JP7645366B2 - Optical glass, optical elements and optical instruments - Google Patents

Description

The present invention relates to optical glass, and in particular to optical glass with a refractive index of 1.70 to 1.77 and an Abbe number of 28 to 36.

In recent years, with the development of micro (compact) high-definition optical systems, there is a strong demand for optical glass materials with a refractive index of 1.70 to 1.77, an Abbe number in the range of 28 to 36, relatively low P _g,F values and ΔP _g,F values, relatively low density, and relatively high light transmittance. In the prior art, optical glasses with a refractive index within the above range mainly include lanthanum flint glass (LaF) and heavy flint glass (ZF).

Lanthanum flint glass has a relatively low P _g,F value and ΔP _g,F value, and can be used for secondary color difference correction, but the density of lanthanum flint glass is generally 4.0g/cm ³ or more, and the acid resistance stability (D _A ) is usually less than class 3 or less than class 4. Lenses, prisms, etc. used in micro-optical systems are limited by the power and range of the driving motor, and if the density exceeds 4.0g/cm ³ , it will have a devastating effect on the overall design. In addition, unlike the processing of conventional optical components, lenses and prisms used in micro-optical systems are in a strong acid and strong alkali environment during the processing process, and if the optical material does not have good acid resistance, the yield rate of optical elements will be greatly reduced and it may not be possible to obtain a qualified product.

Traditional heavy flint glass within the above range of refractive index and Abbe number has low density, but has good chemical stability, and can meet the processing needs in strong acid environment. However, traditional heavy flint glass has a relatively large P _g,F value, which cannot meet the requirements of micro-optical systems to eliminate secondary color difference while reducing lens assembly. Meanwhile, heavy flint glass generally has poor light transmittance, and cannot meet the high demand for light transmittance of micro-optical systems.

The technical problem to be solved by the present invention is to provide an optical glass having a relatively low P _g,F value and ΔP _g,F value, excellent chemical stability, high light transmittance, and a relatively low density.

The technical solutions adopted in the present invention to solve the technical problems are as follows.
(1) Optical glass containing the following components by weight: _SiO2 : 25-50%, _ZrO2 : 2-14%, _Rn2O : 5-25%, _Nb2O5 : 25-50%, ( _Nb2O5 + _Rn2O )/ _{SiO2 is} 0.8-1.8, and _Rn2O is one or more of _Li2O , _Na2O , _{and K2O} .

(2) The optical glass according to (1), further comprising the following components by weight: B ₂ O ₃ : 0-5%, and/or ZnO: 0-5%, and/or P ₂ O ₅ : 0-3%, and/or Al ₂ O ₃ : 0-5%, and/or MgO: 0-5%, and/or CaO: 0-8%, and/or SrO: 0-8%, and/or BaO: 0-8%, and/or La ₂ O ₃ : 0-5%, and/or Gd ₂ O ₃ : 0-5%, and/or Y ₂ O ₃ : 0-5%, and/or WO ₃ : 0-5%, and/or Bi ₂ O ₃ : 0-5%, and/or TiO ₂ : 0-5%, and/or a fining agent: 0-2%, wherein the fining agent is Sb ₂ O ₃ , SnO ₂ , SnO, _CeO2 , NaCl, and sulfates.

(3) An optical glass containing SiO ₂ , Rn ₂ O and Nb ₂ O ₅ as necessary components by weight: (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ is 0.8 to 1.8, the refractive index nd of the optical glass is 1.70 to 1.77, the Abbe number ν _d is 28 to 36, the P _g,F value of the optical glass is 0.5950 or less, the ΔP _g,F value is 0.0015 or less, and Rn ₂ O is one or more of Li ₂ O, Na ₂ O and K ₂ O.

(4) The optical glass according to (3), comprising, in weight percent, 25-50% _SiO2 , and/or 2-14% ZrO2, and/or _5-25 % _Rn2O , and/or 25-50% _Nb2O5 , and/or 0-5% _B2O3 , and _{/or 0-5% ZnO, and/or 0-5% P2O5 , and} /or 0-3% _Al2O3 , and/or _0-5 % _MgO , and/or 0-8% CaO, and/or 0-8% SrO, and/or 0-8 _{% BaO} , and/or 0-5% _La2O3 , and/or 0-5% _Gd2O3 , and/or 0-5% _Y2O3 , and/or _{WO3 .} : 0-5%, and/or Bi ₂ O ₃ : 0-5%, and/or TiO ₂ : 0-5%, and/or fining agent: 0-2%, Rn ₂ O is one or more of Li ₂ O, Na ₂ O, K ₂ O, and the fining agent is one or more of Sb ₂ O ₃ , SnO ₂ , SnO, CeO ₂ , NaCl, and sulfates.

(5) An optical glass consisting of the following components by weight: SiO ₂ : 25-50%, ZrO ₂ : 2-14%, Rn ₂ O: 5-25%, Nb ₂ O ₅ : 25-50%, B ₂ O ₃ : 0-5%, ZnO: 0-5%, P ₂ O ₅ : 0-3%, Al ₂ O ₃ : 0-5%, MgO: 0-5%, CaO: 0-8%, SrO: 0-8%, BaO: 0-8%, La ₂ O ₃ : 0-5%, Gd ₂ O ₃ : 0-5%, Y ₂ O ₃ : 0-5%, WO ₃ : 0-5%, Bi ₂ O ₃ : 0-5%, TiO ₂ : 0-5%, fining agent: 0-2%, (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ is 0.8-1.8, Rn ₂ O is one or more of Li ₂ O, Na ₂ O, and K ₂ O, and the fining agent is one or more of Sb ₂ O ₃ , SnO ₂ , SnO, CeO ₂ , NaCl, and sulfate.

(6) An optical glass according to any one of (1) to (5), comprising the following components in weight percent and satisfying one or more of the following six conditions:
1) (Nb ₂ O ₅ + Rn ₂ O)/SiO ₂ is 0.9-1.6;
2) _Rn2O / _SiO2 is 0.2-0.6;
3) Li ₂ O/(Na ₂ O+K ₂ O) is 0.1 to 0.6;
4) _K2O / _Na2O is 0.1-0.7;
5) ZnO/ _ZrO2 is 0.01-1.5;
6) ZnO/RO is 10.0 or less.
Rn ₂ O is one or more of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO.

(7) An optical glass according to any one of (1) to (5), comprising the following components by weight: _SiO2 : 28-47%, and/or _ZrO2 : 3-12%, and/or _Rn2O : 6-23%, and/or _Nb2O5 : _{28-45%, and/or B2O3 : 0-3} %, and/or ZnO: 0-4%, and/or _P2O5 : 0-1%, and/or _Al2O3 : 0-3%, and/or _MgO : 0-3%, and/or _CaO : 0-6%, and/or SrO: 0-5%, and/or _BaO : 0-6%, and/or _{La2O3 :} 0-3%, and/or _Gd2O3 : 0-3%, and/or _Y2O3 : 0-3%, and/or _{WO 3} : 0-3%, and/or Bi ₂ O ₃ : 0-3%, and/or TiO ₂ : 0-3%, and/or fining agent: 0-1%, Rn ₂ O is one or more of Li ₂ O, Na ₂ O, K ₂ O, and the fining agent is one or more of Sb ₂ O ₃ , SnO ₂ , SnO, CeO ₂ , NaCl, and sulfates.

(8) An optical glass according to any one of (1) to (5), comprising the following components in weight percent and satisfying one or more of the following six conditions:
1) (Nb ₂ O ₅ + Rn ₂ O)/SiO ₂ is 1.0-1.5;
2) _Rn2O / _SiO2 is 0.23-0.55;
3) Li ₂ O/(Na ₂ O+K ₂ O) is 0.2 to 0.5;
4) K ₂ O/Na ₂ O is 0.15 to 0.6;
5) ZnO/ _ZrO2 is 0.05-1.0;
6) ZnO/RO is 5.0 or less.
Rn ₂ O is one or more of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO.

(9) An optical glass according to any one of (1) to (5), comprising the following components in weight percent: _SiO2 : 30-45%, and/or ZrO2: 5-10%, and/or _Rn2O : 8-20%, and/or _Nb2O5 : _32-40 %, and/or _ZnO : 0-3%, and/or CaO: 0-5%, and/or SrO: 0-4%, and/or BaO: 0-5%, and/or _La2O3 : 0-2%, and/or _{Gd2O3 :} 0-2%, and/or _Y2O3 : 0-2%, and/or _a fining agent: 0-0.5%, in which _Rn2O is one or more _{of Li2O} , _Na2O , and _K2O , and the fining agent is _Sb2O3 , _SnO2 , _{or ...} , SnO, _CeO2 , NaCl, and sulfates.

(10) An optical glass according to any one of (1) to (5), comprising the following components in weight percent and satisfying one or more of the following five conditions:
1) _Rn2O / _SiO2 is 0.25-0.5;
2) Li ₂ O/(Na ₂ O+K ₂ O) is 0.25 to 0.45;
3) _K2O / _Na2O is 0.2-0.5;
4) ZnO/ _ZrO2 is 0.1-0.5;
5) ZnO/RO is 3.0 or less, preferably ZnO/RO is 1.0 or less.
Rn ₂ O is one or more of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO.

(11) An optical glass according to any one of (1) to (5) containing, by weight, the following components: _Li2O : 1-10%, preferably _Li2O : 1.5-8%, more preferably _Li2O : 2-6%, and/or _Na2O : 2-20%, preferably _Na2O : 4-18%, more preferably _Na2O : 5-15%, and/or _K2O : 0-8%, preferably _K2O : 0-6%, more preferably _K2O : 0.5-5%.

(12) An optical glass according to any one of (1) to (5) containing the following components in weight percent: _SiO2 + _Nb2O5 + _ZrO2 + _Rn2O is 80% or more, preferably _SiO2 + _Nb2O5 + _ZrO2 + _Rn2O is 85% or _{more , more preferably SiO2 + Nb2O5 + ZrO2 + Rn2O is 88 %} or more, and even more preferably _SiO2 + _Nb2O5 + _ZrO2 + _{Rn2O is} 91% or more.

(13) An optical glass according to any one of (1) to (5), which does not contain B ₂ O ₃ , and/or does not contain P ₂ O ₅ , and/or does not contain Al ₂ O ₃ , and/or does not contain MgO, and/or does not contain TiO ₂ , and/or does not contain WO ₃ , and/or does not contain Bi ₂ O ₃ .

(14) The optical glass according to any one of (1) to (5), having a refractive index n _d of 1.70 to 1.77, preferably 1.705 to 1.765, more preferably 1.71 to 1.76, and even more preferably 1.72 to 1.75, and an Abbe number v _d of 28 to 36, preferably 29 to 35, more preferably 30 to 34, and even more preferably 31 to 33.5.

(15) The optical glass according to any one of (1) to (5), having a Pg _,F value of 0.5950 or less, preferably 0.5940 or less, more preferably 0.5930 or less, and/or a ΔPg _,F value of 0.0015 or less, preferably 0.0010 or less, more preferably 0 or less, and/or an acid resistance stability D _A of Class 2 or more, preferably Class 1, and/or a water resistance stability D _W of Class 2 or more, preferably Class 1, and/or a light transmittance τ _{400 nm} of 85.0% or more, preferably 88.0% or more, more preferably 90.0% or more, and/or a density ρ of 3.80 g/cm ³ or less, preferably 3.60 g/cm ³ or less, more preferably 3.40 g/cm ³ or less.

(16) An optical glass according to any one of (1) to (5), wherein the thermal expansion coefficient α _20/300°C of the optical glass is 100× ^{10 -7} /K or less, preferably 95×10 ^-7 /K or less, more preferably 93×10 -7 /K or less, and/or the weather resistance CR is Class 2 or higher, preferably _{Class 1} , and/or the bubble count is Class A or higher, preferably A0 or higher, and/or the stripes are Class D or higher, preferably Class C or higher, and/or the anti-crystallization property is Class B or higher, preferably Class A.

(17) A glass preform produced from the optical glass according to any one of (1) to (16).
(18) An optical element produced from the optical glass according to any one of (1) to (16) or the glass preform according to (17).
(19) An optical instrument comprising the optical glass according to any one of (1) to (16) and/or the optical element according to (18).

The beneficial effects of the present invention are as follows: The optical glass obtained by the present invention has a desired refractive index and Abbe number, and at the same time, has relatively low P _g,F and ΔP _g,F values, excellent chemical stability, high light transmittance, and relatively low density.

The following describes in detail the embodiments of the optical glass according to the present invention, but the present invention is not limited to the embodiments described below, and can be modified as appropriate within the scope of the object of the present invention. Furthermore, although some details are omitted, the gist of the present invention is not limited by the repetition of the description. Hereinafter, the optical glass of the present invention may be simply referred to as glass.

[Optical glass]
The range of the components of the optical glass of the present invention will be described below. In this description, the content and total content of each component will be expressed in weight percent (wt%) unless otherwise specified. That is, the content and total content of each component will be expressed as weight percent relative to the total weight of the glass material converted into an oxide composition. "Converted into an oxide composition" here refers to the case where the total weight of the oxide material when the oxide, complex salt, hydroxide, etc. used as the raw material of the optical glass composition of the present invention is decomposed and converted into an oxide during melting is taken as 100%.

Specifically, the numerical ranges described herein include upper and lower limits, and the terms "greater than or equal to" and "less than or equal to" include the endpoints, and all integers and fractions within the range, but are not limited to the specific values described when the range is limited. References to "and/or" herein are inclusive, e.g., "A and/or B" means A only, B only, or both A and B.

<Required and optional ingredients>
_SiO2 is a network forming component in the present invention. If its content exceeds 50%, the refractive index of the glass is lower than the design requirement, the Abbe number is higher than the design requirement, and the melting performance of the glass is poor. If its content is less than 25%, the broken network bonds inside the glass will increase rapidly, the chemical stability will decrease, and the anti-crystallization property will decrease rapidly. Therefore, the content of _SiO2 is limited to 25-50%, preferably 28-47%, more preferably 30-45%.

An appropriate amount _{of B2O3 can} increase the Abbe number of glass, lower the melting temperature of glass, and reduce the probability of insoluble matter generation in glass. However, in the glass system of the present invention, if the content of _B2O3 exceeds ₅ %, the free oxygen in the glass will be lost, and some oxides with changed valence will transition to low valence, resulting in a rapid deterioration of light transmittance. On the other hand, if the content of _B2O3 exceeds 5 _% , it will cause a rapid increase in the Pg _,F value of the _glass , making it impossible to meet the design requirements. Therefore, the content _{of B2O3} is limited to 5% or less, preferably 3% or less, and more preferably does not contain _B2O3 .

Although the Abbe number of glass can be adjusted by using _P2O5 in the glass, if the content _{of P2O5} exceeds 3% in the present glass, a large amount of crystal _nuclei are formed in the glass, and _the crystallization resistance of the glass is rapidly deteriorated. Therefore, the content of _P2O5 is limited to 3% or less, preferably 1% or less, and more preferably, the _glass does not contain _P2O5 .

Although the use of _Al2O3 in glass can improve the chemical stability of the glass, if the content exceeds 5%, the crystallization resistance of the glass rapidly deteriorates and a large amount of stones are generated inside the glass. Therefore, the content _{of Al2O3} is 5% or less, preferably 3% or less. In some embodiments, since _Al2O3 has _the effect _of increasing the Pg _,F value, it is more preferable that _{Al2O3 is} not included.

_Nb2O5 is _a high refractive index, high dispersion component, and one of the main components of the glass of the present invention. If its content is less than 25%, the Pg _,F value and ΔPg _,F value required for the glass of the present invention cannot be achieved, and if its content exceeds 50%, the refractive index of the glass exceeds the designed value, and the crystallinity resistance of the glass rapidly deteriorates. Therefore, the content _{of Nb2O5} is 25-50%, preferably 28-45%, and more preferably 32-40%.

Although _TiO2 can increase the chemical stability of glass and reduce the thermal expansion coefficient of glass, if its content _exceeds 5%, the light transmittance of glass _will rapidly deteriorate, especially when components such as _B2O3 and _Al2O3 are present in the glass. Therefore, its content is limited to 5% or less, preferably 3% or less. In some embodiments, _TiO2 can rapidly increase the ΔP _g,F value of glass, so it is more preferable not to include _TiO2 .

The use of _ZrO2 in glass can significantly improve the crystallinity of glass, but the above effect is not significant when the content of _ZrO2 is less than 2%, especially when the content of _Nb2O5 exceeds 25%. When the content _{of ZrO2 exceeds} 14%, the solubility of _ZrO2 decreases rapidly, forming minute insoluble matters inside the glass, which deteriorates the quality of the inside of the glass, and more seriously, these minute insoluble matters become crystallization carriers, which significantly reduces the crystallinity of the glass. Therefore, the content of _ZrO2 is 2-14%, preferably 3-12%, more preferably 5-10%.

The use of an appropriate amount of alkali metal oxide _Rn2O ( _Rn2O is _one or more of _Li2O , _Na2O , _K2O ) in glass can increase the solubility of _Nb2O5 , _ZrO2 and other substances that are difficult to melt, and make the refractive index, Abbe number, Pg _,F value and ΔPg _,F value easily meet the design requirements, but when the content of _Rn2O is less than 5%, the above effects are not significant. When the content of _Rn2O exceeds 25%, the broken bonds in the glass structure increase rapidly, and the anti-crystallization property of the glass also decreases rapidly. Therefore, the content of _Rn2O is 5-25%, preferably 6-23%, more preferably 8-20%.

In some embodiments, in order to achieve the desired excellent glass performance, in particular to obtain a relatively low density and a relatively high light transmittance, the total content of _SiO2 , _Nb2O5 , _ZrO2 and _{Rn2O , SiO2} + _Nb2O5 + _ZrO2 + _Rn2O , is preferably controlled to be 80% or more, more preferably _SiO2 + _Nb2O5 + _ZrO2 + _Rn2O to be 85% or more, even more preferably _SiO2 + _Nb2O5 + _ZrO2 + _Rn2O to be 88 _% or more _, and even more _{preferably SiO2} + _Nb2O5 + _ZrO2 + _{Rn2O to} be 91% _or more.

After extensive experimental research, the inventors have found that in some embodiments, by controlling the value of (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ within the range of 0.8-1.8, the P _g,F value and ΔP _g,F value of the glass can be easily reached in the desired range and the stability of the glass can be improved; therefore, preferably, (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ is 0.9-1.6, more preferably 1.0-1.5.

As a micro-optical instrument, its imaging operating surface is much smaller than other imaging instruments, so the requirements for the quality of the glass interior are much higher than other imaging instruments, and even a small amount of bubbles, inclusions, or stripes in the glass will have a significant impact on the imaging quality of the micro-imaging instrument. Research has shown that if the bubble degree of the optical glass used in the micro-imaging instrument does not reach grade _A0 or above and the stripe does not reach grade D or above, it cannot meet the optical grade imaging requirements of the micro-imaging instrument. The glass composition system used in the glass of the present invention has a relatively high viscosity in the optical glass system, which is unfavorable to the increase of the bubble degree and stripe. After a large amount of experimental research, the inventors have found that if the value of _Rn2O / _SiO2 is 0.2 or more, the high-temperature viscosity of the glass can be improved, a high bubble degree and stripe grade of the glass can be achieved, and the quality of the glass interior can be improved, but if the value of _Rn2O / _SiO2 exceeds 0.6, the thermal expansion coefficient of the glass will increase, causing fatal damage to the manufacture of micro-imaging instruments that need to be bonded under high-temperature conditions. Therefore, in the present invention, the value of Rn ₂ O/SiO ₂ is preferably 0.2 to 0.6, more preferably 0.23 to 0.55, and further preferably 0.25 to 0.5.

Among the three alkali metal oxides, Li ₂ O, Na ₂ O, and K ₂ O, Li ₂ O has the strongest ability to increase the solubility of raw materials, but because the electric field strength is relatively large, if its content exceeds 10%, it will promote the deterioration of the crystallinity resistance of the glass. If the Li ₂ O content is less than 1%, the Na ₂ O and K ₂ O contents must be increased to maintain the solubility of the difficult-to-melt materials, but this will cause the chemical stability of the glass to rapidly deteriorate. Therefore, the Li ₂ O content is 1-10%, preferably 1.5-8%, and more preferably 2-6%.

If the _Na2O content exceeds 20%, the chemical stability of the glass will not meet the design requirements, and if the Na2O content is less than 2%, the glass will be difficult to melt. Therefore, the _Na2O content is limited to 2-20%, preferably 4-18%, and more preferably 5-15%.

The use of K ₂ O in glass rapidly reduces the chemical stability of the glass, and potassium is most likely to precipitate, especially in strong acid and strong alkaline environments. Therefore, the content of K ₂ O is limited to 8% or less, preferably 6% or less. In some embodiments, the three alkali metal oxides Li ₂ O, Na ₂ O, and K ₂ O have a synergistic effect to optimize the performance of the glass, so the content of K ₂ O is more preferably 0.5-5%.

As a result of extensive experimental research, the inventors have found that _Li2O , _Na2O and _K2O have a complex synergistic effect in glass, and the content ratio of these elements has an important effect on important indexes such as the crystallization resistance, light transmittance, chemical stability and thermal expansion coefficient of glass.

Li ₂ O has a strong ability to increase the solubility of difficult-to-melt substances and can reduce the thermal expansion coefficient of glass, but because of its large electric field strength, it tends to promote crystal precipitation in glass when added alone to glass. In some embodiments, when Na ₂ O and K ₂ O are present in glass, the ability of Li ₂ O to promote crystal precipitation is reduced, and the crystal resistance of glass is excellent and the thermal expansion coefficient of glass does not exceed the design requirement, especially when Li ₂ O/(Na ₂ O+K ₂ O) is 0.1-0.6, preferably 0.2-0.5, more preferably 0.25-0.45.

Na ₂ O and K ₂ O can increase the solubility of hard-to-melt materials, improve the stability of glass, and optimize the light transmittance of glass, but they also rapidly reduce the chemical stability of glass, especially when Na ₂ O or K ₂ O is contained alone. After extensive experimental research, the inventors have found that in some embodiments, when Na ₂ O and K ₂ O are both present in glass and the content of K ₂ O and Na ₂ O is within the range of K ₂ O/Na ₂ O of 0.1 to 0.7, the glass has high solubility and light transmittance, and is also excellent in chemical stability. Preferably, K ₂ O/Na ₂ O is 0.15 to 0.6, and more preferably, K ₂ O/Na ₂ O is 0.2 to 0.5.

ZnO can increase the refractive index and dispersion of glass, reduce the high-temperature viscosity of glass, and increase the bubble and stripe of glass. If its content exceeds 5%, the phase separation tendency of glass will increase, the stripe will be significantly reduced, and the P _g,F value and ΔP _g,F value of glass will not meet the design requirements. Therefore, the ZnO content is limited to 5% or less, preferably 4% or less, more preferably 3% or less.

As a result of extensive experimental research, the inventors have found that in some embodiments, a small amount of ZnO can significantly improve the solubility of _ZrO2 in glass, and that the effect of improving the solubility of _ZrO2 in glass is most excellent when the ZnO/ _ZrO2 value is 0.01-1.5, preferably 0.05-1.0, and more preferably 0.1-0.5.

BaO can adjust the dispersion of glass, but if its content exceeds 8%, the chemical performance of the glass will be deteriorated and the ΔP _g,F value of the glass will not meet the design requirements. Therefore, the content of BaO is 8% or less, preferably 6% or less, and more preferably 5% or less.

Although CaO can adjust the dispersion of glass and has a better effect of increasing the Abbe number of glass than BaO, if the CaO content exceeds 8%, the crystallization resistance of the glass decreases and the ΔP _g,F value of the glass does not meet the design requirements. Therefore, the CaO content is limited to 8% or less, preferably 6% or less, and more preferably 5% or less.

Although SrO can increase the stability of glass, improve the crystallization resistance of glass, and increase the Abbe number of glass, if the content of SrO exceeds 8%, the Abbe number of glass is higher than the design requirement, and the ΔP _g,F value of glass does not meet the design requirement. Therefore, the content of SrO is limited to 8% or less, preferably 5% or less, and more preferably 4% or less.

Although MgO can increase the chemical stability of glass, if its content exceeds 5%, the crystallization resistance of the glass rapidly decreases. Therefore, the MgO content is limited to 5% or less, preferably 3% or less, and more preferably, no MgO is contained.

As a result of extensive experimental research, the inventors have found that in some embodiments, the ratio of the content of ZnO to the content of alkaline earth metal oxides RO (RO is the total content of BaO, SrO, CaO, and MgO) has a significant effect on the crystallinity resistance of optical glass. Specifically, when the value of ZnO/RO exceeds 10.0, the crystallinity resistance of the glass rapidly deteriorates. Therefore, the value of ZnO/RO is preferably 10.0 or less, more preferably 5.0 or less, even more preferably 3.0 or less, and even more preferably 1.0 or less.

_La2O3 can increase the refractive index of glass, reduce the high-temperature viscosity of glass, and improve the internal quality of glass, but if its content exceeds 5%, the crystallinity resistance of glass _will deteriorate, the Abbe number will increase rapidly, and the ΔP _g,F value _of glass will not meet the design requirements. Therefore, the content of _La2O3 is limited to 5% or less, preferably 3% or less, and more preferably 2% or less.

_Y2O3 can increase the refractive index and dispersibility of glass, strengthen the network cohesion of glass, _and improve the chemical stability of glass. When the content of _Y2O3 exceeds 5%, the glass _network will be excessively cohesed, the crystallization resistance of glass will rapidly decrease, and the density will rapidly increase. Therefore, the content _{of Y2O3} is limited to 5% or less, preferably 3% or less, and more preferably 2% or less.

_Gd2O3 can increase the refractive index and dispersion of glass and improve the stability of glass, but if _its content exceeds 5%, stones are likely to form inside the glass, and the internal quality will not meet the design requirements. Therefore, the content of _Gd2O3 is limited to 5% _or less, preferably 3% or less, and more preferably 2% or less.

_WO3 can improve the dispersion of glass, reduce the Abbe number of glass, and easily meet the design requirements of ΔP _g,F value, but when its content exceeds 5%, the crystallinity resistance and light transmittance of glass are rapidly reduced. Therefore, the content of _WO3 is limited to 5% or less, preferably 3% or less, and more preferably does not contain _WO3 .

_{Bi2O3 can} improve the dispersion of glass, reduce the Abbe number of glass, and make the ΔPg _{,F value} easily meet the design requirements, but when its content exceeds 5%, the light transmittance of glass rapidly decreases and the density rapidly increases. Therefore, the content of _Bi2O3 is limited to 5% or less, preferably 3% or less. In some embodiments, the glass of the present invention needs to be produced in a platinum container, but _Bi2O3 has a strong corrosive effect on the _platinum container, so _it is more preferable not to contain _Bi2O3 .

The glass of the present invention may contain a small amount of fining agents, such as _Sb2O3 , _SnO2 , _SnO , _CeO2 , NaCl, sulfates, etc., to improve the bubble content of the glass, and the content of the fining _agents is limited to 0-2%, preferably 0-1%, more preferably 0-0.5%. In consideration of the existing production technology, it is preferable to use _Sb2O3 as the fining agent.

<Ingredients that should not be included>
In the glass of the present invention, even when oxides of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo are contained alone or in combination in small amounts, the glass is colored and specific wavelengths in the visible light region are absorbed, weakening the visible light transmitting effect of the present invention. Therefore, it is preferable that optical glasses which require wavelength transmittance in the visible light region in particular not actually contain such oxides.

In recent years, there has been a trend to restrict the use of oxides of Th, Cd, Tl, Os, Be, and Se as harmful chemicals, and environmental protection efforts are required not only in the glass manufacturing process, but also in the processing process and disposal of the finished product. Therefore, when the impact on the environment is important, it is preferable not to contain them except for unavoidable contamination. This means that the optical glass does not actually contain substances that pollute the environment. Therefore, the optical glass of the present invention can be manufactured, processed, and disposed of without taking special environmental measures.

_In order to be environmentally friendly, the optical glass of the present invention does not contain _As2O3 and PbO. _As2O3 has the effect of removing bubbles _and preventing coloring of glass, but the addition of _As2O3 increases the platinum erosion in the glass melting furnace, especially the platinum melting furnace, so that more platinum ions enter the glass, which adversely affects the service _life of the platinum melting furnace. PbO can significantly increase the high refractive index and high dispersion of glass, but both _PbO and _As2O3 are substances that cause environmental pollution.

The terms "free" and "0%" used in this specification mean that no compounds, molecules, ions, elements, etc. were intentionally added as raw materials for the optical glass of the present invention. However, impurities or components that were not intentionally added as raw materials and/or equipment for manufacturing the optical glass may be present in small or trace amounts in the final optical glass, and these are also covered by the patent of this invention.

The characteristics of the optical glass of the present invention will be described below.
<Refractive index and Abbe number>
The refractive index (n _d ) and Abbe number (ν _d ) of optical glass are tested according to the method specified in "GB/T 7962.1-2010".
In some embodiments, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is 1.77, preferably 1.765, more preferably 1.76, and even more preferably 1.75.
In some embodiments, the lower limit of the refractive index (n _d ) of the optical glass of the present invention is 1.70, preferably 1.705, more preferably 1.71, and even more preferably 1.72.
In some embodiments, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is 36, preferably 35, more preferably 34, and even more preferably 33.5.
In some embodiments, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is 28, preferably 29, more preferably 30, and even more preferably 31.

<P _g,F value and ΔP _g,F value>
The P _g,F value and ΔP _g,F value of optical glass are calculated by measuring the n _F , n _C , and n _g values of the glass according to the method specified in “GB/T 7962.1-2010” and using the following formula.
P _g,F = (n _g -n _F )/(n _F -n _C )
ΔP _g,F = P _g,F -0.6457 + 0.001703ν _d
In some embodiments, the optical glasses of the present invention have a P _g,F value of 0.5950 or less, preferably 0.5940 or less, and more preferably 0.5930 or less.
In some embodiments, the optical glass of the present invention has a ΔP _g,F value of 0.0015 or less, preferably 0.0010 or less, more preferably 0.0005 or less, and even more preferably 0 or less.

<Thermal expansion coefficient>
The thermal expansion coefficient (α _20/300℃ ) of optical glass is measured from 20℃ to 300℃ according to the method specified in GB/T 7962.16-2010.
In some embodiments, the optical glass of the present invention has a coefficient of thermal expansion (α _{20/300° C.} ) of 100×10 ⁻⁷ /K or less, preferably 95×10 ⁻⁷ /K or less, and more preferably 93×10 ⁻⁷ /K or less.

<Water resistance stability>
The water resistance (D _W ) of optical glass (powder method) is tested according to the method specified in GB/T 17129.
In some embodiments, the water resistance stability (D _W ) of the optical glass of the present invention is Class 2 or higher, and preferably Class 1.

<Acid resistance>
The acid resistance stability (D _A ) (powder method) of optical glass is tested according to the method specified in "GB/T 17129".
In some embodiments, the acid resistance stability (D _A ) of the optical glass of the present invention is Class 2 or higher, and preferably Class 1.

<Density>
The density (ρ) of optical glass is tested according to the method specified in GB/T7962.20-2010.
In some embodiments, the density (ρ) of the optical glasses of the present invention is 3.80 g/cm ³ or less, preferably 3.60 g/cm ³ or less, and more preferably 3.40 g/cm ³ or less.

<Crystallization resistance>
The crystallinity of the glasses of the present invention is tested according to the following method.
The sample is cut into a size of 20×20×10 mm, polished on both sides, and then placed in a crystallization furnace at Tg+200°C for 30 minutes. After being taken out and cooled, the two large surfaces are polished again. The crystallinity of the glass is judged according to Table 1 below, with grade A being the best and grade E being the worst.

In some embodiments, the optical glass of the present invention has excellent crystallinity resistance, being Class B or higher, and preferably Class A.

＜Stripe＞
The stripes of the glass of the present invention are tested according to the method specified in "MLL-G-174B". Using a stripe meter consisting of a point light source and a lens, a standard sample is compared and confirmed from the direction where the stripes are most visible. There are four grades, A, B, C, and D. Grade A means that no visible stripes are visible under the specified detection conditions, grade B means that fine scattered stripes are visible under the specified detection conditions, grade C means that faint parallel stripes are visible under the specified detection conditions, and grade D means that coarse stripes are visible under the specified detection conditions.
In some embodiments, the stripes of optical glass are Class D or better, preferably Class C or better.

<Light transmittance>
The light transmittance (τ _400nm ) of optical glass is tested according to the method specified in "GB/T 7962.12-2010".
In some embodiments, the optical glass of the present invention has a light transmittance (τ _400nm ) of 85.0% or more, preferably 88.0% or more, and more preferably 90.0% or more.

<Bubble level>
The bubble content of optical glass is tested according to the method specified in "GB/T7962.8-2010".
In some embodiments, the cellular content of the optical glass of the present invention is Class A or higher, preferably Class _A0 or higher.

<Weather resistance>
The weatherability (CR) of optical glass is tested according to the following method.
The sample is placed in a test box with a saturated water vapor environment of 90% relative humidity, and alternately circulated at 40-50℃ every hour, 15 times. The weather resistance is classified according to the amount of change in turbidity before and after leaving the sample. Table 2 shows the weather resistance classification conditions.

In some embodiments, the weather resistance (CR) of the optical glass of the present invention is Class 2 or higher, preferably Class 1.

[Method of manufacturing optical glass]
The method for producing the optical glass of the present invention is as follows. The glass of the present invention is produced by conventional raw materials and processes using carbonates, nitrates, sulfates, phosphates, metaphosphates, hydroxides, oxides, etc. as raw materials, and after mixing by a conventional method, the prepared furnace material is charged into a melting furnace (platinum crucible, quartz crucible, etc.) at 1300 to 1350°C and melted. Then, it is clarified, stirred, and homogenized to obtain a homogeneous molten glass without bubbles or unmelted materials, and this molten glass is cast into a mold and annealed. Those skilled in the art can appropriately select the raw materials, manufacturing method, and process parameters according to actual needs.

[Glass preform and optical element]
A glass preform can be produced from the produced optical glass by using press molding means such as polishing, hot press molding, precision press molding, etc. That is, an optical preform can be produced from the optical glass by mechanical processing such as grinding and polishing, or a blank for press molding can be produced from the optical glass, and this blank can be hot press molded and then polished to produce an optical preform, or the blank produced by polishing can be precision press molded to produce an optical preform. It should be noted that the means for producing the optical preform are not limited to the above means.

As described above, the optical glass of the present invention is useful for various optical elements and optical designs. In particular, it is preferable to form a blank from the optical glass of the present invention and use this blank to carry out hot press molding, precision press molding, etc. to produce optical elements such as lenses and prisms. The glass of the present invention can also be used to manufacture glass preforms using the primary droplet molding method.

The optical preform and optical element of the present invention are both formed from the optical glass of the present invention. The optical preform of the present invention has the excellent properties of optical glass, and the optical element of the present invention has the excellent properties of optical glass, making it possible to provide optical elements such as various lenses and prisms with high optical value.
Examples of lenses include various lenses, such as a concave meniscus lens, a convex meniscus lens, a biconvex lens, a biconcave lens, a plano-convex lens, and a plano-concave lens, each of which has a spherical or aspheric lens surface.

[Optical equipment]
The optical glass or optical element formed by the optical glass of the present invention can be used in the manufacture of optical equipment such as photographic equipment, imaging equipment, display equipment and monitor equipment. The optical glass or optical element of the present invention is suitable for use in vehicle-mounted lighting equipment and optical equipment, and is applied to fields such as vehicle-mounted equipment. The optical glass or optical element of the present invention is suitable for use in optical equipment such as microprojection, microimaging (imaging/photography), and microillumination.

<Examples of optical glass>
In order to further clearly illustrate the technical solutions of the present invention, the following non-limiting examples are provided.
In the present examples, the optical glass was obtained using the above-mentioned method for producing optical glass, and has the composition shown in Tables 3 and 4. The properties of each glass were measured by the test methods described in the present invention, and the results are shown in Tables 3 and 4.

<Example of Glass Preform>
The glasses obtained in Examples 1 to 15 of the optical glass are subjected to polishing, hot press molding, precision press molding, or other press molding means to produce various lenses, such as concave meniscus lenses, convex meniscus lenses, biconvex lenses, biconcave lenses, plano-convex lenses, and plano-concave lenses, as well as preforms such as prisms.

<Examples of Optical Elements>
These preforms obtained in the above glass preform examples can be unannealed or annealed, provided that the stress is guaranteed, i.e. the refractive index can be fine-tuned while reducing the stress inside the glass, so that the optical properties such as the refractive index reach the desired values.
Next, each preform is ground and polished to produce various lenses and prisms, such as concave meniscus lenses, convex meniscus lenses, biconvex lenses, biconcave lenses, plano-convex lenses, and plano-concave lenses. An anti-reflective coating can also be applied to the surface of the obtained optical element.

<Example of optical device>
The optical elements manufactured according to the above optical element embodiments can be used in imaging devices, sensors, microscopes, medical technology, digital projection, communication, optical communication technology/information transmission, optics/illumination in the automotive field, photolithography technology, excimer lasers, wafers, computer chips and integrated circuits and electronic devices containing such circuits and chips, or imaging equipment and devices in the automotive field by forming optical parts or components using one or more optical elements according to optical design.

Claims (19)

An optical glass comprising the following components by weight and satisfying the following conditions:
_SiO2 : 25-50%, _ZrO2 : 2-14%, _Rn2O : 5-25%, and _Nb2O5 : _25-50 %.
The (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ (weight ratio) is 0.8 to 1.8, the Li ₂ O/(Na ₂ O+K ₂ O) (weight ratio) is 0.2 to 0.6, the ZnO/ZrO ₂ (weight ratio) is 0.01 to 1.5 , the K ₂ O/Na ₂ O (weight ratio) is 0.1 to 0.7, and the total content of SiO ₂ , Nb ₂ O ₅ , ZrO ₂ , and Rn ₂ O is 91% or more.
Here, _Rn2O is one or more selected from the group consisting of _Li2O , _Na2O , and _K2O . 2. The optical glass according to claim 1, further comprising one or more components selected from the following group by weight percent:
The group consisting of B ₂ O ₃ : 0-5%, ZnO: 0-5%, P ₂ O ₅ : 0-3%, Al ₂ O ₃ : 0-5%, MgO: 0-5%, CaO: 0-8%, SrO: 0-8%, BaO: 0-8%, La ₂ O ₃ : 0-5%, Gd ₂ O ₃ : 0-5%, Y ₂ O ₃ : 0-5%, WO ₃ : 0-5%, Bi ₂ O ₃ : 0-5%, TiO ₂ : 0-5%, and fining agents: 0-2%.
Here, the fining agent is one or more selected from the group consisting of Sb ₂ O ₃ , SnO ₂ , SnO, CeO ₂ , NaCl, and sulfates. An optical glass containing _SiO2 , _Rn2O , and _Nb2O5 as essential components and _satisfying the following conditions:
The optical _{glass has a refractive index n d of 1.70 to 1.77, an Abbe number ν d of 28 to 36 , a P g} ,F value of 0.5950 or less , and a ΔP _g , F value of _0.0015 or less. The optical glass has a refractive index n _d of 1.70 to 1.77 , an _Abbe number _{ν d of 28} to ₃₆ , a P g _,F value of 0.5950 or _less , and a _{ΔP g,F} value of 0.0015 or less.
Here, _Rn2O is one or more selected from the group consisting of _Li2O , _Na2O , and _K2O . 4. The optical glass according to claim 3, comprising one or more components selected from the following group by weight percent:
A group consisting of SiO ₂ : 25-50%, ZrO ₂ : 2-14%, Rn ₂ O: 5-25%, Nb ₂ O ₅ : 25-50%, B ₂ O ₃ : 0-5%, ZnO: 0-5%, P ₂ O ₅ : 0-3%, Al ₂ O ₃ : 0-5%, MgO: 0-5%, CaO: 0-8%, SrO: 0-8%, BaO: 0-8%, La ₂ O ₃ : 0-5%, Gd ₂ O ₃ : 0-5%, Y ₂ O ₃ : 0-5%, WO ₃ : 0-5%, Bi ₂ O ₃ : 0-5%, TiO ₂ : 0-5%, and fining agent: 0-2%. Here, _Rn2O is one or more selected from the group consisting of _Li2O , _Na2O , and _K2O , and the fining agent is one or more selected from the group consisting of _Sb2O3 , _SnO2 , _SnO , _CeO2 , NaCl, and sulfates. 5. The optical glass according to claim 1, which satisfies one or more of the following three conditions:
1) (Nb ₂ O ₅ +Rn ₂ O)/SiO ₂ (weight ratio) is 0.9-1.6;
2) Rn ₂ O/SiO ₂ (weight ratio) is 0.2-0.6;
3 ) ZnO /RO (weight ratio) is 10.0 or less.
Here, Rn ₂ O is one or more selected from the group consisting of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO. 5. The optical glass according to claim 1, comprising one or more components selected from the following group in weight percent:
A group consisting of SiO ₂ : 28-47%, ZrO ₂ : 3-12%, Rn ₂ O: 6-23%, Nb ₂ O ₅ : 28-45%, B ₂ O ₃ : 0-3%, ZnO: 0-4%, P ₂ O ₅ : 0-1%, Al ₂ O ₃ : 0-3%, MgO: 0-3%, CaO: 0-6%, SrO: 0-5%, BaO: 0-6%, La ₂ O ₃ : 0-3%, Gd ₂ O ₃ : 0-3%, Y ₂ O ₃ : 0-3%, WO ₃ : 0-3%, Bi ₂ O ₃ : 0-3%, TiO ₂ : 0-3%, and fining agent: 0-1%.
Here, _Rn2O is one or more selected from the group consisting of _Li2O , _Na2O , and _K2O , and the fining agent is one or more selected from the group consisting of _Sb2O3 , _SnO2 , _SnO , _CeO2 , NaCl, and sulfates. An optical glass according to any one of claims 1 to 4, which satisfies one or more of the following six conditions:
1) (Nb ₂ O ₅ + Rn ₂ O)/SiO ₂ (weight ratio) is 1.0 to 1.5;
2) Rn ₂ O/SiO ₂ (weight ratio) is 0.23-0.55;
3) Li ₂ O/(Na ₂ O+K ₂ O) (weight ratio) is 0.2-0.5;
4) K ₂ O/Na ₂ O (weight ratio) is 0.15 to 0.6;
5) ZnO/ZrO ₂ (weight ratio) is 0.05-1.0;
6) ZnO/RO (weight ratio) is 5.0 or less.
Here, Rn ₂ O is one or more selected from the group consisting of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO. 5. The optical glass according to claim 1, comprising one or more components selected from the following group in weight percent:
A group consisting of _SiO2 : 30-45%, ZrO2: 5-10%, _Rn2O : _8-20 %, _Nb2O5 : 32-40%, _ZnO : 0-3%, CaO: 0-5%, SrO: 0-4%, BaO: 0-5%, _La2O3 : 0-2% _{, Gd2O3} : 0-2%, _Y2O3 : 0-2%, and fining agent: 0-0.5%, where _Rn2O is one or more selected from the group consisting _{of Li2O} , _Na2O , and _K2O , _and the fining agent is one or more selected from the group consisting of _Sb2O3 , _SnO2 , _SnO , _CeO2 , NaCl, and sulfates. An optical glass according to any one of claims 1 to 4, which satisfies one or more of the following five conditions:
1) Rn ₂ O/SiO ₂ (weight ratio) is 0.25-0.5;
2) Li ₂ O/(Na ₂ O+K ₂ O) (weight ratio) is 0.25-0.45;
3) K ₂ O/Na ₂ O (weight ratio) is 0.2-0.5;
4) ZnO/ZrO ₂ (weight ratio) is 0.1-0.5;
5) ZnO/RO (weight ratio) is 3.0 or less.
Here, Rn ₂ O is one or more selected from the group consisting of Li ₂ O, Na ₂ O, and K ₂ O, and RO is the total content of BaO, SrO, CaO, and MgO. 5. The optical glass according to claim 1, comprising one or more components selected from the following group in weight percent:
The group consisting of Li ₂ O: 1-10%, Na ₂ O: 2-20%, and K ₂ O: 0-8%. 5. The optical glass according to claim 1, comprising one or more components selected from the following group in weight percent:
The group consisting of Li ₂ O: 2-6%, Na ₂ O: 5-15%, and K ₂ O: 0.5-5%. _5. The optical glass according to claim 1, which does not contain one or more components selected from the group consisting of _B2O3 , _P2O5 , _{Al2O3 ,} MgO, _TiO2 , _{WO3 ,} and _{Bi2O3 .} 5. The optical glass according to claim 1, wherein the optical glass has a refractive index n _d of 1.70 to 1.77 and an Abbe number v _d of 28 to 36. 5. The optical glass according to claim 1, wherein the optical glass has a refractive index n _d of 1.71 to 1.76 and an Abbe number v _d of 30 to 34. The optical glass according to any one of claims 1 to 4, which satisfies one or more of the following eleven conditions:
1) The Pg _,F value of the optical glass is 0.5950 or less.
2) The ΔP _g,F value is 0.0015 or less.
3) Acid resistance stability D _A is Class 2 or higher.
4) Water resistance stability _DW is Class 2 or higher.
5) The light transmittance τ at _{400 nm} is 85.0% or more.
6) Density ρ is 3.80 g/ ^cm3 or less.
7) The thermal expansion coefficient α _20/300°C is 100×10 ^-7 /K or less.
8) Weather resistance CR is Class 2 or higher.
9) The foaming level is A grade or higher.
10) The stripes are D grade or higher.
11) The crystallization resistance is class B or higher. The optical glass according to any one of claims 1 to 4, which satisfies one or more of the following eleven conditions:
1) The Pg _,F value of the optical glass is 0.5930 or less.
2) The ΔP _g,F value is 0 or less.
3) Acid resistance stability D _A is Class 1.
4) Water resistance stability _DW is Class 1.
5) The light transmittance τ at _{400 nm} is 90.0% or more.
6) Density ρ is 3.40 g/ ^cm3 or less.
7) The thermal expansion coefficient α _20/300°C is 93×10 ^-7 /K or less.
8) Weather resistance CR is Class 1.
9) The bubble level is _A0 or higher.
10) The stripes are C grade or higher.
11) The crystallization resistance is Class A. A glass preform made from the optical glass according to any one of claims 1 to 16 . An optical element manufactured from the optical glass according to any one of claims 1 to 16 or the glass preform according to claim 17 . An optical instrument comprising the optical glass according to any one of claims 1 to 16 and/or the optical element according to claim 18 .