³⁺+_La ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _）Bits 0.105 to 0.195.

24. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（Y ³⁺+_Gd ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Ba ²⁺ _）Less than 0.12.

25. The fluorophosphate glass according to claim 24, wherein n is_（Y ³⁺+_Gd ³⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺ _+Ba ²⁺ _）0.075-0.115.

26. The fluorophosphate glass according to any of claims 1 to 3, characterized in that n is_（Y ³⁺+_Gd ³⁺+_Ba ²⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺+_Ba ²⁺ _）=0.435~0.505。

27. The fluorophosphate glass according to claim 26, wherein n is_（Y ³⁺+_Gd ³⁺+_Ba ²⁺ _）/n_（P ⁵⁺ _+Al ³⁺ _+Sr ²⁺+_Ba ²⁺ _）= 0.44~0.5。

28. The fluorophosphate glass according to any one of claims 1-3, characterized in that the cations further comprise:

0~15 mol% Li⁺(ii) a And/or

0 to 15 mol% of Na⁺(ii) a And/or

0 to 10 mol% of K⁺(ii) a And/or

0 to 8 mol% of B³⁺(ii) a And/or

0 to 10 mol% of Zn²⁺(ii) a And/or

0 to 8 mol% of In³⁺(ii) a And/or

0 to 5 mol% of Nb⁵⁺(ii) a And/or

0 to 5 mol% of Ti⁴⁺(ii) a And/or

0 to 5 mol% of Zr⁴⁺(ii) a And/or

0 to 5 mol% of Ta⁵⁺(ii) a And/or

0 to 5 mol% Ge⁴⁺。

29. The fluorophosphate glass of claim 28, wherein the cations further comprise:

0 to 10 mol% of Li⁺(ii) a And/or

0 to 10 mol% of Na⁺(ii) a And/or

0 to 5 mol% of K⁺(ii) a And/or

0 to 5 mol% of B³⁺(ii) a And/or

0 to 5 mol% of Zn²⁺(ii) a And/or

0 to 5 mol% of In³⁺(ii) a And/or

0 to 3 mol% of Nb⁵⁺(ii) a And/or

0 to 3 mol% of Ti⁴⁺(ii) a And/or

0 to 3 mol% of Zr⁴⁺(ii) a And/or

0 to 3 mol% of Ta⁵⁺(ii) a And/or

0 to 3 mol% Ge⁴⁺。

30. A fluorophosphate glass according to any one of claims 1 to 3, characterized in that the fluorophosphate glass has a refractive index of 1.52 to 1.60 and an Abbe number of 68 to 75.

31. The fluorophosphate glass according to claim 30, wherein the fluorophosphate glass has a refractive index of 1.53 to 1.58 and an abbe number of 69 to 74.

32. The fluorophosphate glass according to claim 31, wherein the fluorophosphate glass has a refractive index of 1.55 to 1.58 and an abbe number of 70 to 73.

33. The fluorophosphate glass according to any one of claims 1 to 3, wherein the fluorophosphate glass has a temperature coefficient of refractive index of-4.0 x 10^-6below/deg.C, the stability of acid resistance is not lower than 2 grade, the stability of water resistance is not lower than 2 grade, the transition temperature is not higher than 510 deg.C, and lambda₈₀No more than 370nm, lambda₅No more than 310nm, and density no more than 4.7g/cm³Stress optical coefficient not higher than 0.6 x 10^-12and/Pa, the abrasion degree is not higher than 500.

34. The fluorophosphate glass of claim 33, wherein the fluorophosphate glass has a temperature coefficient of refractive index of-5.0 x 10^-6below/deg.C, acid-resistant stability is not lower than 1 grade, water-resistant stability is not lower than 1 grade, transition temperature is not higher than 500 deg.C, and lambda₈₀No more than 360nm, lambda₅No more than 300nm, and density no more than 4.6g/cm³Stress optical coefficient not higher than 0.5X 10^-12and/Pa, the abrasion degree is not higher than 450.

35. The fluorophosphate glass of claim 34, wherein the fluorophosphate glass has a temperature coefficient of refractive index of-7.5 x 10^-6Below/centigrade, transition temperature not higher than 495 centigrade, lambda₈₀No more than 350nm, lambda₅No more than 295nm, and density no more than 4.5g/cm³Stress optical coefficient not higher than 0.4 x 10^-12/Pa。

36. A glass preform made from the fluorophosphate glass according to any one of claims 1 to 35.

37. An optical element, wherein the optical element is made from the fluorophosphate glass according to any one of claims 1 to 35 or the glass preform according to claim 36.

38. An optical instrument having the optical element of claim 37.