CN110510869B

CN110510869B - Optical glass

Info

Publication number: CN110510869B
Application number: CN201810492260.3A
Authority: CN
Inventors: 匡波
Original assignee: Chengdu Guangming Optoelectronics Co Ltd
Current assignee: Chengdu Guangming Optoelectronics Co Ltd
Priority date: 2018-05-22
Filing date: 2018-05-22
Publication date: 2021-06-22
Anticipated expiration: 2038-05-22
Also published as: CN110510869A; WO2019223041A1

Abstract

The invention provides an optical glass which has high refractive index and lower Tg temperature and can be produced in large scale. Optical glass, the composition of which, expressed in weight percent, comprises: SiO 2₂：6‑16％；B₂O₃：5‑15％；La₂O₃：25‑35％；TiO₂：15‑30％；Nb₂O₅：5‑15％；ZrO₂: 1 to 15 percent; BaO: 8-20% of SiO₂＞B₂O₃；La₂O₃/(SiO₂+B₂O₃) Is 1.0-2.5. The optical glass has the refractive index of more than 1.95, the transition temperature of below 690 ℃, lower transition temperature and density, and excellent water resistance, acid resistance stability and hardness through reasonable component design.

Description

Optical glass

Technical Field

The present invention relates to an optical glass, and more particularly to an optical glass having a high refractive index of 1.95 or more, and a glass preform and an optical element made of the optical glass.

Background

In recent years, digitalization and high precision of devices using optical systems have been rapidly advanced, and in the field of optical devices such as image pickup devices such as digital cameras and video cameras, and image reproducing (projection) devices such as projectors and projection televisions, there has been an increasing demand for reducing the number of optical elements such as lenses and prisms used in optical systems, and for reducing the weight and size of the entire optical system. In the design of an optical system, miniaturization, ultra-thinning and wide-angle are realized by adopting high-refractive-index glass or utilizing an aspheric lens, and the optical system is widely applied to the fields of vehicles, security and the like. Meanwhile, in the design of a special optical system, high-refractive-index and high-Abbe-number glass can be matched with high-refractive-index and low-Abbe-number glass, so that the purpose of compensating and correcting chromatic aberration is achieved, the research and development requirements of the high-refractive-index glass are gradually increased, and meanwhile, the optical lens applied to vehicle-mounted and security protection is exposed outdoors for a long time, so that the requirements on water resistance, acid resistance and hardness of the optical glass are high.

The prior art discloses a plurality of optical glasses with good optical performance or low Tg temperature, for example, Chinese patent document with application number of 200310114721.7 discloses an optical glass mainly containing B₂O₃、SiO₂And La₂O₃Etc. of which B₂O₃In an amount greater than SiO₂The glass has a refractive index of 1.8-2.1 and an Abbe number of 20-40, has good optical performance, but has a high Tg temperature; chinese patent application No. 200680051694.5 discloses an optical glass having a glass transition temperature of 400 ℃ or lower and a low Tg temperature, but the optical glass has a refractive index of only 1.50 to 1.65, an abbe number of 50 to 65, and poor optical properties, and cannot satisfy the requirements of miniaturization, weight reduction, and high precision of an optical system; chinese patent application No. 201010120158.4 discloses a high refractive index optical glass,it contains 40-85 mol% of TeO₂The components and the production cost are high, and the large-scale production is not facilitated. While the prior art discloses a variety of optical glasses with good optical properties or low Tg temperatures, no optical glass is disclosed that has both good optical properties, a lower Tg temperature, and is less expensive.

Disclosure of Invention

The invention aims to provide optical glass which has high refractive index and lower Tg temperature and can be produced in large scale.

The present invention also provides a glass preform and an optical element formed of the above optical glass.

The technical scheme adopted by the invention for solving the technical problem is as follows: optical glass, the composition of which, expressed in weight percent, comprises: SiO 2₂：6-16％；B₂O₃：5-15％；La₂O₃：25-35％；TiO₂：15-30％；Nb₂O₅：5-15％；ZrO₂: 1 to 15 percent; BaO: 8-20% of SiO₂＞B₂O₃；La₂O₃/(SiO₂+B₂O₃) Is 1.0-2.5.

Further, the method also comprises the following steps: gd (Gd)₂O₃：0-10％；Y₂O₃：0-10％；Yb₂O₃：0-10％；WO₃：0-5％；ZnO：0-8％；MgO：0-5％；CaO：0-5％；SrO：0-5％；Ta₂O₅：0-5％；Al₂O₃：0-5％；Sb₂O₃：0-1％。

Optical glass, the composition of which is expressed in weight percent: SiO 2₂：6-16％；B₂O₃：5-15％；La₂O₃：25-35％；TiO₂：15-30％；Nb₂O₅：5-15％；ZrO₂：1-15％；BaO：8-20％；Gd₂O₃：0-10％；Y₂O₃：0-10％；Yb₂O₃：0-10％；WO₃：0-5％；ZnO：0-8％；MgO：0-5％；CaO：0-5％；SrO：0-5％；Ta₂O₅：0-5％；Al₂O₃：0-5％；Sb₂O₃: 0-1% of SiO₂＞B₂O₃；La₂O₃/(SiO₂+B₂O₃) Is 1.0-2.5.

Further, wherein: SiO 2₂: 6 to 12 percent; and/or B₂O₃: 5 to 10 percent; and/or La₂O₃: 27 to 32 percent; and/or TiO₂: 17 to 27 percent; and/or Nb₂O₅: 8 to 13 percent; and/or ZrO₂: 3 to 12 percent; and/or BaO: 10 to 18 percent; and/or Gd₂O₃: 0 to 5 percent; and/or Y₂O₃: 0 to 5 percent; and/or Yb₂O₃: 0 to 5 percent; and/or WO₃: 0 to 2 percent; and/or ZnO: 0 to 5 percent; and/or MgO: 0 to 2 percent; and/or CaO: 0 to 2 percent; and/or SrO: 0 to 2 percent; and/or Ta₂O₅: 0 to 2 percent; and/or Al₂O₃: 0 to 3 percent; and/or Sb₂O₃：0-0.5％。

Further, the content of each component satisfies one or more of the following 4 cases:

1)La₂O₃/(SiO₂+B₂O₃) 1.2-2.3;

2)TiO₂/(Nb₂O₅+ZrO₂+WO₃) 0.8-2.0:

3) (ZnO + MgO + CaO + SrO)/BaO is 0.1-0.8:

4)TiO₂the ratio of/BaO is 1.0-2.5.

1)La₂O₃/(SiO₂+B₂O₃) 1.3-2.0;

2)TiO₂/(Nb₂O₅+ZrO₂+WO₃) 0.9-1.5:

3) (ZnO + MgO + CaO + SrO)/BaO is 0.15-0.5:

4)TiO₂the ratio of/BaO is 1.3-2.3.

Furthermore, the composition is expressed by weight percentage,further comprising: p₂O₅：0-5％；Bi₂O₃：0-5％；Ga₂O₃:0-5％；Lu₂O₃:0-5％；GeO₂：0-5％；CeO₂：0-0.5％；SnO₂：0-0.5％；F：0-5％。

Further, the refractive index nd of the optical glass is 1.95 or more, and the Abbe number vd is 22 to 30.

Further, the density rho of the optical glass is 5.00g/cm³The following; hardness H_KIs 620 multiplied by 10⁷Pa is above; the transition temperature Tg is 690 ℃ or less.

Further, the optical glass powder method is resistant to water stability D_WIs of type 1; acid stability by powder Process D_AIs type 1.

The glass preform is made of the optical glass.

The optical element is made of the optical glass.

The invention has the beneficial effects that: through reasonable component design, the optical glass has the refractive index of more than 1.95, the transition temperature is below 690 ℃, the optical glass has lower transition temperature and density, and excellent water resistance, acid resistance stability and hardness, and the optical glass is high-refractive-index optical glass with low cost and excellent chemical stability, and can meet the requirements of modern novel photoelectric products.

Detailed Description

I, optical glass

The optical glass of the invention does not contain expensive TeO based on the consideration of reducing the production cost₂Component (c) to obtain a high refractive index optical glass having a refractive index of 1.95 or more and an Abbe number of 22 to 30. The composition of the optical glass of the present invention will be described in detail below, and the content and total content of each glass component are expressed by weight percent unless otherwise specified. In the following description, when a value equal to or less than a predetermined value or a value equal to or greater than the predetermined value is mentioned, the predetermined value is also included.

B₂O₃Is a component for forming glass network, and has the effects of improving glass meltability and devitrification resistance, and reducing glass stateThe effect of transition temperature and density, in order to achieve the above effect, the present invention introduces B of 5% or more₂O₃(ii) a However, when the amount of incorporation exceeds 15%, the glass stability is lowered and the refractive index is lowered, so that the high refractive index of the present invention cannot be obtained, and therefore, B of the present invention₂O₃The upper limit content of (B) is 15%, preferably 10%.

SiO₂Also a glass former, with B₂O₃The loose chain-like layered networks formed are different, SiO₂The three-dimensional network of silicon-oxygen tetrahedrons is formed in the glass, and is very compact and firm. Such networks are incorporated into glass for loose boroxine [ BO ]₃]The network is reinforced to be compact, so that the high-temperature viscosity of the glass is improved; meanwhile, the addition of a silicon-oxygen tetrahedral three-dimensional network, and the glass network isolates La₂O₃、Nb₂O₅The capability of the isodevitrifying cations and anions is enhanced, the devitrifying threshold is increased, the devitrifying resistance of the glass is improved, and SiO in the glass is₂The lower limit of the content is 6%; if SiO₂When the content of (b) is more than 16%, the glass transition temperature is increased and the glass meltability is lowered, so that the upper limit of the content is 16%, preferably 12%. After a great deal of research, the inventor finds that when SiO is used₂The content is less than B₂O₃At contents, the chemical stability and hardness of the glass tend to decrease, so that SiO in the glass of the invention₂The content is more than B₂O₃And (4) content.

La₂O₃Are essential components for obtaining the desired optical properties of the present invention. When La₂O₃When the content of (b) is less than 25%, it is difficult to realize desired optical characteristics; however, when the content exceeds 35%, both devitrification resistance and melting property of the glass deteriorate. Thus, the La of the present invention₂O₃The content of (B) is 25-35%, preferably in the range of 27-32%.

Gd₂O₃、Y₂O₃And Yb₂O₃And La₂O₃Coexisting with the lower upper limit temperature of crystallization and the liquid phase temperatureAnd improving the resistance to devitrification. However, if the content of each of these components exceeds 10%, the upper limit temperature of crystallization increases, and devitrification resistance deteriorates. Thus, Gd₂O₃、Y₂O₃And Yb₂O₃The content of (B) is 0 to 10%, respectively, and the preferable range is 0 to 5%, respectively.

The inventors have found that the present invention uses La in view of maintaining a high refractive index and improving devitrification resistance and glass stability₂O₃With SiO₂、B₂O₃Total weight (SiO)₂+B₂O₃) Ratio La of₂O₃/(SiO₂+B₂O₃) The range of (B) is defined to be 1.0 to 2.5, preferably 1.2 to 2.3, more preferably 1.3 to 2.0.

TiO₂The glass is a high-refraction high-dispersion oxide, and the refractive index and the dispersion of the glass can be improved by adding the oxide into the glass. At the same time, a suitable amount of TiO₂When the glass is added into glass, the glass can enter a glass network to become a part of the glass network, and the stability, particularly the devitrification resistance, of the glass is improved. If too much TiO₂When the glass is added, firstly, the refractive index and the dispersion of the glass are higher than the expected design, secondly, the transmittance of the glass is rapidly deteriorated, and simultaneously, the stability of the glass is not up to the expected design; if TiO, however₂Too little, the refractive index and dispersion of the glass may be lower than expected by design, while the devitrification resistance of the glass is reduced. Thus TiO in the glass according to the invention₂The content of (B) is 15 to 30%, preferably 17 to 27%.

In the glass of the present invention, when Nb₂O₅When the content exceeds 5%, it has an excellent effect of lowering liquidus temperature, and also has the effect of improving the refractive index, crystallization resistance and chemical durability of the glass without deteriorating transmittance, and a suitable amount of Nb₂O₅The anti-devitrification performance of the glass can be effectively improved in the precise mould pressing process; if the content exceeds 15%, the glass dispersion increases and the optical characteristics of the glass of the present invention cannot be achieved. Thus, Nb₂O₅The content of (B) is in the range of 5 to 15%, preferably in the range of 8 to 13%.

WO₃In glassThe main function is to maintain optical constants and improve glass devitrification, but when the content is too high, the glass transmittance is lowered, the degree of coloration is increased, and devitrification performance is deteriorated. Thus, WO₃Is preferably contained in an amount of 0 to 5%, more preferably 0 to 2%.

ZrO₂The oxide is a high-refraction low-dispersion oxide, and can improve the refractive index of the glass and adjust the dispersion when added into the glass. At the same time, ZrO in an amount of 1% or more₂When the glass is added, the devitrification resistance and the glass forming stability of the glass can be improved. If the content is more than 15% in the present invention, the glass becomes hard to melt, the melting temperature increases, and inclusions in the glass and the transmittance thereof tend to decrease. Therefore, the content thereof is set to 1 to 15%, preferably 3 to 12%.

To obtain a high refractive index, the optical glass may be doped with a large amount of TiO₂、Nb₂O₅And WO₃Equal components, but the components have serious influence on the visible light transmittance and the crystallization performance of the optical glass and can cause the Tg temperature and the density of the glass to rise, so that the inventor finds that when TiO is used for researching greatly₂/(Nb₂O₅+ZrO₂+WO₃) Within the range of 0.8-2.0, the above properties tend to be balanced, and particularly within the range of 0.9-1.5, the above properties are excellent.

ZnO has the effect of lowering the glass melting temperature or transition temperature. However, in the present invention, if the content exceeds 8%, the refractive index is lowered and the chemical durability of the glass is also lowered, so that the content of ZnO is in the range of 0 to 8%, preferably 0 to 5%.

BaO is a component for increasing the refractive index of glass and improving the transmittance of glass. When the content is too large, the devitrification resistance and chemical stability of the glass are deteriorated. Therefore, the content thereof is limited to 8 to 20%, preferably 10 to 18%. In the optical glass of the present invention, when TiO is used₂When the/BaO is in the range of 1.0 to 2.5, the glass is excellent in acid-and water-resistant stability, and preferably in the range of 1.3 to 2.3.

CaO helps to raise the refractive index of the glass, which can increase the glass range in place of a portion of BaO. However, if CaO is added in an excessive amount, the devitrification resistance of the glass is deteriorated. Therefore, the CaO content is limited to 0 to 5%, preferably 0 to 2%.

The addition of SrO to glass makes it possible to adjust the refractive index and Abbe number of the glass, but if the addition amount is too large, the stability and devitrification resistance of the glass are deteriorated, and the cost of the glass is rapidly increased. Therefore, the SrO content is limited to 0 to 5%, preferably 0 to 2%.

Although MgO contributes to the improvement of the chemical stability of glass, if the content thereof is too large, the refractive index of glass does not meet the design requirements, the devitrification resistance and chemical stability of glass decrease, and the cost of glass rapidly increases. Therefore, the MgO content is limited to 0 to 5%, preferably 0 to 2%.

The inventor researches and discovers that the alkaline earth metal oxide and ZnO have important influence on the hardness of the glass of the invention and can influence the glass forming stability and the anti-crystallization stability of the glass to a certain extent, and when the (ZnO + MgO + CaO + SrO)/BaO is 0.1-0.8, the hardness, the glass forming stability and the anti-crystallization stability of the glass are excellent, and the (ZnO + MgO + CaO + SrO)/BaO is preferably 0.15-0.5.

Ta₂O₅The refractive index, resistance to devitrification and viscosity of the molten glass can be improved, but it is expensive and disadvantageous in reducing the production cost, so that the content thereof is limited to 5% or less, preferably 2% or less.

Introducing small amount of Al₂O₃The Al composition of the present invention can improve the stability and chemical stability of the formed glass, but when the content exceeds 5%, the glass melting property is deteriorated and the devitrification resistance is lowered, so that the Al composition of the present invention₂O₃The content of (B) is 0 to 5%, preferably 0 to 3%.

P₂O₅Component (B) is an optional component for improving the devitrification resistance of the glass, in particular P₂O₅The content of (A) is 5% or less, and the reduction of the chemical durability, particularly the water resistance, of the glass can be suppressed. Thus, P₂O₅The content is limited to 5% or less, more preferably 3% or less, and further preferably not incorporated.

Bi₂O₃Is an optional component for increasing the refractive index of the glass and reducing the glass transition temperature when the content exceeds the contentSince the glass devitrification resistance is lowered at 5%, the content thereof is limited to 5% or less, preferably 1% or less, and more preferably not incorporated.

GeO₂The component having the effect of increasing the refractive index of the glass and increasing the devitrification resistance is an optional component of the optical glass of the present invention, but the cost is high, and the incorporation of too much is not intended to reduce the production cost of the present invention, so the content thereof is limited to 5% or less, preferably 2% or less, and further, it is not incorporated.

If less than 5% of Lu is introduced into the invention₂O₃The rare earth element is preferably contained in an amount of 5% or less, more preferably 3% or less, and further more preferably not incorporated, because it is expensive and incorporation into the glass is disadvantageous in terms of reduction of production cost.

As an optional component of the present invention, by controlling Ga₂O₃At 5% or less, since resistance to devitrification of the glass can be improved and the degree of abrasion of the glass can be increased, the content thereof is preferably 5% or less, more preferably 3% or less, and further preferably no incorporation.

By adding small amounts of Sb₂O₃、SnO₂、CeO₂The component can improve the fining effect of the glass, but when Sb is used₂O₃When the content exceeds 1%, the glass tends to have a reduced fining property and the deterioration of the forming mold is promoted by its strong oxidizing action, so Sb is preferable in the present invention₂O₃The amount of (B) is 0 to 1%, more preferably 0 to 0.5%. SnO₂However, when the content exceeds 1%, the glass is colored, or when the glass is heated, softened, press-molded or the like and then re-molded, Sn becomes a starting point of crystal nucleus formation, and thus, the glass tends to devitrify. Thus the SnO of the invention₂The content of (b) is preferably 0 to 1%, more preferably 0 to 0.5%, and further preferably not added. CeO (CeO)₂Action and addition amount ratio of (B) and SnO₂The content is preferably 0 to 1%, more preferably 0 to 0.5%, and further preferably no addition.

F is low dispersion,When the amount of the effective component is excessively increased, the refractive index of the glass is significantly decreased, the volatility of the glass melt is increased, and the glass melt tends to be textured during molding or to be volatilized to increase the variation in refractive index. YF can be used as F as a raw material₃、LaF₃、GdF₃、ZrF₄、ZnF₂And introducing alkaline earth metal fluoride. In the present invention, the content of F is preferably 0 to 5%, more preferably 0 to 3%, and further preferably not incorporated.

[ regarding components that should not be contained ]

If necessary, other components not mentioned above can be added within a range not impairing the characteristics of the glass of the present invention. However, since the glass is colored and absorbs at a specific wavelength in the visible light region even when a small amount of a transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo is contained alone or in combination, thereby reducing the property of the present invention to improve the effect of the visible light transmittance, it is preferable that the optical glass, which requires transmittance at a wavelength in the visible light region, is not substantially contained.

In recent years, cations of Pb, Th, Cd, Tl, Os, Be, and Se tend to Be used as harmful chemical substances in a controlled manner, and measures for protecting the environment are required not only in the glass production process but also in the processing process and disposal after commercialization. Therefore, when importance is attached to the influence on the environment, it is preferable that these components are not substantially contained except for inevitable mixing. Thereby, the optical glass becomes practically free from substances contaminating the environment. Therefore, the optical glass of the present invention can be manufactured, processed, and discarded without taking special measures for environmental countermeasures.

The properties of the optical glass of the present invention will be described below.

[ optical constants of optical glass ]

The refractive index (nd) and Abbe number (v) of the optical glass_d) The test was carried out according to the method specified in GB/T7962.1-2010.

The optical glass of the present invention has a refractive index (nd) in the range of 1.95 or more, preferablyPreferably in the range of 1.95 to 2.1, more preferably in the range of 1.98 to 2.05, still more preferably in the range of 1.99 to 2.02; abbe number (v) of the glass of the invention_d) Is in the range of 22 to 30, preferably in the range of 23 to 28, and more preferably in the range of 24 to 27.

[ transition temperature (Tg) of optical glass ]

The transition temperature (Tg) of the optical glass was measured by the method specified in GB/T7962.16-2010.

The glass according to the invention has a transition temperature (Tg) of 690 ℃ or less, preferably 685 ℃ or less.

[ Density of optical glass ]

The density of the optical glass was measured according to the method specified in GB/T7962.20-2010.

The density (. rho.) of the glass of the present invention is 5.00g/cm³Hereinafter, it is preferably 4.90g/cm³Hereinafter, more preferably 4.80g/cm³The following.

[ Water-resistant stability of optical glass (D)_W)]

Water stability by glass powder method (D)_W) Measured using the GB/T17129 test standard.

Optical glass (D) of the present invention_W) The number is 2 or more, preferably 1 or more.

[ acid resistance stability of optical glass (D)_A)]

Acid stability by glass powder method (D)_A) Measured using the GB/T17129 test standard.

Optical glass (D) of the present invention_A) The number is 2 or more, preferably 1 or more.

[ hardness (H) of optical glass_K)]

Hardness (H) of optical glass_K) Measured according to the method specified in GB/T7962.18-2010.

Hardness (H) of the optical glass of the present invention_K) Is 620 multiplied by 10⁷Pa or more, preferably 625X 10⁷Pa or above.

II, glass preform and optical element

Next, the glass preform and the optical element of the present invention are described.

The glass preform of the present invention and the optical element are each formed of the above-described optical glass of the present invention. The glass preform of the present invention has a high refractive index characteristic; the optical element of the present invention has high refractive index characteristics, and can provide various optical elements such as lenses and prisms having high optical values at low cost.

Examples of the lens include various lenses such as a concave meniscus lens, a convex meniscus lens, a double convex lens, a double concave lens, a plano-convex lens, and a plano-concave lens, each of which has a spherical or aspherical lens surface.

Further, since the prism has a high refractive index, by combining the prism with an imaging optical system and bending the optical path to direct the prism in a desired direction, a compact and wide-angle optical system can be realized.

Examples

The present invention is explained by the following examples, but the present invention should not be limited to these examples.

The melting and shaping methods for producing the optical glass may employ techniques well known to those skilled in the art. The preparation method comprises the steps of weighing and mixing glass raw materials (carbonate, nitrate, sulfate, hydroxide, oxide, boric acid and the like) according to the proportion of glass oxide, putting the glass raw materials into a smelting device (such as a platinum crucible), then carrying out appropriate stirring, clarification and homogenization at 1150-1400 ℃, cooling to below 1200 ℃, 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.

[ optical glass examples ]

The characteristics of each glass of the present invention were measured by the methods described above, and the measurement results are shown in tables 1 to 2, where K1 represents La₂O₃/(SiO₂+B₂O₃) K2 represents TiO₂/(Nb₂O₅+ZrO₂+WO₃) K3 represents (ZnO + MgO + CaO + SrO)/BaO, and K4 represents TiO₂/BaO。

TABLE 1

TABLE 2

[ glass preform examples ]

The optical glasses obtained in examples 1 to 10 in table 1 were cut into a predetermined size, and then a release agent was uniformly applied to the surface of the optical glass, followed by heating, softening, and press-molding to prepare preforms of various lenses and prisms 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.

[ optical element examples ]

The preforms obtained in the above examples of glass preforms were annealed to reduce the deformation in the glass and to fine-tune the optical properties such as refractive index to desired values.

Next, each preform is ground and polished to produce 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, and prisms. The surface of the optical element may be coated with an antireflection film.

The invention is high-refractive index optical glass with low cost and excellent chemical stability, the refractive index is more than 1.95, the Abbe number is 22-30, and an optical element formed by the glass can meet the requirements of modern novel photoelectric products.

Claims

1. Optical glass, characterized in that it comprises, in percentages by weight: SiO 2₂：6-16％；B₂O₃：5-15％；La₂O₃：25-32％；TiO₂：15-30％；Nb₂O₅：5-15％；ZrO₂: 1 to 15 percent; BaO: 8-20% of SiO₂＞B₂O₃；La₂O₃/(SiO₂+B₂O₃) 1.0-2.0; the ratio of (ZnO + MgO + CaO + SrO)/BaO is 0.2-0.8.

2. The optical glass of claim 1, further comprising: gd (Gd)₂O₃：0-10％；Y₂O₃：0-10％；Yb₂O₃：0-10％；WO₃：0-5％；ZnO：0-8％；MgO：0-5％；CaO：0-5％；SrO：0-5％；Ta₂O₅：0-5％；Al₂O₃：0-5％；Sb₂O₃：0-1％。

3. Optical glass is characterized by comprising the following components in percentage by weight: SiO 2₂：6-16％；B₂O₃：5-15％；La₂O₃：25-32％；TiO₂：15-30％；Nb₂O₅：5-15％；ZrO₂：1-15％；BaO：8-20％；Gd₂O₃：0-10％；Y₂O₃：0-10％；Yb₂O₃：0-10％；WO₃：0-5％；ZnO：0-8％；MgO：0-5％；CaO：0-5％；SrO：0-5％；Ta₂O₅：0-5％；Al₂O₃：0-5％；Sb₂O₃: 0-1% of SiO₂＞B₂O₃；La₂O₃/(SiO₂+B₂O₃) 1.0-2.0; the ratio of (ZnO + MgO + CaO + SrO)/BaO is 0.2-0.8.

4. The optical glass of any one of claims 1-3, wherein: SiO 2₂: 6 to 12 percent; and/or B₂O₃: 5 to 10 percent; and/or La₂O₃: 27 to 32 percent; and/or TiO₂: 17 to 27 percent; and &Or Nb₂O₅: 8 to 13 percent; and/or ZrO₂: 3 to 12 percent; and/or BaO: 10 to 18 percent; and/or Gd₂O₃: 0 to 5 percent; and/or Y₂O₃: 0 to 5 percent; and/or Yb₂O₃: 0 to 5 percent; and/or WO₃: 0 to 2 percent; and/or ZnO: 0 to 5 percent; and/or MgO: 0 to 2 percent; and/or CaO: 0 to 2 percent; and/or SrO: 0 to 2 percent; and/or Ta₂O₅: 0 to 2 percent; and/or Al₂O₃: 0 to 3 percent; and/or Sb₂O₃：0-0.5％。

5. An optical glass according to any of claims 1 to 3, wherein the content of each component satisfies one or more of the following 3 conditions:

1)La₂O₃/(SiO₂+B₂O₃) 1.2-2.0;

2)TiO₂/(Nb₂O₅+ZrO₂+WO₃) 0.8-2.0:

3)TiO₂the ratio of/BaO is 1.0-2.5.

6. An optical glass according to any of claims 1 to 3, wherein the content of each component satisfies one or more of the following 4 cases:

1)La₂O₃/(SiO₂+B₂O₃) 1.3-2.0;

2)TiO₂/(Nb₂O₅+ZrO₂+WO₃) 0.9-1.5:

3) (ZnO + MgO + CaO + SrO)/BaO is 0.2-0.5:

4)TiO₂the ratio of/BaO is 1.3-2.3.

7. An optical glass according to claim 1 or 2, characterised in that it further comprises, in percentages by weight: p₂O₅：0-5％；Bi₂O₃：0-5％；Ga₂O₃:0-5％；Lu₂O₃:0-5％；GeO₂：0-5％；CeO₂：0-0.5％；SnO₂：0-0.5％；F：0-5％。

8. An optical glass according to any one of claims 1 to 7, wherein the optical glass has a refractive index nd of 1.95 or more and an Abbe number vd of 22 to 30.

9. The optical glass according to any one of claims 1 to 7, wherein the optical glass has a density p of 5.00g/cm³The following; hardness H_KIs 620 multiplied by 10⁷Pa is above; the transition temperature Tg is 690 ℃ or less.

10. The optical glass of any one of claims 1 to 7, wherein the optical glass powder process has a water stability D_WIs of type 1; acid stability by powder Process D_AIs type 1.

11. A glass preform made of the optical glass according to any one of claims 1 to 10.

12. An optical element made of the optical glass according to any one of claims 1 to 10.